Decision Making in Complex Environments: an adaptive network approach

In this thesis we investigate decision making in complex environments using adaptive network models. We first focus on the problem of consensus decision making in large animal groups. Each individual has an internal state that models its choice among the possible q alternatives and we assume that each individual updates its internal state using a majority rule, if it is connected to other individuals, or using a probabilistic rule. In this case, if the individual has no information, the choice shall be totally random, otherwise the probabilistic rule shall have a bias toward one of the q choices, measured by a parameter hi. The individuals shall also update their neighbourhood adaptively, which is modelled by a link creation/ link destruction process with an effective rate z . We show that the system, if there are no informed individuals, undergoes a I order phase transition at a give value, 17z , between a disordered phase and a phase were consensus is reached. When the number of informed individuals increases, the first order phase transition remains, until one reaches a critical value of informed individuals above which the system is no more critical. We also prove that, for z in a critical range, the removal of knowledgeable individuals may induce a transition to a phase where the group is no able to reach a consensual decision. We apply these results to interpret some data on seasonal migrations of Atlantic Bluefin Tuna. We, then, build a model to describe the emergence of hierarchical structures in societies of rational self-interested agents. This model constitutes a highly stylised model for human societies. The decision-making problem of the agents, in this situation, is to which other agent to connect itself. We model the preference of agents of that society for connecting to more prominent agents with a parameter \u3b2. We show that there exists a sharp transition between a disordered equalitarian society and an ordered hierarchical society as beta increases. Moreover, we prove that, in a hierarchical society, social mobility is almost impossible, which captures behaviours that have been observed in real societies

Sexing up the international

This thesis takes sexuality as its subject matter and uses a methodology informed by postcolonial studies to explore new possibilities for thinking about the international, its construction, and its contemporary politics. I argue that postcolonial readings of sexuality can impel us to rethink the meanings and politics of international theory and to challenge notions that have come to appear fixed and unchanging. The thesis canvasses how such an intervention might occur – calling especially for a focus on the local and the everyday – and considers both the utility and the limits of the contributions sexuality might make to a rethinking of international theory. My arguments are made with reference to a series of specific examples from contemporary East and Southeast Asia: the nationalistically imbued gendered and sexed figures of the national serviceman and the Singapore Girl in Singapore; the political and social repercussions of the trial of former Malaysian Deputy Prime Minister Anwar Ibrahim on charges of sodomy; newly emerging homosexual identities in Hong Kong; and the connections between sexuality and disease that inform the Thai response to HIV/AIDS. These case studies exemplify some of the ways in which sexuality can work to recast traditional scholarly understandings of the international. They also illuminate a series of aspects that shape the encounter between sexuality and the international, encompassing issues of nationalism, globalization, metaphor, spatiality and knowledge politics. Through my analysis of these issues, I argue for a broadening out of the source materials that inform knowledge about the international and the pursuit of alternative modes of reading processes of international change and exchange. I contend that scholarship of the international needs to pay more attention to instances where the borders separating everyday, national and international spaces break down, and where we might detect new forms of knowledge about the nature, politics and functioning of the international realm

Linear response theory for complex systems

We present in this work a proposal for modeling perturbation on complex systems. Kubo's Theorem can be derived only for systems whose correlation function is stationary. When the correlation function becomes non - stationary Kubo's linear response function can be extended in two different ways. We show - first for dichotomous systems then for general ones - that this corresponds in assuming that the perturbation acts either on the event generating operator (thus perturbing the leading process without affecting the event occurrence time) or on the global interaction (then perturbing our waiting time distribution). We call the first approach "phenomenological" and the second one "dynamical". We assert that the “dynamical” approach is the one, which better describes our processes and then extend this theory to non dichotomous processes. In this case, besides the linear response term, a new term appears. We then show that for a harmonic perturbation the response is a dumped harmonic perturbation with amplitude a phase depending on depending on the peculiar characteristics of the system . We then illustrate an experimental result on Liquid crystals dynamics that confirms our theory

Suitability of ground-based SfM-MVS for monitoring glacial and periglacial processes

