683 research outputs found
Parsec-scale jet properties of the gamma-ray quasar 3C 286
The quasar 3C~286 is one of two compact steep spectrum sources detected by
the {\it Fermi}/LAT. Here, we investigate the radio properties of the
parsec(pc)-scale jet and its (possible) association with the -ray
emission in 3C~286. The Very Long Baseline Interferometry (VLBI) images at
various frequencies reveal a one-sided core--jet structure extending to the
southwest at a projected distance of 1 kpc. The component at the jet base
showing an inverted spectrum is identified as the core, with a mean brightness
temperature of ~K. The jet bends at about 600 pc (in
projection) away from the core, from a position angle of to
. Based on the available VLBI data, we inferred the proper motion
speed of the inner jet as mas yr (), corresponding to a jet speed of about at an inclination
angle of between the jet and the line of sight of the observer. The
brightness temperature, jet speed and Lorentz factor are much lower than those
of -ray-emitting blazars, implying that the pc-scale jet in 3C~286 is
mildly relativistic. Unlike blazars in which -ray emission is in
general thought to originate from the beamed innermost jet, the location and
mechanism of -ray emission in 3C~286 may be different as indicated by
the current radio data. Multi-band spectrum fitting may offer a complementary
diagnostic clue of the -ray production mechanism in this source.Comment: 9 pages, 4 figures, accept for publication in MNRA
Carbon inequality and economic development across the Belt and Road regions
Given the aim of maintaining global warming below 2Β Β°C, carbon emission reduction has become a global top priority. Since the Belt and Road Initiative has increasing influence on manufacturing-oriented developing countries, more attention should be paid to carbon emission reduction in these regions. This study conducts a comprehensive analysis by analyzing the carbon inequality and regional development and compares the carbon emissions driven by final demand among countries in and outside the Belt and Road area from 1990 to 2015. It is found that the majority of the Belt and Road regions achieved a rapid GDP growth rate with increasing carbon emissions, in which the investment-driven type demonstrated a significant growth. In contrast, the developed countries outside the Belt and Road area maintained their economic growth while decreasing the carbon emissions owed to the declining of investment-driven emissions; however the consumption-driven emissions stably remained a relatively high level. Our results showed that the inequality of carbon emission within Belt and Road regions is lower than the global average, while the inequality of the investment-driven emissions showed an obviously increasing trend. By discussing the carbon inequality and regional development, rational and feasible strategies for countries and regions within and outside the Belt and Road area are essential, and different types of strategies such as low-carbon technologies transfers and overseas financial cooperation are suggested for regional carbon emission reduction and sustainable regional development under the Belt and Road Initiative
Probing structural relaxation in complex fluids by critical fluctuations
Complex fluids, such as polymer solutions and blends, colloids and gels, are
of growing interest in fundamental and applied soft-condensed-matter science. A
common feature of all such systems is the presence of a mesoscopic structural
length scale intermediate between atomic and macroscopic scales. This
mesoscopic structure of complex fluids is often fragile and sensitive to
external perturbations. Complex fluids are frequently viscoelastic (showing a
combination of viscous and elastic behaviour) with their dynamic response
depending on the time and length scales. Recently, non-invasive methods to
infer the rheological response of complex fluids have gained popularity through
the technique of microrheology, where the diffusion of probe spheres in a
viscoelastic fluid is monitored with the aid of light scattering or microscopy.
