2,748 research outputs found
Learning domain-specific sentiment lexicon with supervised sentiment-aware LDA
Frontiers in Artificial Intelligence and Applications, v. 263 entitled: ECAI 2014: 21st European Conference on Artificial Intelligence, 18-22 August 2014, Prague, Czech Republic - Including Prestigious Applications of Intelligent Systems (PAIS 2014)Analyzing and understanding people's sentiments towards different topics has become an interesting task due to the explosion of opinion-rich resources. In most sentiment analysis applications, sentiment lexicons play a crucial role, to be used as metadata of sentiment polarity. However, most previous works focus on discovering general-purpose sentiment lexicons. They cannot capture domain-specific sentiment words, or implicit and connotative sentiment words that are seemingly objective. In this paper, we propose a supervised sentiment-aware LDA model (ssLDA). The model uses a minimal set of domain-independent seed words and document labels to discover a domain-specific lexicon, learning a lexicon much richer and adaptive to the sentiment of specific document. Experiments on two publicly-available datasets (movie reviews and Obama-McCain debate dataset) show that our model is effective in constructing a comprehensive and high-quality domain-specific sentiment lexicon. Furthermore, the resulting lexicon significantly improves the performance of sentiment classification tasks. Š 2014 The Authors and IOS Press.published_or_final_versio
A topic model for building fine-grained domain-specific emotion lexicon
Emotion lexicons play a crucial role in sentiment analysis and opinion mining. In this paper, we propose a novel Emotion-aware LDA (EaLDA) model to build a domainspecific lexicon for predefined emotions that include anger, disgust, fear, joy, sadness, surprise. The model uses a minimal set of domain-independent seed words as prior knowledge to discover a domainspecific lexicon, learning a fine-grained emotion lexicon much richer and adaptive to a specific domain. By comprehensive experiments, we show that our model can generate a high-quality fine-grained domain-specific emotion lexicon. Š 2014 Association for Computational Linguistics.published_or_final_versio
The PB2 mutation with lysine at 627 enhances the pathogenicity of avian influenza (H7N9) virus which belongs to a non-zoonotic lineage
A novel avian-origin influenza A (H7N9) virus emerged in China in 2013 and has caused zoonotic disease in over 1123 persons with an overall mortality around 30%. Amino acid changes at the residues 591, 627 and 701 of polymerase basic protein 2 (PB2) have been found frequently in the human H7N9 isolates but not in viruses isolated from avian species. We have recently identified a cluster of H7N9 viruses in ducks which circulated in China prior to the first recognition of zoonotic disease in 2013. These duck viruses have genetic background distinct from the zoonotic H7N9 lineage. We found that the introduction of PB2 mutation with K at 627 but not K at 591 or N at 701 to the duck H7N9 virus led to increased pathogenicity in mice. We also found that the induction of pro-inflammatory cytokines including TNF-Îą, IP-10, MCP-1 and MIP-1Îą were associated with increased severity of infection. We conclude that introduction of the mammalian adaptation mutations into the PB2 gene of duck H7N9 viruses, which are genetically unrelated to the zoonotic H7N9 lineage, can also enhance pathogenicity in mice.published_or_final_versio
Implicitly Constrained Semi-Supervised Least Squares Classification
We introduce a novel semi-supervised version of the least squares classifier.
This implicitly constrained least squares (ICLS) classifier minimizes the
squared loss on the labeled data among the set of parameters implied by all
possible labelings of the unlabeled data. Unlike other discriminative
semi-supervised methods, our approach does not introduce explicit additional
assumptions into the objective function, but leverages implicit assumptions
already present in the choice of the supervised least squares classifier. We
show this approach can be formulated as a quadratic programming problem and its
solution can be found using a simple gradient descent procedure. We prove that,
in a certain way, our method never leads to performance worse than the
supervised classifier. Experimental results corroborate this theoretical result
in the multidimensional case on benchmark datasets, also in terms of the error
rate.Comment: 12 pages, 2 figures, 1 table. The Fourteenth International Symposium
on Intelligent Data Analysis (2015), Saint-Etienne, Franc
The cTnT response to acute exercise at the onset of an endurance training program: evidence of exercise preconditioning?
