| 1. |
- Jakobsson, Erik, et al.
(author)
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Unexpected potentials for growth
- 2013
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In: Capturing effects. - : Studentlitteratur AB. - 9789144093000 ; , s. 163-181
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Book chapter (other academic/artistic)
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| 2. |
- Demelash, Abeba, 1962
(author)
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Regulation of apoptosis in the thyroid epithelium
- 2004
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Doctoral thesis (other academic/artistic)abstract
- Apoptosis or programmed cell death allows the multicellular organism to remove cells that are in excess or potentially dangerous. Apoptosis has to be strictly controlled, yet inappropriately activated or suppressed apoptototic may contribute to a variety of diseases, including cancer, autoimmune disorders and neurodegenerative conditions. Due to the generation of hydrogen peroxide (H2O2) required for biosynthesis of thyroid hormone the thyroid epithelial cells are constantly subjected to large amounts of reactive oxygen species (ROS), which are capable of inducing apoptosis in many cell types. However, the mechanism by which ROS induce apoptosis has not been fully understood. The aim of this thesis was to elucidate the mechanism of apoptosis induced by H2O2, staurosporine and transforming growth factor-beta (TGF-beta1) in primary cultured thyroid cells. The enzymatic activity of caspase-3 was measured by monitoring cleavage of the exogenous peptide substrat Ac-DEVD-AMC (papers I, II and IV). Analysis of nuclear morphology and DNA fragmentation was accomplished by DAPI staining followed by fluorescence microscopy and gel electrophoresis (paper I). Immunofluorescence, confocal microscopy and electron microscopy were performed for subcellular localization studies (papers II-IV). Protein identification was performed by immunoblotting (paper IV). Using an experimental model of the thyroid follicular epithelium in which thyrocytes are grown as a tight monolayer on filter in a bicameral chamber, the effects of H2O2, staurosporine and TGF-beta1 on the integrity of the thyroid epithelium were studied (papers III and IV). The present findings provide evidence of a caspase-3-dependent mechanism of apoptosis in H2O2-, -staurosporine- and TGF-beta1-treated thyroid epithelial cells. A characteristic fragmentation pattern commonly referred to as DNA laddering was found in cells treated with staurosporine. H2O2, at micromolar concentrations, and TGF-beta1 caused a more diffuse degradation of DNA. Selenium-substituted cells with a high glutathione peroxidase (GPx) activity had a much better capacity to withstand H2O2 and effectively protect against proapoptotic signals than cells with low GPx activity. Localization studies demonstrated translocation of cytochrome c (cyt-c) from mitochondria to the cytoplasm in staurosporine-treated cells. During H2O2-mediated thyroid cell apoptosis, the cyt-c release from mitochondria to the cytosol was restricted. Instead, H2O2-treated cells showed aggregation and fragmentation of mitochondria and shrunken and highly condensed nuclie. Caspase and calpain inhibitors modified the apoptotic response to H2O2, suggesting cooperation of these proteolytic systems in the execution of apoptosis. The thyroid epithelial barrier is rapidly disrupted by H2O2. Cells with ordinary GPx activity do not have a better capacity to prevent H2O2-induced epithelial dysfunction than cells with a low GPx activity. However, selenium yet exerts a protective effect on epithelial integrity. Staurosporine and TGF-beta1 induce loss of barrier function, but this occur independently of caspase-3 activation and apoptosis.
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| 3. |
- Demelash, Abeba, 1962, et al.
(author)
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Selenium has a protective role in caspase-3-dependent apoptosis induced by H2O2 in primary cultured pig thyrocytes.
