| 1. |
- Al-Khalili, A, et al.
(författare)
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Dissociative recombination cross section and branching ratios of protonated dimethyl disulfide and N-methylacetamide
- 2004
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 121:12, s. 5700-5708
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Tidskriftsartikel (refereegranskat)abstract
- Dimethyl disulfide (DMDS) and N-methylacetamide are two first choice model systems that represent the disulfide bridge bonding and the peptide bonding in proteins. These molecules are therefore suitable for investigation of the mechanisms involved when proteins fragment under electron capture dissociation (ECD). The dissociative recombination cross sections for both protonated DMDS and protonated N-methylacetamide were determined at electron energies ranging from 0.001 to 0.3 eV. Also, the branching ratios at 0 eV center-of-mass collision energy were determined. The present results give support for the indirect mechanism of ECD, where free hydrogen atoms produced in the initial fragmentation step induce further decomposition. We suggest that both indirect and direct dissociations play a role in ECD.
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| 2. |
- Aspholm-Hurtig, Marina, et al.
(författare)
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Functional adaptation of BabA, the H. pylori ABO blood group antigen binding adhesin.
- 2004
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Ingår i: Science (New York, N.Y.). - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 305:5683, s. 519-22
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Tidskriftsartikel (refereegranskat)abstract
- Adherence by Helicobacter pylori increases the risk of gastric disease. Here, we report that more than 95% of strains that bind fucosylated blood group antigen bind A, B, and O antigens (generalists), whereas 60% of adherent South American Amerindian strains bind blood group O antigens best (specialists). This specialization coincides with the unique predominance of blood group O in these Amerindians. Strains differed about 1500-fold in binding affinities, and diversifying selection was evident in babA sequences. We propose that cycles of selection for increased and decreased bacterial adherence contribute to babA diversity and that these cycles have led to gradual replacement of generalist binding by specialist binding in blood group O-dominant human populations.
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| 3. |
- Asplund, Marcus, et al.
(författare)
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Price adjustments by a gasoline retail chain
- 2000
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Ingår i: Scandinavian Journal of Economics. - : Wiley. - 0347-0520 .- 1467-9442. ; 102:1, s. 101-121
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Tidskriftsartikel (refereegranskat)abstract
- We use daily data to examine price responses in the Swedish gasoline market to changes in the Rotterdam spot price, exchange rates and taxes. The distribution of price adjustments by a leading retail chain, for the period January 1980 to December 1996, is symmetric with no small adjustments. An error correction model shows that, in the short run, prices gradually move towards the long-run equilibrium in response to cost shocks. There is some evidence that, also in the short run, prices are stickier downwards than upwards. Prices respond more rapidly to exchange rate movements than to the spot market price. Our analysis emphasizes that to fully understand price adjustments it is necessary to examine data sets where the sample frequency at least matches that of price adjustments.
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| 4. |
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| 5. |
- Broomé, Michael, et al.
(författare)
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Pressure-independent cardiac effects of angiotensin II in pigs.
- 2004
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Ingår i: Acta Anaesthesiol Scand. - 0001-6772 .- 1365-201X. ; 182:2, s. 111-9
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Angiotensin II (Ang II) is a potent vasoconstrictor with an important role in the development of cardiovascular disease. Earlier results have shown a positive acute inotropic effect of Ang II in anaesthetized pigs together with significant vasoconstriction. This investigation was designed to study cardiac effects of Ang II, when blood pressure was maintained constant by experimental means. METHODS: Ang II (200 microg h(-1)) was infused in anaesthetized pigs (n = 10) at two different arterial blood pressures, the first determined by the effects of Ang II alone, and the second maintained at baseline blood pressure with nitroprusside. Cardiac systolic and diastolic function was evaluated by analysis of left ventricular pressure-volume relationships. RESULTS: Heart rate, end-systolic elastance (Ees) and pre-load adjusted maximal power (PWRmax EDV(-2)) increased at both blood pressure levels, although less when blood pressure was kept constant with nitroprusside. The time constant for isovolumetric relaxation (tau(1/2)) was prolonged with Ang II alone and shortened with Ang II infused together with nitroprusside. CONCLUSION: Ang II infusion in the pig has inotropic and chronotropic properties independent of arterial blood pressure levels, although the effects seem to be blunted by pharmacological actions of the nitric oxide donor nitroprusside.
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| 6. |
- Bränden, Petter
(författare)
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On operators on polynomials preserving real-rootedness and the Neggers-Stanley conjecture
- 2004
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Ingår i: Journal of Algebraic Combinatorics. - 0925-9899 .- 1572-9192. ; 20:2, s. 119-130
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Tidskriftsartikel (refereegranskat)abstract
- We refine a technique used in a paper by Schur on real-rooted polynomials. This amounts to an extension of a theorem of Wagner on Hadamard products of Polya frequency sequences. We also apply our results to polynomials for which the Neggers-Stanley Conjecture is known to hold. More precisely, we settle interlacing properties for E-polynomials of series-parallel posets and column-strict labelled Ferrers posets.
