534 research outputs found
L1521E: A Starless Core in the Early Evolutionary Stage ?
We have studied the physical and chemical properties of a quiescent starless
core L1521E with various molecular lines. It is found that there exists a
compact dense core traced by the H^13CO^+, HN^13C, CCS, and HC_3N lines; their
distributions have a single peak at the same position. The core radius is as
small as 0.031 pc, whereas the H_2 density at the peak position is as high as
(1.3-5.6)times10^5 cm^-3. Although the density is high enough to excite the
inversion transitions of NH_3, these lines are found to be very faint in
L1521E. The distributions of NH_3 and CCS seem to be different from those of
well-studied starless cores, L1498 and L1544, where the distribution of CCS
shows a shell-like structure while that of NH_3 is concentrated at the center
of the core. Abundances of carbon-chain molecules are higher in L1521E than the
other dark cloud cores, and especially those of sulfur-bearing molecules C_nS
are comparable to the cyanopolyyne peak of TMC-1. Our results suggest that
L1521E would be in a very early stage of physical and chemical evolution.Comment: 10 pages, 3 EPS figures, uses aaspp4.sty and epsf.sty, AAS LaTeX
macros v4.0, The Astrophysical Journal, in pres
Impact of inflammation-based prognostic score on survival after curative thoracoscopic esophagectomy for esophageal cancer
AbstractBackgroundDespite recent improvements in early detection, progress in surgical techniques, and development of chemoradiation therapies, prognosis of esophageal cancer remains poor. The aim of the present study was to assess whether Glasgow Prognostic Score (GPS), an inflammation-based prognostic score, has prognostic value independent of conventional clinicopathological criteria in patients undergoing curative resection for esophageal cancer, even in elderly patients.MethodsWe retrospectively reviewed the database of 141 consecutive patients with histologically verified esophageal squamous cell carcinoma who underwent potentially curative surgery in our institute, between January 2006 and December 2014. GPS and neutrophil lymphocyte ratio (NLR) were calculated.ResultsOn multivariate analysis, TNM stage (p < 0.0001) and GPS (p = 0.041) were independently associated with worse prognosis in overall patients with esophageal cancer.Multivariate analysis evaluated the prognostic factors in two different patient groups: patients younger than 70 years (non-elderly) and those aged 70 years or more (elderly).Multivariate analysis demonstrated that TNM stage (p = 0.0003) was an only independent risk factor for a worse prognosis among non-elderly group. Meanwhile, multivariate analysis demonstrated that TNM stage (p = 0.001) and GPS (p = 0.043) were the independent risk factor for a worse prognosis among elderly group.ConclusionThe present study demonstrated that GPS is associated with prognosis and can be considered as an independent prognostic marker in patients who underwent esophagectomy. Moreover, the GPS has the advantage of being simple to measure, routinely available and well standardized. But the present study failed to confirm the NLR as a significant predictor of survival following resection for esophageal cancer
Mapping Observations of DNC and HN^13C in Dark Cloud Cores
We present results of mapping observations of the DNC, HN^13C, and H^13CO^+
lines (J=1-0) toward 4 nearby dark cloud cores, TMC-1, L1512, L1544, and L63,
along with observations of the DNC and HN^13C lines (J=2-1) toward selected
positions. By use of statistical equilibrium calculations based on the LVG
model, the H_2 densities are derived to be (1.4-5.5)*10^5 cm^-3, and the
[DNC]/[HN^13C] ratios are derived to be 1.25-5.44 with a typical uncertainty by
a factor of 2. The observed [DNC]/[HNC] ratios range from 0.02 to 0.09,
assuming the [^12C]/[^13C] ratio of 60. Distributions of DNC and HN^13C are
generally similar to each other, whereas the distribution of H^13CO^+ is more
extended than those of DNC and HN^13C, indicating that they reside in an inner
part of the cores than HCO^+. The [DNC]/[HN^13C] ratio is rather constant
within each core, although a small systematic gradients are observed in TMC-1
and L63. Particularly, no such systematic gradient is found in L1512 and L1544,
where a significant effect of depletion of molecules is reported toward the
central part of the cores. This suggests that the [DNC]/[HNC] ratio would not
be very sensitive to depletion factor, unlike the [DCO^+]/[HCO^+] ratio. On the
other hand, the core to core variation of the [DNC]/[HNC] ratio, which range an
order of magnitude, is more remarkable than the variation within each core.
