1,572 research outputs found
A tracking algorithm of infrared sequence based on multi-model integration
2014-2015 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
Investigating properties of the cardiovascular system using innovative analysis algorithms based on ensemble empirical mode decomposition
This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited - Copyright @ 2012 Jia-Rong Yeh et al.Cardiovascular system is known to be nonlinear and nonstationary. Traditional linear assessments algorithms of arterial stiffness and systemic resistance of cardiac system accompany the problem of nonstationary or inconvenience in practical applications. In this pilot study, two new assessment methods were developed: the first is ensemble empirical mode decomposition based reflection index (EEMD-RI) while the second is based on the phase shift between ECG and BP on cardiac oscillation. Both methods utilise the EEMD algorithm which is suitable for nonlinear and nonstationary systems. These methods were used to investigate the properties of arterial stiffness and systemic resistance for a pig's cardiovascular system via ECG and blood pressure (BP). This experiment simulated a sequence of continuous changes of blood pressure arising from steady condition to high blood pressure by clamping the artery and an inverse by relaxing the artery. As a hypothesis, the arterial stiffness and systemic resistance should vary with the blood pressure due to clamping and relaxing the artery. The results show statistically significant correlations between BP, EEMD-based RI, and the phase shift between ECG and BP on cardiac oscillation. The two assessments results demonstrate the merits of the EEMD for signal analysis.This work is supported by the National Science Council (NSC) of Taiwan (Grant number NSC 99-2221-E-155-046-MY3), Centre for Dynamical Biomarkers and Translational Medicine, National Central University,
Taiwan which is sponsored by National Science Council (Grant number: NSC 100–2911-I-008-001) and the Chung-Shan Institute of Science & Technology in Taiwan (Grant numbers: CSIST-095-V101 and CSIST-095-V102)
Research on the optimal path algorithm in multi-level road network
2006-2007 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
Quantum fluctuations in high field magnetization of 2D square lattice J1-J2 antiferromagnets
The J1-J2 square lattice Heisenberg model with spin S=1/2 has three phases
with long-range magnetic order and two unconventionally ordered phases
depending on the ratio of exchange constants. It describes a number of recently
found layered vanadium oxide compounds. A simple means of investigating the
ground state is the study of the magnetization curve and high-field
susceptibility. We discuss these quantities by using the spin-wave theory and
the exact diagonalization in the whole J1-J2 plane. We compare both results and
find good overall agreement in the sectors of the phase diagram with magnetic
order. Close to the disordered regions the magnetization curve shows strong
deviations from the classical linear behaviour caused by large quantum
fluctuations and spin-wave approximation breaks down. On the FM side (J1<0)
where one approaches the quantum gapless spin nematic ground state this region
is surprisingly large. We find that inclusion of second order spin-wave
corrections does not lead to fundamental improvement. Quantum corrections to
the tilting angle of the ordered moments are also calculated. They may have
both signs, contrary to the always negative first order quantum corrections to
the magnetization. Finally we investigate the effect of the interlayer coupling
and find that the quasi-2D picture remains valid up to |J_\perp/J1| ~ 0.3.Comment: 13 pages, 6figure
Kinetic frustration and the nature of the magnetic and paramagnetic states in iron pnictides and iron chalcogenides
The iron pnictide and chalcogenide compounds are a subject of intensive
investigations due to their high temperature superconductivity.\cite{a-LaFeAsO}
They all share the same structure, but there is significant variation in their
physical properties, such as magnetic ordered moments, effective masses,
superconducting gaps and T. Many theoretical techniques have been applied
to individual compounds but no consistent description of the trends is
available \cite{np-review}. We carry out a comparative theoretical study of a
large number of iron-based compounds in both their magnetic and paramagnetic
states. We show that the nature of both states is well described by our method
and the trends in all the calculated physical properties such as the ordered
