| 1. |
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| 2. |
- George, Julie, et al.
(författare)
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Comprehensive genomic profiles of small cell lung cancer
- 2015
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 524:7563, s. 47-U73
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Tidskriftsartikel (refereegranskat)abstract
- We have sequenced the genomes of 110 small cell lung cancers (SCLC), one of the deadliest human cancers. In nearly all the tumours analysed we found bi-allelic inactivation of TP53 and RB1, sometimes by complex genomic rearrangements. Two tumours with wild-type RB1 had evidence of chromothripsis leading to overexpression of cyclin D1 (encoded by the CCND1 gene), revealing an alternative mechanism of Rb1 deregulation. Thus, loss of the tumour suppressors TP53 and RB1 is obligatory in SCLC. We discovered somatic genomic rearrangements of TP73 that create an oncogenic version of this gene, TP73Dex2/3. In rare cases, SCLC tumours exhibited kinase gene mutations, providing a possible therapeutic opportunity for individual patients. Finally, we observed inactivating mutations in NOTCH family genes in 25% of human SCLC. Accordingly, activation of Notch signalling in a pre-clinical SCLC mouse model strikingly reduced the number of tumours and extended the survival of the mutant mice. Furthermore, neuroendocrine gene expression was abrogated by Notch activity in SCLC cells. This first comprehensive study of somatic genome alterations in SCLC uncovers several key biological processes and identifies candidate therapeutic targets in this highly lethal form of cancer.
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| 3. |
- Hesselkilde, Eva Zander, et al.
(författare)
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Longitudinal study of electrical, functional and structural remodelling in an equine model of atrial fibrillation
- 2019
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Ingår i: BMC Cardiovascular Disorders. - : Springer Science and Business Media LLC. - 1471-2261. ; 19:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Large animal models are important in atrial fibrillation (AF) research, as they can be used to study the pathophysiology of AF and new therapeutic approaches. Unlike other animal models, horses spontaneously develop AF and could therefore serve as a bona fide model in AF research. We therefore aimed to study the electrical, functional and structural remodelling caused by chronic AF in a horse model. Method: Nine female horses were included in the study, with six horses tachypaced into self-sustained AF and three that served as a time-matched sham-operated control group. Acceleration in atrial fibrillatory rate (AFR), changes in electrocardiographic and echocardiographic variables and response to medical treatment (flecainide 2 mg/kg) were recorded over a period of 2 months. At the end of the study, changes in ion channel expression and fibrosis were measured and compared between the two groups. Results: AFR increased from 299 ± 33 fibrillations per minute (fpm) to 376 ± 12 fpm (p < 0.05) and atrial function (active left atrial fractional area change) decreased significantly during the study (p < 0.05). No changes were observed in heart rate or ventricular function. The AF group had more atrial fibrosis compared to the control group (p < 0.05). No differences in ion channel expression were observed. Conclusion: Horses with induced AF show signs of atrial remodelling that are similar to humans and other animal models.
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| 4. |
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| 5. |
- Boustedt, Jonas, 1965-, et al.
(författare)
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Students' perceptions of the differences between formal and informal learning
- 2011
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Ingår i: ICER '11 Proceedings of the seventh international workshop on Computing education research. - New York, USA : Association for Computing Machinery (ACM). - 9781450308298 ; , s. 61-68
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Konferensbidrag (refereegranskat)abstract
- Research has shown that most learning in the workplace takes place outside of formal training and, given the swiftly changing nature of the field, computer science graduates more than most workers, need to be able to learn computing topics outside of organized classes.In this paper we discuss students' perceptions of the difference between formal and informal learning of computing topics, based on three datasets: essays collected from a technical writing course at a single university; the results of a brainstorming exercise conducted in the same course; and semi-structured interviews conducted at six institutions in three countries.The students report strengths and weaknesses in informal learning. On the one hand, they are motivated, can choose their level of learning, can be more flexible about how they learn, and often retain the material better. On the other hand, they perceive that they may miss important aspects of a topic, learn in an ad hoc way, and have difficulty assessing their learning.
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| 6. |
- Carstensen, Helena, et al.
