| 1. |
- Zhou Hagström, Nanna, 1993-, et al.
(författare)
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Megahertz-rate Ultrafast X-ray Scattering and Holographic Imaging at the European XFEL
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The advent of X-ray free-electron lasers (XFELs) has revolutionized fundamental science, from atomic to condensed matter physics, from chemistry to biology, giving researchers access to X-rays with unprecedented brightness, coherence, and pulse duration. All XFEL facilities built until recently provided X-ray pulses at a relatively low repetition rate, with limited data statistics. Here, we present the results from the first megahertz repetition rate X-ray scattering experiments at the Spectroscopy and Coherent Scattering (SCS) instrument of the European XFEL. We illustrate the experimental capabilities that the SCS instrument offers, resulting from the operation at MHz repetition rates and the availability of the novel DSSC 2D imaging detector. Time-resolved magnetic X-ray scattering and holographic imaging experiments in solid state samples were chosen as representative examples, providing an ideal test-bed for operation at megahertz rates. Nevertheless, our results are relevant and applicable to any other non-destructive XFEL experiments in the soft X-ray range.
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| 2. |
- Boehl, Gregor, et al.
(författare)
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Capital Taxation and Investment : Matching 100 Years of Wealth Inequality Dynamics
- 2017
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Using a parsimonious, analytically tractable dynamic model, we are able to explain up to 100 years of the available data on the dynamics of top-wealth shares for several countries. We build a micro-founded model of heterogeneous agents in which - in addition to stochastic returns on investment - individuals disagree marginally on their expectations of future returns and thus hold different asset positions. We show that, given a positive tax on capital gains, the distribution converges to a double Pareto distribution for which the degree of wealth inequality decreases with the tax rate. Closed-form solutions confirm that without government intervention there is infinite inequality. Moreover, transition dynamics are shown to increase with the tax rate. We discuss the model's ability to match the measured wealth inequality for the US, the UK, Sweden, and France, both in levels and transitions. The heterogeneous development in the different countries and across time can be traced back to different tax regimes.
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| 3. |
- Fischer, Thomas
(författare)
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Determinants of Wealth Inequality and Mobility in General Equilibrium
- 2019
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- What determines inequality and mobility of wealth? This paper quantifies in closed form both the bottom and the top (Pareto) tail of the distribution for a rich continuous-time model. The distribution is especially shaped by bequest motives, demographics, and the asset portfolio composition under idiosyncratic wealth risk. Factors that increase inequality also reduce mobility. The model - enriched by a realistic income process and non-trivial portfolio constraints - is solved in general equilibrium and calibrated to match US evidence. A bequest tax is shown to reduce inequality and increase mobility. Several partial-equilibrium intuitions do not carry over into general equilibrium.
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| 4. |
- Fischer, Thomas
(författare)
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Thomas Piketty and the Rate of Time Preference
- 2017
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Using a standard model where the individual consumption path is computed solving an optimal control problem, we investigate central claims of Piketty (2014) Rather than r>g (confirmed in the data) r-s>g - with s being the rate of time preference - matters. If this condition holds and the elasticity of substitution in the production function is larger than one, the capital share converges to one in the long run. Nevertheless, this does not have major impact on the distribution of wealth. The latter, however, converges to maximum inequality for heterogeneous time preferences or rates of interest (either persistent or stochastic).
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| 5. |
- Fischer, Thomas, et al.
(författare)
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Unequal Returns: Using the Atkinson Index to Measure Financial Risk
- 2018
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- We apply the Atkinson (1970) inequality index to time series of asset returns to offer a novel measure of financial risk consistent with expected-utility theory. This measure is converted to a certainty-equivalent return serving as a performance measure. We extend the Atkinson index to HARA utility and derive closed-form solutions to our measures for a number of preference-return combinations. Further, we establish relationships between risk aversion and the weights assigned to the cumulants of the return distribution for our performance measure. Using data from hedge funds and asset-pricing anomalies, we find that our performance measure contains additional, economically meaningful information.
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