Optically active photoresponsive multifunctional polymeric materials

In the last year [1], Angiolini and co-workers have synthesized and investigated methacrylic polymers bearing in the side chain the chiral cyclic (S)-3-hydroxypyrrolidine moiety interposed between the main chain and the trans-azoaromatic chromophore, substituted or not in the 4’ position by an electron-withdrawing group. In these materials, the presence of a rigid chiral moiety of one prevailing absolute configuration favours the establishment of a chiral conformation of one prevailing helical handedness, at least within chain segments of the macromolecules, which can be observed by circular dichroism (CD). The simultaneous presence of the azoaromatic and chiral functionalities allows the polymers to display both the properties typical of dissymmetric systems (optical activity, exciton splitting of dichroic absorptions), as well as the features typical of photochromic materials (photorefractivity, photoresponsiveness, NLO properties). The first part of this research was to synthesize analogue homopolymers and copolymers based on bisazoaromatic moiety and compare their properties to those of the above mentioned analogue derivatives bearing only one azoaromatic chromophore in the side chain. We focused also the attention on the effects induced on the thermal and chiroptical behaviours by the insertion of particulars achiral comonomers characterized by different side-chain mobility and grown hindrance (MMA, tert-BMA and TrMA). On the other hand carbazole containing polymers [2] have attracted much attention because of their unique features. The use of these materials in advanced micro- and nanotechnologies spreads in many different applications such as photoconductive and photorefractive polymers, electroluminescent devices, programmable optical interconnections, data storage, chemical photoreceptors, NLO, surface relief gratings, blue emitting materials and holographic memory. The second part of the work was focused on the synthesis and the characterization polymeric derivatives bearing in the side chain carbazole or phenylcarbazole moieties linked to the (S)- 2-hydroxy succinimide or the (S)-3-hydroxy pyrrolidinyl ring as chiral groups covalently linked to the main chain through ester bonds. The last objective of this research was to design, synthesize, and characterize multifunctional methacrylic homopolymers and copolymers bearing three distinct functional groups (i.e. azoaromatic, carbazole and chiral group of one single configuration) directly linked in the side chain. This polymeric derivatives could be of potential interest for several advanced application fields, such as optical storage, waveguides, chiroptical switches, chemical photoreceptors, NLO, surface relief gratings, photoconductive materials, etc.

Sviluppo di metodologie di localizzazione nel contesto del Comprehensive Nuclear Test-Ban Treaty

