Characterisation of the entomopathogenic nematode Heterorhabditis (Nematoda : Heterorhabditidae) from Ireland and Britain by molecular and cross-breeding techniques, and the occurrence of the genus in these islands

Des examens de sol ont été effectués en Irlande et en Grande-Bretagne pour rechercher les nématodes du genre #Heterorhabditis. Des échantillons des sols prélevés sur des sites sablonneux furent pourvus de larves de #Galleria mellonella comme appâts. Des #Heterorhabditis furent collectés sur 18 sites sur 169 en Irlande, 2 sur 51 dans le nord de l'Ecosse et 9 sur 20 dans le sud du Pays de Galle. Tous les sites positifs sont situés sur le littoral ; aucun #Heterorhabditis n'a été détecté dans les échantillons prélevés dans 40 sites situés à l'intérieur des terres. La totalité des 76 isolats recueillis au cours de ces analyses ont été identifiés comme appartenant au groupe irlandais d'#Heterorhabditis, à l'aide de méthodes de concentration isoélectrique, de restriction de l'ADN et d'hybridation. Aucun #Heterohabditis appartenant au groupe de l'Europe du nord-ouest n'a été recueilli. Cependant, un isolat recueilli par d'autres chercheurs et provenant du sud de l'Angleterre a été identifié comme appartenant à ce groupe. Les membres du groupe irlandais ne se croisent généralement pas avec les membres du groupe de l'Europe du nord-ouest, bien que des juvéniles infestants fertiles aient été produits dans un nombre limité (3/15) de croisements entre ces groupes. (Résumé d'auteur

Ricci-Flat Branes

Up to overall harmonic factors, the D8-brane solution of the massive type IIA supergravity theory is the product of nine-dimensional Minkowski space (the worldvolume) with the real line (the transverse space). We show that the equations of motion allow for the worldvolume metric to be generalised to an arbitrary Ricci-flat one. If this nine-dimensional Ricci-flat manifold admits Killing spinors, then the resulting solutions are supersymmetric and satisfy the usual Bogomol'nyi bound, although they preserve fewer than the usual one half of the supersymmetries. We describe the possible choices of such manifolds, elaborating on the connection between the existence of Killing spinors and the self-duality condition on the curvature two-form. Since the D8-brane is a domain wall in ten dimensions, we are led to consider the general case: domain walls in any supergravity theory. Similar considerations hold here also. Moreover, it is shown that the worldvolume of any magnetic brane --- of which the domain walls are a specific example --- can be generalised in precisely the same way. The general class of supersymmetric solutions have gravitational instantons as their spatial sections. Some mention is made of the worldvolume solitons of such branes.Comment: 26 pages, LaTe

Investigation of instabilities of photomultiplier tubes for multi-element detector systems

This paper presents an investigation into response of instabilities of EJ-309 liquid scintillator detectors. A brief review of common instabilities associated with the photomultiplier tubes (PMTs) is presented. The energy response, energy linearity and warm-up duration of sixteen EJ-309 detectors coupled to PMTs tested is presented. A single-channel mixed-field analyser digitiser system was used for data acquisition. Furthermore, timing information of the common instability behaviours is presented alongside suggestions on how to correct for such instabilities. The results show that a single-energy energy calibration is sufficient to ensure energy linearity; the detectors must be warmed-up by ~45 minutes before stable response is achieved; the re-warm-up duration depends on the duration of the high voltage supplied to the PMT being switched off. The results indicate that the PMTs take approximately 2 hours to reach "cold" state, where a full warm-up duration must be applied. The reported instability effects will be taken into account when developing a sophisticated auto-calibration methodology for a multi-element scintillator detector system

Interaction between toothbrushes and toothpaste abrasive particles in simulated tooth cleaning

There are currently many toothbrush designs on the market incorporating different filament configurations such as filaments at various angles and different lengths and made from several different materials. In order to understand how the tooth cleaning process occurs there is a need to investigate in detail how the abrasive particles in a toothpaste interact with the filaments in a teeth cleaning contact and cause material removal from a plaque or stain layer. The following describes the development of optical apparatus to enable the visualisation of simulated teeth cleaning contacts. Studies have been carried out using the apparatus to investigate particle entrainment into the contact and how it differs with varying bristle configurations. The effects of filament stiffness and tip shape were also investigated. Various types of electric toothbrushes were also tested. The studies have shown how particles are trapped at the tips of toothbrush filaments. Particles, suspended in fluid, approach the filament tips, as they pass through they may become trapped. Greater particle entrainment into the filament tip contact occurs with a reciprocating action at low filament loads and deflections than with a sliding motion. Large particles are less likely to enter tip contacts and are trapped between tips or under the filament bend at higher loads. Whether the particles are likely to be trapped and how long they remain so depends on the filament stiffness and degree of splay on loading and the filament configuration. The direction the filaments point in, the number of filaments in a tuft, the spacing of the tufts and the way the filaments splay when deflected all have an influence on entrainment of particles. Tufts with tightly packed stiff filaments which deflected together on loading were more effective at trapping particles than more flexible filaments that splayed out on loading as they present more of a barrier to particle entry and exit from the tip region

