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- Björklund, Erik, et al.
(author)
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Postdischarge major bleeding, myocardial infarction, and mortality risk after coronary artery bypass grafting
- 2023
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In: HEART. - 1355-6037 .- 1468-201X.
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Journal article (peer-reviewed)abstract
- Objective To investigate the incidence and mortality risk associated with postdischarge major bleeding after coronary artery bypass grafting (CABG), and relate this to the incidence of, and mortality risk from, postdischarge myocardial infarction.Methods All patients undergoing first-time isolated CABG in Sweden in 2006-2017 and surviving 14 days after hospital discharge were included in a cohort study. Individual patient data from the SWEDEHEART Registry and five other mandatory nationwide registries were merged. Piecewise Cox proportional hazards models were used to investigate associations between major bleeding, defined as hospitalisation for bleeding, with subsequent mortality risk. Similar Cox proportional hazards models were used to investigate the association between postdischarge myocardial infarction and mortality risk.Results Among 36 633 patients, 2429 (6.6%) had a major bleeding event and 2231 (6.1%) had a myocardial infarction. Median follow-up was 6.0 (range 0-11) years. Major bleeding was associated with higher mortality risk <30 days (adjusted HR (aHR)=20.2 (95% CI 17.3 to 23.5)), 30-365 days (aHR=3.8 (95% CI 3.4 to 4.3)) and >365 days (aHR=1.8 (95% CI 1.7 to 2.0)) after the event. Myocardial infarction was associated with higher mortality risk <30 days (aHR=20.0 (95% CI 16.7 to 23.8)), 30-365 days (aHR=4.1 (95% CI 3.6 to 4.8)) and >365 days (aHR=1.8 (95% CI 1.7 to 2.0)) after the event.Conclusions The increase in mortality risk associated with a postdischarge major bleeding after CABG is substantial and is similar to the mortality risk associated with a postdischarge myocardial infarction.
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| 3. |
- Bälter, Olle, et al.
(author)
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The effect of short formative diagnostic web quizzes with minimal feedback
- 2013
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In: Computers and education. - : Elsevier. - 0360-1315 .- 1873-782X. ; 60:1, s. 234-242
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Journal article (peer-reviewed)abstract
- To help students gauge their understanding of basic concepts and encourage good study habits, we administered short online quizzes that use generic questions in the crucial first few weeks of a course. The purpose of the study was to investigate whether the combination of these web quizzes with generic questions with only binary feedback (right or wrong) would be beneficial for students' learning. We implemented these quizzes in three classes in two different subjects at two different universities, one in Sweden and one in the USA. The students' views on the quizzes' effect on their learning was investigated with surveys and interviews.Almost all students appreciated having these quizzes and 38% of them changed their view on how much they knew of the material covered in the course. Furthermore, over 20% of the students reported altering their study habits as a consequence, in particular studying harder or earlier.In conclusion, this study indicated that short quizzes using generic questions with limited correct/incorrect feedback on each question, have positive effects when administered early in courses.The combination of generic questions and short quizzes could be of value for those contemplating automatic formative assessment, particularly if there is some hesitation with respect to the resources needed for constructing and validating the automatic feedback.
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| 4. |
- Crescenzi, P., et al.
(author)
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From theory to practice : NP-completeness for every CS student
- 2013
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In: ITiCSE '13 Proceedings of the 18th ACM conference on Innovation and technology in computer science education. - New York, NY, USA : Association for Computing Machinery (ACM). - 9781450320788 ; , s. 16-21
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Conference paper (peer-reviewed)abstract
- NP-completeness is one of the most central concepts in computer science, and has been extensively applied in many diverse application areas. Despite this, students have problems grasping the concept and, more specifically, applying it to new problems. Independently, we have identified these problems at our universities in different countries and cultures. In an action research approach we have modified our courses and studied the effects. We here present some promising results. Our approach is mainly based on the idea of making more evident the fact that proving a new NP-completeness result is not at all different from designing a new algorithm. Based on this idea, we used tools typically used to teach algorithms (such as automatic program assessment and algorithm visualization systems), accompanied by other activities mainly devoted to augmenting the motivation to study computational complexity and forcing students to think and adopt a standpoint.