Since the first underground nuclear explosion, carried out in 1958, the analysis of seismic signals generated by these sources has allowed seismologists to refine the travel times of seismic waves through the Earth and to verify the accuracy of the location algorithms (the ground truth for these sources was often known). Long international negotiates have been devoted to limit the proliferation and testing of nuclear weapons. In particular the Treaty for the comprehensive nuclear test ban (CTBT), was opened to signatures in 1996, though, even if it has been signed by 178 States, has not yet entered into force, The Treaty underlines the fundamental role of the seismological observations to verify its compliance, by detecting and locating seismic events, and identifying the nature of their sources. A precise definition of the hypocentral parameters represents the first step to discriminate whether a given seismic event is natural or not. In case that a specific event is retained suspicious by the majority of the State Parties, the Treaty contains provisions for conducting an on-site inspection (OSI) in the area surrounding the epicenter of the event, located through the International Monitoring System (IMS) of the CTBT Organization. An OSI is supposed to include the use of passive seismic techniques in the area of the suspected clandestine underground nuclear test. In fact, high quality seismological systems are thought to be capable to detect and locate very weak aftershocks triggered by underground nuclear explosions in the first days or weeks following the test. This PhD thesis deals with the development of two different seismic location techniques: the first one, known as the double difference joint hypocenter determination (DDJHD) technique, is aimed at locating closely spaced events at a global scale. The locations obtained by this method are characterized by a high relative accuracy, although the absolute location of the whole cluster remains uncertain. We eliminate this problem introducing a priori information: the known location of a selected event. The second technique concerns the reliable estimates of back azimuth and apparent velocity of seismic waves from local events of very low magnitude recorded by a trypartite array at a very local scale. For the two above-mentioned techniques, we have used the crosscorrelation technique among digital waveforms in order to minimize the errors linked with incorrect phase picking. The cross-correlation method relies on the similarity between waveforms of a pair of events at the same station, at the global scale, and on the similarity between waveforms of the same event at two different sensors of the try-partite array, at the local scale. After preliminary tests on the reliability of our location techniques based on simulations, we have applied both methodologies to real seismic events. The DDJHD technique has been applied to a seismic sequence occurred in the Turkey-Iran border region, using the data recorded by the IMS. At the beginning, the algorithm was applied to the differences among the original arrival times of the P phases, so the cross-correlation was not used. We have obtained that the relevant geometrical spreading, noticeable in the standard locations (namely the locations produced by the analysts of the International Data Center (IDC) of the CTBT Organization, assumed as our reference), has been considerably reduced by the application of our technique. This is what we expected, since the methodology has been applied to a sequence of events for which we can suppose a real closeness among the hypocenters, belonging to the same seismic structure. Our results point out the main advantage of this methodology: the systematic errors affecting the arrival times have been removed or at least reduced. The introduction of the cross-correlation has not brought evident improvements to our results: the two sets of locations (without and with the application of the cross-correlation technique) are very similar to each other. This can be commented saying that the use of the crosscorrelation has not substantially improved the precision of the manual pickings. Probably the pickings reported by the IDC are good enough to make the random picking error less important than the systematic error on travel times. As a further justification for the scarce quality of the results given by the cross-correlation, it should be remarked that the events included in our data set don’t have generally a good signal to noise ratio (SNR): the selected sequence is composed of weak events ( magnitude 4 or smaller) and the signals are strongly attenuated because of the large distance between the stations and the hypocentral area. In the local scale, in addition to the cross-correlation, we have performed a signal interpolation in order to improve the time resolution. The algorithm so developed has been applied to the data collected during an experiment carried out in Israel between 1998 and 1999. The results pointed out the following relevant conclusions: a) it is necessary to correlate waveform segments corresponding to the same seismic phases; b) it is not essential to select the exact first arrivals; and c) relevant information can be also obtained from the maximum amplitude wavelet of the waveforms (particularly in bad SNR conditions). Another remarkable point of our procedure is that its application doesn’t demand a long time to process the data, and therefore the user can immediately check the results. During a field survey, such feature will make possible a quasi real-time check allowing the immediate optimization of the array geometry, if so suggested by the results at an early stage.

Aldo Rossi, autobiografia scientifica: scrittura come progetto. Indagine critica tra scrittura e progetto di architettura