Here we propose an alternative to traditional microrheology that does not
require doping of probe particles in the fluid (which can sometimes drastically
alter the molecular environment). Instead, our proposed method makes use of the
phenomenon of "avoided crossing" between modes associated with the structural
relaxation and critical fluctuations that are spontaneously generated in the
system.Comment: 4 pages, 4 figure
Compact Bright Radio-loud AGNs. III. A Large VLBA Survey at 43 GHz
We present the results from the 43 GHz Very Long Baseline Array (VLBA) observations of 124 compact radio-loud active galactic nuclei (AGNs) that were conducted between 2014 November and 2016 May. The typical dimensions of the restoring beam in each image are about 0.5 mas x 0.2 mas. The highest resolution of 0.2 mas corresponds to a physical size of 0.02 pc for the lowest redshift source in the sample. The 43 GHz very long baseline interferometry (VLBI) images of 97 AGNs are presented for the first time. We study the source compactness on milliarcsecond and submilliarcsecond scales, and suggest that 95 sources in our sample are suitable for future space VLBI observations. By analyzing our data supplemented with other VLBA AGN surveys from the literature, we find that the core brightness temperature increases with increasing frequency below a break frequency similar to 7 GHz, and decreases between similar to 7 and 240 GHz but increases again above 240 GHz in the rest frame of the sources. This indicates that the synchrotron opacity changes from optically thick to thin. We also find a strong statistical correlation between radio and gamma-ray flux densities. Our correlation is tighter than those in the literature derived from lower-frequency VLBI data, suggesting that the gamma-ray emission is produced more cospatially with the 43 GHz VLBA core emission. This correlation can also be extrapolated to the unbeamed AGN population, implying that a universal gamma-ray production mechanism might be at work for all types of AGNs
Hidden attractors in fundamental problems and engineering models
Recently a concept of self-excited and hidden attractors was suggested: an
attractor is called a self-excited attractor if its basin of attraction
overlaps with neighborhood of an equilibrium, otherwise it is called a hidden
attractor. For example, hidden attractors are attractors in systems with no
equilibria or with only one stable equilibrium (a special case of
multistability and coexistence of attractors). While coexisting self-excited
attractors can be found using the standard computational procedure, there is no
standard way of predicting the existence or coexistence of hidden attractors in
a system. In this plenary survey lecture the concept of self-excited and hidden
attractors is discussed, and various corresponding examples of self-excited and
hidden attractors are considered
Status update of the Power Conditioning System in the National Ignition Facility
Abstract not provide
The Genomic Analysis of Erythrocyte microRNA Expression in Sickle Cell Diseases
BACKGROUND: Since mature erythrocytes are terminally differentiated cells without nuclei and organelles, it is commonly thought that they do not contain nucleic acids. In this study, we have re-examined this issue by analyzing the transcriptome of a purified population of human mature erythrocytes from individuals with normal hemoglobin (HbAA) and homozygous sickle cell disease (HbSS). METHODS AND FINDINGS: Using a combination of microarray analysis, real-time RT-PCR and Northern blots, we found that mature erythrocytes, while lacking ribosomal and large-sized RNAs, contain abundant and diverse microRNAs. MicroRNA expression of erythrocytes was different from that of reticulocytes and leukocytes, and contributed the majority of the microRNA expression in whole blood. When we used microRNA microarrays to analyze erythrocytes from HbAA and HbSS individuals, we noted a dramatic difference in their microRNA expression pattern. We found that miR-320 played an important role for the down-regulation of its target gene, CD71 during reticulocyte terminal differentiation. Further investigation revealed that poor expression of miR-320 in HbSS cells was associated with their defective downregulation CD71 during terminal differentiation. CONCLUSIONS: In summary, we have discovered significant microRNA expression in human mature erythrocytes, which is dramatically altered in HbSS erythrocytes and their defect in terminal differentiation. Thus, the global analysis of microRNA expression in circulating erythrocytes can provide mechanistic insights into the disease phenotypes of erythrocyte diseases
Parametric Study on Dimensional Control of ZnO Nanowalls and Nanowires by Electrochemical Deposition
A simple electrochemical deposition technique is used to synthesize both two-dimensional (nanowall) and one-dimensional (nanowire) ZnO nanostructures on indium-tin-oxide-coated glass substrates at 70Β°C. By fine-tuning the deposition conditions, particularly the initial Zn(NO3)2Β·6H2O electrolyte concentration, the mean ledge thickness of the nanowalls (50β100 nm) and the average diameter of the nanowires (50β120 nm) can be easily varied. The KCl supporting electrolyte used in the electrodeposition also has a pronounced effect on the formation of the nanowalls, due to the adsorption of Clβ ions on the preferred (0001) growth plane of ZnO and thereby redirecting growth on the (100) and (20) planes. Furthermore, evolution from the formation of ZnO nanowalls to formation of nanowires is observed as the KCl concentration is reduced in the electrolyte. The crystalline properties and growth directions of the as-synthesized ZnO nanostructures are studied in details by glancing-incidence X-ray diffraction and transmission electron microscopy
The diminishing socioeconomic disparity in obesity in a Chinese population with rapid economic development: analysis of serial cross-sectional health survey data 2002β2010
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