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| 2. |
- Conache, Gabriela, et al.
(författare)
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Bias-controlled friction of InAs nanowires on a silicon nitride layer studied by atomic force microscopy
- 2010
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Ingår i: Physical Review B Condensed Matter. - College Park, Md. : American Physical Society. - 0163-1829 .- 1095-3795. ; 82:3
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Tidskriftsartikel (refereegranskat)abstract
- By studying how nanowires lying on a surface bend when pushed by an atomic force microscopy tip we are able to measure the friction between them and the substrate. Here, we show how the friction between InAs nanowires and an insulating silicon nitride layer varies when a dc voltage is applied to the tip during manipulation. The bias charges the capacitor formed by the wire and the grounded silicon back contact. Electrostatic forces increase the contact pressure and allow us to tune the friction between the wire and the silicon nitride surface. Using nanowires of about 40-70 nm diameter and a few microns in length we have applied biases in the range +12 to -12 V. A monotonic increase of the sliding friction with voltage was observed. This increase in friction with the normal force implies that the mesoscopic nanowire-surface system behaves like a macroscopic contact, despite the nanometer size of the contact in the direction of motion. The demonstrated bias-controlled friction has potential applications in MEMS/NEMS devices.
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| 4. |
- Fröberg, Andreas, 1985, et al.
(författare)
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Changes in Accelerometer-Measured Physical Activity and Sedentary Time Across Retirement Transition as a Predictor of Self-Rated Health
- 2024
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Ingår i: Journal of Physical Activity and Health. - 1543-3080.
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Tidskriftsartikel (refereegranskat)abstract
- Background: Retirement transition has shown to associate with changes in physical activity (PA) and self-rated health (SRH), but their interrelationship is less studied. The aim was to investigate changes in accelerometer measured total PA, moderate-to-vigorous PA (MVPA) and sedentary time across retirement transition as a predictor of self-rated health. Methods: Data from the Swedish Retirement Study and the Finnish Retirement and Aging study was harmonized and pooled. Data from three waves (about 12 months apart) was included: one pre-retirement (wave 1) and two post-retirement follow-ups (wave 2-3). Totally 245 participants (27% men) were included. Thigh-worn accelerometers were used to collect data for PA variables (wave 1-2), and SRH was obtained from the questionnaire (wave 1-3). Results: Between wave 1 and 2, total PA decreased with 11 (CI:-22;-1) minutes per day, MVPA was stable (0 [CI:-3;3] min), and sedentary time decreased non-significantly with 9 (CI:-20;1) minutes. SRH changed between all three waves (all, p<0.001). At pre-retirement, 10 more minutes of MVPA was associated with greater odds of better SRH when adjusting for accelerometer wear-time, cohort, sex and age, and occupational status (OR:1.11 (95%CI:1.02-1.22)). This association was no longer statistically significant when additionally adjusting for marital status, BMI, and smoking. No significant associations were observed between changes in the PA variables during retirement transition, and SRH at post-retirement follow-ups. Conclusion: This study showed a cross-sectional association between MVPA and greater odds of reporting better SRH before retirement. No longitudinal associations were observed between changes in the PA variables from before to after retirement and later change in SRH
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| 5. |
- Fröberg, Anders, et al.
(författare)
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Controlling Gear Engagement and disengagement on heavy trucks for minimization of fuel consumption
- 2005
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Ingår i: Proceedings of the 16th IFAC World Congress.
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Konferensbidrag (refereegranskat)abstract
- There is a potential to save fuel for heavy trucks by storing kineticenergy in the vehicle when driving downhill, because the speed adds kinetic energyto the vehicle which can be used after the downhill slope to propell the vehicle.This behavior can be even more utilized by disengaging the gear to reduce thefriction in the driveline and thus increase the speed even more. Two differentcontrol strategies to choose when to disengage the gear is presented: One schemethat uses instantaneous inclination and one predictive control scheme that useslook ahead information of the road topology. Simulation results show that geardisengagement in downhills can reduce the fuel consumption about 3%.
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| 7. |
- Fröberg, Andreas, 1985, et al.
