The experiment on a Ku-band gyrotron backward- wave oscillator (gyro-BWO) with a single depressed collector and linear polarization mode output has been performed successfully. Stable magnetic tuning ...bandwidth of 5% and maximum power of 48 kW under a 40-kV 11.5-A electron beam were achieved. The overall efficiency of the gyro-BWO with a single stage depressed collector has been enhanced from 10.5% to 21%. The measured performance has demonstrated a strong potential of the gyro-BWO for new application requiring high-power tunable wave source.
Study of χcJ radiative decays into a vector meson An, L.; An, Q.; Baldini, R. ...
Physical review. D, Particles, fields, gravitation, and cosmology,
06/2011, Letnik:
83, Številka:
11
Journal Article
The combination of nontrivial band topology and symmetry-breaking phases gives rise to novel quantum states and phenomena such as topological superconductivity, quantum anomalous Hall effect, and ...axion electrodynamics. Evidence of intertwined charge density wave (CDW) and superconducting order parameters has recently been observed in a novel kagome material AV_{3}Sb_{5} (A=K, Rb, Cs) that features a Z_{2} topological invariant in the electronic structure. However, the origin of the CDW and its intricate interplay with the topological state has yet to be determined. Here, using hard-x-ray scattering, we demonstrate a three-dimensional CDW with 2×2×2 superstructure in (Rb,Cs)V_{3}Sb_{5}. Unexpectedly, we find that the CDW fails to induce acoustic phonon anomalies at the CDW wave vector but yields a novel Raman mode that quickly damps into a broad continuum below the CDW transition temperature. Our observations exclude strong electron-phonon-coupling-driven CDW in AV_{3}Sb_{5} and support an unconventional CDW that was proposed in the kagome lattice at van Hove filling.
The class B glucagon-like peptide-1 (GLP-1) G protein-coupled receptor is a major target for the treatment of type 2 diabetes and obesity. Endogenous and mimetic GLP-1 peptides exhibit biased ...agonism-a difference in functional selectivity-that may provide improved therapeutic outcomes. Here we describe the structure of the human GLP-1 receptor in complex with the G protein-biased peptide exendin-P5 and a Gα
heterotrimer, determined at a global resolution of 3.3 Å. At the extracellular surface, the organization of extracellular loop 3 and proximal transmembrane segments differs between our exendin-P5-bound structure and previous GLP-1-bound GLP-1 receptor structure. At the intracellular face, there was a six-degree difference in the angle of the Gαs-α5 helix engagement between structures, which was propagated across the G protein heterotrimer. In addition, the structures differed in the rate and extent of conformational reorganization of the Gα
protein. Our structure provides insights into the molecular basis of biased agonism.
The validity of using the weighted information entropy to estimate the complex degree of the infrared images’ backgrounds is discussed in this paper. A Butterworth high pass filter whose cut-off ...frequency can be adaptively regulated to meet the different backgrounds is proposed to restrain the different clutters. Since the backgrounds usually have some random change in the video sequences, an adaptive binarisation criterion for small target detection is also presented. Experimental results show the robustness of our method.
We describe an isothermal, single-reaction method for assembling multiple overlapping DNA molecules by the concerted action of a 5′ exonuclease, a DNA polymerase and a DNA ligase. First we recessed ...DNA fragments, yielding single-stranded DNA overhangs that specifically annealed, and then covalently joined them. This assembly method can be used to seamlessly construct synthetic and natural genes, genetic pathways and entire genomes, and could be a useful molecular engineering tool.
We present a comprehensive simulation of tropospheric chlorine
within the GEOS-Chem global 3-D model of oxidant–aerosol–halogen atmospheric
chemistry. The simulation includes explicit accounting of ...chloride
mobilization from sea salt aerosol by acid displacement of HCl and by other
heterogeneous processes. Additional small sources of tropospheric chlorine
(combustion, organochlorines, transport from stratosphere) are also included.
