Effects of Industry Concentration on Quality Choices for Network Connectivity

I examine the effects of market concentration on connectivity in network industries. Using Cournot interactions for a duopoly, each network chooses quantity, quality for communications within the provider's own network (internal quality), and quality for communications between the provider's network and other networks (external quality). I find that large networks choose higher internal quality than do small networks and large networks choose higher internal quality than external quality. I also find that providers prefer flexible technologies that allow them to simultaneously choose outputs and qualities. Small networks prefer higher external quality than internal quality except when they make credible quality commitments before choosing output and have higher marginal operating costs than large networks. Networks choose identical external quality unless they have exogenously determined customer bases

Effects of Industry Concentration on Quality Choices for Network Connectivity

I examine the effects of market concentration on connectivity in network industries. Using Cournot interactions for a duopoly, each network chooses quantity, quality for communications within the provider's own network (internal quality), and quality for communications between the provider's network and other networks (external quality). I find that large networks choose higher internal quality than do small networks and large networks choose higher internal quality than external quality. I also find that providers prefer flexible technologies that allow them to simultaneously choose outputs and qualities. Small networks prefer higher external quality than internal quality except when they make credible quality commitments before choosing output and have higher marginal operating costs than large networks. Networks choose identical external quality unless they have exogenously determined customer bases

Data dictionary services in XNAT and the Human Connectome Project

The XNAT informatics platform is an open source data management tool used by biomedical imaging researchers around the world. An important feature of XNAT is its highly extensible architecture: users of XNAT can add new data types to the system to capture the imaging and phenotypic data generated in their studies. Until recently, XNAT has had limited capacity to broadcast the meaning of these data extensions to users, other XNAT installations, and other software.We have implemented a data dictionary service for XNAT, which is currently being used on ConnectomeDB, the Human Connectome Project (HCP) public data sharing website. The data dictionary service provides a framework to define key relationships between data elements and structures across the XNAT installation. This includes not just core data representing medical imaging data or subject or patient evaluations, but also taxonomical structures, security relationships, subject groups, and research protocols. The data dictionary allows users to define metadata for data structures and their properties, such as value types (e.g. textual, integers, floats) and valid value templates, ranges, or field lists. The service provides compatibility and integration with other research data management services by enabling easy migration of XNAT data to standards-based formats such as RDF, JSON, and XML. It also facilitates the conversion of XNAT’s native data schema into standard neuroimaging ontology structures and provenances.<br/

Breast cancer chemotherapy vascular toxicity: A review of mediating mechanisms and exercise as a potential therapeutic

Breast cancer chemotherapy, although very potent against tumour tissue, results in significant cardiovascular toxicity. The focus of research in this area has been predominantly towards cardiotoxicity. There is limited evidence detailing the impact of such treatment on the vasculature despite its central importance within the cardiovascular system and resultant detrimental effects of damage and dysfunction. This review highlights the impact of chemotherapy for breast cancer on the vascular endothelium. We consider the most likely mechanisms of endothelial toxicity to be through direct damage and dysfunction of the endothelium. There are sharp consequences of these detrimental effects as they can lead to cardiovascular disease. However, there is potential for exercise to alleviate some of the vascular toxicity of chemotherapy, and the evidence for this is provided. The potential role of exercise in protecting against vascular toxicity is explained, highlighting the recent in-human and animal model exercise interventions. Lastly, the mediating mechanisms of exercise protection of endothelial health is discussed, focusing on the importance of exercise for endothelial health, function, repair, inflammation and hyperlipidaemia, angiogenesis, and vascular remodelling. These are all important counteracting measures against chemotherapy-induced toxicity and are discussed in detail

Vascular Ageing and Exercise: Focus on Cellular Reparative Processes

Ageing is associated with an increased risk of developing noncommunicable diseases (NCDs), such as diabetes and cardiovascular disease (CVD). The increased risk can be attributable to increased prolonged exposure to oxidative stress. Often, CVD is preceded by endothelial dysfunction, which carries with it a proatherothrombotic phenotype. Endothelial senescence and reduced production and release of nitric oxide (NO) are associated with “vascular ageing” and are often accompanied by a reduced ability for the body to repair vascular damage, termed “reendothelialization.” Exercise has been repeatedly shown to confer protection against CVD and diabetes risk and incidence. Regular exercise promotes endothelial function and can prevent endothelial senescence, often through a reduction in oxidative stress. Recently, endothelial precursors, endothelial progenitor cells (EPC), have been shown to repair damaged endothelium, and reduced circulating number and/or function of these cells is associated with ageing. Exercise can modulate both number and function of these cells to promote endothelial homeostasis. In this review we look at the effects of advancing age on the endothelium and these endothelial precursors and how exercise appears to offset this “vascular ageing” process

Exercise acutely increases vitamin D receptor expression in T lymphocytes in vitamin D-deficient men, independent of age

