6,856 research outputs found
Temporal-spatial variations, source apportionment, and ecological risk of trace elements in sediments of water-level-fluctuation zone in the Three Gorges Reservoir, China
The Three Gorges Reservoir (TGR) plays a crucial role in providing electricity for mega-cities across China. However, since the impoundment was completed in 2006, attention to environmental concerns has also been intensive. In order to determine the distribution, sources, and pollution status of trace elements in the water fluctuation zone of the TGR following ten years of repeated “submergence” and “exposure”, we systematically collected 16 paired surface sediment samples (n = 32) covering the entire main body of the TGR in March 2018 (following 6 months of submergence) and September 2018 (after 6 months of exposure), and quantitatively analyzed 13 elements (e.g., Mn, Fe, V, Cr, Ni, Cu, Zn, As, Sr, Y, Zr, Ba, and Pb) using X-ray fluorescence spectrophotometry (XRF). The results showed that, except for Sr, concentrations of trace metals following submergence were generally higher than those after exposure due to the less settling of suspended solids at the faster flow velocity during the drawdown period. Assessment using enrichment factors (EFs) and a geo-accumulation index (Igeo) both characterized a relatively serious anthropogenic pollution status of metals in the upper reaches of the TGR with respect to the middle-lower reaches. Source apportionment by positive matrix factorization (PMF) analysis indicated that agricultural activities (24.8 and 24.3%, respectively) and industrial emissions (24.5 and 22.9%, respectively) were the two major sources in these two periods, followed by natural sources, domestic sewage, and ore mining. Ecological risk assessment showed that metalloid arsenic (As) could be the main potential issue of risk to aquatic organisms and human health. A new source-specific risk assessment method (pRI) combined with PMF revealed that agricultural activities could be the major source of potential ecological risk and should be prioritized as the focus of metal/metalloid risk management in the TGR
Evaluating aggregate effects of rare and common variants in the 1000 Genomes Project exon sequencing data using latent variable structural equation modeling
Methods that can evaluate aggregate effects of rare and common variants are limited. Therefore, we applied a two-stage approach to evaluate aggregate gene effects in the 1000 Genomes Project data, which contain 24,487 single-nucleotide polymorphisms (SNPs) in 697 unrelated individuals from 7 populations. In stage 1, we identified potentially interesting genes (PIGs) as those having at least one SNP meeting Bonferroni correction using univariate, multiple regression models. In stage 2, we evaluate aggregate PIG effects on trait, Q1, by modeling each gene as a latent construct, which is defined by multiple common and rare variants, using the multivariate statistical framework of structural equation modeling (SEM). In stage 1, we found that PIGs varied markedly between a randomly selected replicate (replicate 137) and 100 other replicates, with the exception of FLT1. In stage 1, collapsing rare variants decreased false positives but increased false negatives. In stage 2, we developed a good-fitting SEM model that included all nine genes simulated to affect Q1 (FLT1, KDR, ARNT, ELAV4, FLT4, HIF1A, HIF3A, VEGFA, VEGFC) and found that FLT1 had the largest effect on Q1 (βstd = 0.33 ± 0.05). Using replicate 137 estimates as population values, we found that the mean relative bias in the parameters (loadings, paths, residuals) and their standard errors across 100 replicates was on average, less than 5%. Our latent variable SEM approach provides a viable framework for modeling aggregate effects of rare and common variants in multiple genes, but more elegant methods are needed in stage 1 to minimize type I and type II error
Conformative Filtering for Implicit Feedback Data
Implicit feedback is the simplest form of user feedback that can be used for
item recommendation. It is easy to collect and is domain independent. However,
there is a lack of negative examples. Previous work tackles this problem by
assuming that users are not interested or not as much interested in the
unconsumed items. Those assumptions are often severely violated since
non-consumption can be due to factors like unawareness or lack of resources.
