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| 2. |
- Carlsson, Tobias, et al.
(författare)
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Algorithm for generating a Brownian motion on a sphere
- 2010
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Ingår i: Journal of physics A: Mathematical and theoretical. - : IOP Publishing. - 1751-8113 .- 1751-8121. ; 43:50, s. 505001-
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Tidskriftsartikel (refereegranskat)abstract
- We present a new algorithm for generation of a random walk on a two-dimensional sphere. The algorithm is obtained by viewing the 2-sphere as the equator in the 3-sphere surrounded by an infinitesimally thin band with boundary which reflects Brownian particles and then applying known effective methods for generating Brownian motion on the 3-sphere. To test the method, the diffusion coefficient was calculated in computer simulations using the new algorithm and, for comparison, also using a commonly used method in which the particle takes a Brownian step in the tangent plane to the 2-sphere and is then projected back to the spherical surface. The two methods are in good agreement for short time steps, while the method presented in this paper continues to give good results also for larger time steps, when the alternative method becomes unstable.
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| 3. |
- Kamerlin, Natasha, et al.
(författare)
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Construction of a closed polymer network for computer simulations
- 2014
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 141:15, s. 154113-
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Tidskriftsartikel (refereegranskat)abstract
- Computer simulations are an important tool for linking the behaviour of polymer materials to the properties of the constituent polymer chains. In simulations, one normally uses periodic boundary conditions to mimic a macroscopic system. For a cross-linked polymer network, this will impose restrictions on the motion of the polymer chains at the borders of the simulation cell. We present a new method for constructing a three-dimensional closed network without periodic boundaries by embedding the system onto the surface of a sphere in four dimensions. This method can also be used to construct finite-sized gel particles for simulating the swelling of particles in a surrounding solvent. The method is described in algorithmic detail to allow the incorporation of the method into different types of simulation programs. We also present the results of Brownian dynamics simulations, analyzing the end-to-end distribution, radial distribution function, and the pore size distribution for different volume fractions and for chains with varying stiffness.
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| 5. |
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| 6. |
- Adams, Emma, 1989, et al.
(författare)
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Water–gas-shift assisted ammonia formation over Pd/Ce/alumina
- 2018
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Ingår i: Catalysis Today. - : Elsevier BV. - 0920-5861. ; 307, s. 169-174
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Tidskriftsartikel (refereegranskat)abstract
- We report experimental results for the water–gas-shift assisted formation of ammonia from nitric oxide over alumina supported palladium, modified with various amounts (0–38 wt.%) of cerium. Static and transient flow reactor experiments were performed in order to identify the effects of temperature and the presence of oxygen on the activity for ammonia formation over the catalysts. The water–gas-shift reaction is enhanced with increasing cerium content, thus providing more hydrogen for ammonia formation. During transient operation at temperatures above 350 °C, a slight delay in ammonia formation is observed over the sample containing the highest cerium loading due to its (relatively) high dynamic oxygen storage capacity. At temperatures below 175 °C, N2O formation is preferred over NH3 formation. This work highlights the importance of balancing the effects that ceria influences when choosing the ceria loading for ammonia formation in passive-SCR applications.
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| 7. |
- Ahlberg, Erik, et al.
(författare)
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"Vi klimatforskare stödjer Greta och skolungdomarna"
- 2019
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Ingår i: Dagens nyheter (DN debatt). - 1101-2447.
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- DN DEBATT 15/3. Sedan industrialiseringens början har vi använt omkring fyra femtedelar av den mängd fossilt kol som får förbrännas för att vi ska klara Parisavtalet. Vi har bara en femtedel kvar och det är bråttom att kraftigt reducera utsläppen. Det har Greta Thunberg och de strejkande ungdomarna förstått. Därför stödjer vi deras krav, skriver 270 klimatforskare.
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| 8. |
- Alfvén, Tobias, et al.
(författare)
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Low-level cadmium exposure and osteoporosis.
