Dynamics of Coherent States in Regular and Chaotic Regimes of the Non-integrable Dicke Model

The quantum dynamics of initial coherent states is studied in the Dicke model and correlated with the dynamics, regular or chaotic, of their classical limit. Analytical expressions for the survival probability, i.e. the probability of finding the system in its initial state at time $t$, are provided in the regular regions of the model. The results for regular regimes are compared with those of the chaotic ones. It is found that initial coherent states in regular regions have a much longer equilibration time than those located in chaotic regions. The properties of the distributions for the initial coherent states in the Hamiltonian eigenbasis are also studied. It is found that for regular states the components with no negligible contribution are organized in sequences of energy levels distributed according to Gaussian functions. In the case of chaotic coherent states, the energy components do not have a simple structure and the number of participating energy levels is larger than in the regular cases.Comment: Contribution to the proceedings of the Escuela Latinoamericana de F\'isica (ELAF) Marcos Moshinsky 2017. (9 pages, 4 figures

Co-enforcement of Common Pool Resources: Experimental Evidence from TURFs in Chile

This work presents the results of framed field experiments designed to study the co-enforcement of access to common pool resources. The experiments were conducted in the field with participants in the territorial use rights in fisheries (TURFs) management scheme that regulates access to nearshore fisheries along the coast of Chile. In the experiments, TURF members not only decided on harvest but also invested in monitoring to deter poaching by outsiders. Treatments varied whether the monitoring investment was an individual decision or determined by a group vote. Per-unit sanctions for poaching were exogenous as if provided by a government authority, and we varied the sanction level. Our results suggest that co-enforcement, in which monitoring for poaching is provided by resource users and sanctions are levied by the government, can reduce poaching levels. Monitoring investments were not high enough to lift the expected marginal penalty for poaching above the marginal gain from poaching when the sanction for poaching was low, but expected marginal penalties were higher than the marginal gain from poaching when the sanction was high. Despite this, poaching levels were not sensitive to changes in monitoring levels and sanctions. While co-enforcement did not eliminate poaching, it did eliminate the gains from poaching in all but one treatment

Impacto del Incremento en los Precios de los Alimentos en la Pobreza en México

In Mexico, the recent upsurge of the global food prices have affected, more than proportionately, the most margined sectors of the population. According with the present results, it is possible to conclude that, even though poverty is highly sensitive to food prices increase, the substitution capacity of the families helps cushion the wealth lose of the poorest. Different targeting mechanisms were analyzed in their efficiency for allocating public funds. In this case, food price subsidies were not the best mechanisms studied. In contrast, the usage of the "Oportunidades" platform had a higher targeting efficiency. However, it is important to remember that a large share of the Mexican population below food poverty line does not receive any support from social programs. For the Federal Government, this represents a big challenge of extending their coverage in the short and medium term.Precios de alimentos, pobreza, crisis alimentaria, transferencias, focalización, México

Adiabatic invariants for the regular region of the Dicke model

Adiabatic invariants for the non-integrable Dicke model are introduced. They are shown to provide approximate second integrals of motion in the energy region where the system exhibits a regular dynamics. This low-energy region, present for any set of values of the Hamiltonian parameters is described both with a semiclassical and a full quantum analysis in a broad region of the parameter space. Peres lattices in this region exhibit that many observables vary smoothly with energy, along distinct lines which beg for a formal description. It is demonstrated how the adiabatic invariants provide a rationale to their presence in many cases. They are built employing the Born-Oppenheimer approximation, valid when a fast system is coupled to a much slower one. As the Dicke model has one bosonic and one fermionic degree of freedom, two versions of the approximation are used, depending on which one is the faster. In both cases a noticeably accord with exact numerical results is obtained. The employment of the adiabatic invariants provides a simple and clear theoretical framework to study the physical phenomenology associated to these regimes, far beyond the energies where a quadratic approximation around the minimal energy configuration can be used

New records of non-resident pinnipeds from the Gulf of California, Mexico Registros nuevos de pinnípedos no-residentes en el golfo de California, México

Abstract. Although the California sea lion (Zalophus californianus) is the only pinniped resident in the Gulf of California, there are occasional records of 3 additional species; here we report 4 recent records of the Guadalupe fur seal (Artocephalus townsendi), 6 of the northern elephant seal (Mirounga angustirostris) and 2 of the harbor seal (Phoca vitulina). Harbor seals have been observed mostly during the winter-spring months of El Niño years, before water temperature warms in the summer. It is possible that juveniles and subadult and adult males of A. townsendi and M. angustirostris are using the Gulf as an alternative feeding area during the season of intensive feeding as individuals disperse more and more widely as their populations grow. Key words: Guadalupe fur seal, harbor seal, northern elephant seal, Gulf of California. Resumen. Aunque en el golfo de California, el único pinnípedo residente es el lobo marino de California (Zalophus californianus), existen registros ocasionales de otras 3 especies; en la presente nota se proporcionan 4 registros recientes de lobo fi no de Guadalupe (Arctocephalus townsendi), 6 de elefante marino del norte (Mirounga angustirostris) y 2 de foca común (Phoca vitulina). La foca común se ha observado principalmente durante los meses de invierno-primavera en años de El Niño, antes del calentamiento anual del agua en verano. Es posible que los juveniles y los machos sub-adultos y adultos tanto de A. townsendi como de M. angustirostris hagan uso del golfo como un sitio alternativo durante la temporada de alimentación intensiva como de su expansión geográfi ca debido a su incremento poblacional. Palabras clave: lobo fi no de Guadalupe, foca común, elefante marino del norte, golfo de California