36 resultados para Feedforward and feedback controls
em Aston University Research Archive
Resumo:
The laminar distribution of senile plaques (SP) and neurofibrillary tangles (NFT) was studied in areas B17 and B18 of the visual cortex in 18 cases of Alzheimer’s disease which varied in disease onset and duration. The objective was to test the hypothesis that SP and NFT could spread via either the feedforward or feedback short cortico-cortical projections. In area B17, the mean density of SP and NFT reached a maximum in lamina III and in laminae II and III respectively. In B18, mean SP density was maximal in laminae III and IV and NFT density in laminae II and III. No significant correlations were observed in any cortical lamina between the density of SP and patient age. However, the density of NFT in laminae III, IV and VI in B18 was negatively correlated with patient age. In addition, in B18, the density of SP in lamina II and lamina V was negatively correlated with disease duration and disease onset respectively. Although these results suggest that SP and NFT might spread between B17 and B18 via the feedforward short cortico-cortical projections, it is also possible that the longer cortico-cortical and cortico-subcortical connections may be involved.
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Recent surveys reveal that many university students in the U.K. are not satisfied with the timeliness and usefulness of the feedback given by their tutors. Ensuring timeliness in marking can result in a reduction in the quality of feedback. Though suitable use of Information and Communication Technology should alleviate this problem, existing Virtual Learning Environments are inadequate to support detailed marking scheme creation and they provide little support for giving detailed feedback. This paper describes a unique new web-based tool called e-CAF for facilitating coursework assessment and feedback management directed by marking schemes. Using e-CAF, tutors can create or reuse detailed marking schemes efficiently without sacrificing the accuracy or thoroughness in marking. The flexibility in marking scheme design also makes it possible for tutors to modify a marking scheme during the marking process without having to reassess the students’ submissions. The resulting marking process will become more transparent to students.
Resumo:
The tendency of managers to focus on short-term results rather than on sustained company success is of particular importance to retail marketing managers, because marketing activities involve expenditures which may only pay off in the longer term. To address the issue of myopic management, our study shows how the complexity of the service profit chain (SPC) can cause managers to make suboptimal decisions. Hence, our paper departs from past research by recognizing that understanding the temporal interplay between operational investments, employee satisfaction, customer satisfaction, and operating profit is essential to achieving sustained success. In particular, we intend to improve understanding of the functioning of the SPC with respect to time lags and feedback loops. Results of our large-scale longitudinal study set in a multi-outlet retail chain reveal time-lag effects between operational investments and employee satisfaction, as well as between customer satisfaction and performance. These findings, along with evidence of a negative interaction effect of employee satisfaction on the relationship between current performance and future investments, show the substantial risk of mismanaging the SPC. We identify specific situations in which the dynamic approach leads to superior marketing investment decisions, when compared to the conventional static view of the SCP. These insights provide valuable managerial guidance for effectively managing the SPC over time. © 2012 New York University.
Resumo:
Background. Food allergy is related to poorer quality of life (QoL) and mental health of caregivers. Many parents diagnose food allergy in their child without seeking medical care and there is limited research on this group. This study investigated parental QoL and mental health in parents of children with parent-diagnosed food allergy (PA), medically diagnosed food allergy (MA), and a control group with no allergy (NA). Methods. One hundred and fifty parents from a general population completed validated measures of QoL, anxiety, depression, and stress. Results. Parents of children with food allergy (PA or MA) reported higher stress, anxiety, and depression than the control group (all ). Parents of children with MA reported poorer food allergy related QoL compared to parents of children with PA (); parents of children with PA reported poorer general QoL compared to parents of children with MA (). Conclusion. Parents of children with food allergy have significantly poorer mental health compared to healthy controls, irrespective of whether food allergy is medically diagnosed or not. It is important to encourage parents to have their child medically tested for food allergy and to recognise and refer for psychological support where needed.
