955 research outputs found
Relativistic two-pion exchange nucleon-nucleon potential: configuration space
We have recently performed a relativistic chiral expansion of the
two-pion exchange potential, and here we explore its configuration space
content. Interactions are determined by three families of diagrams, two of
which involve just and , whereas the third one depends on
empirical coefficients fixed by subthreshold data. In this sense, the
calculation has no adjusted parameters and gives rise to predictions, which are
tested against phenomenological potentials. The dynamical structure of the
eight leading non-relativistic components of the interaction is investigated
and, in most cases, found to be clearly dominated by a well defined class of
diagrams. In particular, the central isovector and spin-orbit, spin-spin, and
tensor isoscalar terms are almost completely fixed by just and .
The convergence of the chiral series in powers of the ratio (pion mass/nucleon
mass) is studied as a function of the internucleon distance and, for 1 fm,
found to be adequate for most components of the potential. An important
exception is the dominant central isoscalar term, where the convergence is
evident only for 2.5 fm. Finally, we compare the spatial behavior of the
functions that enter the relativistic and heavy baryon formulations of the
interaction and find that, in the region of physical interest, they differ by
about 5%.Comment: 27 pages, 33 figure
Measurement of neutron diffraction with compact neutron source RANS
Diffraction is used as a measurement technique for crystal structure. X-rays or electron beam with wavelength that is close to the lattice constant of the crystal is often used for the measurement. They have sensitivity in surface
(0.01mm) of heavy metals due to the mean free path for heavy ions. Neutron diffraction has the probe of the internal structure of the heavy metals because it has a
longer mean free path than that of the X-rays or the electrons. However, the neutron diffraction measurement is not widely used because large facilities are required in the many neutron sources. RANS (Riken Accelerator-driven Compact Neutron Source) is developed as a neutron source which is usable easily in laboratories and factories. In RANS, fast neutrons are generated by 7MeV protons colliding on a Be target. Some fast neutrons are moderated with polyethylene to thermal neutrons. The thermal neutrons of 10meV which have wavelength of 10nm can be used for the
diffraction measurement. In this study, the texture evolution in steels was measured with RANS and the validity of the compact neutron source was proved. The texture of IF steel sheets with the thickness of 1.0mm was measured with 10minutes run. The resolution is 2% and is enough to analyze a evolution in texture due to compression/tensile deformation or a volume fraction of two phases in the steel sample. These results have proven the possibility to use compact neutron source for the analysis of mesoscopic structure of metallic materials
Morphological features and water solubility of iron in aged fine aerosol particles over the Indian Ocean
Atmospheric transport of iron (Fe) in fine anthropogenic aerosol
particles is an important route of soluble Fe supply from continental areas
to remote oceans. To elucidate Fe properties of aerosol particles over
remote oceans, we collected atmospheric aerosol particles over the Indian
Ocean during the RV Hakuho Maru KH-18-6 cruise. After aerosol particles were collected
using a cascade impactor, particles of 0.3–0.9 µm aerodynamic diameter
on the sample stage were analyzed using transmission electron microscopy
(TEM) with an energy-dispersive X-ray spectrometry analyzer. The particle
shape and composition indicated that most particles collected north of the
Equator were composed mainly of ammonium sulfate. Regarding the particle
number fraction, 0.6 %–3.0 % of particles contained Fe, which mostly
co-existed with sulfate. Of those particles, 26 % of Fe occurred as metal
spheres, often co-existing with Al or Si, regarded as fly ash; 14 % as
mineral dust; and 7 % as iron oxide aggregates. Water dialysis analyses of
TEM samples indicated Fe in spherical fly ash as being almost entirely insoluble
and Fe in other morphological-type particles as being partly soluble (65 % Fe
mass on average). Global model simulations mostly reproduced observed Fe
mass concentrations in particulate matter with a diameter of less than 2.5 µm (PM2.5) collected using a high-volume air sampler,
including their north–south contrast during the cruise. In contrast, a
marked difference was found between the simulated mass fractions of Fe
mineral sources and the observed Fe types. For instance, the model
underestimated anthropogenic aluminosilicate (illite and kaolinite) Fe
contained in matter such as fly ash from coal combustion. Our observations
revealed multiple shapes and compositions of Fe minerals in particles over
remote ocean areas and further suggested that their solubilities after
aging processes differ depending on their morphological and mineral types.
