492 research outputs found

    The data that we do (not) have: studying drug trafficking and organised crime in Africa

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    An increasing amount of reports highlights the growing salience of drug trafficking in Africa. Yet the evidence-base for this claim remains problematic. Stemming from a critical approach to social sciences’ epistemology, the paper explores how drug trafficking data are framed, produced and shared. Building on an extensive literature review and key interviews, it provides an in-depth analysis of both the main open source drug trafficking metrics (at UN, US and EU level), and the inner working of anti-drug trafficking agencies in key African countries, i.e. Nigeria, Senegal and Mali. The analysis shows that politicised framings, practical challenges and methodological inconsistencies affect drug trafficking knowledge production, especially in Africa. The paper therefore suggests to treat drug trafficking data – both quantitative and qualitative ‘evidence’ – not as proxies that would reveal ‘the reality’ of criminal under- and over-worlds ‘out there’, but performances whose appearance and disappearance is part and parcel of the mechanics of state (un)making. Anchoring the interpretation of drug trafficking data to the dynamics of protection and extraction characterising parallel modes of governance in the post-colonial world leads to the acknowledgement that the absence of reliable data is not a mere knowledge gap, but a datum in itself that calls for interpretation and investigation

    Experimental demonstration of a novel heterogeneously integrated III-V on Si microlaser

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    In this work we present the first experimental demonstration of a novel class of heterogeneously integrated III-V-on-silicon microlasers. We first show that by coupling a silicon cavity to a III-V wire, the interaction between the propagating mode in the III-V wire and the cavity mode in the silicon resonator results in high, narrow band reflection back into the III-V waveguide, forming a so-called resonant mirror. By combining two such mirrors and providing optical gain in the III-V wire in between these 2 mirrors, laser operation can be realized. We simulate the reflectivity spectrum of such a resonant mirror using 3D FDTD and discuss the results. We also present experimental results of the very first optically pumped heterogeneously integrated resonant mirror laser. The fabricated device measures 55 mu m by 2 mu m and shows single mode laser emission with a side-mode suppression ratio of 37 dB

    Self help groups in a city of Tuscany: Reconstruction of the second generation model of work for professionals and services

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    This study is part of a more extensive project aimed to investigate the effectiveness of self-help group participation in improving quality of life in mental disease. The study is taking place in the Tuscany Region, in Italy. In the first qualitative step of analysis researchers are interested in describing the specific features of the psychiatric self-help movement in Tuscany, comparing different realities, networks, kind of groups. Therefore, our aim is to collect exhaustive information to describe how self-help system work in different provinces at the present moment. The implementation of groups for psychiatric problems is quite young in Italy.  Because of a lack of specific regulation in the directives of the Italian health care system, every local service has implemented groups differently, sometimes enhancing, sometimes dismissing them. Prato, near Florence, is one of the more interesting context for the birth of psychiatric self-help movement in the region: public health services improved groups since early 90’s, it was one of the first self-help reality linked to services in the entire region. Now we are in a “second generation” of professionals, and the original meaning of groups seems to be transformed, sometimes misunderstood. Our objectives of study head us toward an in depth analysis of self-help phenomenon in Prato

    Self help groups in a city of Tuscany: Reconstruction of the second generation model of work for professionals and services

    Get PDF
    This study is part of a more extensive project aimed to investigate the effectiveness of self-help group participation in improving quality of life in mental disease. The study is taking place in the Tuscany Region, in Italy. In the first qualitative step of analysis researchers are interested in describing the specific features of the psychiatric self-help movement in Tuscany, comparing different realities, networks, kind of groups. Therefore, our aim is to collect exhaustive information to describe how self-help system work in different provinces at the present moment. The implementation of groups for psychiatric problems is quite young in Italy.  Because of a lack of specific regulation in the directives of the Italian health care system, every local service has implemented groups differently, sometimes enhancing, sometimes dismissing them. Prato, near Florence, is one of the more interesting context for the birth of psychiatric self-help movement in the region: public health services improved groups since early 90’s, it was one of the first self-help reality linked to services in the entire region. Now we are in a “second generation” of professionals, and the original meaning of groups seems to be transformed, sometimes misunderstood. Our objectives of study head us toward an in depth analysis of self-help phenomenon in Prato

