| 1. |
- Dreifaldt, Mats, 1959-, et al.
(författare)
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Pedicled versus skeletonized internal thoracic artery grafts : a randomized trial
- 2021
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Ingår i: Asian cardiovascular & thoracic annals. - : Medikaru Toribyun. - 1816-5370 .- 0218-4923. ; 29:6, s. 490-497
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Concerns have been raised regarding whether skeletonization of the internal thoracic artery could damage the graft and thereby reduces its patency. The objective of this study was to compare patency rates at mid- and long-term follow-up between pedicled and skeletonized left internal thoracic artery grafts.METHODS: This randomized controlled trial included 109 patients undergoing coronary artery bypass surgery. The patients were assigned to receive either one pedicled or one skeletonized left internal thoracic artery graft to the left anterior descending artery. Follow-up was performed at 3 years with conventional angiography, and at 8 years with computed tomography angiography. Differences between patency rates were analyzed with Fisher's exact test and a generalized linear model.RESULTS: The patency rates for pedicled and skeletonized left internal thoracic artery grafts were 46/48 (95.8%) versus 47/52 (90.4%), p = 0.44 at 3 years, and 40/43 (93.0%) versus 37/41 (90.2%), p = 0.71 at 8 years, respectively. The difference in patency rates for pedicled and skeletonized grafts was 5.4% (95% confidence interval: -4.2-14.5) at 3 years and 2.8% (95% confidence interval: -9.9-14.1) at 8 years. All failed grafts, except for one with a localized stenosis, were anastomosed to native coronary arteries with a stenosis less than 70%. Three patients suffered sternal wound infections (two in the pedicled group, one in the skeletonized group).CONCLUSIONS: The skeletonization technique can be used without jeopardizing the patency of the left internal thoracic artery. The most important factor in graft failure was target artery stenosis below 70%.
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| 2. |
- Uusimäki, Liisa, 1959, et al.
(författare)
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Cross-cultural ‘distance’, ‘friction’ and ‘flow’: exploring the experiences of pre-service teachers on international practicum
- 2016
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Ingår i: Asia Pacific Journal of Education. - : Informa UK Limited. - 0218-8791 .- 1742-6855. ; 36:3, s. 425-436
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Tidskriftsartikel (refereegranskat)abstract
- The focus of this paper is to illustrate Australian regional pre-service teachers’ perceptions of an international practicum: their cross-cultural understanding, notions of privilege and teacher/professional identity development. Findings indicate that there were three overlapping dimensions of cross-cultural understanding for pre-service teachers: distance, friction and flow. At times students acknowledged the value of their placement, yet indicated a lack of empathy and engagement with the culture visited. At other times there was clear frustration at the cultural differences, alongside a growth in awareness. The fullest dimension was where pre-service teachers and their students learnt from each other, signalling a sharing towards cross-cultural understanding. Implications of these findings aim to inform how international practicums are designed in the future, as well as signalling directions for further research relating to these border crossings.
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| 3. |
- Nordberg, Klas, et al.
(författare)
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A flexible runtime system for image processing in a distributed computational environment for an unmanned aerial vehicle
- 2006
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Ingår i: International Journal of Pattern Recognition and Artificial Intelligence. - 0218-0014. ; 20:5, s. 763-780
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Tidskriftsartikel (refereegranskat)abstract
- A runtime system for implementation of image processing operations is presented. It is designed for working in a flexible and distributed environment related to the software architecture of a newly developed UAV system. The software architecture can be characterized at a coarse scale as a layered system, with a deliberative layer at the top, a reactive layer in the middle, and a processing layer at the bottom. At a finer scale each of the three levels is decomposed into sets of modules which communicate using CORBA, allowing system development and deployment on the UAV to be made in a highly flexible way. Image processing takes place in a dedicated module located in the process layer, and is the main focus of the paper. This module has been designed as a runtime system for data flow graphs, allowing various processing operations to be created online and on demand by the higher levels of the system. The runtime system is implemented in Java, which allows development and deployment to be made on a wide range of hardware/software configurations. Optimizations for particular hardware platforms have been made using Java's native interface.
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| 4. |
- Aichholzer, Oswin, et al.
(författare)
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Folding Polyominoes into (Poly)Cubes
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Ingår i: International journal of computational geometry and applications. - 0218-1959.
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Tidskriftsartikel (refereegranskat)
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| 5. |
- Andersson, Lars-Erik, 1942-, et al.
(författare)
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Equivalence of topological form for curvilinear geometric objects
- 2000
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Ingår i: International journal of computational geometry and applications. - 0218-1959. ; 10:6, s. 609-622
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Tidskriftsartikel (refereegranskat)abstract
- Given a curvilinear geometric object in R3, made up of properly-joined parametric patches defined in terms of control points, it is of interest to know under what conditions the object will retain its original topological form when the control points are perturbed. For example, the patches might be triangular BΘzier surface patches, and the geometric object may represent the boundary of a solid in a solid-modeling application. In this paper we give sufficient conditions guaranteeing that topological form is preserved by an ambient isotopy. The main conditions to be satisfied are that the original object should be continuously perturbed in a way that introduces no self-intersections of any patch, and such that the patches remain properly joined. The patches need only have C0 continuity along the boundaries joining adjacent patches. The results apply directly to most surface modeling schemes, and they are of interest in several areas of application.
