300 research outputs found
Temporary trade barriers and enterprise export market changes: evidence from China
In theory, previous studies believed that the export market of
enterprises was homogeneous. There is no difference in each
export market, which is obviously inconsistent with the actual
trade situation. This paper divides the export market of enterprises
into main export market and secondary export market
according to the export status, explores the export changes of
enterprises to the main export market and secondary export market
respectively when the temporary trade barriers of the main
export market to the trade exporting country are raised. This
paper focuses on the impact of the main export market on the
anti-dumping degree, countervailing level and the improvement
of trade safeguard measures on the export conversion of enterprises
between the main and secondary markets. The research
shows that the increase of the anti-dumping degree of the main
market against the trade exporting countries will lead to the
higher probability of role exchange between the main and secondary
markets; The countervailing level of the main market
against the trade exporting countries rises, and the export of
enterprises is more likely to turn to the secondary market; The
greater the trade safeguard measures in the main market, the
more likely the secondary market will become the main marke
In Situ Mineralization of Magnetite Nanoparticles in Chitosan Hydrogel
Based on chelation effect between iron ions and amino groups of chitosan, in situ mineralization of magnetite nanoparticles in chitosan hydrogel under ambient conditions was proposed. The chelation effect between iron ions and amino groups in CS–Fe complex, which led to that chitosan hydrogel exerted a crucial control on the magnetite mineralization, was proved by X-ray photoelectron spectrum. The composition, morphology and size of the mineralized magnetite nanoparticles were characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy and thermal gravity. The mineralized nanoparticles were nonstoichiometric magnetite with a unit formula of Fe2.85O4and coated by a thin layer of chitosan. The mineralized magnetite nanoparticles with mean diameter of 13 nm dispersed in chitosan hydrogel uniformly. Magnetization measurement indicated that superparamagnetism behavior was exhibited. These magnetite nanoparticles mineralized in chitosan hydrogel have potential applications in the field of biotechnology. Moreover, this method can also be used to synthesize other kinds of inorganic nanoparticles, such as ZnO, Fe2O3and hydroxyapatite
LLMaAA: Making Large Language Models as Active Annotators
Prevalent supervised learning methods in natural language processing (NLP)
are notoriously data-hungry, which demand large amounts of high-quality
annotated data. In practice, acquiring such data is a costly endeavor.
Recently, the superior few-shot performance of large language models (LLMs) has
propelled the development of dataset generation, where the training data are
solely synthesized from LLMs. However, such an approach usually suffers from
low-quality issues, and requires orders of magnitude more labeled data to
achieve satisfactory performance. To fully exploit the potential of LLMs and
make use of massive unlabeled data, we propose LLMaAA, which takes LLMs as
annotators and puts them into an active learning loop to determine what to
annotate efficiently. To learn robustly with pseudo labels, we optimize both
the annotation and training processes: (1) we draw k-NN examples from a small
demonstration pool as in-context examples, and (2) we adopt the example
reweighting technique to assign training samples with learnable weights.
Compared with previous approaches, LLMaAA features both efficiency and
reliability. We conduct experiments and analysis on two classic NLP tasks,
named entity recognition and relation extraction. With LLMaAA, task-specific
models trained from LLM-generated labels can outperform the teacher within only
hundreds of annotated examples, which is much more cost-effective than other
baselines.Comment: Findings of EMNLP 2023 camera read
BASAR:Black-box Attack on Skeletal Action Recognition
Skeletal motion plays a vital role in human activity recognition as either an
independent data source or a complement. The robustness of skeleton-based
activity recognizers has been questioned recently, which shows that they are
vulnerable to adversarial attacks when the full-knowledge of the recognizer is
accessible to the attacker. However, this white-box requirement is overly
restrictive in most scenarios and the attack is not truly threatening. In this
paper, we show that such threats do exist under black-box settings too. To this
end, we propose the first black-box adversarial attack method BASAR. Through
BASAR, we show that adversarial attack is not only truly a threat but also can
be extremely deceitful, because on-manifold adversarial samples are rather
common in skeletal motions, in contrast to the common belief that adversarial
samples only exist off-manifold. Through exhaustive evaluation and comparison,
we show that BASAR can deliver successful attacks across models, data, and
attack modes. Through harsh perceptual studies, we show that it achieves
effective yet imperceptible attacks. By analyzing the attack on different
activity recognizers, BASAR helps identify the potential causes of their
vulnerability and provides insights on what classifiers are likely to be more
robust against attack. Code is available at
https://github.com/realcrane/BASAR-Black-box-Attack-on-Skeletal-Action-Recognition.Comment: Accepted in CVPR 202
The oligopeptide ABC transporter OppA4 negatively regulates the virulence factor OspC production of the Lyme disease pathogen
Borrelia burgdorferi sensu lato, the agent of Lyme disease, exists in nature through a complex enzootic life cycle that involves both ticks and mammals. The B. burgdorferi genome encodes five Oligopeptide ABC transporters (Opp) that are predicted to be involve in transport of various nutrients. Previously, it was reported that OppA5 is important for the optimal production of OspC, a major virulence factor of B. burgdorferi. In this study, possible role of another Oligopeptide ABC transporter, OppA4 in ospC expression was investigated by construction of an oppA4 deletion mutant and the complemented strain. Inactivation of oppA4 resulted an increased production of OspC, suggesting that OppA4 has a negative impact on ospC expression. Expression of ospC is controlled by Rrp2-RpoN-RpoS, the central pathway essential for mammal infection. We showed that increased ospC expression in the oppA4 mutant was due to an increased rpoS expression. We then further investigated how OppA4 negatively regulates this pathway. Two regulators, BosR and BadR, are known to positively and negatively, respectively, regulate the Rrp2-RpoN-RpoS pathway. We found that deletion of oppA4 resulted in an increased level of BosR. Previous reports showed that bosR is mainly regulated at the post-transcriptional level by other factors. However, OppA4 appears to negatively regulate bosR expression at the transcriptional level. The finding of OppA4 involved in regulation of the Rrp2-RpoN-RpoS pathway further reinforces the importance of nutritional virulence to the enzootic cycle of B. burgdorferi
Two is Better Than One: Answering Complex Questions by Multiple Knowledge Sources with Generalized Links
Incorporating multiple knowledge sources is proven to be beneficial for
answering complex factoid questions. To utilize multiple knowledge bases (KB),
previous works merge all KBs into a single graph via entity alignment and
reduce the problem to question-answering (QA) over the fused KB. In reality,
various link relations between KBs might be adopted in QA over multi-KBs. In
addition to the identity between the alignable entities (i.e. full link),
unalignable entities expressing the different aspects or types of an abstract
concept may also be treated identical in a question (i.e. partial link). Hence,
the KB fusion in prior works fails to represent all types of links, restricting
their ability to comprehend multi-KBs for QA. In this work, we formulate the
novel Multi-KB-QA task that leverages the full and partial links among multiple
KBs to derive correct answers, a benchmark with diversified link and query
types is also constructed to efficiently evaluate Multi-KB-QA performance.
Finally, we propose a method for Multi-KB-QA that encodes all link relations in
the KB embedding to score and rank candidate answers. Experiments show that our
method markedly surpasses conventional KB-QA systems in Multi-KB-QA, justifying
the necessity of devising this task
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