73 research outputs found
Learn Privacy-friendly Global Gaussian Processes in Federated Learning
In the era of big data, Federated Learning (FL) has drawn great attention as it naturally operates on distributed computational resources without the need of data warehousing. Similar to Distributed Learning (DL), FL distributes most computational tasks to end devices, but emphasizes more on preserving the privacy of clients. In other words, any FL algorithm should not send raw client data, if not the information about them, that could leak privacy. As a result, in typical scenarios where the FL framework applies, it is common for clients to have or obtain insufficient training data to produce an accurate model. To decide whether a prediction is trustworthy, models that provide not only point estimations, but also some notion of confidence are beneficial. Gaussian Process (GP) is a powerful Bayesian model that comes with naturally well-calibrated variance estimations. However, it is challenging to learn a stand-alone global GP since merging local kernels leads to privacy leakage. To preserve privacy, previous works that consider federated GPs avoid learning a global model by focusing on the personalized setting or learning an ensemble of local models.
In this work, we present Federated Bayesian Neural Regression (FedBNR), an algorithm that learns a scalable stand-alone global federated GP that respects clients' privacy. We incorporate deep kernel learning and random features for scalability by defining a unifying random kernel. We show this random kernel can recover any stationary kernel and many non-stationary kernels. We then derive a principled approach of learning a global predictive model as if all client data is centralized. We also learn global kernels with knowledge distillation methods for non-identically and independently distributed (non-i.i.d.) clients. We design synthetic experiments to illustrate scenarios where our model has a clear advantage and provide insights into the rationales. Experiments are also conducted on real-world regression datasets and show statistically significant improvements compared to other federated GP models
Bypassing the Simulator: Near-Optimal Adversarial Linear Contextual Bandits
We consider the adversarial linear contextual bandit problem, where the loss
vectors are selected fully adversarially and the per-round action set (i.e. the
context) is drawn from a fixed distribution. Existing methods for this problem
either require access to a simulator to generate free i.i.d. contexts, achieve
a sub-optimal regret no better than , or are
computationally inefficient. We greatly improve these results by achieving a
regret of without a simulator, while maintaining
computational efficiency when the action set in each round is small. In the
special case of sleeping bandits with adversarial loss and stochastic arm
availability, our result answers affirmatively the open question by Saha et al.
[2020] on whether there exists a polynomial-time algorithm with
regret. Our approach naturally handles the case where the
loss is linear up to an additive misspecification error, and our regret shows
near-optimal dependence on the magnitude of the error
Towards Optimal Regret in Adversarial Linear MDPs with Bandit Feedback
We study online reinforcement learning in linear Markov decision processes
with adversarial losses and bandit feedback, without prior knowledge on
transitions or access to simulators. We introduce two algorithms that achieve
improved regret performance compared to existing approaches. The first
algorithm, although computationally inefficient, ensures a regret of
, where is the number of
episodes. This is the first result with the optimal dependence in the
considered setting. The second algorithm, which is based on the policy
optimization framework, guarantees a regret of
and is computationally
efficient. Both our results significantly improve over the state-of-the-art: a
computationally inefficient algorithm by Kong et al. [2023] with
regret, for some problem-dependent constant that can
be arbitrarily close to zero, and a computationally efficient algorithm by
Sherman et al. [2023b] with regret
Effects of habitat usage on hypoxia avoidance behavior and exposure in reef-dependent marine coastal species
Reef habitat in coastal ecosystems is increasingly being augmented with artificial reefs (ARs) and is simultaneously experiencing increasing hypoxia due to eutrophication and climate change. Relatively little is known about the effects of hypoxia on organisms that use complex habitat arrangements and how the presence of highly preferred AR habitat can affect the exposure of organisms to low dissolved oxygen (DO). We performed two laboratory experiments that used video recording of behavioral movement to explore 1) habitat usage and staying duration of individuals continuously exposed to 3, 5, and 7 mg/L dissolved oxygen (DO) in a complex of multiple preferred and avoided habitat types, and 2) the impact of ARs on exposure to different DO concentrations under a series of two-way replicated choice experiments with or without AR placement on the low-oxygen side. Six common reef-dependent species found in the northeastern sea areas of China were used (i.e., rockfish Sebastes schlegelii and Hexagrammos otakii, filefish Thamnaconus modestus, flatfish Pseudopleuronectes yokohamae, sea cucumber Stichopus japonicus, and crab Charybdis japonica). Results showed that lower DO levels decreased the usage of preferred habitats of the sea cucumber and the habitat-generalist filefish but increased the habitat affinity to preferred habitat types for the two habitat-specific rockfishes. Low DO had no effect on the crab’s habitat usage. In the choice experiment, all three fish species avoided 1 mg/L, and the rockfish S. schlegelii continued to avoid the lower DO when given choices involving pairs of 3, 5, and 7 mg/L, while H. otakii and the flatfish showed less avoidance. The availability of ARs affected exposure to low DO for the habitat-preferring rockfishes but was not significant for the flatfish. This study provides information for assessing the ecological effects and potential for adaptation through behavioral movement for key reef-dependent species under the increasing overlap of ARs and hypoxia anticipated in the future
Title2Event: Benchmarking Open Event Extraction with a Large-scale Chinese Title Dataset
Event extraction (EE) is crucial to downstream tasks such as new aggregation
and event knowledge graph construction. Most existing EE datasets manually
define fixed event types and design specific schema for each of them, failing
to cover diverse events emerging from the online text. Moreover, news titles,
an important source of event mentions, have not gained enough attention in
current EE research. In this paper, We present Title2Event, a large-scale
sentence-level dataset benchmarking Open Event Extraction without restricting
event types. Title2Event contains more than 42,000 news titles in 34 topics
collected from Chinese web pages. To the best of our knowledge, it is currently
the largest manually-annotated Chinese dataset for open event extraction. We
further conduct experiments on Title2Event with different models and show that
the characteristics of titles make it challenging for event extraction,
addressing the significance of advanced study on this problem. The dataset and
baseline codes are available at https://open-event-hub.github.io/title2event.Comment: EMNLP 202
Infrared Imaging of Magnetic Octupole Domains in Non-collinear Antiferromagnets
Magnetic structure plays a pivotal role in the functionality of
antiferromagnets (AFMs), which not only can be employed to encode digital data
but also yields novel phenomena. Despite its growing significance, visualizing
the antiferromagnetic domain structure remains a challenge, particularly for
non-collinear AFMs. Currently, the observation of magnetic domains in
non-collinear antiferromagnetic materials is feasible only in MnSn,
underscoring the limitations of existing techniques that necessitate distinct
methods for in-plane and out-of-plane magnetic domain imaging. In this study,
we present a versatile method for imaging the antiferromagnetic domain
structure in a series of non-collinear antiferromagnetic materials by utilizing
the anomalous Ettingshausen effect (AEE), which resolves both the magnetic
octupole moments parallel and perpendicular to the sample surface. Temperature
modulation due to the AEE originating from different magnetic domains is
measured by the lock-in thermography, revealing distinct behaviors of octupole
domains in different antiferromagnets. This work delivers an efficient
technique for the visualization of magnetic domains in non-collinear AFMs,
which enables comprehensive study of the magnetization process at the
microscopic level and paves the way for potential advancements in applications.Comment: National Science Review in pres
Cationic nanoparticles directly bind angiotensin-converting enzyme 2 and induce acute lung injury in mice
- …