University of Trento

About: University of Trento is a education organization based out in Trento, Italy. It is known for research contribution in the topics: Population & Large Hadron Collider. The organization has 10527 authors who have published 30978 publications receiving 896614 citations. The organization is also known as: Universitá degli Studi di Trento & Universita degli Studi di Trento.

A Unified Game-Theoretic Approach to Multiagent Reinforcement Learning

Abstract: To achieve general intelligence, agents must learn how to interact with others in a shared environment: this is the challenge of multiagent reinforcement learning (MARL). The simplest form is independent reinforcement learning (InRL), where each agent treats its experience as part of its (non-stationary) environment. In this paper, we first observe that policies learned using InRL can overfit to the other agents' policies during training, failing to sufficiently generalize during execution. We introduce a new metric, joint-policy correlation, to quantify this effect. We describe an algorithm for general MARL, based on approximate best responses to mixtures of policies generated using deep reinforcement learning, and empirical game-theoretic analysis to compute meta-strategies for policy selection. The algorithm generalizes previous ones such as InRL, iterated best response, double oracle, and fictitious play. Then, we present a scalable implementation which reduces the memory requirement using decoupled meta-solvers. Finally, we demonstrate the generality of the resulting policies in two partially observable settings: gridworld coordination games and poker.

Determining the oncological risk of autologous lipoaspirate grafting for post-mastectomy breast reconstruction.

Abstract: This study compares the incidence of local and regional recurrence of breast cancer between two contiguous time windows in a homogeneous population of 137 patients who underwent fat tissue transplant after modified radical mastectomy. Median follow-up time was 7.6 years and the follow-up period was divided into two contiguous time windows, the first starting at the date of the radical mastectomy and ending at the first lipoaspirate grafting session and the second beginning at the time of the first lipoaspirate grafting session and ending at the end of the total follow-up time. Although this study did not employ an independent control group, the incidence of local recurrence of breast cancer was found to be comparable between the two periods and in line with data from similar patient populations enrolled in large multicenter clinical trials and who did not undergo postsurgical fat tissue grafting. Statistical comparison of disease-free survival curves revealed no significant differences in relapse rate between the two patient subgroups before fat grafting and after fat grafting. Although further confirmation is needed from multicenter randomized clinical trials, our results support the hypothesis that autologous lipoaspirate transplant combines striking regenerative properties with no or marginal effects on the probability of post-mastectomy locoregional recurrence of breast cancer.

Mechanical Characterization of Sol–Gel‐Derived Silicon Oxycarbide Glasses

Abstract: Silicon oxycarbide glasses have been fabricated, in the shape of thin rods suitable for flexural test experiments, by pyrolysis in an inert atmosphere at 1000 and 1200°C of sol-gel precursors containing Si-CH 3 and Si-H bonds The amount of carbon in the silicon oxycarbide network has been controlled by varying the carbon load in the precursor gel Density and surface area analysis revealed that all of the samples pyrolyzed at 1200°C were well-densified silicon oxycarbide glasses whereas for the glasses treated at 1000°C, compositions with low carbon loads showed the presence of a residual fine porous phase The elastic modulus (E), flexural strength (MOR), and Vickers hardness (H v ) increase markedly with the amount of carbon in the oxycarbide glasses reaching the maximum values (E≃115 GPa, MOR≃550 MPa, and H v ≃9 GPa) for samples with the highest carbon content The experimental elastic modulus values of the silicon oxycarbide glasses compare well with the theoretical estimations obtained using the Voigt and Reuss models assuming the disordered network formed by the corresponding thermodynamic compositions

Selective absorption processes as the origin of puzzling spectral line polarization from the Sun.

Abstract: Magnetic fields play a key role in most astrophysical systems, from the Sun to active galactic nuclei. They can be studied through their effects on atomic energy levels, which produce polarized spectral lines. In particular, anisotropic radiation 'pumping' processes (which send electrons to higher atomic levels) induce population imbalances that are modified by weak magnetic fields. Here we report peculiarly polarized light in the He I 10,830-A multiplet observed in a coronal filament located at the centre of the solar disk. We show that the polarized light arises from selective absorption from the ground level of the triplet system of helium, and that it implies the presence of magnetic fields of the order of a few gauss that are highly inclined with respect to the solar radius vector. This disproves the common belief that population imbalances in long-lived atomic levels are insignificant in the presence of inclined fields of the order of a few gauss, and opens up a new diagnostic window for the investigation of solar magnetic fields.