Characterization of dynamical regimes and entanglement sudden death in a microcavity quantum - dot system

The relation between the dynamical regimes (weak and strong coupling) and entanglement for a dissipative quantum - dot microcavity system is studied. In the framework of a phenomenological temperature model an analysis in both, temporal (population dynamics) and frequency domain (photoluminescence) is carried out in order to identify the associated dynamical behavior. The Wigner function and concurrence are employed to quantify the entanglement in each regime. We find that sudden death of entanglement is a typical characteristic of the strong coupling regime.Comment: To appear in Journal of Physics: Condensed Matte

Effect of the origin and cold storage on the growth and productivity of strawberry (Fragaria x anannassa Duch) stolons

Se realizó un estudio para evaluar el efecto de la procedencia y el tratamiento con frío del material de siembra sobre el desarrollo vegetativo y el rendimiento de plantas de fresa, cultivar ‘Douglas’, en la Estación Experimental Fabio Baudrit M., Subestación Fraijanes, Alajuela, Costa Rica. El experimento se inició el 15 de agosto de 1985, fecha en que se colocaron plantas en la cámara fría; se sembró el 15 de octubre del mismo año y se terminó de evaluar en mayo de 1986. Los tratamientos correspondieron a estolones provenientes de plantaciones ubicadas a 1650 y 1900 msnm, con o sin almacenamiento en cámara fría previo a la siembra, a una temperatura constante de 3ºC y humedad relativa de 100% durante 60 días. Se utilizó un diseño de Bloques Completos al azar, con arreglo factorial 2 x 2 y cuatro repeticiones. La unidad experimental fue una parcela de 20 Plantas. El porcentaje de sobrevivencia de plantas fue superior al 97,5% en todos los tratamientos. En las plantas provenientes de 1900 msnm y en las almacenadas en cámara fría, se obtuvo promedios mayores en la tasa de formación de hojas respecto a las provenientes de 1650 msnm y las no enfriadas en el tiempo. Con los tratamientos 1900 y 1650 msnm con frío se obtuvo promedios acumulativos de 6,55 y 2,58 estolones por parcela; mientras que con las no enfriadas no se produjeron estolones. La producción de coronas tuvo un comportamiento similar, debido a que en las plantas provenientes de 1900 msnm y las tratadas con frío obtuvieron promedios de 6,38 y 6,37 coronas por parcela respectivamente, mayores que los obtenidos con las plantas que provenían de 1650 msnm y las no enfriadas.An assay was conducted to evaluate the effect of the origin and cold treatment of ‘Douglas’ strawberry stolons on their vegetative growth and yield, at the Fabio Baudrit Experiment Station, Fraijanes Sub-station, Alajuela, Costa Rica. The trial started on August 15th, 1985, when the plants were set in a cold chamber, it was planted on October 15th and the evaluation continued until May of 1986. The treatments corresponded to the stolons from orchards located at 1650 and 1900 masl, with and without the cold storage treatment prior to planting, at a constant temperature of 3ºC and 100% relative humidity during 60 days. A complete randomized block design with a 2 x 2 factorial arrangement and 4 replications was used. The experimental unit was a plot with 20 Plants. The survival percentage on all treatments was above 97.5%. The plants coming from 1900 masl and stored in the cold chamber produced higher averages of the leaf-formation rate, with respect to the plants coming from 1650 masl and without cold storage. The treatments from 1900 and 1650 masl and cold storage produced cumulative averages of 6.55 and 2.58 stolons/plot. The production of crowns showed a similar behavior, because the plants from 1900 masl and those subjected to cold storage produced averages of 6.38 and 6.37 crowns per plot, respectively, higher than those produced by plants from 1650 masl and those without cold Storage.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Estación Experimental Agrícola Fabio Baudrit Moreno (EEAFBM

Experimental setup and procedure for the measurement of the 7Be(n,p)7Li reaction at n_TOF