PURPOSE: Exercise induces a cardioprotective effect referred to as "preconditioning". Whether the preconditioning impacts upon the cardiac troponin T (cTnT) response to subsequent exercise bouts is unclear. This study investigated the effects of an initial exercise bout, a second exercise bout 48Â h later, as well as subsequent exercise every 48Â h for 4 days or a single identical exercise bout after 8 days of inactivity gap on cTnT response to acute exercise. METHODS: Twenty-eight sedentary overweight young women were randomly assigned to either six bouts of exercise each separated by 48Â h or three bouts of exercise with 48Â h between the first two bouts and 8 days between the second and third bouts. All exercise bouts were identical (60% [Formula: see text], 200Â kJ) and the total testing period (10 days) was the same for both groups. cTnT was assessed before and after the 1st, 2nd, and final exercise bouts. RESULTS: cTnT increased (129%, Pââ0.05) effect on post-exercise cTnT (<â3.00[<â3.00-21.96]). The final exercise bout resulted in an increase (190%, Pâ<â0.05) in cTnT (4.35[<â3.00-13.05]) in both groups. CONCLUSIONS: A single bout exercise resulted in a temporary blunting of cTnT response to acute exercise 48Â h later. The effect of exercise preconditioning was not preserved, regardless of whether followed by repeated exercise every 48Â h or a cessation of exercise for 8 days
APIR-Net: Autocalibrated Parallel Imaging Reconstruction using a Neural Network
Deep learning has been successfully demonstrated in MRI reconstruction of
accelerated acquisitions. However, its dependence on representative training
data limits the application across different contrasts, anatomies, or image
sizes. To address this limitation, we propose an unsupervised, auto-calibrated
k-space completion method, based on a uniquely designed neural network that
reconstructs the full k-space from an undersampled k-space, exploiting the
redundancy among the multiple channels in the receive coil in a parallel
imaging acquisition. To achieve this, contrary to common convolutional network
approaches, the proposed network has a decreasing number of feature maps of
constant size. In contrast to conventional parallel imaging methods such as
GRAPPA that estimate the prediction kernel from the fully sampled
autocalibration signals in a linear way, our method is able to learn nonlinear
relations between sampled and unsampled positions in k-space. The proposed
method was compared to the start-of-the-art ESPIRiT and RAKI methods in terms
of noise amplification and visual image quality in both phantom and in-vivo
experiments. The experiments indicate that APIR-Net provides a promising
alternative to the conventional parallel imaging methods, and results in
improved image quality especially for low SNR acquisitions.Comment: To appear in the proceedings of MICCAI 2019 Workshop Machine Learning
for Medical Image Reconstructio
The effect of beta-tricalcium phosphate on mechanical and thermal performances of poly(lactic acid)
Orthophosphates are bioactive crystals with similar structure, in terms of elemental composition and crystal nature, to human bone. In this work, biocomposite materials were prepared with poly(lactic acid) (PLA) as matrix, and betatricalcium phosphate (b-TCP) as osteoconductive filler by extrusion-compounding followed by conventional injection molding. The b-TCP load content was varied in the 10 40 wt% range and the influence of the b-TCP load on mechanical performance of PLA/b-TCP composites was evaluated. Mechanical properties of composites were obtained by standardized tensile, flexural, impact, and hardness tests. Thermal analysis of composites was carried out by means of differential scanning calorimetry; degradation at high temperatures was studied by thermogravimetric analysis; and the effect of the b-TCP load on dynamical response of composites was studied by mechanical thermal analysis in torsion mode. The bestbalanced properties were obtained for PLA composites containing 30 wt% b-TCP with a remarkable increase in the Young s modulus. These materials offer interesting properties to be used as base materials for medical applications such as interference screws due to high stiffness and mechanical resistance.The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This study was funded by "Conselleria d'Educacio, Cultura i Esport" - Generalitat Valenciana ref: GV/2014/008.Ferri Azor, JM.; Gisbert, I.; GarcĂa Sanoguera, D.; Reig PĂŠrez, MJ.; Balart Gimeno, RA. (2016). The effect of beta-tricalcium phosphate on mechanical and thermal performances of poly(lactic acid). Journal of Composite Materials. 50(30):4189-4198. https://doi.org/10.1177/0021998316636205S41894198503
Use of antagonist muscle EMG in the assessment of neuromuscular health of the low back
