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Aims. According to some estimations, there are as many as 100 000 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.

Abstract: The magnetoresistance, magnetization, and microstructure of granular composites with the general formula (Fe40Co40B20)x(Al2O3)100−x were studied for contents of the amorphous metallic component both above and below the percolation threshold (x≈43). The low-temperature transverse magnetoresistance of the composites is negative at x=41 and practically zero for x=49. For metal contents below the percolation threshold (x=31), a noticeable (7–8%) positive magnetoresistance, reached in magnetic fields of about 17 kOe, was observed. Possible mechanisms of the generation of inverse (positive) magnetoresistance are discussed.

The experimental data, which concern kinetics of formation of KH2PO4 fractal structures, are considered. It is shown that the transport process of KH2PO4 molecules during the fractal aggregate formation is the superdiffusion process and it is caused by hierarchicity of fractal structure and by stochasticity of transport processes

We have used baculovirus-expressed Rep68 that has been purified to homogeneity to reexamine the binding properties of the Rep protein. We find that Rep68 is capable of binding to a linear DNA sequence that is contained within a 25-bp sequence of the A stem of the adeno-associated virus (AAV) terminal repeat proximal to the B and C palindromes. This has been shown conclusively by demonstrating that Rep68 could specifically bind to a synthetic oligonucleotide containing the 25-bp region in the absence of the other sequences within the terminal repeat. Rep78 was also capable of binding the A stem recognition element, as demonstrated by the fact that a DNA affinity column containing the 25-bp sequence can be used to purify Rep78. The ability to recognize the linear DNA sequence within the A stem provides a mechanism by which the Rep protein can be oriented on the terminal repeat so that only the correct strand is cut at the terminal resolution site (trs site) during terminal resolution. In addition, computer analysis suggests that sequences similar to the A stem element are present within the three AAV promoter regions. Electrophoretic mobility shift experiments clearly demonstrate that the p5 promoter contains a Rep binding sequence. DNase protection experiments indicate that the Rep binding sequence within the p5 promoter is located between the YY1 initiator sequence and the TATA binding site. This position immediately suggests a mechanism by which the Rep protein could act as a repressor or a transactivator of p5 transcription by interacting with either YY1 or TBP. In addition, gel shift experiments suggest that the p19 promoter also contains a Rep binding site. The presence of Rep binding sites upstream of both promoters suggests that these sites may be involved in coordinate regulation of AAV transcription. In addition, we have identified a heterologous Rep binding sequence within pBR322 DNA. A comparison of the sequences within the A stem, p5, and pBR322 binding sites suggests that a repeating GAGC motif is at least part of the Rep recognition sequence. In the accompanying report (D. M. McCarty, J. H. Ryan, S. Zolutukhin, X. Zhou, and N. Muzyczka, J. Virol. 68:4998-5006, 1994), we examine the relative affinity of Rep to the A stem site and the complete terminal repeat. Finally, we also have reexamined the ability of Rep68 and Rep78 to cut at the trs site in substrates that do not contain the B and C palindromes or any apparent secondary structure.(ABSTRACT TRUNCATED AT 400 WORDS)

