Microwave and millimeter wave spectroscopy in the slightly hole-doped ladders of Sr14_{14}Cu24_{24}O41_{41}

We have measured the temperature- and frequency dependence of the microwave and millimeter wave conductivity $\sigma_1(T,\omega)$ along both the ladder (c-axis) and the leg (a-axis) directions in Sr$_{14}$Cu$_{24}$O$_{41}$. Below a temperature $T^*$($\sim$170 K), we observed a stronger frequency dependence in $\sigma_1^c(T,\omega)$ than that in $\sigma_1^a(T,\omega)$, forming a small resonance peak developed between 30 GHz and 100 GHz. We also observed nonlinear dc conduction along the c-axis at rather low electric fields below $T^*$. These results suggest some collective excitation contributes to the c-axis charge dynamics of the slightly hole-doped ladders of Sr$_{14}$Cu$_{24}$O$_{41}$ below $T^*$.Comment: 7 pages, 4 figure, to be published in Europhysics Letter

H2O Maser Observations of Candidate Post-AGB Stars and Discovery of Three High-velocity Water Sources

We present the results of 22 GHz H_2O maser observations of a sample of 85 post-Asymptotic Giant Branch (post-AGB) candidate stars, selected on the basis of their OH 1612 MHz maser and far-infrared properties. All sources were observed with the Tidbinbilla 70-m radio telescope and 21 detections were made. 86 GHz SiO Mopra observations of a subset of the sample are also presented. Of the 21 H_2O detections, 15 are from sources that are likely to be massive AGB stars and most of these show typical, regular H_2O maser profiles. In contrast, nearly all the detections of more evolved stars exhibited high-velocity H_2O maser emission. Of the five sources seen, v223 (W43A, IRAS 18450-0148) is a well known `water-fountain' source which belongs to a small group of post-AGB stars with highly collimated, high-velocity H_2O maser emission. A second source in our sample, v270 (IRAS 18596+0315), is also known to have high-velocity emission. We report the discovery of similar emission from a further three sources, d46 (IRAS 15445-5449), d62 (IRAS 15544-5332) and b292 (IRAS 18043-2116). The source d46 is an evolved post-AGB star with highly unusual maser properties. The H_2O maser emission from d62 is probably associated with a massive star. The source b292 is a young post-AGB star that is highly likely to be a water-fountain source, with masers detected over a velocity range of 210 km s^{-1}.Comment: 47 pages, 9 figures, 4 tables, accepted by Ap

The 2006 Radio Outburst of a Microquasar Cyg X-3: Observation and Data

We present the results of the multi-frequency observations of radio outburst of the microquasar Cyg X-3 in February and March 2006 with the Nobeyama 45-m telescope, the Nobeyama Millimeter Array, and the Yamaguchi 32-m telescope. Since the prediction of a flare by RATAN-600, the source has been monitored from Jan 27 (UT) with these radio telescopes. At the eighteenth day after the quench of the activity, successive flares exceeding 1 Jy were observed successfully. The time scale of the variability in the active phase is presumably shorter in higher frequency bands. We also present the result of a follow-up VLBI observation at 8.4 GHz with the Japanese VLBI Network (JVN) 2.6 days after the first rise. The VLBI image exhibits a single core with a size of <8 mas (80 AU). The observed image was almost stable, although the core showed rapid variation in flux density. No jet structure was seen at a sensitivity of $T_b = 7.5\times 10^5$ K.Comment: 17 pages,6 figures; accepted by PAS

Circumstellar masers in the Magellanic Clouds

We have searched for 22 GHz H2O and 43/86/129 GHz SiO masers in bright IRAS point sources in the SMC and LMC, to test whether the kinematics of the mass loss from these stars depends on metallicity. H2O masers were detected in the red supergiants IRAS04553-6825 and IRAS05280-6910, and tentatively in the luminous IR object IRAS05216-6753 and the AGB star IRAS05329-6708. SiO masers were detected in IRAS04553-6825. The outflow velocity increases between the H2O masing zone near the dust-formation region and the more distant OH masing zone from 18 to 26 km/s for IRAS04553-6825 and from 6 to 17 km/s for IRAS05280-6910. The total sample of LMC targets is analysed in comparison with circumstellar masers in the Galactic Centre. The photon fluxes of circumstellar masers in the LMC are very similar to those in the Galactic Centre. The expansion velocities in the LMC appear to be 20% lower than for similarly bright OH masers in the Galactic Centre, but the data are consistent with no difference in expansion velocity. OH/IR stars in the LMC appear to have slower accelerating envelopes than OH/IR stars in the Galactic Centre. Masers in the LMC have blue-asymmetric emission profiles. This may be due to the amplification of stellar and/or free-free radiation, rather than the amplification of dust emission, and may be more pronounced in low metallicity envelopes. SiO maser strength increases with the photometric amplitude at 2.2 micron but is independent of the photometric amplitude at 10 micron. This suggests a strong connection between shocks in the dust-free SiO masing zone and the dust formation process. Appendices describe H2O maser emission from R Dor in the Milky Way, optical echelle spectroscopy of IRAS04553-6825, and the properties of masers in the Galactic Centre (Abridged).Comment: 19 pages, 17 figures. Accepted for publication in Astronomy & Astrophysics Main Journa

