Noise Robustness of a Combined Phase Retrieval and Reconstruction Method for Phase-Contrast Tomography

Classical reconstruction methods for phase-contrast tomography consist of two stages: phase retrieval and tomographic reconstruction. A novel algebraic method combining the two was suggested by Kostenko et al. (Opt. Express, 21, 12185, 2013) and preliminary results demonstrating improved reconstruction compared to a two-stage method given. Using simulated free-space propagation experiments with a single sample-detector distance, we thoroughly compare the novel method with the two-stage method to address limitations of the preliminary results. We demonstrate that the novel method is substantially more robust towards noise; our simulations point to a possible reduction in counting times by an order of magnitude

On the typification of the lichen genus Lepra Scop.

The first typification of Lepra Scop. by Pertusaria discoidea (Pers.) Malme (= Lepra albescens (Hudson) Hafellner), made in the Paris Code (1956), is shown to be correct after studies of the original material in the Micheli Herbarium in FI. Details of the latter are given. All later statements about this case, even in the Code , are irrelevant.acceptedVersio

Externally heated protostellar cores in the Ophiuchus star-forming region

We present APEX 218 GHz observations of molecular emission in a complete sample of embedded protostars in the Ophiuchus star-forming region. To study the physical properties of the cores, we calculate H$_2$CO and c-C$_3$H$_2$ rotational temperatures, both of which are good tracers of the kinetic temperature of the molecular gas. We find that the H$_2$CO temperatures range between 16 K and 124 K, with the highest H$_2$CO temperatures toward the hot corino source IRAS 16293-2422 (69-124 K) and the sources in the $\rho$ Oph A cloud (23-49 K) located close to the luminous Herbig Be star S 1, which externally irradiates the $\rho$ Oph A cores. On the other hand, the c-C$_3$H$_2$ rotational temperature is consistently low (7-17 K) in all sources. Our results indicate that the c-C$_3$H$_2$ emission is primarily tracing more shielded parts of the envelope whereas the H$_2$CO emission (at the angular scale of the APEX beam; 3600 au in Ophiuchus) mainly traces the outer irradiated envelopes, apart from in IRAS 16293-2422, where the hot corino emission dominates. In some sources, a secondary velocity component is also seen, possibly tracing the molecular outflow.Comment: 19 pages, 9 figures, accepted for publication in Ap

Eugen Stahl Schmidt og DIF - Dansk Idræts-Forbunds baggrund, dannelse og etablering 1892-1925

Et historisk tilbageblik på DIF's etablering i anledningen af organisationens 100 års fødselsdag i 1996. Artiklen indeholder en biografi af Eugene Stahl Schmidt, som var en af drivkrafterne bag DIF's stiftelse

Den frivillige, ulønnede leder - en undersøgelse af DIFs ledelseshistorie

Artiklen belyser ledelsesformerne i Danmarks Idræts-Forbund set ud fra forbundets årsskrifter helt tilbage fra 1898