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| 2. |
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| 3. |
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| 4. |
- Arrhenius, Åsa, 1973, et al.
(författare)
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Effects of antimycotics and fungicides to limnic microbial biofilms – a case study of the run-off from a golf course
- 2016
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Ingår i: 4th Biofilm Workshop - Basis and application of biofilms to assess the effects of environmental change in aquatic ecosystems - Girona, 7-8 April 2016.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Antimycotic pharmaceuticals and fungicides are widely used for treating fungal infections in humans and animals and control pests in different areas and applications. They enter the aquatic environment either after passage through the body, or after being rinsed off from areas of application (skin, crops, farmland etc.). However, substantial knowledge gaps currently hamper a proper environmental risk assessment of the individual antimycotics and fungicides and their mixtures for marine and freshwater environments. Previously it has been shown that clotrimazole, a marine priority pollutant, affected sterol composition of marine microalgal communities already at 50 pmol/L which indicates effects at environmental concentrations. In this presentation we will discuss results from our work with limnic microbial biofilms and effects from antimycotics and fungicides individually and as mixtures. Endpoints include growth, pigment pattern, sterol composition, and species composition. Special focus will be on a case study from a Swedish golf course with a high usage of fungicides. Based on an analytical survey we prepared a worst-case-mixture study were we exposed biofilms in indoor microcosms for several days. Effects on growth and some shifts in microalgal species composition could be observed at concentrations relevant for the nearby golf area. Analysis of sterol composition and analytical confirmation of exposure concentrations are work in progress. The work is performed within the Swedish Formas-funded project “Aquatic Environmental Risk Assessment of Antimycotics”.
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| 5. |
- Baveja, Prashant, 1985, et al.
(författare)
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Impact of device parameters on thermal performance of high speed oxide confined 850 nm VCSELs
- 2012
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Ingår i: IEEE Journal of Quantum Electronics. - 0018-9197 .- 1558-1713. ; 48:1, s. 17-26
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Tidskriftsartikel (refereegranskat)abstract
- We study the impact of device parameters, such asinner-aperture diameter and cavity photon lifetime, on thermal rollover mechanisms in 850-nm, oxide-confined, vertical-cavity surface-emitting lasers (VCSELs) designed for high-speed operation. We perform measurements on four different VCSELs of different designs and use our empirical thermal model for calculating the power dissipated with increasing bias currents through various physical processes such as absorption within the cavity, carrier thermalization, carrier leakage, spontaneous carrier recombination, and Joule heating. When reducing the topmirror reflectivity to reduce internal optical absorption loss we find an increase of power dissipation due to carrier leakage. There is therefore a trade-ff between the powers dissipated owing to optical absorption and carrier leakage in the sense that overcompensating for optical absorption enhances carrier leakage (and vice versa). We further find that carrier leakage places the ultimate limit on the thermal performance for this entire class ofdevices. Our analysis yields useful design optimization strategies for mitigating the impact of carrier leakage and should thereby prove useful for the performance enhancement of 850-nm, highspeed, oxide-confined VCSELs.
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| 6. |
- Baveja, P. P., et al.
(författare)
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Assessment of VCSEL thermal rollover mechanisms from measurements and empirical modeling
- 2011
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Ingår i: Optics Express. - 1094-4087 .- 1094-4087. ; 19:16, s. 15490-15505
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Tidskriftsartikel (refereegranskat)abstract
- We use an empirical model together with experimental measurements for studying mechanisms contributing to thermal rollover in vertical-cavity surface-emitting lasers (VCSELs). The model is based on extraction of the temperature dependence of threshold current, internal quantum efficiency, internal optical loss, series resistance and thermal impedance from measurements of output power, voltage and lasing wavelength as a function of bias current over an ambient temperature range of 15-100 degrees C. We apply the model to an oxide-confined, 850-nm VCSEL, fabricated with a 9-mu m inner-aperture diameter and optimized for highspeed operation, and show for this specific device that power dissipation due to linear power dissipation (sum total of optical absorption, carrier thermalization, carrier leakage and spontaneous carrier recombination) exceeds power dissipation across the series resistance (quadratic power dissipation) at any ambient temperature and bias current. We further show that the dominant contributors to self-heating for this particular VCSEL are quadratic power dissipation, internal optical loss, and carrier leakage. A rapid reduction of the internal quantum efficiency at high bias currents (resulting in high temperatures) is identified as being the major cause of thermal rollover. Our method is applicable to any VCSEL and is useful for identifying the mechanisms limiting the thermal performance of the device and to formulate design strategies to ameliorate them.
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| 7. |
- Baveja, P. P., et al.
(författare)
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Impact of photon lifetime on thermal rollover in 850-nm high-speed VCSELs
- 2012
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819489197 ; 8276
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Konferensbidrag (refereegranskat)abstract
- We present an empirical thermal model for VCSELs based on extraction of temperature dependence of macroscopic VCSEL parameters from CW measurements. We apply our model to two, oxide-confined, 850-nm VCSELs, fabricated with a 9-mu m inner-aperture diameter and optimized for high-speed operation. We demonstrate that for both these devices, the power dissipation due to linear heat sources dominates the total self-heating. We further show that reducing photon lifetime down to 2 ps drastically reduces absorption heating and improves device static performance by delaying the onset of thermal rollover. The new thermal model can identify the mechanisms limiting the thermal performance and help in formulating the design strategies to ameliorate them.
