329 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
Optimal Sketching Bounds for Sparse Linear Regression
We study oblivious sketching for -sparse linear regression under various
loss functions such as an norm, or from a broad class of hinge-like
loss functions, which includes the logistic and ReLU losses. We show that for
sparse norm regression, there is a distribution over oblivious
sketches with rows, which is tight up to a
constant factor. This extends to loss with an additional additive
term in the upper bound. This
establishes a surprising separation from the related sparse recovery problem,
which is an important special case of sparse regression. For this problem,
under the norm, we observe an upper bound of rows, showing that sparse recovery is
strictly easier to sketch than sparse regression. For sparse regression under
hinge-like loss functions including sparse logistic and sparse ReLU regression,
we give the first known sketching bounds that achieve rows showing that
rows suffice, where
is a natural complexity parameter needed to obtain relative error bounds for
these loss functions. We again show that this dimension is tight, up to lower
order terms and the dependence on . Finally, we show that similar
sketching bounds can be achieved for LASSO regression, a popular convex
relaxation of sparse regression, where one aims to minimize
over . We show that sketching
dimension suffices and that the dependence
on and is tight.Comment: AISTATS 202
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 ÎŒm luminosity function using about one-third of these redshifts. The results are in reasonable agreement with recent theoretical predictions
Intestinal CCL25 expression is increased in colitis and correlates with inflammatory activity
AbstractCCL25-mediated activation of CCR9 is critical for mucosal lymphocyte recruitment to the intestine. In immune-mediated liver injury complicating inflammatory bowel disease, intrahepatic activation of this pathway allows mucosal lymphocytes to be recruited to the liver, driving hepatobiliary destruction in primary sclerosing cholangitis (PSC). However, in mice and healthy humans CCL25 expression is restricted to the small bowel, whereas few data exist on activation of this pathway in the inflamed colon despite the vast majority of PSC patients having ulcerative colitis. Herein, we show that colonic CCL25 expression is not only upregulated in patients with active colitis, but strongly correlates with endoscopic Mayo score and mucosal TNFα expression. Moreover, approximately 90% (CD4+) and 30% (CD8+) of tissue-infiltrating T-cells in colitis were identified as CCR9+ effector lymphocytes, compared to <10% of T-cells being CCR9+ in normal colon. Sorted CCR9+ lymphocytes also demonstrated enhanced cellular adhesion to stimulated hepatic sinusoidal endothelium compared with their CCR9â counterparts when under flow. Collectively, these results suggest that CCR9/CCL25 interactions are not only involved in colitis pathogenesis but also correlate with colonic inflammatory burden; further supporting the existence of overlapping mucosal lymphocyte recruitment pathways between the inflamed colon and liver
Timeline analysis and wavelet multiscale analysis of the AKARI All-Sky Survey at 90 micron
We present a careful analysis of the point source detection limit of the
AKARI All-Sky Survey in the WIDE-S 90 m band near the North Ecliptic Pole
(NEP). Timeline Analysis is used to detect IRAS sources and then a conversion
factor is derived to transform the peak timeline signal to the interpolated 90
m flux of a source. Combined with a robust noise measurement, the point
source flux detection limit at S/N for a single detector row is
Jy which corresponds to a point source detection limit of the
survey of 0.4 Jy.
Wavelet transform offers a multiscale representation of the Time Series Data
(TSD). We calculate the continuous wavelet transform of the TSD and then search
for significant wavelet coefficients considered as potential source detections.
To discriminate real sources from spurious or moving objects, only sources with
confirmation are selected. In our multiscale analysis, IRAS sources selected
above can be identified as the only real sources at the Point Source
Scales. We also investigate the correlation between the non-IRAS sources
detected in Timeline Analysis and cirrus emission using wavelet transform and
contour plots of wavelet power spectrum. It is shown that the non-IRAS sources
are most likely to be caused by excessive noise over a large range of spatial
scales rather than real extended structures such as cirrus clouds.Comment: 16 pages, 19 figures, 5 tables, accepted for publication in MNRA
AKARI Deep Field South: spectroscopic observations of infrared sources
We present a summary of our spectroscopic redshift catalogue of 404 sources in the AKARI Deep Field South (ADF-S). We have used the AAOmega spectrograph to target mid-infrared and far-infrared sources selected primarily from AKARI observations in this field for which we were able to obtain optical counterparts. Our sources with identified redshifts include 316 with Hα detections at z †0.345 and 15 sources at z > 1 with MgII or Lα emission lines. About 13% of our z †0.345 sources are dominated by active galactic nuclei (AGN) emission, although many show emission from both star formation and AGNs. The median Balmer decrement is 5.9. Ultra-luminous infrared galaxies (ULIRGs) were found only in the higher-redshift sources. Optical and near infrared data will be available shortly, enabling calibration of the line luminosities and spectral energy distribution (SED) fitting for these sources
Formability Characterization of a New Generation High Strength Steels
Advanced high strength steels (AHSS) are being progressively explored by the automotive industry all around the world for cost-effective solutions to accomplish vehicle lightweighting, improve fuel economy, and consequently reduce greenhouse emissions. Because of their inherent high strength, attractive crash energy management properties, and good formability, the effective use of AHSS such as Duel Phase and TRIP (Transformation Induced Plasticity) steels, will significantly contribute to vehicle lightweighting and fuel economy. To further the application of these steels in automotive body and structural parts, a good knowledge and experience base must be developed regarding the press formability of these materials. This project provides data on relevant intrinsic mechanical behavior, splitting limits, and springback behavior of several lots of mild steel, conventional high strength steel (HSS), advanced high strength steel (AHSS) and ultra-high strength steel (UHSS), supplied by the member companies of the Automotive Applications Committee (AAC) of the American Iron and Steel Institute (AISI). Two lots of TRIP600, which were supplied by ThyssenKrupp Stahl, were also included in the study. Since sheet metal forming encompasses a very diverse range of forming processes and deformation modes, a number of simulative tests were used to characterize the forming behavior of these steel grades. In general, it was found that formability, as determined by the different tests, decreased with increased tensile strength. Consistant with previous findings, the formability of TRIP600 was found to be exceptionally good for its tensile strength
Detection of CFIRB with AKARI/FIS Deep Observations
The Cosmic Far-Infrared Background (CFIRB) contains information about the
number and distribution of contributing sources and thus gives us an important
key to understand the evolution of galaxies. Using a confusion study to set a
fundamental limit to the observations, we investigate the potential to explore
the CFIRB with AKARI/FIS deep observations. The Far-Infrared Surveyor (FIS) is
one of the focal-plane instruments on the AKARI (formerly known as ASTRO-F)
satellite, which was launched in early 2006. Based upon source distribution
models assuming three different cosmological evolutionary scenarios (no
evolution, weak evolution, and strong evolution), an extensive model for
diffuse emission from infrared cirrus, and instrumental noise estimates, we
present a comprehensive analysis for the determination of the confusion levels
for deep far-infrared observations. We use our derived sensitivities to suggest
the best observational strategy for the AKARI/FIS mission to detect the CFIRB
fluctuations. If the source distribution follows the evolutionary models,
observations will be mostly limited by source confusion. We find that we will
be able to detect the CFIRB fluctuations and that these will in turn provide
information to discriminate between the evolutionary scenarios of galaxies in
most low-to-medium cirrus regions.Comment: 12 pages, 5 figures, uses elsart.cls, Accepted for publication in
Advances in Space Research, 36th COSPAR Scientific Assembly Beijing, China,
16 ~ 23 July 200
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