1,519 research outputs found
Continuous-variable quantum teleportation of entanglement
Entangled coherent states can be used to determine the entanglement fidelity
for a device that is designed to teleport coherent states. This entanglement
fidelity is universal, in that the calculation is independent of the use of
entangled coherent states and applies generally to the teleportation of
entanglement using coherent states. The average fidelity is shown to be a poor
indicator of the capability of teleporting entanglement; i.e., very high
average fidelity for the quantum teleportation apparatus can still result in
low entanglement fidelity for one mode of the two-mode entangled coherent
state.Comment: 5 pages, 1 figure, published versio
Metabolic flux from the chloroplast provides signals controlling photosynthetic acclimation to cold in Arabidopsis thaliana
Photosynthesis is especially sensitive to environmental conditions, and the composition of the photosynthetic apparatus can be modulated in response to environmental change, a process termed photosynthetic acclimation. Previously, we identified a role for a cytosolic fumarase, FUM2 in acclimation to low temperature in Arabidopsis thaliana. Mutant lines lacking FUM2 were unable to acclimate their photosynthetic apparatus to cold. Here, using gas exchange measurements and metabolite assays of acclimating and non‐acclimating plants, we show that acclimation to low temperature results in a change in the distribution of photosynthetically fixed carbon to different storage pools during the day. Proteomic analysis of wild‐type Col‐0 Arabidopsis and of a fum2 mutant, which was unable to acclimate to cold, indicates that extensive changes occurring in response to cold are affected in the mutant. Metabolic and proteomic data were used to parameterize metabolic models. Using an approach called flux sampling, we show how the relative export of triose phosphate and 3‐phosphoglycerate provides a signal of the chloroplast redox state that could underlie photosynthetic acclimation to cold
Flux sampling is a powerful tool to study metabolism under changing environmental conditions
The development of high-throughput ‘omic techniques has sparked a rising interest in genome-scale metabolic models, with applications ranging from disease diagnostics to crop adaptation. Efficient and accurate methods are required to analyze large metabolic networks. Flux sampling can be used to explore the feasible flux solutions in metabolic networks by generating probability distributions of steady-state reaction fluxes. Unlike other methods, flux sampling can be used without assuming a particular cellular objective. We have undertaken a rigorous comparison of several sampling algorithms and concluded that the coordinate hit-and-run with rounding (CHRR) algorithm is the most efficient based on both run-time and multiple convergence diagnostics. We demonstrate the power of CHRR by using it to study the metabolic changes that underlie photosynthetic acclimation to cold of Arabidopsis thaliana plant leaves. In combination with experimental measurements, we show how the regulated interplay between diurnal starch and organic acid accumulation defines the plant acclimation process. We confirm fumarate accumulation as a requirement for cold acclimation and further predict γ–aminobutyric acid to have a key role in metabolic signaling under cold conditions. These results demonstrate how flux sampling can be used to analyze the feasible flux solutions across changing environmental conditions, whereas eliminating the need to make assumptions which introduce observer bias
On an Asymptotic Series of Ramanujan
An asymptotic series in Ramanujan's second notebook (Entry 10, Chapter 3) is
concerned with the behavior of the expected value of for large
where is a Poisson random variable with mean and
is a function satisfying certain growth conditions. We generalize this by
studying the asymptotics of the expected value of when the
distribution of belongs to a suitable family indexed by a convolution
parameter. Examples include the problem of inverse moments for distribution
families such as the binomial or the negative binomial.Comment: To appear, Ramanujan
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Feasibility study and design concept for an orbiting ice-penetrating radar sounder to characterize in three-dimensions the Europan ice mantle down to (and including) any ice/ocean interface
This report presents a radar sounding model based on the range of current working hypotheses for the nature of Europa's icy shell.Institute for Geophysic
The Lamé Class of Lorenz Curves.
