Spectroscopic Observations of Several Stars Toward the Bok Globule B361

Low dispersion spectroscopic observations have been made of six of the stars toward the Bok globule B361 in order to improve the reliability of the distance to this dark cloud. Five of the six stars have been selected from Schmidt (1975) to confirm and supplement his Photometric data. The results of our MK classification of these stars reduce the uncertainty of the luminosity of the stars as well as they agree well with those by Schmidt in spectral type. Supplemented by our luminosity class estimation, Schmidt\u27s data are used to re-evaluate the distances to the stars. The resultant distance-extinction diagram indicates a more reliable distance to B361 of 400 pc

Scalable Socket Buffer Tuning for High-Performance Web Servers

Although many research efforts have been devoted to network congestion in the face of an increase in the Internet traffic, there is little recent discussion on performance improvements for endhosts. In this paper, we propose a new architecture, called Scalable Socket Buffer Tuning (SSBT), to provide high-performance and fair service for many TCP connections at Internet endhosts. SSBT has two major features. One ist to reduce the number..

Therapy for pneumonitis and sialadenitis by accumulation of CCR2-expressing CD4(+)CD25(+ )regulatory T cells in MRL/lpr mice

Adoptive transfer of CD4(+)CD25(+ )regulatory T cells has been shown to have therapeutic effects in animal models of autoimmune diseases. Chemokines play an important role in the development of autoimmune diseases in animal models and humans. The present study was performed to investigate whether the progression of organ-specific autoimmune diseases could be reduced more markedly by accumulating chemokine receptor-expressing CD4(+)CD25(+ )regulatory T cells efficiently in target organs in MRL/MpJ-lpr/lpr (MRL/lpr) mice. CD4(+)CD25(+)Foxp3(+ )T cells (Treg cells) and CD4(+)CD25(+)Foxp3(+ )CCR2-transfected T cells (CCR2-Treg cells) were transferred via retro-orbital injection into 12-week-old MRL/lpr mice at the early stage of pneumonitis and sialadenitis, and the pathological changes were evaluated. Expression of monocyte chemoattractant protein-1 (MCP-1)/CCL2 was observed in the lung and submandibular gland of the mice and increased age-dependently. The level of CCR2 expression and MCP-1 chemotactic activity of CCR2-Treg cells were much higher than those of Treg cells. MRL/lpr mice to which CCR2-Treg cells had been transferred showed significantly reduced progression of pneumonitis and sialadenitis in comparison with MRL/lpr mice that had received Treg cells. This was due to more pronounced migration of CCR2-Treg cells and their localization for a longer time in MCP-1-expressing lung and submandibular gland, resulting in stronger suppressive activity. We prepared chemokine receptor-expressing Treg cells and demonstrated their ability to ameliorate disease progression by accumulating in target organs. This method may provide a new therapeutic approach for organ-specific autoimmune diseases in which the target antigens remain undefined

Overexpression of Nuclear Receptor 5A1 Induces and Maintains an Intermediate State of Conversion between Primed and Naive Pluripotency

Naive and primed human pluripotent stem cells (hPSCs) have provided useful insights into the regulation of pluripotency. However, the molecular mechanisms regulating naive conversion remain elusive. Here, we report intermediate naive conversion induced by overexpressing nuclear receptor 5A1 (NR5A1) in hPSCs. The cells displayed some naive features, such as clonogenicity, glycogen synthase kinase 3β, and mitogen-activated protein kinase (MAPK) independence, expression of naive-associated genes, and two activated X chromosomes, but lacked others, such as KLF17 expression, transforming growth factor β independence, and imprinted gene demethylation. Notably, NR5A1 negated MAPK activation by fibroblast growth factor 2, leading to cell-autonomous self-renewal independent of MAPK inhibition. These phenotypes may be associated with naive conversion, and were regulated by a DPPA2/4-dependent pathway that activates the selective expression of naive-associated genes. This study increases our understanding of the mechanisms regulating the conversion from primed to naive pluripotency

An evolved disk surrounding the massive main sequence star MWC 297?

