Arbuscular mycorrhizal community composition associated with two plant species in a grassland ecosystem

Arbuscular mycorrhizal (AM) fungi are biotrophic symbionts colonizing about two-thirds of land plant species and found in all ecosystems. They are of major importance in plant nutrient supply and their diversity is suggested to be an important determinant of plant community composition. The diversity of the AM fungal community composition in the roots of two plant species (Agrostis capillaris and Trifolium repens) that co-occurred in the same grassland ecosystem was characterized using molecular techniques. We analysed the small subunit (SSU) ribosomal RNA gene amplified from a total root DNA extract using AM fungal-specific primers. A total of 2001 cloned fragments from 47 root samples obtained on four dates were analysed by restriction fragment length polymorphism, and 121 of them were sequenced. The diversity found was high: a total of 24 different phylotypes (groups of phylogenetically related sequences) colonized the roots of the two host species. Phylogenetic analyses demonstrate that 19 of these phylotypes belonged to the Glomaceae, three to the Acaulosporaceae and two to the Gigasporaceae. Our study reveals clearly that the AM fungal community colonizing T. repens differed from that colonizing A. capillaris, providing evidence for AM fungal host preference. In addition, our results reveal dynamic changes in the AM fungal community through time

Dual-mode model predictive control of an omnidirectional wheeled inverted pendulum

This article describes the position and heading control of a novel form of omnidirectional wheeled inverted pendulum platform known as a Collinear Mecanum Drive. This concept uses four collinear Mecanum wheels to balance in a similar manner to a typical two-wheeled inverted pendulum, whilst also being able to simultaneously translate directly along its balance axis. Control is performed using a constrained time-optimal infinite horizon model predictive controller, with feasibility maintained across the full reference input set. Explored in this article is the derivation of the system dynamics model and controller, a systematic approach to selection of controller parameters and analysis of their effect on control performance and complexity, and an evaluation of the controller's efficacy in both simulation and on a real-world experimental prototype for simple and complex trajectories

Velocity constrained trajectory generation for a collinear Mecanum wheeled robot

While much research has been conducted into the generation of smooth trajectories for underactuated unstable aerial vehicles such as quadrotors, less attention has been paid to the application of the same techniques to ground based omnidirectional dynamically balancing robots. These systems have more control authority over their linear accelerations than aerial vehicles, meaning trajectory smoothness is less of a critical design parameter. However, when operating in indoor environments these systems must often adhere to relatively low velocity constraints, resulting in very conservative trajectories when enforced using existing trajectory optimisation methods. This paper makes two contributions; this gap is bridged by the extension of these existing methods to create a fast velocity constrained trajectory planner, with trajectory timing characteristics derived from the optimal minimum-time solution of a simplified acceleration and velocity constrained model. Next, a differentially flat model of an omnidirectional balancing robot utilizing a collinear Mecanum drive is derived, which is used to allow an experimental prototype of this configuration to smoothly follow these velocity constrained trajectories

Establishing and maintaining international collaborative research teams: an autobiographical insight

Despite the growing impetus for international collaborative research teams (ICRT), there are relatively few resources available to guide and support researchers through the processes of establishing and maintaining ICRTs. In particular, no articles were found that provided researchers’ firsthand accounts of being a member of such a team. Having access to such personal accounts can help both experienced and novice researchers learn more directly about what to expect, as well as the benefits, challenges, pitfalls, and success strategies for establishing and maintaining ICRTs. The authors used phenomenological autobiographical reflective journaling to capture their experiences as members of ICRTs. In this article we provide an overview of key themes that emerged from the analysis of our reflections as members of ICRTs. These themes include: benefits, challenges, and strategies for success. Our aim is to share our first-hand experiences of what it is like to establish and participate in ICRT. It is not our intention to provide readers with prescriptive guidelines on how to set up and maintain ICRTs. Every ICRT is unique and some of these ideas may or may not apply in every case. Instead, we are describing what worked for us, hoping that others may benefit from our experience. Consequently, we suggest that the focus of ICRT should be on the benefits thereof which promote and encourage interaction between disciplines, transfer of knowledge and techniques and personal and professional development.Web of Scienc

The effect of cellulose and starch on the viscoelastic and thermal properties of acid-swollen collagen paste

Collagen pastes are processed materials obtained through the swelling of minced bovine hides using acids into a fibrous swollen structure. Depending on the application, there is a need to improve the performance of these pastes in terms of rheological properties and mechanical strength of the final product. In this work, the addition of cellulose fibres and starch granules as fillers in acid swollen collagen paste was investigated. The influence of cellulose fibre length and starch granules with different amylose and amylopectin content on the viscoelastic and thermal properties of acid swollen paste were studied as a function of mixing ratio and collagen paste concentration. Addition of cellulose and starch granules resulted in an increase in the elastic modulus of the collagen paste with the starch granules having the highest impact. Addition of cellulose and starch also affected the tan δ peak of collagen paste at different collagen concentrations as a function of temperature. The micro differential scanning calorimetry (microDSC) results indicated that the denaturation temperature value of collagen was not influenced by the presence of cellulose and starch. However, upon reheating the denaturation temperature of collagen pastes wit starch granules shifted to lower temperatures

Design and control of a novel omnidirectional dynamically balancing platform for remote inspection of confined and cluttered environments

Remote inspection is a long standing field of interest for robotics researchers, in which robots are used to undertake inspection tasks in environments too hazardous or inaccessible to be directly entered by a human. Recent advances in gridscale battery storage have created a new set of unique hazardous indoor spaces with characteristics unsuitable for the deployment of existing teleoperated inspection robots. This paper outlines the problems encountered in these new environments, analyses existing approaches to robotic platform design, and proposes a better suited novel platform design, based on a dynamically balancing arrangement of Mecanum wheels. Its inverse kinematic and dynamics models are developed, a proof of concept prototype is constructed, and a constrained predictive controller is derived from the developed model. Experimental results demonstrate the efficacy of this new concept

The cardiac complications of COVID-19; many publications, multiple uncertainties

Since the first description of COVID-19 in December 2019, more than 63,000 publications have described its virology, clinical course, management, treatment and prevention. Most physicians are now encountering, or will soon encounter, patients with COVID-19 and must attempt to simultaneously assimilate this avalanche of information while managing an entirely novel disease with few guiding precedents. It is increasingly clear that, although primarily a respiratory illness, COVID-19 is associated with cardiovascular complications. However, the true incidence of direct cardiac complications remains unclear, as all complications thus far reported can also occur in patients without COVID19. In this review, we briefly summarise and critically appraise the data on cardiac complications associated with COVID-19 and describe some cases from our own experience. We identify unresolved questions and highlight the many uncertainties in this developing field