La Corporate Governance in Ungheria: il Modello Dualistico e la Budapest Stock Exchange

Il presente lavoro consiste nell’analisi della corporate governance ed in particolare del modello di amministrazione e controllo di tipo dualistico in un Paese che ha risentito in modo esemplare delle vicende storiche legate al disfacimento dell’ex impero sovietico alla fine degli anni ‘80, l’Ungheria. Il passaggio da un sistema ad economia pianificata al capitalismo ha comportato una serie di riforme sostanziali e incisive che necessitavano dell’afflusso di capitali esteri. Ciò ha reso indispensabile per le aziende l’adozione di pratiche di buon governo societario per incentivare la partecipazione degli investitori internazionali al capitale di rischio e di prestito. Sono stati emanati una serie di codici di condotta e il contributo di maggior rilevanza è stato quello fornito dalla Budapest Stock Exchange, le cui Raccomandazioni devono essere rispettate o, in caso di mancata adesione, adeguatamente giustificate dalle società quotate. Il capitolo 1 illustra i motivi del crollo del blocco sovietico e lo scenario economico e politico ungherese prima e dopo le consistenti opere di riforma avvenute nel periodo della “transizione”. Il capitolo 2 riguarda le caratteristiche tipiche del modello di amministrazione e controllo prevalente in Ungheria, il dualistico di stampo tedesco. Vengono evidenziati gli organi societari del modello in base sia alla normativa che secondo le best practice. Infine, vengono esaminate le differenze esistenti fra la Germania e l’Ungheria, riguardanti ad esempio il tema della rappresentanza dei lavoratori nei consigli di sorveglianza, che rappresenta il fulcro del modello tedesco e che invece riveste un ruolo soltanto marginale in Ungheria. Il capitolo 3 descrive l’andamento del mercato dei capitali ungherese, l’evoluzione della Budapest Stock Exchange e il Gruppo di cui fa parte, il Central Eastern Europe Exchange Group (CEESEG). Il capitolo 4 è dedicato all’analisi della governance nelle tre maggiori società quotate ungheresi (per capitalizzazione) evidenziandone similitudini, differenze e criticità

Production of TeV gamma-radiation in the vicinity of the supermassive black hole in the giant radiogalaxy M87

Although the giant radiogalaxy M 87 harbors many distinct regions of broad-band nonthermal emission, the recently reported fast variability of TeV gamma rays from M 87 on a timescale of days strongly constrains the range of speculations concerning the possible sites and scenarios of particle acceleration responsible for the observed TeV emission. A natural production site of this radiation is the immediate vicinity of the central supermassive mass black hole (BH). Because of the low bolometric luminosity, the nucleus of M 87 is effectively transparent for gamma rays up to energy of 10 TeV, which makes this source an ideal laboratory for study of particle acceleration processes close to the BH event horizon. We critically analyse different possible radiation mechanisms in this region, and argue that the observed very high-energy gamma ray emission can be explained by the inverse Compton emission of ultrarelativistic electron-positron pairs produced through the development of an electromagnetic cascade in the BH magnetosphere. We demonstrate, through detailed numerical calculations of acceleration and radiation of electrons in the magnetospheric vacuum gap, that this ``pulsar magnetosphere like'' scenario can satisfactorily explain the main properties of TeV gamma-ray emission of M 87.Comment: 11 pages, ApJ, in prin

Concentrations of Selected Heavy Metals in Bones and Femoral Bone Structure of Bank (Myodes glareolus) and Common (Microtus arvalis) Voles from Different Polluted Biotopes in Slovakia

Concentrations of selected heavy metals in the femora and femoral bone structure of bank (Myodes glareolus) and common (Microtus arvalis) voles from different polluted biotopes in Slovakia (Kolíňany and Nováky sites) were investigated. Length, weight, and histological structure of vole bones were also analyzed. We observed higher concentrations of lead (Pb), iron (Fe), copper (Cu), and zinc (Zn) in the bones of both species from the Kolíňany site. Significant differences were observed in the concentration of Fe in bank and common voles (p < 0.05) and in the concentration of Zn (p < 0.05) in common voles. The animals from Nováky had higher concentrations of cadmium (Cd) and nickel (Ni) in their bones; however, the differences were not significant. The measured values for bone length and weight were higher in both species from Nováky (p < 0.05). We did not identify differences in qualitative histological characteristics of the femora between the voles (M. glareolus and M. arvalis separately) between the two biotopes. In addition, no statistically significant differences for any the measured variables of primary osteons’ vascular canals were observed. Correlation analysis in M. glareolus showed a strong positive relation between Cd and Ni (r = 0.52), Pb and bone weight (r = 0.53), Fe and bone weight (r = 0.52), and Fe and perimeter size of primary osteons’ vascular canals (r = 0.55). In common voles, a strong positive relation was found between Fe and Cu (r = 0.60) and between Fe and perimeter size of vascular canals of primary osteons (r = 0.55). Our results indicate that accumulation of some heavy metals is slightly increased in the femora of both species at Kolíňany

