| 1. |
- Akram, Nadeem, 1971-, et al.
(författare)
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Experimental characterization of high-speed 1.55 mu m buried heterostructure InGaAsP/InGaAlAs quantum-well lasers
- 2009
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Ingår i: Journal of the Optical Society of America. B, Optical physics. - 0740-3224 .- 1520-8540. ; 26:2, s. 318-327
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Tidskriftsartikel (refereegranskat)abstract
- Detailed experimental characterization is performed for 1550 nm semi-insulating regrown buried heterostructure Fabry-Perot (FP) lasers having 20 InGaAsP/InGaAlAs strain-balanced quantum wells (QWs) in the active region. Light-current-voltage performance, electrical impedance, small-signal response below and above threshold, amplified spontaneous emission spectrum below threshold and relative intensity noise spectrum are measured. Different laser parameters such as external differential quantum efficiency eta(d), background optical loss alpha(i), K-factor, D-factor, characteristic temperature T-0, differential gain dg/dn, gain-compression factor epsilon, carrier density versus current, differential carrier lifetime tau(d), optical gain spectrum below threshold, and chirp parameter alpha are extracted from these measurements. The FP lasers exhibited a high T-0 (78-86.5 degrees C) and very high-resonance frequency (23.7 GHz). The results indicate that appropriately designed lasers having a large number of InGaAsP well/InGaAlAs barrier QWs with shallow valence-band discontinuity can be useful for un-cooled high-speed direct-modulated laser applications.
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| 2. |
- Akram, Nadeem, 1971-, et al.
(författare)
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High-Speed Performance of 1.55 µm Buried Hetero-Structure Lasers with 20 InGaAsP/InGaAlAs Quantum-Wells
- 2006
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Ingår i: 2006 European Conference on Optical Communications Proceedings, ECOC 2006. - : IEEE. - 9782912328397 ; , s. 1-2
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Konferensbidrag (refereegranskat)abstract
- 1550 nm re-grown FP lasers having 20 InGaAsP/InGaAlAs strain-balanced QWs exhibit low threshold current density, high T0 (78.0 #x000B0;C) and high resonance frequency (24 GHz) indicating that a large number of shallow barrier QWs are attractive for un-cooled high-speed direct-modulation applications.
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| 3. |
- Akram, Nadeem, et al.
(författare)
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The effect of barrier composition on the vertical carrier transport and lasing properties of 1.55-mu m multiple quantum-well structures
- 2006
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Ingår i: IEEE Journal of Quantum Electronics. - 0018-9197 .- 1558-1713. ; 42:7, s. 713-714
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the effect of barrier bandgap and composition on the optical performance of 1.55-mu m InGaAsP/In-GaAsP and InGaAsP/InGaAlAs multiple quantum-well structures and Fabry-Perot lasers is evaluated experimentally. Direct vertical carrier transport measurements were performed through strain-compensated multiple quantum-well (MQW) test structures using femto-second laser pulse excitation and time-resolved photoluminescence up-conversion method. MQW test structures were grown with different barrier composition (InGaAsP and InGaAlAs) and barrier bandgap (varied from lambda(g) = 1440 to 1260 nm) having different conduction band Delta E-c and valence band discontinuity Delta E-v, while keeping the same InGaAsP well composition for all the structures. The ambipolar carrier transport was found to be faster in the structures with lower valence band discontinuity Delta E-v. Regrown semi-insulating buried heterostructure Fabry-Perot (SIBH-FP) lasers were fabricated from similar QWs and their static light-current-voltage characteristics (including optical gain and chirp spectra below threshold) and thermal characteristics were measured. Lasers with InGaAlAs barrier showed improved high-temperature operation, higher optical gain, higher differential gain, and lower chirp, making them suitable candidates for high-bandwidth directly modulated uncooled laser applications.
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| 4. |
- Anderson, Dan, 1943, et al.
(författare)
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Microwave breakdown in RF devices
- 2006
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Ingår i: 33rd European Physical Society Conference on Plasma Physics, Rome, June 19-23, 2006. ; , s. 429-
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Konferensbidrag (refereegranskat)
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| 5. |
- Berntsson Svensson, Richard, et al.
