| 11. |
- Broggi, Juli, et al.
(författare)
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Carry-over effects on reproduction in food-supplemented wintering great tits
- 2022
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Ingår i: Journal of Avian Biology. - : Wiley. - 0908-8857 .- 1600-048X. ; 2022:8
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Tidskriftsartikel (refereegranskat)abstract
- Bird winter-feeding has become a popular backyard activity around the world, particularly in northern regions of Europe and America with cold winters. However, the short- and long-term ecological consequences of such artificial feeding remain inconclusive. In seasonal environments, timing of breeding is a crucial aspect that can strongly influence reproductive output and ultimately fitness. Individual condition at the start of the breeding season is especially important in determining breeding success, by influencing the onset of and investment in breeding. However, empirical evidence on the effects of winter feeding on avian breeding performance remain equivocal. We studied onset of reproduction (laying date) and breeding investment (clutch size) over seven consecutive seasons in a population of wild great tits Parus major in southern Sweden. During the first three years of study, no experimental manipulation was undertaken, while over the last four years the study area was exposed to either supplemented or unmanipulated winter feeding conditions. Breeding was positively affected by supplementary feeding during winter, as birds breeding in the supplemented area increased their clutch size compared to birds from the control area, although laying date remained unaffected by winter feeding. Since differences in clutch size were absent during the three years prior to the experimental manipulation, the results suggest that winter supplementary feeding, and not inherent differences between the two areas, was the reason for the observed effect. Both breeding parameters varied over the years of study, although the effects of the experimental manipulation on clutch size remained consistent, which suggests a carry-over effect of winter feeding on subsequent breeding performance.
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| 12. |
- Broggi, Juli, et al.
(författare)
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Mass or pace? Seasonal energy management in wintering boreal passerines
- 2019
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Ingår i: Oecologia. - : Springer Science and Business Media LLC. - 0029-8549 .- 1432-1939. ; 189:2, s. 339-351
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Tidskriftsartikel (refereegranskat)abstract
- Research on winter energy management in small vertebrates has focused on the regulation of body mass (BM) within a framework of starvation-predation trade-off. Winter-acclimatized birds exhibit a seasonal increase in both BM and basal metabolic rate (BMR), although the patterns of co-variation between the two traits remain unknown. We studied this co-variation in three different species of wild titmice, great, blue and willow tits, originating from two boreal regions at different latitudes. Seasonal change in BM and BMR was inter-dependent, particularly in the great tit; however, by contrast, no seasonal change was observed in the willow tit. BMR changed non-linearly in concert with BM with a peak in midwinter for both blue and great tits, whereas such non-linear pattern in willow tit was opposite and independent of BM. Surprisingly, BMR appears to be more sensitive to ambient temperatures than BM in all three species studied. Energy management is a multifaceted strategy that cannot be fully understood without considering reserve levels and energy expenditure simultaneously. Thus, our study indicates that the prevailing conceptual framework based on variation in BM alone is insufficient to understand seasonal energy management in small wintering passerines.
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| 13. |
- Cha, Eunjung, 1985, et al.
(författare)
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Cryogenic low-noise InP HEMTs: A source-drain distance study
- 2016
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Ingår i: 2016 Compound Semiconductor Week, CSW 2016. - 9781509019649 ; , s. Article number 7528576-
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Konferensbidrag (refereegranskat)abstract
- The scaling effect of the source-drain distance was investigated in order to improve the performance of low-noise InP HEMTs at cryogenic temperatures 4-15 K. The highest dc transconductance at an operating temperature of 4.8 K and low bias power was achieved at a source-drain distance of 1.4 mu m. The extracted HEMT minimum noise temperature was 0.9 K at 5.8 GHz for a 3-stage 4-8 GHz hybrid low-noise amplifier at 10 K.
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| 14. |
- Chapman, Ben, et al.
(författare)
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To boldly go: individual differences in boldness influence migratory tendency.