Proper consideration of such Fe types at their sources is necessary for
accurately estimating atmospheric Fe effects on marine biological activity.</p
Status and overview of development of the Silicon Pixel Detector for the PHENIX experiment at the BNL RHIC
We have developed a silicon pixel detector to enhance the physics
capabilities of the PHENIX experiment. This detector, consisting of two layers
of sensors, will be installed around the beam pipe at the collision point and
covers a pseudo-rapidity of | \eta | < 1.2 and an azimuth angle of | \phi | ~
2{\pi}. The detector uses 200 um thick silicon sensors and readout chips
developed for the ALICE experiment. In order to meet the PHENIX DAQ readout
requirements, it is necessary to read out 4 readout chips in parallel. The
physics goals of PHENIX require that radiation thickness of the detector be
minimized. To meet these criteria, the detector has been designed and
developed. In this paper, we report the current status of the development,
especially the development of the low-mass readout bus and the front-end
readout electronics.Comment: 9 pages, 8 figures and 1 table in DOCX (Word 2007); PIXEL 2008
workshop proceedings, will be published in the Proceedings Section of
JINST(Journal of Instrumentation
Parafibromin tumor suppressor enhances cell growth in the cells expressing SV40 large T antigen
Parafibromin is a 531-amino acid protein encoded by HRPT2, a putative tumor suppressor gene recently implicated in the autosomal dominant hyperparathyroidism-jaw tumor familial cancer syndrome and sporadic parathyroid carcinoma. To investigate effects of parafibromin's overexpression on cell proliferation, we performed assays in four different cell lines. The transient overexpression of parafibromin inhibited cell growth in HEK293 and NIH3T3 cells, but enhanced cell growth in the SV40 large T antigen expressing-cell lines such as 293FT and COS7 cells. In 293FT cells, parafibromin was found to interact with SV40 large T antigen and its overexpression promoted entry into the S phase, implying that the interaction enhanced progression through the cell cycle. The tumor suppressor protein parafibromin acts as a positive regulator of cell growth like an oncoprotein in the presence of SV40 large T antigen
Alteration of the size distributions and mixing states of black carbon through transport in the boundary layer in east Asia
Ground-based measurements of black carbon (BC) were performed near
an industrial source region in the early summer of 2014 and at a remote
island in Japan in the spring of 2015. Here, we report the temporal
variations in the transport, size distributions, and mixing states of the
BC-containing particles. These particles were characterized using a
continuous soot monitoring system, a single particle soot photometer, and an
aerosol chemical speciation monitor. The effects of aging on the growth of
BC-containing particles were examined by comparing the ground-based
observations between the near-source and remote island sites. Secondary
formation of sulfate and organic aerosols strongly affected the increases in
BC coating (i.e., enhancement of cloud condensation nuclei activity) with air
mass aging from the source to the outflow regions. The effects of wet removal
on BC microphysics were elucidated by classifying the continental outflow air
masses depending on the enhancement ratios of BC to CO (ΔBC ∕ ΔCO), which were used as an indicator of the transport efficiency of
BC. It was found that ΔBC ∕ ΔCO ratios were controlled mainly
by the wet removal during transport in the planetary boundary layer (PBL) on
the timescale of 1–2 days. The meteorological conditions and backward
trajectory analyses suggested that air masses strongly affected by wet
removal originated mainly from a region in southern China (20–35° N) in the spring of 2015. Removal of large and
thickly coated BC-containing particles was detected in the air masses that
were substantially affected by the wet removal in the PBL, as predicted by
Köhler theory. The size and water solubility of BC-containing particles
in the PBL can be altered by the wet removal as well as the condensation of
non-BC materials
Preparation of 169Yb Calibration Sources for the Measurement of Electron Anti-Neutrino Mass
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