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| 3. |
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| 4. |
- Barrigón, E., et al.
(författare)
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GaAs Nanowire pn-Junctions Produced by Low-Cost and High-Throughput Aerotaxy
- 2018
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 18:2, s. 1088-1092
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Tidskriftsartikel (refereegranskat)abstract
- Semiconductor nanowires could significantly boost the functionality and performance of future electronics, light-emitting diodes, and solar cells. However, realizing this potential requires growth methods that enable high-throughput and low-cost production of nanowires with controlled doping. Aerotaxy is an aerosol-based method with extremely high growth rate that does not require a growth substrate, allowing mass-production of high-quality nanowires at a low cost. So far, pn-junctions, a crucial element of solar cells and light-emitting diodes, have not been realized by Aerotaxy growth. Here we report a further development of the Aerotaxy method and demonstrate the growth of GaAs nanowire pn-junctions. Our Aerotaxy system uses an aerosol generator for producing the catalytic seed particles, together with a growth reactor with multiple consecutive chambers for growth of material with different dopants. We show that the produced nanowire pn-junctions have excellent diode characteristics with a rectification ratio of >105, an ideality factor around 2, and very promising photoresponse. Using electron beam induced current and hyperspectral cathodoluminescence, we determined the location of the pn-junction and show that the grown nanowires have high doping levels, as well as electrical properties and diffusion lengths comparable to nanowires grown using metal organic vapor phase epitaxy. Our findings demonstrate that high-quality GaAs nanowire pn-junctions can be produced using a low-cost technique suitable for mass-production, paving the way for industrial-scale production of nanowire-based solar cells.
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| 5. |
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| 6. |
- Bratteby, L E, et al.
(författare)
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Whole-body mineral measurements in Swedish adolescents at 17 years compared to 15 years of age.
- 2002
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Ingår i: Acta Paediatrica. - 0803-5253 .- 1651-2227. ; 91:10, s. 1031-8
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Tidskriftsartikel (refereegranskat)abstract
- AIM: To provide reference data for bone mineral variables in 15- and 17-y-old adolescents and to analyse the relationships between these variables and measures of bone and body size, gender, puberty, growth, various lifestyle and environmental factors and socioeconomic background.METHODS: In the same 321 randomly selected adolescents (147 boys and 174 girls) living in two different regions of Sweden, the total bone mineral content (TBMC), bone area (BA) and total bone mineral density (TBMD) were assessed by dual-energy X-ray absorptiometry at ages 15 and 17 y. The effects of bone and body size, gender, growth, sexual maturity, physical activity, region of domicile, social conditions, food habits, smoking and alcohol intake on TBMC and TBMD were examined in multivariate analyses.RESULTS: In the 15-y-old adolescents, BA, height, gender, physical activity, maturity and weight explained 91% and 48%, of the variance in TBMC and TBMD, respectively. In similar analyses in the 17-y-olds, the corresponding figures were 92% and 62%, respectively, when BA, height, growth, physical activity, gender and region emerged as significant in the model. In all these analyses, BA explained most of the variance in TBMC and TBMD. No significant reduction of variance was found when different measures of social conditions, smoking, food habits, alcohol or dietary intakes of energy, calcium or vitamin D were included in the models. The reason why region of domicile had a significant impact on TBMC in the 17-y-olds is not known. The fact that the normal fluoride concentration in drinking water (1.1 mg/L) is 10 times higher in the region where TBMC was higher than in the other region is an interesting observation.CONCLUSION: Almost 90% of the variance in TBMC and 50% of that in TBMD was explained by measures of bone and body size and only a few percent by gender, physical activity, Tanner stage, growth and region of domicile.
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| 7. |
- Carlsson, N, et al.
