2,660 research outputs found

    Organized crime, the quality of local institutions and FDI in Italy: A panel data analysis

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    This paper examines the impact of crime on foreign direct investment (FDI) inflows in the Italian provinces. The incidence of organized crime is measured by the number of complaints regarding criminal offences of different kinds traditionally related to the mafia organizations. The results show how the correlation between organized crime and FDI is both negative and significant, even when an indicator of financial incentives for investment is included in the regressions. Our analysis shows that crime represents a deterrent for foreign investors, suggesting that high levels of (certain) crimes may be perceived as a signal of a local socioinstitutional environment unfavourable for FDI

    Professor Ugo Carraro and BAM: two friends for life

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    Picard group of hypersurfaces in toric 3-folds

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    We show that the usual sufficient criterion for a generic hypersurface in a smooth projective manifold to have the same Picard number as the ambient variety can be generalized to hypersurfaces in complete simplicial toric varieties. This sufficient condition is always satisfied by generic K3 surfaces embedded in Fano toric 3-folds.Comment: 14 pages. v2: some typos corrected. v3: Slightly changed title. Final version to appear in Int. J. Math., incorporates many (mainly expository) changes suggested by the refere

    Time Minimal Trajectories for a Spin 1/2 Particle in a Magnetic Field

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    In this paper we consider the minimum time population transfer problem for the zz-component of the spin of a (spin 1/2) particle driven by a magnetic field, controlled along the x axis, with bounded amplitude. On the Bloch sphere (i.e. after a suitable Hopf projection), this problem can be attacked with techniques of optimal syntheses on 2-D manifolds. Let (−E,E)(-E,E) be the two energy levels, and ∣Ω(t)∣≤M|\Omega(t)|\leq M the bound on the field amplitude. For each couple of values EE and MM, we determine the time optimal synthesis starting from the level −E-E and we provide the explicit expression of the time optimal trajectories steering the state one to the state two, in terms of a parameter that can be computed solving numerically a suitable equation. For M/E<<1M/E<<1, every time optimal trajectory is bang-bang and in particular the corresponding control is periodic with frequency of the order of the resonance frequency ωR=2E\omega_R=2E. On the other side, for M/E>1M/E>1, the time optimal trajectory steering the state one to the state two is bang-bang with exactly one switching. Fixed EE we also prove that for M→∞M\to\infty the time needed to reach the state two tends to zero. In the case M/E>1M/E>1 there are time optimal trajectories containing a singular arc. Finally we compare these results with some known results of Khaneja, Brockett and Glaser and with those obtained by controlling the magnetic field both on the xx and yy directions (or with one external field, but in the rotating wave approximation). As byproduct we prove that the qualitative shape of the time optimal synthesis presents different patterns, that cyclically alternate as M/E→0M/E\to0, giving a partial proof of a conjecture formulated in a previous paper.Comment: 31 pages, 10 figures, typos correcte

    TRANSFORMATIONAL LEADERSHIP AND ITS EFFECT ON EMPLOYEE PSYCHOLOGICAL WELL-BEING IN SELECTED DELTA STATE BROADCAST STATIONS

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    Main Objective: This study examined the effect of transformational leadership on the employee psychological well-being in selected Delta State broadcasting stations. Background Problems: Managers and governments across the globe are concerned about employee psychological health. Organizations in Nigeria have paid little attention to their employees' psychological well-being, and the majority of top executives in the broadcasting industry are unaware of the impact that transformational leadership has on the workforce's psychological well-being. The goal of this research is to investigate transformational leadership and its effect on employee psychological well-being in selected sample of Delta State broadcasting stations. Novelty: Transformational leadership is an effective type of leadership that encourages workers to perform better by increasing their levels of competence and self-reinforcement. Research Methods: The cross-sectional research design approach was used in this study. The participants in this study included 173 management and non-management employees from the Nigerian Television Authority in Asaba (47) and the Delta State Broadcasting Services in Asaba (69) and Warri (57) respectively. Using the SPSS software version 23.0, data was analyzed using linear regression. Findings/Results: According to the findings, transformational leadership had a significant and positive effect on employee psychological well-being. Conclusion: Transformational leaders work toward a common goal with followers, often self-sacrificing, prioritize employees, and develop them

    From eventual to atomic and locally atomic CC programs: A concurrent semantics

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    We present a concurrent semantics (i.e. a semantics where concurrency is explicitely represented) for CC programs with atomic tells. This allows to derive concurrency, dependency, and nondeterminism information for such languages. The ability to treat failure information puts CLP programs also in the range of applicability of our semantics: although such programs are not concurrent, the concurrency information derived in the semantics may be interpreted as possible parallelism, thus allowing to safely parallelize those computation steps which appear to be concurrent in the net. Dually, the dependency information may also be interpreted as necessary sequentialization, thus possibly exploiting it to schedule CC programs. The fact that the semantical structure contains dependency information suggests a new tell operation, which checks for consistency only the constraints it depends on, achieving a reasonable trade-off between efficiency and atomicity

    Is contrast-enhanced US alternative to spiral CT in the assessment of treatment outcome of radiofrequency ablation in hepatocellular carcinoma?

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    Purpose: The present study was conducted to assess the efficacy of contrast-enhanced ultrasound with low mechanical index in evaluating the response of percutaneous radiofrequency ablation treatment of hepatocellular carcinoma by comparing it with 4-row spiral computed tomography. Materials and Methods: 100 consecutive patients (65 men and 35 women; age range: 62 – 76 years) with solitary hepatocellular carcinomas (mean lesion diameter: 3.7cm± 1.1cm SD) underwent internally cooled radiofrequency ablation. Therapeutic response was evaluated at one month after the treatment with triple-phasic contrast-enhanced spiral CT and low-mechanical index contrast-enhanced ultrasound following bolus injection of 2.4 ml of Sonovue (Bracco, Milan). 60 out of 100 patients were followed up for another 3 months. Contrast-enhanced sonographic studies were reviewed by two blinded radiologists in consensus. Sensitivity, specificity, NPV and PPV of contrast-enhanced ultrasound examination were determined. Results: After treatment, contrast-enhanced ultrasound identified persistent signal enhancement in 24 patients (24%), whereas no intratumoral enhancement was detected in the remaining 76 patients (76%). Using CT imaging as gold standard, the sensitivity, specificity, NPV, and PPV of contrast enhanced ultrasound were 92.3% (95% CI = 75.9 – 97.9%), 100% (95% CI = 95.2 – 100%), 97.4% (95% CI = 91.1 – 99.3%), and 100% (95% CI = 86.2 – 100%). Conclusion: Contrast-enhanced ultrasound with low mechanical index using Sonovue is a feasible tool in evaluating the response of hepatocellular carcinoma to radiofrequency ablation. Accuracy is comparable to 4-row spiral CT
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