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We present a detailed spectral and temporal analysis of the black-hole candidate MAXI~J1535$-$571 using NICER observations in September and October 2017. We focus specifically on observations in the hard-intermediate state when the source shows type-C quasi-periodic oscillations (QPOs). We fitted the time-averaged spectrum of the source and the rms and phase-lag spectra of the QPO with a one-component time-dependent Comptonization model. We found that the corona contracts from $\sim 10^4$ to $\sim 3 \times 10^3$ km as the QPO frequency increases from $\sim 1.8$ Hz to $\sim 9.0$ Hz. The fits suggest that the system would consists of two coronas, a small one that dominates the time-averaged spectrum and a larger one, possibly the jet, that dominates the rms and lag spectra of the QPO. We found a significant break in the relation of the spectral parameters of the source and the properties of the QPO, including its lag spectra, with QPO frequency. The change in the relations happens when the QPO frequency crosses a critical frequency $\nu_c \approx 3.0$ Hz. Interestingly, the QPO reaches this critical frequency simultaneously as the radio emission from the jet in this source is quenched., Comment: 15 pages, 8 figures, accepted for publication in MNRAS

The clumpy stellar wind from the companion star in high mass X-ray binaries causes variable, partial absorption of the emission from the X-ray source. We studied XMM-Newton observations from the 7.22 d-long "Cyg X-1 Hard state Observations of a Complete Binary Orbit in X-rays" (CHOCBOX) monitoring campaign, in order to constrain the effects of the stellar wind on the short-timescale X-ray spectral-timing properties of the source. We find these properties to change significantly in the presence of the wind. In particular, the longest sampled timescales (corresponding to temporal frequencies of $\nu\sim$ 0.1-1 Hz) reveal an enhancement of the fractional variability power, while on the shortest sampled timescales ($\nu\sim$ 1-10 Hz) the variability is suppressed. In addition, we observe a reduction (by up to a factor of $\sim$ 1.8) of the otherwise high coherence between soft and hard band light curves, as well as of the amplitude of the hard X-ray lags intrinsic to the X-ray continuum. The observed increase of low frequency variability power can be explained in terms of variations of the wind column density as a consequence of motions of the intervening clumps. In this scenario (and assuming a terminal velocity of $v_{\infty}=2400\ {\rm km\ s^{-1}}$), we obtain an estimate of $l \sim$ 0.5-1.5 $\times 10^{-4} R_{\ast}$ for the average radial size of a clump. On the other hand, we suggest the behaviour at high frequencies to be due to scattering in an optically thicker medium, possibly formed by collision of the stellar wind with the edge of the disc., Comment: 16 pages, 13 figures

We present a high time resolution, multi-frequency linear polarization analysis of Very Large Array (VLA) radio observations during some of the brightest radio flaring (~1 Jy) activity of the 2015 outburst of V404 Cygni. The VLA simultaneously captured the radio evolution in two bands (each with two 1 GHz base-bands), recorded at 5/7 GHz and 21/26 GHz, allowing for a broadband polarimetric analysis. Given the source's high flux densities, we were able to measure polarization on timescales of ~13 minutes, constituting one of the highest temporal resolution radio polarimetric studies of a black hole X-ray binary (BHXB) outburst to date. Across all base-bands, we detect variable, weakly linearly polarized emission (, 24 pages, 9 figures, accepted by MNRAS

MAXI J1535-571 is a black-hole X-ray binary that in 2017 exhibited a very bright outburst which reached a peak flux of up to 5 Crab in the 2-20 keV band. Given the high flux, several X-ray space observatories obtained unprecedented high signal-to-noise data of key parts of the outburst. In our previous paper we studied the corona of MAXI J1535-571 in the hard-intermediate state (HIMS) with Insight-HXMT. In this paper we focus on the study of the corona in the soft-intermediate state (SIMS) through the spectral-timing analysis of 26 NICER detections of the type-B quasi-periodic oscillations (QPOs). From simultaneous fits of the energy, rms and lag spectra of these QPOs with our time-dependent Comptonization model, we find that in the SIMS the corona size is ~ 6500 km and vertically extended. We detect a narrow iron line in the energy spectra, which we interpret to be due to the illumination of the outer part of the accretion disk by this large corona. We follow the evolution of the corona and the radio jet during the HIMS-SIMS transition, and find that the jet flux peaks after the time when the corona extends to its maximum vertical size. The jet flux starts to decay after the corona contracts vertically towards the black hole. This behavior points to a connection between the X-ray corona and the radio jet similar to that seen in other sources., Comment: 13 pages, 7 figures, accepted for publication in MNRAS

