453 research outputs found
Asset Pricing and the Foreign Exchange Risk in the Polish Market
This study examines the relationship between the cross-section of Polish stock returns and the foreign exchange rates with a sample period from 2002 to 2011. The findings indicate that the foreign exchange risk is priced in the cross-section of Polish stock returns with a sample period spanning 2002 to 2011. Moreover, it is also evident that the relation between the expected returns and the foreign exchange sensitivity is not linear and the foreign exchange sensitivity is larger for stocks with small size and high book-to- market ratios
Experimental tests of the chiral anomaly magnetoresistance in the Dirac-Weyl semimetals NaBi and GdPtBi
In the Dirac/Weyl semimetal, the chiral anomaly appears as an "axial" current
arising from charge-pumping between the lowest (chiral) Landau levels of the
Weyl nodes, when an electric field is applied parallel to a magnetic field . Evidence for the chiral anomaly was obtained from the longitudinal
magnetoresistance (LMR) in NaBi and GdPtBi. However, current jetting
effects (focussing of the current density ) have raised general concerns
about LMR experiments. Here we implement a litmus test that allows the
intrinsic LMR in NaBi and GdPtBi to be sharply distinguished from pure
current jetting effects (in pure Bi). Current jetting enhances along the
mid-ridge (spine) of the sample while decreasing it at the edge. We measure the
distortion by comparing the local voltage drop at the spine (expressed as the
resistance ) with that at the edge (). In Bi,
sharply increases with but decreases (jetting effects are
dominant). However, in NaBi and GdPtBi, both and
decrease (jetting effects are subdominant). A numerical simulation allows the
jetting distortions to be removed entirely. We find that the intrinsic
longitudinal resistivity in NaBi decreases by a factor of
10.9 between = 0 and 10 T. A second litmus test is obtained from the
parametric plot of the planar angular magnetoresistance. These results
strenghthen considerably the evidence for the intrinsic nature of the
chiral-anomaly induced LMR. We briefly discuss how the squeeze test may be
extended to test ZrTe.Comment: 17 pages, 8 figures, new co-authors added, new Fig. 6a added. In
press, PR
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Hierarchical Structure with Highly Ordered Macroporous-Mesoporous Metal-Organic Frameworks as Dual Function for CO2 Fixation.
As a major greenhouse gas, the continuous increase of carbon dioxide (CO2) in the atmosphere has caused serious environmental problems, although CO2 is also an abundant, inexpensive, and nontoxic carbon source. Here, we use metal-organic framework (MOF) with highly ordered hierarchical structure as adsorbent and catalyst for chemical fixation of CO2 at atmospheric pressure, and the CO2 can be converted to the formate in excellent yields. Meanwhile, we have successfully integrated highly ordered macroporous and mesoporous structures into MOFs, and the macro-, meso-, and microporous structures have all been presented in one framework. Based on the unique hierarchical pores, high surface area (592 m2/g), and high CO2 adsorption capacity (49.51 cm3/g), the ordered macroporous-mesoporous MOFs possess high activity for chemical fixation of CO2 (yield of 77%). These results provide a promising route of chemical CO2 fixation through MOF materials
High-efficiency photoelectric detector based on a p-n homojunction of monolayer black phosphorus
We numerically investigate the high-efficiency photovoltaic effect in lateral
p-n homojunction based on monolayer black phosphorus (MBP) by using the
non-equilibrium Green's function combined with the density functional theory.
Due to the built-in electric field of the p-n junction and the wrinkle
structure of MBP, the photocurrent excited by either linearly or elliptically
polarized light is significantly enhanced in a wide photon energy range.
Moreover, because of the electron-photon interaction, the photocurrent is
related to atomic orbitals through the polarizing angle of polarized light.
Therefore, we can read the orbital information of the band structure from the
polarizing angular distribution of photocurrent. These findings suggest the
promising application of MBP-based p-n homojunction in high-efficiency
photoelectric devices and orbital-resolved photovoltaic detection
Semantic Enhanced Knowledge Graph for Large-Scale Zero-Shot Learning
Zero-Shot Learning has been a highlighted research topic in both vision and
language areas. Recently, most existing methods adopt structured knowledge
information to model explicit correlations among categories and use deep graph
convolutional network to propagate information between different categories.