(författare)
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IMPROVED SIZE HOMOGENEITY OF INP-ON-GAINP STRANSKI-KRASTANOW ISLANDS BY GROWTH ON A THIN GAP INTERFACE LAYER
- 1995
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Ingår i: Journal of Crystal Growth. - : Elsevier BV. - 0022-0248. ; 156:1-2, s. 23-29
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Tidskriftsartikel (refereegranskat)abstract
- Coherent InP nano-sized islands, embedded into GaInP, have been grown by metal-organic vapour phase epitaxy using the Stranski-Krastanow growth mode. Photoluminescence, atomic force microscopy and transmission electron microscopy studies show that the insertion of a thin ∼ 4 monolayer thick GaP layer affects the critical thickness of the subsequently deposited two-dimensional InP wetting layer, increasing it from ∼ 1.5 monolayers (without an inserted GaP layer) to ∼ 2.5 monolayers (with an inserted GaP layer). We demonstrate that the inserted GaP layer affects also the island formation. The bimodal size distribution of Stranski-Krastanow islands, typical for low InP coverages, can be overcome without island coalescence by deposition on top of the thin GaP layer, where a coverage of InP of about 3.5–4.5 monolayers results in the formation of almost only the larger, fully developed, pyramidal islands. Annealing experiments at growth temperature of 580°C show that these islands (base area ≈ 40 × 50 nm2, height ≈ 10–15 nm, surface density ≈ (1−2) × 109 cm−2) are rather stable in a time-scale over several minutes before they slowly undergo an Ostwald ripening process.
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| 11. |
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| 12. |
- Karlsson, L. S., et al.
(författare)
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Structural Characterisation of GaP <111 > B Nanowires by HRTEM
- 2008
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Ingår i: Microscopy of Semiconducting Material 2007. - 0930-8989. - 9781402086144 ; 120, s. 229-232
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Konferensbidrag (refereegranskat)abstract
- GaP < 111 > B nanowires are dominated by (111) twins orthogonal to the growth direction and show well-developed {111} side-facets. Based on this, a 3D-model has been constructed with a cross-section of an octahedron used as a building block. The twins can be of ortho- or para type i.e. by 60 degrees about the growth axis or 180 degrees in the twin plane. The segment thickness variation follows an exponential distribution with a clear dependence oil growth ternperature. Multislice simulations show different features of the twin types that are useful for further characterisation.
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| 13. |
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| 14. |
- Lantz, H, et al.
(författare)
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Differences in whole body measurements by DXA-scanning using two Lunar DPX-L machines
- 1999
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Ingår i: International journal of obesity and related metabolic disorders : journal of the International Association for the Study of Obesity. - : Springer Science and Business Media LLC. - 0307-0565. ; 23:7, s. 764-70
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To compare bone mineral and body composition results of two dual-energy X-ray absorptiometry (DXA) instruments from the same manufacturer.SETTINGS: The Medical departments of Sahlgrenska University Hospital, Göteborg and University Hospital, Uppsala, Sweden.DESIGN: Unique aluminium spine phantoms (Phant A and B) delivered with each DXA machine (DXA-A and DXA-B) were cross-checked on the other machine by using the 'AP spine mode'. Eight adolescents were examined on both instruments within 5 h to ascertain total body variables by using standard, as well as extended, modes of analysis. All these double-examinations were undertaken on two occasions, before and after exchange of a detector on the DXA-B.SUBJECTS: Four males and four females aged 15.4-19.2 y with normal body weights, were examined on both occasions. On each occasion, the first examination was performed in Göteborg on four individuals and in Uppsala on four individuals.RESULTS: On the first occasion the phantom measurements resulted in much lower bone mineral density (BMD) values on the DXA-B than on the DXA-A. Later it was detected that a so-called R-value and the corresponding '%-fat' value were out of range on the DXA-B. After exchange of detector, the difference in phantom BMD-values between the two machines had diminished. On the first occasion in vivo BMD values were lowest on the DXA-B (P < 0.01), while on the second occasion they were significantly lower on the DXA-A (P < 0.05). Soft tissue differences were greater after detector exchange and as compared to DXA-A, DXA-B underestimated body fat by 3.5 kg (13.2 vs 9.7 kg, P < 0.001) and overestimated lean tissue mass by 3.8 kg (47.1 vs 50.9 kg, P < 0.001) on the second occasion.CONCLUSIONS: The differences in results between two apparently identical Lunar DPX-L machines were not acceptable. In multicenter studies, it may be necessary to standardise results of participating machines into results of one machine by means of regression equations obtained by examining subsamples of individuals on one master machine and other participating instruments.
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| 15. |
- Lindquist, B, et al.
