Terahertz confocal microscopy with a quantum cascade laser source

The recent advances in generation, manipulation and detection of Terahertz (THz) radiation have been accompanied by a growing interest in the application of THz technologies to a wide range of fields spanning from imaging, remote sensing and security controls, to spectroscopy and biomedical science. An appealing reason for developing photonic techniques in this frequency range is the capability for THz rays to penetrate common packaging materials (paper, plastic, wood, ceramics). The recent invention of quantum cascade lasers (QCL) emitting at THz frequencies is enabling a major step forward in THz imaging technologies thanks to the availability of a powerful, compact, solid-state, laser source. Once combined with bolometer array camera detectors, they have allowed the first systems for stand-off THz image acquisition operating in real time up to distances of more than twenty meters. On the other side, there are also great expectations for THz microscopy, especially as a potential diagnostic tool in quality inspection of various industrial productions or in molecular biology at the cell level. Yet, this research direction is just in its infancy, with most works focusing on near-field techniques. In the present thesis work, I focused instead on trying to transfer the principle of optical confocal microscopy to the THz, by implementing the first confocal imaging system based on a QCL, in this case emitting at ~ 3 THz. The confocal spatial filtering can sensibly reduce the depth of field of the microscope, as well as improve its resolution and contrast, making it very useful for inspection of close-by surfaces, where different planes have to be clearly distinguished, or where a depth information is crucial. The use of a QCL source required various preparatory tests and measurements, to assess the emission beam quality and to choose the best option for the spatial filter. In order to reduce the emitting area and improving the profile regularity, hollow metallic waveguide couplers and pinholes were examined. The waveguides were also fully characterized in terms of propagation and coupling losses to QCLs in different configurations, proving that very low-loss modes can be efficiently excited, an interesting result for the future development of THz endoscopes. The definitive confocal setup was finally assembled and characterized in terms of lateral and axial resolution and several images of test objects were collected in order to show the excellent performance of the instrument realized

Unveiling quantum-limited operation of interband cascade lasers

A comprehensive experimental analysis of the frequency fluctuations of a mid-infrared interband cascade laser, down to the quantum-limited operation, is reported. These lasers differ from any other class of semiconductor lasers in their structure and internal carrier generation and transport processes. Although already commercially available, a full evaluation of their potential has not been possible, until now, mainly because their internal dynamics are not yet understood well enough. The measured intrinsic linewidth, down to 10 kHz, ranks them in between quantum cascade and bipolar semiconductor lasers. Understanding the noise features is especially important for demanding applications and is a necessary step for a deeper knowledge of the physical behavior for this class of lasers, in view of the development of novel designs for improved performance.A comprehensive experimental analysis of the frequency fluctuations of a mid-infrared interband cascade laser, down to the quantum-limited operation, is reported. These lasers differ from any other class of semiconductor lasers in their structure and internal carrier generation and transport processes. Although already commercially available, a full evaluation of their potential has not been possible, until now, mainly because their internal dynamics are not yet understood well enough. The measured intrinsic linewidth, down to 10 kHz, ranks them in between quantum cascade and bipolar semiconductor lasers. Understanding the noise features is especially important for demanding applications and is a necessary step for a deeper knowledge of the physical behavior for this class of lasers, in view of the development of novel designs for improved performance

A. S. MAKARENKO’S HERITAGE AND RE-EDUCATION OF PRISONERS WITHIN THE PARADIGM OF ITALIAN CONSTITUTION

В статье характеризируется опыт работы президента Международной Макаренковской ассоциации на должности преподавателя-волонтера в двух итальянских тюрьмах и то, как он анализирует возможность перевоспитывать заключенных в парадигме итальянской конституции. Кроме того, соавторы обращают большое внимание на сходство нескольких статей итальянской Конституции, посвященных образованию и воспитанию, с некоторыми теоретическими установками А. С. Макаренко и Л. В. ВыготскогоIn the article is studied the professional experience of the president of International Makarenko Association as volunteer – teacher in two Italian jails and how he studies the possibility to re-educate prisoners in the paradigm of Italian Constitution. Moreover, coauthors pay particular attention to the analogies of some articles of Italian Constitution dedicated to education and upbringing with theoretical setups of A. S. Makarenko and L. V. Vygotsk

