| 1. |
- Andersson, Mikael S., et al.
(författare)
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Thermally induced magnetic relaxation in square artificial spin ice
- 2016
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- The properties of natural and artificial assemblies of interacting elements, ranging from Quarks to Galaxies, are at the heart of Physics. The collective response and dynamics of such assemblies are dictated by the intrinsic dynamical properties of the building blocks, the nature of their interactions and topological constraints. Here we report on the relaxation dynamics of the magnetization of artificial assemblies of mesoscopic spins. In our model nano-magnetic system - square artificial spin ice - we are able to control the geometrical arrangement and interaction strength between the magnetically interacting building blocks by means of nano-lithography. Using time resolved magnetometry we show that the relaxation process can be described using the Kohlrausch law and that the extracted temperature dependent relaxation times of the assemblies follow the Vogel-Fulcher law. The results provide insight into the relaxation dynamics of mesoscopic nano-magnetic model systems, with adjustable energy and time scales, and demonstrates that these can serve as an ideal playground for the studies of collective dynamics and relaxations.
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| 2. |
- Berga, Mercè, et al.
(författare)
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Combined effects of zooplankton grazing and dispersal on the diversity and assembly mechanisms of bacterial metacommunities
- 2015
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Ingår i: Environmental Microbiology. - : Wiley. - 1462-2912 .- 1462-2920. ; 17:7, s. 2275-2287
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Tidskriftsartikel (refereegranskat)abstract
- Effects of dispersal and the presence of predators on diversity, assembly and functioning of bacterial communities are well studied in isolation. In reality, however, dispersal and trophic interactions act simultaneously and can therefore have combined effects, which are poorly investigated. We performed an experiment with aquatic metacommunities consisting of three environmentally different patches and manipulated dispersal rates among them as well as the presence or absence of the keystone species Daphnia magna. Daphnia magnareduced both local and regional diversity, whereas dispersal increased local diversity but decreased beta-diversity having no net effect on regional diversity. Dispersal modified the assembly mechanisms of bacterial communities by increasing the degree of determinism. Additionally, the combination of the D. magna and dispersal increased the importance of deterministic processes, presumably because predator-tolerant taxa were spread in the metacommunity via dispersal. Moreover, the presence of D. magna affected community composition, increased community respiration rates but did not affect bacterial production or abundance, whereas dispersal slightly increased bacterial production. In conclusion, our study suggests that predation by a keystone species such as D. magna and dispersal additively influence bacterial diversity, assembly processes and ecosystem functioning.
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| 3. |
- Hillebrand, Helmut, et al.
(författare)
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Decomposing multiple dimensions of stability in global change experiments
- 2018
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 21:1, s. 21-30
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Tidskriftsartikel (refereegranskat)abstract
- Ecological stability is the central framework to understand an ecosystem's ability to absorb or recover from environmental change. Recent modelling and conceptual work suggests that stability is a multidimensional construct comprising different response aspects. Using two freshwater mesocosm experiments as case studies, we show how the response to single perturbations can be decomposed in different stability aspects (resistance, resilience, recovery, temporal stability) for both ecosystem functions and community composition. We find that extended community recovery is tightly connected to a nearly complete recovery of the function (biomass production), whereas systems with incomplete recovery of the species composition ranged widely in their biomass compared to controls. Moreover, recovery was most complete when either resistance or resilience was high, the latter associated with low temporal stability around the recovery trend. In summary, no single aspect of stability was sufficient to reflect the overall stability of the system.
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| 4. |
- Horner, Nolan S, et al.
(författare)
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Implant-Related Complications and Mortality After Use of Short or Long Gamma Nail for Intertrochanteric and Subtrochanteric Fractures: A Prospective Study with Minimum 13-Year Follow-up.
