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Is international law a building or stumbling block to States' response to a legacy of massive atrocities? Reassessing the obligations to investigate and prosecute
No full textPost-conflict situations, regime changes, and peace processes within situations of active hostility pose tremendous challenges for the governments and societies involved. The inherent dilemma between justice and the international obligations to investigate and prosecute a legacy of large-scale human rights abuses, and the role of alternative justice mechanisms, which seek to pursue more abstract goals such as peace and reconciliation, has its roots in the current discourse of transitional justice. By analyzing the provisions in which the obligations to investigate and prosecute are enshrined or derived, this work disentangles the common misconception that such procedural obligations are naturally rooted and clearly spelled out in the most important international humanitarian and human rights instruments considered by this study. It also dispels the notion that successor governments facing a transition operate in a normative vacuum: international law, human rights bodies, the ICC, and the UN impose limitations on the sovereign exercise of states’ prerogatives, thus shaping local approaches to policies of justice. But an uncompromising call for prosecution overlooks
realpolitik considerations, practical difficulties, and the peculiar needs of fragile successor governments with limited power and room for maneuver. Granted that the rule of law cannot be reestablished in a society in which perpetrators enjoy impunity, since de facto and de jure impunity do per se constitute a breach of states parties’ duties under the conventions, criminal prosecution cannot be the only tool for reckoning with the past because punishment also encompasses non-criminal sanctions. A pluralistic notion of accountability and an integrated approach to peacemaking are thus advocated. International law is only capable of adjusting to the peculiarities of transitions if it is flexibly understood and applied. To remain relevant as a legal regime it needs to accord with political realities but should always be interpreted in a manner consistent with its rationale
Static and dynamics properties of a miscible two-component Bose-Einstein condensate
Full text linkOne of the main reasons which makes Bose-Einstein condensates a successful topic of research is their flexibility for creating systems whose Hamiltonian can be engineered almost at will. A particularly relevant research topic in the field of Bose–Einstein condensation concerns the realization of binary mixtures in the presence of coherent coupling Ω. These systems show properties having analogies with the formation of stripe phases, which are related to supersolidity, or with the formation of domain walls, which are related to quark confinement in quantum chromodynamics. Technically, the realization of coherently coupled binary mixtures requires a deep knowledge of the system properties, even in absence of coherent coupling between the two states, and a highly precise control of the magnetic field. Both these topics are treated in this research work, which aims to lay the foundation for experimental studies in resonantly-coupled spinor BECs. More in detail, the simplest collective oscillation, i.e., the spin-dipole (SD) oscillation and the static SD polarizability are studied to test the miscibility properties of the system and its response to external perturbation of the trapping potentials, both at zero and at finite temperature in order to characterize the behaviour of the system at Ω = 0. This work also reports the theoretical study done to design a magnetic shield able to guarantee a precise control of the environmental magnetic field and suitable to be used to study the binary mixture in the presence of coherent coupling
Design and microfabrication of multifunctional bio-inspired surfaces
Full text linkIn this thesis, we used CMOS-like technologies to produce improved, hierarchical multifunctional bioinspired surfaces. Different natural surfaces have been surveyed including well-known lotus leaf, sharkskin, back of the Namib Desert beetle, butterfly wings, and legs of water-walking insects. The lotus leaf features superhydrophobicity, which leads to low adhesion and self-cleaning. Sharkskin is composed of ripples that manage to reduce skin-friction and thus drag resistance. The Namib Desert beetle, harvests water from the heterogeneous pattern having hydrophilic/hydrophobic bumps on his back. Butterfly wings have re-entrant structures that manage to reach superhydrophobicity from a hydrophilic substrate. Hairy legs of water-walking insects are superhydrophobic with low adhesion that allows them to fight and jump on water.
In chapter 1, we have undertaken a review of bioinspired surfaces that emulate the abilities of such natural surfaces.
Then, in chapter 2 we have described the innovative CMOS-like techniques used for generating several hierarchical and re-entrant microstructures.
Chapter 3 depicts the analysis of surfaces with hierarchical structures generated with a fast and easy process; this latter forms a second hierarchical level composed of random pyramidal elements using wet etching. Surfaces realized with this process manage to reach remarkably high contact angle and low contact angle hysteresis. Additionally, in this chapter we have introduced an analytical model to study the stability of Cassie-Baxter state over Wenzel state for these hierarchical surfaces.
