| 1. |
- Carlsson, Peter, et al.
(författare)
-
Cross-Country Ski
- 2015
-
Ingår i: The Engineering Approach to Winter Sports. - New York, NY : Springer. - 9781493930197 ; , s. 107-152
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Cross-country skiing, biathlon and ski orienteering are competitive sports with practitioners who are mostly from countries in the northern hemisphere. The competition season is during the time when the ground is covered with snow, which roughly extends from mid-November to late March. During the rest time of the year, which is a long preparatory period of training for the skiers before the competition season, the skiers use roller skis for dryland training with the aim of imitating skiing on snow. Furthermore, over the last few decades, fairly specific indoor testing methods for cross-country skiers have become possible due to the development of treadmills that allow roller skiing using classical and freestyle techniques.
|
|
| 2. |
- Ainegren, Mats, 1963-, et al.
(författare)
-
A Study of Skin-Close Heat and Moisture with Different Types of Backpacks in Cycling
- 2020
-
Ingår i: The 13th Conference of the International Sports Engineering Association. - Basel Switzerland : MDPI.
-
Konferensbidrag (refereegranskat)abstract
- The aim of this project was to evaluate effects of backpacks with different design intended for use during cycling on skin-close temperature and relative humidity, oxygen uptake, heart rate and aerodynamic drag. Seven subjects took part in the study cycling on a mountain bike mounted on a “smart trainer” placed on a force plate in a wind tunnel. Three series of experiments were carried out: without backpack, with conventional backpack and with a backpack having innovative rear panel design. As hypothesized, the results showed that an innovatively designed backpack with the ducts deflecting part of the airflow towards some areas of the user’s back provided lower temperature and relative humidity for the microclimate compared to a conventional backpack without airflow channels. Further, reference tests without any backpack resulted in the lowest temperature and humidity. However, no differences were found between the three tests for oxygen uptake, heart rate and aerodynamic drag.
|
|
| 3. |
|
|
| 4. |
- Arvidsson, Anna K, 1971-, et al.
(författare)
-
Dynamisk prognosstyrd vintervägdrift : Summering av Fas 1
- 2017
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Vinterväghållningens uppgift är att se till att vägar är tillräckligt framkomliga och säkra att åka på. Rent praktiskt innebär detta att med hjälp av plogning, sand- och saltspridning hålla vägarna tillräckligt snö- och isfria enligt de gällande reglerna. Inom operativ vinterväghållning är erfarenhet ofta en bristvara, det beror bland annat på den allt rörligare arbetsmarknaden med korta kontraktsperioder men även på de stora pensionsavgångarna som varit de senaste åren. För att beredskapshavaren ska bibehålla och samtidigt kunna öka produktiviteten är det väsentligt att beslutsstöd utvecklas.Det finns idag ett antal vägväderprognostjänster som kan leverera kvalificerat stöd till beslutstagare inom vinterväghållning. Som underlag används bland annat aktuell väderinformation från Trafikverkets VViS stationer (VägVäderinformationsSystem) som är utplacerade längs de statliga vägarna. Vissa tjänster använder även data från sensorer i bilar. Tjänsterna levererar dynamiska väglagsprognoser och i vissa fall även förslag på åtgärd för olika vägavsnitt. De levererar geografisk och tidsmässigt detaljerade beslutsunderlag som möjliggör högkvalitativa beslut för att göra rätt åtgärd i rätt tid på rätt plats. Den kanske främsta fördelen med prognoserna är att de tydligt påvisar att endast delar av vägnätet behöver åtgärdas samt att yttemperaturprognosen utöver väglagsprognosen är viktig information för att bestämma hur mycket salt som behövs för att vägen inte ska bli hal.Dagens ruttoptimeringsprogram genomför tidsoptimering (kortaste tid) på det vägnät som ska åtgärdas utifrån väghållarens vägklassindelning som baseras på mängden trafik (årsdygnsmedeltrafik). Vägklimatet kan dock variera kraftigt inom ett driftområde och det finns behov av att justera för dessa variationer för att kunna uppnå ökad resurseffektivitet. I dagsläget görs dessa korrigeringar manuellt för resursplanering och görs normalt inför varje vintersäsong.Syftet med projektet är att med dynamisk väglagsinformation skapa förutsättningar för dynamiska åtgärder för en mer produktiv vinterväghållning. Att integrera data från en vägväderprognostjänst i redan befintliga system, såsom ett förarstödssystem med ruttvisning skulle ge arbetsledningen möjlighet att arbeta betydligt mer detaljerat samt dynamiskt, vilket ger möjlighet för signifikanta effektivitetsökningar. I projektet har även en utvärdering av en vädertjänst gjorts med avseende på vilket prognosfönster som är lämpligt att använda i optimeringen. Projektet i denna första fas kan beskrivas som ett första försök att bygga ihop systemen samt validera att det är genomförbart och att resultatet blir pålitliga rutter för vinterväghållarna.Projektet har visat att en dynamisk prognosstyrd ruttplanering för preventiv saltning kan förbättra miljön genom en minskning av emissioner från väghållningsfordonen på grund av kortare körsträckor samt en minskad saltanvändning. Arbetsmiljön för saltbilsförarna förbättras genom en högre automatiseringsgrad vilket betyder att det är mindre att hålla reda på, detta leder till minskad stress vid höga utförandekrav. Bättre kvalité på vinterväghållningen gynnar även framkomligheten för trafikanterna.
|
|
| 5. |
- Arvidsson, Anna K, 1971-, et al.
(författare)
-
Dynamisk prognosstyrd vintervägdrift : Fas 2
- 2018
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Nyckfullt väder, korta tidsramar och höga kvalitetskrav kan göra vinterväghållningen till en utmaning. Pressen på både driftledningspersonal och maskinförare är under perioder väldigt hög. Vägklimatet kan variera kraftigt inom ett och samma driftområde och det finns behov att justera för dessa variationer för att maximera effektiviteten.Projektet ”Dynamisk prognosstyrd vintervägdrift” har haft syftet att utveckla en lösning för att förenkla hanteringen av dataflöden från vägväderprognoser och förenkla för beslutstagaren vilka åtgärder som behövs och var de behövs. Detta har gjorts genom att data från vägvädertjänster och det befintliga vägnätet i driftområdet har ruttoptimerats med antalet tillgängliga fordon, för att skapa förutsättningar för dynamiska åtgärder för en mer produktiv och hållbar vinterväghållning.Två av projektets faser har nu slutförts och syftet och målet att effektivisera driftverksamheten genom ihopkopplade dataflöden har uppnåtts. I samband med detta har även en produkt för prognosstyrd dynamisk ruttoptimering tagits fram. Projektet visade att med hjälp av prognosstyrd dynamisk ruttoptimering kan man realisera beslutsstödsystemens fulla potential genom automatisering. Potentialen i att använda prognosstyrd vinterväghållning är stor, såväl för kunderna som för den enskilda driftentreprenören. Entreprenören har nytta av det i det operativa arbetet, det förbättrar arbetsmiljön och kan minska kostnaderna. Men även påverkan på miljön minskar och långsiktigt minskar även samhällskostnaderna för drift och underhåll av vägar. Det är viktigt att understryka att tekniken möjliggör att säkerhetsfaktorn på vägen inte sänks trots besparingar av salt och åtgärdstider.
|
|
| 6. |
- Arvidsson, Anna K, 1971-, et al.