- 2004
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In: European journal of endocrinology / European Federation of Endocrine Societies. - 0804-4643. ; 150:6, s. 841-9
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Journal article (peer-reviewed)abstract
- OBJECTIVE: Hydrogen peroxide (H2O2), necessary for thyroid hormonogenesis, is produced at the apical surface of the thyroid follicular epithelium. Excess H2O2 is potentially cytotoxic and may contribute to the development of hypothyroidism, e.g. in severe selenium deficiency. Yet it is unclear how H2O2 contributes to thyroid cell death. DESIGN AND METHODS: H2O2-induced apoptosis and necrosis were studied in primary cultured pig thyroid cells. Glutathione peroxidase (GPx) activity was altered by culture in low serum with or without selenite substitution. Apoptosis was evaluated by spectrofluorometric measurement of caspase-3-specific substrate cleavage, and by analysis of DNA fragmentation by agarose gel electrophoresis. Necrosis was detected by 51Cr release from prelabeled cells. RESULTS: Exogenous H2O2 dose-dependently (100-400 micromol/l) activated caspase-3 within 3-12 h, and DNA degradation was observed after 24 h. The potency of H2O2 to induce apoptosis was low compared with that of staurosporine, a strong proapoptotic agent. H2O2-treated cells with reduced GPx activity showed increased caspase-3 activation. Incubation of serum-starved cells with selenite (10-100 nmol/l) normalized the GPx activity and reduced the activation of caspase-3 by H2O2. High H2O2 concentrations (400-800 micromol/l) were required to obtain necrosis. The H2O2-induced necrosis was exaggerated by both low GPx activity and catalase inhibition. CONCLUSIONS: Cytotoxic effects of H2O2 on thyroid cells include caspase-3-dependent apoptosis that occurs at H2O2 concentrations insufficient to induce necrosis. Selenium deficiency aggravates the apoptotic response, probably due to impaired capacity of GPx to degrade H2O2.
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| 4. |
- Merolli, Mark, et al.
(author)
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Global communication practices of physiotherapists on Twitter
- 2019
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In: European Journal of Physiotherapy. - : Taylor & Francis. - 2167-9169 .- 2167-9177. ; 21:1, s. 20-26
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Journal article (peer-reviewed)abstract
- Background: Social media have offered professional communities the opportunity to be digitally connected. The hashtag #GlobalPT was conceived and promoted from 2015 and has acted as a slogan for the globally connected physiotherapy community. This study explores the global reach and dominant communication themes that emerged during a set time frame that represented the single largest period of #GlobalPT activity.Method: Using purposive sampling, 988 publically available tweets including the hashtag #GlobalPT were studied. Descriptive statistical analysis was conducted to quantify tweet data and qualitative, inductive phenomenological thematic content analysis to describe latent themes within the tweets.Results: #GlobalPT activity was noted across 24 countries (UK top represented) and four languages (929/988, 94.03% in English). Europe was the most active area (738/988, 74.70%), followed by Oceania (120/988, 12.15%). Thematic content analysis identified eight themes within the communication practices of the physiotherapy community on Twitter. The three major themes were: sharing information (108/377, 28.65%), promotional activity (93/377, 24.67%) and positive feedback (69/377, 18.30%).Conclusion: The professional communication practices of physiotherapists on Twitter show a global spread of communication. The themes provide preliminary evidence for social media’s unique potential to assist the World Confederation for Physical Therapy strategic vision.
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| 5. |
- Peng, Shanchi, et al.