(författare)
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"Hälsokost" som barnmat
- 1975
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Ingår i: Läkartidningen. - 0023-7205 .- 1652-7518. ; 72:9
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 16. |
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| 17. |
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| 18. |
- Lötborn, M, et al.
(författare)
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Whole-body bone mineral measurements in 15-year-old Swedish adolescents.
- 1999
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Ingår i: Osteoporosis International. - : Springer Science and Business Media LLC. - 0937-941X .- 1433-2965. ; 9:2, s. 106-14
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Tidskriftsartikel (refereegranskat)abstract
- Bone mineral area (BA), total bone mineral content (TBMC) and total bone mineral density (TBMD) were assessed by dual-energy X-ray absorptiometry (DXA) in 396 randomly selected, healthy 15-year-old Swedish boys and girls. The influence of body size, pubertal development, physical activity level (PAL), total energy expenditure (TEE), dietary intake of energy, calcium and vitamin D, and alcohol and smoking habits on TBMC and TBMD were examined in bi- and multivariate analyses. In bivariate analyses BA, TBMC and TBMD showed strong correlations with weight, height and TEE in both sexes. In boys but not in girls these bone variables were significantly correlated with dietary intakes of energy, calcium and vitamin D. No significant correlations were found between PAL and the three bone variables. In multivariate analyses with TBMC as dependent variable BA, height, weight and Tanner stages explained 88% and 87% of the variance in boys and girls respectively. In similar analyses with TBMD as dependent variable the corresponding figures were 50% and 54%. The major part of the variance in all these models was explained by BA, and only a few percent by all the other independent variables. No significant reduction was found when TEE or daily intakes of calcium or vitamin D were introduced into the models. These results illustrate the importance of including BA, weight and height as independent variables in regression models of TBMC to avoid spurious associations with other variables in the analyses. The results may also indicate that in normal Swedish adolescents environmental factors such as dietary intake of nutrients play a minor role as determinants of bone mineralization. High levels of physical activity and bone mineral measures possibly explain the lack of significant correlations between these variables and do not imply a lack of association.
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| 19. |
- MONTELIUS, L, et al.
(författare)
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CHARACTERIZATION OF THE MN ACCEPTOR LEVEL IN GAAS
- 1988
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Ingår i: Journal of Applied Physics. - CIRCULATION FULFILLMENT DIV, 500 SUNNYSIDE BLVD, WOODBURY, NY 11797-2999 : AIP Publishing. - 0021-8979 .- 1089-7550. ; 64, s. 1564-1567
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Tidskriftsartikel (refereegranskat)
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| 20. |
- Mårtensson, T, et al.
(författare)
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III-V nanowires on Si and nanowire arrays
- 2005
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Ingår i: Book of abstracts: 342nd WE-Heraeus-Seminar Sci and Technol of Inorganic Nanowires, Bad Honnef, Germany (2005).
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 21. |
- Ohlsson, B. J., et al.
(författare)
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Size-, shape-, and position-controlled GaAs nano-whiskers
- 2001
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 79:20, s. 3335-3337
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Tidskriftsartikel (refereegranskat)abstract
- We have developed a technique for the synthesis of size-selected, GaAs, epitaxial nano-whiskers, grown on a crystalline substrate. As catalysts, we used size-selected gold aerosol particles, which enabled us to fully vary the surface coverage independently of the whisker diameter. The whiskers were rod shaped, with a uniform diameter between 10 and 50 nm, correlated to the size of the catalytic seed. Furthermore, by the use of nano-manipulation of the aerosol particles by means of atomic force microscopy, we can nucleate individual nano-whiskers in a controlled manner at specific positions on a substrate with accuracy on the nm level.
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| 22. |
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| 23. |
- Vasen, T., et al.
(författare)
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InAs nanowire GAA n-MOSFETs with 12-15 nm diameter
- 2016
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Ingår i: 2016 IEEE Symposium on VLSI Technology, VLSI Technology 2016. - 9781509006373 ; 2016-September
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Konferensbidrag (refereegranskat)abstract
- InAs nanowires (NW) grown by MOCVD with diameter d as small as 10 nm and gate-All-Around (GAA) MOSFETs with d = 12-15 nm are demonstrated. Ion = 314 μA/μm, and Ssat =68 mV/dec was achieved at Vdd = 0.5 V (Ioff = 0.1 μA/μm). Highest gm measured is 2693 μS/μm. Device performance is enabled by small diameter and optimized high-k/InAs gate stack process. Device performance tradeoffs between gm, Ron, and Imin are discussed.
