Hawking radiation and mode conversion at optically induced horizons.

The scattering of electromagnetic radiation is an essential and fundamental tool by which we may study light-matter interaction. In usual conditions, the medium is considered as stationary and scattering is characterized by a change in the wavevector spectrum of the light beam. The frequency of the beam is not affected. In this thesis we study the problem of scattering from a moving dielectric perturbation (DP) induced by the nonlinear Kerr effect. Light is scattered and resonantly transferred to two output modes identified by distinct frequencies, one positive and the other negative in the comoving reference frame. Experiments confirm generation of negative resonant radiation in a variety of settings, ranging from optical fibers to bulk Kerr media. A first Born approximation analysis, verified by numerical simulations, predicts that the mixing of the positive and negative modes during the scattering process leads to amplification at the expense of the DP. This provides a link with the spontaneous emission of photons, known as “Hawking radiation”, excited at the event horizon of a gravitational black hole. The moving DP is thus described using the tools of transformation optics and general relativity, in terms of a flowing medium which curves the effective space-time metric as seen by the light rays. Our experimental results show evidences of spontaneous photon emission by the analogue horizon associated to the moving DP, which are in quantitative agreement with the Hawking model

Hawking radiation and mode conversion at optically induced horizons.

The scattering of electromagnetic radiation is an essential and fundamental tool by which we may study light-matter interaction. In usual conditions, the medium is considered as stationary and scattering is characterized by a change in the wavevector spectrum of the light beam. The frequency of the beam is not affected. In this thesis we study the problem of scattering from a moving dielectric perturbation (DP) induced by the nonlinear Kerr effect. Light is scattered and resonantly transferred to two output modes identified by distinct frequencies, one positive and the other negative in the comoving reference frame. Experiments confirm generation of negative resonant radiation in a variety of settings, ranging from optical fibers to bulk Kerr media. A first Born approximation analysis, verified by numerical simulations, predicts that the mixing of the positive and negative modes during the scattering process leads to amplification at the expense of the DP. This provides a link with the spontaneous emission of photons, known as \u201cHawking radiation\u201d, excited at the event horizon of a gravitational black hole. The moving DP is thus described using the tools of transformation optics and general relativity, in terms of a flowing medium which curves the effective space-time metric as seen by the light rays. Our experimental results show evidences of spontaneous photon emission by the analogue horizon associated to the moving DP, which are in quantitative agreement with the Hawking model

Hawking radiation and mode conversion at optically induced horizons.

The scattering of electromagnetic radiation is an essential and fundamental tool by which we may study light-matter interaction. In usual conditions, the medium is considered as stationary and scattering is characterized by a change in the wavevector spectrum of the light beam. The frequency of the beam is not affected. In this thesis we study the problem of scattering from a moving dielectric perturbation (DP) induced by the nonlinear Kerr effect. Light is scattered and resonantly transferred to two output modes identified by distinct frequencies, one positive and the other negative in the comoving reference frame. Experiments confirm generation of negative resonant radiation in a variety of settings, ranging from optical fibers to bulk Kerr media. A first Born approximation analysis, verified by numerical simulations, predicts that the mixing of the positive and negative modes during the scattering process leads to amplification at the expense of the DP. This provides a link with the spontaneous emission of photons, known as “Hawking radiation”, excited at the event horizon of a gravitational black hole. The moving DP is thus described using the tools of transformation optics and general relativity, in terms of a flowing medium which curves the effective space-time metric as seen by the light rays. Our experimental results show evidences of spontaneous photon emission by the analogue horizon associated to the moving DP, which are in quantitative agreement with the Hawking model

Digital for Heritage and Museums: Design-Driven Changes and Challenges

In the recent decade, cultural institutions have increasingly embraced digital technologies as key resources for accomplishing their mission and innovating their cultural activities. In the present work, we attempt to disentangle through a design-driven and multidisciplinary approach the challenges brought by digital transformation in the cultural heritage sector. A diversified research team has thus been involved to include scholars with different backgrounds around the common phenomenon of investigation of Digital (Cultural) Heritage, under the Design Think Thank project. The Introduction is followed by a Methodological section, which outlines the approach to select and review case studies from the exploratory literature for producing a state-of-the-art report and delineates the methodology to map the main user behaviours and needs in the digital experience of CH throughout the value chain. The research team identified three relevant and major themes for the investigation which are addressed in the Literature Review Section through the lenses of design research and practices; simultaneously, design knowledge emerges to have an agency in the transformation. The following section tries to triangulate the results from the literature review, and the mapping of users and stakeholders throughout the cultural institutions value chain, to track and highlight their role and interest in changing heritage panorama. The contribution of the present work wishes to consolidate the results gathered in the first phases of the TT, providing the design community of academics and practitioners with a theoretical contribution about digital changes and challenges of heritage and museums based on a design perspective