GRS 1915+105 can show type-C quasi-periodic oscillations (QPOs) in the power density spectrum. A high-frequency QPO (HFQPO) at 67 Hz has been observed in this source, albeit less often than the type-C QPOs. Besides these features, GRS 1915+105 sometimes shows a broad bump in the power spectrum at around 30-150 Hz. We study the power spectra of GRS 1915+105 with the Rossi X-ray Timing Explorer when the source was in the $\chi$ class. We find that the rms amplitude of the bump depends strongly upon both the frequency of the type-C QPO and the hardness ratio, and is correlated with the corona temperature and anti-correlated with the radio flux at 15 GHz. The characteristic frequency of the bump is better correlated with a combination of the frequency of the type-C QPO and the hardness ratio than with the frequency of the type-C QPO alone. The rms amplitude of the bump generally increases with energy from ~1-2% at ~3 keV to ~10-15% at ~30 keV. We suggest that the bump and the high-frequency QPO may be the same variability component but the properties of the corona affect the coherence of this variability, leading either to a HFQPO when the spectrum is in the relatively soft $\gamma$ class, or to a bump when the spectrum is in the hard $\chi$ class. Finally, we discuss the anti-correlation between the rms amplitude of the bump and the radio flux in the context of the relation between the corona and the jet., Comment: 11 pages, 7 figures, accepted for publication in MNRAS

During a 2018 outburst, the black hole X-ray binary MAXI J1820+070 was comprehensively monitored at multiple wavelengths as it underwent a hard to soft state transition. During this transition a rapid evolution in X-ray timing properties and a short-lived radio flare were observed, both of which were linked to the launching of bi-polar, long-lived relativistic ejecta. We provide detailed analysis of two Very Long Baseline Array observations, using both time binning and a new dynamic phase centre tracking technique to mitigate the effects of smearing when observing fast-moving ejecta at high angular resolution. We identify a second, earlier ejection, with a lower proper motion of $18.0\pm1.1$ mas day$^{-1}$. This new jet knot was ejected $4\pm1$ hours before the beginning of the rise of the radio flare, and $2\pm1$ hours before a switch from type-C to type-B X-ray quasi-periodic oscillations (QPOs). We show that this jet was ejected over a period of $\sim6$ hours and thus its ejection was contemporaneous with the QPO transition. Our new technique locates the original, faster ejection in an observation in which it was previously undetected. With this detection we revised the fits to the proper motions of the ejecta and calculated a jet inclination angle of $(64\pm5)^\circ$, and jet velocities of $0.97_{-0.09}^{+0.03}c$ for the fast-moving ejecta ($\Gamma>2.1$) and $(0.30\pm0.05)c$ for the newly-identified slow-moving ejection ($\Gamma=1.05\pm0.02$). We show that the approaching slow-moving component is predominantly responsible for the radio flare, and is likely linked to the switch from type-C to type-B QPOs, while no definitive signature of ejection was identified for the fast-moving ejecta., Comment: 11 pages including 5 figures. Accepted for publication in MNRAS

GRS 1915+105 was the first stellar-mass black-hole in our Galaxy to display a superluminal radio jet, similar to those observed in active galactic nuclei with a supermassive black hole at the centre. It has been proposed that the radio emission in GRS 1915+105 is fed by instabilities in the accretion disc by which the inner parts of the accretion flow is ejected in the jet. Here we show that there is a significant correlation between: (i) the radio flux, coming from the jet, and the flux of the iron emission line, coming from the disc and, (ii) the temperature of the corona that produces the high-energy part of the X-ray spectrum via inverse Compton scattering and the amplitude of a high-frequency variability component coming from the innermost part of the accretion flow. At the same time, the radio flux and the flux of the iron line are strongly anti-correlated with the temperature of the X-ray corona and the amplitude of the high-frequency variability component. These correlations persist over ~10 years, despite the highly variable X-ray and radio properties of the source in that period. Our findings provide, for the first time, incontrovertible evidence that the energy that powers this black-hole system can be directed either to the X-ray corona or the jet. When this energy is used to power the corona, raising its temperature, there is less energy left to fuel the jet and the radio flux drops, and vice versa. These facts, plus the modelling of the variability in this source show conclusively that in GRS 1915+105 the X-ray corona morphs into the jet., Comment: 54 pages, 10 figures, To appear in Nature Astronomy. Notice that this is the original submission (very first submission on May 18, 2020!); due to embargo conditions we cannot post the final, accepted, version until 6 months after publication. Final version available at: https://www.nature.com/articles/s41550-022-01617-y (please, contact the corresponding author for any further clarification)

Type-C quasi-periodic oscillations (QPOs) in black hole X-ray transients can appear when the source is in the low-hard and hard-intermediate states. The spectral-timing evolution of the type-C QPO in MAXI J1535-571 has been recently studied with Insight-HXMT. Here we fit simultaneously the time-averaged energy spectrum, using a relativistic reflection model, and the fractional rms and phase-lag spectra of the type-C QPOs, using a recently developed time-dependent Comptonization model when the source was in the intermediate state. We show, for the first time, that the time-dependent Comptonization model can successfully explain the X-ray data up to 100 keV. We find that in the hard-intermediate state the frequency of the type-C QPO decreases from 2.6 Hz to 2.1 Hz, then increases to 3.3 Hz, and finally increases to ~ 9 Hz. Simultaneously with this, the evolution of corona size and the feedback fraction (the fraction of photons up-scattered in the corona that return to the disc) indicates the change of the morphology of the corona. Comparing with contemporaneous radio observations, this evolution suggests a possible connection between the corona and the jet when the system is in the hard-intermediate state and about to transit into the soft-intermediate state., 11 pages, 6 figures, accepted for publication in MNRAS