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| 24. |
- Von Post-Skagegård, M, et al.
(författare)
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Changes in food habits in healthy Swedish adolescents during the transition from adolescence to adulthood
- 2002
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Ingår i: European Journal of Clinical Nutrition. - : Springer Science and Business Media LLC. - 0954-3007 .- 1476-5640. ; 56:6, s. 532-8
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To investigate the change in food habits in Swedish adolescents between 15 and 21 y of age with reference to age, sex, region and socioeconomic background. DESIGN: A longitudinal study from 1993 to 1999. SETTING: Two different regions in Sweden, the university city of Uppsala and the industrial town of Trollhättan. SUBJECTS: On three different occasions, 1993, 1995 and 1999, 208 adolescents, 96 males and 112 females, were studied. METHODS: A food frequency questionnaire containing 29 different food groups was used. The questionnaire also contained questions about food habits and amounts of some food items and socioeconomic conditions of the participants and their families. RESULTS: At 17 and 21 y of age, the adolescents consumed significantly more often pasta, vegetables, coffee and tea compared to age 15, while the frequency consumption of fat spread, milk, bread, potatoes, carrots and buns and biscuits decreased. The changes between 15 and 17 were smaller than between age 17 and 21. At age 21, the males decreased their intake of fruit, while the females decreased their intake of meat. No-meat consumers among females increased from 2 to 13%. Higher educational level of the mothers of the adolescents was associated with more frequent consumption of vegetables and pasta between ages 17 and 21. Milk consumption decreased significantly in both sexes. Breakfast habits did not change: 90% had breakfast five times/week or more. CONCLUSIONS: Food habits change significantly during adolescence along with lifestyle changes. Therefore, health promotion during adolescence ought to be more supported by the society.
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| 25. |
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| 26. |
- Baba, S., et al.
(författare)
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Cooper-pair splitting in two parallel InAs nanowires
- 2018
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Ingår i: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 20:6
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Tidskriftsartikel (refereegranskat)abstract
- We report on the fabrication and electrical characterization of an InAs double-nanowire (NW) device consisting of two closely placed parallel NWs coupled to a common superconducting electrode on one side and individual normal metal leads on the other. In this new type of device we detect Cooper-pair splitting (CPS) with a sizeable efficiency of correlated currents in both NWs. In contrast to earlier experiments, where CPS was realized in a single NW, demonstrating an intrawire electron pairing mediated by the superconductor (SC), our experiment demonstrates an interwire interaction mediated by the common SC. The latter is the key for the realization of zero-magnetic field Majorana bound states, or Parafermions; in NWs and therefore constitutes a milestone towards topological superconductivity. In addition, we observe transport resonances that occur only in the superconducting state, which we tentatively attribute to Andreev bound states and/or Yu-Shiba resonances that form in the proximitized section of one NW.
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| 27. |
- Baba, S., et al.
(författare)
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Gate tunable parallel double quantum dots in InAs double-nanowire devices
- 2017
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 111:23
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Tidskriftsartikel (refereegranskat)abstract
- We report fabrication and characterization of InAs nanowire devices with two closely placed parallel nanowires. The fabrication process we develop includes selective deposition of the nanowires with micron scale alignment onto predefined finger bottom gates using a polymer transfer technique. By tuning the double nanowire with the finger bottom gates, we observed the formation of parallel double quantum dots with one quantum dot in each nanowire bound by the normal metal contact edges. We report the gate tunability of the charge states in individual dots as well as the inter-dot electrostatic coupling. In addition, we fabricate a device with separate normal metal contacts and a common superconducting contact to the two parallel wires and confirm the dot formation in each wire from comparison of the transport properties and a superconducting proximity gap feature for the respective wires. With the fabrication techniques established in this study, devices can be realized for more advanced experiments on Cooper-pair splitting, generation of Parafermions, and so on.
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| 28. |
- Balocco, C, et al.
