Recent empirical evidence suggests that the Weston-Watkins support vector machine is among the be... more Recent empirical evidence suggests that the Weston-Watkins support vector machine is among the best performing multiclass extensions of the binary SVM. Current state-of-the-art solvers repeatedly solve a particular subproblem approximately using an iterative strategy. In this work, we propose an algorithm that solves the subproblem exactly using a novel reparametrization of the Weston-Watkins dual problem. For linear WW-SVMs, our solver shows significant speed-up over the state-of-the-art solver when the number of classes is large. Our exact subproblem solver also allows us to prove linear convergence of the overall solver.
Multiclass extensions of the support vector machine (SVM) have been formulated in a variety of wa... more Multiclass extensions of the support vector machine (SVM) have been formulated in a variety of ways. A recent empirical comparison of nine such formulations [Doǧan et al. 2016] recommends the variant proposed by Weston and Watkins (WW), despite the fact that the WW-hinge loss is not calibrated with respect to the 0-1 loss. In this work we introduce a novel discrete loss function for multiclass classification, the ordered partition loss, and prove that the WW-hinge loss is calibrated with respect to this loss. We also argue that the ordered partition loss is maximally informative among discrete losses satisfying this property. Finally, we apply our theory to justify the empirical observation made by Doǧan et al. that the WW-SVM can work well even under massive label noise, a challenging setting for multiclass SVMs.
To achieve enhanced physical stability of poly(ethylene glycol)-poly(d,l-lactide) polymeric micel... more To achieve enhanced physical stability of poly(ethylene glycol)-poly(d,l-lactide) polymeric micelles (PEG-PDLLA PMs), a mixture of methoxy PEG-PDLLA-polyglutamate (mPEG-PDLLA-PLG) and mPEG-PDLLA-poly(l-lysine) (mPEG-PDLLA-PLL) copolymers was applied to self-assembled stable micelles with polyion-stabilized cores. Prior to micelle preparation, the synthetic copolymers were characterized by H-nuclear magnetic resonance (NMR) and infrared spectroscopy (IR), and their molecular weights were calculated by H-NMR and gel permeation chromatography (GPC). Dialysis was used to prepare PMs with deoxypodophyllotoxin (DPT). Transmission electron microscopy (TEM) images showed that DPT polyion complex micelles (DPT-PCMs) were spherical, with uniform distribution and particle sizes of 36.3±0.8 nm. In addition, compared with nonpeptide-modified DPT-PMs, the stability of DPT-PCMs was significantly improved under various temperatures. In the meantime, the pH sensitivity induced by charged peptides al...
Core-crosslinked pullulan nanoparticles (Pull-LA-CLNPs) were synthesized by the reduction-sensiti... more Core-crosslinked pullulan nanoparticles (Pull-LA-CLNPs) were synthesized by the reduction-sensitive strategy for paclitaxel (PTX) delivery. Pull-LA-CLNPs showed high stability against extensive dilution, high salt concentration and organic solvent. In vitro drug release study showed that PTX release from Pull-LA-NPs at pH 7.4 and 5.4 was significantly influenced by addition of DTT. In cytotoxicity assay, PTX loaded Pull-LA-CLNPs showed a low IC50 at 0.51μg/mL. Asialoglycoprotein receptor (ASGPR) competitive inhibition and intracellular distribution studies performed by flow cytometer, fluorescence microscope and confocal laser scanning microscopy (CLSM) showed that Pull-LA-NPs could be efficiently taken up by the cells via ASGPR-mediated endocytosis and mainly distributed in cytoplasm. From in vivo pharmacokinetics study, Pull-LA-CLNPs displayed the longest systemic retention time and slowest plasma elimination rate in comparison with Taxol and Pull-LA-NCLNPs. In conclusion, Pull-LA...
Recent empirical evidence suggests that the Weston-Watkins support vector machine is among the be... more Recent empirical evidence suggests that the Weston-Watkins support vector machine is among the best performing multiclass extensions of the binary SVM. Current state-of-the-art solvers repeatedly solve a particular subproblem approximately using an iterative strategy. In this work, we propose an algorithm that solves the subproblem exactly using a novel reparametrization of the Weston-Watkins dual problem. For linear WW-SVMs, our solver shows significant speed-up over the state-of-the-art solver when the number of classes is large. Our exact subproblem solver also allows us to prove linear convergence of the overall solver.
Multiclass extensions of the support vector machine (SVM) have been formulated in a variety of wa... more Multiclass extensions of the support vector machine (SVM) have been formulated in a variety of ways. A recent empirical comparison of nine such formulations [Doǧan et al. 2016] recommends the variant proposed by Weston and Watkins (WW), despite the fact that the WW-hinge loss is not calibrated with respect to the 0-1 loss. In this work we introduce a novel discrete loss function for multiclass classification, the ordered partition loss, and prove that the WW-hinge loss is calibrated with respect to this loss. We also argue that the ordered partition loss is maximally informative among discrete losses satisfying this property. Finally, we apply our theory to justify the empirical observation made by Doǧan et al. that the WW-SVM can work well even under massive label noise, a challenging setting for multiclass SVMs.
To achieve enhanced physical stability of poly(ethylene glycol)-poly(d,l-lactide) polymeric micel... more To achieve enhanced physical stability of poly(ethylene glycol)-poly(d,l-lactide) polymeric micelles (PEG-PDLLA PMs), a mixture of methoxy PEG-PDLLA-polyglutamate (mPEG-PDLLA-PLG) and mPEG-PDLLA-poly(l-lysine) (mPEG-PDLLA-PLL) copolymers was applied to self-assembled stable micelles with polyion-stabilized cores. Prior to micelle preparation, the synthetic copolymers were characterized by H-nuclear magnetic resonance (NMR) and infrared spectroscopy (IR), and their molecular weights were calculated by H-NMR and gel permeation chromatography (GPC). Dialysis was used to prepare PMs with deoxypodophyllotoxin (DPT). Transmission electron microscopy (TEM) images showed that DPT polyion complex micelles (DPT-PCMs) were spherical, with uniform distribution and particle sizes of 36.3±0.8 nm. In addition, compared with nonpeptide-modified DPT-PMs, the stability of DPT-PCMs was significantly improved under various temperatures. In the meantime, the pH sensitivity induced by charged peptides al...
Core-crosslinked pullulan nanoparticles (Pull-LA-CLNPs) were synthesized by the reduction-sensiti... more Core-crosslinked pullulan nanoparticles (Pull-LA-CLNPs) were synthesized by the reduction-sensitive strategy for paclitaxel (PTX) delivery. Pull-LA-CLNPs showed high stability against extensive dilution, high salt concentration and organic solvent. In vitro drug release study showed that PTX release from Pull-LA-NPs at pH 7.4 and 5.4 was significantly influenced by addition of DTT. In cytotoxicity assay, PTX loaded Pull-LA-CLNPs showed a low IC50 at 0.51μg/mL. Asialoglycoprotein receptor (ASGPR) competitive inhibition and intracellular distribution studies performed by flow cytometer, fluorescence microscope and confocal laser scanning microscopy (CLSM) showed that Pull-LA-NPs could be efficiently taken up by the cells via ASGPR-mediated endocytosis and mainly distributed in cytoplasm. From in vivo pharmacokinetics study, Pull-LA-CLNPs displayed the longest systemic retention time and slowest plasma elimination rate in comparison with Taxol and Pull-LA-NCLNPs. In conclusion, Pull-LA...
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Papers by yutong wang