(författare)
-
Dynamisk prognosstyrd vinterväghållning – fas 3 & 4 : restsaltmodeller och automatisk saltspridning
- 2021
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I ett föränderligt klimat där allt större krav ställs på väghållare och vinterdriftsentreprenörer att åstadkomma en för trafikanterna acceptabel vintersdriftstandard samtidigt som de ekonomiska resurserna blir alltmer begränsade, ökar behoven av kostnadseffektiva metoder. Prognosstyrd dynamisk vägdrift har visat sig kunna leda till en ökad produktivitet då väglagsprognoser integreras med ruttoptimering. Ett sätt att vidareutveckla väglagsprognoserna är att veta hur mycket salt som behövs på vägen, eller mer exakt, hur mycket salt finns kvar? Om det redan finns salt på vägen, behöver du inte sprida hela mängden, det kan räcka med hälften eller ännu mindre. Restsaltmätningar har gjorts under tre vintersäsonger vid Testsite E18. Platsen valdes eftersom den är utrustad med flera olika sensorer, monterade över, bredvid och i vägen. Salt mättes var trettionde centimeter tvärs över vägens två körfält. Av 9 mätningar var det bara 5 tillfällen med salt varav två av dem saltades enbart för våra mätningar, kvar var tre mätningar med vinterförhållanden. Alla mätningar som gjordes jämfördes med sensorer monterade på testplatsen för att jämföra hur väl en sensor representerar vägytan. Det visade sig att det generellt var väldigt låga saltvärden från de monterade sensorerna jämfört med de manuella mätningarna.
|
|
| 7. |
- Berin, Emilia, 1992-
(författare)
-
Resistance Training and Physical Activity in Postmenopausal Women : Effects on Vasomotor Symptoms, Quality of Life and Microcirculation
- 2023
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background Menopause is a physiological event, but is associated with bothersome symptoms as well as physical changes that affect women’s health. About 75 % of women experience vasomotor symptoms (hot flushes and night sweats) related to menopause that often reduce quality of life. The vasomotor symptoms may be attributed to dysfunctional temperature regulation centrally in the hypothalamus and peripherally in the skin’s circulation. The most effective treatment for vasomotor symptoms is menopausal hormone therapy, but not all women are able to, or want to, use it. In addition to the impact on quality of life, studies have associated vasomotor symptoms and menopause with macrovascular endothelial dysfunction. Previous studies on the association of these factors with the skin’s microcirculatory function are small and few. Observational studies have associated physical activity and exercise with less vasomotor symptoms, but the evidence from intervention trials is of low quality and the results are ambiguous. Physical activity has established general health effects, and could potentially decrease vasomotor symptoms by effects on endogenous opioids centrally, and by more efficient thermoregulation peripherally. The aim of this thesis was to investigate the effect of resistance training on vasomotor symptoms and health-related quality of life in postmenopausal women, and to explore the women’s experiences of the training to find barriers and facilitators. We also aimed to investigate whether the skin’s microcirculatory function differed between women regarding menopausal status, vasomotor symptoms, menopausal hormone therapy, and physical activity. Material and methods The first study was an open randomized controlled trial including 65 postmenopausal women with moderate to severe vasomotor symptoms and low physical activity levels. We randomized the women to 15 weeks of resistance training (intervention) or unchanged physical activity (control). The participants registered vasomotor symptoms daily in a diary, and answered health-related quality of life questionnaires at baseline and at 15 weeks. The first 15 women to finish the intervention were recruited to a qualitative study. The women’s experiences of the resistance training intervention were explored in individual interviews after the intervention period, and all were followed-up with telephone interviews after one year. The third study was cross-sectional, including 1148 women from Linköping, 50-64 years old, who participated in the Swedish CArdioPulmonary bioImage Study (SCAPIS). These women answered a questionnaire about menopausal status, vasomotor symptoms and menopausal hormone therapy use, and wore accelerometers for seven days to assess physical activity. The skin’s microcirculation was assessed at rest and during post-occlusive reactive hyperemia. Results Moderate to severe vasomotor symptoms per 24 hours decreased significantly more in the group of women randomized to resistance training compared with the control group (mean difference -2.7, 95% CI -4.2 to -1.3). The resistance training group improved in domains of menopause-specific health-related quality of life compared with the control group but there was little impact on generic health-related quality of life. In the qualitative study we found that the vasomotor symptoms acted as a “trigger” for the women to become motivated to exercise. Their motivation then evolved from being driven by hopes of symptom relief into being driven by a wish for general well-being, which was still a driving force after one year. Microvascular function did not differ between postmenopausal and premenopausal women, or between women with or without vasomotor symptoms or menopausal hormone therapy. Women with higher levels of objectively measured and self-reported physical activity had a better reactivity of the skin’s microcirculation. The differences remained significant after adjusting for BMI, smoking, hypertension, diabetes, and education. Conclusions Resistance training could be effective for decreasing vasomotor symptoms and improving some aspects of health-related quality of life in motivated postmenopausal women. The vasomotor symptoms themselves spurred motivation to exercise, indicating they present an opportunity to increase physical activity. When a woman seeks medical advice for vasomotor symptoms, this could be a chance for health care professionals to help her initiate or increase exercise. Women who performed more physical activity and exercise had better skin microvascular function, but no association with VMS was found. Future studies are needed to investigate what type and dose of exercise is the most effective to reduce vasomotor symptoms and whether there is a way to predict for whom exercise will or will not be an effective intervention.
|
|
| 8. |
- Björkstrand, Thomas, et al.
(författare)
-
Svenskt teckenspråkslexikon
- 2010
-
Annan publikation (mjukvara/multimedium) (övrigt vetenskapligt/konstnärligt)
|
|
| 9. |
- Bäckström, Denise, 1976-, et al.
(författare)
-
Deaths caused by injury among people of working age (18-64) are decreasing, while those among older people (64+) are increasing.
- 2018
-
Ingår i: European Journal of Trauma and Emergency Surgery. - : Springer Science and Business Media LLC. - 1863-9933 .- 1863-9941. ; 44:4, s. 589-596
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Injury is an important cause of death in all age groups worldwide, and contributes to many losses of human and economic resources. Currently, we know a few data about mortality from injury, particularly among the working population. The aim of the present study was to examine death from injury over a period of 14 years (1999-2012) using the Swedish Cause of Death Registry (CDR) and the National Patient Registry, which have complete national coverage.METHOD: CDR was used to identify injury-related deaths among adults (18 years or over) during the years 1999-2012. ICD-10 diagnoses from V01 to X39 were included. The significance of changes over time was analyzed by linear regression.RESULTS: The incidence of prehospital death decreased significantly (coefficient -0.22, r (2) = 0.30; p = 0.041) during the study period, while that of deaths in hospital increased significantly (coefficient 0.20, r (2) = 0.75; p < 0.001). Mortality/100,000 person-years in the working age group (18-64 years) decreased significantly (coefficient -0.40, r (2) = 0.37; p = 0.020), mainly as a result of decrease in traffic-related deaths (coefficient -0.34, r (2) = 0.85; p < 0.001). The incidence of deaths from injury among elderly (65 years and older) patients increased because of the increase in falls (coefficient 1.71, r (2) = 0.84; p < 0.001) and poisoning (coefficient 0.13, r (2) = 0.69; p < 0.001).CONCLUSION: The epidemiology of injury in Sweden has changed during recent years in that mortality from injury has declined in the working age group and increased among those people 64 years old and over.
|
|
| 10. |
- Bäckström, Denise, 1976-
(författare)
-
Injury mortality in Sweden; changes over time and the effect of age and injury mechanism
- 2017
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Injuries are one of the most common causes of death in the world. Varying types of injuries dominate in different parts of the world, which also have separate influences mortality. In Scandinavia blunt injuries dominates and the majority of those who die do so pre hospital. Over time different injury pattern may vary and by analyzing this we can assess when, where and how preventive work can be reinforced. The aim of this thesis was to study injury epidemiology in Sweden and assess the contribution of different injury patters on mortality. Method: We used the Swedish cause of death and the national patient registries which have a complete national coverage. ICISS was calculated (based on ICD-10) in the in hospital population. We have chosen to do this investigation with a broad perspective using the term injury, which includes trauma but also other diagnoses like suffocation and drowning. Results: During the study period (1999-2012) the number of deaths because of injury was 1213, 25 388, and 18 332 among children, working age and elderly, respectively. Mortality declined in the children and in the working age but inclined in the elderly. Mortality increased with each age group except between the ages of 15–25 and 26–35 years. One thousand two hundred sixty four (97%) of those who died because of penetrating trauma (sharp objects and firearms) were killed by intentional trauma (assault and intentional self-harm). One thousand and seventeen (83%) of the children died prehospital. In the working age 22 211 (80%) of 25 388 died pre hospital. Nine thousand six hundred and eighteen (53%) of 18 332 of the elderly died prehospital. During 2001- 2011 the risk adjusted in hospital mortality decreased in traffic and assault but not in fall related injuries. Discussion: Largely, the anticipated injury mortality picture was found, with blunt injuries (traffic accidents) dominating in the working age and falls in elderly. Further a significant portion of the deaths occurred pre hospital. The intentional injuries are dominated by intentional selfharm. The decrease in child injury mortality is notable as Sweden already has one of the lowest incidences in child injury mortality in the world. The decrease in injury mortality in the working age also implies that preventive work has had an effect. The incline in injury mortality in elderly on the other hand needs to be further studied. Areas of particular importance for future preventive work is the incline in injury mortality in elderly and intentional injuries among children.
|
|
| 11. |
- Bäckström, Esmeralda, et al.
