Comparative analysis of design and control strategies for Three-Phase Four-Legs Power Converters

Studio e analisi comparativa di un convertitore trifase a quattro rami, con diverse strategie di controlloopenEmbargo temporaneo per motivi di priorità  nella ricerca previo accordo con terze part

Flow distortion measurements in convoluted aero engine intakes

The unsteady flowfields generated by convoluted aero engine intakes are major sources of instabilities that can compromise the performance of the downstream turbomachinery components. Hence, there exists a need for high spatial and temporal resolution measurements that will allow a greater understanding of the aerodynamics. Stereoscopic Particle Image Velocimetry is capable of providing such fidelity but its application has been limited previously as the optical access through cylindrical ducts for air flow measurements constitutes a notable pitfall for this type of measurements. This paper presents a suite of S-PIV measurements and flow field analysis in terms of snapshot, statistical and time-averaged measurements for two S-duct configurations across a range of inlet Mach numbers. The flow assessments comprise effects of inlet Mach number and S-duct centerline offset distance. Overall, the work demonstrates the feasibility of using S-PIV techniques for determining the complex flow field at the exit of convoluted intakes with at least two orders of magnitude higher spatial resolution than the traditional pressure rake measurements allow. Analysis of the conventional distortion descriptors quantifies the dependency upon the S-duct configuration and highlights that the more aggressive duct generates twice the levels of swirl distortion than the low offset one. The analysis also shows a weak dependency of the distortion descriptor magnitude upon the inlet Mach number across the entire range of Mach numbers tested. A statistical assessment of the unsteady distortion history over the data acquisition time highlights the dominant swirl patterns of the two configurations. Such an advancement in measurement capability enables a significantly more substantial steady and unsteady flow analyses and highlights the benefits of synchronous high resolution three component velocity measurements to unlock the aerodynamics of complex engine-intake systems

Unravelling the Genetic Bases of Hearing Loss: Functional Characterisation of Pathogenic Variants and Novel Candidate Genes Identified by Whole-Exome Sequencing

Hearing Loss (HL) is the most common sensory disorder in humans, and more than half of cases are due to genetic factors. In 30% of cases, hereditary HL is associated with additional clinical features, and it is defined syndromic (SHL), whereas in 70% of cases HL is the only symptom, and it is considered nonsyndromic (NSHL). HL is characterised by an extreme genetic heterogeneity, with more than 150 loci currently associated and at least 100 genes identified, making extremely challenging to obtain a molecular diagnosis with traditional screening methods. For these reasons, whole-exome sequencing (WES) has been introduced to search for mutations and novel genes underlying the disease. In this frame, this thesis describes the study of the genetic bases of deafness in 11 HL (3 SHL and 8 NSHL) families applying WES and an accurate functional validation of the candidate mutations. This approach allowed the identification of the causative mutations in 7 out of the 11 families analysed, while for 3 NSHL families no strong candidate pathogenic variants emerged from our WES data analyses. In addition, in one NSHL family we identified a missense variant in the candidate deafness-causing gene DIAPH2, coding for a protein involved in actin filament elongation. My in-vitro studies indicate a possible functional impairment of the mutant DIAPH2 protein, which might be very relevant in hearing function. In fact, immunohistochemical studies indicate that the mouse ortholog protein Diap2 is expressed in the cochlea in the actin-rich stereocilia of the sensory outer hair cells during development. Auditory brainstem response measurements to evaluate the hearing phenotype of Diaph2 knock-out and knock-in mice were also undertaken. However, at least at the time points analysed, no hearing impairment was detected in the mouse models. Consequently, the role of DIAPH2 in HL in humans still needs to be further clarified

Cmv-specific cell-mediated immunity in immunocompetent adults with primary cmv infection: A case series and review of the literature

Cytomegalovirus-specific cell-mediated immunity (CMV-CMI) in actively infected healthy immunocompetent hosts has been poorly investigated. Conversely, correlates of maternal protective immunity for the fetus after primary infection in pregnancy continue to be studied. The kinetics and magnitude of CMV-specific CMI in immunocompetent primary CMV-infected adults are described. A literature review on CMV-CMI in primarily infected pregnant women and its correlation to the risk of vertical virus transmission is included. Immunological measurements after infection were performed by enzyme-linked ImmunoSPOT assay enumerating IFN-γ secreting CMV-specific T cells, at a single cell level, upon in vitro stimulation with viral antigens. Simultaneously, serological and virological profiles of infected patients were investigated. Patients displayed mild-to-moderate clinical and laboratory profiles for infection, and all showed positive EliSpot results in the early stage of infection (<20 days after onset). The virus-CMI was strong in the majority of patients (58.8%) in which the lowest CMV-DNAemia levels (<300 copies/mL) were detected. Significantly higher viral loads were observed in patients with weak CMV-CMI at the same time-point post-infection (up to 15,104 copies/mL; p < 0.001). T cell response magnitudes to IE-1 and pp65-UL83 peptides were overlapping and stable over time. In these case series, the early presence of CMV-CMI was probably pivotal in controlling viral replication and led to spontaneous viral clearance

Dynamic flow distortion investigation in an S-duct using DDES and SPIV data

The dynamic flow distortion generated within convoluted aero-engine intakes can affect the performance and operability of the engine. There is a need for a better understanding of the main flow mechanisms which promote flow distortion at the exit of S-shaped intakes. This paper presents a detailed analysis of the main coherent structures in an S-duct flow field based on a Delayed Detached Eddy Simulation (DDES). The DDES capability to capture the characteristics of the highly unsteady flow field is demonstrated against high resolution, synchronous Stereoscopic Particle Image Velocimetry (SPIV) measurements at the Aerodynamic Interface Plane (AIP). The flow field mechanisms responsible for the main AIP perturbations are identified. Clockwise and counter-clockwise stream-wise vortices are alternately generated around the separation region at a frequency of St=0.53, which promotes the swirl switching at the AIP. Spanwise vortices are also shed from the separation region at a frequency of St=1.06, and convect downstream along the separated centreline shear layer. This results in a vertical modulation of the main loss region and a fluctuation of the velocity gradient between the high and low velocity flow at the AIP

La coscienza: un ritardato mentale?

During recent decades, Benjamin Libet’s experiments on awareness of voluntary acts have been a focus of the interest of neuroscientists and philosophers. As is well known, Libet has shown that awareness of intending to act “here and now” (for example, the free and spontaneous decision to bend the wrist) is preceded by about a half a second of measurable electric change of the motor cortex. More recent experiments have even shifted the neural anticipation to 10 seconds. The current paper has two main aims. Firstly, it presents a comparison between the results of these experiments and what Aristotle and Kant have argued about the role played by the arational element in conscious voluntary acts. Secondly, it provides an analysis of the limits of the peculiar condition in which the experiments have been carried out as well as of the interpretation of their results