However, it is difficult to add new categories to existing structured knowledge
graph, and deep graph convolutional network suffers from over-smoothing
problem. In this paper, we provide a new semantic enhanced knowledge graph that
contains both expert knowledge and categories semantic correlation. Our
semantic enhanced knowledge graph can further enhance the correlations among
categories and make it easy to absorb new categories. To propagate information
on the knowledge graph, we propose a novel Residual Graph Convolutional Network
(ResGCN), which can effectively alleviate the problem of over-smoothing.
Experiments conducted on the widely used large-scale ImageNet-21K dataset and
AWA2 dataset show the effectiveness of our method, and establish a new
state-of-the-art on zero-shot learning. Moreover, our results on the
large-scale ImageNet-21K with various feature extraction networks show that our
method has better generalization and robustness
SVFormer: Semi-supervised Video Transformer for Action Recognition
Semi-supervised action recognition is a challenging but critical task due to
the high cost of video annotations. Existing approaches mainly use
convolutional neural networks, yet current revolutionary vision transformer
models have been less explored. In this paper, we investigate the use of
transformer models under the SSL setting for action recognition. To this end,
we introduce SVFormer, which adopts a steady pseudo-labeling framework (ie,
EMA-Teacher) to cope with unlabeled video samples. While a wide range of data
augmentations have been shown effective for semi-supervised image
classification, they generally produce limited results for video recognition.
We therefore introduce a novel augmentation strategy, Tube TokenMix, tailored
for video data where video clips are mixed via a mask with consistent masked
tokens over the temporal axis. In addition, we propose a temporal warping
augmentation to cover the complex temporal variation in videos, which stretches
selected frames to various temporal durations in the clip. Extensive
experiments on three datasets Kinetics-400, UCF-101, and HMDB-51 verify the
advantage of SVFormer. In particular, SVFormer outperforms the state-of-the-art
by 31.5% with fewer training epochs under the 1% labeling rate of Kinetics-400.
Our method can hopefully serve as a strong benchmark and encourage future
search on semi-supervised action recognition with Transformer networks
Polycomb proteins control floral determinacy by H3K27me3-mediated repression of pluripotency genes in arabidopsis thaliana
Logistic regression analysis of clinical and computed tomography features of pulmonary abscesses and risk factors for pulmonary abscess-related empyema
OBJECTIVES: This study was conducted to investigate the risk factors for pulmonary abscess-related empyema by investigating the clinical characteristics and chest computed tomography imaging features of patients with pulmonary abscesses. METHODS: We retrospectively analyzed the chest computed tomography findings and clinical features of 101 cases of pulmonary abscess, including 25 cases with empyema (the experimental group) and 76 cases with no empyema (the control group). The potential risk factors for pulmonary abscess-related empyema were compared between the groups by using univariate and multivariate logistic regression analyses. RESULTS: The incidence of pulmonary abscess-related empyema was 24.8% (25/101). Univariate analysis showed that male gender, diabetes, pleuritic symptoms, white blood cells 410 109 /L, albumin level o25 g/L, and positive sputum cultures were potential clinical-related risk factors and that an abscess 45 cm in diameter and transpulmonary fissure abscesses were potential computed tomography imaging-related risk factors for pulmonary abscess-related empyema. Multivariate logistic regression analysis showed that transpulmonary fissure abscesses (odds ratio=9.102, p=0.003), diabetes (odds ratio=9.066, p=0.003), an abscess 45 cm in diameter (odds ratio=8.998, p=0.002), and pleuritic symptoms (odds ratio=5.395, p=0.015) were independent risk factors for pulmonary abscess-related empyema. CONCLUSIONS: Transpulmonary fissure abscesses, diabetes, giant pulmonary abscesses, and pleuritic symptoms increased the risk of empyema among patients with pulmonary abscesses
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