Spectroscopic orbits of nearby stars

We observed stars with variable radial velocities to determine their spectroscopic orbits. Velocities of 132 targets taken over a time span reaching 30 years are presented. They were measured with the correlation radial velocity spectrometers (1913 velocities) and the new VUES echelle spectrograph (632 velocities), with typical accuracy of 0.5 and 0.2 km/s, respectively. We derived spectroscopic orbits of 57 stars (including 53 first-time orbits), mostly nearby dwarfs of spectral types K and M. Their periods range from 2.2 days to 14 years, some of those are Hipparcos astrometric binaries. Comments on individual objects are provided. Many stars belong to hierarchical systems containing three or more components, including 20 new hierarchies resulting from this project. The preliminary orbit of the young star HIP~47110B has a large eccentricity e=0.47 despite short period of 4.4 d; it could be still circularizing. Our results enrich the data on nearby stars and contribute to a better definition of the multiplicity statistics.Comment: Accepted by Astronomy & Astrophysics; 17 pages, 5 figures, 3 table

The lower main sequence of stars in the solar neighborhood: Model predictions versus observation

We have used the Simbad database and VizieR catalogue access tools to construct the observational color-absolute magnitude diagrams of nearby K-M dwarfs with precise Hipparcos parallaxes (\sigma_\pi/\pi < 0.05). Particular attention has been paid to removing unresolved double/multiple and variable stars. In addition to archival data, we have made use of nearly 2000 new radial-velocity measurements of K-M dwarfs to identify spectroscopic binary candidates. The main sequences, cleaned from unresolved binaries, variable stars, and old population stars which can also widen the sequence due to their presumably lower metallicity, were compared to available solar-metallicity models. Significant ofsets of most of the model main-sequence lines are seen with respect to observational data, especially for the lower-mass stars. Only the location and slope of the Victoria-Regina and, partly, BaSTI isochrones match the data quite well.Comment: Submitted to JENAM-2011 SpS3 (Saint Petersburg, July 4-8, 2011) Proceeding

Compact Star Clusters in the M31 Disk

We have carried out a survey of compact star clusters (apparent size <3 arcsec) in the southwest part of the M31 galaxy, based on the high-resolution Suprime-Cam images (17.5 arcmin x 28.5 arcmin), covering ~15% of the deprojected galaxy disk area. The UBVRI photometry of 285 cluster candidates (V < 20.5 mag) was performed using frames of the Local Group Galaxies Survey. The final sample, containing 238 high probability star cluster candidates (typical half-light radius r_h ~ 1.5 pc), was selected by specifying a lower limit of r_h > 0.15 arcsec (>0.6 pc). We derived cluster parameters based on the photometric data and multiband images by employing simple stellar population models. The clusters have a wide range of ages from ~5 Myr (young objects associated with 24 um and/or Ha emission) to ~10 Gyr (globular cluster candidates), and possess mass in a range of 3.0 < log(m/M_sol) < 4.3 peaking at m ~ 4000 M_sol. Typical age of these intermediate-mass clusters is in the range of 30 Myr < t < 3 Gyr, with a prominent peak at ~70 Myr. These findings suggest a rich intermediate-mass star cluster population in M31, which appears to be scarce in the Milky Way galaxy.Comment: 16 pages, 8 figures, 1 table, accepted for publication in Ap

Few-nucleon systems in translationally invariant harmonic oscillator basis

We present a translationally invariant formulation of the no-core shell model approach for few-nucleon systems. We discuss a general method of antisymmetrization of the harmonic-oscillator basis depending on Jacobi coordinates. The use of a translationally invariant basis allows us to employ larger model spaces than in traditional shell-model calculations. Moreover, in addition to two-body effective interactions, three- or higher-body effective interactions as well as real three-body interactions can be utilized. In the present study we apply the formalism to solve three and four nucleon systems interacting by the CD-Bonn nucleon-nucleon potential. Results of ground-state as well as excited-state energies, rms radii and magnetic moments are discussed. In addition, we compare charge form factor results obtained using the CD-Bonn and Argonne V8' NN potentials.Comment: 25 pages. RevTex. 13 Postscript figure

Bioengineering bacterial encapsulin nanocompartments as targeted drug delivery system

The development of Drug Delivery Systems (DDS) has led to increasingly efficient therapies for the treatment and detection of various diseases. DDS use a range of nanoscale delivery platforms produced from polymeric of inorganic materials, such as micelles, and metal and polymeric nanoparticles, but their variant chemical composition make alterations to their size, shape, or structures inherently complex. Genetically encoded protein nanocages are highly promising DDS candidates because of their modular composition, ease of recombinant production in a range of hosts, control over assembly and loading of cargo molecules and biodegradability. One example of naturally occurring nanocompartments are encapsulins, recently discovered bacterial organelles that have been shown to be reprogrammable as nanobioreactors and vaccine candidates. Here we report the design and application of a targeted DDS platform based on the Thermotoga maritima encapsulin reprogrammed to display an antibody mimic protein called Designed Ankyrin repeat protein (DARPin) on the outer surface and to encapsulate a cytotoxic payload. The DARPin9.29 chosen in this study specifically binds to human epidermal growth factor receptor 2 (HER2) on breast cancer cells, as demonstrated in an in vitro cell culture model. The encapsulin-based DDS is assembled in one step in vivo by co-expressing the encapsulin-DARPin9.29 fusion protein with an engineered flavin-binding protein mini-singlet oxygen generator (MiniSOG), from a single plasmid in Escherichia coli. Purified encapsulin-DARPin_miniSOG nanocompartments bind specifically to HER2 positive breast cancer cells and trigger apoptosis, indicating that the system is functional and specific. The DDS is modular and has the potential to form the basis of a multi-receptor targeted system by utilising the DARPin screening libraries, allowing use of new DARPins of known specificities, and through the proven flexibility of the encapsulin cargo loading mechanism, allowing selection of cargo proteins of choice