| 1. |
- Ahmed, Mobyen Uddin, Dr, 1976-, et al.
(författare)
-
A machine learning approach for biomass characterization
- 2019
-
Ingår i: Energy Procedia. - : Elsevier Ltd. - 1876-6102. ; , s. 1279-1287
-
Konferensbidrag (refereegranskat)abstract
- The aim of this work is to apply and evaluate different chemometric approaches employing several machine learning techniques in order to characterize the moisture content in biomass from data obtained by Near Infrared (NIR) spectroscopy. The approaches include three main parts: a) data pre-processing, b) wavelength selection and c) development of a regression model enabling moisture content measurement. Standard Normal Variate (SNV), Multiplicative Scatter Correction and Savitzky-Golay first (SG1) and second (SG2) derivatives and its combinations were applied for data pre-processing. Genetic algorithm (GA) and iterative PLS (iPLS) were used for wavelength selection. Artificial Neural Network (ANN), Gaussian Process Regression (GPR), Support Vector Regression (SVR) and traditional Partial Least Squares (PLS) regression, were employed as machine learning regression methods. Results shows that SNV combined with SG1 first derivative performs the best in data pre-processing. The GA is the most effective methods for variable selection and GPR achieved a high accuracy in regression modeling while having low demands on computation time. Overall, the machine learning techniques demonstrate a great potential to be used in future NIR spectroscopy applications. © 2019 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the scientific committee of ICAE2018 - The 10th International Conference on Applied Energy.
|
|
| 2. |
|
|
| 3. |
- Öhman, May-Britt, 1966-, et al.
(författare)
-
Sámi Land Free University : An invitation to centre Indigenous Peoples expertise and knowledge in an online open access university
- 2023
-
Konferensbidrag (refereegranskat)abstract
- This roundtable aims at presenting what the platform Sámi Land Free University (SFU) has achieved so far and to invite to a conversation on what SFU may achieve in the practice of decolonising research and education, while inviting interested to join forces for courses and joint or shared research over the colonial borders.Over the last four decades, Indigenous Studies (IS) has been developed as an academic discipline within several settler colonial states and within colonial academia, the strongest presence in North America, Australia and Aotearoa/New Zealand. So far Sweden is lagging behind. Yet, IS mainly turns the gaze towards the Indigenous peoples, while to achieve decolonization and long term sustainability, as well as good relations, there is a need for a 180 degrees shift in vision. What if there were several universities that centre Indigenous knowledges and expertise, as point of departure, while researching and teaching for the benefit of all?In 2015, the SFU [www.samelandsfriauniversitet.com ] was created by Lule and Forest Sámi, Dr May-Britt Ӧhman with a vision and challenge of the mind to include the Sámi community and international Indigenous collaborations, having its base on the Swedish side of Sábme. SFU has co-hosted symposia and workshops. We now envision moving on, producing free to access online educational content, inviting earlier and new collaborators. Methods adopted are supra-disciplinary, giving voice to academics, artists, and practitioners of Indigenous ways of knowing and being, while also inviting other scientific methods. Commentator: Kim TallBear, Univ of Alberta, Faculty of Native Studies1 May-Britt Öhman, Lule and Forest Sámi, with Tornedalian heritage, SábmeCentre for Multidisciplinary Studies on Racism, Uppsala UniversityExperiences from the last 7 years with the platform Sámi Land Free University – what has it done for my – and others – thinking and acting?Introductory presentation on how the Sámi Land Free University came about as a website in 2015, followed by a Facebook page, a youtube channel, and some of the activities that has taken place, as well as some thoughts on possibilities to move ahead.There are so far very little opportunities for Sámi to study our own history, culture, traditions, epistemologies at universities in Sweden. There are even less opportunities to have a place in academia for Sámi who are open with their Sámi identity. Hence, there is a need for a place to gather, to develop courses, and proposed ways to make this happen, as the (settler colonial) academia so far gives very little space to Sámi perspectives in Sweden. Yet, Swedish legislation states that the Sámi are a people, with rights, and that Sámi history, culture and tradition shall be taught to pupils in school and secondary school.Furthermore, at universities, there is almost no teaching on Indigenous peoples culture, history, traditions, around the world, while the settler colonial perspectives are taught in all university courses.Thus, there is a need for a Sámi university, on Swedish side of Sábme, that will provide both Sámi and other Indigenous peoples history, traditions, culture, expertise, perspectives - the question is mainly how to organize this.2 Frances Wyld, Martu woman (Aboriginal People of the Pilbara region of Australia) living on Kaurna land, Dr of CommunicationJustice and Society, University of South AustraliaAll good thing are wild and free: the wild winds that carried me to Sámi Land Free University.NAISA introduced me to the international cross fertilization of ideas within Indigenous research and education, specifically it created the opportunity to collaborate with Sámi Land Free University as an Australian Aboriginal scholar. The collaboration has included 6 visits to Sweden and Sápmi for symposia and workshops, publications, and freelance work on a climate change and Indigenous sustainability project. I am a storyteller; I write in the moment inspired by nature. I watch the news reporting on the damage done by wild winds on the weekend. The reporter is in front of a house where a tree has fallen onto it, the house is on my road. At the same time, through my open door, I hear the whine of the chainsaw cutting into this majestic ghost gum tree. Only weeks ago, I was riding my bicycle along the same road with a wild sense of freedom as my birds, the Rainbow Lorikeets who live in the avenue of trees, flew alongside me. Sámi Land Free University has given me the same sense of freedom to work as a decolonising scholar within Critical Indigenous Studies, gaining international perspectives and walking on two lands that are both rich is stories. The collaboration has given me opportunities, and now in the spirit of reciprocity, I lend my skills as a curriculum developer to create content for this grassroots university in another land inhabited by Indigenous people who have much in common with my own people, with knowledges to share for a sustainable future.3 Anna Kajsa Aira and Laila Susanna Kuhmunen, Jokkmokk in collaboration with Alma Linke NilsenDuv gábdde - Du gákti - Din kolt – Your Sámi dressWe are Sámi artisans, duojár. Anna Kajsa makes handicraft – duodje - in the Lule Sámi tradition, Jokkmokk area. Laila Susanna works within the North Sámi duodji tradition of the Karesuando area. We both live in Jokkmokk/Jåhkåmåhkke, a Sámi metropolis. Sámi heritage is passed down from generation to generation.The traditional Sámi dress – gábbde/gákti/kolt - reveals one’s geographical area and is an important link to one’s roots and history. Many Sámi now reclaim their culture by wanting to wear the dress, but there is a gap of one generation in the transmission of knowledge about how to make them. Our project “your Sámi dress” is about providing this knowledge, both by making the gábbde for children and young people, for rent, and through making a digital platform with instructions and advice. It is just as important to be able to wear your gábbde as it is to handle it respectfully. While there is a university in Sweden for textiles and fashion, there is no such for Sámi culture. We think maybe our work could find a place within the SFU, and thereby receive more support. 