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| 8. |
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| 9. |
- Berglund, Erik, et al.
(författare)
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Multidisciplinary Intervention and Acceptance and Commitment Therapy for Return-to-Work and Increased Employability among Patients with Mental Illness and/or Chronic Pain : A Randomized Controlled Trial
- 2018
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Ingår i: International Journal of Environmental Research and Public Health. - : MDPI AG. - 1661-7827 .- 1660-4601. ; 15:11
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Tidskriftsartikel (refereegranskat)abstract
- Background: People on long-term sick leave often have a long-lasting process back to work, where the individuals may be in multiple and recurrent states; i.e., receiving different social security benefits or working, and over time they may shift between these states. The purpose of this study was to evaluate the effects of two vocational rehabilitation programs, compared to a control, on return-to-work (RTW) or increased employability in patients on long-term sick leave due to mental illness and/or chronic pain. Methods: In this randomized controlled study, 427 women and men were allocated to either (1) multidisciplinary team management, i.e., multidisciplinary assessments and individual rehabilitation management, (2) acceptance and commitment therapy (ACT), or (3) control. A positive outcome was defined as RTW or increased employability. The outcome was considered negative if the (part-time) wage was reduced or ceased, or if there was an indication of decreased employability. The outcome was measured one year after entry in the project and analyzed using binary and multinomial logistic regressions. Results: Participants in the multidisciplinary team group reported having RTW odds ratio (OR) 3.31 (95% CI 1.39-7.87) compared to the control group in adjusted models. Participants in the ACT group reported having increased employability OR 3.22 (95% CI 1.13-9.15) compared to the control group in adjusted models. Conclusions: This study of vocational rehabilitation in mainly female patients on long-term sick leave due to mental illness and/or chronic pain suggests that multidisciplinary team assessments and individually adapted rehabilitation interventions increased RTW and employability. Solely receiving the ACT intervention also increased employability.
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| 10. |
- Bergmann, Michael Alexander, 1989, et al.
(författare)
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Towards ultraviolet and blue microcavity lasers
- 2018
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Ingår i: Northen Optics and Photonics conference. - 9789163964886 ; 2018
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Konferensbidrag (refereegranskat)abstract
- The development of III-nitride-based (Al,Ga,In(N)) microcavity lasers is a challenging task. Significant progress in recent years has resulted in realizations of electrically pumped devices with optical output power in the mW-range and with threshold current densities below 20 kA/cm2. However, to become practical, the lifetime and power conversion efficiency of these devices must be improved. Among the challenges are achieving transverse optical mode confinement, highreflectivity mirrors and control over the resonator length. We will highlight our theoretical work on transverse optical mode confinement, emphasising the overwhelming risk of ending up with an optically anti-guided cavity, and its consequences such as very high optical losses that easily could double the threshold gain for lasing. We will show some anti-guided cavities with reasonable threshold gain and built-in modal discrimination. However, all anti-guided cavities are very sensitive to temperature effects and small structural changes in the cavity caused by fabrication imperfections. We have explored electrically conductive distributed Bragg reflectors (DBRs) in both AlN/GaN and ZnO/GaN. The AlN/GaN DBRs were grown with different strain-compensating interlayers, and the DBR without interlayers had the lowest vertical resistivity with a specific series resistance of 0.044 cmfor eight DBRpairs. In the ZnO/GaN DBR, the measured resistance was dominated by lateral and contact contributions, setting a lower measurable limit of ~10 for three DBR-pairs. Numerical simulations show the importance of having in-plane strained layers in the ZnO/GaN DBR, since that leads to cancellation of the spontaneous and piezoelectric polarization. This results in a dramatically reduced vertical resistance, potentially three orders of magnitude lower than what could be measured. cm An alternative to an epitaxially grown DBR is a dielectric DBR, which offers high reflectivity over a broader wavelength range, relaxing the requirements on resonator length control. To deposit a dielectric DBR on the bottom side of the cavity, the sample must first be bonded to a carrier wafer before the substrate can be removed. We used thermocompression gold-gold bonding to successfully bond the laser structure to a Si carrier wafer. The subsequent substrate removal is a challenging process due to the chemical inertness of the III-nitride-based materials. A doping-dependent electrochemical etch technique was used, which allows for the selective removal of a sacrificial (n-doped) layer between the cavity and the substrate. This resulted in nm-precise cavity lift-off with a low root-mean-square surface roughness down to 0.3 nm. Thus, the process is suitable for the fabrication of high-quality optical devices such as microcavity lasers. In addition, the technique offers a new alternative to create III-nitridebased optical resonators, mechanical resonators, thin film LEDs and transistors.
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| 11. |
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| 12. |
- Bremer, Anna, et al.
(författare)
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Copy number variation characteristics in subpopulations of patients with autism spectrum disorders.