These results are interpreted qualitatively by a combination of three competing
time-dependent processes; gas-phase deuterium fractionation, depletion of
molecules onto grain surface, and dynamical evolution of a core.Comment: 22 pages, 8 EPS figures, aasLaTex 5.0, accepted to The Astrophysical
Journa
On the Influence of Uncertainties in Chemical Reaction Rates on Results of the Astrochemical Modelling
With the chemical reaction rate database UMIST95 (Millar et al. 1997) we
analyze how uncertainties in rate constants of gas-phase chemical reactions
influence the modelling of molecular abundances in the interstellar medium.
Random variations are introduced into the rate constants to estimate the
scatter in theoretical abundances. Calculations are performed for dark and
translucent molecular clouds where gas phase chemistry is adequate. Similar
approach was used by Pineau des Forets & Roueff (2000) for the study of
chemical bistability. All the species are divided into 6 sensitivity groups
according to the value of the scatter in their model abundances computed with
varied rate constants. It is shown that the distribution of species within
these groups depends on the number of atoms in a molecule and on the adopted
physical conditions. The simple method is suggested which allows to single out
reactions that are most important for the evolution of a given species.Comment: 4 pages. To appear in the proceedings of the 4th Cologne-Bonn Zermatt
Symposiu
Ion-dispersion and rapid electron fluctuations in the cusp: a case study
We present results from co-ordinated measurements with the low altitude REIMEI satellite and the ESR (EISCAT Svalbard Radar), together with other ground-based instruments carried out in February 2006. The results mainly relate to the dayside cusp where clear signatures of so-called ion-dispersion are seen in the satellite data. The cusp ion-dispersion is important for helping to understand the temporal and spatial structure of magnetopause reconnection. Whenever a satellite crosses boundaries of flux tubes or convection cells, cusp structures such as ion-dispersion will always be encountered. In our case we observed 3 distinct steps in the ion energy, but it includes at least 2 more steps as well, which we interpret as temporal features in relation to pulsed reconnection at the magnetopause. In addition, fast variations of the electron flux and energy occurring during these events have been studied in detail. The variations of the electron population, if interpreted as structures crossed by the REIMEI satellite, would map near the magnetopause to similar features as observed previously with the Cluster satellites. These were explained as Alfvén waves originating from an X-line of magnetic reconnection
Crucial Role of MLL for the Maintenance of Memory T Helper Type 2 Cell Responses
SummaryThe Mixed-Lineage Leukemia (MLL) gene, a mammalian homolog of the Drosophila trithorax, is implicated in regulating the maintenance of Hox gene expression and hematopoiesis. The physiological functions of MLL in the immune system remain largely unknown. Although MLL+/â CD4 T cells differentiate normally into antigen-specific effector Th1/Th2 cells in vitro, the ability of memory Th2 cells to produce Th2 cytokines was selectively reduced. Furthermore, histone modifications at the Th2 cytokine gene loci were not properly maintained in MLL+/â memory Th2 cells. The reduced expression of MLL in memory Th2 cells resulted in decreased GATA3 expression accompanied with impaired GATA3 locus histone modifications. The direct association of MLL with the GATA3 locus and the Th2 cytokine gene loci was demonstrated. Memory Th2 cell-dependent allergic airway inflammation was decreased in MLL+/â Th2 cell-transferred mice. Thus, a crucial role for MLL in the maintenance of memory Th2 cell function is indicated
Molecular Line Observations of a Carbon-Chain-Rich Core L492
We report on molecular abundances and distributions in a starless dense core
L492. We have found that the abundances of carbon-chain molecules such as CCS,
CS, HCN, HCN, and HCN are comparable to those in
chemically young dark cloud cores called "carbon-chain--producing regions",
such as L1495B, L1521B, L1521E, and TMC-1. This is the first dark cloud core
with extremely rich in carbon-chain-molecules that is found outside the Taurus
region. In addition, the deuterium fractionation ratios of DNC/HNC and
DCO/HCO are also comparable to those in carbon-chain--producing
regions, being significantly lower than those in the evolved prestellar cores
such as L1498 and L1544. On the other hand, the abundances of NH and
NH are systematically higher than those in carbon-chain--producing
regions. Our mapping observations reveal that the central hole of molecular
distributions, which were reported for CCS and CS in evolved prestellar
cores is not significant in L492, indicating that the depletion factor of
molecules is not very high. Furthermore, L492 is dynamically more evolved than
carbon-chain--producing regions, and the protostellar collapse has started like
L1498 and L1544. Therefore, it is likely that the chemical and dynamical
evolutionary stage of L492 is intermediate between carbon-chain--producing
regions (L1495B, L1521B, L1521E, and TMC-1) and evolved prestellar cores (L1498
and L1544).Comment: 26 pages, 8 figures, accepted for publication in The Astrophysical
Journal (Preprint with high resolution figures will be available at
http://www.nro.nao.ac.jp/library/report/list.html
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