4,428 research outputs found
Boundary effect on CDW: Friedel oscillations, STM image
We study the effect of open boundary condition on charge density waves (CDW).
The electron density oscillates rapidly close to the boundary, and additional
non-oscillating terms (~ln(r)) appear. The Friedel oscillations survive beyond
the CDW coherence length (v_F/Delta), but their amplitude gets heavily
suppressed. The scanning tunneling microscopy image (STM) of CDW shows clear
features of the boundary. The local tunneling conductance becomes asymmetric
with respect to the Fermi energy, and considerable amount of spectral weight is
transferred to the lower gap edge. Also it exhibits additional zeros reflecting
the influence of the boundary.Comment: 7 pages, 6 figure
Regularizing Face Verification Nets For Pain Intensity Regression
Limited labeled data are available for the research of estimating facial
expression intensities. For instance, the ability to train deep networks for
automated pain assessment is limited by small datasets with labels of
patient-reported pain intensities. Fortunately, fine-tuning from a
data-extensive pre-trained domain, such as face verification, can alleviate
this problem. In this paper, we propose a network that fine-tunes a
state-of-the-art face verification network using a regularized regression loss
and additional data with expression labels. In this way, the expression
intensity regression task can benefit from the rich feature representations
trained on a huge amount of data for face verification. The proposed
regularized deep regressor is applied to estimate the pain expression intensity
and verified on the widely-used UNBC-McMaster Shoulder-Pain dataset, achieving
the state-of-the-art performance. A weighted evaluation metric is also proposed
to address the imbalance issue of different pain intensities.Comment: 5 pages, 3 figure; Camera-ready version to appear at IEEE ICIP 201
Asymptotic quasinormal modes of scalar field in a gravity's rainbow
In the context of a gravity's rainbow, the asymptotic quasinormal modes of
the scalar perturbation in the quantum modified Schwarzschild black holes are
investigated. By using the monodromy method, we calculated and obtained the
asymptotic quasinormal frequencies, which are dominated not only by the mass
parameter of the spacetime, but also by the energy functions from the modified
dispersion relations. However, the real parts of the asymptotic quasinormal
modes is still , which is consistent with Hod's conjecture. In
addition, for the quantum corrected black hole, the area spacing is calculated
and the result is independent of the energy functions, in spite of the area
itself is energy dependence. And that, by relating the area spectrum to loop
quantum gravity, the Barbero-Immirzi parameter is given and it remains the same
as from the usual black hole
Variability of Soft X-ray Spectral Shape in Blazars Observed by ROSAT
In paper 1 (Cheng et al. 2001) we have shown that the soft X-ray spectra of
two types of Seyfert 1 galaxies statistically vary differently with increasing
intensity. In order to understand how the spectrum of blazars changes, the
spectral shape variability of 18 blazars observed by ROSAT/PSPC mode are
studied by presenting the correlation of Hardness Ratio 1 versus Count Rates
(HR1-CTs). According to our criteria, 10 blazars show a positive HR1-CTs
relation, and only 2 blazars display an anti-correlation of HR1 versus CTs. The
rest 6 blazars do not indicate any clear correlation. From these we can see
that most blazars of our sample statistically show a hardening spectrum during
overall flux increase, though some vary randomly. By investigating the photon
index of these objects and different radiation theories, we argue that the
dominance of the synchrotron or inverse Compton emission in the soft X-ray band
may interpret the dichotomy of spectral variability well, and that different
spectral variations might represent a sequence of synchrotron peaked frequency.Comment: 11 pages, 3 figures, CJA
Ochrocephalamine A, a new quinolizidine alkaloid from Oxytropis ochrocephala Bunge
One dimeric matrine-type alkaloid, ochrocephalamine A (1), was isolated from the poisonous plant Oxytropis ochrocephala Bunge. Its structure was elucidated by spectroscopic data and single-crystal X-ray diffraction. The insecticidal and cytotoxic activities of 1 were evaluated
Chronic adiponectin deficiency leads to Alzheimer’s disease-like cognitive impairments and pathologies through AMPK inactivation and cerebral insulin resistance in aged mice
BACKGROUND: Insulin resistance is the major pathogenesis underlying type 2 diabetes mellitus (T2DM) and these patients have doubled risk of Alzheimer's disease (AD). Increasing evidence suggests that insulin resistance plays an important role in AD pathogenesis, possibly due to abnormal GSK3β activation, causing intra- and extracellular amyloid-beta (Aβ) accumulation. Adiponectin (APN) is an adipokine with insulin-sensitizing and anti-inflammatory effects. Reduced circulatory APN level is associated with insulin resistance and T2DM. The role of APN in AD has not been elucidated. In this study, we aim to examine if adiponectin deficiency would lead to cerebral insulin resistance, cognitive decline and Alzheimer's-like pathology in mice. METHODS: To study the role of adiponectin in cognitive functions, we employed adiponectin-knockout (APN-KO) mice and demonstrated chronic APN deficiency in their CNS. Behavioral tests were performed to study the cognitions of male APN-KO mice. Brains and tissue lysates were collected to study the pathophysiological and molecular changes in the brain of APN-KO mice. SH-SY5Y neuroblastoma cell line was used to study the molecular mechanism upon APN and insulin treatment. RESULTS: Aged APN-deficient mice displayed spatial memory and learning impairments, fear-conditioned memory deficit as well as anxiety. These mice also developed AD pathologies including increased cerebral Aβ42 level, Aβ deposition, hyperphosphorylated Tau proteins, microgliosis and astrogliosis with increased cerebral IL-1β and TNFα levels that associated with increased neuronal apoptosis and reduced synaptic proteins levels, suggesting APN deficiency may lead to neuronal and synaptic loss in the brain. AD pathologies-associated APN-KO mice displayed attenuated AMPK phosphorylation and impaired insulin signaling including decreased Akt induction and increased GSK3β activation in the hippocampus and frontal cortex. Aged APN-KO mice developed hippocampal insulin resistance with reduced pAkt induction upon intracerebral insulin injection. Consistently, APN treatment in SH-SY5Y cells with insulin resistance and overexpressing Aβ induce higher pAkt levels through AdipoR1 upon insulin treatment whereas the induction was blocked by compound C, indicating APN can enhance neuronal insulin sensitivity through AMPK activation. CONCLUSION: Our results indicated that chronic APN deficiency inactivated AMPK causing insulin desensitization and elicited AD-like pathogenesis in aged mice which also developed significant cognitive impairments and psychiatric symptoms.published_or_final_versio
Restudy on Dark Matter Time-Evolution in the Littlest Higgs model with T-parity
Following previous study, in the Littlest Higgs model (LHM), the heavy photon
is supposed to be a possible dark matter candidate and its relic abundance of
the heavy photon is estimated in terms of the Boltzman-Lee-Weinberg
time-evolution equation. The effects of the T-parity violation is also
considered. Our calculations show that when Higgs mass taken to be 300
GeV and don't consider T-parity violation, only two narrow ranges
GeV and GeV are tolerable with the
current astrophysical observation and if GeV, there must at
least exist another species of heavy particle contributing to the cold dark
matter. As long as the T-parity can be violated, the heavy photon can decay
into regular standard model particles and would affect the dark matter
abundance in the universe, we discuss the constraint on the T-parity violation
parameter based on the present data. Direct detection prospects are also
discussed in some detail.Comment: 13 pages, 11 figures include
- …