On the rate of convergence of the Hamiltonian particle-mesh method

The Hamiltonian Particle-Mesh (HPM) method is a particle-in-cell method for compressible fluid flow with Hamiltonian structure. We present a numer- ical short-time study of the rate of convergence of HPM in terms of its three main governing parameters. We find that the rate of convergence is much better than the best available theoretical estimates. Our results indicate that HPM performs best when the number of particles is on the order of the number of grid cells, the HPM global smoothing kernel has fast decay in Fourier space, and the HPM local interpolation kernel is a cubic spline

eIF4E promotes nuclear export of cyclin D1 mRNAs via an element in the 3′UTR

The eukaryotic translation initiation factor eIF4E is a critical modulator of cellular growth with functions in the nucleus and cytoplasm. In the cytoplasm, recognition of the 5′ m7G cap moiety on all mRNAs is sufficient for their functional interaction with eIF4E. In contrast, we have shown that in the nucleus eIF4E associates and promotes the nuclear export of cyclin D1, but not GAPDH or actin mRNAs. We determined that the basis of this discriminatory interaction is an ∼100-nt sequence in the 3′ untranslated region (UTR) of cyclin D1 mRNA, we refer to as an eIF4E sensitivity element (4E-SE). We found that cyclin D1 mRNA is enriched at eIF4E nuclear bodies, suggesting these are functional sites for organization of specific ribonucleoproteins. The 4E-SE is required for eIF4E to efficiently transform cells, thereby linking recognition of this element to eIF4E mediated oncogenic transformation. Our studies demonstrate previously uncharacterized fundamental differences in eIF4E-mRNA recognition between the nuclear and cytoplasmic compartments and further a novel level of regulation of cellular proliferation

"A whole way of life": ontology of culture from Raymond Williams's perspective

An overall understanding of culture, both the culture of community one lives in and the culture of communities one communicates with, seems to be important for people to live their lives under the shelter of peace. This study hands over and foregrounds what people should notice when they face with their own and other nation’s culture in order to understand it better and prevent probable problems. Knowing about the essence of one's own culture, the person can protect it while it is being attacked by other cultures. It is predicted that by being aware of all the criteria just mentioned, people can both protect their own genuine culture and communicate with other communities, with different cultures, without facing with or creating crucial problems; as a result, they can live peacefully and help the matter of globalization. The main goal of this study is to present ontology of culture through which people would be able to get how to know their own and other's cultures. This knowledge helps them to communicate properly by knowing about what aspects of culture they should focus on when facing other cultures in order not to create any crucial problem

Identification of a strong emission line at 2.8935 mu in the spectrum of the Orion Nebula

A strong emission line at 2.8935 mu discovered by Rubin et al. (2001) in an ISO SWS02 spectrum of the Orion Nebula is identified as the 4p - 4s multiplet of the O I triplets. Line formation is due to de-excitation cascades following UV-pumping of high triplet terms and occurs in the O I zone immediately behind the Hydrogen ionization front. This cascade mechanism also accounts for permitted O I triplet lines in the optical spectrum (Grandi 1975). An escape probability treatment of the O I cascades accounts for the strength of the 2.89 mu line and suggests interesting diagnostic possibilities for the optical lines.Comment: Minor changes. Accepted by MNRA

Photometric Analysis of Recently Discovered Eclipsing Binary GSC 00008-00901

Photometric analysis of $BVR_C$ light curves of newly discovered eclipsing binary GSC 0008-00901 is presented. The orbital period is improved to 0.28948(11) days. Photometric parameters are determined, as well. The analysis yielded to conclusion that system is an over-contact binary of W UMa type with components not in thermal contact. The light curves from 2005 show the presence of a spot on the surface of one of the components, while light curves from 2006 are not affected by maculation.Comment: Accepted for publication in Astrophysics & Space Scienc

The Empirical Mass-Luminosity Relation for Low Mass Stars

This work is devoted to improving empirical mass-luminosity relations and mass-metallicity-luminosity relation for low mass stars. For these stars, observational data in the mass-luminosity plane or the mass-metallicity-luminosity space subject to non-negligible errors in all coordinates with different dimensions. Thus a reasonable weight assigning scheme is needed for obtaining more reliable results. Such a scheme is developed, with which each data point can have its own due contribution. Previous studies have shown that there exists a plateau feature in the mass-luminosity relation. Taking into account the constraints from the observational luminosity function, we find by fitting the observational data using our weight assigning scheme that the plateau spans from 0.28 to 0.50 solar mass. Three-piecewise continuous improved mass-luminosity relations in K, J, H and V bands, respectively, are obtained. The visual mass-metallicity-luminosity relation is also improved based on our K band mass-luminosity relation and the available observational metallicity data.Comment: 8 pages, 2 figures. Accepted for publication in Astrophysics & Space Scienc

Reanalysis of two eclipsing binaries: EE Aqr and Z Vul

We study the radial-velocity and light curves of the two eclipsing binaries EE Aqr and Z Vul. Using the latest version of the Wilson & Van Hamme (2003) model, absolute parameters for the systems are determined. We find that EE Aqr and Z Vul are near-contact and semi-detached systems, respectively. The primary component of EE Aqr fills about 96% of its 'Roche lobe', while its secondary one appears close to completely filling this limiting volume. In a similar way, we find fill-out proportions of about 72 and 100% of these volumes for the primary and secondary components of Z Vul respectively. We compare our results with those of previous authors.Comment: 13 pages, 8 figures, 10 table

Reconstruction of Objects by Direct Demodulation

High resolution reconstruction of complicated objects from incomplete and noisy data can be achieved by solving modulation equations iteratively under physical constraints. This direct demodulation method is a powerful technique for dealing with inverse problem in general case. Spectral and image restorations and computerized tomography are only particular cases of general demodulation. It is possible to reconstruct an object in higher dimensional space from observations by a simple lower dimensional instrument through direct demodulation. Our simulations show that wide field and high resolution images of space hard X-rays and soft gamma rays can be obtained by a collimated non-position-sensitive detector without coded aperture masks.Comment: 11 pages, 6 figure

The theory of stellar winds

We present a brief overview of the theory of stellar winds with a strong emphasis on the radiation-driven outflows from massive stars. The resulting implications for the evolution and fate of massive stars are also discussed. Furthermore, we relate the effects of mass loss to the angular momentum evolution, which is particularly relevant for the production of long and soft gamma-ray bursts. Mass-loss rates are not only a function of the metallicity, but are also found to depend on temperature, particularly in the region of the bi-stability jump at 21 000 Kelvin. We highlight the role of the bi-stability jump for Luminous Blue Variable (LBV) stars, and discuss suggestions that LBVs might be direct progenitors of supernovae. We emphasize that radiation-driven wind studies rely heavily on the input opacity data and linelists, and that these are thus of fundamental importance to both the mass-loss predictions themselves, as well as to our overall understanding of the lives and deaths of massive stars.Comment: 6 pages, invited review Astrophysics and Space Science, Vol 336, Issue 1, pp. 163-167 (special HEDLA 2010 Issue