10081 research outputs found
Sort by
Deep space orbit determination and guidance of the LICIACube microsatellite mission
Get PDFRecently, the JPL's MarCO mission demonstrated that these probes are also mature enough to be employed in the deep space, even though with the limitations related to the employed commercial components. Currently, other deep space CubeSats are planned either as stand-alone missions or as companions of a traditional large probe.
Therefore, developing a dedicated navigation suite is crucial to reaching the mission's goals, considering the limitations of the onboard components compared to typical deep space missions. In this framework, the LICIACube mission represents an ideal candidate test-bench, as it performs a flyby of the Didymos asteroid system subject to a strong position, epochs, and pointing requirements. This mission will also allow us to infer the capabilities of such microsatellites and highlight their limitations compared with the benefits of a lighter design and tailoring efforts.
In this work, the OD and guidance methods and tools adopted for classical deep space missions have been tailored for the CubeSat applications and validated through extensive analyses. In addition, navigation procedures and interfaces have been designed in view of the operations foreseen in late 2022. The pre-launch covariance analysis has been performed to assess the mission's feasibility for the nominal trajectory and its associated uncertainties, based on conservative assumptions on the main parameters. Extensive sensitivity analyses have been carried out to understand the main mission parameters affecting the performance and to demonstrate the robustness of the designed trajectory and operation schedule in fulfilling the mission requirements.
The developed system was also stressed by tuning the models to access different reconstruction methods for the maneuvers. The analysis demonstrated the feasibility of the LICIACube mission navigation in compliance with the mission requirements, compatible with the limited resources available, both in space and on the ground
Sinus rhythm restoration with electrical cardioversion: acute effect of shock configuration and subsequent modifications in peripheral flow and sleep.
Get PDFAtrial fibrillation (AF) is a widespread arrhythmia, associated with higher risk of stroke, sleep disorders and dementia. In some conditions, electrical cardioversion (ECV) represents the best choice for rhythm control. Nowadays, there is a growing interest in developing new devices for screening and monitoring of AF patients. We aimed to improve acute efficacy of ECV procedure and to explore the feasibility of the use of new wearable devices for monitoring in candidates to AF ECV. We compared antero-apical pads vs antero-posterior patches approach for AF ECV, and we elaborated a decision algorithm to improve acute efficacy. After, we evaluated the feasibility of the use of new wearable devices for monitoring of candidates to AF ECV. In particular, we analysed the effect of AF ECV on heart rate variability and vascular age parameters derived from PPG signals registered with Empatica (CE 1876/MDD 93/42/EEC), and on EEG pattern registered with Neurosteer (Israel).
From December 2005 to September 2019, 492 patients were enrolled. We evaluated acute efficacy of the two approaches for AF ECV and we elaborated a decision algorithm based on body surface area, weight, and height. The decision algorithm improved first shock efficacy (93.2% vs. 87.2%, p=0.025).
From 1st November 2021 to 1st April 2022, 24 patients were enrolled in PPEEG-AF pilot study. Considering vascular age parameters, a significant reduction in TPR and a wave was observed (p<0.001). Considering sleep patterns, a tendency to higher coherence was observed in registrations acquired during AF, or considering signals registered for each patient independently from AF.
