| 1. |
- Barker, A., et al.
(författare)
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Age-dependent decline of beta-cell function in type 1 diabetes after diagnosis: a multi-centre longitudinal study
- 2014
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Ingår i: Diabetes, obesity and metabolism. - : Wiley. - 1462-8902 .- 1463-1326. ; 16:3, s. 262-267
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Tidskriftsartikel (refereegranskat)abstract
- AimsC-peptide secretion is currently the only available clinical biomarker to measure residual -cell function in type 1 diabetes. However, the natural history of C-peptide decline after diagnosis can vary considerably dependent upon several variables. We investigated the shape of C-peptide decline over time from type 1 diabetes onset in relation to age at diagnosis, haemoglobin A1c (HbA1c) levels and insulin dose. MethodsWe analysed data from 3929 type 1 diabetes patients recruited from seven European centres representing all age groups at disease onset (childhood, adolescence and adulthood). The influence of the age at onset on -cell function was investigated in a longitudinal analysis at diagnosis and up to 5-years follow-up. ResultsFasting C-peptide (FCP) data at diagnosis were available in 3668 patients stratified according to age at diagnosis in four groups (less than5years, n=344; greater than5yearsless than10years, n=668; greater than10yearsless than18years, n=991; greater than18years, n=1655). FCP levels were positively correlated with age (pless than0.001); the subsequent decline in FCP over time was log-linear with a greater decline rate in younger age groups (pless than0.0001). ConclusionsThis study reveals a positive correlation between age at diagnosis of type 1 diabetes and FCP with a more rapid decline of -cell function in the very young patients. These data can inform the design of clinical trials using C-peptide values as an end-point for the effect of a given treatment.
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| 2. |
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| 3. |
- Lauria, A., et al.
(författare)
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BMI is an important driver of beta-cell loss in type 1 diabetes upon diagnosis in 10 to 18-year-old children
- 2015
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Ingår i: European Journal of Endocrinology. - : BioScientifica. - 0804-4643 .- 1479-683X. ; 172:2, s. 107-113
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Body weight-related insulin resistance probably plays a role in progression to type 1 diabetes, but has an uncertain impact following diagnosis. In this study, we investigated whether BMI measured at diagnosis was an independent predictor of C-peptide decline 1-year post-diagnosis. Design: Multicentre longitudinal study carried out at diagnosis and up to 1-year follow-up. Methods: Data on C-peptide were collected from seven diabetes centres in Europe. Patients were grouped according to age at diagnosis (less than5 years, n = 126; greater than5 years less than10 years, n = 295; greater than10 years less than18 years, n = 421; greater than18 years, n = 410). Linear regression was used to investigate whether BMI was an independent predictor of change in fasting C-peptide over 1 year. Models were additionally adjusted for baseline insulin dose and HbA1c. Results: In individuals diagnosed between 0 and 5 years, 5 and 10 years and those diagnosed greater than18 years, we found no association between BMI and C-peptide decline. In patients aged 10-18 years, higher BMI at baseline was associated with a greater decline in fasting C-peptide over 1 year with a decrease (beta 95% CI; P value) of 0.025 (0.010, 0.041) nM/kg per m(2) higher baseline BMI (P = 0.001). This association remained significant after adjusting for gender and differences in HbA1c and insulin dose (beta = 0.026, 95% CI = 0.0097, 0.042; P = 0.002). Conclusions: These observations indicate that increased body weight and increased insulin demand are associated with more rapid disease progression after diagnosis of type 1 diabetes in an age group 10-18 years. This should be considered in studies of beta-cell function in type 1 diabetes.
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| 5. |
- Nordwall, F, et al.