4 Henrik Andersson and Hampus Andersson, Gällivare Forest Sámi villageExperiences of and reflections on the needs for education and higher education for and about Sámi reindeer herdersReindeer husbandry is carried out on Sámi territories, on almost 50 percent of the territories of the colonial state of Sweden. It is is a tradition – a way of life – as well as a basis for livelihood, income, since several hundred of years. It is acknowledged as a national interest, to be protected, since 1987.Yet, the knowledge and expertise of reindeer herding is mainly passed within the families. Learning demands spending time together with the older generations, from early childhood. As the school system requests pupils to be in school, this often come into conflict with the need to learn. Furthermore, for a reindeer herder, there are an increasing set of other skills than the actual herding – which is complex enough- that are of importance; economics, law, animal health, and one’s own history and culture etc. In school, secondary school, and at universities, there are no opportunities to study reindeer herding with the other skills thereto related. Another aspect of the education system’s lack of teaching on reindeer and reindeer herding, is that when persons within the reindeer herding meet with all parts of society – health care, police, teachers, social care, etc, they have to carry the burden of constantly educating them, and also facing discrimination and racism. Henrik , 42 years old, and Hampus , 20 years old, are two generations reindeer herders within the Gällivare Forest Sámi village, Flakaberg group. They will share their experiences and reflect on the need for education and higher education for Sámi reindeer herders. 5 Susanne Spik and Gun Aira, Jåhkåmåkke in collaboration with Alma Linke NilsenLule Sámi culture and language on university level ? Experiences, reflections and ideas Gun Aira is a Lule Sámi teacher and Susanne Spik, is an entrepreneur and innovator. Both live in Jåhkåmåhkke, and are active within reindeer herding. Both have attended university – teacher’s education- at a Swedish university, in the 1980s. The Lule Sámi language and culture origin in the Lule River valley. Due to the by the Swedish state forced relocation of several North Sámi families, from the Karesuando area during in the 20th century, along with fierce Swedification politics, both the language and culture have become sidestepped. While there is a Lule Sámi centre on Norwegian side, there is no such on the Swedish. In general, there is vastly more support to Sámi culture and language in Norway, than in Sweden. We will present our experiences, reflections and ideas on how SFU could be of use to promote Lule Sámi language and culture, and wish to develop this with the others and the audience.
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Andersson, Fredrik, et al.
(författare)
-
Preferences for equity in health behind a veil of ignorance
- 1999
-
Ingår i: Health Economics. - 1099-1050. ; 8:5, s. 78-369
-
Tidskriftsartikel (refereegranskat)abstract
- Individual attitudes to distributions of life years between two groups in a society are explored by means of an experiment. Subjects are asked to place themselves behind a veil of ignorance which is specified in terms of risk (known probabilities) for some subjects and in terms of uncertainty (unknown probabilities) for some subjects. The latter is argued to be the appropriate interpretation of Rawls’ notion. It is found that subjects exhibit convex preferences over life years for the two groups, and that preferences do not differ between the risk and the uncertainty specifications.
|
|
| 7. |
|
|
| 8. |
- Andersson, Hampus, et al.
(författare)
-
Early Pharmacodynamic Changes Measured Using RNA Sequencing of Peripheral Blood from Patients in a Phase I Study with Mitazalimab, a Potent CD40 Agonistic Monoclonal Antibody
- 2023
-
Ingår i: Cells. - 2073-4409. ; 12:19
-
Tidskriftsartikel (refereegranskat)abstract
- CD40-targeting therapies can enhance the dendritic cell priming of tumor-specific T cells and repolarize intratumoral macrophages to alleviate the tumoral immunosuppressive environment and remodel the extracellular matrix. Mitazalimab is a potent agonistic CD40 monoclonal IgG1 antibody currently under clinical development. This study used RNA sequencing of blood samples from a subset of patients from a Phase I trial with mitazalimab (NCT02829099) to assess peripheral pharmacodynamic activity. We found that mitazalimab induced transient peripheral transcriptomic alterations (at 600 µg/kg and 900 µg/kg dose administered intravenously), which mainly were attributed to immune activation. In particular, the transcriptomic alterations showed a reduction in effector cells (e.g., CD8+ T cells and natural killer cells) and B cells peripherally with the remaining cells (e.g., dendritic cells, monocytes, B cells, and natural killer cells) showing transcription profiles consistent with activation. Lastly, distinct patient subgroups based on the pattern of transcriptomic alterations could be identified. In summary, the data presented herein reinforce the anticipated mode of action of mitazalimab and support its ongoing clinical development.
|
|
| 9. |
- Andersson, Hampus, et al.
(författare)
-
Next-generation CD40 agonists for cancer immunotherapy
- 2024
-
Ingår i: Expert Opinion on Biological Therapy. - 1471-2598. ; 24:5, s. 351-363
-
Forskningsöversikt (refereegranskat)abstract
- Introduction: There is a need for new therapies that can enhance response rates and broaden the number of cancer indications where immunotherapies provide clinical benefit. CD40 targeting therapies provide an opportunity to meet this need by promoting priming of tumor-specific T cells and reverting the suppressive tumor microenvironment. This is supported by emerging clinical evidence demonstrating the benefits of immunotherapy with CD40 antibodies in combination with standard of care chemotherapy. Areas covered: This review is focused on the coming wave of next-generation CD40 agonists aiming to improve efficacy and safety, using new approaches and formats beyond monospecific antibodies. Further, the current understanding of the role of different CD40 expressing immune cell populations in the tumor microenvironment is reviewed. Expert opinion: There are multiple promising next-generation approaches beyond monospecific antibodies targeting CD40 in immuno-oncology. Enhancing efficacy is the most important driver for this development, and approaches that maximize the ability of CD40 to both remodel the tumor microenvironment and boost the anti-tumor T cell response provide great opportunities to benefit cancer patients. Enhanced understanding of the role of different CD40 expressing immune cells in the tumor microenvironment may facilitate more efficient clinical development of these compounds.
|
|
| 10. |
- Andersson, Hampus, 2002-, et al.
