83 research outputs found
AKARI Far-Infrared Source Counts in the Lockman Hole
We report initial results of far-infrared observations of the Lockman hole
with Far-Infrared Surveyor (FIS) onboard the AKARI infrared satellite. On the
basis of slow scan observations of a 0.6 deg x 1.2 deg contiguous area, we
obtained source number counts at 65, 90 and 140 um down to 77, 26 and 194 mJy
(3 sigma), respectively. The counts at 65 and 140 um show good agreement with
the Spitzer results. However, our 90 um counts are clearly lower than the
predicted counts by recent evolutionary models that fit the Spitzer counts in
all the MIPS bands. Our 90 um counts above 26 mJy account for about 7% of the
cosmic background. These results provide strong constraints on the evolutionary
scenario and suggest that the current models may require modifications.Comment: 25 pages, 8 figures, Publications of the Astronomical Society of
Japan, in pres
Galaxy Colours in the AKARI Deep SEP Survey
We investigate the segregation of the extragalactic population via colour
criteria to produce an efficient and inexpensive methodology to select specific
source populations as a function of far-infrared flux. Combining galaxy
evolution scenarios and a detailed spectral library of galaxies, we produce
simulated catalogues incorporating segregation of the extragalactic population
into component types (Normal, star-forming, AGN) via color cuts. As a practical
application we apply our criteria to the deepest survey to be undertaken in the
far-infrared with the AKARI (formerly ASTRO-F) satellite. Using the
far-infrared wavebands of the Far-Infrared Surveyor (FIS, one of the
focal-plane instruments on AKARI) we successfully segregate the normal,
starburst and ULIRG populations. We also show that with additional MIR imaging
from AKARI's Infrared Camera (IRC), significant contamination and/or degeneracy
can be further decreased and show a particular example of the separation of
cool normal galaxies and cold ULIRG sources. We conclude that our criteria
provide an efficient means of selecting source populations (including rare
luminous objects) and produce colour-segregated source counts without the
requirement of time intensive ground-based follow up to differentiate between
the general galaxy population.Comment: Accepted for publication in Advances in Space Research. COSPAR,
Beijing, 2006, E1.6 Advances in FIR and Submillimeter Astrophysics. (13
pages, 2 colour figures
Intracellular localization of tyrosine kinase substrates beneath crosslinked surface immunoglobulins in B cells
Crosslinking of surface immunoglobulins (sIg) in B cells led to the accumulation of submembranal phosphotyrosine, which was followed morphologically with the PY20 antiphosphotyrosine monoclonal antibody. Phosphotyrosine was not detected before sIg crosslinking. After sIg crosslinking, phosphotyrosine-containing proteins were redistributed from scattered small clusters near the plasma membrane to a juxtanuclear region, where immunofluorescent staining decreased with time. Double immunofluorescent staining of individual cells showed accumulation of phosphotyrosine beneath crosslinked sIg molecules at the cell surface. The sIg molecules were subsequently internalized more rapidly than the phosphotyrosine-containing molecules were redistributed. Genistein, a protein tyrosine kinase (PTK) inhibitor, blocked intracellular tyrosine phosphorylations but not cell surface patching of crosslinked sIg. When polyacrylamide beads coated with anti-Ig antibodies were added to the cells, intracellular tyrosine phosphorylation occurred beneath the regions of contact with the beads. This study provides an independent line of evidence confirming recent biochemical experiments that show that crosslinking of the antigen receptor induces PTK activity in B cells, and that components of the newly described sIg complex are among the PTK substrates. The surprising finding that the bulk of the induced phosphotyrosine remains associated with crosslinked sIg for many minutes suggests a role for complex local protein interactions in phosphotyrosine-mediated signal transduction through the antigen receptor of B cells
Molecular targeting of hepatocyte growth factor by an antagonist, NK4, in the treatment of rheumatoid arthritis
INTRODUCTION: Hepatocyte growth factor (HGF) is a potent proangiogenic molecule that induces neovascularization. The HGF antagonist, NK4, competitively antagonizes HGF binding to its receptor. In the present study, we determined the inhibitory effect of NK4 in a rheumatoid arthritis (RA) model using SKG mice. METHODS: Arthritis was induced in SKG mice by a single intraperitoneal injection of β-glucan. Recombinant adenovirus containing NK4 cDNA (AdCMV.NK4) was also injected intravenously at the time of or 1 month after β-glucan injection. Ankle bone destruction was examined radiographically. The histopathologic features of joints were examined using hematoxylin and eosin and immunohistochemical staining. Enzyme-linked immunosorbent assays were used to determine the serum levels of HGF, interferon γ (IFN-γ, interleukin 4 (IL-4) and IL-17 production by CD4(+ )T cells stimulated with allogeneic spleen cells. RESULTS: The intravenous injection of AdCMV.NK4 into SKG mice suppressed the progression of β-glucan-induced arthritis. Bone destruction was also inhibited by NK4 treatment. The histopathologic findings of the ankles revealed that angiogenesis, inflammatory cytokines and RANKL expression in synovial tissues were significantly inhibited by NK4 treatment. Recombinant NK4 (rNK4) proteins inhibited IFN-γ, IL-4 and IL-17 production by CD4(+ )T cells stimulated with allogeneic spleen cells. CONCLUSIONS: These results indicate that NK4 inhibits arthritis by inhibition of angiogenesis and inflammatory cytokine production by CD4(+ )T cells. Therefore, molecular targeting of angiogenic inducers by NK4 can potentially be used as a novel therapeutic approach for the treatment of RA