(författare)
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Effects of dofetilide and ranolazine on atrial fibrillatory rate in a horse model of acutely induced atrial fibrillation
- 2019
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Ingår i: Journal of Cardiovascular Electrophysiology. - : Wiley. - 1045-3873 .- 1540-8167. ; 30:4, s. 596-606
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: The atrial fibrillatory rate is a potential biomarker in the study of antiarrhythmic drug effects on atrial fibrillation (AF). The purpose of this study was to evaluate whether dose-dependent changes in the atrial fibrillatory rate can be monitored on surface electrocardiography (ECG) following treatment with dofetilide, ranolazine, and a combination of the two in an acute model of AF in horses. Methods and Results: Eight horses were subjected to pacing-induced AF on 4 separate days. Saline (control), dofetilide, ranolazine, or a combination of dofetilide and ranolazine was administered in four incremental doses. Atrial fibrillatory activity was extracted from surface ECGs using spatiotemporal QRST cancellation. The mean atrial fibrillatory rate before drug infusion was 297 ± 27 fpm. Dofetilide reduced the atrial fibrillatory rate following the infusion of low doses (0.89 µg/kg, P < 0.05) and within 5 minutes preceding cardioversion (P < 0.05). Cardioversion with ranolazine was preceded by a reduction in the atrial fibrillatory rate in the last minute (P < 0.05). The combination of drugs reduced the atrial fibrillatory rate in a similar manner to dofetilide used alone. A trend toward a lower atrial fibrillatory rate before drug infusion was found among horses cardioverting on low doses of the drugs. Conclusion: The atrial fibrillatory rate derived from surface ECGs showed a difference in the mode of action on AF between dofetilide and ranolazine. Dofetilide reduced the atrial fibrillatory rate, whereas ranolazine displayed a cardioverting mechanism that was distinct from a slowing of the fibrillatory process.
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| 7. |
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| 8. |
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| 9. |
- Ericson, Thomas, et al.
(författare)
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Meteor Burst Communication without feedback
- 1995
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Ingår i: IEEE Transactions on Communications. - : IEEE. - 0090-6778 .- 1558-0857. ; 43:234, s. 851-857
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Tidskriftsartikel (refereegranskat)abstract
- Traditional meteor burst communication (MBC) systems are duplex (or half-duplex) systems. These systems provide the transmitter with feedback information for the detection of usable meteor trails. To achieve this feedback, a high power transmitter is required also at receive-only sites. In this paper, however, we discuss the application of channel coding to construct a true broadcast-type MBC system that allows for the simultaneous reception of messages at several receiving sites. Furthermore, MBC-systems without feedback allow for simple low power receivers that are impossible to to detect. Suitable codes, system performance and implementation complexity aspects are considered. Simulations with actual field trial data show that these systems are feasible and provide reliable, low-cost transmission of broadcast data.
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| 10. |
- Fang, Jun, et al.
(författare)
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Functional characterization of a multi-cancer risk locus on chr5p15.33 reveals regulation of TERT by ZNF148
- 2017
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Genome wide association studies (GWAS) have mapped multiple independent cancer susceptibility loci to chr5p15.33. Here, we show that fine-mapping of pancreatic and testicular cancer GWAS within one of these loci (Region 2 in CLPTM1L) focuses the signal to nine highly correlated SNPs. Of these, rs36115365-C associated with increased pancreatic and testicular but decreased lung cancer and melanoma risk, and exhibited preferred protein-binding and enhanced regulatory activity. Transcriptional gene silencing of this regulatory element repressed TERT expression in an allele-specific manner. Proteomic analysis identifies allele-preferred binding of Zinc finger protein 148 (ZNF148) to rs36115365-C, further supported by binding of purified recombinant ZNF148. Knockdown of ZNF148 results in reduced TERT expression, telomerase activity and telomere length. Our results indicate that the association with chr5p15.33-Region 2 may be explained by rs36115365, a variant influencing TERT expression via ZNF148 in a manner consistent with elevated TERT in carriers of the C allele.
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| 11. |
- McCartney, Robert, et al.
(författare)
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Computing students learning computing informally
- 2010
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Ingår i: Koli Calling '10. - New York, NY, USA : ACM Digital Library. - 9781450305204 ; , s. 43-48
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Konferensbidrag (refereegranskat)abstract
- In this paper we present background and early results from an investigation of how computing students learn computer science topics through informal means, that is, outside of organized classes. We provide some overall perspective by discussing the variety of research areas that fall under the general \informal learning" name. From there we propose specific research questions that concern what the students learn, what resources they bring to bear, what strategies they employ, and how they evaluate their progress. Preliminary results indicate that students primarily learn specific technologies, and that both their motivation and evaluation are closely tied to projects (at school, work, or home).
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| 12. |
- McCartney, Robert, et al.
