A model for evolution and extinction

We present a model for evolution and extinction in large ecosystems. The model incorporates the effects of interactions between species and the influences of abiotic environmental factors. We study the properties of the model by approximate analytic solution and also by numerical simulation, and use it to make predictions about the distribution of extinctions and species lifetimes that we would expect to see in real ecosystems. It should be possible to test these predictions against the fossil record. The model indicates that a possible mechanism for mass extinction is the coincidence of a large coevolutionary avalanche in the ecosystem with a severe environmental disturbance.Comment: Postscript (compressed etc. using uufiles), 16 pages, with 15 embedded figure

Indianapolis v. Edmond and the Original Understanding of the Fourth Amendment

In this article I examine to what extent Indianapolis v. Edmond is in keeping with the original understanding of the Fourth Amendment. I conclude that the Founders were much more concerned with searches of real property, often insisting, not only on suspicion, but also a on warrant when searches of real property are involved. Secondly, while the Founders did not consider warrants necessary for searches and seizures off of real property (which for the sake of simplicity I call searches in public areas) the evidence suggests suspicion was required. Indeed, the Fourth Amendment was a direct response to the British general warrant, which did not require particularized individual suspicion. I suggest that the suspicionless search in Indianapolis is not in keeping with the original understanding of the Fourth Amendment

Dissection of Nodule Development by Supplementation of \u3cem\u3eRhizobium leguminosarum\u3c/em\u3e biovar \u3cem\u3ephaseoli\u3c/em\u3e Purine Auxotrophs with 4-Aminoimidazole-5-Carboxamide Riboside

Purine auxotrophs of Rhizobium leguminosarum biovar phaseoli CFN42 elicit uninfected pseudonodules on bean (Phaseolus vulgaris L.). Addition of 4-aminoimidazole-5-carboxamide (AICA) riboside to the root medium during incubation of the plant with these mutants leads to enhanced nodule development, although nitrogenase activity is not detected. Nodules elicited in this manner had infection threads and anatomical features characteristic of normal nodules, such as peripheral vasculature rather than the central vasculature of the pseudonodules that were elicited without AICA riboside supplementation. Although 105 to 106 bacteria could be recovered from these nodules after full development, bacteria were not observed in the interior nodule cells. Instead, large cells with extensive internal membranes were present. Approximately 5% of the normal amount of leghemoglobin and 10% of the normal amount of uricase were detected in these nodules. To promote the development of true nodules rather than pseudonodules, AICA riboside was required no later than the second day through no more than the sixth day following inoculation. After this period, removal of AICA riboside from the root medium did not prevent the formation of true nodules. This observation suggests that there is a critical stage of infection, reached before nodule emergence, at which development becomes committed to forming a true nodule rather than a pseudonodule

A Model for Church Growth Groups

Cell groups are a feature of the most rapidly growing churches in Australia. Cell groups will probably lead to church growth for the Seventh-day Adventist Church. For this reason it has been seen as significant to develop and evaluate a model for integrating Cell Groups, renamed as Church Growth Groups, into the Seventh-day Adventist Church

Infection of Soybean and Pea Nodules by \u3cem\u3eRhizobium\u3c/em\u3e spp. Purine Auxotrophs in the Presence of 5-aminoimidazole-4-Carboxamide Riboside

Purine auxotrophs of various Rhizobium species are symbiotically defective, usually unable to initiate or complete the infection process. Earlier studies demonstrated that, in the Rhizobium etli-bean symbiosis, infection by purine auxotrophs is partially restored by supplementation of the plant medium with 5-amino-imidazole-4-carboxamide (AICA) riboside, the unphosphorylated form of the purine biosynthetic intermediate AICAR. The addition of purine to the root environment does not have this effect. In this study, purine auxotrophs of Rhizobium fredii HH303 and Rhizobium leguminosarum 128C56 (bv. viciae) were examined. Nutritional and genetic characterization indicated that each mutant was blocked in purine biosynthesis prior to the production of AICAR. R. fredii HH303 and R. leguminosarum 128C56 appeared to be deficient in AICA riboside transport and/or conversion into AICAR, and the auxotrophs derived from them grew very poorly with AICA riboside as a purine source. All of the auxotrophs elicited poorly developed, uninfected nodules on their appropriate hosts. On peas, addition of AICA riboside or purine to the root environment led to enhanced nodulation; however, infection threads were observed only in the presence of AICA riboside. On soybeans, only AICA riboside was effective in enhancing nodulation and promoting infection. Although AICA riboside supplementation of the auxotrophs led to infection thread development on both hosts, the numbers of bacteria recovered from the nodules were still 2 or more orders of magnitude lower than in fully developed nodules populated by wild-type bacteria. The ability to AICA riboside to promote infection by purine auxotrophs, despite serving as a very poor purine source for these strains, supports the hypothesis that AICAR plays a role in infection other than merely promoting bacterial growth

The Impact on Older People’s Wellbeing of Leaving Heritage Volunteering and the Challenges of Managing this Process

The benefits of volunteering for older volunteers and for the organisations who host them is well-documented. The impact of being obliged to leave volunteering due to age-related conditions, and any challenges that this creates for volunteer managers, are under-researched. This study explored how volunteers and volunteer managers experienced this point in the volunteering lifecycle and whether the topic warranted further research. Semi-structured interviews were carried out with fourteen older people, who were (or had been) volunteers at one of three cultural heritage organisations in the north-east of England alongside seven volunteer managers from those organisations. These represented the diversity of heritage organisations in the region. Volunteers discussed leaving volunteering in terms of loss but also indicated that forms of personal appraisal and agency were possible, ameliorating the impact of leaving. Volunteer managers discussed how organisational frameworks and the relationships they formed with volunteers shaped their practices. These relationships created a sense of organisational reciprocity which led some managers to exceed the rules in order to sustain people in their volunteering. The results suggest that supporting personal agency could ameliorate the impact of leaving volunteering but that organisations would benefit from articulating the extent and the limits of that support

Journalists and Safety Training: Experiences and Opinions

Over the last generation, safety trainings (sometimes known as Hostile Environment and First Aid Training or HEFAT) have been widely embraced by the news industry as a means of preparing journalists to cover conflict, crisis and other potentially dangerous assignments. Yet the effectiveness, relevance and usefulness of such trainings – both generally and in terms of specific content and approaches – have not been independently assessed. For this reason, the Dart Center for Journalism and Trauma, a project of the Graduate School of Journalism at Columbia University, surveyed a wide range of journalists around the world about the safety trainings they attended, the skills they acquired and the gaps between these trainings and their professional needs on the ground. From October 2016 to February 2017, 247 journalists completed the survey, which was conducted by the Dart Center’s research lab housed at The University of Tulsa Department of Psychology. This report, prepared by an interdisciplinary team of researchers in psychology, occupational safety and journalism practice, details the survey results. We make no attempt to evaluate particular commercial or nonprofit safety training providers. Instead, this report examines the various approaches to journalism safety training; how journalists assess their training experiences; and the systematic gaps and other issues suggested by their assessments