5,059 research outputs found
Gaussian-shaped Optical Frequency Comb Generation for Microwave Photonic Filtering
Using only electro-optic modulators, we generate a 41-line 10-GHz
Gaussian-shaped optical frequency comb. We use this comb to demonstrate
apodized microwave photonic filters with greater than 43-dB sidelobe
suppression without the need for a pulse shaper.Comment: 3 pages, 4 figure
Scalar form-factor of the proton with light-cone QCD sum rules
In this article, we calculate the scalar form-factor of the proton in the
framework of the light-cone QCD sum rules approach with the three valence quark
light-cone distribution amplitudes up to twist-6, and observe the scalar
form-factor at intermediate and large momentum transfers has significant contributions from the end-point (or soft) terms. The
numerical values for the are compatible with the calculations
from the chiral quark model and lattice QCD at the region .Comment: 18 pages, 7 figures, revised versio
Lipid raft/caveolae signaling is required for Cryptococcus neoformans invasion into human brain microvascular endothelial cells
<p>Abstract</p> <p>Background</p> <p><it>Cryptococcus neoformans </it>has a predilection for central nervous system infection. <it>C. neoformans </it>traversal of the blood brain barrier, composed of human brain microvascular endothelial cells (HBMEC), is the crucial step in brain infection. However, the molecular mechanism of the interaction between <it>Cryptococcus neoformans </it>and HBMEC, relevant to its brain invasion, is still largely unknown.</p> <p>Methods</p> <p>In this report, we explored several cellular and molecular events involving the membrane lipid rafts and caveolin-1 (Cav1) of HBMEC during <it>C. neoformans </it>infection. Immunofluorescence microscopy was used to examine the roles of Cav1. The knockdown of Cav1 by the siRNA treatment was performed. Phosphorylation of Cav1 relevant to its invasion functions was investigated.</p> <p>Results</p> <p>We found that the host receptor CD44 colocalized with Cav1 on the plasma membrane, and knockdown of Cav1 significantly reduced the fungal ability to invade HBMEC. Although the CD44 molecules were still present, HBMEC membrane organization was distorted by Cav1 knockdown. Concomitantly, knockdown of Cav1 significantly reduced the fungal crossing of the HBMEC monolayer <it>in vitro</it>. Upon <it>C. neoformans </it>engagement, host Cav1 was phosphorylated in a CD44-dependent manner. This phosphorylation was diminished by filipin, a disrupter of lipid raft structure. Furthermore, the phosphorylated Cav1 at the lipid raft migrated inward to the perinuclear localization. Interestingly, the phospho-Cav1 formed a thread-like structure and colocalized with actin filaments but not with the microtubule network.</p> <p>Conclusion</p> <p>These data support that <it>C. neoformans </it>internalization into HBMEC is a lipid raft/caveolae-dependent endocytic process where the actin cytoskeleton is involved, and the Cav1 plays an essential role in <it>C. neoformans </it>traversal of the blood-brain barrier.</p
Decay width of the pentaquark state with QCD sum rules
In this article, we take the point of view that the pentaquark state
has negative parity, and choose the diquark-triquark type
interpolating current to calculate the strong coupling constant
in the QCD sum rule approach. Our numerical results indicate the values of the
strong coupling constant are very small, , and the width , which can explain the
narrow width naturally.Comment: 10 pages, 2 figures, Third version, to appear in Phys.Rev.
Electromagnetic wave absorbing properties and hyperfine interactions of Fe-Cu-Nb-Si-B nanocomposites
The Fe–Cu–Nb–Si–B alloy nanocomposite containing two ferromagnetic phases (amorphous phase and nanophase phase) is obtained by properly annealing the as-prepared alloys. High resolution transmission electron microscopy (HRTEM) images show the coexistence of these two phases. It is found that Fe–Si nanograins are surrounded by the retained amorphous ferromagnetic phase. Mossbauer spectroscopy measurements show that the nanophase is the D03-type Fe– Si phase, which is employed to find the atomic fractions of resonant 57Fe atoms in these two phases. The microwave permittivity and permeability spectra of Fe–Cu–Nb–Si–B nanocomposite are measured in the frequency range of 0.5 GHz– 10 GHz. Large relative microwave permeability values are obtained. The results show that the absorber containing the nanocomposite flakes with a volume fraction of 28.59% exhibits good microwave absorption properties. The reflection loss of the absorber is less than −10 dB in a frequency band of 1.93 GHz–3.20 GHz
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Thin liquid water clouds: their importance and our challenge
Many clouds important to the Earth’s energy balance contain small amounts of liquid water, yet despite many improvements, large differences in retrievals of their liquid water amount and particle size still must be resolved
Magnetic moment of the pentaquark with light-cone QCD sum rules
In this article, we study the magnetic moment of the pentaquark state as diquark-diquark-antiquark () state in the
framework of the light-cone QCD sum rules approach. The numerical results
indicate the magnetic moment of the pentaquark state is about
.Comment: 10 pages, 1 figure. The main contents of this article is included in
hep-ph/0503007, this article will not be submitted to a journal for
publicatio
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