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Schedin, S., Hallberg, P. & Behndig, A. (2017). Analysis of long-term visual quality with numerical 3D ray tracing after corneal crosslinking treatment. Applied Optics, 56(35), 9787-9792
Open this publication in new window or tab >>Analysis of long-term visual quality with numerical 3D ray tracing after corneal crosslinking treatment
2017 (English)In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 56, no 35, p. 9787-9792Article in journal (Refereed) Published
Abstract [en]

A numerical 3D ray tracing model was used to evaluate the long-term visual effects of two regimens of corneal crosslinking (CXL) treatment of 48 patients with the corneal degeneration keratoconus. The 3D ray tracing analyses were based on corneal elevation data measured by Scheimpflug photography. Twenty-two patients were treated with standard CXL applied uniformly across the corneal surface, whereas 26 patients underwent a customized, refined treatment only at local zones on the cornea (photorefractive intrastromal CXL; PiXL). Spot diagrams, spot root-mean-square (RMS) values, and Strehl ratios were evaluated for the patients prior to and 1, 3, 6, and 12 months after treatment. It was found that the group of patients treated with PiXL, on average, tended to attain a long-term improvement of the corneal optical performance, whereas only minor changes of the optical parameters were found for group treated with standard CXL. Our results confirmed that standard CXL treatment stabilizes the corneal optical quality over time, and thus halts the progression of the corneal degeneration. In addition to stabilization, the results showed that a significantly higher proportion of subjects treated with PiXL improved in RMS, 3, 6, and 12 months after treatment, compared to with CXL (p<0.05). This finding indicates that the PiXL treatment might improve optical quality over time.

Place, publisher, year, edition, pages
Optical Society of America, 2017
Keywords
Ophthalmic optics and devices, Geometric optical design, Vision acuity, Visual optics, modeling, Visual optics, refractive anomalies
National Category
Other Physics Topics
Identifiers
urn:nbn:se:umu:diva-142716 (URN)10.1364/AO.56.009787 (DOI)000417553500023 ()29240126 (PubMedID)
Available from: 2017-12-08 Created: 2017-12-08 Last updated: 2018-06-09Bibliographically approved
Bugaytsova, J. A., Björnham, O., Chernov, Y. A., Gideonsson, P., Henriksson, S., Mendez, M., . . . Boren, T. (2017). Helicobacter pylori Adapts to Chronic Infection and Gastric Disease via pH-Responsive BabA-Mediated Adherence. Cell Host and Microbe, 21(3), 376-389
Open this publication in new window or tab >>Helicobacter pylori Adapts to Chronic Infection and Gastric Disease via pH-Responsive BabA-Mediated Adherence
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2017 (English)In: Cell Host and Microbe, ISSN 1931-3128, E-ISSN 1934-6069, Vol. 21, no 3, p. 376-389Article in journal (Refereed) Published
Abstract [en]

The BabA adhesin mediates high-affinity binding of Helicobacter pylori to the ABO blood group antigen-glycosylated gastric mucosa. Here we show that BabA is acid responsive-binding is reduced at low pH and restored by acid neutralization. Acid responsiveness differs among strains; often correlates with different intragastric regions and evolves during chronic infection and disease progression; and depends on pH sensor sequences in BabA and on pH reversible formation of high-affinity binding BabA multimers. We propose that BabA's extraordinary reversible acid responsiveness enables tight mucosal bacterial adherence while also allowing an effective escape from epithelial cells and mucus that are shed into the acidic bactericidal lumen and that bio-selection and changes in BabA binding properties through mutation and recombination with babA-related genes are selected by differences among individuals and by changes in gastric acidity over time. These processes generate diverse H. pylori subpopulations, in which BabA's adaptive evolution contributes to H. pylori persistence and overt gastric disease.

Place, publisher, year, edition, pages
CELL PRESS, 2017
National Category
Microbiology in the medical area Medical Biotechnology (with a focus on Cell Biology (including Stem Cell Biology), Molecular Biology, Microbiology, Biochemistry or Biopharmacy)
Identifiers
urn:nbn:se:umu:diva-132788 (URN)10.1016/j.chom.2017.02.013 (DOI)000396375600023 ()28279347 (PubMedID)
Available from: 2017-05-11 Created: 2017-05-11 Last updated: 2019-05-24Bibliographically approved
Wadbro, E., Hallberg, P. & Schedin, S. (2016). Optimization of an intraocular lens for correction of advanced corneal refractive errors. Applied Optics, 55(16), 4378-4382
Open this publication in new window or tab >>Optimization of an intraocular lens for correction of advanced corneal refractive errors
2016 (English)In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 55, no 16, p. 4378-4382Article in journal (Refereed) Published
Abstract [en]

