Gravitational Waves: completeness and connectedness by geodesics

Only few months ago some physicists gave the official announcement that gravitational waves exist, but, from a geometrical point of view, they have always been ``real objects'' and their properties have been widely investigated. The aim of this talk is introducing generalized plane waves and discussing some of their properties such as geodesic connectedness and geodesic completeness.

Slow waves in un modello di crescita tumorale

In questo elaborato ho analizzato un sistema di reazione-diffusione proposto come modello per descrivere un fenomeno di crescita tumorale. In particolare, è stato approfondito il processo in cui l'invasione neoplastica è originata dalla produzione di un eccesso di ioni acidi da parte delle cellule maligne. Il sistema preso in esame descrive l'andamento di tre grandezze: la concentrazione di tessuto sano, la concentrazione di tessuto maligno e l'eccesso di ioni acidi. Ho quindi cercato soluzioni compatibili con il sistema le quali fossero funzioni della tipologia travelling waves, ossia onde che si propagano lungo l'asse reale con un grafico fissato e ad una velocità costante. I risultati ottenuti in questo lavoro sono stati così suddivisi: nel Capitolo 1 viene descritto il processo di invasione tumorale dal punto di vista biologico, nel Capitolo 2 vengono forniti alcuni lemmi e proposizioni preliminari, nel Capitolo 3 viene calcolata un'approssimazione della soluzione del sistema tramite onde del tipo slow waves e infine nel Capitolo 4 sono state studiate la presenza e la larghezza dello spazio interstiziale, ossia di una regione situata tra il tessuto sano e quello neoplastico nella quale si registra una concentrazione di cellule, sia normali sia maligne, praticamente nulla. Infine, sono state rappresentate graficamente le soluzioni in tre possibili situazioni caratterizzate da un diverso parametro di aggressività del tumore.

Rogue waves generation via nonlinear soliton collision in multiple-soliton state of a mode-locked fiber laser

We report for the first time, rogue waves generation in a mode-locked fiber laser that worked in multiple-soliton state in which hundreds of solitons occupied the whole laser cavity. Using real-time spatio-temporal intensity dynamics measurements, it is unveiled that nonlinear soliton collision accounts for the formation of rogue waves in this laser state. The nature of interactions between solitons are also discussed. Our observation may suggest similar formation mechanisms of rogue waves in other systems.

Gravimetric and density profiling using the combination of surface acoustic waves and neutron reflectivity

A new approach is described herein, where neutron reflectivity measurements that probe changes in the density profile of thin films as they absorb material from the gas phase have been combined with a Love wave based gravimetric assay that measures the mass of absorbed material. This combination of techniques not only determines the spatial distribution of absorbed molecules, but also reveals the amount of void space within the thin film (a quantity that can be difficult to assess using neutron reflectivity measurements alone). The uptake of organic solvent vapours into spun cast films of polystyrene has been used as a model system with a view to this method having the potential for extension to the study of other systems. These could include, for example, humidity sensors, hydrogel swelling, biomolecule adsorption or transformations of electroactive and chemically reactive thin films. This is the first ever demonstration of combined neutron reflectivity and Love wave-based gravimetry and the experimental caveats, limitations and scope of the method are explored and discussed in detail.

Follicular dendritic cell disruption as a novel mechanism of virus-induced immunosuppression

Arboviruses (Arthropod-borne viruses) cause acute diseases that are increasingly affecting both human and animal health. Currently, there is a critical lack of understanding about the nature of arbovirus-host interactions in the lymph nodes (LNs), the place where the adaptive immune response is initiated and shaped. In this study, we used bluetongue virus (BTV) and its natural sheep host, to characterise the early events of an arbovirus infection with particular focus on the LNs. Our findings reveal a previously uncharacterized mechanism used by an arbovirus to manipulate host immunity. This study shows that BTV, similarly to other antigens delivered through the skin, is transported rapidly via the lymph to the peripheral lymph nodes. Here, BTV infects and disrupts the stromal network of marginal reticular cells and follicular dendritic cells composing the scaffolding of the follicular area. These cells contribute to antigen presentation and affinity maturation of B-cells for the production of antibodies. Consequently, we observed a loss of germinal centre structure, which hinders B-cell proliferation. This process results in a delayed production of high affinity and virus neutralizing antibodies that is directly related to the virulence of the BTV strain used and the severity of disease. Moreover the humoral immune response to a different antigen is also hampered in BTV-infected animals. Our data show that an arbovirus can evade the host antiviral responses by inducing an acute immunosuppression. Although transient, this immunosuppression occurs at the critical early stages of infection when a delayed host humoral immune response likely affects virus systemic dissemination and the clinical outcome of disease.