«In altri termini mi sfuggiva e ancora oggi mi sfugge gran parte del significato dell’evoluzione del tempo; come se il tempo fosse una materia che osservo dall’esterno. Questa mancanza di evoluzione è fonte di alcune mie sventure ma anche mi appartiene con gioia.» Aldo Rossi, Autobiografia scientifica. The temporal dimension underpinning the draft of Autobiografia scientifica by Aldo Rossi may be referred to what Lucien Lévy-Bruhl, the well-known French anthropologist, defines as “primitive mentality” and “prelogical” conscience : the book of life has lost its page numbers, even punctuation. For Lévy-Bruhl, but certainly for Rossi, life or its summing up becomes a continuous account of ellipses, gaps, repetitions that may be read from left to right or viceversa, from head to foot or viceversa without distinction. Rossi’s autobiographical writing seems to accept and support the confusion with which memories have been collected, recording them after the order memory gives them in the mental distillation or simply according to the chronological order in which they have happened. For Rossi, the confusion reflects the melting of memory elements into a composite image which is the result of a fusion. He is aware that the same sap pervades all memories he is going to put in order: each of them has got a common denominator. Differences have diminished, almost faded; the quick glance is prevalent over the distinction of each episode. Rossi’s writing is beyond the categories dependent on time: past and present, before and now. For Rossi, the only repetition – the repetition the text will make possible for an indefinite number of times – gives peculiarity to the event. As Gilles Deleuze knows, “things” may only last as “singleness”: more frequent the repetition is, more singular is the memory phenomenon that recurs, because only what is singular magnifies itself and happens endlessly forever. Rossi understands that “to raise the first time to nth forever”, repetition becomes glorification . It may be an autobiography that, celebrating the originality, enhances the memory event in the repetition; in fact it greatly differs from the biographical reproduction, in which each repetition is but a weaker echo, a duller copy, provided with a smaller an smaller power in comparison with the original. Paradoxically, for Deleuze the repetition asserts the originality and singularity of what is repeated. Rossi seems to share the thought expressed by Kierkegaard in the essay Repetition: «The hope is a graceful maiden slipping through your fingers; the memory of an elderly woman, indeed pretty, but never satisfactory if necessary; the repetition is a loved friend you are never tired of, as it is only the new to make you bored. The old never bores you and its presence makes you happy [...] life is but a repetition [...] here is the beauty of life» . Rossi knows well that repetition hints at the lasting stability of cosmic time. Kierkegaard goes on: «The world exists, and it exists as a repetition» . Rossi devotes himself, on purpose and in all conscience, to collect, to inventory and «to review life», his own life, according to a recovery not from the past but of the past: a search work, the «recherche du temps perdu», as Proust entitled his masterpiece on memory. If you want the past time to be not wasted, you must give it presence. «Memoria e specifico come caratteristiche per riconoscere se stesso e ciò che è estraneo mi sembravano le più chiare condizioni e spiegazioni della realtà. Non esiste uno specifico senza memoria, e una memoria che non provenga da un momento specifico; e solo questa unione permette la conoscenza della propria individualità e del contrario (self e non-self)» . Rossi wants to understand himself, his own character; it is really his own character that requires to be understood, to increase its own introspective ability and intelligence. «Può sembrare strano che Planck e Dante associno la loro ricerca scientifica e autobiografica con la morte; una morte che è in qualche modo continuazione di energia. In realtà, in ogni artista o tecnico, il principio della continuazione dell’energia si mescola con la ricerca della felicità e della morte» . The eschatological incipit of Rossi’s autobiography refers to Freud’s thought in the exact circularity of Dante’s framework and in as much exact circularity of the statement of the principle of the conservation of energy: in fact it was Freud to connect repetition to death. For Freud, the desire of repetition is an instinct rooted in biology. The primary aim of such an instinct would be to restore a previous condition, so that the repeated history represents a part of the past (even if concealed) and, relieving the removal, reduces anguish and tension. So, Freud ask himself, what is the most remote state to which the instinct, through the repetition, wants to go back? It is a pre-vital condition, inorganic of the pure entropy, a not-to-be condition in which doesn’t exist any tension; in other words, Death. Rossi, with the theme of death, introduces the theme of circularity which further on refers to the sense of continuity in transformation or, in the opposite way, the transformation in continuity. «[...] la descrizione e il rilievo delle forme antiche permettevano una continuità altrimenti irripetibile, permettevano anche una trasformazione, una volta che la vita fosse fermata in forme precise» . Rossi’s attitude seems to hint at the reflection on time and – in a broad sense – at the thought on life and things expressed by T.S. Eliot in Four Quartets: «Time present and time past / Are both perhaps present in time future, / And time future is contained in time past. / I all time is eternally present / All time is unredeemable. / What might have been is an abstraction / Remaining perpetual possibility / Only in a word of speculation. / What might have been and what has been / Point to one end, which is always present. [...]» . Aldo Rossi’s autobiographical story coincides with the description of “things” and the description of himself through the things in the exact parallel with craft or art. He seems to get all things made by man to coincide with the personal or artistic story, with the consequent immediate necessity of formulating a new interpretation: the flow of things has never met a total stop; all that exists nowadays is but a repetition or a variant of something existing some time ago and so on, without any interruption until the early dawnings of human life. Nevertheless, Rossi must operate specific subdivisions inside the continuous connection in time – of his time – even if limited by a present beginning and end of his own existence. This artist, as an “historian” of himself and his own life – as an auto-biographer – enjoys the privilege to be able to decide if and how to operate the cutting in a certain point rather than in another one, without being compelled to justify his choice. In this sense, his story is a matter very ductile and flexible: a good story-teller can choose any moment to start a certain sequence of events. Yet, Rossi is aware that, beyond the mere narration, there is the problem to identify in history - his own personal story – those flakings where a clean cut enables the separation of events of different nature. In order to do it, he has to make not only an inventory of his own “things”, but also to appeal to authority of the Divina Commedia started by Dante when he was 30. «A trent’anni si deve compiere o iniziare qualcosa di definitivo e fare i conti con la propria formazione» . For Rossi, the poet performs his authority not only in the text, but also in his will of setting out on a mystical journey and handing it down through an exact descriptive will. Rossi turns not only to the authority of poetry, but also evokes the authority of science with Max Plank and his Scientific Autobiography, published, in Italian translation, by Einaudi, 1956. Concerning Planck, Rossi resumes an element seemingly secondary in hit account where the German physicist «[...] risale alle scoperte della fisica moderna ritrovando l’impressione che gli fece l’enunciazione del principio di conservazione dell’energia; [...]» . It is again the act of describing that links Rossi to Planck, it is the description of a circularity, the one of conservation of energy, which endorses Rossi’s autobiographical speech looking for both happiness and death. Rossi seems to agree perfectly to the thought of Planck at the opening of his own autobiography: «The decision to devote myself to science was a direct consequence of a discovery which was never ceased to arouse my enthusiasm since my early youth: the laws of human thought coincide with the ones governing the sequences of the impressions we receive from the world surrounding us, so that the mere logic can enable us to penetrate into the latter one’s mechanism. It is essential that the outer world is something independent of man, something absolute. The search of the laws dealing with this absolute seems to me the highest scientific aim in life» . For Rossi the survey of his own life represents a way to change the events into experiences, to concentrate the emotion and group them in meaningful plots: «It seems, as one becomes older. / That the past has another pattern, and ceases to be a mere sequence [...]» Eliot wrote in Four Quartet, which are a meditation on time, old age and memory . And he goes on: «We had the experience but missed the meaning, / And approach to the meaning restores the experience / In a different form, beyond any meaning [...]» . Rossi restores in his autobiography – but not only in it – the most ancient sense of memory, aware that for at least 15 centuries the Latin word memoria was used to show the activity of bringing back images to mind: the psychology of memory, which starts with Aristotele (De Anima), used to consider such a faculty totally essential to mind. Keith Basso writes: «The thought materializes in the form of “images”» . Rossi knows well – as Aristotele said – that if you do not have a collection of mental images to remember – imagination – there is no thought at all. According to this psychological tradition, what today we conventionally call “memory” is but a way of imagining created by time. Rossi, entering consciously this stream of thought, passing through the Renaissance ars memoriae to reach us gives a great importance to the word and assumes it as a real place, much more than a recollection, even more than a production and an emotional elaboration of images.