(författare)
-
The majority of patients report satisfaction more than 24 years after temporomandibular joint discectomy
- 2024
-
Ingår i: Oral and Maxillofacial Surgery. - : Springer Nature. - 1865-1550 .- 1865-1569.
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: To retrospectively evaluate long-term outcomes after temporomandibular joint (TMJ) discectomy.Methods: Included patients (n = 64) had undergone discectomy during 1989-1998 at Umeå University Hospital. A questionnaire was used to evaluate pre- and postoperative symptoms, postoperative complications, general pain, and subjective opinion about the outcome of the surgery.Results: The results are based on responses from 47 patients (40 women/7 men), including 36 (30 women/6 men) who completed the questionnaire and 11 (10 women/1 man) who were contacted by telephone and answered selected questions. Seventeen patients were excluded because of death, a move abroad, declining to participate, or no available patient information. Among the respondents, 41 (87%) were satisfied with the results, five (11%) were unsatisfied, and one (2%) patient did not answer the question. The results showed a significant long-term improvement in locking, clicking/crepitation, and pain when chewing or opening the jaw (p = 0.001). The prevalence of headaches had decreased significantly at follow-up (p = 0.001). Reported impaired jaw-opening capacity showed no significant improvement (p = 0.08). Of the 47 respondents, 19 (40%) had asked for additional treatment after the discectomy, and six of the 19 patients (13%) had undergone more surgery of the joint.Conclusion: The results of this retrospective long-term follow-up study indicate that TMJ discectomy has a high success rate, as most patients were satisfied with the postoperative results. Discectomy is thus an effective surgical intervention for patients with disabling TMJ pain and dysfunction when conservative interventions have been unsuccessful.
|
|
| 12. |
- Bäckström, Mikael, et al.
(författare)
-
A New Wind Tunnel Facility Dedicated to Sports Technology Research and Development
- 2016
-
Ingår i: Procedia Engineering. - : Elsevier. ; , s. 62-67
-
Konferensbidrag (refereegranskat)abstract
- It is desirable to test sportswear and sports equipment at exactly the same conditions experienced during use. Although outdoor tests are in many cases the most adequate, they are at the same time quite complex, demand special measurement technology and wearable equipment. Results of such tests are often hard to interpret due to large variations because of rapidly varying ambient conditions and individual specifics of human objects, among other factors, which are hard or impossible to control. One common alternative is provided through indoor tests made in a stable, controlled environment. Controlling such parameters as temperature, wind speed and direction, air humidity with indoor facilities intended to replicate ambient conditions, and designed to house large objects, is a complex undertaking. Furthermore, replicating seasonal conditions complicates matters even more. A significant amount of research and development related to the operation of sports and other related equipment at high speeds and windy conditions has been carried out in wind tunnels with different degrees of climatic realism. However, the majority of such facilities are designed and constructed for the automotive industry, the aerospace industry and for marine research. A new wind tunnel facility, opened in March 2015 at the Sports Tech Research Centre at Mid Sweden University, is currently among the very few facilities in the world designed under the direct control of sports technology specialists and dedicated primarily to research and development within sports, outdoor clothing and footwear as well as equipment development and testing. The main goal when constructing this dedicated facility has been to successfully replicate ambient conditions for training and equipment testing in environments with controlled wind speed, temperature (+4 to +35°C) and precipitation (from fine mist to heavy downfall). The wind tunnel facility houses the largest moving belt in Sweden (5 m long and 2.7 m wide) which can be adjusted for leveled, uphill and downhill motion. The moving belt is placed in a 10 m2 test section in which the wind speed can be adjusted to match belt speed or independently up to 55 km/h (without narrowing the test section). A fog and rain system, mounted in the test section, can generate rainy conditions varying from fine mist to heavy monsoon. It is also possible to open the facility in order to allow experiments to be performed in wide range of outdoor, ambient conditions. This paper presents the basic parameters of the new wind tunnel facility. As this facility is open for wider international cooperation, we also report the general directions of current research and the future work planned to be carried out at this facility.
|
|
| 13. |
|
|
| 14. |
- Bäckström, Mats G., et al.
(författare)
-
Can intentional electrical discharges be used for HPM protection?
- 2011
-
Ingår i: 2011 IEEE International Symposium on Electromagnetic Compatibility, EMC 2011; Long Beach, CA; 14 August 2011 through 19 August 2011. - 1077-4076. ; , s. 752-757
-
Konferensbidrag (refereegranskat)abstract
- The possibility to protect electronics against High Power Microwaves (HPM) using an intentional electrical discharge triggered by the HPM pulse has been investigated. The case considered is a resonant slot, located e.g. in an antenna array or in a Frequency Selective Surface (FSS). The reduction of the pulse energy transmitted through the slot is regarded to be the most important parameter of merit. Experimental and theoretical research showed that a spark in the middle of a 46.3 0.1 mm resonant slot, induced by the incident HPM-pulse, gave a reduction of the transmitted pulse energy of about 24 dB. The studies showed that the investigated approach can provide a quite good level of protection that at least reduces the requirements on additional protection components such as limiters integrated in receivers located behind the slot. In order to achieve a sufficiently strong enhancement of the electric field to initiate breakdown in wide slots one presumably has to introduce a small pointed gap in the middle of the slot. This may in turn require that a radioactive sample is located close to the gap in order to produce a sufficient number of seed electrons necessary for triggering the discharge. © 2011 IEEE.
|
|
| 15. |
- Bäckström, Mikael, 1963-, et al.
(författare)
-
People and Skis
- 2006
-
Ingår i: Science-First Hand. - Novosibirsk : INFOLIO Publishing House. - 1810-8520. ; :3, s. 110-125
-
Tidskriftsartikel (populärvet., debatt m.m.)
|
|
| 16. |
|
|
| 17. |
- Bäckström, Mikael, et al.
(författare)
-
Sports Technology Education at Mid Sweden University
- 2013
-
Ingår i: 6TH ASIA-PACIFIC CONGRESS ON SPORTS TECHNOLOGY (APCST). - : Elsevier. ; , s. 214-219
-
Konferensbidrag (refereegranskat)abstract
- In present paper we would like to share some experiences of building new education in Sports Technology at MidSweden University and the results of 10 years of successfully running it in Östersund. The Sports Technologyeducation at Mid Sweden University started at Campus Östersund in 2003 as a part of the curriculum of theEngineering Department. This specialization was initially at the three-year Bachelor level, and later it was extendedto an additional two-year Master level. Aiming at the quality of Sports Technology education, three keystones areunderlying its process, representing the solid knowledge base, capacity to be flexible in problem solving and the usean innovative approaches. The Department unites researches with a background in both natural sciences andengineering disciplines, having a wide experience of working with and within the industry, equally active in researchand teaching. The unique constellation of the profiles forming the Department include not only the SportsTech®group, being “the backbone”, but also the Ecology and Eco-technology, and Quality Technology groups bringing theexcellence and extra competence needed to assure the quality of the Sports Technology education. We were the firsthigher education institution in Sweden to give this kind of education program and now some other SwedishUniversities have followed us. Our success can be measured by a number of graduates taking good jobs in theindustry. We also enjoy a steady flow of new students coming from all parts of Sweden, and Sports Technologyeducation stays among the most desirable ones in the country.
|
|
| 18. |
- Bäckström, Torbjörn, et al.