- 2011
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X. ; 14, s. 871-876
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Tidskriftsartikel (refereegranskat)abstract
- Ecology Letters (2011) ABSTRACT: Partial migration, whereby only a fraction of the population migrates, is thought to be the most common type of migration in the animal kingdom, and can have important ecological and evolutionary consequences. Despite this, the factors that influence which individuals migrate and which remain resident are poorly understood. Recent work has shown that consistent individual differences in personality traits in animals can be ecologically important, but field studies integrating personality traits with migratory behaviour are extremely rare. In this study, we investigate the influence of individual boldness, an important personality trait, upon the migratory propensity of roach, a freshwater fish, over two consecutive migration seasons. We assay and individually tag 460 roach and show that boldness influences migratory propensity, with bold individuals being more likely to migrate than shy fish. Our data suggest that an extremely widespread personality trait in animals can have significant ecological consequences via influencing individual-level migratory behaviour.
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| 15. |
- Culina, Antica, et al.
(författare)
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Connecting the data landscape of long-term ecological studies : The SPI-Birds data hub
- 2021
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Ingår i: Journal of Animal Ecology. - : John Wiley & Sons. - 0021-8790 .- 1365-2656. ; 90:9, s. 2147-2160
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Tidskriftsartikel (refereegranskat)abstract
- The integration and synthesis of the data in different areas of science is drastically slowed and hindered by a lack of standards and networking programmes. Long-term studies of individually marked animals are not an exception. These studies are especially important as instrumental for understanding evolutionary and ecological processes in the wild. Furthermore, their number and global distribution provides a unique opportunity to assess the generality of patterns and to address broad-scale global issues (e.g. climate change). To solve data integration issues and enable a new scale of ecological and evolutionary research based on long-term studies of birds, we have created the SPI-Birds Network and Database ()-a large-scale initiative that connects data from, and researchers working on, studies of wild populations of individually recognizable (usually ringed) birds. Within year and a half since the establishment, SPI-Birds has recruited over 120 members, and currently hosts data on almost 1.5 million individual birds collected in 80 populations over 2,000 cumulative years, and counting. SPI-Birds acts as a data hub and a catalogue of studied populations. It prevents data loss, secures easy data finding, use and integration and thus facilitates collaboration and synthesis. We provide community-derived data and meta-data standards and improve data integrity guided by the principles of Findable, Accessible, Interoperable and Reusable (FAIR), and aligned with the existing metadata languages (e.g. ecological meta-data language). The encouraging community involvement stems from SPI-Bird's decentralized approach: research groups retain full control over data use and their way of data management, while SPI-Birds creates tailored pipelines to convert each unique data format into a standard format. We outline the lessons learned, so that other communities (e.g. those working on other taxa) can adapt our successful model. Creating community-specific hubs (such as ours, COMADRE for animal demography, etc.) will aid much-needed large-scale ecological data integration.
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| 16. |
- Cöster, Maria, et al.
(författare)
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Validity, reliability, and responsiveness of a self-reported foot and ankle score (SEFAS)
- 2012
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Ingår i: Acta Orthopaedica. - : Medical Journals Sweden AB. - 1745-3682 .- 1745-3674. ; 83:2, s. 197-203
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Tidskriftsartikel (refereegranskat)abstract
- Background and purpose A questionnaire was introduced by the New Zealand Arthroplasty Registry for use when evaluating the outcome of total ankle replacement surgery. We evaluated the reliability, validity, and responsiveness of the modified Swedish version of the questionnaire (SEFAS) in patients with osteoarthritis or inflammatory arthritis before and/or after their ankle was replaced or fused. Patients and methods The questionnaire was translated into Swedish and cross-culturally adapted according to a standardized procedure. It was sent to 135 patients with ankle arthritis who were scheduled for or had undergone surgery, together with the foot and ankle outcome score (FAOS), the short form 36 (SF-36) score, and the EuroQol (EQ-5D) score. Construct validity was evaluated with Spearman's correlation coefficient when comparing SEFAS with FAOS, SF-36, and EQ-5D, content validity by calculating floor and ceiling effects, test-retest reliability with intraclass correlation coefficient (ICC), internal consistency with Cronbach's alpha (n = 62), agreement by Bland-Altman plot, and responsiveness by effect size and standardized response mean (n = 37). Results For construct validity, we correlated SEFAS with the other scores and 70% or more of our predefined hypotheses concerning correlations could be confirmed. There were no floor or ceiling effects. ICC was 0.92 (CI 95%: 0.88-0.95), Cronbach's alpha 0.96, effect size was 1.44, and the standardized response mean was 1.00. Interpretation SEFAS is a self-reported foot and ankle score with good validity, reliability and responsiveness, indicating that the score can be used to evaluate patients with osteoarthritis or inflammatory arthritis of the ankle and outcome of surgery.
