12,417 research outputs found
On the Polarization of H-alpha Lines Scattered by Neutral Hydrogen in Active Galactic Nuclei
Raman scattering by atomic hydrogen converts the UV continuum around
Ly into optical continuum around H, and the basic atomic physics
has been discussed in several works on symbiotic stars. We propose that the
same process may operate in active galactic nuclei (AGN) and calculate the
linear polarization of the broad emission lines Raman-scattered by a high
column neutral hydrogen compnent. The conversion efficiency of the Raman
scattering process is discussed and the expected scattered flux is computed
using the spectral energy distribution of an AGN given by a typical power law.
The high column H {\sc i} component in AGN is suggested by many observations
encompassing radio through UV and X-ray ranges. When the neutral hydrogen
component with a column density is present around the
active nucleus, it is found that the scattered H is characterized by a
very broad width and that the strength of the polarized flux
is comparable to that of the electron-scattered flux expected from a
conventional unified model of narrow line AGN. The width of the scattered flux
is mainly determined by the column density of the neutral scatterers where the
total scattering optical depth becomes of order unity. The asymmetry in the
Raman scattering cross section around Ly introduces red asymmetric
polarized profiles around H. The effects of the blended Ly and O
{\sc vi} 1034 doublet are also investigated. We briefly discuss the
spectropolarimetric observations performed on the Seyfert galaxy IRAS
110548-1131 and the narrow line radio galaxy Cyg A.Comment: 11 pages, 6 figures, accepted for publication in MNRA
Voltage Scaling of Graphene Device on SrTiO3 Epitaxial Thin Film
Electrical transport in monolayer graphene on SrTiO3 (STO) thin film is
examined in order to promote gate-voltage scaling using a high-k dielectric
material. The atomically flat surface of thin STO layer epitaxially grown on
Nb-doped STO single-crystal substrate offers good adhesion between the high-k
film and graphene, resulting in nonhysteretic conductance as a function of gate
voltage at all temperatures down to 2 K. The two-terminal conductance
quantization under magnetic fields corresponding to quantum Hall states
survives up to 200 K at a magnetic field of 14 T. In addition, the substantial
shift of charge neutrality point in graphene seems to correlate with the
temperature-dependent dielectric constant of the STO thin film, and its
effective dielectric properties could be deduced from the universality of
quantum phenomena in graphene. Our experimental data prove that the operating
voltage reduction can be successfully realized due to the underlying high-k STO
thin film, without any noticeable degradation of graphene device performance.Comment: 12 pages, 9 figures (5 figures + 4 figures on supp.) in Nano Letters
(2016
Breakdown of the interlayer coherence in twisted bilayer graphene
Coherent motion of the electrons in the Bloch states is one of the
fundamental concepts of the charge conduction in solid state physics. In
layered materials, however, such a condition often breaks down for the
interlayer conduction, when the interlayer coupling is significantly reduced by
e.g. large interlayer separation. We report that complete suppression of
coherent conduction is realized even in an atomic length scale of layer
separation in twisted bilayer graphene. The interlayer resistivity of twisted
bilayer graphene is much higher than the c-axis resistivity of Bernal-stacked
graphite, and exhibits strong dependence on temperature as well as on external
electric fields. These results suggest that the graphene layers are
significantly decoupled by rotation and incoherent conduction is a main
transport channel between the layers of twisted bilayer graphene.Comment: 5 pages, 3 figure
A synthetic approach to a fullerene-rich dendron and its linear polymer via ring-opening metathesis polymerization
Through the esterification of an acyl chloride functionalized fullerene precursor with dendritic alcohol, a fullerene-rich dendron containing a norbornene unit at the focal point is prepared for ring-opening metathesis polymerization to obtain its linear polymer with a unimodal and narrow molar mass distribution (PDI = 1.08) by a progressive addition of catalysts.close181
