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- Signori, A, et al.
(författare)
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Heterogeneity on long-term disability trajectories in patients with secondary progressive MS: a latent class analysis from Big MS Data network
- 2023
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Ingår i: Journal of neurology, neurosurgery, and psychiatry. - : BMJ. - 1468-330X .- 0022-3050. ; 94:1, s. 23-30
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Tidskriftsartikel (refereegranskat)abstract
- Over the decades, several natural history studies on patients with primary (PPMS) or secondary progressive multiple sclerosis (SPMS) were reported from international registries. In PPMS, a consistent heterogeneity on long-term disability trajectories was demonstrated. The aim of this study was to identify subgroups of patients with SPMS with similar longitudinal trajectories of disability over time.MethodsAll patients with MS collected within Big MS registries who received an SPMS diagnosis from physicians (cohort 1) or satisfied the Lorscheider criteria (cohort 2) were considered. Longitudinal Expanded Disability Status Scale (EDSS) scores were modelled by a latent class growth analysis (LCGA), using a non-linear function of time from the first EDSS visit in the range 3–4.ResultsA total of 3613 patients with SPMS were included in the cohort 1. LCGA detected three different subgroups of patients with a mild (n=1297; 35.9%), a moderate (n=1936; 53.6%) and a severe (n=380; 10.5%) disability trajectory. Median time to EDSS 6 was 12.1, 5.0 and 1.7 years, for the three groups, respectively; the probability to reach EDSS 6 at 8 years was 14.4%, 78.4% and 98.3%, respectively. Similar results were found among 7613 patients satisfying the Lorscheider criteria.ConclusionsContrary to previous interpretations, patients with SPMS progress at greatly different rates. Our identification of distinct trajectories can guide better patient selection in future phase 3 SPMS clinical trials. Additionally, distinct trajectories could reflect heterogeneous pathological mechanisms of progression.
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- Carlsson, C., et al.
(författare)
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Performance characteristics of buried heterostructure VCSELs using semi-insulating GaInP : Fe regrowth
- 2001
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Ingår i: IEEE Journal of Quantum Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9197 .- 1558-1713. ; 37:7, s. 945-950
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Tidskriftsartikel (refereegranskat)abstract
- We have fabricated GaAs-AlGaAs buried heterostructure vertical cavity surface emitting lasers, emitting at 850 nm, using semi-insulating GaInP:Fe regrowth and investigated their static properties. Lasers of different size (10-21 mum) have threshold currents in the range 2.8-7.0 mA, and produce a maximum output power of 1.7-6.0 mW at room temperature. The variation of threshold current with device size shows that the leakage current at the regrowth interface accounts for a significant part of the injection current. In spite of this, a differential quantum efficiency in the range 20%-30% is obtained which indicates that the regrowth interface is smooth and does not introduce any significant scattering loss. Studies of the transverse mode properties suggest that the GaInP provides weak guiding, resulting in single mode operation up to an output power of 0.7 mW and a beam divergence of only 6 degrees for lasers as large as 10 mum.
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- Karlsson, Mikael, et al.
(författare)
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Monolithic integration of continuous-relief diffractive structures with vertical-cavity surface-emitting lasers
- 2003
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Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 15:3, s. 359-361
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we have studied the transfer of diffractive optical elements (DOEs), originally made in resist, into GaAs for monolithic integration with vertical-cavity surface-emitting lasers (VCSELs). The DOEs are blazed gratings and Fresnel lenses, and have been fabricated on the back surface of bottom emitting VCSELs using electron-beam lithography or replication by hot embossing in resist followed by a quick-dry etch step. Diffraction efficiency was measured to be 81% in the first order of diffraction for the blazed grating.
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- Olsen, A Ø, et al.
(författare)
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HBV frequency quintuplers
- 2005
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Ingår i: Book of abstracts: Intl Symp on Space Terahertz Technol, Göteborg, Sweden (2005).
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Konferensbidrag (refereegranskat)
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- Vukusic, J., et al.
(författare)
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Fabrication and characterization of diffractive optical elements in InP for monolithic integration with surface-emitting components
- 2000
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 39:3, s. 398-401
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Tidskriftsartikel (refereegranskat)abstract
- We report on the fabrication and subsequent characterization of binary diffractive optical elements (DOE's) in InP for operation at 1.3 mu m. Fresnel lenses of different focal, lengths and a DOE that splits and focuses an incident beam into a 1 x 4 array of spots (optical fan-out) were fabricated. We realized the surface reliefs by patterning resist, using electron-beam lithography and etching with a chemically assisted ion beam, which produced well-defined patterns with smooth sidewalls and little if no surface roughness. The measured efficiency for the lenses was 36%. For the fan-out element the efficiency and the uniformity error were 26% and 30%, respectively. Spot sizes small as 16 mu m were measured.
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| 15. |
- Vukusic, J., et al.
