11,021 research outputs found

    The evolution of the jet from Herbig Ae star HD 163296 from 1999 to 2011

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    Young A and B stars, the so-called Herbig Ae/Be stars (HAeBe), are surrounded by an active accretion disk and drive outflows. We study the jet HH 409, which is launched from the HAeBe star HD 163296, using new and archival observations from Chandra and HST/STIS. In X-rays we can show that the central source is not significantly extended. The approaching jet, but not the counter-jet, is detected in Ly alpha. In addition, there is red-shifted Ly alpha emission extended in the same direction as the jet, that is also absent in the counter-jet. We can rule out an accretion or disk-wind origin for this feature. In the optical we find the knots B and B2 in the counter-jet. Knot B has been observed previously, so we can derive its proper motion of 0.37+-0.01 arcsec/yr. Its electron density is 3000/cm^3, thus the cooling time scale is a few months only, so the knot needs to be reheated continuously. The shock speed derived from models of H alpha and forbidden emission lines (FELs) decreased from 50 km/s in 1999 to 30 km/s in 2011 because the shock front loses energy as it travels along the jet. Knot B2 is observed at a similar position in 2011 as knot B was in 1999, but shows a lower ionization fraction and higher mass loss rate, proving variations in the jet launching conditions.Comment: 14 pages, 8 figures, accepted by A&

    Temporal regulation of murine cytomegalovirus transcription and mapping of viral RNA synthesized at immediate early times after infection

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    The replication of murine cytomegalovirus strain Smith in murine embryonic fibroblasts was investigated at immediate early, early, and late times after infection. Cloned subgenomic HindIII fragments of murine cytomegalovirus DNA served to define the regions of transcription. At immediate early times viral RNA classes ranging in size from 5.1 to 1.05 kilobases (kb) were transcribed mainly from the fragments HindIII-K and -L, whereas low levels of transcription were detected from the two termini HindIII-E and HindIII-N. A characteristic pattern of proteins could be translated from immediate early RNA in vitro. At early and late times after infection transcription from all HindIII fragments occurred, but different patterns of transcripts and proteins could be identified. Inhibitors of DNA synthesis induced differences in the late transcription pattern, located in the HindIII-F fragment. The coding region for abundant immediate early transcription could be located at between 0.769 and 0.817 map units. A plasmic clone containing the main part (0.769 to 0.815 map units) of this region was constructed. This region coded for six polyadenylated immediate early RNA species of 5.1, 2.75, 2.0, 1.75, 1.65, and 1.05 kb in size. Only the 1.75-kb RNA originated entirely from the HindIII-L fragment. The 5.1- and 2.75-kb RNA species were encoded by both the HindIII-L and HindIII-K fragments, and the 2.0-, 1.65-, and 1.05-kb RNA species were entirely transcribed within HindIII-K

    The cytolytic T lymphocyte response to the murine cytomegalovirus

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    Limiting dilution (LD) analysis with two modifications, the expansion and the restimulation LD assay, led to the detection and quantification of two distinct in vivo maturation stages within the lineage of virus- specific self-restricted CTL after infection of mice with the murine cytomegalovirus (MCMV). A low frequency set, representing an average of 15% of the specifically activated CTL-P in a draining lymph node, generated virus-specific lytic activity in the absence of antigen, solely under expansion conditions provided by growth and differentiation interleukins. These cells were considered to be active and were denoted antigen-independent or interleukin-receptive CTL-P (IL- CTL-P). A high frequency set required additional antigen in vitro to generate functionally active clones, and therefore the cells were termed antigen-dependent. Both sets are present in vivo simultaneously at the peak of the acute immune response and represent antigen- activated cells because their existence strictly depends on a preceding priming event. IL-CTL-P disappear quickly after acute infection and are absent during the memory state. It is proposed that the isolation of IL- CTL-P could serve to detect viral antigen expression during persistent and/or recurrent herpes virus infections

    Location, transcripts, and translation products

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    Cloned genomic fragments from the region (0.769 to 0.818 map units) coding for immediate-early (IE) transcripts of murine cytomegalovirus (MCMV) were used to analyze the physical organization of this region, the direction of transcription, and the proteins synthesized in vitro. Three IE transcription units could be identified. From IE coding region 1 (ie1; 0.781 to 0.796 map units) a dominant 2.75-kilobase (kb) RNA was transcribed from right to left on the prototype arrangement of the MCMV genome which directed the synthesis of an 89,000-molecular-weight polypeptide (89K polypeptide), the major IE protein. This phosphoprotein (pp89) has been shown to be active in the regulation of transcription. Upstream of ie1 and separated by the MCMV enhancer sequence was a second IE coding region, ie2, which was mapped at 0.803 to 0.817 map units. From ie2 a 1.75-kb RNA of moderate abundance was transcribed in the direction opposite to that of the ie1 RNA. After hybrid selection of the ie2 transcript, a 43,000-molecular-weight translation product was detected. A third coding region, ie3, was located directly downstream of ie1 (0.773 to 0.781 map units). The series of RNAs with low abundance, terminating in ie3, probably used the ie1 transcription start site and ranged from 1.0 to 5.1 kb in size. The 5.1-kb RNA apparently represents the nonspliced transcript from both coding regions ie1 and ie3. A 15K polypeptide was translated in vitro from RNA that was hybrid selected by ie3 sequences. Immunoprecipitation with monoclonal antibody revealed that 31K to 67K polypeptides were related to pp89. Some of these proteins were translated from RNAs that were smaller than 2.75 kb. Polypeptides related to pp89 were also synthesized in vivo. Because polypeptides unrelated to pp89 that were translated from RNA that was selected by ie2 and ie3 sequences were not immunoprecipitated by murine antisera, we assumed that the amount of these proteins synthesized in vivo during infection was probably very lo

    Bounds on new Majoron models from the Heidelberg-Moscow-Experiment

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    In recent years several new Majoron models were invented to avoid shortcomings of the classical models while leading to observable decay rates in double beta experiments. We give the first experimental half life bounds on double beta decays with new Majoron emission and derive bounds on the effective neutrino--Majoron couplings from the data of the 76Ge^{76}Ge HEIDELBERG--MOSCOW experiment. While stringent half life limits for all decay modes and the coupling constants of the classical models were obtained, small matrix elements and phase space integrals \cite{hir95,pae95} result in much weaker limits on the effective coupling constants of the new Majoron models.Comment: 8 pages, postscript encoded as uu-fil

    A Hybrid PV-battery/diesel Electricity Supply on Peucang Island: an Economic Evaluation

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    Renewable energy technologies are currently under a dynamic cost development. This case holds especially for solar technology that has reached price levels that were unimaginable until a short time ago. It also holds for battery technologies the application of which is related to the increasing USAge of photovoltaic energy converters and the growing interest in electric vehicles. With the decreasing prices more and more possible application cases of renewable energy technologies become economically viable. A case study was done for a location on a small island located on the west tip of Java. The levelized electricity cost of a hybrid electricity supply system composed of a solar generator and battery in combination with the existing diesel generators was compared to the electricity generation cost of the existing system. Two different battery options were taken into account, lead-acid batteries and lithium-ion batteries. The results of this study can give a rough orientation also for other locations with similar characteristics
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