2,400 research outputs found
Quantile correlations and quantile autoregressive modeling
In this paper, we propose two important measures, quantile correlation (QCOR)
and quantile partial correlation (QPCOR). We then apply them to quantile
autoregressive (QAR) models, and introduce two valuable quantities, the
quantile autocorrelation function (QACF) and the quantile partial
autocorrelation function (QPACF). This allows us to extend the classical
Box-Jenkins approach to quantile autoregressive models. Specifically, the QPACF
of an observed time series can be employed to identify the autoregressive
order, while the QACF of residuals obtained from the fitted model can be used
to assess the model adequacy. We not only demonstrate the asymptotic properties
of QCOR, QPCOR, QACF, and PQACF, but also show the large sample results of the
QAR estimates and the quantile version of the Ljung-Box test. Simulation
studies indicate that the proposed methods perform well in finite samples, and
an empirical example is presented to illustrate usefulness
Orbital symmetry fingerprints for magnetic adatoms in graphene
In this paper, we describe the formation of local resonances in graphene in
the presence of magnetic adatoms containing localized orbitals of arbitrary
symmetry, corresponding to any given angular momentum state. We show that
quantum interference effects which are naturally inbuilt in the honeycomb
lattice in combination with the specific orbital symmetry of the localized
state lead to the formation of fingerprints in differential conductance curves.
In the presence of Jahn-Teller distortion effects, which lift the orbital
degeneracy of the adatoms, the orbital symmetries can lead to distinctive
signatures in the local density of states. We show that those effects allow
scanning tunneling probes to characterize adatoms and defects in graphene.Comment: 15 pages, 11 figures. Added discussion about the multi-orbital case
and the validity of the single orbital picture. Published versio
Charmed weak decays into in the light-front quark model
More than ten weak decay modes have been measured with the
branching fractions relative to that of . In order
to extract the absolute branching fractions, the study of
is needed. In this work, we predict
with the transition form factors calculated in the
light-front quark model. We also predict and .
The previous values for have been found to deviate
from the most recent observation. Nonetheless, our is able to alleviate the deviation. Moreover, we obtain
, which is consistent with the current
data.Comment: 12 pages, 2 figure
Anomalous physical properties of underdoped weak-ferromagnetic superconductor RuSrEuCuO
Similar to the optimal-doped, weak-ferromagnetic (WFM induced by canted
antiferromagnetism, T = 131 K) and superconducting (T = 56 K)
RuSrGdCuO, the underdoped RuSrEuCuO
(T = 133 K, T = 36 K) also exhibited a spontaneous vortex state
(SVS) between 16 K and 36 K. The low field (20 G) superconducting
hysteresis loop indicates a weak and narrow Meissner state region of average
lower critical field B(T) = B(0)[1 -
(T/T)], with B(0) = 7 G and T = 16 K. The
vortex melting transition (T = 21 K) below T obtained from
the broad resistivity drop and the onset of diamagnetic signal indicates a
vortex liquid region due to the coexistence and interplay between
superconductivity and WFM order. No visible jump in specific heat was observed
near T for Eu- and Gd-compound. This is not surprising, since the
electronic specific heat is easily overshadowed by the large phonon and
weak-ferromagnetic contributions. Furthermore, a broad resistivity transition
due to low vortex melting temperature would also lead to a correspondingly
reduced height of any specific heat jump. Finally, with the baseline from the
nonmagnetic Eu-compound, specific heat data analysis confirms the magnetic
entropy associated with antiferromagnetic ordering of Gd (J = S = 7/2)
at 2.5 K to be close to ln8 as expected.Comment: 7 figure
Design and Implementation of Monitoring Schemes for Software-Defined Routing over a Federated Multi-domain SDN Testbed