- 2011
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Ingår i: American Journal of Medical Genetics, Part B, Neuropsychiatric Genetics. - : Wiley. - 1552-4841. ; 156B156:2, s. 115-124
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Tidskriftsartikel (refereegranskat)abstract
- Autism spectrum disorders (ASDs) are a heterogeneous group of disorders with a complex genetic etiology. We used high-resolution whole genome array-based comparative genomic hybridization (array-CGH) to screen 223 ASD patients for gene dose alterations associated with susceptibility for autism. Clinically significant copy number variations (CNVs) were identified in 18 individuals (8%), of which 9 cases (4%) had de novo aberrations. In addition, 20 individuals (9%) were shown to have CNVs of unclear clinical relevance. Among these, 13 cases carried rare but inherited CNVs that may increase the risk for developing ASDs, while parental samples were unavailable in the remaining seven cases. Classification of all patients into different phenotypic and inheritance pattern groups indicated the presence of different CNV patterns in different patient groups. Clinically relevant CNVs were more common in syndromic cases compared to non-syndromic cases. Rare inherited CNVs were present in a higher proportion of ASD cases having first- or second-degree relatives with an ASD-related neuropsychiatric phenotype in comparison with cases without reported heredity (P=0.0096). We conclude that rare CNVs, encompassing potential candidate regions for ASDs, increase the susceptibility for the development of ASDs and related neuropsychiatric disorders giving us further insight into the complex genetics underlying ASDs
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| 13. |
- Cardinali, G., et al.
(författare)
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Low-Threshold AlGaN-based UVB VCSELs enabled by post-growth cavity detuning
- 2022
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 121:10
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Tidskriftsartikel (refereegranskat)abstract
- The performance of vertical-cavity surface-emitting lasers (VCSELs) is strongly dependent on the spectral detuning between the gain peak and the resonance wavelength. Here, we use angle-resolved photoluminescence spectroscopy to investigate the emission properties of AlGaN-based VCSELs emitting in the ultraviolet-B spectral range with different detuning between the photoluminescence peak of the quantum-wells and the resonance wavelength. Accurate setting of the cavity length, and thereby the resonance wavelength, is accomplished by using doping-selective electrochemical etching of AlGaN sacrificial layers for substrate removal combined with deposition of dielectric spacer layers. By matching the resonance wavelength to the quantum-wells photoluminescence peak, a threshold power density of 0.4 MW/cm2 was achieved, and this was possible only for smooth etched surfaces with a root mean square roughness below 2 nm. These results demonstrate the importance of accurate cavity length control and surface smoothness to achieve low-Threshold AlGaN-based ultraviolet VCSELs.
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| 14. |
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| 15. |
- Chang, Tsu Chi, et al.
(författare)
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Electrically Injected GaN-Based Vertical-Cavity Surface-Emitting Lasers with TiO2 High-Index-Contrast Grating Reflectors
- 2020
-
Ingår i: ACS Photonics. - : American Chemical Society (ACS). - 2330-4022. ; 7:4, s. 861-866
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate the first electrically injected GaN-based vertical-cavity surface-emitting lasers (VCSELs) with a TiO2 high-index-contrast grating (HCG) as the top mirror. Replacing the top distributed Bragg reflector (DBR) with an HCG offers substantial thickness reduction, polarization-pinning, and setting of the resonance wavelength by the grating parameters. Conventional HCGs are usually suspended in the low refractive index material, such as air, in order to create the largest refractive index contrast. However, the mechanical stability of such structures can be questioned and creating free-hanging GaN-membrane on top of GaN is problematic. We have therefore fabricated TiO2-HCGs resting directly on GaN without an air-gap. No DBR layers are used below the HCG to boost the reflectivity. A VCSEL with an aperture diameter of 10 μm shows a threshold current of 25 mA under pulsed operation at room temperature. The lasing modes locate around 400 nm and are transversely electrically -polarized with a line width of 0.5 nm. The full-width half-maximum beam divergence is 10°. This demonstration of a TiO2-HCG VCSEL offers a new route to achieve polarization pinning and could also allow additional benefits such as postgrowth setting of the resonance wavelength.
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| 16. |
- Chang, Tsu-Chi, et al.
(författare)
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GaN-based vertical-cavity surface-emitting laser incorporating a TiO2 high-index-contrast grating
- 2020
-
Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 11280
-
Konferensbidrag (refereegranskat)abstract
- We demonstrate the first electrically injected GaN-based VCSEL with a TiO2 high-contrast grating (HCG) as the top mirror. The TiO2-HCG rested directly on the n-GaN without an airgap for mechanical stability. A VCSEL with an aperture diameter of 10 mu m had a threshold current of 25 mA under pulsed operation at room temperature. Multiple longitudinal modes coexist around 400 nm, each TM-polarized with a linewidth of 0.5 nm (spectral resolution limited). This first demonstration of a TiO2-HCG VCSEL offers a new route to achieve polarization pinning and could also allow additional benefits such as post-growth setting of resonance wavelength.
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| 17. |
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| 18. |
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| 19. |
- Davani, Hooman A., et al.
(författare)
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Polarization investigation of a tunable high-speed short-wavelength bulk-micromachined MEMS-VCSEL
- 2012
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819489197 ; 8276, s. Art. no. 82760T-
-
Konferensbidrag (refereegranskat)abstract
- We report the investigation of the state of polarization (SOP) of a tunable vertical-cavity surface-emitting laser (VCSEL) operating near 850 nm with a mode-hop free single-mode tuning range of about 12 nm and an amplitude modulation bandwidth of about 5 GHz. In addition, the effect of a sub-wavelength grating on the device and its influence on the polarization stability and polarization switching has been investigated. The VCSEL with an integrated sub-wavelength grating shows a stable SOP with a polarization mode suppression ratio (PMSR) more than 35 dB during the tuning.