Imaginar metáforas de amor, sexo e fé: uma leitura literária de Breaking the Waves (1996) de Lars von Trier

Either with words or images, the expression of feelings results, in a work of art, in communication. If this was not the case, the work would not require a spectator or a reader. And if words suggest images from what its author refers to and a countless number of figurations may happen, the images from a film reveal what you can see. We are often left with "just" the space for those facts to shape up as possible meanings to which we react with emotion or with a particular intellectualization, finding exactly what we call readings or interpretations. Starting from a definition of literature that we see spilled in the work prospected from the polysystem theory by Itamar Even-Zohar from the Porter Institute for Poetics and Semiotics (University of Tel-Aviv), we consider the dynamic character of every cultural moment/object. This is how a literary reading, that is to apply some of the methodologies in the interpretation of a literary work, is allowed to extend to other cultural objects. This is what we are going to do with Lars von Trier's Breaking the Waves, a landmark in cinema for what the movement and manifest Dogma 95 represents, but that for a literature reader particularly focused on the narration of love in its different manifestations - in which sex and faith are included - a corpus is revealed, filled with interpretative possibilities and emotional reactions, important condiments particularly to the spectator and/or interested reader.

Follicular population on the estimation of the superovulatory response in Santa Ines sheep.

The aim was to verify the correlation between follicular population count, superovulatory response and the recovery of viable structures in the in vivo production of sheep embryos. In conclusion, there is a median correlation between follicular population observed by ultrasonography and viable recovered structures after superovulation protocol. Therefore, this tool is not indicated as a screening tool, alone, in the selection of Santa Inês sheep embryo donors.

Follicular wave synchronization on in vivo embryo production in Santa Ines sheep.

This study aimed to evaluate two hormonal protocols for synchronization of follicular wave emergence on in vivo embryo production in Santa Ines sheep under tropical conditions. The greater PRCL rate in GT probably contributed to the smaller number of viable embryos. Thus, it is suggested the appliance indicated the GEm protocol for in vivo embryo production in Santa Ines sheep under tropical conditions.

Restricted intake and lipid inclusion: effects on ovarian follicular development in Santa Inês ewe lambs.

The reproductive efficiency is directly related to the nutritional management. The diet lipid inclusion, especially with enhanced sources of omega 6 and omega 3 fatty acids, is positively associated to the ovarian follicular development of ruminants. The objective of this study was to evaluate the effects of toasted soybean grain addition on restricted or ad libitum feeding on ovarian follicular development of Santa Inês ewe lambs In conclusion, the diameter of the largest follicle and the number of >5 mm follicles were not influenced by the restricted intake diet nor the lipid inclusion; however, they increased in a direct relationship with the age of the animals.

Resonant metamaterials for the control of Rayleigh waves

Since their emergence, locally resonant metamaterials have found several applications for the control of surface waves, from micrometer-sized electronic devices to meter-sized seismic barriers. The interaction between Rayleigh-type surface waves and resonant metamaterials has been investigated through the realization of locally resonant metasurfaces, thin elastic interfaces constituted by a cluster of resonant inclusions or oscillators embedded near the surface of an elastic waveguide. When such resonant metasurfaces are embedded in an elastic homogeneous half-space, they can filter out the propagation of Rayleigh waves, creating low-frequency bandgaps at selected frequencies. In the civil engineering context, heavy resonating masses are needed to extend the bandgap frequency width of locally resonant devices, a requirement that limits their practical implementations. In this dissertation, the wave attenuation capabilities of locally resonant metasurfaces have been enriched by proposing (i) tunable metasurfaces to open large frequency bandgaps with small effective inertia, and by developing (ii) an analytical framework aimed at studying the propagation of Rayleigh waves propagation in deep resonant waveguides. In more detail, inertial amplified resonators are exploited to design advanced metasurfaces with a prescribed static and a tunable dynamic response. The modular design of the tunable metasurfaces allows to shift and enlarge low-frequency spectral bandgaps without modifying the total inertia of the metasurface. Besides, an original dispersion law is derived to study the dispersive properties of Rayleigh waves propagating in thick resonant layers made of sub-wavelength resonators. Accordingly, a deep resonant wave barrier of mechanical resonators embedded inside the soil is designed to impede the propagation of seismic surface waves. Numerical models are developed to confirm the analytical dispersion predictions of the tunable metasurface and resonant layer. Finally, a medium-size scale resonant wave barrier is designed according to the soil stratigraphy of a real geophysical scenario to attenuate ground-borne vibration.

