On Torsion-Free Crawley Groups

The notion of a Crawley p-group is well known in Abelian group theory. In this present work, a corresponding concept is introduced for torsion-free groups. The principal result, which uses the set-theoretic notions of the diamond and Martin’s axiom, establishes an independence result for N1-free Crawley groups

Multi-Pulse Laser Wakefield Acceleration: A New Route to Efficient, High-Repetition-Rate Plasma Accelerators and High Flux Radiation Sources

Laser-driven plasma accelerators can generate accelerating gradients three orders of magnitude larger than radio-frequency accelerators and have achieved beam energies above 1 GeV in centimetre long stages. However, the pulse repetition rate and wall-plug efficiency of plasma accelerators is limited by the driving laser to less than approximately 1 Hz and 0.1% respectively. Here we investigate the prospects for exciting the plasma wave with trains of low-energy laser pulses rather than a single high-energy pulse. Resonantly exciting the wakefield in this way would enable the use of different technologies, such as fibre or thin-disc lasers, which are able to operate at multi-kilohertz pulse repetition rates and with wall-plug efficiencies two orders of magnitude higher than current laser systems. We outline the parameters of efficient, GeV-scale, 10-kHz plasma accelerators and show that they could drive compact X-ray sources with average photon fluxes comparable to those of third-generation light source but with significantly improved temporal resolution. Likewise FEL operation could be driven with comparable peak power but with significantly larger repetition rates than extant FELs

Laserwire at the Accelerator Test Facility 2 with Sub-Micrometre Resolution

A laserwire transverse electron beam size measurement system has been developed and operated at the Accelerator Test Facility 2 (ATF2) at KEK. Special electron beam optics were developed to create an approximately 1 x 100 {\mu}m (vertical x horizontal) electron beam at the laserwire location, which was profiled using a 150 mJ, 71 ps laser pulse with a wavelength of 532 nm. The precise characterisation of the laser propagation allows the non-Gaussian transverse profiles of the electron beam caused by the laser divergence to be deconvolved. A minimum vertical electron beam size of 1.07 ${\pm}$ 0.06 (stat.) ${\pm}$ 0.05 (sys.) {\mu}m was measured. A vertically focussing quadrupole just before the laserwire was varied whilst making laserwire measurements and the projected vertical emittance was measured to be 82.56 ${\pm}$ 3.04 pm rad.Comment: 17 pages, 26 figures, submitted to Phys. Rev. ST Accel. Beam

Wild Animal Tuberculosis: Stakeholder Value Systems and Management of Disease

When human health is put at risk from the transmission of animal diseases, the options for intervention often require input from stakeholders whose differing values systems contribute to decisions on disease management. Animal tuberculosis (TB), caused principally by Mycobacterium bovis is an archetypical zoonotic pathogen in that it can be transmitted from animals to humans and vice versa. Although elimination of zoonotic transmission of TB to humans is frequently promoted as the raison d'être for TB management in livestock, in many countries the control strategies are more likely based on minimizing the impact of sustained infection on the agricultural industry. Where wild animals are implicated in the epidemiology of the disease, the options for control and eradication can require involvement of additional stakeholder groups. Conflict can arise when different monetary and/or societal values are assigned to the affected animals. This may impose practical and ethical dilemmas for decision makers where one or more species of wild animal is seen by some stakeholders to have a greater value than the affected livestock. Here we assess the role of stakeholder values in influencing TB eradication strategies in a number of countries including Ireland, the UK, the USA, Spain, France, Australia, New Zealand and South Africa. What it reveals is that the level of stakeholder involvement increases with the complexity of the epidemiology, and that similar groups of stakeholders may agree to a set of control and eradication measures in one region only to disagree with applying the same measures in another. The level of consensus depends on the considerations of the reservoir status of the infected host, the societal values assigned to each species, the type of interventions proposed, ethical issues raised by culling of sentient wild animals, and the economic cost benefit effectiveness of dealing with the problem in one or more species over a long time frame. While there is a societal benefit from controlling TB, the means to achieve this requires identification and long-term engagement with all key stakeholders in order to reach agreement on ethical frameworks that prioritize and justify control options, particularly where culling of wild animals is concerned

DNA Typing of Mycobacterium bovis Isolates from Badgers (Meles meles) Culled from Areas in Ireland with Different Levels of Tuberculosis Prevalence

