206 research outputs found
Fostering student motivation and engagement with feedback through ipsative processes
Recent feedback literature emphasises the active role of learners in feedback processes and a programmatic approach to feedback design. This conceptual paper argues for the importance of ipsative processes, i.e. processes focusing on learners’ progress as a mechanism in meeting these two requirements. It suggests that the iterative nature of ipsative processes can encourage effective, learner-centred feedback and its implementation across multiple tasks can promote the uptake of feedback in subsequent work. Using self-determination theory, the paper discusses how ipsative feedback processes create conditions which can foster students’ perceptions of autonomy, competence and relatedness, thus fostering student motivation to engage with feedback. The implementation of ipsative processes is illustrated with references to two pedagogic practices. The paper identifies the need for further empirical research investigating academic and noncognitive benefits of ipsative processes in feedback for students as well as autoethnographic work examining the implications of implementing ipsative processes for teachers
Eliciting, processing and enacting feedback: mechanisms for embedding student feedback literacy within the curriculum
Recent feedback literature suggests that the development of student feedback literacy has potential to address problems in current feedback practice. Students’ feedback literacy involves developing the capacity to make the most of feedback opportunities by active involvement in feedback processes. How the development of student feedback literacy can be embedded within the undergraduate curriculum has not yet been discussed in any depth. This conceptual paper fills that gap by elaborating three key mechanisms for embedding feedback literacy within the curriculum: eliciting, processing and enacting. These are illustrated through enhanced variations of four existing practices: feedback requests, self-assessment, peer review, and curated e-portfolios. The discussion summarizes the key implications for practice and identifies the need for further empirical work investigating how students elicit, process and enact feedback in situ, and longitudinal research exploring the impact of curriculum design on the development of student feedback literacy
Navigating feedback practices across learning contexts: implications for feedback literacy
Student feedback practices have been primarily discussed within a context of the particular course or unit of study. Little attention has been paid to how students navigate their feedback practices as they progress through different learning contexts and whether they apply known feedback strategies in new settings. To open exploration of this issue, case studies of five participants were studied over different courses – undergraduate, direct-entry access program and postgraduate - in order to identify how learners’ understandings of past and immediate contexts impacted their approaches to feedback. Data were collected through student artefacts which included e-portfolios completed in the direct-entry program and two interviews, approximately one year apart. Thematic analysis of the data indicated influences of learners’ feedback histories on the application of feedback in new contexts. The findings highlight the need to consider students’ past feedback experiences, as well as identify connections between courses, in order to assist students in applying feedback practices across contexts. Further research exploring how micro transitions between courses and students’ lived experiences of interacting with feedback tools and materials influence their feedback literacy is recommended
Diffusion studies in magnetron sputter deposited silicon nitride films
In this work, silicon nitride coatings were deposited by magnetron sputtering onto float glass substrates and post-deposition annealed at 650°C for 5min. The structures and compositions of the coatings were investigated by X-ray diffraction, X-ray reflectometry, scanning electron microscopy and energy dispersive X-ray spectroscopy. Samples were then over-coated with silver and subjected to a second annealing process to initiate the diffusion of silver through the adjacent coating layers. Additional silicon nitride coatings were then deposited on selected samples to produce Si3N4/Ag/Si3N4/glass stacks, which were annealed at temperatures in the range 100-600°C. Ag and Na diffusion coefficients were then calculated from compositional profiles obtained from time of flight secondary ion mass spectrometry analysis. The coatings deposited in this study were found to have stoichiometric Si3N4 compositions and were amorphous after annealing. The diffusion rate of silver through these coatings was found to depend on annealing temperature and coating density and roughness, which in turn can be related to the deposition conditions. © 2013 Elsevier B.V
Transvenous Lead Extraction in Patients with Cardiac Implantable Device: The Impact of Systemic and Local Infection on Clinical Outcomes. An ESC‐EHRA ELECTRa (European Lead Extraction Controlled) Registry Substudy
Background: Infections of cardiac implantable devices (CIEDI) have poor outcomes despite improvement in lead extraction (TLE) procedures. Methods: To explore the influence of CIEDI on the outcomes of TLE and the differences between patients with systemic (Sy) vs. local (Lo) CIEDI, we performed a sub‐analysis of the EORP ELECTRa (European Lead Extraction ConTRolled) Registry. Results: Among 3555 patients enrolled by 73 centers in 19 Countries, the indication for TLE was CIEDI in 1850: 1170 with Lo‐CIEDI and 680 with Sy‐CIEDI. Patients with CIEDI had a worse in‐hospital prognosis in terms of major complications (3.57% vs. 1.71%; p = 0.0007) and mortality (2.27% vs. 0.49%; p < 0.0001). Sy‐CIEDI was an independent predictor of in‐hospital death (H.R. 2.14; 95%CI 1.06–4.33. p = 0.0345). Patients with Sy‐CIEDI more frequently had an initial CIED implant and a higher prevalence of comorbidities, while subjects with Lo‐CIEDI had a higher prevalence of previous CIED procedures. Time from signs of CIEDI and TLE was longer for Lo‐CIEDI despite a shorter pre‐TLE antibiotic treatment. Conclusions: Patients with CIEDI have a worse in‐hospital prognosis after TLE, especially for patients with Sy‐CIEDI. These results raise the suspicion that in a relevant group of patients CIEDI can be systemic from the beginning without progression from Lo‐CIEDI. Future research is needed to characterize this subgroup of patients
Quaternary structure of the specific p53-DNA complex reveals the mechanism of p53 mutant dominance