Production of nanostructured electrodes from spent Lithium ion batteries and their application in new energy storage devices

The present work is aimed at demonstrating the potentiality of lithium ion batteries recycling through the production of high added value nanostructured material. Nanostructured electrodic materials were synthesized starting from waste lithium ion batteries (LIBs). Firstly, the metals contained in the electrodic powder of exhausted LIBs were extracted by acid-reducing leaching. After filtration, metals rich solution was separated from graphite. Nanoparticles- based electrodes were produced by controlled precipitation and subsequent calcination of metals in order to obtain nanoparticles of LiNi1/3Co1/3Mn1/3O2, one of the most employed LIBs cathodic material. Cathodic materials synthesized starting from waste LIBs and from high grade synthetic reagents were compared after their characterization by SEM, EDX and XRD. The electrochemical performance of the electrodes was evaluated by galvanostatic cycling the electrodes in a lithium half-cell. Remarkably, the electrochemical performances obtained with the electrodes produced by the recovery of metals are close to those recorded using electrodes produced by synthetic reagents. © 2020 Author(s)

Surgical vls therapy of oesophageal achalasia in pediatric age: four case reports

The Authors present a retrospective review of their record of cases, characterized by 4 cases of achalasia in which it was performed a Heller myotomy with front fundoplication (Thall) in laparoscopic approach in the period from 2012 to 2019. In paediatric achalasia, the laparoscopic Heller myotomy seems to be the best treatment because of its multiple advantages offered by the minimally invasive technique. First of all, thanks to the video-technique, which allows a complete and extended myotomy, the accuracy of this operation is maximized; moreover, the post-operative pain is widely reduced, thanks to the minimal dissection and traction of the tissues; finally, but not negligible, this approach ensures a better aesthetic result than the classic open technique. With regard to the front fundoplication, the Authors suggest that it is mandatory because, even if it extends the operating time, it ensures a natural protection to the myotomy herniated mucosa and avoids gastro-oesophageal reflux, which often occurs after the surgical correction, thus obliging to perform a reoperation

CCD-based imaging and 3D space--time mapping of terahertz fields via Kerr frequency conversion

We investigate the spatially and temporally resolved four-wave mixing of terahertz (THz) fields and optical pulses in large-bandgap dielectrics, such as diamond. We show that it is possible to perform beam profiling and space–time resolved mapping of THz fields by encoding the spatial information into an optical signal, which can then be recorded by a standard CCD camera

Counterpropagating frequency mixing with terahertz waves in diamond

Frequency conversion by means of Kerr-nonlinearity is one of the most common and exploited nonlinear optical processes in the UV, visible, IR and Mid-IR spectral regions. Here we show that wave mixing of an optical field and a Terahertz wave can be achieved in diamond, resulting in the frequency conversion of the THz radiation either by sum- or difference-frequency generation. In the latter case, we show that this process is phase-matched and most efficient in a counter-propagating geometry

Papillary thyroid carcinoma in paediatric age

In children, differentiated thyroid carcinoma is a rare condition. Early diagnosis is not always easy, because of the lack of clinical symptoms, but it has a pivotal role in performing a correct therapeutic process. The study describes three cases of papillary thyroid carcinoma. None of the three patients had a positive familiarity or exposure to risk factors. In two cases, the tumor occurred as a non-injurious swelling in the anterior cervical region, in the other case it occurred with a latero-cervical lymphadenopathy that had been persistent for a year. In the first two patients we made a certain diagnosis by the needle aspiration of the thyroid nodule; in the other case the diagnosis was made by surgical exeresis and histological analysis of the lymph nodes. We also performed blood chemistry and hormonal tests, neck ultrasound, chest x-ray. The three children underwent total thyroidectomy and two of them also underwent rightsided cervical lymph node exeresis because there was the presence of metastasis. In our experience, the best therapeutic strategy for children with differentiated thyroid carcinoma is the total thyroidectomy, followed or not by latero-cervical lymph node exeresis and radioiodiotherapy. The removal of the whole gland reduces the risk of relapse