Photo-based surface reconstruction is rapidly emerging as an alternative survey technique to lidar (light detection and ranging) in many fields of geoscience fostered by the recent development of computer vision algorithms such as structure from motion (SfM) and dense image matching such as multi-view stereo (MVS). The objectives of this work are to test the suitability of the ground-based SfM-MVS approach for calculating the geodetic mass balance of a 2.1km2 glacier and for detecting the surface displacement of a neighbouring active rock glacier located in the eastern Italian Alps. The photos were acquired in 2013 and 2014 using a digital consumer-grade camera during single-day field surveys. Airborne laser scanning (ALS, otherwise known as airborne lidar) data were used as benchmarks to estimate the accuracy of the photogrammetric digital elevation models (DEMs) and the reliability of the method. The SfM-MVS approach enabled the reconstruction of high-quality DEMs, which provided estimates of glacial and periglacial processes similar to those achievable using ALS. In stable bedrock areas outside the glacier, the mean and the standard deviation of the elevation difference between the SfM-MVS DEM and the ALS DEM was-0.42 \ub1 1.72 and 0.03 \ub1 0.74 m in 2013 and 2014, respectively. The overall pattern of elevation loss and gain on the glacier were similar with both methods, ranging between-5.53 and + 3.48 m. In the rock glacier area, the elevation difference between the SfM-MVS DEM and the ALS DEM was 0.02 \ub1 0.17 m. The SfM-MVS was able to reproduce the patterns and the magnitudes of displacement of the rock glacier observed by the ALS, ranging between 0.00 and 0.48 m per year. The use of natural targets as ground control points, the occurrence of shadowed and low-contrast areas, and in particular the suboptimal camera network geometry imposed by the morphology of the study area were the main factors affecting the accuracy of photogrammetric DEMs negatively. Technical improvements such as using an aerial platform and/or placing artificial targets could significantly improve the results but run the risk of being more demanding in terms of costs and logistics

Mechanically induced oxidation of alcohols to aldehydes and ketones in ambient air: Revisiting TEMPO-assisted oxidations

The present work addresses the development of an eco-friendly and cost-efficient protocol for the oxidation of primary and secondary alcohols to the corresponding aldehydes and ketones by mechanical processing under air. Ball milling was shown to promote the quantitative conversion of a broad set of alcohols into carbonyl compounds with no trace of an over-oxidation to carboxylic acids. The mechanochemical reaction exhibited higher yields and rates than the classical, homogeneous, TEMPO-based oxidation

SAF-IS: a Spatial Annotation Free Framework for Instance Segmentation of Surgical Tools

Instance segmentation of surgical instruments is a long-standing research problem, crucial for the development of many applications for computer-assisted surgery. This problem is commonly tackled via fully-supervised training of deep learning models, requiring expensive pixel-level annotations to train. In this work, we develop a framework for instance segmentation not relying on spatial annotations for training. Instead, our solution only requires binary tool masks, obtainable using recent unsupervised approaches, and binary tool presence labels, freely obtainable in robot-assisted surgery. Based on the binary mask information, our solution learns to extract individual tool instances from single frames, and to encode each instance into a compact vector representation, capturing its semantic features. Such representations guide the automatic selection of a tiny number of instances (8 only in our experiments), displayed to a human operator for tool-type labelling. The gathered information is finally used to match each training instance with a binary tool presence label, providing an effective supervision signal to train a tool instance classifier. We validate our framework on the EndoVis 2017 and 2018 segmentation datasets. We provide results using binary masks obtained either by manual annotation or as predictions of an unsupervised binary segmentation model. The latter solution yields an instance segmentation approach completely free from spatial annotations, outperforming several state-of-the-art fully-supervised segmentation approaches

Angular deflection of rotary nickel titanium files: a comparative study

A new manufacturing method of twisting nickel titanium wire to produce rotary nickel titanium (RNT) files has recently been developed. The aim of the present study was to evaluate whether the new manufacturing process increased the angular deflection of RNT files, by comparing instruments produced using the new manufacturing method (Twisted Files) versus instruments produced with the traditional grinding process. Testing was performed on a total of 40 instruments of the following commercially available RNT files: Twisted Files (TF), Profile, K3 and M2 (NRT). All instruments tested had the same dimensions (taper 0.06 and tip size 25). Test procedures strictly followed ISO 3630-1. Data were collected and statistically analyzed by means ANOVA test. The results showed that TF demonstrated significantly higher average angular deflection levels (P<0.05), than RNT manufactured by a grinding process. Since angular deflection represent the amount of rotation (and consequently deformation) that a RNT file can withstand before torsional failure, such a significant improvement is a favorable property for the clinical use of the tested RNT files

