517 research outputs found
When to efficiently rebalance a portfolio
A constant weight asset allocation is a popular investment strategy and is
optimal under a suitable continuous model. We study the tracking error for the
target continuous rebalancing strategy by a feasible discrete-in-time
rebalancing under a general multi-dimensional Brownian semimartingale model of
asset prices. In a high-frequency asymptotic framework, we derive an
asymptotically efficient sequence of simple predictable strategies
Lyman Break Galaxies at z~5: Rest-frame UV Spectra II
We present the results of spectroscopy of Lyman Break Galaxies (LBGs) at z~5
in the J0053+1234 field with the Faint Object Camera and Spectrograph on the
Subaru telescope. Among 5 bright candidates with z' < 25.0 mag, 2 objects are
confirmed to be at z~5 from their Ly alpha emission and the continuum
depression shortward of Ly alpha. The EWs of Ly alpha emission of the 2 LBGs
are not so strong to be detected as Ly alpha emitters, and one of them shows
strong low-ionized interstellar (LIS) metal absorption lines. Two faint objects
with z' \geq 25.0 mag are also confirmed to be at z~5, and their spectra show
strong Ly alpha emission in contrast to the bright ones. These results suggest
a deficiency of strong Ly alpha emission in bright LBGs at z~5, which has been
discussed in our previous paper. Combined with our previous spectra of LBGs at
z~5 obtained around the Hubble Deep Field-North (HDF-N), we made a composite
spectrum of UV luminous (M_1400 \leq -21.5 mag) LBGs at z~5. The resultant
spectrum shows a weak Ly alpha emission and strong LIS absorptions which
suggests that the bright LBGs at z~5 have chemically evolved at least to ~0.1
solar metallicity. For a part of our sample in the HDF-N region, we obtained
near-to-mid infrared data, which constraint stellar masses of these objects.
With the stellar mass and the metallicity estimated from LIS absorptions, the
metallicities of the LBGs at z~5 tend to be lower than those of the galaxies
with the same stellar mass at z \lesssim 2, although the uncertainty is very
large.Comment: 17 pages, 5 figures, accepted for publication in PAS
Visual Feedback Without Geometric Features Against Occlusion: A Walsh Basis
Date of Online Publication: 09 January 2018For a visual feedback without geometric features, this brief suggests to apply a basis made by the Walsh functions in order to reduce the off-line experimental cost. Depending on the resolution, the feedback is implementable and achieves the closed-loop stability of dynamical systems as long as the input-output linearity on matrix space exists. Remarkably, a part of the whole occlusion effects is rejected, and the remaining part is attenuated. The validity is confirmed by the experimental feedback for nonplanar sloshing
Intramesocolic Diverticular Perforation of the Sigmoid Colon Diagnosed by Detecting Air Collection in Anterior Pararenal Space on Computed Tomography: Report of a Case
A 64-year-old woman was admitted to our hospital with lower abdominal pain. Routine laboratory values were unremarkable except for the white blood cell count (15,000/micro litter) and the C-reactive protein (CRP) value (22.5 mg/dl). A Computed tomography (CT) scan revealed air collection in the middle of the anterior pararenal space. One day later, CT revealed air collection in the anterior pararenal space spread to the right side and abscess in the sigmoid mesentery. Because an intramesocolic perforation of the sigmoid colon was suspected, an emergency operation was performed. Abscess formation was recognized in the sigmoid mesentery, and sigmoidectomy including the contaminated mesentery and Hartmann.s procedure were performed. The perforation was 3 cm in diameter, and some diverticula were present in the vicinity of the perforated site. The specimen microscopically revealed perforation at the edge of the diverticulum in association with sudden disruption of the proper muscle layer. Based on pathological findings, intramesocolic diverticular perforation of the sigmoid colon was diagnosed. The present case is a very rare condition. However, it was possible to make a diagnosis preoperatively by detecting air collection in the anterior pararenal space on CT scan. If a sigmoid perforation occurs between the leaves of the mesocolon, air extends into the root of the sigmoid mesocolon and within the anterior pararenal space
GALAXY CRUISE: Spiral and ring classifications for 700K bright galaxies at z=0.01-0.3
