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- Ericsson, Rolf
(författare)
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A Comparative Study of Head Development in Mexican Axolotl and Australian Lungfish: Cell Migration, Cell Fate and Morphogenesis
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The development of the vertebrate head is a complex process involving interactions between a multitude of cell types and tissues. This thesis describes the development of the cranial neural crest and of the visceral arch muscles in the head of two species. One, the Mexican axolotl (Ambystoma mexicanum), is a basal tetrapod, whereas the other, the Australian lungfish (Neoceratodus forsteri), belongs to the Dipnoi, the extant sister group of the Tetrapoda. The migration of neural crest cells, which form most of the bones and connective tissues in the head, and the morphogenesis of the jaw, was determined in the Mexican axolotl. It was shown that both the upper and lower jaws form from ventral condensations of neural crest cells in the mandibular arch. The dorsal condensation, earlier considered to give rise to the upper jaw, was shown to form the trabecula cranii.The normal spatio-temporal development of visceral arch muscles was investigated in both the Mexican axolotl and the Australian lungfish. In axolotl, the muscles tended to start forming almost simultaneously in all visceral arches at their future origins and extend towards their future insertions at the onset of muscle fibre formation. In lungfish, fibres formed simultaneously throughout most of each muscle anlage in the first and second visceral arch, but were delayed in the branchial arches. The anlagen were first observed at their future insertion, from which they developed towards future origins. To test the ability of neural crest cells to pattern the visceral arch muscles, migrating crest cells were extirpated from axolotl embryos, which resulted in a wide range of muscle malformations. In most cases, the muscles appeared in the right position but were small and extended in abnormal directions. This shows that neural crest cells are responsible not for the position of the muscles but for their correct anatomical pattern. Fate mapping showed that connective tissue surrounding myofibers is, at least partly, neural crest derived.In conclusion, the work presented in this thesis shows that although early development may map out the patterns of later development, the differences between axolotl and lungfish head development are not seen until during morphogenesis. Further investigation of morphogenesis is needed to explain the great variation of head morphology seen in vertebrates today.
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- Johansson, Rolf, et al.
(författare)
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Sensor Integration in Task-level Programming and Industrial Robotic Task Execution Control
- 2004
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Ingår i: Industrial Robot. - : Emerald. - 0143-991X. ; 31:3, s. 284-296
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Tidskriftsartikel (refereegranskat)abstract
- Presents an approach to improved performance and flexibility in industrial robotics by means of sensor integration and feedback control in task-level programming and task execution. Also presents feasibility studies in support of the ideas. Discusses some solutions to the problem using six degrees of freedom force control together with the ABB S4CPlus system as an illustrative example. Consider various problems in the design of an open sensor interface for industrial robotics and discusses possible solutions. Finally, presents experimental results from industrial force controlled grinding.
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- Bengtsson, Johan, et al.
(författare)
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A Robot Playing Scrabble Using Visual Feedback
- 2000
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Ingår i: IFAC Proceedings Volumes. ; 33:27, s. 551-556
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Tidskriftsartikel (refereegranskat)abstract
- Today most industrial robot systems use dedicated and rather limited sensors, and available control systems provide limited support for feedback control. Aiming towards more autonomous robot systems, we want to improve flexibility. The game Scrabble is used as a test problem capturing these aspects. Our approach is to incorporate visual servoing and a conventional powerful off-line prograrnrning (OLP) system into the real-time control system, providing task specification and visual debugging. We use the OLP tool Envision from Deneb and an ABB robot with reconfigured control system, where the control system has an Open Robot Control architecture (ORC). The vision system is connected to a host computer and the camera is attached to the robot gripper. By extending the control system, we have designed and implemented both the vision system and the application for the Scrabble game. Our system implementation shows that ORC constitutes a necessary support for incorporation of real-time visual feedback and that OLP may effectively be used with real-time feedback of sensor data.
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- Björnsson, Einar, 1958, et al.
(författare)
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Fatigue in patients with primary sclerosing cholangitis.
- 2004
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Ingår i: Scandinavian journal of gastroenterology. - : Informa UK Limited. - 0036-5521 .- 1502-7708. ; 39:10, s. 961-8
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The occurrence of fatigue in primary sclerosing cholangitis (PSC), its impact on quality of life and the role of concomitant inflammatory bowel disease (IBD) and coexisting irritable bowel syndrome (IBS) is unexplored. METHODS: Ninety-three patients with PSC, associated with IBD in 80% of cases and 77 patients with IBD alone, were enrolled in the study. The patients completed the following questionnaires: the Fatigue Impact Scale (FIS), the Psychological General Well-Being Index (PGWB), the Gastrointestinal Symptom Rating Scale (GSRS), the Beck Depression Inventory (BDI) and diagnostic criteria for IBS. Questionnaire data were related to liver tests and the latest liver biopsy in the PSC patients. Two sex- and age matched controls from the general population (GP) were assigned to each PSC patient and these controls completed the FIS and the BDI. RESULTS: Total fatigue score did not differ significantly between patients with PSC and IBD alone. Median total fatigue score among GP subjects was 39 (13-72), which was higher than in PSC (19 (6-52) (P = 0.02)) and in IBD patients (19 (5-35) (P < 0.0001)). PGWB and GSRS scores did not differ between patients with PSC and IBD alone. Depression and general health (PGWB) were independent predictors for total fatigue score in PSC. No correlation was observed between fatigue in PSC and the severity of the liver disease. CONCLUSIONS: Fatigue in patients with PSC is related to depression but not to the severity of the liver disease. Both the PSC and IBD patients had lower total fatigue scores than subjects from the general population. This argues against fatigue as a specific symptom of PSC and IBD patients.