Erythropoietin reduces pathogenic humoral immunity by inhibiting T Follicular Helper cell differentiation and function

A large fraction of organ transplant recipients develop anti-donor antibodies (DSA), with accelerated graft loss and increased mortality. We tested the hypothesis that erythropoietin (EPO) reduces DSA formation by inhibiting T follicular helper (TFH) cells. We measured DSA levels, splenic TFH, TFR cells, germinal center (GC), and class switched B cells, in murine models of allogeneic sensitization, allogeneic transplantation and in parent-to-F1 models of graft versus host disease (GVHD). We quantified the same cell subsets and specific antibodies, upon EPO or vehicle treatment, in wild type mice and animals lacking EPO receptor selectively on T or B cells, immunized with T-independent or T-dependent stimuli. In vitro, we tested the EPO effect on TFH induction. We isolated TFH and TFR cells to perform in vitro assay and clarify their role. EPO reduced DSA levels, GC, class switched B cells, and increased the TFR/TFH ratio in the heart transplanted mice and in two GVHD models. EPO did also reduce TFH and GC B cells in SRBC-immunized mice, while had no effect in TNP-AECM-FICOLL-immunized animals, indicating that EPO inhibits GC B cells by targeting TFH cells. EPO effects were absent in T cells EPOR conditional KO mice, confirming that EPO affects TFH in vivo through EPOR. In vitro, EPO affected TFH induction through an EPO-EPOR-STAT5-dependent pathway. Suppression assay demonstrated that the reduction of IgG antibodies was dependent on TFH cells, sustaining the central role of the subset in this EPO-mediated mechanism. In conclusion, EPO prevents DSA formation in mice through a direct suppression of TFH. Development of DSA is associated with high risk of graft rejection, giving our data a strong rationale for studies testing the hypothesis that EPO administration prevents their formation in organ transplant recipients. Our findings provide a foundation for testing EPO as a treatment of antibody mediated disease processes.

Precise Near-Field Focusing exploiting Bessel Beam Launchers for Wireless Power Transfer at millimeter waves

Wireless Power Transfer has become a promising technology to overcome the limits of wired solutions. Within this framework, the objective of this thesis is to study a WPT link at millimeter waves involving a particular type of antenna working in the radiative near-field, known as Bessel Beam (BB) Launcher. This antenna has been chosen for its peculiarity of generating a Bessel Beam which is by nature non-diffractive, showing good focusing and self-healing capabilities. In particular, a Bull-Eye Leaky Wave Antenna is designed and analysed, fed by a loop antenna and resonating at approximately 30 GHz. The structure excites a Hybrid-TE mode showing zeroth-order Bessel function over the z-component of the magnetic field. The same antenna is designed with two different dimensions, showing good wireless power transport properties. The link budgets obtained for different configurations are reported. With the aim of exploiting BB Launchers in wearable applications, a further analysis on the receiving part is conducted. For WPT wearable or implantable devices a reduced dimension of the receiver system must be considered. Therefore, an electrically large loop antenna in planar technology is modified, inserting phase shifters in order to increase the intensity of the magnetic field in its interrogation zone. This is fundamental when a BB Launcher is involved as transmitter. The loop antenna, in reception, shows a further miniaturization level since it is built such that its interrogation zone corresponds to the main beam dimension of transmitting BB Launcher. The link budget is evaluated with the new receiver showing comparable results with respect to previous configurations, showing an efficient WPT link for near-field focusing. Finally, a matching network and a full-wave rectifying circuit are attached to two of the different receiving systems considered. Further analysis will be carried out about the robustness of the square loop over biological tissues.