(författare)
-
Paradoxical effects of GABA-A modulators may explain sex steroid induced negative mood symptoms in some persons
- 2011
-
Ingår i: Neuroscience. - Oxford : Elsevier BV. - 0306-4522 .- 1873-7544. ; 191:Special issue, s. 46-54
-
Forskningsöversikt (refereegranskat)abstract
- Some women have negative mood symptoms, caused by progestagens in hormonal contraceptives or sequential hormone therapy or by progesterone in the luteal phase of the menstrual cycle, which may be attributed to metabolites acting on the GABA-A receptor. The GABA system is the major inhibitory system in the adult CNS and most positive modulators of the GABA-A receptor (benzodiazepines, barbiturates, alcohol, GABA steroids), induce inhibitory (e.g. anesthetic, sedative, anticonvulsant, anxiolytic) effects. However, some individuals have adverse effects (seizures, increased pain, anxiety, irritability, aggression) upon exposure. Positive GABA-A receptor modulators induce strong paradoxical effects including negative mood in 3%-8% of those exposed, while up to 25% have moderate symptoms. The effect is biphasic: low concentrations induce an adverse anxiogenic effect while higher concentrations decrease this effect and show inhibitory, calming properties. The prevalence of premenstrual dysphoric disorder (PMDD) is also 3%-8% among women in fertile ages, and up to 25% have more moderate symptoms of premenstrual syndrome (PMS). Patients with PMDD have severe luteal phase-related symptoms and show changes in GABA-A receptor sensitivity and GABA concentrations. Findings suggest that negative mood symptoms in women with PMDD are caused by the paradoxical effect of allopregnanolone mediated via the GABA-A receptor, which may be explained by one or more of three hypotheses regarding the paradoxical effect of GABA steroids on behavior: (1) under certain conditions, such as puberty, the relative fraction of certain GABA-A receptor subtypes may be altered, and at those subtypes the GABA steroids may act as negative modulators in contrast to their usual role as positive modulators; (2) in certain brain areas of vulnerable women the transmembrane C1(-) gradient may be altered by factors such as estrogens that favor excitability; (3) inhibition of inhibitory neurons may promote disinhibition, and hence excitability. This article is part of a Special Issue entitled: Neuroactive Steroids: Focus on Human Brain. (C) 2011 Published by Elsevier Ltd on behalf of IBRO.
|
|
| 19. |
|
|
| 20. |
- Cronskär, Marie
(författare)
-
On customization of orthopedic implants - from design and additive manufacturing to implementation
- 2014
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This doctoral thesis is devoted to studying the possibilities of using additive manufacturing (AM) and design based on computed tomography (CT), for the production of patient-specific implants within orthopedic surgery, initially in a broad perspective and, in the second part of the thesis focusing on customized clavicle osteosynthesis plates. The main AM method used in the studies is the Electron Beam Melting (EBM) technology. Using AM, the parts are built up directly from 3D computer models, by melting or in other ways joining thin layers of material, layer by layer, to build up the part. Over the last 20 years, this fundamentally new way of manufacturing and the rapid development of software for digital 3D reconstruction of anatomical models from medical imaging, have opened up entirely new opportunities for the design and manufacturing of patient-specific implants. Based on the information in a computed tomography (CT) scan, both digital and physical models of the anatomy can be created and of implants that are customized based on the anatomical models. The main method used is a number of case studies performed, focusing on different parts of the production chain, from CT-scan to final implant, and with several aims: learning about the details of the different steps in the procedure, finding suitable applications, developing the method and trying it out. The first study was on customized hip stems, focusing on the EBM method and its special preconditions and possibilities. It was followed by a study of bone plates, designed to follow the patient-specific bone contour, in this case a tibia fracture including the whole production chain. Further, four cases of patient-specific plates for clavicle fracture fixation were performed in order to develop and evaluate the method. The plates fit towards the patient’s bone were tested in cooperation with an orthopedic surgeon at Östersund hospital. In parallel with the case studies, a method for finite element (FE) analysis of fixation plates placed on a clavicle bone was developed and used for the comparative strength analysis of different plates and plating methods. The loading on the clavicle bone in the FE model was defined on a muscle and ligament level using multibody musculoskeletal simulation for more realistic loading than in earlier similar studies. The initial studies (papers I and II) showed that the EBM method has great potential, both for the application of customized hip stems and bone plates; in certain conditions EBM manufacturing can contribute to significant cost reductions compared to conventional manufacturing methods due to material savings and savings in file preparation time. However, further work was needed in both of the application areas before implementation. The studies on the fracture fixation using patient-specific clavicle plates indicated that the method can facilitate the work for the surgeon both in the planning and in the operating room, with the potential of a smoother plate with a better fit and screw positioning tailored to the specific fracture (paper VI). However, a large clinical trial is required to investigate the clinical benefit of using patient-specific plates. The FE simulations showed similar stress distributions and displacements in the patient-specific plates and the commercial plates (papers III to VI). To summarize: the results of this thesis contribute to the area of digital design and AM in patient-specific implants with broad basis of knowledge regarding the technologies used and areas in which further work is needed for the implementation of the technology on a larger scale. Further, a method has been developed and initially evaluated for implementation in the area of clavicle fracture fixation, including an approach for comparing the strength of different clavicle plates.
|
|
| 21. |
|
|
| 22. |
|
|
| 23. |
- Delsing, Jerker, et al.
(författare)
-
Susceptibility of sensor networks to intentional electromagnetic interference
- 2006
-
Ingår i: 2006 17th International Zurich Symposium on Electromagnetic Compatibility. - Piscataway, NJ : IEEE Communications Society. - 3952299030 ; , s. 172-175
-
Konferensbidrag (refereegranskat)abstract
- It is reasonable to think that sensor networks might be part of society critical systems in the future. Therefor this paper discusses and shows the vulnerabilities of sensor networks to intentional electromagnetic interference (IEMI). Principle ways of sensor network IEMI is addressed and followed by a discussion on schemes for protection. Experimental results for both in-band and exband interference from low- and high- level sources is reported. It is obvious that more emphasis has to be put on sensor networks susceptibility to IEMI, and in particular more experimental data is needed.
|
|
| 24. |
|
|
| 25. |
|
|
| 26. |
- Fischer, Kerstin, 1951, et al.
(författare)
-
Immediate and early loading of oxidized tapered implants in the partially edentulous maxilla: a 1-year prospective clinical, radiographic, and resonance frequency analysis study.
- 2009
-
Ingår i: Clinical implant dentistry and related research. - : Wiley. - 1708-8208 .- 1523-0899. ; 11:2, s. 69-80
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The use of immediate/early implant loading protocols offers obvious advantages for the patient. Although well documented in the totally edentulous mandible, information about clinical outcomes from such protocols in the partially edentate maxilla is lacking. PURPOSE: The present study was conducted to clinically and radiographically evaluate a tapered implant design with an oxidized surface for immediate/early loading in the partially edentulous maxilla. The aim was also to correlate implant stability measurements using resonance frequency analysis (RFA) with implant diameter and length, bone quality and quantity, and marginal bone levels and marginal bone loss. MATERIALS AND METHODS: A total of 32 patients with a need of implant treatment in their partially edentulous maxilla were included in the study. A total of 53 Replace Select TiUnite implants (Nobel Biocare AB, Göteborg, Sweden) were used in the study; 16 for single tooth replacements in 16 patients and 37 implants for partial bridges in another 16 patients. The single tooth replacements were loaded the same day with a temporary crown, while permanent partial bridges were delivered within 16 days. Intraoral radiographs were taken at surgery and after 1 year for marginal bone measurements. RFA measurements were performed at baseline and after 3, 6, and 12 months. RESULTS: One implant used for a single tooth replacement failed, giving an overall survival rate of 98.1% after 1 year. On average, 1.1 mm (SD 1.0) bone was lost during 1 year; 1.5 mm (SD 1.0) in single tooth and 0.9 mm (SD 1.0) in partial cases. The implant stability increased with time from 63.3 implant stability quotient (ISQ) (SD 6.1) at baseline to 64.3 (SD 5.3), 65.0 (SD 4.6), and 66.8 (SD 5.6) after 3, 6, and 12 months, respectively. The average change from baseline to 1 year was 3.3 ISQ (SD 5.0) and was statistically significant (p < .05). There was no difference between single and partial cases. Implant stability correlated with bone quantity and quality at implant sites, but not with marginal bone level measurements. CONCLUSIONS: It is concluded that immediate/early loading can be used in the partially edentulous maxilla with good clinical and radiographic short-term outcomes. Implant stability at placement correlated with bone quantity and quality, and increased with time as measured with RFA, indicating a favorable bone tissue response to the loaded implants. Any correlations between RFA and marginal bone level measurements were not observed in the present study.
|
|
| 27. |
- Fridell, Mats, et al.