The new decision algorithm improved acute efficacy and reduced costs associated with adhesive patches. Significant modifications were observed on vascular age parameters measured before and after ECV, and a possible AF effect on sleep pattern was noticed. More data are necessary to confirm these preliminary results
Quantum integrability as a new method for exact results on N=2 supersymmetric gauge theories and black holes
Get PDFIn this thesis I show a triple new connection we found between quantum integrability, N=2 supersymmetric gauge theories and black holes perturbation theory. I use the approach of the ODE/IM correspondence between Ordinary Differential Equations (ODE) and Integrable Models (IM), first to connect basic integrability functions - the Baxter’s Q, T and Y functions - to the gauge theory periods. This fundamental identification allows several new results for both theories, for example: an exact non linear integral equation (Thermodynamic Bethe Ansatz, TBA) for the gauge periods; an interpretation of the integrability functional relations as new exact R-symmetry relations for the periods; new formulas for the local integrals of motion in terms of gauge periods. This I develop in all details at least for the SU(2) gauge theory with Nf=0,1,2 matter flavours. Still through to the ODE/IM correspondence, I connect the mathematically precise definition of quasinormal modes of black holes (having an important role in gravitational waves’ obervations) with quantization conditions on the Q, Y functions. In this way I also give a mathematical explanation of the recently found connection between quasinormal modes and N=2 supersymmetric gauge theories. Moreover, it follows a new simple and effective method to numerically compute the quasinormal modes - the TBA - which I compare with other standard methods. The spacetimes for which I show these in all details are in the simplest Nf=0 case the D3 brane in the Nf=1,2 case a generalization of extremal Reissner-Nordström (charged) black holes. Then I begin treating also the Nf=3,4 theories and argue on how our integrability-gauge-gravity correspondence can generalize to other types of black holes in either asymptotically flat (Nf=3) or Anti-de-Sitter (Nf=4) spacetime. Finally I begin to show the extension to a 4-fold correspondence with also Conformal Field Theory (CFT), through the renowned AdS/CFT correspondence
Integrated Programmable-Array accelerator to design heterogeneous ultra-low power manycore architectures
Get PDFThere is an ever-increasing demand for energy efficiency (EE) in rapidly evolving Internet-of-Things end nodes. This pushes researchers and engineers to develop solutions that provide both Application-Specific Integrated Circuit-like EE and Field-Programmable Gate Array-like flexibility. One such solution is Coarse Grain Reconfigurable Array (CGRA). Over the past decades, CGRAs have evolved and are competing to become mainstream hardware accelerators, especially for accelerating Digital Signal Processing (DSP) applications. Due to the over-specialization of computing architectures, the focus is shifting towards fitting an extensive data representation range into fewer bits, e.g., a 32-bit space can represent a more extensive data range with floating-point (FP) representation than an integer representation. Computation using FP representation requires numerous encodings and leads to complex circuits for the FP operators, decreasing the EE of the entire system. This thesis presents the design of an EE ultra-low-power CGRA with native support for FP computation by leveraging an emerging paradigm of approximate computing called transprecision computing. We also present the contributions in the compilation toolchain and system-level integration of CGRA in a System-on-Chip, to envision the proposed CGRA as an EE hardware accelerator. Finally, an extensive set of experiments using real-world algorithms employed in near-sensor processing applications are performed, and results are compared with state-of-the-art (SoA) architectures. It is empirically shown that our proposed CGRA provides better results w.r.t. SoA architectures in terms of power, performance, and area
Safe and Collaborative Navigation & Interaction With Mobile Manipulators in Domestic Appliance Test Labs
Get PDFSafe collaboration between a robot and human operator forms a critical requirement for deploying a robotic system into a manufacturing and testing environment. In this dissertation, the safety requirement for is developed and implemented for the navigation system of the mobile manipulators. A methodology for human-robot co-existence through a 3d scene analysis is also investigated. The proposed approach exploits the advance in computing capability by relying on graphic processing units (GPU’s) for volumetric predictive human-robot contact checking. Apart from guaranteeing safety of operators, human-robot collaboration is also fundamental when cooperative activities are required, as in appliance test automation floor. To achieve this, a generalized hierarchical task controller scheme for collision avoidance is developed. This allows the robotic arm to safely approach and inspect the interior of the appliance without collision during the testing procedure. The unpredictable presence of the operators also forms dynamic obstacle that changes very fast, thereby requiring a quick reaction from the robot side. In this aspect, a GPU-accelarated distance field is computed to speed up reaction time to avoid collision between human operator and the robot. An automated appliance testing also involves robotized laundry loading and unloading during life cycle testing. This task involves Laundry detection, grasp pose estimation and manipulation in a container, inside the drum and during recovery grasping. A wrinkle and blob detection algorithms for grasp pose estimation are developed and grasp poses are calculated along the wrinkle and blobs to efficiently perform grasping task. By ranking the estimated laundry grasp poses according to a predefined cost function, the robotic arm attempt to grasp poses that are more comfortable from the robot kinematic side as well as collision free on the appliance side. This is achieved through appliance detection and full-model registration and collision free trajectory execution using online collision avoidance
3D modelling for the preoperative planning of nephron sparing surgery for renal cancer
Get PDFLo scopo del progetto è quello di valutare l’impatto clinico dell’ utilizzo del 3D modeling nella pianificazione chirurgica preoperatoria della PN.