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| 7. |
- Dincbas-Renqvist, Vildan, et al.
(författare)
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Thermodynamics of folding, stabilization, and binding in an engineered protein--protein complex.
- 2004
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Ingår i: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 0002-7863 .- 1520-5126. ; 126:36, s. 11220-30
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Tidskriftsartikel (refereegranskat)abstract
- We analyzed the thermodynamics of a complex protein-protein binding interaction using the (engineered) Z(SPA)(-)(1) affibody and it's Z domain binding partner as a model. Free Z(SPA)(-)(1) exists in an equilibrium between a molten-globule-like (MG) state and a completely unfolded state, wheras a well-ordered structure is observed in the Z:Z(SPA)(-)(1) complex. The thermodynamics of the MG state unfolding equilibrium can be separated from the thermodynamics of binding and stabilization by combined analysis of isothermal titration calorimetry data and a separate van't Hoff analysis of thermal unfolding. We find that (i) the unfolding equilibrium of free Z(SPA)(-)(1) has only a small influence on effective binding affinity, that (ii) the Z:Z(SPA)(-)(1) interface is inconspicuous and structure-based energetics calculations suggest that it should be capable of supporting strong binding, but that (iii) the conformational stabilization of the MG state to a well-ordered structure in the Z:Z(SPA)(-)(1) complex is associated with a large change in conformational entropy that opposes binding.
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| 8. |
- Eklöf, Mats, 1953, et al.
(författare)
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Feedback of workplace data to individual workers, workgroups or supervisors as a way to stimulate working environment activity: a cluster randomized controlled study.
- 2004
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Ingår i: International archives of occupational and environmental health. - : Springer Science and Business Media LLC. - 0340-0131 .- 1432-1246. ; 77:7, s. 505-14
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To test whether feedback and discussion of ergonomic and psychosocial working-environment data during one short session with individual, groups or supervisors of white-collar computer workers had an effect on activity to modify workplace design, working technique and psychosocial aspects of work. METHODS: A total of 36 workgroups from nine organizations representing different trades was randomized (stratified for organization) to three feedback conditions or control with no feedback. Data were collected 1 month before and 6 months after feedback sessions. The effects studied were: (1) change in the proportion of workgroup members who reported any modification regarding workplace design or working technique; (2) change in the proportion of workgroup members who reported any modification regarding psychosocial aspects; (3) average number of modification types regarding workplace design or working technique per individual in a workgroup; (4) average number of modification types regarding psychosocial aspects per individual in a workgroup. RESULTS: All feedback conditions differed positively from controls regarding change in the proportion of workgroup members who reported any modification in workplace design or working technique. No such effect was found for psychosocial aspects. For change in average number of psychosocial modification types per individual in a workgroup an effect was observed for feedback to supervisors. No intervention effect was observed for the average number of modifications in workplace design or working technique per individual in a workgroup. CONCLUSION: Feedback and discussion of ergonomic and psychosocial working-environment data during one short session with individual, groups or supervisors of white-collar computer workers may have a positive effect on how many people in a workgroup modify (or have modifications done regarding) workplace design and working technique. Feedback to supervisors may have an effect on the average number of psychosocial modification types per individual in a workgroup. Feedback to group supervisors appeared to be the most cost-effective variant.
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| 9. |
- Ellmann, A, et al.
(författare)
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Radiative lifetime of a bound excited state of Te-
- 2004
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 92:25, s. 253002-
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Tidskriftsartikel (refereegranskat)abstract
- We report on the first experimental study of the lifetime of a bound excited state of a negative ion. A new experimental technique was developed and used to measure the radiative lifetime of the 5p(5) P-2(1/2) level of Te-. The experiment was performed in a magnetic storage ring, where a laser beam was applied along one of the straight sections. In the experiment the population of the excited J=1/2 level was probed each time the Te- ions passed through the laser field. A decay curve was built up by sampling the population of the excited level of the Te- ions as a function of time after injection into the ring. A multiconfiguration Dirac-Hartree-Fock calculation was performed in conjunction with the experiment. The calculation yielded a radiative lifetime of 0.45 s, in excellent agreement with the measured value of 0.42(5) s.
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| 10. |
- Eriksson, Kenneth, 1952, et al.
(författare)
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Explicit time-stepping for stiff ODES
- 2003
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Ingår i: SIAM Journal on Scientific Computing. - 1064-8275 .- 1095-7197. ; 25:4, s. 1142-1157
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Tidskriftsartikel (refereegranskat)abstract
- We present a new strategy for solving stiff ODEs with explicit methods. By adaptively taking a small number of stabilizing small explicit time steps when necessary, a stiff ODE system can be stabilized enough to allow for time steps much larger than what is indicated by classical stability analysis. For many stiff problems the cost of the stabilizing small time steps is small, so the improvement is large. We illustrate the technique on a number of well-known stiff test problems.
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