96 research outputs found
Is the Market Smart Enough to Identify Superior Analysts and Follow their Recommendations?
In this article we investigate whether there is persistency in analysts forecasting ability and if it exists, whether the market has the ability to identify these differences in abilities. Our results reveal that the forecasting ability of analysts is persistent. We then investigate whether investors identify superior analysts’ ability by analyzing market reaction to their recommendations compared to the reaction to other analysts. Our findings suggest that the twoday returns after the analysts’ reports’ are strongly positively correlated with analysts’ recommendations and there is a significant difference in reaction between high and low quality analysts. We conclude that the market is smart enough to identify different types of analysts and follow their recommendations respectively
Charge-Density Wave in Overdoped Cuprates Driven by Electron-Phonon Couplings
Recent resonant x-ray scattering (RXS) experiments revealed a novel charge
order in highly overdoped LaSrCuO (LSCO). The observed charge
order appears around the wavevector and remains robust from
cryogenic temperatures to room temperature. To investigate the origin of this
charge order in the overdoped region, we use determinant quantum Monte Carlo
(DQMC) simulations to examine models with various interactions. We demonstrate
that this CDW originates from remnant correlations in overdoped cuprates. The
doping-independent wavevector further reflects the presence of
nonlocal electron-phonon couplings. Our study reveals the importance of phonons
in the cuprates, which assist correlated electrons in the formation of exotic
phases.Comment: 7 pages, 4 figure
Calculation and experimental verification of force-magnetic coupling model of magnetised rail based on density functional theory
Metal magnetic memory (MMM) is a widely used non-destructive electromagnetic detection technology. However, the analysis of its underlying principle is still insufficient. The mechanical and magnetic coupling model is a reasonable standpoint from which to study the principle of MMM. In this paper, a mechanical and magnetic coupling model of steel material is established based on density functional theory (DFT) using the CASTEP first-principles analysis software. In order to simulate the practical working environment, the residual magnetism in the rail is assumed to change with the stress on the rail. By applying different stresses to the model, the relationship between the atomic magnetic moment, the lattice constant and stress is explored, as well as the causes of magnetic signals in the stress concentration zone. It is revealed that the atomic magnetic moment and the crystal volume decrease with the increase in compressive stress. The magnetic signal on the surface of the magnetised metal component decreases with the increase in compressive stress, while the tensile stress shows the opposite tendency. Generally speaking, the change in atomic magnetic moment and crystal volume caused by lattice distortion under stress can be seen as the fundamental reason for the change in magnetic signal on the surface of the magnetised metal. The bending experiment of the rail shows that the normal magnetic field decreases with the increase in compressive stress in the stress concentration zone. The conclusion is verified by experiments
Message Feedback Interference Cancellation Aided UAMP Iterative Detector for OTFS Systems
The designing of efficient signal detectors is important and yet challenge
for orthogonal time frequency space (OTFS) systems in high-mobility scenarios.
In this letter, we develop an efficient message feedback interference
cancellation aided unitary approximate message passing (denoted as UAMPMFIC)
iterative detector, where the latest feedback messages from variable nodes are
utilized for more reliable interference cancellation and performance
improvement. A fast recursive scheme is leveraged in the proposed UAMP-MFIC
detector to prevent complexity increasing. To further alleviate the
error-propagation and improve the receiver performance, we also develop the
bidirectional symbol detection structures, where Turbo UAMP-MFIC detector and
iterative weight UAMP-MFIC detector are proposed to efficiently fuse the
estimation results of forward and backward UAMP-MFIC detectors. The simulation
results are finally provided to demonstrate performance improvement of our
proposed detectors over existing detectors
Self-retracting motion of graphite micro-flakes: superlubricity in micrometer scale
Through experimental study, we reveal superlubricity as the mechanism of
self-retracting motion of micrometer sized graphite flakes on graphite
platforms by correlating respectively the lock-up or self-retraction states
with the commensurate or incommensurate contacts. We show that the
scale-dependent loss of self-retractability is caused by generation of contact
interfacial defects. A HOPG structure is also proposed to understand our
experimental observations, particularly in term of the polycrystal structure.