In chapter 4 the fabrication and analysis of surfaces composed of controlled hierarchical levels, which combine sharkskin with single-level lotus leaf-inspired pillared structures are reported. These particular hierarchical surfaces are demonstrated to hold high superhydrophobic properties along with low skin-friction. The superhydrophobicity of these surfaces has been characterized in a series of tests on an inclined plane. The data extrapolated from this measurement was used to evaluate the total dissipated energy of the sliding drop. Combining the data collected during this experiment with contact angle and contact angle hysteresis measurements we propose a global parameter that evaluates the superhydrophobic “level” of a surface.
Furthermore, in chapter 5 similar hierarchical surfaces have also been tested for water harvesting together with single-level pillared surfaces that feature heterogeneous chemistry with hydrophilic/hydrophobic spot on every single pillar.
In chapter 6 a series of tests have also been performed on butterfly-inspired surfaces. Although the substrate of such surfaces is hydrophilic, thanks to the re-entrant structures the surfaces reach high level of hydrophobicity. An implemented mathematical model and experimental test confirm the stability of this hydrophobic state.
In chapter 7, we describe two sets of surfaces inspired by the hairy legs of water walking insect the first is composed of stretchable pyramidal-pillars and the second of truncated-conical silicon pillars. The ability of sharp structures to easily detach from water surfaces is exploited to change the contact angle value of a water drop deposed on this fast type of stretchable micropatterned surface. A mathematical model has been implemented and experimental tests have been carried out to evaluate the stability of the water-air composite interface on both types of microstructured surfaces. In particular, in the polymeric surfaces elasto-capillarity seams to influence the metastability of the Cassie-Baxter state
Flutter instability in structural mechanics: theory and experimental evidence
Full text linkThe present thesis summarizes the research activity in the field of elastic structures subject to tangential follower forces performed in the Instability Lab of the University of Trento. Elastic structures loaded by nonconservative positional forces are interesting from different perspectives. First, they are subject to flutter instability, a dynamical instability which remains undetected using static approaches. Second, in these structures dissipation plays a fundamental and destabilizing role. Third, a critical load calculated in the limit of vanishing dissipation is found to be smaller than the critical load calculated in the same structure where the dissipation is assumed absent 'from the beginning'. This behaviour is so peculiar that is usually referred to as 'the Ziegler paradox' and was never experimentally substantiated before. Flutter instability in elastic structures subject to follower load, the most important cases being the famous Beck's and Pflüger's columns (two elastic rods in a cantilever configuration, with an additional concentrated mass at the end of the rod in the latter case), have attracted, and still attract, a thorough research interest. In the present thesis, the effects of internal and external damping, crucial in the interpretation of experiments, have been investigated. Contrary to a common belief, it has been shown that the effect of external damping is qualitatively the same as the effect of internal damping, both yielding a pronounced destabilization paradox. This result corrects previous claims relative to destabilization by external damping of the Ziegler's and Pflüger's elastic structures. The major challenge in the research area of follower forces is the practical realization of these forces, which was previously obtained only for the case of the Ziegler double pendulum (a two-degrees-of-freedom elastic system subject to a tangential force). Therefore, an experimental setup to introduce follower tangential forces at the end of an elastic rod was designed, realized, validated, and tested, in which the follower action is produced by exploiting Coulomb friction on an element (a freely-rotating wheel) in sliding contact against a plate (realized by a conveyor belt). It is therefore shown that follower forces can be realized in practice and the first experimental evidence is given of the flutter and divergence instability of the Pflüger's column. Load thresholds for both the two instabilities are measured for the first time. Moreover, the detrimental effect of dissipation on the critical load for flutter is experimentally demonstrated. The introduced approach to follower forces discloses new horizons for testing self-oscillating structures and for exploring and documenting dynamic instabilities possible when nonconservative loads are applied
Advanced Signal Processing Methods for Planetary Radar Sounders Data
Full text linkRadar sounders are spaceborne electromagnetic sensors specifically designed for subsurface investigations. They operate in the HF/VHF part of the electromagnetic spectrum and are widely employed for applications such as monitoring changes to the polar ice sheets of the Earth and for the study of planetary bodies (e.g. Mars) from satellite. Radar sounding of planetary bodies is a relatively young discipline both in terms of system design and data processing architectures. As a result of the current state of the art in system design, the data recorded by radar sounders are typically affected by artifacts, such as off-nadir surface clutter, which hinders its interpretation by scientists. On top of that, the analysis of the very large of amount of data produced by such systems is typically performed manually by experts thus inherently subjective and time-consuming. Therefore the development of automatic high-level processing strategies for reliable, objective and fast extraction of information is needed.
Accordingly, this thesis work deals with different aspects of radar sounding namely system design, low-level and high-level processing.
