| 1. |
- Abdulle, Assyr, et al.
(author)
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High weak order methods for stochastic differential equations based on modified equations
- 2012
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In: SIAM Journal on Scientific Computing. - : Society for Industrial & Applied Mathematics (SIAM). - 1064-8275 .- 1095-7197. ; 34:3, s. A1800-A1823
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Journal article (peer-reviewed)abstract
- Inspired by recent advances in the theory of modified differential equations, we propose a new methodology for constructing numerical integrators with high weak order for the time integration of stochastic differential equations. This approach is illustrated with the constructions of new methods of weak order two, in particular, semi-implicit integrators well suited for stiff (mean-square stable) stochastic problems, and implicit integrators that exactly conserve all quadratic firstintegrals of a stochastic dynamical system. Numerical examples confirm the theoretical results and show the versatility of our methodology.
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| 2. |
- Adebahr, J, et al.
(author)
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Ion and solvent dynamics in gel electrolytes based on ethylene oxide grafted acrylate polymers
- 2002
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In: The Journal of Physical Chemistry Part B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106 .- 1089-5647. ; 106:47, s. 12119-12123
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Journal article (peer-reviewed)abstract
- Multinuclear pulsed field gradient NMR measurements and theological viscosity measurements were performed on three series of polymer gel electrolytes. The gels were based on a lithium salt electrolyte swollen into a copolymer matrix comprising an acrylate backbone and ethylene oxide side chains. In each series the side chains differed in length and number, but the acrylate-to-ethylene oxide ratio was kept constant. It was found that the self-diffusion coefficient of the cations was much lower than that of the anions, and that it decreased rapidly when the side chains got longer. In contrast, the self-diffusion coefficient of the anions was found to be independent of chain length. In the gel electrolytes, the diffusion coefficients of the solvent molecules are relatively constant despite an increased viscosity with increasing length of the side chains. However, in saltfree gels made for comparison, the diffusion coefficients of the solvent molecules decreased with, increasing length of the side chains, which is consistent with an increased viscosity.
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| 3. |
- Ahlin, Rebecca, 1989, et al.
(author)
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Effects on Serum Hormone Concentrations after a Dietary Phytoestrogen Intervention in Patients with Prostate Cancer: A Randomized Controlled Trial
- 2023
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In: Nutrients. - : MDPI. - 2072-6643 .- 2072-6643. ; 15:7
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Journal article (peer-reviewed)abstract
- Phytoestrogens have been suggested to have an anti-proliferative role in prostate cancer, potentially by acting through estrogen receptor beta (ERβ) and modulating several hormones. We primarily aimed to investigate the effect of a phytoestrogen intervention on hormone concentrations in blood depending on the ERβ genotype. Patients with low and intermediate-risk prostate cancer, scheduled for radical prostatectomy, were randomized to an intervention group provided with soybeans and flaxseeds (∼200 mg phytoestrogens/d) added to their diet until their surgery, or a control group that was not provided with any food items. Both groups received official dietary recommendations. Blood samples were collected at baseline and endpoint and blood concentrations of different hormones and phytoestrogens were analyzed. The phytoestrogen-rich diet did not affect serum concentrations of testosterone, insulin-like growth factor 1, or sex hormone-binding globulin (SHBG). However, we found a trend of decreased risk of increased serum concentration of estradiol in the intervention group compared to the control group but only in a specific genotype of ERβ (p = 0.058). In conclusion, a high daily intake of phytoestrogen-rich foods has no major effect on hormone concentrations but may lower the concentration of estradiol in patients with prostate cancer with a specific genetic upset of ERβ.
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| 4. |
- Akkerman, V., et al.
