Cache replacement policies often order blocks into distinct positions. A block is placed into a set in some initial position. A re-referenced block is promoted into a higher position while other blocks may move into lower positions. A block in the lowest position is a candidate for replacement. Tree-based PseudoLRU is a well-known space-efficient replacement policy based on representing block positions as distinct paths in a binary tree. We find that a placement or promotion for one block often needlessly disturbs the non-promoted blocks. Guided by the principle of minimal disturbance, i.e. that a policy should seek to disturb the order of non-promoted blocks to the smallest extent possible, we develop a simple modification to PseudoLRU resulting in a policy that improves performance over previous techniques while retaining the low cost of PseudoLRU. The result is a minimal disturbance placement and promotion (MDPP) policy. We first give a static formulation of MDPP and show that it provides superior performance to LRU, PseudoLRU and matches performance for SRRIP for both single-threaded and multi-core workloads. We then give a dynamic formulation that uses dead block prediction for placement and bypass and show that it meets or exceeds state-of-the-art performance with lower overhead. For single-threaded workloads, dynamic MDPP matches the 5.9% speedup over LRU of the state-of-the-art policy SHiP. For multi-core workloads, dynamic MDPP gives a normalized weighted speedup of 14.3% over LRU, compared with SHiP that yields a speedup of 12.3% over LRU and requires double the storage overhead per set. We show that minimal disturbance policies can reduce the frequency of a costly read-modify-write cycle for replacement state, making them potentially suitable for future work in DRAM caches.

Intra-process memory isolation is a cornerstone technique of protecting the sensitive data in memory-corruption defenses, such as the shadow stack in control flow integrity (CFI) and the safe region in code pointer integrity (CPI). In this paper, we propose SEIMI, a highly efficient intra-process memory isolation technique for memory-corruption defenses. The core is to use the efficient Supervisor-mode Access Prevention (SMAP), a hardware feature that is originally used for preventing the kernel from accessing the user space, to achieve intra-process memory isolation. To leverage SMAP, SEIMI creatively executes the user code in the privileged mode. In addition to enabling the new design of the SMAP-based memory isolation, we further develop multiple new techniques to ensure secure escalation of user code. Extensive experiments show that SEIMI outperforms existing isolation mechanisms, including the Memory Protection Keys (MPK) based scheme and the Memory Protection Extensions (MPX) based scheme.

Background: Clinical protocols in osteoporosis treatment could not meet the requirement of increasing local bone mineral density. A local delivery system was brought in to fix this dilemma. The high-energy extracorporeal shock wave (ESW) can travel into the deep tissues with little heat loss. Hence, ESW-driven nanoparticles could be used for local treatment of osteoporosis. Materials and methods: An ESW-actuated nanomotor (NM) sealed into microneedles (MNs) (ESW-NM-MN) was constructed for localized osteoporosis protection. The NM was made of calcium phosphate nanoparticles with a high Young’s modulus, which allows it to absorb ESW energy efficiently and convert it into kinetic energy for solid tissue penetration. Zoledronic (ZOL), as an alternative phosphorus source, forms the backbone of the NM (ZOL-NM), leading to bone targeting and ESW-mediated drug release. Results: After the ZOL-NM is sealed into hyaluronic acid (HA)-made microneedles, the soluble MN tips could break through the stratum corneum, injecting the ZOL-NM into the skin. As soon as the ESW was applied, the ZOL-NM would absorb the ESW energy to move from the outer layer of skin into the deep tissue and be fragmented to release ZOL and Ca²⁺ for anti-osteoclastogenesis and pro-osteogenesis. In vivo, the ZOL-NM increases localized bone parameters and reduces fracture risk, indicating its potential value in osteoporotic healing and other biomedical fields. Conclusion: The ESW-mediated transdermal delivery platform (ESW-NM-MN) could be used as a new strategy to improve local bone mineral density and protect local prone-fracture areas.

In K-edge decomposition imaging for the multienergy system with the photon counting detectors (PCDs), the energy bins significantly affect the intensity of the extracted K-edge signal. Optimized energy bins can provide a better K-edge signal to improve the quality of the decomposition images and have the potential to reduce the amount of contrast agents. In this article, we present the Gaussian spectrum selection method (GSSM) for the multienergy K-edge decomposition imaging which can extract an optimized K-edge signal by optimizing energy bins compared with the conventional theoretical attenuation selection method (TASM). GSSM decides the width and locations of the energy bins using a simple but effective model of the imaging system, which takes the degraded energy resolution of the detector and the continuous x-ray spectrum into consideration. Besides, we establish the objective function, difference of attenuation to relative standard deviation ratio (DAR), to determine the optimal energy bins which maximize the K-edge signal. The results show that GSSM gets a better K-edge signal than TASM especially at the lower concentration level of contrast agents. The new method has the potential to improve the contrast and reduce the amount of contrast agents.