Opacity of electromagnetically induced transparency for quantum fluctuations

We analyze the propagation of a pair of quantized fields inside a medium of three-level atoms in $\Lambda$ configuration. We calculate the stationary quadrature noise spectrum of the field after propagating through the medium, in the case where the probe field is in a squeezed state and the atoms show electromagnetically induced transparency (EIT). We find an oscillatory transfer of the initial quantum properties between the probe and pump fields which is most strongly pronounced when both fields have comparable Rabi frequencies. This implies that the quantum state measured after propagation can be completely different from the initial state, even though the mean values of the field are unaltered

Observation of ground-state quantum beats in atomic spontaneous emission

We report ground-state quantum beats in spontaneous emission from a continuously driven atomic ensemble. Beats are visible only in an intensity autocorrelation and evidence spontaneously generated coherence in radiative decay. Our measurement realizes a quantum eraser where a first photon detection prepares a superposition and a second erases the "which-path" information in the intermediate state.Comment: 4 pages, 4 figures, to appear in Phys. Rev. Letter

Conditional control of quantum beats in a cavity QED system

We probe a ground-state superposition that produces a quantum beat in the intensity correlation of a two-mode cavity QED system. We mix drive with scattered light from an atomic beam traversing the cavity, and effectively measure the interference between the drive and the light from the atom. When a photon escapes the cavity, and upon detection, it triggers our feedback which modulates the drive at the same beat frequency but opposite phase for a given time window. This results in a partial interruption of the beat oscillation in the correlation function, that then returns to oscillate.Comment: 9 pages, 5 figures, XVII Reuni\'on Iberoamericana de \'Optica, X Encuentro de \'Optica, L\'aseres y Aplicaciones (RIAO-OPTILAS-2010

Tussock grasses as shelters for overwintering arthropods in Pampean agroecosystems: effects of plant size, clustering and architecture

Las gramíneas perennes son utilizadas como refugios por numerosas especies de artrópodos invernantes de la región pampeana. Las características estructurales y el tamaño de las plantas, así como su disposición espacial, condicionarían la disponibilidad de hábitat o de refugio y en consecuencia la selección de las mismas por artrópodos invernantes. En este trabajo evaluamos la influencia del tamaño, agrupamiento y modificación de la arquitectura de plantas de Schizachyrium condensatum sobre la abundancia y riqueza de artrópodos invernantes en su interior. En un borde de un área agrícola de la Pampa Ondulada se dispusieron plantas de distinto tamaño: desde 110 cm de altura (plantas grandes) a 70 cm de altura (plantas pequeñas), de manera aislada o en grupos de 5 plantas, a las cuales se les modificó o no su arquitectura (abiertas o cerradas). Luego de la temporada invernal, se extrajeron los artrópodos y se determinó la abundancia y riqueza de morfoespecies en cada planta. Dos especies predadoras de la familia Coccinellidae, Hippodamia convergens y Coccinella ancoralis, representaron el 90% de la abundancia total concentrándose mayoritariamente en las plantas grandes agrupadas-cerradas. En las plantas grandes/cerradas se registró más del doble de la abundancia de artrópodos que en las plantas grandes/abiertas; en las plantas pequeñas no hubo efectos debido a la arquitectura. Se registró similar riqueza de especies de artrópodos entre plantas pequeñas/aisladas y plantas pequeñas agrupadas; en las plantas grandes/agrupadas se detectó casi el doble de especies de artrópodos que en las plantas grandes/aisladas. Estos resultados muestran que el tamaño pequeño, así como la apertura y el aislamiento de las plantas grandes, influyen negativamente sobre la selección de los sitios de refugio de coccinélidos invernantes. En consecuencia, planteamos la importancia de la conservación de las gramíneas perennes en los bordes de áreas agrícolas como refugios que asegurarían la permanencia de coccinélidos afidófagos en las proximidades de los campos de cultivo durante el período invernal.Perennial grasses are used as overwintering shelters by several arthropod species in the Pampa region. Plant size, structure, and clustering may condition habitat or shelter availability, and therefore their selection by overwintering arthropods. We analyzed the influence of clustering, size and architecture modification of Schizachyrium condensatum plants on the abundance and richness of these arthropods dwelling inside these plants. We set up plants of different sizes, from large (110 cm tall) to small (70 cm tall), along the edge of a field crop in the Rolling Pampas. They were planted isolated or in groups of five plants, with or without architecture modification (open or closed). After the winter season, overwintering arthropods were removed and the abundance and richness of morphospecies were calculated for each plant. Two predator species from the Coccinellidae family, Hippodamia convergens and Coccinella ancoralis, represented almost 90% of total abundance in large, grouped and closed plants. In large closed plants there was almost twice the abundance of arthropods than in large open plants. In small plants there was no effect due to architecture. In small plants there was similar arthropod richness between isolated and grouped plants, whereas in large plants there was almost twice the species in grouped than in isolated plants. Our results show that small plant size, as well as opening and isolation for large plants, negatively affected the choice of wintering sites for coccinelids. Therefore, we highlight the importance of conserving perennial grasses in the edges of agricultural areas as they allow the persistence of aphidofagous coccinelids in the surroundings of crop fields during wintering periods and thus contribute to the sustainability of the beneficial faunaFil: Cánepa, María E.. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias; ArgentinaFil: Montero, Guillermo A.. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias; ArgentinaFil: Barberis, Ignacio Martín. Universidad Nacional de Rosario. Facultad de Ciencias Agrarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Santa Fe; Argentin

