160 research outputs found
Wide-Field Infrared Imaging Polarimetry of the NGC 6334 Region: A Nest of Infrared Reflection Nebulae
We report the detection of eighteen infrared reflection nebulae (IRNe) in the
, , & linear polarimetric observations of the NGC 6334 massive
star-formation complex, of which 16 IRNe are new discoveries. Our images cover
180 square arcminutes, one of the widest near-infrared polarization data
in star-formation regions so far. These IRNe are most likely associated with
embedded young OB stars at different evolutionary phases, showing a variety of
sizes, morphologies, and polarization properties, which can be divided into
four categories. We argue the different nebula characteristics to be a possible
evolutionary sequence of circumstellar structures around young massive stars.Comment: 4 pages, 1 figur
V1647 Orionis (IRAS 05436-0007) : A New Look at McNeil's Nebula
We present a study of the newly discovered McNeil's nebula in Orion using the
JHKs-band simultaneous observations with the near-infrared (NIR) camera SIRIUS
on the IRSF 1.4m telescope. The cometary infrared nebula is clearly seen
extending toward north and south from the NIR source (V1647 Orionis) that
illuminates McNeil's nebula. The compact nebula has an apparent diameter of
about 70 arcsec. The nebula is blue (bright in J) and has a cavity structure
with two rims extending toward north-east and north-west. The north-east rim is
brighter and sharp, while the north-west rim is diffuse. The north-east rim can
be traced out to ~ 40 arcsec from the location of the NIR source. In contrast,
no cavity structure is seen toward the south, although diffuse nebula is
extended out to ~ 20 arcsec. New NIR photometric data show a significant
variation in the magnitudes (> 0.15 mag) of the source of McNeil's nebula
within a period of one week, that is possibly under the phase of eruptive
variables like FUors or EXors.Comment: 13 pages, 5 figures in JPEG format. Accepted for the publication in
PASJ Letter
Eicosapentaenoic acid inhibits voltage-gated sodium channels and invasiveness in prostate cancer cells
Background and purpose: The voltage-gated Na + channels (Nav) and their corresponding current (INa) are involved in several cellular processes, crucial to metastasis of cancer cells. We investigated the effects of eicosapentaenoic (EPA), an omega-3 polyunsaturated fatty acid, on INa and metastatic functions (cell proliferation, endocytosis and invasion) in human and rat prostate cancer cell lines (PC-3 and Mat-LyLu cells). Experimental approach: The whole-cell voltage clamp technique and conventional/quantitative real-time reverse transcriptase polymerase chain reaction analysis were used. The presence of Nav proteins was shown by immunohistochemical methods. Alterations in the fatty acid composition of phospholipids after treatment with EPA and metastatic functions were also examined. Key results: A transient inward Na + current (INa), highly sensitive to tetrodotoxin, and NaV proteins were found in these cells. Expression of NaV1.6 and NaV1.7 transcripts (SCN8A and SCN9A) was predominant in PC-3 cells, while NaV1.7 transcript (SCN9A) was the major component in Mat-LyLu cells. Tetrodotoxin or synthetic small interfering RNA targeted for SCN8A and SCN9A inhibited metastatic functions (endocytosis and invasion), but failed to inhibit proliferation in PC-3 cells. Exposure to EPA produced a rapid and concentration-dependent suppression of INa. In cells chronically treated (up to 72h) with EPA, the EPA content of cell lipids increased time-dependently, while arachidonic acid content decreased. Treatment of PC-3 cells with EPA decreased levels of mRNA for SCN9A and SCN8A, cell proliferation, invasion and endocytosis. Conclusion and implications: Treatment with EPA inhibited INa directly and also indirectly, by down-regulation of Nav mRNA expression in prostate cancer cells, thus inhibiting their metastatic potential
Deep Near Infrared Imaging toward Vela Molecular Ridge C - 1: A Remarkable Embedded Cluster in RCW 36 -
We present deep near-infrared (J, H, Ks) images toward an embedded cluster
which lies in a C18O clump in the cloud C of the Vela Molecular Ridge. This
cluster has at least ~ 350 members and a radius of ~ 0.5 pc. The stellar
surface number density is approximately 3000 stars pc^-2 in the central 0.1 pc
x 0.1 pc region of the cluster. This is much higher than most of the young
clusters within 1 kpc of the Sun. From the comparison of the luminosity
function and near-infrared excess fraction with those of other embedded
clusters, we estimate that the age of this cluster is approximately 2-3 Myr.
This cluster exhibits an excess of brighter stars in its central region, from
which we conclude that the more massive stars are located near the cluster
center.Comment: 23 pages, 8 figures. Color version of Figure 1 made available in gif
format. Accepted 24 June 2004 for publication in the Ap
Evolution of Elliptical Galaxies at z >~ 1 Revealed from a Large, Multicolor Sample of Extremely Red Objects
We study the evolution of elliptical galaxies at z >~ 1 on the basis of a
sample of 247 Extremely Red Objects (EROs) with R-Ks >= 3.35 (AB) and Ks <=
22.1 (AB) constructed from BVRi'z'JHKs multicolor data of a 114 arcmin2 area in
the Subaru/XMM Deep Survey Field. By fitting template spectra of old
ellipticals (OEs) and young, dusty starbursts (DSs) to the multicolor data, we
classify EROs into these two classes and estimate their redshifts. We find that
58% of the EROs in our sample belong to the OE class and that 24% of the OEs
are fit by a spectrum having a disk component with the B-band bulge-to-total
luminosity ratio of <= 0.9. We compare the observed surface density of OEs with
predictions from passive evolution models. We then derive rest-frame B-band
luminosity functions (LFs) of OEs in our sample at z=1-1.5 and 1.5-2.5. We find
that the LF at z=1-1.5 roughly agrees with the LF of local ellipticals if a
dimming of 1.3 mag from z=1.25 to the present epoch is assumed. On the other
hand, the amplitude of the LF at z=1.5-2.5 is found to be lower than that of
the local LF by a factor of ~ 3 over the whole range of magnitude observed.