Sono stati arruolati in modo prospettico 195 pazienti con diagnosi di neoplasia renale T1 candidati a PN tra dicembre 2018 e agosto 2021. Prima dell’intervento chirurgico tutti i pazienti sono stati sottoposti a imaging 2D (TC torace-addome con mezzo di contrasto). Per valutare il ruolo e l’impatto clinico del 3D modelling sulla pianificazione chirurgica, la popolazione è stata suddivisa in due gruppi: gruppo di studio (n=100 pazienti), comprende pazienti candidati a PN dopo pianificazione chirurgica basata sia sull’imaging 2D sia sul modello virtuale 3D; gruppo di controllo (n=95) comprende pazienti candidati a PN dopo pianificazione chirurgica basata solo sull’imaging 2D. L’outcome primario dello studio è la valutazione dell’impatto della ricostruzione 3D nella pianificazione preoperatoria della PN per quanto riguarda il tasso di conversione a RN, tipo di clampaggio arterioso e la necessità di sutura del sistema caliceale.
Nei pazienti del gruppo di studio nel 77.8% dei casi la conversione a RN è stata pianificata prima della chirurgia sulla base del modello 3D, mentre nel gruppo di controllo solo nel 27.3% la conversione a RN è stata pianificata prima della chirurgia sulla base dell’imaging 2D (p=0.03). Nei pazienti sottoposti a PN, l’effettivo clampaggio arterioso eseguito durante la chirurgia è risultato significativamente differente nel gruppo di studio rispetto al gruppo di controllo con maggior tasso di clampaggi arteriosi selettivi (36.3% vs. 9.5%; p<0.001). All’analisi multivariata, solo l’utilizzo del modello 3D è risultato unico predittore indipendente di clampaggio arterioso selettivo (p≤0.001).
La revisione di modelli 3D consente una maggior tasso di conversione a RN pianificate prima della chirurgia, maggior adozione di clampaggio arterioso selettivo con maggior adesione al programma chirurgico rispetto ai pazienti sottoposti a PN con pianificazione basata su imaging 2D.The aim of the project is to evaluate the clinical impact of the use of 3D modeling in the preoperative surgical planning of PN.
Overall, 195 patients diagnosed with T1 renal mass scheduled for PN between December 2018 and August 2021 were prospectively enrolled. Before surgery, all patients underwent 2D imaging (chest-abdomen CT with contrast enhancement). To evaluate the role and the clinical impact of 3D modeling on surgical planning, the population was divided into two groups: study group (n = 100 patients), includes patients who are candidates for PN after surgical planning based on both 2D imaging and on virtual 3D model; control group (n = 95) includes patients who are candidates for PN after surgical planning based only on 2D imaging. The primary outcome of the study is the evaluation of the impact of 3D reconstruction in the preoperative planning of PN with regard to the conversion rate to RN, type of arterial clamping and the need for suturing the calyceal system.
In study group, 77.8% of cases the conversion to RN was planned before surgery on the basis of the 3D model, while in the control group only 27.3% of conversion to RN was planned before surgery on the basis of the 2D imaging (p = 0.03). In patients undergoing PN, the actual arterial clamping performed during surgery was significantly different in the study group compared to the control group with significantly higher rate of selective arterial clamping (36.3% vs. 9.5%; p <0.001). In multivariate analysis, only the use of the 3D model was independent predictor of selective arterial clamping (p≤0.001).
Revision of 3D models allows for higher conversion rate to planned RN prior to surgery, higher adoption of selective arterial clamping with greater adherence to the surgical schedule than patients undergoing PN with 2D imaging-based planning
Analysis and Application of Language Models to Human-Generated Textual Content
Get PDFSocial networks are enormous sources of human-generated content.
Users continuously create information, useful but hard to detect, extract, and categorize.
Language Models (LMs) have always been among the most useful and used approaches to process textual data.
Firstly designed as simple unigram models, they improved through the years until the recent release of BERT, a pre-trained Transformer-based model reaching state-of-the-art performances in many heterogeneous benchmark tasks, such as text classification and tagging.
In this thesis, I apply LMs to textual content publicly shared on social media.
I selected Twitter as the principal source of data for the performed experiments since its users mainly share short and noisy texts.
My goal is to build models that generate meaningful representations of users encoding their syntactic and semantic features.
Once appropriate embeddings are defined, I compute similarities between users to perform higher-level analyses.
Tested tasks include the extraction of emerging knowledge, represented by users similar to a given set of well-known accounts, controversy detection, obtaining controversy scores for topics discussed online, community detection and characterization, clustering similar users and detecting outliers, and stance classification of users and tweets (e.g., political inclination, COVID-19 vaccines position).
The obtained results suggest that publicly available data contains delicate information about users, and Language Models can now extract it, threatening users' privacy
The role of MGMT promoter methylation as a predictive factor for temozolomide-based treatment in neuroendocrine neoplasms: a prospective observational study.
