1,016 research outputs found

    Counteracting cocaine production. An analysis based on a novel dataset

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    he debate about the effectiveness of the counteracting policies against the supply of drugs, in particular of cocaine, is very lively and intense. Indeed, since many opinions are based on certain measures rather than others, the construction of reliable indicators is one of the preconditions for a correct and concerted assessment of drug supply. The lack of reliable data on drug provision derives, on the one side, from the objective difficulties encountered in assessing the quantitative elements of drug production and drug trafficking due to its illegal nature, and, on the other side, from the lack of a standard methodological approach to the issue. This paper tries to contribute to the topic by proposing a new dataset, based on a completely new approach to the problem of measuring drug supply. We put forward a unique dataset covering cocaine related seizures in Colombia for the whole of year 2008. Data have been collected on a daily basis from the websites of the main organizations fighting against drug traffickers (Army, Air Force, National Police, Departamento Administrativo de Seguridad, Armada Nacional, Fiscalia), detailing each single seizure of laboratories for the production of both basic paste and cocaine hydrochloride. By means of this dataset, we offer some accounts of the main numbers on drug supply and on drug seizures, suggesting some policy options, and arriving to an estimate of cocaine production.

    Microscopic Deterministic Dynamics and Persistence Exponent

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    Numerically we solve the microscopic deterministic equations of motion with random initial states for the two-dimensional ϕ4\phi^4 theory. Scaling behavior of the persistence probability at criticality is systematically investigated and the persistence exponent is estimated.Comment: to appear in Mod. Phys. Lett.

    Phase Ordering Dynamics of ϕ4\phi^4 Theory with Hamiltonian Equations of Motion

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    Phase ordering dynamics of the (2+1)- and (3+1)-dimensional ϕ4\phi^4 theory with Hamiltonian equations of motion is investigated numerically. Dynamic scaling is confirmed. The dynamic exponent zz is different from that of the Ising model with dynamics of model A, while the exponent λ\lambda is the same.Comment: to appear in Int. J. Mod. Phys.

    Emergence of a non trivial fluctuating phase in the XY model on regular networks

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    We study an XY-rotor model on regular one dimensional lattices by varying the number of neighbours. The parameter 2γ12\ge\gamma\ge1 is defined. γ=2\gamma=2 corresponds to mean field and γ=1\gamma=1 to nearest neighbours coupling. We find that for γ<1.5\gamma<1.5 the system does not exhibit a phase transition, while for γ>1.5\gamma > 1.5 the mean field second order transition is recovered. For the critical value γ=γc=1.5\gamma=\gamma_c=1.5, the systems can be in a non trivial fluctuating phase for whichthe magnetisation shows important fluctuations in a given temperature range, implying an infinite susceptibility. For all values of γ\gamma the magnetisation is computed analytically in the low temperatures range and the magnetised versus non-magnetised state which depends on the value of γ\gamma is recovered, confirming the critical value γc=1.5\gamma_{c}=1.5

    Passive Tracer Dynamics in 4 Point-Vortex Flow

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    The advection of passive tracers in a system of 4 identical point vortices is studied when the motion of the vortices is chaotic. The phenomenon of vortex-pairing has been observed and statistics of the pairing time is computed. The distribution exhibits a power-law tail with exponent 3.6\sim 3.6 implying finite average pairing time. This exponents is in agreement with its computed analytical estimate of 3.5. Tracer motion is studied for a chosen initial condition of the vortex system. Accessible phase space is investigated. The size of the cores around the vortices is well approximated by the minimum inter-vortex distance and stickiness to these cores is observed. We investigate the origin of stickiness which we link to the phenomenon of vortex pairing and jumps of tracers between cores. Motion within the core is considered and fluctuations are shown to scale with tracer-vortex distance rr as r6r^{6}. No outward or inward diffusion of tracers are observed. This investigation allows the separation of the accessible phase space in four distinct regions, each with its own specific properties: the region within the cores, the reunion of the periphery of all cores, the region where vortex motion is restricted and finally the far-field region. We speculate that the stickiness to the cores induced by vortex-pairings influences the long-time behavior of tracers and their anomalous diffusion.Comment: 18 pages, 15 figure

    Dynamical approach to the microcanonical ensemble

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    An analytical method to compute thermodynamic properties of a given Hamiltonian system is proposed. This method combines ideas of both dynamical systems and ensemble approaches to thermodynamics, providing de facto a possible alternative to traditional Ensemble methods. Thermodynamic properties are extracted from effective motion equations. These equations are obtained by introducing a general variational principle applied to an action averaged over a statistical ensemble of paths defined on the constant energy surface. The method is applied first to the one dimensional (\beta)-FPU chain and to the two dimensional lattice (\phi ^{4}) model. In both cases the method gives a good insight of some of their statistical and dynamical properties.Comment: 5 pages, 4 figures, RevTe

    Out of Equilibrium Solutions in the XYXY-Hamiltonian Mean Field model

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    Out of equilibrium magnetised solutions of the XYXY-Hamiltonian Mean Field (XYXY-HMF) model are build using an ensemble of integrable uncoupled pendula. Using these solutions we display an out-of equilibrium phase transition using a specific reduced set of the magnetised solutions

    A practical algorithmic approach to mature aggressive B cell lymphoma diagnosis in the double/triple hit era. Selecting cases, matching clinical benefit. A position paper from the Italian Group of Haematopathology (G.I.E.)

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    An accurate diagnosis of clinically distinct subgroups of aggressive mature B cell lymphomas is crucial for the choice of proper treatment. Presently, precise recognition of these disorders relies on the combination of morphological, immunophenotypical, and cytogenetic/molecular features. The diagnostic workup in such situations implies the application of costly and time-consuming analyses, which are not always required, since an intensified treatment option is reasonably reserved to fit patients. The Italian Group of Haematopathology proposes herein a practical algorithm for the diagnosis of aggressive mature B cell lymphomas based on a stepwise approach, aimed to select cases deserving molecular analysis, in order to optimize time and resources still assuring the optimal management for any patient

    Oxygen therapy in headache disorders: A systematic review

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    Background: The global active prevalence of migraines is approximately 14.7%. Oxygen therapy may reduce the use of non-steroidal anti-inflammatory drugs (NSAIDs) which often have various negative side effects. The purpose of this systematic review is to analyze the literature on the efficacy of high flow oxygen for the management of headache disorders, compared to placebo treatment. Methods: Studies were identified by PubMed, Web of Science and Scopus database from 1980 to the 30 October 2020. The search included the following terms: “oxygen therapy” and “headache” and “migraine”. Studies were included if high flow oxygen was used in the treatment of headache disorders. All selected studies were qualitatively analyzed. Results: Our literature search identified 71 studies, of which 65 were discarded and 6 were included in the meta-analysis. The random effect model did not show a pooled significant resolution of headache disorders (OR 2.08 (95% CI 0.92–4.70), p &lt; 0.0001) in the oxygen therapy group compared to the placebo group. Conclusion: In our systematic review of six studies, there were no significant differences between high flow oxygen and placebo treatment groups

    Offsprings of a point vortex

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    The distribution engendered by successive splitting of one point vortex are considered. The process of splitting a vortex in three using a reverse three-point vortex collapse course is analysed in great details and shown to be dissipative. A simple process of successive splitting is then defined and the resulting vorticity distribution and vortex populations are analysed
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