(författare)
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Microwave detection at 110 GHz by nanowires with broken symmetry
- 2005
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Ingår i: Nano Letters. - : American Chemical Society (ACS). - 1530-6992 .- 1530-6984. ; 5:7, s. 1423-1427
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Tidskriftsartikel (refereegranskat)abstract
- By using arrays of nanowires with intentionally broken symmetry, we were able to detect microwaves up to 110 GHz at room temperature. This is, to the best of our knowledge, the highest speed that has been demonstrated in different types of novel electronic nanostructures to date. Our experiments showed a rather stable detection sensitivity over a broad frequency range from 100 MHz to 110 GHz. The novel working principle enabled the nanowires to detect microwaves efficiently without a dc bias. In principle, the need for only one high-resolution lithography step and the planar architecture allow an arbitrary number of nanowires to be made by folding a linear array as many times as required over a large area, for example, a whole wafer. Our experiment on 18 parallel nanowires showed a sensitivity of approximately 75 mV dc output/mW of nominal input power of the 110 GHz signal, even though only about 0.4% of the rf power was effectively applied to the structure because of an impedance mismatch. Because this array of nanowires operates simultaneously, low detection noise was achieved, allowing us to detect -25 dBm 110 GHz microwaves at zero bias with a standard setup.
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| 29. |
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| 30. |
- Barany, E, et al.
(författare)
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Mercury and selenium in whole blood and serum in relation to fish consumption and amalgam fillings in adolescents
- 2003
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Ingår i: Journal of Trace Elements in Medicine and Biology. - 1878-3252 .- 0946-672X. ; 17:3, s. 165-170
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Tidskriftsartikel (refereegranskat)abstract
- Mercury and selenium in whole blood and serum of 245 17-year old Swedish adolescents were analysed. The relationships between these elements' concentrations and the consumption of fish as well as the number of dental amalgam fillings were studied. The geometric means (GM) of the mercury concentrations were 1.1 mug/L in blood and 0.43 mug/L in serum. The mean selenium concentration in blood was 110 mug/L and the GM of the serum selenium concentration 110 mug/L. Fish species with dietary restrictions due to elevated mercury Levels (i.e. pike, perch, pikeperch, burbot, eel and halibut) were consumed on average 0.7 times/month and fish species without such restrictions 4.1 times/month. Despite this comparatively Low fish consumption, the adolescents' blood mercury concentrations were positively correlated with fish consumption. Of the adolescents, 39% had amalgam fillings (mean 2 +/- 1.5). Serum mercury was influenced by the number of amalgam fittings, by fish consumption, blood and serum levels of selenium and the residential area. Blood and serum selenium concentrations were not influenced by fish consumption, but were positively associated with the serum mercury concentration.
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| 31. |
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| 32. |
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| 33. |
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| 34. |
- Bi, Zhaoxia, et al.
(författare)
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High In-content InGaN nano-pyramids : Tuning crystal homogeneity by optimized nucleation of GaN seeds
- 2018
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 123:2
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Tidskriftsartikel (refereegranskat)abstract
- Uniform arrays of submicron hexagonal InGaN pyramids with high morphological and material homogeneity, reaching an indium composition of 20%, are presented in this work. The pyramids were grown by selective area metal-organic vapor phase epitaxy and nucleated from small openings in a SiN mask. The growth selectivity was accurately controlled with diffusion lengths of the gallium and indium species, more than 1 μm on the SiN surface. High material homogeneity of the pyramids was achieved by inserting a precisely formed GaN pyramidal seed prior to InGaN growth, leading to the growth of well-shaped InGaN pyramids delimited by six equivalent 10 1 ̄ 1 facets. Further analysis reveals a variation in the indium composition to be mediated by competing InGaN growth on two types of crystal planes, 10 1 ̄ 1 and (0001). Typically, the InGaN growth on 10 1 ̄ 1 planes is much slower than on the (0001) plane. The formation of the (0001) plane and the growth of InGaN on it were found to be dependent on the morphology of the GaN seeds. We propose growth of InGaN pyramids seeded by 10 1 ̄ 1-faceted GaN pyramids as a mean to avoid InGaN material grown on the otherwise formed (0001) plane, leading to a significant reduction of variations in the indium composition in the InGaN pyramids. The InGaN pyramids in this work can be used as a high-quality template for optoelectronic devices having indium-rich active layers, with a potential of reaching green, yellow, and red emissions for LEDs.
