667 research outputs found
Optical Camera with high temporal resolution to search for transients in the wide field
The wide field optical camera with high temporal resolution for the
continuous monitoring of the sky in order to catch the initial stages of GRBs
is described.Comment: 4 pages, 4 figures. To be published in "Il Nuovo Cimento",
Proceedings of the 4th Rome Workshop on Gamma-Ray Bursts in the Afterglow
Era, eds. L. Piro, L. Amati, S. Covino, B. Gendr
A description of a system of programs for mathematically processing on unified series (YeS) computers photographic images of the Earth taken from spacecraft
A description of a batch of programs for the YeS-1040 computer combined into an automated system for processing photo (and video) images of the Earth's surface, taken from spacecraft, is presented. Individual programs with the detailed discussion of the algorithmic and programmatic facilities needed by the user are presented. The basic principles for assembling the system, and the control programs are included. The exchange format within whose framework the cataloging of any programs recommended for the system of processing will be activated in the future is displayed
Application of laser interferometry to analyze cutting tool state during machining
The efficiency of a cutting tool can be enhanced through stress-strain and temperature studies. Existing mathematical methods implement simplified boundary conditions, and experimental methods that are either inapplicable to real working conditions or lack the necessary accuracy. This study aims to develop novel experimental methods for stress-strain and temperature field analyses. The approaches entail recording the side deformation fields of the cutting tool by laser interferometry during its operation, separating the deformation fields caused by the cutting forces and heating, as well as calculating the stress-strain and temperature fields using the Young's modulus, Poisson's ratio, and coefficient of linear thermal expansion of the tool material. The advantages of these methods include their applicability under real cutting conditions and the possibility to study the stress-strain and temperature fields of a tool during non-stationary operation by high-speed video recording. The study proves the efficiency of the proposed methods by the orthogonal machining of difficult-to-cut steel disc using a cemented carbide tool with positive rake angle. As a result, the temperature and principal stress fields in the tool were determined. Developed methods can help in the study of cutting tool efficiency. © Published under licence by IOP Publishing Ltd
Automated search for star clusters in large multiband surveys: II. Discovery and investigation of open clusters in the Galactic plane
Automated search for star clusters in J,H,K_s data from 2MASS catalog has
been performed using the method developed by Koposov et. al (2008). We have
found and verified 153 new clusters in the interval of the galactic latitude
-24 < b < 24 degrees. Color excesses E(B-V), distance moduli and ages were
determined for 130 new and 14 yet-unstudied known clusters. In this paper, we
publish a catalog of coordinates, diameters, and main parameters of all the
clusters under study. A special web-site available at http://ocl.sai.msu.ru has
been developed to facilitate dissemination and scientific usage of the results.Comment: 9 pages, 3 tables, 5 figures, accepted to Astronomy Letter
Nuclear export factor RBM15 facilitates the access of DBP5 to mRNA
The conserved mRNA export receptor NXF1 (Mex67 in yeast) assembles with messenger ribonucleoproteins (mRNP) in the nucleus and guides them through the nuclear pore complex into the cytoplasm. The DEAD family RNA helicase Dbp5 is essential for nuclear export of mRNA and is thought to dissociate Mex67 from mRNP upon translocation, thereby generating directional passage. However, the molecular mechanism by which Dbp5 recognizes Mex67-containing mRNP is not clear. Here we report that the human NXF1-binding protein RBM15 binds specifically to human DBP5 and facilitates its direct contact with mRNA in vivo. We found that RBM15 is targeted to the nuclear envelope, where it colocalizes extensively with DBP5 and NXF1. Gene silencing of RBM15 leads to cytoplasmic depletion and nuclear accumulation of general mRNA as well as individual endogenous transcripts, indicating that RBM15 is required for efficient mRNA export. We propose a model in which RBM15 acts locally at the nuclear pore complex, by facilitating the recognition of NXF1–mRNP complexes by DBP5 during translocation, thereby contributing to efficient mRNA export
Automated search for galactic star clusters in large multiband surveys: I. Discovery of 15 new open clusters in the Galactic anticenter region
Aims: According to some estimations, there are as many as 100000 open
clusters in the Galaxy, but less than 2000 of them have been discovered,
measured, and cataloged. We plan to undertake data mining of multiwavelength
surveys to find new star clusters. Methods: We have developed a new method to
search automatically for star clusters in very large stellar catalogs, which is
based on convolution with density functions. We have applied this method to a
subset of the Two Micron All Sky Survey catalog toward the Galactic anticenter.