Studies have been published on the efficacy of Dienogest in the management of pain symptoms in endometriosis. Nonetheless, few data are available on the reducing effect on endometrioma's size. The aim of the study was to evaluate if Dienogest could determine significant changes in size, as well as in symptoms. In this prospective observational study, patients were enrolled with pain symptoms and at least one endometrioma diagnosed via TV-US. The volume of the endometrioma and pain symptoms was measured according to the LxDxWx0.5233 formula and VAS, respectively. Dienogest 2 mg was administered daily. Follow-up visits were scheduled after 6 and 12 months of treatment to assess changes in patients' symptoms and endometrioma's volume. Seventy patients were enrolled, 63 patients completed a 6-month treatment. The reduction of the mean volume after 6 months was 66.71%. Fifty-eight patients completed the 12 month-treatment. The reduction of the mean volume after 12 months was 76.19%. Dysmenorrhea showed a 74.05% reduction after 6 months and a 96.55% reduction after 12 months. Patients reported a reduction in dyspareunia and chronic pelvic pain of 42.71% and 48.91% after 6 months and 51.93% and 59.96% after 12 months, respectively. Dienogest leads to a statistically significant reduction of endometrioma's volume and pain symptoms.

INTRODUCTION. This paper contributes to the study of peer interactions in the university classroom. METHOD. We evaluate the effects of teamwork on individual academic performance in four Team Based Learning (TBL) courses in the degrees of Economics and Business Administration. RESULTS. We found that the average grade of the rest of the team members has a significant and positive association with the grade of the individual student. The student’s personal test score increases about 0.65 points for every 1-point increase in the average score of their teammates. This association remains positive and significant even when we include socio-demographic variables to control for individual characteristics. We also tested the heterogeneity of peer effects in relation to the ability of individual and team performance. DISCUSSION. The results suggest there is no heterogeneity in individual ability; however, we found a positive or slightly negative difference in the magnitude of the peer effect for teams in the top/bottom quartile compared to teams in the middle of the distribution.

We report the energy-resolved broadband timing analysis of the black hole X-ray transient MAXI J1631-479 during its 2019 outburst from February 11 to April 9, using data from the Insight-Hard X-ray Modulation Telescope (Insight-HXMT), which caught the source from its hard intermediate state to the soft state. Thanks to the large effective area of Insight-HXMT at high energies, we are able to present the energy dependence of fast variability up to ~100 keV. Type-C quasi-periodic oscillations (QPOs) with frequency varying between 4.9 Hz and 6.5 Hz are observed in the 1-100 keV energy band. While the QPO fractional rms increases with photon energy from 1 keV to ~10 keV and remains more or less constant from ~10 keV to ~100 keV, the rms of the flat-top noise first increases from 1 keV to ~8 keV then drops to less than 0.1% above ~30 keV. We suggest that the disappearance of the broadband variability above 30 keV could be caused by the non-thermal acceleration in the Comptonizing plasma. At the same time, the QPOs could be produced by the precession of either a small-scale jet or a hot inner flow model., To be published in The Astrophysical Journal

Black hole imaging challenges the 3rd generation space VLBI, the Very Long Baseline Interferometry, to operate on a 500 GHz band. The coherent integration time needed here is 450 s though the available space oscillators cannot offer more than 10 s. Self-calibration methods might solve this issue in an interferometer formed by 3 antenna/satellite systems, but the need for the 3rd satellite increases mission costs. A frequency transfer is of special interest to alleviate both performance and cost issues. A concept of 2-way optical frequency transfer is examined to investigate its suitability to enable space-to-space interferometry, in particular, to image the 'shadows' of black holes from space. The concept, promising on paper, has been demonstrated by tests. The laboratory test set-up is presented and the verification of the temporal stability using standard analysis tool as TimePod has been passed. The resulting Allan Deviation is dominated by the 1/$��$ phase noise trend since the frequency transfer timescale of interest is shorter than 0.2 s. This trend continues into longer integration times, as proven by the longest tests spanning over a few hours. The Allan Deviation between derived 103.2 GHz oscillators is $1.1\times10^{-14}/��$ within 10 ms < $��$ < 1,000 s that degrades twice towards the longest delay 0.2 s. The worst case satisfies the requirement with a margin of 11 times. The obtained coherence in the range of 0.997-0.9998 is beneficial for space VLBI at 557 GHz. The result is of special interest to future science missions for black hole imaging from space., 13 pages, 15 figures, published by JAI

