52 research outputs found
Diffusion Augmentation for Sequential Recommendation
Sequential recommendation (SRS) has become the technical foundation in many
applications recently, which aims to recommend the next item based on the
user's historical interactions. However, sequential recommendation often faces
the problem of data sparsity, which widely exists in recommender systems.
Besides, most users only interact with a few items, but existing SRS models
often underperform these users. Such a problem, named the long-tail user
problem, is still to be resolved. Data augmentation is a distinct way to
alleviate these two problems, but they often need fabricated training
strategies or are hindered by poor-quality generated interactions. To address
these problems, we propose a Diffusion Augmentation for Sequential
Recommendation (DiffuASR) for a higher quality generation. The augmented
dataset by DiffuASR can be used to train the sequential recommendation models
directly, free from complex training procedures. To make the best of the
generation ability of the diffusion model, we first propose a diffusion-based
pseudo sequence generation framework to fill the gap between image and sequence
generation. Then, a sequential U-Net is designed to adapt the diffusion noise
prediction model U-Net to the discrete sequence generation task. At last, we
develop two guide strategies to assimilate the preference between generated and
origin sequences. To validate the proposed DiffuASR, we conduct extensive
experiments on three real-world datasets with three sequential recommendation
models. The experimental results illustrate the effectiveness of DiffuASR. As
far as we know, DiffuASR is one pioneer that introduce the diffusion model to
the recommendation
RePAST: A ReRAM-based PIM Accelerator for Second-order Training of DNN
The second-order training methods can converge much faster than first-order
optimizers in DNN training. This is because the second-order training utilizes
the inversion of the second-order information (SOI) matrix to find a more
accurate descent direction and step size. However, the huge SOI matrices bring
significant computational and memory overheads in the traditional architectures
like GPU and CPU. On the other side, the ReRAM-based process-in-memory (PIM)
technology is suitable for the second-order training because of the following
three reasons: First, PIM's computation happens in memory, which reduces data
movement overheads; Second, ReRAM crossbars can compute SOI's inversion in
time; Third, if architected properly, ReRAM crossbars can
perform matrix inversion and vector-matrix multiplications which are important
to the second-order training algorithms.
Nevertheless, current ReRAM-based PIM techniques still face a key challenge
for accelerating the second-order training. The existing ReRAM-based matrix
inversion circuitry can only support 8-bit accuracy matrix inversion and the
computational precision is not sufficient for the second-order training that
needs at least 16-bit accurate matrix inversion. In this work, we propose a
method to achieve high-precision matrix inversion based on a proven 8-bit
matrix inversion (INV) circuitry and vector-matrix multiplication (VMM)
circuitry. We design \archname{}, a ReRAM-based PIM accelerator architecture
for the second-order training. Moreover, we propose a software mapping scheme
for \archname{} to further optimize the performance by fusing VMM and INV
crossbar. Experiment shows that \archname{} can achieve an average of
115.8/11.4 speedup and 41.9/12.8energy saving
compared to a GPU counterpart and PipeLayer on large-scale DNNs.Comment: 13pages, 13 figure
2D materials for conducting holes from grain boundaries in perovskite solar cells
Grain boundaries in organic-inorganic halide perovskite solar cells (PSCs) have been found to be detrimental to the photovoltaic performance of devices. Here, we develop a unique approach to overcome this problem by modifying the edges of perovskite grain boundaries with flakes of high-mobility two-dimensional (2D) materials via a convenient solution process. A synergistic effect between the 2D flakes and perovskite grain boundaries is observed for the first time, which can significantly enhance the performance of PSCs. We find that the 2D flakes can conduct holes from the grain boundaries to the hole transport layers in PSCs, thereby making hole channels in the grain boundaries of the devices. Hence, 2D flakes with high carrier mobilities and short distances to grain boundaries can induce a more pronounced performance enhancement of the devices. This work presents a cost-effective strategy for improving the performance of PSCs by using high-mobility 2D materials
The water lily genome and the early evolution of flowering plants
Water lilies belong to the angiosperm order Nymphaeales. Amborellales,
Nymphaeales and Austrobaileyales together form the so-called ANA-grade of
angiosperms, which are extant representatives of lineages that diverged the earliest
from the lineage leading to the extant mesangiosperms1–3. Here we report the
409-megabase genome sequence of the blue-petal water lily (Nymphaea colorata).
