Follow up on the crystal growth experiments of the LDEF

The results of the 4 solution growth experiments on the LDEF have been published elsewhere. Both the crystals of CaCO3, which were large and well shaped, and the much smaller TTF-TCNQ crystals showed unusual morphological behavior. The follow up on these experiments was begun in 1981, when ESA initiated a 'Concept Definition Study' on a large, 150 kg, Solution Growth Facility (SGF) to be included in the payload of EURECA-1, the European Retrievable Carrier. This carrier was a continuation of the European Spacelab and at that time planned for launch in 1987. The long delay of the LDEF retrieval and of subsequent missions brought about reflections both on the concept of crystal growth in space and on the choice of crystallization materials that had been made for the LDEF. Already before the LDEF retrieval, research on TTF-TCNQ had been stopped, and a planned growth experiment with TTF-TCNQ on the SGF/EURECA had been cancelled. The target of the SGF investigation is now more fundamental in nature. None of the crystals to be grown here are, like TTF-TCNQ, in particular demand by science or industry, and the crystals only serve the purpose of model crystals. The real purpose of the investigation is to study the growth behavior. One of the experiments, the Soret Coefficient Measurement experiment is not growing crystals at all, but has it as its sole purpose to obtain accurate information on thermal diffusion, a process of importance in crystal growth from solution

Horizontal-branch morphology and multiple stellar populations in the anomalous globular cluster M22

M22 is an anomalous globular cluster that hosts two groups of stars with different metallicity and s-element abundance. The star-to-star light-element variations in both groups, with the presence of individual Na-O and C-N anticorrelations, demonstrates that this Milky-Way satellite has experienced a complex star-formation history. We have analysed FLAMES/UVES spectra for seven stars covering a small color interval, on the reddest horizontal-branch (HB) portion of this cluster and investigated possible relations between the chemical composition of a star and its location along the HB. Our chemical abundance analysis takes into account effects introduced by deviations from the local-thermodynamic equilibrium (NLTE effects), that are significant for the measured spectral lines in the atmospheric parameters range spanned by our stars. We find that all the analysed stars are barium-poor and sodium-poor, thus supporting the idea that the position of a star along the HB is strictly related to the chemical composition, and that the HB-morphology is influenced by the presence of different stellar populations.Comment: 21 pages, 3 figures, accepted for publication in Ap

Use of radiobiological modeling in treatment plan evaluation and optimization of prostate cancer radiotherapy

There are many tools available that are used to evaluate a radiotherapy treatment plan, such as isodose distribution charts, dose volume histograms (DVH), maximum, minimum and mean doses of the dose distributions as well as DVH point dose constraints. All the already mentioned evaluation tools are dosimetric only without taking into account the radiobiological characteristics of tumors or OARs. It has been demonstrated that although competing treatment plans might have similar mean, maximum or minimum doses they may have significantly different clinical outcomes (Mavroidis et al. 2001). For performing a more complete treatment plan evaluation and comparison the complication-free tumor control probability (P+) and the biologically effective uniform dose (D ) have been proposed (Källman et al. 1992a, Mavroidis et al. 2000). The D concept denotes that any two dose distributions within a target or OAR are equivalent if they produce the same probability for tumor control or normal tissue complication, respectively (Mavroidis et al. 2001)..

Atomic Diffusion and Mixing in Old Stars. III. Analysis of NGC 6397 Stars under New Constraints

We have previously reported on chemical abundance trends with evolutionary state in the globular cluster NGC 6397 discovered in analyses of spectra taken with FLAMES at the VLT. Here, we reinvestigate the FLAMES-UVES sample of 18 stars, ranging from just above the turnoff point (TOP) to the red giant branch below the bump. Inspired by new calibrations of the infrared flux method, we adopt a set of hotter temperature scales. Chemical abundances are determined for six elements (Li, Mg, Ca, Ti, Cr, and Fe). Signatures of cluster-internal pollution are identified and corrected for in the analysis of Mg. On the modified temperature scales, evolutionary trends in the abundances of Mg and Fe are found to be significant at the 2{\sigma} and 3{\sigma} levels, respectively. The detailed evolution of abundances for all six elements agrees with theoretical isochrones, calculated with effects of atomic diffusion and a weak to moderately strong efficiency of turbulent mixing. The age of these models is compatible with the external determination from the white dwarf cooling sequence. We find that the abundance analysis cannot be reconciled with the strong turbulent-mixing efficiency inferred elsewhere for halo field stars. A weak mixing efficiency reproduces observations best, indicating a diffusion-corrected primordial lithium abundance of log {\epsilon}(Li) = 2.57 +- 0.10. At 1.2{\sigma}, this value agrees well with WMAP-calibrated Big-Bang nucleosynthesis predictions.Comment: 14 pages, 5 figures, accepted by Ap

