92 research outputs found
Global Spiral Modes in NGC 1566: Observations and Theory
We present an observational and theoretical study of the spiral structure in
galaxy NGC 1566. A digitized image of NGC 1566 in I-band was used for
measurements of the radial dependence of amplitude variations in the spiral
arms. We use the known velocity dispersion in the disk of NGC 1566, together
with its rotation curve, to construct linear and 2D nonlinear simulations which
are then compared with observations. A two-armed spiral is the most unstable
linear global mode in the disk of NGC 1566. The nonlinear simulations are in
agreement with the results of the linear modal analysis, and the theoretical
surface amplitude and the velocity residual variations across the spiral arms
are in qualitative agreement with the observations. The spiral arms found in
the linear and nonlinear simulations are considerably shorter than those
observed in the disk of NGC 1566. We argue therefore, that the surface density
distribution in the disk of the galaxy NGC 1566 was different in the past, when
spiral structure in NGC 1566 was linearly growing.Comment: 41 pages, 20 figures, to be published in the Astrophysical Journa
Cosmology from cosmic shear power spectra with Subaru Hyper Suprime-Cam first-year data
We measure cosmic weak lensing shear power spectra with the Subaru Hyper
Suprime-Cam (HSC) survey first-year shear catalog covering 137deg of the
sky. Thanks to the high effective galaxy number density of 17
arcmin even after conservative cuts such as magnitude cut of
and photometric redshift cut of , we obtain a high
significance measurement of the cosmic shear power spectra in 4 tomographic
redshift bins, achieving a total signal-to-noise ratio of 16 in the multipole
range . We carefully account for various uncertainties
in our analysis including the intrinsic alignment of galaxies, scatters and
biases in photometric redshifts, residual uncertainties in the shear
measurement, and modeling of the matter power spectrum. The accuracy of our
power spectrum measurement method as well as our analytic model of the
covariance matrix are tested against realistic mock shear catalogs. For a flat
cold dark matter (CDM) model, we find for
( for ) from our HSC tomographic
cosmic shear analysis alone. In comparison with Planck cosmic microwave
background constraints, our results prefer slightly lower values of ,
although metrics such as the Bayesian evidence ratio test do not show
significant evidence for discordance between these results. We study the effect
of possible additional systematic errors that are unaccounted in our fiducial
cosmic shear analysis, and find that they can shift the best-fit values of
by up to in both directions. The full HSC survey data
will contain several times more area, and will lead to significantly improved
cosmological constraints.Comment: 43 pages, 21 figures, accepted for publication in PAS
Effect of sand on landing knee valgus during single leg land and drop jump tasks: Possible implications for ACL injury prevention and rehabilitation.
Context: Despite significant emphasis on Anterior Cruciate Ligament (ACL) injury prevention, injury rates continue to rise and re-injury is common. Interventions to reduce injury have included resistance, balance and jump training elements. The use of sand-based jump training has been postulated as an effective treatment. However, evidence on landing mechanics is limited.
Objective: To determine potential differences in landing strategies and subsequent landing knee valgus when performing single leg landing (SLL) and drop jump (DJ) tasks onto sand and land, and compare between both male and female populations.
Design: A randomised repeated measures crossover design.
Setting: University Laboratory.
Participants: 31 participants (20 males, 11 females) from a university population.
Interventions: All participants completed DJ and SLL tasks on both sand and land surfaces.
Main Outcome Measures: 2-dimensional Frontal Plane Projection Angle (FPPA) of knee valgus was measured in both the DJ and SLL tasks (right and left) for both sand and land conditions.