Following the completion of the second neutron beam line and the related experimental area (EAR2) at the n_TOF spallation neutron source at CERN, several experiments were planned and performed. The high instantaneous neutron flux available in EAR2 allows to investigate neutron induced reactions with charged particles in the exit channel even employing targets made out of small amounts of short-lived radioactive isotopes. After the successful measurement of the 7Be(n,) cross section, the 7Be(n,p)7Li reaction was studied in order to provide still missing cross section data of relevance for Big Bang Nucleosynthesis (BBN), in an attempt to find a solution to the cosmological Lithium abundance problem. This paper describes the experimental setup employed in such a measurement and its characterization.Séptimo Programa Marco de la Comunidad Europea de la Energía Atómica (Euratom)-Proyecto CHANDA (No. 605203)Narodowe Centrum Nauki (NCN)-UMO-2012/04/M/ST2/00700-UMO-2016/22/M/ST2/00183Croatian Science Foundation-HRZZ 168

Measurement of the 70Ge(n,γ) cross section up to 300 keV at the CERN n_TOF facility

Neutron capture data on intermediate mass nuclei are of key importance to nucleosynthesis in the weak component of the slow neutron capture processes, which occurs in massive stars. The (n,γ) cross section on 70Ge, which is mainly produced in the s process, was measured at the neutron time-of-flight facility n_TOF at CERN. Resonance capture kernels were determined up to 40 keV neutron energy and average cross sections up to 300 keV. Stellar cross sections were calculated from kT =5 keV tokT =100 keV and are in very good agreement with a previous measurement by Walter and Beer (1985) and recent evaluations. Average cross sectionsareinagreementwithWalterandBeer(1985)overmostoftheneutronenergyrangecovered,whilethey aresystematicallysmallerforneutronenergiesabove150keV.Wehavecalculatedisotopicabundancesproduced in s-process environments in a 25 solar mass star for two initial metallicities (below solar and close to solar). While the low metallicity model reproduces best the solar system germanium isotopic abundances, the close to solar model shows a good global match to solar system abundances in the range of mass numbers A=60–80.Austrian Science Fund J3503Adolf Messer Foundation ST/M006085/1European Research Council ERC2015-StGCroatian Science Foundation IP-2018-01-857

Photo-induced enhanced Raman spectroscopy for universal ultra-trace detection of explosives, pollutants and biomolecules

Surface-enhanced Raman spectroscopy is one of the most sensitive spectroscopic techniques available, with single-molecule detection possible on a range of noble-metal substrates. It is widely used to detect molecules that have a strong Raman response at very low concentrations. Here we present photo-induced-enhanced Raman spectroscopy, where the combination of plasmonic nanoparticles with a photo-activated substrate gives rise to large signal enhancement (an order of magnitude) for a wide range of small molecules, even those with a typically low Raman cross-section. We show that the induced chemical enhancement is due to increased electron density at the noble-metal nanoparticles, and demonstrate the universality of this system with explosives, biomolecules and organic dyes, at trace levels. Our substrates are also easy to fabricate, self-cleaning and reusable

92 Zr ( n , γ ) and ( n ,tot) measurements at the GELINA and n_TOF facilities

Background: Stellar nucleosynthesis of elements heavier than iron is driven by neutron capture processes. 92Zr is positioned at a strategic point along the slow nucleosynthesis path, given its proximity to the neutron magic number N = 50 and its position at the matching region between the weak and main slow processes. Purpose: In parallel with recent improved astronomical data, the extraction of accurate Maxwellian averaged cross sections (MACSs) derived from a more complete and accurate set of resonance parameters should allow for a better understanding of the stellar conditions at which nucleosynthesis takes place. Methods: Transmission and capture cross section measurements using enriched 92Zr metallic samples were performed at the time-of flight facilities GELINA of JRC-Geel (BE) and n_TOF of CERN (CH). The neutron beam passing through the samples was investigated in transmission measurements at GELINA using a Li-glass scintillator. The γ rays emitted during the neutron capture reactions were detected by C6D6 detectors at both GELINA and n_TOF. Results: Resonance parameters of individual resonances up to 81 keV were extracted from a combined resonance shape analysis of experimental transmissions and capture yields. For the majority of the resonances the parity was determined from an analysis of the transmission data obtained with different sample thicknesses. Average resonance parameters were calculated. Conclusions: Maxwellian averaged cross sections were extracted from resonances observed up to 81 keV. The MACS for kT = 30 keV is fully consistent with experimental data reported in the literature. The MACSs for kT 15 keV are in good agreement with those derived from the ENDF/B-VIII.0 library and recommended in the KADONIS database. For kT higher than 30 keV differences are observed. A comparison with MACSs obtained with the cross sections recommended in the JEFF-3.3 and JENDL-4.0 libraries shows discrepancies even for kT 15 keV.European Community Seventh Framework Programme FP7/2007-2011 under the Project CHANDA (Grant No. 605203

