| 31231. |
- Goedecke, J. H., et al.
(författare)
-
Pathogenesis of type 2 diabetes risk in black Africans : a South African perspective
- 2020
-
Ingår i: Journal of Internal Medicine. - : John Wiley & Sons. - 0954-6820 .- 1365-2796. ; 288:3, s. 284-294
-
Tidskriftsartikel (refereegranskat)abstract
- The prevalence of type 2 diabetes (T2D) is higher in black Africans than their European counterparts. This review summarizes the research exploring the pathogenesis of T2D in populations of African ancestry compared to white Europeans and shows that the pathogenesis differs by ethnicity. Black Africans present with a phenotype of low insulin sensitivity and hyperinsulinaemia as a result of increased insulin secretion and reduced hepatic insulin clearance. Whether hyperinsulinaemia precedes insulin resistance or is merely a compensatory mechanism is yet to be determined. Black Africans have lower visceral adipose tissue and ectopic fat deposition and greater peripheral (gluteo-femoral) fat deposition than their European counterparts. This suggests that black Africans are more sensitive to the effects of ectopic fat deposition, or alternatively, that ectopic fat is not an important mediator of T2D in black Africans. Importantly, ethnic disparities in T2D risk factors may be confounded by differences in sociocultural and lifestyle factors. Future longitudinal and dietary intervention studies, in combination with genetic analyses, are needed for a better understanding of the pathophysiology of T2D in black Africans. This will be key for effective prevention and management strategies.
|
|
| 31232. |
- Goedecke, Julia H, et al.
(författare)
-
Reduced gluteal expression of adipogenic and lipogenic genes in black south african women is associated with obesity-related insulin resistance
- 2011
-
Ingår i: Journal of Clinical Endocrinology and Metabolism. - Philadelphia : Lippincott Williams & Wilkins. - 0021-972X .- 1945-7197. ; 96:12, s. E2029-E2033
-
Tidskriftsartikel (refereegranskat)abstract
- Context: Black South African women are less insulin sensitive than their White counterparts, despite less central and greater peripheral fat deposition. We hypothesized that this paradox may be explained, in part, by differences in the adipogenic capacity of sc adipose tissue (SAT). Objective: Our objective was to measure adipogenic and lipogenic gene expression in abdominal and gluteal SAT depots and determine their relationships with insulin sensitivity (S(I)) in South African women. Participants and Design: Fourteen normal-weight [body mass index (BMI) <25 kg/m(2)] Black, 13 normal-weight White, 14 obese (BMI >30 kg/m(2)) Black, and 13 obese White premenopausal South African women participated in this cross-sectional study.Main outcomes:S(I) (frequently sampled iv glucose tolerance test) in relation to expression of adipogenic and lipogenic genes in abdominal and gluteal SAT depots. Results: With increasing BMI, Black women had less visceral fat (P = 0.03) and more abdominal (P = 0.017) and gynoid (P = 0.041) SAT but had lower S(I) (P < 0.01) than White women. The expression of adipogenic and lipogenic genes was proportionately lower with obesity in Black but not White women in the gluteal and deep SAT depots (P < 0.05 for ethnicity × BMI effect). In Black women only, the expression of these genes correlated positively with S(I) (all P < 0.05), independently of age and fat mass. Conclusions: Obese Black women have reduced SAT expression of adipogenic and lipogenic genes compared with White women, which associates with reduced S(I). These findings suggest that obesity in Black women impairs SAT adipogenesis and storage, potentially leading to insulin resistance and increased risk of type 2 diabetes.
|
|
| 31233. |
- Goedecke, Julia H., et al.
(författare)
-
Waist circumference thresholds predicting incident dysglycaemia and type 2 diabetes in Black African men and women
- 2022
-
Ingår i: Diabetes, obesity and metabolism. - : John Wiley & Sons. - 1462-8902 .- 1463-1326. ; 24:5, s. 918-927
-
Tidskriftsartikel (refereegranskat)abstract
- Aims: To determine the waist circumference (WC) thresholds for the prediction of incident dysglycaemia and type 2 diabetes (T2D) in Black South African (SA) men and women and to compare these to the advocated International Diabetes Federation (IDF) Europid thresholds.Materials and Methods: In this prospective study, Black SA men (n = 502) and women (n = 527) from the Middle-aged Sowetan Cohort study who had normal or impaired fasting glucose at baseline (2011-2015) were followed up until 2017 to 2018. Baseline measurements included anthropometry, blood pressure and fasting glucose, HDL cholesterol and triglyceride concentrations. At follow-up, glucose tolerance was assessed using an oral glucose tolerance test. The Youden index was used to determine the optimal threshold of WC to predict incident dysglycaemia and T2D.Results: In men, the optimal WC threshold was 96.8 cm for both dysglycaemia and T2D (sensitivity: 56% and 70%; specificity: 74% and 70%, respectively), and had higher specificity (P < 0.001) than the IDF threshold of 94 cm. In women, the optimal WC threshold for incident dysglycaemia was 91.8 cm (sensitivity 86%, specificity 37%) and for T2D it was 95.8 cm (sensitivity 85%, specificity 45%), which had lower sensitivity, but higher specificity to predict incident dysglycaemia and T2D than the IDF threshold of 80 cm (sensitivity: 97% and 100%; specificity: 12% and 11%, respectively)).Conclusions: We show for the first time using prospective cohort data from Africa that the IDF Europid WC thresholds are not appropriate for an African population, and show that African-specific WC thresholds perform better than the IDF Europid thresholds to predict incident dysglycaemia and T2D.
|
|
| 31234. |
- Goesweiner, Christian, et al.
