83 research outputs found
The HADES Program with HARPS-N@TNG - HADES: THE HArps-n red Dwarf Exoplanet Survey
No full textWe present the complete analysis of the Harps-n Dwarf Exoplanet Survey (HADES), which monitored the radial velocity variations of a large sample of M dwarfs, with HARPS-N@TNG, over the last 10 years, to determine the rate of occurrence of small planets around low-mass stars. M dwarfs are attractive targets for planet searches because they represent the shortest route to detecting potentially habitable planets. We paid particular attention to radial velocity jitter levels induced by stellar activity, to rule out radial velocity variations due to astrophysical noise as Keplerian signals. In particular, the analysis of spectral indices based on Ca II H & K and Hα lines enables us to highlight periods due to chromospheric inhomogeneities modulated by stellar rotation and differential rotation. The HADES (HARPS-N Red Dwarf Exoplanet Survey Radial Velocity) project is the result of a collaborative effort between the GAPS Consortium, the Institut de Ciències de l’Espai de Catalunya (ICE), and the Instituto de Astrofísica de Canarias (IAC)
The HADES Program with HARPS-N@TNG. HADES: THE HArps-n red Dwarf Exoplanet Survey
No full textMany efforts to detect Earth-like planets around low-mass stars are currently devoted to almost every extra-solar planet search. M dwarfs stand as ideal targets for Doppler radial velocity searches as their low masses and luminosities make low-mass planets orbiting within their habitable zones more easily detectable than those around higher-mass stars. Nonetheless, the statistics of the frequency of this kind of planet hosted by low-mass stars remains poorly constrained.
Our M-dwarf radial velocity monitoring with HARPS-N within the HARPS-N Red Dwarf Exoplanet Survey Radial Velocity (HADES) project started in 2012 and is contributing to the widening of the current statistics through the in-depth analysis of accurate radial velocity observations in a narrow range of spectral sub-types from M0 to M3, to investigate the planetary population around a well-defined class of host stars.
The HADES project is the result of a collaborative effort between the Italian Global Architecture of Planetary Systems (GAPS) Consortium, the Institut de Ciències de l’Espai de Catalunya (ICE), and the Instituto de Astrofísica de Canarias (IAC)
Genetic changes in the development of multiple myeloma
No full textMultiple myeloma (MM) is a malignancy of clonal plasma cells (PC) which develops as a consequence of a multistep process of transformation from a normal PC to an asymptomatic stage known as monoclonal gammopathy of undetermined significance (MGUS) to MM to the more aggressive plasma cell leukaemia (PCL). MGUS is the most common PC disorder and the majority of cases never progress to MM requiring treatment, as progression only occurs in ~1% of patients per year. From a genetic point of view, specific abnormalities represent initiating events (i.e. IgH translocations or hyperdiploidy) of this multistep process while others occur at later stages. In this study, interphase-FISH showed that initiating events are present in MGUS (n=187) and asymptomatic MM (SMM, n=128) at similar frequencies as found in MM (n=400) (the only exception was t(4;14)) and showed that these abnormalities alone, regardless of their biological impact in MM, cannot drive progression to overt disease. The time of occurrence of deletion/monosomy of chromosome 13 (13) was found to depend on the presence of specific concurrent abnormalities. 13 was extremely rare in MGUS and SMM with translocations directly involving CCND1 and CCND3 suggesting a possible role of 13 in the progression of disease specifically in these genetic sub-groups. However, it was clear that, excluding 13 in these sub-groups, standard interphase-FISH abnormalities are insufficient to predict progression of MGUS and SMM. High resolution array CGH showed an increasing level of genomic complexity from MGUS (n=25) to SMM (n=15) to MM (n=47) to PCL (n=11). In MGUS, the number of copy number changes per case was highly associated with progression (P=0.003). The simplest profiles belonged to MGUS cases with t(11;14) and t(14;20); surprisingly, none of these patients had progressed to MM by the end of this study (median follow-up=72 months). The integration of results from interphase-FISH, array CGH and metaphase analysis suggested that there were various abnormalities (corresponding to distinct molecular pathways) responsible for disease progression. A number of chromosomal changes were found to be strongly associated with progression (del(1)(p22.3-p23); del(6)(q25), MYC changes, del(12)(p13), 13 in t(11;14), abnormalities involving members of the NF-B pathway, del(17)(p13)). Such associations were not only suggested by the fact that these abnormalities were rare in MGUS/SMM compared to MM, but also by the observation that all pre-malignant patients positive for these changes