221 research outputs found
Cost-Sensitive Boosting for Classification of Imbalanced Data
The classification of data with imbalanced class distributions has
posed a significant drawback in the performance attainable by most
well-developed classification systems, which assume relatively
balanced class distributions. This problem is especially crucial
in many application domains, such as medical diagnosis, fraud
detection, network intrusion, etc., which are of great importance
in machine learning and data mining.
This thesis explores meta-techniques which are applicable to most
classifier learning algorithms, with the aim to advance the
classification of imbalanced data. Boosting is a powerful
meta-technique to learn an ensemble of weak models with a promise
of improving the classification accuracy. AdaBoost has been taken
as the most successful boosting algorithm. This thesis starts with
applying AdaBoost to an associative classifier for both learning
time reduction and accuracy improvement. However, the promise of
accuracy improvement is trivial in the context of the class
imbalance problem, where accuracy is less meaningful. The insight
gained from a comprehensive analysis on the boosting strategy of
AdaBoost leads to the investigation of cost-sensitive boosting
algorithms, which are developed by introducing cost items into the
learning framework of AdaBoost. The cost items are used to denote
the uneven identification importance among classes, such that the
boosting strategies can intentionally bias the learning towards
classes associated with higher identification importance and
eventually improve the identification performance on them. Given
an application domain, cost values with respect to different types
of samples are usually unavailable for applying the proposed
cost-sensitive boosting algorithms. To set up the effective cost
values, empirical methods are used for bi-class applications and
heuristic searching of the Genetic Algorithm is employed for
multi-class applications.
This thesis also covers the implementation of the proposed
cost-sensitive boosting algorithms. It ends with a discussion on
the experimental results of classification of real-world
imbalanced data. Compared with existing algorithms, the new
algorithms this thesis presents are superior in achieving better
measurements regarding the learning objectives
Simultaneous Determination of Copper, Lead, and Cadmium at Hexagonal Mesoporous Silica Immobilized Quercetin Modified Carbon Paste Electrode
A new method was developed for simultaneous determination of copper, lead, and cadmium, based on their voltammetric response at a carbon paste electrode modified with hexagonal mesoporous silica (HMS) immobilized quercetin (HMS-Qu/CPE). Compared with quercetin modified carbon paste electrode (Qu/CPE) and quercetin ionic liquid modified carbon paste electrode (Qu-IL/CPE), the HMS-Qu/CPE exhibited improved selectivity and high sensitivity toward the detection of copper, lead, and cadmium. The properties of the HMS-Qu/CPE in 0.1 M HCOONa-HCl buffer solution (pH4.7) were investigated by adsorptive stripping voltammetry (ASV) and electrochemical impedance spectroscopy (EIS). The electrochemical behavior of copper, lead, and cadmium at the modified electrodes and factors affecting the preconcentration procedures were also investigated. Detection limits of 5.0, 0.8, 1.0 nM for copper, lead, and cadmium were obtained, respectively. The method is simple, fast, sensitive, and selective, and is successfully applied to soil sample
An Object SLAM Framework for Association, Mapping, and High-Level Tasks
Object SLAM is considered increasingly significant for robot high-level
perception and decision-making. Existing studies fall short in terms of data
association, object representation, and semantic mapping and frequently rely on
additional assumptions, limiting their performance. In this paper, we present a
comprehensive object SLAM framework that focuses on object-based perception and
object-oriented robot tasks. First, we propose an ensemble data association
approach for associating objects in complicated conditions by incorporating
parametric and nonparametric statistic testing. In addition, we suggest an
outlier-robust centroid and scale estimation algorithm for modeling objects
based on the iForest and line alignment. Then a lightweight and object-oriented
map is represented by estimated general object models. Taking into
consideration the semantic invariance of objects, we convert the object map to
a topological map to provide semantic descriptors to enable multi-map matching.
