Divergence of opinion and risk : an empirical analysis of the Ex Ante beliefs of institutional investors

Bibliography: p. [24-25

A viscoelastic anisotropic hyperelastic constitutive model of the human cornea

A constitutive model based on the continuum mechanics theory has been developed which represents interlamellar cohesion, regional variation of collagen fibril density, 3D anisotropy and both age-related viscoelastic and hyperelastic stiffening behaviour of the human cornea. Experimental data gathered from a number of previous studies on 48 ex vivo human cornea (inflation and shear tests) enabled calibration of the constitutive model by numerical analysis. Wide-angle X-ray scattering and electron microscopy provided measured data which quantify microstructural arrangements associated with stiffness. The present study measures stiffness parallel to the lamellae of the cornea which approximately doubles with an increase in strain rate from 0.5 to 5%/min, while the underlying stromal matrix provides a stiffness 2–3 orders of magnitude lower than the lamellae. The model has been simultaneously calibrated to within 3% error across three age groups ranging from 50 to 95 years and three strain rates across the two loading scenarios. Age and strain-rate-dependent material coefficients allow numerical simulation under varying loading scenarios for an individual patient with material stiffness approximated by their age. This present study addresses a significant gap in numerical representation of the cornea and has great potential in daily clinical practice for the planning and optimisation of corrective procedures and in preclinical optimisation of diagnostic procedures

Ex vivo testing of intact eye globes under inflation conditions to determine regional variation of mechanical stiffness

BACKGROUND: The eye globe exhibits significant regional variation of mechanical behaviour. The aim of this present study is to develop a new experimental technique for testing intact eye globes in a form that is representative of in vivo conditions, and therefore suitable for determining the material properties of the complete outer ocular tunic. METHODS: A test rig has been developed to provide closed-loop control of either applied intra-ocular pressure or resulting apical displacement; measurement of displacements across the external surface of the eye globe using high-resolution digital cameras and digital image correlation software; prevention of rigid-body motion and protection of the ocular surface from environmental drying. The method has been demonstrated on one human and one porcine eye globe, which were cyclically loaded. Finite element models based on specimen specific tomography, free from rotational symmetry, were used along with experimental pressure-displacement data in an inverse analysis process to derive the mechanical properties of tissue in different regions of the eye’s outer tunic. RESULTS: The test method enabled monitoring of mechanical response to intraocular pressure variation across the surface of the eye globe. For the two eyes tested, the method showed a gradual change in the sclera’s stiffness from a maximum at the limbus to a minimum at the posterior pole, while in the cornea the stiffness was highest at the centre and lowest in the peripheral zone. Further, for both the sclera and cornea, the load–displacement behaviour did not vary significantly between loading cycles. CONCLUSIONS: The first methodology capable of mechanically testing intact eye globes, with applied loads and boundary conditions that closely represent in vivo conditions is introduced. The method enables determination of the regional variation in mechanical behaviour across the ocular surface

Capturing Transition Paths and Transition States for Conformational Rearrangements in the Ribosome

AbstractTo reveal the molecular determinants of biological function, one seeks to characterize the interactions that are formed in conformational and chemical transition states. In other words, what interactions govern the molecule’s energy landscape? To accomplish this, it is necessary to determine which degrees of freedom can unambiguously identify each transition state. Here, we perform simulations of large-scale aminoacyl-transfer RNA (aa-tRNA) rearrangements during accommodation on the ribosome and project the dynamics along experimentally accessible atomic distances. From this analysis, we obtain evidence for which coordinates capture the correct number of barrier-crossing events and accurately indicate when the aa-tRNA is on a transition path. Although a commonly used coordinate in single-molecule experiments performs poorly, this study implicates alternative coordinates along which rearrangements are accurately described as diffusive movements across a one-dimensional free-energy profile. From this, we provide the theoretical foundation required for single-molecule techniques to uncover the energy landscape governing aa-tRNA selection by the ribosome

A new test method for investigating punching shear strength in Ultra High Performance Fibre Reinforced Concrete (UHPFRC) slabs

Punching shear capacity of Ultra High Performance Fibre Reinforced Concrete (UHPFRC) slabs has been the subject of a number of studies. There is, however, only limited information available on this parameter of UHPFRC without conventional reinforcement. This is due to the complexity of punching shear behaviour within concrete and is also limited by the lack of suitable test methods currently available. Therefore, in this study, attempts to design a novel testing method to measure the punching shear capacity of the concrete was carried out. The designed test arrangement was employed to carry out an extensive experimental study on UHPFRC slabs subjected to punching shear failure. From the results obtained, the relationship between the punching shear load and the angle of the shear plane, the critical value of the basic control perimeter and failure mode were studied. The experimental study undertaken here provides significant insight into the punching shear capacity of UHPFRC slabs. The results illustrate and highlight many of the advantages of using UHPFRC compared to normal concrete in structural designs. The novel punching shear test presented here has established itself as a suitable procedure for testing UHPFRC and potentially, other fibre reinforced composites

In Silico insights on the electrode high sensitivity to salts.

Recent findings in sensing and biosensing based on electrical measurements\ud point to a very high sensitivity, in which the introduction of one molecule of\ud an analyte into one million (or more) molecules of water is already detectable.\ud In some cases, the high sensitivity could be attributed to specific interactions\ud between the analyte and the molecules on the sensing unit, but results have\ud also been published of considerable sensitivity of bare electrodes for\ud molecules with no molecular recognition capability. This is the case of\ud some electronic tongues reported in the literature. lt seems that the presence\ud of trace amounts of the analyte, e.g. a NaCl molecule, is sufficient to ai ter the\ud properties of the water at the interface, particularly because the electrical\ud measurements are very sensitive to interface changes.CAPESCNPqFAPESPNSF/US

Insights from Coarse-Grained Gō Models for Protein Folding and Dynamics

Exploring the landscape of large scale conformational changes such as protein folding at atomistic detail poses a considerable computational challenge. Coarse-grained representations of the peptide chain have therefore been developed and over the last decade have proved extremely valuable. These include topology-based Gō models, which constitute a smooth and funnel-like approximation to the folding landscape. We review the many variations of the Gō model that have been employed to yield insight into folding mechanisms. Their success has been interpreted as a consequence of the dominant role of the native topology in folding. The role of local contact density in determining protein dynamics is also discussed and is used to explain the ability of Gō-like models to capture sequence effects in folding and elucidate conformational transitions