Continuous Damage Fiber Bundle Model for Strongly Disordered Materials

We present an extension of the continuous damage fiber bundle model to describe the gradual degradation of highly heterogeneous materials under an increasing external load. Breaking of a fiber in the model is preceded by a sequence of partial failure events occurring at random threshold values. In order to capture the subsequent propagation and arrest of cracks, furthermore, the disorder of the number of degradation steps of material constituents, the failure thresholds of single fibers are sorted into ascending order and their total number is a Poissonian distributed random variable over the fibers. Analytical and numerical calculations showed that the failure process of the system is governed by extreme value statistics, which has a substantial effect on the macroscopic constitutive behaviour and on the microscopic bursting activity as well.Comment: 10 pages, 13 figure

Eyes wide shut? UK consumer perceptions on aviation climate impacts and travel decisions to New Zealand

The purview of climate change concern has implicated air travel, as evidenced in a growing body of academic literature concerned with aviation CO2 emissions. This article assesses the relevance of climate change to long haul air travel decisions to New Zealand for United Kingdom consumers. Based on 15 semi-structured open-ended interviews conducted in Bournemouth, UK during June 2009, it was found that participants were unlikely to forgo potential travel decisions to New Zealand because of concern over air travel emissions. Underpinning the interviewees’ understandings and responses to air travel’s climate impact was a spectrum of awareness and attitudes to air travel and climate change. This spectrum ranged from individuals who were unaware of air travel’s climate impact to those who were beginning to consume air travel with a ‘carbon conscience’. Within this spectrum were some who were aware of the impact but not willing to change their travel behaviours at all. Rather than implicating long haul air travel, the empirical evidence instead exemplifies changing perceptions towards frequent short haul air travel and voices calls for both government and media in the UK to deliver more concrete messages on air travel’s climate impact

The Effect of Habitual Smoking on VO2max

VO2max is associated with many factors, including age, gender, physical activity, and body composition. It is popularly believed that habitual smoking lowers aerobic fitness. PURPOSE: to determine the effect of habitual smoking on VO2max after controlling for age, gender, activity and BMI. METHODS: 2374 men and 375 women employed at the NASA/Johnson Space Center were measured for VO2max by indirect calorimetry (RER>=1.1), activity by the 11 point (0-10) NASA Physical Activity Status Scale (PASS), BMI and smoking pack-yrs (packs day*y of smoking). Age was recorded in years and gender was coded as M=1, W=0. Pack.y was made a categorical variable consisting of four levels as follows: Never Smoked (0), Light (1-10), Regular (11-20), Heavy (>20). Group differences were verified by ANOVA. A General Linear Models (GLM) was used to develop two models to examine the relationship of smoking behavior on VO2max. GLM #1(without smoking) determined the combined effects of age, gender, PASS and BMI on VO2max. GLM #2 (with smoking) determined the added effects of smoking (pack.y groupings) on VO2max after controlling for age, gender, PASS and BMI. Constant errors (CE) were calculated to compare the accuracy of the two models for estimating the VO2max of the smoking subgroups. RESULTS: ANOVA affirmed the mean VO2max of each pack.y grouping decreased significantly (p<0.01) as the level of smoking exposure increased. GLM #1 showed that age, gender, PASS and BMI were independently related with VO2max (R2 = 0.642, SEE = 4.90, p<0.001). The added pack.y variables in GLM #2 were statistically significant (R2 change = 0.7%, p<0.01). Post hoc analysis showed that compared to Never Smoked, the effects on VO2max from Light and Regular smoking habits were -0.83 and -0.85 ml.kg- 1.min-1 respectively (p<0.05). The effect of Heavy smoking on VO2max was -2.56 ml.kg- 1.min-1 (p<0.001). The CE s of each smoking group in GLM #2 was smaller than the CE s of the smoking group counterparts in GLM #1. CONCLUSIONS: After accounting for the effects of gender, age, PASS and BMI the effect of habitual smoking on reducing VO2max is minimal, about 0.85 ml/kg/min, until the habit exceeds 20 pack.y at which point an additional decrease of 1.71 ml/kg/min is noted. Adding pack.y data improves the accuracy of predicting the VO2max of smokers

Missing Attention to Power Dynamics in Collaborative Multi-Actor Business Models for Sustainability

Advances within the Sustainability Business Models (SBMs) literature from the perspective of boundary-spanning business models have received limited attention. Further, discourse within the SBMs literature exploring collaborative practices adopts the perspective that collaborative forums are always a ‘force for good’. This paper reviews important theories and relevant literature and calls into question the dearth of research examining business models for sustainability and focuses on the role that power, and power relations, play in the shaping and steering of value creation. In advancing research on sustainable operations, we assess the implications of ignoring uneven power, and draw attention to the affects and consequences of this omission in the study of SBMs. By embracing an alternative, deliberative democracy perspective, we challenge the sub-literature on collaborative multi-actor business models. In taking an inquisitive and critical stance on omnipresent power dynamics, we shine a light on the consequences of uneven power across multi-actor structures by augmenting research with practical insights from selected vignettes. Our proposed concept of a democratic business model for sustainability offers a new strand of theoretical development and a fresh perspective on the sustainability and business models literature

