A model of hyphal tip growth involving microtubule-based transport

We propose a simple model for mass transport within a fungal hypha and its subsequent growth. Inspired by the role of microtubule-transported vesicles, we embody the internal dynamics of mass inside a hypha with mutually excluding particles progressing stochastically along a growing one-dimensional lattice. The connection between long range transport of materials for growth, and the resulting extension of the hyphal tip has not previously been addressed in the modelling literature. We derive and analyse mean-field equations for the model and present a phase diagram of its steady state behaviour, which we compare to simulations. We discuss our results in the context of the filamentous fungus, Neurospora crassa.Comment: 5 pages, 5 figure

Auto-driven Photo Elicitation Interviews in Research with Children: Ethical and Practical Considerations

Children can sometimes find it difficult to articulate their experiences if they have to rely solely on words. Giving children the opportunity to use arts-based research approaches can support their participation in research and create a bridge that enables them to express their perspectives and feelings. This paper focuses on the ethical and practical considerations when using photo elicitation interviews (PEI) in research with children. The discussion and examples provided are drawn from an international study that used auto-driven PEI, where photographs are taken by children themselves, to explore children’s experiences of living with a chronic condition and the impact condition management may have on their everyday lives. In this paper we critically explore the issues arising from our use of PEI including children’s participation and engagement, balancing power and control, and keeping children safe. The main areas of focus for the paper are how PEI provided a means of shifting control; how setting photographic boundaries influenced our PEI study with children; and how we addressed risks associated with the method. Our experience shows that PEI is an engaging and valuable research method, providing a powerful medium for obtaining rich data with children. However, PEI is challenging and it requires researchers to conscientiously address ethical and practical aspects that extend beyond those inherent to standard (words-alone) interviews

Before and after riparian management: Sediment and nutrient exports from a small agricultural catchment, Western Australia

Riparian vegetation can trap sediment and nutrients coming from hillslopes and reduce stream bank erosion. This study presents results from a 10 year stream monitoring program in a small agricultural catchment near Albany, Western Australia. In 1996, a 1.6 km stream reach was fenced, planted with eucalyptus species and managed separately from the adjacent paddocks. Stream flow, nutrient and sediment concentration data were collected at the downstream end of the fenced riparian area between 1991 and 2000, so there are data for the “before” and “after” riparian management periods. Suspended sediment concentrations fell dramatically following riparian management; the average event mean concentration (EMC) dropped from 254 mg/l to 15.8 mg/l. Maximum suspended sediment concentrations dropped by an order of magnitude. As a result, sediment exports from the catchment reduced noticeably following riparian management, mainly due to reduced stream bank erosion. In contrast, riparian management had limited impact on nutrient exports. There was no detectable change in total phosphorus EMC, a 67% increase in filterable reactive phosphorus average EMC and a 37% decrease in average total nitrogen EMC between the before and after periods. This study demonstrates the benefits of riparian management in reducing stream bank erosion, and suggests that in this environment, with sandy soils with low phosphorus retention, there are limitations on the effectiveness of riparian management for reducing nutrient exports

Teacher and Student-focused Approaches: influence of learning approach and self-efficacy in a psychology postgraduate sample

The current study examined approaches to teaching in a postgraduate psychology sample. This included considering teaching-focused (information transfer) and student-focused (conceptual changes in understanding) approaches to teaching. Postgraduate teachers of psychology ( N = 113) completed a questionnaire measuring their use of a teacher- or student-focused approach, deep and surface approaches to learning and teaching, and research self-efficacy. Standard multiple regressions revealed that the manner in which postgraduate students approached their own studies (i.e., deep or surface learning approach) predicted the use of a teacher- or student-focused approach in their teaching practice. Specifically, postgraduates adopting a deep approach to their own learning were more likely to adopt a teaching-focused approach to their teaching practice. Those adopting a surface approach to their own studies were most likely to adopt a student-focused approach. Furthermore, postgraduates with a high level of teaching self-efficacy were more likely to adopt a student-focused approach to teaching practice. Additionally, postgraduates who had received formal teaching training scored higher on teacher self-efficacy than those who had not received such training. Taken together, the findings suggest the key role of formal training in enhancing self-efficacy in teaching, and demonstrate an association between the learning styles adopted by postgraduate teachers and their approach to teaching. </jats:p

Low-mass members of the young cluster IC 4665 and pre-main-sequence lithium depletion

We have used fibre spectroscopy to establish cluster membership and examine pre-main-sequence (PMS) lithium depletion for low-mass stars (spectral types F to M) in the sparse young (~30 Myr) cluster IC 4665. We present a filtered candidate list of 40 stars that should contain 75 per cent of single cluster members with V of 11.5 to 18 in the central square degree of the cluster. Whilst F- and G-type stars in IC 4665 have depleted little or no lithium, the K- and early M-type stars have depleted more Li than expected when compared with similar stars in other clusters of known age. An empirical age estimate based on Li-depletion among the late-type stars of IC 4665 would suggest it is older than 100 Myr. This disagrees entirely with ages determined either from the nuclear turn-off, from isochronal matches to low-mass stars or from the re-appearance of lithium previously found in much lower mass stars (the ``lithium depletion boundary''). We suggest that other parameters besides age, perhaps composition or rotation, are very influential in determining the degree of PMS Li-depletion in stars with M greater than 0.5 Msun. Further work is required to identify and assess the effects of these additional parameters, particularly to probe conditions at the interface between the sub-photospheric convection zone and developing radiative core. Until then, PMS Li depletion in F- to early M-type stars cannot be confidently used as a precise age indicator in young clusters, kinematic groups or individual field stars.Comment: Accepted for publication in MNRA

Generalized Arago-Fresnel laws: The EME-flow-line description

We study experimentally and theoretically the influence of light polarization on the interference patterns behind a diffracting grating. Different states of polarization and configurations are been considered. The experiments are analyzed in terms of electromagnetic energy (EME) flow lines, which can be eventually identified with the paths followed by photons. This gives rise to a novel trajectory interpretation of the Arago-Fresnel laws for polarized light, which we compare with interpretations based on the concept of "which-way" (or "which-slit") information.Comment: 14 pages, 6 figure

Academic achievement : the role of praise in motivating students

The motivation of students is an important issue in higher education, particularly in the context of the increasing diversity of student populations. A social-cognitive perspective assumes motivation to be dynamic, context-sensitive and changeable, thereby rendering it to be a much more differentiated construct than previously understood. This complexity may be perplexing to tutors who are keen to develop applications to improve academic achievement. One application that is within the control of the tutor, at least to some extent, is the use of praise. Using psychological literature the article argues that in motivating students, the tutor is not well served by relying on simplistic and common sense understandings of the construct of praise and that effective applications of praise are mediated by students' goal orientations, which of themselves may be either additive or interactive composites of different objectives and different contexts

Architecture of a Silicon Strip Beam Position Monitor

A collaboration between Fermilab and the Institute for High Energy Physics (IHEP), Beijing, has developed a beam position monitor for the IHEP test beam facility. This telescope is based on 5 stations of silicon strip detectors having a pitch of 60 microns. The total active area of each layer of the detector is about 12x10 cm2. Readout of the strips is provided through the use of VA1` ASICs mounted on custom hybrid printed circuit boards and interfaced to Adapter Cards via copper-over-kapton flexible circuits. The Adapter Cards amplify and level-shift the signal for input to the Fermilab CAPTAN data acquisition nodes for data readout and channel configuration. These nodes deliver readout and temperature data from triggered events to an analysis computer over gigabit Ethernet links.Comment: Submitted to TWEPP 201