(författare)
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Introducing Support for Release Planning of Quality Requirements - An Industrial Evaluation of the QUPER Model
- 2008
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Ingår i: Second International Workshop on Software Product Management, 2008. IWSPM '08.. - 9781424440832 ; , s. 20-28
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Konferensbidrag (refereegranskat)abstract
- In market-driven product development and release planning, it is important to market success to find the right balance among competing quality requirements. To address this issue, a conceptual model that incorporates quality as a dimension in addition to the cost and value dimensions used in prioritisation approaches for functional requirements has been developed. In this paper, we present an industrial evaluation of the model. The results indicate that the quality performance model provides helpful information about quality requirements in release planning. All subjects stated that the most difficult estimations may be more accurate by using the quality performance model.
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| 6. |
- Bishop, D. Timothy, et al.
(författare)
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Genome-wide association study identifies three loci associated with melanoma risk
- 2009
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 41:8, s. 920-925
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Tidskriftsartikel (refereegranskat)abstract
- We report a genome-wide association study of melanoma conducted by the GenoMEL consortium based on 317K tagging SNPs for 1,650 selected cases and 4,336 controls, with replication in an additional two cohorts (1,149 selected cases and 964 controls from GenoMEL, and a population-based case-control study in Leeds of 1,163 cases and 903 controls). The genome-wide screen identified five loci with genotyped or imputed SNPs reaching P < 5 x 10(-7). Three of these loci were replicated: 16q24 encompassing MC1R (combined P = 2.54 x 10(-27) for rs258322), 11q14-q21 encompassing TYR (P = 2.41 x 10(-14) for rs1393350) and 9p21 adjacent to MTAP and flanking CDKN2A (P = 4.03 x 10(-7) for rs7023329). MC1R and TYR are associated with pigmentation, freckling and cutaneous sun sensitivity, well-recognized melanoma risk factors. Common variants within the 9p21 locus have not previously been associated with melanoma. Despite wide variation in allele frequency, these genetic variants show notable homogeneity of effect across populations of European ancestry living at different latitudes and show independent association to disease risk.
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| 7. |
- Brohet, Richard M., et al.
(författare)
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Oral contraceptives and breast cancer risk in the international BRCA1/2 carrier cohort study: A report from EMBRACE, GENEPSO, GEO-HEBON, and the IBCCS Collaborating Group
- 2007
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Ingår i: Journal of Clinical Oncology. - 1527-7755. ; 25:25, s. 3831-3836
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Tidskriftsartikel (refereegranskat)abstract
- Purpose Earlier studies have shown that endogenous gonadal hormones play an important role in the etiology of breast cancer among BRCA1/ 2 mutation carriers. So far, little is known about the safety of exogenous hormonal use in mutation carriers. In this study, we examined the association between oral contraceptive use and risk of breast cancer among BRCA1/ 2 carriers. Patients and Methods In the International BRCA1/ 2 Carrier Cohort study ( IBCCS), a retrospective cohort of 1,593 BRCA1/ 2 mutation carriers was analyzed with a weighted Cox regression analysis. Results We found an increased risk of breast cancer for BRCA1/ 2 mutation carriers who ever used oral contraceptives ( adjusted hazard ratio [ HR] = 1.47; 95% CI, 1.16 to 1.87). HRs did not vary according to time since stopping use, age at start, or calendar year at start. However, a longer duration of use, especially before first full- term pregnancy, was associated with an increased risk of breast cancer for both BRCA1 and BRCA2 mutation carriers ( 4 or more years of use before first full-term pregnancy: HR = 1.49 [ 95% CI, 1.05 to 2.11] for BRCA1 carriers and HR = 2.58 [ 95% CI, 1.21 to 5.49] for BRCA2 carriers). Conclusion No evidence was found among BRCA1/ 2 mutation carriers that current use of oral contraceptives is associated with risk of breast cancer more strongly than is past use, as is found in the general population. However, duration of use, especially before first full- term pregnancy, may be associated with an increasing risk of breast cancer among both BRCA1 and BRCA2 mutation carriers.
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| 8. |
- Brown, Kevin M., et al.
(författare)
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Common sequence variants on 20q11.22 confer melanoma susceptibility
- 2008
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Ingår i: Nature Genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 40:7, s. 838-840
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Tidskriftsartikel (refereegranskat)abstract
- We conducted a genome-wide association pooling study for cutaneous melanoma and performed validation in samples totaling 2,019 cases and 2,105 controls. Using pooling, we identified a new melanoma risk locus on chromosome 20 (rs910873 and rs1885120), with replication in two further samples (combined P < 1 x 10(-15)). The per allele odds ratio was 1.75 (1.53, 2.01), with evidence for stronger association in early-onset cases.