Background: Non-specific low back pain (LBP) has been one of the most frequently occurring musculoskeletal problems. Impairment in the mechanical stability of the lumbar spine has been known to lower the safety margin of the spine musculature and can result in the occurrence of pain symptoms of the low back area. Previously, changes in spinal stability have been identified by investigating recruitment patterns of low back and abdominal muscles in laboratory experiments with controlled postures and physical activities that were hard to conduct in daily life. The main objective of this study was to explore the possibility of developing a reliable spine stability assessment method using surface electromyography (EMG) of the low back and abdominal muscles in common physical activities. Methods: Twenty asymptomatic young participants conducted normal walking, plank, and isometric back extension activities prior to and immediately after maintaining a 10-min static upper body deep flexion on a flat bed. EMG data of the erector spinae, external oblique, and rectus abdominals were collected bilaterally, and their mean normalized amplitude values were compared between before and after the static deep flexion. Changes in the amplitude and co-contraction ratio values were evaluated to understand how muscle recruitment patterns have changed after the static deep flexion. Results: Mean normalized amplitude of antagonist muscles (erector spinae muscles while conducting plank; external oblique and rectus abdominal muscles while conducting isometric back extension) decreased significantly (P < 0.05) after the 10-min static deep flexion. Normalized amplitude of agonist muscles did not vary significantly after deep flexion. Conclusions: Results of this study suggest the possibility of using surface EMG in the evaluation of spinal stability and low back health status in simple exercise postures that can be done in non-laboratory settings. Specifically, amplitude of antagonist muscles was found to be more sensitive than agonist muscles in identifying changes in the spinal stability associated with the 10-min static deep flexion. Further research with various loading conditions and physical activities need to be performed to improve the reliability and utility of the findings of the current study.open0
Interplay of Mre11 Nuclease with Dna2 plus Sgs1 in Rad51-Dependent Recombinational Repair
The Mre11/Rad50/Xrs2 complex initiates IR repair by binding to the end of a double-strand break, resulting in 5Ⲡto 3Ⲡexonuclease degradation creating a single-stranded 3Ⲡoverhang competent for strand invasion into the unbroken chromosome. The nuclease(s) involved are not well understood. Mre11 encodes a nuclease, but it has 3Ⲡto 5â˛, rather than 5Ⲡto 3Ⲡactivity. Furthermore, mutations that inactivate only the nuclease activity of Mre11 but not its other repair functions, mre11-D56N and mre11-H125N, are resistant to IR. This suggests that another nuclease can catalyze 5Ⲡto 3Ⲡdegradation. One candidate nuclease that has not been tested to date because it is encoded by an essential gene is the Dna2 helicase/nuclease. We recently reported the ability to suppress the lethality of a dna2Î with a pif1Î. The dna2Î pif1Î mutant is IR-resistant. We have determined that dna2Î pif1Î mre11-D56N and dna2Î pif1Î mre11-H125N strains are equally as sensitive to IR as mre11Î strains, suggesting that in the absence of Dna2, Mre11 nuclease carries out repair. The dna2Î pif1Î mre11-D56N triple mutant is complemented by plasmids expressing Mre11, Dna2 or dna2K1080E, a mutant with defective helicase and functional nuclease, demonstrating that the nuclease of Dna2 compensates for the absence of Mre11 nuclease in IR repair, presumably in 5Ⲡto 3Ⲡdegradation at DSB ends. We further show that sgs1Î mre11-H125N, but not sgs1Î, is very sensitive to IR, implicating the Sgs1 helicase in the Dna2-mediated pathway
A Unique Automation Platform for Measuring Low Level Radioactivity in Metabolite Identification Studies
Generation and interpretation of biotransformation data on drugs, i.e. identification of physiologically relevant metabolites, defining metabolic pathways and elucidation of metabolite structures, have become increasingly important to the drug development process. Profiling using 14C or 3H radiolabel is defined as the chromatographic separation and quantification of drug-related material in a given biological sample derived from an in vitro, preclinical in vivo or clinical study. Metabolite profiling is a very time intensive activity, particularly for preclinical in vivo or clinical studies which have defined limitations on radiation burden and exposure levels. A clear gap exists for certain studies which do not require specialized high volume automation technologies, yet these studies would still clearly benefit from automation. Use of radiolabeled compounds in preclinical and clinical ADME studies, specifically for metabolite profiling and identification are a very good example. The current lack of automation for measuring low level radioactivity in metabolite profiling requires substantial capacity, personal attention and resources from laboratory scientists. To help address these challenges and improve efficiency, we have innovated, developed and implemented a novel and flexible automation platform that integrates a robotic plate handling platform, HPLC or UPLC system, mass spectrometer and an automated fraction collector
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