Resumo:
Recent National Student Surveys revealed that many U.K. university students are dissatisfied with the timeliness and usefulness of the feedback received from their tutors. Ensuring timeliness in marking often results in a reduction in the quality of feedback. In Computer Science where learning relies on practising and learning from mistakes, feedback that pin-points errors and explains means of improvement is important to achieve a good student learning experience. Though suitable use of Information and Communication Technology should alleviate this problem, existing Virtual Learning Environments and e-Assessment applications such as Blackboard/WebCT, BOSS, MarkTool and GradeMark are inadequate to support a coursework assessment process that promotes timeliness and usefulness of feedback while maintaining consistency in marking involving multiple tutors. We have developed a novel Internet application, called eCAF, for facilitating an efficient and transparent coursework assessment and feedback process. The eCAF system supports detailed marking scheme editing and enables tutors to use such schemes to pin-point errors in students' work so as to provide helpful feedback efficiently. Tutors can also highlight areas in a submitted work and associate helpful feedback that clearly links to the identified mistakes and the respective marking criteria. In light of the results obtained from a recent trial of eCAF, we discuss how the key features of eCAF may facilitate an effective and efficient coursework assessment and feedback process.
Resumo:
Aims: Previous data suggest heterogeneity in laminar distribution of the pathology in the molecular disorder frontotemporal lobar degeneration (FTLD) with transactive response (TAR) DNA-binding protein of 43kDa (TDP-43) proteinopathy (FTLD-TDP). To study this heterogeneity, we quantified the changes in density across the cortical laminae of neuronal cytoplasmic inclusions, glial inclusions, neuronal intranuclear inclusions, dystrophic neurites, surviving neurones, abnormally enlarged neurones, and vacuoles in regions of the frontal and temporal lobe. Methods: Changes in density of histological features across cortical gyri were studied in 10 sporadic cases of FTLD-TDP using quantitative methods and polynomial curve fitting. Results: Our data suggest that laminar neuropathology in sporadic FTLD-TDP is highly variable. Most commonly, neuronal cytoplasmic inclusions, dystrophic neurites and vacuolation were abundant in the upper laminae and glial inclusions, neuronal intranuclear inclusions, abnormally enlarged neurones, and glial cell nuclei in the lower laminae. TDP-43-immunoreactive inclusions affected more of the cortical profile in longer duration cases; their distribution varied with disease subtype, but was unrelated to Braak tangle score. Different TDP-43-immunoreactive inclusions were not spatially correlated. Conclusions: Laminar distribution of pathological features in 10 sporadic cases of FTLD-TDP is heterogeneous and may be accounted for, in part, by disease subtype and disease duration. In addition, the feedforward and feedback cortico-cortical connections may be compromised in FTLD-TDP. © 2012 The Authors. Neuropathology and Applied Neurobiology © 2012 British Neuropathological Society.
Resumo:
In Alzheimer's disease (AD), neurofibrillary tangles (NFT) occur within neurons in both the upper and lower cortical laminae. Using a statistical method that estimates the size and spacing of NFT clusters along the cortex parallel to the pia mater, two hypotheses were tested: 1) that the cluster size and distribution of the NFT in gyri of the temporal lobe reflect degeneration of the feedforward (FF) and feedback (FB) cortico-cortical pathways, and 2) that there is a spatial relationship between the clusters of NFT in the upper and lower laminae. In 16 temporal lobe gyri from 10 cases of sporadic AD, NFT were present in both the upper and lower laminae in 11/16 (69%) gyri and in either the upper or lower laminae in 5/16 (31%) gyri. Clustering of the NFT was observed in all gyri. A significant peak-to-peak distance was observed in the upper laminae in 13/15 (87%) gyri and in the lower laminae in 8/ 12 (67%) gyri, suggesting a regularly repeating pattern of NFT clusters along the cortex. The regularly distributed clusters of NFT were between 500 and 800 μm in size, the estimated size of the cells of origin of the FF and FB cortico-cortical projections, in the upper laminae of 6/13 (46%) gyri and in the lower laminae of 2/8 (25%) gyri. Clusters of NFT in the upper laminae were spatially correlated (in phase) with those in the lower laminae in 5/16 (31%) gyri. The clustering patterns of the NFT are consistent with their formation in relation to the FF and FB cortico-cortical pathways. In most gyri, NFT clusters appeared to develop independently in the upper and lower laminae.
