Phosphoproteins and protein-kinase activity in isolated envelopes of pea (Pisum sativum L.) chloroplasts

A protein kinase was found in envelope membranes of purified pea (Pisum sativum L.) chloroplasts. Separation of the two envelope membranes showed that most of the enzyme activity was localized in the outer envelope. The kinase was activated by Mg2+ and inhibited by ADP and pyrophosphate. It showed no response to changes in pH in the physiological range (pH 7-8) or conventional protein substrates. Up to ten phosphorylated proteins could be detected in the envelope-membrane fraction. The molecular weights of these proteins, as determined by polyacrylamide-gel electrophoresis were: two proteins higher than 145 kDa, 97, 86, 62, 55, 46, 34 and 14 kDa. The 86-kDa band being the most pronounced. Experiments with separated inner and outer envelopes showed that most labeled proteins are also localized in the outer-envelope fraction. The results indicate a major function of the outer envelope in the communication between the chloroplast and the parent cell

Crossover effects in a discrete deposition model with Kardar-Parisi-Zhang scaling

We simulated a growth model in 1+1 dimensions in which particles are aggregated according to the rules of ballistic deposition with probability p or according to the rules of random deposition with surface relaxation (Family model) with probability 1-p. For any p>0, this system is in the Kardar-Parisi-Zhang (KPZ) universality class, but it presents a slow crossover from the Edwards-Wilkinson class (EW) for small p. From the scaling of the growth velocity, the parameter p is connected to the coefficient of the nonlinear term of the KPZ equation, lambda, giving lambda ~ p^gamma, with gamma = 2.1 +- 0.2. Our numerical results confirm the interface width scaling in the growth regime as W ~ lambda^beta t^beta, and the scaling of the saturation time as tau ~ lambda^(-1) L^z, with the expected exponents beta =1/3 and z=3/2 and strong corrections to scaling for small lambda. This picture is consistent with a crossover time from EW to KPZ growth in the form t_c ~ lambda^(-4) ~ p^(-8), in agreement with scaling theories and renormalization group analysis. Some consequences of the slow crossover in this problem are discussed and may help investigations of more complex models.Comment: 16 pages, 7 figures; to appear in Phys. Rev.

Exact multilocal renormalization on the effective action : application to the random sine Gordon model statics and non-equilibrium dynamics

We extend the exact multilocal renormalization group (RG) method to study the flow of the effective action functional. This important physical quantity satisfies an exact RG equation which is then expanded in multilocal components. Integrating the nonlocal parts yields a closed exact RG equation for the local part, to a given order in the local part. The method is illustrated on the O(N) model by straightforwardly recovering the $\eta$ exponent and scaling functions. Then it is applied to study the glass phase of the Cardy-Ostlund, random phase sine Gordon model near the glass transition temperature. The static correlations and equilibrium dynamical exponent $z$ are recovered and several new results are obtained. The equilibrium two-point scaling functions are obtained. The nonequilibrium, finite momentum, two-time $t,t'$ response and correlations are computed. They are shown to exhibit scaling forms, characterized by novel exponents $\lambda_R \neq \lambda_C$, as well as universal scaling functions that we compute. The fluctuation dissipation ratio is found to be non trivial and of the form $X(q^z (t-t'), t/t')$. Analogies and differences with pure critical models are discussed.Comment: 33 pages, RevTe

The conserved Fanconi anemia nuclease Fan1 and the SUMO E3 ligase Pli1 act in two novel Pso2-independent pathways of DNA interstrand crosslink repair in yeast

DNA interstrand cross-links (ICLs) represent a physical barrier to the progression of cellular machinery involved in DNA metabolism. Thus, this type of adduct represents a serious threat to genomic stability and as such, several DNA repair pathways have evolved in both higher and lower eukaryotes to identify this type of damage and restore the integrity of the genetic material. Human cells possess a specialized ICL-repair system, the Fanconi anemia (FA) pathway. Conversely yeasts rely on the concerted action of several DNA repair systems. Recent work in higher eukaryotes identified and characterized a novel conserved FA component, FAN1 (Fanconi anemia-associated nuclease 1, or FANCD2/FANCI-associated nuclease 1). In this study, we characterize Fan1 in the yeast Schizosaccharomyces pombe. Using standard genetics, we demonstrate that Fan1 is a key component of a previously unidentified ICL-resolution pathway. Using high-throughput synthetic genetic arrays, we also demonstrate the existence of a third pathway of ICL repair, dependent on the SUMO E3 ligase Pli1. Finally, using sequence-threaded homology models, we predict and validate key residues essential for Fan1 activity in ICL repair

Modelling spectral and timing properties of accreting black holes: the hybrid hot flow paradigm

