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Sökning: WFRF:(Berggren Per Docent)

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1.
  • Amoignon, Olivier, 1969- (författare)
  • Numerical Methods for Aerodynamic Shape Optimization
  • 2005
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Gradient-based aerodynamic shape optimization, based on Computational Fluid Dynamics analysis of the flow, is a method that can automatically improve designs of aircraft components. The prospect is to reduce a cost function that reflects aerodynamic performances.When the shape is described by a large number of parameters, the calculation of one gradient of the cost function is only feasible by recourse to techniques that are derived from the theory of optimal control. In order to obtain the best computational efficiency, the so called adjoint method is applied here on the complete mapping, from the parameters of design to the values of the cost function. The mapping considered here includes the Euler equations for compressible flow discretized on unstructured meshes by a median-dual finite-volume scheme, the primal-to-dual mesh transformation, the mesh deformation, and the parameterization. The results of the present research concern the detailed derivations of expressions, equations, and algorithms that are necessary to calculate the gradient of the cost function. The discrete adjoint of the Euler equations and the exact dual-to-primal transformation of the gradient have been implemented for 2D and 3D applications in the code Edge, a program of Computational Fluid Dynamics used by Swedish industries.Moreover, techniques are proposed here in the aim to further reduce the computational cost of aerodynamic shape optimization. For instance, an interpolation scheme is derived based on Radial Basis Functions that can execute the deformation of unstructured meshes faster than methods based on an elliptic equation.In order to improve the accuracy of the shape, obtained by numerical optimization, a moving mesh adaptation scheme is realized based on a variable diffusivity equation of Winslow type. This adaptation has been successfully applied on a simple case of shape optimization involving a supersonic flow. An interpolation technique has been derived based on a mollifier in order to improve the convergence of the coupled mesh-flow equations entering the adaptive scheme.The method of adjoint derived here has also been applied successfully when coupling the Euler equations with the boundary-layer and parabolized stability equations, with the aim to delay the laminar-to-turbulent transition of the flow. The delay of transition is an efficient way to reduce the drag due to viscosity at high Reynolds numbers.
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2.
  • Berggren, Jan, 1965- (författare)
  • Engelskundervisning i gymnasieskolan för mobilisering av ungdomars livschanser
  • 2013
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Berggren, Jan (2013). Engelskundervisning i gymnasieskolan för mobilisering av ungdomars livschanser. (English teaching in upper secondary school and mobilization of young people's life chances). Linnaeus University Dissertations No 156/2013, ISBN: 978-91-87427-64-0. Written in Swedish with a summary in English.English is a school subject which every Swedish upper secondary student is required to take. The selection and dissemination of knowledge among students attending upper secondary programmes carries the intention of social integration as well as specialization. The aim of this dissertation is then to show how perspectives on education in English elicited from teachers’ and students’ responses in interviews as well as Swedish education policy (SOU, directives, propositions) contribute to the conditions for the selection of knowledge and teaching, on and between programmes.Inspired by Basil Bernstein’s theories of educational sociology (1990, 2000) and Fairclough och Chouliaraki’s critical discourse analysis, CDA (1999), albeit adjusted to the aim of this study in pedagogics, the focus is on teachers’ and students’ views on teaching and knowledge in English classes on four vocational and academic programmes, establishing varying discourse practices on the different programmes. Moreover, perspectives on upper secondary teaching in Swedish education policy texts are analysed following the same methodology.Results indicate that education policy texts at the time of the interviews strive for adjustment of course content in English teaching to the programme (termed ‘infärgning’ in Swedish). Reflecting this trend in education policy, teachers and students on programmes speak of aspirations for English teaching as being either adapted for mainly academic purposes, or vocational and everyday-life purposes. On the basis of these aspirations it is argued that teachers and students establish either academically oriented discourse or vocational and everyday-life oriented discourse as the dominant pedagogical discourse on the individual programme. Thus, education policy as well as teachers and students reflect each other in striving for knowledge to be adapted for the programme. The two discourses contribute to a movement in favour of differences between programmes, though some of the vocational students complain on not being offered possibilities to analyse and discuss current problems in society. This is to say they complain that they do not receive an education in line with the academically oriented discourse, which is offered to students on academic programmes. At the same time, vocational students are dissatisfied in not gaining adequate knowledge in vocational English.Finally, these perspectives indicate discursive conditions for the selection of knowledge and the organization of teaching in English classes on different programmes. In the last chapter of the dissertation these varying perspectives on programmes concerning the selection of knowledge are analysed but now with a focus on the relationship between programmes. Consequences of the varying dominant pedagogical discourses on the programmes are discussed with regard to how they can be understood to mobilize life chances of young people differently, creating conditions for social integration and differentiation. Keywords: Selection of knowledge, upper secondary education, English, education policy, critical discourse analysis, sociology of education, social integration, social differentiation
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3.
  • Saghaleyni, Rasool, 1987, et al. (författare)
  • Enhanced metabolism and negative regulation of ER stress support higher erythropoietin production in HEK293 cells
  • 2022
  • Ingår i: Cell Reports. - : Elsevier BV. - 2211-1247. ; 39:11
  • Tidskriftsartikel (refereegranskat)abstract
    • Recombinant protein production can cause severe stress on cellular metabolism, resulting in limited titer and product quality. To investigate cellular and metabolic characteristics associated with these limitations, we compare HEK293 clones producing either erythropoietin (EPO) (secretory) or GFP (non-secretory) protein at different rates. Transcriptomic and functional analyses indicate significantly higher metabolism and oxidative phosphorylation in EPO producers compared with parental and GFP cells. In addition, ribosomal genes exhibit specific expression patterns depending on the recombinant protein and the production rate. In a clone displaying a dramatically increased EPO secretion, we detect higher gene expression related to negative regulation of endoplasmic reticulum (ER) stress, including upregulation of ATF6B, which aids EPO production in a subset of clones by overexpression or small interfering RNA (siRNA) knockdown. Our results offer potential target pathways and genes for further development of the secretory power in mammalian cell factories.
