8,415 research outputs found
Flexible couplings: diffusing neuromodulators and adaptive robotics
Recent years have seen the discovery of freely diffusing gaseous neurotransmitters, such as nitric oxide (NO), in biological nervous systems. A type of artificial neural network (ANN) inspired by such gaseous signaling, the GasNet, has previously been shown to be more evolvable than traditional ANNs when used as an artificial nervous system in an evolutionary robotics setting, where evolvability means consistent speed to very good solutions¿here, appropriate sensorimotor behavior-generating systems. We present two new versions of the GasNet, which take further inspiration from the properties of neuronal gaseous signaling. The plexus model is inspired by the extraordinary NO-producing cortical plexus structure of neural fibers and the properties of the diffusing NO signal it generates. The receptor model is inspired by the mediating action of neurotransmitter receptors. Both models are shown to significantly further improve evolvability. We describe a series of analyses suggesting that the reasons for the increase in evolvability are related to the flexible loose coupling of distinct signaling mechanisms, one ¿chemical¿ and one ¿electrical.
It's TEEtime: A New Architecture Bringing Sovereignty to Smartphones
Modern smartphones are complex systems in which control over phone resources
is exercised by phone manufacturers, OS vendors, and users. These stakeholders
have diverse and often competing interests. Barring some exceptions, users
entrust their security and privacy to OS vendors (Android and iOS) and need to
accept their constraints. Manufacturers protect their firmware and peripherals
from the OS by executing in the highest privilege and leveraging dedicated CPUs
and TEEs. OS vendors need to trust the highest privileged code deployed by
manufacturers. This division of control over the phone is not ideal for OS
vendors and is even more disadvantageous for the users. Users are generally
limited in what applications they can install on their devices, in the privacy
model and trust assumptions of the existing applications, and in the
functionalities that applications can have.
We propose TEEtime, a new smartphone architecture based on trusted execution
allowing to balance the control different stakeholders exert over phones. More
leveled control over the phone means that no stakeholder is more privileged
than the others. In particular, TEEtime makes users sovereign over their
phones: It enables them to install sensitive applications in isolated domains
with protected access to selected peripherals alongside an OS. TEEtime achieves
this while maintaining compatibility with the existing smartphone ecosystem and
without relying on virtualization; it only assumes trust in a phone's firmware.
TEEtime is the first TEE architecture that allows isolated execution domains to
gain protected and direct access to peripherals. TEEtime is based on Armv8-A
and achieves peripheral isolation using a novel mechanism based on memory and
interrupt controller protection. We demonstrate the feasibility of our design
by implementing a prototype of TEEtime, and by running exemplary sensitive
applications
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