9,340 research outputs found
Impact of Saturn's rings on mission analysis for MJS 77
Mariner Jupiter-Saturn '77 mission objectives for Saturn are considered which affect the trajectory design and in particular the aim point at Saturn. These objectives include the following: (1) earth, sun occulation of Saturn, rings, and satellites; (2) close as possible to surface; (3) close as possible to rings; (4) close encounter with Titan (approximately 20,000 km); (5) close encounter with lapetus; (6) multiple satellite encounters; (7) post-Saturn trajectory to Uranus; and (8) post-Saturn trajectory toward solar apex
The archaeological settlement of Monte Bibele (Bologna)
Monte Bibele is an archaeological settlement of the 4th and 3rd century BC with a village, a necropolis and a votive deposit. Earlier, during the 14th and 13th century BC, in the same area there was a small village of sub-Apennine facies attributable to the late Bronze Age. The Second Iron Age settlement is just a part of a larger demographic reorganization of the Apennines, as is also proved by the recent discovery of the Monterenzio Vecchio necropolis and votive deposit, on the opposite side of Idice Valley. These are small settlements located close to the main routes of both sides of the Apennines and populated by Italic (Etruscans, Umbrians, Ligurians, etc.) and transalpine peoples (Celts) allied to control the surroundings. Of the architectural structures of Monte Bibele, the best known are those of the village, in the part of the massive called ‘Pianella di Monte Savino’. It has an Etruscan foundation, over an area of about 7,000 m2, in part still to be explored, and documented in its final phase in the late 3rd century BC, when the village was sealed by a sudden fire. Archaeologists of Te.M.P.L.A. (Research Center for Multimedia Technologies Applied to Archaeology of Bologna University’s Department of History and Cultures) over the last decade, have made many models of houses at Pianella. Reconstructions are based on direct feedbacks (archaeological data) and indirect comparisons (historical sources, traditional architecture). The first model was virtual, followed by a real one made near the Museum of Monterenzio, and by the two new houses made directly in situ, thanks to EU funds for the development of Emilia Romagna used for renovating the archaeological and naturalistic area of Monte Bibele (Por Fesr 2007/2013)
Fear Conditioning Potentiates Synaptic Transmission onto Long-Range Projection Neurons in the Lateral Subdivision of Central Amygdala
Recent studies indicate that the lateral subdivision of the central amygdala (CeL) is essential for fear learning. Specifically, fear conditioning induces cell-type-specific synaptic plasticity in CeL neurons that is required for the storage of fear memories. The CeL also controls fear expression by gating the activity of the medial subdivision of the central amygdala (CeM), the canonical amygdala output to areas that mediate defensive responses. In addition to the connection with CeM, the CeL sends long-range projections to innervate extra-amygdala areas. However, the long-range projection CeL neurons have not been well characterized, and their role in fear regulation is unknown. Here we show in mice that a subset of CeL neurons directly project to the midbrain periaqueductal gray (PAG) and the paraventricular nucleus of the thalamus, two brain areas implicated in defensive behavior. These long-range projection CeL neurons are predominantly somatostatin-positive (SOM(+)) neurons, which can directly inhibit PAG neurons, and some of which innervate both the PAG and paraventricular nucleus of the thalamus. Notably, fear conditioning potentiates excitatory synaptic transmission onto these long-range projection CeL neurons. Thus, our study identifies a subpopulation of SOM(+) CeL neurons that may contribute to fear learning and regulate fear expression independent of CeM
NIHAO project II: Halo shape, phase-space density and velocity distribution of dark matter in galaxy formation simulations
We use the NIHAO (Numerical Investigation of Hundred Astrophysical Objects)
cosmological simulations to study the effects of galaxy formation on key
properties of dark matter (DM) haloes. NIHAO consists of
high-resolution SPH simulations that include (metal-line) cooling, star
formation, and feedback from massive stars and SuperNovae, and cover a wide
stellar and halo mass range: ( ). When compared to DM-only simulations,
the NIHAO haloes have similar shapes at the virial radius, R_{\rm vir}, but are
substantially rounder inside . In NIHAO simulations
increases with halo mass and integrated star formation efficiency,
reaching at the Milky Way mass (compared to 0.5 in DM-only),
providing a plausible solution to the long-standing conflict between
observations and DM-only simulations. The radial profile of the phase-space
parameter () is best fit with a single power law in DM-only
simulations, but shows a flattening within for NIHAO
for total masses . Finally, the global velocity
distribution of DM is similar in both DM-only and NIHAO simulations, but in the
solar neighborhood, NIHAO galaxies deviate substantially from Maxwellian. The
distribution is more symmetric, roughly Gaussian, with a peak that shifts to
higher velocities for Milky Way mass haloes. We provide the distribution
parameters which can be used for predictions for direct DM detection
experiments. Our results underline the ability of the galaxy formation
processes to modify the properties of dark matter haloes.Comment: 19 pages, 17 figures, analysis strongly improved, main conclusions
unchanged, accepted for publication in MNRA
NIHAO IV: Core creation and destruction in dark matter density profiles across cosmic time
We use the NIHAO simulations to investigate the effects of baryonic physics
on the time evolution of Dark Matter central density profiles. The sample is
made of independent high resolution hydrodynamical simulations of
galaxy formation and covers a wide mass range: 1e10< Mhalo <1e12, i.e., from
dwarfs to L* . We confirm previous results on the dependence of the inner dark
matter density slope, , on the ratio between stellar-to-halo mass. We
show that this relation holds approximately at all redshifts (with an intrinsic
scatter of ~0.18 in ). This implies that in practically all haloes the
shape of their inner density profile changes quite substantially over cosmic
time, as they grow in stellar and total mass. Thus, depending on their final
stellar-to-halo mass ratio, haloes can either form and keep a substantial
density core (size~1 kpc), or form and then destroy the core and re-contract
the halo, going back to a cuspy profile, which is even steeper than CDM
predictions for massive galaxies (~1e12 Msun). We show that results from the
NIHAO suite are in good agreement with recent observational measurements of
in dwarf galaxies. Overall our results suggest that the notion of a
universal density profile for dark matter haloes is no longer valid in the
presence of galaxy formation.Comment: 11 pages, 13 figures. Corrected typo in table 2 (middle row) with
respect to the version published in MNRA
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