5,084 research outputs found
Exploring Privacy Preservation in Outsourced K-Nearest Neighbors with Multiple Data Owners
The k-nearest neighbors (k-NN) algorithm is a popular and effective
classification algorithm. Due to its large storage and computational
requirements, it is suitable for cloud outsourcing. However, k-NN is often run
on sensitive data such as medical records, user images, or personal
information. It is important to protect the privacy of data in an outsourced
k-NN system.
Prior works have all assumed the data owners (who submit data to the
outsourced k-NN system) are a single trusted party. However, we observe that in
many practical scenarios, there may be multiple mutually distrusting data
owners. In this work, we present the first framing and exploration of privacy
preservation in an outsourced k-NN system with multiple data owners. We
consider the various threat models introduced by this modification. We discover
that under a particularly practical threat model that covers numerous
scenarios, there exists a set of adaptive attacks that breach the data privacy
of any exact k-NN system. The vulnerability is a result of the mathematical
properties of k-NN and its output. Thus, we propose a privacy-preserving
alternative system supporting kernel density estimation using a Gaussian
kernel, a classification algorithm from the same family as k-NN. In many
applications, this similar algorithm serves as a good substitute for k-NN. We
additionally investigate solutions for other threat models, often through
extensions on prior single data owner systems
Contextual Linear Bandits under Noisy Features: Towards Bayesian Oracles
We study contextual linear bandit problems under uncertainty on features;
they are noisy with missing entries. To address the challenges from the noise,
we analyze Bayesian oracles given observed noisy features. Our Bayesian
analysis finds that the optimal hypothesis can be far from the underlying
realizability function, depending on noise characteristics, which is highly
non-intuitive and does not occur for classical noiseless setups. This implies
that classical approaches cannot guarantee a non-trivial regret bound. We thus
propose an algorithm aiming at the Bayesian oracle from observed information
under this model, achieving regret bound with respect to
feature dimension and time horizon . We demonstrate the proposed
algorithm using synthetic and real-world datasets.Comment: 30 page
Spinal V2b neurons reveal a role for ipsilateral inhibition in speed control
The spinal cord contains a diverse array of interneurons that govern motor output. Traditionally, models of spinal circuits have emphasized the role of inhibition in enforcing reciprocal alternation between left and right sides or flexors and extensors. However, recent work has shown that inhibition also increases coincident with excitation during contraction. Here, using larval zebrafish, we investigate the V2b (Gata3+) class of neurons, which contribute to flexor-extensor alternation but are otherwise poorly understood. Using newly generated transgenic lines we define two stable subclasses with distinct neurotransmitter and morphological properties. These V2b subclasses synapse directly onto motor neurons with differential targeting to speed-specific circuits. In vivo, optogenetic manipulation of V2b activity modulates locomotor frequency: suppressing V2b neurons elicits faster locomotion, whereas activating V2b neurons slows locomotion. We conclude that V2b neurons serve as a brake on axial motor circuits. Together, these results indicate a role for ipsilateral inhibition in speed control
PIANO: Proximity-based User Authentication on Voice-Powered Internet-of-Things Devices
Voice is envisioned to be a popular way for humans to interact with
Internet-of-Things (IoT) devices. We propose a proximity-based user
authentication method (called PIANO) for access control on such voice-powered
IoT devices. PIANO leverages the built-in speaker, microphone, and Bluetooth
that voice-powered IoT devices often already have. Specifically, we assume that
a user carries a personal voice-powered device (e.g., smartphone, smartwatch,
or smartglass), which serves as the user's identity. When another voice-powered
IoT device of the user requires authentication, PIANO estimates the distance
between the two devices by playing and detecting certain acoustic signals;
PIANO grants access if the estimated distance is no larger than a user-selected
threshold. We implemented a proof-of-concept prototype of PIANO. Through
theoretical and empirical evaluations, we find that PIANO is secure, reliable,
personalizable, and efficient.Comment: To appear in ICDCS'1
Does tailoring instructional style to a medical student\u27s self-perceived learning style improve performance when teaching intravenous catheter placement? A randomized controlled study.
BACKGROUND: Students may have different learning styles. It is unclear, however, whether tailoring instructional methods for a student\u27s preferred learning style improves educational outcomes when teaching procedures. The authors sought to examine whether teaching to a student\u27s self-perceived learning style improved the acquisition of intravenous (IV) catheter placement skills. The authors hypothesized that matching a medical student\u27s preferred learning style with the instructor\u27s teaching style would increase the success of placing an IV catheter.
METHODS: Using the VARK model (i.e., visual [V], auditory [A], read/write [R] and kinesthetic [K]), third-year medical students reported their self-perceived learning style and were subsequently randomized to instructors who were trained to teach according to a specific learning format (i.e., visual, auditory). Success was gauged by: 1) the placement of an IV on the first attempt and 2) the number of attempts made until an IV line was successfully placed.
RESULTS: The average number of attempts in the matched learning style group was 1.53, compared to 1.64 in the unmatched learning style group; however, results were not statistically significant. Both matched and unmatched groups achieved a similar success rate (57 and 58 %, respectively). Additionally, a comparison of success between the unmatched and matched students within each learning style modality yielded no statistical significance.
CONCLUSIONS: Results suggest that providing procedural instruction that is congruent with a student\u27s self-perceived learning style does not appear to improve outcomes when instructing students on IV catheter placement
- …