Advances and Challenges of Multi-task Learning Method in Recommender System: A Survey

Multi-task learning has been widely applied in computational vision, natural language processing and other fields, which has achieved well performance. In recent years, a lot of work about multi-task learning recommender system has been yielded, but there is no previous literature to summarize these works. To bridge this gap, we provide a systematic literature survey about multi-task recommender systems, aiming to help researchers and practitioners quickly understand the current progress in this direction. In this survey, we first introduce the background and the motivation of the multi-task learning-based recommender systems. Then we provide a taxonomy of multi-task learning-based recommendation methods according to the different stages of multi-task learning techniques, which including task relationship discovery, model architecture and optimization strategy. Finally, we raise discussions on the application and promising future directions in this area

Detection of Hepatitis B virus in serum and liver of chickens

Hepatitis B virus (HBV) is one of the most important human pathogens. Its existence in food animals could present a significant threat to public health. The objective of this study was to determine if HBV is present in serum and liver of chickens. A total of 129 serum samples from broiler chickens were collected for the detection of HBV antigens and antibodies, and 193 liver samples were tested for HBV DNA sequence by PCR and for the existence of HBV antigens by immunohistochemistry. The overall prevalence of HBsAg, anti-HBs, anti-HBc was 28.68%, 53.49%, 17.05%, respectively, whereas HBeAg, anti-HBe were barely detectable. Three serum samples were found to be positive for both HBsAg and HBeAg. Further analysis of these samples with transmission electron microscopy (TEM) revealed two morphologic particles with 20 nm and 40 nm in diameter, which were similar to small spherical and Danes particles of HBV. The viral DNA sequence identified in two of the chicken livers shared 92.2% of one known HBV strain and 97.9% nucleotide sequence of another HBV strain. Our results showed the existence of HBV in chickens. This would present a significant risk to people who work with live chickens or chicken products if HBV found in chicken could be confirmed to be the same as human HBV

Increased Mast Cell Activation in Mongolian Gerbils Infected by Hepatitis E Virus

Recently, mechanism study of hepatitis E virus (HEV) infection has attracted an increasing attention because of the growing rate of the acute hepatitis caused by the virus over the world. As an important initiate in the inflammation, mast cells (MCs) play a critical role in maintaining a healthy physiology. However, the function of the MCs in the acute hepatitis caused by HEV is still unclear. In the present study, mongolian gerbils infected by HEV were used as an animal model to evaluate the role of MCs in the HEV infection. The positive ELISA and RT-PCR results showed the gerbils was successfully infected with HEV. The number of mast cell in the liver and the small intestine in the infected animals were growing higher significantly than the control group. In addition, higher expression of the tryptase and 5-HT in the liver and the intestine detected by immunohistochemical method and western blot also indicate the activation of MCs in the infection. These results suggest that MCs play an important role in the hepatitis E

Prevalence of Hepatitis E Virus in Swine Fed on Kitchen Residue

The aim of this study was to investigate the prevalence of swine hepatitis E virus (HEV) in pigs fed different feedstuffs (kitchen residue or mixed feeds) and genetic identification of HEV isolated in Hebei province, China. Serum and fecal samples were collected from adult swine. Anti-HEV antibody was evaluated by double sandwich antigen enzyme immunoassay. HEV RNA was extracted from fecal samples and amplified by nested RT-PCR. The reaction products were sequenced, and the sequence analyzed. Virus-like particles were distinguishable by negative staining in the electron microscope. Histopathological observation and immunohistochemical localization were used in the animal models. Overall, the anti-HEV positive percentage of serum samples from pigs fed on kitchen residue was 87.10% (27/31), and 53.06% (130/245) from pigs fed on complete feed. The HEV RNA positivity rate of fecal samples from pigs fed on kitchen residue was 61.54% (8/13), but zero for pigs fed on complete feed. Sequence analysis of these eight samples and comparison with the published sequence showed that there were eight groups that belonged to genotype 4 d and the nucleotide identity was 95.6–99.3%. swHE11 is most closely related to strain CCC220, and the other seven HEV isolates were most closely related to strains swGX40, SwCH189 and V0008ORF3, which are isolates from human and pigs. Histopathological observation showed that there was liver damage in the experimental group, and immunohistochemistry indicated that the HEV antigens were strongly positive at 7 days after infection. The results demonstrated that the prevalence of HEV in pigs fed on kitchen residue was higher than in those fed on complete feed (P<0.05)