(författare)
-
Prediction of psychiatric comorbidity on premature death in a cohort of patients with substance use disorders : A 42-year follow-up
- 2019
-
Ingår i: BMC Psychiatry. - : Springer Science and Business Media LLC. - 1471-244X. ; 19:1, s. 150-150
-
Tidskriftsartikel (refereegranskat)abstract
- Background: We need to better understand how the use of different substances and psychiatric comorbidity influence premature death generally and cause-specific death by overdose, intoxication and somatic disorders in people with substance use disorders. Method: A cohort of 1405 patients consecutively admitted to a Swedish detoxification unit for substance use disorders in 1970-1995 was followed-up for 42 years. Substances were identified by toxicological analyses. Mortality figures were obtained from a national registry. Causes of death were diagnosed by forensic autopsy in 594 patients deceased by 2012. Predictions were calculated by competing risks analysis. Results: Forty-two per cent of the cohort died during follow-up; more men than women (46.3% vs 30.4%). The standardised mortality ratio (SMR) was calculated as the ratio of observed deaths in males and females in specific age groups in the cohort versus expected deaths in corresponding groups in the general population. SMR was 5.68 for men (CI 95%; 5.04-6.11) and 4.98 (CI 95%; 4.08-5.88) for women. The crude mortality rate (number of deaths divided by number of person observation years) was 2.28% for men and 1.87% for women. Opiates predicted increased risk of premature death while amphetamine and cannabis predicted lower risk. Comorbid psychiatric disorders were identified in 378 cases and personality disorders in 763 cases. Primary psychoses or mood/depression and anxiety disorders predicted a higher risk of premature mortality. Death by overdose was predicted by male gender, younger age at admission to substance treatment, opiate use, and comorbid depression and anxiety syndromes. Cannabis and amphetamine use predicted a lower risk of overdose. Death by intoxication was predicted by male gender, use of sedatives/hypnotics or alcohol/mixed substances, primary psychoses and depression/anxiety syndromes. Premature death by somatic disorder was predicted by male gender and alcohol/mixed abuse. Conclusion: Psychiatric comorbid disorders were important risk factors for premature drug-related death. Early identification of these factors may be life-saving in the treatment of patients with substance use disorders.
|
|
| 28. |
- Gatchell, Michael, et al.
(författare)
-
Commissioning of the DESIREE storage rings - a new facility for cold ion-ion collisions
- 2014
-
Ingår i: XXVIII International Conference on Photonic, Electronic and Atomic Collisions (ICPEAC 2013). - : Institute of Physics (IOP). ; 488:1
-
Konferensbidrag (refereegranskat)abstract
- We report on the ongoing commissioning of the Double ElectroStatic Ion Ring ExpEriment, DESIREE, at Stockholm University. Beams of atomic carbon anions (C-) and smaller carbon anion molecules (C-2(-), C-3(-), C-4(-) etc.) have been produced in a sputter ion source, accelerated to 10 keV or 20 keV, and stored successfully in the two electrostatic rings. The rings are enclosed in a common vacuum chamber cooled to below 13 Kelvin. The DESIREE facility allows for studies of internally relaxed single isolated atomic, molecular and cluster ions and for collision experiments between cat-and anions down to very low center-of-mass collision energies (meV scale). The total thermal load of the vacuum chamber at this temperature is measured to be 32 W. The decay rates of stored ion beams have two components: a non-exponential component caused by the space charge of the beam itself which dominates at early times and an exponential term from the neutralization of the beam in collisions with residual gas at later times. The residual gas limited storage lifetime of carbon anions in the symmetric ring is over seven minutes while the 1/e lifetime in the asymmetric ring is measured to be about 30 seconds. Although we aim to improve the storage in the second ring, the number of stored ions are now sufficient for many merged beams experiments with positive and negative ions requiring milliseconds to seconds ion storage.
|
|
| 29. |
- Gatchell, Michael, et al.
(författare)
-
First results from the Double ElectroStatic Ion-Ring ExpEriment, DESIREE
- 2014
-
Ingår i: XXVIII International Conference on Photonic, Electronic and Atomic Collisions (ICPEAC 2013). - : Institute of Physics (IOP). ; 488
-
Konferensbidrag (refereegranskat)abstract
- We have stored the first beams in one of the rings of the double electrostatic ion-storage ring, DESIREE at cryogenic and at room temperature conditions. At cryogenic operations the following parameters are found. Temperature; T= 13K, pressure; p <10(-13) mbar, initial number of stored ions; N > 10(7) and storage lifetime of a C-2(-) beam; tau = 450 S.
|
|
| 30. |
- Glazunov, Andrés Alayón, et al.
(författare)
-
Probability Distribution Function of the Electric Field Strength From a CW IEMI Source
- 2014
-
Ingår i: IEEE transactions on electromagnetic compatibility (Print). - 0018-9375 .- 1558-187X. ; 56:6, s. 1550-1558
-
Tidskriftsartikel (refereegranskat)abstract
- A statistical method for predicting the vulnerability of a target, i.e., critical equipment, located inside a building subject to a radiated Intentional Electromagnetic Interference (IEMI) source outside a building, has been devised. Combining probability density functions of small-and large-scale fluctuations of the electric field strength results in a Suzuki distributed electric field strength impinging at the equipment. Specifying the susceptibility level or the critical electric field strength of the target, the vulnerability of a target is evaluated as a function of the distance between source and target, taking into account losses from in and outside the building. Vulnerability isocontours defined as lines of constant probability of exceeding the susceptibility level are presented for a generic, continuous wave power source in a scenario emulating a dense urban microcell propagation environment. A comparison of the vulnerabilities predicted based on the Suzuki and the Log-normal distributions are also been provided for the same scenario. The proposed method provides estimates of critical distances of radiated IEMI attacks and may have use when deciding on the perimeter defense of a facility.
|
|
| 31. |
- Grigull, Susanne, et al.