Get PDFTemozolomide-based treatments have been demonstrated active in advanced NETs. However, treatment selection and sequencing are based solely on clinical parameters, since no biomarker is currently available to guide clinical management. MGMT-promoter methylation status is a good predictive factor for TEM treatment response in glioblastomas and melanomas and it is currently used in clinical practice. Differently, in NET patients, evidence on MGMT-promoter methylation status role is scarce.
The aim of this study was to prospectively evaluate the role of MGMT status in predicting response to TEM-based treatment in NET patients. Primary endpoint was correlation of MGMT promoter methylation with PFS; secondary endpoints were correlation with OS, ORR, DCR, safety and cost analysis.
A single-center, prospective observational trial has been conducted at ENETS Center-of-Excellence Outpatient Clinic of Policlinico-Sant’Orsola (Bologna). Patients with advanced, well-differentiated NETs of gastro-entero-pancreatic and lung origin candidate to TEM-based treatment, with tissue available for MGMT-promoter methylation analysis were enrolled. MGMT-promoter methylation status was analyzed by pyrosequencing on tumor tissue.
Data of 22 patients were analyzed. Five patients (23%) presented MGMT-promoter methylation. In the MGMT-methylated population, median PFS was 34 months [IQR:15-58], compared to 14 [IQR:8-38] in non-methylated patients. MGMT-promoter methylation status was the only independent variable related to PFS. Better outcomes were observed in the MGMT-methylated group, also for OS (34vs21 months), DCR (100%vs88%) and ORR (80%vs24%). TEM-based treatment resulted a safe treatment, with low rate of adverse events (G≥3<10%). The cost of MGMT-promoter methylation testing by pyrosequencing is affordable (60 euros/patient) and the test is widely available.
This study has prospectively demonstrated the role of MGMT-promoter methylation status as good predictive factor for TEM-based treatment in NET patients. Due to its promising predictive role, the wide availability and low costs of the assay, this biomarker could be implemented in clinical practice to guide treatment selection in NET patients
Forms (形 XING) and Visions (象 XIANG): A Comparative History of Screendance in Europe and in China
Get PDFLa presente tesi si propone di trattare il soggetto della screendance, giovane disciplina in continua definizione nata combinando cinema e coreografia, da una prospettiva alternativa, coerente con le ultime trasformazioni sociali.
La ricerca, suddivisa in quattro parti, inizia da una ricognizione critica sulla terminologia utilizzata per indicare la screendance nel suo sviluppo storico in Europa e in Cina durante il XX secolo. Adoperando una metodologia basata sugli strumenti della storiografia comparativa, vengono utilizzati come chiavi di lettura i due concetti taoisti di xiang o visione e xing o forma, l’uno riferito al contesto culturale, storico e artistico di una data società umana in un dato periodo storico, e l’altro alludente alle forme artistiche specifiche definite da quei principi.
Nel focalizzarsi sul confronto tra i differenti sviluppi della screendance nel corso del XX secolo in Europa e in Cina, nella seconda parte, la tesi affronta una comparazione diacronica delle trasformazioni di xiang delle due aree geografiche, insieme a una comparazione sincronica delle xing, rendendo più evidenti analogie e divergenze di numerosi case studies occidentali e cinesi.
Uno sguardo sul panorama europeo, attento alle differenze nella disseminazione della screendance attraverso i festival in Gran Bretagna, Francia, Belgio e Italia, costituisce il focus della terza parte.
Con la quarta ed ultima parte, la tesi riserva ampio spazio alla disamina della situazione contemporanea della screendance, seguendone la diffusione negli ultimi quattro decenni attraverso i festival e, più recentemente, i nuovi canali social di creazione e condivisione di contenuti video, e prospettando un futuro in cui la realtà della screendance europea e quella cinese potranno confrontare le proprie identità culturali. Il ricco apparato documentario include un elenco dei festival di screendance europei e cinesi, e una serie di interviste inedite ai maggiori operatori e professionisti del settore, italiani ed europei.This thesis aims to deal with the subject of screendance from an alternative perspective, consistent with the latest social transformations. The research, divided into four parts, begins with a critical review of the terminology used to indicate screendance in its historical development in Europe and China during the twentieth century. Using a methodology based on the tools of comparative historiography, the author uses the two Taoist concepts of xiang or vision and xing or form as keys, one referring to the cultural, historical and artistic context of a given human society in a given historical period , and the other alluding to the specific artistic forms defined by those principles.