(författare)
-
When the climate apocalypse comes I’ll make it : 16 yr old Hampus' survival month in the forest
- 2020
-
Annan publikation (film/video) (populärvet., debatt m.m.)abstract
- When the climate apocalypse comes I’ll make it: 16 year old Hampus Andersson’s survival month living off the lands and waters in the forests of Norrbotten, Sweden. There is a lot of talk of crisis and apocalypse, due to war, to climate change. Young people worried about their future go on school strike and manifest, around the world. But, when the climate or any other crisis happens, how are these young (and adult) protesters prepared to fend for themselves? How long can you survive without electricity and water in the tap, with access to food in the supermarket? Thinking about all of this, 16 year old Hampus Andersson decided to try to live off the lands and waters for a full month, on his own. If there is such a crisis, would he make it on his own? From mid July to mid August 2019, the experiment went on. He made sure to learn from more experienced and older reindeer herders and others with experience from the forests. Hampus is not completely unaware on how to get access to food in the forest. His father is a Sámi reindeer herder, and his mother’s family are an agriculture family. But until this day he had never done such an experiment. How would he find food, water, shelter? What would be the hardest? Some things that he had never even thought about turned out to be harder than expected. During the stay Hampus documented his everyday life with photos and short films, and posted on his Facebook page and Instagram. This is a film made from those photos and videos, along with an interview by film maker Petri Storlöpare, Slowfilm AB. Hampus speaks of his experiences, thoughts and ideas on how to continue this experiment. Will he try the same in the Arctic winter, with temperatures down to minus 40 Celsius? The film project is supported by Dálkke: Indigenous Climate Change Studies, led by Dr. May-Britt Öhman, Centre for Multidisciplinary Studies on Racism, CEMFOR, Uppsala University.
|
|
| 11. |
- Andersson, Jenny, et al.
(författare)
-
Thinking the Human System : The Application of Humanities and Social Science Reasoning to Societal Problems
- 2022
-
Ingår i: The Humanities and the Modern Politics of Knowledge : The Impact and Organization of the Humanities in Sweden, 1850-2020 - The Impact and Organization of the Humanities in Sweden, 1850-2020. - 9789463728867 - 9789048555024 ; , s. 207-230
-
Bokkapitel (refereegranskat)abstract
- Between 1967 and 1972, Swedish futures studies emerged as a distinct political and intellectual endeavor. In this development, the humanities and social sciences played a special role, especially through the idea that human knowledge and knowledge about a “human system” could be brought to bear on societal problems and used to forge a new approach to the future. We focus here on two scholars, historian Birgitta Odén and geographer Torsten Hägerstrand, proposing that they were important f igures in developing a new engagement with problems of social and human time in Swedish social science and humanities research.
|
|
| 12. |
- Andersson, Martin, et al.
(författare)
-
The anomalous hyperfine structure of Al II
- 2012
-
Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 45:13
-
Tidskriftsartikel (refereegranskat)abstract
- The hyperfine structure of a large number of transitions in Al II cannot be described using A and B hyperfine constants and the hyperfine structure is therefore said to be anomalous. In this paper, we have studied the hyperfine structure of a few transitions in Al II, 3s5s(3)S-3s5p(3)P, 3s4d(3)D-3s5p(3)P and 3s5p(3)P-3s5d(3)D, by combining theory and experiment. It is shown that the anomalous hyperfine structure is due to strong off-diagonal hyperfine interaction resulting not only in a deplacement of the energies of the hyperfine levels, but also resulting in large intensity redistribution among the individual hyperfine lines. It is shown that the hyperfine mixing in 3s4d(3)D and 3s5d(3)D is very large, whereas small but not negligible in 3s5p(3)P. By combining experimental spectra and theory we could obtain accurate wavefunctions for the 3s4d(3)D and 3s5d(3)D hyperfine levels which were used to calculate the gf-values of all individual hyperfine transitions not only for 3s5p(3)P, but also for 3s3p(3)P and 3s4p(3)P, where the off-diagonal hyperfine interaction leads to negligible intensity redistribution.
|
|
| 13. |
|
|
| 14. |
- Björkman, Henrik, et al.
(författare)
-
Split renal function in patients with suspected renal artery stenosis : a comparison between gamma camera renography and two methods of measurements with computed tomography
- 2006
-
Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 47:1, s. 107-113
-
Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To validate a method for calculating split renal function from computed tomography (CT) compared with gamma camera renography, and to test a new method for the measurement based on a volume-rendering technique. MATERIAL AND METHODS: Thirty-eight patients, aged 65.7 +/- 11.6 (range 37.8-82.1) years, who had undergone both CT angiography and gamma camera renography for a suspected renal artery stenosis were included in this study. Split renal function was calculated from the CT examinations by measuring area and mean attenuation in the image slices of the kidneys, and also by measuring volume and mean attenuation from a 3D reconstruction of the kidneys. Gamma camera renography with 99mTc-MAG3 with or without captopril enhancement was used as a reference. RESULTS: The 2D CT method had good correlation with renography (r=0.93). Mean difference was 4.7 +/- 3.6 (0-12) percentage points per kidney. There was also excellent correlation between the two CT methods (r=1.00). CONCLUSION: CT is equivalent to renography in determining split renal function, and the measurement from the CT examination can be made more quickly and equally accurately with a 3D technique.
|
|
| 15. |
- Carlsson, Magnus, et al.
(författare)
-
Methodology for Development and Validation of Multipurpose Simulation Models
- 2012
-
Ingår i: 50th AIAA Aerospace Sciences Meeting Online Proceedings including the New Horizons Forum and Aerospace Exposition (2012). - Reston, Virigina : AIAA.
-
Konferensbidrag (refereegranskat)abstract
- This paper describes a framework for development and validation of multipurpose simulation models. The presented methodology enables reuse of models in different applications with different purposes. The scope is simulation models representing physical environment, physical aircraft systems or subsystems, avionics equipment, and electronic hardware. The methodology has been developed by a small interdisciplinary team, with experience from Modeling and Simulation (M&S) of vehicle systems as well as development of simulators for verification and training. Special care has been taken to ensure usability of the workflow and method descriptions, mainly by means of 1) a user friendly format, easy to overview and update, 2) keeping the amount of text down, and 3) providing relevant examples, templates, and checklists. A simulation model of the Environmental Control System (ECS) of a military fighter aircraft, the Saab Gripen, is used as an example to guide the reader through the workflow of developing and validating multipurpose simulation models. The methods described in the paper can be used in both military and civil applications, and are not limited to the aircraft industry.
|
|
| 16. |
- Dahlin, Lars B., et al.