(författare)
-
Enkätstudie – Insamling och lagring av bergtekniska och hydrogeologiska data
- 2020
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Insamling av bergtekniska och hydrogeologiska data sker kontinuerligt och i olika faser av bergbyggnadsprojekt. I nuläget är insamlingsprocesserna dock inte standardiserade och det finns inget centralt, nationellt system för att lagra insamlade data. Det är också svårt att värdera eller återanvända data från tidigare projekt och oftast måste all nödvändiga fältdata samlas in från noll inför nya infrastrukturprojekt, även i områden där det finns tidigare bergbyggnation. Arbete inför och under denna förstudie pekar på ett stort behov av dels en tydligare och delvis förbättrad metodik för insamling av data och dels önskemål om en nationell portal för åtkomst till arkiv och databaser, med information från tidigare bergbyggnadsprojekt i ett område.Med hjälp av två enkätstudier som skickades ut till olika aktörer i bergbyggbranschen har vi identifierat geologiska, bergtekniska och hydrogeologiska parametrar vars insamlingsmetodik och metodbeskrivningar är i behov av att förbättras och eventuellt standardiseras. Med hjälp av enkätsvaren har befintliga databaslösningar samt önskemål runt funktionaliteten av en framtida nationell databas också analyserats.Enkätstudien pekar också på att en standardisering av datainsamlingsprocessen är nödvändig för att säkerställa tillförlitligheten och spårbarheten av data, samt på att standardiserad metodik bör vara anpassad till projektkomplexitet och i möjligaste mån ansluta till nuvarande internationellt accepterad metodik. Studien visar dock även att bergbyggbranschens åsikter är mycket splittrade kring vissa frågor. Hur processen att driva utvecklingen och förvaltandet av metodik, metodbeskrivningar och dataportal/databas är inte heller självklart, eller hur detta ska finansieras och vilka förvaltande organ som ska ansvara.Det rekommenderas i denna förstudie att man vid en uppbyggnad av en nationell databas delar upp en sådan i ett sökbart dokumentarkiv och i en parameterdatabas. En eller flera statliga organisationer bör ha huvudansvaret för förvaltning.Föreliggande rapport är tänkt att tjäna som beslutsunderlag vid initiering och finansiering av projekt inom det aktuella området. Det rekommenderas starkt att den eller de organisationerna som ska bygga upp ett dokumentarkiv och en nationell parameterdatabas tar hänsyn till de funktionsönskemål som tas upp i rapporten.Notera att denna rapport även finns tillgänglig i PDF-format på Stiftelsen BergtekniskForskning – BeFos hemsida. Länkarna i rapporten kan enkelt öppnas direkt från PDF-filen och bilder kan förstoras.
|
|
| 32. |
- Hartman, Henrik, et al.
(författare)
-
First storage of ion beams in the Double Electrostatic Ion-Ring Experiment : DESIREE
- 2013
-
Ingår i: Review of Scientific Instruments. - : American Institute of Physics (AIP). - 0034-6748 .- 1089-7623. ; 84:5
-
Tidskriftsartikel (refereegranskat)abstract
- We report on the first storage of ion beams in the Double ElectroStatic Ion Ring ExpEriment, DESIREE, at Stockholm University. We have produced beams of atomic carbon anions and small carbon anion molecules (Cn-, n = 1, 2, 3, 4) in a sputter ion source. The ion beams were accelerated to 10 keV kinetic energy and stored in an electrostatic ion storage ring enclosed in a vacuum chamber at 13 K. For 10 keV C2- molecular anions we measure the residual-gas limited beam storage lifetime to be 448 s +/- 18 s with two independent detector systems. Using the measured storage lifetimes we estimate that the residual gas pressure is in the 10-14 mbar range. When high current ion beams are injected, the number of stored particles does not follow a single exponential decay law as would be expected for stored particles lost solely due to electron detachment in collision with the residual-gas. Instead, we observe a faster initial decay rate, which we ascribe to the effect of the space charge of the ion beam on the storage capacity.
|
|
| 33. |
- Holmberg, Ellinor, et al.
(författare)
-
Allopregnanolone involvement in feeding regulation, overeating and obesity
- 2018
-
Ingår i: Frontiers in neuroendocrinology (Print). - : Academic Press. - 0091-3022 .- 1095-6808. ; 48, s. 70-77
-
Forskningsöversikt (refereegranskat)abstract
- Obesity is strongly associated with ill health, primarily caused by consumption of excessive calories, and promoted (inter alia) by gamma-amino-butyric-acid (GABA) stimulating food intake by activating GABA(A) receptors (primarily with alpha 3 and alpha 2 subunits) in the hypothalamic arcuate nucleus and paraventricular nucleus. Allopregnanolone is a potent positive GABAA receptor modulating steroid (GAMS). As reviewed here, elevated allopregnanolone levels are associated with increases in food intake, preferences for energy-rich food, and obesity in humans and other mammals. In women with polycystic ovarian disease, high serum allopregnanolone concentrations are linked to uncontrolled eating, and perturbed sensitivity to allopregnanolone. Increases in weight during pregnancy also correlate with increases in allopregnanolone levels. Moreover, Prader-Willis syndrome is associated with massive overeating, absence of a GABA(A) receptor (with compensatory > 12-, > 5- and > 1.5-fold increases in alpha 4, gamma 2, and alpha 1, alpha 3 subunits), and increases in the alpha 4, beta x, delta receptor subtype, which is highly sensitive to allopregnanolone. GABA and positive GABA-A receptor modulating steroids like allopregnanolone stimulates food intake and weight gain.
|
|
| 34. |
- Koptioug, Andrei, 1956-, et al.
(författare)
-
Studying Moisture Transport Trough "Active" Fabrics Using Humidity-Temperature Sensor Nodes
- 2018
-
Ingår i: Proceedings, Volume 2, ISEA 2018. - Basel Switzerland : MDPI. ; , s. 230-
-
Konferensbidrag (refereegranskat)abstract
- Active fabrics providing better comfort of the garments and footwear rapidly become an essential part of our life. However, only limited information about the performance of such fabrics is commonly available for the garment and footwear designers, and tests are often done only with the final products. Thus development of the objective testing methods for the fabric assemblies containing microporous membranes and garments using them is one of the important topics. Garment tests in the climate chamber when exercising in windy and rainy conditions with a set of temperature and humidity sensors placed over the body allow comparing manufactured garments for thermal and humidity comfort. To allow for better material testing a new laboratory setup was developed for studying the dynamics of the humidity transport through different fabrics at realistic conditions in extension of the existing ISO test procedure. Present paper discusses the experimental procedures and first results acquired with new setup.
|
|
| 35. |
|
|
| 36. |
- Koptyug, Andrey, 1956-, et al.
(författare)
-
Cross-country ski vibrations and possible mechanisms of their influence on the free gliding
- 2012
-
Ingår i: Procedia Engineering. - : Elsevier BV. - 1877-7058. ; 34, s. 473-478
-
Tidskriftsartikel (refereegranskat)abstract
- Present paper describes the results of experimental studies on the self-induced and forced vibrations of loaded cross country skis and presents the discussion on the possible mechanisms causing such vibrations and the ways they can influence the friction between the ski running surface and the snow. Studied vibrations of gliding skis are most probably caused by the frictional effects. Mechanisms involved are similar to the ones causing the brake disc squeal or the violin string excitation by the bow. Major factors responsible for the development of these vibrations such as micro roughness of the surfaces, nonlinearities in the material properties, thermo-elastic instabilities and instabilities due to decreasing friction with increasing sliding velocity are also common for the case of gliding skis. The results of this study indicate that the ski vibration pattern both in amplitude and in frequency could influence the ski gliding properties. Though it seems quite feasible that the control of the cross country ski vibrations can improve the gliding performance, further systematic studies are needed to confirm it and to formulate the consecutive strategies of cross country ski design improvement.
|
|
| 37. |
- Koptyug, Andrey, et al.
(författare)
-
Gliding-induced ski vibrations : Approaching proper modeling
- 2014
-
Ingår i: Procedia Engineering. - : Elsevier BV. ; , s. 539-544
-
Konferensbidrag (refereegranskat)abstract
- Phenomena of the ski and snow boards vibrations generated in gliding are known for years. In the cross country and jumping skis such vibrations are not very obvious but can play quite positive role reducing the effective gliding friction. The research into the nature of friction-induced vibrations and the factors influencing their frequencies and magnitudes is driven by the desire to control them for improving ski gliding performance. Significant amount of experimental data acquired in the field and laboratory studies is already available making it possible to formulate certain qualitative conclusions. But so far it did not bring comprehensive understanding of the phenomenon and specifically of the mechanisms controlling such vibrations. Modeling is one of the potent tools allowing to deeper understand experimentally studied phenomena and it can provide much stronger quantitative prediction capacity. Present paper discusses possible approaches to modeling of the phenomenon and first results of constructing simplified models. © 2014 The Authors.
|
|
| 38. |
|
|
| 39. |
- Koptyug, Andrey, 1956-, et al.