We also developed a method to verify whether detected stellar groups are real
star clusters, which tests whether the stars that form the spatial density peak
also fall onto a single isochrone in the color-magnitude diagram. By fitting an
isochrone to the data, we estimate at the same time the main physical
parameters of a cluster: age, distance, color excess. Results: For the present
paper, we carried out a detailed analysis of 88 overdensity peaks detected in a
field of degrees near the Galactic anticenter. From this analysis,
15 overdensities were confirmed to be new open clusters and the physical and
structural parameters were determined for 12 of them; 10 of them were
previously suspected to be open clusters by Kronberger (2006) and Froebrich
(2007). The properties were also determined for 13 yet-unstudied known open
clusters, thus almost tripling the sample of open clusters with studied
parameters in the anticenter. The parameters determined with this method showed
a good agreement with published data for a set of well-known clusters.Comment: accepted to A&
Identification and characterization of the mouse nuclear export factor (Nxf) family members
TAP/hNXF1 is a key factor that mediates general cellular mRNA export from the nucleus, and its orthologs are structurally and functionally conserved from yeast to humans. Metazoans encode additional proteins that share homology and domain organization with TAP/hNXF1, suggesting their participation in mRNA metabolism; however, the precise role(s) of these proteins is not well understood. Here, we found that the human mRNA export factor hNXF2 is specifically expressed in the brain, suggesting a brain-specific role in mRNA metabolism. To address the roles of additional NXF factors, we have identified and characterized the two Nxf genes, Nxf2 and Nxf7, which together with the TAP/hNXF1's ortholog Nxf1 comprise the murine Nxf family. Both mNXF2 and mNXF7 have a domain structure typical of the NXF family. We found that mNXF2 protein is expressed during mouse brain development. Similar to TAP/hNXF1, the mNXF2 protein is found in the nucleus, the nuclear envelope and cytoplasm, and is an active mRNA export receptor. In contrast, mNXF7 localizes exclusively to cytoplasmic granules and, despite its overall conserved sequence, lacks mRNA export activity. We concluded that mNXF2 is an active mRNA export receptor similar to the prototype TAP/hNXF1, whereas mNXF7 may have a more specialized role in the cytoplasm
FAVOR (FAst Variability Optical Registration) -- A Two-telescope Complex for Detection and Investigation of Short Optical Transients
An astronomical complex intended to detect optical transients (OTs) in a wide
field and follow them up with high time resolution investigation is described.Comment: 4 pages, 3 figures. To be published in "Il Nuovo Cimento",
Proceedings of the 4th Rome Workshop on Gamma-Ray Bursts in the Afterglow
Era, eds. L. Piro, L. Amati, S. Covino, B. Gendr
RTE and CTE mRNA export elements synergistically increase expression of unstable, Rev-dependent HIV and SIV mRNAs
Studies of retroviral mRNA export identified two distinct RNA export elements utilizing conserved eukaryotic mRNA export mechanism(s), namely the Constitutive Transport Element (CTE) and the RNA Transport Element (RTE). Although RTE and CTE are potent in nucleocytoplasmic mRNA transport and expression, neither element is as powerful as the Rev-RRE posttranscriptional control. Here, we found that whereas CTE and the up-regulatory mutant RTEm26 alone increase expression from a subgenomic gag and env clones, the combination of these elements led to a several hundred-fold, synergistic increase. The use of the RTEm26-CTE combination is a simple way to increase expression of poorly expressed retroviral genes to levels otherwise only achieved via more cumbersome RNA optimization. The potent RTEm26-CTE element could be useful in lentiviral gene therapy vectors, DNA-based vaccine vectors, and gene transfer studies of other poorly expressed genes
Scalable Production and Purification of Adeno-Associated Viral Vectors (AAV).
Here we describe methods for the production of adeno-associated viral (AAV) vectors by transient transfection of HEK293 cells grown in serum-free medium in orbital shaken bioreactors and the subsequent purification of vector particles. The protocol for expression of AAV components is based on polyethyleneimine (PEI) mediated transfection of a 2-plasmid system and is specified for production in milliliter to liter scales. After PEI and plasmid DNA (pDNA) complex formation the diluted cell culture is transfected without a prior concentration step or medium exchange. Following a 3-day batch process, cell cultures are further processed using different methods for lysis and recovery. Methods for the purification of viral particles are described, including iodixanol gradient purification, immunoaffinity chromatography, and ultrafiltration, as well as quantitative PCR to quantify vector titer
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