(författare)
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MOVPE-grown GaInNAsVCSELs at 1.3 mu m with conventional mirror design approach
- 2003
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Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 0013-5194 .- 1350-911X. ; 39:8, s. 662-664
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Tidskriftsartikel (refereegranskat)abstract
- 1.3 mum oxide confined GaInNAs VCSELs designed using the same design philosophy used for standard 850 nm VCSELs is presented. The VCSELs have doped mirrors, with graded and highly doped interfaces, and are fabricated using production-friendly procedures. Multimode VCSELs (I I mum oxide aperture) with an emission wavelength of 1287 nm have a threshold current of 3 mA and produce I mW of output power at 20degreesC. The maximum operating temperature is 95degreesC. Emission at 1303 nm with I mW of output power and a threshold current of 7 mA has been observed from VCSELs with a larger detuning between the gain peak and the cavity resonance.
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- Barrientos Z, C. M., et al.
(författare)
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Vertically illuminated TW-UTC photodiodes for terahertz generation
- 2012
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. - 9780819491534 ; 8452
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Konferensbidrag (refereegranskat)abstract
- More efficient and powerful continuous-wave photonic mixers as terahertz sources are motivated by the need of more versatile local oscillators for submillimeter/terahertz receiver systems. Uni-Travelling Carrier (UTC) photodiodes are very prospective candidates for reaching this objective, but so far only have been reported as lumped-elements or as edge-illuminated optical-waveguide travelling-wave (TW) devices. To overcome the associated power limitations of those implementations, we are developing a novel implementation of the UTC photodiodes which combines a traveling-wave photomixer with vertical velocity-matched illumination in a distributed structure. In this implementation called velocity-matched travelling-wave uni-travelling carrier photodiode, it is possible to obtain in-situ velocity matching of the beat-fringes of the two angled laser beams with the submm/THz-wave on the stripline. In this way, minimum frequency roll-off is achieved by tuning the angle between the two laser beams. A first design of these TW-UTC PDs from our Terahertz Photonics Laboratory at University of Chile has been micro-fabricated at the MC2 cleanroom facility at Chalmers Technical University.
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- Hillert, J, et al.
(författare)
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Treatment Switching and Discontinuation Over 20 Years in the Big Multiple Sclerosis Data Network
- 2021
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Ingår i: Frontiers in neurology. - : Frontiers Media SA. - 1664-2295. ; 12, s. 647811-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Although over a dozen disease modifying treatments (DMTs) are available for relapsing forms of multiple sclerosis (MS), treatment interruption, switching and discontinuation are common challenges. The objective of this study was to describe treatment interruption and discontinuation in the Big MS data network.Methods: We merged information on 269,822 treatment episodes in 110,326 patients from 1997 to 2016 from five clinical registries in this cohort study. Treatment stop was defined as a clinician recorded DMT end for any reason and included treatment interruptions, switching to alternate DMTs and long-term or permanent discontinuations.Results: The incidence of DMT stopping cross the full observation period was lowest in FTY (19.7 per 100 person-years (PY) of treatment; 95% CI 19.2–20.1), followed by NAT (22.6/100 PY; 95% CI 22.2–23.0), IFNβ (23.3/100 PY; 95% CI 23.2–23.5). Of the 184,013 observed DMT stops, 159,309 (86.6%) switched to an alternate DMT within 6 months. Reasons for stopping a drug were stable during the observation period with lack of efficacy being the most common reason followed by lack of tolerance and side effects. The proportion of patients continuing on most DMTs were similarly stable until 2014 and 2015 when drop from 83 to 75% was noted.Conclusions: DMT stopping reasons and rates were mostly stable over time with a slight increase in recent years, with the availability of more DMTs. The overall results suggest that discontinuation of MS DMTs is mostly due to DMT properties and to a lesser extent to risk management and a competitive market.
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- Iaffaldano, P, et al.
(författare)
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Early treatment delays long-term disability accrual in RRMS: Results from the BMSD network
- 2021
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Ingår i: Multiple sclerosis (Houndmills, Basingstoke, England). - : SAGE Publications. - 1477-0970 .- 1352-4585. ; 27:10, s. 1543-1555
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Tidskriftsartikel (refereegranskat)abstract
- The optimal timing of treatment starts for achieving the best control on the long-term disability accumulation in multiple sclerosis (MS) is still to be defined. Objective: The aim of this study was to estimate the optimal time to start disease-modifying therapies (DMTs) to prevent the long-term disability accumulation in MS, using a pooled dataset from the Big Multiple Sclerosis Data (BMSD) network. Methods: Multivariable Cox regression models adjusted for the time to first treatment start from disease onset (in quintiles) were used. To mitigate the impact of potential biases, a set of pairwise propensity score (PS)-matched analyses were performed. The first quintile, including patients treated within 1.2 years from onset, was used as reference. Results: A cohort of 11,871 patients (median follow-up after treatment start: 13.2 years) was analyzed. A 3- and 12-month confirmed disability worsening event and irreversible Expanded Disability Status Scale (EDSS) 4.0 and 6.0 scores were reached by 7062 (59.5%), 4138 (34.9%), 3209 (31.1%), and 1909 (16.5%) patients, respectively. The risk of reaching all the disability outcomes was significantly lower ( p < 0.0004) for the first quintile patients’ group. Conclusion: Real-world data from the BMSD demonstrate that DMTs should be commenced within 1.2 years from the disease onset to reduce the risk of disability accumulation over the long term.
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