1,135 research outputs found
Bilinear and quadratic Hamiltonians in two-mode cavity quantum electrodynamics
In this work we show how to engineer bilinear and quadratic Hamiltonians in
cavity quantum electrodynamics (QED) through the interaction of a single driven
two-level atom with cavity modes. The validity of the engineered Hamiltonians
is numerically analyzed even considering the effects of both dissipative
mechanisms, the cavity field and the atom. The present scheme can be used, in
both optical and microwave regimes, for quantum state preparation, the
implementation of quantum logical operations, and fundamental tests of quantum
theory.Comment: 11 pages, 3 figure
Nonadiabatic coherent evolution of two-level systems under spontaneous decay
In this paper we extend current perspectives in engineering reservoirs by
producing a time-dependent master equation leading to a nonstationary
superposition equilibrium state that can be nonadiabatically controlled by the
system-reservoir parameters. Working with an ion trapped inside a nonindeal
cavity we first engineer effective Hamiltonians that couple the electronic
states of the ion with the cavity mode. Subsequently, two classes of
decoherence-free evolution of the superposition of the ground and decaying
excited levels are achieved: those with time-dependent azimuthal or polar
angle. As an application, we generalise the purpose of an earlier study [Phys.
Rev. Lett. 96, 150403 (2006)], showing how to observe the geometric phases
acquired by the protected nonstationary states even under a nonadiabatic
evolution.Comment: 5 pages, no figure
Dissecting eukaryotic translation and its control by ribosome density mapping
Translation of an mRNA is generally divided into three stages: initiation, elongation and termination. The relative rates of these steps determine both the number and position of ribosomes along the mRNA, but traditional velocity sedimentation assays for the translational status of mRNA determine only the number of bound ribosomes. We developed a procedure, termed Ribosome Density Mapping (RDM), that uses site-specific cleavage of polysomal mRNA followed by separation on a sucrose gradient and northern analysis, to determine the number of ribosomes associated with specified portions of a particular mRNA. This procedure allows us to test models for translation and its control, and to examine properties of individual steps of translation in vivo. We tested specific predictions from the current model for translational control of GCN4 expression in yeast and found that ribosomes were differentially associated with the uORFs elements and coding region under different growth conditions, consistent with this model. We also mapped ribosome density along the ORF of several mRNAs, to probe basic kinetic properties of translational steps in yeast. We found no detectable decline in ribosome density between the 5′ and 3′ ends of the ORFs, suggesting that the average processivity of elongation is very high. Conversely, there was no queue of ribosomes at the termination site, suggesting that termination is not very slow relative to elongation and initiation. Finally, the RDM results suggest that less frequent initiation of translation on mRNAs with longer ORFs is responsible for the inverse correlation between ORF length and ribosomal density that we observed in a global analysis of translation. These results provide new insights into eukaryotic translation in vivo
Weighted Bergman kernels and virtual Bergman kernels
We introduce the notion of "virtual Bergman kernel" and apply it to the
computation of the Bergman kernel of "domains inflated by Hermitian balls", in
particular when the base domain is a bounded symmetric domain.Comment: 12 pages. One-hour lecture for graduate students, SCV 2004, August
2004, Beijing, P.R. China. V2: typo correcte
Application of GIS in potential beekeeping assessment: Case study of Montesinho Natural Park (Portugal)
Planners require solutions that address routine work needs and seems essential to improving efficiency and
productivity. There are a great number of different factors related to beekeeper activity as well the quality and
productivity of different bee products. The spatial analysis is a powerful tool for overlap and relates various levels
of information on a map, and consequently a very useful for beekeeping activity planning. This work proposes
and applies a methodology to potential beekeeping assessment in Montesinho Natural Park, a region in the
northwest of Portugal. The beekeeping potential maps were developed with the following data sources: legal
standards, vegetation, land use, topography, water resources, roads, electromagnetic fields, and some honey
physico-chemical analysis. The design and implementation of spatial analysis model based on Geographic
Information System (GIS) to beekeeping planning activities has already been described by Anjos et al (2014).