The study of eukaryotic viral DNA replication in vitro has led to the identification of cellular enzymes involved in DNA replication. Adeno-associated virus (AAV) is distinct from previously reported systems in that it is believed to replicate entirely by leading-strand DNA synthesis and requires coinfection with adenovirus to establish completely permissive replication. In previous work, we demonstrated that two of the AAV nonstructural proteins, Rep78 and -68, are site-specific endonucleases and DNA helicases that are capable of resolving covalently closed AAV termini, a key step in AAV DNA replication. We have now cloned the AAV nonstructural proteins Rep78, Rep68, and Rep52 in the baculovirus expression system. Using the baculovirus-expressed proteins, we have developed an efficient in vitro AAV DNA replication system which mimics the in vivo behavior of AAV in every respect. With no-end AAV DNA as the starting substrate, the reaction required an adenovirus-infected cell extract and the presence of either Rep78 or Rep68. Rep52, as expected, did not support DNA replication. A mutant in the AAV terminal resolution site (trs) was defective for DNA replication in the in vitro assay. Little, if any, product was formed in the absence of the adenovirus-infected HeLa cell extract. In general, uninfected HeLa extracts were less efficient in supporting AAV DNA replication than adenovirus-infected extracts. Thus, the requirement for adenovirus infection in vivo was partially duplicated in vitro. The reduced ability of uninfected HeLa extracts to support complete DNA replication was not due to a defect in terminal resolution but rather to a defect in the reinitiation reaction or in elongation. Rep78 produced a characteristic monomer-dimer pattern of replicative intermediates, but surprisingly, Rep68 produced little, if any, dimer replicative form. The reaction had a significant lag (30 min) before incorporation of 32P-deoxynucleoside triphosphate could be detected in DpnI-resistant monomer replicative form and was linear for at least 4 h after the lag. The rate of incorporation in the reaction was comparable to that in the simian virus 40 in vitro system. Replication of the complete AAV DNA molecule was demonstrated by the following criteria. (i) Most of the monomer and dimer product DNAs were completely resistant to digestion with DpnI. (ii) Virtually all of the starting substrate was converted to heavy-light or heavy-heavy product DNA in the presence of bromo-dUTP when examined on CsCl density gradients.(ABSTRACT TRUNCATED AT 400 WORDS)

Abstract: Macroscopic fractal aggregates of KH2PH4 (KDP) measuring up to 500 m have been obtained. The fractal structure forms as a result of the precipitation of KDP particles from a supersaturated aqueous solution in the presence of a temperature gradient followed by a diffusioncontrolled mechanism of aggregation. The electron-microscopic analysis performed has shown that the fractals are formed predominantly from crystallites of the tetragonal modification measuring ∼1 m. The dielectric constant (ɛ) of fractal KH2PO4 has been measured in the temperature range 80–300 K. A characteristic anomaly has been discovered on the ɛ(T) curve in the vicinity of 122 K, which attests to a ferroelectric phase transition. The absolute value of ɛ is significantly smaller than the components ɛ 11 and ɛ 33 for KH2PO4.

Abstract: We have observed that carbon deposits obtained by atomizing graphite in an electric arc in an atmosphere of argon and helium exhibit porosity and possess fractal structure. The results of measurements of the internal friction Q −1 and the effective Young’s modulus E as a function of temperature are presented. Data on the resistivity, density, and microhardness of the carbon deposits are presented. A possible mechanism for formation of fractal structures in carbon deposits is discussed.

We describe an online database for extrasolar planetary-mass candidates, which is updated regularly as new data are available. We first discuss criteria for inclusion of objects in the catalog: “definition” of a planet and several aspects of the confidence level of planet candidates. We are led to point out the contradiction between the sharpness of criteria for belonging to a catalog and the fuzziness of the confidence level for an object to be a planet. We then describe the different tables of extrasolar planetary systems, including unconfirmed candidates (which will ultimately be confirmed, or not, by direct imaging). It also provides online tools: histograms of planet and host star data, cross-correlations between these parameters, and some Virtual Observatory services. Future evolutions of the database are presented.

We report the discovery of a new cataclysmic variable (CV) among unidentified objects from the ASCA Galactic Plane Survey made using the Virtual Observatory data mining. First, we identified AX J194939+2631with IPHAS J194938.39+263149.2, the only prominent Hαemitter among 400 sources in a 1 arcmin field of the IPHAS survey, then secured as a single faint X-ray source found in an archival Chandra dataset. Spectroscopic follow-up with the 3.5-m Calar Alto telescope confirmed its classification as a CV, possibly of magnetic nature. Our analysis suggests that AX J194939+2631 is a medium distance system (d≈ 0.6 kpc) containing a late-Kor early-Mtype dwarf as a secondary component and a partially disrupted accretion disc revealed by the double-peaked Hαline. However, additional deep observations are needed to confirm our tentative classification of this object as an intermediate polar.

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