(författare)
-
Rehabilitation, Using Guided Cerebral plasticity, of a Brachial plexus Injury treated with Intercostal and phrenic Nerve transfers
- 2017
-
Ingår i: Frontiers in Neurology. - : Frontiers Media SA. - 1664-2295. ; 8
-
Tidskriftsartikel (refereegranskat)abstract
- Recovery after surgical reconstruction of a brachial plexus injury using nerve grafting and nerve transfer procedures is a function of peripheral nerve regeneration and cerebral reorganization. A 15-year-old boy, with traumatic avulsion of nerve roots C5-C7 and a non-rupture of C8-T1, was operated 3 weeks after the injury with nerve transfers: ( a) terminal part of the accessory nerve to the suprascapular nerve, (b) the second and third intercostal nerves to the axillary nerve, and (c) the fourth to sixth intercostal nerves to the musculocutaneous nerve. A second operation-free contralateral gracilis muscle transfer directly innervated by the phrenic nerve-was done after 2 years due to insufficient recovery of the biceps muscle function. One year later, electromyography showed activation of the biceps muscle essentially with coughing through the intercostal nerves, and of the transferred gracilis muscle by deep breathing through the phrenic nerve. Voluntary flexion of the elbow elicited clear activity in the biceps/gracilis muscles with decreasing activity in intercostal muscles distal to the transferred intercostal nerves (i.e., corresponding to eighth intercostal), indicating cerebral plasticity, where neural control of elbow flexion is gradually separated from control of breathing. To restore voluntary elbow function after nerve transfers, the rehabilitation of patients operated with intercostal nerve transfers should concentrate on transferring coughing function, while patients with phrenic nerve transfers should focus on transferring deep breathing function.
|
|
| 17. |
- Eklöf, Hampus, et al.
(författare)
-
A prospective comparison of duplex ultrasonography, Captopril renography, MRA and CTA in assessing renal artery stenosis
- 2006
-
Ingår i: Acta Radiologica. - : SAGE Publications. - 0284-1851 .- 1600-0455. ; 47:8, s. 764-774
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: To prospectively compare the diagnostic accuracy of duplex ultrasonography, captopril renography, computed tomography angiography (CTA), and 3D Gd magnetic resonance angiography (MRA) in diagnosing hemodynamically significant renal artery stenosis (RAS). Material and Methods: The standard of reference was measurement of transstenotic pressure gradient. Fifty-eight hypertensive patients with suspicion of RAS were evaluated, when possible, by all five techniques. Sensitivity and specificity to detect RAS were compared for each technique on both a patient and kidney basis. Discrepancies were evaluated separately and classified as borderline, method dependent, or operator dependent. Results: The prevalence of RAS was 77%. The sensitivity/specificity of ultrasonography, captopril renography, CTA, and MRA in detecting kidneys with RAS was 73/71%, 52/63%, 94/62%, and 93/91%, respectively. Ultrasonography had a significantly lower sensitivity than CTA and MRA (P < 0.001) but higher than captopril renography (P = 0.013). Borderline RAS was the main cause for discrepancies. Conclusion: MRA and CTA were significantly better than duplex ultrasonography and captopril renography in detecting hemodynamically significant RAS. The ultrasonography criteria for RAS based on the evaluation of renal peak systolic velocity and renal/aortic ratio are questionable. Captopril renography cannot be recommended for assessing RAS.
|
|
| 18. |
|
|
| 19. |
|
|
| 20. |
|
|
| 21. |
- Gavel, Hampus, 1964-
(författare)
-
On aircraft fuel systems : conceptual design and modeling
- 2007
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The largest and most important fluid system in an aircraft is the fuel system. Obviously, future aircraft projects involve the design of fuel system to some degree. In this project design methodologies for aircraft fuel systems are studied, with the aim to shortening the system development time.This is done by means of illustrative examples of how optimization and the use of matrix methods, such as the morphological matrix, house of quality and the design structure matrix, have been developed and implemented at Saab Aerospace in the conceptual design of aircraft fuel systems. The methods introduce automation early in the development process and increase understanding of how top requirements regarding the aircraft level impact low-level engineering parameters such as pipe diameter, pump size, etc. The morphological matrix and the house of quality matrix are quantified, which opens up for use of design optimization and probabilistic design.The thesis also discusses a systematic approach when building a large simulation model of a fluid system where the objective is to minimize the development time by applying a strategy that enables parallel development and collaborative engineering, and also by building the model to the correct level of detail. By correct level of detail is meant the level that yields a simulation outcome that meets the stakeholders’ expectations. The experienced gained at Saab in building a simulation model, mainly from the Gripen fuel system, but also the accumulated experience from other system models, is condensed and fitted into an overall process.
|
|
| 22. |
- Gavel, Hampus, et al.
(författare)
-
Optimal Conceptual Design of Aircraft Fuel Transfer Systems
- 2006
-
Ingår i: Journal of Aircraft. - : American Institute of Aeronautics and Astronautics (AIAA). - 0021-8669 .- 1533-3868. ; 43:5, s. 1334-1340
-
Tidskriftsartikel (refereegranskat)abstract
- This paper describes early considerations that have to be made when designing an aircraft fuel system. Emphasis is placed on illustrating the impact of top-level aircraft requirements on low-level practicalities such as fuel system design. Choosing between concepts is one of the most critical parts of any design process. Different concepts have different advantages, and the concept that is the best choice is often dependent on the top-level requirements. This paper shows how optimization has been used successfully at Saab Aerospace as a tool that supports concept selection. The example studied is the design of a fuel transfer system for a ventral drop tank and the optimization results in different conceptual designs depending on the top-level requirements.
|
|
| 23. |
|
|
| 24. |
- Gavel, Hampus, et al.
(författare)
-
Quantification of the Elements in the Relationship matrix : A conceptual study of Aircraft Fuel System
- 2004
-
Ingår i: 42nd AIAA Aerospace Sciences Meeting and Exhibit, Reno, USA, paper AIAA-2004-0538. - Reston, Virigina : American Institute of Aeronautics and Astronautics. ; , s. 5244-5252
-
Konferensbidrag (refereegranskat)abstract
- This paper describes how the framework of thc house of quality and design structure matrices are used to visualizee dependencies between top level requirements and engineering design properties. It is also discussed how quantification of the matrix elements may increase the understanding of how the top-level requirements impacts the low-level design parameters. lndeed, history has shown that overlooking combinatory effects between subsystems and night conditions may become expensive. Not only in terms of not goning getting the sizing right but more so if an entirely wrong concept is chosen.This paper shows a matrix technique that has successfully been used at Saab and how this technique may facilitate the cconcept evaluation process of early fuel system design.The matrix method aids the designer to take alk the relevant aspects into account when evaluating a design. Use of the method will also increase the understanding of what top-level requirement or combination thereof, which drives the choice of one particular concept rather than the other. The understanding of how the top-level requiremEnts impacts low level design parameters such as pump size or pipe diameter will also increse.
|
|
| 25. |
- Gavel, Hampus, et al.
