227 research outputs found

    Riots, coups and civil war : revisiting the greed and grievance debate

    Get PDF
    The most influential recent work on the determinants of civil wars found the factors associated with the grievance motivation to be largely irrelevant. Our paper subjects the results of this empirical work to further scrutiny by embedding the study of civil war in a more general analysis of varieties of violent contestation of political power within the borders of the state. Such an approach, we argue, will have important implications for how we think theoretically about the occurrence of domestic war as well as how we specify our empirical tests. In the empirical model, the manifestation of domestic conflict range from low intensity violence and coups to civil war. Our multinomial specification of domestic conflict supports the hypothesis that diversity accentuates distributional conflict and thus increases the risk of civil war. We also find that democracies may be more efficient than autocracies in reducing the risk of civil war.Post Conflict Reconstruction,Population Policies,Social Conflict and Violence,Peace&Peacekeeping,Hazard Risk Management

    Political violence and economic growth

    Get PDF
    This paper analyzes the economic growth impact of organized political violence. First, the authors articulate the theoretical underpinnings of the growth impact of political violence in a popular model of growth under uncertainty. The authors show that, under plausible assumptions regarding attitudes toward risk, the overall effects of organized political violence are likely to be much higher than its direct capital destruction impact. Second, using a quantitative model of violence that distinguishes between three levels of political violence (riots, coups, and civil war), the authors use predicted probabilities of aggregate violence and its three manifestations to identify their growth effects in an encompassing growth model. Panel regressions suggest that organized political violence, especially civil war, significantly lowers long-term economic growth. Moreover, unlike most previous studies, the authors also find ethnic fractionalization to have a negative and direct effect on growth, though its effect is substantially ameliorated by the institutions specific to a non-factional partial democracy. Third, the results show that Sub-Saharan Africa has been disproportionately impacted by civil war, which explains a substantial share of its economic decline, including the widening income gap relative to East Asia. Civil wars have also been costly for Sub-Saharan Africa. For the case of Sudan, a typical large African country experiencing a long-duration conflict, the cost of war amounts to $46 billion (in 2000 fixed prices), whichis roughly double the country's current stock of external debt. Fourth, the authors suggest that to break free from its conflict-underdevelopment trap, Africa needs to better manage its ethnic diversity. The way to do this would be to develop inclusive, non-factional democracy. A democratic but factional polity would not work, and would be only marginally better than an authoritarian regime.Post Conflict Reconstruction,Population Policies,Hazard Risk Management,Post Conflict Reintegration,Social Conflict and Violence

    Dielectric Susceptibility and Heat Capacity of Ultra-Cold Glasses in Magnetic Field

    Full text link
    Recent experiments demonstrated unexpected, even intriguing properties of certain glassy materials in magnetic field at low temperatures. We have studied the magnetic field dependence of the static dielectric susceptibility and the heat capacity of glasses at low temperatures. We present a theory in which we consider the coupling of the tunnelling motion to nuclear quadrupoles in order to evaluate the static dielectric susceptibility. In the limit of weak magnetic field we find the resonant part of the susceptibility increasing like B2B^2 while for the large magnetic field it behaves as 1/B. In the same manner we consider the coupling of the tunnelling motion to nuclear quadrupoles and angular momentum of tunnelling particles in order to find the heat capacity. Our results show the Schotky peak for the angular momentum part, and B2B^2 dependence for nuclear quadrupoles part of heat capacity, respectively. We discuss whether or not this approach can provide a suitable explanation for such magnetic properties.Comment: 10 pages, 1 figur

    Front propagation in a regular vortex lattice : dependence on the vortex structure

    Get PDF
    International audienceWe investigate the dependence on the vortex structure of the propagation of fronts in stirred flows. For this, we consider a regular set of vortices whose structure is changed by varying both their boundary conditions and their aspect ratios. These configurations are investigated experimentally in autocatalytic solutions stirred by electroconvective flows and numerically from kinematic simulations based on the determination of the dominant Fourier mode of the vortex stream function in each of them. For free lateral boundary conditions, i.e. in an extended vortex lattice, it is found that both the flow structure and the front propagation negligibly depend on vortex aspect ratios. For rigid lateral boundary conditions, i.e. in a vortex chain, vortices involve a slight dependence on their aspect ratios which surprisingly yields a noticeable decrease of the enhancement of front velocity by flow advection. These different behaviors reveal a sensitivity of the mean front velocity on the flow sub-scales. It emphasizes the intrinsic multi-scale nature of front propagation in stirred flows and the need to take into account not only the intensity of vortex flows but also their inner structure to determine front propagation at a large scale. Differences between experiments and simulations suggest the occurrence of secondary flows in vortex chains at large velocity and large aspect ratios

    Nonlocal interactions in doped cuprates: correlated motion of Zhang-Rice polarons