Transport infrastructure and economic development in least developed countries: the case of Afghanistan

This PhD thesis tries to show the impact of transport infrastructure in economic development in least developed countries and in particular in the case of Afghanistan. Some least developed countries during 1990 to 1999 experienced lack of investment in transportation. Lack of investment further increased the economic development gap between developed and least developed countries. Moreover, lack of literature and research in poor countries such as Afghanistan encouraged me to do my research in this country in order to unveil the problems, facing poor people who are living in inaccessible places and suffer from lack of economic opportunities and long term unemployment. This thesis shows the effect of inaccessibility and immobility in economic opportunities and basic social services in Afghanistan. This thesis is important because it covers the role of transport infrastructures at the moment that international community promised to rebuild the infrastructures of post conflict Afghanistan.

Wavelet analysis of heart rate variability related to nocturnal frontal lobe epilepsy seizures

Introduction: Nocturnal frontal lobe epilepsy (NFLE) is a distinct syndrome of partial epilepsy whose clinical features comprise a spectrum of paroxysmal motor manifestations of variable duration and complexity, arising from sleep. Cardiovascular changes during NFLE seizures have previously been observed, however the extent of these modifications and their relationship with seizure onset has not been analyzed in detail. Objective: Aim of present study is to evaluate NFLE seizure related changes in heart rate (HR) and in sympathetic/parasympathetic balance through wavelet analysis of HR variability (HRV). Methods: We evaluated the whole night digitally recorded video-polysomnography (VPSG) of 9 patients diagnosed with NFLE with no history of cardiac disorders and normal cardiac examinations. Events with features of NFLE seizures were selected independently by three examiners and included in the study only if a consensus was reached. Heart rate was evaluated by measuring the interval between two consecutive R-waves of QRS complexes (RRi). RRi series were digitally calculated for a period of 20 minutes, including the seizures and resampled at 10 Hz using cubic spline interpolation. A multiresolution analysis was performed (Daubechies-16 form), and the squared level specific amplitude coefficients were summed across appropriate decomposition levels in order to compute total band powers in bands of interest (LF: 0.039062 - 0.156248, HF: 0.156248 - 0.624992). A general linear model was then applied to estimate changes in RRi, LF and HF powers during three different period (Basal) (30 sec, at least 30 sec before seizure onset, during which no movements occurred and autonomic conditions resulted stationary); pre-seizure period (preSP) (10 sec preceding seizure onset) and seizure period (SP) corresponding to the clinical manifestations. For one of the patients (patient 9) three seizures associated with ictal asystole were recorded, hence he was treated separately. Results: Group analysis performed on 8 patients (41 seizures) showed that RRi remained unchanged during the preSP, while a significant tachycardia was observed in the SP. A significant increase in the LF component was instead observed during both the preSP and the SP (p<0.001) while HF component decreased only in the SP (p<0.001). For patient 9 during the preSP and in the first part of SP a significant tachycardia was observed associated with an increased sympathetic activity (increased LF absolute values and LF%). In the second part of the SP a progressive decrease in HR that gradually exceeded basal values occurred before IA. Bradycardia was associated with an increase in parasympathetic activity (increased HF absolute values and HF%) contrasted by a further increase in LF until the occurrence of IA. Conclusions: These data suggest that changes in autonomic balance toward a sympathetic prevalence always preceded clinical seizure onset in NFLE, even when HR changes were not yet evident, confirming that wavelet analysis is a sensitive technique to detect sudden variations of autonomic balance occurring during transient phenomena. Finally we demonstrated that epileptic asystole is associated with a parasympathetic hypertonus counteracted by a marked sympathetic activation.