Prevalence of a virus similar to human hepatitis B virus in swine

Abstract Background The objective of this study is to established evidence of the existence of a novel member of the hepadnavirus family endemic in swine. Temporarily this virus was designated as swine hepatitis B virus (SHBV). This SHBV can be detected by using human hepatitis B virus diagnostic kits including ELISA, immunohistochemical staining, and transmission electron microscopy (TEM). Also seroprevalence of pig farms in Beijing, China, and pathological features of SHBV infection was determined. Results Screened result shows that overall prevalence of HBsAg was 24.8%, closed to that of anti-HBsAg, whereas HBeAg and anti-HBe were barely detectable. The distribution of HBsAg and HBcAg was examined by immunohistochemistry of liver samples. Typical hepatitis pathological change, such as spotty parenchymal cell degeneration, necrosis of hepatocytes and proliferation of fibrous connective tissue were observed during histopathological analysis. Analysis of HBsAg-positive serum with TEM revealed two morphologic forms, 20 nm and 40 nm sized particles, similar to small spherical and Danes particles of HBV. Observation of the ultrastructure of the liver also found HBV-like particles in the nucleus of hepatocytes. Conclusion Our research result implies that SHBV could be a causative agent of swine. The discovery of SHBV will unveil novel evolutionary aspects of hepatitis and provides new information for further hepadnavirus research.</p

The Synergistic Effect of Acidic Properties and Channel Systems of Zeolites on the Synthesis of Polyoxymethylene Dimethyl Ethers from Dimethoxymethane and Trioxymethylene

A series of zeolites with different topology structures, including SAPO-34, SUZ-4, ZSM-5, USY, MOR, and beta, were used to synthesize polyoxymethylene dimethyl ethers (PODEn) from dimethoxymethane (DMM) and trioxymethylene (TOM). The influence of acidic properties and channel systems were studied by activity evaluation, characterization, and theoretical calculation. The results confirmed that pore mouth diameter larger than a TOM molecule was an essential prerequisite for the synthesis of PODEn over zeolites, and the synergistic effect between medium-strong Br&oslash;nsted acid sites (Br&oslash;nsted MAS) and the maximal space of zeolites available determined the catalytic performance of all studied zeolites. DMM and TOM were firstly decomposed into methoxymethoxy groups (MMZ) and monomer CH2O over Br&oslash;nsted MAS. Subsequently, the steric constraint of the maximum included sphere, with an appropriate size in zeolite channels, can promote the combination of CH2O and MMZ to form transition species ZO(CH2O)nCH3, which reacted with the methyl-end group to form PODEn over Br&oslash;nsted MAS. Moreover, the reaction temperature showed different effects on the product selectivity and distribution, which also mainly depends on the size of the maximum space available in zeolite channels

Cardioprotective Effects of SIRT6 in a Mouse Model of Transverse Aortic Constriction-Induced Heart Failure

SIRT6, a member of the NAD (+)-dependent class III deacetylase sirtuin family, plays important roles in the maintenance of cardiovascular homeostasis. Telomere shortening is a risk factor for age-associated diseases, including heart disease. In the present study, we investigated the role of SIRT6 and telomerase in a mouse model of transverse aortic constriction (TAC)-induced heart failure. SIRT6, telomerase reverse transcriptase (TERT), and telomere repeat binding factor (TRF)-1 were significantly downregulated in TAC mice compared with their expression in sham-operated mice. Lentiviral vector-mediated overexpression of SIRT6 upregulated TERT and TRF1 and increased the survival of mice after TAC. Echocardiography and hemodynamic measurements as well as histological analyses indicated that SIRT6 overexpression attenuated TAC-induced heart dysfunction and decreased TAC-induced cardiac inflammatory responses, reducing cardiac fibrosis and decreasing infarct size. Taken together, our findings indicate that SIRT6 protects the myocardium against damage and this effect may be mediated by the modulation of telomeres. Our findings linking SIRT6 and telomere integrity in the heart warrant further investigation into the underlying mechanisms and support SIRT6 as a promising therapeutic target for the treatment of cardiovascular diseases

Bacterial community diversity and dynamics of Dongzhai harbor mangrove soils in China

Dongzhai Harbor National Nature Reserve is the largest mangrove reserve in China, but the bacterial diversity and community structure of soils in the Dongzhai harbor mangrove (DHM) is still not well known. This study was conducted to characterize and compare the bacterial community diversity and composition of DHM soils in three typical sites (YA, entrance of wastewater and sanitary sewage; YB, located in Dongzhai Harbor National Nature Reserve; YC, near the sea) using high-throughput sequencing of the 16S rDNA. Community statistical analyses suggested that the YB and YC soils have a similar community structure, but they differ from the YA soils significantly. Proteobacteria and Chloroflexi were the ubiquitous and dominant groups that made up nearly 80% of total bacterial communities, but it was noted that Chloroflexi had a higher relative abundance in YA soil samples than YB and YC soil samples and that the operational taxonomic units (OTUs) of Anaerolineaceae, Gammaproteobacteria, and Thiogranum reached extremely significant levels. Interaction network analysis of the 50 most abundant OTUs further demonstrated that the OTUs of YA showed few interactions with YB and YC OTUs, and the Cluster of Orthologous Group (COG) involved in lipid transport and metabolism showed significant differences between the YA and YB soil samples. Our results will greatly help to understand the bacterial community variation of the DHM as human activities enhance and grow, and to identify some challenges for the restoration and management of the mangrove ecosystem.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author