(författare)
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Effects of an Empowerment-Based Health-Promotion School Intervention on Physical Activity and Sedentary Time among Adolescents in a Multicultural Area
- 2018
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Ingår i: International Journal of Environmental Research and Public Health. - Basel : MDPI. - 1661-7827 .- 1660-4601. ; 15:11
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Tidskriftsartikel (refereegranskat)abstract
- Physical activity (PA) decreases with age, and interventions are needed to promote PA during adolescence, especially, among those in low-socioeconomic status (SES) areas. The aim of this study was to investigate whether a two-year, empowerment-based health-promotion school intervention had any effects on changes in (a) moderate-to-vigorous PA (MVPA), (b) sedentary time (SED), (c) exercise training (ET) frequency, and (d) ET duration, among adolescents. Participants (aged 12-13 years at baseline) from one intervention school and two control schools, were recruited from a multicultural area of Sweden, characterized by low-SES. During the course of the two-year intervention, a total of 135 participants (43% boys) were included in the study. The intervention was developed and implemented as a result of cooperation and shared decision-making among the researchers and the participants. MVPA and SED were measured with accelerometers, and ET frequency and duration was self-reported at the beginning of the seventh, eighth, and ninth grade, respectively. There were no significant effects of the two-year, empowerment-based health-promotion school intervention on changes in the accelerometer-measured MVPA and SED, or the self-reported ET frequency and duration, among the adolescents. Overall, the intervention was unsuccessful at promoting PA and reducing SED. Several possible explanations for the intervention's lack of effects are discussed.
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| 8. |
- Fröberg, Mats, et al.
(författare)
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Long-term effects of experimental fertilization and soil warming on dissolved organic matter leaching from a spruce forest in Northern Sweden
- 2013
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Ingår i: Geoderma. - : Elsevier BV. - 0016-7061 .- 1872-6259. ; 200-201, s. 172-179
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Tidskriftsartikel (refereegranskat)abstract
- Nitrogen deposition and increasing temperature are two of the major large-scale changes projected for coming decades and the effect of this change on dissolved organic matter is largely unknown. We have utilized a long-term fertilization and soil warming experiment in Northern Sweden to study the effects of increased nutrient levels and increased temperature on DOC transport under the O horizon. The site is N limited and mean annual temperature 2. °C. Experimental fertilization with ammonium nitrate and a physiological mixture of other macro- and micro-nutrients has been going on for 22. years and soil warming, 5. °C above ambient soil temperature for 14. years, prior to the study. Experimental plots have been irrigated to avoid drying and we also studied the effect of this long-term irrigation on DOC by establishing control plots receiving no irrigation.DOC concentrations and fluxes under the O horizon were approximately 50% higher in fertilized plots than in non-fertilized control plots. We did not find any statistically significant effect of soil warming. There was a statistically significant effect of long-term irrigation on DOC with higher DOC concentration and fluxes in irrigated plots than in plots without irrigation. There were no major effects on DOC quality measured by specific UV absorbance. Fertilization approximately doubled soil organic matter stocks in the O horizon, whereas there were no such effects of warming or irrigation on soil organic matter amounts. There was no statistically significant treatment effect on DOC collected from the B horizon. We hypothesize that the positive effect of fertilization on DOC is related to increased soil C stocks.
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| 9. |
- Fuhrer, Andreas, et al.
(författare)
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Few electron double quantum dots in InAs/InP nanowire heterostructures
- 2007
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 7:2, s. 243-246
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Tidskriftsartikel (refereegranskat)abstract
- We report on fabrication of double quantum dots in catalytically grown InAs/InP nanowire heterostructures. In the few-electron regime, starting with both dots empty, our low-temperature transport measurements reveal a clear shell structure for sequential charging of the larger of the two dots with up to 12 electrons. The resonant current through the double dot is found to depend on the orbital coupling between states of different radial symmetry. The charging energies are well described by a capacitance model if next-neighbor capacitances are taken into account.
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| 10. |
- Halje, Karin, et al.
(författare)
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Towards mHealth Systems for Support of Psychotherapeutic Practice : A Qualitative Study of Researcher-Clinician Collaboration in System Design and Evaluation.
- 2016
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Ingår i: International Journal of Telemedicine and Applications. - : Hindawi Publishing Corporation. - 1687-6415 .- 1687-6423. ; 2016
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Tidskriftsartikel (refereegranskat)abstract
- We examined clinicians' and researchers' experiences from participation in collaborative research on the introduction of Internet and mobile information systems (mHealth systems) in psychotherapeutic routines. The study used grounded theory methodology and was set in a collaboration that aimed to develop and evaluate mHealth support of psychotherapy provided to young people. Soundness of the central objects developed in the design phase (the collaboration contract, the trial protocol, and the system technology) was a necessary foundation for successful collaborative mHealth research; neglect of unanticipated organizational influences during the trial phase was a factor in collaboration failure. The experiences gained in this study can be used in settings where collaborative research on mHealth systems in mental health is planned.
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