296 research outputs found
Trace fossils on a trace fossil: A vertebrate-bitten vertebrate coprolite from the miocene of Italy
Despite their long history of discoveries and research, of all the vertebrate coprolites currently known worldwide, only a very few have been explicitly recognised as exhibiting bite marks by other vertebrates. These rare specimens represent “compound ichnofossils”, i.e., trace fossils (the lithifie faeces) on which other trace fossils (the tooth incisions) are present. Here we report on an unusual large-sized coprolite from the Miocene “Pietra leccese” formation of southern Italy that displays several superficia bite marks. This specimen is described, f gured, and chemically characterised by means of hand-held energy dispersive X-ray f uorescence – the firs application of this method to the analysis of a vertebrate coprolite. Based on its size, morphology, structure, and major-element composition, the Pietra leccese coprolite is here identifie as the fossilised excreta of a large carnivorous vertebrate, possibly a shark, whereas the tooth incisions are attributed to the biting action of indeterminate f sh, likely including both bony and cartilaginous fish Biting seemingly occurred prior to the eventual deposition of the scat at the seafl or (i.e., when it was still in the water column) and probably ref ects unintentional snagging or aborted exploratory coprophagy aimed at testing the palatability of the faeces. In conclusion, the highly idiosyncratic specimen described in this paper represents a significa t addition to the overly scanty record of vertebrate-bitten vertebrate coprolites and provides an unusual window on the ecological interactions between marine vertebrates in the Miocene central Mediterranean ecosystems witnessed by the remarkable fossil assemblage of the Pietra leccese
Caracterização e seleção de genĂłtipos agronomicamente superiores de morangueiro com base no inter-relacionamento de caracterĂsticas de importância agronĂ´mica.
Dissertação (Mestrado em Produção Vegetal) - Universidade do Estado de Santa Catarina. Programa de PĂłs-Graduação em CiĂŞncias Agrárias, Lages, SC. 2016, Orientador: Jefferson LuĂs Meirelles Coimbra, Co-orientador: Sandro Bonow
Implementation of an elasto-viscoplastic constitutive law in Abaqus/Standard for an improved characterization of rock materials
Subsidence modeling is an important activity in the oil and gas industry, for the environmental and operational implications associated to this phenomenon. Abaqus/Standard has been used for many years in Eni as the main numerical simulator for studying the geomechanical behavior of reservoirs. The results of a large campaign of acquisition of subsidence monitoring data in conjunction with the advanced analysis of laboratory experiments have shown that, in some cases, an improved mechanical characterization can be tailored to better capture the complex behavior of the reservoir rock under the effect of underground fluid withdrawal. In this work we first present an implementation in Abaqus/Standard of an elasto-viscoplastic model – namely the Vermeer and Neher model – as user defined material by means of the UMAT subroutine. Next, we provide the results of various simulations of laboratory tests that were performed to investigate its capability to identify the main features of the behavior of reservoir sands, also including time dependency. Finally, we show a preliminary application to a synthetic, nonetheless realistic, reservoir model that has been performed to assess the capabilities of the elasto-viscoplastic model in the simulation of subsidence evolution
Elasto-viscoplastic modeling of subsidence above gas fields in the Adriatic Sea
Abstract. From the analysis of GPS monitoring data collected above gas
fields in the Adriatic Sea, in a few cases subsidence responses have been
observed not to directly correlate with the production trend. Such behavior,
already described in the literature, may be due to several physical
phenomena, ranging from simple delayed aquifer depletion to a much more
complex time-dependent mechanical response of subsurface geomaterials to
fluid withdrawal. In order to accurately reproduce it and therefore to be
able to provide reliable forecasts, in the last years Eni has enriched its
3D finite element geomechanical modeling workflow by adopting an advanced
constitutive model (Vermeer and Neher, 1999), which also considers the
viscous component of the deformation. While the numerical implementation of
such methodology has already been validated at laboratory scale and tested
on synthetic hydrocarbon fields, the work herein presents its first
application to a real gas field in the Adriatic Sea where the phenomenon has
been observed. The results show that the model is capable to reproduce very
accurately both GPS data and other available measurements. It is worth
remarking that initial runs, characterized by the use of model parameter