moments, effective masses and Fermi surfaces are in good agreement with
experiments across the compounds. The variation of these properties can be
traced to variations in the key structural parameters, rather than changes in
the screening of the Coulomb interactions. Our results provide a natural
explanation of the strongly Fermi surface dependent superconducting gaps
observed in experiments\cite{Ding}. We propose a specific optimization of the
crystal structure to look for higher T superconductors.Comment: 5 pages, 3 figures with a 5-page supplementary materia
Correlation between expression of DcR3 on tumor cells and sensitivity to FasL
To investigate the correlation between sensitivity to Fas ligand (FasL) and expression level of decoy receptor 3 (DcR3) on tumor cell surface, Fas/DcR3 mRNA expression was detected by RT-PCR. Anti-DcR3 mAb was used to detect expression level of DcR3 on surface of tumor cells by flow cytometry. Caspase-8, caspase-9, caspase-3, Bcl-2 expressions were analyzed by Western blot, respectively. Sensitivity to apoptosis induced by FasL was determined by Annexin V apoptosis kit. The expressions of DcR3 on the surface of tumor cells from high to low were approximately 35.3% in BGC823 cells, and 21.6% in MCF-7 cells, respectively. The apoptotic rates induced by FasL from low to high were 15.6% in BGC823 cells, and 58.2% in MCF-7 cells, respectively. There was a significant correlation between the expression levels of DcR3 with FasL-inducing apoptosis
Magnetism and Charge Dynamics in Iron Pnictides
In a wide variety of materials, such as copper oxides, heavy fermions,
organic salts, and the recently discovered iron pnictides, superconductivity is
found in close proximity to a magnetically ordered state. The character of the
proximate magnetic phase is thus believed to be crucial for understanding the
differences between the various families of unconventional superconductors and
the mechanism of superconductivity. Unlike the AFM order in cuprates, the
nature of the magnetism and of the underlying electronic state in the iron
pnictide superconductors is not well understood. Neither density functional
theory nor models based on atomic physics and superexchange, account for the
small size of the magnetic moment. Many low energy probes such as transport,
STM and ARPES measured strong anisotropy of the electronic states akin to the
nematic order in a liquid crystal, but there is no consensus on its physical
origin, and a three dimensional picture of electronic states and its relations
to the optical conductivity in the magnetic state is lacking. Using a first
principles approach, we obtained the experimentally observed magnetic moment,
optical conductivity, and the anisotropy of the electronic states. The theory
connects ARPES, which measures one particle electronic states, optical
spectroscopy, probing the particle hole excitations of the solid and neutron
scattering which measures the magnetic moment. We predict a manifestation of
the anisotropy in the optical conductivity, and we show that the magnetic phase
arises from the paramagnetic phase by a large gain of the Hund's rule coupling
energy and a smaller loss of kinetic energy, indicating that iron pnictides
represent a new class of compounds where the nature of magnetism is
intermediate between the spin density wave of almost independent particles, and
the antiferromagnetic state of local moments.Comment: 4+ pages with additional one-page supplementary materia
Postnatal expression of myostain (MSTN) and myogenin (MYoG) genes in Hu sheep of China
The study of candidate genes is an important tool to identify genes associated with economic traits. Skeletal muscle development is an important physiological process in meat animals, and it directly affects meat production. The expression of myostain (MSTN) and myogenin (MYoG) genes in longissimus dorsi, during the early growth stage of Hu sheep, was studied by semi-quantitative Reverse transcription polymerase chain reaction (RT-PCR). The results demonstrate that age and gender were playing a very important role in the expression of sheep muscle. MSTN and MYOG genes showed similar variation pattern for the male and female. The expression level of the MSTN and MYoG genes all showed a positive correlation with live weight, carcass weight and meat percentage, but only showed a significant relationship with meat percentage. MSTN gene showed an extreme significant positive relationship with MYoG.Key words: Sheep, myostain (MSTN), myogenin (MYoG), gene expression, muscle trait
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