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| 20. |
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| 21. |
- Ganowiak, Katarzyna, et al.
(författare)
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Fibrils from Synthetic Amyloid-Related Peptides Enhance Development of Experimental AA-Amyloidosis in Mice
- 1994
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Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 199:1, s. 306-312
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Tidskriftsartikel (refereegranskat)abstract
- Amyloid enhancing factor is an incompletely characterized activity of extracts from many amyloid-containing tissues and which greatly shortens the preamyloidotic phase during experimental induction of AA-amyloidosis. In this communication we show that amyloid-like fibrils made in vitro from synthetic peptides, corresponding to segments of amyloid fibril proteins, have amyloid enhancing factor-like activity. Thus, there is a possibility that amyloid enhancing factor activity depends on small fibrils serving as nucleation centers for fibril elongation.
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| 22. |
- Gierl, Christian, et al.
(författare)
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Tuneable VCSEL aiming for the application in interconnects and short haul systems
- 2011
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819484963 ; 7959
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Widely tunable vertical cavity surface emitting lasers (VCSEL) are of high interest for optical communications, gas spectroscopy and fiber-Bragg-grating measurements. In this paper we present tunable VCSEL operating at wavelength around 850 nm and 1550 nm with tuning ranges up to 20 nm and 76 nm respectively. The first versions of VCSEL operating at 1550 nm with 76 nm tuning range and an output power of 1.3mW were not designed for high speed modulation, but for applications where only stable continious tuning is essential (e.g. gas sensing). The next step was the design of non tunable VCSEL showing high speed modulation frequencies of 10 GHz with side mode supression ratios beyond 50 dB. The latest version of these devices show record output powers of 6.7mW at 20 °C and 3mW at 80 °C. The emphasis of our present and future work lies on the combination of both technologies. The tunable VCSEL operating in the 850 nm-region reaches a modulation bandwidth of 5.5GHz with an output power of 0.8mW.
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| 23. |
- Gustavsson, Anders, et al.
(författare)
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Disease progression and costs of care in Alzheimer's disease patients treated with donepezil: a longitudinal naturalistic cohort.
- 2012
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Ingår i: European Journal of Health Economics. - : Springer Science and Business Media LLC. - 1618-7601 .- 1618-7598. ; 13:5, s. 561-568
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND/AIMS: Improved data and methods are needed for modeling disease progression in Alzheimer's disease (AD) for economic evaluation of treatments. The aim is to estimate prediction models for long-term AD progression and subsequently economic outcomes. METHODS: Three-year follow-up data on 435 patients treated with the cholinesterase inhibitor donepezil in clinical practise were analyzed. Regression models were estimated for long-term prediction of decline in cognitive function (ADAS-cog) and activities in daily living (ADL) ability, risk of institutionalization and costs of care. RESULTS: The cognitive deterioration was estimated at between 1.6 and 4 ADAS-cog points per every 6 months, increasing with disease severity. Cognitive function was an important predictor of ADL-ability, which itself was the most important predictor of the risk of institutionalization and costs of care. Combining all models in a cross-validation process generated accurate predictions of costs of care at each 6 months follow-up. CONCLUSION: The proposed methods for representing AD progression and economic outcomes can be used in micro-simulation models for the economic evaluation of new treatments.
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| 24. |
- Gustavsson, Catharina, 1961-, et al.
(författare)
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Process evaluation of an implementation intervention to facilitate the use of the Swedish Physical Activity on Prescription in primary healthcare.
- 2023
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Ingår i: BMC Health Services Research. - : BioMed Central (BMC). - 1472-6963. ; 23:1
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The Swedish Physical Activity on Prescription (PAP-S) is a method for healthcare to promote physical activity for prevention and treatment of health disorders. Despite scientific support and education campaigns, the use has been low. The aim of this study was to perform a process evaluation of an implementation intervention targeting the use of the PAP-S method in primary healthcare (PHC). Specifically, we wanted to evaluate feasibility of the implementation intervention, and its effect on the implementation process and the outcome (number of PAP-S prescriptions).METHODS: This was a longitudinal study using the Medical Research Council guidance for process evaluation of a 9-month implementation intervention among healthcare staff at three PHC centres in Sweden. Data was collected by: participatory observations of the implementation process; questionnaires to the staff before, after and 6 months after the implementation intervention; interviews after the implementation intervention; and number of PAP-S prescriptions.RESULTS: During the implementation intervention, the workplaces' readiness-to-change and the healthcare staff's confidence in using the PAP-S method were favourably influenced, as was the number of PAP-S prescriptions. After the implementation intervention, the number of PAP-S prescriptions decreased to about the same number as before the implementation intervention, at two out of three PHC centres. Four of the six implementation strategies appeared to impact on the implementation process: external facilitation; leadership engagement by a committed workplace management; local PAP-S coordinator taking a leading role and acting as local champion; educational outreach concerning how to use the PAP-S method.CONCLUSION: The implementation intervention was not sufficient to produce sustained change of the healthcare staff's behaviour, nor did it achieve favourable long-term outcome on the number of PAP-S prescriptions. The healthcare staffs' sparse knowledge of the PAP-S method prior to the implementation intervention hampered the implementation. More hands-on education in how to use the PAP-S method introduced early in the implementation process is imperative for successful implementation of the PAP-S method. The findings also suggest that committed workplace management and local PAP-S coordinators, taking leading roles and acting as local champions, need to be firmly established at the PHC centres before the external facilitator withdraws.TRIAL REGISTRATION: Registered in the ISRCTN registry with study registration number: ISRCTN15551042 (Registration date: 12/01/2016).
