Hydrogen Balmer line formation in solar flares affected by return currents

Aims. We investigate the effect of the electric return currents in solar flares on the profiles of hydrogen Balmer lines. We consider the monoenergetic approximation for the primary beam and runaway model of the neutralizing return current. Methods. Propagation of the 10 keV electron beam from a coronal reconnection site is considered for the semiempirical chromosphere model F1. We estimate the local number density of return current using two approximations for beam energy fluxes between $4\times 10^{11}$ and $1\times 10^{12} {\rm erg cm^{-2} s^{-1}}$. Inelastic collisions of beam and return-current electrons with hydrogen are included according to their energy distributions, and the hydrogen Balmer line intensities are computed using an NLTE radiative transfer approach. Results. In comparison to traditional NLTE models of solar flares that neglect the return-current effects, we found a significant increase emission in the Balmer line cores due to nonthermal excitation by return current. Contrary to the model without return current, the line shapes are sensitive to a beam flux. It is the result of variation in the return-current energy that is close to the hydrogen excitation thresholds and the density of return-current electrons.Comment: 4 pages, 3 figures, 1 table, accepted for publication in Astronomy and Astrophysics Letter

Response of optical hydrogen lines to beam heating: I. Electron beams

We investigate the role of non-thermal electrons in the formation regions of Halpha, Hbeta, and Hgamma lines in order to unfold their influence on the formation of these lines. We concentrate on pulse-beam heating varying on a subsecond timescale. Furthermore, we theoretically explore possibility that a new diagnostic tool exists indicating the presence of non-thermal electrons in the flaring chromosphere based on observations of optical hydrogen lines. To model the evolution of the flaring atmosphere and the time-dependent hydrogen excitation and ionisation, we used a 1-D radiative hydrodynamic code combined with a test-particle code that simulates the propagation, scattering, and thermalisation of a power-law electron beam in order to obtain the flare heating and the non-thermal collisional rates due to the interaction of the beam with the hydrogen atoms. All calculated models have shown a time-correlated response of the modelled Balmer line intensities on a subsecond timescale, with a subsecond timelag behind the beam flux. Depending on the beam parameters, both line centres and wings can show pronounced intensity variations. The non-thermal collisional rates generally result in an increased emission from a secondary region formed in the chromosphere.Comment: 13 pages, 11 figures, accepted to Astronomy and Astrophysic

Czech female managers and their wages

This paper examines gender gaps in employment and wages among top- and lower-level managerial employees in the Czech Republic at the time of its accession to the EU. Using both least-squares and matching-based decomposition techniques, we find the wage gap among comparable men and women to be sizeable, but quite similar across firm hierarchy levels. The key reason why the average relative wage position of female top managers is worse compared to lower-ranking female employees is that women tend not to be at the helm of the highest-paying companies. Overall, the representation of women at the top of Czech firms as well as the structure of the gender wage gap there appears quite similar to those in the US.Gender wage gap Managers Czech Republic

Admission to selective schools, alphabetically

One's position in an alphabetically sorted list may be important in determining access to over-subscribed public services. Motivated by anecdotal evidence, we investigate the importance of the position in the alphabet of Czech students for their admission chances into over-subscribed schools. Empirical evidence based on the population of students graduating from secondary schools and applying to universities is consistent with the use of alphabet in admission procedures at both secondary and tertiary level, implying potential inefficiency in the matching of students with universities.Admissions Alphabetical order Serial position Order effects

Job Reallocation in Two Cases of Massive Adjustment in Eastern Europe

Summary This paper uses worker-level data to characterize economy-wide job creation and job destruction during periods of massive structural adjustment. We contrast the gradualist Czech and the rapid Estonian approach to the destruction of the communist economy and assess their experience in light of selected theories of reallocation with frictions. We find that gradual job destruction combined with job creation support allows extensive reallocation to concur with low unemployment. Drastic job destruction, on the other hand, need not slow down job creation as long as unemployment benefits are kept very low.job creation job destruction transition Czech Republic Estonia Eastern Europe

Sacrificing Oneself or Another: The Difference Between Prescriptive and Normative Judgments in Moral Evaluation

When asked whether to sacrifice oneself or another person to save others, one might think that people would consider sacrificing themselves rather than someone else as the right and appropriate course of action—thus showing an other-serving bias. So far however, most studies found instances of a self-serving bias—people say they would rather sacrifice others. In three experiments using trolley-like dilemmas, we tested whether an other-serving bias might appear as a function of judgment type. That is, participants were asked to make a prescriptive judgment (whether the described action should or should not be done) or a normative judgment (whether the action is right or wrong). We found that participants exhibited an other-serving bias only when asked whether self- or other-sacrifice is wrong. That is, when the judgment was normative and in a negative frame (in contrast to the positive frame asking whether the sacrifice is right). Otherwise, participants tended to exhibit a self-serving bias; that is, they approved sacrificing others more. The results underscore the importance of question wording and suggest that some effects on moral judgment might depend on the type of judgment