Organisational institutionalisation of responsible innovation

© 2020 The Author(s) We describe the institutionalisation of responsible innovation (RI) over the last decade at the Engineering and Physical Sciences Research Council (EPSRC) and universities funded by it as a focal point for RI in the UK. Drawing on organisational theory we identify factors influencing the dynamics of RI institutionalisation, including forces of legitimation, entrepreneurship and decoupling. We report significant institutionalisation at the EPSRC prior to 2013, when it published its RI policy. Notwithstanding instances of experimentation and assimilation since, we report limited institutionalisation within research communities in universities as RI has encountered competing institutional logics, responsibility norms and epistemic practices. Our findings suggest an ongoing and dynamic process of translation that reflects RI's status as a performative and contested discourse ‘in the making’

Intelligent Control and Security of Fog Resources in Healthcare Systems via a Cognitive Fog Model

There have been significant advances in the field of Internet of Things (IoT) recently, which have not always considered security or data security concerns: A high degree of security is required when considering the sharing of medical data over networks. In most IoT-based systems, especially those within smart-homes and smart-cities, there is a bridging point (fog computing) between a sensor network and the Internet which often just performs basic functions such as translating between the protocols used in the Internet and sensor networks, as well as small amounts of data processing. The fog nodes can have useful knowledge and potential for constructive security and control over both the sensor network and the data transmitted over the Internet. Smart healthcare services utilise such networks of IoT systems. It is therefore vital that medical data emanating from IoT systems is highly secure, to prevent fraudulent use, whilst maintaining quality of service providing assured, verified and complete data. In this paper, we examine the development of a Cognitive Fog (CF) model, for secure, smart healthcare services, that is able to make decisions such as opting-in and opting-out from running processes and invoking new processes when required, and providing security for the operational processes within the fog system. Overall, the proposed ensemble security model performed better in terms of Accuracy Rate, Detection Rate, and a lower False Positive Rate (standard intrusion detection measurements) than three base classifiers (K-NN, DBSCAN and DT) using a standard security dataset (NSL-KDD)

Ion size effects at ionic exclusion from dielectric interfaces and slit nanopores

A previously developed field-theoretic model [R.D. Coalson et al., J. Chem. Phys. 102, 4584 (1995)] that treats core collisions and Coulomb interactions on the same footing is investigated in order to understand ion size effects on the partition of neutral and charged particles at planar interfaces and the ionic selectivity of slit nanopores. We introduce a variational scheme that can go beyond the mean-field (MF) regime and couple in a consistent way pore modified core interactions, steric effects, electrostatic solvation and image-charge forces, and surface charge induced electrostatic potential. We show that in the dilute limit, the MF and the variational theories agree well with MC simulation results, in contrast to a recent RPA method. The partition of charged Yukawa particles at a neutral dielectric interface (e.g air-water or protein-water interface) is investigated. It is shown that as a result of the competition between core collisions that push the ions towards the surface, and repulsive solvation and image forces that exclude them from the interface, a concentration peak of finite size ions sets in close to the dielectric interface. We also characterize the role played by the ion size on the ionic selectivity of neutral slit nanopores. We show that the complex interplay between electrostatic forces, excluded volume effects induced by core collisions and steric effects leads to an unexpected reversal in the ionic selectivity of the pore with varying pore size: while large pores exhibits a higher conductivity for large ions, narrow pores exclude large ions more efficiently than small ones

Three-dimensional electron microscopy reveals the evolution of glomerular barrier injury

Open access articleGlomeruli are highly sophisticated filters and glomerular disease is the leading cause of kidney failure. Morphological change in glomerular podocytes and the underlying basement membrane are frequently observed in disease, irrespective of the underlying molecular etiology. Standard electron microscopy techniques have enabled the identification and classification of glomerular diseases based on two-dimensional information, however complex three-dimensional ultrastructural relationships between cells and their extracellular matrix cannot be easily resolved with this approach. We employed serial block face-scanning electron microscopy to investigate Alport syndrome, the commonest monogenic glomerular disease, and compared findings to other genetic mouse models of glomerular disease (Myo1e−/−, Ptpro−/−). These analyses revealed the evolution of basement membrane and cellular defects through the progression of glomerular injury. Specifically we identified sub-podocyte expansions of the basement membrane with both cellular and matrix gene defects and found a corresponding reduction in podocyte foot process number. Furthermore, we discovered novel podocyte protrusions invading into the glomerular basement membrane in disease and these occurred frequently in expanded regions of basement membrane. These findings provide new insights into mechanisms of glomerular barrier dysfunction and suggest that common cell-matrix-adhesion pathways are involved in the progression of disease regardless of the primary insult