Emerging Software-Defined Networking (SDN) paradigm has been widely affecting most networking fields. However, the real-world SDN application for inter-domain routing management is still limited since the routing exchange among wide-area networks is quite complicate due to the extreme scale of global Internet connectivity. Several SDN-leveraged routing ideas are being proposed to improve the routing exchange among wide-area networks. Thus, in this paper, an on-going experience for experimenting and validating the inter-domain routing proposals over OF@TEIN federated testbed in Asia is shared. By focusing on the design and implementation of monitoring deployment for visibility support, we try to identify practical key points and provide improved monitoring for validating the performance and anomaly of the exchange. Other design considerations are also discussed together with possible future research directions
Advanced Glycation End Products Induce PeroxisomeProliferator-Activated Receptor c Down-Regulation-Related Inflammatory Signals in Human Chondrocytesvia Toll-Like Receptor-4 and Receptor for AdvancedGlycation End Products
Accumulation of advanced glycation end products (AGEs) in joints is important in the development of cartilage destruction and damage in age-related osteoarthritis (OA). The aim of this study was to investigate the roles of peroxisome proliferator-activated receptor γ (PPARγ), toll-like receptor 4 (TLR4), and receptor for AGEs (RAGE) in AGEs-induced inflammatory signalings in human OA chondrocytes. Human articular chondrocytes were isolated and cultured. The productions of metalloproteinase-13 and interleukin-6 were quantified using the specific ELISA kits. The expressions of related signaling proteins were determined by Western blotting. Our results showed that AGEs enhanced the productions of interleukin-6 and metalloproteinase-13 and the expressions of cyclooxygenase-2 and high-mobility group protein B1 and resulted in the reduction of collagen II expression in human OA chondrocytes. AGEs could also activate nuclear factor (NF)-κB activation. Stimulation of human OA chondrocytes with AGEs significantly induced the up-regulation of TLR4 and RAGE expressions and the down-regulation of PPARγ expression in a time- and concentration-dependent manner. Neutralizing antibodies of TLR4 and RAGE effectively reversed the AGEs-induced inflammatory signalings and PPARγ down-regulation. PPARγ agonist pioglitazone could also reverse the AGEs-increased inflammatory signalings. Specific inhibitors for p38 mitogen-activated protein kinases, c-Jun N-terminal kinase and NF-κB suppressed AGEs-induced PPARγ down-regulation and reduction of collagen II expression. Taken together, these findings suggest that AGEs induce PPARγ down-regulation-mediated inflammatory signalings and reduction of collagen II expression in human OA chondrocytes via TLR4 and RAGE, which may play a crucial role in the development of osteoarthritis pathogenesis induced by AGEs accumulation
Theory of Scanning Tunneling Spectroscopy of Magnetic Adatoms in Graphene
We examine theoretically the signatures of magnetic adatoms in graphene
probed by scanning tunneling spectroscopy (STS). When the adatom hybridizes
equally with the two graphene sublattices, the broadening of the local adatom
level is anomalous and can scale with the cube of the energy. In contrast to
ordinary metal surfaces, the adatom local moment can be suppressed by the
proximity of the probing scanning tip. We propose that the dependence of the
tunneling conductance on the distance between the tip and the adatom can
provide a clear signature for the presence of local magnetic moments. We also
show that tunneling conductance can distinguish whether the adatom is located
on top of a carbon atom or in the center of a honeycomb hexagon.Comment: 4.1 pages, 4 figure
The p53-dependent apoptotic pathway of breast cancer cells (BC-M1) induced by the bis-type bioreductive compound aziridinylnaphthoquinone
