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:In this paper, we analyze the vulnerabilities due to integrity cyber attacks named zero-stealthy attacks in cyber-physical systems, which are modeled as a stochastic linear time invariant (LTI) system equipped with a Kalman filter, an LQG controller, and a χ 2 failure detector. The attacks are designed by a sophisticated attacker so that the measurement residual of the compromised system coincides with the healthy one, and thus it is impossible to detect the attacks. First, we characterize and analyze an existence condition of the attacks from an attacker's standpoint. Then, we extend the attacks into an attacker's goal: The scenario when the adversary wishes to manipulate the systems to an objective designed by him/her. Our results provide that the attacker can manipulate the compromised system to the objective without accessing the networks of real-time sensor or actuator data. Finally, we verify the dangerousness of the attacks through a simple numerical example.

Measurement of tumor position is important for the radiotherapy of lung tumors with respiratory motion. Although tumors can be observed using X-ray fluoroscopy during radiotherapy, it is often difficult to measure tumor position from X-ray image sequences accurately because of overlapping organs. To measure tumor position accurately, a method for extracting tumor intensities from X-ray image sequences using a hidden Markov model (HMM) has been proposed. However, the performance of tumor intensity extraction depends on limited knowledge regarding the tumor motion observed in the four-dimensional computed tomography (4DCT) data used to construct the HMM. In this study, we attempted to improve the performance of tumor intensity extraction by augmenting 4DCT data. The proposed method was tested using simulated datasets of X-ray image sequences. The experimental results indicated that the HMM using the augmentation method could improve tumor-tracking performance when the range of tumor movement during treatment differed from that in the 4DCT data.

Fabrication of a nanopore in a hollow microcapsule was demonstrated using near-infrared femtosecond laser irradiation. The shape of the irradiated microcapsules was kept spherical except for a pore in the shell owing to the nonthermal processing by a femtosecond laser. The simulation results for the near-field and far-field scattering around a microcapsule revealed that highly-enhanced optical intensity can be generated at a spot on the shell of a microcapsule, which would in turn contribute to localized ablation. To the best of our knowledge, this is the first demonstration of the nanoperforation of transparent hollow microcapsules by a near-infrared laser without any doping with absorbing metals or dyes that may cause cell toxicity. The presented method is a promising approach for safer drug delivery and the controlled release of therapeutic drugs.