9 research outputs found
Building a Winning Team: Selecting Source Model Ensembles using a Submodular Transferability Estimation Approach
Estimating the transferability of publicly available pretrained models to a
target task has assumed an important place for transfer learning tasks in
recent years. Existing efforts propose metrics that allow a user to choose one
model from a pool of pre-trained models without having to fine-tune each model
individually and identify one explicitly. With the growth in the number of
available pre-trained models and the popularity of model ensembles, it also
becomes essential to study the transferability of multiple-source models for a
given target task. The few existing efforts study transferability in such
multi-source ensemble settings using just the outputs of the classification
layer and neglect possible domain or task mismatch. Moreover, they overlook the
most important factor while selecting the source models, viz., the cohesiveness
factor between them, which can impact the performance and confidence in the
prediction of the ensemble. To address these gaps, we propose a novel Optimal
tranSport-based suBmOdular tRaNsferability metric (OSBORN) to estimate the
transferability of an ensemble of models to a downstream task. OSBORN
collectively accounts for image domain difference, task difference, and
cohesiveness of models in the ensemble to provide reliable estimates of
transferability. We gauge the performance of OSBORN on both image
classification and semantic segmentation tasks. Our setup includes 28 source
datasets, 11 target datasets, 5 model architectures, and 2 pre-training
methods. We benchmark our method against current state-of-the-art metrics
MS-LEEP and E-LEEP, and outperform them consistently using the proposed
approach.Comment: To appear at ICCV 202
MADG: Margin-based Adversarial Learning for Domain Generalization
Domain Generalization (DG) techniques have emerged as a popular approach to
address the challenges of domain shift in Deep Learning (DL), with the goal of
generalizing well to the target domain unseen during the training. In recent
years, numerous methods have been proposed to address the DG setting, among
which one popular approach is the adversarial learning-based methodology. The
main idea behind adversarial DG methods is to learn domain-invariant features
by minimizing a discrepancy metric. However, most adversarial DG methods use
0-1 loss based divergence metric. In contrast,
the margin loss-based discrepancy metric has the following advantages: more
informative, tighter, practical, and efficiently optimizable. To mitigate this
gap, this work proposes a novel adversarial learning DG algorithm, MADG,
motivated by a margin loss-based discrepancy metric. The proposed MADG model
learns domain-invariant features across all source domains and uses adversarial
training to generalize well to the unseen target domain. We also provide a
theoretical analysis of the proposed MADG model based on the unseen target
error bound. Specifically, we construct the link between the source and unseen
domains in the real-valued hypothesis space and derive the generalization bound
using margin loss and Rademacher complexity. We extensively experiment with the
MADG model on popular real-world DG datasets, VLCS, PACS, OfficeHome,
DomainNet, and TerraIncognita. We evaluate the proposed algorithm on
DomainBed's benchmark and observe consistent performance across all the
datasets
Downregulation of RWA genes in hybrid aspen affects xylan acetylation and wood saccharification
High acetylation of angiosperm wood hinders its conversion to sugars by glycoside hydrolases, subsequent ethanol fermentation and (hence) its use for biofuel production. We studied the REDUCED WALL ACETYLATION (RWA) gene family of the hardwood model Populus to evaluate its potential for improving saccharification. The family has two clades, AB and CD, containing two genes each. All four genes are expressed in developing wood but only RWA-A and -B are activated by master switches of the secondary cell wall PtNST1 and PtMYB21. Histochemical analysis of promoter:: GUS lines in hybrid aspen (Populus tremula x tremuloides) showed activation of RWA-A and -B promoters in the secondary wall formation zone, while RWA-C and -D promoter activity was diffuse. Ectopic downregulation of either clade reduced wood xylan and xyloglucan acetylation. Suppressing both clades simultaneously using the wood-specific promoter reduced wood acetylation by 25% and decreased acetylation at position 2 of Xylp in the dimethyl sulfoxide-extracted xylan. This did not affect plant growth but decreased xylose and increased glucose contents in the noncellulosic monosaccharide fraction, and increased glucose and xylose yields of wood enzymatic hydrolysis without pretreatment. Both RWA clades regulate wood xylan acetylation in aspen and are promising targets to improve wood saccharification.Peer reviewe