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| 2. |
- Anders, Berntson, et al.
(författare)
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Dispersion management with filtering
- 1998
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We present results of analytical and numerical consideration of the pulses in a model of a DM fiber link including the fixed-frequency filters and compensating gain, both taken in the distributed approximation. Combining the variational approximation and perturbative treatment of the filtering and gain terms, we predict stationary propagation regimes. The most important new features are the absence of the minimum DM strength necessary for the existence of the pulses in the case when the average dispersion is nil or normal, and the existence of a minimum necessary normalized power in this case. These features are well corroborated by direct simulations.
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| 3. |
- Anders, Berntson, et al.
(författare)
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Dispersion management with filtering
- 1999
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Ingår i: Optics Letters. - : Optical Society of America Inc.. - 0146-9592 .- 1539-4794. ; 24:8, s. 507-509
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Tidskriftsartikel (refereegranskat)abstract
- With regards to their potential to improving the pulse-based regimes in optical communication networks, dispersion-managed solitons in a fiber link including guiding filters and compensating gain were investigated. Combining the variational approximation and the perturbative treatment of the filtering and gain, stationary regimes are predicted. Among other features, the minimum map strength necessary for the existence of the pulses when path-averaged dispersion (PAD) is zero or normal is absent, rather, a minimum necessary normalized power for any PAD exists.
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| 4. |
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| 5. |
- Berntson, L., et al.
(författare)
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Construct validity of ILAR and EULAR criteria in juvenile idiopathic arthritis : a population based incidence study from the Nordic countries. International League of Associations for Rheumatology. European League Against Rheumatism
- 2001
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Ingår i: Journal of Rheumatology. - 0315-162X .- 1499-2752. ; 28:12, s. 2737-43
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: New classification criteria (ILAR) have been proposed for juvenile idiopathic arthritis (JIA). They are more descriptive than those formerly used [American College of Rheumatology (ACR), European League Against Rheumatism (EULAR)], but require validation against classifications already in use. We validated the ILAR criteria in relation to the EULAR criteria in a prospective, incidence, and population based setting, and analyzed their feasibility. METHODS: Construct validity of ILAR and EULAR classification criteria refers to how closely the 2 instruments are related and how each of them operates in classifying subgroups/categories. Twenty doctors in 5 Nordic countries collected data from the incidence cases within their catchment areas during an 18 month period beginning July 1, 1997. Clinical and serological data from the first year of disease were collected. RESULTS: A total of 322 patients were included. Classification according to the ILAR criteria was possible in 321 patients; 290 patients had a disease duration > or = 3 months and were classified according to the EULAR criteria. One child could only be classified according to the EULAR criteria. Thus, 31/322 (9.6%) children were classified according to the ILAR criteria only. Forty-eight of 321 (15%) patients did not fit into any category and 6% (20/321) fulfilled criteria for2 categories. In the ILAR classification 5 out of 7 categories/subgroups have 2 to 5 specified exclusion criteria that highly discriminate the definition of each patient. In our study the exclusion criteria were fulfilled to only a small extent. CONCLUSION: The EULAR and ILAR criteria differ concerning the operational definitions of the subvariables involved, which complicates their comparison. By using ILAR rather than EULAR criteria the number of cases with juvenile arthritis increased by 10%, considering the first half-year after onset. The validity of the ILAR criteria is low since they often exclude patients from subgroup classification and the possibility of having more than one diagnosis is not negligible. The specified exclusion criteria for some of the subgroups are difficult to fulfill in clinical work and variables involved could be questioned with regard to their consistency.
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| 6. |
- Berntson, L., et al.
(författare)
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Incidence of juvenile idiopathic arthritis in the Nordic countries : A population based study with special reference to the validity of the ILAR and EULAR criteria
- 2003
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Ingår i: Journal of Rheumatology. - 0315-162X .- 1499-2752. ; 30:10, s. 2275-2282
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To find the incidence of juvenile arthritis according to the ILAR and EULAR criteria within defined areas in the Nordic countries, and to study the validity of the ILAR and EULAR criteria from this perspective. METHOD: A longitudinal, prospective, population based study with patients enrolled according to the ILAR and EULAR criteria. Twenty doctors in Iceland, Norway, Sweden, Denmark, and Finland collected data from the incidence cases within their catchment areas over a period of 1.5 years, beginning July 1, 1997. Clinical and serological data from the first year of the disease were collected. RESULTS: In the whole group of 315 patients, the incidence rate was 15 per 100,000 children/year (95% CI 13-17) according to the ILAR criteria, varying from 7 (1-13) in Iceland, 19 (7-31) and 23 (10-36) from 2 different regions in Norway, and 9 (5-12) and 16 (9-23) from 2 different areas in Denmark, to 15 (12-18) in Sweden and 21/100,000/year (15-26) in the Helsinki region in Finland. An early peak in distribution for age of onset was found in girls but not in boys. The number of antinuclear antibody (ANA) positive children in the whole group, made up of children who had undergone at least one analyzed ANA test, was 123/315 (39%). Girls were ANA positive in 83/197 (42%) and boys in 40/118 (34%). Uveitis developed in 27/315 (8.6%) children during the first 6 months of the disease. CONCLUSION: Incidence rates of juvenile arthritis for areas within the Nordic countries were in accord with previous data. The ILAR criteria present slightly higher incidence rates, with a shorter disease duration for inclusion, compared to the EULAR criteria. Patients in one subgroup in either of the criteria sets do not necessarily belong to the expected subgroup in the other set of criteria; e.g., for juvenile ankylosing spondylitis (EULAR) and enthesitis related arthritis (ILAR). Our epidemiological findings are a reminder to be aware of possible new subgroups in children with juvenile arthritis.
