30 research outputs found
Contemporary Flat-Tax Reforms in Eastern Europe. Causes of Diverse Approaches : A comparison of Slovakia, Czech Republic and Germany.
The paper deals with the issue of contemporary flat-tax reforms in Eastern Europe and aims to account for the different approaches that various European countries adopted towards the idea of a flat-tax. Empirically, the work is based on detailed studies of Slovakia, the Czech Republic and Germany. The analysis considers three factors being decisive for the flat-tax feasibility: 1./ party system institutionalization, 2./ coalition/opposition cohesiveness, 3./ labor union institutionalization. First, the study is concerned with each of the factor's influence on the political decision-making process in the three country cases. Secondly, on country paired comparisons the findings for each of the countries are mutually contrasted. Although all identified factors seem to be at play with regard to flat-tax feasibility, I argue that it is either the strength or the weakness of labor unions' institutionalization and welfare identity that underlie the political decision-making in the East and the West and as a result determine the flat-tax (un-)feasibility. The absence of welfare identity in the East allows for higher coalition cohesion in favor and weaker opposition against the flattax adoption in contrast to the West.Series: Discussion Papers SFB International Tax Coordinatio
Productivity of Solar Flares and Magnetic Helicity Injection in Active Regions
The main objective of this study is to better understand how magnetic
helicity injection in an active region is related to the occurrence and
intensity of solar flares. We therefore investigate magnetic helicity injection
rate and unsigned magnetic flux, as a reference. In total, 378 active regions
are analyzed using /MDI magnetograms. The 24-hour averaged helicity
injection rate and unsigned magnetic flux are compared with the flare index and
the flare-productive probability in next 24 hours following an measurement. In
addition, we study the variation of helicity over a span of several days around
the times of the 19 flares above M5.0 which occurred in selected strong
flare-productive active regions. The major findings of this study are: (1) for
a sub-sample of 91 large active regions with unsigned magnetic fluxes in the
range from 3 to 5 10 Mx, there is a difference in magnetic
helicity injection rate between flaring active regions and non-flaring active
regions by a factor of 2; (2) the C-flare-productive probability as a
function of helicity injection displays a sharp boundary between
flare-productive active regions and flare-quiet ones; (3) the history of
helicity injection before all the 19 major flares displayed a common
characteristic: a significant helicity accumulation of (3-45) 10
Mx during a phase of monotonically increasing helicity over 0.5 to
2 days. Our results support the notion that helicity injection is important in
flares, but it is not effective to use it alone for the purpose of flare
forecast. It is necessary to find a way to better characterize the time history
of helicity injection as well as its spatial distribution inside active
regions.Comment: 22 pages, 5 figures, ApJ, in pres
Bimodal Distribution of Area-Weighted Latitude of Sunspots And Solar North-South Asymmetry
We study the latitudinal distribution of sunspots observed from 1874 to 2009
using the center-of-latitude (COL). We calculate COL by taking the
area-weighted mean latitude of sunspots for each calendar month. We then form
the latitudinal distribution of COL for the sunspots appearing in the northern
and southern hemispheres separately, and in both hemispheres with unsigned and
signed latitudes, respectively. We repeat the analysis with subsets which are
divided based on the criterion of which hemisphere is dominant for a given
solar cycle. Our primary findings are as follows: (1) COL is not monotonically
decreasing with time in each cycle. Small humps can be seen (or short plateaus)
around every solar maxima. (2) The distribution of COL resulting from each
hemisphere is bimodal, which can well be represented by the double Gaussian
function. (3) As far as the primary component of the double Gaussian function
is concerned, for a given data subset, the distributions due to the sunspots
appearing in two different hemispheres are alike. Regardless of which
hemisphere is magnetically dominant, the primary component of the double
Gaussian function seems relatively unchanged. (4) When the northern (southern)
hemisphere is dominant the width of the secondary component of the double
Gaussian function in the northern (southern) hemisphere case is about twice as
wide as that in the southern (northern) hemisphere. (5) For the distribution of
the COL averaged with signed latitude, whose distribution is basically
described by a single Gaussian function, it is shifted to the positive
(negative) side when the northern (southern) hemisphere is dominant. Finally,
we conclude by briefly discussing the implications of these findings on the
variations in the solar activity.Comment: Accepted for publication in New Astronom
A Statistical Study on Photospheric Magnetic Nonpotentiality of Active Regions and Its Relationship with Flares during Solar Cycles 22-23
A statistical study is carried out on the photospheric magnetic
nonpotentiality in solar active regions and its relationship with associated
flares. We select 2173 photospheric vector magnetograms from 1106 active
regions observed by the Solar Magnetic Field Telescope at Huairou Solar
Observing Station, National Astronomical Observatories of China, in the period
of 1988-2008, which covers most of the 22nd and 23rd solar cycles. We have
computed the mean planar magnetic shear angle (\bar{\Delta\phi}), mean shear
angle of the vector magnetic field (\bar{\Delta\psi}), mean absolute vertical
current density (\bar{|J_{z}|}), mean absolute current helicity density
(\bar{|h_{c}|}), absolute twist parameter (|\alpha_{av}|), mean free magnetic
energy density (\bar{\rho_{free}}), effective distance of the longitudinal
magnetic field (d_{E}), and modified effective distance (d_{Em}) of each
photospheric vector magnetogram. Parameters \bar{|h_{c}|}, \bar{\rho_{free}},
and d_{Em} show higher correlation with the evolution of the solar cycle. The
Pearson linear correlation coefficients between these three parameters and the
yearly mean sunspot number are all larger than 0.59. Parameters
\bar{\Delta\phi}, \bar{\Delta\psi}, \bar{|J_{z}|}, |\alpha_{av}|, and d_{E}
show only weak correlations with the solar cycle, though the nonpotentiality
and the complexity of active regions are greater in the activity maximum
periods than in the minimum periods. All of the eight parameters show positive
correlations with the flare productivity of active regions, and the combination
of different nonpotentiality parameters may be effective in predicting the
flaring probability of active regions.Comment: 20 pages, 5 figures, 4 tables, accepted for publication in Solar
Physic
A statistical study on photospheric active-region magnetic nonpotentiality and associated flares during solar cycles 22 – 23
Relationships of a growing magnetic flux region to flares
Some sites for solar flares are known to develop where new magnetic flux emerges and becomes abutted against opposite polarity pre-existing magnetic flux (review by Galzauskas/1/). We have identified and analyzed the evolution of such flare sites at the boundaries of a major new and growing magnetic flux region within a complex of active regions, Hale No. 16918. This analysis was done as a part of a continuing study of the circumstances associated with flares in Hale Region 16918, which was designated as an FBS target during the interval 18 – 23 June 1980. We studied the initiation and development of both major and minor flares in Hα images in relation to the identified potential flare sites at the boundaries of the growing flux region and to the general development of the new flux. This study lead to our recognition of a spectrum of possible relationships of growing flux regions to flares as follows: (1) intimate interaction with adjacent old flux — flare sites centered at new/old flux boundary, (2) forced or “intimidated” interaction in which new flux pushes old field having lower flux density towards a neighboring old polarity inversion line where a flare then takes place, (3) “influential” interaction — magnetic lines of force over an old polarity inversion line, typically containing a filament, reconnect to the new emerging flux; a flare occurs with erupting filament when the magnetic field overlying the filament becomes too weak to prevent its eruption, (4) inconsequential interaction — new flux region is too small or has wrong orientation for creating flare conditions, (5) incidental — flare occurs without any significant relationship to new flux regions