409,469 research outputs found

    How effective is our feedback? : feeding forward and self-regulation

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    Giving and receiving feedback is based on a number of stages, procedures, and factors that could determine whether the feedback is effective or not. The key stakeholders of feedback are the tutor and the student, who could work together towards building bridges, such as holding dialogues, giving and receiving constructive criticism. Ideally, feedback is not a one-way, top-down approach, where the tutor ‘commands’ the discourse, whilst the student is merely a passive recipient. In whatever form it is delivered, the feedback that is passed on to the student should be more than ‘correcting’ the work; it could involve a communicative approach whereby the tutor passes on salient information that the student may utilise to sharpen his or her work. Hence, the possession of feedback is not solely relegated to the tutor. Instead, there is a transference where the student claims ownership of the feedback, and thus becomes responsible for its implementation. The responsibility to do so should not be perceived by the student as though he or she were doing a favour to their tutor, but an action which is undertaken for their own personal benefit and gain. Rather than feeding ‘back’, it is transformed to feeding ‘forward’, as the tutor provides suggestions that help shape future writing or assigned work. This paper, which is the result of a doctoral study conducted by the author, aims to present some benefits and challenges of feedback. Whilst exploring various areas of feedback, it suggests that, by revisiting practices, perceptions, and conceptualisations, there can be a shift towards feed forward and eventually offer the possibility of harnessing students’ autonomy and self-regulation.peer-reviewe

    Simulations of momentum feedback by black hole winds

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    The observed super-massive black hole (SMBH) mass -- galaxy velocity dispersion (Mbh−σM_{\rm bh} - \sigma) correlation may be established when winds/outflows from the SMBH drive gas out of the potential wells of classical bulges. Here we present numerical simulations of this process in a static isothermal potential. Simple spherically symmetric models of SMBH feedback at the Eddington luminosity can successfully explain the Mbh−σM_{\rm bh} - \sigma and nuclear cluster mass MNC−σM_{\rm NC}-\sigma correlations, as well as why larger bulges host SMBHs while smaller ones host nuclear star clusters. However these models do not specify how SMBHs feed on infalling gas whilst simultaneously producing feedback that drives gas out of the galaxy. More complex models with rotation and/or anisotropic feedback allow SMBHs to feed via a disc or regions not exposed to SMBH winds, but in these more realistic cases it is not clear why a robust Mbh−σM_{\rm bh} - \sigma relation should be established. In fact, some of the model predictions contradict observations. For example, an isotropic SMBH wind impacting on a disc (rather than a shell) of aspect ratio H/R≪1H/R \ll 1 requires the SMBH mass to be larger by a factor ∼R/H\sim R/H, which is opposite to what is observed. We conclude that understanding how a SMBH feeds is as important a piece of the puzzle as understanding how its feedback affects its host galaxy. Finally, we note that in aspherical cases the SMBH outflows induce differential motions in the bulge. This may pump turbulence that is known to hinder star formation in star forming regions. SMBH feedback thus may not only drive gas out of the bulge but also reduce the fraction of gas turned into stars.Comment: 17 pages, to appear in MNRA

    Intracellular Regulatory Networks are close to Monotone Systems

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    Several meso-scale biological intracellular regulatory networks that have specified directionality of interactions have been recently assembled from experimental literature. Directed networks where links are characterized as positive or negative can be converted to systems of differential equations and analyzed as dynamical systems. Such analyses have shown that networks containing only sign-consistent loops, such as positive feed-forward and feedback loops function as monotone systems that display well-ordered behavior. Perturbations to monotone systems have unambiguous global effects and a predictability characteristic that confers advantages for robustness and adaptability. We find that three intracellular regulatory networks: bacterial and yeast transcriptional networks and a mammalian signaling network contain far more sign-consistent feedback and feed-forward loops than expected for shuffled networks. Inconsistent loops with negative links can be more easily removed from real regulatory networks as compared to shuffled networks. This topological feature in real networks emerges from the presence of hubs that are enriched for either negative or positive links, and is not due to a preference for double negative links in paths. These observations indicate that intracellular regulatory networks may be close to monotone systems and that this network topology contributes to the dynamic stability

    Can 'quality marking' be used to provide effective feedback within higher education?

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    Providing written feedback to learners within Higher Education can be a time-consuming and frequently ineffective process, with comments often undervalued or not acted upon. The same concerns exist within the primary sector; marking systems do not always effectively support the principles of Assessment for Learning. This frustration resulted in the development of the 'Quality Marking' model for primary schools (Clarke 1998) which follows an explicit process within which the type of comments, or prompts, used are key. This small scale study has investigated whether 'quality marking' – and in particular the use of scaffold prompts – can be applied to the Higher Education context. A group of final year student teachers within initial teacher training received and acted upon the feedback, as well as completing a series of questionnaires to record their perceptions of the process and its formative value. It is clear from the data gathered that 'quality marking' was viewed as an effective approach. Key identified reasons for this were the likelihood of the feedback to feed forward into future learning, the level of engagement from the learner, the clarity of how to bridge the learning gap, and the beginnings of self-monitoring

    Cold Feedback in Cooling-Flow Galaxy Clusters

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    We put forward an alternative view to the Bondi-driven feedback between heating and cooling of the intra-cluster medium (ICM) in cooling flow galaxies and clusters. We adopt the popular view that the heating is due to an active galactic nucleus (AGN), i.e. a central black hole accreting mass and launching jets and/or winds. We propose that the feedback occurs with the entire cool inner region (5-30 kpc). A moderate cooling flow does exist here, and non-linear over-dense blobs of gas cool fast and are removed from the ICM before experiencing the next major AGN heating event. Some of these blobs may not accrete on the central black hole, but may form stars and cold molecular clouds. We discuss the conditions under which the dense blobs may cool to low temperatures and feed the black hole.Comment: 6 pages, no figures, to appear in the Proceedings of "Heating vs. Cooling in Galaxies and Clusters of Galaxies", August 2006, Garching (Germany

    Timing feedback-inhibition of the male reproductive hormone axis

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    Hormonal methods of male contraception have addressed feedback-inhbition of the cascade of hormones that has evolved to regulate sperm production but high concentrations of testosterone (T) in the blood have not worked satisfactorily. We hypothesized that an episodic event, such as degranulation of gonadotropin-releasing hormone (GnRH) neurons in the hypothalamus, could be as well inhibited by episodic interference as by continuously-applied suppression. We used a computational model of hypothalamus-pituitary-gonad axis described by Veldhuis et al. to test the hypothesis that episodic administration of T would inhibit GnRH and/or luteinizing hormone (LH) secretion. A set of stochastic differential equations model feedback as well as feed-forward actions of GnRH, LH and T. The model predicted feedback-inhibition of GnRH pulses in a dose and frequency dependent manner when transdermal patches or injections delivering pulsatile T were applied. Since the published model did not address the effect of chronic GnRH deprivation on the viability of pituitary gonadotrophes, we introduced a function to address this issue. Incorporation of this function in the model allowed the prediction of a “holiday period” in the contraceptive regimen, during which exogenous T would not be needed to protect from conception. Pulsatile T delivered by real-life transdermal delivery system applied as per a parsimonious regimen reduced secretion of LH and T and fertility. The vitality function, proposed to account for survival and proliferation of pituitary gonadotrophes correlated with in vivo observations as extensive apoptosis in the anterior pituitary was observed after application of transdermal T
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