INTRODUCTION: Several aziridinylbenzoquinone drugs have undergone clinical trials as potential antitumor drugs. These bioreductive compounds are designed to kill cells preferentially within the hypoxia tumor microenvironment. The bioreductive compound of bis-type naphthoquinone synthesized in our laboratory, 2-aziridin-1-yl-3-[(2-{2-[(3-aziridin-1-yl-1,4-dioxo-1,4-dihydronaphthalen-2-yl)thio]ethoxy}ethyl)thio]naphthoquinone (AZ-1), had the most potent death effect on the breast cancer cells BC-M1 in our previous screening. In the present study, we determined that the mechanism of the death effect of BC-M1 cells induced by AZ-1 was mediated by the apoptosis pathway. METHODS: We evaluated the cytotoxicity of AZ-1 and the anti-breast cancer drugs tamoxifen and paclitaxel to BC-M1 cells and MCF-7 cells by the MTT assay and measured the apoptosis phenomena by Hoechst 33258 staining for apoptotic bodies. We also quantified the sub-G(1 )peak area and the ratio of the CH(2)/CH(3 )peak area of the cell membrane in BC-M1 cells by flow cytometry and (1)H-NMR spectra, respectively. The apoptosis-related protein expressions, including p53, p21, the RNA-relating protein T-cell restricted intracellular antigen-related protein, cyclin-dependent kinase 2 (cell cycle regulating kinase) and pro-caspase 3, were detected by western blot, and the caspase-3 enzyme activity was also quantified by an assay kit. RESULTS: AZ-1 induced two of the breast cancer cell lines, with IC(50 )= 0.51 μM in BC-M1 cells and with IC(50)= 0.57 μM in MCF-7 cells, and showed less cytotoxicity to normal fibroblast cells (skin fibroblasts) with IC(50)= 5.6 μM. There was a 10-fold difference between two breast cancer cell lines and normal fibroblasts. Of the two anti-breast cancer drugs, tamoxifen showed IC(50)= 0.12 μM to BC-M1 cells and paclitaxel had much less sensitivity than AZ-1. The expression of p53 protein increased from 0.5 to 1.0 μM AZ-1 and decreased at 2.0 μM AZ-1. The p21 protein increased from 0.5 μM AZ-1, with the highest at 2 μM AZ-1. Regarding the AZ-1 compound-induced BC-M1 cells mediating the apoptosis pathway, the apoptotic body formation, the sub-G(1 )peak area, the ratio of CH(2)/CH(3 )of phospholipids in the cell membrane and the enzyme activity of caspase-3 were all in direct proportion with the dose-dependent increase of the concentration of AZ-1. The death effect-related proteins, including T-cell restricted intracellular antigen-related protein, cyclin-dependent kinase 2, and pro-caspase-3, all dose-dependently decreased with AZ-1 concentration. CONCLUSIONS: The AZ-1-induced cell death of BC-M1 cells mediating the apoptosis pathway might be associated with p53 protein expression, and AZ-1 could have the chance to be a candidate drug for anti-breast cancer following more experimental evidence, such as animal models
Diagnosis of Polypoidal Choroidal Vasculopathy from Fluorescein Angiography Using Deep Learning
Purpose: To differentiate polypoidal choroidal vasculopathy (PCV) from choroidal neovascularization (CNV) and to determine the extent of PCV from fluorescein angiography (FA) using attention-based deep learning networks.
Methods: We build two deep learning networks for diagnosis of PCV using FA, one for detection and one for segmentation. Attention-gated convolutional neural network (AG-CNN) differentiates PCV from other types of wet age-related macular degeneration. Gradient-weighted class activation map (Grad-CAM) is generated to highlight important regions in the image for making the prediction, which offers explainability of the network. Attention-gated recurrent neural network (AG-PCVNet) for spatiotemporal prediction is applied for segmentation of PCV.
Results: AG-CNN is validated with a dataset containing 167 FA sequences of PCV and 70 FA sequences of CNV. AG-CNN achieves a classification accuracy of 82.80% at image-level, and 86.21% at patient-level for PCV. Grad-CAM shows that regions contributing to decision-making have on average 21.91% agreement with pathological regions identified by experts. AG-PCVNet is validated with 56 PCV sequences from the EVEREST-I study and achieves a balanced accuracy of 81.132% and dice score of 0.54.
Conclusions: The developed software provides a means of performing detection and segmentation of PCV on FA images for the first time. This study is a promising step in changing the diagnostic procedure of PCV and therefore improving the detection rate of PCV using FA alone.
Translational Relevance: The developed deep learning system enables early diagnosis of PCV using FA to assist the physician in choosing the best treatment for optimal visual prognosis
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