Endometriosis is a chronic inflammatory gynecological disorder associated with pelvic pain symptoms and infertility. Ovarian cysts (endometriomas) are the most common localization of endometriosis in the pelvis. Considering non-invasive methods, transvaginal ultrasound has high sensitivity and specificity for endometrioma diagnosis. Laparoscopic removal of endometrioma is related to a damage to the ovarian reserve and should be limited to patients with suspicious cysts or unresponsive to medical treatment. The main goal of medical therapy of symptomatic endometrioma is the control of pain symptoms, while no benefits have been demonstrated in terms of improving fertility rates of women seeking pregnancy. The aim of medical treatment is the inhibition of ovulation, stop of menstruation and achievement of a stable hypo-hormonal milieu. Estroprogestins and progestins are indicated by guidelines as first line medications for symptomatic patients. Several hormonal treatments have been proposed for the treatment of symptomatic endometriomas. In particular, dienogest, a relatively new progestin, has shown promising results. Medical treatment should be conceived as a long-term treatment. Safety, tolerability, a low percentage of side effects and an easy route of administration are essential for patient acceptance and adherence to therapy.

We report the detection of an infrared burst lagging a thermonuclear Type I X-ray burst from the accreting neutron star 4U 1728-34 (GX 354-0). Observations were performed simultaneously with XMM-Newton (0.7-12 keV), NuSTAR (3-79 keV) and HAWK-I@VLT (2.2$��$m). We measure a lag of $4.75 \pm 0.5$ s between the peaks of the emission in the two bands. Due to the length of the lag and the shape of the IR burst, we found that the most plausible cause for such a large delay is reprocessing of the Type I burst X-rays by the companion star. The inferred distance between the neutron star and the companion can be used to constrain the orbital period of the system, which we find to be larger than $\sim$ 66 minutes (or even $\gtrsim$ 2 hours, for a realistic inclination $< 75^\circ$). This is much larger than the current tentatively estimated period of $\sim 11$ minutes. We discuss the physical implications on the nature of the binary and conclude that most likely the companion of 4U 1728-34 is a helium star., Accepted for publication in MNRAS Letters. 6 Pages, 4 Figures

We report on the first NuSTAR observation of the transitional millisecond pulsar binary XSS J12270-4859 during its current rotation-powered state, complemented with a 2.5 yr-long radio monitoring at Parkes telescope and archival XMM-Newton and Swift X-ray and optical data. The radio pulsar is mainly detected at 1.4 GHz displaying eclipses over ∼ 40 per cent of the 6.91 h orbital cycle. We derive a new updated radio ephemeris to study the 3- 79 keV light curve that displays a significant orbital modulation with fractional amplitude of 28 ± 3 per cent, a structured maximum centred at the inferior conjunction of the pulsar and no cycle-to-cycle or low-high-flaring mode variabilities. The average X-ray spectrum, extending up to ∼70 keV without a spectral break, is well described by a simple power law with photon index γ = 1.17 ± 0.08 giving a 3-79 keV luminosity of 7.6+3.8 -0.8 × 1032 erg s-1 for a distance of 1.37+0.69 -0.15 kpc. Energy resolved orbital light curves reveal that the modulation is not energy dependent from 3 to 25 keV and is undetected with an upper limit of ∼10 per cent above 25 keV. Comparison with previous X-ray XMM-Newton observations in common energy ranges confirms that themodulation amplitudes vary on time-scales of a fewmonths, indicative of a non-stationary contribution of the intrabinary shock (IBS) formed by the colliding winds of the pulsar and the companion. A more detailed inspection of energy resolved modulations than previously reported gives hints of a mild softening at superior conjunction of the pulsar below 3 keV, likely due to the contribution of the thermal emission from the neutron star. The IBS emission, if extending into the MeV range, would be energetically capable alone to irradiate the donor star., DdM, AP, and TMB acknowledge financial support from the Italian Space Agency (ASI) and National Institute for Astrophysics (INAF) under agreements ASI-INAF I/037/12/0 and ASI-INAF n.2017-14-H.0 and from INAF ‘Sostegno alla ricerca scientifica main streams dell’INAF’, Presidential Decree 43/2018. DdM, AP, MB, and AP also acknowledge support from INAF ‘SKA/CTA projects’, Presidential Decree 70/2016. DFT acknowledges support from the Spanish Ministry of Economy, Industry and Competitiveness grants PGC2018-095512-B-I00, SGR2017-1383, and AYA2017-92402-EXP. FCZ is supported by a Juan de la Cierva fellowship and grants from the Spanish Ministry of Economy, Industry and Comeptitiveness grants SGR2017-1383 and PGC2018-095512-B-I00. We also thank the ‘PHAROS’ COST Action (CA16214) for partial support.