The second part is focused on the comparison between the different developments of the screendance during the twentieth century in Europe and China, and deals with a diachronic comparison of the xiang transformations of the two geographical areas, together with a synchronic comparison of the xing, making more evident analogies and divergences of numerous Western and Chinese case studies.
A look at the European panorama, attentive to the differences in the dissemination of the screendance through the festivals in Great Britain, France, Belgium and Italy, constitutes the focus to the third part.
With the fourth and last part, the thesis reserves ample space for the examination of the contemporary situation of screendance, following its diffusion in the last four decades through festivals and, more recently, the new social channels for creating and sharing video content, and envisaging a future in which the reality of the European and Chinese screendance will be able to compare their own cultural identities. The rich documentary apparatus includes a list of European and Chinese screendance festivals, and a series of unpublished interviews with the major operators and professionals in the sector, both Italian and European
Photocatalytic processes: Assessment of the performance of various reactors and materials
Get PDFIl crescente livello di inquinamento nel mondo rappresenta un problema su cui è stata posta particolare attenzione negli ultimi decenni indirizzando così la ricerca verso l’impiego di tecnologie sostenibili ed efficienti per la purificazione dell’aria e dell’acqua. Una tecnologia emergente, che si sta dimostrando molto efficace, è quella dell’ossidazione fotocatalitica. Questa tecnica utilizza come fotocatalizzatori dei materiali semiconduttori, quali il biossido di titanio. L’ossido di titanio sembra essere il fotocatalizzatore ideale se irradiato da radiazioni in campo UV e per questo è stato impiegato anche nella mia attività sperimentale.
Il lavoro svolto è stato focalizzato essenzialmente sullo studio della cinetica di degradazione fotocatalitica dell’acido formico. Le prove sperimentali condotte in laboratorio hanno riguardato substrati organici che degradano direttamente senza intermedi di reazione, come l’acido formico. A tal fine è stato impiegato un apparato sperimentale funzionante in batch. I campioni prelevati a periodi regolari sono stati analizzati ad un misuratore di Carbonio Organico Totale (TOC). Per l’attivazione del processo fotocatalitico sono state utilizzate due sorgenti luminose differenti installate in due reattori con diversa geometria: il reattore piano illuminato con tecnologia LED e il reattore anulare illuminato con lampada fluorescente. I dati sperimentali (concentrazione dell’acido formico in funzione del tempo) sono stati oggetto di analisi cinetica. È stato usato a tal fine il metodo integrale di analisi cinetica assumendo due diversi modelli, a cui corrispondono due diverse equazioni cinetiche: un’equazione cinetica ad un solo parametro di “tipo” quadratico di Minero e un’equazione cinetica a due parametri del tipo Langmuir Hinshelwood. La regressione dei dati sperimentali è risultata molto soddisfacente e piuttosto simile per entrambi i modelli. Un’importante conclusione è che la degradazione fotocatalitica di soluzioni acquose di acido formico pare consentire di usare il modello quadratico per attuare delle “misure attinometriche” dell’energia radiante assorbita nel reattore.The increasing level of pollution in the world represents a problem on which particular attention has been paid in recent decades, thus directing research towards the use of sustainable and efficient technologies for air and water purification. An emerging technology, which is proving to be very effective, is the photocatalytic oxidation.
This technique uses semiconductor materials such as titanium dioxide as photocatalysts. Titanium oxide seems to be the ideal photocatalyst if irradiated by UV radiation and for this reason it was also used in my experimental activity. The work carried out was essentially focused on the study of the photocatalytic degradation kinetics of formic acid. The experimental tests conducted in the laboratory concerned organic substrates that degrade directly without reaction intermediates, such as formic acid. For this purpose, an experimental apparatus operating in batch was used. The samples taken at regular periods were analyzed on a Total Organic Carbon (TOC) meter. To activate the photocatalytic process, two different light sources were used installed in two reactors with different geometry: the flat reactor illuminated with LED technology and the annular reactor illuminated with a fluorescent lamp. The experimental data (concentration of formic acid vs time) were subjected to kinetic analysis. For this purpose the integral method of kinetic analysis was used assuming two different models, to which correspond two different kinetic equations: a kinetic equation with a single parameter of the Minero quadratic "type" and a kinetic equation with two parameters of the type Langmuir Hinshelwood. The regression of the experimental data was very satisfactory and quite similar for both models. An important conclusion is that the photocatalytic degradation of aqueous solutions of formic acid seems to allow the use of the quadratic model to implement "actinometric measurements" of the radiant energy absorbed in the reactor