6,196 research outputs found
"Dry-column" chromatography of plant pigments
Separation of plant pigments which can be accomplished on thin-layer silica plates with mixture of petroleum ether, halocarbon, acetone, and polar solvent can be readily translated into dry-column technique that yields reproducible chromatograms after elution in fashion of liquid chromatography with fluorimeter as detector. Best solvent system was found to be mixture of petroleum ether, dichloromethane, acetone, and ethyl acetate
Cross section normalization in proton-proton collisions at = 2.76 TeV and 7 TeV, with ALICE at LHC
Measurements of the cross sections of the reference processes seen by the
ALICE trigger system were obtained based on beam properties measured from van
der Meer scans. The measurements are essential for absolute cross section
determinations of physics processes.
The paper focuses on instrumental and technical aspects of detectors and
accelerators, including a description of the extraction of beam properties from
the van der Meer scan. As a result, cross sections of reference processes seen
by the ALICE trigger system are given for proton-proton collisions at two
energies; =2.76 TeV and 7 TeV, together with systematic uncertainties
originating from beam intensity measurements and other detector effects.
Consistency checks were performed by comparing to data from other experiments
in LHC.Comment: Quark Matter 2011 Conference Proceedings, 4 pages, 2 figure
A Measurement of Proper Motions of SiO Maser Sources in the Galactic Center with the VLBA
We report on the high-precision astrometric observations of maser sources
around the Galactic Center in the SiO J=1--0 v=1 and 2 lines with the VLBA
during 2001 -- 2004. With phase-referencing interferometry referred to the
radio continuum source Sgr A*, accurate positions of masers were obtained for
three detected objects: IRS 10 EE (7 epochs), IRS 15NE (2 epochs), and SiO 6
(only 1 epoch). Because circumstellar masers of these objects were resolved
into several components, proper motions for the maser sources were derived with
several different methods. Combining our VLBA results with those of the
previous VLA observations, we obtained the IRS 10EE proper motion of 76+-3 km
s^{-1} (at 8 kpc) to the south relative to Sgr A*. Almost null proper motion of
this star in the east--west direction results in a net transverse motion of the
infrared reference frame of about 30+-9 km s^{-1} to the west relative to Sgr
A*. The proper-motion data also suggests that IRS 10EE is an astrometric binary
with an unseen massive companion.Comment: High-res. figures are available at
ftp://ftp.nro.nao.ac.jp/nroreport/no656.pdf.gz . PASJ 60, No. 1 (2008) in
pres
A sensitive cloud chamber without radioactive sources
We present a sensitive diffusion cloud chamber which does not require any
radioactive sources. A major difference from a commonly used chamber is use of
a heat sink as its bottom plate. A result of a performance test of the chamber
is given.Comment: 8 pages, 8 figures, iopart.cls, figures and references adde
SHG microscopic observations of polar state in Li-doped KTaO3 under electric field
Incipient ferroelectric KTaO3 with off-center Li impurity of the critical
concentration of 2.8 mol% was investigated in order to clarify the dipole glass
state under electric field. Using optical second-harmonic generation (SHG)
microscope, we observed a marked history dependence of SHG intensity through
zero-field cooling (ZFC), zero-field heating (ZFH), field heating after ZFC
(FH/ZFC) and FH after field cooling (FH/FC). These show different paths with
respect to temperature: In the ZFC/ZFH process, weak SHG was observed at low
temperature, while in the FH/ZFC process, relatively high SHG appears in a
limited temperature range below TF depending on the field strength, and in the
FC and FH/FC processes, the SHG exhibits ferroelectric-like temperature
dependence: it appears at the freezing temperature of 50K, increases with
decreasing temperature and has a tendency of saturation. These experimental
results strongly suggest that dipole glass state or polar nano-clusters which
gradually freezes with decreasing temperature is transformed into
semi-macroscopic polar state under the electric field. However at sufficiently
low temperature, the freezing is so strong that the electric field cannot
enlarge the polar clusters. These experimental results show that the polar
nano-cluster model similar to relaxors would be more relevant in KTaO3 doped
with the critical concentration of Li. Further experiments on the anisotropy of
SHG determine that the average symmetry of the field-induced polar phase is
tetragonal 4mm or 4, which is also confirmed by the X-ray diffraction
measurement.Comment: 26 pages, 8 figures, 1 tabl
p21 is decreased in polycystic kidney disease and leads to increased epithelial cell cycle progression: roscovitine augments p21 levels.
BackgroundAutosomal dominant polycystic kidney disease (ADPKD) is a common genetic disease with few treatment options other than renal replacement therapy. p21, a cyclin kinase inhibitor which has pleiotropic effects on the cell cycle, in many cases acts to suppress cell cycle progression and to prevent apoptosis. Because defects in cell cycle arrest and apoptosis of renal tubular epithelial cells occur in PKD, and in light of earlier reports that polycystin-1 upregulates p21 and that the cyclin-dependent kinase inhibitor roscovitine arrests progression in a mouse model, we asked whether (1) p21 deficiency might underlie ADPKD and (2) the mechanism of the salutary roscovitine effect on PKD involves p21.Methodsp21 levels in human and animal tissue samples as well as cell lines were examined by immunoblotting and/or immunohistochemisty. Apoptosis was assessed by PARP cleavage. p21 expression was attenuated in a renal tubular epithelial cell line by antisense methods, and proliferation in response to p21 attenuation and to roscovitine was assessed by the MTT assay.ResultsWe show that p21 is decreased in human as well as a non-transgenic rat model of ADPKD. In addition, hepatocyte growth factor, which induces transition from a cystic to a tubular phenotype, increases p21 levels. Furthermore, attenuation of p21 results in augmentation of cell cycle transit in vitro. Thus, levels of p21 are inversely correlated with renal tubular epithelial cell proliferation. Roscovitine, which has been shown to arrest progression in a murine model of PKD, increases p21 levels and decreases renal tubular epithelial cell proliferation, with no affect on apoptosis.ConclusionThe novelty of our study is the demonstration in vivo in humans and rat models of a decrement of p21 in cystic kidneys as compared to non-cystic kidneys. Validation of a potential pathogenetic model of increased cyst formation due to enhanced epithelial proliferation and apoptosis mediated by p21 suggests a mechanism for the salutary effect of roscovitine in ADPKD and supports further investigation of p21 as a target for future therapy
Slow relaxation to equipartition in spring-chain systems
In this study, one-dimensional systems of masses connected by springs, i.e.,
spring-chain systems, are investigated numerically. The average kinetic energy
of chain-end particles of these systems is larger than that of other particles,
which is similar to the behavior observed for systems made of masses connected
by rigid links. The energetic motion of the end particles is, however,
transient, and the system relaxes to thermal equilibrium after a while, where
the average kinetic energy of each particle is the same, that is, equipartition
of energy is achieved. This is in contrast to the case of systems made of
masses connected by rigid links, where the energetic motion of the end
particles is observed in equilibrium. The timescale of relaxation estimated by
simulation increases rapidly with increasing spring constant. The timescale is
also estimated using the Boltzmann-Jeans theory and is found to be in quite
good agreement with that obtained by the simulation
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