GRO J1744-28, commonly known as the `Bursting Pulsar', is a low mass X-ray binary containing a neutron star and an evolved giant star. This system, together with the Rapid Burster (MXB 1730-33), are the only two systems that display the so-called Type II X-ray bursts. These type of bursts, which last for 10s of seconds, are thought to be caused by viscous instabilities in the disk; however the Type II bursts seen in GRO J1744-28 are qualitatively very different from those seen in the archetypal Type II bursting source the Rapid Burster. To understand these differences and to create a framework for future study, we perform a study of all X-ray observations of all 3 known outbursts of the Bursting Pulsar which contained Type II bursts, including a population study of all Type II X-ray bursts seen by RXTE. We find that the bursts from this source are best described in four distinct phenomena or `classes' and that the characteristics of the bursts evolve in a predictable way. We compare our results with what is known for the Rapid Burster and put out results in the context of models that try to explain this phenomena., Accepted to MNRAS Aug 17 2018

We performed an analysis of all RXTE observations of the Low Mass X-ray Binary and Black Hole Candidate IGR J17091-3624 during the 2011-2013 outburst of the source. By creating lightcurves, hardness-intensity diagrams and power density spectra of each observation, we have created a set of 9 variability `classes' that phenomenologically describe the range of types of variability seen in this object. We compare our set of variability classes to those established by Belloni et al. (2000) to describe the similar behaviour of the LMXB GRS 1915+105, finding that some types of variability seen in IGR J17091-3624 are not represented in data of GRS 1915+105. We also use all available X-ray data of the 2011-2013 outburst of IGR J17091-3624 to analyse its long-term evolution, presenting the first detection of IGR J17091-3624 above 150 keV as well as noting the presence of `re-flares' during the latter stages of the outburst. Using our results we place new constraints on the mass and distance of the object, and find that it accretes at, 26 Pages, 31 Figures, 8 Tables. Accepted to MNRAS

Sabbioneta is a small town situated in the province of Mantova, in northern Italy. Founded by Vespasiano Gonzaga Colonna in the XVI century, it constituted the capital of the Sabbioneta Ducat. His specific historical background and renaissance urban fabric made it enter into the UNESCO’s World Heritage list in 2008. Other than the economic and political consequences of this event, it shows the architectural importance of Sabbioneta and its great potential for future developments. Palazzo Ducale (Figure 1) was one of the first constructions of the new town. Acting as a ducal residence in its beginnings, its function has evolved over time until the current situation: an exposition space.

Leonardo S.p.A. in collaboration with INRIM is developing an industrial version of the Rb-POP for space addressing future GNSS satellite constellations in the frame of ESA General Support Technology Program (GSTP). We present the advancement status of the first phase of the program consisting in the development of the clock Physics Package (PP) subsystem.

We studied time variability and spectral evolution of the Galactic black hole transient Swift J174510.8-262411 during the first phase of its outburst. INTEGRAL and Swift observations collected from 2012 September 16 until October 30 have been used. The total squared fractional rms values did not drop below 5% and QPOs, when present, were type-C, indicating that the source never made the transition to the soft-intermediate state. Even though the source was very bright (up to 1 Crab in hard X-rays), it showed a so called failed outburst as it never reached the soft state. XRT and IBIS broad band spectra, well represented by a hybrid thermal/non-thermalComptonisationmodel, showed physical parameters characteristic of the hard and intermediate states. In particular, the derived temperature of the geometrically thin disc black body was about 0.6 keV at maximum.We found a clear decline of the optical depth of the corona electrons (close to values of 0.1), as well as of the total compactness ratio lh/ls. The hard-to-hard/intermediate state spectral transition is mainly driven by the increase in the soft photon flux in the corona, rather than small variations of the electron heating. This, associated with the increasing of the disc temperature, is consistent with a disc moving towards the compact object scenario, i.e. the truncated-disc model. Moreover, this scenario is consistent with the decreasing fractional squared rms and increasing of the noise and QPO frequency. In our final group of observations, we found that the contribution from the non-thermal Comptonisation to the total power supplied to the plasma is 0.59+0.02/-0.05 and that the thermal electrons cool to kTe, Accepted for publication in Monthly Notices of the Royal Astronomical Society; 12 pages, 8 figures, 5 tables

We present the spectral and timing analysis of X-ray observations performed on the Galactic black hole transient GRS 1716-249 during the 2016-2017 outburst. The source was almost continuously observed with the Neil Gehrels Swift Observatory from December 2016 until October 2017. The X-ray hardness ratio and timing evolution indicate that the source approached the soft state three times during the outburst, even though it never reached the canonical soft spectral state. Thus, GRS 1716-249 increases the number of black hole transients showing outbursts with "failed" state transition. During the softening events, XRT and BAT broadband spectral modeling, performed with thermal Comptonization plus a multicolor disc black-body, showed a photon index (Gamma < 2) and an inner disc temperature (kTin = 0.2-0.5 keV) characteristic of the hard intermediate state. This is in agreement with the root mean square amplitude of the flux variability (rms > 10%). We find that, coherently with a scenario in which the disc moves closer to the compact object, the accretion disc inner radius decreases with the increase of the inner disc temperature, until a certain point when the temperature starts to increase at constant radius. This, in addition with the spectral analysis results, suggests that either the accretion disc reached the innermost stable circular orbit during the hard intermediate state or the hot accretion flow might re-condensate in an inner mini-disc. We report on the radio observations performed during the outburst finding that GRS 1716-249 is located on the radio-quiet "outlier" branch of the radio/X-ray luminosity plane., 18 pages, 7 figures, accepted in MNRAS