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| 35. |
- Bi, Zhaoxia, et al.
(författare)
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Self-assembled InN quantum dots on side facets of GaN nanowires
- 2018
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 123:16
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Tidskriftsartikel (refereegranskat)abstract
- Self-assembled, atomic diffusion controlled growth of InN quantum dots was realized on the side facets of dislocation-free and c-oriented GaN nanowires having a hexagonal cross-section. The nanowires were synthesized by selective area metal organic vapor phase epitaxy. A 3 Å thick InN wetting layer was observed after growth, on top of which the InN quantum dots formed, indicating self-assembly in the Stranski-Krastanow growth mode. We found that the InN quantum dots can be tuned to nucleate either preferentially at the edges between GaN nanowire side facets, or directly on the side facets by tuning the adatom migration by controlling the precursor supersaturation and growth temperature. Structural characterization by transmission electron microscopy and reciprocal space mapping show that the InN quantum dots are close to be fully relaxed (residual strain below 1%) and that the c-planes of the InN quantum dots are tilted with respect to the GaN core. The strain relaxes mainly by the formation of misfit dislocations, observed with a periodicity of 3.2 nm at the InN and GaN hetero-interface. The misfit dislocations introduce I1 type stacking faults (...ABABCBC...) in the InN quantum dots. Photoluminescence investigations of the InN quantum dots show that the emissions shift to higher energy with reduced quantum dot size, which we attribute to increased quantum confinement.
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| 36. |
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| 37. |
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| 38. |
- Bratteby, L E, et al.
(författare)
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A 7-day activity diary for assessment of daily energy expenditure validated by the doubly labelled water method in adolescents.
- 1997
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Ingår i: European Journal of Clinical Nutrition. - 0954-3007 .- 1476-5640. ; 51:9, s. 585-91
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To validate the use of an activity diary and predicted BMR for assessment of daily total energy expenditure (TEE) and physical activity level (PAL = TEE/BMR) in adolescents.DESIGN: TEE and PAL estimated from activity diary records kept for seven days and BMR predicted from age, gender and body weight were compared with the results of doubly labelled water (DLW) measurements and indirect calorimetry performed during the same time period.SETTING: The Unit of paediatric Physiology of the Department of Clinical Physiology, University Hospital, Uppsala, Sweden.SUBJECTS: Fifty randomly selected 15 y old adolescents (25 boys and 25 girls).RESULTS: The mean difference between TEE estimated in all adolescents by the activity diary and by DLW methods was 1.2%. The limits of agreement (mean difference 2 s.d.) were -3.47 and 3.77 MD/d, equivalent to a coefficient of variation of 15%. The mean difference between PAL assessed by activity diary records and by DLW measurements was 0.001, and the limits of agreement between the two methods were 0.54.CONCLUSIONS: The results imply that the activity diary method provides a close estimate of TEE and PAL in population groups.
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| 39. |
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| 40. |
- Bratteby, L E, et al.
(författare)
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Daily energy expenditure and physical activity assessed by an activity diary in 374 randomly selected 15-year-old adolescents.
- 1997
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Ingår i: European Journal of Clinical Nutrition. - 0954-3007 .- 1476-5640. ; 51:9, s. 592-600
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: To assess the average daily levels of physical activity, energy expenditure and the time and energy spent a different activities in two cohorts of Swedish adolescents.DESIGN: Total energy expenditure (TEE) and physical activity level (PAL = TEE/basal metabolic rate (BMR)) were estimated in 374 randomly selected healthy adolescents living with two different regions of Sweden on the basis of a seven-day activity diary (AD) and predicted BMR. A validation of the estimates from the AD with the doubly labelled water (DLW) method in a randomly selected subsample of 50 of these subjects is presented elsewhere.SETTING: The Unit of Paediatric of the Department of Clinical Physiology, University Hospital, Uppsala and the Department of Paediatrics, Northern Alvsborg Hospital, Trollhättan, Sweden.RESULTS: No significant differences in TEE and PAL were found between the adolescents of the two regions. High levels of TEE (14.2 and 10.9 MJ/d in boys and girls, respectively) and PAL (1.95 and 1.80) were observed. There was a close association between the PAL and the adolescents and their reported time spent sitting. Those with the lowest PAL values spent 3-6 h longer each day sitting compared to those with the highest PAL values. The results also indicate that everyday activities such as walking and bicycling have a crucial impact on the PAL values.CONCLUSIONS: In the 15 y old adolescents of the two studied regions of Sweden, high and concordant levels of energy expenditure and physical activity were found.
