Health Reforms in Mexico City. 2000-2006

Objectives: To describe the reform applied to the health system of Mexico City between 2000 and 2006 and to present their results

A flow equation approach to periodically driven quantum systems

We present a theoretical method to generate a highly accurate {\em time-independent} Hamiltonian governing the finite-time behavior of a time-periodic system. The method exploits infinitesimal unitary transformation steps, from which renormalization group-like flow equations are derived to produce the effective Hamiltonian. Our tractable method has a range of validity reaching into frequency regimes that are usually inaccessible via high frequency $\omega$ expansions in the parameter $h/\omega$, where $h$ is the upper limit for the strength of local interactions. We demonstrate our approach on both interacting and non-interacting many-body Hamiltonians where it offers an improvement over the more well-known Magnus expansion and other high frequency expansions. For the interacting models, we compare our approximate results to those found via exact diagonalization. While the approximation generally performs better globally than other high frequency approximations, the improvement is especially pronounced in the regime of lower frequencies and strong external driving. This regime is of special interest because of its proximity to the resonant regime where the effect of a periodic drive is the most dramatic. Our results open a new route towards identifying novel non-equilibrium regimes and behaviors in driven quantum many-particle systems.Comment: 25 pages, 14 figure

Magnon thermal Hall effect in kagome antiferromagnets with Dzyaloshinskii-Moriya interactions

We theoretically study magnetic and topological properties of antiferromagnetic kagome spin systems in the presence of both in- and out-of-plane Dzyaloshinskii-Moriya interactions. In materials such as the iron jarosites, the in-plane interactions stabilize a canted noncollinear "umbrella" magnetic configuration with finite scalar spin chirality. We derive expressions for the canting angle, and use the resulting order as a starting point for a spin-wave analysis. We find topological magnon bands, characterized by non-zero Chern numbers. We calculate the magnon thermal Hall conductivity, and propose the iron jarosites as a promising candidate system for observing the magnon thermal Hall effect in a noncollinear spin configuration. We also show that the thermal conductivity can be tuned by varying an applied magnetic field, or the in-plane Dzyaloshinskii-Moriya strength. In contrast with previous studies of topological magnon bands, the effect is found to be large even in the limit of small canting.Comment: 11 pages, 11 figure

Near- to mid-infrared picosecond optical parametric oscillator based on periodically poled RbTiOAsO4

We describe a Ti:sapphire-pumped picosecond optical parametric oscillator based on periodically poled RbTiOAsO4 that is broadly tunable in the near to mid infrared. A 4.5-mm single-grating crystal at room temperature in combination with pump wavelength tuning provided access to a continuous-tuning range from 3.35 to 5 mu m, and a pump power threshold of 90 mW was measured. Average mid-infrared output powers in excess of 100 mW and total output powers of 400 mW in similar to 1-ps pulses were obtained at 33% extraction efficiency. (C) 1998 Optical Society of America.</p

Momentum-space entanglement after a quench in one-dimensional disordered fermionic systems

We numerically investigate the momentum-space entanglement entropy and entanglement spectrum of the random-dimer model and its generalizations, which circumvent Anderson localization, after a quench in the Hamiltonian parameters. The type of dynamics that occurs depends on whether or not the Fermi level of the initial state is near the energy of the delocalized states present in these models. If the Fermi level of the initial state is near the energy of the delocalized states, we observe an interesting slow logarithmic-like growth of the momentum-space entanglement entropy followed by an eventual saturation. Otherwise, the momentum-space entanglement entropy is found to rapidly saturate. We also find that the momentum-space entanglement spectrum reveals the presence of delocalized states in these models for long times after the quench and the many-body entanglement gap decays logarithmically in time when the Fermi level is near the energy of the delocalized states.Comment: 4+e pages, 3 figure

A Nordic survey of the management of palliative care in patients with head and neck cancer

Background The five Nordic countries with a population of 27M people form a rather homogenous region in terms of health care. The management of Head and Neck Cancer (HNC) is centralized to the 21 university hospitals in these countries. Our aim was to survey the current status of organization of palliative care for patients with HNC in the Nordic countries as the field is rapidly developing. Materials and methods A structured web-based questionnaire was sent to all the Departments of Otorhinolaryngology-Head and Neck Surgery and Oncology managing HNC in the Nordic countries. Results All 21 (100%) Nordic university hospitals responded to the survey. A majority (over 90%) of the patients are discussed at diagnosis in a multidisciplinary tumor board (MDT), but the presence of a palliative care specialist is lacking in 95% of these MDT's. The patients have access to specialized palliative care units (n = 14, 67%), teams (n = 10, 48%), and consultants (n = 4, 19%) in the majority of the hospitals. Conclusion The present results show that specialized palliative care services are available at the Nordic university hospitals. A major finding was that the collaboration between head and neck surgeons, oncologists and palliative care specialists is not well structured and the palliative care pathway of patients with HNC is not systematically organized. We suggest that early integrated palliative care needs to be included as an addition to the already existing HNC care pathways in the Nordic countries.Peer reviewe