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| 5. |
- Enström, Emma, et al.
(author)
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Computer Lab Work on Theory
- 2010
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In: ITICSE 2010. - NEW YORK : ASSOC COMPUTING MACHINERY. - 9781605588209 ; , s. 93-97
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Conference paper (peer-reviewed)abstract
- This paper describes an attempt to introduce computer lab exercises on NP-completeness proofs in a class already containing computer lab exercises on algorithms and data structures. In the article we are interested in the answer of the following question: Can the students feel that their understanding of theoretical computer science is improved by performing a computer lab exercise on the subject? The class is mandatory for students in a computer science program, and is taken by about 130 students each year. Theory of NP-completeness proofs with reductions has previous years been examined on an individual assignment with written solutions handed in and later explained orally by the student to a teacher. The new assignment is performed as a computer lab exercise where students are working in small groups of two. This exercise is placed before the individual assignment, and is examined first by running automated test cases and later by an oral presentation in lab to a teacher. An improvement can be observed of the students' average results since the new assignment was introduced. This is not enough to prove the benefit of using the new assignment. However, the responses to questionnaires at course evaluations show that almost all students think that the assignment redly gave them better understanding of polynomial reductions in NP completeness proofs. The students' result on the new assignment corresponds closely to their results on the following individual assignment. Seemingly, the new assignment predicts accurately who is going to pass the following assignment.
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| 6. |
- Enström, Emma
(author)
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Dynamic programming - structure, difficulties and teaching
- 2013
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In: 2013 IEEE Frontiers in Education Conference. - New York : IEEE. - 9781467352611 ; , s. 1857-1863
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Conference paper (peer-reviewed)abstract
- In this paper we describe action research on our third year Algorithms, Data structures and Complexity course, in which students have considered dynamic programming hard in comparison to the other topics. Attempting to amend this, we wanted to know which difficulties the students encountered, where they gained their knowledge, and which tasks they were most certain that they could perform after the course. Such work resides in the didactics of the subject taught, but the general methods of attacking perceived difficulties in a course can be tried on any course. We identified subtasks that could be taught separately, and adapted the lectures to Pattern Oriented Instruction in order to help students cope with the cognitive complexity of solving problems using dynamic programming. For this, we prepared new clicker questions, visualisations and a lab assignment. We also constructed self-efficacy items on the course goals for dynamic programming, and administered them before and after the teaching and learning activities. Among the self-efficacy items, determining the evaluation order and solving a problem with dynamic programming with no hints had the lowest score after the course. As for the activities, arguing correctness of a solution was something many students claimed that they did not learn anywhere. Students considered the lab exercise most useful, but they also learned a lot from the other activities.
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| 7. |
- Enström, Emma, et al.
(author)
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Five Years with Kattis – Using an Automated Assessment System in Teaching
- 2011
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In: 2011 Frontiers in Education Conference (FIE). - New York : IEEE. - 9781612844695
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Conference paper (peer-reviewed)abstract
- Automated assessment systems have been employed in computer science (CS) courses at a number of different universities. Such systems are especially applicable in teaching algorithmic problem solving since they can automatically test if an algorithm has been correctly implemented, i.e., that it performs its specified function on a set of inputs. Being able to implement algorithms that work correctly is a crucial skill for CS students in their professional role, but it can be difficult to convey the importance of this in a classroom situation. Programming and problem solving education supported by automated grading has been used since 2002 at our department. We study, using action research methodology, different strategies for deploying automated assessment systems in CS courses. Towards this end, we have developed an automated assessment system and both introduced it into existing courses and constructed new courses structured around it. Our primary data sources for evaluation consists of course evaluations, statistics on students' submitted solutions, and experience teaching the courses. Authors of this paper have been participating in teaching all of the courses mentioned here.
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| 8. |
- Enström, Emma, et al.