Results: FPPA was lower (moderate to large effect) for SLL in sand compared to land in both legs (Left: 4.3⁰ ±2.8⁰; Right: 4.1⁰ ±3.8⁰) for females. However, effects were unclear (Left: -0.7⁰ ±2.2⁰) and trivial for males (Right: -1.1⁰ ±1.9⁰). FPPA differences for males and females performing DJ were unclear, thus more data is required. Differences in FPPA (land vs sand) with respect to grouping (sex) for both SLL (Left: 4.9⁰ ±3.0⁰) and (Right: 5.1⁰ ±4.0⁰) were both very likely higher small/ possibly moderate for females compared to males
HELIUM PHOTODISINTEGRATION AND NUCLEOSYNTHESIS: IMPLICATIONS FOR TOPOLOGICAL DEFECTS, HIGH ENERGY COSMIC RAYS, AND MASSIVE BLACK HOLES
We consider the production of He and H by He photodisintegration
initiated by non-thermal energy releases during early cosmic epochs. We find
that this process cannot be the predominant source of primordial H since it
would result in anomalously high He/D ratios in conflict with standard
chemical evolution assumptions. We apply this fact to constrain topological
defect models of highest energy cosmic ray (HECR) production. Such models have
been proposed as possible sources of ultrahigh energy particles and gamma-rays
with energies above eV. The constraints on these models derived from
He-photodisintegration are compared to corresponding limits from spectral
distortions of the cosmic microwave background radiation (CMBR) and from the
observed diffuse gamma-ray background. It is shown that for reasonable primary
particle injection spectra superconducting cosmic strings, unlike ordinary
strings or annihilating monopoles, cannot produce the HECR flux at the present
epoch without violating at least the He-photodisintegration bound. The
constraint from the diffuse gamma-ray background rules out the dominant
production of HECR by the decay of Grand Unification particles in models with
cosmological evolution assuming standard fragmentation functions. Constraints
on massive black hole induced photodisintegration are also discussed.Comment: 20 latex pages, 1 figure added via figures comman
First Data Release of the Hyper Suprime-Cam Subaru Strategic Program
The Hyper Suprime-Cam Subaru Strategic Program (HSC-SSP) is a three-layered
imaging survey aimed at addressing some of the most outstanding questions in
astronomy today, including the nature of dark matter and dark energy. The
survey has been awarded 300 nights of observing time at the Subaru Telescope
and it started in March 2014. This paper presents the first public data release
of HSC-SSP. This release includes data taken in the first 1.7 years of
observations (61.5 nights) and each of the Wide, Deep, and UltraDeep layers
covers about 108, 26, and 4 square degrees down to depths of i~26.4, ~26.5, and
~27.0 mag, respectively (5sigma for point sources). All the layers are observed
in five broad bands (grizy), and the Deep and UltraDeep layers are observed in
narrow bands as well. We achieve an impressive image quality of 0.6 arcsec in
the i-band in the Wide layer. We show that we achieve 1-2 per cent PSF
photometry (rms) both internally and externally (against Pan-STARRS1), and ~10
mas and 40 mas internal and external astrometric accuracy, respectively. Both
the calibrated images and catalogs are made available to the community through
dedicated user interfaces and database servers. In addition to the pipeline
products, we also provide value-added products such as photometric redshifts
and a collection of public spectroscopic redshifts. Detailed descriptions of
all the data can be found online. The data release website is
https://hsc-release.mtk.nao.ac.jp/.Comment: 34 pages, 20 figures, 7 tables, moderate revision, accepted for
publication in PAS
Transcriptome analysis of Hpa1Xoo transformed cotton revealed constitutive expression of genes in multiple signalling pathways related to disease resistance
The transcriptome profile in leaves and roots of the transgenic cotton line T-34 expressing hpa1Xoo from Xanthomonas oryzae pv. oryzae was analysed using a customized 12k cotton cDNA microarray. A total of 530 cDNA transcripts involved in 34 pathways were differentially expressed in the transgenic line T-34, in which 123 differentially expressed genes were related to the cotton defence responses including the hypersensitive reaction, defence responses associated with the recognition of pathogen-derived elicitors, and defence signalling pathways mediated by salicylic acid, jasmonic acid, ethylene, auxin, abscicic acid, and Ca2+. Furthermore, transcripts encoding various leucine-rich protein kinases and mitogen-activated protein kinases were up-regulated in the transgenic line T-34 and expression of transcripts related to the energy producing and consuming pathway was also increased, which suggested that the enhanced metabolism related to the host defence response in the transgenic line T-34 imposed an increased energy demand on the transgenic plant
A Mechanism for the Inhibition of Neural Progenitor Cell Proliferation by Cocaine
Investigating the mechanism of cocaine's effect on fetal brain development, Chun-Ting Lee and colleagues find that down-regulation of cyclin A by a cocaine metabolite inhibits neural proliferation
The Hyper Suprime-Cam SSP survey: Overview and survey design
Hyper Suprime-Cam (HSC) is a wide-field imaging camera on the prime focus of the 8.2-m Subaru telescope on the summit of Mauna Kea in Hawaii. A team of scientists from Japan, Taiwan, and Princeton University is using HSC to carry out a 300-night multi-band imaging survey of the high-latitude sky. The survey includes three layers: the Wide layer will cover 1400 deg2 in five broad bands (grizy), with a 5 σ point-source depth of r ≈ 26. The Deep layer covers a total of 26 deg2 in four fields, going roughly a magnitude fainter, while the UltraDeep layer goes almost a magnitude fainter still in two pointings of HSC (a total of 3.5 deg2). Here we describe the instrument, the science goals of the survey, and the survey strategy and data processing. This paper serves as an introduction to a special issue of the Publications of the Astronomical Society of Japan, which includes a large number of technical and scientific papers describing results from the early phases of this survey
Hepatoid adenocarcinoma of the lung mimicking metastatic hepatocellular carcinoma
Hepatoid adenocarcinoma of the lung is a rare subtype of lung cancer. We report a case of a metastatic hepatoid adenocarcinoma of the lung with aggressive behavior, including biopsy and autopsy findings. The pulmonary tumors showed features indistinguishable from hepatocellular carcinoma and were diffusely positive for Hepatocyte Paraffin 1
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