Microstructure and kinematics of H2O masers in the massive star forming region IRAS 06061+2151

We have made multi-epoch VLBI observations of H2O maser emission in the massive star forming region IRAS 06061+2151 with the Japanese VLBI network (JVN) from 2005 May to 2007 October. The detected maser features are distributed within an 1\arcsec$\times$1\arcsec (2000 au$\times$2000 au at the source position) around the ultra-compact H {\small\bf II} region seen in radio continuum emission. Their bipolar morphology and expanding motion traced through their relative proper motions indicate that they are excited by an energetic bipolar outflow. Our three-dimensional model fitting has shown that the maser kinematical structure in IRAS 06061+2151 is able to be explained by a biconical outflow with a large opening angle ($>$ 50\degr). The position angle of the flow major axis coincides very well with that of the large scale jet seen in 2.1\:\mu\rmn{m} hydrogen emission. This maser geometry indicates the existence of dual structures composed of a collimated jet and a less collimated massive molecular flow. We have also detected a large velocity gradient in the southern maser group. This can be explained by a very small (on a scale of several tens of au) and clumpy (the density contrast by an order of magnitude or more) structure of the parental cloud. Such a structure may be formed by strong instability of shock front or splitting of high density core.Comment: 14 pages, 6 figures accepted for publication in MNRA

Single-cell RNA-sequencing resolves self-antigen expression during mTEC development

The crucial capability of T cells for discrimination between self and non-self peptides is based on negative selection of developing thymocytes by medullary thymic epithelial cells (mTECs). The mTECs purge autoreactive T cells by expression of cell-type specific genes referred to as tissue-restricted antigens (TRAs). Although the autoimmune regulator (AIRE) protein is known to promote the expression of a subset of TRAs, its mechanism of action is still not fully understood. The expression of TRAs that are not under the control of AIRE also needs further characterization. Furthermore, expression patterns of TRA genes have been suggested to change over the course of mTEC development. Herein we have used single-cell RNA-sequencing to resolve patterns of TRA expression during mTEC development. Our data indicated that mTEC development consists of three distinct stages, correlating with previously described jTEC, mTEChi and mTEClo phenotypes. For each subpopulation, we have identified marker genes useful in future studies. Aire-induced TRAs were switched on during jTEC-mTEC transition and were expressed in genomic clusters, while otherwise the subsets expressed largely overlapping sets of TRAs. Moreover, population-level analysis of TRA expression frequencies suggested that such differences might not be necessary to achieve efficient thymocyte selection.RM is supported by a PhD Fellowship from the Fundação para a Ciência e Tecnologia, Portugal (SFRH/ BD/51950/2012). XZ is supported by an Advanced Postdoc Mobility Fellowship from the Swiss National Science Foundation (SNSF, grant number P300P2_151352). Part of the work was performed during XZ’s visit to the Simons Institute for the Theory of Computing. TL is supported by the Academy of Finland (Decision 311081). The authors would like to thank Bee Ling Ng and the staff of the Cytometry Core Facility, and Stephan Lorenz and the staff of the Single Cell Genomics Core Facility for their contribution. Mark Lynch is acknowledged for technical assistance with the Fluidigm C1 platform. Mike Stubbington and Kylie James are acknowledged for revising the language of the manuscript. We thank Sarah Teichmann for help and discussions regarding the manuscript.info:eu-repo/semantics/publishedVersio

Globular-shaped variable lymphocyte receptors B antibody multimerized by a hydrophobic clustering in hagfish

In hagfish and lampreys, two representative jawless vertebrates, the humoral immunity is directly mediated by variable lymphocyte receptors B (VLRBs). Both monomeric VLRBs are structurally and functionally similar, but their C-terminal tails differ: lamprey VLRB has a Cys-rich tail that forms disulfide-linked pentamers of dimers, contributing to its multivalency, whereas hagfish VLRB has a superhydrophobic tail of unknown structure. Here, we reveal that VLRBs obtained from hagfish plasma have a globular-shaped multimerized form (approximately 0.6 to 1.7 MDa) that is generated by hydrophobic clustering instead of covalent linkage. Electron microscopy (EM) and single-particle analysis showed that the multimerized VLRBs form globular-shaped clusters with an average diameter of 28.7 ± 2.2 nm. The presence of VLRBs in the complex was confirmed by immune-EM analysis using an anti-VLRB antibody. Furthermore, the hydrophobic hagfish C-terminus (HC) was capable of triggering multimerization and directing the cellular surface localization via a glycophosphatidylinositol linkage. Our results strongly suggest that the hagfish VLRB forms a previously unknown globular-shaped antibody. This novel identification of a structurally unusual VLRB complex may suggest that the adaptive immune system of hagfish differs from that of lamprey