Badgers (Meles meles) have been implicated in the transmission of Mycobacterium bovis infection to cattle in Ireland and UK. Recent studies in Ireland have shown that although the disease is endemic in badgers, the prevalence of disease is not uniform throughout the country and can vary among subpopulations. The extent to which the prevalence levels in badgers impact on the prevalence in cattle is not known. Previously, DNA fingerprinting has shown that M. bovis strain types are shared between badgers and cattle, and that there are a large number of strain types circulating in the two species. In this study we have carried out spoligotyping and variable number tandem repeat (VNTR) analysis of M. bovis isolates from two groups of badgers, representing a wide geographic area, with different tuberculosis prevalence levels. The results of the typing show that there is no geographic clustering of strain types associated with prevalence. However, two VNTR profiles were identified that appear to be associated with high- and low-prevalence M. bovis infection levels, respectively. In addition, spoligotyping and VNTR analysis has provided evidence, for the first time, of multiple infections of individual badgers with different M. bovis strains

Mycobacterium bovis: A model pathogen at the interface of livestock, wildlife, and humans

Complex and dynamic interactions involving domestic animals, wildlife, and humans create environments favorable to the emergence of new diseases, or reemergence of diseases in new host species. Today, reservoirs of Mycobacterium bovis, the causative agent of tuberculosis in animals, and sometimes humans, exist in a range of countries and wild animal populations. Free-ranging populations of white-tailed deer in the US, brushtail possum in New Zealand, badger in the Republic of Ireland and the United Kingdom, and wild boar in Spain exemplify established reservoirs of M. bovis. Establishment of these reservoirs is the result of factors such as spillover from livestock, translocation of wildlife, supplemental feeding of wildlife, and wildlife population densities beyond normal habitat carrying capacities. As many countries attempt to eradicate M. bovis from livestock, efforts are impeded by spillback from wildlife reservoirs. It will not be possible to eradicate this important zoonosis from livestock unless transmission between wildlife and domestic animals is halted. Such an endeavor will require a collaborative effort between agricultural, wildlife, environmental, and political interests.Peer Reviewe

An intervention to improve outcomes of falls in dementia: the DIFRID mixed-methods feasibility study:A mixed methods study to develop and assess the feasibility of the DIFRID intervention

Background : Fall-related injuries are a significant cause of morbidity and mortality in people with dementia (PWD). There is presently little evidence to guide the management of such injuries, and yet there are potentially substantial benefits to be gained if the outcome of these injuries could be improved. This study aimed to design an appropriate new healthcare intervention for PWD following a fall and to assess the feasibility of its delivery in the UK National Health Service. Objective (s): To determine whether it is possible to design an intervention to improve outcomes of falls in dementia; to investigate the feasibility and acceptability of the DIFRID intervention; to investigate the feasibility of a future randomised controlled trial (RCT) and data collection tools needed to evaluate the effectiveness and efficiency of the DIFRID intervention. Design : Mixed-methods feasibility study. Methods : A systematic review (using Cochrane methodology) and realist review (using RAMESES methodology) explored the existing evidence base and developed programme theories. Searches were carried out in Nov 2015 (updated Jan 2018) for effectiveness studies and August 2016 for economic studies. A prospective observational study identified service use via participant diary completion. Qualitative methods (semi-structured interviews, focus groups, and observation) were used to explore: current practice; stakeholder perspectives of the health and social care needs of PWD following a fall; ideas for intervention; and barriers and facilitators to change. Each of these datasets informed intervention development, via Delphi consensus methods. Finally, a single-arm feasibility study with embedded process evaluation was conducted. Setting : Community. Participants : PWD presenting with falls needing healthcare attention in each setting at 3 sites and their carers. Professionals delivering the intervention, responsible for training and supervision and members of the intervention team. Professionals responsible for approaching and recruiting participants. Interventions: A complex multidisciplinary therapy intervention. Physiotherapists, occupational therapists, and support workers delivered up to 22 sessions of tailored activities in the PWD’s home or local area over a period of 12 weeks. Main outcome measures: Assessment of feasibility of study procedures; assessment of the acceptability, feasibility and fidelity of intervention components; assessment of suitability and acceptability of outcome measures for PWD and carers (number of falls; quality of life; fear of falling; activities of daily living; goal setting; health utilisation; carer burden). Results : A multidisciplinary intervention delivered in PWDs’ own homes was designed based on qualitative work, realist review and recommendations of the consensus panel. The intervention was delivered to 11 PWD. The study suggested that the intervention is both feasible and acceptable to stakeholders. A number of modifications was recommended to address some of the issues arising during feasibility testing. Measurement of outcome measures was successful. Limitations : Recruitment to the feasibility study was lower than expected and therefore the intervention needs to be tested with a larger number of PWD. Conclusions : The study has highlighted the feasibility of delivering a creative, tailored, individual approach to intervention for PWD following a fall. Although the intervention required greater investment of time than usual practice, many staff valued the opportunity to work more closely with PWD and carers. Future work : We conclude that further research is now needed to refine this intervention in the context of a pilot randomised controlled trial