24 research outputs found
One for All, All for One: Learning and Transferring User Embeddings for Cross-Domain Recommendation
Cross-domain recommendation is an important method to improve recommender
system performance, especially when observations in target domains are sparse.
However, most existing techniques focus on single-target or dual-target
cross-domain recommendation (CDR) and are hard to be generalized to CDR with
multiple target domains. In addition, the negative transfer problem is
prevalent in CDR, where the recommendation performance in a target domain may
not always be enhanced by knowledge learned from a source domain, especially
when the source domain has sparse data. In this study, we propose CAT-ART, a
multi-target CDR method that learns to improve recommendations in all
participating domains through representation learning and embedding transfer.
Our method consists of two parts: a self-supervised Contrastive AuToencoder
(CAT) framework to generate global user embeddings based on information from
all participating domains, and an Attention-based Representation Transfer (ART)
framework which transfers domain-specific user embeddings from other domains to
assist with target domain recommendation. CAT-ART boosts the recommendation
performance in any target domain through the combined use of the learned global
user representation and knowledge transferred from other domains, in addition
to the original user embedding in the target domain. We conducted extensive
experiments on a collected real-world CDR dataset spanning 5 domains and
involving a million users. Experimental results demonstrate the superiority of
the proposed method over a range of prior arts. We further conducted ablation
studies to verify the effectiveness of the proposed components. Our collected
dataset will be open-sourced to facilitate future research in the field of
multi-domain recommender systems and user modeling.Comment: 9 pages, accepted by WSDM 202
Parity Splitting and Polarized-Illumination Selection of Plasmonic Higher-Order Topological States
Topological states, originated from interactions between internal degree of
freedoms (like spin and orbital) in each site and crystalline symmetries, offer
a new paradigm to manipulate electrons and classical waves. The accessibility
of spin degree of freedom has motivated much attention on spin-related
topological physics. However, intriguing topological physics related to
atomic-orbital parity, another binary degree of freedom, have not been
exploited since accessing approaches on atomic orbitals are not well developed.
Here, we theoretically discover spectral splitting of
atomic-orbital-parity-dependent second-order topological states on a
designer-plasmonic Kagome metasurface, and experimentally demonstrate it by
exploiting the easy controllability of metaatoms. Unlike previous
demonstrations on Hermitian higher-order topological insulators, radiative
non-Hermicity of the metasurface enables far-field access into
metaatomic-orbital-parity-dependent topological states with polarized
illuminations. The atomic-orbital parity degree of freedom may generate more
intriguing topological physics by interacting with different crystalline
symmetries, and promise applications in polarization-multiplexing topological
lasing and quantum emitters.Comment: 19 pages, 4 figure
On the origin and evolution of RNA editing in metazoans
Extensive adenosine-to-inosine (A-to-I) editing of nuclear-transcribed mRNAs is the hallmark of metazoan transcriptional regulation. Here, by profiling the RNA editomes of 22 species that cover major groups of Holozoa, we provide substantial evidence supporting A-to-I mRNA editing as a regulatory innovation originating in the last common ancestor of extant metazoans. This ancient biochemistry process is preserved in most extant metazoan phyla and primarily targets endogenous double-stranded RNA (dsRNA) formed by evolutionarily young repeats. We also find intermolecular pairing of sense-antisense transcripts as an important mechanism for forming dsRNA substrates for A-to-I editing in some but not all lineages. Likewise, recoding editing is rarely shared across lineages but preferentially targets genes involved in neural and cytoskeleton systems in bilaterians. We conclude that metazoan A-to-I editing might first emerge as a safeguard mechanism against repeat-derived dsRNA and was later co-opted into diverse biological processes due to its mutagenic nature
Stereoselective Synthesis of 1,3-Amino Alcohols by the Pd-Catalyzed Cyclization of Trichloroacetimidates
The
synthesis of 4-vinyl-5,6-dihydro-1,3-oxazines, precursors of
1,3-amino alcohols, using the palladium-catalyzed cyclization of trichloroacetimidates
is reported. The reaction favors the formation of the
4,6-<i>cis</i>-isomers with up to >20:1 diastereoselectivity.