(författare)
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Liminal Spaces and Learning Computing
- 2009
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Ingår i: European Journal of Engineering Education. - Abingdon : Taylor & Francis. - 0304-3797 .- 1469-5898. ; 34:4, s. 383-391
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Tidskriftsartikel (refereegranskat)abstract
- “Threshold concepts” are concepts that, among other things, transform the way a student looks at a discipline. Although the term “threshold” might suggest that the transformation occurs at a specific point in time, an “aha” moment, it seems more common (at least in computing) that a longer time period is required. This time period is referred to as the “liminal space.” In this paper, we summarise our findings concerning how computing students experience the liminal space and discuss how this might affect teaching. Most of our findings so far relate to software engineering. As similar liminal spaces likely occur in other engineering disciplines, these findings have relevance across engineering education.
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| 13. |
- McCartney, Robert, et al.
(författare)
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Why computing students learn on their own : motivation for self-directed learning of computing
- 2016
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Ingår i: ACM Transactions on Computing Education. - New York, NY, USA : Association for Computing Machinery (ACM). - 1946-6226. ; 16:1
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Tidskriftsartikel (refereegranskat)abstract
- In this article, we address the question of why computing students choose to learn computing topics on their own. A better understanding of why some students choose to learn on their own may help us to motivate other students to develop this important skill. In addition, it may help in curriculum design; if we need to leave some topics out of our expanding curriculum, a good choice might be those topics that students readily learn on their own.Based on a thematic analysis of 17 semistructured interviews, we found that computing students’ motivations for self-directed learning fall into four general themes: projects, social and peer interactions, joy of learning, and fear. Under these, we describe several more specific subthemes, illustrated in the words of the students.The project-related and social motivations are quite prominent. Although these motivations appear in theliterature, they received greater emphasis from our interviewees. Perhaps most characteristic of computingis the motivation to learn to complete some project, both projects done for fun and projects required for schoolor work.
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| 14. |
- Moström, Jan-Erik, et al.
(författare)
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Computer Science Student Transformations : Changes and Causes
- 2009
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Ingår i: ITiCSE'09. - New York : ACM. ; , s. 181-185
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Konferensbidrag (refereegranskat)abstract
- We examine the transformations experienced by students during their study of computing. These transformations led to changes in the students’ perception of computing and in their behavior, confidence, and sense of identity as computing professionals. We discuss these transformations, their causes, and implications for the learning and teaching of computer science.
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| 15. |
- Moström, Jan Erik, et al.
(författare)
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Computer science student transformations : changes and causes
- 2009
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Ingår i: ITiCSE 2009. - New York, NY, USA : ACM Digital Library. - 9781605583815 ; , s. 181-185
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Konferensbidrag (refereegranskat)abstract
- We examine the transformations experienced by students during their study of computing. These transformations led to changes in the students' perceptions of computer science, in their sense of identity as computer scientists, their behavior and their confidence. The changes are caused by learning or using particular concepts, and often associated with writing computer programs, learning new programming languages, or interacting with peers.
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| 16. |
- Moström, Jan Erik, et al.
(författare)
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Computer Science Student Transformations : Changes and Causes
- 2009
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Ingår i: SIGCSE Bulletin inroads. - : Association for Computing Machinery (ACM). - 0097-8418. ; 41:3, s. 181-185
-
Tidskriftsartikel (refereegranskat)abstract
- We examine the transformations experienced by students during their study of computing. These transformations led to changes in the students' perceptions of computer science, in their sense of identity as computer scientists, their behavior and their confidence. The changes are caused by learning or using particular concepts, and often associated with writing computer programs, learning new programming languages, or interacting with peers.
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| 17. |
- Moström, Jan Erik, 1962-, et al.
(författare)
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Concrete examples of abstraction as manifested in students’ transformative experiences
- 2008
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Ingår i: ICER '08. - New York : ACM. - 9781605582160 ; , s. 125-136
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Konferensbidrag (refereegranskat)abstract
- This paper examines transformational learning experiences of computing students as a way to better understand threshold concepts in computing. From empirical evidence we found that students often describe transformative experiences as learning situations in which they were led to use various kinds of abstraction, for example modularity, data abstraction, inheritance, polymorphism, reuse, design patterns, and complexity. Some students describe an abstract concept as coming first, and then needing to be made concrete though application; others describe transformations in which they learn the advantages of these abstract concepts from their experience of not using them.Abstraction is certainly of central importance in computer science. It appears, however, from our students’ descriptions of transformative experiences, that abstraction per se is not a threshold, but that particular concepts in which abstraction is paramount exhibit the characteristics of threshold concepts.
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| 18. |
- Raj, Akanksha, et al.