We present a detailed analysis of the X-ray/IR fast variability of the Black-Hole Transient GX 339-4 during its low/hard state in August 2008. Thanks to simultaneous high time-resolution observations made with the VLT and RXTE, we performed the first characterisation of the sub-second variability in the near-infrared band - and of its correlation with the X-rays - for a low-mass X-ray binary, using both time and frequency-domain techniques. We found a power-law correlation between the X-ray and infrared fluxes when measured on timescales of 16 seconds, with a marginally variable slope, steeper than the one found on timescales of days at similar flux levels. We suggest the variable slope - if confirmed - could be due to the infrared flux being a non-constant combination of both optically thin and optically thick synchrotron emission from the jet, as a result of a variable self-absorption break. From cross spectral analysis we found an approximately constant infrared time lag of $\approx$ 0.1s, and a very high coherence of $\approx$ 90 per cent on timescales of tens of seconds, slowly decreasing toward higher frequencies. Finally, we report on the first detection of a linear rms-flux relation in the emission from a low-mass X-ray binary jet, on timescales where little correlation is found between the X-rays and the jet emission itself. This suggests that either the inflow variations and jet IR emission are coupled by a non-linear or time-variable transform, or that the IR rms-flux relation is not transferred from the inflow to the jet, but is an intrinsic property of emission processes in the jet., 11 pages, 8 figures. Accepted for publication in MNRAS

We present the status of the industrialization activity of a Rubidium POP (Pulsed Optically Pumped) clock Physics Package (PP) designed to meet the harsh space environment and more than 12 years of life-time. Leonardo completed the design phase including thermal, mechanical and magnetic analyses. PP manufacturing started at the beginning of 2018. The vibration test on the full microwave cavity assembly prototype including the Rb cell is foreseen by the first half of the year. The target for the Rb POP industrialization activity is to achieve a space qualification of the full clock by 2020 and the readiness for experimental flight by 2022.

We present the first detection of X-ray coherent pulsations from the transitional millisecond pulsar XSS J12270-4859, while it was in a sub-luminous accretion disk state characterized by a 0.5-10 keV luminosity of 5E33 erg/s (assuming a distance of 1.4 kpc). Pulsations were observed by XMM-Newton at an rms amplitude of (7.7 +/- 0.5)% with a second harmonic stronger than the the fundamental frequency, and were detected when the source is neither flaring nor dipping. The most likely interpretation of this detection is that matter from the accretion disk was channelled by the neutron star magnetosphere and accreted onto its polar caps. According to standard disk accretion theory, for pulsations to be observed the mass in-flow rate in the disk was likely larger than the amount of plasma actually reaching the neutron star surface; an outflow launched by the fast rotating magnetosphere then probably took place, in agreement with the observed broad-band spectral energy distribution. We also report about the non-detection of X-ray pulsations during a recent observation performed while the source behaved as a rotationally-powered radio pulsar., Accepted for publication in MNRAS Letters. 5 pages, including 3 figures and 1 table. Corrected a typo in the uncertainty affecting the spin frequency

We present 3-79 keV NuSTAR observations of the neutron star low-mass X-ray binary 4U 1636-53 in the soft, transitional and hard state. The spectra display a broad emission line at 5-10 keV. We applied several models to fit this line: A GAUSSIAN line, a relativistically broadened emission line model, KYRLINE, and two models including relativistically smeared and ionized reflection off the accretion disc with different coronal heights, RELXILL and RELXILLLP. All models fit the spectra well, however, the KYRLINE and RELXILL models yield an inclination of the accretion disc of $\sim88\degree$ with respect to the line of sight, which is at odds with the fact that this source shows no dips or eclipses. The RELXILLLP model, on the other hand, gives a reasonable inclination of $\sim56\degree$. We discuss our results for these models in this source and the possible primary source of the hard X-rays., 9 pages, 8 figures

X-ray binary observations led to the interpretation that powerful compact jets, produced in the hard state, are quenched when the source transitions to its soft state. The aim of this paper is to discuss the possibility that a powerful dark jet is still present in the soft state. Using the black hole X-ray binaries GX339-4 and H1743-322 as test cases, we feed observed X-ray power density spectra in the soft state of these two sources to an internal shock jet model. Remarkably, the predicted radio emission is consistent with current upper-limits. Our results show that, for these two sources, a compact dark jet could persist in the soft state with no major modification of its kinetic power compared to the hard state., Comment: 7 pages, 3 figures, 1 table, accepted for publication in MNRAS

