Advanced Diagnosis Techniques for Radio Telescopes in Astronomical Applications

The performance of radio telescopes in astronomical applications can be affected by structural variations due to: 1. Misalignment of the feeding structure, resulting in a lateral or axial displacement of the receiver; 2. Wind stress; 3. Gravitational distortion as the antenna is tilted; 4. Thermal distortion with ambient temperature or sunlight. Diagnosis methods are necessary to estimate any deviation of the antenna system from its nominal behavior in order to guarantee the maximum performance. Several approaches have been developed during the years, and among them the electromagnetic diagnosis appears today as the most appealing, because it allows a relatively simple measurement setup and a reduced human intervention. Electromagnetic diagnosis is based on the acquisition of the antenna Far Field Pattern (FFP), with the Antenna Under Test (AUT) working in receiving mode. A natural radio star or a satellite beacon provides the signal source. The acquisition of the FFP typically requires a very large number of field samples to get the complete information about the AUT, and the subsequent measurement process may span over several hours. A prolonged acquisition has significant drawbacks related to the continuous tracking of the source and the inconstancy of the environmental conditions. The purpose of the PhD activity has been focused on an optimized formulation of the diagnosis of radio telescopes aimed at reducing the number of field samples to acquire, and so at minimizing the measurement time. A diagnosis approach has been developed, based on the Aperture Field method for the description of the AUT radiation mechanism. A Principal Component Analysis (PCA) has been employed to restore a linear relationship between the unknowns describing the AUT status and the far field data. An optimal far field sampling grid is selected by optimizing the singular values behavior of the relevant linearized operator. During the activity, a computational tool based on Geometrical Optics (GO) has been developed to improve the diagnosis approach. Indeed, once the Aperture Field is recovered from the inversion of the measured FFP, an additional step is required to assess the AUT status from the phase distribution. Obviously, the computation of the phase distribution should be based on efficient algorithms in order to properly manage electrically large reflectors. The developed GO technique relies on the Fast Marching Method (FMM) for the direct solution of the eikonal equation. A GO approach based on the FMM is appealing because it shows a favorable computational trend. Furthermore, the explicit solution of the eikonal equation opens the possibility to set up an inverse ray tracing scheme, which proves particularly convenient compared to direct ray tracing because it allows to easily select the minimum number of rays to be traced. The FMM is also amenable for parallel execution. In particular, in the present work, the Fast Iterative Method has been implemented on Graphics Processing Units (GPUs). Moreover, the FMM has been accelerated by introducing a tree data structure. The tree allows to manage the mutual interactions between multiple scattering surfaces and the parallelization of the ray tracing step. The method has been numerically tested on simple canonical cases to show its performance in terms of accuracy and speed. Then, it has been applied to the evaluation of the Aperture Field phase required by the reflector diagnosis. During the research activity, the problem of validating the diagnosis algorithms has been also faced. Obviously, a numerical analysis can been carried out to test the model employed to describe the system and to evaluate the performance of the algorithm. To this end, a reliable commercial software exploited to simulate reflector antennas has been exploited. However, to complete the analysis, the experimental validation becomes mandatory, and an experimental outdoor far field test range is required. Accordingly, a test range has been set up thanks to the collaboration with Istituto Nazionale di Astrofisica (INAF) of Naples, Italy. Its realization has involved the full development of the software to drive an Alt-Azimuth positioner and to remotely control the instrumentation. In addition, an upgrade of the internal connections of a Vector Network Analyzer has been performed in order to allow the interferometric acquisition

Negative-Pressure Wound Therapy for Prevention of Sternal Wound Infection after Adult Cardiac Surgery : Systematic Review and Meta-Analysis

The results of current studies are not conclusive on the efficacy of incisional negative-pressure wound therapy (NPWT) for the prevention of sternal wound infection (SWI) after adult cardiac surgery. A systematic review of the literature was performed through PubMed, Scopus and Google to identify studies which investigated the efficacy of NPWT to prevent SWI after adult cardiac surgery. Available data were pooled using RevMan and Meta-analyst with random effect models. Out of 191 studies retrieved from the literature, ten fulfilled the inclusion criteria and were included in this analysis. The quality of these studies was judged fair for three of them and poor for seven studies. Only one study was powered to address the efficacy of NPWT for the prevention of postoperative SWI. Pooled analysis of these studies showed that NPWT was associated with lower risk of any SWI (4.5% vs. 9.0%, RR 0.54, 95% CI 0.34-0.84, I-2 48%), superficial SWI (3.8% vs. 4.4%, RR 0.63, 95% CI 0.29-1.36, I-2 65%), and deep SWI (1.8% vs. 4.7%, RR 0.46, 95% CI 0.26-0.74, I-2 0%), but such a difference was not statistically significant for superficial SWI. When only randomized and alternating allocated studies were included, NPWT was associated with a significantly lower risk of any SWI (3.3% vs. 16.5%, RR 0.22, 95% CI 0.08-0.62, I-2 0%), superficial SWI (2.6% vs. 12.4%, RR 0.21, 95% CI 0.06-0.69, I-2 0%), and deep SWI (1.2% vs. 4.8%, RR 0.17, 95% CI 0.03-0.95, I-2 0%). This pooled analysis showed that NPWT may prevent postoperative SWI after adult cardiac surgery. NPWT is expected to be particularly useful in patients at risk for surgical site infection and may significantly reduce the burden of resources needed to treat such a complication. However, the methodology of the available studies was judged as poor for most of them. Further studies are needed to obtain conclusive results on the potential benefits of this preventative strategy.Peer reviewe

