A quantum computational semantics for epistemic logical operators. Part I: epistemic structures

Some critical open problems of epistemic logics can be investigated in the framework of a quantum computational approach. The basic idea is to interpret sentences like “Alice knows that Bob does not understand that π is irrational” as pieces of quantum information (generally represented by density operators of convenient Hilbert spaces). Logical epistemic operators (to understand, to know. . .) are dealt with as (generally irreversible) quantum operations, which are, in a sense, similar to measurement-procedures. This approach permits us to model some characteristic epistemic processes, that concern both human and artificial intelligence. For instance, the operation of “memorizing and retrieving information” can be formally represented, in this framework, by using a quantum teleportation phenomenon

Augmented contents as assistive technology to make more inclusive everyday objects for visually impaired people

This study investigates how to exploit technologies for making society more inclusive by increasing the usability of artefacts that may be not accessible to people with disabilities. Accessing everyday objects can be a challenge for blind and visually impaired people. Although digital calendars are available, a tangible paper-based calendar can be more suitable or preferred by users, in specific contexts. Such a calendar should be as inclusive as possible. This paper shares the experience of designing an inclusive paper-based calendar conceived in codesign sessions with blind and visually impaired users

A study of the deep structure of the energy landscape of glassy polystyrene: the exponential distribution of the energy-barriers revealed by high-field Electron Spin Resonance spectroscopy

The reorientation of one small paramagnetic molecule (spin probe) in glassy polystyrene (PS) is studied by high-field Electron Spin Resonance spectroscopy at two different Larmor frequencies (190 and 285 GHz). The exponential distribution of the energy-barriers for the rotational motion of the spin probe is unambigously evidenced at both 240K and 270K. The same shape for the distribution of the energy-barriers of PS was evidenced by the master curves provided by previous mechanical and light scattering studies. The breadth of the energy-barriers distribution of the spin probe is in the range of the estimates of the breadth of the PS energy-barriers distribution. The evidence that the deep structure of the energy landscape of PS exhibits the exponential shape of the energy-barriers distribution agrees with results from extreme-value statistics and the trap model by Bouchaud and coworkers.Comment: Final version in press as Letter to the Editor on J.Phys.:Condensed Matter. Changes in bol

Glassforming Liquids, Amorphous and Semicrystalline Polymers: Exploring their Energy Landscape and Dynamical Heterogeneity by Multi-frequency High-Field EPR

We review past and recent work carried out on viscous liquids, amorphous and semicrystalline polymers by multifrequency high-field electron paramagnetic resonance (HF-EPR) facility in Pisa. The emphasis is on the enhanced ability to provide fine details of the reorientation process of the paramagnetic guest, the spin probe, revealing features driving the dynamics of the host system, including the energy-barrier distribution of glassy polymers, the dynamical heterogeneity of semicrystalline polymers, and the dynamical changes occurring at the critical temperature predicted by the ideal mode-coupling theory

On the onset of breathing mode in Hall thrusters and the role of electron mobility fluctuations

Breathing mode is an ionization instability which is observed ubiquitously in the operation of Hall thrusters. It is recognized as a relatively low frequency (10-30 kHz) longitudinal oscillation of the discharge current and the plasma parameters. Although breathing instability is widely studied in the literature, the conditions for its origin are not fully understood. In this work we investigate the mechanisms responsible for the origin of the breathing mode in Hall thrusters by using a numerical model, allowing us to highlight the importance of electron mobility fluctuations for the onset and self-sustenance of the instability. Our one-dimensional, fully fluid model of the thruster channel is calibrated against the measured discharge current signal for a 5 kW-class Hall thruster operating in a condition where breathing mode is fully developed. The corresponding steady, unstable configuration (base state) is numerically computed by applying the Selective Frequency Damping (SFD) method. Then, a series of numerical tests is performed to show the existence of a feedback loop involving fluctuations around the base state of the neutral density, electron mobility, and electric field. We show that oscillations of the electron mobility are mainly caused by variations of the neutral density and are in phase with them; this, in turn, induces oscillations of the electric field, which are in phase opposition. The electric field acts simultaneously on the electron temperature and on the ion dynamics, promoting the depletion and replenishment of neutrals in the chamber

Using accessible digital resources for teaching database design: towards an inclusive distance learning proposal

[Proceedings of] 13th Annual Conference on Innovation and Technology in Computer Science Education (ITiCSE'08), Madrid, Spain, June 30-July 2, 2008This paper introduces a pilot experience in teaching database using accessible digital resources in 3er course of Computer Science degree at Universidad Carlos III de Madrid. A platform containing learning material in different formats (video, audio, slides presentation) has been designed allowing students accessing resources as well as to be evaluated by means of tests. Preliminary results show that 46.81% of the students have already interacted with the system and 97.12% of the students passed the tests.Publicad

Is coffee powder extract a possible functional ingredient useful in food and nutraceutical industries?

The present study aimed to assess the phytochemical content and in vitro bioactivity of ethanolic extracts of Arabica (A) and/or Robusta (R) coffee powder having different geographical origins. For this purpose, total phenols (TPC) and flavonoids (TFC) content as well as a- and b-tocopherol were quantified. The antioxidant activity was assessed by using a multi-target approach in which the radical scavenging potential, the protection from lipid peroxidation, and the involvement of the iron-reducing mechanism were applied. The carbohydrate hydrolyzing enzymes’ (a-amylase and a-glucosidase) inhibitory activities were also assessed. Arabica coffee sample (C2-A) showed the highest TPC, TFC, and a-tocopherol content with values of 63.1 mg chlorogenic acid equivalents (CAE)/g dry powder, 16.2 mg of quercetin (QE) equivalents/g dry powder, and 5.6 mg/100 g dry powder, respectively. Relative Antioxidant Capacity Index (RACI), used to statistically integrate results from 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), 2,2-diphenyl-1-picrylhydrazyl (DPPH), ferric reducing ability power (FRAP), and protection of lipid peroxidation assays, evidenced that sample C4-R derived from Robusta from Guatemala showed the highest antioxidant potential with a value of –0.61. Arabica from Puerto Rico was the most active against a-amylase, whereas the blend Arabica/Robusta sample (C5-A60R40) showed the highest inhibitory activity against a-glucosidase with IC50 values of 120.2 and 134.6 mg/mL, respectively. The results show how the qualitative-quantitative composition of the extracts is strongly associated not only with the variety but also with the geographical origin of the samples