From START to FINISH : the influence of osmotic stress on the cell cycle

Peer reviewedPublisher PD

The influence of pulsed redox conditions on soil phosphorus

The effects of eleven pulsed reduction-oxidation cycles (20 and 2 days respectively) on soil phosphorus (P) dynamics are compared for 12 soils having contrasting properties and overfertilised with respect to P. Incubation conditions simulated transient waterlogging of the soil profile and involved repeated sampling and analysis of both the solution and solid phase P forms. An initial increase in P concentration occurred upto and including the fourth full cycle was followed by a sharp decline in concentration for all but one soil. Accompanying changes in the main extractable forms of P, which appeared to be cumulative, could be summarised as a general decline in the organic P fraction and an overall increase in amorphous associated inorganic forms of P. The fact that up to 60% of the total soil P was demonstrated to change its sensitivity for a particular extractant suggests that these operationally defined P forms can experience substantial transformations. There was also a suggestion that certain changes in P forms may not be reversible. While the laboratory conditions represent an extreme situation changes in timing and frequency of intense precipitation events, as predicted in many climate change scenarios, may increase the risk of episodic soil waterlogging. The potential onset of reducing conditions even for periods of less than twenty days will influence soil P dynamics and short-term bioavailable P. Various mechanisms are involved but the robustness of sequential extraction procedures and general soil test methods (e.g. Olsen) for quantifying and reliably distinguishing specific soil P forms/associations are questioned

Rescaling Social Welfare Policies in Italy. National report

Downloadable at: http://www.euro.centre.org/rescalingDocuments/files/Italy.pd

Raman spectra and structural analysis in ZrOxNy thin films

Raman spectroscopy has been used as a local probe to characterize the structural evolution of magnetron-sputtered decorative zirconium oxynitride ZrOxNy films which result from an increase of reactive gas flow in the deposition The lines shapes, the frequency position and widths of the Raman bands show a systematic change as a function of the reactive gas flow (a mixture of both oxygen and nitrogen). The as-deposited zirconium nitride film presents a Raman spectrum with the typical broadened bands, due to the disorder induced by N vacancies. The recorded Raman spectrum of the zirconium oxide film is typical of the monoclinic phase of ZrO2, which is shown also by X-ray diffraction. Raman spectra of zirconium oxynitride thin films present changes, which are found to be closely related with the oxygen content in films and the subsequent structural changes.FCT institution by the project nº POCTI/CTM/38086/2001 co-financed by European community fund FEDEREuropean Union through the NMP3-CT-2003 505948 project "HARDECOAT