2,470 research outputs found
Characterizations of -well-posedness for parametric quasivariational inequalities defined by bifunctions
The purpose of this paper is to investigate the
well-posedness issue of parametric quasivariational inequalities
defined by bifunctions. We generalize the concept of
-well-posedness to parametric quasivariational inequalities
having a unique solution and derive some characterizations of
-well-posedness. The corresponding concepts of
-well-posedness in the generalized sense are also introduced
and investigated for the problems having more than one solution.
Finally, we give some sufficient conditions for
-well-posedness of parametric quasivariational inequalities
Stanniocalcin-1 promotes tumor angiogenesis through up-regulation of VEGF in gastric cancer cells
<p>Abstract</p> <p>Background</p> <p>Stanniocalcin-1(STC-1) is up-regulated in several cancers including gastric cancer. Evidences suggest that STC-1 is associated with carcinogenesis and angiogenic process. However, it is unclear on the exact role for STC-1 in inducing angiogenesis and tumorigeneisis.</p> <p>Method</p> <p>BGC/STC cells (high-expression of STC-1) and BGC/shSTC cells (low- expression of STC-1) were constructed to investigate the effect of STC-1 on the xenograft tumor growth and angiogenesis <it>in vitro </it>and <it>in vivo</it>. ELISA assay was used to detect the expression of vascular endothelial growth factor (VEGF) in the supernatants. Neutralizing antibody was used to inhibit VEGF expression in supernatants. The expression of phosphorylated -PKCβII, phosphorylated -ERK1/2 and phosphorylated -P38 in the BGC treated with STC-1protein was detected by western blot.</p> <p>Results</p> <p>STC-1 could promote angiogenesis <it>in vitro </it>and <it>in vivo</it>, and the angiogenesis was consistent with VEGF expression <it>in vitro</it>. Inhibition of VEGF expression in supernatants with neutralizing antibody markedly abolished angiogenesis induced by STC-1 <it>in vitro</it>. The process of STC-1-regulated VEGF expression was mediated via PKCβII and ERK1/2.</p> <p>Conclusions</p> <p>STC-1 promotes the expression of VEGF depended on the activation of PKCβII and ERK1/2 pathways. VEGF subsequently enhances tumor angiogenesis which in turn promotes the gastric tumor growth.</p
HII region G46.5-0.2: the interplay between ionizing radiation, molecular gas and star formation
HII regions are particularly interesting because they can generate dense
layers of gas and dust, elongated columns or pillars of gas pointing towards
the ionizing sources, and cometary globules of dense gas, where triggered star
formation can occur. Understanding the interplay between the ionizing radiation
and the dense surrounding gas is very important to explain the origin of these
peculiar structures, and hence to characterize triggered star formation.
G46.5-0.2 (G46), a poorly studied galactic HII region located at about 4 kpc,
is an excellent target to perform this kind of studies. Using public molecular
data extracted from the Galactic Ring Survey (13CO J=1-0) and from the James
Clerk Maxwell Telescope data archive (12CO, 13CO, C18O J=3-2, HCO+ and HCN
J=4-3), and infrared data from the GLIMPSE and MIPSGAL surveys, we perform a
complete study of G46, its molecular environment and the young stellar objects
placed around it. We found that G46, probably excited by an O7V star, is
located close to the edge of the GRSMC G046.34-00.21 molecular cloud. It
presents a horse-shoe morphology opening in direction of the cloud. We observed
a filamentary structure in the molecular gas likely related to G46 and not
considerable molecular emission towards its open border. We found that about
10' towards the southwest of G46 there are some pillar-like features, shining
at 8 um and pointing towards the HII region open border. We propose that the
pillar-like features were carved and sculpted by the ionizing flux from G46. We
found several young stellar objects likely embedded in the molecular cloud
grouped in two main concentrations: one, closer to the G46 open border
consisting of Class II type sources, and other one mostly composed by Class I
type YSOs located just ahead the pillars-like features, strongly suggesting an
age gradient in the YSOs distribution.Comment: Accepted for publication in The Astronomical Journal (April 14,
2015). Some figures were degraded to reduce file siz
Interactions of the Infrared bubble N4 with the surroundings
The physical mechanisms that induce the transformation of a certain mass of
gas in new stars are far from being well understood. Infrared bubbles
associated with HII regions have been considered to be good samples of
investigating triggered star formation. In this paper we report on the
investigation of the dust properties of the infrared bubble N4 around the HII
region G11.898+0.747, analyzing its interaction with its surroundings and star
formation histories therein, with the aim of determining the possibility of
star formation triggered by the expansion of the bubble. Using Herschel PACS
and SPIRE images with a wide wavelength coverage, we reveal the dust properties
over the entire bubble. Meanwhile, we are able to identify six dust clumps
surrounding the bubble, with a mean size of 0.50 pc, temperature of about 22 K,
mean column density of 1.7 cm, mean volume density of
about 4.4 cm, and a mean mass of 320 . In
addition, from PAH emission seen at 8 m, free-free emission detected at 20
cm and a probability density function in special regions, we could identify
clear signatures of the influence of the HII region on the surroundings. There
are hints of star formation, though further investigation is required to
demonstrate that N4 is the triggering source.Comment: Accepted by ApJ (16 pages, 11 figures, 9 tables
Optimal extraction parameters of Theabrownin from Sichuan Dark Tea
Background: Sichuan Dark Tea is a popular beverage with hypolipidemic and lifting greasy properties in the minority neighborhoods of Sichuan and Tibet regions. The theabrownin, an important pigment of dark tea, has been proven for the role of the hypolipidemic property in Sichuan Dark Tea. The objective of the study investigated the extraction process of theabrownin.Materials and Methods: Theabrownin was extracted from Sichuan Dark Tea with water and organic solvents. The quadratic regression orthogonally rotational combinational design experiment was performed to obtain the optimal extraction parameters.Results: The extraction yield of theabrownin was significantly influenced by both water extraction temperature and solid-liquid ratio, and the contribution of these factors on theabrownin yield was as follows: water temperature﹥solid-liquid ratio﹥organic solvent temperature. Moreover, the polynomial regression model established could predict the experimental value accurately.Conclusion: The optimum extraction process of theabrownin from Sichuan Dark Tea was established, which water temperature at 65.69-77.88℃, organic solvent temperature at 13.65-17.48℃ and a solid liquid ratio of 1:43.58-1:50.75(g/mL).Keywords: theabrownin; extraction; optimization; Sichuan Dark TeaAbbreviations list: SDT: Sichuan Dark Tea; TB: Theabrowni
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