Based on numerical 3D ray tracing, we propose a new procedure to optimize personalized intra-ocular lenses (IOLs). The 3D ray tracing was based on measured corneal elevation data from patients who suffered from advanced keratoconus. A mathematical shape description of the posterior IOL surface, by means of a tensor product cubic Hermite spline, was implemented. The optimized lenses provide significantly reduced aberrations. Our results include a trade-off study that suggests that it is possible to considerably reduce the aberrations with only minor perturbations of an ideal spherical lens. The proposed procedure can be applied for correction of aberrations of any optical system by modifying a single surface.

Place, publisher, year, edition, pages
Optical Society of America, 2016
Keywords
Ophthalmic optics and devices, Geometric optical design, Vision - acuity, Nonspherical lens design, Visual optics, modeling, Visual optics, refractive anomalies
National Category
Ophthalmology
Identifiers
urn:nbn:se:umu:diva-121173 (URN)10.1364/AO.55.004378 (DOI)000377050400017 ()27411190 (PubMedID)
External cooperation:
Available from: 2016-05-27 Created: 2016-05-27 Last updated: 2018-06-07Bibliographically approved
Schedin, S., Hallberg, P. & Behndig, A. (2016). Three-dimensional ray-tracing model for the study of advanced refractive errors in keratoconus. Applied Optics, 55(3), 507-514
Open this publication in new window or tab >>Three-dimensional ray-tracing model for the study of advanced refractive errors in keratoconus
2016 (English)In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 55, no 3, p. 507-514Article in journal (Refereed) Published
Abstract [en]

We propose a numerical three-dimensional (3D) ray-tracing model for the analysis of advanced corneal refractive errors. The 3D modeling was based on measured corneal elevation data by means of Scheimpflug photography. A mathematical description of the measured corneal surfaces from a keratoconus (KC) patient was used for the 3D ray tracing, based on Snell's law of refraction. A model of a commercial intraocular lens (IOL) was included in the analysis. By modifying the posterior IOL surface, it was shown that the imaging quality could be significantly improved. The RMS values were reduced by approximately 50% close to the retina, both for on-and off-axis geometries. The 3D ray-tracing model can constitute a basis for simulation of customized IOLs that are able to correct the advanced, irregular refractive errors in KC.

Place, publisher, year, edition, pages
Optical Society of America, 2016
National Category
Ophthalmology
Identifiers
urn:nbn:se:umu:diva-113596 (URN)10.1364/AO.55.000507 (DOI)000369055100038 ()26835925 (PubMedID)
Available from: 2015-12-21 Created: 2015-12-21 Last updated: 2018-06-07Bibliographically approved
Schedin, S. & Hassan, O. A. B. (2016). Work integrated learning model in relation to CDIO standards. Journal of Applied Research in Higher Education, 8(3), 278-286
Open this publication in new window or tab >>Work integrated learning model in relation to CDIO standards
2016 (English)In: Journal of Applied Research in Higher Education, ISSN 2050-7003, E-ISSN 1758-1184, Vol. 8, no 3, p. 278-286Article in journal (Refereed) Published
Abstract [en]

Purpose – The purpose of this paper is to develop a practical model of work integrated learning for undergraduate engineering students in relation to Conceiving-Designing-Implementing-Operating standards 7 (Integrated Learning Experiences) and 8 (Active Learning). Moreover, it is discussed the role of cultural-social perspective and peer learning in enhancing the developed learning model from a pedagogical point of view.

Design/methodology/approach – The model is based on an organized collaboration with the industrial partners in the surrounding geographic region. As a part of the collaboration, each participating student is guaranteed internships at a chosen company over the summer period. In the model, company-based projects are integrated with some of the study program courses. Moreover, the participating students are given a possibility to perform their final thesis at the chosen company.

Findings – A number of positive effects have been observed and documented as follows: first, the integrated learning improves the learning process for the students, where learning, knowledge and practice are integrated into the engineering curricula; second, the general quality of the study programs in the faculty has been developed and improved based on the professional skills as required by modern industrial companies; and third, the obtained advantage for the industrial partners has been to establish professional contacts with the students as well as the possibility to be acquainted with potential future employees.