(författare)
-
Strategy for Modeling of large A/C fluid systems
- 2004
-
Ingår i: World Aviation Congress and Display, WAC-04, SAE Technical Paper 2004-01-3093. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. ; , s. 1495-1506
-
Konferensbidrag (refereegranskat)abstract
- There is an ongoing trend in the European Military a/c industry towards cooperation between nations when purchasing and between manufacturers when developing and producing a/c. Different manufacturers at different locations develop different parts or sub-systems. When using this approach a vital part of a fast and precise system evaluation is the use of simulation models. In order to stay competitive it is not only sufficient to be able to build large simulation models but also to do it fast.This paper describes the conclusions regarding a modelling strategy of large fluid systems drawn from the building of a simulation model of the JAS 39 Gripen fuel system. An overall process is suggested into which the activities of building a model are fitted. This is however not the main objective; it is more important to identify the different issues and activities at the engineering level. If these are properly dealt with, the model development time will be reduced, if not, the wrong model may be designed. "Wrong" here means a model that does not do the job, or solves a problem other than the one intended by the stakeholder.
|
|
| 26. |
- Gavel, Hampus, et al.
(författare)
-
Using Optimization as a Tool in Fuel System Conceptual Design
- 2003
-
Ingår i: SAE World Aviation Congress and Display, Montreal, Canada, SAE Technical Paper 2003-01-3054. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International.
-
Konferensbidrag (refereegranskat)abstract
- Choosing between concepts is often the most critical part of the design process. Different concepts have different advantages and disadvantages. The concept that is the best choice is most often dependent on the top level requirements. Sometimes there may also be a trade off between concept choice and the top requirements. In aircraft (a/c) fuel system design it has often proved difficult to find the switching point where the superior concept is changed. This sometimes makes the designer conservative and leads to the selection of a concept with too high a penalty. There is also a risk for the opposite and perhaps worse scenario: That the designer strives to reduce weight and cost and therefore, accidentally, chooses an under achieving concept and thus induces large downstream cost if late redesign or retro modifications are necessary.This paper shows how optimization has been successfully used at Saab Aerospace as a tool that supports concept selection. The example shown is the choice of fuel transfer method for a ventral drop tank. The example also illustrates the impact of top-level requirements on low-level practicalities such as fuel system design.
|
|
| 27. |
|
|
| 28. |
- Hanstock, Helen, 1989-, et al.
(författare)
-
390 Can a heat-and-moisture exchanger attenuate inflammatory responses to exercise in sub-zero conditions?
- 2021
-
Ingår i: British Journal of Sports Medicine. ; 55:Suppl 1
-
Tidskriftsartikel (refereegranskat)abstract
- Background Heavy endurance training in sub-zero environments increases risk of exercise-induced asthma. Heat-and-moisture exchangers (HME) can prevent exercise-induced bronchoconstriction but it is not known whether they protect against inflammatory responses to exercise in healthy individuals.Objective To investigate whether use of an HME during exercise in a sub-zero environment affects post-exercise inflammatory responses.Design Investigator-blind randomised crossover trial.Setting Environmental chamber at -15°C.Participants 23 healthy, trained participants aged 18–53 (15 male, 8 female, VO2peak 57±6 and 50±4 mL/kg/min; mean±SD).Interventions Two experimental trials with and without HME, consisting of 30-min moderate-intensity running followed by a 4-min maximal running time-trial. Plasma samples were obtained pre- and 1h-post-exercise and analysed for a panel of 10 cytokines using a multiplex immunoassay.Main Outcome Measurements Plasma cytokine concentrations (GM-CSF, IL-1β, IL-4, IL-5, IL-6, IL-8, IL-10, IL-13, IL-17E/25, TNF-α). Data were log-transformed then analysed using two-way repeated-measures ANOVA; one participant was an extreme outlier and excluded.Results Five cytokines (GM-CSF, IL-1β, IL-4, IL-13, IL-17E/25) returned <20% concentrations within detection limits and were excluded from further analysis. The other cytokines returned >85% samples in range. IL-6, IL-8 and IL-10 increased after exercise (IL-6: F=36, p≤0.0001; IL-8: F=39, p≤0.0001; IL-10: F(1,21)=8.9, p=0.0072). There was a trend towards a greater post-exercise increase in IL-10 with HME (HME: median 0.062 (range -0.203–1.053) pg/mL; no-HME: 0.047 (-0.079–0.50) pg/mL; F=3.0, p=0.096). There were no significant interactions for other cytokines.Conclusions Use of an HME during exercise in a sub-zero environment did not affect systemic pro- and anti-inflammatory cytokine responses to exercise. Local inflammatory markers in the lungs may be relevant to investigate in future studies.
|
|
| 29. |
- Hanstock, Helen, 1989-, et al.
(författare)
-
A heat-and-moisture exchanging mask may increase the physiological demands of submaximal exercise in -15 degrees Celsius.
- 2020
-
Ingår i: Book of Abstracts of the 25th Annual Congress of the European College of Sport Science – 28th - 30th October 2020. - 9783981841435 ; , s. 75-76
-
Konferensbidrag (refereegranskat)abstract
- INTRODUCTION: Winter endurance athletes such as cross-country skiers have an increased prevalence of asthma (Eriksson et al., 2018, Scand J Med Sci Sport). Heat-and-moisture exchangers (HMEs) such as masks and mouthpieces with a filter to facilitate warming and humidification of inspired air may protect the airways from injury during exercise in cold, dry climates. However, if there is evidence of impaired exercise capacity, athletes will likely avoid using such devices. The aim of this study was to investigate the influence of an HME mask (AirTrim Sport, Vapro AB, Västerås, Sweden) on heart rate (HR), breathing rate (BR), muscle oxygenation (SmO2) and perceived exertion at fixed submaximal workloads. METHODS: 23 active, healthy participants without asthma aged 31 ± 8 years (15 men, 8 women) performed a familiarisation test followed by two experimental trials with and without HME in a randomised, crossover design. All tests were performed at a 4% gradient on a motorised treadmill and consisted of a submaximal incremental warm-up followed by a maximal, self-paced 4-min running time trial (TT). During the familiarisation test, participants wore a portable oxygen uptake system (Metamax 3B, Cortex Biophysik, Leipzig, Germany) with the TT used to derive VO2peak. Submaximal VO2 was interpolated to derive speeds estimated to elicit 65, 70, 75 and 90% of VO2peak. In two subsequent trials performed in a climate chamber at -15 degrees Celsius, participants ran for 5 min at speeds equivalent to 65, 70 and 75% VO2peak, 3 min at 90% and 12 min at 65% VO2peak. HR and BR were monitored via a chest harness (LifeMonitor, Equivital, Cambridge, UK); mean SmO2 from the right and left quadriceps was derived using near infra-red sensors (MOXY, Fortiori Design, Hutchinson MN, USA). Data were summarised as 1 min epochs, taken from 90 to 30 s before the end of each stage. Borg 6-20 rating of perceived exertion (RPE) was reported 1 min before the end of each stage. Data were analysed using repeated-measures ANOVA and linear mixed models. The study was approved by the regional ethical review board and conducted according to the Declaration of Helsinki. RESULTS: HR was 2.5 beats/min higher during the HME trial (95% CI: 0.3 - 4.6, p=.03). In the male participants only, SmO2 was lower during the HME trial than control (-2.3%, 95% CI: -0.1 - -4.5, p=.04). The female participants reported higher RPE (0.65 AU) during the HME trial (p=.009). There was no difference in BR between the HME and control trials. CONCLUSION: Despite potentially small increases in dead space and resistance to breathing, an HME did not affect BR during submaximal exercise in -15 degrees C. However, higher HR during exercise with an HME, as well as lower SmO2 in the male participants and higher RPE in the female participants, indicates slightly higher physiological stress during steady-state exercise with an HME. It would therefore be relevant to investigate whether an HME affects maximal exercise capacity in sub-zero temperatures.