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| 26. |
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| 27. |
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| 28. |
- Gustavsson, Johan, 1974, et al.
(författare)
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High-speed 850-nm VCSELs for 40 Gb/s transmission
- 2010
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We have explored the possibility to extend the data transmission rate for standard 850-nm GaAs-based VCSELs beyond the 10 Gbit/s limit of today's commercially available directly-modulated devices. By sophisticated tailoring of the design for high-speed performance we demonstrate that 10 Gb/s is far from the upper limit. For example, the thermal conductivity of the bottom mirror is improved by the use of binary compounds, and the electrical parasitics are kept at a minimum by incorporating a large diameter double layered oxide aperture in the design. We also show that the intrinsic high speed performance is significantly improved by replacing the traditional GaAs QWs with strained InGaAs QWs in the active region. The best overall performance is achieved for a device with a 9 μm diameter oxide aperture, having in a threshold current of 0.6 mA, a maximum output power of 9 mW, a thermal resistance of 1.9 °C/mW, and a differential resistance of 80 Ω. The measured 3dB bandwidth exceeds 20 GHz, and we experimentally demonstrate that the device is capable of error-free transmission (BER
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| 29. |
- Gustavsson, Johan, 1974, et al.
(författare)
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High speed 850nm VCSELs for >40Gb/s transmission
- 2013
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Ingår i: 2013 Optical Fiber Communication Conference and Exposition and the National Fiber Optic Engineers Conference, OFC/NFOEC 2013. - 9781479904570 ; , s. OTh4H.4-
-
Konferensbidrag (refereegranskat)abstract
- VCSELs capable of direct modulation exceeding 40Gb/s are needed in next generation optical interconnect standards. Using a refined high-speed design we demonstrate GaAs-based VCSELs having record-high 28GHz modulation bandwidth, and that operate error-free at 47Gb/s.
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| 30. |
- Gustavsson, Johan, 1974, et al.
(författare)
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High-speed, high-temperature VCSELs for optical interconnects
- 2013
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Ingår i: 2013 IEEE Photonics Society Summer Topical Meeting Series, PSSTMS 2013. - 9781467350600 ; , s. 7-8
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Konferensbidrag (refereegranskat)abstract
- Directly modulated VCSELs operating at 40Gb/s are required for next generation optical interconnect standards. Using a refined high-speed design we demonstrate GaAs-based VCSELs that operate error-free at 47Gb/s at 25°C, and 40Gb/s at 85°C.
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| 31. |
- Gustavsson, Johan, 1974, et al.
(författare)
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Mode and polarization control in VCSELs using shallow surface structures
- 2007
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Ingår i: IET Optoelectronics. ; 1:5, s. 197-205
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Tidskriftsartikel (refereegranskat)abstract
- Monolithic techniques for mode and polarisation control in vertical-cavity surface emitting lasers (VCSELs) using shallow surface structures are summarized and put in the context with other techniques in terms of performance and manufacturability. The method of using circular-symmetric surface structures for mode control and their combination with a sub-wavelength surface grating for simultaneous mode and polarisation control is described in detail, and adherent experimental results for both 850-nm and 1.3-µm oxide-confined VCSELs are presented.
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| 32. |
- Gustavsson, Johan, 1974, et al.
(författare)
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Optimized active region design for high speed 850 nm VCSELs
- 2009
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Ingår i: CLEO/Europe - EQEC 2009 - European Conference on Lasers and Electro-Optics and the European Quantum Electronics Conference; Munich; Germany; 14 June 2009 through 19 June 2009. - 9781424440801 ; , s. Art. no. 5192928-
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Konferensbidrag (refereegranskat)abstract
- Short wavelength (850 nm) VCSELs operating at speeds of 25 Gb/s and above are needed for future highcapacity, short reach data communication links. The modulation bandwidth is intrinsically limited by thedifferential gain of the QWs used in the active region of the VCSEL. In this work we explore the use of strainedInGaAs/AlGaAs QWs and benchmark the performance against conventional GaAs/AlGaAs QWs.An 8-band k⋅p model [1] was used to calculate the energy band dispersions, using band offsets from modelsolid theory [2]. In all cases, the QW and barrier compositions and QW thickness were chosen for a gain peak at845 nm, enabling emission at 850 nm with a small detuning between the gain peak and the cavity resonance.With increasing In-concentration the QW thickness is reduced and the Al-concentration in the barrier isincreased to maintain the gain peak at 845 nm and the number of QWs is increased to maintain opticalconfinement and enable operation at a low carrier density for high differential gain. It was found that theincorporation of up to 10% In leads to a significant reduction in threshold carrier density and increase indifferential gain. This is due to an increased separation and reduced mixing between the highest heavy-hole andlight-hole valence bands (Fig.1). A further increase of In concentration leads to a less marked improvement.With an optimum active region design (5 x 4 nm In0.10Ga0.90As/Al0.37Ga0.63As QWs) a differential gain twice ashigh as that of a conventional design with 3 x 8 nm GaAs/Al0.30Ga0.70As QWs was predicted (Table 1).The improvement of differential gain was experimentally confirmed by extracting the resonance frequencyand its dependence on current from the modulation response of VCSELs with optimized InGaAs/AlGaAs QWand conventional GaAs/AlGaAs QW active regions. The differential gain was calculated from the correspondingD-factors (Fig.2) [3]. Excellent agreement was obtained between theory and experiments (Table 1).VCSELs with an optimized InGaAs/AlGaAs QW active region have a modulation bandwidth of 20 GHz at25° and 15 GHz at 85°C [4] and have enabled error-free transmission over 50 (100) m multimode fiber up to 32(25) Gb/s at a bias current density as low as 11 kA/cm2 under direct current modulation.