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| 6. |
- Andersson, Mattias, et al.
(författare)
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Balanced partition of minimum spanning trees
- 2003
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Ingår i: International Journal of Computational Geometry and Applications. - 0218-1959. ; 13:4, s. 303-316
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Tidskriftsartikel (refereegranskat)abstract
- To better handle situations where additional resources are available to carry out a task, many problems from the manufacturing industry involve dividing a task into a number of smaller tasks, while optimizing a specific objective function. In this paper we consider the problem of partitioning a given set S of n points in the plane into k subsets, S-1,...,S-k, such that max(1less than or equal toiless than or equal tok) MST(S-i) is minimized. Variants of this problem arise in applications from the shipbuilding industry. We show that this problem is NP-hard, and we also present an approximation algorithm for the problem, in the case when k is a fixed constant. The approximation algorithm runs in time O(n logn) and produces a partition that is within a factor (4/3 + epsilon) of the optimal if k = 2, and a factor (2 + epsilon) otherwise.
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| 7. |
- Andersson, Mattias, et al.
(författare)
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Restricted mesh simplification using edge contractions
- 2009
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Ingår i: International Journal of Computational Geometry and Applications. - 0218-1959. ; 19:3, s. 247-265
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Tidskriftsartikel (refereegranskat)abstract
- We consider the problem of simplifying a planar triangle mesh using edge contractions, under the restriction that the resulting vertices must be a subset of the input set. That is, contraction of an edge must be made on to one of its adjacent vertices, which results in removing the other adjacent vertex. We show that if the perimeter of the mesh consists of at most five vertices, then we can always find a vertex not on the perimeter which can be removed in this way. If the perimeter consists of more than five vertices such a vertex may not exist. In order to maintain a higher number of removable vertices under the above restriction, we study edge flips which can be performed in a visually smooth way. A removal of a vertex which is preceded by one such smooth operation is called a 2-step removal. Moreover, we introduce the possibility that the user defines "important" vertices (or edges) which have to remain intact. Given m such important vertices, or edges, we show that a simplification hierarchy of size O(n) and depth O(log(n/m))can be constructed by 2-step removals in O(n) time, such that the simplified graph contains the m important vertices and edges, and at most O(m) other vertices from the input graph. In some triangulations, many vertices may not even be 2-step removable. In order to provide the option to remove such vertices, we also define and examine k-step removals. This increases the lower bound on the number of removable vertices.
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| 8. |
- Bose, Prosenjit, et al.
(författare)
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Online routing in convex subdivisions
- 2002
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Ingår i: International journal of computational geometry and applications. - 0218-1959. ; 12:4, s. 283-295
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Tidskriftsartikel (refereegranskat)abstract
- We consider online routing algorithms for finding paths between the vertices of plane graphs. We show (1) there exists a routing algorithm for arbitrary triangulations that has no memory and uses no randomization, (2) no equivalent result is possible for convex subdivisions, (3) there is no competitive online routing algorithm under the Euclidean distance metric in arbitrary triangulations, and (4) there is no competitive online routing algorithm under the link distance metric even when the input graph is restricted to be a Delaunay, greedy, or minimum-weight triangulation.
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| 9. |
- Carlsson, Svante, et al.
(författare)
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Optimum guard covers and m-watchmen routes for restricted polygons
- 1993
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Ingår i: International journal of computational geometry and applications. - 0218-1959. ; 3:1, s. 85-105
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Tidskriftsartikel (refereegranskat)abstract
- A watchman, in the terminology of art galleries, is a mobile guard. We consider several watchman and guard problems for different classes of polygons. We introduce the notion of vision spans along a path (route) which provide a natural connection between the Art Gallery problem, the m-watchmen problem and the watchman route problem. We prove that finding the minimum number of vision points, i.e., static guards, along a shortest watchman route is NP-hard. We provide a linear time algorithm to compute the best set of static guards in a histogram polygon. The m-watchmen problem, minimize total length of routes for m watchmen, is NP-hard for simple polygons. We give a \Theta(n 3 + n 2 m 2 )-time algorithm to compute the best set of m watchmen in a histogram. 1 Introduction The problem of placing guards in an art gallery so that every point in the gallery is visible to at least one guard has been considered by several researchers. If the gallery is represented by a polygon, ...
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| 10. |
- Ebbers-Baumann, Annette, et al.
(författare)
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Embedding point sets into plane graphs of small dilation
- 2007
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Ingår i: International Journal of Computational Geometry and Applications. - 0218-1959. ; 17:3, s. 201-230
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Tidskriftsartikel (refereegranskat)abstract
- Let S be a set of points in the plane. What is the minimum possible dilation of all plane graphs that contain S? Even for a set S as simple as five points evenly placed on the circle, this question seems hard to answer; it is not even clear if there exists a lower bound > 1. In this paper we provide the first upper and lower bounds for the embedding problem. 1. Each finite point set can be embedded in to the vertex set of a finite triangulation of dilation <= 1.1247. 2. Each embedding of a closed convex curve has dilation >= 1.00157. 3. Let P be the plane graph that results from intersecting n infinite families of equidistant, parallel lines in general position. Then the vertex set of P has dilation >= 2/root 3 approximate to 1.1547.
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