The permeability of fractured rocks in pressurised volcanic and geothermal systems

AbstractThe connectivity of rocks’ porous structure and the presence of fractures influence the transfer of fluids in the Earth’s crust. Here, we employed laboratory experiments to measure the influence of macro-fractures and effective pressure on the permeability of volcanic rocks with a wide range of initial porosities (1–41 vol. %) comprised of both vesicles and micro-cracks. We used a hand-held permeameter and hydrostatic cell to measure the permeability of intact rock cores at effective pressures up to 30 MPa; we then induced a macro-fracture to each sample using Brazilian tensile tests and measured the permeability of these macro-fractured rocks again. We show that intact rock permeability increases non-linearly with increasing porosity and decreases with increasing effective pressure due to compactional closure of micro-fractures. Imparting a macro-fracture both increases the permeability of rocks and their sensitivity to effective pressure. The magnitude of permeability increase induced by the macro-fracture is more significant for dense rocks. We finally provide a general equation to estimate the permeability of intact and fractured rocks, forming a basis to constrain fluid flow in volcanic and geothermal systems.</jats:p

Does heart rate influence CMR image quality of the coronary vessel wall?

Cardiolog

Development of a human factors roadmap for the successful implementation of industrial human-robot collaboration

The concept of industrial human-robot collaboration (HRC) is becoming increasingly integrated into manufacturing production lines as a means for enhancing productivity and product quality. However, developments have focused primarily on the technology and, until recently, little research has been geared to understand the key human factors (HF) that need to be considered to enable successful implementation of industrial HRC. Recent work by the authors has led to the identification of key organisational and individual level HF. The purpose of this paper is to draw together the evidence from their studies and propose a HF roadmap for the successful implementation of industrial HRC. The roadmap will have profound implications as it enables automation specialists and manufacturing system engineers to understand the key HF that need to be considered optimise the efficiency and productivity of the collaboration between humans and industrial robots

CT angiography; useful in non-selected outpatients?

Dance has been a part of the physical education (PE) curriculum in several countries for a longtime. In spite of this, studies demonstrate that the position of dance in the subject of PE iscontested and that little time is devoted to dance. The overall aim of this article is to examine theposition of dance as a pedagogical discourse in Swedish steering documents over time. Theempirical material consists of five Swedish curricula for PE over a period of 50 years (1962–2011).Discourse analysis is used to identify organised systems of meaning, including privileged andprioritised values. Our theoretical frame of reference draws on Bernstein’s concept of codes. Threedifferent knowledge areas within dance are found in the text material: ‘dance as cultural preserver’,‘dance as bodily exercise’ and ‘dance as expression’. Three pedagogical discourses emerge fromthese knowledge areas: an identity formation discourse, a public health discourse and an aestheticdiscourse. The identity formation discourse in earlier curricula focuses on the perpetuation ofSwedish and Nordic cultural traditions, while in later curricula, it emphasises the construction of abroader multicultural identity formation related to the understanding of different cultures. Thepublic health discourse constitutes a prioritised understanding of dance as physical training relatedto a healthy lifestyle. The aesthetic discourse, which has the weakest position over time, representsthe valuing of embodied experiences and feelings expressed through movements. This discourse isclosely linked to the construction of gender. Over time, a new performance code came to surpassthe former competence code in the steering documents. The performance code positions dance inPE as mainly a physical activity with little artistic or aesthetic value. The pedagogical discourse ofdance remains within a highly disciplinary framework of social control

Increased accuracy in computed tomography coronary angiography; a new body surface area adapted protocol

Vascular Biology and Interventio

100 kV versus 120 kV: effective reduction in radiation dose?

Atherosclerosi

Fingertip digital thermal monitoring: a fingerprint for cardiovascular disease?

Cardiac Dysfunction and Arrhythmia

Composite likelihood estimation of demographic parameters

which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Background: Most existing likelihood-based methods for fitting historical demographic models to DNA sequence polymorphism data to do not scale feasibly up to the level of whole-genome data sets. Computational economies can be achieved by incorporating two forms of pseudo-likelihood: composite and approximate likelihood methods. Composite likelihood enables scaling up to large data sets because it takes the product of marginal likelihoods as an estimator of the likelihood of the complete data set. This approach is especially useful when a large number of genomic regions constitutes the data set. Additionally, approximate likelihood methods can reduce the dimensionality of the data by summarizing the information in the original data by either a sufficient statistic, or a set of statistics. Both composite and approximate likelihood methods hold promise for analyzing large data sets or for use in situations where the underlying demographic model is complex and has many parameters. This paper considers a simple demographic model of allopatric divergence between two populations, in which one of the population is hypothesized to have experienced a founder event, or population bottleneck. A large resequencing data set from human populations is summarized by the joint frequency spectrum, which is a matrix of the genomic frequency spectrum of derived base frequencies in two populations. A Bayesia