Depletion of Nonlinearity in Magnetohydrodynamic Turbulence: Insights from Analysis and Simulations

We build on recent developments in the study of fluid turbulence [Gibbon \textit{et al.} Nonlinearity 27, 2605 (2014)] to define suitably scaled, order-$m$ moments, $D_m^{\pm}$, of $\omega^\pm= \omega \pm j$, where $\omega$ and $j$ are, respectively, the vorticity and current density in three-dimensional magnetohydrodynamics (MHD). We show by mathematical analysis, for unit magnetic Prandtl number $P_M$, how these moments can be used to identify three possible regimes for solutions of the MHD equations; these regimes are specified by inequalities for $D_m^{\pm}$ and $D_1^{\pm}$. We then compare our mathematical results with those from our direct numerical simulations (DNSs) and thus demonstrate that 3D MHD turbulence is like its fluid-turbulence counterpart insofar as all solutions, which we have investigated, remain in \textit{only one of these regimes}; this regime has depleted nonlinearity. We examine the implications of our results for the exponents $q^{\pm}$ that characterize the power-law dependences of the energy spectra $\mathcal{E}^{\pm}(k)$ on the wave number $k$, in the inertial range of scales. We also comment on (a) the generalization of our results to the case $P_M \neq 1$ and (b) the relation between $D_m^{\pm}$ and the order-$m$ moments of gradients of hydrodynamic fields, which are used in characterizing intermittency in turbulent flows.Comment: 14 pages, 3 figure

X-ray Emitting GHz-Peaked Spectrum Galaxies: Testing a Dynamical-Radiative Model with Broad-Band Spectra

In a dynamical-radiative model we recently developed to describe the physics of compact, GHz-Peaked-Spectrum (GPS) sources, the relativistic jets propagate across the inner, kpc-sized region of the host galaxy, while the electron population of the expanding lobes evolves and emits synchrotron and inverse-Compton (IC) radiation. Interstellar-medium gas clouds engulfed by the expanding lobes, and photoionized by the active nucleus, are responsible for the radio spectral turnover through free-free absorption (FFA) of the synchrotron photons. The model provides a description of the evolution of the spectral energy distribution (SED) of GPS sources with their expansion, predicting significant and complex high-energy emission, from the X-ray to the gamma-ray frequency domain. Here, we test this model with the broad-band SEDs of a sample of eleven X-ray emitting GPS galaxies with Compact-Symmetric-Object (CSO) morphology, and show that: (i) the shape of the radio continuum at frequencies lower than the spectral turnover is indeed well accounted for by the FFA mechanism; (ii) the observed X-ray spectra can be interpreted as non-thermal radiation produced via IC scattering of the local radiation fields off the lobe particles, providing a viable alternative to the thermal, accretion-disk dominated scenario. We also show that the relation between the hydrogen column densities derived from the X-ray (N_H) and radio (N_HI) data of the sources is suggestive of a positive correlation, which, if confirmed by future observations, would provide further support to our scenario of high-energy emitting lobes.Comment: 29 pages, 3 figures, 6 tables; to appear in ApJ. A few clarifications included, according to referee's suggestion

Fermi LAT Gamma-ray Detections of Classical Novae V1369 Centauri 2013 and V5668 Sagittarii 2015

We report the Fermi Large Area Telescope (LAT) detections of high-energy (>100 MeV) gamma-ray emission from two recent optically bright classical novae, V1369 Centauri 2013 and V5668 Sagittarii 2015. At early times, Fermi target-of-opportunity observations prompted by their optical discoveries provided enhanced LAT exposure that enabled the detections of gamma-ray onsets beginning ~2 days after their first optical peaks. Significant gamma-ray emission was found extending to 39-55 days after their initial LAT detections, with systematically fainter and longer duration emission compared to previous gamma-ray detected classical novae. These novae were distinguished by multiple bright optical peaks that encompassed the timespans of the observed gamma rays. The gamma-ray light curves and spectra of the two novae are presented along with representative hadronic and leptonic models, and comparisons to other novae detected by the LAT are discussed.Comment: 13 pages, 6 figures, 4 tables, ApJ accepte