11,035 research outputs found
Deranged calcium signaling and neurodegeneration in spinocerebellar ataxia type 3
Spinocerebellar ataxia type 3 (SCA3), also known as Machado-Joseph disease (MJD), is
an autosomal-dominant neurodegenerative disorder caused by a polyglutamine
expansion in ataxin-3 (SCA3, MJD1) protein. In biochemical experiments we demonstrate
that mutant SCA3exp specifically associated with the type 1 inositol 1,4,5-trisphosphate
receptor (InsP3R1), an intracellular calcium (Ca2+) release channel. In electrophysiological
and Ca2+ imaging experiments we show that InsP3R1 are sensitized to activation by InsP3
in the presence of mutant SCA3exp. We found that feeding SCA3-YAC-84Q transgenic
mice with dantrolene, a clinically relevant stabilizer of intracellular Ca2+ signaling,
improved their motor performance and prevented neuronal cells loss in pontine nuclei
and substantia nigra regions. Our results indicate that deranged Ca2+ signaling may play
an important role in SCA3 pathology and that Ca2+ signaling stabilizers such as
dantrolene may be considered as potential therapeutic drugs for treatment of SCA3
patients
Antiviral treatment alters the frequency of activating and inhibitory receptor-expressing natural killer cells in chronic Hepatitis B virus infected patients
Natural killer (NK) cells play a critical role in innate antiviral immunity, but little is known about the impact of antiviral therapy on the frequency of NK cell subsets. To this aim, we performed this longitudinal study to examine the dynamic changes of the frequency of different subsets of NK cells in CHB patients after initiation of tenofovir or adefovir therapy. We found that NK cell numbers and subset distribution differ between CHB patients and normal subjects; furthermore, the association was found between ALT level and CD158b+ NK cell in HBV patients. In tenofovir group, the frequency of NK cells increased during the treatment accompanied by downregulated expression of NKG2A and KIR2DL3. In adefovir group, NK cell numbers did not differ during the treatment, but also accompanied by downregulated expression of NKG2A and KIR2DL3. Our results demonstrate that treatment with tenofovir leads to viral load reduction, and correlated with NK cell frequencies in peripheral blood of chronic hepatitis B virus infection. In addition, treatments with both tenofovir and adefovir in chronic HBV infected patients induce a decrease of the frequency of inhibitory receptor+ NK cells, which may account for the partial restoration of the function of NK cells in peripheral blood following treatment
Phonon anomaly in BaFe2As2
The detailed optical properties of BaFe2As2 have been determined over a wide
frequency range above and below the structural and magnetic transition at T_N =
138 K. A prominent in-plane infrared-active mode is observed at 253 cm^{-1}
(31.4 meV) at 295 K. The frequency of this vibration shifts discontinuously at
T_N; for T < T_N the frequency of this mode displays almost no temperature
dependence, yet it nearly doubles in intensity. This anomalous behavior appears
to be a consequence of orbital ordering in the Fe-As layers.Comment: 4 pages, 3 figures and one table (minor revisions
Observation of an in-plane magnetic-field-driven phase transition in a quantum Hall system with SU(4) symmetry
In condensed matter physics, the study of electronic states with SU(N)
symmetry has attracted considerable and growing attention in recent years, as
systems with such a symmetry can often have a spontaneous symmetry-breaking
effect giving rise to a novel ground state. For example, pseudospin quantum
Hall ferromagnet of broken SU(2) symmetry has been realized by bringing two
Landau levels close to degeneracy in a bilayer quantum Hall system. In the past
several years, the exploration of collective states in other multi-component
quantum Hall systems has emerged. Here we show the conventional pseudospin
quantum Hall ferromagnetic states with broken SU(2) symmetry collapsed rapidly
into an unexpected state with broken SU(4) symmetry, by in-plane magnetic field
in a two-subband GaAs/AlGaAs two-dimensional electron system at filling factor
around . Within a narrow tilting range angle of 0.5 degrees, the
activation energy increases as much as 12 K. While the origin of this puzzling
observation remains to be exploited, we discuss the possibility of a
long-sought pairing state of electrons with a four-fold degeneracy.Comment: 13 pages, 4 figure
An improvement of isochronous mass spectrometry: Velocity measurements using two time-of-flight detectors
Isochronous mass spectrometry (IMS) in storage rings is a powerful tool for
mass measurements of exotic nuclei with very short half-lives down to several
tens of microseconds, using a multicomponent secondary beam separated in-flight
without cooling. However, the inevitable momentum spread of secondary ions
limits the precision of nuclear masses determined by using IMS. Therefore, the
momentum measurement in addition to the revolution period of stored ions is
crucial to reduce the influence of the momentum spread on the standard
deviation of the revolution period, which would lead to a much improved mass
resolving power of IMS. One of the proposals to upgrade IMS is that the
velocity of secondary ions could be directly measured by using two
time-of-flight (double TOF) detectors installed in a straight section of a
storage ring. In this paper, we outline the principle of IMS with double TOF
detectors and the method to correct the momentum spread of stored ions.Comment: Accepted by Nuclear Inst. and Methods in Physics Research,
Binary Nonlinearization of Lax pairs of Kaup-Newell Soliton Hierarchy
Kaup-Newell soliton hierarchy is derived from a kind of Lax pairs different
from the original ones. Binary nonlinearization procedure corresponding to the
Bargmann symmetry constraint is carried out for those Lax pairs. The proposed
Lax pairs together with adjoint Lax pairs are constrained as a hierarchy of
commutative, finite dimensional integrable Hamiltonian systems in the Liouville
sense, which also provides us with new examples of finite dimensional
integrable Hamiltonian systems. A sort of involutive solutions to the
Kaup-Newell hierarchy are exhibited through the obtained finite dimensional
integrable systems and the general involutive system engendered by binary
nonlinearization is reduced to a specific involutive system generated by
mono-nonlinearization.Comment: 15 pages, plain+ams tex, to be published in Il Nuovo Cimento
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A three-level BDDC algorithm for Mortar discretizations
In this paper, a three-level BDDC algorithm is developed for the solutions of large sparse algebraic linear systems arising from the mortar discretization of elliptic boundary value problems. The mortar discretization is considered on geometrically non-conforming subdomain partitions. In two-level BDDC algorithms, the coarse problem needs to be solved exactly. However, its size will increase with the increase of the number of the subdomains. To overcome this limitation, the three-level algorithm solves the coarse problem inexactly while a good rate of convergence is maintained. This is an extension of previous work, the three-level BDDC algorithms for standard finite element discretization. Estimates of the condition numbers are provided for the three-level BDDC method and numerical experiments are also discussed
Vehicular Communications for 5G Cooperative Small-Cell Networks
© 1967-2012 IEEE. Cooperative transmission is an effective approach for vehicular communications to improve wireless transmission capacity and reliability in fifth-generation (5G) small-cell networks. Based on distances between the vehicle and cooperative small-cell base stations (BSs), the cooperative probability and the coverage probability have been derived for 5G cooperative small-cell networks where small-cell BSs follow Poisson point process distributions. Furthermore, the vehicular handoff rate and the vehicular overhead ratio have been proposed to evaluate the vehicular mobility performance in 5G cooperative small-cell networks. To balance the vehicular communication capacity and the vehicular handoff ratio, an optimal vehicular overhead ratio can be achieved by adjusting the cooperative threshold of 5G cooperative small-cell networks
A SERS nano-tag-based fiber-optic strategy for <em>in situ</em> immunoassay in unprocessed whole blood
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