An active state of the BL Lac Object Markarian 421 detected by INTEGRAL in April 2013

Multiwavelength variability of blazars offers indirect insight into their powerful engines and on the mechanisms through which energy is propagated from the centre down the jet. The BL Lac object Mkn 421 is a TeV emitter, a bright blazar at all wavelengths, and therefore an excellent target for variability studies. Mkn 421 was observed by INTEGRAL and Fermi-LAT in an active state on 16-21 April 2013. Well sampled optical, soft, and hard X-ray light curves show the presence of two flares. The average flux in the 20-100 keV range is 9.1e-11 erg/s/cm2 (~4.5 mCrab) and the nuclear average apparent magnitude, corrected for Galactic extinction, is V ~12.2. In the time-resolved X-ray spectra (3.5-60 keV), which are described by broken power laws and, marginally better, by log-parabolic laws, we see a hardening that correlates with flux increase, as expected in refreshed energy injections in a population of electrons that later cool via synchrotron radiation. The hardness ratios between the JEM-X fluxes in two different bands and between the JEM-X and IBIS/ISGRI fluxes confirm this trend. During the observation, the variability level increases monotonically from the optical to the hard X-rays, while the large LAT errors do not allow a significant assessment of the MeV-GeV variability. The cross-correlation analysis during the onset of the most prominent flare suggests a monotonically increasing delay of the lower frequency emission with respect to that at higher frequency, with a maximum time-lag of about 70 minutes, that is however not well constrained. The spectral energy distributions from the optical to the TeV domain are satisfactorily described by homogeneous models of blazar emission based on synchrotron radiation and synchrotron self-Compton scattering, except in the state corresponding to the LAT softest spectrum and highest flux.Comment: 11 pages, 6 figures, in press in A&

Jet quenching in the neutron star low-mass X-ray binary 1RXS J180408.9-342058

We present quasi-simultaneous radio (VLA) and X-ray (Swift) observations of the neutron star low-mass X-ray binary (NS-LMXB) 1RXS J180408.9-342058 (J1804) during its 2015 outburst. We found that the radio jet of J1804 was bright (232 ± 4 µJy at 10 GHz) during the initial hard X-ray state, before being quenched by more than an order of magnitude during the soft X-ray state (19 ± 4 µJy). The source then was undetected in radio ( < 13 µJy) as it faded to quiescence. In NS-LMXBs, possible jet quenching has been observed in only three sources and the J1804 jet quenching we show here is the deepest and clearest example to date. Radio observations when the source was fading towards quiescence (L X = 10 34-35 erg s -1 ) show that J1804 must follow a steep track in the radio/X-ray luminosity plane with ß > 0.7 (where L R a L X ß ). Few other sources have been studied in this faint regime, but a steep track is inconsistent with the suggested behaviour for the recently identified class of transitional millisecond pulsars. J1804 also shows fainter radio emission at L X < 10 35 erg s -1 than what is typically observed for accreting millisecond pulsars. This suggests that J1804 is likely not an accreting X-ray or transitional millisecond pulsar. © 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society

Fire Sale Bank Recapitalizations

status: accepte

APPLICATIONS OF PHOTOACOUSTIC AND DIFFUSE REFLECTANCE SPECTROSCOPY IN MINERALS FLOTATION

La spectroscopie photoacoustique (PAS) et la spectroscopie par réflexion diffuse (DRS) nous ont servi à mesurer la concentration superficielle du cuivre à la surface de poudres de sulfure de zinc ou de blende. Les appareillages ont été préalablement testés sur un système modèle (colorants adsorbés sur de la silice).Photoacoustic spectroscopy (PAS) and diffuse reflectance spectroscopy (DRS) have been used to get the surface concentration of copper on powders of zinc sulfide or sphalerites. Spectrometer were first tested on a model system (dyes adsorbed on silica)

Who Monitors the Monitor? Bank Capital Structure and Borrower Monitoring Who Monitors the Monitor? Bank Capital Structure and Borrower Monitoring

Abstract The role that banks play in screening and monitoring their borrowers is well understood. However, these bank activities are costly and unobservable, thus difficult to contract upon. This introduces the possibility of shirking and leads to the question -who monitors the monitor? Financial intermediation theories posit that bank capital structure plays such a role in incentivizing banks to monitor their borrowers. Both bank debt and bank equity have been proposed in various theories as providing the discipline to induce banks to monitor. However, empirical evidence on how bank capital structure influences borrower monitoring is scant. To circumvent identification concerns with regressing (unobservable) bank monitoring on (endogenous) bank capital structure, we use variation in country-level creditor rights to capture banks' need to monitor their borrowers. We develop a theoretical model in which greater ex-post protection offered to lenders (i.e., banks) during borrower bankruptcy/renegotiation reduces the bank's ex-ante incentives to monitor. This is because the greater salvage value of bank loans reduces the bank's expected loss from not monitoring. Our model also examines how banks alter their capital structures in response to changes in their country's creditor rights, and shows that the reduced demand for bank monitoring induced by stronger creditor rights induces the bank to shift its capital structure away from the source of financing that induces it to monitor. We find empirically that increases in creditor rights result in banks tilting their capital structures away from equity and towards deposits. We verify (theoretically and empirically) that these demandbased tilts in bank capital structure are not explained by supply-side effects (i.e., creditor rights make it cheaper to supply bank debt), and conclude that bank equity is a stronger source of discipline on banks than bank debt. JEL classification: G15, G21, G3