Reactive gas-phase chlorine Cl*, including Cl, ClO, Cl2, BrCl, ICl,
HOCl, ClNO3, ClNO2, and minor species, is produced by the
HCl+OH reaction and by heterogeneous conversion of sea salt aerosol
chloride to BrCl, ClNO2, Cl2, and ICl. The model
successfully simulates the observed mixing ratios of HCl in marine air
(highest at northern midlatitudes) and the associated HNO3
decrease from acid displacement. It captures the high ClNO2 mixing
ratios observed in continental surface air at night and attributes the
chlorine to HCl volatilized from sea salt aerosol and transported inland
following uptake by fine aerosol. The model successfully simulates the
vertical profiles of HCl measured from aircraft, where enhancements in the
continental boundary layer can again be largely explained by transport inland
of the marine source. It does not reproduce the boundary layer Cl2
mixing ratios measured in the WINTER aircraft campaign (1–5 ppt in the
daytime, low at night); the model is too high at night, which could be due to
uncertainty in the rate of the ClNO2+Cl- reaction, but we have
no explanation for the high observed Cl2 in daytime. The global
mean tropospheric concentration of Cl atoms in the model is 620 cm−3
and contributes 1.0 % of the global oxidation of methane, 20 % of
ethane, 14 % of propane, and 4 % of methanol. Chlorine chemistry
increases global mean tropospheric BrO by 85 %, mainly through the
HOBr+Cl- reaction, and decreases global burdens of tropospheric
ozone by 7 % and OH by 3 % through the associated bromine radical
chemistry. ClNO2 chemistry drives increases in ozone of up to
8 ppb over polluted continents in winter.
The pattern of constitutive and cycle-dependent integrins in normal endometrium has recently been established, suggesting a role for cell adhesion molecules in endometrial receptivity and ...implantation. Currently few, if any, models exist for the study of human endometrial integrins and their role in establishment of the receptive endometrial phenotype. The Ishikawa cell line maintains functional estrogen receptors and progesterone receptors. The progesterone receptors in these cells are inducible by priming with estradiol and down-regulated by treatment with progesterone. In the present study the pattern of integrin expression in this well differentiated endometrial cell line is compared to that in normal endometrial epithelium using immunohistochemistry and flow cytometry and is confirmed by immunoprecipitation, Western immunoblot, and PCR. Like normal endometrial epithelium, Ishikawa cells maintain constitutive expression of alpha 2 beta 1, alpha 3 beta 1, alpha 6 beta 4. PCR demonstrates the expected size fragments of each, although evidence for alternatively spliced forms of the alpha 2-subunit was noted. Progesterone treatment of estradiol-primed cells resulted in increased expression of the alpha 1 beta 1 collagen-laminin receptor and suppression of the alpha v beta 3 vitronectin receptor, two of the cycle-dependent integrins expressed by normal endometrial epithelium. These data support the use of Ishikawa cells as an excellent model to study the regulation endometrial integrins and advance our understanding of hormonally mediated events surrounding implantation.
Background. Vulvovaginal candidosis (VVC), which is most frequently caused by Candida albicans, is one of the most common vaginal infections and is a common problem worldwide. Despite the fact that ...extensive epidemiological studies have been performed, what triggers VVC, especially recurrence of the infection, is still uncertain. Methods. Genotypes of C. albicans strains associated with VVC and balanoposthitis and of strains isolated from samples from vaginas of asymptomatic women and from various extragenital sites were determined with use of C. albicans microsatellite locus I polymorphism analysis. Genetic similarity of representative strains with the same and different C. albicans microsatellite locus I genotypes were examined by sequence analysis of housekeeping genes CaADP1, CaSYA1, and CaVPS13. Results. The C. albicans microsatellite locus I genotypes of independent C. albicans strains isolated from samples from extragenital sites were mostly of individual specificity. In contrast, strains associated with VVC were mainly concentrated to a few genotypes, with genotypes 30-45 and 32-46 being the most common. The overall frequencies of the 2 genotypes among C. albicans strains from vaginal samples from patients with VVC and from asymptomatic women were 59.1% and 24.0%, respectively (P = .002); the frequencies among patients with complicated VVC and among patients with uncomplicated VVC were 69.2% and 35.7%, respectively (P = .003). A similar genotype distribution pattern of C. albicans strains associated with balanoposthitis was also revealed. The genetic similarity of strains with the dominant genotypes associated with both VVC and balanoposthitis was confirmed by sequence analysis of the 3 genes. Conclusions. The results suggest the existence of vaginopathic C. albicans strains with enhanced virulence and tropism for the vagina and the high possibility of sexual transmission of genital C. albicans infection. Identification of specific genotypes that correlate with severity of VVC is also of diagnostic and therapeutic significance.
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