7,102 research outputs found

    Impact of Saturn's rings on mission analysis for MJS 77

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    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)

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    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

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    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

    Tethers in space handbook, second edition

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    The Tethers in Space Handbook, Second Edition represents an update to the initial volume issued in September 1986. As originally intended, this handbook is designed to serve as a reference manual for policy makers, program managers, educators, engineers, and scientists alike. It contains information for the uninitiated, providing insight into the fundamental behavior of tethers in space. For those familiar with space tethers, it includes a summary of past and ongoing studies and programs, a complete bibliography of tether publications, and names, addresses, and phone numbers of workers in the field. Perhaps its most valuable asset is the brief description of nearly 50 tether applications which have been proposed and analyzed over the past 10 years. The great variety of these applications, from energy generation to boosting satellites to gravity wave detection is an indication that tethers will play a significant part in the future of space development. This edition of the handbook preserves the major characteristics of the original; however, some significant rearrangements and additions have been made. The first section on Tether Programs has been brought up to date, and now includes a description of TSS-2, the aerodynamic NASA/Italian Space Agency (ASI) mission. Tether Applications follows, and this section has been substantially rearranged. First, the index and cross-reference for the applications have been simplified. Also, the categories have changed slightly, with Technology and Test changed to Aerodynamics, and the Constellations category removed. In reality, tether constellations may be applicable to many of the other categories, since it is simply a different way of using tethers. Finally, to separate out those applications which are obviously in the future, a Concepts category has been added. A new section included here on Conference Summaries recognizes the fact that the tether community is growing internationally, and that meetings provide a means of rapid communication and interaction. Finally, the Bibliography section has been considerably updated to include all known references. These are listed by author and by subject and include the papers to be presented at the Third International Conference in May 1989

    NIHAO project II: Halo shape, phase-space density and velocity distribution of dark matter in galaxy formation simulations

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    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 90\simeq 90 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: 106<M/M<101110^6 < M_* / M_{\odot} < 10^{11} ( 109.5<Mhalo/M<1012.510^{9.5} < M_{\rm halo} / M_{\odot} < 10^{12.5}). When compared to DM-only simulations, the NIHAO haloes have similar shapes at the virial radius, R_{\rm vir}, but are substantially rounder inside 0.1Rvir\simeq 0.1R_{\rm vir}. In NIHAO simulations c/ac/a increases with halo mass and integrated star formation efficiency, reaching 0.8\sim 0.8 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 QQ parameter (ρ/σ3\rho/\sigma^3) is best fit with a single power law in DM-only simulations, but shows a flattening within 0.1Rvir\simeq 0.1R_{\rm vir} for NIHAO for total masses M>1011MM>10^{11} M_{\odot}. 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
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