729 research outputs found
Kinetic energy driven superconductivity in doped cuprates
Within the t-J model, the mechanism of superconductivity in doped cuprates is
studied based on the partial charge-spin separation fermion-spin theory. It is
shown that dressed holons interact occurring directly through the kinetic
energy by exchanging dressed spinon excitations, leading to a net attractive
force between dressed holons, then the electron Cooper pairs originating from
the dressed holon pairing state are due to the charge-spin recombination, and
their condensation reveals the superconducting ground-state. The electron
superconducting transition temperature is determined by the dressed holon pair
transition temperature, and is proportional to the concentration of doped holes
in the underdoped regime. With the common form of the electron Cooper pair, we
also show that there is a coexistence of the electron Cooper pair and
antiferromagnetic short-range correlation, and hence the antiferromagnetic
short-range fluctuation can persist into the superconducting state. Our results
are qualitatively consistent with experiments.Comment: 6 pages, Revtex, two figures are included, corrected typo
Correlation between chemical composition, EHGE and TME of corn for ducks
Correlations between chemical composition, enzymatic hydrolysate gross energy (EHGE), and true metabolizable energy (TME) of corn for ducks were investigated. Twenty-two corn samples were collected from various regions in 11 provinces of China. The crude protein (CP), ether extract (EE), neutral detergent fibre (NDF), Ash, gross energy (GE), dry matter (DM), amylopectin (AP), amylose (AM), total starch (TS), and AP/AM were determined for each sample. Five of the samples of corn were chosen at the mean, mean ± 1 standard deviation (SD), and mean ± 2 SD based on AP/AM. The EHGE of these samples was analysed using the pepsin-artificial small intestinal fluid enzymatic method. These five samples were also force-fed to male Cherry Valley ducks to assay their TME. Finally, correlation analyses were performed, and regression equations were established. Ash content, GE, and TS were highly related to EHGE. Univariate prediction equations were EHGE = 11.8566Ash-0.0421 (P <0.05), EHGE = 0.1535GE1.5642 (P <0.05), and EHGE = 0.1020TS1.1561 (P <0.05). The total starch, AP/AM, and ash of the chemical compositions were highly related to TME. The corresponding univariate regression equations were TME = 21.9355TS-0.0910 (P <0.05), TME = 15.6590AP/AM-0.0559 (P <0.05), and TME = 15.0778Ash0.0442 (P <0.05). The mean EHGE was equivalent to 78.5% of TME, but their correlation coefficient was low. In conclusion, chemical composition was predictive of EHGE and TME of corn samples for ducks, but the correlation of EHGE and TME was low
Keywords: Cherry Valley duck, amylopectin, amylose, true metabolizable energ
Knockout of p75 neurotrophin receptor attenuates the hyperphosphorylation of Tau in pR5 mouse model
p75 neurotrophin receptor (p75NTR) has been implicated in Alzheimer's disease (AD). However, whether p75NTR is involved in Tau hyperphosphorylation, one of the pathologies observed in AD, remains unclear. In our previous study, the extracellular domain of p75NTR blocked amyloid beta (Aβ) toxicity and attenuated Aβ-induced Tau hyperphosphorylation. Here we show that, in the absence of Aβ, p75NTR regulates Tau phosphorylation in the transgenic mice with the P301L human Tau mutation (pR5). The knockout of p75NTR in pR5 mice attenuated the phosphorylation of human Tau. In addition, the elevated activity of kinases responsible for Tau phosphorylation including glycogen synthase kinase 3 beta; cyclin-dependent-kinase 5; and Rho-associated protein kinase was also inhibited when p75NTR is knocked out in pR5 mice at 9 months of age. The increased caspase-3 activity observed in pR5 mice was also abolished in the absence of p75NTR. Our study also showed that p75NTR is required for Aβ- and pro-brain derived neurotrophin factor (proBDNF)-induced Tau phosphorylation, in vitro. Overall, our data indicate that p75NTR is required for Tau phosphorylation, a key event in the formation of neurofibrillary tangles, another hallmark of AD. Thus, targeting p75NTR could reduce or prevent the pathologic hyperphosphorylation of Tau.Noralyn B. Mañucat-Tan, Lin-Lin Shen, Larisa Bobrovskaya, Mohammed Al-hawwas, Fiona H. Zhou, Yan-Jiang Wang, Xin-Fu Zho
The molecular systems composed of the charmed mesons in the doublet
We study the possible heavy molecular states composed of a pair of charm
mesons in the H and S doublets. Since the P-wave charm-strange mesons
and are extremely narrow, the future experimental
observation of the possible heavy molecular states composed of
and may be feasible if they really exist.
Especially the possible states may be searched for via the
initial state radiation technique.Comment: 42 pages, 4 tables, 31 figures. Improved numerical results and
Corrected typos
Electron Dynamics in NdCeCuO: Evidence for the Pseudogap State and Unconventional c-axis Response
Infrared reflectance measurements were made with light polarized along the a-
and c-axis of both superconducting and antiferromagnetic phases of electron
doped NdCeCuO. The results are compared to
characteristic features of the electromagnetic response in hole doped cuprates.
Within the CuO planes the frequency dependent scattering rate,
1/, is depressed below 650 cm; this behavior is a
hallmark of the pseudogap state. While in several hole doped compounds the
energy scales associated with the pseudogap and superconducting states are
quite close, we are able to show that in NdCeCuO
the two scales differ by more than one order of magnitude. Another feature of
the in-plane charge response is a peak in the real part of the conductivity,
, at 50-110 cm which is in sharp contrast with the
Drude-like response where is centered at . This
latter effect is similar to what is found in disordered hole doped cuprates and
is discussed in the context of carrier localization. Examination of the c-axis
conductivity gives evidence for an anomalously broad frequency range from which
the interlayer superfluid is accumulated. Compelling evidence for the pseudogap
state as well as other characteristics of the charge dynamics in
NdCeCuO signal global similarities of the cuprate
phase diagram with respect to electron and hole doping.Comment: Submitted to PR
Transition from in-plane to out-of-plane azimuthal enhancement in Au+Au collisions
The incident energy at which the azimuthal distributions in semi-central
heavy ion collisions change from in-plane to out-of-plane enhancement, E_tran,
is studied as a function of mass of emitted particles, their transverse
momentum and centrality for Au+Au collisions. The analysis is performed in a
reference frame rotated with the sidewards flow angle, Theta_flow, relative to
the beam axis. A systematic decrease of E_tran as function of mass of the
reaction products, their transverse momentum and collision centrality is
evidenced. The predictions of a microscopic transport model (IQMD) are compared
with the experimental results.Comment: 32 pages, Latex, 22 eps figures, accepted for publication in Nucl.
Phys.
- …