(författare)
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Lubrication synergy : Mixture of hyaluronan and dipalmitoylphosphatidylcholine (DPPC) vesicles
- 2017
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Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797 .- 1095-7103. ; 488, s. 225-233
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Tidskriftsartikel (refereegranskat)abstract
- Phospholipids and hyaluronan have been implied to fulfil important roles in synovial joint lubrication. Since both components are present in synovial fluid, self-assembly structures formed by them should also be present. We demonstrate by small angle X-ray scattering that hyaluronan associates with the outer shell of dipalmitoylphophatidylcholine (DPPC) vesicles in bulk solution. Further, we follow adsorption to silica from mixed hyaluronan/DPPC vesicle solution by Quartz Crystal Microbalance with Dissipation measurements. Atomic Force Microscope imaging visualises the adsorbed layer structure consisting of non-homogeneous phospholipid bilayer with hyaluronan/DPPC aggregates on top. The presence of these aggregates generates a long-range repulsive surface force as two such surfaces are brought together. However, the aggregates are easily deformed, partly rearranged into multilayer structures and partly removed from between the surfaces under high loads. These layers offer very low friction coefficient (<0.01), high load bearing capacity (≈23 MPa), and self-healing ability. Surface bound DPPC/hyaluronan aggregates provide a means for accumulation of lubricating DPPC molecules on sliding surfaces.
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| 19. |
- Sanders, Kate, et al.
(författare)
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Student understanding of object-oriented programming as expressed in concept maps
- 2008
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Ingår i: SIGCSE Bulletin inroads. - : Association for Computing Machinery (ACM). - 0097-8418. ; 40:1, s. 332-336
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present the results of an experiment in which we sought to elicit students’ understanding of objectoriented (OO) concepts using concept maps. Our analysis confirmed earlier research indicating that students do not have a firm grasp on the distinction between “class” and “instance.” Unlike earlier research, we found that our students generally connect classes with both data and behavior. Students rarely included any mention of the hardware/software context of programs, their users, or their real-world domains. Students do mention inheritance, but not encapsulation or abstraction. And the picture they draw of OO is a static one: we found nothing that could be construed as referring to interaction among objects in a program. We then discuss the implications for teaching introductory OO programming.
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| 20. |
- Sanders, Kate, et al.
(författare)
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Student understanding of object-oriented programming as expressed in concept maps
- 2008
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Ingår i: SIGCSE ’08. - New York, NY, USA : ACM. - 9781595937995 ; , s. 332-336
-
Konferensbidrag (refereegranskat)abstract
- In this paper, we present the results of an experiment in which we sought to elicit students’ understanding of object-oriented (OO) concepts using concept maps. Our analysis confirmed earlier research indicating that students do not have a firm grasp on the distinction between “class” and “instance.” Unlike earlier research, we found that our students generally connect classes with both data and behavior. Students rarely included any mention of the hardware/software context of programs, their users, or their real-world domains. Students do mention inheritance, but not encapsulation or abstraction. And the picture they draw of OO is a static one: we found nothing that could be construed as referring to interaction among ob jects in a program. We then discuss the implications for teaching introductory OO programming.
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| 21. |
- Sanders, Kate, et al.
(författare)
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Threshold concepts and threshold skills in computing
- 2012
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Ingår i: ICER '12. - New York, NY, USA : ACM Digital Library. - 9781450316040 ; , s. 23-30
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Konferensbidrag (refereegranskat)abstract
- Threshold concepts can be used to both organize disciplinary knowledge and explain why students have difficulties at certain points in the curriculum. Threshold concepts transform a student's view of the discipline; before being learned, they can block a student's progress. In this paper, we propose that in computing, skills, in addition to concepts, can sometimes be thresholds. Some students report finding skills more difficult than concepts. We discuss some computing skills that may be thresholds and compare threshold skills and threshold concepts.
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| 22. |
- Simonsson, Bengt, et al.
(författare)
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Roquinimex (Linomide) vs placebo in AML after autologous bone marrow transplantation
- 2000
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Ingår i: Bone Marrow Transplantation. - 0268-3369 .- 1476-5365. ; 25:11, s. 1121-1127
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Tidskriftsartikel (refereegranskat)abstract
- Roquinimex, Linomide, a quinoline derivative with pleiotropic immunomodulatory activity, has previously been shown to enhance natural killer (NK) cell number and activity after ABMT in patients with AML. In this study 278 AML patients in remission were randomized to receive Roquinimex 0.2 mg/kg body weight or placebo twice weekly for 2 years following ABMT. Out of 139 patients in each group, 109 Roquinimex patients and 108 placebo patients were in their first CR. Median age at inclusion was 41 years for Roquinimex patients and 39 years for placebo patients. Twelve patients in each group had their marrow purged prior to reinfusion. Relapse and death were study endpoints. Surviving patients were followed for 2.6 to 6. 9 years. The total number of relapses was 60 in the Roquinimex group and 63 in the placebo group (not significant). Leukemia-free and overall survivals were similar in the two groups. Recovery of platelet counts was significantly delayed in the Roquinimex group as compared to placebo. No other significant differences regarding toxicity parameters were recorded. In conclusion, previous findings on NK cells could not be confirmed and the study showed no benefit for Roquinimex over placebo regarding relapse or survival following ABMT for AML in remission.