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- Bülow, Margareta, et al.
(författare)
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Supraglottic swallow, effortful swallow, and chin tuck did not alter hypopharyngeal intrabolus pressure in patients with pharyngeal dysfunction.
- 2002
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Ingår i: Dysphagia. - : Springer Science and Business Media LLC. - 1432-0460 .- 0179-051X. ; 17:3, s. 197-201
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Tidskriftsartikel (refereegranskat)abstract
- Simultaneous videoradiography and solid-state manometry (videomanometry) were performed in 8 patients (4 women, 4 men; age range = 46-81 years, mean age = 70 years) with pharyngeal dysfunction in order to disclose any changes in intrabolus pressure during swallowing maneuvers. Five of the patients had severe pharyngeal dysfunction with frequent misdirected swallows. Three of the patients had moderate pharyngeal dysfunction with delayed initiation of pharyngeal swallow. Three different swallowing techniques were applied: supraglottic swallow, effortful swallow, and chin tuck. Pharyngeal intrabolus pressure was analyzed at the level of the inferior pharyngeal constrictor. Supraglottic swallow, effortful swallow, and chin tuck did not alter peak amplitude or duration of the intrabolus pressure.
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- Bülow, Margareta, et al.
(författare)
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Videomanometric analysis of supraglottic swallow, effortful swallow, and chin tuck in patients with pharyngeal dysfunction
- 2001
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Ingår i: Dysphagia. - : Springer Science and Business Media LLC. - 1432-0460 .- 0179-051X. ; 16:3, s. 190-195
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Tidskriftsartikel (refereegranskat)abstract
- Simultaneous videoradiography and solid-state manometry (videomanometry) was performed in 8 patients (4 women, 4 men; age range = 46-81 years, mean age = 70 years) with pharyngeal dysfunction. Five patients had severe pharyngeal dysfunction with frequent misdirected swallows. Three patients had moderate pharyngeal dysfunction with delayed initiation of pharyngeal swallow. Three different swallowing techniques were used: supraglottic swallow, effortful swallow, and chin tuck. Ten video radiographic variables and six manometric variables were analyzed. Contrast media penetration to the airways was analyzed regarding number of events and level of penetration. Supraglottic swallow, effortful swallow, and chin tuck did not reduce the number of misdirected swallows, but effortful swallow and chin tuck significantly (p = 0.008) reduced the depth of contrast penetration into the larynx and trachea. There was no significant improvement of pharyngeal retention. Chin tuck reduced the distance between the thyroid and the hyoid and the distance between the mandible and the hyoid. No other measured variable was significantly altered. This study shows that none of the different swallowing techniques reduced the number of misdirected swallows. However, there was a significantly reduced depth of the misdirected swallows. The swallowing techniques did not seem to prevent the occurrence of retention or improve weak pharyngeal constrictor muscles in this group of patients with severe to moderate dysfunction.
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| 10. |
- Bülow, Margareta, et al.
(författare)
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Videoradiographic analysis of how carbonated thin liquids and thickened liquids affect the physiology of swallowing in subjects with aspiration on thin liquids.
- 2003
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Ingår i: Acta Radiologica. - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 44:4, s. 366-372
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To analyze how carbonated thin liquids affected the physiology of swallowing in dysphagic patients. Material and Methods: 40 patients were analyzed; 36 were neurologically impaired. During a therapeutic videoradiographic swallowing examination the patients had to swallow liquids with the following consistencies three times: thin, thickened and carbonated. The liquids were given in doses of 3 x 5 ml. The swallows were analyzed regarding penetration/aspiration, pharyngeal transit time and pharyngeal retention. Results: Significant difference was found regarding penetration/aspiration when comparisons were made between thin liquid and carbonated thin liquid (p<0.0001). Carbonated liquid reduced the penetration to the airways. The comparison between thin liquid and thickened liquid (p<0.0001) showed significant less penetration with thickened liquids. Pharyngeal transit time was reduced both when comparing thin liquid with thin carbonated liquid (p<0.0001) and thickened liquid (p<0.0001). Pharyngeal retention was significantly reduced (p<0.0001) with carbonated thin liquid compared to thickened liquid. The comparison of thin liquids and carbonated thin liquids showed p = 0.0013, thin and thickened liquids p = 0.0097. Conclusions: Carbonated liquids reduced penetration/aspiration into the airways, reduced pharyngeal retention and pharyngeal transit time became shorter. Therefore, carbonated liquids are a valuable treatment option for patients with penetration/aspiration. Thickened liquids may still be an option for patients who cannot tolerate carbonated liquids and liquids with this consistency are safer than thin liquids.
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