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| 41. |
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| 42. |
- Bratteby, L-E, et al.
(författare)
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Physical activity, energy expenditure and their correlates in two cohorts of Swedish subjects between adolescence and early adulthood
- 2005
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Ingår i: European Journal of Clinical Nutrition. - : Springer Science and Business Media LLC. - 0954-3007 .- 1476-5640. ; 59, s. 1324-1334
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To assess physical activity and energy expenditure and to identify their correlates during adolescence and early adulthood. DESIGN: In a cohort study, total energy expenditure (TEE) and physical activity level (PAL) were assessed at 15 and 21 y from a 7-day activity diary and predicted BMR. The influences on TEE and PAL of body size, gender, sexual maturity, physical activity habits, sitting time, region, social conditions, employment, food habits, smoking and alcohol intake were examined in multivariate analyses.Subjects:71 male and 89 female subjects, living in two socioeconomically different regions of Sweden, a university region and an industrial region. SETTING: The university city of Uppsala and the industrial town of Trollhättan. RESULTS: At both 15 and 21 y, PAL and TEE were high, with gender, sitting time and physical activity habits as main correlates. At age 21 y, employment and the mother's educational level also appeared as significant correlates. The relations between the main variables and their correlates were more complex than at age 15 y, and the sitting time was reduced and the activity habits were changed. CONCLUSIONS: A reduction of daily sitting appears to be a major reason why high levels of physical activity and energy expenditure were maintained from 15 to 21 y of age in spite of changed and less frequent activity habits during this interval.
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| 43. |
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| 44. |
- Bratteby, L E, et al.
(författare)
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Total energy expenditure and physical activity as assessed by the doubly labeled water method in Swedish adolescents in whom energy intake was underestimated by 7-d diet records.
- 1998
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Ingår i: American Journal of Clinical Nutrition. - : Elsevier BV. - 0002-9165 .- 1938-3207. ; 67:5, s. 905-11
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Tidskriftsartikel (refereegranskat)abstract
- Swedish children and adolescents may be adopting a sedentary lifestyle with low energy expenditures and intakes, but no quantitative data are available. The purpose of the present study in 50 adolescents aged 15 y was to investigate whether assessment of total energy expenditure (TEE) and physical activity level (PAL) by the doubly labeled water method and indirect calorimetry and estimation of energy intake by a 7-d diet record would indicate physical inactivity. The boys' (n = 25) mean weight was 112% and the girls' (n = 25) was 109% of Swedish reference values from 1976; the mean height of both boys and girls was 102% of those reference values. Mean TEE in the boys and girls, 13.82 +/- 1.90 and 10.70 +/- 1.59 MJ/d, and mean PAL (TEE/basal metabolic rate), 1.89 +/- 0.16 and 1.79 +/- 0.22, respectively, were nonsignificantly higher than corresponding figures from other published studies. Mean energy intake as a percentage of TEE was 81.9 +/- 17.9% in the boys and 78.3 +/- 16.4% in the girls. Significant negative correlations were found both between energy intake as a percentage of TEE and percentage body fat and between energy intake as a percentage of TEE and body mass index. These results add to the evidence that 7-d diet records underestimate energy intake in adolescents, particularly those with a tendency for overweight and increased body fat. The results support indications of a trend of increasing body weight and height in Swedish adolescents, but conflict with the presumptions of low physical activity, low energy expenditure, and low energy intake. These results support the view that current recommendations for energy intake during adolescence are too low.
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| 45. |
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| 46. |
- Bryllert, Tomas, et al.
