Cornucopia: Temporal safety for CHERI heaps

Use-after-free violations of temporal memory safety continue to plague software systems, underpinning many high-impact exploits. The CHERI capability system shows great promise in achieving C and C++ language spatial memory safety, preventing out-of-bounds accesses. Enforcing language-level temporal safety on CHERI requires capability revocation, traditionally achieved either via table lookups (avoided for performance in the CHERI design) or by identifying capabilities in memory to revoke them (similar to a garbage-collector sweep). CHERIvoke, a prior feasibility study, suggested that CHERI’s tagged capabilities could make this latter strategy viable, but modeled only architectural limits and did not consider the full implementation or evaluation of the approach. Cornucopia is a lightweight capability revocation system for CHERI that implements non-probabilistic C/C++ temporal memory safety for standard heap allocations. It extends the CheriBSD virtual-memory subsystem to track capability flow through memory and provides a concurrent kernel-resident revocation service that is amenable to multi-processor and hardware acceleration. We demonstrate an average overhead of less than 2% and a worst-case of 8.9% for concurrent revocation on compatible SPEC CPU2006 benchmarks on a multi-core CHERI CPU on FPGA, and we validate Cornucopia against the Juliet test suite’s corpus of temporally unsafe programs. We test its compatibility with a large corpus of C programs by using a revoking allocator as the system allocator while booting multi-user CheriBSD. Cornucopia is a viable strategy for always-on temporal heap memory safety, suitable for production environments.This work was supported by the Defense Advanced Research Projects Agency (DARPA) and the Air Force Research Laboratory (AFRL), under contracts FA8750-10-C-0237 (“CTSRD”) and HR0011-18-C-0016 (“ECATS”). We also acknowledge the EPSRC REMS Programme Grant (EP/K008528/1), the ABP Grant (EP/P020011/1), the ERC ELVER Advanced Grant (789108), the Gates Cambridge Trust, Arm Limited, HP Enterprise, and Google, Inc

I’m so tired: biological and genetic mechanisms of cancer-related fatigue

Objective The goal of this paper is to discuss cancer-related fatigue (CRF) and address issues related to the investigation into potential biological and genetic causal mechanisms. The objectives are to: (1) describe CRF as a component of quality of life (QOL); (2) address measurement issues that have slowed progress toward an understanding of mechanisms underlying this symptom; (3) review biological pathways and genetic approaches that have promise for the exploration of causal mechanisms of CRF; and (4) offer directions for future research. Methods Review, synthesis, and interpretation of the literature. Results Until recently, CRF and QOL have been understood primarily as subjective patient-reported experiences. With increased understanding of human genetics, theories and research are being expanded to incorporate biological and genetic understandings of these subjective experiences. Proposed biological and genetic mechanisms of CRF that have been examined include cytokine dysregulation, hypothalamic-pituitary-adrenal (HPA) axis dysfunction, five hydroxy tryptophan (5-HT) neurotransmitter dysregulation, circadian rhythm disruption, alterations in adenosine triphosphate (ATP) and muscle metabolism, and vagal afferent activation. Approaches to the study of genetic mechanisms have also been addressed including candidate genes, genome-wide scanning, and gene expression. Based on the review and synthesis of the literature, directions for future research are proposed. Conclusions Understanding the biological and genetic basis of CRF has the potential to contribute to a more complete understanding of the genetic determinants of QO

Efeitos do treinamento de resistência na força muscular e níveis de fadiga em pacientes com câncer de mama Los efectos de los ejercicios de resistencia sobre varios músculos y niveles de fatiga en pacientes con cáncer de mama The effects of resistance training on muscular strength and fatigue levels in breast cancer patients

