| 1. |
- Karlström, Olov, et al.
(author)
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Increasing thermoelectric performance using coherent transport
- 2011
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In: Physical Review B (Condensed Matter and Materials Physics). - 1098-0121. ; 84:11
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Journal article (peer-reviewed)abstract
- We show that coherent electron transport through zero-dimensional systems can be used to tailor the shape of the system's transmission function. This quantum-engineering approach can be used to enhance the performance of quantum dots or molecules in thermal-to-electric power conversion. Specifically, we show that electron interference in a two-level system can substantially improve the maximum thermoelectric power and the efficiency at maximum power by suppressing parasitic charge flow near the Fermi energy and by reducing electronic heat conduction. We discuss possible realizations of this approach in molecular junctions or quantum dots.
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| 2. |
- Gospic, Katarina, et al.
(author)
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Altruism costs-the cheap signal from amygdala
- 2014
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In: Social Cognitive & Affective Neuroscience. - : Oxford University Press (OUP). - 1749-5016 .- 1749-5024. ; 9:9, s. 1325-1332
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Journal article (peer-reviewed)abstract
- When people state their willingness to pay for something, the amount usually differs from the behavior in a real purchase situation. The discrepancy between a hypothetical answer and the real act is called hypothetical bias. We investigated neural processes of hypothetical bias regarding monetary donations to public goods using fMRI with the hypothesis that amygdala codes for real costs. Real decisions activated amygdala more than hypothetical decisions. This was observed for both accepted and rejected proposals. The more the subjects accepted real donation proposals the greater was the activity in rostral anterior cingulate cortex-a region known to control amygdala but also neural processing of the cost-benefit difference. The presentation of a charitable donation goal evoked an insula activity that predicted the later decision to donate. In conclusion, we have identified the neural mechanisms underlying real donation behavior, compatible with theories on hypothetical bias. Our findings imply that the emotional system has an important role in real decision making as it signals what kind of immediate cost and reward an outcome is associated with.
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| 3. |
- Holt, Asbjörn, et al.
(author)
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A NEMO potential that includes the dipole-quadrupole and quadrupole-quadrupole polarizability
- 2010
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In: Journal of Computational Chemistry. - : Wiley. - 0192-8651 .- 1096-987X. ; 31:8, s. 1583-1591
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Journal article (peer-reviewed)abstract
- To increase the accuracy of molecular force fields a systematical and balanced improvement of the various terms included is needed. In this work, we have followed this strategy to improve the quality of the NEMO potential for the formaldehyde dimer by introducing local quadrupole moments and higher-order polarizabilities. It is found that inclusion of the quadrupole moment significantly improves the interaction potential. Furthermore, the inclusion of higher-order polarizabilities up to quadrupole-quadrupole polarizability is shown to give a better description of the intermolecular interaction. In addition, it is demonstrated that localized properties based on MP2 densities reproduces the BSSE corrected MP2 interaction energy at large intermolecular separations. This is not the case for HF-SCF based properties.
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| 4. |
- Holt, Asbjörn, et al.
(author)
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Calculation of the Molecular and Atomic Properties of Selected Anions in Water.
- 2011
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In: The Journal of Physical Chemistry Part B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106. ; 115:5, s. 1098-1104
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Journal article (peer-reviewed)abstract
- The polarizability and other properties have been studied for F(-), Cl(-), Br(-), and HCOO(-) in water using a combined quantum chemical statistical mechanics simulation model that explicitly takes into account the Pauli repulsion as well as the electrostatic coupling between the QM system and the classical surroundings. It is shown that the surrounding molecules significantly reduce both the polarizability and the size of the anions. For the formate ions, local properties have been computed.
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| 5. |
- Isacsson, Gunnar, et al.
(author)
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The value of commuting time in an empirical on-the-job search model : An application based on moments from two samples
- 2013
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In: Applied Economics. - : Informa UK Limited. - 0003-6846 .- 1466-4283. ; 45:19, s. 2827-2837
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Journal article (peer-reviewed)abstract
- This article estimates the Value of Commuting Time (VOCT) among Swedish males in an empirical on-the-job search model. It uses a large sample of employee-establishment linked data obtained from administrative registers. The sample lacks information on mode choice for the journey to work. We therefore estimate a mode choice model on another sample and use this model to link the administrative data to the relevant set of travel times, costs and distances. The VOCT is found to be 1.8 times the net hourly wage rate in the sample. The relatively high estimate results from a high VOCT among cohabiting men.
