1,497 research outputs found
Saturation properties of nuclear matter in a relativistic mean field model constrained by quark dynamics
We have built an effective Walecka-type hadronic Lagrangian in which the
hadron masses and the density dependence of the coupling constants are deduced
from the quark dynamics using a Nambu-Jona-Lasinio model. The parameters of
this Nambu-Jona-Lasinio model have been determined using the meson properties
in the vacuum but also in the medium through the omega meson mass in nuclei
measured by the TAPS collaboration. Realistic properties of nuclear matter have
been obtained.Comment: 4 pages, 1 figure, to appear in the Proceedings of "Quark Confinement
and the Hadron Spectrum VII
Auxiliary homotransplantation of the canine liver with the use of a "reverse" Welch technique.
Reflexiones sobre el conocimiento lingüístico declarado por los escolares catalanes al final de la Educación Secundaria Obligatoria
A finales de 2008, la Generalitat de Cataluña
dio a conocer los datos de un estudio que ha reabierto
el eterno debate sobre las competencias lingüísticas
de los escolares catalanes.
A partir de este documento, el trabajo persigue un análisis
de las informaciones más relevantes en lo relativo
a las habilidades lingüísticas declaradas, haciendo hincapié
en algunos de los grandes retos del Sistema Educativo:
mejora de los niveles de conocimiento de catalán,
castellano y lenguas extranjeras, y la búsqueda de
una mayor equidad entre escolares autóctonos e inmigrantes
en el acceso a las lenguas de la escuela
Dynamic force spectroscopy of DNA hairpins. II. Irreversibility and dissipation
We investigate irreversibility and dissipation in single molecules that
cooperatively fold/unfold in a two state manner under the action of mechanical
force. We apply path thermodynamics to derive analytical expressions for the
average dissipated work and the average hopping number in two state systems. It
is shown how these quantities only depend on two parameters that characterize
the folding/unfolding kinetics of the molecule: the fragility and the
coexistence hopping rate. The latter has to be rescaled to take into account
the appropriate experimental setup. Finally we carry out pulling experiments
with optical tweezers in a specifically designed DNA hairpin that shows
two-state cooperative folding. We then use these experimental results to
validate our theoretical predictions.Comment: 28 pages, 12 figure
Birds from sima del elefante, atapuerca, spain: Palaeoecological implications in the oldest human bearing levels of the iberian peninsula
Palaeoenvironmental reconstruction of Early Pleistocene sites has a particular interest as it sheds light on how the arriving of the first Europeans occurred, as well as on the nature of the relation between these humans and the ecosystems. Bird remains are useful tools for this purpose, because they are commonly represented in the assemblages and most taxa still exist, allowing a direct comparison between past and extant birds associations. Here we analyse the bird remains from the Early Pleistocene levels of the Sima del Elefante site (1.1 to 1.5 million years old). Almost 10.000 remains belonging to at least 26 different taxa have been included. The assemblage is dominated by corvids and has a mixed origin, with cave-dwelling taxa dying in the cave and other taxa being accumulated by predators. The Sima del Elefante avian assemblage provides the oldest record of several taxa in the Iberian Peninsula (Haliaeetus albicilla, Corvus pliocaenus). Besides, here we report the oldest evidence of Imperial Eagle in the Iberian Peninsula, prior to the separation of the oriental and Iberian populations. The assemblage composition suggests that open environmental conditions were dominant, with minor presence of woodlands and water bodies, which is congruent with some previous approaches by other proxies. The first humans occupying the Iberian Peninsula inhabited under Mediterranean climate conditions, which gradually deteriorated, as reflected by the avian turnover recorded at the middle Pleistocene Atapuerca assemblages. © 2021 Universita degli Studi di Milano. All rights reserved
“Clip-Stone” Filiation Within the Biliary Tract
A case of cholangitis due to the migration of a metal clip used for surgical cholecystectomy 4 years
earlier, is reported. The diagnostic approach and therapeutic options, either endoscopic or surgical are
discussed. The use of resorbable clips during the performance of laparoscopic cholecystectomy should
avoid this type of complication
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