(author)
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Iteratively Intervening with the “Most Difficult” Topics of an Algorithms and Complexity Course
- 2017
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In: ACM Transactions on Computing Education. - : ACM Digital Library. - 1946-6226. ; 17:1
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Journal article (peer-reviewed)abstract
- When compared to earlier programming and data structure experiences that our students might have, the perspective changes on computers and programming when introducing theoretical computer science into the picture. Underlying computational models need to be addressed, and mathematical tools employed, to understand the quality criteria of theoretical computer science. Focus shifts from doing to proving. Over several years, we have tried to make this perspective transition smoother for the students of a third-year mandatory algorithms, data structures, and computational complexity course. The concepts receiving extra attention in this work are NP-completeness, one of the most central concepts in computer science, and dynamic programming, an algorithm construction method that is powerful but somewhat unintuitive for some students.The major difficulties that we attribute to NP-completeness are that the tasks look similar but have a different purpose than in algorithm construction exercises. Students do not immediately see the usefulness of the concept, and hence motivation could be one issue. One line of attacking NP-completeness has been to emphasize its algorithmic aspects using typical tools for teaching algorithms.Some potential difficulties associated with dynamic programming are that the method is based on a known difficult concept—recursion—and that there are many ingredients in a dynamic programming solution to a problem.For both dynamic programming and NP-completeness, we have invented several new activities and structured the teaching differently, forcing students to think and adopt a standpoint, and practice the concepts in programming assignments. Student surveys show that these activities are appreciated by the students, and our evaluations indicate that they have positive effects on learning. We believe that these activities could be useful in any similar course.The approach to improving the course is action research, and the evaluation has been done using course surveys, self-efficacy surveys, rubrics-like grading protocols, and grades. We have also interviewed teaching assistants about their experiences.
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| 10. |
- Enström, Emma, 1978-
(author)
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On difficult topics in theoretical computer science education
- 2014
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Doctoral thesis (other academic/artistic)abstract
- This thesis primarily reports on an action research project that has been conducted on a course in theoretical computer science (TCS). The course is called Algorithms, data structures, and complexity (ADC) and is given at KTH Royal Institute of Technology in Stockholm, Sweden.The ADC course is an introduction to TCS, but resembles and succeeds courses introducing programming, system development best practices, problem solving, proving, and logic. Requiring the completion of four programming projects, the course can easily be perceived as a programming course by the students. Most previous research in computer science education has been on programming and introductory courses.The focus of the thesis work has been to understand what subject matter is particularly difficult to students. In three action research cycles, the course has been studied and improved to alleviate the discovered difficulties. We also discuss how the course design may color students’ perceptions of what TCS is. Most of the results are descriptive.Additionally, automated assessment has been introduced in the ADC course as well as in introductory courses for non-CS majors. Automated assessment is appreciated by the students and is directing their attention to the importance of program correctness. A drawback is that the exercises in their current form are not likely to encourage students to take responsibility for program correctness.The most difficult tasks of the course are related to proving correctness, solving complex dynamic programming problems, and to reductions. A certain confusion regarding the epistemology, tools and discourse of the ADC course and of TCS in general can be glimpsed in the way difficulties manifest themselves. Possible consequences of viewing the highly mathematical problems and tools of ADC in more practical, programming, perspective, are discussed. It is likely that teachers could explicitly address more of the nature and discourse of TCS in order to reduce confusion among the students, for instance regarding the use of such words and constructs as “problem”, “verify a solution”, and “proof sketch”.One of the tools used to study difficulties was self-efficacy surveys. No correlation was found between the self-efficacy beliefs and the graded performance on the course. Further investigation of this is beyond the scope of this thesis, but may be done with tasks corresponding more closely and exclusively to each self-efficacy item.Didactics is an additional way for a professional to understand his or her subject. Didactics is concerned with the teaching and learning of something, and hence sheds light on that “something” from an angle that sometimes is not reflected on by its professionals. Reflecting on didactical aspects of TCS can enrichen the understanding of the subject itself, which is one goal with this work.
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