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| 17. |
- Ekberg, Marie, et al.
(författare)
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Hospital admission rates among men and women with symptoms of chronic bronchitis and airflow limitation corresponding to the GOLD stages of chronic obstructive pulmonary disease - A population-based study
- 2008
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Ingår i: Respiratory Medicine. - : Elsevier BV. - 1532-3064 .- 0954-6111. ; 102:1, s. 109-120
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Tidskriftsartikel (refereegranskat)abstract
- Chronic obstructive pulmonary disease is a major cause of increased morbidity and mortality. The aim of this study was to investigate hospital admission rates among individuals with symptoms of chronic bronchitis and among those with airflow limitation corresponding to GOLD stages 1-4. Method: Between 1974 and 1992, 22 044 middle-aged individuals participated in a health screening, which included spirometry (without broncho-dilation), as well as recording of respiratory symptoms and smoking habits. Information on hospital admissions until 31 December 2002 was obtained from local and national registers. The hospital admission rates due to all causes, obstructive Lung disease and cardiovascular disease were analysed among individuals with symptoms of chronic bronchitis and among those with airflow limitation corresponding to GOLD stages 1-4 using ordinal regression with adjustment for age and with individuals with normal lung function and without symptoms of chronic bronchitis as reference group. Results: Symptoms of chronic bronchitis and GOLD stages 1-4 showed increased hospital admission rates (hospital admission rates due to obstructive lung disease excluded) among smokers of both genders. Furthermore, symptoms of chronic bronchitis showed increased hospital admission rates due to obstructive lung disease among smoking women. There were also increased hospital admission rates due to obstructive lung disease among smokers of GOLD stages 1-4 and increased hospital admission rates due to cardiovascular disease among female smokers of GOLD stage 2. Conclusion: Among smokers, symptoms of chronic bronchitis as well airflow limitation corresponding to GOLD stages 1-4 conveyed a substantial morbidity with increased hospital admission rates due to all causes. The burden of disease is most likely underestimated among individuals with symptoms of chronic bronchitis and chronic obstructive pulmonary disease.
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| 18. |
- Ekberg, Marie, et al.
(författare)
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Mortality in GOLD stages of COPD and its dependence on symptoms of chronic bronchitis
- 2005
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Ingår i: Respiratory Research. - : Springer Science and Business Media LLC. - 1465-9921 .- 1465-993X. ; 6, s. 98-106
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Tidskriftsartikel (refereegranskat)abstract
- Background: The GOLD classification of COPD severity introduces a stage 0 ( at risk) comprising individuals with productive cough and normal lung function. The aims of this study were to investigate total mortality risks in GOLD stages 0 - 4 with special focus on stage 0, and furthermore to assess the influence of symptoms of chronic bronchitis on mortality risks in GOLD stages 1 - 4. Method: Between 1974 and 1992, a total of 22 044 middle-aged individuals participated in a health screening, which included a spirometry as well as recording of respiratory symptoms and smoking habits. Individuals with comorbidity at baseline ( diabetes, stroke, cancer, angina pectoris, or heart infarction) were excluded from the analyses. Hazard ratios (HR 95% CI) of total mortality were analyzed in GOLD stages 0 - 4 with individuals with normal lung function and without symptoms of chronic bronchitis as a reference group. HR: s in smoking individuals with symptoms of chronic bronchitis within the stages 1 - 4 were calculated with individuals with the same GOLD stage but without symptoms of chronic bronchitis as reference. Results: The number of deaths was 3674 for men and 832 for women based on 352 324 and 150 050 person-years respectively. The proportion of smokers among men was 50% and among women 40%. Self reported comorbidity was present in 4.6% of the men and 6.6% of the women. Among smoking men, Stage 0 was associated with an increased mortality risk, HR; 1.65 ( 1.32 - 2.08), of similar magnitude as in stage 2, HR; 1.41 ( 1.31 - 1.70). The hazard ratio in stage 0 was significantly higher than in stage 1 HR; 1.13 ( 0.98 - 1.29). Among male smokers with stage 1; HR: 2.04 ( 1.34 - 3.11), and among female smokers with stage 2 disease; HR: 3.16 ( 1.38 - 7.23), increased HR: s were found in individuals with symptoms of chronic bronchitis as compared to those without symptoms of chronic bronchitis. Conclusion: Symptoms fulfilling the definition of chronic bronchitis were associated with an increased mortality risk among male smokers with normal pulmonary function ( stage 0) and also with an increased risk of death among smoking individuals with mild to moderate COPD ( stage 1 and 2).