Far infrared luminosity function of local galaxies in the AKARI Deep Field South
We present the first far-infrared luminosity function in the AKARI Deep Field South, a premier deep field of the AKARI Space Telescope, using spectroscopic redshifts obtained with AAOmega. To date, we have found spectroscopic redshifts for 389 galaxies in this field and have measured the local (z<0.25) 90 μm luminosity function using about one-third of these redshifts. The results are in reasonable agreement with recent theoretical predictions
Effects of Titanium Dioxide Nanoparticle Aggregate Size on Gene Expression
Titanium dioxide (titania) nanoparticle aggregation is an important factor in understanding cytotoxicity. However, the effect of the aggregate size of nanoparticles on cells is unclear. We prepared two sizes of titania aggregate particles and investigated their biological activity by analyzing biomarker expression based on mRNA expression analysis. The aggregate particle sizes of small and large aggregated titania were 166 nm (PDI = 0.291) and 596 nm (PDI = 0.417), respectively. These two size groups were separated by centrifugation from the same initial nanoparticle sample. We analyzed the gene expression of biomarkers focused on stress, inflammation, and cytotoxicity. Large titania aggregates show a larger effect on cell viability and gene expression when compared with the small aggregates. This suggests that particle aggregate size is related to cellular effects
Torus Constraints in ANEPD-CXO245: A Compton-thick AGN with Double-peaked Narrow Lines
We report on the torus constraints of the Compton-thick active galactic nucleus (AGN) with double-peaked optical narrow-line region emission lines, ANEPD-CXO245, at z = 0.449 in the AKARI NEP Deep Field. The unique infrared data on this field, including those from the nine-band photometry over 2–24 μm with the AKARI Infrared Camera, and the X-ray spectrum from Chandra allow us to constrain torus parameters such as the torus optical depth, X-ray absorbing column, torus angular width (σ), and viewing angle (i). We analyze the X-ray spectrum as well as the UV–optical–infrared spectral energy distribution (UOI-SED) with clumpy torus models in X-ray (XCLUMPY) and infrared (CLUMPY), respectively. From our current data, the constraints on σ–i from both X-rays and UOI show that the line of sight crosses the torus as expected for a type 2 AGN. We obtain a small X-ray scattering fraction (NH from the X-ray spectrum, we find that the gas-to-dust ratio is <4 times larger than the Galactic value
A deep ATCA 20cm radio survey of the AKARI Deep Field South near the South Ecliptic Pole
The results of a deep 20 cm radio survey at 20 cm are reported of the AKARI
Deep Field South (ADF-S) near the South Ecliptic Pole (SEP), using the
Australia Telescope Compact Array telescope, ATCA. The survey has 1 sigma
detection limits ranging from 18.7--50 microJy per beam over an area of ~1.1 sq
degrees, and ~2.5 sq degrees to lower sensitivity. The observations, data
reduction and source count analysis are presented, along with a description of
the overall scientific objectives, and a catalogue containing 530 radio sources
detected with a resolution of 6.2" x 4.9". The derived differential source
counts show a pronounced excess of sources fainter than ~1 mJy, consistent with
an emerging population of star forming galaxies. Cross-correlating the radio
with AKARI sources and archival data we find 95 cross matches, with most
galaxies having optical R-magnitudes in the range 18-24 mag, and 52 components
lying within 1" of a radio position in at least one further catalogue (either
IR or optical). We have reported redshifts for a sub-sample of our catalogue
finding that they vary between galaxies in the local universe to those having
redshifts of up to 0.825. Associating the radio sources with the Spitzer
catalogue at 24 microns, we find 173 matches within one Spitzer pixel, of which
a small sample of the identifications are clearly radio loud compared to the
bulk of the galaxies. The radio luminosity plot and a colour-colour analysis
suggest that the majority of the radio sources are in fact luminous star
forming galaxies, rather than radio-loud AGN. There are additionally five cross
matches between ASTE or BLAST submillimetre galaxies and radio sources from
this survey, two of which are also detected at 90 microns, and 41 cross-matches
with submillimetre sources detected in the Herschel HerMES survey Public Data
release.Comment: MNRAS accepted and in press 9 July 2012: 28 pages, 15 Figures, 17
Table
The Far-Infrared Surveyor (FIS) for AKARI
The Far-Infrared Surveyor (FIS) is one of two focal plane instruments on the
AKARI satellite. FIS has four photometric bands at 65, 90, 140, and 160 um, and
uses two kinds of array detectors. The FIS arrays and optics are designed to
sweep the sky with high spatial resolution and redundancy. The actual scan
width is more than eight arcmin, and the pixel pitch is matches the diffraction
limit of the telescope. Derived point spread functions (PSFs) from observations
of asteroids are similar to the optical model. Significant excesses, however,
are clearly seen around tails of the PSFs, whose contributions are about 30% of
the total power. All FIS functions are operating well in orbit, and its
performance meets the laboratory characterizations, except for the two longer
wavelength bands, which are not performing as well as characterized.
Furthermore, the FIS has a spectroscopic capability using a Fourier transform
spectrometer (FTS). Because the FTS takes advantage of the optics and detectors
of the photometer, it can simultaneously make a spectral map. This paper
summarizes the in-flight technical and operational performance of the FIS.Comment: 23 pages, 10 figures, and 2 tables. Accepted for publication in the
AKARI special issue of the Publications of the Astronomical Society of Japa
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