2,389 research outputs found
Dynamic structure of stock communities: A comparative study between stock returns and turnover rates
The detection of community structure in stock market is of theoretical and
practical significance for the study of financial dynamics and portfolio risk
estimation. We here study the community structures in Chinese stock markets
from the aspects of both price returns and turnover rates, by using a
combination of the PMFG and infomap methods based on a distance matrix. We find
that a few of the largest communities are composed of certain specific industry
or conceptional sectors and the correlation inside a sector is generally larger
than the correlation between different sectors. In comparison with returns, the
community structure for turnover rates is more complex and the sector effect is
relatively weaker. The financial dynamics is further studied by analyzing the
community structures over five sub-periods. Sectors like banks, real estate,
health care and New Shanghai take turns to compose a few of the largest
communities for both returns and turnover rates in different sub-periods.
Several specific sectors appear in the communities with different rank orders
for the two time series even in the same sub-period. A comparison between the
evolution of prices and turnover rates of stocks from these sectors is
conducted to better understand their differences. We find that stock prices
only had large changes around some important events while turnover rates surged
after each of these events relevant to specific sectors, which may offer a
possible explanation for the complexity of stock communities for turnover
rates
Synthesis of Three-Dimensional Nanocarbon Hybrids by Chemical Vapor Deposition
Carbon nanomaterials such as graphene, carbon nanotube (CNT), and carbon nanofiber (CNF) have received tremendous attentions in the past two decades due to their extraordinary mechanical strength and thermal and electrical properties. Recently, it indicates that three-dimensional (3D) nanocarbon hybrids overcome the weakness of individual low-dimensional nanocarbon materials and exhibit unique properties among carbon nanomaterials. Efforts have thus been made to acquire synergistic integration of one-dimensional (1D) and two-dimensional (2D) carbon nanomaterials. Meanwhile, chemical vapor deposition (CVD) is a widespread and effective method of fabricating three-dimensional nanocarbon hybrids compared with other synthetic methods. In this case, a number of 3D nanocarbon hybrids are synthesized by using different precursors at diverse temperature, and the nanocarbon hybrids are expected to be a promising choice for various application areas in the future
Tree-based Text-Vision BERT for Video Search in Baidu Video Advertising
The advancement of the communication technology and the popularity of the
smart phones foster the booming of video ads. Baidu, as one of the leading
search engine companies in the world, receives billions of search queries per
day. How to pair the video ads with the user search is the core task of Baidu
video advertising. Due to the modality gap, the query-to-video retrieval is
much more challenging than traditional query-to-document retrieval and
image-to-image search. Traditionally, the query-to-video retrieval is tackled
by the query-to-title retrieval, which is not reliable when the quality of
tiles are not high. With the rapid progress achieved in computer vision and
natural language processing in recent years, content-based search methods
becomes promising for the query-to-video retrieval. Benefited from pretraining
on large-scale datasets, some visionBERT methods based on cross-modal attention
have achieved excellent performance in many vision-language tasks not only in
academia but also in industry. Nevertheless, the expensive computation cost of
cross-modal attention makes it impractical for large-scale search in industrial
applications. In this work, we present a tree-based combo-attention network
(TCAN) which has been recently launched in Baidu's dynamic video advertising
platform. It provides a practical solution to deploy the heavy cross-modal
attention for the large-scale query-to-video search. After launching tree-based
combo-attention network, click-through rate gets improved by 2.29\% and
conversion rate get improved by 2.63\%.Comment: This revision is based on a manuscript submitted in October 2020, to
ICDE 2021. We thank the Program Committee for their valuable comment
Grease film evolution in rolling elastohydrodynamic lubrication contacts
Although most rolling element bearings are grease lubricated, the underlying mechanisms of grease lubrication has not been fully explored. This study investigates grease film evolution with glass disc revolutions in rolling elastohydrodynamic lubrication (EHL) contacts. The evolution patterns of the grease films were highly related to the speed ranges and grease structures. The transference of thickener lumps, film thickness decay induced by starvation, and residual layer were recognized. The formation of an equilibrium film determined by the balance of lubricant loss and replenishment was analyzed. The primary mechanisms that dominate grease film formation in different lubricated contacts were clarified. © 2020, The Author(s)
Alpha-1 antitrypsin is a potential biomarker for hepatitis B
<p>Abstract</p> <p>Background</p> <p>Function exertion of specific proteins are key factors in disease progression, thus the systematical identification of those specific proteins is a prerequisite to understand various diseases. Though many proteins have been verified to impact on hepatitis, no systematical protein screening has been documented to hepatitis B virus (HBV) induced hepatitis, hindering the comprehensive understanding to this severe disease.</p> <p>Aim</p> <p>To identify the major proteins in the progression of HBV infection from mild stage to severe stage.</p> <p>Methods</p> <p>We performed an integrated strategy by combining two-dimensional electrophoresis (2-DE), peptide mass fingerprinting (PMF) analysis, and tissue microarray techniques to screen the functional proteins and detect the localization of those proteins.</p> <p>Results</p> <p>Interestingly, MS/MS identification revealed the expression level of alpha-1 antitrypsin (AAT) was significantly elevated in serum samples from patients with severe chronic hepatitis. Immunoblotting with a specific AAT antibody confirmed that AAT is highly expressed in serum samples from patients with hepatic carcinoma and severe chronic hepatitis. Furthermore, we observed that AAT is with highest expression in normal tissue and cells, but lowest in hepatic carcinoma and severe chronic hepatitis tissues and cells, suggesting the specific secretion of AAT from tissues and cells to serum.</p> <p>Conclusion</p> <p>These results suggest the possibility of AAT as a potential biomarker for hepatitis B in diagnosis.</p
Microbiology, ecology, and application of the nitrite-dependent anaerobic methane oxidation process
Nitrite-dependent anaerobic methane oxidation (n-damo), which couples the anaerobic oxidation of methane to denitrification, is a recently discovered process mediated by “Candidatus Methylomirabilis oxyfera.” M. oxyfera is affiliated with the “NC10” phylum, a phylum having no members in pure culture. Based on the isotopic labeling experiments, it is hypothesized that M. oxyfera has an unusual intra-aerobic pathway for the production of oxygen via the dismutation of nitric oxide into dinitrogen gas and oxygen. In addition, the bacterial species has a unique ultrastructure that is distinct from that of other previously described microorganisms. M. oxyfera-like sequences have been recovered from different natural habitats, suggesting that the n-damo process potentially contributes to global carbon and nitrogen cycles. The n-damo process is a process that can reduce the greenhouse effect, as methane is more effective in heat-trapping than carbon dioxide. The n-damo process, which uses methane instead of organic matter to drive denitrification, is also an economical nitrogen removal process because methane is a relatively inexpensive electron donor. This mini-review summarizes the peculiar microbiology of M. oxyfera and discusses the potential ecological importance and engineering application of the n-damo process
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