(författare)
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Designed emitter states in resonant tunneling through quantum dots
- 2002
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 80:15, s. 2681-2683
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Tidskriftsartikel (refereegranskat)abstract
- Resonant tunneling through a single layer of self-assembled quantum dots (QDs) is compared to tunneling through two layers of vertically aligned (stacked) dots. The difference can be viewed as going from a two-dimensional emitter to a zero-dimensional emitter. The temperature dependence of current peaks originating in tunneling through individual QDs and individual stacks is used to clarify this point. In addition, we show that the statistical size distribution of self-assembled quantum dots causing the inhomogeneous broadening in luminescence experiments can be analyzed in a resonant tunneling experiment. (C) 2002 American Institute of Physics.
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| 47. |
- Bryllert, Tomas, et al.
(författare)
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Resonant tunneling through coupled self-assembled quantum dots and the influence of inhomogeneous broadening
- 2002
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Ingår i: 7th International Conference on Nanometer-Scale Science and Technology and 21st European Conference on Surface Science.
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Konferensbidrag (refereegranskat)abstract
- Resonant tunneling through a single layer of self-assembled quantum dots (QDs) as well as tunneling through two layers of vertically aligned (stacked) dots is investigated. The difference between single and double layers of QDs can be viewed as going from a two-dimensional emitter to a zero-dimensional emitter. By fabricating small-area devices we are able to probe single stacks of quantum dots, revealing details of the coupling between the stacked dots. Very sharp resonances, with peak-to-valley ratios of several hundred, have been measured in the current-voltage characteristics. We also show that the statistical size distribution of self-assembled quantum dots causing the inhomogeneous broadening in luminescence experiments can be analysed in a resonant tunneling experiment
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| 48. |
- Bryllert, Tomas, et al.
(författare)
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Vertical high mobility wrap-gated InAs nanowire transistor
- 2005
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Ingår i: 63rd Device Research Conference Digest, 2005. DRC '05. - 0780390407 ; 1
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Konferensbidrag (refereegranskat)abstract
- We demonstrate a wrap-gated field effect transistor based on a matrix of vertically standing InAs nanowires (Jensen, et. al., 2004). A lower limit of the mobility, derived from the transconductance, is on the order of 3000 cm2/Vs. The narrow ~100 nm channels show excellent current saturation and a threshold of Vg = -0.15 V. The sub-threshold characteristics show a close to ideal slope of 62mV/decade over two orders of magnitude
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| 49. |
- Chen, D, et al.
(författare)
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Altered control of gastric acid secretion in gastrin-cholecystokinin double mutant mice
- 2004
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Ingår i: Gastroenterology. - : Elsevier BV. - 1528-0012 .- 0016-5085. ; 126:2, s. 476-487
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Tidskriftsartikel (refereegranskat)abstract
- Background & Aims: Three pathways control gastric acid secretion: the gastrin-enterochromaffin-like (ECL) cell axis, the vagus-parietal cell axis, and the cholecystokinin (CCK)-D cell axis. Mice lacking gastrin or both gastrin and CCK were examined to determine the role of the hormones. Methods: Acid was measured after pylorus ligation, and biopsies from gastrin knockout (KO), gastrin-CCK double-KO, and wild-type (WT) mice were collected for biochemical, immunocytochemical, and electron-microscopic examination. Results: The ECL cells were inactive in both groups of mutant mice but the cell number was unaffected. Both parietal cell number and level of H+/K+-ATPase messenger RNA (mRNA) were reduced in the mutant strains, but gastrin-CCK double-KO mice displayed more active parietal cells and larger acid output than the gastrin KO mice. The acid response to histamine in double-KO mice was unchanged whereas that to gastrin was diminished, but it could be restored by infusion of gastrin. Oxyntic D-cell density was the same in both mutant strains, but the D cells were more active in the gastrin KO than in the double-KO mice. CCK infusion in gastrin-CCK double-KO mice raised the somatostatin mRNA level and inhibited acid secretion to the level seen in gastrin KO mice. Vagotomy and atropine abolished acid secretion in all 3 groups of mice. Conclusions: Lack of gastrin impairs the gastrin-ECL axis, whereas lack of gastrin and CCK impairs both hormonal pathways. In the gastrin-CCK double-KO mice, acid secretion is only controlled by cholinergic vagal stimulation, which normalizes the acid output.
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