The dependence of the viscosity-parameter on the disk scale height profile

It is shown that the height scale for accretion disks is a constant whenever hydrostatic equilibrium and sub-sonic turbulence regime hold in the disk. In order to have a variable height scale, processes that do contribute with an extra term to the continuity equation are needed. This makes the viscosity parameter much greater in the outer region and much smaller in the inner region. Under these circumstances, turbulence is a presumable source of viscosity in the disk.Comment: 8 pages, submitted to Apj

Achernar: Rapid Polarization Variability as Evidence of Photospheric and Circumstellar Activity

We present the results of a high accuracy ($\sigma \approx 0.005$) polarization monitoring of the Be Star Achernar that was carried out between July 7th and November 5th, 2006. Our results indicate that, after a near quiescent phase from 1998 to 2002, Achernar is presently in an active phase and has built a circumstellar disk. We detect variations both in the polarization level and position angle in timescales as short as one hour and as long as several weeks. Detailed modeling of the observed polarization strongly suggests that the short-term variations originate from discrete mass ejection events which produce transient inhomogeneities in the inner disk. Long-term variations, on the other hand, can be explained by the formation of an inner ring following one or several mass ejection events.Comment: 16 pages, 5 figures, Accepted to Ap

A Survey of Chloroplast Protein Kinases and Phosphatases in Arabidopsis thaliana

Protein phosphorylation is a major mode of regulation of metabolism, gene expression and cell architecture. In chloroplasts, reversible phosphorylation of proteins is known to regulate a number of prominent processes, for instance photosynthesis, gene expression and starch metabolism. The complements of the involved chloroplast protein kinases (cpPKs) and phosphatases (cpPPs) are largely unknown, except 6 proteins (4 cpPKs and 2 cpPPs) which have been experimentally identified so far. We employed combinations of programs predicting N-terminal chloroplast transit peptides (cTPs) to identify 45 tentative cpPKs and 21 tentative cpPPs. However, test sets of 9 tentative cpPKs and 13 tentative cpPPs contain only 2 and 7 genuine cpPKs and cpPPs, respectively, based on experimental subcellular localization of their N-termini fused to the reporter protein RFP. Taken together, the set of enzymes known to be involved in the reversible phosphorylation of chloroplast proteins in A. thaliana comprises altogether now 6 cpPKs and 9 cpPPs, the function of which needs to be determined in future by functional genomics approaches. This includes the calcium-regulated PK CIPK13 which we found to be located in the chloroplast, indicating that calcium-dependent signal transduction pathways also operate in this organelle

Measuring the Solar Radius from Space during the 2003 and 2006 Mercury Transits

The Michelson Doppler Imager (MDI) aboard the Solar and Heliospheric Observatory observed the transits of Mercury on 2003 May 7 and 2006 November 8. Contact times between Mercury and the solar limb have been used since the 17th century to derive the Sun's size but this is the first time that high-quality imagery from space, above the Earth's atmosphere, has been available. Unlike other measurements this technique is largely independent of optical distortion. The true solar radius is still a matter of debate in the literature as measured differences of several tenths of an arcsecond (i.e., about 500 km) are apparent. This is due mainly to systematic errors from different instruments and observers since the claimed uncertainties for a single instrument are typically an order of magnitude smaller. From the MDI transit data we find the solar radius to be 960".12 +/- 0".09 (696,342 +/- 65 km). This value is consistent between the transits and consistent between different MDI focus settings after accounting for systematic effects.Comment: Accepted for publication in The Astrophysical Journal (2012 March 5

Lack of FIBRILLIN6 in Arabidopsis thaliana affects light acclimation and sulfate metabolism

Arabidopsis thaliana contains 13 fibrillins (FBNs), which are all localized to chloroplasts. FBN1 and FBN2 are involved in photoprotection of photosystem II, and FBN4 and FBN5 are thought to be involved in plastoquinone transport and biosynthesis, respectively. The functions of the other FBNs remain largely unknown. To gain insight into the function of FBN6, we performed coexpression and Western analyses, conducted fluorescence and transmission electron microscopy, stained reactive oxygen species (ROS), measured photosynthetic parameters and glutathione levels, and applied transcriptomics and metabolomics. Using coexpression analyses, FBN6 was identified as a photosynthesis‐associated gene. FBN6 is localized to thylakoid and envelope membranes, and its knockout results in stunted plants. The delayed‐growth phenotype cannot be attributed to altered basic photosynthesis parameters or a reduced CO2 assimilation rate. Under moderate light stress, primary leaves of fbn6 plants begin to bleach and contain enlarged plastoglobules. RNA sequencing and metabolomics analyses point to an alteration in sulfate reduction in fbn6. Indeed, glutathione content is higher in fbn6, which in turn confers cadmium tolerance of fbn6 seedlings. We conclude that loss of FBN6 leads to perturbation of ROS homeostasis. FBN6 enables plants to cope with moderate light stress and affects cadmium tolerance

Women’s pelvic floor muscle strength and urinary and anal incontinence after childbirth: a cross-sectional study

Abstract OBJECTIVE To analyse pelvic floor muscle strength (PFMS) and urinary and anal incontinence (UI and AI) in the postpartum period. METHOD Cross-sectional study carried out with women in their first seven months after child birth. Data were collected through interviews, perineometry (Peritron™), and the International Consultation on Incontinence Questionnaire-Short Form (ICIQ-SF). RESULTS 128 women participated in the study. The PFMS mean was 33.1 (SD=16.0) cmH2O and the prevalence of UI and AI was 7.8% and 5.5%, respectively. In the multiple analyses, the variables associated with PFMS were type of birth and cohabitation with a partner. Newborn’s weight, previous pregnancy, UI during pregnancy, and sexual activity showed an association with UI after child birth. Only AI prior to pregnancy was associated with AI after childbirth. CONCLUSION Vaginal birth predisposes to the reduction of PFMS, and caesarean section had a protective effect to its reduction. The occurrence of UI during pregnancy is a predictor of UI after childbirth, and women with previous pregnancies and newborns with higher weights are more likely to have UI after childbirth.AI prior to pregnancy is the only risk factor for its occurrence after childbirth. Associations between PFMS and cohabitation with a partner, and between UI and sexual activity do not make possible to conclude that these variables are directly associated

MINERvA neutrino detector response measured with test beam data

The MINERvA collaboration operated a scaled down replica of the solid scintillator tracking and sampling calorimeter regions of the MlNERvA detector in a hadron test beam at the Fermilab Test Beam Facility. This paper reports measurements with samples of protons, pions, and electrons from 0.35 to 2.0 GeV/c momentum. The calorimetric response to protons, pions, and electrons is obtained from these data. A measurement of the parameter in Birks\u27 law and an estimate of the tracking efficiency are extracted from the proton sample. Overall the data are well described by a Geant4-based Monte Carlo simulation of the detector and particle interactions with agreements better than 4% for the calorimetric response, though some features of the data are not precisely modeled. These measurements are used to tune the MINERvA detector simulation and evaluate systematic uncertainties in support of the MINERvA neutrino cross-section measurement program. (C) 2015 Published by Elsevier B.V