The general picture that emerged by the end of 1990s from a large set of optical and X-ray, spectral and timing data was that the X-rays are produced in the innermost hot part of the accretion flow, while the optical/infrared (OIR) emission is mainly produced by the irradiated outer thin accretion disc. Recent multiwavelength observations of Galactic black hole transients show that the situation is not so simple. Fast variability in the OIR band, OIR excesses above the thermal emission and a complicated interplay between the X-ray and the OIR light curves imply that the OIR emitting region is much more compact. One of the popular hypotheses is that the jet contributes to the OIR emission and even is responsible for the bulk of the X-rays. However, this scenario is largely ad hoc and is in contradiction with many previously established facts. Alternatively, the hot accretion flow, known to be consistent with the X-ray spectral and timing data, is also a viable candidate to produce the OIR radiation. The hot-flow scenario naturally explains the power-law like OIR spectra, fast OIR variability and its complex relation to the X-rays if the hot flow contains non-thermal electrons (even in energetically negligible quantities), which are required by the presence of the MeV tail in Cyg X-1. The presence of non-thermal electrons also lowers the equilibrium electron temperature in the hot flow model to <100 keV, making it more consistent with observations. Here we argue that any viable model should simultaneously explain a large set of spectral and timing data and show that the hybrid (thermal/non-thermal) hot flow model satisfies most of the constraints.Comment: 26 pages, 13 figures. To be published in the Space Science Reviews and as hard cover in the Space Sciences Series of ISSI - The Physics of Accretion on to Black Holes (Springer Publisher

The effects of sample position and gas flow pattern on the sintering of a 7xxx aluminum alloy

The effects of sample position and gas flow pattern on the sintering of a 7xxx aluminum alloy Al-7Zn-2.5Mg-1Cu in flowing nitrogen have been investigated both experimentally and numerically. The near-surface pore distribution and sintered density of the samples show a strong dependency on the sample separation distance over the range from 2 mm to 40 mm. The open porosity in each sample increases with increasing separation distance while the closed porosity remains essentially unchanged. A two-dimensional computational fluid dynamics (CFD) model has been developed to analyze the gas flow behavior near the sample surfaces during isothermal sintering. The streamlines, velocity profile, and volume flow rate in the cavity between each two samples are presented as a function of the sample separation distance at a fixed nitrogen flow rate of 6 L/min. The CFD modeling results provide essential details for understanding the near-surface pore distribution and density of the sintered samples. It is proposed that the different gas flow patterns near the sample surfaces result in variations of the oxygen content from the incoming nitrogen flow in the local sintering atmosphere, which affects the self-gettering process of the aluminum compacts during sintering. This leads to the development of different near-surface pore distributions and sintered densities

The range and level of impurities in CO2 streams from different carbon capture sources

For CO2 capture and storage deployment, the impact of impurities in the gas or dense phase CO2 stream arising from fossil fuel power plants, or large scale industrial emitters, is of fundamental importance to the safe and economic transportation and storage of the captured CO2. This paper reviews the range and level of impurities expected from the main capture technologies used with fossil-fuelled power plants in addition to other CO2 emission-intensive industries. Analysis is presented with respect to the range of impurities present in CO2 streams captured using pre-combustion, post-combustion and oxy-fuel technologies, in addition to an assessment of the different parameters affecting the CO2 mixture composition. This includes modes of operation of the power plant, and different technologies for the reduction and removal of problematic components such as water and acid gases (SOx/NOx). A literature review of data demonstrates that the purity of CO2 product gases from carbon capture sources is highly dependent upon the type of technology used. This paper also addresses the CO2 purification technologies available for the removal of CO2 impurities from raw oxy-fuel flue gas, such as Hg and non-condensable compounds. CO2 purities of over 99% are achievable using post-combustion capture technologies with low levels of the main impurities of N2, Ar and O2. However, CO2 capture from oxy-fuel combustion and integrated gasification combined cycle power plants will need to take into consideration the removal of non-condensables, acid gas species, and other contaminants. The actual level of CO2 purity required will be dictated by a combination of transport and storage requirements, and process economics

Measurement of the p-pbar -> Wgamma + X cross section at sqrt(s) = 1.96 TeV and WWgamma anomalous coupling limits

The WWgamma triple gauge boson coupling parameters are studied using p-pbar -> l nu gamma + X (l = e,mu) events at sqrt(s) = 1.96 TeV. The data were collected with the DO detector from an integrated luminosity of 162 pb^{-1} delivered by the Fermilab Tevatron Collider. The cross section times branching fraction for p-pbar -> W(gamma) + X -> l nu gamma + X with E_T^{gamma} > 8 GeV and Delta R_{l gamma} > 0.7 is 14.8 +/- 1.6 (stat) +/- 1.0 (syst) +/- 1.0 (lum) pb. The one-dimensional 95% confidence level limits on anomalous couplings are -0.88 < Delta kappa_{gamma} < 0.96 and -0.20 < lambda_{gamma} < 0.20.Comment: Submitted to Phys. Rev. D Rapid Communication

Shrinking a large dataset to identify variables associated with increased risk of Plasmodium falciparum infection in Western Kenya

Large datasets are often not amenable to analysis using traditional single-step approaches. Here, our general objective was to apply imputation techniques, principal component analysis (PCA), elastic net and generalized linear models to a large dataset in a systematic approach to extract the most meaningful predictors for a health outcome. We extracted predictors for Plasmodium falciparum infection, from a large covariate dataset while facing limited numbers of observations, using data from the People, Animals, and their Zoonoses (PAZ) project to demonstrate these techniques: data collected from 415 homesteads in western Kenya, contained over 1500 variables that describe the health, environment, and social factors of the humans, livestock, and the homesteads in which they reside. The wide, sparse dataset was simplified to 42 predictors of P. falciparum malaria infection and wealth rankings were produced for all homesteads. The 42 predictors make biological sense and are supported by previous studies. This systematic data-mining approach we used would make many large datasets more manageable and informative for decision-making processes and health policy prioritization