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| 9. |
- Chang-Claude, Jenny, et al.
(författare)
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Age at menarche and menopause and breast cancer risk in the International BRCA1/2 Carrier Cohort Study
- 2007
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Ingår i: Cancer Epidemiology Biomarkers and Prevention. - 1055-9965. ; 16:4, s. 740-746
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Tidskriftsartikel (refereegranskat)abstract
- Background: Early menarche and late menopause are important risk factors for breast cancer, but their effects on breast cancer risk in BRCA1 and BRCA2 carriers are unknown. Methods: We assessed breast cancer risk in a large series of 1,187 BRCA1 and 414 BRCA2 carriers from the International BRCA1/2 Carrier Cohort Study. Rate ratios were estimated using a weighted Cox-regression approach. Results: Breast cancer risk was not significantly related to age at menopause {hazard ratio [HR] for menopause below age 35 years, 0.60 [95% confidence interval (95% CI), 0.25-1.44]; 35 to 40 years, 1.15 [0.65-2.04]; 45 to 54 years, 1.02 [0.65-1.60]; ≥55 years, 1.12 [0.12-5.02], as compared with premenopausal women}. However, there was some suggestion of a reduction in risk after menopause in BRCA2 carriers. There was some evidence of a protective effect of oophorectomy (HR, 0.56; 95% CI, 0.29-1.09) and a significant trend of decreasing risk with increasing time since oophorectomy, but no apparent effect of natural menopause. There was no association between age at menarche and breast cancer risk, nor any apparent association with the estimated total duration of breast mitotic activity. Conclusions: These results are consistent with other observations suggesting a protective effect of oophorectomy, similar in relative effect to that in the general population. The absence of an effect of age at natural menopause is, however, not consistent with findings in the general population and may reflect the different natural history of the disease in carriers.
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| 10. |
- Chang, Yu-mei, et al.
(författare)
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Sun exposure and melanoma risk at different latitudes: a pooled analysis of 5700 cases and 7216 controls
- 2009
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Ingår i: International Journal of Epidemiology. - : Oxford University Press (OUP). - 1464-3685 .- 0300-5771. ; 38:3, s. 814-830
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Tidskriftsartikel (refereegranskat)abstract
- Background Melanoma risk is related to sun exposure; we have investigated risk variation by tumour site and latitude. Methods We performed a pooled analysis of 15 case-control studies (5700 melanoma cases and 7216 controls), correlating patterns of sun exposure, sunburn and solar keratoses (three studies) with melanoma risk. Pooled odds ratios (pORs) and 95% Bayesian confidence intervals (CIs) were estimated using Bayesian unconditional polytomous logistic random-coefficients models. Results Recreational sun exposure was a risk factor for melanoma on the trunk (pOR 1.7; 95% CI: 1.4-2.2) and limbs (pOR 1.4; 95% CI: 1.1-1.7), but not head and neck (pOR 1.1; 95% CI: 0.8-1.4), across latitudes. Occupational sun exposure was associated with risk of melanoma on the head and neck at low latitudes (pOR 1.7; 95% CI: 1.0-3.0). Total sun exposure was associated with increased risk of melanoma on the limbs at low latitudes (pOR 1.5; 95% CI: 1.0-2.2), but not at other body sites or other latitudes. The pORs for sunburn in childhood were 1.5 (95% CI: 1.3-1.7), 1.5 (95% CI: 1.3-1.7) and 1.4 (95% CI: 1.1-1.7) for melanoma on the trunk, limbs, and head and neck, respectively, showing little variation across latitudes. The presence of head and neck solar keratoses was associated with increased risk of melanoma on the head and neck (pOR 4.0; 95% CI: 1.7-9.1) and limbs (pOR 4.0; 95% CI: 1.9-8.4). Conclusion Melanoma risk at different body sites is associated with different amounts and patterns of sun exposure. Recreational sun exposure and sunburn are strong predictors of melanoma at all latitudes, whereas measures of occupational and total sun exposure appear to predict melanoma predominately at low latitudes. Keywords Melanoma, recreational sun exposure, occupational sun exposure, total sun exposure, sunburn, solar keratoses
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