235 research outputs found
Protection from Lethal Cell Death in Cecal Ligation and Puncture-Induced Sepsis Mouse Model by In Vivo Delivery of FADD siRNA
The Aligned Model
In Calabi-Yau string compactification, it is pointed out that there exists a
new type of model (the aligned
model) in which the differs from the standard and also from the
flipped . With the aid of the discrete symmetry suggested from Gepner
model, we construct a simple and phenomenologically interesting
three-generation model with the aligned gauge symmetry.
The triplet-doublet splitting problem can be solved. It is also found that
there is a realistic solution for solar neutrino problem and for the -problem. At low energies this model is in accord with the minimal
supersymmetric standard model except for the existence of singlet fields with
masses of TeV.Comment: LaTeX 24 page
Unconventional critical scaling of magnetization in uranium ferromagnetic superconductors UGe and URhGe
We report a dc magnetization study of the critical phenomenon around the
ferromagnetic transition temperature T_C in high-quality single crystals of
uranium ferromagnetic superconductors UGe2 and URhGe. The critical exponents,
beta for the temperature dependence of the magnetization below T_C, gamma for
the magnetic susceptibility, and delta for the magnetic isothermal at T_C have
been determined with a modified Arrott plot, a Kouvel-Fisher plot, and the
scaling analysis. Magnetization in the ferromagnetic state has strong uniaxial
magnetic anisotropy in the two compounds. However, the universality class of
the critical phenomena do not belong to the three dimensional (3D) Ising
system. Although the values of beta in UGe2 and URhGe are close to those in the
3D magnets, the values of gamma are close to unity, that expected from the mean
field theory. Similar critical exponents have been reported previously for the
3D Ising ferromagnet UIr where superconductivity appears under high pressure.
The critical behavior may be limited to a very narrow Ginzburg critical region
of 1 mK because of the strong itinerant character of the 5f electrons in the
ferromagnetic superconductor UCoGe where the mean field behavior of the
magnetization has been reported. The unconventional critical scaling of
magnetization in UGe2, URhGe and UIr cannot be explained via previous
approaches to critical phenomena. The ferromagnetic correlation between the 5f
electrons differs from that in the 3D Ising system and this difference may be a
key point for the understanding of the ferromagnetism where superconductivity
emerges.Comment: 8 pages, 5 figure
Magnetic measurements at pressures above 10 GPa in a miniature ceramic anvil cell for a superconducting quantum interference device magnetometer
A miniature ceramic anvil high pressure cell (mCAC) was earlier designed by
us for magnetic measurements at pressures up to 7.6 GPa in a commercial
superconducting quantum interference (SQUID) magnetometer [N. Tateiwa et al.,
Rev. Sci. Instrum. 82, 053906 (2011)]. Here, we describe methods to generate
pressures above 10 GPa in the mCAC. The efficiency of the pressure generation
is sharply improved when the Cu-Be gasket is sufficiently preindented. The
maximum pressure for the 0.6 mm culet anvils is 12.6 GPa when the Cu-Be gasket
is preindented from the initial thickness of 0.30 to 0.06 mm. The 0.5 mm culet
anvils were also tested with a rhenium gasket. The maximum pressure attainable
in the mCAC is about 13 GPa. The present cell was used to study YbCu2Si2 which
shows a pressure induced transition from the non-magnetic to magnetic phases at
8 GPa. We confirm a ferromagnetic transition from the dc magnetization
measurement at high pressure. The mCAC can detect the ferromagnetic ordered
state whose spontaneous magnetic moment is smaller than 1 mB per unit cell. The
high sensitivity for magnetic measurements in the mCAC may result from the the
simplicity of cell structure. The present study shows the availability of the
mCAC for precise magnetic measurements at pressures above 10 GPa
The Weak-Scale Hierarchy and Discrete Symmetries
In the underlying Planck scale theory we introduce a certain type of discrete
symmetry, which potentially brings the stability of the weak-scale hierarchy
under control. Under the discrete symmetry the -problem and the tadpole
problem can be solved simultaneously without relying on some fine-tuning of
parameters. Instead, it is required that doublet Higgs and color-triplet Higgs
fields reside in different irreducible representations of the gauge symmetry
group at the Planck scale and that they have distinct charges of the discrete
symmetry group.Comment: 13 pages, LATEX, 1 figures(not included, available on request by fax
or Postscript file
Membrane topology analysis of HIV-1 envelope glycoprotein gp41
<p>Abstract</p> <p>Background</p> <p>The gp41 subunit of the HIV-1 envelope glycoprotein (Env) has been widely regarded as a type I transmembrane protein with a single membrane-spanning domain (MSD). An alternative topology model suggested multiple MSDs. The major discrepancy between the two models is that the cytoplasmic Kennedy sequence in the single MSD model is assigned as the extracellular loop accessible to neutralizing antibodies in the other model. We examined the membrane topology of the gp41 subunit in both prokaryotic and mammalian systems. We attached topological markers to the C-termini of serially truncated gp41. In the prokaryotic system, we utilized a green fluorescent protein (GFP) that is only active in the cytoplasm. The tag protein (HaloTag) and a membrane-impermeable ligand specific to HaloTag was used in the mammalian system.</p> <p>Results</p> <p>In the absence of membrane fusion, both the prokaryotic and mammalian systems (293FT cells) supported the single MSD model. In the presence of membrane fusion in mammalian cells (293CD4 cells), the data obtained seem to support the multiple MSD model. However, the region predicted to be a potential MSD is the highly hydrophilic Kennedy sequence and is least likely to become a MSD based on several algorithms. Further analysis revealed the induction of membrane permeability during membrane fusion, allowing the membrane-impermeable ligand and antibodies to cross the membrane. Therefore, we cannot completely rule out the possible artifacts. Addition of membrane fusion inhibitors or alterations of the MSD sequence decreased the induction of membrane permeability.</p> <p>Conclusions</p> <p>It is likely that a single MSD model for HIV-1 gp41 holds true even in the presence of membrane fusion. The degree of the augmentation of membrane permeability we observed was dependent on the membrane fusion and sequence of the MSD.</p
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