(författare)
-
Spin-spin relaxation of nuclear quadrupole resonance coherences and the important role of degenerate energy levels
- 2020
-
Ingår i: Molecular Physics. - : Taylor & Francis. - 0026-8976 .- 1362-3028. ; 118:17
-
Tidskriftsartikel (refereegranskat)abstract
- We present an extension of a Redfield approach for calculating spin-spin relaxation rates of zero-field nuclear quadrupole resonance (NQR) coherences, which was published in [Kruk et al., PCCP, 2018, 20, 23414-23426]. The oversimplification of the secular approximation made in the recent paper makes the calculation invalid for zero-field NQR and has led to partially large deviations between predicted and experimental data from 209Bi-containing molecular crystals. Furthermore, these deviations led to speculations about an additional dipole-dipole relaxation mechanism besides the main electric field gradient (EFG) fluctuations. Here, we demonstrate how a complete application of the Redfield relaxation expression eliminates the deviation from experimental data without the need for additional assumptions. In particular, we point out the important role of off-diagonal elements in the Redfield relaxation matrix within the 3/2-1/2 block appearing due to degenerate energy levels. The resulting coupling between single and double coherence spin density elements leads to a faster coherence decay than for all other transitions. The pseudo rotational model for EFG fluctuations, as proposed in the earlier publication and usually applied for isotropic liquids, is extended in a second analysis by introducing a vibrational mode to account for the case of crystalline solids.
|
|
| 31235. |
|
|
| 31236. |
- Goetz, Charlotte, et al.
(författare)
-
Warm protons at comet 67P/Churyumov-Gerasimenko-implications for the infant bow shock
- 2021
-
Ingår i: Annales Geophysicae. - : European Geosciences Union (EGU). - 0992-7689 .- 1432-0576. ; 39:3, s. 379-396
-
Tidskriftsartikel (refereegranskat)abstract
- The plasma around comet 67P/Churyumov-Gerasimenko showed remarkable variability throughout the entire Rosetta mission. Plasma boundaries such as the diamagnetic cavity, solar wind ion cavity and infant bow shock separate regions with distinct plasma parameters from each other. Here, we focus on a particular feature in the plasma: warm, slow solar wind protons. We investigate this particular proton population further by focusing on the proton behaviour and surveying all of the Rosetta comet phase data. We find over 300 events where Rosetta transited from a region with fast, cold protons into a region with warm, slow protons. We investigate the properties of the plasma and magnetic field at this boundary and the location where it can be found. We find that the protons are preferentially detected at intermediate gas production rates with a slight trend towards larger cometocentric distances for higher gas production rates. The events can mostly be found in the positive convective electric field hemisphere. These results agree well with simulations of the infant bow shock (IBS), an asymmetric structure in the plasma environment previously detected on only 2 d during the comet phase. The properties of the plasma on both sides of this structure are harder to constrain, but there is a trend towards higher electron flux, lower magnetic field, higher magnetic field power spectral density and higher density in the region that contains the warm protons. This is in partial agreement with the previous IBS definitions; however, it also indicates that the plasma and this structure are highly non-stationary. For future research, Comet Interceptor, with its multi-point measurements, can help to disentangle the spatial and temporal effects and give more clarity on the influence of changing upstream conditions on the movement of boundaries in this unusual environment.
|
|
| 31237. |
- Goggins, S., et al.
(författare)
-
Computer-Supported Collaborative Learning at Work : CSCL@Work - Bridging Learning and Work
- 2013
-
Ingår i: CSCL 2013 conference proceedings volume 2. ; , s. 436-440
-
Konferensbidrag (refereegranskat)abstract
- We created an interdisciplinary workshop to explore principles of computer-supported collaborative learning in work settings. The workshop's theme was, simply CSCL at work. Our first workshop at ACM Group 2010, the 2 nd at ACM Group 2012, and the resulting book, raise an important set of issues and potentials for research, but does not solve the thorny and controversial issues. This workshop wanted to make progress on the identified issues. The CSCL@Work workshop was a half-day workshop devoted to sharing innovative approaches and discussing solutions aimed at understanding studying and designing 'learning at work' supported by digital/mobile technologies. We selected the CSCL conference as an ideal venue for a workshop on this topic because the North American and European communities who participate in the Learning Sciences include leading members of the international CSCL communities. The workshops at ACM group focused more on CSCW whereas this proposed workshop on CSCL2013 included CSCL researchers. It started with contextualizing the current situation. Then, participant questions and proposed solutions aimed at the issues we have raised and begun to recognize. We focused on working groups, an approach, which supports knowledge building. To participate in the workshop, discussants was asked for a position paper of up to 2 pages in standard CSCL conference format. Our edited book was made available to participants in advance, and selected authors provided overviews of their work and perspective in an interleaved way with the more action oriented working sessions.
|
|
| 31238. |
- Goggins, Sean P., et al.