Therefore, non-consumption by a user does not always mean disinterest or
irrelevance. In this paper, we propose a novel method called Conformative
Filtering (CoF) to address the issue. The motivating observation is that if
there is a large group of users who share the same taste and none of them have
consumed an item before, then it is likely that the item is not of interest to
the group. We perform multidimensional clustering on implicit feedback data
using hierarchical latent tree analysis (HLTA) to identify user `tastes' groups
and make recommendations for a user based on her memberships in the groups and
on the past behavior of the groups. Experiments on two real-world datasets from
different domains show that CoF has superior performance compared to several
common baselines
Automatic Discrimination of Laughter Using Distributed sEMG
Laughter is a very interesting non-verbal human vocalization. It is classified as a semi voluntary behavior despite being a direct form of social interaction, and can be elicited by a variety of very different stimuli, both cognitive and physical. Automatic laughter detection, analysis and classification will boost progress in affective computing, leading to the development of more natural human-machine communication interfaces. Surface Electromyography (sEMG) on abdominal muscles or invasive EMG on the larynx show potential in this direction, but these kinds of EMG-based sensing systems cannot be used in ecological settings due to their size, lack of reusability and uncomfortable setup. For this reason, they cannot be easily used for natural detection and measurement of a volatile social behavior like laughter in a variety of different situations. We propose the use of miniaturized, wireless, dry-electrode sEMG sensors on the neck for the detection and analysis of laughter. Even if with this solution the activation of specific larynx muscles cannot be precisely measured, it is possible to detect different EMG patterns related to larynx function. In addition, integrating sEMG analysis on a multisensory compact system positioned on the neck would improve the overall robustness of the whole sensing system, enabling the synchronized measure of different characteristics of laughter, like vocal production, head movement or facial expression; being at the same time less intrusive, as the neck is normally more accessible than abdominal muscles. In this paper, we report laughter discrimination rate obtained with our system depending on different conditions
How to perform better intervention to prevent and control diabetic retinopathy among patients with type 2 diabetes
This meta-analysis of randomized controlled trials (RCTs) aims to investigate how to perform better interventions targeting modifiable risk factors of diabetic retinopathy (DR) to
prevent and control DR in patients with type 2 diabetes by comparing different intervention
types and follow-up intervals. Literature published before June 1st, 2019 were searched on
Pubmed, Embase and ScienceDirect. RCTs targeting modifiable risk factors of DR (including
blood glucose, blood pressure, lipid, dietary, physical activity and smoking) were selected
by two reviewers and double checked for accuracy. Random effects models were estimated
to calculate pooled Odds Ratios (OR). Twenty-two RCTs (n = 22,511) were included. In general, interventions targeting modifiable risk factor of DR reduced the risk of developing DR
(I
2 = 26.7%; OR = 0.60; 95% CI 0.45 to 0.79) and DR worsening (I
2 = 0.0%; OR = 0.62; 95% CI 0.47
to 0.80; P < 0.001). Multifactorial interventions had better effect on reducing the risk of
development and progression of DR in comparison with other interventions, while only
blood-pressure-control interventions showed significant effect on slowing down DR worsening. Additionally, interventions with follow-up >5 years had better effect on reduction of
DR development, and interventions with follow-up >2 years had better effect on reducing
the risk of DR worsenin
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A new perspective of e-trust in the era of social media: insights from customer satisfaction data
Managerial relevance: In this competitive business world, social media penetrates online sales very rapidly. Businesses operating online are required to provide a safe and secured environment for customers to ensure their satisfaction. Our research results confirm that in addition to social media advertising, guaranteed 'e-safety' for customers will help establishing trust between the customer and the online businesses; it is also viewed important for present and future sales. The social media reviews need to be incorporated in managerial decision making. We try to analyse how these reviews are changing over the period of time and what are the ways to enhance customer satisfaction using information on customer expectations. This paper can help service companies to position their websites to compete in the market. Abstract In this era of social media, products and services are sold globally using a few simple clicks online. In such online purchases, trust and familiarity are considered two important driving forces of consumer decision making. While online sales advocate high levels of flexibility and choices for consumers, they also hold the online service provider responsible for ensuring the security of the online user's data. Using a Structural Equation Model (SEM) with data collected from the online service industry, we test the direct effects of 'social media-induced purchase intention' on customer satisfaction. We also test the mediating role of e-commerce/online sales (e-advertisement, e-safety and e-information) on customer satisfaction. In addition to social media advertising and information sharing, we find that a new factor-'e-safety'-mediates the relationship between customer purchase intention and customer satisfaction. Our analysis indicates that online e-trust can be established between the customer and the service company when online purchases are made. At the same time, the quality of online information and e-safety of online payments make the service company trustworthy for future purchases. We relate data analysis directly to managerial decision making to avoid any delay in online customer services in the era of social media
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The performance of UK stock recommendation revisions: Does brokerage house reputation matter?