progressed to overt disease. However, among patients who did progress and carried the same abnormalities, time to progression was found to be highly variable from case to case. This suggested that other factors (genetic or otherwise) must be interacting with chromosomal abnormalities in order to lead to progression. Other changes, e.g. 1q21 gain, despite being rare in pre-malignant cases compared to MM and despite some being associated with a dismal prognosis in MM, did not appear to be linked to rapid progression. This study has made significant progress towards understanding the progression from pre-malignant disease to MM, which will provide information towards potential novel targets for therapy to prevent progression or prolong the pre-malignant phase of a highly aggressive diseas
After Y2K: Time, Andre the giant and other democratic avatar
No full textJesus said-
And the New Year arrived. The New Millenium. Just another day in a lifetime of similar days. But each one of them crowded with possibility. The possibility of disaster, the possibility of perfection ... What would become of them? I wondered. In another hundred years would they all be born in test tubes or perhaps evolve through computers to become groups of disembodied digitised intelligence machines . . . In a hundred years would they be living on other planets? Would the Earth still exist? Would they engineer themselves genetically so that disease was a thing of the past? Would they all become just one big multi-ethnic race? Will they discover the secret of the universe? ... Will they all speak the same language in the future? Will they make love? Maybe there will be more than two sexes. Will they still believe life is sacred? Will it matter? Do we matter? (Hal Hartley, The Book of Life, Fr. 2000)
Stellar masks and bisector's shape for M-type stars observed in the GAPS programme with HARPS-N at TNG
No full textThe HARPS/HARPS-N Data Reduction Software (DRS) relies on the cross-correlation between the observed spectra and a suitable stellar mask to compute a cross-correlation function (CCF) to be used both for the radial velocity (RV) computation and as an indicator of stellar lines asymmetry, induced for example by the stellar activity. Unfortunately the M2 mask currently used by the HARPS/HARPS-N DRS for M-type stars results in heavily distorted CCFs. We created several new stellar masks in order to decrease the errors in the RVs and to improve the reliability of the activity indicators as the bisector’s span. We obtained very good results with a stellar mask created from the theoretical line list provided by the VALD3 database for an early M-type star (Teff= 3500 K and log g= 4.5). The CCF’s shape and relative activity indicators improved and the RV time-series allowed us to recover known exoplanets with periods and amplitudes compatible with the results obtained with HARPS-TERRA
SUNRISES AND SUNSETS AT KOGAION
No full textProposing a differentiation between the utensils (with the results) of the "classical" archaeology and the wide affer for a be
tter research by a cooperation with the pluridisciplinary research, the author exemplifies with some outcomes from his own
research (or in a team with different specialities), at the Dacian Sanctuaries from Dealul Gradiste ( "Sarmizegethusa Regia"). The results, says the author, could not be acquired by
the archaeologists, not only because of their utensils, but essentially because the horizon of research is too large, asking for analysis by many sciences and branches of kowledge in
which, usually, the archaeologist is not trainned.
Former archaeological research concluded that at "Sarmizegethusa Regia" was a fortress and a "Dacian Capital", conclusions which are firmly refuted by the pluridi
sciplinary investigation. In change, is ignored many evidence which can confirm that at Dealul Gradiste-Muntele Godeanu was
the legendary KOGAION mentioned by Strabo
The Kepler-454 system : A small, not-rocky inner planet, a Jovian world, and a distant companion
No full textKepler-454 (KOI-273) is a relatively bright (V = 11.69 mag), Sun-like starthat hosts a transiting planet candidate in a 10.6 d orbit. From spectroscopy, we estimate the stellar temperature to be 5687 +/- 50 K, its metallicity to be [m/H] = 0.32 +/- 0.08, and the projected rotational velocity to be v sin i 10 years and mass >12.1M_J . The twelve exoplanets with radii <2.7 R_Earth and precise mass measurements appear to fall into two populations, with those <1.6 R_Earth following an Earth-like composition curve and larger planets requiring a significant fraction of volatiles. With a density of 2.76 +/- 0.73 g cm-3, Kepler-454b lies near the mass transition between these two populations and requires the presence of volatiles and/or H/He gas.Peer reviewe
Human-Mechanical system interaction in Virtual Reality
No full textThe present work aims to show the great potential of Virtual Reality (VR) technologies in the field of Human-Robot Interaction (HRI).