The p53 tumour suppressor is a transcriptional activator that controls cell fate in response to various stresses. p53 can initiate cell cycle arrest, senescence and/or apoptosis via transactivation of p53 target genes, thus preventing cancer onset. Mutations that impair p53 usually occur in the core domain and negate the p53 sequence-specific DNA binding. Moreover, these mutations exhibit a dominant negative effect on the remaining wild-type p53. Here, we report the cryo electron microscopy structure of the full-length p53 tetramer bound to a DNA-encoding transcription factor response element (RE) at a resolution of 21 Å. While two core domains from both dimers of the p53 tetramer interact with DNA within the complex, the other two core domains remain available for binding another DNA site. This finding helps to explain the dominant negative effect of p53 mutants based on the fact that p53 dimers are formed co-translationally before the whole tetramer assembles; therefore, a single mutant dimer would prevent the p53 tetramer from binding DNA. The structure indicates that the Achilles’ heel of p53 is in its dimer-of-dimers organization, thus the tetramer activity can be negated by mutation in only one allele followed by tumourigenesis
DNA probe modified with 3-iron bis(dicarbollide) for electrochemical determination of DNA sequence of Avian Influenza Virus H5N1
A quantitative LumiFluo assay to test inhibitory compounds blocking p53 degradation induced by human papillomavirus oncoprotein E6 in living cells
High-risk human papillomaviruses (HR-HPVs) are the causative agents for the onset of several epithelial cancers in humans. The deregulated expression of the viral oncoproteins E6 and E7 is the driving force sustaining the progression of malignant transformation in pre-neoplastic lesions. Targeting the viral E6 oncoprotein through inhibitory compounds can counteract the survival of cancer cells due to the reactivation of p53-mediated pathways and represents an intriguing strategy to treat HPV-associated neoplasias. Here, we describe the development of a quantitative and easy-to-perform assay to monitor the E6-mediated degradation of p53 in living cells to be used for small-molecule testing. This assay allows to unbiasedly determine whether a compound can protect p53 from the E6-mediated degradation in cells, through a simple 3-step protocol. We validated the assay by testing two small molecules, SAHA and RITA, reported to impair the E6-mediated p53 degradation. Interestingly, we observed that only SAHA efficiently rescued p53, while RITA could not provide the same degree of protection. The possibility to specifically and quantitatively monitor the ability of a selected compound to rescue p53 in a cellular context through our LumiFluo assay could represent an important step towards the successful development of anti-HPV drugs
Lysine120 Interactions with p53 Response Elements can Allosterically Direct p53 Organization
p53 can serve as a paradigm in studies aiming to figure out how allosteric perturbations in transcription factors (TFs) triggered by small changes in DNA response element (RE) sequences, can spell selectivity in co-factor recruitment. p53-REs are 20-base pair (bp) DNA segments specifying diverse functions. They may be located near the transcription start sites or thousands of bps away in the genome. Their number has been estimated to be in the thousands, and they all share a common motif. A key question is then how does the p53 protein recognize a particular p53-RE sequence among all the similar ones? Here, representative p53-REs regulating diverse functions including cell cycle arrest, DNA repair, and apoptosis were simulated in explicit solvent. Among the major interactions between p53 and its REs involving Lys120, Arg280 and Arg248, the bps interacting with Lys120 vary while the interacting partners of other residues are less so. We observe that each p53-RE quarter site sequence has a unique pattern of interactions with p53 Lys120. The allosteric, DNA sequence-induced conformational and dynamic changes of the altered Lys120 interactions are amplified by the perturbation of other p53-DNA interactions. The combined subtle RE sequence-specific allosteric effects propagate in the p53 and in the DNA. The resulting amplified allosteric effects far away are reflected in changes in the overall p53 organization and in the p53 surface topology and residue fluctuations which play key roles in selective co-factor recruitment. As such, these observations suggest how similar p53-RE sequences can spell the preferred co-factor binding, which is the key to the selective gene transactivation and consequently different functional effects
Persistent Megalocystic Ovary Following in Vitro Fertilization in a Postpartum Patient with Polycystic Ovarian Syndrome
SummaryObjectiveOvarian hyperstimulation syndrome (OHSS) is more severe when pregnancy occurs, as the developing pregnancy produces human chorionic gonadotropin, which stimulates the ovary's persistent growth. If no pregnancy occurs, the syndrome will typically resolve within 1 week. In a maintained pregnancy, slow resolution of symptoms usually occurs over 1-2 months.Case ReportA 31-year-old woman, gravida 2, para 1, aborta 1, with polycystic ovary syndrome underwent in vitro fertilization (IVF) with clomiphene citrate and follicle-stimulating hormone/gonadotropin releasing hormone-antagonist stimulation. During transvaginal oocyte retrieval, enlarged bilateral ovaries were noted. She had an episode of OHSS after IVF/embryo transfer, for which paracentesis was performed three times. Pregnancy was achieved. Throughout antenatal examinations, bilateral ovaries were enlarged. She delivered a healthy baby by cesarean section at term. However, 1 month after delivery, the bilateral ovary had not shrunk, and levels of tumor markers CA125 and CA199 were 50.84 and 41.34 U/mL, respectively. At laparotomy for suspected malignancy, both adnexae formed “kissing ovaries”, which were multinodulated with yellow serous fluid. Specimens from wedge resection submitted for frozen section showed a benign ovarian cyst. The final pathology report showed bilateral follicle cysts.ConclusionWith the increasing use of gonadotropins in the management of infertility, ovarian enlargement secondary to hyperstimulation is common. Generally, symptoms appear between the 6th and 13th weeks of pregnancy and disappear thereafter. The hyperstimulated ovary often subsides after the first trimester. This case is unusual as the megalocystic ovary persisted after delivery. To the best of our knowledge, we report the first case of enlarged bilateral ovaries persisting 2 months after delivery
- …