Student-t processes as alternatives to Gaussian processes

We investigate the Student-t process as an alternative to the Gaussian process as a non-parametric prior over functions. We derive closed form expressions for the marginal likelihood and predictive distribution of a Student-t process, by integrating away an inverse Wishart process prior over the co-variance kernel of a Gaussian process model. We show surprising equivalences between different hierarchical Gaussian process models leading to Student-t processes, and derive a new sampling scheme for the inverse Wishart process, which helps elucidate these equivalences. Overall, we show that a Student-t process can retain the attractive properties of a Gaussian process - a nonparamet-ric representation, analytic marginal and predictive distributions, and easy model selection through covariance kernels - but has enhanced flexibility, and predictive covariances that, unlike a Gaussian process, explicitly depend on the values of training observations. We verify empirically that a Student-t process is especially useful in situations where there are changes in covariance structure, or in applications such as Bayesian optimization, where accurate predictive covariances are critical for good performance. These advantages come at no additional computational cost over Gaussian processes.

Impact of Early Postnatal Androgen Exposure on Voice Development

Background: the impact of early postnatal androgen exposure on female laryngeal tissue may depend on certain characteristics of this exposure. We assessed the impact of the dose, duration, and timing of early androgen exposure on the vocal development of female subjects who had been treated for adrenocortical tumor (ACT) in childhood.Methods: the long-term effects of androgen exposure on the fundamental vocal frequency (F0), vocal pitch, and final height and the presence of virilizing signs were examined in 9 adult (age, 18.4 to 33.5 years) and 10 adolescent (13.6 to 17.8 years) female ACT patients. We also compared the current values with values obtained 0.9 years to 7.4 years after these subjects had undergone ACT surgery, a period during which they had shown normal androgen levels.Results: of the 19 subjects, 17 (89%) had been diagnosed with ACT before 4 years of age, 1 (5%) at 8.16 years, and 1 (5%) at 10.75 years. Androgen exposure (2 to 30 months) was sufficiently strong to cause pubic hair growth in all subjects and clitoromegaly in 74% (14/19) of the subjects, but did not reduce their height from the target value. Although androgen exposure induced a remarkable reduction in F0 (132 Hz) and moderate pitch virilization in 1 subject and partial F0 virilization, resulting in F0 of 165 and 169 Hz, in 2 subjects, the majority had normal F0 ranging from 189 to 245 Hz.Conclusions: Female laryngeal tissue is less sensitive to androgen exposure between birth and adrenarche than during other periods. Differential larynx sensitivity to androgen exposure in childhood and F0 irreversibility in adulthood are age-, concentration-, duration-, and timing-dependent events that may also be affected by exposure to inhibitory or stimulatory hormones. Further studies are required to better characterize each of these factors.

Voice Performance Evaluation of Street Children From Aracaju, Brazil Using Perceptual-Auditory and Acoustic Analyses

Objective. To compare the voice performance of children involved in street labor with regular children using perceptual-auditory and acoustic analyses.Methods. A controlled cross-sectional study was carried out on 7- to 10-year-old children of both genders. Children from both groups lived with their families and attended school regularly; however, child labor was evident in one group and not the other. A total of 200 potentially eligible street children, assisted by the Child Labor Elimination Programme (PETI), and 400 regular children were interviewed. Those with any vocal discomfort (106, 53% and 90, 22.5%) had their voices assessed for resonance, pitch, loudness, speech rate, maximum phonation time, and other acoustic measurements.Results. A total of 106 street children (study group [SG]) and 90 regular children (control group [CG]) were evaluated. the SG group demonstrated higher oral and nasal resonance, reduced loudness, a lower pitch, and a slower speech rate than the CG. the maximum phonation time, fundamental frequency, and upper harmonics were higher in the SG than the CG. Jitter and shimmer were higher in the CG than the SG.Conclusion. Using perceptual-auditory and acoustic analyses, we determined that there were differences in voice performance between the two groups, with street children having better quality perceptual and acoustic vocal parameters than regular children. We believe that this is due to the procedures and activities performed by the Child Labor Elimination Program (PETI), which helps children to cope with their living conditions.

Reflective writing: The student nurse's perspective on reflective writing and poetry writing.

Summary Background Reflective writing is a mandatory part of nurse education but how students develop their skills and use reflection as part of their experiential learning remains relatively unknown. Understanding reflective writing in all forms from the perspective of a student nurse is therefore important. Objectives To explore the use of reflective writing and the use of poetry in pre-registered nursing students. Design A qualitative design was employed to explore reflective writing in pre-registered nursing students. Setting A small university in Scotland. Participants BSc (Hons) Adult and Mental Health Pre-registration Student Nurses. Methods Two focus groups were conducted with 10 student nurses during March 2012. Data was analysed thematically using the framework of McCarthy (1999). Results Students found the process of reflective writing daunting but valued it over time. Current educational methods, such as assessing reflective accounts, often lead to the ‘narrative’ being watered down and the student feeling judged. Despite this, reflection made students feel responsible for their own learning and research on the topic. Some students felt the use of models of reflection constricting, whilst poetry freed up their expression allowing them to demonstrate the compassion for their patient under their care. Conclusions Poetry writing gives students the opportunity for freedom of expression, personal satisfaction and a closer connection with their patients, which the more formal approach to reflective writing did not offer. There is a need for students to have a safe and supportive forum in which to express and have their experiences acknowledged without the fear of being judged.