Indeed, it is foreseeable that in not too distant future cooperating robots will be increasingly present in human environments.
Many authors actually believe that after the current information revolution, we will witness the so-called "robotics revolution", with the spread of increasingly intelligent and autonomous robots capable of moving into our own environments.
Since these machines must be able to interact with human beings in a safe way, new design tools for the study of Human-Robot Interaction (HRI) are needed. The author believes that VR is an ideal design tool for the study of the interaction between humans and automatic machines, since it allows the designers to interact in real-time with virtual robotic systems and to evaluate different control algorithms, without the need of physical prototypes. This also shields the user from any risk related to the physical experimentation.
However, VR technologies have also a more immediate application in the field of HRI, such as the study of usability of interfaces for real-time controlled robots. In fact, these robots, such as robots for microsurgery or even "teleoperated" robots working in a hostile environments, are already quite common. VR allows the designers to evaluate the usability of such interfaces by relating their physical input with a virtual output.
In particular, the author has developed a new software application aimed at simulating automatic robots and, more generally, mechanical systems in a virtual environment. The user can interact with one or more virtual manipulators and also control them in real-time by means of several input devices.
Finally, an innovative approach to the modeling and control of a humanoid robot with high degree of redundancy is discussed.
VR implementation of a virtual humanoid is useful for the study of both humanoid robots and human beings
The mass of Kepler-93b and the composition of terrestrial planets
No full textKepler-93b is a 1.478 ± 0.019 R ⊕ planet with a 4.7 day period around a bright (V = 10.2), astroseismically characterized host star with a mass of 0.911 ± 0.033 M ☉ and a radius of 0.919 ± 0.011 R ☉. Based on 86 radial velocity observations obtained with the HARPS-N spectrograph on the Telescopio Nazionale Galileo and 32 archival Keck/HIRES observations, we present a precise mass estimate of 4.02 ± 0.68 M ⊕. The corresponding high density of 6.88 ± 1.18 g cm–3 is consistent with a rocky composition of primarily iron and magnesium silicate. We compare Kepler-93b to other dense planets with well-constrained parameters and find that between 1 and 6 M ⊕, all dense planets including the Earth and Venus are well-described by the same fixed ratio of iron to magnesium silicate. There are as of yet no examples of such planets with masses >6 M ⊕. All known planets in this mass regime have lower densities requiring significant fractions of volatiles or H/He gas. We also constrain the mass and period of the outer companion in the Kepler-93 system from the long-term radial velocity trend and archival adaptive optics images. As the sample of dense planets with well-constrained masses and radii continues to grow, we will be able to test whether the fixed compositional model found for the seven dense planets considered in this paper extends to the full population of 1-6 M ⊕ planets.Peer reviewe
CSI 2264: Simultaneous optical and infrared light curves of young disk-bearing stars in NGC 2264 with CoRoT and Spitzer-- evidence for multiple origins of variability
No full textWe present the Coordinated Synoptic Investigation of NGC 2264, a continuous 30-day multi-wavelength photometric monitoring campaign on more than 1000 young cluster members using 16 telescopes. The unprecedented combination of multi-wavelength, high-precision, high-cadence, and long-duration data opens a new window into the time domain behavior of young stellar objects. Here we provide an overview of the observations, focusing on results from Spitzer and CoRoT. The highlight of this work is detailed analysis of 162 classical T Tauri stars for which we can probe optical and mid-infrared flux variations to 1% amplitudes and sub-hour timescales. We present a morphological variability census and then use metrics of periodicity, stochasticity, and symmetry to statistically separate the light curves into seven distinct classes, which we suggest represent different physical processes and geometric effects. We provide distributions of the characteristic timescales and amplitudes, and assess the fractional representation within each class. The largest category (>20%) are optical "dippers" having discrete fading events lasting ~1-5 days. The degree of correlation between the optical and infrared light curves is positive but weak; notably, the independently assigned optical and infrared morphology classes tend to be different for the same object. Assessment of flux variation behavior with respect to (circum)stellar properties reveals correlations of variability parameters with H emission and with effective temperature. Overall, our results point to multiple origins of young star variability, including circumstellar obscuration events, hot spots on the star and/or disk, accretion bursts, and rapid structural changes in the inner disk
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