46 research outputs found
Adversarial Personalized Ranking for Recommendation
Item recommendation is a personalized ranking task. To this end, many
recommender systems optimize models with pairwise ranking objectives, such as
the Bayesian Personalized Ranking (BPR). Using matrix Factorization (MF) ---
the most widely used model in recommendation --- as a demonstration, we show
that optimizing it with BPR leads to a recommender model that is not robust. In
particular, we find that the resultant model is highly vulnerable to
adversarial perturbations on its model parameters, which implies the possibly
large error in generalization.
To enhance the robustness of a recommender model and thus improve its
generalization performance, we propose a new optimization framework, namely
Adversarial Personalized Ranking (APR). In short, our APR enhances the pairwise
ranking method BPR by performing adversarial training. It can be interpreted as
playing a minimax game, where the minimization of the BPR objective function
meanwhile defends an adversary, which adds adversarial perturbations on model
parameters to maximize the BPR objective function. To illustrate how it works,
we implement APR on MF by adding adversarial perturbations on the embedding
vectors of users and items. Extensive experiments on three public real-world
datasets demonstrate the effectiveness of APR --- by optimizing MF with APR, it
outperforms BPR with a relative improvement of 11.2% on average and achieves
state-of-the-art performance for item recommendation. Our implementation is
available at: https://github.com/hexiangnan/adversarial_personalized_ranking.Comment: SIGIR 201
IntersectGAN: Learning Domain Intersection for Generating Images with Multiple Attributes
Generative adversarial networks (GANs) have demonstrated great success in
generating various visual content. However, images generated by existing GANs
are often of attributes (e.g., smiling expression) learned from one image
domain. As a result, generating images of multiple attributes requires many
real samples possessing multiple attributes which are very resource expensive
to be collected. In this paper, we propose a novel GAN, namely IntersectGAN, to
learn multiple attributes from different image domains through an intersecting
architecture. For example, given two image domains and with certain
attributes, the intersection denotes a new domain where images
possess the attributes from both and domains. The proposed
IntersectGAN consists of two discriminators and to distinguish
between generated and real samples of different domains, and three generators
where the intersection generator is trained against both discriminators. And an
overall adversarial loss function is defined over three generators. As a
result, our proposed IntersectGAN can be trained on multiple domains of which
each presents one specific attribute, and eventually eliminates the need of
real sample images simultaneously possessing multiple attributes. By using the
CelebFaces Attributes dataset, our proposed IntersectGAN is able to produce
high quality face images possessing multiple attributes (e.g., a face with
black hair and a smiling expression). Both qualitative and quantitative
evaluations are conducted to compare our proposed IntersectGAN with other
baseline methods. Besides, several different applications of IntersectGAN have
been explored with promising results
The association of N-palmitoylethanolamine with the FAAH inhibitor URB597 impairs melanoma growth through a supra-additive action
<p>Abstract</p> <p>Background</p> <p>The incidence of melanoma is considerably increasing worldwide. Frequent failing of classical treatments led to development of novel therapeutic strategies aiming at managing advanced forms of this skin cancer. Additionally, the implication of the endocannabinoid system in malignancy is actively investigated.</p> <p>Methods</p> <p>We investigated the cytotoxicity of endocannabinoids and their hydrolysis inhibitors on the murine B16 melanoma cell line using a MTT test. Enzyme and receptor expression was measured by RT-PCR and enzymatic degradation of endocannabinoids using radiolabeled substrates. Cell death was assessed by Annexin-V/Propidium iodine staining. Tumors were induced in C57BL/6 mice by s.c. flank injection of B16 melanoma cells. Mice were injected i.p. for six days with vehicle or treatment, and tumor size was measured each day and weighted at the end of the treatment. Haematoxylin-Eosin staining and TUNEL assay were performed to quantify necrosis and apoptosis in the tumor and endocannabinoid levels were quantified by HPLC-MS. Tube formation assay and CD31 immunostaining were used to evaluate the antiangiogenic effects of the treatments.</p> <p>Results</p> <p>The <it>N</it>-arachidonoylethanolamine (anandamide, AEA), 2-arachidonoylglycerol and <it>N</it>- palmitoylethanolamine (PEA) reduced viability of B16 cells. The association of PEA with the fatty acid amide hydrolase (FAAH) inhibitor URB597 considerably reduced cell viability consequently to an inhibition of PEA hydrolysis and an increase of PEA levels. The increase of cell death observed with this combination of molecules was confirmed in vivo where only co-treatment with both PEA and URB597 led to decreased melanoma progression. The antiproliferative action of the treatment was associated with an elevation of PEA levels and larger necrotic regions in the tumor.</p> <p>Conclusions</p> <p>This study suggests the interest of targeting the endocannabinoid system in the management of skin cancer and underlines the advantage of associating endocannabinoids with enzymatic hydrolysis inhibitors. This may contribute to the improvement of long-term palliation or cure of melanoma.</p