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  • Pettersson, Håkan, et al. (författare)
  • Infrared Photodetectors in Heterostructure Nanowires
  • 2006
  • Ingår i: Nano letters (Print). - Washington : American Chemical Society (ACS). - 1530-6984 .- 1530-6992. ; 6:2, s. 229-232
  • Tidskriftsartikel (refereegranskat)abstract
    • We report on spectrally resolved photocurrent measurements on single self-assembled nanowire heterostructures. The wires, typically 3 μm long with an average diameter of 85 nm, consist of InAs with a 1 μm central part of InAsP. Two different sets of wires were prepared with phosphorus contents of 15 ±3% and 35 ±3%, respectively, as determined by energy-dispersive spectroscopy measurements made in transmission electron microscopy. Ohmic contacts are fabricated to the InAs ends of the wire using e-beam lithography. The conduction band offset between the InAs and InAsP regions virtually removes the dark current through the wires at low temperature. In the optical experiments, interband excitation in the phosphorus-rich part of the wires results in a photocurrent with threshold energies of about 0.65 and 0.82 eV, respectively, in qualitative agreement with the expected band gap of the two compositions. Furthermore, a strong polarization dependence is observed with an order of magnitude larger photocurrent for light polarized parallel to the wire than for light polarized perpendicular to the wire. We believe that these wires form promising candidates as nanoscale infrared polarization-sensitive photodetectors.
  • Pettersson, Håkan, et al. (författare)
  • Intersubband photoconductivity of self-assembled InAs quantum dots embedded in InP
  • 2004
  • Ingår i: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 95:4, s. 1829-1831
  • Tidskriftsartikel (refereegranskat)abstract
    • The results from photoconductivity (PC) measurements on InAs dots embedded in InP are presented. The PC technique is recently applied to the study of InAs dots embedded in matrices of GaAs and Al0.3Ga0.7As matrix, respectively. It is demonstrated that this technique reveals important new physical insight into the electronic structure of the InAs/InP dots, information that cannot easily be obtained by other techniques.
  • Bratteby, L-E, et al. (författare)
  • Physical activity, energy expenditure and their correlates in two cohorts of Swedish subjects between adolescence and early adulthood
  • 2005
  • Ingår i: European Journal of Clinical Nutrition. - 0954-3007 .- 1476-5640. ; 59, s. 1324-1334
  • 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.
  • Gaines, Hans, et al. (författare)
  • Six-week follow-up after HIV-1 exposure : a position statement from the Public Health Agency of Sweden and the Swedish Reference Group for Antiviral Therapy
  • 2016
  • Ingår i: INFECTIOUS DISEASES. - : Taylor & Francis. - 2374-4235 .- 2374-4243. ; 48:2, s. 93-98
  • Forskningsöversikt (refereegranskat)abstract
    • In 2014 the Public Health Agency of Sweden and the Swedish Reference Group for Antiviral Therapy (RAV) conducted a review and analysis of the state of knowledge on the duration of follow-up after exposure to human immunodeficiency virus (HIV). Up until then a follow-up of 12 weeks after exposure had been recommended, but improved tests and new information on early diagnosis motivated a re-evaluation of the national recommendations by experts representing infectious diseases and microbiology, county medical officers, the RAV, the Public Health Agency, and other national authorities. Based on the current state of knowledge the Public Health Agency of Sweden and the RAV recommend, starting in April 2015, a follow-up period of 6 weeks after possible HIV-1 exposure, if HIV testing is performed using laboratory-based combination tests detecting both HIV antibody and antigen. If point-of-care rapid HIV tests are used, a follow-up period of 8 weeks is recommended, because currently available rapid tests have insufficient sensitivity for detection of HIV-1 antigen. A follow-up period of 12 weeks is recommended after a possible exposure for HIV-2, since presently used assays do not include HIV-2 antigens and only limited information is available on the development of HIV antibodies during early HIV-2 infection. If pre- or post-exposure prophylaxis is administered, the follow-up period is recommended to begin after completion of prophylaxis. Even if infection cannot be reliably excluded before the end of the recommended follow-up period, HIV testing should be performed at first contact for persons who seek such testing.