Spatial analysis techniques allows to define the potential beekeeper map supporting the beekeeper management
in this region. Anjos O, Silva G, Roque N, Fernandez P, 2014. GIS based analysis to support the beekeeping
planning. Book of abstracts of the International Symposium on Bee Products 3rd edition – Annual meeting of the
International Honey Commission (IHC), Faculty of medicine, University of Rijeka, p:6
Infecção congênita pelo citomegalovÃrus: ocorrência em duas populações de nÃvel sócio-econômico diferentes em São Paulo, Brasil
In São Paulo, Brazil, between November 1980 and July 1982, 1614 newborns of middle socioeconomic background and 1156 newborns of low socioeconomic background were examined for the occurrence of congenital cytomegalovirus (CMV) infection by isolation of virus from urine samples or detection of specific anti-CMV IgM in umbilical cord serum tested by immunofluorescence. In the low socioeconomic population prevalence of CMV complement-fixing antibodies in mothers was 84.4%(151/179) and the incidence of congenital infection assessed by virus isolation 0.98% (5/508), as compared with 0.46% (3/648) in the group of newborns tested by detection of specific anti-CMV IgM in umbilical cord-serum. In middle socioeconomic level population prevalence of CMV complement-fixing antibodies in mothers was 66.5% (284/427) and the incidence of CMV congenital infection was 0.39% (2/518) in the group of newborns screened by virus isolation and 0.18% (2/1096) in the group tested by detection of specific anti-CMV IgM. In the present study none of the 12 congenitally infected newborns presented clinical apparent disease at birth.Entre novembro de 1980 e julho de 1982, 1614 recém-nascidos (RNs) de nivel sócio-econômico médio e 1156 RNs de baixo nÃvel sócioeconômico foram examinados para verificar a ocorrência de infecção congênita pelo citomegalovÃrus (CMV), através de isolamento do vÃrus em amostras de urina ou detecção de anticorpos IgM especÃficos em amostras de sangue de cordão umbilical. Na população de baixo nÃvel sócio econômico a prevalência de anticorpos fixadores do complemento (Ac Fc) anti-CMV nas mães foi de 84,4% (151/179) e a incidência de infecção congênita determinada por isolamento do vÃrus foi de 0,90% (5/508). No grupo de RNs em que o diagnóstico baseou-se apenas na detecção de Ac IgM CMV-especÃficos no sangue de cordão a incidência de infecção congênita foi de apenas 0,46% (3/648). Na população de nivel sócio-econômico médio a prevalência de Ac Fc anti-CMV nas mães foi de 66,5% (284/427) e a incidência de infecção congênita foi de 0,39% (2/518) no grupo de RNs testados por isolamento de vÃrus na urina e 0,18% (2/1090) no grupo testado por detecção de Ac IgM especÃficos. No presente estudo nenhum dos 12 RNs infectados congenitamente apresentou sinais ou sintomas de doença ao nascimento
Experimental solubility and density studies on aqueous solutions ofquaternary ammonium halides, and thermodynamic modelling formelting enthalpy estimations
Aiming to extend the yet limited knowledge on phase equilibria and physical-chemical properties of quaternaryalkylammonium halides and their aqueous binary systems, the solubilities of ten salts in water were measured inthis work in the temperature range between 293.2 K and 348.2 K along with their densities. The PC-SAFT equa-tion of state was thenapplied in the description of density as well as water activity coefficients data. The model-ling results describe very satisfactorily the experimental data, and the non-associating parameters follow well-defined trends with the molecular weight of the alkylammonium halides. These parameters were applied inthe prediction of the solubility data with unsatisfactory results, with mole fraction average absolute deviation(AAD= 0.018), deteriorating with increasing alkyl chain length.However, refitting thebinaryinteraction param-eter a much better description is obtained (AAD = 0.0045). COSMO-RS was also applied for the solubility predic-tion (AAD = 0.025), with poorer results for the chloride salts. After, the melting enthalpies of the quaternaryalkylammonium halides were estimated using the PC-SAFT equation, which in spite of their uncertainty, are pos-sibly the best option to perform solid-liquid equilibrium analysis of utmost importance when designing andscreening new deep eutectic mixtures based on these compounds.publishe
A Model of Vertical Oligopolistic Competition
This paper develops a model of successive oligopolies with endogenous market entry, allowing for varying degrees of product differentiation and entry costs in both markets. Our analysis shows that the downstream conditions dominate the overall profitability of the two-tier structure while
the upstream conditions mainly affect the distribution of profits. We compare the welfare effects of upstream versus downstream deregulation policies and show that the impact of deregulation may be overvalued when ignoring feedback effects from the other market. Furthermore, we analyze how different forms of vertical restraints influence the endogenous market structure and show when they are welfare enhancing
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