This paper presents a morphology classification catalog of spiral and ring
features of 687,859 magnitude-limited galaxies at =0.01-0.3 (r<20 mag) based
on the Third Public Data Release of the Hyper Suprime-Cam Subaru Strategic
Program. We employ two deep learning classifiers to determine the spiral and
ring structures separately based on GALAXY CRUISE Data Release 1, which is
dedicated to Hyper Suprime-Cam data. The number of spiral and ring galaxies
contain 385,449 and 33,993 sources, respectively, which constitute and
of the sample. A notable result of this study is the construction of a
large sample of ring galaxies utilizing high-quality imaging data delivered by
the Subaru Hyper Suprime-Cam. However, the accurate identification of ring
galaxies remains difficult at a limited seeing resolution. Additionally, we
confirm that most spiral galaxies are located on the star-forming main
sequence, whereas ring galaxies preferentially reside in the green valley at
stellar mass of 1E10.5-11 solar mass. Furthermore, decreasing fractions of
spiral and ring galaxies are observed toward the centers of the galaxy
clusters. The obtained morphology catalog is publicly available on the GALAXY
CRUISE website.Comment: 17 pages, 14 figures, 3 table
Discovery of H alpha absorption in the unusual broad absorption line quasar SDSS J083942.11+380526.3
We discovered an H alpha absorption in a broad H alpha emission line of an
unusual broad absorption line quasar, SDSS J083942.11+380526.3 at z=2.318, by
near-infrared spectroscopy with the Cooled Infrared Spectrograph and Camera for
OHS (CISCO) on the Subaru telescope. The Presence of non-stellar H alpha
absorption is known only in the Seyfert galaxy NGC 4151 to date, thus our
discovery is the first case for quasars. The H alpha absorption line is
blueshifted by 520 km/s relative to the H alpha emission line, and its redshift
almost coincides with those of UV low-ionization metal absorption lines. The
width of the H alpha absorption (~ 340 km/s) is similar to those of the UV
low-ionization absorption lines. These facts suggest that the H alpha and the
low-ionization metal absorption lines are produced by the same low-ionization
gas which has a substantial amount of neutral gas. The column density of the
neutral hydrogen is estimated to be ~ 10^18 cm^-2 by assuming a gas temperature
of 10,000 K from the analysis of the curve of growth. The continuum spectrum is
reproduced by a reddened (E(B-V) ~ 0.15 mag for the SMC-like reddening law)
composite quasar spectrum. Furthermore, the UV spectrum of SDSS
J083942.11+380526.3 shows a remarkable similarity to that of NGC 4151 in its
low state, suggesting the physical condition of the absorber in SDSS
J083942.11+380526.3 is similar to that of NGC 4151 in the low state. As
proposed for NGC 4151, SDSS J083942.11+380526.3 may be also seen through the
close direction of the surface of the obscuring torus.Comment: Accepted for publication in Ap
Lyman Break Galaxies at : Rest-Frame UV Spectra
We report initial results for spectroscopic observations of candidates of
Lyman Break Galaxies (LBGs) at in a region centered on the Hubble Deep
Field-North by using the Faint Object Camera and Spectrograph attached to the
Subaru Telescope. Eight objects with mag, including one AGN, are
confirmed to be at . The rest-frame UV spectra of seven LBGs
commonly show no or weak Lyalpha emission line (rest-frame equivalent width of
0-10\AA) and relatively strong low-ionization interstellar metal absorption
lines of SiII 1260, OI+SiII 1303, and CII 1334 (mean
rest-frame equivalent widths of them are \AA). These
properties are significantly different from those of the mean rest-frame UV
spectrum of LBGs at , but are quite similar to those of subgroups of
LBGs at with no or weak Lyalpha emission. The weakness of Lyalpha
emission and strong low-ionization interstellar metal absorption lines may
indicate that these LBGs at are chemically evolved to some degree and
have a dusty environment. Since the fraction of such LBGs at in our
sample is larger than that at , we may witness some sign of evolution
of LBGs from to , though the present sample size is very
small. It is also possible, however, that the brighter LBGs tend to show no or
weak Lyalpha emission, because our spectroscopic sample is bright (brighter
than ) among LBGs at . More observations are required to
establish spectroscopic nature of LBGs at .Comment: 16 pages, 3 figures, accepted by Ap
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