|
|
| 30. |
|
|
| 31. |
- Jones, Thomas W., et al.
(författare)
-
Anthropometric, Physiological, and Performance Developments in Cross-country Skiers
- 2021
-
Ingår i: Medicine & Science in Sports & Exercise. - : American collegeof sports medicine. - 0195-9131 .- 1530-0315. ; 53:12, s. 2553-2564
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose This study aimed to describe changes in laboratory-assessed anthropometric and physiological characteristics, training volumes, and competitive performance in national development-team cross-country skiers over a 25-month period, and to analyze whether changes in competitive performance could be predicted by changes in laboratory-assessed qualities and training volumes.Methods Data collected over 25 months from 30 national development-team cross-country skiers (14 women, 16 men; age, 18–23 yr) were analyzed retrospectively using multivariate statistics. Anthropometric and physiological characteristics were assessed via dual-energy x-ray absorptiometry and incremental roller-ski treadmill tests, respectively. Total training volumes and distributions of low- and high-intensity training were analyzed from online training diaries, and competitive performance was determined by International Ski Federation (FIS) distance and sprint points.Results Whole- and upper-body lean mass increased in the full cohort of skiers (n = 30; both P < 0.05), whereas lower-body lean mass, whole-body fat mass, speed and oxygen uptake (V˙O2) at a blood lactate concentration (BLa) of 2 and 4 mmol·L−1, as well as time-trial completion time, power output, and peak V˙O2, improved in the women only (all P < 0.05). Valid predictive models were identified for female skiers’ best FIS distance points (R2 = 0.81/Q2 = 0.51) and changes in FIS distance points (R2 = 0.83/Q2 = 0.54), with body mass, fat mass, lean mass, V˙O2peak, and speed at a BLa of 4 mmol·L−1 identified as consistently important variables for projection.Conclusions The valid prediction of competitive performance was achieved for women only in distance events. This study suggests that improvements in body composition and aerobic capacity may be more beneficial for elite female development-level skiers than for their male counterparts. These results have implications for athlete selection and performance development.
|
|
| 32. |
- Laaksonen, Marko, 1975-, et al.
(författare)
-
Laboratory-Based Factors Predicting Skiing Performance in Female and Male Biathletes
- 2020
-
Ingår i: Frontiers in Sports and Active Living. - : Frontiers Media SA. - 2624-9367. ; 2
-
Tidskriftsartikel (refereegranskat)abstract
- Skiing in biathlon is a high-intensity, intermittent endurance discipline. This study aimed to evaluate the relationships between laboratory-derived physiological variables and skiing performance during a field-based biathlon competition (BC) for female and male biathletes. Fourteen female (23 ± 3 year, VO2max 56 ± 4 mL·kg−1·min−1) and 14 male (24 ± 4 year, VO2max 66 ± 3 mL·kg−1·min−1) biathletes performed a submaximal incremental test and a maximal time-trial (TT) using treadmill roller-skiing for the assessment of oxygen uptake at a lactate threshold of 4 mmol·L−1 (VO2@4mmol), gross efficiency (GE), aerobic (MRae) and anaerobic (MRan) metabolic rates, peak oxygen consumption (VO2peak), anaerobic capacity and TT performance. Field-based skiing performance was assessed during a BC. The TT and BC skiing performances were significantly correlated in both sexes (r = 0.68–0.69, p < 0.01). VO2peak (31/21%), anaerobic capacity (1/0%), and GE (35/32%) explained 67 and 52% of the variance in BC skiing performance for the females (p < 0.01) and males (p = 0.051), respectively. A second model showed that VO2@4mmol (30/35%), anaerobic capacity (0/0%) and GE (37/13%) explained 67 and 48% of the variance in BC skiing performance for the females (p < 0.01) and males (p = 0.077), respectively. Results of this study suggest that a high VO2@4mmol and GE, but not anaerobic capacity, are important for BC skiing performance, especially for females. In addition, a laboratory-based TT could be useful for regular laboratory testing of biathletes due to its relationship with field-based skiing performance in biathlon.
|
|
| 33. |
|
|
| 34. |
- Moberg, Christina, et al.
(författare)
-
De unga gör helt rätt när de stämmer staten
- 2022
-
Ingår i: Aftonbladet. - 1103-9000.
-
Tidskriftsartikel (populärvet., debatt m.m.)abstract
- 1 620 forskare och lärare i forskarvärlden: Vi ställer oss bakom Auroras klimatkrav
|
|
| 35. |
- Nordenstedt, Helena, et al.
(författare)
-
Global hälsa på läkarutbildningen igår, idag och imorgon
- 2021
-
Ingår i: Socialmedicinsk Tidskrift. - : Stiftelsen socialmedicinsk tidskrift. - 0037-833X. ; 98:2, s. 232-243
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Undervisning i global hälsa förekommer i olika former vid samtliga läkarutbildningar i Sverige, och på vissa håll har kursmoment med fokus på internationell hälsa funnits i över trettio år. I denna artikel presenteras utvecklingenav global hälsa vid Sveriges läkarutbildningar – från dåtid till nutid och framtid. Textbidrag har inkommit från respektive lärosäte och sammanställts av Helena Nordenstedt och Hampus Holmer.
|
|
| 36. |
|
|
| 37. |
- Steinkellner, Sören, et al.