The realisation of the superlubricity in micrometer scale in our experiments
will have impact in the design and fabrication of micro/nanoelectromechanical
systems based on graphitic materials
Strain-induced enhancement of in infinite-layer PrSrNiO films
The mechanism of unconventional superconductivity in correlated materials
remains a great challenge in condensed matter physics. The recent discovery of
superconductivity in infinite-layer nickelates, as analog to high-Tc cuprates,
has opened a new route to tackle this challenge. By growing 8 nm Pr0.8Sr0.2NiO2
films on the (LaAlO3)0.3(Sr2AlTaO6)0.7 substrate, we successfully raise the
transition temperature Tc from 9 K in the widely studied SrTiO3-substrated
nickelates into 15 K. By combining x-ray absorption spectroscopy with the
first-principles and many-body simulations, we find a positive correlation
between Tc and the pre-edge peak intensity, which can be attributed to the
hybridization between Ni and O orbitals induced by the strain. Our result
suggests that structural engineering can further enhance unconventional
superconductivity, and the charge-transfer property plays a crucial role in the
pairing strength.Comment: 8 pages, 4 figure
CRAFTS for Fast Radio Bursts : extending the dispersion-fluence relation with new FRBs detected by FAST
We report three new FRBs discovered by the Five-hundred-meter Aperture Spherical radio Telescope (FAST), namely FRB 181017.J0036+11, FRB 181118, and FRB 181130, through the Commensal Radio Astronomy FAST Survey (CRAFTS). Together with FRB 181123, which was reported earlier, all four FAST-discovered FRBs share the same characteristics of low fluence (1000 pc cm(-3)), consistent with the anticorrelation between DM and fluence of the entire FRB population. FRB 181118 and FRB 181130 exhibit band-limited features. FRB 181130 is prominently scattered (tau(s) 8 ms) at 1.25 GHz. FRB 181017.J0036+11 has full-bandwidth emission with a fluence of 0.042 Jy ms, which is one of the faintest FRB sources detected so far. CRAFTS has started to build a new sample of FRBs that fills the region for more distant and fainter FRBs in the fluence-DME diagram, previously out of reach of other surveys. The implied all-sky event rate of FRBs is 1.24(-0.90)(+1.94) x 5 sky(-1) day(-1) at the 95% confidence interval above 0.0146 Jy ms. We also demonstrate here that the probability density function of CRAFTS FRB detections is sensitive to the assumed intrinsic FRB luminosity function and cosmological evolution, which may be further constrained with more discoveries
A repeating fast radio burst associated with a persistent radio source
The dispersive sweep of fast radio bursts (FRBs) has been used to probe the ionized baryon content of the intergalactic medium1, which is assumed to dominate the total extragalactic dispersion. Although the host-galaxy contributions to the dispersion measure appear to be small for most FRBs2, in at least one case there is evidence for an extreme magneto-ionic local environment3,4 and a compact persistent radio source5. Here we report the detection and localization of the repeating FRB 20190520B, which is co-located with a compact, persistent radio source and associated with a dwarf host galaxy of high specific-star-formation rate at a redshift of 0.241 ± 0.001. The estimated host-galaxy dispersion measure of approximately 903−111+72 parsecs per cubic centimetre, which is nearly an order of magnitude higher than the average of FRB host galaxies2,6, far exceeds the dispersion-measure contribution of the intergalactic medium. Caution is thus warranted in inferring redshifts for FRBs without accurate host-galaxy identifications
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Selected Chinese Art Song of Shande Ding: a Performance and Pedagogical Guide
Chinese art song includes a vast array of unique and beautiful repertoire. Shande Ding (1911–1995) was one of the pioneering western-educated Chinese composers, who composed a large number of Chinese art songs with Western compositional techniques and made a prominent contribution to the Chinese art song literature. However, due to the difficulty non-native speakers often experience singing in Chinese, these repertoires remain relatively unperformed in the United States. As such, there is a need for a guide to help international singers to be able to perform this repertoire.The purpose of this project is to provide singers with a performance and pedagogical guide of twelve songs from Ding’s thirty-one art songs, and a catalog of all thirty-one works. This research paper includes Ding’s biography, a performance guide with an English poetic translation, a Pinyin translation, an approximate International Phonetic Alphabet (IPA) translation, and word-for-word English translation of the selected twelve songs for non-Chinese speakers, a pedagogical analysis of these songs, discussing the lyrics, melodic and rhythmic elements, piano accompaniment, breathing, range, and accessibility, and a catalog of all thirty-one songs with title, source of the text, meter, key center, range, and performance considerations in an appendix. </p
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