Evaluation of the pathogenetic role of cellular subsets of the Follicular Lymphoma Microenvironment

Follicular lymphoma (FL) is a B cell neoplasm, composed of follicle center cells, that accounts for about 20% of all lymphomas, with the highest incidence reported in the USA and western Europe. FL has been considered a virtually incurable disease, with a high response rate alternated with frequent post-therapy relapses or progression towards more aggressive lymphomas. Due to the extreme variability in outcome, many efforts were made to predict prognosis, the need for therapy, and the likelihood of evolution. Even if clinical scores turned out to be robust and easy to use in clinical practice for patient risk stratification, marked heterogeneity in outcome remains within each group and further insights into the biology of FL are needed. The genome-wide approach underscored the pivotal role of the FL microenvironment in the evolution of the disease. In 2004, a landmark study by Dave et al. first described the microenvironment impact on tumor biology. By gene expression profiling they identified two different immune response signatures, involving T-cells and macrophages which seemed to independently predict FL outcome, but their exact is not completely understood and different studies led to variable results. Subsequently, many workgroups identified in amount and distribution pattern of these different cell subsets features which can impact prognosis, this leading to hypothesizing the use of these parameters as surrogate markers of the molecular signature. We aimed to assess the possible contributions of micro-environmental components to FL transformation or progression, its relevance as a prognostic/predictive tool, and its potential role as an innovative therapeutic target. We used immunohistochemical techniques, focusing specifically on macrophages and T-cells subsets, and then found correlations between the presence, proportions, and distribution of these reactive cells and the clinical outcomes leading to the future development of a reliable tool for upfront risk stratification of patients affected by FL.

Oceanic Near-inertial internal waves generation, propagation and interaction with mesoscale dynamics

Oceans play a key role in the climate system, being the largest heat sinks on Earth. Part of the energy balance of ocean circulation is driven by the Near-inertial internal waves (NIWs). Strong NIWs are observed during a multi-platform, multi-disciplinary and multi-scale campaign led by the NATO-STO CMRE in autumn 2017 in the Ligurian Sea (northwestern Mediterranean Sea). The objectives of this work are as follows: characterise the studied area at different scales; study the NIWs generation and their propagation; estimate the NIWs properties; study the interaction between NIWs and mesoscale structures. This work provides, to the author’s knowledge, the first characterization of NIWs in the Mediterranean Sea. The near-surface NIWs observed at the fixed moorings are locally generated by wind bursts while the deeper waves originate in other regions and arrive at the moorings several days later. Most of the observed NIWs energy propagates downward with a mean vertical group velocity of (2.2±0.3) ⋅10-4 m s-1. On average, the NIWs have an amplitude of 0.13 m s-1 and mean horizontal and vertical wavelengths of 43±25 km and 125±35 m, while shorter wavelengths are observed at the near-coastal mooring, 36±2 km and 33±2 m, respectively. Most of the observed NIWs are blue shifted and reach a value 9% higher than the local inertial frequency. Only two observed NIWs are characterised by a redshift (up to 3% lower than the local inertial frequency). In support of the in situ observations, a high resolution numerical model is implemented using NEMO (Madec et al., 2019). Results show that anticyclones (cyclones) shift the frequency of NIWs to lower (higher) frequencies with respect to the local inertial frequency. Anticyclones facilitate the downward propagation of NIW energy, while cyclones dampen it. Absence of NIWs energy within an anticyclone is also investigated.

Sensor networks optimization and software development for Structural Health Monitoring based on ultrasonic guided waves

The Structural Health Monitoring (SHM) research area is increasingly investigated due to its high potential in reducing the maintenance costs and in ensuring the systems safety in several industrial application fields. A growing demand of new SHM systems, permanently embedded into the structures, for savings in weight and cabling, comes from the aeronautical and aerospace application fields. As consequence, the embedded electronic devices are to be wirelessly connected and battery powered. As result, a low power consumption is requested. At the same time, high performance in defects or impacts detection and localization are to be ensured to assess the structural integrity. To achieve these goals, the design paradigms can be changed together with the associate signal processing. The present thesis proposes design strategies and unconventional solutions, suitable both for real-time monitoring and periodic inspections, relying on piezo-transducers and Ultrasonic Guided Waves. In the first context, arrays of closely located sensors were designed, according to appropriate optimality criteria, by exploiting sensors re-shaping and optimal positioning, to achieve improved damages/impacts localisation performance in noisy environments. An additional sensor re-shaping procedure was developed to tackle another well-known issue which arises in realistic scenario, namely the reverberation. A novel sensor, able to filter undesired mechanical boundaries reflections, was validated via simulations based on the Green's functions formalism and FEM. In the active SHM context, a novel design methodology was used to develop a single transducer, called Spectrum-Scanning Acoustic Transducer, to actively inspect a structure. It can estimate the number of defects and their distances with an accuracy of 2[cm]. It can also estimate the damage angular coordinate with an equivalent mainlobe aperture of 8[deg], when a 24[cm] radial gap between two defects is ensured. A suitable signal processing was developed in order to limit the computational cost, allowing its use with embedded electronic devices.