Os efeitos de programas generalizados de atividade física no combate ao câncer e aos efeitos colaterais de seu tratamento têm sido amplamente relatados na literatura. O objetivo do presente estudo foi o de examinar os efeitos de um programa de prescrição de exercício físico individualizado, com ênfase no treinamento resistido, na força muscular e nos níveis de fadiga em pacientes portadoras de câncer de mama em tratamento. Vinte mulheres foram divididas aleatoriamente em dois grupos, sendo um experimental (57,5 ± 23,0 anos) e um controle (56,6 ± 16,0 anos). O grupo experimental exercitou-se, após a cirurgia, durante 60 minutos, de forma moderada, duas vezes por semana, durante 21 semanas. A força muscular total foi avaliada antes e após o tratamento e os níveis de fadiga foram avaliados em três momentos durante o treinamento. Foram encontradas diferenças significativas na força muscular total entre os grupos após o treinamento (p = 0,025). Os níveis de fadiga diminuíram significativamente entre os grupos após a primeira (p = 0,001) e a segunda (p = 0,005) intervenção e ao final do tratamento (p = 0,001). Os resultados deste estudo sugerem que os exercícios resistidos devem ser incluídos na prescrição de exercícios no combate da fadiga e na melhoria da força muscular em mulheres com câncer de mama, submetidas a tratamento.<br>Los efectos de programas generalizados de actividad física de combate al cáncer y los efectos colaterales de su tratamiento vienen siendo bastante estudiados. El objetivo del presente estudio ha sido el de examinar los efectos de un programa prescrito de ejercicio físico individual, con énfasis en el entrenamiento resistido, en la fuerza muscular y en los niveles de fatiga en pacientes portadoras de cáncer de mama en tratamiento. Veinte mujeres fueron divididas aleatoriamente en dos grupos, siendo uno de ellos el experimental (57,5 ± 23,0 años) y el otro de control (56,6 ± 16,0 años). El grupo experimental se ejercitó después de una cirugía durante 60 minutos, de forma moderada, dos veces por semana, durante 21 semanas. La fuerza muscular total fue evaluada antes y después del tratamiento y los niveles de fatiga fueron evaluados en cuatro momentos durante los ejercicios. Fueron encontradas diferencias significativas en la fuerza muscular total entre los grupos después de los ejercicios (p = 0,025). Los niveles de fatiga disminuyeron significativamente entre los grupos después de la primera (p = 0,001) y la segunda (p = 0,005) intervención y al final del tratamiento (p = 0,001). Los resultados de este estudio sugieren que los ejercicios resistidos deben ser incluidos en la prescripción de ejercicios de combate a la fatiga y en la mejoría de la fuerza muscular en mujeres con cáncer de mama sometidas a tratamiento.<br>The effects of generalized exercise programs to combat cancer and cancer treatment-related side effects have been extensively reported in the literature. The purpose of this study was to examine the effects of an individualized exercise program with emphasis on resistance exercise, changes in muscular strength and fatigue in breast cancer female patients under treatment. Twenty subjects were randomly divided in two groups: an experimental (57.5 ± 23.0 years) and a control (56.6 ± 16.0 years) group. A twenty-one week intervention involving pre- and post-functional assessments, prescriptive exercise, and three moments of fatigue measures was used. The experimental group exercised at a low to moderate-intensity for sixty minutes two days a week beginning after surgery. Significant differences in overall muscular strength were observed between groups post-intervention (p = 0.025). Fatigue was also significantly different between groups at treatment one (p = 0.001), treatment two (p = 0.005) and post-intervention (p = 0.001). The results of this study suggest that an emphasis on resistance training should be utilized to combat fatigue and to increase muscular strength in breast cancer patients undergoing treatment

Gap-junction channels inhibit transverse propagation in cardiac muscle

<p>Abstract</p> <p>The effect of adding many gap-junctions (g-j) channels between contiguous cells in a linear chain on transverse propagation between parallel chains was examined in a 5 × 5 model (5 parallel chains of 5 cells each) for cardiac muscle. The action potential upstrokes were simulated using the PSpice program for circuit analysis. Either a single cell was stimulated (cell A1) or the entire chain was stimulated simultaneously (A-chain). Transverse velocity was calculated from the total propagation time (TPT) from when the first AP crossed a V_mof -20 mV and the last AP crossed -20 mV. The number of g-j channels per junction was varied from zero to 100, 1,000 and 10,000 (R_gjof ∞, 100 MΩ, 10 MΩ, 1.0 MΩ, respectively). The longitudinal resistance of the interstitial fluid (ISF) space between the parallel chains (R_ol2) was varied between 200 KΩ (standard value) and 1.0, 5.0, and 10 MΩ. The higher the R_ol2value, the tighter the packing of the chains. It was found that adding many g-j channels inhibited transverse propagation by blocking activation of all 5 chains, unless R_ol2was greatly increased above the standard value of 200 KΩ. This was true for either method of stimulation. This was explained by, when there is strong longitudinal coupling between all 5 cells of a chain awaiting excitation, there must be more transfer energy (i.e., more current) to simultaneously excite all 5 cells of a chain.</p