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| 23. |
- Thomas, Lynda, et al.
(författare)
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A broader threshold : Including skills as well as concepts in computing education
- 2014
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Ingår i: Threshold Concepts: From personal practice to communities of practice. - Cork, Ireland : NAIRTL. - 9781906642594 ; , s. 154-158
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Konferensbidrag (refereegranskat)abstract
- We propose ‘threshold skills’ as a complement to threshold concepts. The definition of threshold concepts assumes that theoretical knowledge is paramount: gaining the understanding of particular concepts irreversibly transforms the learners.Mastering computing, like many disciplines, however, requires learning a combination of concepts and skills. Mathematicians learn to do proofs, musicians learn to play their instruments, and martial artists learn to make moves by doing these activities, not just intellectually understanding them. We propose some characteristics for threshold skills and outline implications for teaching and for future work.
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| 24. |
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| 25. |
- Thomas, Lynda, et al.
(författare)
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Graduating students' designs - Through a phenomenographic lens
- 2014
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Ingår i: ICER 2014. - New York, NY, USA : ACM Digital Library. - 9781450327558 ; , s. 91-98
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Konferensbidrag (refereegranskat)abstract
- We expand upon previous research that looked at the question: \Can graduating students design software systems?" Specifically we want to examine students' understanding of the phenomenon\produce a design." What does this instruction mean to them? In order to investigate student understandings, we examined their designs using a phenomenographic approach. Our outcome space includes six understandings: (0) the design a layman might produce; (1) a design with some formal notation; (2) a design that uses formal notations to express the static relationships among the parts; (3) a design that uses formal notation to express sequential (dynamic) information, but does not relate that to the static system parts; (4) a design that includes and relates multiple artifacts, both static and dynamic; and (5) a design that relaxes the notations and includes only essential artifacts. The last understanding was found only in our expert's design, and we do not expect it from undergraduates.
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| 26. |
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| 27. |
- Thomas, Lynda, et al.
(författare)
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In the liminal space : software design as a threshold skill
- 2017
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Ingår i: Practice and Evidence of the Scholarship of Teaching and Learning in Higher Education. - 1750-8428. ; 12:2, s. 333-351
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Tidskriftsartikel (refereegranskat)abstract
- In previous work we proposed the idea of ‘threshold skills’ as a complement to threshold concepts. The definition of threshold concepts assumes that theoretical knowledge is paramount: gaining the understanding of particular concepts irreversibly transforms the learners. We noted, however, that mastering computing, like many disciplines, requires learning a combination of concepts and skills, and we suggested that this required further investigation. In this paper we examine the activity of designing software as a possible example of such a threshold skill. We looked at 35 software designs collected from students nearing graduation in computing courses, and see many of the characteristics of threshold skill and also of students being in liminal space. A close examination of the students’ designs leads to some useful implications for teaching this fundamental activity.
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| 28. |
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| 29. |
- Thomas, Lynda, et al.
(författare)
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Student software designs at the undergraduate midpoint
- 2017
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Ingår i: ITiCSE '17. - New York, NY, USA : Association for Computing Machinery (ACM). - 9781450347044 ; , s. 34-39
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Konferensbidrag (refereegranskat)abstract
- We replicate a study and extend previous research that examined graduating students' achievement and understanding when asked to "produce a design". In this paper, we examine software designs produced by students at an earlier stage in their undergraduate studies -- the midpoint. We were looking for characteristics of the development of skill at software design as students progress through the curriculum. These students did about as well as graduating students from the same institution in terms of the quality of their software designs, although they failed to produce as many complete designs. In addition to attributes uncovered in previous research, a new design attribute was noticed -- meaningful links between static components. We raise the question of where GUI designs fit in the area of software design.We were also looking for evidence that mastering software design is a Threshold [8] that could be seen in development in this earlier cohort. There was some evidence for this, and the identified design attributes provide an indication of the sub-skills that need to be mastered.The paper concludes with some implications for the teaching of software design.