Resumo:
The 2008 National Student Survey revealed that: 44% of full-time students in England did not think that the feedback on their work had been prompt nor did they agree that the feedback on their work helped them clarify things that they did not understand (HEFCE, 2008). Computer Science and Engineering & Technology have been amongst the poorest performers in this aspect as they ranked in the lower quartile (Surridge, 2007, p.32). Five years since the first NSS survey, assessment and feedback remains the biggest concern. Dissatisfaction in any aspect of studies demotivates students and can lead to disengagement and attrition. As the student number grows, the situation can only get worse if nothing is done about it. We have conducted a survey to investigate views on assessment and feedback from Engineering, Mathematics and Computing students. The survey aims at investigating the core issues of dissatisfaction in assessment and feedback and ways in which UK Engineering students can learn better through helpful feedback. The study focuses on collecting students' experiences with feedback received in their coursework, assignments and quizzes in Computing Science modules. The survey reveals the role of feedback in their learning. The results of the survey help to identify the forms of feedback that are considered to be helpful in learning and the time frame for timely feedback. We report on the findings of the survey. We also explore ways to improve assessment and feedback in a bid to better engage engineering students in their studies.
Resumo:
A large body of evidence supports a role of oxidative stress in Alzheimer disease (AD) and in cerebrovascular disease. A vascular component might be critical in the pathophysiology of AD, but there is a substantial lack of data regarding the simultaneous behavior of peripheral antioxidants and biomarkers of oxidative stress in AD and vascular dementia (VaD). Sixty-three AD patients, 23 VaD patients and 55 controls were included in the study. We measured plasma levels of water-soluble (vitamin C and uric acid) and lipophilic (vitamin E, vitamin A, carotenoids including lutein, zeaxanthin, β-cryptoxanthin, lycopene, α- and β-carotene) antioxidant micronutrients as well as levels of biomarkers of lipid peroxidation [malondialdehyde (MDA)] and of protein oxidation [immunoglobulin G (IgG) levels of protein carbonyls and dityrosine] in patients and controls. With the exception of β-carotene, all antioxidants were lower in demented patients as compared to controls. Furthermore, AD patients showed a significantly higher IgG dityrosine content as compared to controls. AD and VaD patients showed similar plasma levels of plasma antioxidants and MDA as well as a similar IgG content of protein carbonyls and dityrosine. We conclude that, independent of its nature - vascular or degenerative - dementia is associated with the depletion of a large spectrum of antioxidant micronutrients and with increased protein oxidative modification. This might be relevant to the pathophysiology of dementing disorders, particularly in light of the recently suggested importance of the vascular component in AD development. Copyright © 2004 S. Karger AG, Basel.
Resumo:
Background: A large body of evidence supports a role of oxidative stress in Alzheimer disease (AD) and in cerebrovascular disease. A vascular component might be critical in the pathophysiology of AD. Objective(s): To evaluate the simultaneous behavior of a broad spectrum of peripheral antioxidants and biomarkers of oxidative stress in AD and vascular dementia (VaD). Methods: Sixty-three AD patients, 23 VaD patients and 55 controls were included in the study. We measured plasma levels of water-soluble (vitamin C and uric acid) and lipophilic (vitamin E, vitamin A, carotenoids including lutein, zeaxanthin, [3-cryptoxanthin, lycopene, c~- and [3-carotene) antioxidant micronutrients as well as levels of biomarkers of lipid peroxidation [malondialdehyde (MDA)] and of protein oxidation [immunoglobniin G (Ig G) levels of protein carbonyls and dityrosine] in patients and controls. Results: AD and VaD patients showed significantly decreased plasma levels of the water-soluble vitamin C and uric acid, of the lipophilic vitamin Eand vitamin A, and of the carotenoids lutein, zeaxanthin, 13-cryptoxanthin, lycopene and (x-carotene as compared to controls; among biomarkers of oxidative stress, only the content of dityrosine in Ig G was found to be significantly higher (p < 0.01) in AD patients as compared to controls; although a trend towards higher levels of dityrosine was also observed in VaD subjects compared to controls (6.3 4- 1.7 ~M in VaD patients vs. 5.1 4- 1.6 IxM in controls; p = 0.06), it did not reach statistical significance. In a cumulative analysis of all patient samples, a significant inverse association was found between plasma lycopene and MDA levels (r = -0.53, p < 0.0001). Conclusions: Independent of its nature-vascular or degenerativedementia is associated with the depletion of a large spectrum of antioxidant micronutrients and with increased protein oxidative modification. This might be relevant to the pathophysiology of dementing disorders, particularly in light of the recently suggested importance of the vascular component in AD development.
