722 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
Detection of HC11N in the Cold Dust Cloud TMC-1
Two consecutive rotational transitions of the long cyanopolyyne HC11N,
J=39-38, and J=38-37, have been detected in the cold dust cloud TMC-1 at the
frequencies expected from recent laboratory measurements by Travers et al.
(1996), and at about the expected intensities. The astronomical lines have a
mean radial velocity of 5.8(1) km/s, in good agreement with the shorter
cyanopolyynes HC7N and HC9N observed in this very sharp-lined source [5.82(5)
and 5.83(5) km/s, respectively]. The column density of HC11N is calculated to
be 2.8x10^(11) cm^(-2). The abundance of the cyanopolyynes decreases smoothly
with length to HC11N, the decrement from one to the next being about 6 for the
longer carbon chains.Comment: plain tex 10 pages plus 3 ps fig file
Molecular Line Observations of Carbon-Chain-Producing Regions L1495B and L1521B
We present the first comprehensive study on physical and chemical properties
of quiescent starless cores L1495B and L1521B, which are known to be rich in
carbon-chain molecules like the cyanopolyyne peak of TMC-1 and L1521E. We have
detected radio spectral lines of various carbon-chain molecules such as CCS,
CS, CH, HCN, and HCN. On the other hand, the NH
lines are weak and the NH lines are not detected. According to our
mapping observations of the HCN, CCS, and CS lines, the dense cores
in L1495B and L1521B are compact with the radius of 0.063 and 0.044 pc,
respectively, and have a simple elliptical structure. The distributions of 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. Since the
HCO, HNC, and CS lines are detected in L1495B and
L1521B, the densities of these cores are high enough to excite the NH and
NH lines. Therefore, the abundances of NH and NH
relative to carbon-chain molecules are apparently deficient, as observed in
L1521E. We found that longer carbon-chain molecules such as HCN and
CH are more abundant in TMC-1 than L1495B and L1521B, while those of
sulfur-bearing molecules such as CS, CCS, and CS are comparable.
Both distributions and abundances of the observed molecules of L1495B and
L1521B are quite similar to those of L1521E, strongly suggesting that L1495B
and L1521B is in a very early stage of physical and chemical evolution.Comment: 19 pages, 6 figures, accepted to The Astrophysical Journa
Unusual Findings in the Small Bowel
AbstractSmall bowel endoscopy has now become a routine investigation. The most common methods to visualize the small bowel are balloon-assisted enteroscopy and capsule endoscopy. Currently, the most common indications for small bowel endoscopy are obscure gastrointestinal bleeding and suspected or established Crohn's disease. Common findings of small bowel endoscopy include arteriovascular malformations, erosions, ulcers, and edema in the mucosa. However, there are myriad uncommon small bowel conditions which can now be visualized endoscopically. These include vasculitis, neuroendocrine tumors, familial polyposis syndromes such as Peutz–Jeghers syndrome; ulcerative celiac disease; enteropathy-associated T-cell lymphoma; and infections such as Whipple's disease, tuberculosis, and blastomycosis. The aim of this video is to demonstrate the endoscopic characteristics of various unusual but very important small bowel diseases. This article is part of an expert video encyclopedia
The nature of the dense core population in the Pipe Nebula: A survey of NH3, CCS, and HC5N molecular line emission
Recent extinction studies of the Pipe Nebula (d=130 pc) reveal many cores
spanning a range in mass from 0.2 to 20.4 Msun. These dense cores were
identified via their high extinction and comprise a starless population in a
very early stage of development. Here we present a survey of NH3 (1,1), NH3
(2,2), CCS (2_1,1_0), and HC5N (9,8) emission toward 46 of these cores. An
atlas of the 2MASS extinction maps is also presented. In total, we detect 63%
of the cores in NH3 (1,1) 22% in NH3 (2,2), 28% in CCS, and 9% in HC5N
emission. We find the cores are associated with dense gas (~10^4 cm-3) with 9.5
< T_k < 17 K. Compared to C18O, we find the NH3 linewidths are systematically
narrower, implying that the NH3 is tracing the dense component of the gas and
that these cores are relatively quiescent. We find no correlation between core
linewidth and size. The derived properties of the Pipe cores are similar to
cores within other low-mass star-forming regions: the only differences are that
the Pipe cores have weaker NH3 emision and most show no current star formation
as evidenced by the lack of embedded infrared sources. Such weak NH3 emission
could arise due to low column densities and abundances or reduced excitation
due to relatively low core volume densities. Either alternative implies that
the cores are relatively young. Thus, the Pipe cores represent an excellent
sample of dense cores in which to study the initial conditions for star
formation and the earliest stages of core formation and evolution.Comment: 35 pages, 10 figures (excluding the appendix). For the complete
appendix contact [email protected]. Accepted for publication in ApJ
The high-velocity clouds and the Magellanic Clouds
From an analysis of the sky and velocity distributions of the high-velocity
clouds (HVCs) we show that the majority of the HVCs has a common origin. We
conclude that the HVCs surround the Galaxy, forming a metacloud of 300 kpc in
size and with a mass of 3 10^9 M_sun, and that they are the product of a
powerful ``superwind'' (about 10^58 ergs), which occurred in the Magellanic
Clouds about 570 Myr ago as a consequence of the interaction of the Large and
Small Magellanic Clouds. The HVCs might be magnetic bubbles of semi-ionized
gas, blown from the Magellanic Clouds around 570 Myr ago, that circulate
largely through the halo of the Galaxy as a stream or flow of gas.Comment: 28 pages with 23 figure
Triggered Star Formation by Massive Stars
