Sr. Hannah: Handling Change

Sister Hannah is a woman religious I interviewed recently about her life and experiences. Our interview focused primarily on her thoughts about modern-day changes in the Catholic Church

Zinc Homeostasis and isotopic fractionation in plants: a review

Aims Recent advances in mass spectrometry have dem- onstrated that higher plants discriminate stable Zn iso- topes during uptake and translocation depending on environmental conditions and physiological status of the plant. Stable Zn isotopes have emerged as a prom- ising tool to characterize the plants response to inade- quate Zn supply. The aim of this review is to build a comprehensive model linking Zn homeostasis and Zn isotopic fractionation in plants and advance our current view of Zn homeostasis and interaction with other micronutrients. Methods The distribution of stable Zn isotopes in plants and the most likely causes of fractionation are reviewed, and the interactions with micronutrients Fe, Cu, and Ni are discussed. Results The main sources of Zn fractionation in plants are i) adsorption, ii) low- and high-affinity transport phenomena, iii) speciation, iv) compartmentalization, and v) diffusion. We propose a model for Zn fraction- ation during uptake and radial transport in the roots, root-to-shoot transport, and remobilization. Conclusions Future work should concentrate on better understanding the molecular mechanisms underlying the fractionations as this will be the key to future devel- opment of this novel isotope system. A combination of stable isotopes and speciation analyses might prove a powerful tool for plant nutrition and homeostasis studies

Improving 1D Stellar Models with 3D Atmospheres

Stellar evolution codes play a major role in present-day astrophysics, yet they share common issues. In this work we seek to remedy some of those by the use of results from realistic and highly detailed 3D hydrodynamical simulations of stellar atmospheres. We have implemented a new temperature stratification extracted directly from the 3D simulations into the Garching Stellar Evolution Code to replace the simplified atmosphere normally used. Secondly, we have implemented the use of a variable mixing-length parameter, which changes as a function of the stellar surface gravity and temperature -- also derived from the 3D simulations. Furthermore, to make our models consistent, we have calculated new opacity tables to match the atmospheric simulations. Here, we present the modified code and initial results on stellar evolution using it.Comment: 4 pages, 5 figures; submitted to the conference proceedings: Seismology of the Sun and the Distant Stars 201

Zinc isotopic fractionation in Phragmites australis in response to toxic levels of zinc

Stable isotope signature of Zn have shown great promise in elucidating changes in uptake and translocation mechanisms of this metal in plants during environmental changes. Here we tested this potential by investigating the effect of high Zn concentrations on the isotopic fractionation patterns of Phragmites australis (Cav.) Trin. ex Steud. Plants were grown for 40 d in a nutritive solution containing 3.2 µM (sufficient) or 2 mM (toxic) Zn. The Zn isotopic composition of roots, rhizomes, shoots and leaves was analysed. Stems and leaves were sampled at different heights to evaluate the effect of long-distance transport on Zn fractionation. During Zn sufficiency, roots, rhizomes and shoots were isotopically heavy (δ66ZnJMC Lyon = 0.2¿) while the youngest leaves were isotopically light (-0.5 ¿). During Zn excess, roots were still isotopically heavier (δ66Zn = 0.5 ¿) and the rest of the plant was isotopically light (up to -0.5 ¿). The enrichment of heavy isotopes at the roots was attributed to Zn uptake mediated by transporter proteins under Zn sufficient conditions and to chelation and compartmentation in Zn excess. The isotopically lighter Zn in shoots and leaves is consistent with long distance root to shoot transport. The tolerance response of P. australis increased the range of Zn fractionation within the plant and with respect to the environment

Feasibility of low-dose digital pulsed video-fluoroscopic swallow exams (VFSE): effects on radiation dose and image quality

Background: Fluoroscopy is a frequently used examination in clinical routine without appropriate research evaluation latest hardware and software equipment. Purpose: To evaluate the feasibility of low-dose pulsed video-fluoroscopic swallowing exams (pVFSE) to reduce dose exposure in patients with swallowing disorders compared to high-resolution radiograph examinations (hrVFSE) serving as standard of reference. Material and Methods: A phantom study (Alderson-Rando Phantom, 60 thermoluminescent dosimeters [TLD]) was performed for dose measurements. Acquisition parameters were as follows: (i) pVFSE: 76.7 kV, 57 mA, 0.9 Cu mm, pulse rate/s 30;(ii) hrVFSE: 68.0 kV, 362 mA, 0.2 Cu mm, pictures 30/s. The dose area product (DAP) indicated by the detector system and the radiation dose derived from the TLD measurements were analyzed. In a patient study, image quality was assessed qualitatively (5-point Likert scale, 5 = hrVFSE;two independent readers) and quantitatively (SNR) in 35 patients who subsequently underwent contrast-enhanced pVFSE and hrVFSE. Results: Phantom measurements showed a dose reduction per picture of factor 25 for pVFSE versus hrVFSE images (0.0025 mGy versus 0.062 mGy). The DAP (mu Gym 2) was 28.0 versus 810.5 (pVFSE versus hrVFSE) for an average examination time of 30 s. Direct and scattered organ doses were significantly lower for pVFSE as compared to hrVFSE (P< 0.05). Image quality was rated 3.9 +/- 0.5 for pVFSE versus the hrVFSE standard;depiction of the contrast agent 4.8 +/- 0.3;noise 3.6 +/- 0.5 (P< 0.05);SNR calculations revealed a relative decreased of 43.9% for pVFSE as compared to hrVFSE. Conclusion: Pulsed VFSE is feasible, providing diagnostic image quality at a significant dose reduction as compared to hrVFSE