Troposphere Calibration Techniques for Deep Space Probe Tracking

Ground-based Earth troposphere calibration systems play an important role in planetary exploration, especially to carry out radio science experiments aimed at the estimation of planetary gravity fields. In these experiments, the main observable is the spacecraft (S/C) range rate, measured from the Doppler shift of an electromagnetic wave transmitted from ground, received by the spacecraft and coherently retransmitted back to ground. If the solar corona and interplanetary plasma noise is already removed from Doppler data, the Earth troposphere remains one of the main error sources in tracking observables. Current Earth media calibration systems at NASA’s Deep Space Network (DSN) stations are based upon a combination of weather data and multidirectional, dual frequency GPS measurements acquired at each station complex. In order to support Cassini’s cruise radio science experiments, a new generation of media calibration systems were developed, driven by the need to achieve the goal of an end-to-end Allan deviation of the radio link in the order of 3×〖10〗^(-15) at 1000 s integration time. The future ESA’s Bepi Colombo mission to Mercury carries scientific instrumentation for radio science experiments (a Ka-band transponder and a three-axis accelerometer) which, in combination with the S/C telecommunication system (a X/X/Ka transponder) will provide the most advanced tracking system ever flown on an interplanetary probe. Current error budget for MORE (Mercury Orbiter Radioscience Experiment) allows the residual uncalibrated troposphere to contribute with a value of 8×〖10〗^(-15) to the two-way Allan deviation at 1000 s integration time. The current standard ESA/ESTRACK calibration system is based on a combination of surface meteorological measurements and mathematical algorithms, capable to reconstruct the Earth troposphere path delay, leaving an uncalibrated component of about 1-2% of the total delay. In order to satisfy the stringent MORE requirements, the short time-scale variations of the Earth troposphere water vapor content must be calibrated at ESA deep space antennas (DSA) with more precise and stable instruments (microwave radiometers). In parallel to this high performance instruments, ESA ground stations should be upgraded to media calibration systems at least capable to calibrate both troposphere path delay components (dry and wet) at sub-centimetre level, in order to reduce S/C navigation uncertainties. The natural choice is to provide a continuous troposphere calibration by processing GNSS data acquired at each complex by dual frequency receivers already installed for station location purposes. The work presented here outlines the troposphere calibration technique to support both Deep Space probe navigation and radio science experiments. After an introduction to deep space tracking techniques, observables and error sources, in Chapter 2 the troposphere path delay is widely investigated, reporting the estimation techniques and the state of the art of the ESA and NASA troposphere calibrations. Chapter 3 deals with an analysis of the status and the performances of the NASA Advanced Media Calibration (AMC) system referred to the Cassini data analysis. Chapter 4 describes the current release of a developed GNSS software (S/W) to estimate the troposphere calibration to be used for ESA S/C navigation purposes. During the development phase of the S/W a test campaign has been undertaken in order to evaluate the S/W performances. A description of the campaign and the main results are reported in Chapter 5. Chapter 6 presents a preliminary analysis of microwave radiometers to be used to support radio science experiments. The analysis has been carried out considering radiometric measurements of the ESA/ESTEC instruments installed in Cabauw (NL) and compared with the requirements of MORE. Finally, Chapter 7 summarizes the results obtained and defines some key technical aspects to be evaluated and taken into account for the development phase of future instrumentation.