  • Hartmanis, Åsalie, et al. (författare)
  • Obligatoriskt nanoregister? Nej tack!
  • 2012
  • Ingår i: Ny teknik. - : Talentum Sweden AB. - 0550-8754.
  • Tidskriftsartikel (populärvet., debatt m.m.)
  • Larsson, Ingrid, et al. (författare)
  • Body composition through adult life : Swedish reference data on body composition
  • 2015
  • Ingår i: European Journal of Clinical Nutrition. - : Nature Publishing Group. - 0954-3007 .- 1476-5640. ; 69:7, s. 837-842
  • Tidskriftsartikel (refereegranskat)abstract
    • Background/Objectives:The prevalence of obesity, defined as body mass index (BMI) greater than or equal to30 kg/m2, differs between populations; however, there is a need for data on description on body composition in reference populations of different ages and from different countries. The objective of this study was to pool dual-energy X-ray absorptiometry (DXA) body composition reference data from population-based Swedish cohorts.Subjects/Methods:Four population-based cross-sectional cohort studies including 1424 adult Swedes were divided into five age groups (20–29, 30–39, 40–49, 50–61 and 75 years of age); BMI 24.6±3.9 kg/m2 were pooled. Body composition was measured with DXA.Results:The difference in BMI from the youngest to the oldest age group was 3.2 and 4.3 kg/m2 in men and women, respectively (P<0.001, both sexes), and fat mass (FM) was 9.9 and 9.1% higher in the oldest compared with the youngest men and women (P<0.001, both sexes). Fat-free mass (FFM) remained stable up to 60 years of age in men (P=0.83) and was lower at 75 years of age compared with the younger ages. In women, FFM was lower from age 60. From youngest to oldest age groups, height-adjusted FM differed from 4.6 to 7.8 kg/m2 in men and from 6.8 to 10.8 kg/m2 in women (P<0.001, both sexes).Conclusions:Our results provide reference data on body composition in Swedish populations. BMI and FM were higher among older age groups compared with the younger ones. FFM remained stable up to 60 years of age and was lower first among the 75 years of age.
  • Lee, SK, et al. (författare)
  • Reduction of the Schottky barrier height on silicon carbide using Au nano-particles
  • 2002
  • Ingår i: Solid-State Electronics. - : Elsevier. - 0038-1101 .- 1879-2405. ; 46:9, s. 1433-1440
  • Tidskriftsartikel (refereegranskat)abstract
    • By the incorporation of size-selected Au nano-particles in Ti Schottky contacts on silicon carbide, we could observe considerably lower the barrier height of the contacts. This result could be obtained for both n- and p-type Schottky contacts using current-voltage and capacitance voltage measurements. For n-type Schottky contacts, we observed reductions of 0.19-0.25 eV on 4H-SiC and 0.15-0.17 eV on 6H-SiC as compared with particle-free Ti Schottky contacts. For p-type SiC, the reduction was a little lower with 0.02-0.05 eV on 4H- and 0.10-0.13 eV on 6H-SiC. The reduction of the Schottky barrier height is explained using a model with enhanced electric field at the interface due to the small size of the circular patch and the large difference of the barrier height between Ti and Au.
  • Lewen, R, et al. (författare)
  • High frequency characterization of a GaInAs/InP electronic waveguide T-branch switch
  • 2002
  • Ingår i: Applied Physics Reviews. - : American Institute of Physics (AIP). - 1931-9401. ; 91:4, s. 2398-2402
  • Tidskriftsartikel (refereegranskat)abstract
    • We report comprehensive microwave measurements on a T-branch switch; a GaInAs/InP electron waveguide based structure. The study includes a small signal model of the device where limitations of high frequency operation are discussed. An example of large signal operation where the nonlinearity of the device is exploited by operating the T-branch switch as a frequency multiplier is demonstrated.
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