Taking account of a strong decrease in the number density of morphologically
classified early-type galaxies at z >~ 1.5 found by several authors, we
conclude that the majority of ellipticals seen at present have not established
either a red color or a smooth 1/4-law profile before z ~ 1.5$. (abridged)Comment: 46 pages, 15 PostScript figures. Submitted to Ap
Synthesis, Characterization and Magnetic Susceptibility of the Heavy Fermion Transition Metal Oxide LiV_{2}O_{4}
The preparative method, characterization and magnetic susceptibility \chi
measurements versus temperature T of the heavy fermion transition metal oxide
LiV_{2}O_{4} are reported in detail. The intrinsic \chi(T) shows a nearly
T-independent behavior below ~ 30 K with a shallow broad maximum at about 16 K,
whereas Curie-Weiss-like behavior is observed above 50-100 K. Field-cooled and
zero-field-cooled magnetization M measurements in applied magnetic fields H =
10 to 100 G from 1.8 to 50 K showed no evidence for spin-glass ordering.
Crystalline electric field theory for an assumed cubic V point group symmetry
is found insufficient to describe the observed temperature variation of the
effective magnetic moment. The Kondo and Coqblin-Schrieffer models do not
describe the magnitude and T dependence of \chi with realistic parameters. In
the high T range, fits of \chi(T) by the predictions of high temperature series
expansion calculations provide estimates of the V-V antiferromagnetic exchange
coupling constant J/k_{B} ~ 20 K, g-factor g ~ 2 and the T-independent
susceptibility. Other possible models to describe the \chi(T) are discussed.
The paramagnetic impurities in the samples were characterized using isothermal
M(H) measurements with 0 < H <= 5.5 Tesla at 2 to 6 K. These impurities are
inferred to have spin S_{imp} ~ 3/2 to 4, g_{imp} ~ 2 and molar concentrations
of 0.01 to 0.8 %, depending on the sample.Comment: 19 typeset RevTeX pages, 16 eps figures included, uses epsf; to be
published in Phys. Rev.
Small satellites with MEMS x-ray telescopes for x-ray astronomy and solar system exploration
Toward a new era of X-ray astronomy, next generation X-ray optics are indispensable. To meet a demand for telescopes lighter than the foil optics but with a better angular resolution less than 1 arcmin, we are developing micropore X-ray optics based on micromaching technologies. Using sidewalls of micropores through a thin silicon wafer, this type can be the lightest X-ray telescope ever achieved. Two new Japanese missions ORBIS and GEOX will carry this optics. ORBIS is a small X-ray astronomy mission to monitor supermassive blackholes, while GEO-X is a small exploration mission of the Earth's magnetosphere. Both missions need a ultra light-weight (<1 kg) telescope with moderately good angular resolution (<10 arcmin) at an extremely short focal length (<30 cm). We plan to demonstrate this optics in these two missions around 2020, aiming at future other astronomy and exploration missions
Deficient activation of CD95 (APO-1/ Fas)-mediated apoptosis: a potential factor of multidrug resistance in human renal cell carcinoma
The pronounced resistance of human renal cell carcinoma (RCC) to anticancer-induced apoptosis has primarily been related to the expression of P-glycoprotein and effective drug detoxification mechanisms. Because the CD95 system has recently been identified as a key mediator of anticancer drug-induced apoptosis, we analysed the contribution of the CD95 system to chemotherapy-induced apoptosis in four newly established RCC cell lines. Here, we demonstrate that all RCC cell lines expressed CD95-receptor and -ligand. Exposure to agonistic anti-CD95 antibodies resulted in induction of apoptosis and significant (P< 0.05) reduction of cell number in three out of four cell lines, indicating that the essential components for CD95-mediated apoptosis were present and functionally intact in the majority of these RCC cell lines. Moreover, treatment of cultures with bleomycin or topotecan, a novel topoisomerase I inhibitor with little substrate affinity for P-glycoprotein, led to induction of apoptosis and significant (P< 0.05) dose-dependent reduction of cell number in all RCC cell lines. Both anticancer drugs also induced upregulation of CD95 ligand expression in all cell lines. Additionally, augmentation of CD95 receptor expression was found in three RCC cell lines, including one p53-mutated cell line, whereas another p53-mutated cell line showed no or only a weak CD95 receptor upregulation after exposure to topotecan or bleomycin, respectively. Despite this upregulation of CD95 receptor and ligand, antagonistic antibodies directed against CD95 receptors or ligands could not inhibit induction of apoptosis by topotecan and bleomycin in any cell line. Thus, although a functionally intact CD95 signalling cascade is present in most RCC cell lines, the anticancer drugs topotecan and bleomycin that induce upregulation of CD95 receptor and ligand fail to effectively activate CD95-mediated apoptosis. This deficient activation of CD95-mediated apoptosis might be an important additional factor for the multidrug resistance phenotype of human RCCs. © 2000 Cancer Research Campaig
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