2,233 research outputs found
Representation of women in the parliament of the Weimar republic: Evidence from roll call votes
This is the post-print version of the article which has been accepted for publication and will appear in a revised form, subsequent to peer review and/or editorial input in Politics and Gender. Copyright @ Cambridge University Press.In modern democracies, the representation of voter interests and preferences is primarily the job of political parties and their elected officials. These patterns can however change when issues are at stake that concern the interests of social groups represented by all relevant parties of a political system. In this article we focus on the behavior of female MPs in the parliament of Weimar Germany and, thus, in a parliament where legislative party discipline was very high. On the basis of a dataset containing information on the legislative voting behavior of MPs, we show that gender, even when controlling for a battery of further theoretically derived explanatory factors, had a decisive impact on the MPs’ voting behavior on a law proposal to curb the spread of sexually transmitted diseases.Zukunftskolleg (University of Konstanz) and the German Research Foundatio
Spin dynamics and magnetic-field-induced polarization of excitons in ultrathin GaAs/AlAs quantum wells with indirect band gap and type-II band alignment
The exciton spin dynamics are investigated both experimentally and
theoretically in two-monolayer-thick GaAs/AlAs quantum wells with an indirect
band gap and a type-II band alignment. The magnetic-field-induced circular
polarization of photoluminescence, , is studied as function of the
magnetic field strength and direction as well as sample temperature. The
observed nonmonotonic behaviour of these functions is provided by the interplay
of bright and dark exciton states contributing to the emission. To interpret
the experiment, we have developed a kinetic master equation model which
accounts for the dynamics of the spin states in this exciton quartet, radiative
and nonradiative recombination processes, and redistribution of excitons
between these states as result of spin relaxation. The model offers
quantitative agreement with experiment and allows us to evaluate, for the
studied structure, the heavy-hole factor, , and the spin
relaxation times of electron, s, and hole, s, bound in the exciton.Comment: 17 pages, 16 figure
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Femtosecond Pump-Probe Diagnostics Of Preformed Plasma Channels
We report on recent ultrafast pump-probe experiments 28 in He plasma waveguides using 800 nm, 80 fs pump pulses of 0.2 x 1018 W/cm2 peak guided intensity, and single orthogonally-polarized 800 nm probe pulses with similar to0.1% of pump intensity. The main results are: (1) We observe frequency-domain interference between the probe and a weak, depolarized component of the pump that differs substantially in mode shape from the injected pump pulse; (2) we observe spectral blue-shifts in the transmitted probe that are not evident in the transmitted pump. The evidence indicates that pump depolarization and probe blue-shifts both originate near the channel entrance.Physic
Restoring betatron phase coherence in a beam-loaded laser-wakefield accelerator
Matched beam loading in laser wakefield acceleration (LWFA), characterizing
the state of flattening of the acceleration electric field along the bunch,
leads to the minimization of energy spread at high bunch charges. Here, we
demonstrate by independently controlling injected charge and acceleration
gradients, using the self-truncated ionization injection scheme, that minimal
energy spread coincides with a reduction of the normalized beam divergence.
With the simultaneous confirmation of a constant beam radius at the plasma
exit, deduced from betatron radiation spectroscopy, we attribute this effect to
the reduction of chromatic betatron decoherence. Thus, beam loaded LWFA enables
highest longitudinal and transverse phase space densities
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Instruments of value: using the analytic tools of public value theory in teaching and practice
The tools of public value management - such as the strategic triangle and the public value account,– are increasingly used by scholars and practitioners alike. At the same time, some confusion remains regarding their functionality in action. Based on our experiences with these tools in classrooms and boardrooms, we analyze how these instruments help to explore and structure different dimensions of public management challenges. We propose a set of ‘principles of application’, detailing under what conditions public value tools are most likely to be helpful, and suggest a course of action for strengthening, connecting and extending the current tool box
Demonstration of a beam loaded nanocoulomb-class laser wakefield accelerator.
Laser-plasma wakefield accelerators have seen tremendous progress, now capable of producing quasi-monoenergetic electron beams in the GeV energy range with few-femtoseconds bunch duration. Scaling these accelerators to the nanocoulomb range would yield hundreds of kiloamperes peak current and stimulate the next generation of radiation sources covering high-field THz, high-brightness X-ray and γ-ray sources, compact free-electron lasers and laboratory-size beam-driven plasma accelerators. However, accelerators generating such currents operate in the beam loading regime where the accelerating field is strongly modified by the self-fields of the injected bunch, potentially deteriorating key beam parameters. Here we demonstrate that, if appropriately controlled, the beam loading effect can be employed to improve the accelerator's performance. Self-truncated ionization injection enables loading of unprecedented charges of ∼0.5 nC within a mono-energetic peak. As the energy balance is reached, we show that the accelerator operates at the theoretically predicted optimal loading condition and the final energy spread is minimized.Higher beam quality and stability are desired in laser-plasma accelerators for their applications in compact light sources. Here the authors demonstrate in laser plasma wakefield electron acceleration that the beam loading effect can be employed to improve beam quality by controlling the beam charge
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