Novel Drugs and Radiotherapy in Relapsed Lymphomas. Abscopal Response and Beyond

Abstract: Combined modality has represented a mainstay of treatment across many lymphoma histologies, given their sensitivity to both multi-agent chemotherapy and intermediate-dose radiotherapy. More recently, several new agents, including immunotherapies, have reshaped the therapeutic panorama of some lymphomas. In parallel, radiotherapy techniques have witnessed substantial improvement, accompanied by a growing understanding that radiation itself comes with an immune-mediated effect. Six decades after a metastatic lesion regression outside the irradiated field was first described, there is increasing evidence that a combination of radiotherapy and immunotherapy could boost an abscopal effect. This review focuses on the mechanisms underlying this interaction in the setting of lymphomas, and on the results of pivotal prospective studies. Furthermore, the available evidence on the concomitant use of radiotherapy and small molecules (i.e., lenalidomide, venetoclax, and ibrutinib), as well as brentuximab vedotin, and chimeric antigen receptor (CAR) T-cell therapy, is summarized. Currently, combining radiotherapy with new agents in patients who are affected by lymphomas appears feasible, particularly as a bridge to anti-CD19 autologous CAR T-cell infusion. However, more studies are required to assess these combinations, and preliminary data suggest only a synergistic rather than a curative effec

Linestrength ratio spectroscopy as a new primary thermometer for redefined Kelvin dissemination

Experimental methods for primary thermometry, after Kelvin unit redefinition on May 2019, become based on a known value of the Boltzmann constant rather than by measuring temperature with respect to a reference point. In this frame, we propose Linestrength Ratio Thermometry (LRT) as a candidate method for primary thermometry in the 9-700 K temperature range. Temperature accuracies at the ppm level are prospected for LRT applied to optical transitions of the CO molecule in the range 80-700 K and of a rare-earth-doped crystal in the 9-100 K one. Future implementations of this technique can contribute to measure the calibration- discrepancies in the ITS-90 metrological scale of thermodynamic temperature which can have a measurable impact in applications ranging from fundamental-physics to meteorology and climatology

Retrieval of phase relation and emission profile of quantum cascade laser frequency combs

The major development recently undergone by quantum cascade lasers has effectively extended frequency comb emission to longer-wavelength spectral regions, i.e. the mid and far infrared. Unlike classical pulsed frequency combs, their mode-locking mechanism relies on four-wave mixing nonlinear processes, with a temporal intensity profile different from conventional short-pulses trains. Measuring the absolute phase pattern of the modes in these combs enables a thorough characterization of the onset of mode-locking in absence of short-pulses emission, as well as of the coherence properties. Here, by combining dual-comb multi-heterodyne detection with Fourier-transform analysis, we show how to simultaneously acquire and monitor over a wide range of timescales the phase pattern of a generic frequency comb. The technique is applied to characterize a mid-infrared and a terahertz quantum cascade laser frequency comb, conclusively proving the high degree of coherence and the remarkable long-term stability of these sources. Moreover, the technique allows also the reconstruction of electric field, intensity profile and instantaneous frequency of the emission.Comment: 20 pages. Submitted to Nature Photonic

QGIS AND OPEN DATA CUBE APPLICATIONS FOR LOCAL CLIMATE ZONES ANALYSIS LEVERAGING PRISMA HYPERSPECTRAL SATELLITE DATA

Climate change poses a significant threat to humans and biodiversity, impacting various aspects of livelihoods, infrastructure, and ecosystems. Understanding climate change and its interaction with the environment is crucial for achieving Sustainable Development Goals. Local Climate Zones (LCZ) play a key role in comprehending climate change by categorizing urban areas also based on their thermal characteristics. This study presents prototype open-source software tools developed to integrate ground and satellite data for LCZ analysis in the Metropolitan City of Milan (Northern Italy). These tools consist of a QGIS plugin to access and preprocess ground-based meteorological sensor data and a client-server platform, based on the Open Data Cube and Docker technologies, for the exploitation of multispectral and hyperspectral satellite data in LCZ mapping and analysis. The tools’ architecture, data retrieval methods, and analysis capabilities are described in detail. The QGIS plugin facilitates the access and preprocessing of ground-based sensor data within the user-friendly QGIS environment. The platform enables seamless ground-sensor and satellite data management and analysis, using Jupyter Notebooks as an interface to support programmatic operations on the data. The proposed tools provide a framework for studying climate change and its local impacts on urban environments, with the potential of empowering users to effectively analyze and mitigate its effects