Mean-field theory for Bose-Hubbard Model under a magnetic field

We consider the superfluid-insulator transition for cold bosons under an effective magnetic field. We investigate how the applied magnetic field affects the Mott transition within mean field theory and find that the critical hopping strength $(t/U)_c$, increases with the applied field. The increase in the critical hopping follows the bandwidth of the Hofstadter butterfly at the given value of the magnetic field. We also calculate the magnetization and superfluid density within mean field theory.Comment: 11 pages, 7 figures, published versio

Spatial analysis of locational conflicts: case study: locational conflicts generated by the expansion of built up surfaces in the northern area of Bucharest, Romania

The aim of this paper is to identify and analyze land use conflicts existing in the northern area of Bucharest and to spatially model their impact on the expandint residential areas. The main objectives are: 1) to analyze the dynamics of built up surfaces between 1975-2010; 2) to analyze the spatial and temporal dynamic of locational conflicts and 3) to spatially model the impact of locational conflicts on residential areas.Peer Reviewe

Coulomb effects on the transport properties of quantum dots in strong magnetic field

We investigate the transport properties of quantum dots placed in strong magnetic field using a quantum-mechanical ' approach based on the 2D tight-binding Hamiltonian with direct Coulomb interaction and the Landauer-B\"{u}ttiker (LB) formalism. The electronic transmittance and the Hall resistance show Coulomb oscillations and also prove multiple addition processes. We identify this feature as the 'bunching' of electrons observed in recent experiments and give an elementary explanation in terms of spectral characteristics of the dot. The spatial distribution of the added electrons may distinguish between edge and bulk states and it has specific features for bunched electrons. The dependence of the charging energy on the number of electrons is discussed for strong and vanishing magnetic field. The crossover from the tunneling to quantum Hall regime is analyzed in terms of dot-lead coupling.Comment: 17 pages,8 figures,Revtex,submitted to Physical Review

Spin magnetization of strongly correlated electron gas confined in a two-dimensional finite lattice

The influence of disorder and interaction on the ground state polarization of the two-dimensional (2D) correlated electron gas is studied by numerical investigations of unrestricted Hartree-Fock equations. The ferromagnetic ground state is found to be plausible when the electron number is lowered and the interaction and disorder parameters are suitably chosen. For a finite system at constant electronic density the disorder induced spin polarization is cut off when the electron orbitals become strongly localized to the individual network sites. The fluctuations of the interaction matrix elements are calculated and brought out as favoring the ferromagnetic instability in the extended and weak localization regime. The localization effect of the Hubbard interaction term is discussed.Comment: 7 pages, 9 figure

Investigation of the Δn = 0 selection rule in Gamow-Teller transitions : The β-decay of 207 Hg

Gamow-Teller β decay is forbidden if the number of nodes in the radial wave functions of the initial and final states is different. This Δn=0 requirement plays a major role in the β decay of heavy neutron-rich nuclei, affecting the nucleosynthesis through the increased half-lives of nuclei on the astrophysical r-process pathway below both Z=50 (for N>82) and Z=82 (for N>126). The level of forbiddenness of the Δn=1ν1g 9/2 →π0g 7/2 transition has been investigated from the β − decay of the ground state of 207 Hg into the single-proton-hole nucleus 207 Tl in an experiment at the ISOLDE Decay Station. From statistical observational limits on possible γ-ray transitions depopulating the π0g 7/2 −1 state in 207 Tl, an upper limit of 3.9×10 −3 % was obtained for the probability of this decay, corresponding to log⁡ft>8.8 within a 95% confidence limit. This is the most stringent test of the Δn=0 selection rule to date

THE RELIGIOUS STRUCTURE OF THE ROMANIAN POPULATION IN 2011 BY COUNTIES AND GEOGRAPHICAL-HISTORICAL PROVINCES

The Religious Structure of the Romanian Population in 2011 by Counties and Geographical-Historical Provinces. Our study addresses the issue of religion, which is one of the essential geo-demographic structures in the study of the Romanian population. We were motivated by the fact that it was not possible to study this issue in the period of 1948-1989 since censuses did not include data on religion. The situation of religion has become more visible and individualized only since the last decade of the last century and afterwards once with the censuses of 1992 and 2002 up to present day. More broadly, this study examines the key aspects of denominational structure of the Romanian population, based on the census conducted on 20 October 2011 at national level, data being provided by the National Institute of Statistics. Our research work consisted in the collection and processing of statistical data, subsequently synthesised in tables and graphical material (three tables and three figures). Table 1 provides key comparative data on the general religious structure of the Romanian population registered at the censuses in 2002 and 2011. Table 2 is the main source of information of this study, revealing the religious structure and territorial distribution of the Romanian population in the geographical – historical provinces and counties in 2011. Table 3 is a synthesis in which we present the total population at county and provinces level as absolute data (digits) and rates in case of the five main religious denominations (i.e. Orthodox, Roman Catholic, Reformed, Pentecostal and Greek-Catholic, the remaining religious denominations being grouped into the category of Other religions and Atheists. The research results are also highlighted by three charts and maps, allowing for the easy tracking of the subject as a whole and territorially, at county level and in the geographical-historical provinces. In a brief presentation of the topic addressed it can be emphasized that the Romanian population recorded at the census in 2011 was of 20,121,641 inhabitants, of which 81.04 % Christian Orthodox, 4.33% Roman-Catholic, 2.99% Protestant, 1.80% Greek-Catholic, and 0.75% Pentecostal. The other 16 denominations (Baptist, Seventh-Day Adventists, Muslim, Unitarian, Jehovah’s Witnesses, Christian Evangelical, Christian of Old Rite, Lutheran Evangelical, Serbian Orthodox, Evangelical, Evangelical of Augustan Confession, Mosaic, Armenian, another religion, free of religion and atheists) hold only 2.83% of the population of our country. Approximately 6.26% of the population did not provide information on their religion (see tables 1, 2 and 3). Regarding the degree of representativeness of religious denominations in Romania, we conclude that the share of Orthodox religion population (81.04% of the 20,121,641 inhabitants of the country) expresses normality, given that on the one hand 6.26% of the registered population (1,259,739 persons) was included in the category of Unavailable Information, and on the other hand the difference of 12.7% (2,554,898 people) belongs to other 20 recorded religions, emphasizing that only the Roman-Catholic, Reformed and Pentecostal denominations registered a little over 1% (see table 1)