(author)
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Analysis of flame acceleration induced by wall friction in open tubes
- 2010
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In: Physics of Fluids. - : AIP Publishing. - 1070-6631 .- 1089-7666. ; 22:5, s. 1-14
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Journal article (peer-reviewed)abstract
- Spontaneous flame acceleration leading to explosion triggering in open tubes/channels due to wall friction was analytically and computationally studied. It was first demonstrated that the acceleration is affected when the thermal expansion across the flame exceeds a critical value depending on the combustion configuration. For the axisymmetric flame propagation in cylindrical tubes with both ends open, a theory of the initial (exponential) stage of flame acceleration in the quasi-isobaric limit was developed and substantiated by extensive numerical simulation of the hydrodynamics and combustion with an Arrhenius reaction. The dynamics of the flame shape, velocity, and acceleration rate, as well as the velocity profile ahead and behind the flame, have been determined. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3425646]
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| 5. |
- Akkerman, V., et al.
(author)
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Flow-flame interaction in a closed chamber
- 2008
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In: Physics of Fluids. - : AIP Publishing. - 1070-6631 .- 1089-7666. ; 20:5, s. 21-
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Journal article (peer-reviewed)abstract
- Numerous studies of flame interaction with a single vortex and recent simulations of burning in vortex arrays in open tubes demonstrated the same tendency for the turbulent burning rate proportional to U-rms lambda(2/3), where U-rms is the root-mean-square velocity and lambda is the vortex size. Here, it is demonstrated that this tendency is not universal for turbulent burning. Flame interaction with vortex arrays is investigated for the geometry of a closed burning chamber by using direct numerical simulations of the complete set of gas-dynamic combustion equations. Various initial conditions in the chamber are considered, including gas at rest and several systems of vortices of different intensities and sizes. It is found that the burning rate in a closed chamber (inverse burning time) depends strongly on the vortex intensity; at sufficiently high intensities it increases with U-rms approximately linearly in agreement with the above tendency. On the contrary, dependence of the burning rate on the vortex size is nonmonotonic and qualitatively different from the law lambda(2/3). It is shown that there is an optimal vortex size in a closed chamber, which provides the fastest total burning rate. In the present work, the optimal size is six times smaller than the chamber height.
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| 6. |
- Al-Tamprouri, Chaifa, et al.
(author)
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Cat and dog ownership during/after the first year of life and risk for sensitization and reported allergy symptoms at age 13
- 2019
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In: Immunity Inflammation and Disease. - : Wiley. - 2050-4527. ; 7:4, s. 250-257
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Journal article (peer-reviewed)abstract
- Background Avoidance of pets as a strategy for preventing atopic diseases has been questioned. This study aimed to identify the risk of sensitization and allergic symptoms at age 13 in relation to dog- and cat-keeping during and after the first year of life. Methods The study included all children born at ostersund Hospital in Northern Sweden between February 1996 and January 1997 (n = 1231). At inclusion, parents were asked to answer questionnaires about lifestyle, including cat- and dog-keeping. Dog allergy, cat allergy, hay fever, and asthma were diagnosed based on parental reported allergic symptoms at 13 years of age (n = 834). The risks of sensitization or allergy in relation to dog- and cat-keeping during and after the first year of life were analyzed with logistic regression. To adjust for reverse causation, all subjects that had reported avoidance of pets due to allergic symptoms of the child or allergy in the family (n = 177) were excluded. Results Dog- or cat-keeping during the first year of life reduced the risk of sensitization to dog or cat allergens, respectively, and to birch and to at least one of the 10 allergens tested. Cat-keeping, both during and after the first year of life, reduced the risk of cat allergy and hay fever. Having a dog at home during the first year of life reduced the risk of dog and cat allergy, whereas dog-keeping after the first year of life did not affect allergic symptoms. Conclusions Cat ownership, either during or after the first year of life, may be a strategy for preventing the development of cat allergy and hay fever later in life. Dog ownership reduced the risk of sensitization to dog and birch allergen, and also the risk of cat and dog allergy, but had no effect on hay fever.
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| 7. |
- Alrifaiy, Ahmed, et al.