Research limitations/implications – The feedback the authors received so far from the industrial partners has been positive. A detailed evaluation will be made at a later stage when more information is available. Practical implications – The developed learning model supports the expected learning outcomes, especially with regard to interpersonal skills, teamwork and communication. As a part of the collaboration, each participating student is guaranteed internships at a chosen company over the summer periods. The authors consider this collaboration as a “win-win situation” for the three parties involved in the learning model: the students, the university/faculty and the industrial partners.

Originality/value – Case study based on observations and evaluation of a developed learning model. 

Place, publisher, year, edition, pages
Emerald Group Publishing Limited, 2016
Keywords
Work integrated learning, Active Learning (CDIO standard 8), Integrated Learning Experiences (CDIO standard 7), Peer learning, Social-cultural theory of learning
National Category
Learning
Identifiers
urn:nbn:se:umu:diva-113674 (URN)10.1108/JARHE-11-2014-0104 (DOI)000386610000001 ()
Available from: 2015-12-22 Created: 2015-12-22 Last updated: 2018-06-07Bibliographically approved
Zakrisson, J., Schedin, S. & Andersson, M. (2015). Cell shape identification using digital holographic microscopy. Applied Optics, 54(24), 7442-7448
Open this publication in new window or tab >>Cell shape identification using digital holographic microscopy
2015 (English)In: Applied Optics, ISSN 1559-128X, E-ISSN 2155-3165, Vol. 54, no 24, p. 7442-7448Article in journal (Refereed) Published
Abstract [en]

We present a cost-effective, simple and fast digital holographic microscopy method based upon Rayleigh-Sommerfeld back propagation for identification of the geometrical shape of a cell. The method was tested using synthetic hologram images generated by ray-tracing software and from experimental images of semi-transparent spherical beads and living red blood cells. Our results show that by only using the real part of the back-reconstructed amplitude the proposed method can provide information of the geometrical shape of the object and at the same time accurately determine the axial position of the object under study. The proposed method can be used in flow chamber assays for pathophysiological studies where fast morphological changes of cells are studied in high numbers and at different heights.

Place, publisher, year, edition, pages
Optical Society of America, 2015
Keywords
Microscopy, Digital holography, Optical tweezers or optical manipulation
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:umu:diva-106588 (URN)10.1364/AO.54.007442 (DOI)000360190200039 ()26368783 (PubMedID)
Available from: 2015-07-22 Created: 2015-07-22 Last updated: 2018-06-07Bibliographically approved
Schedin, S. & Hassan, O. A. .. (2014). An Integrated Learning Model In Collaboration With Industrial Partners. In: Proceedings of the 10th International CDIO Conference, Universitat Politècnica de Catalunya, Barcelona, Spain, June 16-19, 2014: . Paper presented at 10th International CDIO Conference, Universitat Politècnica de Catalunya, Barcelona, Spain, June 16-19, 2014 (pp. 1-9).
Open this publication in new window or tab >>An Integrated Learning Model In Collaboration With Industrial Partners
2014 (English)In: Proceedings of the 10th International CDIO Conference, Universitat Politècnica de Catalunya, Barcelona, Spain, June 16-19, 2014, 2014, p. 1-9Conference paper, Published paper (Refereed)
Abstract [en]

We present a recently developed learning model of work integrated learning in the Bachelor programs in Mechanical Engineering as well as Electronic and Computer Engineering at Umeå University, Sweden. The model is based on an organized collaboration with our industrial partners in the surrounding geographic region. As a part of the collaboration, each participating student is guaranteed internships at a chosen company over the summer period.

In the model, company based projects are integrated with some of the study program courses. Moreover, the participating students are given a possibility to perform their final thesis at the chosen company. We consider this collaboration as a "win-win situation" for the three parties involved in the learning model: the students, the University/faculty and the industrial partners. A number of positive effects have been observed and documented as follows:

i) The integrated learning improves the learning process for the students, where learning, knowledge and practice are integrated into the engineering curricula.

ii) The general quality of the study programs in the faculty has been developed and improved based on the professional skills as required by modern industrial companies.

iii) The obtained advantage for the industrial partners has been to establish professional contacts with the students as well as the possibility to be acquainted with potential future employees.

We discuss the experiences of this learning model in relation to CDIO standard 7 (Integrated Learning Experiences) and 8 (Active Learning). It has been found that the company based projects promote interdisciplinary learning as well as fostering system building skills and personal communication skills. Moreover, the developed learning model supports the expected learning outcomes, especially with regard to interpersonal skills,  teamwork and communication. Finally, we investigate the learning theories that support the developed learning model from a pedagogical point of view.

