Measurement of cavitation in a sliding bearing using digital holography

This paper was presented at the 4th Micro and Nano Flows Conference (MNF2014), which was held at University College, London, UK. The conference was organised by Brunel University and supported by the Italian Union of Thermofluiddynamics, IPEM, the Process Intensification Network, the Institution of Mechanical Engineers, the Heat Transfer Society, HEXAG - the Heat Exchange Action Group, and the Energy Institute, ASME Press, LCN London Centre for Nanotechnology, UCL University College London, UCL Engineering, the International NanoScience Community, www.nanopaprika.eu.Although most of the mathematical models for cavitation in bearings provide reasonable estimates of engineering parameters such as load capacity and friction, they are based on substantially different assumptions and further work is required to understand the fundamental operation of bearings. In this study digital holography was used to examine bubble formation within a glass sliding bearing. Digital holography collects the both the phase and amplitude of the transmitted wavefront and therefore contains quantitative information concerning the thickness of the cavitation bubbles. This paper introduces the experimental configuration and the digital holography system used to study cavitation. It also discusses the demodulation process and how the information can be used to find other interesting parameters such as bubble position and shape

Learning from difference and similarity: identities and relational reflexive learning

Within organizations there is reciprocal interplay between identity construction and learning. Processes of learning are enabled and constrained by identity practices; concomitantly, the possibilities for learning are shaped by the identity positions available to individuals. There is a dynamic between the impositions of organizations and people’s freedom to shape their identities and learning plays a crucial role in this. Our purpose in this special issue is to contribute to the understanding of the intersection of identity work and learning as a response to experiences of being different. Experiences of difference include moving into a new role, encountering a disjuncture with others while in a role or a difference in broader life which is reacted to as if it were a problem in an organizational setting. Being different produces a variety of challenges and the papers in this special issue trace how people cope with vulnerabilities, develop resilience and often collaborate in their learning. We focus on how people reflect on their own identity and learn and how, by learning together with people who have similar experiences, micro-communities can support, develop and enhance their insight and identity-positions

Are science students ready for university mathematics?

At UTS students in science courses often struggle with the first year first semester mathematics subject. This year we requested all commencing science students to take a Readiness Survey so that we could advise them of suitable pathways for the maths subjects in their degree. One such pathway includes taking a one-semester subject of introductory calculus before the regular mathematics subject. This paper reports on the practicalities of running such a test before semester starts, and the pathways taken up with varying levels of success by Science students. Insights from a parallel survey and pathway used for some years now with Engineering students in the same institution are offered

The Mathematics Problem and Mastery Learning for First-Year, Undergraduate STEM Students

In the 2014 academic year Mastery Learning was implemented in four first-year mathematics subjects in an effort to address a lack of preparedness and poor outcomes of increasing numbers of undergraduate students in science, engineering and mathematics programs. This followed partial success in the use of diagnostic testing and pre-teaching, active learning, and a greater emphasis on problem solving in context - under-prepared students were still more likely to fail the pre-teaching subject and to struggle with subsequent mathematics subjects. Also, failure rates overall were higher than benchmarks required. This paper describes the learning design used, and the outcomes achieved, with implementing Mastery Learning – the positive: improved academic success, time management, and attitudes towards learning and Mathematics, an increased sense of independence, confidence and retention of content, and reduced stress and anxiety; and the negative: students having a sense of being taught how to pass a test rather than having a deeper understanding of the content. It will be seen that this negative is a consequence of a small but important difference in implementation

Arabidopsis DOF Transcription Factors Act Redundantly to Reduce CONSTANS Expression and Are Essential for a Photoperiodic Flowering Response

SummaryFlowering of Arabidopsis is induced by long summer days (LDs). The transcriptional regulator CONSTANS (CO) promotes flowering, and its transcription is increased under LDs. We systematically misexpressed transcription factors in companion cells and identified several DOF proteins that delay flowering by repressing CO transcription. Combining mutations in four of these, including CYCLING DOF FACTOR 2 (CDF2), caused photoperiod-insensitive early flowering by increasing CO mRNA levels. CO transcription is promoted to differing extents by GIGANTEA (GI) and the F-box protein FKF1. We show that GI stabilizes FKF1, thereby reducing CDF2 abundance and allowing transcription of CO. Despite the crucial function of GI in wild-type plants, introducing mutations in the four DOF-encoding genes into gi mutants restored the diurnal rhythm and light inducibility of CO. Thus, antagonism between GI and DOF transcription factors contributes to photoperiodic flowering by modulating an underlying diurnal rhythm in CO transcript levels

miR824-Regulated AGAMOUS-LIKE16 Contributes to Flowering Time Repression in Arabidopsis

The timing of flowering is pivotal for maximizing reproductive success under fluctuating environmental conditions. Flowering time is tightly controlled by complex genetic networks that integrate endogenous and exogenous cues, such as light, temperature, photoperiod, and hormones. Here, we show that AGAMOUS-LIKE16 (AGL16) and its negative regulator microRNA824 (miR824) control flowering time in Arabidopsis thaliana. Knockout of AGL16 effectively accelerates flowering in nonvernalized Col-FRI, in which the floral inhibitor FLOWERING LOCUS C (FLC) is strongly expressed, but shows no effect if plants are vernalized or grown in short days. Alteration of AGL16 expression levels by manipulating miR824 abundance influences the timing of flowering quantitatively, depending on the expression level and number of functional FLC alleles. The effect of AGL16 is fully dependent on the presence of FLOWERING LOCUS T (FT). Further experiments show that AGL16 can interact directly with SHORT VEGETATIVE PHASE and indirectly with FLC, two proteins that form a complex to repress expression of FT. Our data reveal that miR824 and AGL16 modulate the extent of flowering time repression in a long-day photoperiod