First motions from seismic sources near a free surface

The radiation patterns of first motions are calculated for the sudden occurrence of an arbitrarily oriented fault (dislocation) at the surface of a half space; the dislocation in the fault plane is also arbitrarily oriented and is assumed to occur over a very small area of the fault plane. Initially the source is considered at a finite depth and the solution is obtained by allowing the depth to tend to zero. In general the results show a surprising directionality for the radiation of SV. In the focal plane projection the first motions of P and SH for a strike-slip fault show the familiar four-lobed radiation patterns. The first motions of SV show some reversals in polarity with angular distance from the source. The first motions for all components of motion for a dip-slip fault have characteristics governed strongly by the presence of the free surface, and hence differ markedly from the usual radiation patterns for a deeply imbedded source

Convective instability of 3-D fluid-saturated geological fault zones heated from below

We conduct a theoretical analysis to investigate the convective instability of 3-D fluid-saturated geological fault zones when they are heated uniformly from below. In particular, we have derived exact analytical solutions for the critical Rayleigh numbers of different convective flow structures. Using these critical Rayleigh numbers, three interesting convective flow structures have been identified in a geological fault zone system. It has been recognized that the critical Rayleigh numbers of the system have a minimum value only for the fault zone of infinite length, in which the corresponding convective flow structure is a 2-D slender-circle flow. However, if the length of the fault zone is finite, the convective flow in the system must be 3-D. Even if the length of the fault zone is infinite, since the minimum critical Rayleigh number for the 2-D slender-circle flow structure is so close to that for the 3-D convective flow structure, the system may have almost the same chance to pick up the 3-D convective flow structures. Also, because the convection modes are so close for the 3-D convective flow structures, the convective flow may evolve into the 3-D finger-like structures, especially for the case of the fault thickness to height ratio approaching zero. This understanding demonstrates the beautiful aspects of the present analytical solution for the convective instability of 3-D geological fault zones, because the present analytical solution is valid for any value of the ratio of the fault height to thickness. Using the present analytical solution, the conditions, under which different convective flow structures may take place, can be easily determined

Contrasting effects of necrotrophic and biotrophic plant pathogens on the aphid Aphis fabae

Phytophagous insects have to contend with a wide variation in food quality brought about by a variety of factors intrinsic and extrinsic to the plant. One of the most important factors is infection by plant pathogenic fungi. Necrotrophic and biotrophic plant pathogenic fungi may have contrasting effects on insect herbivores due to their different infection mechanisms and induction of different resistance pathways, although this has been little studied and there has been no study of their combined effect. We studied the effect of the biotrophic rust fungus Uromyces viciae-fabae (Pers.) Schroet (Basidiomycota: Uredinales: Pucciniaceae) and the necrotrophic fungus Botrytis cinerea Pers. (Ascomycota: Helotiales: Sclerotiniaceae) singly and together on the performance of the aphid Aphis fabae Scop. (Hemiptera: Aphididae) on Vicia faba (L.) (Fabaceae). Alone, botrytis had an inhibitory effect on individual A. fabae development, survival and fecundity, while rust infection consistently enhanced individual aphids’ performance. These effects varied in linear relation to lesion or pustule density. However, whole-plant infection by either pathogen resulted in a smaller aphid population of smaller aphids than on uninfected plants, indicating a lowering of aphid carrying capacity with infection. When both fungi were applied simultaneously to a leaf they generally cancelled the effect of each other out, resulting in most performance parameters being similar to the controls, although fecundity was reduced. However, sequential plant infection (pathogens applied five days apart) led to a 70% decrease in fecundity and 50% reduction in intrinsic rate of increase. The application of rust before botrytis had a greater inhibitory effect on aphids than applying botrytis before rust. Rust infection increased leaf total nitrogen concentration by 30% while infection by botrytis with or without rust led to a 38% decrease. The aphids’ responses to the two plant pathogens individually is consistent with the alteration in plant nutrient content by infection and also the induction of different plant defence pathways and the possible cross-talk between them. This is the first demonstration of the complex effects of the dual infection of a plant by contrasting pathogens on insect herbivores. Key words: Vicia faba, Botrytis cinerea, Uromyces viciae-fabae, tripartite interactions, induced resistanc

Undertaking Doctoral Research with Children and Young People with Life-limiting or Life-threatening Conditions

Doctoral level research can contribute to the evidence base, particularly in under‐researched areas and numerically small fields such as children and young people's palliative care. It is acknowledged that much of what we currently do in children's and young people's palliative care is eminence‐based, rather than evidence‐based (Together for Short Lives, 2018). Whilst sharing experience and wisdom was valuable, particularly when the specialty was in its infancy, it is important now to develop an evidence base to ensure that children, young people and their families receive the highest standard of care. This requires fostering the development of a research culture, including trained clinical and non‐clinical researchers, who will pursue a penetrating and rigorous research agenda (Beecham et al., 2016)

Development of a research-based classification of approaches to paediatric palliative medicine service provision within children's and young adults' hospices: A mixed methods study.

BACKGROUND: Globally, pioneers in children's palliative care influenced this speciality's development through individual initiatives leading to diverse models of care. Children's and young adults' hospices have now been established around the world. However, service provision varies widely leading to inequities both within countries and internationally. AIM: To describe and classify existing approaches to paediatric palliative medicine in children's and young adults' hospices across the UK. DESIGN: A mixed methods study conducted by telephone interview. SETTING/PARTICIPANTS: Thirty-one leaders of children's hospice care, representing 28 services, 66% of UK children's and young adults' hospice organisations. RESULTS: A geographic-specialist classification was developed through integration of findings, enabling hospices to be classified as Regional specialist, Regional non-specialist, Local specialist and Local non-specialist. Both qualitative and quantitative data demonstrated diversity and inequity in paediatric palliative medicine provision. Of 159 doctors (63.5% of whom were general practitioners) working in participating hospices only 27.5% had specialist training in paediatric palliative medicine. The majority of participating hospices (67.9%) did not have involvement from a paediatric palliative medicine consultant. CONCLUSIONS: Internationally, the integration of specialist children's palliative care teams with existing services is a current challenge. Despite differing approaches to children's palliative care world-wide, models of care which facilitate integration of specialist children's palliative care could benefit a range of countries and contexts. The geographic-specialist classification could be used to inform recommendations for a networked approach to paediatric palliative medicine within children's and young adults' hospices to promote equity for children with life-limiting and life-threatening conditions