Chemoselective hydrolysis of the resulting 5,6-dihydro-1,3-oxazines
was also investigated
Total Synthesis of (±)-Cephalosol
A concise and efficient total synthesis of (±)-cephalosol has been completed (5 steps from known ester <b>5</b>, 39% overall yield), featuring a Cu(II)-promoted haloisocoumarin formation and sequential Suzuki cross-coupling/intramolecular oxo-Michael addition
Inhibition of PGE2 in Subchondral Bone Attenuates Osteoarthritis
Aberrant subchondral bone architecture is a crucial driver of the pathological progression of osteoarthritis, coupled with increased sensory innervation. The sensory PGE2/EP4 pathway is involved in the regulation of bone mass accrual by the induction of differentiation of mesenchymal stromal cells. This study aimed to clarify whether the sensory PGE2/EP4 pathway induces aberrant structural alteration of subchondral bone in osteoarthritis. Destabilization of the medial meniscus (DMM) using a mouse model was combined with three approaches: the treatment of celecoxib, capsaicin, and sensory nerve-specific prostaglandin E2 receptor 4 (EP4)-knockout mice. Cartilage degeneration, subchondral bone architecture, PGE2 levels, distribution of sensory nerves, the number of osteoprogenitors, and pain-related behavior in DMM mice were assessed. Serum and tissue PGE2 levels and subchondral bone architecture in a human sample were measured. Increased PGE2 is closely related to subchondral bone’s abnormal microstructure in humans and mice. Elevated PGE2 concentration in subchondral bone that is mainly derived from osteoblasts occurs in early-stage osteoarthritis, preceding articular cartilage degeneration in mice. The decreased PGE2 levels by the celecoxib or sensory denervation by capsaicin attenuate the aberrant alteration of subchondral bone architecture, joint degeneration, and pain. Selective EP4 receptor knockout of the sensory nerve attenuates the aberrant formation of subchondral bone and facilitates the prevention of cartilage degeneration in DMM mice. Excessive PGE2 in subchondral bone caused a pathological alteration to subchondral bone in osteoarthritis and maintaining the physiological level of PGE2 could potentially be used as an osteoarthritis treatment
Total Synthesis of Aquatolide: Wolff Ring Contraction and Late-Stage Nozaki–Hiyama–Kishi Medium-Ring Formation
A total synthesis
of the highly strained natural product aquatolide
has been achieved. The synthesis featured a photoinduced Wolff ring
contraction reaction for the construction of bicyclo[2.1.1]Âhexane
from diazo compound with a bicyclo[2.2.1]Âheptane skeleton. The eight-membered
enone was built by a late-stage intramolecular Nozaki–Hiyama–Kishi
vinylation reaction of steric bulky vinyl iodide and aldehyde
Realization of all-band-flat photonic lattices
Flatbands play an important role in correlated quantum matter and have novel
applications in photonic lattices. Synthetic magnetic fields and destructive
interference in lattices are traditionally used to obtain flatbands. However,
such methods can only obtain a few flatbands with most bands remaining
dispersive. Here we realize all-band-flat photonic lattices of an arbitrary
size by precisely controlling the coupling strengths between lattice sites to
mimic those in Fock-state lattices. This allows us to go beyond the
perturbative regime of strain engineering and group all eigenmodes in
flatbands, which simultaneously achieves high band flatness and large usable
bandwidth. We map out the distribution of each flatband in the lattices and
selectively excite the eigenmodes with different chiralities. Our method paves
a new way in controlling band structure and topology of photonic lattices
Visualization 1: Simultaneous two-color stimulated Raman scattering microscopy by adding a fiber amplifier to a 2 ps OPO-based SRS microscope
Epi-SRS in vivo mouse skin imaging. Originally published in Optics Letters on 01 February 2017 (ol-42-3-523