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| 6. |
- Karlström, Anders, et al.
(author)
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Is sick absence related to commuting travel time? : Swedish Evidence Based on the Generalized Propensity Score Estimator
- 2010
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Reports (other academic/artistic)abstract
- This paper focuses on the effects of commuting time on sickness insurance utilization by applying a generalized propensity score estimator to a large sample of Swedish employees. We analyse the effect of commuting time both on the probability of using sickness insurance at all and on the probability that an individual on sick leave is on so-called partial sick leave rather than being completely absent from work. Insurance utilization is in both cases defined as being ill for more than 14 days. The results indicate, in general, that individuals do not use sickness insurance because of their commuting time. However, commuting time seems to increase the risk of being on sick leave among females with relatively low annual wage earnings. The results indicate, furthermore, a relatively weak and negative relationship between the probability of being on partial sick leave and commuting time in the group of individuals who have utilized sickness insurance. The latter result applies to both men and women.
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| 7. |
- Karlström, Gunnar, et al.
(author)
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Dipolar Order in Molecular Fluids: I. Toward an Understanding
- 2011
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In: Journal of Statistical Physics. - : Springer Science and Business Media LLC. - 1572-9613 .- 0022-4715. ; 145:2, s. 410-417
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Journal article (peer-reviewed)abstract
- The origin behind the dipolar order in molecular fluids is investigated by using a simple dipolar fluid and Monte Carlo simulation technique. A penalty function is employed to separately manipulate the positional and orientational structure of the fluid. By considering the distance-dependent Kirkwood function G (k), which in turn is related to the dielectric permittivity of the fluid, it is observed that both positional and orientational ordering are involved to establish dipolar order.
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| 8. |
- Karlström, Gunnar, et al.
(author)
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Retardation effects breaking long-range orientational ordering in dipolar fluids.
- 2010
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In: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 132:5
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Journal article (peer-reviewed)abstract
- A strongly coupled dipolar fluid confined in a sphere has been examined by Monte Carlo simulations using a modified distance-dependent pair interaction to emulate retardation effects. The effective dipole-dipole interaction and a property closely related to Kirkwood's g-factor have been analyzed for potentials with different distances at which the retardation effects became effective. The retardation effects were found to break the otherwise long-range structural ordering occurring in strongly coupled dipolar fluids.
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| 9. |
- Karlström, Gunnar, et al.
(author)
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Two-center potential correlations and its use to determine effective ion-ion interactions and dielectric permittivities in dipolar solvents
- 2010
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In: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 132:8
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Journal article (peer-reviewed)abstract
- General expressions for two-center electrostatic potential correlations and its use to determine (i) the effective interaction between simple ions in a dipolar solvent and (ii) the dielectric permittivity of the solvent are proposed. Such two-center potential correlations were determined from Monte Carlo simulations of spherically confined dipolar particles embedded in a dielectric medium described by using an image charge approximation. The deduced dielectric permittivities increased with increasing dipolar moment, and at large dipole moments the effective interaction displayed an attractive first minimum. (C) 2010 American Institute of Physics.
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| 10. |
- Lindman, Björn, et al.
(author)
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On the mechanism of dissolution of cellulose
- 2010
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In: Journal of Molecular Liquids. - : Elsevier BV. - 0167-7322. ; 156:1, s. 76-81
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Journal article (peer-reviewed)abstract
- Cellulose is insoluble in water and many organic solvents, but can be dissolved in a number of solvents of intermediate properties, like N-methylmorpholine N-oxide (NMMO) and ionic liquids (ILs). It can also be dissolved in water at high and low pHs, in particular if a cosolute of intermediate polarity is added. The insolubility in water is often referred to strong intermolecular hydrogen bonding between cellulose molecules. However, an examination of the interactions involved reveals another picture, which suggests that cellulose is significantly amphiphilic and that hydrophobic interactions are important for explaining the solubility pattern of cellulose. (C) 2010 Elsevier B.V. All rights reserved.
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