    Electrical Properties of Self-Assembled Nano-Schottky Diodes

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    A bottom-up methodology to fabricate a nanostructured material by Au nanoclusters on 6H-SiC surface is illustrated. Furthermore, a methodology to control its structural properties by thermal-induced self-organization of the Au nanoclusters is demonstrated. To this aim, the self-organization kinetic mechanisms of Au nanoclusters on SiC surface were experimentally studied by scanning electron microscopy, atomic force microscopy, Rutherford backscattering spectrometry and theoretically modelled by a ripening process. The fabricated nanostructured materials were used to probe, by local conductive atomic force microscopy analyses, the electrical properties of nano-Schottky contact Au nanocluster/SiC. Strong efforts were dedicated to correlate the structural and electrical characteristics: the main observation was the Schottky barrier height dependence of the nano-Schottky contact on the cluster size. Such behavior was interpreted considering the physics of few electron quantum dots merged with the concepts of ballistic transport and thermoionic emission finding a satisfying agreement between the theoretical prediction and the experimental data. The fabricated Au nanocluster/SiC nanocontact is suggested as a prototype of nano-Schottky diode integrable in complex nanoelectronic circuits

    Extremely uniform lasing wavelengths of InP microdisk lasers heterogeneously integrated on SOI

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    A standard deviation in lasing wavelength lower than 500pm is characterized on nominally identical and optically-pumped microdisk lasers, heterogeneously integrated on the same SOI circuit. This lasing wavelength uniformity is obtained using electron-beam lithography

    Field Localization and Enhancement of Phase Locked Second and Third Harmonic Generation in Absorbing Semiconductor Cavities

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    We predict and experimentally observe the enhancement by three orders of magnitude of phase mismatched second and third harmonic generation in a GaAs cavity at 650nm and 433nm, respectively, well above the absorption edge. Phase locking between the pump and the harmonics changes the effective dispersion of the medium and inhibits absorption. Despite hostile conditions the harmonics become localized inside the cavity leading to relatively large conversion efficiencies. Field localization plays a pivotal role and ushers in a new class of semiconductor-based devices in the visible and UV ranges

    Overview of the EU FP7-project HISTORIC

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    HISTORIC aims to develop and test complex photonic integrated circuits containing a relatively large number of digital photonic elements for use in e.g. all-optical packet switching. These photonic digital units are all-optical flip-flops based on ultra compact laser diodes, such as microdisk lasers and photonic crystal lasers. These lasers are fabricated making use of the heterogeneous integration of InP membranes on top of silicon on insulator (SOI) passive optical circuits. The very small dimensions of the lasers are, at least for some approaches, possible because of the high index contrast of the InP membranes and by making use of the extreme accuracy of CMOS processing. All-optical flip-flops based on heterogeneously integrated microdisk lasers with diameter of 7.5 mu m have already been demonstrated. They operate with a CW power consumption of a few mW and can switch in 60ps with switching energies as low as 1.8 fJ. Their operation as all-optical gate has also been demonstrated. Work is also on-going to fabricate heterogeneously integrated photonic crystal lasers and all-optical flip-flops based on such lasers. A lot of attention is given to the electrical pumping of the membrane InP-based photonic crystal lasers and to the coupling to SOI wire waveguides. Optically pumped photonic crystal lasers coupled to SOI wires have been demonstrated already. The all-optical flip-flops and gates will be combined into more complex photonic integrated circuits, implementing all-optical shift registers, D flip-flops, and other all-optical switching building blocks. The possibility to integrate a large number of photonic digital units together, but also to integrate them with compact passive optical routers such as AWGs, opens new perspectives for the design of integrated optical processors or optical buffers. The project therefore also focuses on designing new architectures for such optical processing or buffer chips
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