Our phylogenomic analyses support Amborellales and Nymphaeales as successive
sister lineages to all other extant angiosperms. The N. colorata genome and 19 other
water lily transcriptomes reveal a Nymphaealean whole-genome duplication event,
which is shared by Nymphaeaceae and possibly Cabombaceae. Among the genes
retained from this whole-genome duplication are homologues of genes that regulate
flowering transition and flower development. The broad expression of homologues of
floral ABCE genes in N. colorata might support a similarly broadly active ancestral
ABCE model of floral organ determination in early angiosperms. Water lilies have
evolved attractive floral scents and colours, which are features shared with
mesangiosperms, and we identified their putative biosynthetic genes in N. colorata.
The chemical compounds and biosynthetic genes behind floral scents suggest that
they have evolved in parallel to those in mesangiosperms. Because of its unique
phylogenetic position, the N. colorata genome sheds light on the early evolution of
angiosperms.Supplementary Tables: This file contains Supplementary Tables 1-21.National Natural Science Foundation of China, the open funds of the State Key Laboratory of Crop Genetics and Germplasm Enhancement (ZW201909) and State Key Laboratory of Tree Genetics and Breeding, the Fujian provincial government in China, the European Union Seventh Framework Programme (FP7/2007-2013) under European Research Council Advanced Grant Agreement and the Special Research Fund of Ghent University.http://www.nature.com/naturecommunicationsam2021BiochemistryGeneticsMicrobiology and Plant Patholog
Synthesis of ethyl 4-(2-fluoro-4-nitrophenoxy) picolinate
Cancer has seriously affected people's production and life. The appearance of anti-cancer drugs has brought good news to people. Ethyl 4-(2-fluoro-4-nitrophenoxy) picolinate is an important basic skeleton of a small molecule inhibitor of c-Met and a major intermediate in cancer therapy. A rapid and efficient method for the synthesis of compound 8 was established. Compound 8 was synthesized from picolinic acid by acylation and substitution. These steps were weight gain reaction. The synthesis method was optimized and the structure was confirmed by hydrogen NMR spectroscopy
Synthesis of ethyl 4-(2-fluoro-4-nitrophenoxy) picolinate
Cancer has seriously affected people's production and life. The appearance of anti-cancer drugs has brought good news to people. Ethyl 4-(2-fluoro-4-nitrophenoxy) picolinate is an important basic skeleton of a small molecule inhibitor of c-Met and a major intermediate in cancer therapy. A rapid and efficient method for the synthesis of compound 8 was established. Compound 8 was synthesized from picolinic acid by acylation and substitution. These steps were weight gain reaction. The synthesis method was optimized and the structure was confirmed by hydrogen NMR spectroscopy
Design, Synthesis, Activity and Docking Study of Sorafenib Analogs Bearing Sulfonylurea Unit
Two series of novel sorafenib analogs containing a sulfonylurea unit were synthesized and their chemical structures were confirmed by 1H-NMR, 13C-NMR, MS spectrum and elemental analysis. The synthesized compounds were evaluated for the cytotoxicity against A549, Hela, MCF-7, and PC-3 cancer cell lines. Some of the compounds showed moderate cytotoxic activity, especially compounds 1-(2,4-difluorophenylsulfonyl)-3-(4-(2-(methylcarbamoyl)pyridin-4-yloxy)phenyl)urea (6c) and 1-(4-bromophenylsulfonyl)-3-(4-(2-(methylcarbamoyl)pyridin-4-yloxy)phenyl)urea (6f) with the IC50 values against four cancer cell lines ranging from 16.54 ± 1.22 to 63.92 ± 1.81 μM, respectively. Inhibitory rates against vascular endothelial growth factor receptor-2 (VEGFR2/KDR) kinase at 10 μM of target compounds were further carried out in this paper in order to investigate the target of these compounds. Structure-activity relationships (SARs) and docking studies indicated that the sulfonylurea unit was important to these kinds of compounds. None of the substitutions in the phenoxy group and small halogen atoms such as 2,4-difluoro substitution of the aryl group contributed to the activity. The results suggested that sulfonylurea sorafenib analogs are worthy of further study
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