109 research outputs found
Construction of an All-in-one Double-conditional shRNA Expression Vector
Gene silencing by RNA interference (RNAi) is widely used for assessing gene function. An important advance in the RNAi field was the discovery that plasmid-based RNAi can substitute for synthetic small interfering RNA in vitro and in vivo. However, constitutive and ubiquitous knockdown of gene expression by RNAi in mice can limit the scope of experiments because this process can lead to embryonic lethality, or result in compensatory overexpression of other genes such that no phenotypic abnormalities occur. Either way, analyses of the physiological roles of the gene of interest in adult mice are not possible. To overcome these limitations, we previously constructed a double-conditional short-hairpin RNA (shRNA) expression vector that can regulate shRNA expression in a spatio-temporal manner with a tetracycline-inducible floxed stuffer sequence selectively excised by application of Cre recombinase. In this study, we aimed to modify this vector to create an all-in-one vector that produces double-conditional transgenic mice through a single round of gene transfer to fertilized eggs. We added a coding region for nuclear localizing Cre (NCre) recombinase with a multi-cloning site for a cell-specific promoter into the double-conditional short-hairpin RNA (shRNA) expression vector that we previously constructed. Using Escherichia coli, we confirmed successful construction of the vector. First, we confirmed isopropyl-β-D-thiogalactopyranoside-induced expression of NCre recombinase through the lac operon as a specific promoter by western blotting. Second, we confirmed functional recombination of the floxed sequence of loxP-like TATA-lox by analysing restriction enzyme-digested fragments. This all-in-one double-conditional shRNA expression vector will be useful for reversible in vitro and in vivo knockdown of target gene expression, in target cells via promoter-specific expression of NCre, and at specific times by tetracycline application
Angular correlation of the two gamma rays produced in the thermal neutron capture on gadolinium-155 and gadolinium-157
The ANNRI-Gd collaboration studied in detail the single -ray spectrum
produced from the thermal neutron capture on Gd and Gd in our
previous publications. Gadolinium targets were exposed to a neutron beam
provided by the Japan Spallation Neutron Source (JSNS) in J-PARC, Japan. In the
present analysis, one new additional coaxial germanium crystal was used in the
analysis in combination with the fourteen germanium crystals in the cluster
detectors to study the angular correlation of the two rays emitted in
the same neutron capture. We present for the first time angular correlation
functions for two rays produced during the electromagnetic cascade
transitions in the (n, ) reactions on Gd and Gd. As expected, we observe the mild angular correlations for the strong,
but rare transitions from the resonance state to the two energy levels of known
spin-parities. Contrariwise, we observe negligibly small angular correlations
for arbitrary pairs of two rays produced in the majority of cascade
transitions from the resonance state to the dense continuum states.Comment: 21 pages, 13 figure
Gamma Ray Spectra from Thermal Neutron Capture on Gadolinium-155 and Natural Gadolinium
Abstract
Natural gadolinium is widely used for its excellent thermal neutron capture cross section, because of its two major isotopes: Gd and Gd. We measured the -ray spectra produced from the thermal neutron capture on targets comprising a natural gadolinium film and enriched Gd (in GdO powder) in the energy range from 0.11 MeV to 8.0 MeV, using the ANNRI germanium spectrometer at MLF, J-PARC. The freshly analyzed data of the Gd() reaction are used to improve our previously developed model (ANNRI-Gd model) for the Gd() reaction [K. Hagiwara et al. [ANNRI-Gd Collaboration], Prog. Theor. Exp. Phys. 2019, 023D01 (2019)], and its performance confirmed with the independent data from the Gd() reaction. This article completes the development of an efficient Monte Carlo model required to simulate and analyze particle interactions involving the thermal neutron captures on gadolinium in any relevant future experiments
Prime Focus Spectrograph - Subaru's future -
The Prime Focus Spectrograph (PFS) of the Subaru Measurement of Images and
Redshifts (SuMIRe) project has been endorsed by Japanese community as one of
the main future instruments of the Subaru 8.2-meter telescope at Mauna Kea,
Hawaii. This optical/near-infrared multi-fiber spectrograph targets cosmology
with galaxy surveys, Galactic archaeology, and studies of galaxy/AGN evolution.