- 2017
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Ingår i: JB & JS open access. - 2472-7245. ; 2:3
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to evaluate the rates of implant-related complications and mortality after treatment of an intertrochanteric or subtrochanteric fracture with a short or long Gamma nail.Between September 1998 and August 2003, 644 patients at 2 centers treated with a long or short Gamma nail for a hip fracture were prospectively enrolled in this study. These patients were followed until they reached 1 of the study end points, which included death, a reoperation directly related to the Gamma nail, or the end date of the study.The average age (and standard deviation) of the patients included in the study was 81.3 ± 8.6 years at the time of the operation, and 28.3% of the patients were male. The rate of implant-related complications was 9.9%. The most common complications included peri-implant fracture (4.2%), proximal lateral thigh discomfort requiring extraction of the implant (2.0%), and lag-screw cutout (1.1%). Interestingly, more than half (56%) of the 27 peri-implant fractures occurred >1.5 years after the index operation. The median time from the operation to death was 2.9 years (range, 0 to 17.1 years). The 30-day mortality rate after treatment was 9.5%. Patients with American Society of Anesthesiologists (ASA) class-3 or 4 physical status had a significantly higher risk of mortality than ASA class-1 patients.Gamma nails are effective in the treatment of intertrochanteric and subtrochanteric fractures. However, 9.8% of patients had complications requiring additional surgery. The most common serious complications include peri-implant fracture and lag-screw cutout. Several peri-implant fractures occurred long after the index procedure. Patients had a high rate of mortality (27%) after 1 year, and higher preoperative ASA class was found to be a predictor of increased risk of mortality. Therefore, clinicians must carefully consider patients' preoperative comorbidities when counselling patients on the risks of surgery.Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.
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| 5. |
- Karp, Daniel S., et al.
(författare)
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Crop pests and predators exhibit inconsistent responses to surrounding landscape composition
- 2018
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 115:33, s. 7863-7870
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Tidskriftsartikel (refereegranskat)abstract
- The idea that noncrop habitat enhances pest control and represents a win–win opportunity to conserve biodiversity and bolster yields has emerged as an agroecological paradigm. However, while noncrop habitat in landscapes surrounding farms sometimes benefits pest predators, natural enemy responses remain heterogeneous across studies and effects on pests are inconclusive. The observed heterogeneity in species responses to noncrop habitat may be biological in origin or could result from variation in how habitat and biocontrol are measured. Here, we use a pest-control database encompassing 132 studies and 6,759 sites worldwide to model natural enemy and pest abundances, predation rates, and crop damage as a function of landscape composition. Our results showed that although landscape composition explained significant variation within studies, pest and enemy abundances, predation rates, crop damage, and yields each exhibited different responses across studies, sometimes increasing and sometimes decreasing in landscapes with more noncrop habitat but overall showing no consistent trend. Thus, models that used landscape-composition variables to predict pest-control dynamics demonstrated little potential to explain variation across studies, though prediction did improve when comparing studies with similar crop and landscape features. Overall, our work shows that surrounding noncrop habitat does not consistently improve pest management, meaning habitat conservation may bolster production in some systems and depress yields in others. Future efforts to develop tools that inform farmers when habitat conservation truly represents a win–win would benefit from increased understanding of how landscape effects are modulated by local farm management and the biology of pests and their enemies. © 2018 National Academy of Sciences. All rights reserved.
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| 6. |
- Lebret, Karen, et al.
(författare)
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High abundances of the nuisance raphidophyte Gonyostomum semen in brown water lakes are associated with high concentrations of iron
- 2018
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Algal blooms occur frequently in lakes and oceans and the causes and consequences of those are often studied. In this study, we focus on a less well known type of algal bloom by the freshwater raphidophyte Gonyostomum semen. This species' abundance and occurrence is increasing, especially in brown water lakes, the most abundant lake type in the boreal zone. The aim of the study was to investigate which environmental factors are associated with G. semen by statistical evaluation of field data of 95 Swedish lakes over five years. Although we found G. semen to be associated with dark waters it was, contrary to our expectations, mainly high concentrations of iron, and only to a lesser extent high TOC (total organic carbon) concentrations, that were associated with blooms of G. semen. In addition, high phosphorus concentrations and low pH also appear to facilitate G. semen blooms. We suggest that browning of lakes caused by increased iron concentrations may decrease net heterotrophy by fostering heavy algal blooms, i.e. the opposite to commonly assumed effects of increased DOM (dissolved organic matter).
