793 research outputs found
R&D Status of Nuclear Emulsion For Directional Dark Matter Search
In this study, we are doing R&D for directional dark matter search with
nuclear emulsion. First of all, higher resolution nuclear emulsion with fine
silver halide crystals was developed in the production facility of emulsion at
Nagoya university, and we confirmed that it can detect the expected nuclear
recoil tracks. The readout of submicron tracks was required the new technology.
We developed the expansion technique, and could readout the signal by shape
analysis with optical microscopy. The two dimensional angular resolution is 36
degrees at the original track length of range from 150nm to 200nm with optical
microscopy. Finally we demonstrated by using recoiled nuclei induced by 14.8MeV
neutron, and confirmed the technique.Moreover, we developed the X-ray
microscope system with SPring-8 as final check with higher resolution of
selected candidate tracks with optical microscopy. The angular resolution was
improved from 31 degrees with optical microscopy to 17degrees with X-ray
microscopy at the track length of range from 150nm to 250nm. We are developing
the practical system and planning for start of the test running with prototype
detector.Comment: Proceedings of the 3rd International conference on Directional
Detection of Dark Matter (CYGNUS 2011), Aussois, France, 8-10 June 201
An Obstruction to Quantization of the Sphere
In the standard example of strict deformation quantization of the symplectic
sphere , the set of allowed values of the quantization parameter
is not connected; indeed, it is almost discrete. Li recently constructed a
class of examples (including ) in which can take any value in an
interval, but these examples are badly behaved. Here, I identify a natural
additional axiom for strict deformation quantization and prove that it implies
that the parameter set for quantizing is never connected.Comment: 23 page. v2: changed sign conventio
Direct perturbation theory on the shift of Electron Spin Resonance
We formulate a direct and systematic perturbation theory on the shift of the
main paramagnetic peak in Electron Spin Resonance, and derive a general
expression up to second order. It is applied to one-dimensional XXZ and
transverse Ising models in the high field limit, to obtain explicit results
including the polarization dependence for arbitrary temperature.Comment: 5 pages (no figures) in REVTE
Chaos and its quantization in dynamical Jahn-Teller systems
We investigate the Jahn-Teller system for the purpose to
reveal the nature of quantum chaos in crystals. This system simulates the
interaction between the nuclear vibrational modes and the electronic motion in
non-Kramers doublets for multiplets of transition-metal ions. Inclusion of the
anharmonic potential due to the trigonal symmetry in crystals makes the system
nonintegrable and chaotic. Besides the quantal analysis of the transition from
Poisson to Wigner level statistics with increasing the strength of
anharmonicity, we study the effect of chaos on the electronic orbital angular
momentum and explore the magnetic -factor as a function of the system's
energy. The regular oscillation of this factor changes to a rapidly-decaying
irregular oscillation by increasing the anharmonicity (chaoticity).Comment: 8 pages, 6 figure
Frustrated quantum-spin system on a triangle coupled with lattice vibrations - Correspondence to Longuet-Higgins et al.'s Jahn-Teller model -
We investigate the quantum three spin model
of spin on a triangle, in which spins are coupled with
lattice-vibrational modes through the exchange interaction depending on
distances between spin sites. The present model corresponds to the dynamic
Jahn-Teller system proposed by Longuet-Higgins {\it et al.},
Proc.R.Soc.A.{\bf 244},1(1958). This correspondence is revealed by using the
transformation to Nakamura-Bishop's bases proposed in Phys.Rev.Lett.{\bf
54},861(1985). Furthermore, we elucidate the relationship between the behavior
of a chiral order parameter and
that of the electronic orbital angular momentum in vibronic model: The regular oscillatory behavior of the expectation value
. The increase of the additional
anharmonicity(chaoticity) is found to yield a rapidly decaying irregular
oscillation of
Dynamic regulation of Ero1 and peroxiredoxin 4 localization in the secretory pathway
In the early secretory compartment (ESC), a network of chaper-
ones and enzymes assists oxidative folding of nascent proteins.