Vitamin D plays a key role in the modulation of the immune system, mediated through the intracellular vitamin D receptor (VDR). Exercise has been shown to influence the activity and availability of the VDR. This study aimed to investigate the effect of age on basal immune cell (T-lymphocytes) VDR expression and the subsequent effect of acute aerobic exercise to modulate VDR expression in peripheral T-cells. Thirty-five males were included in the study (means ± SD: age 44 ± 17 y, BMI 25.7 ± 3.1 kg·m-2), separated into three age groups: 18-30 y (n=12), 31-45 y (n=11), and 60-75 y (n=12). Participants completed two trials: control (CON) and aerobic exercise (AE), with blood samples collected pre- and post-exercise (0 h, 1h, and 3 h). Peripheral blood T-cells were isolated and analysed for VDR expression by flow cytometry. The results show that advanced age is associated with lower VDR expression in T-cells (882 ± 274 vs 796 ± 243 vs 594 ± 174 geomean). Acute AE was successful at acutely increasing VDR expression in T-cells, irrespective of age. Advanced age corresponds to a lower T cell VDR expression, which may be responsible for age-associated development of chronic conditions and autoimmunity. Exercise was successful in increasing VDR expression in T-cells irrespective of age and independent of exercise-induced T cell mobilisation

Trail use, motivations and environmental attitudes of 3780 European mountain bikers: what is sustainable?

Background: The extent to which mountain biking impacts upon the environment is largely determined by rider behaviours. The purpose of this study was to gain a better understanding of how mountain bikers interact with the natural environment and explore their attitudes towards sustainability. Methods: 3780 European mountain bikers completed an online cross-sectional survey. Results: Connection to nature was an important source of motivation and the use of mountain bike trails has increased rider’s appreciation of and willingness to protect nature, with a large majority having taken direct action to do so. Mountain bikers are prepared to contribute towards trail maintenance through the provision of labour or financially. Although most mountain bikers make use of wet trails and illegal trails, incidence of conflict is relatively low. A range of characteristics were identified as being fundamental elements of sustainable trails, both in relation to the sustainability of the trail itself and in terms of wider environmental sustainability. Conclusions: European mountain bikers care about the sustainability of the natural environment. Self-reported attitudes and behaviours suggest a willingness to reduce environmental impact and actively protect nature

Blood flow restriction exercise attenuates the exercise-induced endothelial progenitor cells in healthy, young men.

Endothelial progenitor cells (EPCs) are a vasculogenic subset of progenitors, which play a key role in maintenance of endothelial integrity. These cells are exercise-responsive, and thus exercise may play a key role in vascular repair and maintenance via mobilization of such cells. Blood flow restriction exercise, due to the augmentation of local tissue hypoxia, may promote exercise-induced EPC mobilization. Nine, healthy, young (18-30yrs) males participated in the study. Participants undertook 2 trials of single leg knee extensor (KE) exercise, at 60% of thigh occlusion pressure (4 sets at 30% maximal torque) (BFR) or non- blood flow restricted (non-BFR), in a fasted state. Blood was taken prior, immediately after, and 30 minutes after exercise. Blood was used for the quantification of haematopoietic progenitor cells (HPCs: CD34+CD45dim), EPCs (CD34+VEGFR2+/CD34+CD45dimVEGFR2+) by flow cytometry. Our results show that unilateral KE exercise did not affect circulating HPC levels (p = 0.856), but did result in increases in both CD34+VEGFR2+ and CD34+CD45dimVEGFR2+ EPCs, but only in the non-BFR trial (CD34+VEGFR2+: 269 ± 42 cells·mL-1 to 573 ± 90 cells·mL-1, pre- to immediately post-exercise, p = 0.008; CD34+CD45dimVEGFR2+: 129 ± 21 cells·mL-1 to 313 ± 103 cells·mL-1, pre- to 30 min post-exercise, p = 0.010). In conclusion, low intensity BFR exercise did not result in significant circulating changes in EPCs in the post-exercise recovery period and may impair exercise-induced EPC mobilization compared to non-BFR exercise

Immune Response of Elite Enduro Racers to Laboratory and Racing Environments: The Influence of Training Impulse and Vibration

Introduction: Understanding the sport-specific immune response elicited during both training and competition is imperative to maximise athlete health and performance. Despite a growing population of professional enduro mountain bike athletes, little is known about the recovery of the immune system following enduro racing events. Methods: Nine international level elite enduro mountain bike athletes (age 24.3 ± 2.4 years, height 178.5 ± 8.7 cm, mass 76.5 ± 12.5 kg) completed a laboratory-based maximal exercise test (LAB) on a cycle ergometer and competed in an international mountain bike enduro race event (RACE). Blood samples were taken before, immediately after, and 1 h after LAB and before, 1 h after, and 17 h after RACE. Leukocyte subsets were enumerated using seven-colour flow cytometry. Lucia’s training impulse (LuTRIMP) and vibration exposure (VIB) were quantified during RACE. Results: Seven participants were included in the final analyses. There was a significant (p 0.05). Cell subset redistribution from pre- to post-one-hour time points (%Δpre-post1h) in cell subsets with potent effector functions (Neutrophils, CD3−/CD56+ NK-cells, CD8+/CD62L−/CD45RA− T-cells, CD8+/CD27+/CD28− T-cells, and CD3−/CD56dim/CD57− NK-cells) was significantly greater at RACE than LAB (p < 0.05). VIB was shown to be a superior predictor of %Δpre-post1h CD4+ T-cells, CD4+ early T-cells, CD4+ naïve T-cells, and NK cells as compared with LuTRIMP on its own (ΔR2 = 0.63 − 0.89, p < 0.05). Conclusions: The race event offers a greater challenge to the immune system than LAB, and potentially, whole body vibration is a key component of training load measurement in mountain bike applications