Taking advantage of Subaru's wide field of view, which is further extended with
the recently completed Wide Field Corrector, PFS will enable us to carry out
multi-fiber spectroscopy of 2400 targets within 1.3 degree diameter. A
microlens is attached at each fiber entrance for F-ratio transformation into a
larger one so that difficulties of spectrograph design are eased. Fibers are
accurately placed onto target positions by positioners, each of which consists
of two stages of piezo-electric rotary motors, through iterations by using
back-illuminated fiber position measurements with a wide-field metrology
camera. Fibers then carry light to a set of four identical fast-Schmidt
spectrographs with three color arms each: the wavelength ranges from 0.38
{\mu}m to 1.3 {\mu}m will be simultaneously observed with an average resolving
power of 3000. Before and during the era of extremely large telescopes, PFS
will provide the unique capability of obtaining spectra of 2400
cosmological/astrophysical targets simultaneously with an 8-10 meter class
telescope. The PFS collaboration, led by IPMU, consists of USP/LNA in Brazil,
Caltech/JPL, Princeton, & JHU in USA, LAM in France, ASIAA in Taiwan, and
NAOJ/Subaru.Comment: 13 pages, 11 figures, submitted to "Ground-based and Airborne
Instrumentation for Astronomy IV, Ian S. McLean, Suzanne K. Ramsay, Hideki
Takami, Editors, Proc. SPIE 8446 (2012)
Prime Focus Spectrograph (PFS) for the Subaru Telescope: Overview, recent progress, and future perspectives
PFS (Prime Focus Spectrograph), a next generation facility instrument on the
8.2-meter Subaru Telescope, is a very wide-field, massively multiplexed,
optical and near-infrared spectrograph. Exploiting the Subaru prime focus, 2394
reconfigurable fibers will be distributed over the 1.3 deg field of view. The
spectrograph has been designed with 3 arms of blue, red, and near-infrared
cameras to simultaneously observe spectra from 380nm to 1260nm in one exposure
at a resolution of ~1.6-2.7A. An international collaboration is developing this
instrument under the initiative of Kavli IPMU. The project is now going into
the construction phase aiming at undertaking system integration in 2017-2018
and subsequently carrying out engineering operations in 2018-2019. This article
gives an overview of the instrument, current project status and future paths
forward.Comment: 17 pages, 10 figures. Proceeding of SPIE Astronomical Telescopes and
Instrumentation 201
The ASTRO-H X-ray Observatory
The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly
successful X-ray missions initiated by the Institute of Space and Astronautical
Science (ISAS). ASTRO-H will investigate the physics of the high-energy
universe via a suite of four instruments, covering a very wide energy range,
from 0.3 keV to 600 keV. These instruments include a high-resolution,
high-throughput spectrometer sensitive over 0.3-2 keV with high spectral
resolution of Delta E < 7 eV, enabled by a micro-calorimeter array located in
the focal plane of thin-foil X-ray optics; hard X-ray imaging spectrometers
covering 5-80 keV, located in the focal plane of multilayer-coated, focusing
hard X-ray mirrors; a wide-field imaging spectrometer sensitive over 0.4-12
keV, with an X-ray CCD camera in the focal plane of a soft X-ray telescope; and
a non-focusing Compton-camera type soft gamma-ray detector, sensitive in the
40-600 keV band. The simultaneous broad bandpass, coupled with high spectral
resolution, will enable the pursuit of a wide variety of important science
themes.Comment: 22 pages, 17 figures, Proceedings of the SPIE Astronomical
Instrumentation "Space Telescopes and Instrumentation 2012: Ultraviolet to
Gamma Ray
Progress with the Prime Focus Spectrograph for the Subaru Telescope: a massively multiplexed optical and near-infrared fiber spectrograph
The Prime Focus Spectrograph (PFS) is an optical/near-infrared multi-fiber
spectrograph with 2394 science fibers, which are distributed in 1.3 degree
diameter field of view at Subaru 8.2-meter telescope. The simultaneous wide
wavelength coverage from 0.38 um to 1.26 um, with the resolving power of 3000,
strengthens its ability to target three main survey programs: cosmology,
Galactic archaeology, and galaxy/AGN evolution. A medium resolution mode with
resolving power of 5000 for 0.71 um to 0.89 um also will be available by simply
exchanging dispersers. PFS takes the role for the spectroscopic part of the
Subaru Measurement of Images and Redshifts project, while Hyper Suprime-Cam
works on the imaging part. To transform the telescope plus WFC focal ratio, a
3-mm thick broad-band coated glass-molded microlens is glued to each fiber tip.