The thesis provides three main novel contributions to the state of the art. First, we present a study on system design, performance assessment and 3D electromagnetic simulations of a radar sounding system specifically tailored for detecting lava tubes under the Moon surface. Lava tubes are considered to be important and useful structures. By having a stable temperature and by providing protection against cosmic ray radiation and micrometeorites impacts, they could potentially serve as natural shelter for human outposts on the Moon.
The results presented in this thesis show that a multi-frequency radar sounder is the best option for effectively sound most of the lava tube dimension expected from the literature and that they show unique electromagnetic signature which can be used for their detection.
The second novel contribution is focused on low-level processing and consists in a bio-inspired clutter detection model based on bats echolocation. Very relevant analogies occur between a bat and radar sounder such as the nadir acquisition geometry. The mathematical model proposed in this thesis adapts the bats frequency diversity strategy (i.e. multi-frequency approach) to solve clutter ambiguities to the radar sounding case.
The proposed bio-inspired clutter detection model has been tested and validated on experimental data acquired over Mars. The experimental results showed that the method is able to discriminate in a precise way the radar echoes arising from subsurface targets with respect to off-nadir surface clutter ones.
The third novel contribution of this thesis goes in the direction of high-level processing and in particular of automatic data analysis for accurate and fast extraction of relevant information from radar sounding data. To this extent, we propose a novel automatic method for retrieving the spatial position and radiometric properties of the subsurface layers based on Hidden Markov Models for radar response modeling and the Viterbi Algorithm for the inference step. Furthermore, a novel radargram enhancement and denoising technique has been developed to support the detection step. The effectiveness of the technique has been demonstrated on different radargrams acquired over the North Pole of Mars pointing out its superiority with respect to current state of the art techniques
«Improbe litigare». Ricerche sulle condotte non collaborative delle parti nel processo civile romano
Full text linkLa presente ricerca ha una peculiarità nell’oggetto ed un’altra nei fini. Nell’oggetto, perché non esamina un singolo istituto o un insieme coordinato di regole del processo romano ma propone piuttosto una «chiave di lettura» di quella realtà processuale alla luce di un’esigenza che è apparsa alla stessa in qualche misura connaturata: quella, che con lessico moderno potrebbe definirsi di «economia processuale», di assicurare la costante e adeguata cooperazione delle parti allo svolgimento del giudizio e il loro efficace contributo al conseguimento dei suoi scopi, manifestantesi con particolare pregnanza nella procedura per formulas in ragione delle stesse caratteristiche di quello schema processuale (centralità dell’iniziativa di parte, assenza di meccanismi pubblici di coazione diretta, sovrapposizione tra azione e pretesa sostanziale, ecc...). Nei fini, in quanto lo scopo dell’indagine in questa sede condotta non è quello di innovare le conoscenze già acquisite circa la forma o lo svolgimento del procedimento formulare, quanto piuttosto (e più semplicemente) quello di esaminare in una diversa prospettiva determinati profili della sua disciplina, individuando e mettendo in evidenza i diversi rimedi, eventualmente riconoscibili nel contesto della stessa, tendenti ad assicurare tale fondamentale esigenza di cooperazione delle parti e di regolarità del giudizio; a prescindere che gli stessi risultino come tali espressamente individuati o assolvano indirettamente a siffatta funzione senza esservi apertamen- te ricondotti. Nei quattro capitoli di cui si compone l’indagine (oltre all’introduzione e alla sintesi conclusiva) si indagano pertanto gli strumenti predisposti a garanzia della regolarità e dell’efficacia del giudizio in tre momenti o fasi fondamentali della vicenda processuale: la fase costitutiva del rapporto processuale e dell’introduzione del giudizio; quella dell’esercizio della pretesa giudiziale con la formulazione dell’intentio e il momento dell’attuazione concreta della pretesa processuale riconosciuta fondata, oltre ad esaminare - in via preliminare - una serie di istituti (non spe- cificamente riconducibili ad uno dei momenti così individuati) ma ricondotti dalle fonti alla funzione specifica di assicurare la coerenza tra le condotte delle parti e le finalità del giudizio. Il tutto con il duplice obiettivo di valutare - per un verso - se e in che misura gli strumenti processuali in quest’ottica accostabili si dimostrino effettivamente idonei a prevenire e reprimere gli eventuali comportamenti distorsivi (dilatori, ostruzionistici od opportunistici) provenienti dai litiganti e - per altro verso - se alla base degli stessi possano individuarsi degli elementi comuni o delle costanti funzionali che sembrino suggerire che nel sistema processuale dell’età formulare il suddetto obiettivo di regolarità ed efficienza della vicenda del giudizio risultasse perseguito in una forma efficace e in qualche modo coerente. Un interrogativo al quale si è ritenuto di poter ricondurre, come sarà evidenziato a conclusione dell’indagine, una risposta tendenzialmente affermativa (per quanto aperta a ulteriori approfondimenti)
Anion Exchange Membranes (AEMs), based on Polyamine Obtained by Modifying Polyketone, for Electrochemical Applications