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| 7. |
- Berntson, L., et al.
(författare)
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The influence of heredity for psoriasis on the ILAR classification of juvenile idiopathic arthritis
- 2002
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Ingår i: Journal of Rheumatology. - 0315-162X .- 1499-2752. ; 29:11, s. 2454-2458
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To evaluate how heredity for psoriasis influences classification according to the International League of Associations for Rheumatology (ILAR). Heredity for psoriasis is currently both an exclusion and an inclusion criterion for different types of childhood arthritis according to ILAR classification criteria. METHODS: Twenty physicians in 5 Nordic countries prospectively collected data from the incident cases in their catchment areas over an 18 month period beginning July 1, 1997. Clinical and serological data from the first year of disease were collected. RESULTS: Of the 321 patients included who could be classified according to ILAR criteria for childhood arthritis, 50 (15.6%) patients were excluded from 55 classification events and fulfilled criteria for "other arthritis 1" i.e., did not fulfill criteria for any of the other classification categories, primarily because of heredity for psoriasis. If psoriasis in second degree relatives was disregarded as an exclusion criterion, only 8.7% of the patients remained in the "other arthritis 1" subgroup. For 20.6% of the whole group, heredity for psoriasis in a first or second degree relative (or both) and its distribution among arthritis subgroups did not differ except for juvenile psoriatic arthritis. CONCLUSION: We suggest that second degree heredity for psoriasis be withdrawn as an exclusion criterion from the ILAR criteria.
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| 8. |
- Beukelman, Timothy, et al.
(författare)
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A survey of national and multi-national registries and cohort studies in juvenile idiopathic arthritis : challenges and opportunities
- 2017
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Ingår i: Pediatric Rheumatology. - : BIOMED CENTRAL LTD. - 1546-0096. ; 15
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Tidskriftsartikel (refereegranskat)abstract
- Background: To characterize the existing national and multi-national registries and cohort studies in juvenile idiopathic arthritis (JIA) and identify differences as well as areas of potential future collaboration.Methods: We surveyed investigators from North America, Europe, and Australia about existing JIA cohort studies and registries. We excluded cross-sectional studies. We captured information about study design, duration, location, inclusion criteria, data elements and collection methods.Results: We received survey results from 18 studies, including 11 national and 7 multi-national studies representing 37 countries in total. Study designs included inception cohorts, prevalent disease cohorts, and new treatment cohorts (several of which contribute to pharmacosurveillance activities). Despite numerous differences, the data elements collected across the studies was quite similar, with most studies collecting at least 5 of the 6 American College of Rheumatology core set variables and the data needed to calculate the 3-variable clinical juvenile disease activity score. Most studies were collecting medication initiation and discontinuation dates and were attempting to capture serious adverse events.Conclusion: There is a wide-range of large, ongoing JIA registries and cohort studies around the world. Our survey results indicate significant potential for future collaborative work using data from different studies and both combined and comparative analyses.
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| 9. |
- Carlsson, A., et al.
(författare)
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Receiver Model Including Square-Law Detection and ISI from Arbitrary Electrical Filtering
- 2003
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Ingår i: Conference on Optical Fiber Communication, Technical Digest Series. ; , s. 68-69
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Konferensbidrag (refereegranskat)abstract
- A dynamic receiver model, which uses the electrical filter time response to include the effects of inter-symbol-interference (ISI) was described. The model consisted an arrayed waveguide grating (AWG), a photodiode (PD), an electrical low pass filter (LPF) and a decision circuit. The model used matrix formalism, which made it directly applicable to numerical simulations. An example, measurements and numerical results on 10Gbit/s simulations, that showed the influence of ISI from a 4th order Bessel filter on the Bit Error Ratio (BER) was also presented.
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| 10. |
- Carlsson, A., et al.
(författare)
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Rigorous modeling of noise and ISI in optical WDM receivers with arbitrary electrical filtering
- 2002
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Ingår i: Pacific Rim Conference on Lasers and Electro-Optics, CLEO - Technical Digest. ; , s. 532-533
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Konferensbidrag (refereegranskat)abstract
- Rigorous modeling of noise and intersymbol signal interference in optical wavelength division multiplexing receivers with arbitrary electrical filtering was presented. Simulations of a WDM back-to-back system was performed with 32 signal channels. Bit-error-rate was evaluated as a function of received power at the input to the pre-amplifier. Results indicated that for a filter with a narrow bandwidth, the impulse response was spread out, and the detected bit was affected by the impulse response from previous bits.
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