1,739 research outputs found
Famiglia e responsabilitÃ
The work traces the path that led to the development of civil
liability in family law. On one hand, it seems to share the idea of
strengthening the protection of the person in familiar group; on the other
hand, it focuses on the opportunity of leading, under certain circumstances,
the affection of non-pecuniary familiar interests to the breach of contract
La coroplastica votiva del santuario settentrionale di Pontecagnano
Excavations carried out in Pontecagnano nothern sanctuary area have brought to light more than
4000 votive terracottas. Installed during the VI century B.C in a suburban area – near a swamp, the
sanctuary was intentionally defuncionalized shortly before Picentia colony foundation. Statuette
fragments have been found into important votive deposits concentrated in specialised zones of
sacred area. For the sanctuary ‘disinauguration’ ritual, the terracottas have been diffusely discharged
in large quantities on the whole sanctuary surface, together with other votive categories and with
the Sanctuary furnishings.
The wide repertory, made up by 6th and 4th centuries B.C. evidences, has supplied some interesting
causes for reflection about sanctuary ritual peculiarities and about the local coroplastic industry
practices
Growth of asteroids, planetary embryos and Kuiper belt objects by chondrule accretion
Chondrules are millimeter-sized spherules that dominate primitive meteorites
(chondrites) originating from the asteroid belt. The incorporation of
chondrules into asteroidal bodies must be an important step in planet
formation, but the mechanism is not understood. We show that the main growth of
asteroids can result from gas-drag-assisted accretion of chondrules. The
largest planetesimals of a population with a characteristic radius of 100 km
undergo run-away accretion of chondrules within ~3 Myr, forming planetary
embryos up to Mars sizes along with smaller asteroids whose size distribution
matches that of main belt asteroids. The aerodynamical accretion leads to
size-sorting of chondrules consistent with chondrites. Accretion of mm-sized
chondrules and ice particles drives the growth of planetesimals beyond the ice
line as well, but the growth time increases above the disk life time outside of
25 AU. The contribution of direct planetesimal accretion to the growth of both
asteroids and Kuiper belt objects is minor. In contrast, planetesimal accretion
and chondrule accretion play more equal roles for the formation of Moon-sized
embryos in the terrestrial planet formation region. These embryos are isolated
from each other and accrete planetesimals only at a low rate. However, the
continued accretion of chondrules destabilizes the oligarchic configuration and
leads to the formation of Mars-sized embryos and terrestrial planets by a
combination of direct chondrule accretion and giant impacts.Comment: Accepted for publication in Science Advances (new AAAS journal
Observations of nitrogen isotope fractionation in deeply embedded protostars
(Abridged) The terrestrial planets, comets, and meteorites are significantly
enriched in 15N compared to the Sun and Jupiter. While the solar and jovian
nitrogen isotope ratio is believed to represent the composition of the
protosolar nebula, a still unidentified process has caused 15N-enrichment in
the solids. Several mechanisms have been proposed to explain the variations,
including chemical fractionation. However, observational results that constrain
the fractionation models are scarce. While there is evidence of 15N-enrichment
in prestellar cores, it is unclear how the signature evolves into the
protostellar phases. Our aim is to measure the 14N/15N ratio around three
nearby, embedded low-to-intermediate-mass protostars. Isotopologues of HCN and
HNC were used to probe the 14N/15N ratio. A selection of H13CN, HC15N, HN13C,
and H15NC transitions was observed with the APEX telescope. The 14N/15N ratios
were derived from the integrated intensities assuming a standard 12C/13C ratio.
The assumption of optically thin emission was verified using radiative transfer
modeling and hyperfine structure fitting. Two sources, IRAS 16293A and R CrA
IRS7B, show 15N-enrichment by a factor of around 1.5-2.5 in both HCN and HNC
with respect to the solar composition. Solar composition cannot be excluded for
the third source, OMC-3 MMS6. Furthermore, there are indications of a trend
toward increasing 14N/15N ratios with increasing outer envelope temperature.
The enhanced 15N abundances in HCN and HNC found in two Class~0 sources
(14N/15N of 160-290) and the tentative trend toward a temperature-dependent
14N/15N ratio are consistent with the chemical fractionation scenario, but
14N/15N ratios from additional tracers are indispensable for testing the
models. Spatially resolved observations are needed to distinguish between
chemical fractionation and isotope-selective photochemistry.Comment: Accepted for publication in Astronomy and Astrophysics. 16 pages, 13
figure
Lead isotope evidence for a young formation age of the Earth–Moon system
AbstractA model of a giant impact between two planetary bodies is widely accepted to account for the Earth–Moon system. Despite the importance of this event for understanding early Earth evolution and the inventory of Earth's volatiles critical to life, the timing of the impact is poorly constrained. We explore a data-based, two-stage Pb isotope evolution model in which the timing of the loss of volatile Pb relative to refractory U in the aftermath of the giant impact is faithfully recorded in the Pb isotopes of bulk silicate Earth. Constraining the first stage Pb isotopic evolution permits calculating an age range of 4.426–4.417 Ga for the inflection in the U/Pb ratio related to the giant impact. This model is supported by Pb isotope data for angrite meteorites that we use to demonstrate volatility-driven, planetary-scale Pb loss was an efficient process during the early Solar System. The revised age is ∼100 Myr younger than most current estimates for the age of the Moon but fully consistent with recent ages for lunar ferroan anorthosite and the timing of Earth's first crust inferred from the terrestrial zircon record. The estimated loss of ∼98% of terrestrial Pb relative to the Solar System bulk composition by the end of the Moon-forming process implies that the current inventory of Earth's most volatile elements, including water, arrived during post-impact veneering by volatile-rich bodies
Probing the Protosolar Disk Using Dust Filtering at Gaps in the Early Solar System
Jupiter and Saturn formed early, before the gas disk dispersed. The presence
of gap-opening planets affects the dynamics of the gas and embedded solids and
halts the inward drift of grains above a certain size. A drift barrier can
explain the absence of calcium aluminium rich inclusions (CAIs) in chondrites
originating from parent bodies that accreted in the inner solar system.
Employing an interdisciplinary approach, we use a -X-Ray-fluorescence
scanner to search for large CAIs and a scanning electron microscope to search
for small CAIs in the ordinary chondrite NWA 5697. We carry out long-term,
two-dimensional simulations including gas, dust, and planets to characterize
the transport of grains within the viscous -disk framework exploring
the scenarios of a stand-alone Jupiter, Jupiter and Saturn \textit{in situ}, or
Jupiter and Saturn in a 3:2 resonance. In each case, we find a critical grain
size above which drift is halted as a function of the physical conditions in
the disk. From the laboratory search we find four CAIs with a largest size of
200m. \Combining models and data, we provide an estimate for
the upper limit of the -viscosity and the surface density at the
location of Jupiter, using reasonable assumptions about the stellar accretion
rate during inward transport of CAIs, and assuming angular momentum transport
to happen exclusively through viscous effects. Moreover, we find that the
compound gap structure in the presence of Saturn in a 3:2 resonance favors
inward transport of grains larger than CAIs currently detected in ordinary
chondrites.Comment: 16 pages, 10 figures, updated to match published version in
Astrophysical Journa
Vibroacoustic performances of an acoustic box through hybrid FE-SEA method
VIBROACOUSTIC PERFORMANCES OF AN ACOUSTIC BOX THROUGH HYBRID FE-SEA METHO
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