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| 30. |
- Thomas, Lynda, et al.
(författare)
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Threshold concepts in computer science : an ongoing empirical investigation
- 2010
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Ingår i: Threshold concepts and transformational learning. - Rotterdam : Sense Publishers. - 9789460912054 - 9789460912061 - 9789460912078 ; , s. 241-258
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- The chapter describes an ongoing multi-national, multi-institutional project aimed at empirically identifying threshold concepts in Computer Science, and describing students’ experiences of learning these concepts.
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| 31. |
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| 32. |
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| 33. |
- Wang, Min, et al.
(författare)
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The effect of temperature on supported dipalmitoylphosphatidylcholine (DPPC) bilayers : Structure and lubrication performance
- 2015
-
Ingår i: Journal of Colloid and Interface Science. - : Elsevier BV. - 0021-9797 .- 1095-7103. ; 445, s. 84-92
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Tidskriftsartikel (refereegranskat)abstract
- Phospholipids fulfill an important role in joint lubrication. They, together with hyaluronan and glycoproteins, are the biolubricants that sustain low friction between cartilage surfaces bathed in synovial fluid. In this work we have investigated how the friction force and load bearing capacity of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) bilayers on silica surfaces are affected by temperature, covering the temperature range 25–52 °C. Friction forces have been determined utilizing the AFM colloidal probe technique, which showed that DPPC bilayers are able to provide low friction forces over the whole temperature interval. However, the load bearing capacity is improved at higher temperatures. We interpret this finding as being a consequence of lower rigidity and higher self-healing capacity of the DPPC bilayer in the liquid disordered state compared to the gel state. The corresponding structure of solid supported DPPC bilayers at the silica–liquid interface has been followed using X-ray reflectivity measurements, which suggests that the DPPC bilayer is in the gel phase at 25 °C and 39 °C and in the liquid disordered state at 55 °C. Well-defined bilayer structures were observed for both phases. The deposited DPPC bilayers were also imaged using AFM PeakForce Tapping mode, and these measurements indicated a less homogeneous layer at temperatures below 37 °C.
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| 34. |
- Wieland, D. C. Florian, et al.
(författare)
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Structure of DPPC-hyaluronan interfacial layers - effects of molecular weight and ion composition
- 2016
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Ingår i: Soft Matter. - : Royal Society of Chemistry. - 1744-683X .- 1744-6848. ; 12:3, s. 729-740
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Tidskriftsartikel (refereegranskat)abstract
- Hyaluronan and phospholipids play an important role in lubrication in articular joints and provide in combination with glycoproteins exceptionally low friction coefficients. We have investigated the structural organization of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) Langmuir layers at the solution-air interface at different length scales with respect to the adsorption of hyaluronan (HA). This allows us to assemble a comprehensive picture of the adsorption and the resulting structures, and how they are affected by the molecular weight of HA and the presence of calcium ions. Brewster angle microscopy and grazing incident diffraction were used to determine the lateral structure at the micro- and macro scale. The data reveals an influence of HA on both the macro and micro structure of the DPPC Langmuir layer, and that the strength of this effect increases with decreasing molecular weight of HA and in presence of calcium ions. Furthermore, from X-ray reflectivity measurements we conclude that HA adsorbs to the hydrophilic part of DPPC, but data also suggest that two types of interfacial structures are formed at the interface. We argue that hydrophobic forces and electrostatic interactions play important rules for the association between DPPC and HA. Surface pressure area isotherms were used to determine the influence of HA on the phase behavior of DPPC while electrophoretic mobility measurements were used to gain insight into the binding of calcium ions to DPPC vesicles and hyaluronan.
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| 35. |
- Wieland, D. C. Florian, et al.
(författare)
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Studying solutions at high shear rates : A dedicated microfluidics setup
- 2016
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Ingår i: Journal of Synchrotron Radiation. - : International Union of Crystallography. - 0909-0495 .- 1600-5775. ; 23:2, s. 480-486
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Tidskriftsartikel (refereegranskat)abstract
- The development of a dedicated small-angle X-ray scattering setup for the investigation of complex fluids at different controlled shear conditions is reported. The setup utilizes a microfluidics chip with a narrowing channel. As a consequence, a shear gradient is generated within the channel and the effect of shear rate on structure and interactions is mapped spatially. In a first experiment small-angle X-ray scattering is utilized to investigate highly concentrated protein solutions up to a shear rate of 300000 s-1. These data demonstrate that equilibrium clusters of lysozyme are destabilized at high shear rates.
