619 research outputs found
Opportunistic Reasoning for the Semantic Web: Adapting Reasoning to the Environment
Despite the efforts devoted so far, the Semantic Web vision appears to be an eluding target. We propose a paradigm shift for the Semantic Web centred around the pragmatics of developing Semantic Web applications in order to overcome the bootstrapping problem it suffers from. This paradigm is based on the vision of the Semantic Web as the result emerging from the integration and collaboration of a plethora of Semantic Web applications, rather that as a global entity. On the basis of this assumption we describe and propose Opportunistic Reasoning as a general purpose reasoning model suitable for the development of reasonably scalable Semantic Web applications
Decoupled Adversarial Contrastive Learning for Self-supervised Adversarial Robustness
Adversarial training (AT) for robust representation learning and
self-supervised learning (SSL) for unsupervised representation learning are two
active research fields. Integrating AT into SSL, multiple prior works have
accomplished a highly significant yet challenging task: learning robust
representation without labels. A widely used framework is adversarial
contrastive learning which couples AT and SSL, and thus constitute a very
complex optimization problem. Inspired by the divide-and-conquer philosophy, we
conjecture that it might be simplified as well as improved by solving two
sub-problems: non-robust SSL and pseudo-supervised AT. This motivation shifts
the focus of the task from seeking an optimal integrating strategy for a
coupled problem to finding sub-solutions for sub-problems. With this said, this
work discards prior practices of directly introducing AT to SSL frameworks and
proposed a two-stage framework termed Decoupled Adversarial Contrastive
Learning (DeACL). Extensive experimental results demonstrate that our DeACL
achieves SOTA self-supervised adversarial robustness while significantly
reducing the training time, which validates its effectiveness and efficiency.
Moreover, our DeACL constitutes a more explainable solution, and its success
also bridges the gap with semi-supervised AT for exploiting unlabeled samples
for robust representation learning. The code is publicly accessible at
https://github.com/pantheon5100/DeACL.Comment: Accepted by ECCV 2022 oral presentatio
Connecting the Cytoskeleton to the Endoplasmic Reticulum and Golgi
A tendency in cell biology is to divide and conquer. For example, decades of painstaking work have led to an understanding of endoplasmic reticulum (ER) and Golgi structure, dynamics, and transport. In parallel, cytoskeletal researchers have revealed a fantastic diversity of structure and cellular function in both actin and microtubules. Increasingly, these areas overlap, necessitating an understanding of both organelle and cytoskeletal biology. This review addresses connections between the actin/microtubule cytoskeletons and organelles in animal cells, focusing on three key areas: ER structure and function; ER-to-Golgi transport; and Golgi structure and function. Making these connections has been challenging for several reasons: the small sizes and dynamic characteristics of some components; the fact that organelle-specific cytoskeletal elements can easily be obscured by more abundant cytoskeletal structures; and the difficulties in imaging membranes and cytoskeleton simultaneously, especially at the ultrastructural level. One major concept is that the cytoskeleton is frequently used to generate force for membrane movement, with two potential consequences: translocation of the organelle, or deformation of the organelle membrane. While initially discussing issues common to metazoan cells in general, we subsequently highlight specific features of neurons, since these highly polarized cells present unique challenges for organellar distribution and dynamics
An Empirical Study & Evaluation of Modern CAPTCHAs
For nearly two decades, CAPTCHAs have been widely used as a means of
protection against bots. Throughout the years, as their use grew, techniques to
defeat or bypass CAPTCHAs have continued to improve. Meanwhile, CAPTCHAs have
also evolved in terms of sophistication and diversity, becoming increasingly
difficult to solve for both bots (machines) and humans. Given this
long-standing and still-ongoing arms race, it is critical to investigate how
long it takes legitimate users to solve modern CAPTCHAs, and how they are
perceived by those users.
In this work, we explore CAPTCHAs in the wild by evaluating users' solving
performance and perceptions of unmodified currently-deployed CAPTCHAs. We
obtain this data through manual inspection of popular websites and user studies
in which 1,400 participants collectively solved 14,000 CAPTCHAs. Results show
significant differences between the most popular types of CAPTCHAs:
surprisingly, solving time and user perception are not always correlated. We
performed a comparative study to investigate the effect of experimental context
-- specifically the difference between solving CAPTCHAs directly versus solving
them as part of a more natural task, such as account creation. Whilst there
were several potential confounding factors, our results show that experimental
context could have an impact on this task, and must be taken into account in
future CAPTCHA studies. Finally, we investigate CAPTCHA-induced user task
abandonment by analyzing participants who start and do not complete the task.Comment: Accepted at USENIX Security 202
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