Intrinsic rotation in tokamaks: theory

Self-consistent equations for intrinsic rotation in tokamaks with small poloidal magnetic field $B_p$ compared to the total magnetic field $B$ are derived. The model gives the momentum redistribution due to turbulence, collisional transport and energy injection. Intrinsic rotation is determined by the balance between the momentum redistribution and the turbulent diffusion and convection. Two different turbulence regimes are considered: turbulence with characteristic perpendicular lengths of the order of the ion gyroradius, $\rho_i$, and turbulence with characteristic lengths of the order of the poloidal gyroradius, $(B/B_p) \rho_i$. Intrinsic rotation driven by gyroradius scale turbulence is mainly due to the effect of neoclassical corrections and of finite orbit widths on turbulent momentum transport, whereas for the intrinsic rotation driven by poloidal gyroradius scale turbulence, the slow variation of turbulence characteristics in the radial and poloidal directions and the turbulent particle acceleration can be become as important as the neoclassical and finite orbit width effects. The magnetic drift is shown to be indispensable for the intrinsic rotation driven by the slow variation of turbulence characteristics and the turbulent particle acceleration. The equations are written in a form conducive to implementation in a flux tube code, and the effect of the radial variation of the turbulence is included in a novel way that does not require a global gyrokinetic formalism.Comment: 88 pages, 4 figure

Canonical circuit quantization with linear nonreciprocal devices

Nonreciprocal devices effectively mimic the breaking of time-reversal symmetry for the subspace of dynamical variables that they couple, and can be used to create chiral information processing networks. We study the systematic inclusion of ideal gyrators and circulators into Lagrangian and Hamiltonian descriptions of lumped-element electrical networks. The proposed theory is of wide applicability in general nonreciprocal networks on the quantum regime. We apply it to pedagogical and pathological examples of circuits containing Josephson junctions and ideal nonreciprocal elements described by admittance matrices, and compare it with the more involved treatment of circuits based on nonreciprocal devices characterized by impedance or scattering matrices. Finally, we discuss the dual quantization of circuits containing phase-slip junctions and nonreciprocal devices.Comment: 12 pages, 4 figures; changes made to match the accepted version in PR

Propuesta de zonación polínica para el sector Casablanca (Almenara)-Torreblanca, provincia de Castellón

Proponemos , como hipótesis de trabajo, dos zonas polínicas para el territorio comprendido entre Casablanca (Almenara) y Torreblanca (Fig . 1). La zona A (entre 6280 BP y 2200 BP) presenta elevados porcentajes AP que relacionamos a un paisaje donde la acción antrópica actuaba desde una época anterior a la fOrmación de la turbera. Así , los porcentajes AP estarían relacionados a una dinámi ca de deforestación- reforestación que configura un paisaje tipo l andnam (sen su IVERSEN, 1941). La zona B, entre 2200 BP y la Alta Edad Media (?) , presenta l os el ementos de una agricultura i ntensa, sincrónicamente se asocian los porcentajes de Olea, Vitis y Gramineae tipo Cerealia lo que puede relacionarse a la técnica agrícola denominada arbustrum en los tratatos agrícolas romanos . En este momento la vegetación arbórea del sector sufre un desequilibrio i rreversibleOn propase deux zones pol l iniques 1 comme hypothese de travai l 1 pour l e terr i toire compris entre Casablanca (Almenara) et Torre blanca ( F ig . 1) . La zone A (entre 6280 BP et 2200 BP) presente des i mportantes taux AP repprochés a un paysage oU 11 action humaine agi t depuis quelque te'mps; les hauts pourcentages AP font partie d 1 un systeme de déboisement et boisements constituant un paysage type landnam (sensu IVERSEN, 1941) . La zone B, entre 2200 BP et le r.loyen Age (?) 1 présente tous l es éléments d' une mise e n val eur du territoire tres in tense nommée arbustum dans les trai tés agricoles romaines . Dans cette zone 8 le déboisement du secteur provoque un déséquilibre irreversible du paysage arboréen. A présent, une interpretation climatique des documents polliniques s' avére encere incertain

Impact of Free Trade Agreements on the Colombian Beef Sector

Colombia negotiated bilateral Trade Agreements (TAs) with the United States and with the MERCOSUR region (Argentina, Brazil, Paraguay, and Uruguay). Colombian cattle and beef interest groups argue that TAs hurt the local beef supply chain. We employ a partial equilibrium framework to assess the impact of these TAs on the welfare of cattle producers, beef marketers and meat consumers in Colombia. Our results suggest that with free imports of chicken parts from the U.S, beef consumption and retail prices of beef both decrease and the derived demand and prices of fed cattle decrease. With beef imports from the MERCOSUR region, domestic beef prices and beef production fall, but total beef consumption increases. Overall, consumers are better off and there are net gains to society with free trade agreements. These net gains tend to increase over time, as Colombia gradually decreases the tariff for imported beef. We identify the reduction in marginal costs required to compete with imported beef, primarily from MERCOSUR. We argue that this is possible because the elimination of trade barriers is gradual and the Colombian beef supply chain can compete with imported meats with an annual reduction of marginal costs between 2 and 4%.Beef, Colombia, partial equilibrium, trade liberalization, International Relations/Trade, F14, D60, Q17,