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| 7. |
- Sako, Masao, et al.
(författare)
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The Data Release of the Sloan Digital Sky Survey-II Supernova Survey
- 2018
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Ingår i: Publications of the Astronomical Society of the Pacific. - : IOP Publishing. - 0004-6280 .- 1538-3873. ; 130:988
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes the data release of the Sloan Digital Sky Survey-II (SDSS-II) Supernova Survey conducted between 2005 and 2007. Light curves, spectra, classifications, and ancillary data are presented for 10,258 variable and transient sources discovered through repeat ugriz imaging of SDSS Stripe 82, a 300 deg(2) area along the celestial equator. This data release is comprised of all transient sources brighter than r similar or equal to 22.5 mag with no history of variability prior to 2004. Dedicated spectroscopic observations were performed on a subset of 889 transients, as well as spectra for thousands of transient host galaxies using the SDSS-III BOSS spectrographs. Photometric classifications are provided for the candidates with good multi-color light curves that were not observed spectroscopically, using host galaxy redshift information when available. From these observations, 4607 transients are either spectroscopically confirmed, or likely to be, supernovae, making this the largest sample of supernova candidates ever compiled. We present a new method for SN host-galaxy identification and derive host-galaxy properties including stellar masses, star formation rates, and the average stellar population ages from our SDSS multi-band photometry. We derive SALT2 distance moduli for a total of 1364 SN. Ia with spectroscopic redshifts as well as photometric redshifts for a further 624 purely photometric SN. Ia candidates. Using the spectroscopically confirmed subset of the three-year SDSS-II SN. Ia sample and assuming a flat.CDM cosmology, we determine Omega(M) = 0.315 +/- 0.093 (statistical error only) and detect a non-zero cosmological constant at 5.7 sigma.
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| 8. |
- Svensson, MK, et al.
(författare)
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The risk for diabetic nephropathy is low in young adults in a 17-year follow-up of the Diabetes Incidence Study in Sweden (DISS) : Higher age and BMI at diabetes onset can be important risk factors
- 2015
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Ingår i: Diabetes/Metabolism Research Reviews. - : John Wiley & Sons. - 1520-7552 .- 1520-7560. ; 31:2, s. 138-146
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: To estimate the occurrence of diabetic nephropathy (DN) in a population-based cohort of patients diagnosed with diabetes as young adults (15-34 years). Methods: All 794 patients registered 1987-1988 in the Diabetes Incidence Study in Sweden (DISS) were invited to a follow-up study 15-19 years after diagnosis and 468 (58%) participated. Islet cell antibodies were used to classify type of diabetes.RESULTS: After median 17 years of diabetes 15% of all patients, 14% T1DM and 25% T2DM, were diagnosed with DN. 91% had micro- and 8.6% macroalbuminuria. Older age at diagnosis (HR 1.05; 95% CI 1.01-1.10 per year) was an independent and a higher BMI at diabetes diagnosis (HR 1.04; 95% CI 1.00-1.09 per 1 kg/m(2) ) a near-significant predictor of development of DN. Age at onset of diabetes (p = 0.041), BMI (p = 0.012) and HbA1c (p < 0.001) were significant predictors of developing DN between 9 and 17 years of diabetes. At 17 years of diabetes duration, a high HbA1c level (OR 1.06; 95% CI 1.03-1.08 per 1 mmol/mol increase) and systolic blood pressure (OR 1.08; 95% CI 1.05-1.12 per 1 mmHg increase) were associated with DN.CONCLUSIONS: Patients with T2DM diagnosed as young adults seem to have an increased risk to develop DN compared to those with T1DM. Older age and higher BMI at diagnosis of diabetes were risk markers of development of DN. In addition, poor glycaemic control but not systolic blood pressure at 9 years of follow up were risk markers for later development of DN.
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