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| 33. |
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| 34. |
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| 35. |
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| 36. |
- Gustavsson, Leif, et al.
(författare)
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CO2 Mitigation : On Methods and Parameters for Comparison of Fossil-Fuel and Biofuel Systems
- 2006
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Ingår i: Mitigation and Adaptation Strategies for Global Change. - : Springer Science and Business Media LLC. - 1381-2386 .- 1573-1596. ; 11:5/6, s. 935-959
-
Tidskriftsartikel (refereegranskat)abstract
- The replacement of fossil fuels by biofuels could be an important means of reducing net carbon dioxide (CO2) emission. An estimation of the CO2 mitigation efficiency of biofuel systems depends on the method and assumptions used. Here, different parameters and methods are discussed for comparing fossil-fuel- and biofuel-based systems. Three parameters are suggested: the monetary cost, the primary energy cost and the biofuel cost of CO2 mitigation. They are defined as the difference in monetary expenditure, primary energy use and biofuel use between the compared systems, divided by the difference in net CO2 emission between the systems. Cogeneration and separate production of electricity and heat is then compared using these parameters and the methods of multi-functional products or subtraction. In both methods, either electricity or heat is regarded as the main product and the other is regarded as a by-product. The multi-functional method is preferable due to its transparency as both the main product and the by-product are part of the functional unit. Using heat as the main product illustrates the typical situation that the heat demand limits the use of cogeneration. When comparing systems the output from them should not differ. If the by-product is not fully, cogenerated part of the by-product has to be produced separately. A logical choice for producing this part of the by-product is to use a similar fuel and technology as used for cogeneration.
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| 39. |
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| 40. |
- Gustavsson, Leif, et al.
(författare)
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Heating Detached Houses in Urban Areas
- 2003
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Ingår i: Energy. - 0360-5442 .- 1873-6785. ; 28:8, s. 851-875
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Tidskriftsartikel (refereegranskat)abstract
- District heating systems using cogeneration, as well as local fuel-based and electric heating systems for detached houses, are analysed. The analysis includes the whole energy system, from the natural resource to the end user, with respect to primary energy use, emission and cost. The end-use technologies studied are heat pumps, resistance heaters and boilers. It was assumed that the base-load electricity, except for the cogenerated electricity, was produced in stand-alone power plants using wood chips or natural gas, while peak-load electricity and fuel used for transportation were produced from crude oil. The heat pump and district heating systems are found to be most energy efficient, followed by the local fuel-based systems. The wood-fuel-based systems emit about one tenth of the greenhouse gases emitted by the natural-gas-based systems. The sulphur and nitrogen oxide emission, however, is higher for wood-fuel-based systems. Systems based on natural gas are less expensive than the corresponding wood-fuel-based systems. Decarbonization and carbon dioxide sequestration, however, do not reduce the carbon dioxide emission to the low level of the wood-fuel-based systems and, in addition, make the natural-gas-based systems more expensive than the wood-fuel-based systems.
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| 41. |
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| 42. |
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| 43. |
- Gustavsson, Linda, et al.
(författare)
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Sore throat in women after intubation with 6.5 or 7.0 mm endotracheal tube : a quantitative study
- 2014
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Ingår i: Intensive & Critical Care Nursing. - : Elsevier BV. - 0964-3397 .- 1532-4036. ; 30:6, s. 318-324
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Tidskriftsartikel (refereegranskat)abstract
- Background: Women experience more sore throats than men after endotracheal intubation.Aim: The aim of this study was to investigate the incidence of self-rated sore throat immediately,and 2—4 hours postoperatively, in women after elective gynaecological surgery under generalanaesthesia using an endotracheal tube (ETT) size 6.5 or 7.0 mm in inner diameter.Method: Eighty-two female participants who had undergone elective gynaecological surgeryparticipated, 44 and 38 were intubated with size 6.5 mm ETT and 7.0 mm ETT respectively.They estimated the occurrence of sore throat preoperatively and postoperatively, according toa 4-point Likert scale. Statistical data were analysed using the Package for Social Science (SPSS)19.Results: Sore throat was present in 29.5% of participants who were intubated with size 6.5 mmETT immediately postoperatively and in 39.5% of those who were intubated with size 7.0 mmETT.Conclusion: Nurses specialising in the supervision of daily care specific to the intubated patientshould note and alleviate sore throat as part of their nursing care.
