Ages of mutations on a coalescent tree

Using the coalescent process, DNA sequences of a sample of individuals can be used to study the phylogenetic history of the individuals. Under the infinitely-many-sites mutation model, the DNA sequence data can be summarized by the number of segregating sites (which is numerically equivalent to the number of mutations on the tree). A number of methods exist, including a recursive method presented in this paper, that obtain an estimate of the age of the most recent common ancestor (MRCA), given the number of mutations. This paper introduces a method for finding the ages of mutations, given the total number of mutations on the tree. While the result is not useful in estimating the age of a specific segregating site, it is useful in examining the underlying assumption of a relatively constant population over time. This utilization of the result is illustrated using DNA sequence data obtained from a sample of Amerindians of the Nuu-Chah-Nulth tribe.

A novel method for the isolation of motile bacteria using gradient culture systems

Isolation of motile bacteria from stream water samples was achieved by using Lutrol F127 (poloxamer 407) as a gelling agent in culture media. This block copolymer has the property of repeatedly liquefying and solidifying at low and high temperatures, respectively. The ability of motile bacteria to move through liquid-state Lutrol F127 towards a higher nutrient concentration was exploited. After establishment of the nutrient gradient and inoculation, the system was cooled to liquefy the medium and kept liquid to allow motile bacteria to move. Raising the temperature allowed solidification and prevented further movement. Colonies could be easily removed. The proportion of motile isolates (determined by microscopic observation) increased from 42% in the indigenous population to 100% after isolation using the gradient system.

Predicting gender from electronic discourse

There is substantial evidence of gender differences in face-to-face communication, and we suspect that similar differences are present in electronic communication. We designed three studies to examine gender-preferential language style in electronic discourse. In Expt 1, participants sent electronic messages to a designated 'netpal'. A discriminant analysis showed that it was possible to successfully classify the participants by gender with 91.4% accuracy. In Expts 2 and 3, we wanted to determine whether readers of e-mails could accurately identify author gender. We gave participants a selection of messages from Expt 1 and asked them to predict the author's gender. It was found that for 14 of the 16 messages used, the gender of author was correctly predicted. In the third experiment, six messages about gender-neutral topics were composed. Using a subset of the variables identified in Expt 1, female and male versions of each message were created. When participants were asked to rate whether a female or a male wrote these messages, their ratings differed as a function of the message version. These findings establish that people use gender-preferential language in informal electronic discourse. Furthermore, readers of these messages can use these gender-linked language differences to identify the author's gender.

DILEMMA: logic engineering in primary care, shared care and oncology (AIM Project A2005)

The aim of DILEMMA is to provide tools for the development of decision support systems for use in general medical practice, hospital-based cancer care, and shared care of cancer and cardiology patients. In primary care, the project intends to provide aids to clinical performance in prescribing, referral and the use of clinical guidelines. The demonstrator applications involve telematics and knowledge-based methodology, using an approach termed logic engineering which combines logic programming and software lifecycle methods. DILEMMA will demonstrate systems to assist shared care and home care which should help reduce pressure on secondary health resources and, by disseminating best practice knowledge, improve patient care and patient quality of life.

The impact of Multiple Mini Interviews on the attrition and academic outcomes of midwifery students

BACKGROUND

Admission to the Bachelor of Midwifery (BMid) in Australia has traditionally been based on academic ranking. The BMid is a high demand course offered to a limited number of students and therefore choosing applicants who complete the degree is important. Multiple Mini Interviews (MMIs) are used to assess non-cognitive skills and select students into healthcare degrees. One university in Australia has introduced MMIs as part of the application process for the BMid.

AIM

Compare attrition rates and Grade Point Average (GPA) scores between students admitted into the BMid using both academic ranking and MMIs, to those admitted on academic ranking alone.

METHODS

A basic convergent mixed methods design, using an explanatory unidirectional framework to integrate data. Attrition rates, GPA, and multiple mini interview scores (2013-2019), were linked and compared for before and after the use of MMI's. Focus groups with students, interviewers, and hospital-based educators, explored stakeholder experiences. Open-ended questions from an applicant survey were added to the qualitative data set, which was analysed thematically.

FINDINGS

Students who enrolled via the MMI's had significantly lower attrition rates than those enrolled before MMI's were introduced. GPA scores were significantly higher for students who enrolled via the MMI's. Integration of data found MMI's identified students passionate to undertake midwifery, and that success at the interviews increased students' confidence to successfully complete their studies.

CONCLUSION

MMI's as part of the entry process into the BMid enabled identification of applicants more likely to remain in the course and succeed in their studies.