(author)
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A lab-on-a-chip for hypoxic patch clamp measurements combined with optical tweezers and spectroscopy : first investigations of single biological cells
- 2015
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In: Biomedical engineering online. - : Springer Science and Business Media LLC. - 1475-925X. ; 14
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Journal article (peer-reviewed)abstract
- The response and the reaction of the brain system to hypoxia is a vital research subject that requires special instrumentation. With this research subject in focus, a new multifunctional lab-on-a-chip (LOC) system with control over the oxygen content for studies on biological cells was developed. The chip was designed to incorporate the patch clamp technique, optical tweezers and absorption spectroscopy. The performance of the LOC was tested by a series of experiments. The oxygen content within the channels of the LOC was monitored by an oxygen sensor and verified by simultaneously studying the oxygenation state of chicken red blood cells (RBCs) with absorption spectra. The chicken RBCs were manipulated optically and steered in three dimensions towards a patch-clamp micropipette in a closed microfluidic channel. The oxygen level within the channels could be changed from a normoxic value of 18% O 2 to an anoxic value of 0.0-0.5% O 2. A time series of 3 experiments were performed, showing that the spectral transfer from the oxygenated to the deoxygenated state occurred after about 227 ± 1 s and a fully developed deoxygenated spectrum was observed after 298 ± 1 s, a mean value of 3 experiments. The tightness of the chamber to oxygen diffusion was verified by stopping the flow into the channel system while continuously recording absorption spectra showing an unchanged deoxygenated state during 5400 ± 2 s. A transfer of the oxygenated absorption spectra was achieved after 426 ± 1 s when exposing the cell to normoxic buffer. This showed the long time viability of the investigated cells. Successful patching and sealing were established on a trapped RBC and the whole-cell access (Ra) and membrane (Rm) resistances were measured to be 5.033 ± 0.412 M Ω and 889.7 ± 1.74 M Ω respectively.
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| 8. |
- Andersson, Erik, et al.
(author)
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Ambio fit for the 2020s
- 2022
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In: Ambio. - : Springer Nature. - 0044-7447 .- 1654-7209. ; 51:5, s. 1091-1093
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Journal article (peer-reviewed)
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| 9. |
- Andersson, Magnus, et al.
(author)
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A proposed time-resolved X-ray scattering approach to track local and global conformational changes in membrane transport proteins
- 2008
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In: Structure. - : Elsevier BV. - 0969-2126 .- 1878-4186. ; 16:1, s. 21-28
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Journal article (peer-reviewed)abstract
- Time-resolved X-ray scattering has emerged as a powerful technique for studying the rapid structural dynamics of small molecules in solution. Membrane-protein-catalyzed transport processes frequently couple large-scale conformational changes of the transporter with local structural changes perturbing the uptake and release of the transported substrate. Using light-driven halide ion transport catalyzed by halorhodopsin as a model system, we combine molecular dynamics simulations with X-ray scattering calculations to demonstrate how small-molecule time-resolved X-ray scattering can be extended to the study of membrane transport processes. In particular, by introducing strongly scattering atoms to label specific positions within the protein and substrate, the technique of time-resolved wide-angle X-ray scattering can reveal both local and global conformational changes. This approach simultaneously enables the direct visualization of global rearrangements and substrate movement, crucial concepts that underpin the alternating access paradigm for membrane transport proteins.
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| 10. |
- Andersson, Mats, 1957, et al.
(author)
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Explicit representation of membership of polynomial ideals
- 2011
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In: Mathematische Annalen. - : Springer Science and Business Media LLC. - 0025-5831 .- 1432-1807. ; 349:2, s. 345-365
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Journal article (peer-reviewed)abstract
- We introduce a new division formula on projective space which provides explicit solutions to various polynomial division problems with sharp degree estimates. We consider simple examples as the classical Macaulay theorem as well as a quite recent result by Hickel, related to the effective Nullstellensatz. We also obtain a related result that generalizes Max Noether's classical AF + BG theorem.
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