(författare)
-
Computer-supported collaborative learning at work : CSCL@Work goes TEL@Work
- 2013
-
Ingår i: ECTEL-meets-ECSCW 2013. - : CEUR-WS. ; , s. 30-34
-
Konferensbidrag (refereegranskat)abstract
- We propose the topic of "CSCL at Work" which we advanced through workshops at ACM Group 2010, ACM Group 2012 and CSCL 2013. The resulting book raises an important set of issues and potential topics for research and practice but, like any agenda setting work, does not solve thorny or controversial issues. CSCL@Work provides one possible viewpoint for bridging informal learning and work. The purpose of our proposal is to share innovative approaches discovered to date, and gain input focused on solutions aimed for understanding, studying and designing Technology-enhanced learning at work. From 13 case studies, three main theses can be derived that characterize how and when learning at work takes places, A) Learning occurs in unexpected and unusual online learning places, including Social Media. B) Learning activities incorporate feedback from diverse sources, which are not available within traditional organizational boundaries. C) learning takes place across established boundaries. Theses issues inform the design of collaborative technologies, technology-enhanced learning (TEL) and sociotechnical learning practices. To make learning visible, we argue that individual and collaborative learning design must support the alignment of pedagogical, social and technological design. This alignment will increase the likelihood of both surface and deep learning at the workplace.
|
|
| 31239. |
- Goggins, Sean P, et al.
(författare)
-
CSCL@work : making learning visible in unexpected online places across established boundaries
- 2012
-
Ingår i: International Journal of Sociotechnology and Knowledge Development. - : IGI Global. - 1941-6253 .- 1941-6261. ; 4:3, s. 17-37
-
Tidskriftsartikel (refereegranskat)abstract
- We introduce Computer-Supported Collaborative Learning (CSCL) at the workplace (CSCL@Work) as a conceptual framework for bridging the knowledge of researchers in the field of CSCL to work-based learning. Research in the field of Organizational Learning emerged in 1978, and gained further attention in the 1990’s when challenges centered on the creation of organizational cultures to support existing knowledge sharing. In contemporary firms, shepherding the creation of new knowledge is of equal importance, and is driven by two primary research questions. First, how do organizations create new knowledge when the answer to a particular problem is not available within the firm? Second, what cultures of learning must and do exist to support solving problems when the answer is not known within an organization? Contemporary answers to these questions must recognize that learning is an implicit, often invisible component of work, and explicitly decouple the construct of learning from its main western institutionalization, the school. To advance thinking in this area, we undertook a meta analysis of 8 CSCL@Work cases and developed 3 design theses: 1) Learning occurs in unexpected and unusual online learning places, especially through Social Media. 2) Learning activities incorporate feedback from diverse people, who are not available within traditional organizational boundaries; 3) learning must be made visible across established boundaries. Designing explicit construction of new knowledge needs to be integrated into workplace practices today through pedagogical and technological design.
|
|
| 31240. |
- Goggins, Sean P., et al.
(författare)
-
CSCL@Work revisited - beyond CSCL and CSCW? : Are There Key Design Principles for Computer Supported Collaborative Learning at the Workplace?
- 2012
-
Ingår i: GROUP’12 Proceedings of the ACM 2012 International Conference on Support Group Work. - New York, NY, USA : The Association for Computing Machinery. - 9781450314862 ; , s. 323-326
-
Konferensbidrag (refereegranskat)abstract
- We propose an interdisciplinary workshop to explore key design principles of collaborative learning in the workplace. The workshop's theme is, simply "CSCL at the workplace". Our first workshop at ACM Group 2010, and the resulting book, raise an important set of issues and potentials for research, but does not solve the thorny and controversial issues. This workshop will be focused on for making progress on the identified issues. The ACM Group conference remains an ideal venue for a workshop on this topic because the North American and European communities who participate in Group include leading members of the international CSCL and CSCW communities. The proposed workshop will be a full day. It will open with a situating presentation by the organizers and, participant questions and proposed solutions aimed at the issues we have raised and begun to recognize, and focus working groups on the resolution of those issues in work to follow the conference. To participate in the workshop, discussants will be asked for a position paper of up to 2 pages in standard ACM format. Our edited book will be made available to participants in advance, and selected authors who will be present will provide overviews of their work and perspective in an interleaved way with the more action oriented working sessions.
|
|
