Pressure dependence of the Verwey transition in magnetite: an infrared spectroscopic point of view

We investigated the electronic and vibrational properties of magnetite at temperatures from 300 K down to 10 K and for pressures up to 10 GPa by far-infrared reflectivity measurements. The Verwey transition is manifested by a drastic decrease of the overall reflectance and the splitting of the phonon modes as well as the activation of additional phonon modes. In the whole studied pressure range the down-shift of the overall reflectance spectrum saturates and the maximum number of phonon modes is reached at a critical temperature, which sets a lower bound for the Verwey transition temperature T$_{\mathrm{v}}$. Based on these optical results a pressure-temperature phase diagram for magnetite is proposed.Comment: 5 pages, 4 figures; accepted for publication in J. Appl. Phy

Metabolomics applications in children: A right way to go

Metabolomics is a new science based on the study of the metabolome, representing the set of all the metabolites of a biological organism, which are the final products of its gene expression. Metabolomics appears to be a promising tool in perinatal studies, such as hypoxic–ischemic encephalopathy (HIE), intrauterine growth restriction (IUGR), congenital infections, genetic diseases, neonatal nutrition

Low loss Ge-on-Si waveguides operating in the 8–14 µm atmospheric transmission window

Germanium-on-silicon waveguides were modeled, fabricated and characterized at wavelengths ranging from 7.5 to 11 µm. Measured waveguide losses are below 5 dB/cm for both TE and TM polarization and reach values of ∼ 1 dB/cm for ≥ 10 µm wavelengths for the TE polarization. This work demonstrates experimentally for the first time that Ge-on-Si is a viable waveguide platform for sensing in the molecular fingerprint spectral region. Detailed modeling and analysis is presented to identify the various loss contributions, showing that with practical techniques losses below 1 dB/cm could be achieved across the full measurement range

Affordances of distractors and compatibility effects: a study with the computational model TRoPICALS

Seeing an object activates in the brain both visual and action codes. Crucial evidence supporting this view is offered by compatibility effect experiments (Ellis et al. (2007). J Exp Psychol: Hum Percept Perform): perception of an object can facilitate or interfere with the execution of an action (e.g. grasping) even when the viewer has no intention of interacting with the object. TRoPICALS (Caligiore et al. (2010). Psychol Rev) is a computational model developed to study compatibility effects. It provides a general hypothesis about the brain mechanisms underlying compatibility effects, suggesting that the top-down bias from prefrontal cortex (PFC), and its agreement or disagreement with the affordances of objects, plays a key role in such phenomena. Compatibility effects have been investigated in the presence of a distractor object in (Ellis et al. (2007). J Exp Psychol: Hum Percept Perform). The reaction times (RTs) results confirmed compatibility effects found in previous experiments without the distractor. Interestingly, results also showed an unexpected effect of the distractor: responding to a target with a grip compatible with the size of the distractor produced slower RTs in comparison to the incompatible case. Here we present an enhanced version of TRoPICALS that reproduces and explains these new results. This explanation is based on the idea according to which PFC might play a double role in its top-down guidance of action selection producing: (a) a positive bias in favor of the action requested by the experimental task; (b) a negative bias directed to inhibiting the action evoked by the distractor. The model also provides two testable predictions on the possible consequences on compatibilities effects of the target and distractor objects in Parkinsonian disease patients with damages of inhibitory circuits

Chiral spin currents and spectroscopically accessible single merons in quantum dots

We provide unambiguous theoretical evidence for the formation of correlation-induced isolated merons in rotationally-symmetric quantum dots. Our calculations rely on neither the lowest-Landau-level approximation, nor on the maximum-density-droplet approximation, nor on the existence of a spin-polarized state. For experimentally accessible system parameters, unbound merons condense in the ground state at magnetic fields as low as $B^* = 0.2$ T and for as few as N = 3 confined fermions. The four-fold degenerate ground-state at $B^*$ corresponds to four orthogonal merons $\ket{QC}$ characterized by their topological chirality $C$ and charge $Q$. This degeneracy is lifted by the Rashba and Dresselhaus spin-orbit interaction, which we include perturbatively, yielding spectroscopic accessibility to individual merons. We further derive a closed-form expression for the topological chirality in the form of a chiral spin current and use it to both characterize our states and predict the existence of other topological textures in other regions of phase space, for example, at N=5. Finally, we compare the spin textures of our numerically exact meron states to ansatz wave-functions of merons in quantum Hall droplets and find that the ansatz qualitatively describes the meron states.Comment: 4 pages, 5 figures; minor title change, typos fixe

Low-energy electrodynamics of superconducting diamond

Heavily-boron-doped diamond films become superconducting with critical temperatures $T_c$ well above 4 K. Here we first measure the reflectivity of such a film down to 5 cm$^{-1}$, by also using Coherent Synchrotron Radiation. We thus determine the optical gap, the field penetration depth, the range of action of the Ferrell-Glover-Tinkham sum rule, and the electron-phonon spectral function. We conclude that diamond behaves as a dirty BCS superconductor.Comment: 4 pages including 3 figure

The classroom as a research community: an innovative methodological approach for e-learning.

The crisis generated by the pandemic has also affected our education system and challenged traditional teaching/learning models both in school and university. Technology has changed learning and emphasized the collaborative and distributed dimensions of knowledge. Classrooms can be considered as knowledge communities, where active learning, the dimension of research, and comparison with peers represent the values of citizenship that is also digital citizenship. The methodological approach defined as "Bayes' class" fits into this context. Bayes' class is a theoretical-operational approach to learning based on research, experience, and discovery. In this paper we present the results of a teaching activity conducted during the lockdown. We started with these questions: how to use technologies to redesign a digitally enhanced learning environment for university internship activities in the look-down phase? How to redesign indirect internship activities? How to continue to accompany future teachers at a distance in building their knowledge, skills, attitudes, and sensibilities? The focus group, conducted at the end of the experience, confirmed that the “Bayes’ Class” teaching setting, promotes a participatory culture based on interaction, peering, and multitasking. In addition, the experience allowed for the enhancement of the indirect internship as a community of practic

Far-infrared absorption and the metal-to-insulator transition in hole-doped cuprates

By studying the optical conductivity of BSLCO and YCBCO, we show that the metal-to-insulator transition (MIT) in these hole-doped cuprates is driven by the opening of a small gap at low T in the far infrared. Its width is consistent with the observations of Angle-Resolved Photoemission Spectroscopy in other cuprates, along the nodal line of the k-space. The gap forms as the Drude term turns into a far-infrared absorption, whose peak frequency can be approximately predicted on the basis of a Mott-like transition. Another band in the mid infrared softens with doping but is less sensitive to the MIT.Comment: To be published on Physical Review Letter

Blended learning and emergency distance learning. How to rethink learning environments at school

The Italian School context, in the current scenario, represent a field in which emerges many innovation possibilities. The activation of emergency distance learning due to the suspension of presence teaching activities, represents the occasion for Italian School to renovate school traditional dynamics. Aware of the fact that virtual learning environments provide different teaching and learning dynamics, it is important to reform learning design practices and organize an integrated learning environment that eases effective learning paths. In this paper we present the design of a research-training-action path in a Secondary Italian School in which it will be activated a training course for teachers and introduced the e-learning platform Moodle in teaching-learning activities