Resumo:
Once again this publication is produced to celebrate and promote good teaching and learning support and to offer encouragement to those imaginative and innovative staff who continue to wish to challenge students to learn to maximum effect. It is hoped that others will pick up some good ideas from the articles contained in this volume. We have again changed our approach for this 2006/07 edition (our fourth) of the Aston Business School Good Practice Guide. As before, some contributions were selected from those identifying interesting best practice on their Annual Module reflection forms in 2005/2006. Other contributors received HELM (Research Centre in Higher Education Learning and Management) small research grants in 2005/2006. Part of the conditions were for them to write an article for this publication. We have also been less tight on the length of the articles this year. Some contributions are, therefore, on the way to being journal articles. HELM will be working with these authors to help develop these for publication. The themes covered in this year?s articles are all central to the issues faced by those providing HE teaching and learning opportunities in the 21st Century. Specifically this is providing support and feedback to students in large classes, embracing new uses of technology to encourage active learning and addressing cultural issues in a diverse student population. Michael Grojean and Yves Guillaume used Blackboard™ to give a more interactive learning experience and improve feedback to students. It would be easy for other staff to adopt this approach. Patrick Tissington and Qin Zhou (HELM small research grant holders) were keen to improve the efficiency of student support, as does Roger McDermott. Celine Chew shares her action learning project, completed as part of the Aston University PG Certificate in Teaching and Learning. Her use of Blackboard™ puts emphasis on the learner having to do something to help them meet the learning outcomes. This is what learning should be like, but many of our students seem used to a more passive learning experience, so much needs to be done on changing expectations and cultures about learning. Regina Herzfeldt also looks at cultures. She was awarded a HELM small research grant and carried out some significant new research on cultural diversity in ABS and what it means for developing teaching methods. Her results fit in with what many of us are experiencing in practice. Gina leaves us with some challenges for the future. Her paper certainly needs to be published. This volume finishes with Stuart Cooper and Matt Davies reflecting on how to keep students busy in lectures and Pavel Albores working with students on podcasting. Pavel?s work, which was the result of another HELM small research grant, will also be prepared for publication as a journal article. The students learnt more from this work that any formal lecture and Pavel will be using the approach again this year. Some staff have been awarded HELM small research grants in 2006/07 and these will be published in the next Good Practice Guide. In the second volume we mentioned the launch of the School?s Research Centre in Higher Education Learning and Management (HELM). Since then HELM has stimulated a lot of activity across the School (and University) particularly linking research and teaching. A list of the HELM seminars for 2006/2007 is listed as Appendix 1 of this publication. Further details can be obtained from Catherine Foster (c.s.foster@aston.ac.uk), who coordinates the HELM seminars. For 2006 and 2005 HELM listed, 20 refereed journal articles, 7 book chapters, 1 published conference papers, 20 conference presentations, two official reports, nine working papers and £71,535 of grant money produced in this research area across the School. I hope that this shows that reflection on learning is alive and well in ABS. We have also been working on a list of target journals to guide ABS staff who wish to publish in this area. These are included as Appendix 2 of this publication. May I thank the contributors for taking time out of their busy schedules to write the articles and to Julie Green, the Quality Manager, for putting the varying diverse approaches into a coherent and publishable form and for agreeing to fund the printing of this volume.