A higher transmission fiber is selected for the longest part of cable system,
while one with a better FRD performance is selected for the fiber-positioner
and fiber-slit components, given the more frequent fiber movements and tightly
curved structure. Each Fiber positioner consists of two stages of
piezo-electric rotary motors. Its engineering model has been produced and
tested. Fiber positioning will be performed iteratively by taking an image of
artificially back-illuminated fibers with the Metrology camera located in the
Cassegrain container. The camera is carefully designed so that fiber position
measurements are unaffected by small amounts of high special-frequency
inaccuracies in WFC lens surface shapes. Target light carried through the fiber
system reaches one of four identical fast-Schmidt spectrograph modules, each
with three arms. Prototype VPH gratings have been optically tested. CCD
production is complete, with standard fully-depleted CCDs for red arms and
more-challenging thinner fully-depleted CCDs with blue-optimized coating for
blue arms.Comment: 14 pages, 12 figures, submitted to "Ground-based and Airborne
Instrumentation for Astronomy V, Suzanne K. Ramsay, Ian S. McLean, Hideki
Takami, Editors, Proc. SPIE 9147 (2014)
First Results of the Ce(n,γ)Ce Cross-Section Measurement at n_TOF
An accurate measurement of the Ce(n,γ) energy-dependent cross-section was performed at the n_TOF facility at CERN. This cross-section is of great importance because it represents a bottleneck for the s-process nucleosynthesis and determines to a large extent the cerium abundance in stars. The measurement was motivated by the significant difference between the cerium abundance measured in globular clusters and the value predicted by theoretical stellar models. This discrepancy can be ascribed to an overestimation of the Ce capture cross-section due to a lack of accurate nuclear data. For this measurement, we used a sample of cerium oxide enriched in Ce to 99.4%. The experimental apparatus consisted of four deuterated benzene liquid scintillator detectors, which allowed us to overcome the difficulties present in the previous measurements, thanks to their very low neutron sensitivity. The accurate analysis of the p-wave resonances and the calculation of their average parameters are fundamental to improve the evaluation of the Ce Maxwellian-averaged cross-section
First Results of the Ce(n,γ)Ce Cross-Section Measurement at n_TOF
An accurate measurement of the Ce(n,γ) energy-dependent cross-section was performed at the n_TOF facility at CERN. This cross-section is of great importance because it represents a bottleneck for the s-process nucleosynthesis and determines to a large extent the cerium abundance in stars. The measurement was motivated by the significant difference between the cerium abundance measured in globular clusters and the value predicted by theoretical stellar models. This discrepancy can be ascribed to an overestimation of the Ce capture cross-section due to a lack of accurate nuclear data. For this measurement, we used a sample of cerium oxide enriched in Ce to 99.4%. The experimental apparatus consisted of four deuterated benzene liquid scintillator detectors, which allowed us to overcome the difficulties present in the previous measurements, thanks to their very low neutron sensitivity. The accurate analysis of the p-wave resonances and the calculation of their average parameters are fundamental to improve the evaluation of the Ce Maxwellian-averaged cross-section
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