Full text linkPolymeric anion exchange materials can be key components for forming membranes for use in several electrochemical applications. Polyketones seem particularly promising as materials for making anion exchange membranes (AEMs), not only because the starting monomers, carbon monoxide and ethylene, are relatively inexpensive (pointing to the feasibility of producing polyketone at a more competitive cost than other membranes), but also because the presence of 1,4-dicarbonyl units along the backbone is an important chemical feature for the purposes of chemically modifying these polymers. It allows for post-manufacturing functionalization through the so-called Paal-Knorr reaction, which introduces N-substituted pyrrole units along the polymer backbone. An anion exchange membrane (AEM) was made with a modified polyketone using a solvent casting method, followed by iodomethylation and ion exchange with KOH (PK-PDAPm). Every step in the synthetic process was confirmed by Fourier Transform InfraRed spectroscopy (FTIR). Nuclear Magnetic Resonance (NMR) spectroscopy was also used to characterize the structure of the modified polyketone in detail. The results obtained revealed the formation of a pyrrole ring along the polyketone backbone. Polyamines modified in this way are amenable to structural rearrangements to form N-substituted pyrrole crosslinked with dihydropyridine units. Scanning electron microscopy, differential scanning calorimetry, and X-ray diffraction techniques were also used to study the morphological, thermal, and structural characteristics of the modified polyketone, as well as the membranes derived therefrom. Thermogravimetric analyses demonstrated the thermal stability of the material up to 200oC, with no significant mass loss or degradation. The conductivity of the AEM was studied at temperatures up to 120oC, and the highest value of 9x10-4 S.cm-1 was reached at 120oC for the ionic conductivity of the membrane in iodide form, with values of the same order of magnitude (10-4 S.cm-1) for the membrane in OH form.
Polyamine (PA-SiNH2)m, membranes containing silica formed by sol-gel reactions of 3-aminopropyltriethoxysilane (APTES) in hydrolytic conditions were prepared by solution casting, followed by methylation and an ion exchange process, in an effort to improve the properties of the AEM. FTIR and NMR were used to investigate the chemical features of the silica and its interaction with the polyamine polymer. The influence of amino-functionalized silica (Si-NH2) on the properties of the membrane obtained was investigated. The results demonstrated: a significant improvement in thermal stability up to 300oC, and an increase in water uptake and ion exchange capacity by comparison with the AEM (PK-PDAPm) containing no silica. The maximum conductivity obtained for (PA-SiNH2)m-I and (PA-SiNH2)m-OH was 2.4 ×10-4 S cm-1 at 130oC, and 4.8 ×10-4 S cm-1 at 120oC.
These details may serve as an initial guide to the use of the above-described AEM in electrochemical applications
Numerical and Experimental Study on the Friction of Complex Surfaces
Full text linkWhenever two bodies are in contact due to a normal load and one is sliding against the other, a tangential force arises, as opposed to the motion. This force is called friction force and involves different mechanisms, such as asperity interactions, energy dissipation, chemical and physical alterations of the surface topography and wear. The friction coefficient is defined as the ratio between the friction force and the applied normal load. Despite this apparently simple definition, friction appears to be a very complex phenomenon, which also involves several aspects at both the micro- and nano-scale, including adhesion and phase transformation. Moreover, it plays a
key role in a variety of systems, and must be either enhanced (e.g. for locomotion) or minimized (e.g. in bearings), depending on the application. Considering friction as a multiscale problem, an analytical model has been proposed, starting from the literature, to describe friction in the presence of anisotropy, adhesion and wear between surfaces with hierarchical structures, e.g. self-similar. This model has been implemented in a MATLAB code for the design of the tribological properties of hierarchical surfaces and has been applied to study the ice friction, comparing analytical predictions with experimental tests. Furthermore, particular isotropic or anisotropic surface morphologies (e.g., microholes of different shapes and sizes) has been investigated for their influence to the static and dynamic friction coefficients with respect to a flat counterpart. In particular, it has been proved that the presence of grooves on surfaces could decrease the friction coefficients and thus reduce wear and energy dissipation. Experimental tests were performed with a setup realized ad hoc and the results were compared with full numerical simulations. If patterned surfaces showed that they can reduce sliding friction, other applications could require an increase in energy dissipation, e.g. to enhance the toughness of microfibers. Specifically, the applied method consists of introducing sliding frictional elements (sliding knots) in biological (silkworm silk, natural or degummed) and synthetic fibres, reproducing the concept of molecules, where the sacrificial bonds provide higher toughness to the molecular backbone, with a hidden length, which occurs after their breakage. A variety of slip knot topologies with different unfastening mechanisms have been investigated, including even complex knots usually adopted in the textile industry. The knots were made by manipulation of fibres with tweezers and the resulting knotted fibres were characterized through nanotensile tests to obtain their stress-strain curve until failure. The presence of sliding knots strongly increases the dissipated energy per unit mass, without compromising the structural integrity of the fibre itself