Finally, we suggest an object-driven active exploration strategy to achieve
autonomous mapping in the grasping scenario. A range of public datasets and
real-world results in mapping, augmented reality, scene matching,
relocalization, and robotic manipulation have been used to evaluate the
proposed object SLAM framework for its efficient performance.Comment: Accepted by IEEE Transactions on Robotics(T-RO
CFD-Based Analysis of Wedges Water Entry under Impact Loads
1053-1056The impact on a falling wedge upon water entry is numerically investigated in this paper. After verified by experimental data, the numerical framework is applied for parametric studies on wedges of different drop heights and different deadrise angles to reveal the interaction behaviour between the wedge and water during impact. Pressure distribution on the wedge surface during the water entry shows that the pressure peak moves up along the surface as impact time increases. It is found that the force peak decrease with the increase of drop height and decrease of deadrise angle of the wedge. The peak positions move positively along the timeline as the increase of deadrise angle while the peak force appears just in a small impact time range for a wedge
4-Amino-13-(1-naphthyl)-[2,2]paracyclophane
The title compound [systematic name: 12-amino-42-(1-naphthyl)-1,4(1,4)-dibenzenacyclohexaphane], C26H23N, was synthesized from 4-amino-13-bromo-[2,2]paracyclophane and 1-naphthaleneboronic acid in the presence of 1,4-dioxane. It is a new cyclophane-derived compound which can be regarded as a prospective ligand for asymmetric synthesis and catalysis. The benzene rings of the paracyclophane units are very slightly deformed from planarity as shallow boats
Broader HIV-1 neutralizing antibody responses induced by envelope glycoprotein mutants based on the EIAV attenuated vaccine
<p>Abstract</p> <p>Background</p> <p>In order to induce a potent and cross-reactive neutralizing antibody (nAb), an effective envelope immunogen is crucial for many viral vaccines, including the vaccine for the human immunodeficiency virus (HIV). The Chinese equine infectious anemia virus (EIAV) attenuated vaccine has controlled the epidemic of this virus after its vaccination in over 70 million equine animals during the last 3 decades in China. Data from our past studies demonstrate that the Env protein of this vaccine plays a pivotal role in protecting horses from both homologous and heterogeneous EIAV challenges. Therefore, the amino acid sequence information from the Chinese EIAV attenuated vaccine, in comparison with the parental wild-type EIAV strains, was applied to modify the corresponding region of the envelope glycoprotein of HIV-1 CN54. The direction of the mutations was made towards the amino acids conserved in the two EIAV vaccine strains, distinguishing them from the two wild-type strains. The purpose of the modification was to enhance the immunogenicity of the HIV Env.</p> <p>Results</p> <p>The induced nAb by the modified HIV Env neutralized HIV-1 B and B'/C viruses at the highest titer of 1:270. Further studies showed that a single amino acid change in the C1 region accounts for the substantial enhancement in induction of anti-HIV-1 neutralizing antibodies.</p> <p>Conclusions</p> <p>This study shows that an HIV envelope modified by the information of another lentivirus vaccine induces effective broadly neutralizing antibodies. A single amino acid mutation was found to increase the immunogenicity of the HIV Env.</p
Increased Expression and Altered Methylation of HERVWE1 in the Human Placentas of Smaller Fetuses from Monozygotic, Dichorionic, Discordant Twins
<div><h3>Background</h3><p>The human endogenous retroviral family W, Env(C7), member 1 gene (<em>HERVWE1</em>) is thought to participate in trophoblast cell fusion, and its expression is diminished in the placentas of singleton intrauterine growth-retarded pregnancies. However, there is limited information about the role of <em>HERVWE1</em> in discordant fetal growth in twins. This study was to compare <em>HERVWE1</em> gene expression between the placentas of discordant monozygotic twins and to identify its regulation by methylation.</p> <h3>Methodology/Principal Findings</h3><p>Fetuses from twenty-one pairs of monozygotic, dichorionic, discordant twins were marked as “smaller” or “larger” according to birth weight. Placental <em>HERVWE1</em> mRNA and protein expression profiles were analyzed using quantitative RT-PCR and immunohistochemistry (IHC) staining. Methylation profiles of the <em>HERVWE1</em> promoter region were analyzed using a pyrosequencing assay. DNA methyltransferase (<em>DNMT</em>) transcript levels were analyzed by RT-PCR. 5-methyl cytosine (5-MC) was stained using an immunohistochemical assay. There was a significant negative correlation between <em>HERVWE1</em> mRNA levels and birth weight in twins (<em>P</em><0.01). Whereas the mean methylation level of the <em>HERVWE1</em> promoter region was diminished in the smaller group in discordant twins(<em>P</em><0.01), increased mRNA and protein levels of <em>HERVWE1</em> were found in smaller fetuses compared with larger fetuses in discordant twins(<em>P</em><0.01). There was no significant difference in 5-MC staining intensity between discordant twins (<em>P</em>>0.05). The <em>DNMT3b3</em> mRNA levels in the smaller group were significantly downregulated compared with the larger group in discordant twins(<em>P</em><0.05), whereas the <em>DNMT3b7</em> mRNA levels in the smaller group were significantly upregulated compared with the larger group in discordant twins(<em>P</em><0.05).</p> <h3>Conclusions/Significance</h3><p>In discordant, monozygotic, dichorionic twins, <em>HERVWE1</em> expression was higher in smaller fetuses and lower in larger fetuses. Methylation of the <em>HERVWE1</em> gene promoter region may participate in the regulation of <em>HERVWE1</em> gene expression in discordant twin pregnancies.</p> </div
RNA sequencing from human neutrophils reveals distinct transcriptional differences associated with chronic inflammatory states
Background
The transcriptional complexity of mammalian cells suggests that they have broad abilities to respond to specific environmental stimuli and physiologic contexts. These abilities were not apparent a priori from the structure of mammalian genomes, but have been identified through detailed transcriptome analyses. In this study, we examined the transcriptomes of cells of the innate immune system, human neutrophils, using RNA sequencing (RNAseq).
Methods
We sequenced poly-A RNA from nine individual samples corresponding to specific phenotypes: three children with active, untreated juvenile idiopathic arthritis (JIA)(AD), three children with the same disease whose disease was inactive on medication (CRM), and three children with cystic fibrosis (CF).
Results
We demonstrate that transcriptomes of neutrophils, typically considered non-specific in their responses and functions, display considerable specificity in their transcriptional repertoires dependent on the pathologic context, and included genes, gene isoforms, and long non-coding RNA transcripts. Furthermore, despite the small sample numbers, these findings demonstrate the potential of RNAseq approaches to biomarker development in rheumatic diseases.
Conclusions
These data demonstrate the capacity of cells previously considered non-specific in function to adapt their transcriptomes to specific biologic contexts. These data also provide insight into previously unrecognized pathological pathways and show considerable promise for elucidating disease and disease-state specific regulatory networks
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