Microorganisms of food ice cubes and their transfer to drinks

The present work was carried out to investigate the microbiological characteristics of the ice cubes produced at different levels: 1) home-made (HM) from domestic freezers; 2) produced by ice machines in bars and pubs (BP); 3) produced by ice industries (IN). BP samples were collected from the box stocks. HM and BP samples were transferred into sterile stomacher bags. IN samples were provided in the manufacturers’ plastic bags. Samples were transported into thermal insulated boxes. Five samples per each production level, forming a total of 15 samples (HM1-HM5, BP1-BP5, IN1-IN5), were collected in duplicate in two consecutive months. Each ice sample was thawed in 1 L sterile Dhuram’s bottle at room temperature and subjected to the membrane filtration analyses. Total mesophilic microorganisms (TMM), total psychrotrophic microorganisms (TPM), pseudomonads, members of the Enterobacteriaceae family, coliforms, enterococci, yeasts and moulds were investigated. When the amounts of colonies were uncountable, 1 mL of sample was directly inoculated into agar media. All results were expressed as colony forming units (CFU)/100 mL of thawed ice. TMM were in the range 100-9600, 312-6300 and 130-4000 for HM, BP and IN samples, respectively. Three HM and two IN samples were negative for the presence of TPM. The highest concentration (960) was found for IN2. Pseudomonads were detected in all HM samples but the highest levels were registered for BP1 (390) and IN2 (384). Except IN4, Enterobacteriaceae were found in all samples. All INs and 4 HM samples did not displayed coliforms. By contrast, they were hosted in all BP samples, ranging from 1 to 184. Enterococci were never found in HM samples, but detected in two INs and 3 BPs. Except IN1, moulds were always registered, while yeasts developed from the majority of HM and IN samples and two BP samples. The colonies representative for the different morphologies were randomly picked up from plates, purified to homogeneity and subjected to a phenotypic grouping. Yeasts and bacteria were subjected to the genetic identification by sequencing of D1/D2 domains of 26S rRNA gene and partial sequencing of 16S rRNA gene, respectively, while moulds were identified phenotypically. So far, the species mostly represented among bacteria, as evaluated only by the forward 16S rRNA gene sequence, were Bacillus spp., Pseudomonas spp., Pantoea spp., Pantoea agglomerans, Enterococcus faecium, and Agrobacterium tumefaciens. Candida intermedia and Pichia guillermondii were identified among yeasts and Penicillium spp. among moulds. The work was also aimed to monitor the microbial transfer from ice to humans through drinks. To this purpose, each microorganism was inoculated singly in sterile mineral water to produce contaminated ice cubes using disposable ice cube trays. Inoculums occurred at the highest concentrations found in the ice cubes analysed. The concentrations of the microorganisms were followed in six different types of drinks, including alcoholic (vodka and whiskey), moderate alcoholic (Martini), sparkling (tonic water), sugary (peach tea) and sugary sparkling (coke) drinks. In order to simulate the contamination of drinks by ice during consumption, six ice cubes (corresponding to 60 mL) containing each microorganism were added to 100 mL of each drink (simulating a bar administration) in sterile cups and, after 1 h, the entire volume was analysed by membrane filtration. A physiological solution was used as control. So far, the tests were performed with Penicillium spp. and P. agglomerans. Penicillium was not influenced by the different drinks, since, after 1 h, its level did not change. Regarding P. agglomerans, which is an opportunistic pathogen causing urinary tract infections, its concentration in peach tea was superimposable to that found in physiological solution, while it decreased in all other drinks. In particular, the concentration of this bacterium almost halved in vodka, coke and tonic water, diminished consistently in Martini and completely disappeared in whiskey. Experimentations are in progress to determine the behaviour of the other microorganisms in these systems. These data evidenced that the worst hygienic characteristics were found in BP samples, while the majority of ice cubes produced in specialized industries were characterized by acceptable microbiological parameters. This work indicated that the concentration of P. agglomerans is reduced by alcohol and CO2, but further in vivo assays are necessary to better clarify their role on the other ice microorganisms

Hyaluronan Produced by Smooth Muscle Cells Plays a Critical Role in Neointima Formation

Large body of evidence supports the idea that microenvironment plays a critical role in several pathologies including atherosclerosis and cancer. The amount of hyaluronan (HA) is involved in the microenvironment alterations and the concentration of this polymer reflects the progression of the diseases promoting neoangiogenesis, cell migration, and inflammation. The HA synthesis is regulated by several factors: UDP sugar precursors availability and the phosphorylation of synthetic enzyme HAS2 as well as specific drugs reducing the UDP precursors. The HAS2 phosphorylation is done by AMP kinase, a sensor of cell energy. When the cells have low energy, AMP kinase is activated and modifies covalently the regulatory enzymes, blocking all biosynthetic processes and activating the energy producing metabolism. It was recently reported that the hexosamine biosynthetic pathway (HBP) may increase the concentration of HA precursor UDP-N-acetylglucosamine (UDP-GlcNAc) leading to an increase of HA synthesis. We demonstrated that the increase of HA synthesis depends on the HAS2 post translational modification O-GlcNAcylation, which increases HA secretion modifying a residue different from the phosphorylation site of AMP kinase. In this report we highlighted the critical aspects of the post translational HAS2 regulation and its influence on HA synthesis

A critical analysis of Popper's experiment

An experiment which could decide against the Copenhagen interpretation of quantum mechanics has been proposed by K. Popper and, subsequently, it has been criticized by M.J. Collett and R. Loudon. Here we show that both the above mentioned arguments are not correct because they are based on a misuse of basic quantum rules.Comment: 12 pages, 3 figures, RevTex; to be published on PR