We present the results of the interferometric observations of the circumstellar disk surrounding MWC 297 in the continuum at 230 GHz (1.3 mm) and in the (J=2-1) rotational transitions of $^{12}$CO,$^{13}$CO and C$^{18}$O using the Submillimeter Array. At a distance of 250 pc, MWC 297 is one of the closest, young massive stars (M$_{\star}$ $\sim$10 M$_{\odot}$) to us. Compact continuum emission is detected towards MWC 297 from which we estimate a disk mass (gas+dust) of 0.07 M$_{\odot}$ and a disk radius of $\le$ 80 AU. Our result demonstrates that circumstellar disks can survive around massive stars well into their main sequence phase even after they have become optically visible. Complementing our observations with the data compiled from the literature, we find the submm dust opacity index $\beta$ to be between 0.1 and 0.3. If the emission is optically thin, the low value of $\beta$ indicates the presence of relatively large grains in the disk, possibly because of grain growth. We do not detect any CO emission associated with the continuum source. We argue that the $^{13}$CO emission from the disk is likely optically thin, in which case, we derive an upper limit to the gas mass which implies significant depletion of molecular gas in the disk. The mass of this disk and the evolutionary trends observed are similar to those found for intermediate mass Herbig Ae stars and low mass T Tauri stars.Comment: 4 pages, 3 Figures, accepted for publication in ApJ

Submillimeter Array Observation of the Proto-Planetary Nebula CRL 618 in the CO J=6-5 Line

We report on the results of a Submillimeter Array interferometric observation of the proto-planetary nebula CRL 618 in the 12CO J=6-5 line. With the new capability of SMA enabling us to use two receivers at a time, we also observed simultaneously in the 12CO J=2-1 and 13CO J=2-1 lines. The 12CO J=6-5 and 13CO J=2-1 lines were first interferometrically observed toward CRL 618. The flux of the high velocity component of the 12CO J=6-5 line is almost fully recovered, while roughly 80% of the flux of the low velocity component is resolved out. The low recovery rate suggests that the emission region of the low velocity component of the 12CO J=6-5 line is largely extended. Continuum emission is detected both at 230 and 690 GHz. The flux of the 690 GHz continuum emission seems to be partially resolved out, suggesting dust emission partly contaminates the 690 GHz continuum flux. The cavity structure, which has been confirmed in a previous observation in the 12CO J=2-1 line, is not clearly detected in the 12CO J=6-5 line, and only the south wall of the cavity is detected. This result suggests that the physical condition of the molecular envelope of CRL 618 is not exactly axial symmetric.Comment: 24 pages, 9 figures, 1 table, accepted for publication in AJ. Full resolution version available at http://www.asiaa.sinica.edu.tw/~junichi/paper

The star-forming core of Monoceros R2

Publisher's version/PDFThe central region of the Monoceros R2 molecular cloud has been studied using molecular line maps, maps in continuum emission, and an M-band (4.7 [micrometres]) absorption spectrum toward Mon R2 IRS 3. Maps were made in the emission lines CO (3-2) H[subscript 2]CO (5[subscript 1.5]-4[subscript 1.4), and HCN (4-3), all with a 14" beam size. CO (2-1) and [superscript 13]CO (3-2) spectra were obtained at a dozen positions. Maps of continuum emission were made at 1300 [micrometres] (25" resolution), 1100 [micrometres] (20" resolution), 800 [micrometres] (14" resolution), and 450 [micrometres] (14" resolution). The M-band spectrum of IRS 3 has a velocity resolution of 5.2 km s[superscript -1] and shows fundamental vibrational band absorption lines of CO and [superscript 13]CO over a range of rotational states. The CO map has numerous intensity peaks which, if interpreted as clumps, have masses from 0.1 to 3 M [subscript circled dot]. The large velocity dispersion of these structures implies that they cannot be gravitationally bound. The brightest CO-emitting gas shows no bipolar distribution with velocity. Diffuse CO-emitting gas with low velocities does have a generally bipolar distribution, but there are no collimated lobes pointing to a particular source. We conclude that the source (or sources) of the very extended Mon R2 outflow is (are) now inactive. The highest velocity gas is found toward the embedded young stellar object IRS 3, suggesting that IRS 3 is the source of a compact outflow, unresolved at our 14" resolution. The presence of blueshifted CO in the absorption spectrum supports the interpretation of IRS 3 as an outflow source. The H[subscript 2]CO and HCN maps demonstrate that much of the dense gas is distributed within three structures having different velocities. The fundamental band absorption lines of [superscript 13]CO show two gas temperatures in the line of sight to IRS 3. The colder (45 K) is identified as gas in the clump surrounding IRS 3, which is seen in emission lines of CO, H[subscript 2]CO, and HCN. The warmer (310 K) we interpret as gas very close to IRS 3. From the submillimeter continuum maps we identify 11 clumps whose masses lie in the range 3-10 M [subscript circled dot]. A clump that is prominent in the continuum maps but not in the molecular line maps is attributed to heated dust inside the compact H II region, where molecules have been destroyed