196,201 research outputs found
Lithium synthesis around stellar mass black holes
No full textWe present a study of nucleosynthesis of light elements in the accretion disk of stellar mass black holes. The amount of both stable isotopes of lithium produced is sizeable for a host of values of black hole mass, disk viscosity and accretion rate. We discuss our results in the context of the lithium problem and propose observational tests for this mechanism
A quantitative approach in the treatment of hemiplegic patients using an electropneumatic platform
No full textExercise is the central feature in the rehabilitative treatment of hemiplegic patients. In cognitive rehabilitation, great importance is attributed to the recovery of a sufficient number of proprioceptive channels before expecting the patient to regain voluntary control. The PERM [Piattaforma (Platform), Elettropneumatica (Electropneumatic) per (for) Riabilitazione (Rehabilitation) Motoria (Motor)] is a new device that can be used in the treatment of the lower limbs to provide the patient with controlled and quantifiable mechanical stimuli, thus enabling the therapist to adopt a more rigourous approach to treatment even in the very early stages of rehabilitation. Alternatively, the system can be used in a different operating mode as a normal biofeedback system capable of displaying on-screen the extent to which voluntary load has been transferred to the lower limb. Exercise is the central feature in the rehabilitative treatment of hemiplegic patients. In cognitive rehabilitation, great importance is attributed to the recovery of a sufficient number of proprioceptive channels before expecting the patient to regain voluntary control. The PERM [Piattaforma (Platform), Elettropneumatica (Electropneumatic) per (for) Riabilitazione (Rehabilitation) Motoria (Motor)] is a new device that can be used in the treatment of the lower limbs to provide the patient with controlled and quantifiable mechanical stimuli, thus enabling the therapist to adopt a more rigorous approach to treatment even in the very early stages of rehabilitation. Alternatively, the system can be used in a different operating mode as a normal biofeedback system capable of displaying on-screen the extent to which voluntary load has been transferred to the lower limb
Mapping dark matter in the Milky Way, a synopsis
No full textMapping the dark matter distribution across our Galaxy represents a central challenge for the near future as a new generation of space-borne and ground-based astronomical surveys swiftly comes online. Here we present a synopsis of the present status of the field, reviewing briefly the baryonic content and the kinematics of the MilkyWay and outlining the methods used to infer the dark matter component. The discussion then proceeds with some of the latest developments based on our own work. In particular, we present a new compilation of kinematic measurements tracing the rotation curve of the Galaxy and an exhaustive array of observation-based baryonic models setting the contribution of stellar bulge, stellar disc and gas to the total gravitational potential. The discrepancy between these two components is then quantified to derive the latest constraints on the dark matter distribution and on modified Newtonian dynamics. We shall end with an overview of future directions to improve our mapping of the dark matter distribution in the Milky Way
An estimate of the DM profile in the Galactic bulge region
No full textWe present an analysis of the mass distribution in the region of the Galactic bulge, which leads to constraints on the total amount and distribution of Dark Matter (DM) therein. Our results – based on the dynamical measurement of the BRAVA collaboration – are quantitatively compatible with those of a recent analysis, and generalized to a vast sample of observationally inferred morphologies of the stellar components in the region of the Galactic bulge. By fitting the inferred DM mass to a generalized NFW profile, we find that cores (γ≲0.6) are forbidden only for very light configurations of the bulge, and that cusps (γ≳1.2) are allowed, but not necessarily preferred. Interestingly, we find that the results for the bulge region are compatible with those obtained with dynamical methods (based on the rotation curve) applied to outer regions of the Milky Way, for all morphologies adopted. We find that the uncertainty on the shape of the stellar morphology heavily affects the determination of the DM distribution in the bulge region, which is gravitationally dominated by baryons, adding up to the uncertainty on its normalization. The combination of the two hinders the actual possibility to infer sound conclusions about the distribution of DM in the region of the Galactic bulge, and only future observations of the stellar census and dynamics in this region will bring us closer to a quantitatively more definite answer
Lithium synthesis in microquasar accretion
No full textWe study the synthesis of lithium isotopes in the hot tori formed around stellar mass black holes by accretion of the companion star. We find that sizable amounts of both stable isotopes Li6 and Li7 can be produced, the exact figures varying with the characteristics of the torus and reaching as much as 10 -2MTM for each isotope. This mass output is enough to contaminate the entire Galaxy at a level comparable with the original, pregalactic amount of lithium and to overcome other sources such as cosmic-ray spallation or stellar nucleosynthesis. © 2012 American Physical Society
Declinazioni etiche dell'atto immaginativo. Husserl interprete di Hume
No full textNelle lezioni e nei manoscritti inediti degli anni 1917-1924, Husserl parla di “una valenza metodologica dell’immaginazione pura nelle valutazioni morali”; l’immaginazione è così una componente fondamentale per la sua definizione di coscienza morale [Gewissen], intesa come una serie di retrospezioni riflessive (considerate come le posizioni che l’io prende rispetto a se stesso). Si intende pertanto ricostruire il percorso attraverso il quale Husserl, criticando il tentativo di naturalizzazione della morale compiuto da Hume, chiarisce in che senso l’immaginazione sia una componente fondamentale per le valutazioni morali, mettendo in evidenza le implicazioni etiche dell’“osservatore disinteressato” a cui si arriva per mezzo di un atto di immaginazione
Self-annihilating dark matter and the CMB: Reionizing the universe and constraining cross sections
No full textI summarize the recent advances in determining the effects of self-ahhinilating WIMP dark matter on the modification of the recombination history, at times earlier than the formation of astrophysical objects. Depending on mass and self-annihilation cross section, WIMP DM can reproduce sizable amounts of the total free electron abundance at z≳6; as known, this affects the CMB temperature and polarization correlation spectra, and can be used to place stringent bounds in the particle mass vs cross-section plane. WMAP5 data already strongly disfavor the region capable to explain the recent positron anomaly in terms of DM annihilation, whereas in principle the Planck mission has the potential to see a signal produced by a candidate in that region, or from WIMPs with thermal annihilation cross-sections 〈σν〉∼ 3×10-26cm3/s and masses with values m κ≲50GeV/c2. © 2010 American Institute of Physics
galkin: A new compilation of Milky Way rotation curve data
No full textWe present galkin, a novel compilation of kinematic measurements tracing the rotation curve of our Galaxy together with a tool to treat the data. The compilation is optimised to Galactocentric radii between 3 and 20 kpc and includes the kinematics of gas, stars and masers in a total of 2780 measurements carefully collected from almost four decades of literature. A simple, user-friendly tool is provided to select, treat and retrieve the full database. Keywords: Dark matter, Galaxy: kinematics and dynamic
Trattamento Riabilitativo della Patologia dell’apparato locomotore con Tecniche di Biofeedback
No full textBiofeedback platform for the quantitative approch in the rehabilitation procedures of hemiplegic patients
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