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| 19. |
- Ellis, Vincenzo A., et al.
(författare)
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Explaining prevalence, diversity and host specificity in a community of avian haemosporidian parasites
- 2020
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Ingår i: Oikos. - : Wiley. - 0030-1299 .- 1600-0706. ; 129:9, s. 1314-1329
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Tidskriftsartikel (refereegranskat)abstract
- Many hypotheses attempt to explain parasite–host associations, but rarely are they examined together in a single community. For hosts, key traits are the proportion of infected individuals (prevalence) and the diversity of parasites infecting them. A key parasite trait is host specificity, ranging from specialists infecting one or a few closely related species to generalists infecting many species. We tested 10 hypotheses to explain host-parasite associations; five ‘host-centric’ (e.g. prevalence is related to host abundance) and five ‘parasite-centric’ (e.g. parasite abundance is related to host specificity). We analyzed a community of 67 locally transmitted avian haemosporidian parasite lineages (genera Plasmodium, Haemoproteus or Leucocytozoon), sampled from 2726 birds (64 species) in southern Sweden. Among host-centric hypotheses, Haemoproteus and Leucocytozoon prevalence and Haemoproteus diversity were related to host habitat preferences, whereas there were no relationships with host abundance or body mass. Haemoproteus and Leucocytozoon prevalences were more similar among closely related than among distantly related host species. Haemoproteus prevalence and diversity were lower in host species with few close relatives (‘evolutionarily distinct’ hosts). Among parasite-centric hypotheses, most lineages, even relative generalists, infected closely related host species more often than expected by chance. However, the host species of Haemoproteus and Leucocytozoon lineages overlapped less among lineages than expected by chance. Specialists did not reach higher prevalences than generalists on single host species. However, the abundance of Haemoproteus lineages was related to host specificity with generalists more common than specialists; this was driven by three closely related generalists. Host specificity of parasites was unrelated to the abundance or evolutionarily distinctiveness of their hosts. Parasite communities are likely structured by many factors and cannot be explained by hypotheses focusing solely on hosts or parasites. However, we found consistent effects of host phylogenetic relationships, plausibly a result of evolutionarily conserved host immune systems limiting parasite distributions.
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| 20. |
- Galeev, Roman, et al.
(författare)
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Genome-wide RNAi Screen Identifies Cohesin Genes as Modifiers of Renewal and Differentiation in Human HSCs
- 2016
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Ingår i: Cell Reports. - : Elsevier BV. - 2211-1247. ; 14:12, s. 2988-3000
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Tidskriftsartikel (refereegranskat)abstract
- To gain insights into the regulatory mechanisms of hematopoietic stem cells (HSCs), we employed a genome-wide RNAi screen in human cord-blood derived cells and identified candidate genes whose knockdown maintained the HSC phenotype during culture. A striking finding was the identification of members of the cohesin complex (STAG2, RAD21, STAG1, and SMC3) among the top 20 genes from the screen. Upon individual validation of these cohesin genes, we found that their knockdown led to an immediate expansion of cells with an HSC phenotype in vitro. A similar expansion was observed in vivo following transplantation to immunodeficient mice. Transcriptome analysis of cohesin-deficient CD34(+) cells showed an upregulation of HSC-specific genes, demonstrating an immediate shift toward a more stem-cell-like gene expression signature upon cohesin deficiency. Our findings implicate cohesin as a major regulator of HSCs and illustrate the power of global RNAi screens to identify modifiers of cell fate.
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