    Full text link
    In-plane, inter-carrier correlations in hole doped cuprates are investigated by ab initio multiconfiguration calculations. The dressed carriers display features that are reminiscent of both Zhang-Rice (ZR) CuO4 singlet states and Jahn-Teller polarons. The interaction between these quasiparticles is repulsive. At doping levels that are high enough, the interplay between long-range unscreened Coulomb interactions and long-range phase coherence among the O-ion half-breathing vibrations on the ZR plaquettes may lead to a strong reduction of the effective adiabatic energy barrier associated to each polaronic state. Tunneling effects cannot be neglected for a relatively flat, multi-well energy landscape. We suggest that the coherent, superconducting quantum state is the result of such coherent quantum lattice fluctuations involving the in-plane O ions. Our findings appear to support models where the superconductivity is related to a lowering of the in-plane kinetic energy

    Characterization of nano-composite M-2411/Y-123 thin films by electron backscatter diffraction and in-field critical current measurements

    Get PDF
    Thin films of nano-composite Y-Ba-Cu-O (YBCO) superconductors containing nano-sized, non-superconducting particles of Y2Ba 4CuMOx (M-2411 with M = Ag and Nb) have been prepared by the PLD technique. Electron backscatter diffraction (EBSD) has been used to analyze the crystallographic orientation of nano-particles embedded in the film microstructure. The superconducting YBa2Cu3O7 (Y-123) phase matrix is textured with a dominant (001) orientation for all samples, whereas the M-2411 phase exhibits a random orientation. Angular critical current measurements at various temperature (T) and applied magnetic field (B) have been performed on thin films containing different concentration of the M-2411 second phase. An increase in critical current density J c at T < 77 K and B < 6 T is observed for samples with low concentration of the second phase (2 mol % M-2411). Films containing 5 mol % Ag-2411 exhibit lower Jc than pure Y-123 thin films at all fields and temperatures. Samples with 5 mol % Nb-2411 show higher Jc(B) than phase pure Y-123 thin films for T < 77 K

    Perioperative management of patients undergoing pancreaticoduodenectomies (PD). Surgical clinic no. III Cluj expertise

    Get PDF
    Clinica Chirurgie III, Institutul Regional de Gastroenterologie si Hepatologie, UMF “Iuliu Hatieganu” Cluj-Napoca, România, Al XIII-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” și al III-lea Congres al Societății de Endoscopie, Chirurgie miniminvazivă și Ultrasonografie ”V.M.Guțu” din Republica MoldovaIntroducere: În 2009, în Clinica Chirurgie III Cluj-Napoca a fost introdus un protocol care cuprinde aspecte legate de pregătirea preoperatorie a pacienților pentru DPC, de tactica și tehnica intraoperatorie, și tratament postoperator. Material si metode: Studiul înrolează 444 pacienti cu DPC operați în clinica între 2009-2018, împărțiți în două loturi: 2009-2015 și 2016-2018. Au fost urmăriți factorii incriminați în apariția principalelor complicații postoperatorii, rezultatele fiind comparate cu cele obținute înainte de 2009. Informaţiile s-au colectat utilizând Excel 2009, analiza statistică efectuandu-se cu software-ul R v3.2.4. Rezultate: Nu am obtinut reducerea semnificativă a morbidității (53% înainte de 2009, 45,6% între 2009-2015 și 42% între 2016- 2018), însă a scăzut rata de apariție a fistulei pancreatice (de la 10% la 9,06%, respectiv 7,5%) și a stazei gastrice (de la 43% la 20,47%, respectiv 12,8%). Hemoragia bontului pancreatic a apărut mai frecvent (de la 2%, la 6,71%, respectiv 7,2%). Mortalitatea s-a redus semnificativ (de la 11,9%, la 6,04%, respectiv 3,99%), datorită scăderii fistulelor pancreatice grad C. Concluzie: Implementarea protocolului de pregătire a DPC și-a dovedit utilitatea, iar preocuparea de îmbunătațire a acestuia, prin adaptarea la literatură și la propria experiență rămâne o prioritate.Introduction: In 2009, a protocol was introduced at the Surgical Clinic III Cluj-Napoca, which included aspects related to preoperative preparation of patients for PD, intraoperative tactics and technique, and postoperative treatment. Material and Method: The study includes 444 patients with PD operated in the clinic between 2009-2018, divided into two batches: 2009-2015 and 2016-2018. We followed the factors involved in the occurrence of the main postoperative complications and the results were compared with those we obtained before 2009. The information was collected using Excel 2009, the statistical analysis being performed with the software R v3.2.4. Results: We have not achieved a significant decrease in morbidity (53% before 2009, 45.6% between 2009-2015 and 42% between 2016-2018), but decreased the rate of pancreatic fistula (from 10% to 9, 06% and 7.5% respectively) and gastric stasis (from 43% to 20.47% and 12.8% respectively). Pancreas bleeding occurred more frequently (from 2% to 6.71% and 7.2%, respectively). Mortality was significantly reduced (from 11.9% to 6.04% and 3.99%, respectively) due to the reduce rate of grade C pancreatic fistulae. Conclusion: Implementation of the protocol has proven useful and the concern for improvement by adapting it to literature and our experience remains a priority
    • …
    corecore