In this paper, the class of Lamé Lorenz curves is studied. This family has the advantage of modeling inequality with a single parameter. The family has a double motivation: it can be obtain from an economic model and from simple transformations of classical Lorenz curves. The underlying cumulative distribution functions have a simple closed form, and correspond to the Singh-Maddala and Dagum distributions, which are well known in the economic literature. The Lorenz order is studied and several inequality and polarization measures are obtained, including Gini, Donaldson-Weymark-Kakwani, Pietra and Wolfson indices. Some extensions of the Lamé family are obtained. Fitting and estimation methods under two different data configuration are proposed. Empirical applications with real data are given. Finally, some relationships with other curves are included.The authors thank to Ministerio de Econom a y Competitividad, project
ECO2010-15455, for partial support. The second author thanks to the Ministerio
de Educaci on (FPU AP-2010-4907) for partial support. We are grateful
for the constructive suggestions provided by the reviewers, which improved
the paper
Oceanographic patterns associated with Nassau Grouper aggregation spawn timing: shifts in surface currents on the nights of peak spawning
Energy levels and lifetimes of Gd IV and enhancement of the electron dipole moment
We have calculated energy levels and lifetimes of 4f7 and 4f6 5d
configurations of Gd IV using Hartree-Fock and configuration interaction
methods. This allows us to reduce significantly the uncertainty of the
theoretical determination of the electron electric dipole moment (EDM)
enhancement factor in this ion and, correspondingly, in gadolinium-containing
garnets for which such measurements were recently proposed. Our new value for
the EDM enhancement factor of Gd+3 is -2.2 +- 0.5. Calculations of energy
levels and lifetimes for Eu~III are used to control the accuracy.Comment: Submitted to Phys. Rev. A 6 pages, 0 figures, 3 table
Predictors of late presentation for obstetric fistula repair in Abakaliki, South-East Nigeria
Late presentation is a challenge to reducing the backlog of obstetric fistulas. We aimed to identify characteristics of women presenting late for repair in order to improve patient recruitment. It was a cross-sectional comparative study. Data was collected from the women and the hospital notes using proforma and analysed using SPSS. Associations between categorical variables were determined using Chi-square. Predictors of late presentation were determined using logistic regression. A P-value of <0.05 was statistically significant. The mean time of presentation was 42.3 months. Late presentation was significantly associated with age >35 years, parity < 3, not having a spouse, and trauma. On logistic regression, women aged 35 years and above were five times more likely to present late compared with younger ones (AOR= 5.192, 95%CI 1.839-14.660, P=0.002), while women with parity >3 were five times less likely to present late compared with those <3 (AOR= 0.208, 95%CI 0.073-0.587, P=0.003). In conclusion, most patients presented late. Although age, parity, having a spouse, and aetiology were associated with time of presentation, age >35 years and parity < 3 were the significant predictors of late presentation. Recruitment for early repair should be a priority area of the national policy for the elimination of obstetric fistula.
La présentation tardive est un défi pour réduire l'arriéré des fistules obstétricales. Nous avons cherché à identifier caractéristiques des femmes se présentant tardivement pour réparation afin d'améliorer le recrutement des patientes. Il s'agissait d'une étude comparative transversale. Les données ont été recueillies auprès des femmes et des notes d'hôpital à l'aide de formulaires proforma. et analysés à l'aide de SPSS. Les associations entre les variables catégorielles ont été déterminées à l'aide du Chi carré. Les prédicteurs de présentation tardive ont été déterminés à l'aide de la régression logistique. Une valeur p de <0,05 était statistiquement significatif. Le délai moyen de présentation était de 42,3 mois. La présentation tardive était significativement associé à l'âge > 35 ans, la parité < 3, l'absence de conjoint et un traumatisme. En régression logistique, les femmes âgés de 35 ans et plus étaient cinq fois plus susceptibles de se présenter tardivement que les plus jeunes (AOR = 5,192, IC à 95 % 1,839-14,660, P=0,002), tandis que les femmes avec une parité >3 étaient cinq fois moins susceptibles de présenter en retard par rapport à ceux <3 (AOR = 0,208, IC à 95 % 0,073-0,587, P = 0,003). En conclusion, la plupart des patients présenté tardivement. Bien que l'âge, la parité, le fait d'avoir un conjoint et l'étiologie soient associés au temps de la présentation, l'âge > 35 ans et la parité < 3 étaient les prédicteurs significatifs de la présentation tardive. Recrutement la réparation précoce devrait être un domaine prioritaire de la politique nationale d'élimination de la fistule obstétricale
Tracking potential larval dispersal patterns from Nassau grouper aggregation sites: evidence for local retention and the “importance of place”
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