Ero1 flavoproteins oxidize protein disulfide isomerase (PDI), gen-
erating H2O2 as a byproduct. Peroxiredoxin 4 (Prx4) can utilize
luminal H2O2 to oxidize PDI, thus favoring oxidative folding while
limiting oxidative stress. Interestingly, neither ER oxidase contains
known ER retention signal(s), raising the question of how cells pre-
vent their secretion. Here we show that the two proteins share sim-
ilar intracellular localization mechanisms. Their secretion is pre-
vented by sequential interactions with PDI and ERp44, two
resident proteins of the ESC-bearing KDEL-like motifs. PDI binds
preferentially Ero1 , whereas ERp44 equally retains Ero1 and
Prx4. The different binding properties of Ero1 and Prx4 increase
the robustness of ER redox homeostasis
Findings of N-Isopropyl-p-(^<123>I)-Iodoamphetamine SPECT in Mitochondrial encephalomyopathy with lactic acidosis and strokelike episodes (MELAS) : Case report and review of literature
This study investigated the recollections of child survivors of the 2004 Asian tsunami in terms of their vantage point and posttraumatic stress disorder (PTSD) responses. Five years after the tsunami, 110 children (aged 7-13 years) living in Aceh, Indonesia were assessed for source of memories of the tsunami (personal memory or second-hand source), vantage point of the memory, and were administered the Children's Revised Impact of Event Scale-13. Fifty-three children (48%) met criteria for PTSD. Two-thirds of children reported direct memories of the tsunami and one-third reported having memories based on reports from other people. More children (97%) who reported an indirect memory of the tsunami recalled the event from an onlooker's perspective to some extent than those who recalled the event directly (63%). Boys were more likely to rely on stories from others to reconstruct their memory of the tsunami, and to adopt an observer perspective. Boys who adopted an observer's perspective had less severe PTSD than those who adopted a field perspective. These findings suggest that, at least in the case of boys, an observer perspectives of trauma can be associated with levels of PTSD
PLEIAD/SIMC1/C5orf25, a Novel Autolysis Regulator for a Skeletal-Muscle-Specific Calpain, CAPN3, Scaffolds a CAPN3 Substrate, CTBP1
AbstractCAPN3/p94/calpain-3 is a skeletal-muscle-specific member of the calpain protease family. Multiple muscle cell functions have been reported for CAPN3, and mutations in this protease cause limb-girdle muscular dystrophy type 2A. Little is known about the molecular mechanisms that allow CAPN3 to be so multifunctional. One hypothesis is that the very rapid and exhaustive autolytic activity of CAPN3 needs to be suppressed by dynamic molecular interactions for specific periods of time. The previously identified interaction between CAPN3 and connectin/titin, a giant molecule in muscle sarcomeres, supports this assumption; however, the regulatory mechanisms of non-sarcomere-associated CAPN3 are unknown. Here, we report that a novel CAPN3-binding protein, PLEIAD [Platform element for inhibition of autolytic degradation; originally called SIMC1/C5orf25 (SUMO-interacting motif containing protein 1/chromosome 5 open reading frame 25)], suppresses the protease activity of CAPN3. Database analyses showed that PLEIAD homologs, like CAPN3 homologs, are evolutionarily conserved in vertebrates. Furthermore, we found that PLEIAD also interacts with CTBP1 (C-terminal binding protein 1), a transcriptional co-regulator, and CTBP1 is proteolyzed in COS7 cells expressing CAPN3. The identified cleavage sites in CTBP1 suggested that it undergoes functional modification upon its proteolysis by CAPN3, as well as by conventional calpains. These results indicate that PLEIAD can shift its major function from CAPN3 suppression to CAPN3-substrate recruitment, depending on the cellular context. Taken together, our data suggest that PLEIAD is a novel regulatory scaffold for CAPN3, as reflected in its name
Electron Spin Resonance in S=1/2 antiferromagnetic chains
A systematic field-theory approach to Electron Spin Resonance (ESR) in the
quantum antiferromagnetic chain at low temperature (compared to the
exchange coupling ) is developed. In particular, effects of a transverse
staggered field and an exchange anisotropy (including a dipolar
interaction) on the ESR lineshape are discussed. In the lowest order
of perturbation theory, the linewidth is given as and
, respectively. In the case of a transverse staggered
field, the perturbative expansion diverges at lower temperature;
non-perturbative effects at very low temperature are discussed using exact
results on the sine-Gordon field theory. We also compare our field-theory
results with the predictions of Kubo-Tomita theory for the high-temperature
regime, and discuss the crossover between the two regimes. It is argued that a
naive application of the standard Kubo-Tomita theory to the
Dzyaloshinskii-Moriya interaction gives an incorrect result. A rigorous and
exact identity on the polarization dependence is derived for certain class of
anisotropy, and compared with the field-theory results.Comment: 53 pages in REVTEX, 7 figures in EPS included; revised version with
missing references and correction
Two-magnon Raman scattering in spin-ladder geometries and the ratio of rung and leg exchange constants
We discuss ways in which the ratio of exchange constants along the rungs and
legs of a spin-ladder material influences the two-magnon Raman scattering
spectra and hence can be determined from it. We show that within the
Fleury-Loudon-Elliott approach, the Raman line-shape does not change with
polarization geometries. This lineshape is well known to be difficult to
calculate accurately from theory. However, the Raman scattering intensities do
vary with polarization geometries, which are easy to calculate. With some
assumptions about the Raman scattering Hamiltonian, the latter can be used to
estimate the ratio of exchange constants. We apply these results to Sugai's
recent measurements of Raman scattering from spin-ladder materials such as
LaCaCuO and SrCuO.Comment: 5 pages, revtex. Latest version focuses on ladder materials, with a
detailed examination of the role of Heisenberg-like coupling constants which
appear in the Fleury-Loudon-Elliott scattering operator but are rarely
discussed in the literatur
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