Marking and providing feedback face-to-face: staff and student perspectives.

The setting, marking and providing feedback on assessments forms an important part of a tutor’s role. Studies into the use of feedback and how it is interpreted by students indicate a mismatch between what students are looking for and what tutors think they are giving. Tutors comment that students are more interested in the mark than the feedback, and yet students indicate that they do not get enough feedback, or that it is not useful. This study investigates student and staff perceptions of the linking of marking and feedback in face-to-face sessions. A cohort of year one university students were given the option of receiving either written feedback or a 15 minute meeting with one of their tutors to have their essay marked with them. Forty nine students chose face-to-face marking, the remaining 35 students received written feedback. Focus groups were used to investigate the student experience. Staff members were also asked to reflect on the process. Students and staff found the experience of face-to-face marking beneficial and positive. Both felt that the time spent together allowed for a feedback dialogue about the piece of work, and that staff could explain and justify why marks were given.

Student use of electronic information services in further education

Urquhart,C., Thomas, R., Spink, S., Fenton, R., Yeoman, A., Lonsdale, R., Armstrong, C., Banwell, L., Ray, K., Coulson, G. & Rowley, J. (2005). Student use of electronic information services in further education. International Journal of Information Management, 25(4), 347-362. Sponsorship: JISC

Comparing Student Software Designs Using Semantic Categorization

Eckerdal, A. McCartney, R. Mostr?m, J.E. Ratcliffe, M. Zander, C. Comparing Student Software Designs Using Semantic Categorization. Proceedings of the Fifth Finnish/Baltic Sea Conference on Computer Science Education, 2005

Understanding student information behavior in relation to electronic information services: lessons from longitudinal monitoring and evaluation Part 1

Rowley, J.& Urquhart, C. (2007). Understanding student information behavior in relation to electronic information services: lessons from longitudinal monitoring and evaluation Part 1. Journal of the American Society for Information Science and Technology, 58(8), 1162-1174. Sponsorship: JISC

Understanding student information behavior in relation to electronic information services: lessons from longitudinal monitoring and evaluation Part 2

Urquhart, C. & Rowley, J. (2007). Understanding student information behavior in relation to electronic information services: lessons from longitudinal monitoring and evaluation Part 2. Journal of the American Society for Information Science and Technology, 58(8), 1188-1197. Sponsorship: JISC

Data-driven fuzzy rule generation and its application for student academic performance evaluation

K. Rasmani and Q. Shen. Data-driven fuzzy rule generation and its application for student academic performance evaluation. Applied Intelligence, 25(3):305-319, 2006.

Subsethood-based Fuzzy Rule Models and their Application to Student Performance

K. Rasmani and Q. Shen. Subsethood-based Fuzzy Rule Models and their Application to Student Performance Classification. Proceedings of the 14th International Conference on Fuzzy Systems, pages 755-760, 2005.

Through the eyes of instructors: a phenomenographic investigation of student success

Kinnunen, P., McCartney, R., Murphy, L., and Thomas, L. 2007. Through the eyes of instructors: a phenomenographic investigation of student success. In Proceedings of the Third international Workshop on Computing Education Research (Atlanta, Georgia, USA, September 15 - 16, 2007). ICER '07. ACM, New York, NY, 61-72.

Vibrato in singing voice: the link between source-filter and sinusoidal models

The application of inverse filtering techniques for high-quality singing voice analysis/synthesis is discussed. In the context of source-filter models, inverse filtering provides a noninvasive method to extract the voice source, and thus to study voice quality. Although this approach is widely used in speech synthesis, this is not the case in singing voice. Several studies have proved that inverse filtering techniques fail in the case of singing voice, the reasons being unclear. In order to shed light on this problem, we will consider here an additional feature of singing voice, not present in speech: the vibrato. Vibrato has been traditionally studied by sinusoidal modeling. As an alternative, we will introduce here a novel noninteractive source filter model that incorporates the mechanisms of vibrato generation. This model will also allow the comparison of the results produced by inverse filtering techniques and by sinusoidal modeling, as they apply to singing voice and not to speech. In this way, the limitations of these conventional techniques, described in previous literature, will be explained. Both synthetic signals and singer recordings are used to validate and compare the techniques presented in the paper.