We present our diagnosis of the role that massive stars play in the formation
of low- and intermediate-mass stars in OB associations (the Lambda Ori region,
Ori OB1, and Lac OB1 associations). We find that the classical T Tauri stars
and Herbig Ae/Be stars tend to line up between luminous O stars and
bright-rimmed or comet-shaped clouds; the closer to a cloud the progressively
younger they are. Our positional and chronological study lends support to the
validity of the radiation-driven implosion mechanism, where the Lyman continuum
photons from a luminous O star create expanding ionization fronts to evaporate
and compress nearby clouds into bright-rimmed or comet-shaped clouds. Implosive
pressure then causes dense clumps to collapse, prompting the formation of
low-mass stars on the cloud surface (i.e., the bright rim) and
intermediate-mass stars somewhat deeper in the cloud. These stars are a
signpost of current star formation; no young stars are seen leading the
ionization fronts further into the cloud. Young stars in bright-rimmed or
comet-shaped clouds are likely to have been formed by triggering, which would
result in an age spread of several megayears between the member stars or star
groups formed in the sequence.Comment: 2007, ApJ, 657, 88
Synthesis of Oligosaccharides Derived from Lactulose (OsLu) Using Soluble and Immobilized Aspergillus oryzae β-Galactosidase
β-Galactosidase from Aspergillus oryzae offers a high yield for the synthesis of oligosaccharides derived from lactulose (OsLu) by transgalactosylation. Oligosaccharides with degree of polymerization (DP) ≥ 3 have shown to possess higher in vitro bifidogenic effect than di- and tetrasaccharides. Thus, in this work, an optimization of reaction conditions affecting the specific selectivity of A. oryzae β-galactosidase for synthesis of OsLu has been carried out to enhance OsLu with DP ≥ 3 production. Assays with β-galactosidase immobilized onto a glutaraldehyde–agarose support were also carried out with the aim of making the process cost-effective and industrially viable. Optimal conditions with both soluble and immobilized enzyme for the synthesis of OsLu with DP ≥ 3 were 50 °C, pH 6.5, 450 g/L of lactulose, and 8 U/mL of enzyme, reaching yields of ca. 50% (w/v) of total OsLu and ca. 20% (w/v) of OsLu with DP 3, being 6′-galactosyl-lactulose the major one, after a short reaction time. Selective formation of disaccharides, however, was favored at 60 °C, pH 4.5, 450 g/L of lactulose and 8 U/mL of enzyme. Immobilization increased the enzymatic stability to temperature changes and allowed to reuse the enzyme. We can conclude that the use, under determined optimal conditions, of the A. oryzae β-galactosidase immobilized on a support of glutaraldehyde–agarose constitutes an efficient and cost-effective alternative to the use of soluble β-galactosidases for the synthesis of prebiotic OsLu mixturesThis work has been supported by projects AGL2014-53445-R from Ministerio de Economía y Competitividad; ALIBIRD-CM S-2013/ABI-2728 from Comunidad Autónoma de Madrid and COOPB20099 from CSI
Rapid detection of trace bacteria in biofluids using porous monoliths in microchannels
We present advancements in microfluidic technology for rapid detection of as few as 10 rickettsial organisms in complex biological samples. An immuno-reactive filter, macroporous polyacrylamide monolith (PAM), fabricated within a microfluidic channel enhances solid-phase immuno-capture, staining and detection of targeted bacteria. Bacterial cells in samples flowing through the channel are forced to interact with the PAM filter surface due to size exclusion, overcoming common transport and kinetic limitations for rapid (min), high-efficiency (~100%) capture. In the process, targeted cells in sample volumes of 10 ?l to >100 ?l are concentrated within a sub-50 nl region at the PAM filter edge in the microchannel, thus concentrating them over 1000-fold. This significantly increases sensitivity, as the hydrophilic PAM also yields low non-specific immuno-fluorescence backgrounds with samples including serum, blood and non-targeted bacteria. The concentrated target cells are detected using fluorescently-labeled antibodies. With a single 2.0�0�3 mm PAM filter, as few as 10 rickettsial organisms per 100 祃 of lysed blood sample can be analyzed within 60 min, as compared to hours or even days needed for conventional detection methods. This method is highly relevant to rapid, multiplexed, low-cost point of care diagnostics at early stages of infection where diagnostics providing more immediate and actionable test results are needed to improve patient outcomes and mitigate potential natural and non-natural outbreaks or epidemics of rickettsial diseases
Comportamiento electoral en el Quindío a partir de la reforma política de 2003
This paper presents details of the elections in Quindio State after the political amendment bill 2003, and how this amendment bill has influenced on the electoral behavior of the Colombian political parties and political movements, during the 2006 and 2007 elections.This work thoroughly shows details of the electoral behavior in every single municipality. The composition of the state councils and assembly is presented and how mayor's offices and governor's office are established. Finally, the presidential elections are examined.Los autores de esta reflexión se ocupan en detalle de las elecciones en el Departamento del Quindío a partir de la reforma política del 2003 y cómo ésta impacta el comportamiento electoral de los partidos y movimientos políticos en las elecciones de 2006 y 2007.A reglón seguido detalla el comportamiento electoral municipio por municipio, registrando la composición de concejos y de la asamblea departamental y como quedan configuradas las alcaldías y la gobernación del departamento y finalmente revisa las elecciones a presidente
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