Exact numerical diagonalization of one-dimensional interacting electrons nonadiabatically coupled to phonons

We study the role of non-adiabatic Holstein electron-phonon coupling on the neutral-ionic phase transition of charge transfer crystals which can be tuned from continuous to discontinuous, using exact numerical diagonalization. The variation of electronic properties through the transition is smoothed by nonadiabaticity. Lattice properties are strongly affected, and we observe both squeezing and antisqueezing, depending on details of the adiabatic potentials, and identify the quantum uncertainty of the phonons as the most sensitive measure of nonadiabaticity. The adiabatic limit is regular for a continuous transition but turns out completely inadequate near a discontinuous transition. The relevance of coherent state approaches is assessed critically.Comment: latex manuscript (7 pages), 3 eps figures; revised version, better discussion, one figure replaced; to be published in Europhys. Let

Costs of publicly provided maternity services in Rosario, Argentina

This material is posted here with permission of the publishers, Instituto Nacional de Salud Pública. Internal or personal use of this material is permitted. However, permission to reprint/republish this material must be obtained from the Publisher.Objective. This study estimates the costs of maternal health services in Rosario, Argentina. Material and Methods. The rovider costs (US$1999) of antenatal care, a normal vaginal delivery and a caesarean section, were evaluated retrospectively in two municipal hospitals. The cost of an antenatal visit was evaluated in two health centres and the patient costs associated with the visit were evaluated in a hospital and a health centre. Results. The average cost per hospital day is$114.62. The average cost of a caesarean section ($525.57) is five times greater than that of a normal vaginal delivery ($105.61). A normal delivery costs less at the general hospital and a c-section less at the aternity hospital. The average cost of an antenatal visit is $31.10. The provider cost is lower at the health centre than at the hospital. Personnel accounted for 72-94$4.70. Direct costs are minimal compared to indirect costs of travel and waiting time. Conclusions. These results suggest the potential for increasing the efficiency of resource use by promoting antenatal care visits at the primary level. Women could also benefit from reduced travel and waiting time. Similar benefits could accrue to the provider by encouraging normal delivery at general hospitals, and complicated deliveries at specialised maternity hospitals.Josephine Borghi is funded by the Department for International Development through the Maternal Health Programme at the London School of Hygiene and Tropical Medicine. This project was conducted for and funded by the Human Reproduction Programme at WHO, Geneva

Pseudospin Magnetism in Graphene

We predict that neutral graphene bilayers are pseudospin magnets in which the charge density-contribution from each valley and spin spontaneously shifts to one of the two layers. The band structure of this system is characterized by a momentum-space vortex which is responsible for unusual competition between band and kinetic energies leading to symmetry breaking in the vortex core. We discuss the possibility of realizing a pseudospin version of ferromagnetic metal spintronics in graphene bilayers based on hysteresis associated with this broken symmetry.Comment: 5 pages, 4 figures; added figure 1, modified introduction and discussion; updated reference

High frequency electro-optic measurement of strained silicon racetrack resonators

The observation of the electro-optic effect in strained silicon waveguides has been considered as a direct manifestation of an induced $\chi^{(2)}$ non-linearity in the material. In this work, we perform high frequency measurements on strained silicon racetrack resonators. Strain is controlled by a mechanical deformation of the waveguide. It is shown that any optical modulation vanishes independently of the applied strain when the applied voltage varies much faster than the carrier effective lifetime, and that the DC modulation is also largely independent of the applied strain. This demonstrates that plasma carrier dispersion is responsible for the observed electro-optic effect. After normalizing out free carrier effects, our results set an upper limit of $8\,pm/V$ to the induced high-speed $\chi^{(2)}_{eff,zzz}$ tensor element at an applied stress of $-0.5\,GPa$. This upper limit is about one order of magnitude lower than the previously reported values for static electro-optic measurements

The Role of Electron-electron Interactions in Graphene ARPES Spectra

We report on a theoretical study of the influence of electron-electron interactions on ARPES spectra in graphene that is based on the random-phase-approximation and on graphene's massless Dirac equation continuum model. We find that level repulsion between quasiparticle and plasmaron resonances gives rise to a gap-like feature at small k. ARPES spectra are sensitive to the electron-electron interaction coupling strength $\alpha_{\rm gr}$ and might enable an experimental determination of this material parameter.Comment: 5 Pages, 4 Figures, Submitte

A heat island model for large urban areas and its application to Milano

The study of the urban heat island has been carried out through two new enhanced versions of the UCLM (Urban Canopy Layer Model) model, Landsat/Thematic Mapper data sets and meteorological data collected over a square area 30 km of side including Milan and its hinterland. The urban climate can be described in different summer and winter radiative settings. The input data are divided into two classes: 1) parameters related to urban and rural local properties (albedo and emissivity, vegetation index NDVI, surface roughness length, land cover...); 2) meteorological data related to the general synoptic conditions. The bulk system of the model is made up of four independent equations expressed in terms of four unknowns, i.e., the temperature values at ground level, canopy level and reference level (100 m) and relative humidity within the urban structure. The study area is divided by a regular square mesh of variable dimension (from 30 m to 1500 m); both the input and output data are average cell values. UCLM30 and UCLM60 calculate the temperature excess as well as the turbulent heat exchanges and the heat storage in the urban canopy as a function of the radiative and dynamic forcing. As can be observed in reality, the model shows that in summer the highest urban heating occurs in early morning and after sunset and that, in extreme conditions, the temperature can be up to 8 7C warmer in town than in the nearby rural lands

Manejo de espécies forrageiras em consórcio com milho safrinha.

O propósito deste documento é fornecer algumas informações sobre o cultivo consorciado de milho com espécies forrageiras dos gêneros Urochloa e Panicum, de forma a proporcionar maiores subsídios na tomada de decisão quanto à adoção deste sistema visando a sustentabilidade de sistemas produtivos de grãos e de carne/leite, pela utilização do componente forrageiro em duplo propósito para fornecer forragem no período de maior escassez de alimento e, ainda, viabilizar o SPD pelo resíduo depositado na superfície do solo.Editado por: Germani Concenço, Gessi Ceccon

Manejo de espécies forrageiras em consórcio com milho safrinha.

O propósito deste documento é fornecer algumas informações sobre o cultivo consorciado de milho com espécies forrageiras dos gêneros Urochloa e Panicum, de forma a proporcionar maiores subsídios na tomada de decisão quanto à adoção deste sistema visando a sustentabilidade de sistemas produtivos de grãos e de carne/leite, pela utilização do componente forrageiro em duplo propósito para fornecer forragem no período de maior escassez de alimento e, ainda, viabilizar o SPD pelo resíduo depositado na superfície do solo.Editado por: Germani Concenço, Gessi Ceccon