Fil: Carballo, Ignacio Esteban. Pontificia Universidad Católica Argentina; Argentina Fil: Carballo, Ignacio Esteban. Universidad de Buenos Aires. Facultad de Ciencias Económicas. Centro de Estudios de la Estructura Económica; Argentina Fil: Belloni, Carlos M. Universidad de Buenos Aires; Argentina Fil: Belloni, Carlos M. Universidad Austral. IAE Business School. Departamento de Economía; Argentina Fil: López Amorós, Martín. Universidad de Buenos Aires; Argentina Fil: López Amorós, Martín. Universidad Argentina de la Empresa; Argentina Fil: López Amorós, Martín. Universidad Nacional de Tierra del Fuego; Argentina Fil: López Amorós, Martín. Universidad Nacional de Tres de Febrero; Argentina Fil: Fracchia, Eduardo. Universidad Austral. IAE Business School. Área de Economía; Argentina Resumen: En este trabajo nos proponemos abordar la temática del emprendedorismo y su relación con las políticas públicas. Para ello, realizamos una revisión introductoria de la literatura partiendo de los principales conceptos que definen el emprendedorismo y las distintas concepciones del emprendedor. Concluimos el trabajo afirmando que los canales que determinan la actividad emprendedora y su relación causal con el desarrollo económico son extensos, generando arduos debates en torno a la efectividad y prácticas adecuadas de las políticas públicas. Es necesario impulsar políticas que comprometan de manera sostenible esfuerzos de los sectores públicos y privados para mantener vigorosos los procesos de emprendedorismo. Abstract: In this paper we study entrepreneurship and its relation to public policy through an introductory review of the literature on the main concepts of entrepreneurship and the different conceptions of the entrepreneur. We conclude the paper stating that the channels that determine entrepreneurship and its causal relationship with economic velopment are extensive, generating intense debate about the effectiveness and appropriate practices of public policies therein. In this regard we advocate for the promotion of public policies involving sustainable efforts in both public and private sectors to foster strong entrepreneurship processes.

In September 2016, the microquasar Cygnus X-3 underwent a giant radio flare, which was monitored for 6 days with the Medicina Radio Astronomical Station and the Sardinia Radio Telescope. Long observations were performed in order to follow the evolution of the flare on a hourly scale, covering six frequency ranges from 1.5 GHz to 25.6 GHz. The radio emission reached a maximum of 13.2 +/- 0.7 Jy at 7.2 GHz and 10 +/- 1 Jy at 18.6 GHz. Rapid flux variations were observed at high radio frequencies at the peak of the flare, together with rapid evolution of the spectral index: alpha steepened from 0.3 to 0.6 within 5 hours. This is the first time that such fast variations are observed, giving support to the evolution from optically thick to optically thin plasmons in expansion moving outward from the core. Based on the Italian network (Noto, Medicina and SRT) and extended to the European antennas (Torun, Yebes, Onsala), VLBI observations were triggered at 22 GHz on five different occasions, four times prior to the giant flare, and once during its decay phase. Flux variations of 2-hour duration were recorded during the first session. They correspond to a mini-flare that occurred close to the core ten days before the onset of the giant flare. From the latest VLBI observation we infer that four days after the flare peak the jet emission was extended over 30 mas., Comment: 13 pages, 9 figures. Accepted for publication in MNRAS

We have systematically studied a large sample of the neutron star low mass X-ray binaries (LMXBs) monitored by the Rossi X-ray Timing Explorer (50 sources; 10000+ observations). We find that the hysteresis patterns between Compton dominated and thermal dominated states, typically observed in black hole LMXBs, are also common in neutron star systems. These patterns, which also sample intermediate states, are found when looking at the evolution of both X-ray colour and fast variability of ten systems accreting below ~ 30 % of the Eddington Luminosity. We show that hysteresis does not require large changes in luminosity and it is the natural form that state transitions take at these luminosities. At higher accretion rates neutron stars do not show hysteresis, and they remain in a thermal dominated, low variability state, characterized by flaring behaviour and fast colour changes. Only at luminosities close to the Eddington Luminosity, are high variability levels seen again, in correspondence to an increase in the fractional contribution of the Comptonization component. We compare this behaviour with that observed in LMXBs harbouring black holes, showing that the spectral, timing and multi-wavelength properties of a given source can be determined by its location in the fast variability-luminosity diagram, which, therefore, provides a common framework for neutron star and black hole accretion states., Comment: Accepted for publication in MNRAS

Ultra-Luminous X-ray sources are thought to be accreting black holes that might host Intermediate Mass Black Holes (IMBH), proposed to exist by theoretical studies, even though a firm detection (as a class) is still missing. The brightest ULX in M82 (M82 X-1) is probably one of the best candidates to host an IMBH. In this work we analyzed the data of the recent release of observations obtained from M82 X-1 taken by XMM-Newton. We performed a study of the timing and spectral properties of the source. We report on the detection of (46+-2) mHz Quasi-Periodic Oscillations (QPOs) in the power density spectra of two observations. A comparison of the frequency of these high-frequency QPOs with previous detections supports the 1:2:3 frequency distribution as suggested in other studies. We discuss the implications if the (46+-2) mHz QPO detected in M82 X-1 is the fundamental harmonic, in analogy with the High-Frequency QPOs observed in black hole binaries. For one of the observations we have detected for the first time a QPO at 8 mHz (albeit at a low significance), that coincides with a hardening of the spectrum. We suggest that the QPO is a milli-hertz QPO originating from the close-by transient ULX M82 X-2, with analogies to the Low-Frequency QPOs observed in black hole binaries., 9 pages (with 4 figures and 4 tables). Accepted for publication in MNRAS (26/09/13)