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4.
  • Shah, Farhan, 1975- (författare)
  • Neuromuscular injuries and pharyngeal dysfunction in snorers and sleep apnea patients : a study on pathological changes in the human soft palate and its relationship with swallowing dysfunction
  • 2018
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Obstructive sleep apnea (OSA) is a prevalent progressive sleep disorder with serious negative health consequences. Although several risk factors such as obesity can make an individual vulnerable to develop OSA, the pathophysiological mechanism for the collapse of the upper airway is unclear. Moreover, the etiology of the commonly occurring swallowing dysfunction in snorers and sleep apnea patients is not understood. In the light of this, we aimed to investigate whether muscle and nerve changes in upper airway contributes to pharyngeal dysfunction in snorers and sleep apnea patients.Twenty-two patients (1 female, 21 males, mean age 45 years) undergoing soft palate surgery because of snoring and sleep apnea were included in the study. Ten healthy non-snoring males, mean age 38 years, were recruited as controls. Biopsies from the uvula were obtained from both patients and voluntary controls. Control autopsies from both uvula and palatopharyngeus muscles were taken post mortem from 6 previously healthy adult subjects (3 males, 3 females, mean age 52 years) and two male infants (age 4 months and 1.4 years). Overnight sleep registration and videoradiographic examinations of pharyngeal swallowing function were performed in both patients and voluntary controls.Enzyme and immunohistochemistry and morphometric techniques were used to investigate cytoskeletal and membrane proteins desmin and dystrophin and two neurotrophins, brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF). The nerve fascicles in the soft palate were explored for changes in axon and Schwann cell density and for signs of axon regeneration. All patients were snores, and 14 patients had OSA with a mean apnea-hypopnea index 24, range 5-84. Sixteen of the 22 patients had swallowing dysfunction. None of the 10 voluntary controls had sleep apnea or swallowing dysfunction. In both controls and patients, a subgroup of muscle fibers in the soft palate lacked immunoreaction for desmin and the C-terminus of dystrophin, and these fibers were more common in patients than in controls (p<0.001). Moreover, muscle fibers with disorganized desmin were commonly observed in patients, but not in controls (p<0.001). Thus, overall, desmin abnormalities were significantly more frequent in patients (46 vs. 15%, p<0.001), and some of these fibers showed upregulation of BDNF. In addition, nerve fascicles from the soft palate of patients displayed lower density of axons (p<0.02) and a smaller area occupied by Schwann cells (p=0.001) compared to controls. The axon density within nerve fascicles as well as the cytoskeletal abnormalities in muscles correlated significantly with swallowing dysfunction (rs=0.50 and 0.76, respectively, p≤0.03).To conclude, human soft palate muscles seem to be of a unique allotype. In the soft palate of snorers and sleep apnea patients, cytoskeletal myopathy and neuropathy were frequently observed, and these changes correlate significantly with pharyngeal swallowing dysfunction. The upregulation of BDNF in muscle fibers of patients may relate to a regenerative attempt after injury. Consequently, a disturbed sensorimotor function and muscle weakness may contribute to development and progression of swallowing dysfunction and OSA. Traumatic snoring vibrations and muscle overload are plausible causes of the neuromuscular injuries. 
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5.
  • Särnblad Hansson, Anna, 1975- (författare)
  • Ecology and genetic population structure of Indo-Pacific bottlenose dolphins in East Africa
  • 2011
  • Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
    • Many marine mammal populations are threatened by anthropogenic activities. The Indo-Pacific bottlenose dolphins (Tursiops aduncus) off Zanzibar are subject to high levels of bycatch, negative impact from tourism and were previously hunted. To assess conservation status and to formulate necessary management actions for viable dolphin populations, knowledge of their population ecology is vital. This thesis provides information on population size, distribution, social structure, genetic diversity and population differentiation for Indo-Pacific bottlenose dolphins off southern Zanzibar. To investigate these parameters, individual identification and group structure data collected during boat based surveys were used in combination with genetic analyses of tissue samples from bycaught animals and skin biopsies from free ranging animals. The results show that the area off southern Zanzibar potentially constitute an important nursing ground (Paper I, II) for the relatively small population of Indo-Pacific bottlenose dolphins present year round (Paper I). The dolphins in this area live in a fission-fusion society where some animals also form long-term relationships (Paper II). Genetic analyses indicate limited exchange of reproducing females between northern and southern Zanzibar suggesting female philopatry with a greater dispersal by males (Paper III, IV). The relatively high genetic diversity of the Indo-Pacific bottlenose dolphins off Zanzibar indicates no current threat to their genetic health, despite recent anthropogenic impacts. (Paper IV). On a greater geographical scale the results show that the Indo-Pacific bottlenose dolphins in the western Indian Ocean, ranging from Oman to South Africa, share a relatively recent common founder population and belong to a proposed third species within the genus Tursiops (Paper III, IV). Finally, the results presented demonstrate the value of a multi-disciplinary approach to determine the conservation status of animal populations.
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