(författare)
-
Modeling and simulation of Saab Gripen’s vehicle systems
- 2009
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- This paper gives an overview of the modeling and simulation work for the military aircraft JAS 39 Gripen´s vehicle systems. The vehicle systems comprise fuel, ECS, hydraulic, and auxiliary power systems and also landing gear. Vehicle systems have several modeling challenges such as both compressible air and less compressible fluids that give stiff differential equations, gforce effects, nonlinear cavitation and saturation. It is also a complex system of integrated systems that requires models with integrated system software. Dynamic models based on physical differential equations have generally been used. The physical systems were previously modeled in Easy5 and the software in MATRIXx. Changes in tools where the physical systems are modeled in Dymola and the control algorithms are modeled in Simulink have opened up for new possibilities for more advanced and more complete system simulations. Simulations have been performed during the whole development cycle of the aircraft from concept evaluation to qualification tests. The paper gives some examples from the simulations where system performance and the internal states of the system are calculated.
|
|
| 38. |
- Steinkellner, Sören, et al.
(författare)
-
Modeling and Simulation of Saab Gripens Vehicle Systems, Challenges in Processes and Data Uncertainties
- 2010
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In aircraft development, it is crucial to understand and evaluate behaviour, performance, safety and other aspects of subsystems before and after they are physically available for testing. Simulation models are used to gain knowledge in order to make decisions at all development stages. This paper describes the development of Saab Gripen´s vehicle systems and some methods and challenges related to uncertainties in test and model data. The ability to handle uncertain information and lack of information is the key to success in early design. The vehicle systems comprise fuel, environment control system (ECS), hydraulic, auxiliary power, escape, electrical power and landing gear system.
|
|
| 39. |
- Stenfors, Nikolai, et al.
(författare)
-
A breathing mask attenuates acute airway responses to exercise in sub-zero environment in healthy subjects
- 2022
-
Ingår i: European Journal of Applied Physiology. - : Springer Science+Business Media B.V.. - 1439-6319 .- 1439-6327. ; 122, s. 1473-1484
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: Cold air exposure is associated with increased respiratory morbidity and mortality. Repeated inhalation of cold and dry air is considered the cause of the high prevalence of asthma among winter endurance athletes. This study assessed whether a heat- and moisture-exchanging breathing device (HME) attenuates airway responses to high-intensity exercise in sub-zero temperatures among healthy subjects.Methods: Using a randomized cross-over design, 23 healthy trained participants performed a 30-min warm-up followed by a 4-min maximal, self-paced running time trial in − 15 °C, with and without HME. Lung function was assessed pre- and immediately post-trials. Club cell protein (CC-16), 8-isoprostane, and cytokine concentrations were measured in plasma and urine pre- and 60 min post trials. Symptoms were assessed prior to, during, and immediately after each trial in the chamber.Results: HME use attenuated the decrease in forced expiratory volume in 1 s (FEV1) post trials (∆FEV1: mean (SD) HME − 0.5 (1.9) % vs. no-HME − 2.7 (2.7) %, p = 0.002). HME also substantially attenuated the median relative increase in plasma-CC16 concentrations (with HME + 27% (interquartile range 9–38) vs no-HME + 121% (55–162), p < 0.001) and reduced airway and general symptom intensity, compared to the trial without HME. No significant changes between trials were detected in urine CC16, 8-isoprostane, or cytokine concentrations.Conclusion: The HME attenuated acute airway responses induced by moderate-to-maximal-intensity exercise in − 15 °C in healthy subjects. Further studies are needed to examine whether this HMEs could constitute primary prevention against asthma in winter endurance athletes.
|
|
| 40. |
- Tinghög, Gustav, 1979-, et al.
(författare)
-
Horizontal Inequality in Rationing by Waiting Lists
- 2014
-
Ingår i: International Journal of Health Services. - : Baywood Publishing Company, Inc.. - 0020-7314 .- 1541-4469. ; 44:1, s. 169-184
-
Tidskriftsartikel (refereegranskat)abstract
- The objective of this article was to investigate the existence of horizontal inequality in access to care for six categories of elective surgery in a publicly funded system, when care is rationed through waiting lists. Administrative waiting time data on all elective surgeries (n = 4,634) performed in Östergötland, Sweden, in 2007 were linked to national registers containing variables on socioeconomic indicators. Using multiple regression, we tested five hypotheses reflecting that more resourceful groups receive priority when rationing by waiting lists. Low disposable household income predicted longer waiting times for orthopedic surgery (27%, p < 0.01) and general surgery (34%,p < 0.05). However, no significant differences on the basis of ethnicity and gender were detected. A particularly noteworthy finding was that disposable household income appeared to be an increasingly influential factor when the waiting times were longer. Our findings reveal horizontal inequalities in access to elective surgeries, but only to a limited extent. Whether this is good or bad depends on one's moral inclination. From a policymaker's perspective, it is nevertheless important to recognize that horizontal inequalities arise even though care is not rationed through ability to pay.
|
|
| 41. |
|
|
| 42. |
- Tutt, Alasdair, et al.
(författare)
-
A heat-and-moisture-exchanging mask affects each sex differently during exercise in sub-zero conditions
- 2020
-
Konferensbidrag (refereegranskat)abstract
- Purpose: To identify how performance is affected during maximal exercise in sub-zero conditions with the use of a heat-and-moisture-exchanging mask between men and women.Methods: 23 healthy participants (eight female, 15 male; age 18-53 y) performed two simulated four-minute competition efforts including a graded warm-up at -15℃ in randomized order either with or without mask first. Breathing frequency, heart rate and velocity were measured constantly. Capillary blood samples were collected 2 min pre-and post-maximal test.Results: There was an overall negative effect of the mask on performance for both sexes (Women: -5 ± 21m; Men: -17 ± 30m, p = 0.033). Female participants accumulated more blood lactate than men during the effort with mask (9.3 ± 3.1 vs. 7.8 ± 1.4 mmol⋅L-1, p = 0.044 ). Men had an increased breathing frequency in the first 80-s of the time trial with the mask (p < 0.05). Women exhibited more even pacing, whilst men tended towards a negative pacing strategy, this observation was not affected by the mask. There was no change in heart rate between trials in either sex.Conclusions: Competition performance in both sexes is hindered by wearing a mask in sub-zero conditions. The mechanisms through which this hindrance occurs are different between sexes.Practical applications: Men and women should consider whether using a mask in short competition efforts is worthwhile for them at -15℃. Future research is required around longer competitions in sub-zero conditions.
|
|
| 43. |
- Tutt, Alasdair, et al.
(författare)
-
Heat-and-moisture exchanging masks : Advantage or a hindrance during exercise in sub-zero conditions?