Input of terrestrial organic matter linked to deglaciation increased mercury transport to the Svalbard fjords
Deglaciation has accelerated the transport of minerals as well as modern and ancient organic matter from land to fjord sediments in Spitsbergen, Svalbard, in the European Arctic Ocean. Consequently, such sediments may contain significant levels of total mercury (THg) bound to terrestrial organic matter. The present study compared THg contents in surface sediments from three fjord settings in Spitsbergen: Hornsund in the southern Spitsbergen, which has high annual volume of loss glacier and receives sediment from multiple tidewater glaciers, Dicksonfjorden in the central Spitsbergen, which receives sediment from glacifluvial rivers, and Wijdefjorden in the northern Spitsbergen, which receive sediments from a mixture of tidewater glaciers and glacifluvial rivers. Our results showed that the THg (52 +/- 15 ng g(-1)) bound to organic matter (OM) was the highest in the Hornsund surface sediments, where the glacier loss (0.44 km(3) yr(-1)) and organic carbon accumulation rates (9.3 similar to 49.4 g m(-2) yr(-1)) were elevated compared to other fjords. Furthermore, the delta C-13 (-27 similar to -24 parts per thousand) and delta S-34 values (-10 similar to 15 parts per thousand) of OM indicated that most of OM were originated from terrestrial sources. Thus, the temperature-driven glacial melting could release more OM originating from the meltwater or terrestrial materials, which are available for THg binding in the European Arctic fjord ecosystems.11Ysciescopu
Biopsychological traits of Sasang typology based on Sasang personality questionnaire and body mass index
BACKGROUND: The purpose of present study was to examine biological and psychological characteristics of people according to the Sasang typology, which is popular in Korea. We evaluated the Sasang Personality Questionnaire (SPQ) as a measure of temperament, and Body Mass Index (BMI) as a measure of the somatic properties of each Sasang type. METHODS: Subjects were 2506 (877 males, 1629 females) outpatients between the ages of 20 through 70 who requested traditional medical assessment and treatment in Korea. The structural validity of the SPQ was examined and its correlation with BMI was analyzed. The SPQ and BMI measures of each Sasang type across age and gender were presented and their differences were analyzed with Analysis of Variance. RESULTS: Confirmatory factor analysis and path analysis identified an acceptable three-factor structure of the SPQ measuring differences in individual’s behavior, emotion, and cognition. SPQ scores (29.71 ± 1.00, 28.29 ± 0.19 and 26.14 ± 0.22) and BMI scores (22.92 ± 0.09, 25.56 ± 0.10 and 21.44 ± 0.10) were significantly (p < 0.001) different among So-Yang, Tae-Eum and So-Eum Sasang types, respectively. CONCLUSIONS: The results showed that the SPQ and BMI is a reliable measure for quantifying the biopsychological characteristics of each types, and useful for guiding personalized and type-specific treatment with medical herbs and acupuncture
Renal transplantation in a patient with Bartter syndrome and glomerulosclerosis
Bartter syndrome (BS) is a clinically and genetically heterogeneous inherited renal tube disorder characterized by renal salt wasting, hypokalemic metabolic alkalosis and normotensive hyperreninemic hyperaldosteronism. There have been several case reports of BS complicated by focal segmental glomerulosclerosis (FSGS). Here, we have reported the case of a BS patient who developed FSGS and subsequent end-stage renal disease (ESRD) and provided a brief literature review. The patient presented with classic BS at 3 months of age and developed proteinuria at 7 years. Renal biopsy performed at 11 years of age revealed a FSGS perihilar variant. Hemodialysis was initiated at 11 years of age, and kidney transplantation was performed at 16 years of age. The post-transplantation course has been uneventful for more than 3 years with complete disappearance of BS without the recurrence of FSGS. Genetic study revealed a homozygous p.Trp(TGG)610Stop(TGA) mutation in the CLCNKB gene. In summary, BS may be complicated by secondary FSGS due to the adaptive response to chronic salt-losing nephropathy, and FSGS may progress to ESRD in some patients. Renal transplantation in patients with BS and ESRD results in complete remission of BS
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