Data availability statement: The data that support the findings of this study are available from the corresponding author upon reasonable request.Copyright © 2020 The Authors. Our study examines the impact of brokerage house (BH) reputation on the performance of investment strategies following stock recommendation revisions in the UK stock market. We develop two alternative proxies for BH reputation based either on the past positions on the annualInstitutional Investor(II) All-Europe Research Team or on the past recommendation performance of BHs. We find that BH reputation proxied by the pastIIrankings has no significant impact on the recommendation performance, suggesting that theIIrankings are largely "popularity contests". However, BH reputation proxied by the past year recommendation performance of BHs has a significantly positive impact on the recommendation performance in the next year, implying that the recommendation performance of BHs in the UK market is persistent. The bootstrap simulations further confirm that the observed performance persistence could be due to BH skill rather than BH luck (i.e., random chance).Faculty of Humanities and Social Sciences (HaSS), Newcastle University under the Faculty Research Fund, Grant/Award Number: OSR/0372/FR19/0001
Transcriptional Robustness Complements Nonsense-Mediated Decay in Humans
In eukaryotes, gene expression is a complex, multi-step process involving transcription, splicing, translation, and post-translational modifications. At each individual step, errors can occur that lead to nonfunctional and potentially toxic proteins. Therefore, eukaryotes have evolved a wide array of solutions to minimize the risk of error.This work was supported by NIH grant R01 GM088344 to COW. The funder had no role in the preparation of the article.Cellular and Molecular Biolog
Occurrence, sources and seasonal variation of PM2.5 carbonaceous aerosols in a water level fluctuation zone in the Three Gorges Reservoir, China
Periodic water impoundment and seasonal flood events result in a 30 m water level fluctuation zone (WLFZ) in the Three Gorges Reservoir Region (TGRR), China. In order to assess the occurrence, sources and seasonal variation of airborne carbonaceous pollutants, a total of thirty-nine PM2.5 samples, twenty-two from August 2017 (summer: low water level ∼135m) and seventeen from January 2018 (winter: high water level ∼175m) were collected consecutively at a rural site in WLFZ in the TGRR. The results showed that OC, EC, char, soot, 16 PAHs and n-alkanes were higher in winter (mean: 9.17 μg/m3, 4.69 μg/m3, 4.25 μg/m3, 0.45 μg/m3, 19.8 ng/m3 and 210 ng/m3, respectively) than in summer (mean: 6.55 μg/m3, 1.70 μg/m3, 1.37 μg/m3, 0.32 μg/m3, 6.13 ng/m3 and 79.1 ng/m3, respectively). Compositional differences suggested air-soil/plant exchange as a source for 2-3-rings PAHs in summer and biomass burning for 4-5-rings in winter. Diagnostic ratios and PCA suggested more vehicular emission for PAHs in summer. Plant waxes contributed 18.2% and 26.2% of the n-alkanes in summer and winter, respectively, implying a relatively greater contribution from petroleum residues. The specific ratios and relative abundance of hopanes and steranes indicated mixed sources from both vehicle exhaust and petroleum residue; and petroleum residues contribute more steranes in summer compared with winter. As revealing basic information on the formation mechanism of carbonaceous aerosols, this study could contribute to a further understanding of their environmental geochemical behavior in the WLFZ of TGRR
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