Does improvisation lead to outcome deviation? A conceptual framework of improvisation, its antecedents and outcome deviation

Management and organization literature has extensively noticed the crucial role that improvisation assumes in organizations, both as a learning process (Miner, Bassoff & Moorman, 2001), a creative process (Fisher & Amabile, 2008), a capability (Vera & Crossan, 2005), and a personal disposition (Hmielesky & Corbett, 2006; 2008). My dissertation aims to contribute to the existing literature on improvisation, addressing two general research questions: 1) How does improvisation unfold at an individual level? 2) What are the potential antecedents and consequences of individual proclivity to improvise? This dissertation is based on a mixed methodology that allowed me to deal with these two general research questions and enabled a constant interaction between the theoretical framework and the empirical results. The selected empirical field is haute cuisine and the respondents are the executive chefs of the restaurants awarded by Michelin Guide in 2010 in Italy. The qualitative section of the dissertation is based on the analysis of 26 inductive case studies and offers a multifaceted contribution. First, I describe how improvisation works both as a learning and creative process. Second, I introduce a new categorization of individual improvisational scenarios (demanded creative improvisation, problem solving improvisation, and pure creative improvisation). Third, I describe the differences between improvisation and other creative processes detected in the field (experimentation, brainstorming, trial and error through analytical procedure, trial and error, and imagination). The quantitative inquiry is founded on a Structural Equation Model, which allowed me to test simultaneously the relationships between proclivity to improvise and its antecedents and consequences. In particular, using a newly developed scale to measure individual proclivity to improvise, I test the positive influence of industry experience, self-efficacy, and age on proclivity to improvise and the negative impact of proclivity to improvise on outcome deviation. Theoretical contributions and practical implications of the results are discussed.

Procedures of quality control and data analysis of multi-site ground-based observations for the absolute flux calibration of Gaia

The Gaia space mission is a major project for the European astronomical community. As challenging as it is, the processing and analysis of the huge data-flow incoming from Gaia is the subject of thorough study and preparatory work by the DPAC (Data Processing and Analysis Consortium), in charge of all aspects of the Gaia data reduction. This PhD Thesis was carried out in the framework of the DPAC, within the team based in Bologna. The task of the Bologna team is to define the calibration model and to build a grid of spectro-photometric standard stars (SPSS) suitable for the absolute flux calibration of the Gaia G-band photometry and the BP/RP spectrophotometry. Such a flux calibration can be performed by repeatedly observing each SPSS during the life-time of the Gaia mission and by comparing the observed Gaia spectra to the spectra obtained by our ground-based observations. Due to both the different observing sites involved and the huge amount of frames expected (≃100000), it is essential to maintain the maximum homogeneity in data quality, acquisition and treatment, and a particular care has to be used to test the capabilities of each telescope/instrument combination (through the “instrument familiarization plan”), to devise methods to keep under control, and eventually to correct for, the typical instrumental effects that can affect the high precision required for the Gaia SPSS grid (a few % with respect to Vega). I contributed to the ground-based survey of Gaia SPSS in many respects: with the observations, the instrument familiarization plan, the data reduction and analysis activities (both photometry and spectroscopy), and to the maintenance of the data archives. However, the field I was personally responsible for was photometry and in particular relative photometry for the production of short-term light curves. In this context I defined and tested a semi-automated pipeline which allows for the pre-reduction of imaging SPSS data and the production of aperture photometry catalogues ready to be used for further analysis. A series of semi-automated quality control criteria are included in the pipeline at various levels, from pre-reduction, to aperture photometry, to light curves production and analysis.

Evaluation of slope stability under water and seismic load through the Minimum Lithostatic Deviation method

The main objective of this thesis is to obtain a better understanding of the methods to assess the stability of a slope. We have illustrated the principal variants of the Limit Equilibrium (LE) method found in literature, focalizing our attention on the Minimum Lithostatic Deviation (MLD) method, developed by Prof. Tinti and his collaborators (e.g. Tinti and Manucci, 2006, 2008). We had two main goals: the first was to test the MLD method on some real cases. We have selected the case of the Vajont landslide with the objective to reconstruct the conditions that caused the destabilization of Mount Toc, and two sites in the Norwegian margin, where failures has not occurred recently, with the aim to evaluate the present stability state and to assess under which conditions they might be mobilized. The second goal was to study the stability charts by Taylor and by Michalowski, and to use the MLD method to investigate the correctness and adequacy of this engineering tool.