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| 44. |
- Gustavsson, Martha, et al.
(författare)
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Everyday doings in a nursing home - described by residents and staff
- 2015
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Ingår i: Scandinavian Journal of Occupational Therapy. - : TAYLOR and FRANCIS LTD. - 1103-8128 .- 1651-2014. ; 22:6, s. 435-441
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Tidskriftsartikel (refereegranskat)abstract
- Objective: For many groups of elderly people it is important to be active, which can be hindered by disabilities that come with age. Research has progressed in this area but mostly concerns the elderly living at home. The aim of this study was to examine how residents and staff at a nursing home described the residents everyday doings. Methods: A nursing home was selected in which 15 of the residents and six of the staff were interviewed about the residents activities during an ordinary day and week. Results: The material was analysed using qualitative content analysis in which two categories emerged: shared doings and individual doings. The shared doings were important for supporting the residents in their social and physical activities, but participation in these was often hampered by reduced functions. The individual doings, where the residents own interests can be promoted, were also hampered by their disabilities. Being able to be active and having something to do were emphasized, either continuing with previous activities or participating in shared activities at the nursing home. Conclusions: Receiving care and being forced to adjust to the context at the nursing home had a significant impact on the residents daily doings. Most of the residents needed help to be able to continue performing their activities or to find new ones. The social environment consisting of other residents and staff also influenced the residents activities.
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| 45. |
- Gustavsson, Per M., et al.
(författare)
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Service Oriented Simulations Concept
- 2005
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Ingår i: Proceedings of the 10th Simulation conference and exhibition. ; , s. 533-538
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In the effort to provide simulation support to the future Network Based Defence (NBD) that are currently being applied by the Swedish Armed Forces (SwAF), and the similair work within US and NATO, the authors opinion is that simulation should be treated as any other services, existing in the operational systems. Meaning that architecture should be conformant between the operational and simulated systems, for a start use the same infrastructure. The choice so far for simulation is the High Level Architecture (HLA). During the author’s participation in ongoing work supporting NBD, questions have gradually been raised if HLA is the simulation path to walk. In the Core Enterprise Services (CES) and Swedish Armed Force Enterprise Architecture (FMA) Services IT-Kernel, core services are specified and HLA do address a lot of non-simulation specific services giving unwanted redundancy. However, the services already defined may with some enhancements deliver the same services addressed within FMA Services ITKernel. The Next Generation HLA could be more than just a simulation standard if it utilizes the FMA ideas. In this paper the authors present the ongoing work, as it stands today, with Service Oriented Simulations, that is an outlook for simulation using the architectural structuring, services, components and infrastructures concepts evolving in FMA and Global Information Grid (GIG). The focus of the work is to enable interoperable simulation support for the whole system lifecycle – Acquisition, Development, Training, Planning, In-the-Field decision support, System removal – within NBD, entailing that the architecture for simulation is uniform regardless of its application and giving end-users the capability to focus on what to simulate instead of how to simulate.
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| 46. |
- Gustavsson, Per M., 1965-, et al.
(författare)
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Towards Service Oriented Simulations
- 2004
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Ingår i: Fall Simulation Interoperability Workshop 2004. ; , s. 219-229
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In the effort to provide simulation support to the future Network Based Defence (NBD)1 that are currently being applied by the Swedish Armed Forces (SwAF), the authors opinion is that simulation should be treated as any other services and use the same architectural requirements addressed in the SwAF Enterprise Architecture (FMA)2 and in subsidiary documents.The choice so far for simulation is the High Level Architecture (HLA). During the author’s participation in ongoing work supporting NBD, questions have gradually been raised if HLA is the simulation path to walk. In the Core Enterprise Services (CES) and FMA Services IT-Kernel, core services are specified and HLA do address a lot of non-simulation specific services giving unwanted redundancy. However, the services already defined may with some enhancements deliver the same services addressed within CES and FMA Services IT-Kernel. Furthermore, HLA also comes with the Federation Development and Execution Process (FEDEP) that introduce process methodology to build HLA federations. Basically FEDEP is a software development process for distributed systems. The Next Generation HLA could be more than just a simulation standard if it utilizes the FMA ideas and avoids the green HLA elephant3.In this paper the authors present the ongoing work, as it stands today, with Service Oriented Simulations, that is an outlook for simulation using the architectural structuring, services, components and infrastructures concepts evolving in FMA and with the Global Information Grid (GIG) Enterprise Services (GES) in mind. The focus is to identify simulation services that encapsulate the core features of simulation. Thereby reducing redundancy in methodology and service as well as enabling interoperable simulation support for the whole system lifecycle – Acquisition, Development, Training, Planning, In-the-Field decision support, System removal – within NBD, entailing that the architecture for simulation is uniform regardless of its application and giving end-users the capability to focus on what to simulate instead of how to simulate.