Resumo:
This multi-modal investigation aimed to refine analytic tools including proton magnetic resonance spectroscopy (1H-MRS) and fatty acid gas chromatography-mass spectrometry (GC-MS) analysis, for use with adult and paediatric populations, to investigate potential biochemical underpinnings of cognition (Chapter 1). Essential fatty acids (EFAs) are vital for the normal development and function of neural cells. There is increasing evidence of behavioural impairments arising from dietary deprivation of EFAs and their long-chain fatty acid metabolites (Chapter 2). Paediatric liver disease was used as a deficiency model to examine the relationships between EFA status and cognitive outcomes. Age-appropriate Wechsler assessments measured Full-scale IQ (FSIQ) and Information Processing Speed (IPS) in clinical and healthy cohorts; GC-MS quantified surrogate markers of EFA status in erythrocyte membranes; and 1H-MRS quantified neurometabolite markers of neuronal viability and function in cortical tissue (Chapter 3). Post-transplant children with early-onset liver disease demonstrated specific deficits in IPS compared to age-matched acute liver failure transplant patients and sibling controls, suggesting that the time-course of the illness is a key factor (Chapter 4). No signs of EFA deficiency were observed in the clinical cohort, suggesting that EFA metabolism was not significantly impacted by liver disease. A strong, negative correlation was observed between omega-6 fatty acids and FSIQ, independent of disease diagnosis (Chapter 5). In a study of healthy adults, effect sizes for the relationship between 1H-MRS- detectable neurometabolites and cognition fell within the range of previous work, but were not statistically significant. Based on these findings, recommendations are made emphasising the need for hypothesis-driven enquiry and greater subtlety of data analysis (Chapter 6). Consistency of metabolite values between paediatric clinical cohorts and controls indicate normal neurodevelopment, but the lack of normative, age-matched data makes it difficult to assess the true strength of liver disease-associated metabolite changes (Chapter 7). Converging methods offer a challenging but promising and novel approach to exploring brain-behaviour relationships from micro- to macroscopic levels of analysis (Chapter 8).
Resumo:
A central component in pre-service teacher training is teaching practice and feedback. In some cases, feedback results in disquiet and tension (Brandt, 2008). Many researchers attribute this tension to the incompatibility of the assessment and development roles that the trainer must perform. The research reported on here, however, suggests that tension may also be rooted in a difference in expectation amongst trainers and trainees about the purpose and performance of feedback. This can result in trainees not playing by the rules of the game (Roberts & Sarangi, 2001) either because they do not understand them or because they wish to challenge them.
Resumo:
It is not known whether the association between increased plasma homocysteine (Hcy) associated with LDL modification and propensity for LDL uptake by macrophages in cardiovascular disease patients holds true in vascular dementia (VaD). Plasma from 83 subjects diagnosed with Alzheimer's disease (AD), VaD, mild cognitive impairment (MCI) and from controls was analysed to examine (1) whether LDL isolated from the plasma of VaD is biochemically and functionally distinct from that isolated from AD, MCI or controls; and (2) whether such biomarkers of LDL phenotype are related to plasma folate levels, Hcy levels and/or to disease severity. Folate and vitamin B6 levels were significantly lower in VaD subjects than in controls. VaD-LDL showed increased protein carbonyl content (p <0.05) and was more susceptible to scavenging by macrophages (p <0.05) than AD- or control-LDL. Patients from the VaD cohort were more prevalent in the lowest tertile for HDL:LDL and the upper tertile for LDL oxidation; the combined parameters of HDL cholesterol, LDL oxidation and scavenging by macrophages show 87% sensitivity towards VaD detection. The association between folate deficiency, LDL modification and dysfunction in VaD but not in AD may provide a novel biomarker assessment to discriminate between the diseases.
Resumo:
Corticobasal degeneration (CBD) is a rare and progressive neurological disorder characterised by the presence of ballooned neurons (BN) and tau positive inclusions in neurons and glial cells. We studied the spatial patterns of the BN, tau positive neurons with inclusions (tau + neurons), and tau positive plaques in the neocortex and hippocampus in 12 cases of CBD. All lesions were aggregated into clusters and in many brain areas, the clusters were distributed in a regular pattern parallel to the tissue boundary. In the majority of cortical areas, the clusters of BN were larger in the lower compared with the upper laminae while the clusters of tau + neurons were larger in the upper laminae. Clusters of BN and tau + neurons were either negatively correlated or not significantly correlated in the upper and lower cortical laminae. Hence, BN and tau + lesions in CBD exhibit similar spatial patterns as lesions in Alzheimer's disease (AD), dementia with Lewy bodies (DLB) and Pick's disease (PD). The location, sizes and distribution of the clusters in the neocortex suggest that the tau + lesions may be associated with the degeneration of the feedforward and the BN the feedback cortico-cortical and/or the efferent cortical pathways. © 2001 Elsevier Science Ireland Ltd. All rights reserved.