(författare)
-
Possibility of modern humidity sensor application in the studies ofmoisture transport through the sports and outdoor garments
- 2016
-
Ingår i: icSPORTS 2016 - Proceedings of the 4th International Congress on Sport Sciences Research and Technology Support. - Portugal : SciTePress. - 9789897582059 ; , s. 51-58
-
Konferensbidrag (refereegranskat)abstract
- Sensor nodes containing pairs of temperature and humidity sensors were assessed as a mean of garmentperformance and comfort studies. Modern sensors are small, low weight and produce minimal disturbancewhen placed under the garments and in the footwear. Four sensor nodes were used to provide dynamicinformation about heat and humidity transfer properties of garments during the tests in realistic conditions.Pilot studies were carried out for the few models of cross country skiing garments and waders. Main studieswere carried out in the wind tunnel at Mid Sweden University having pivoted treadmill, temperature controland rain capacity. Additional experiments with the waders were carried out in a large water tank. Studies ofthe temperature and humidity dynamics under the garments containing microporous membranes illustratethe importance of recognizing main features of such materials. In particular, such membranes can onlytransport moisture from the side where humidity is higher. It means that garments and footwear containingsuch membranes will potentially behave differently when ambient air humidity changes. In particular,modern garments with incorporated microporous membranes being superior at low ambient air humidity canbe dramatically less effective for moisture transfer from the body in the rain.
|
|
| 40. |
- Koptyug, Andrey, 1956-, et al.
(författare)
-
Studies into the Mechanisms of the Cross-country Ski Vibrations and Possible Models of the Phenomenon
- 2013
-
Ingår i: 6TH ASIA-PACIFIC CONGRESS ON SPORTS TECHNOLOGY (APCST). - : Elsevier. ; , s. 40-45
-
Konferensbidrag (refereegranskat)abstract
- Field and laboratory measurements show a presence of intense cross-country ski vibrations during free gliding. Thereare indications that such vibrations may and indeed do affect the average friction forces and thus should affect the skigliding. Our studies into the nature of these vibrations and the factors influencing their frequencies and magnitudesare driven by the desire to control them for improving ski gliding performance. The complexity of the correspondingresonance system, represented by constant interaction of the skier, the skis and the snow, and the mechanisms of thevibration excitation, most probably dominated by the stochastic forces caused by a stick-slip character of the friction,demand new approaches to the modelling and experiments. Present paper describes some results of the experimentallaboratory studies of such vibrations, and possible approaches to their modelling following the routes suggested inmodelling of the similar phenomena.
|
|
| 41. |
- Larsen, Robert, 1980-, et al.
(författare)
-
Decreased risk adjusted 30-day mortality for hospital admitted injuries : a multi-centre longitudinal study
- 2018
-
Ingår i: Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine. - : BIOMED CENTRAL LTD. - 1757-7241. ; 26
-
Tidskriftsartikel (refereegranskat)abstract
- Background: The interpretation of changes in injury-related mortality over time requires an understanding of changes in the incidence of the various types of injury, and adjustment for their severity. Our aim was to investigate changes over time in incidence of hospital admission for injuries caused by falls, traffic incidents, or assaults, and to assess the risk-adjusted short-term mortality for these patients. Methods: All patients admitted to hospital with injuries caused by falls, traffic incidents, or assaults during the years 2001-11 in Sweden were identified from the nationwide population-based Patient Registry. The trend in mortality over time for each cause of injury was adjusted for age, sex, comorbidity and severity of injury as classified from the International Classification of diseases, version 10 Injury Severity Score (ICISS). Results: Both the incidence of fall (689 to 636/100000 inhabitants: p = 0.047, coefficient -4.71) and traffic related injuries (169 to 123/100000 inhabitants: p < 0.0001, coefficient -5.37) decreased over time while incidence of assault related injuries remained essentially unchanged during the study period. There was an overall decrease in risk-adjusted 30-day mortality in all three groups (OR 1.00; CI95% 0.99-1.00). Decreases in traffic (OR 0.95; 95% CI 0.93 to 0.97) and assault (OR 0.93; 95% CI 0.87 to 0.99) related injuries was significant whereas falls were not during this 11-year period. Discussion: Risk-adjustment is a good way to use big materials to find epidemiological changes. However after adjusting for age, year, sex and risk we find that a possible factor is left in the pre-and/or in-hospital care. Conclusions: The decrease in risk-adjusted mortality may suggest changes over time in pre-and/or in-hospital care. A non-significantdecrease in risk-adjusted mortality was registered for falls, which may indicate that low-energy trauma has not benefited for the increased survivability as much as high-energy trauma, ie traffic-and assault related injuries.
|
|
| 42. |
- Larsen, Robert, 1980-, et al.
(författare)
-
Female risk-adjusted survival advantage after injuries caused by falls, traffic or assault : a nationwide 11-year study
- 2019
-
Ingår i: Scandinavian Journal of Trauma, Resuscitation and Emergency Medicine. - : Springer Science and Business Media LLC. - 1757-7241. ; 27
-
Tidskriftsartikel (refereegranskat)abstract
- BackgroundA female survival advantage after injury has been observed, and animal models of trauma have suggested either hormonal or genetic mechanisms as component causes. Our aim was to compare age and risk-adjusted sex-related mortality in hospital for the three most common mechanisms of injury in relation to hormonal effects as seen by age.MethodsAll hospital admissions for injury in Sweden during the period 2001-2011 were retrieved from the National Patient Registry and linked to the Cause of Death Registry. The International Classification of Diseases Injury Severity Score (ICISS) was used to adjust for injury severity, and the Charlson Comorbidity Index to adjust for comorbidity. Age categories (0-14, 15-50, and 51years) were used to represent pre-menarche, reproductive and post- menopausal women.ResultsWomen had overall a survival benefit (OR 0.51; 95% CI 0.50 to 0.53) after adjustment for injury severity and comorbidity. A similar pattern was seen across the age categories (0-14years OR 0.56 (95% CI 0.25 to 1.25), 15-50years OR 0.70 (95% CI 0.57 to 0.87), and 51years OR 0.49 (95% CI 0.48 to 0.51)).ConclusionIn this 11-year population-based study we found no support for an oestrogen-related mechanism to explain the survival advantage for females compared to males following hospitalisation for injury.
|
|
| 43. |
- Li, Xuri, et al.
(författare)
-
PDGF-C is a new protease-activated ligand for the PDGF alpha-receptor.
- 2000
-
Ingår i: Nat Cell Biol. - : Springer Science and Business Media LLC. - 1465-7392 .- 1476-4679. ; 2:5, s. 302-9
-
Tidskriftsartikel (refereegranskat)abstract
- Platelet-derived growth factors (PDGFs) are important in many types of mesenchymal cell. Here we identify a new PDGF, PDGF-C, which binds to and activates the PDGF alpha-receptor. PDGF-C is activated by proteolysis and induces proliferation of fibroblasts when overexpressed in transgenic mice. In situ hybridization analysis in the murine embryonic kidney shows preferential expression of PDGF-C messenger RNA in the metanephric mesenchyme during epithelial conversion. Analysis of kidneys lacking the PDGF alpha-receptor shows selective loss of mesenchymal cells adjacent to sites of expression of PDGF-C mRNA; this is not found in kidneys from animals lacking PDGF-A or both PDGF-A and PDGF-B, indicating that PDGF-C may have a unique function.
|
|
| 44. |
- Lidar, Julius, 1984-
(författare)
-
Bioenergetic and Mechanical Modeling of Endurance Sports with Emphasis on Individualization
- 2023
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Endurance athletes strive to improve their race times by enhancing their physical abilities, techniques, tactics, and equipment. Numerical simulations can aid in this effort by enabling repeated testing under identical conditions, thus isolating the effect of a single variable of interest on race time. This thesis outlines the mechanical assumptions and mathematical formulations to conducting numerical simulations. Paper I exemplifies applications and limitations when using numerical simulations with a propulsive power model, by investigating the impact of dynamic friction on race times in cross-country skiing.Further, the thesis introduces bioenergetic modeling as a possible method for more accurately modeling an athlete’s propulsive power. It provides an overview of existing bioenergetic models and describes a non-linear grey-box parameter estimation method for individualizing bioenergetic model formulations to reflect an individual athlete’s bioenergetic systems. In Paper II, an assessment of validation for two existing bioenergetic models is performed on an individual level when applied to simulated sprint time trials in cross-country skiing. The models show overall good agreement with measurement data but lack the ability to capture the dynamics of the human metabolic energy systems in more detail.In Paper III, a new bioenergetic model is developed which describes the dynamic behavior of the metabolic energy supply systems and various sources of metabolic demand. The model is individualized and validated against intermittent cycling with varying power output. Although the model shows good agreement with measurements, it does not capture the details of the aerobic slow component and periods of recovery, indicating a need for continued development.
|
|
| 45. |
- Lindblom, Per, 1974, et al.
