Optical design and computation

Naturally in the more final stages of design accurate ray tracing or an equivalent thereof is imperative. Also in this respect development has taken place only in comparatively recent years. Before introduction of the desk calculator the usual method was purely trigonometrically using log tables. When-using desk calculators log tables are of course unnecessary and the natural values of the trigonometrical functions are used, preferably in decimal degree fractions or radians, as arguments

Strange baryon production asymmetry in K(+-)N interactions

The asymmetry of strange baryon production in Kp interactions at high energies is considered in the framework of the Quark-Gluon String Model. The contribution of the String-Junction Mechanism to the strange baryon production is analysed.Comment: Contribution to the proceedings of the IV International Conference on Quarks and Nuclear Physics (QNP06), Universidad Complutense, Madrid (Spain), 5-10 June 2006 (2 pages with 2 figures

Time-Series Ensemble Photometry and the Search for Variable Stars in the Open Cluster M11

This work presents the first large-scale photometric variability survey of the intermediate age (~200 Myr) open cluster M11. Thirteen nights of data over two observing seasons were analyzed (using crowded field and ensemble photometry techniques) to obtain high relative precision photometry. In this study we focus on the detection of candidate member variable stars for follow-up studies. A total of 39 variable stars were detected and can be categorized as follows: 1 irregular (probably pulsating) variable, 6 delta Scuti variables, 14 detached eclipsing binary systems, 17 W UMa variables, and 1 unidentified/candidate variable. While previous proper motion studies allow for cluster membership determination for the brightest stars, we find that membership determination is significantly hampered below V=15,R=15.5 by the large population of field stars overlapping the cluster MS. Of the brightest detected variables that have a high likelihood of cluster membership, we find five systems where further work could help constrain theoretical stellar models, including one potential W UMa member of this young cluster.Comment: 38 pages, 13 figures, accepted for December 2005 AJ, high-resolution version available upon reques

Self-energy of a scalar charge near higher-dimensional black holes

We study the problem of self-energy of charges in higher dimensional static spacetimes. Application of regularization methods of quantum field theory to calculation of the classical self-energy of charges leads to model-independent results. The correction to the self-energy of a scalar charge due to the gravitational field of black holes of the higher dimensional Majumdar-Papapetrou spacetime is calculated exactly. It proves to be zero in even dimensions, but it acquires non-zero value in odd dimensional spacetimes. The origin of the self-energy correction in odd dimensions is similar to the origin the conformal anomalies in quantum field theory in even dimensional spacetimes.Comment: 9 page

The first close-up of the "flip-flop" phenomenon in a single star

We present temperature maps of the active late-type giant FK Com which exhibit the first imagining record of the ``flip-flop'' phenomenon in a single star. The phenomenon, in which the main part of the spot activity shifts 180 degrees in longitude, discovered a decade ago in FK Com, was reported later also in a number of RS CVn binaries and a single young dwarf. With the surface images obtained right before and after the ``flip-flop'', we clearly show that the ``flip-flop'' phenomenon in FK Com is caused by changing the relative strengths of the spot groups at the two active longitudes, with no actual spot movements across the stellar surface, i.e. exactly as it happens in other active stars.Comment: 4 pages, accepted by A&A Letter

Determination of the Maximum Velocity of Filaments in the in vitro Motility Assay

The in vitro motility assay (IVMA) is a powerful tool commonly used in basic muscle research and for drug screenings with the aim to find treatment options for neuromuscular disorders. In brief, the sliding movement of fluorescence-labeled actin filaments on myosin motor proteins is recorded, and the sliding velocity is analyzed via image analysis methods. Due to low signal-to-noise ratios and large variability in the velocity signal, accurate determination of the maximum sliding velocity is challenging. We introduce a new method and software program named Actin Phase Velocity (ActiPHV). The method extracts the maximum velocity from filament tracking data. Based on simulated and real reference data we show that our method yields a higher accuracy compared to previous methods. As a result, our method enables enhancing the sensitivity of the IVMA to better exploit its full potential

Initial State: Theory Status

I present a brief discussion of the different approaches to the study initial state effects in heavy ion collisions in view of the recent results from Pb+Pb and p+p collisions at the LHC.Comment: 8 pages, 6 figures. Contribution to the proceedings of the XXII International Conference on Ultrarelativistic Nucleus-Nucleus Collisions, QM2011. Annecy, France, 22-28 May 201