Topical rifampicin for prevention of deep sternal wound infections in patients undergoing coronary artery bypass grafting

Deep sternal wound infections (DSWI), although an infrequent complication, significantly impair postoperative outcomes after coronary artery bypass grafting (CABG) surgery. Among several preventive strategies, topical antibiotic therapy immediately before sternal closure has been strongly advocated. In this retrospective analysis, the incidence of DSWI in 517 patients undergoing isolated CABG and receiving rifampicin irrigation of mediastinum, sternum and suprasternal tissues was compared to an historical consecutive cohort of 448 patients. To account for the inherent selection bias, a 1:1 propensity matched analysis was performed. Patients receiving topical rifampicin experienced significantly less occurrence of postoperative DSWI (0.2% vs 2.5%, p = 0.0016 in the unmatched analysis; 0.3% vs 2.1%, p = 0.0391 in the matched analysis). Intensive care unit stay, hospital stay, and operative mortality were similar between groups. This study shows that topical rifampicin in combination with commonly prescribed preventative strategies significantly reduces the incidence of DSWI to less than 0.3% in unselected patients undergoing a full median sternotomy for CABG. Further studies, including a larger number of patients and with a randomization design, would establish the potential preventative role of topical rifampicin in reducing the occurrence of DSWI

Optimized Trajectory Tracking of a Class of Uncertain Systems Applied to Optimized Raster Scanning in Near-Field Measurements

A tracking problem is considered for a very recurring class of systems, such as Cartesian robots with real actuators, conveyor belts, and certain scanning devices used for medical and engineering applications, as near-field antenna characterization. Theorems are proven for the design of a PID controller with a possible compensation signal to track sufficiently regular trajectories with a prescribed maximum error. The developed design methodology is used to identify the current antenna scanning system without a controller and to design and construct a new controller that provides better performance than the current one. Moreover, this paper proposes an optimized raster scan acquisition scheme that reduces the number of field samples and the scanning path length compared with the more conventional approaches. By using the new controller and the proposed optimized sampling strategy, which provides a sparse distribution of the samples, the performance of an antenna can be evaluated in a considerably shorter time than that necessary using the pre-existing controller and standard scanning, as experimentally assessed in this paper

Molecular analysis of Duchenne/Becker muscular dystrophy

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Autonomy Supportive Contexts, Autonomous Motivation, and Self-Efficacy Predict Academic Adjustment of First-Year University Students

Aim: The purpose of this study was to investigate the process that lead to academic adjustment of undergraduate students in the first year of higher education, by testing a predictive model based on self-determination theory with the inclusion of self-efficacy. The model posits that perceived autonomous forms of support from parents and teachers foster autonomous motivation and self-efficacy, which in turn predict academic adjustment.Method: A two-wave prospective design was adopted. Freshman students at an Italian university (N = 388; 73.5% females, Mage = 21.38 years ± 4.84) completed measures of autonomous motivation, perceived autonomy support from parents and teachers, self-efficacy, and intention to drop out from university at the start of their academic year. Students' past performance and socioeconomic background were also measured. At the end of the first semester, information about number of course modules passed and credits attained for each student were obtained from the department office and matched with the data collected in the first wave by an identification number.Results: Findings of structural equation modeling analysis supported the proposed model for first-year university students, after controlling for the influence of past performance and socioeconomic background. Specifically, autonomous motivation and self-efficacy predicted dropout intention and academic adjustment a few months later. Autonomous motivation and self-efficacy were encouraged by autonomy supportive behaviors provided by teachers and parents.Conclusion: According to our findings, in order to promote higher degree of academic adjustment in freshman students, interventions should aim to encourage autonomous motivation and self-efficacy through autonomous supportive behavior from the university and the family contexts

Highlights from 2022 in EHJ Open.

editorial reviewe

MORFEO enters final design phase

MORFEO (Multi-conjugate adaptive Optics Relay For ELT Observations, formerly MAORY), the MCAO system for the ELT, will provide diffraction-limited optical quality to the large field camera MICADO. MORFEO has officially passed the Preliminary Design Review and it is entering the final design phase. We present the current status of the project, with a focus on the adaptive optics system aspects and expected milestones during the next project phase