Real-time capabilities of a digital analyzer for mixed-field assay using scintillation detectors

Scintillation detectors offer a single-step detection method for fast neutrons and necessitate real-time acquisition, whereas this is redundant in two-stage thermal detection systems using helium-3 and lithium-6, where the fast neutrons need to be thermalized prior to detection. The relative affordability of scintillation detectors and the associated fast digital acquisition systems have enabled entirely new measurement setups that can consist of sizeable detector arrays. These detectors in most cases rely on photomultiplier tubes, which have significant tolerances and result in variations in detector response functions. The detector tolerances and other environmental instabilities must be accounted for in measurements that depend on matched detector performance. This paper presents recent advances made to a high-speed FPGA-based digitizer. The technology described offers a complete solution for fast-neutron scintillation detectors by integrating multichannel high-speed data acquisition technology with dedicated detector high-voltage supplies. This configuration has significant advantages for large detector arrays that require uniform detector responses. We report on bespoke control software and firmware techniques that exploit real-time functionality to reduce setup and acquisition time, increase repeatability, and reduce statistical uncertainties

Networks and coalitions in the implementation of the International Treaty on Plant Genetic Resources for Food and Agriculture in Uganda

Uganda acceded to the International Treaty for Plant Genetic Resources for Food and Agriculture (ITPGTFA) in the year 2003. Despite this, there are still gaps in implementation of the treaty in the country. The article provides insights into the systemic interactions and coalitions among actors in the implementation of the treaty and subsequent barriers to the implementation of the ITPGRFA. Using social network analysis, the interactions of 26 key policy actors are mapped for 4 main expertise networks that are important for implementation of the treaty; that is, the policy direction networks; scientific expertise; financial expertise; and legal networks in order to identify gaps for further action. Findings indicate that the linkages between actors are poor especially in the legal expertise and policy direction networks where the competent authority for the treaty does not have efficient connections with critical and non-critical actors. Many key actors are also excluded from the network leading poor information and resource flows among stakeholders implementing the treaty. In the interim, a memorandum of understanding has been signed by three major institutions that are key to establish clear processes for implementation of the treaty and establishing clear guidelines for access and benefit sharing and clear roles of institutions involved in the policy development and implementation. Key lessons learned from this research are that networks and coalitions are important for fostering information and exchange of expertise to enable effective implementation or domestication of the international treaty (IT). The structured engagement of other non-governmental stakeholders such as non-governmental organisations (NGOs) and international organizations that provide financial and technical support for various aspects of policy implementation is also important

A comparative study of the psychological problems of HIV-infected and HIV-uninfected children in a South African sample

According to research children living with HIV experience elevated levels of depression, anxiety, ADHD and disruptive behavioural disorders. Although South Africa’s paediatric population that is infected with the human immunodeficiency virus (HIV) is the largest worldwide, little research has been conducted on their mental health challenges. However, attributing high levels of mental health problems solely to their HIV status can be problematic as there may be other contributory factors. This research explored the mental health problems of HIV-infected children and compared these to the mental health problems of their HIV-unaffected peers from similar backgrounds. Data was gathered from two samples of child and caregiver pairs. HIV-infected children (aged 6–12 years) and their caregivers/mothers (n = 54) were recruited from the Kalafong paediatric clinic where they received medical treatment and routine ART. A comparison group of 113 HIV-uninfected children and their uninfected mothers were recruited from primary care clinics in the same community. Caregivers completed the Child Behaviour Checklist (CBCL) to assess children’s mental health. Children completed the Self-Description Questionnaire (SDQ-I) and the Revised Children’s Manifest Anxiety Scale (RCMAS). The scores of the psychometric sub-scales of the two groups were compared using parametric and non-parametric statistics. HIV-infected children experienced more somatic and affective problems, physiological anxiety, less ADHD and lower self-esteem than HIV-uninfected children in the comparison group, while controlling for age differences. The high levels of mental health problems of both groups of children may be attributed to similar difficult socio-economic circumstances. The fact that most infected children were not aware of their HIV-status could have influenced the results. Mental health services should not be limited to HIV-infected children but should form part of all health care services.http://www.tandfonline.com/loi/caic202019-01-22hj2018PsychologyStatistic