17 research outputs found
SafeDiffuser: Safe Planning with Diffusion Probabilistic Models
Diffusion model-based approaches have shown promise in data-driven planning,
but there are no safety guarantees, thus making it hard to be applied for
safety-critical applications. To address these challenges, we propose a new
method, called SafeDiffuser, to ensure diffusion probabilistic models satisfy
specifications by using a class of control barrier functions. The key idea of
our approach is to embed the proposed finite-time diffusion invariance into the
denoising diffusion procedure, which enables trustworthy diffusion data
generation. Moreover, we demonstrate that our finite-time diffusion invariance
method through generative models not only maintains generalization performance
but also creates robustness in safe data generation. We test our method on a
series of safe planning tasks, including maze path generation, legged robot
locomotion, and 3D space manipulation, with results showing the advantages of
robustness and guarantees over vanilla diffusion models.Comment: 19 pages, website: https://safediffuser.github.io/safediffuser
On the Forward Invariance of Neural ODEs
To ensure robust and trustworthy decision-making, it is highly desirable to
enforce constraints over a neural network's parameters and its inputs
automatically by back-propagating output specifications. This way, we can
guarantee that the network makes reliable decisions under perturbations. Here,
we propose a new method for achieving a class of specification guarantees for
neural Ordinary Differentiable Equations (ODEs) by using invariance set
propagation. An invariance of a neural ODE is defined as an output
specification, such as to satisfy mathematical formulae, physical laws, and
system safety. We use control barrier functions to specify the invariance of a
neural ODE on the output layer and propagate it back to the input layer.
Through the invariance backpropagation, we map output specifications onto
constraints on the neural ODE parameters or its input. The satisfaction of the
corresponding constraints implies the satisfaction of output specifications.
This allows us to achieve output specification guarantees by changing the input
or parameters while maximally preserving the model performance. We demonstrate
the invariance propagation on a comprehensive series of representation learning
tasks, including spiral curve regression, autoregressive modeling of joint
physical dynamics, convexity portrait of a function, and safe neural control of
collision avoidance for autonomous vehicles.Comment: 20 page
Telomerase prevents accelerated senescence in glucose-6-phosphate dehydrogenase (G6PD)-deficient human fibroblasts
Fibroblasts derived from glucose-6-phosphate dehydrogenase (G6PD)-deficient patients display retarded growth and accelerated cellular senescence that is attributable to increased accumulation of oxidative DNA damage and increased sensitivity to oxidant-induced senescence, but not to accelerated telomere attrition. Here, we show that ectopic expression of hTERT stimulates telomerase activity and prevents accelerated senescence in G6PD-deficient cells. Stable clones derived from hTERT-expressing normal and G6PD-deficient fibroblasts have normal karyotypes, and display no sign of senescence beyond 145 and 105 passages, respectively. Activation of telomerase, however, does not prevent telomere attrition in earlier-passage cells, but does stabilize telomere lengths at later passages. In addition, we provide evidence that ectopic expression of hTERT attenuates the increased sensitivity of G6PD-deficient fibroblasts to oxidant-induced senescence. These results suggest that ectopic expression of hTERT, in addition to acting in telomere length maintenance by activating telomerase, also functions in regulating senescence induction