Predicting environmental gradients with fern species composition in Brazilian Amazonia

Conclusions: Fern species composition can be used as an indicator of soil cation concentration, which can be expected to be relevant also for other components of rain forests. Presence-absence data are adequate for this purpose, which makes the collecting of additional data potentially very rapid. Comparison with earlier studies suggests that edaphic preferences of fern species have good transferability across geographical regions within lowland Amazonia. Therefore, species and environmental data sets already available in the Amazon region represent a good starting point for generating better environmental and floristic maps for conservation planning.</p

Experimental setup and procedure for the measurement of the 7Be(n,α)α reaction at n_TOF

The newly built second experimental area EAR2 of the n_TOF spallation neutron source at CERN allows to perform (n, charged particles) experiments on short-lived highly radioactive targets. This paper describes a detection apparatus and the experimental procedure for the determination of the cross-section of the 7Be(n,α)α reaction, which represents one of the focal points toward the solution of the cosmological Lithium abundance problem, and whose only measurement, at thermal energy, dates back to 1963. The apparently unsurmountable experimental difficulties stemming from the huge 7Be γ-activity, along with the lack of a suitable neutron beam facility, had so far prevented further measurements. The detection system is subject to considerable radiation damage, but is capable of disentangling the rare reaction signals from the very high background. This newly developed setup could likely be useful also to study other challenging reactions requiring the detectors to be installed directly in the neutron beam.European Atomic Energy Community (Euratom) Seventh Framework Programme FP7/2007-2011-UMO-2012/04/M/ST2/00700Croatian Science Foundation-HRZZ 168

Perspectivas de pesquisas na relação entre clima e o funcionamento da Floresta Amazônica

Pesquisas recentes do programa LBA (Programa de\ud Grande Escala da Biosfera‑Atmosfera na Amazônia)\ud demonstram ligações entre o clima e o uso da terra\ud na Amazônia e o funcionamento do bioma (1). A\ud vegetação tem uma estreita relação com a atmosfera,\ud controlando uma série de processos físico‑químicos que influenciam\ud a taxa de formação de nuvens, quantidade de núcleos de condensação\ud de nuvens, quantidade de vapor de água, balanço de radiação, emissão\ud de gases biogênicos e de efeito estufa entre tantas outras propriedades.\ud A Amazônia, por sua localização tropical e grande área (Figura 1), é\ud uma importante fonte de vapor de água para nosso planeta. Ela também\ud contém o maior reservatório de carbono entre os ecossistemas\ud terrestres, e tem um papel fundamental na mitigação das mudanças\ud climáticas em curso. A mobilização de pequena fração do carbono\ud acumulado na biomassa da floresta pode perturbar o ciclo de carbono\ud global. A Amazônia também é parte do mais intenso ciclo hidrológico\ud de nosso planeta, com um sofisticado processamento e reciclagem de\ud vapor de água, que alimenta a maior bacia hidrológica. Estes aspectos\ud fazem da região amazônica uma questão central em pesquisas de clima\ud e nas mudanças globais. Desde seu início, o programa LBA focou no\ud relacionamento entre clima, ciclos biogeoquímicos e o papel da mudança\ud de uso do solo em curso, alterando o funcionamento do bioma