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| 47. |
- Gustavsson, Åsa
(författare)
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Transthyretin in senile systemic amyloidosis and familial amyloidotic polyneuropathy
- 1994
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The amyloidoses comprise a heterogeneous group of disorders characterized by the deposition of fibrillar, proteinaceous amyloid deposits in various organs and tissues. To date, 17 different proteins of various sizes have been identified as amyloid proteins. Irrespective of the specific protein comprising the amyloid fibrils, the fibrils are all about 10 nm wide and of indefinite length.In the most common familial form of amyloidosis, familial amyloidotic polyneuropathy (FAP), the amyloid fibril protein is the plasma protein transthyretin (TTR). In FAP type I, which is the type found in Sweden, there is a mutation in the TTR gene leading to the substitution of a methionine for valine at position 30. This mutation leads to a form of amyloidosis characterized by polyneuropathy starting in the lower limbs and usually slowly progressing until death occurs. Another TTR-derived form of amyloidosis is senile systemic amyloidosis (SSA). This form of amyloidosis is present in about 25% of people 80 years of age or older. In SSA, amyloid is deposited mainly in the heart but deposits are also found in many other organs.In this study it is demonstrated that normal TTR can form fibrils in vitro. Fibril formation studies were also performed in vitro with synthetic peptides corresponding to parts of the TTR amino acid sequence. These results indicate that TTR peptides with 13-strand secondary structure are fibrillogenic in vitro and are likely important in in vivo amyloidogenesis.The TTR amino acid and DNA sequences in cases with SSA were determined and found to be normal, thus showing that no mutation is necessary for development of this form of amyloidosis. However, cleavage of TTR may be important in fibrillogenesis since TTR fragments lacking 45-51 N-terminal amino acid residues predominated in the amyloid.Antigenic epitopes exposed on normal TTR and TTR derived from amyloid deposits were also examined. The 13-strand H was found to be exposed in amyloid TTR and not in normal TTR, thus suggesting a changed structural conformation of TTR in amyloid fibrils.
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| 48. |
- Haghighi, Mona, et al.
(författare)
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A Comparison of Rule-based Analysis with Regression Methods in Understanding the Risk Factors for Study Withdrawal in a Pediatric Study
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- Regression models are extensively used in many epidemiological studies to understand the linkage between specific outcomes of interest and their risk factors. However, regression models in general examine the average effects of the risk factors and ignore subgroups with different risk profiles. As a result, interventions are often geared towards the average member of the population, without consideration of the special health needs of different subgroups within the population. This paper demonstrates the value of using rule-based analysis methods that can identify subgroups with heterogeneous risk profiles in a population without imposing assumptions on the subgroups or method. The rules define the risk pattern of subsets of individuals by not only considering the interactions between the risk factors but also their ranges. We compared the rule-based analysis results with the results from a logistic regression model in The Environmental Determinants of Diabetes in the Young (TEDDY) study. Both methods detected a similar suite of risk factors, but the rule-based analysis was superior at detecting multiple interactions between the risk factors that characterize the subgroups. A further investigation of the particular characteristics of each subgroup may detect the special health needs of the subgroup and lead to tailored interventions.
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| 49. |
- Haglund, Erik, 1985, et al.
(författare)
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25 Gbit/s transmission over 500 m multimode fibre using 850 nm VCSEL with integrated mode filter
- 2012
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Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 1350-911X .- 0013-5194. ; 48:9, s. 517-518
-
Tidskriftsartikel (refereegranskat)abstract
- An integrated mode filter in the form of a shallow surface relief was used to reduce the spectral width of a high-speed 850 nm vertical-cavity surface-emitting laser (VCSEL). The mode filter reduced the RMS spectral width from 0.9 to 0.3 nm for a VCSEL with an oxide aperture as large as 5 mu m. Because of reduced effects of chromatic and modal fibre dispersion, the mode filter significantly increases the maximum error-free (bit error rate
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| 50. |
- Haglund, Erik, 1985, et al.
(författare)
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850 nm datacom VCSELs for higher-speed and longer-reach transmission
- 2013
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Ingår i: European VCSEL Day 2013.
-
Konferensbidrag (refereegranskat)abstract
- The 850 nm GaAs-based VCSEL is already the dominating technology for transmitters in optical interconnects up to 100 m in datacenters, thanks to low-cost fabrication, excellent high-speed properties at low currents and the existence of high-speed OM4 multimode fiber optimized for this particular wavelength. Future datacenters will require faster and more energy-efficient VCSELs to increase the overall bandwidth and reduce the power consumption of the datacenter network. In addition, longer-reach interconnects exceeding 1 km will also be required as datacenters grow into large multi-building complexes.By optimizing the doping profiles of the DBRs to reduce resistance, using a short (½-λ) cavity to improve longitudinal optical confinement and optimizing the photon lifetime for optimal damping, we obtained a record-high small-signal modulation bandwidth of 28 GHz for a ~4 µm oxide aperture VCSEL. A 7 µm oxide aperture VCSEL (~27 GHz bandwidth) enabled error-free transmission (bit-error-rate 300 m), the large spectral width of VCSELs leads to severe signal degradation by fiber dispersion. We have investigated two methods of fabricating low-spectral width quasi-single mode VCSELs to mitigate this problem. By using a small oxide aperture of ~3 µm, error-free transmission was achieved at 22 Gbit/s over 1.1 km of OM4 fiber. An alternative approach is to use an integrated mode filter in the form of a shallow surface relief to reduce the spectral width of the VCSEL. The mode filter allows for the use of a larger oxide aperture and thereby enables a lower resistance and operation at a lower current density. A 5 µm oxide aperture VCSEL with a mode filter enabled error-free transmission at 25 Gbit/s over 500 m of OM4 fiber.
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