Choice, extension, conservation. From transfinite to finite proof methods in abstract algebra
Full text linkMaximality principles such as the ones going back to Kuratowski and Zorn ensure the existence of higher type ideal objects the use of which is commonly held indispensable for mathematical practice. The modern turn towards computational methods, which can be witnessed to have a strong influence on contemporary foundational studies, encourages a reassessment within a constructive framework of the methodological intricacies that go along with invocations of maximality principles. The common thread that can be followed through the chapters of this thesis is explained by the attempt to put the widespread use of ideal objects under constructive scrutiny. It thus walks the tracks of a revised Hilbert’s programme which has inspired a reapproach to constructive algebra by finitary means, and for which Scott’s entailment relations have already shown to provide a vital and utmost versatile tool. In this thesis several forms of the Kuratowski-Zorn Lemma are introduced and proved equivalent over constructive set theory; the notion of Jacobson radical is brought from commutative rings to a general ideal theory for single-conclusion entailment relations; a flexible conservation criterion of Scott for multi-conclusion entailment relations is put into action; elementary and constructive variants for algebraic extension theorems such as Sikorski’s on the injectivity of complete atomic Boolean algebras are phrased and proved in terms of entailment relations; and a point-free version of Sikora’s theorem on spaces of orderings of groups is obtained by a revisitation with syntactical means of some of the classical criteria for groups to be orderable
Different forms of (dis)affection with the organization: The positive influence of organizational identification on employees
Full text linkThis dissertation proposes the discussion of four empirical studies which show the validity of a new perspective within the social identity approach – the expanded model of organizational identification – and its applications in organizations. The social identity literature provides an important framework for understanding the reciprocal relationships between organizations and their employees, but traditional identity approach has largely neglected a new notion of organizational identification that includes other forms of attachment to the organization. Thus, the purpose of the present contribution is twofold: first, examining the validity of this new expanded perspective, which integrates organizational identification with other notions of identification, namely ambivalent identification, neutral identification and disidentification; and second, investigating its applications in organizational contexts, specifically by investigating how this approach is related to individuals’ outcomes. The first empirical study aims to provide further evidence for this model and to show discriminability and reliability of an Italian-language translation of Kreiner and Ashforth’s scales of a short version of the expanded model of organizational identification (EMOI) in an Italian speaking sample. Results provide good scale reliabilities, and confirmatory factor analyses demonstrate the good factorial validity of the short measure. We also tested the discriminant validity between organizational identification and affective commitment and we examined several antecedents of the four forms of identification. The second empirical study contributes to the understanding of the role of organizational identification for work-related stress by exploring the interactions between organizational identification and the other "problematic" dimensions of the expanded model in predicting employee strain. We hypothesized that ambivalent identification, neutral identification, and disidentification would moderate the negative relationship between organizational identification and exhaustion and ego depletion, such that the link between identification and strain would be stronger when the other dimensions are low. Results largely supported the hypotheses and show reliable interactions for disidentification and neutral identification and marginally significant moderation effects for ambivalent identification. Finally, we tested the interaction effects with a different outcome. Specifically, in the third study, we predicted a negative relationship between organizational identification and counterproductive work behaviors and a moderation of this link by ambivalent identification. We explored both overall counterproductive work behaviors (CWB) and also CWBs toward the organization (CWB-O), and CWBs toward other individuals (CWB-I). A survey-based study of 198 German employees revealed a moderating effect of ambivalent identification on the negative relationship between organizational identification and CWB, and CWB-O. Employees highly identified with their organization reported lower levels of CWB and CWB-O but - and as predicted - only when ambivalent identification was low. We then replicated the study examining CWB, and a scenario study of 228 American employees supported the previous findings: when organizational identification was high, participants in the low ambivalent condition reported lower levels of CWB-O than participants in the high ambivalent condition. The moderating effect of ambivalent and organizational identification was not significant on CWB-I in both studies. These findings provide new evidence for the positive influence of organizational identification under conditions of low ambivalence on counterproductive behaviors toward the organization. Limitations and practical implications of all studies are discussed