- 2020
-
Ingår i: Book of Abstracts of the 25th Annual Congress of the European College of Sport Science, 28th - 30th October, 2020.. - 9783981841435 ; , s. 49-50
-
Konferensbidrag (refereegranskat)abstract
- INTRODUCTION: Heat-and-moisture exchanging masks (HMEs) are commonly used by athletes experiencing cold-air induced airway obstructions such as exercise-induced asthma to negate symptoms in training and competition. These masks have been demonstrated as an effective intervention at wide ranging intensity levels and duration for preventing airway obstructions (3). A large proportion of cross-country skiers experience asthma symptoms whilst training and competing in cold conditions (1, 2). As large numbers of athletes in cross country skiing and other outdoor winter endurance sports train and compete in cold conditions around the globe, links have been inferred between prolonged cold air inhalation and the development of exercise-induced asthma (2). The aim of this study was to investigate the effect of an HME on the performance (defined as distance completed) of healthy people during a maximal self-paced exercise test. METHODS: Twenty-three healthy, well-trained participants (eight females, 15 males; age 18-53 y) performed two simulated competition efforts at -15 degrees Celsius in randomized order either with or without mask first. The protocol was 5 min each at 65, 70 and 75% of VO2 Max followed by 3 min at 90% VO2 Max and a further 12 min at 65% before a 5 min pause to simulate a competition warm up followed by a 4 min maximal self-paced running test. A t-test was performed to compare performance outcomes. Two-way repeated measures ANOVA was used to examine effects of trial order and gender on performance. Linear regressions were used to investigate relationships between key physiological and biometric data and the effect of the HME on performance. All statistical analyses were performed with R using the jamovi interface. The study was conducted according to the declaration of Helsinki and approved by the regional ethics committee. RESULTS: Participants ran significantly further without HME (Mean: 931m, SD: 106m) than with HME (Mean: 918m, SD: 110m, p=0.039). No significant effect of trial order was observed (p=0.816). Body mass negatively correlated with the magnitude of the effect of the mask on performance; participants with higher body mass had a greater negative effect of the mask (r2 = 0.215, p= 0.026). No relationships were found between the effect of the HME and sex, age, ventilation, absolute or relative VO2peak. CONCLUSION: Our findings suggest that HME usage hinders maximal running performance in healthy subjects to an extent that may be sufficient to alter competition outcomes. Potential effects of sex, body mass and performance level should also be investigated further. References: 1. Larsson, K. et al. (1993), Br Med J, 307(6915), pp. 1326–1329. 2. Eriksson, L. M. et al. (2018), Scand J Med Sci Sport, 28(1), pp. 180–186. doi: 10.1111/sms.12879. 3. Nisar, M. et al. (1992), Thorax, 47(6), p. 446. doi: 10.1136/thx.47.6.446.
|
|
| 44. |
- Tutt, Alasdair S., et al.
(författare)
-
A heat and moisture-exchanging mask impairs self-paced maximal running performance in a sub-zero environment
- 2021
-
Ingår i: European Journal of Applied Physiology. - : Springer. - 1439-6319 .- 1439-6327. ; 121:7, s. 1979-1992
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: Heat-and-moisture-exchanging devices (HME) are commonly used by endurance athletes during training in sub-zero environments, but their effects on performance are unknown. We investigated the influence of HME usage on running performance at − 15 °C.Methods: Twenty-three healthy adults (15 male, 8 female; age 18–53 years; V˙ O 2peak men 56 ± 7, women 50 ± 4 mL·kg−1·min−1) performed two treadmill exercise tests with and without a mask-style HME in a randomised, crossover design. Participants performed a 30-min submaximal warm-up (SUB), followed by a 4-min maximal, self-paced running time-trial (TT). Heart rate (HR), respiratory frequency (fR), and thoracic area skin temperature (Tsk) were monitored using a chest-strap device; muscle oxygenation (SmO2) and deoxyhaemoglobin concentration ([HHb]) were derived from near-infra-red-spectroscopy sensors on m. vastus lateralis; blood lactate was measured 2 min before and after the TT.Results: HME usage reduced distance covered in the TT by 1.4%, despite similar perceived exertion, HR, fR, and lactate accumulation. The magnitude of the negative effect of the HME on performance was positively associated with body mass (r2 = 0.22). SmO2 and [HHb] were 3.1% lower and 0.35 arb. unit higher, respectively, during the TT with HME, and Tsk was 0.66 °C higher during the HME TT in men. HR (+ 2.7 beats·min−1) and Tsk (+ 0.34 °C) were higher during SUB with HME. In the male participants, SmO2 was 3.8% lower and [HHb] 0.42 arb. unit higher during SUB with HME.Conclusion: Our findings suggest that HME usage impairs maximal running performance and increases the physiological demands of submaximal exercise.
|
|
| 45. |
- Tutt, Alasdair, et al.
(författare)
-
Sex differences in muscle oxygenation during sub-zero exercise with a heat-and-moisture exchanger
- 2020
-
Konferensbidrag (refereegranskat)abstract
- Purpose: To investigate whether use of an HME in sub-zero temperatures affects the physiological demands of fixed-intensity submaximal exercise, and whether the effect of the HME differed between sexes.Methods: Twenty-three healthy, trained participants (15 male, 8 female, VO2peak 57 ± 6 and 50 ± 4 mL·kg-1·min-1; mean ± SD) gave written, informed consent to participate in the study. Participants completed two experimental trials, with and without HME. Each experimental trial consisted of 30-min submaximal treadmill running in -15°C. Muscle oxygenation (SmO2) and relative deoxyhaemoglobin concentration [HHb] were determined using wireless near-infrared spectroscopy sensors placed bilaterally on m. vastus lateralis. Nineteen complete datasets were obtained (12 men and 7 women) and analysed using linear mixed models.Results: There were significant sex × trial interactions for SmO2 (p=0.007) and [HHb] (p=0.009); in the men only, SmO2 was lower (-3.8%, 95% CI: -1.9–-5.6%) and [HHb] was higher (0.42 AU, 95% CI: 0.2–0.65) from 5 min into the HME trial, whereas in the women there was no difference between trials.Conclusion: The lower SmO2 and higher [HHb] in the men during fixed-intensity exercise with HME indicates greater O2 extraction at the tissues. Thus, an HME could be interpreted as increasing the physiological demands of exercise in men. We could speculate that airflow limitation from the HME could be exacerbated by higher absolute rates of ventilation resulting in reduced tissue oxygen delivery.Practical Applications: Our observations could have implications for athletes when deciding whether to use an HME during training and competition.
|
|
| 46. |
|
|