The notion of source states characterizing the X-ray emission from black hole binaries has revealed to be a very useful tool to disentangle the complex spectral and aperiodic phenomenology displayed by those classes of accreting objects. We seek to use the same tools for Ultra-Luminous X-ray (ULX) sources. We analyzed the data from the longest observations obtained from the ULX source in NGC 5408 (NGC 5408 X-1) taken by XMM-Newton. We performed a study of the timing and spectral properties of the source. In accordance with previous studies on similar sources, the intrinsic energy spectra of the source are well described by a cold accretion disc emission plus a curved high-energy emission component. We studied the broad-band noise variability of the source and found an anti-correlation between the root mean square variability in the 0.0001-0.2Hz and intensity, similarly to what is observed in black-hole binaries during the hard states. We discuss the physical processes responsible for the X-ray features observed and suggest that NGC 5408 X-1 harbors a black hole accreting in an unusual bright hard-intermediate state., Comment: 12 pages, including 6 figures and 3 tables. Accepted for publication in MNRAS (06/08/13)

Quasi-periodic oscillations (QPOs) with frequencies from $\sim0.05$-$30$ Hz are a common feature in the X-ray emission of accreting black hole binaries. As the QPOs originate from the innermost accretion flow, they provide the opportunity to probe the behaviour of matter in extreme gravity. In this paper, we present a systematic analysis of the inclination dependence of phase lags associated with both Type-B and Type-C QPOs in a sample of 15 Galactic black hole binaries. We find that the phase lag at the Type-C QPO frequency strongly depends on inclination, both in evolution with QPO frequency and sign. Although we find that the Type-B QPO soft lags are associated with high inclination sources, the source sample is too small to confirm this as a significant inclination dependence. These results are consistent with a geometrical origin of Type-C QPOs and a different origin for Type-B and Type-C QPOs. We discuss the possibility that the phase lags originate from a pivoting spectral power law during each QPO cycle, while the inclination dependence arises from differences in dominant relativistic effects. We also search for energy dependences in the Type-C QPO frequency. We confirm this effect in the three known sources (GRS 1915+105, H1743-322 and XTE J1550-564) and newly detect it in XTE J1859+226. Lastly, our results indicate that the unknown inclination sources XTE J1859+226 and MAXI J1543-564 are most consistent with a high inclination., 16 pages, 10 figures; accepted for publication in MNRAS

Highlights • Levonorgestrel IUD was effective in treatment of recurrent APA. • No side effects were reported. • No impairments on a subsequent pregnancy were reported.

We present optical monitoring of the black hole candidate XTE J1752-223 during its 2009 - 2010 outburst and decay to quiescence. The optical light curve can be described by an exponential decay followed by a plateau, then a more rapid fade towards quiescence. The plateau appears to be due to an extra component of optical emission that brightens and then fades over ~ 40 days. We show evidence for the origin of this optical 'flare' to be the synchrotron jet during the decaying hard state, and we identify and isolate both disc and jet components in the spectral energy distributions. The optical flare has the same morphology and amplitude as a contemporaneous X-ray rebrightening. This suggests a common origin, but no firm conclusions can be made favouring or disfavouring the jet producing the X-ray flare. The quiescent optical magnitudes are B >= 20.6, V >= 21.1, R >= 19.5, i' >= 19.2. From the optical outburst amplitude we estimate a likely orbital period of < 22 h. We also present near-infrared (NIR) photometry and polarimetry and rare mid-infrared imaging (8 - 12 microns) when the source is nearing quiescence. The fading jet component, and possibly the companion star may contribute to the NIR flux. We derive deep mid-IR flux upper limits and NIR linear polarization upper limits. With the inclusion of radio data, we measure an almost flat jet spectral index between radio and optical; F_nu ~ nu^(~ +0.05). The data favour the jet break to optically thin emission to reside in the infrared, but may shift to frequencies as high as the optical or UV during the peak of the flare.

We present a study of the spectral properties during the state transition of GX 339−4. Data are taken from the 2010 outburst of GX 339−4, which is densely covered by Rossi X-ray Timing Explorer, providing an excellent coverage of the state transitions between the low/hard state and the high/soft state. We select all observations within a certain hardness ratio range during the soft intermediate state (SIMS). This sample was chosen in such a way to comprise all observations that show a type-B quasi-periodic oscillation (QPO). In addition, we also investigate the spectra of hard intermediate state observations. The spectra, obtained from Proportional Counter Array data in the 10–40 keV range, are fitted with a power law and an additional high-energy cut-off, if needed. We find that the spectra are significantly harder during the SIMS of the soft-to-hard transition than they are during the hard-to-soft transition. This demonstrates that during the SIMS of the soft-to-hard transition not only the luminosity and peak frequencies of type-B QPOs are lower, but also that the photon index is lower, compared to the hard-to-soft transition. Hence, type-B QPOs can be associated with a different spectral shape, even though they appear at the same hardness. However, in each branch only certain combinations of centroid frequency and photon index are realized.