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| 36. |
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| 37. |
- Zander, Carol, et al.
(författare)
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Copying Can Be Good : How Instructors Use Imitation in Teaching Programming
- 2019
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Ingår i: Proceedings of the 2019 ACM Conference on Innovation and Technology in Computer Science Education (ITICSE '19). - New York, NY, USA : ACM Digital Library. - 9781450368957 ; , s. 450-456
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Konferensbidrag (refereegranskat)abstract
- Students' "copying" is often considered negatively. In this paper, we explore the ways in which copying and imitation are used positively by computing instructors in their teaching. We found that instructors expect their students to use these strategies in many different contexts and at many different levels.
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| 38. |
- Zander, Carol, et al.
(författare)
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Copying Can Be Good : How Students View Imitation as a Tool in Learning to Program
- 2020
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Ingår i: 2020 IEEE Frontiers in Education Conference (FIE). - : Institute of Electrical and Electronics Engineers (IEEE). - 9781728189611 - 9781728189628
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Konferensbidrag (refereegranskat)abstract
- Student ‘copying’ is often considered negatively as thoughts of plagiarism come to mind. Previously, we investigated the ways that instructors expect to use copying and imitation positively in their teaching. In this paper, we follow up that study by focusing on the student perspective and explore the ways in which students see copying and imitating as positive tools in learning to program (both at an introductory level and through more advanced learning of algorithms, etc.).In a qualitative research study, using semi-structured interviews, students were asked about how they use copying positively - their goals when they copy, how they go about it, how they view the experience of copying, and results beyond simply fulfilling their immediate goals.When comparing student results with the previous study, it was noted that there is some level of agreement between instructors and students about how copying can be useful for learning to program. There is also some degree of mismatch between instructor and student views. Students did not report imitating instructors’ approaches to learning and sometimes were unsure about whether they were supposed to copy the materials that they were given. This leads to some teaching suggestions in terms of instructors being more explicit in their attitude to this type of ‘legitimate’ copying and imitation.
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| 39. |
- Zander, Carol, et al.
(författare)
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Pseudocode : scaffolding student object-oriented software designs
- 2023
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Ingår i: Koli calling '23: Proceedings of the 23rd Koli calling international conference on computing education research. - : Association for Computing Machinery. - 9798400716539
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Konferensbidrag (refereegranskat)abstract
- This work investigates how students, given a partial software design consisting of a class diagram and high-level use cases, translate the use cases into pseudocode. We gathered pseudocode solutions in March 2023 from intermediate undergraduate students in their fourth programming course (covering a combination of data structures, object-oriented programming, and some discrete mathematics) at a four-year public university in the United States. We are interested in pseudocode as a way of helping students move from static information about an object-oriented problem to a design that captures dynamic behaviour that can then be implemented in code.
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| 40. |
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| 41. |
- Zander, Carol, et al.
(författare)
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Self-directed learning : Stories from industry
- 2012
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Ingår i: Koli Calling '12. - New York, NY, USA : ACM Digital Library. - 9781450317955 ; , s. 111-117
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Konferensbidrag (refereegranskat)abstract
- We report preliminary results from an ongoing investigation of how computing professionals perceive and value selfdirected learning, based on a qualitative analysis of interviews with ten computing professionals. The professionals expect that future colleagues will have a well-developed ability to learn on their own. They indicate that professionals use a range of resources, strategies, and collaborators to help them learn. They find their work-related self-directed learning enjoyable, expressing a sense of confidence and pride; yet they often also find it to be a stressful never-ending process. Copyright 2012 ACM.
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| 42. |
- Zander, Carol, et al.
(författare)
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Student transformations : are they computer scientists yet?
- 2009
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Ingår i: ICER '09. - New York : ACM. - 9781605586151 ; , s. 129-140
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Konferensbidrag (refereegranskat)abstract
- We examine the changes in the ways computing students view their field as they learn, as reported by the students themselves in short written biographies. In many ways, these changes result in students thinking and acting more like computer scientists and identifying more with the computing community. Most of the changes are associated with programming and software engineering, rather than theoretical computer science, however.
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| 43. |
- Zander, PO, et al.
(författare)
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Investigating Values in CSCL Design
- 2005
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Ingår i: Lund on Informatics. - 9147076348 ; , s. 196-218
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 44. |
- Zander, Thomas, et al.
