Can a continuous mineral foam explain the stiffening of aged bone tissue? A micromechanical approach to mineral fusion in musculoskeletal tissues

Recent experimental data revealed a stiffening of aged cortical bone tissue, which could not be explained by common multiscale elastic material models. We explain this data by incorporating the role of mineral fusion via a new hierarchical modeling approach exploiting the asymptotic (periodic) homogenization (AH) technique for three-dimensional linear elastic composites. We quantify for the first time the stiffening that is obtained by considering a fused mineral structure in a softer matrix in comparison with a composite having non-fused cubic mineral inclusions. We integrate the AH approach in the Eshelby-based hierarchical mineralized turkey leg tendon model (Tiburtius et al 2014 Biomech. Model. Mechanobiol. 13 1003–23), which can be considered as a base for musculoskeletal mineralized tissue modeling. We model the finest scale compartments, i.e. the extrafibrillar space and the mineralized collagen fibril, by replacing the self-consistent scheme with our AH approach. This way, we perform a parametric analysis at increasing mineral volume fraction, by varying the amount of mineral that is fusing in the axial and transverse tissue directions in both compartments. Our effective stiffness results are in good agreement with those reported for aged human radius and support the argument that the axial stiffening in aged bone tissue is caused by the formation of a continuous mineral foam. Moreover, the proposed theoretical and computational approach supports the design of biomimetic materials which require an overall composite stiffening without increasing the amount of the reinforcing material

The Threat of Force as an Action in Self-Defense Under International Law

Self-defense is a universally accepted exception to the prohibition of the use of force in international law, and it has been subjected to careful academic scrutiny. The prohibition of the threat of force, although equally important in terms of its normative status to the prohibition on use, has attracted far less academic commentary to date. This Article examines the relationship between the two prohibitions--of the use and threat of force--and considers the largely unexplored possibility of states utilizing a threat of force as a means of lawful defensive response: self-defense in the form of a threat. The status of this concept under international law is assessed, and the criteria that may regulate it are analyzed. This Article is based on an analogy between traditional forcible self-defense and the notion of threats made in self-defense. However, one cannot automatically apply the well-established rules of self-defense to a defensive threat, largely because of the practical differences between a threatened response and a response involving actual force

A coinductive semantics of the Unlimited Register Machine

We exploit (co)inductive specifications and proofs to approach the evaluation of low-level programs for the Unlimited Register Machine (URM) within the Coq system, a proof assistant based on the Calculus of (Co)Inductive Constructions type theory. Our formalization allows us to certify the implementation of partial functions, thus it can be regarded as a first step towards the development of a workbench for the formal analysis and verification of both converging and diverging computations

Formal Verification of Hardware Synthesis

Original manuscript: January 21, 2013We report on the implementation of a certified compiler for a high-level hardware description language (HDL) called Fe-Si (FEatherweight SynthesIs). Fe-Si is a simplified version of Bluespec, an HDL based on a notion of guarded atomic actions. Fe-Si is defined as a dependently typed deep embedding in Coq. The target language of the compiler corresponds to a synthesisable subset of Verilog or VHDL. A key aspect of our approach is that input programs to the compiler can be defined and proved correct inside Coq. Then, we use extraction and a Verilog back-end (written in OCaml) to get a certified version of a hardware design.United States. Defense Advanced Research Projects Agency (Agreement FA8750-12-2-0110

A formally verified compiler back-end

This article describes the development and formal verification (proof of semantic preservation) of a compiler back-end from Cminor (a simple imperative intermediate language) to PowerPC assembly code, using the Coq proof assistant both for programming the compiler and for proving its correctness. Such a verified compiler is useful in the context of formal methods applied to the certification of critical software: the verification of the compiler guarantees that the safety properties proved on the source code hold for the executable compiled code as well

Mejoras operativas en la valoración genética del ganado caprino lechero de raza murciano-granadina

Se compararon diferentes modelos para la evaluación de cabras lecheras para su uso en un programa de mejora genética establecido entre la Asociación de Ganaderos de Caprino de Raza Murciano-Granadina de la Comunidad Valenciana y el Centro de Investigación y Tecnología Animal del Instituto Valenciano de Investigaciones Agrarias. Se compararon en primer lugar dos modelos mixtos con diferente estructura de covarianzas. También se realizaron comparaciones entre modelos que incluyeron otros efectos sistemáticos: edad de la hembra en el momento del parto y días desde el parto hasta el primer control de la lactación. Se consideraron los caracteres estandarizados producción de leche y porcentajes de grasa y proteína. Las comparaciones se realizaron considerando criterios estadísticos de información. Los resultados indican que el modelo de repetibilidad es el más adecuado al tener en cuenta las covarianzas entre medidas de una cabra. La inclusión del efecto edad de la hembra al parto sólo fue ventajosa para el carácter producción de leche. La consideración del efecto tiempo desde el parto al primer control lechero fue positiva para los caracteres de producción de leche y de porcentaje de proteína. Ninguno de los efectos incluidos mejoró el modelo actualmente utilizado para porcentaje de grasa

Identifying the connection between Roman Conceptions of ‘Pure Air’ and Physical and Mental Health in Pompeian Gardens (c. 150 BC-AD 79): A Multi-Sensory Approach to Ancient Medicine

Different genres of Roman literature commented on the relationship between the condition of the environment and physical and mental health. They often refer to clear, pure, or good air as a beneficial aspect of the environment. Yet, unlike fetid air, they provide few descriptions of what constituted healthy air quality. Moreover, aside from pointing out the association between the environment and bodily condition, the writers also did not explain precisely how the link between the two was made. This paper utilizes a comparative study of ancient literature and the archaeological remains of Roman gardens in Pompeii: archaeobotanical samples, fresco paintings, location, and surviving features. Three questions are addressed in this study: First, how did the Romans identify and define pure? Second, how did air connect to the body? Third, what were the qualities of pure air and how did they benefit the body? Not only was inhalation a means of linking air to the body, but the two were also related through sensory perception. I argue that sight, sound, and olfaction were used to identify the qualities of pure air. Through the sensory process of identification, the beneficial properties of pure air were, in accordance with ancient perceptions of sensory function, taken into the body and affected health. Thus, sensory perception acted as the bridge between the environment and health