The first close-up of the "flip-flop" phenomenon in a single star

We present temperature maps of the active late-type giant FK Com which exhibit the first imagining record of the ``flip-flop'' phenomenon in a single star. The phenomenon, in which the main part of the spot activity shifts 180 degrees in longitude, discovered a decade ago in FK Com, was reported later also in a number of RS CVn binaries and a single young dwarf. With the surface images obtained right before and after the ``flip-flop'', we clearly show that the ``flip-flop'' phenomenon in FK Com is caused by changing the relative strengths of the spot groups at the two active longitudes, with no actual spot movements across the stellar surface, i.e. exactly as it happens in other active stars.Comment: 4 pages, accepted by A&A Letter

Composition of Exports and Cross-Country Corruption

This research examines the connection between a country’s export structure and corruption, incorporating disaggregated data on exports for a recent time period over a large set of nations. We ask whether various types of exports (e.g. agricultural, mineral, manufacturing and fuel) exert similar influences on corruption across nations. Our results suggest that corruption decreases as nations attain prosperity, as economic and political freedoms increase, and with a larger government size. Ceteris paribus, transition countries are also found to be more corrupt. Ethnic and linguistic fractionalizations exert opposite influences on corruption, while religious fractionalization does not seem to matter. Although the effects of ore and manufacturing exports are statistically insignificant, agricultural and fuel exports affect corruption significantly. Our findings for fuel exports support previous research, as well as uniquely demonstrate that the impact of fuel exports is sensitive to the prevailing corruption level. We conclude with a discussion of policy implications.corruption; exports; resource curse; government

Causes of Corruption in Russia: A Disaggregated Analysis

This paper examines determinants of corruption across Russian regions. Key contributions include: (i) a formal study of economic corruption determinants across Russian regions; (ii) comparisons of determinants of perceived corruption versus those of actual corruption; and (iii) studying the influence of market competition and other factors on corruption. The results show that economic prosperity, population, market competition and urbanization are significant determinants of Russian corruption. The use of alternative corruption measures reveals that economic prosperity and population have a largely similar impact on corruption perceptions and corruption incidence. However, there are significant differences in the effects of competition and urbanization.corruption perceptions; corruption incidence; Russia; government; competition

Causes of Corruption in Russia: A Disaggregated Analysis

This paper examines determinants of corruption across Russian regions. Key contributions include: (i) a formal study of economic corruption determinants across Russian regions; (ii) comparisons of determinants of perceived corruption versus those of actual corruption; and (iii) studying the influence of market competition and other factors on corruption. The results show that economic prosperity, population, market competition and urbanization are significant determinants of Russian corruption. The use of alternative corruption measures reveals that economic prosperity and population have a largely similar impact on corruption perceptions and corruption incidence. However, there are significant differences in the effects of competition and urbanization.corruption perceptions, corruption incidence, Russia, government, competition

Flip-flop phenomenon: observations and theory

In many active stars the spots concentrate on two permanent active longitudes which are 180 degrees apart. In some of these stars the dominant part of the spot activity changes the longitude every few years. This so-called flip-flop phenomenon has up to now been reported in 11 stars, both single and binary alike, and including also the Sun. To explain this phenomenon, a non-axisymmetric dynamo mode, giving rise to two permanent active longitudes at opposite stellar hemispheres, is needed together with an oscillating axisymmetric magnetic field. Here we discuss the observed characteristics of the flip-flop phenomenon and present a dynamo solution to explain them.Comment: 4 pages, 5 figures, contribution to the conference "Dynamos of the Sun, Stars and Planets", to be published in AN Volume 32

A Finite Element Study of Micropipette Aspiration of Single Cells: Effect of Compressibility

Micropipette aspiration (MA) technique has been widely used to measure the viscoelastic properties of different cell types. Cells experience nonlinear large deformations during the aspiration procedure. Neo-Hookean viscohyperelastic (NHVH) incompressible and compressible models were used to simulate the creep behavior of cells in MA, particularly accounting for the effect of compressibility, bulk relaxation, and hardening phenomena under large strain. In order to find optimal material parameters, the models were fitted to the experimental data available for mesenchymal stem cells. Finally, through Neo-Hookean porohyperelastic (NHPH) material model for the cell, the influence of fluid flow on the aspiration length of the cell was studied. Based on the results, we suggest that the compressibility and bulk relaxation/fluid flow play a significant role in the deformation behavior of single cells and should be taken into account in the analysis of the mechanics of cells