Multiaxial analyzer detects low-energy electrons

Three curved plate energy analyzers coupled with three electron multiplier tubes detect and measure low energy electron flux in several directions simultaneously

Observational signatures of lithium depletion in the metal-poor globular cluster NGC6397

The "stellar" solution to the cosmological lithium problem proposes that surface depletion of lithium in low-mass, metal-poor stars can reconcile the lower abundances found for Galactic halo stars with the primordial prediction. Globular clusters are ideal environments for studies of the surface evolution of lithium, with large number statistics possible to obtain for main sequence stars as well as giants. We discuss the Li abundances measured for >450 stars in the globular cluster NGC6397, focusing on the evidence for lithium depletion and especially highlighting how the inferred abundances and interpretations are affected by early cluster self-enrichment and systematic uncertainties in the effective temperature determination.Comment: 6 pages, 2 figures, conference proceedings for IAU symposium 26

Development and Validation of a Systematic Training Program for the diagnosis of Anorexia Nervosa, Bulimia Nervosa, and Concomitant Conditions

The research concerning eating disorders and concomitant conditions shows that anorexia nervosa and bulimia nervosa are serious disorders that pose many diagnostic and therapeutic challenges to mental health and nutrition professionals. Most psychologists and nutritionists receive broad-based training that likely only superficially touches upon the importance of these diagnostic issues. Nevertheless, effective treatment planning requires that diagnostic issues and concomitant conditions be evaluated and incorporated into the diagnosis and treatment of eating disorders. Thus, there is an increasing need for specialized training in order to better evaluate and treat the complicated clinical picture presented by eating disorder clients. However to date, no systematic training package has been available to meet this training need. The present study was designed to fulfill this need by developing and initially validating an expert system-based, computer-assisted training program (ES-CAT). The initial validation involved comparing the mean overall post-test scores of 56 subjects. Subjects were randomly assigned to one of three groups [i.e., expert system-based, computer assisted trainer (ES-CAT), expert system-based trainer without computer guidance (ES), and traditional self-study (SS)]. The ES-CAT was shown to be more effective in training subjects in the diagnosis and treatment of eating disorders than either an expert system-based trainer without computer guidance (ES) or a traditional method of training (SS). Indeed, subjects who used the ES-CAT showed large gains in knowledge and mastery of the material at better than 85%. The addition of the computer-based guidance to the expert system trainer showed more significant gains (from a pre-test to post-test) of learning than the expert system trainer manual only. Furthermore, the expert system-based trainer without computer guidance (ES) was significantly more effective in training subjects than a traditional method of reading and studying textbooks (SS). The total training time of the ES-CAT was approximately 16 hours. Thus, a reasonable and effective means of training practitioners to better evaluate and treat the complicated clinical picture presented by eating disorder patients was developed and initially validated

Carbon and oxygen in metal-poor halo stars

Carbon and oxygen are key tracers of the Galactic chemical evolution; in particular, a reported upturn in [C/O] towards decreasing [O/H] in metal-poor halo stars could be a signature of nucleosynthesis by massive Population III stars. We reanalyse carbon, oxygen, and iron abundances in thirty-nine metal-poor turn-off stars. For the first time, we take into account three-dimensional (3D) hydrodynamic effects together with departures from local thermodynamic equilibrium (LTE) when determining both the stellar parameters and the elemental abundances, by deriving effective temperatures from 3D non-LTE H$\beta$ profiles, surface gravities from Gaia parallaxes, iron abundances from 3D LTE Feii equivalent widths, and carbon and oxygen abundances from 3D non-LTE Ci and Oi equivalent widths. We find that [C/Fe] stays flat with [Fe/H], whereas [O/Fe] increases linearly up to $0.75$ dex with decreasing [Fe/H] down to $-3.0$ dex. As such [C/O] monotonically decreases towards decreasing [O/H], in contrast to previous findings, mainly by virtue of less severe non-LTE effects for Oi at low [Fe/H] with our improved calculations.Comment: 5 pages, 2 figures; published in A&A Letter