(författare)
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Influence of high hydrostatic pressure on solid supported DPPC bilayers with hyaluronan in the presence of Ca2+ ions
- 2019
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Ingår i: Soft Matter. - : Royal Society of Chemistry. - 1744-683X .- 1744-6848. ; 15:36, s. 7295-7304
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Tidskriftsartikel (refereegranskat)abstract
- The molecular mechanisms responsible for outstanding lubrication of natural systems, like articular joints, have been the focus of scientific research for several decades. One essential aspect is the lubrication under pressure, where it is important to understand how the lubricating entities adapt under dynamic working conditions in order to fulfill their function. We made a structural investigation of a model system consisting of two of the molecules present at the cartilage interface, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine and hyaluronan, at high hydrostatic pressure. Phospholipid layers are found at the cartilage surfaces and are able to considerably reduce friction. Their behavior under load and varied solution conditions is important as pressures of 180 bar are encountered during daily life activities. We focus on how divalent ions, like Ca2+, affect the interaction between DPPC and hyaluronan, as other investigations have indicated that calcium ions influence their interaction. It could be shown that already low amounts of Ca2+ strongly influence the interaction of hyaluronan with DPPC. Our results suggest that the calcium ions increase the amount of adsorbed hyaluronan indicating an increased electrostatic interaction. Most importantly, we observe a modification of the DPPC phase diagram as hyaluronan absorbs to the bilayer which results in an Lα-like structure at low temperatures and a decoupling of the leaflets forming an asymmetric bilayer structure.
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| 45. |
- Zander, Thomas, et al.
(författare)
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Influence of the Molecular Weight and the Presence of Calcium Ions on the Molecular Interaction of Hyaluronan and DPPC
- 2020
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Ingår i: Molecules. - : NLM (Medline). - 1431-5157 .- 1420-3049. ; 25:17
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Tidskriftsartikel (refereegranskat)abstract
- Hyaluronan is an essential physiological bio macromolecule with different functions. One prominent area is the synovial fluid which exhibits remarkable lubrication properties. However, the synovial fluid is a multi-component system where different macromolecules interact in a synergetic fashion. Within this study we focus on the interaction of hyaluronan and phospholipids, which are thought to play a key role for lubrication. We investigate how the interactions and the association structures formed by hyaluronan (HA) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) are influenced by the molecular weight of the bio polymer and the ionic composition of the solution. We combine techniques allowing us to investigate the phase behavior of lipids (differential scanning calorimetry, zeta potential and electrophoretic mobility) with structural investigation (dynamic light scattering, small angle scattering) and theoretical simulations (molecular dynamics). The interaction of hyaluronan and phospholipids depends on the molecular weight, where hyaluronan with lower molecular weight has the strongest interaction. Furthermore, the interaction is increased by the presence of calcium ions. Our simulations show that calcium ions are located close to the carboxylate groups of HA and, by this, reduce the number of formed hydrogen bonds between HA and DPPC. The observed change in the DPPC phase behavior can be attributed to a local charge inversion by calcium ions binding to the carboxylate groups as the binding distribution of hyaluronan and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine is not changed.
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| 46. |
- Zander, Thomas, et al.
(författare)
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The influence of hyaluronan on the structure of a DPPC-bilayer under high pressures
- 2016
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Ingår i: Colloids and Surfaces B. - : Elsevier. - 0927-7765 .- 1873-4367. ; 142, s. 230-238
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Tidskriftsartikel (refereegranskat)abstract
- The superior lubrication properties of synovial joints have inspired many studies aiming at uncovering the molecular mechanisms which give rise to low friction and wear. However, the mechanisms are not fully understood yet, and, in particular, it has not been elucidated how the biolubricants present at the interface of cartilage respond to high pressures, which arise during high loads of joints. In this study we utilize a simple model system composed of two biomolecules that have been implied as being important for joint lubrication. It consists of a solid supported dipalmitoylphosphatidylcholin (DPPC) bilayer, which was formed via vesicles fusion on a flat Si wafer, and the anionic polysaccharide hyaluronan (HA). We first characterized the structure of the HA layer that adsorbed to the DPPC bilayers at ambient pressure and different temperatures using X-ray reflectivity (XRR) measurements. Next, XRR was utilized to evaluate the response of the system to high hydrostatic pressures, up to 2 kbar (200 MPa), at three different temperatures. By means of fluorescence microscopy images the distribution of DPPC and HA on the surface was visualized. Our data suggest that HA adsorbs to the headgroup region that is oriented towards the water side of the supported bilayer. Phase transitions of the bilayer in response to temperature and pressure changes were also observed in presence and absence of HA. Our results reveal a higher stability against high hydrostatic pressures for DPPC/HA composite layers compared to that of the DPPC bilayer in absence of HA.
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| 47. |
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| 48. |
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