values directly obtained from the interpretation of mechanical laboratory
tests, already provided very good results and only minor tuning operations
have been required to perfect the model outcomes. Ongoing R&D projects
are focused on a regional scale characterization of the Adriatic Sea basin
in the framework of the Vermeer and Neher model approach
A previously unreported function of beta1B integrin isoform in caspase-8-dependent integrin-mediated keratinocyte death
Integrins regulate adhesive cell-matrix interactions and mediate survival signals. On the other hand, unligated or free cytoplasmic fragments of integrins induce apoptosis in many cell types (integrin-mediated death). We have previously shown that b1 integrins expression protects keratinocyte stem cells from anoikis, while the role of the b1B integrin isoform has never been clarified. Here we report that suspended keratinocytes undergo apoptosis via the activation of caspase-8, independently of Fas/Fas Ligand system. Indeed, anti-b1 integrin neutralizing antibodies induced apoptosis in short-hairpin-RNA-Fas-Associated-Death-Domain treated cells. Moreover, before and during suspension, caspase-8 directly associated with b1 integrin, that in turn internalized and progressively degraded, shedding the cytoplasmic domain. b1B was expressed only in the cytoplasm in a perinuclear fashion and remained unaltered during suspension. At 24 hrs, as b1A located close to the nucleus, b1B co-localized with b1A and co-immunoprecipitated with caspase-8. Caspase-8 was activated earlier in b1B integrin transfected keratinocytes, and these cells underwent a higher rate of apoptosis than mock cells. By contrast, caspase-8 was not activated in siRNA b1B transfected cells. These results indicate that when b1A is unligated, b1B is responsible for “integrin-mediated death” in human keratinocytes
Incidentally discovered pheochromocytoma and aldosterone-producing adenoma in the same adrenal gland
Simultaneous occurrence of pheochromocytoma and aldosterone-producing adrenocortical tumor has been rarely reported in patients with symptoms or findings suggestive for both neoplasms. Herein, we report and discuss on a challenging case of synchronous pheochromocytoma and aldosterone-producing adenoma incidentally detected in the same adrenal gland and documented by biochemical studies and pathological examination
Controle de corda-de-viola com as opções de tratamentos herbicidas disponĂveis para a cultura do algodĂŁo.
Glaciovolcanic evidence for a polythermal Neogene East Antarctic Ice Sheet
A paradigm has existed for more than 30 years that the basal
thermal regime of the East Antarctic Ice Sheet in Victoria Land made
a fundamental transition from wet-based to cold-based either at
ca. 14 Ma or after ca. 2.5 Ma. The basal thermal regime is important
because it determines the potential for unstable behavior in an ice
sheet. We have studied the environmental characteristics of subglacially
erupted volcanic centers scattered along 800 km of the Ross Sea
fl ank of the Transantarctic Mountains. The volcanoes preserve evidence
for the coeval paleo-ice thicknesses and contain features diagnostic
of both wet-based and cold-based ice conditions. By dating the
sequences we are able to demonstrate that the basal thermal regime
varied spatially and with time between ca. 12 Ma and present. It was
polythermal overall and probably comprised a coarse temperature
patchwork of frozen-bed and thawed-bed ice, similar to the East Antarctic
Ice Sheet today. Thus, an important shift is required in the prevailing
paradigm describing its temporal evolution
Relativistic theory of elastic deformable astronomical bodies: perturbation equations in rotating spherical coordinates and junction conditions
In this paper, the dynamical equations and junction conditions at the
interface between adjacent layers of different elastic properties for an
elastic deformable astronomical body in the first post-Newtonian approximation
of Einstein theory of gravity are discussed in both rotating Cartesian
coordinates and rotating spherical coordinates. The unperturbed rotating body
(the ground state) is described as uniformly rotating, stationary and
axisymmetric configuration in an asymptotically flat space-time manifold.
Deviations from the equilibrium configuration are described by means of a
displacement field. In terms of the formalism of relativistic celestial
mechanics developed by Damour, Soffel and Xu, and the framework established by
Carter and Quintana the post Newtonian equations of the displacement field and
the symmetric trace-free shear tensor are obtained. Corresponding
post-Newtonian junction conditions at interfaces also the outer surface
boundary conditions are presented. The PN junction condition is an extension of
Wahr's one which is a Newtonian junction conditions without rotating.Comment: Revtex4, 14 page
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