(författare)
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Comparing size-limit strategies for exploitation of a self-thinned stream fish population
- 2000
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Ingår i: Fisheries Management and Ecology. - : Wiley. - 0969-997X. ; 7:5, s. 413-424
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Tidskriftsartikel (refereegranskat)abstract
- There is increasing evidence that territorial stream fish populations exhibit some degree of self-thinning. Four size-limit strategies were examined, under which a size-structured model population exhibiting self-thinning was exploited. The effects of: (1) increased minimum-size limits; (2) protection of spawners; (3) decreasing maximum-size limits; and (4) slot limits (prescribe lower and upper size limits of fish that must be released) were analysed in terms of population size and mean body size in the population after harvest. Biomass and numbers harvested, mean size of fish taken and proportions of different sizes in the population after harvesting were also analysed. Combinations of high exploitation rates and high minimum-size limits maximized both the number and biomass harvested while it favoured post-harvest abundance and the proportion of larger sizes in the population. When harvest rates and minimum-sizes were increased, the combinations of these that maintained or increased yield were successively narrowed. Protection of spawners and slot limits did not come close to reaching the levels of post-harvest abundance, yield, positive size structure and endpoints of harvest rates that were obtained with a high minimum size applied to the fishery. Maximum-size limits favoured the abundance of smaller size-classes. The results emphasize the advantages of setting the largest sizes of fish in the population as a minimum size that can legally be retained.
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| 6. |
- Nordwall, F, et al.
(författare)
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Simulated harvesting of stream salmonids with a seasonal life history
- 2000
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Ingår i: North American Journal of Fisheries Management. - 0275-5947. ; 20:2, s. 481-492
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Tidskriftsartikel (refereegranskat)abstract
- We assessed the influence of timing of harvests on an age-structured population by altering the order of the harvest in relation to density-dependent recruitment and winter mortality. To analyze the effects of harvest timing on a general population of stream salmonids with five age-classes, we used three management strategies: no minimum size limits and two minimum size limits with increasing degrees of protection. The effects on population size, yield, age structure, and population stability were analyzed. Harvest timing greatly influenced the mean population size. A low to moderate harvest increased mean population size in cases with strong density dependence. This increase was even greater at low exploitation levels when harvesting occurred before recruitment. Increasing minimum size limits produced improved population sizes and mean size of fish caught, but yield was lower. Mean population sizes differed in relation to combinations of harvest timing, size limits, and levels of exploitation. In cases where mean population sizes were maintained or increased, the population behavior was mainly attributed to an increased survival of recruits and the stabilizing properties that harvesting had on the population dynamics. This suggests that as harvest rates increase, the population harvested will become increasingly even-aged, and there will be a higher drop in yield but not in mean size of the fish caught. Our results have important management implications but are sensitive to relationships for density-dependent recruitment and mortality.
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| 7. |
- Rodrigo Navarro, Jaime, et al.
(författare)
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High performance and low complexity carrier phase recovery schemes for 64-QAM coherent optical systems
- 2017
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Ingår i: 2017 Optical Fiber Communications Conference and Exhibition, OFC 2017 - Proceedings. - : Institute of Electrical and Electronics Engineers Inc.. - 9781943580231
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Konferensbidrag (refereegranskat)abstract
- We experimentally validate two novel CPR schemes outperforming existing CPRs in complexity and performance. A complexity reduction of at least a factor of 4 is reported compared to the BPS algorithm for a 64QAM system.
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| 8. |
- Öhlund, Gunnar, et al.
(författare)
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Life history and large-scale habitat use of brown trout (salmo trutta) and brook trout (salvelinus fontinalis) - implications for species replacement patterns
- 2008
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Ingår i: Canadian Journal of Fisheries and Aquatic Sciences. ; 65, s. 633-644
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Tidskriftsartikel (refereegranskat)abstract
- Simple models of temperature-mediated interference competition have generally failed to explain salmonid species replacement patterns along altitudinal gradients, a fact that emphasizes the need to link individual features and their relation to habitat characteristics to population-level dynamics. We compared life history parameters in stream resident populations of brook trout (/Salvelinus fontinalis/) and brown trout (/Salmo trutta/) in eight boreal streams. By use of electro-fishing data from 1000 sites, we analyzed and related differences in life history traits to habitat- and interaction-related patterns of growth and densities of brook and brown trout, respectively. Brown trout were competitively dominant throughout the size span of sampled sympatric sites and lowered growth rates in sympatry were mainly caused by environmental factors, revealing a link between brook trout invasions and habitat-related limitations on brown trout performance. Still, the frequency of allopatric brook trout sites increased in the smallest watersheds, indicating that localities with a high degree of brook trout dominance rarely sustain brown trout over time. Brook trout populations had higher turn-over rates and proportions of mature females than brown trout populations. Our results suggest growth potential and its effect on population fecundity as a critical factor limiting competitive ability and distribution of brown trout in Swedish brook trout dominated headwaters.
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