(author)
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Global Standard Stratotype-Section and Point (GSSP) for the Base of the Jiangshanian Stage (Cambrian: Furongian) at Duibian, Jiangshan, Zhejiang, Southeast China
- 2012
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In: Episodes. - 0705-3797. ; 35:4, s. 462-477
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Journal article (peer-reviewed)abstract
- The International Commission on Stratigraphy and the IUGS Executive Committee have recently approved a Global Standard Stratotype-section and Point (GSSP) defining the base of the second stage of the Furongian Series, Cambrian System. This stage is named the Jiangshanian Stage, after Jiangshan City, western Zhejiang Province, China, where the GSSP is located. The GSSP is exposed in a natural outcrop near Duibian Village. It is defined at the base of a limestone (wackestone) layer 108.12 m above the base of the Huayansi Formation in the Duibian B section, coinciding with the first appearance of the cosmopolitan agnostoid trilobite Agnostotes orientalis (base of the A. orientalis Zone). The GSSP is at a position of 28 degrees 48.977'N latitude and 118 degrees 36.887 'E longitude. Secondary global markers at or near the base of the stage include the first appearance of the cosmopolitan polymerid trilobite Irvingella angustilimbata, which coincides with the FAD of the primary marker in the stratotype section, and near the end of a large positive carbon isotopic excursion (SPICE excursion). Faunal turnovers close to the base of the Jiangshanian Stage have been recognized as being at the base of the Iverian Stage in Australia, the Gonggrian Stage in Korea, and the Agnostotes orientalis Irvingella perfecta Zone in Siberia, and near the base of the Aksayan Stage in Kazakhstan, the Sunwaptan Stage in Laurentia, and the Parabolina brevispina Zone in Baltica.
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| 6. |
- Peng, Shia Hui, et al.
(author)
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Approximation of subgrid-scale stresses based on the Leonard expansion
- 2009
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In: Turbulence, Heat and Mass Transfer 6.
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Conference paper (peer-reviewed)abstract
- Based on the reconstruction series for subgrid-scale (SGS) stress tensor, SGS modellingis revisited. It is shown that, along with the first Leonard term in the series, the second term is alsoexploitable in relation to the viscous dissipation rate tensor, "ij , being further subjected to a Leonardexpansion. The approximation of "ij is discussed in analogy to RANS modelling. With the assumptionof anisotropy dissipation, it is shown that the second term can be approximated in terms of an eddyviscosityformulation, which, together with the first Leonard term, forms a two-term mixed model. Theresulting mixed model has been analyzed in LES of turbulent channel flow. The emphasis in the presentwork has been placed on the effect of model coefficients. The Leonard term may induce negative diffusionassociated to energy backscatter, while the second Smagorinsky term reinforces energy dissipation.Moreover, the modelled Leonard stresses have also been highlighted in the computation.
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| 7. |
- Bano, Sayyeda Umbereen, et al.
(author)
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A Comparative Analysis Of Techniques For Real-Time Transient Stability Assessment
- 2022
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In: 2022 North American Power Symposium, NAPS 2022. - : Institute of Electrical and Electronics Engineers (IEEE).
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Conference paper (peer-reviewed)abstract
- Real-time monitoring of transient stability is crucial in power systems to avoid sudden blackout and power failure. Previously developed algorithms based on the concept of Maximum Lyapunov Exponent and Synchrophasor Measurements claim to have fast prediction of transient stability after a severe disturbance. In this paper, formerly established techniques for real-time transient stability assessment are implemented to the IEEE-39 bus test system for various fault case scenarios. Based on the obtained results from these techniques, a comparative analysis is performed to determine accuracy, effectiveness and robustness of each technique.
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| 8. |
- Golestani, S.J., et al.
(author)
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Transmission network expansion planning considering unit commitment problem simultaneously
- 2010
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In: IEEE PES Innovative Smart Grid Technologies Conference Europe, ISGT Europe 2010; Gothenburg; Sweden; 11 October 2010 through 13 October 2010. - 9781424485109 ; , s. Art. no. 5638905-
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Conference paper (peer-reviewed)abstract
- Transmission Network Expansion Planning (TNEP) is an important part of power system planning in new structured power market. Its goal is to minimize the network construction and operational cost while satisfying the demand increase, considering technical and economic conditions. Since change in Unit Commitment (UC), influences transmission lines, this paper presents an Integer Coded Genetic Algorithm (ICGA) to solve both problems together. Genetic algorithm can consider all generation and network constraints. Also random behavior of genetic algorithm can simulate real probabilities such as uncertainty in generation. Considering uncertainty for some units, in each iteration, it can find out the probability of congestion for each line. After all iterations it can highlight the transmission lines which need expansion, because of high congestion probability. Simulation results of the proposed idea are presented for IEEE30-bus network.
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