(författare)
-
Endothelial PDGF-B retention is required for proper investment of pericytes in the microvessel wall.
- 2003
-
Ingår i: Genes & development. - : Cold Spring Harbor Laboratory. - 0890-9369 .- 1549-5477. ; 17:15, s. 1835-40
-
Tidskriftsartikel (refereegranskat)abstract
- Several platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF) family members display C-terminal protein motifs that confer retention of the secreted factors within the pericellular space. To address the role of PDGF-B retention in vivo, we deleted the retention motif by gene targeting in mice. This resulted in defective investment of pericytes in the microvessel wall and delayed formation of the renal glomerulus mesangium. Long-term effects of lack of PDGF-B retention included severe retinal deterioration, glomerulosclerosis, and proteinuria. We conclude that retention of PDGF-B in microvessels is essential for proper recruitment and organization of pericytes and for renal and retinal function in adult mice.
|
|
| 46. |
- Löfgren, Mats, 1949-, et al.
(författare)
-
Decrease in serum concentration of 5α-pregnane-3,20-dione prior to spontaneous labor
- 1988
-
Ingår i: Acta Obstetricia et Gynecologica Scandinavica. - : wiley online library. - 0001-6349 .- 1600-0412. ; 67:5, s. 467-470
-
Tidskriftsartikel (refereegranskat)abstract
- Serum 5α-pregnane-3,20-dione (5αDHP) and progesterone (P) concentrations before spontaneous labor were studied in 13 women whose pregnancy and delivery were uncomplicated. Blood samples were drawn twice weekly from the 36th week of gestation up to the onset of spontaneous labor. P and 5αDHP values were analysed by applying RIA methods. Mean serum 5αDHP concentrations declined significantly during the last week of pregnancy, from 135±12 nmol/l 5 days prior to spontaneous labor, to 111 ±10 nmol/l on the day spontaneous labor started (p < 0.005). No significant changes in progesterone concentration occurred during the observation period. These results suggest a change in 5aDHP production preceding the onset of spontaneous labor.
|
|
| 47. |
- Löfgren, Mats, et al.
(författare)
-
Effects in vitro of progesterone and two 5 alpha-reduced progestins, 5 alpha-pregnane-3,20-dione and 5 alpha-pregnane-3 alpha-ol-20-one, on contracting human myometrium at term
- 1992
-
Ingår i: Acta Obstetricia et Gynecologica Scandinavica. - 0001-6349 .- 1600-0412. ; 71:1, s. 28-33
-
Tidskriftsartikel (refereegranskat)abstract
- Progesterone is known to prevent labour at term in domestic animals, but its effect in primates is uncertain. 5 alpha-reduced progesterone metabolites are more potent central nervous system depressants than progesterone is itself. Progesterone and its 5 alpha-reduced metabolites also relax pregnant rat myometrium in vitro. The serum concentration of the initial 5 alpha-reduced metabolite, 5 alpha-pregnane-3,20-dione, is high during pregnancy, but decreases significantly prior to parturition. The next metabolite, 5 alpha-pregnane-3 alpha-ol-20-one, has anaesthetic properties in human beings. The purpose of this study was to ascertain whether these progesterone metabolites also suppress contracting human uterine muscle at term. An in vitro model was devised. Strips of human myometrial muscle were mounted in organ chambers and after regular contractions had become established, the strips were superfused with progestin solutions. The progestins were dissolved in the buffer using an ultrasound bath. Progesterone, used as reference substance, slightly reduced the measured amount of muscular work performed per contraction, recordable after 18 min of exposure (p less than 0.05). Similar results have been reported previously in the literature; 5 alpha-pregnane-3 alpha-ol-20-one showed the same tendency though not significant at the 5% level. 5 alpha-pregnane-3,20-dione evidently reduced the contraction frequency after 10 min of exposure (p less than 0.05). None of the substances affected the duration of the contraction. These 5 alpha-reduced progesterone metabolites are thus not potent inhibitors of contracting human term myometrium in vitro.
|
|
| 48. |
- Löfgren, Mats, et al.
(författare)
-
High progesterone is related to effective human labor : study of serum progesterone and 5α-pregnane-3,20-dione in normal and abnormal deliveries
- 1997
-
Ingår i: Acta Obstetricia et Gynecologica Scandinavica. - 0001-6349 .- 1600-0412. ; 76:5, s. 423-430
-
Tidskriftsartikel (refereegranskat)abstract
- Background. The role of progesterone levels during human labor is unclear. Objective. To investigate serum concentrations of progesterone and 5α-pregnane-3,20-dione in normal and abnormal deliveries. Methods. Venous and umbilical cord serum samples were collected from 108 parturient women. In a further 49 deliveries, arterial and venous umbilical cord sera were collected separately. The concentrations of progesterone and 5opregnane-3,20-dione were determined by radioimmunoassay. The delivery modes studied were: elective cesarean section; oxytocin-resistant dystocia; normal but induced delivery, and normal spontaneous delivery. Results. Progesterone concentrations in maternal and umbilical serum were higher following normal labor than after dystocia (p<0.005) and elective cesarean section (p<0.005). The maternal and umbilical progesterone concentrations in dystocia and elective cesarean section were between 77–43 % of those in normal labor. The concentrations did not vary between gestational weeks 37 and 42, within the different modes of delivery. The 5α-pregnane-3,20-dione serum concentration in the fetal compartment was twice that in the maternal compartment (p<0.001); its concentration in venous umbilical serum was higher than in corresponding arterial samples (p<0.001). No distinct differences in the 5α-pregnane-3,20-dione serum concentration were found with regard to parity or mode of delivery. Conclusion. High progesterone concentrations during parturition appear to be related to effective labor. The findings support results from in vitro experiments on human term myometrium. Read More: http://informahealthcare.com/doi/abs/10.3109/00016349709047823
|
|
| 49. |
- Löfgren, Mats, et al.
(författare)
-
Progesterone concentrations in maternal and fetal serum are lower during functional dystocia than in normal labor
- 1992
-
Ingår i: Obstetrics and Gynecology. - 0029-7844 .- 1873-233X. ; 79:5, s. 752-759
-
Tidskriftsartikel (refereegranskat)abstract
- Concentrations of progesterone and estradiol (E2) were measured in parturient serum and in fetal cord serum during normal labor and in women with functional dystocia. In the study group, there were no cases of cephalopelvic disproportion. In oxytocin-resistant dystocia, the course of labor could not be corrected with oxytocin. To ascertain the effect of oxytocin, we included a number of women whose labor had been induced with oxytocin, followed by normal cervical dilatation and descent of the fetus. All the parturients were grouped retrospectively into those with normal labor and those with dystocia, based on previous definitions. The serum concentrations of progesterone in both the fetal cord and maternal vein were found to be significantly lower in the oxytocin-resistant dystocia group than in women in spontaneous normal labor and those with oxytocin-induced labor and normal progression (P < .05-.005). Oxytocin had no evident effect on the serum concentration of either progesterone or E2, nor did concentrations vary following epidural blockade. Serum E2 concentrations in the maternal vein were similar in all delivery groups. Fetal cord E2 serum concentrations were similar in all vaginal deliveries. Women with the most severe oxytocin-resistant dystocia, delivered by cesarean, had significantly lower serum concentrations of E2 in fetal cord serum compared with the vaginally delivered women (P < .001).
|
|
| 50. |
|
|