- 2000
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Ingår i: Journal of Bone and Mineral Research. - 0884-0431 .- 1523-4681. ; 15, s. 1579-1586
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Tidskriftsartikel (refereegranskat)abstract
- Osteoporosis is a major cause of morbidity worldwide. A number of risk factors, such as age and gender, are well established. High cadmium exposure causes renal damage and in severe cases also causes osteoporosis and osteomalacia, We have examined whether long-term Pow-level cadmium exposure increases the risk of osteoporosis. Bone mineral density (BMD) in the forearm was measured in 520 men and 544 women, aged 16-81 years, environmentally or occupationally exposed to cadmium, using dual-energy X-ray absorptiometry (DXA) technique. Cadmium in urine was used as the dose estimate and protein HC was used: as a marker of renal tubular damage. There was a clear dose-response relation between cadmium dose and the prevalence of tubular proteinuria. Inverse relations were found between cadmium dose, tubular proteinuria, and BMD, particularly apparent in persons over 60 years of age, There was a dose-response relation between cadmium dose and osteoporosis. The odds ratios (ORs) for men were 2.2 (95% CI, 1.0-4.8) in the dose group 0.5-3 nmol Cd/mmol creatinine and 5.3 (2.0-14) in the highest dose category (greater than or equal to 3 nmol/mmol creatinine) compared with the lowest dose group (<0.5 nmol Cd/mmol creatinine). For women, the OR was 1.8 (0.65-5.3) in the dose group 0.53 nmol Cd/mmol creatinine. We conclude that exposure to low levels of cadmium is associated with an increased risk of osteoporosis.
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| 9. |
- Alvarsson, Jonathan, et al.
(författare)
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Ligand-Based Target Prediction with Signature Fingerprints
- 2014
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Ingår i: Journal of Chemical Information and Modeling. - : American Chemical Society (ACS). - 1549-9596 .- 1549-960X. ; 54:10, s. 2647-2653
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Tidskriftsartikel (refereegranskat)abstract
- When evaluating a potential drug candidate it is desirable to predict target interactions in silico prior to synthesis in order to assess, e.g., secondary pharmacology. This can be done by looking at known target binding profiles of similar compounds using chemical similarity searching. The purpose of this study was to construct and evaluate the performance of chemical fingerprints based on the molecular signature descriptor for performing target binding predictions. For the comparison we used the area under the receiver operating characteristics curve (AUC) complemented with net reclassification improvement (NRI). We created two open source signature fingerprints, a bit and a count version, and evaluated their performance compared to a set of established fingerprints with regards to predictions of binding targets using Tanimoto-based similarity searching on publicly available data sets extracted from ChEMBL. The results showed that the count version of the signature fingerprint performed on par with well-established fingerprints such as ECFP. The count version outperformed the bit version slightly; however, the count version is more complex and takes more computing time and memory to run so its usage should probably be evaluated on a case-by-case basis. The NRI based tests complemented the AUC based ones and showed signs of higher power.
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| 10. |
- Andersson, Tobias, 1976, et al.
(författare)
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Country of birth and mortality risk in hypertension with and without diabetes: the Swedish primary care cardiovascular database.
- 2021
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Ingår i: Journal of hypertension. - 1473-5598. ; 39:6, s. 1155-1162
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Tidskriftsartikel (refereegranskat)abstract
- Hypertension and diabetes are common and are both associated with high cardiovascular morbidity and mortality. We aimed to investigate associations between mortality risk and country of birth among hypertensive individuals in primary care with and without concomitant diabetes, which has not been studied previously. In addition, we aimed to study the corresponding risks of myocardial infarction and ischemic stroke.This observational cohort study of 62557 individuals with hypertension diagnosed 2001-2008 in the Swedish Primary Care Cardiovascular Database assessed mortality by the Swedish Cause of Death Register, and myocardial infarction and ischemic stroke by the National Patient Register. Cox regression models were used to estimate study outcome hazard ratios by country of birth and time updated diabetes status, with adjustments for multiple confounders.During follow-up time without diabetes using Swedish-born as reference, adjusted mortality hazard ratios per country of birth category were Finland: 1.26 (95% confidence interval 1.15-1.38), high-income European countries: 0.84 (0.74-0.95), low-income European countries: 0.84 (0.71-1.00) and non-European countries: 0.65 (0.56-0.76). The corresponding adjusted mortality hazard ratios during follow-up time with diabetes were high-income European countries: 0.78 (0.63-0.98), low-income European countries: 0.74 (0.57-0.96) and non-European countries: 0.56 (0.44-0.71). During follow-up without diabetes, the corresponding adjusted hazard ratio of myocardial infarction was increased for Finland: 1.16 (1.01-1.34), whereas the results for ischemic stroke were inconclusive.In Sweden, hypertensive immigrants (with the exception for Finnish-born) with and without diabetes have a mortality advantage, as compared to Swedish-born.
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