Keywords
Work Integrated Learning, Integrated Learning Experiences (CDIO Standard 7), Active Learning (CDIO Standard 8)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:umu:diva-97720 (URN)84-697-2147-X (ISBN)978-84-697-2147-6 (ISBN)
Conference
10th International CDIO Conference, Universitat Politècnica de Catalunya, Barcelona, Spain, June 16-19, 2014
Available from: 2015-01-07 Created: 2015-01-07 Last updated: 2018-06-07Bibliographically approved
Hassan, O. & Schedin, S. (2013). Lärande, examination och bedömningssätt ur ett universitetsperspektiv. In: : . Paper presented at Den 11:e Universitetspedagogiska konferensen vid Umeå universitet 13-14 mars 2013 (pp. 36-40). Umeå: Umeå universitet
Open this publication in new window or tab >>Lärande, examination och bedömningssätt ur ett universitetsperspektiv
2013 (Swedish)Conference paper, Oral presentation with published abstract (Other academic)
Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2013
National Category
Engineering and Technology
Identifiers
urn:nbn:se:umu:diva-86273 (URN)
Conference
Den 11:e Universitetspedagogiska konferensen vid Umeå universitet 13-14 mars 2013
Available from: 2014-02-21 Created: 2014-02-21 Last updated: 2018-06-08Bibliographically approved
Schedin, S. & Hassan, O. (2013). Modell för arbetsintegrerat lärande på högskoleingenjörsutbildning. In: : . Paper presented at 4:e Utvecklingskonferensen för Sveriges ingenjörsutbildningar, Tekniska Högskolan vid Umeå universitet, 27 – 28 november 2013 (pp. 92-94). Umeå: Umeå universitet
Open this publication in new window or tab >>Modell för arbetsintegrerat lärande på högskoleingenjörsutbildning
2013 (Swedish)Conference paper, Published paper (Refereed)
Abstract [sv]

Vi beskriver en nyligen införd modell för arbetsintegrerat lärande (AIL) eller co-op (co-operative education) på högskoleingenjörsprogrammen i maskinteknik respektive elektro- och datorteknik. Modellen innebär att genom samverkan med företag i närregionen erbjuda och garantera ett antal programstudenter feriearbeten under två perioder, samt examensarbeten. I modellen ingår också företagsanknutna projektarbeten och en studieresa. Upplägget förväntas bidra till positiva effekter för samtliga parter, för utbildningsprogrammen, för samarbetsföretagen samt för studenterna. Vi förklarar även hur arbetsintegrerat lärande stöds av vedertagna lärandeteorier.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2013
Keywords
Arbetsintegrerat lärande, socio-kulturellt perspektiv, näringsliv, ingenjörsutbildning.
National Category
Engineering and Technology
Identifiers
urn:nbn:se:umu:diva-86270 (URN)
Conference
4:e Utvecklingskonferensen för Sveriges ingenjörsutbildningar, Tekniska Högskolan vid Umeå universitet, 27 – 28 november 2013
Available from: 2014-02-21 Created: 2014-02-21 Last updated: 2018-06-08Bibliographically approved
Hassan, O., Schedin, S. & Girhammar, U. A. (2012). Experimental Analysis of Composite Timbre-Concrete Wall Element. In: Proceedings of the 15th European conference on composite materials: . Paper presented at 15th European Conference on composite materials, June 24-28, 2012, Venice, Italy.
Open this publication in new window or tab >>Experimental Analysis of Composite Timbre-Concrete Wall Element
2012 (English)In: Proceedings of the 15th European conference on composite materials, 2012Conference paper, Published paper (Refereed)
Abstract [en]

The authors present an experimental and theoretical study on a composite or hybrid element used in residential and agricultural buildings. The composite wall element consists of timber studs connected to a concrete plate by means of nail plate shear connectors. Experimental results are presented and compared with an analytical model for partial composite action. A good agreement is obtained between the analytical and experimental results. Also, some suggestions to improve the design of the composite element are discussed.

Keywords
Timbre-concrete wall element, ultimate load design, service load design, nail- plates, bending and axial loading.
National Category
Building Technologies
Identifiers
urn:nbn:se:umu:diva-54578 (URN)978-88-88785-33-2 (ISBN)
Conference
15th European Conference on composite materials, June 24-28, 2012, Venice, Italy
Funder
EU, European Research Council
Available from: 2012-04-30 Created: 2012-04-30 Last updated: 2018-06-08Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-9031-4331

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