Search

We report the discovery of millihertz quasi-periodic oscillations (mHz QPOs) from the neutron star (NS) low-mass X-ray binary 4U 1730--22 using the Neutron Star Interior Composition Explorer (NICER). After being inactive for almost 50 years, 4U 1730--22 went into outburst twice between June and August 2021, and between February and July 2022. We analyse all the NICER observations of this source, and detect mHz QPOs with a significance > $4\sigma$ in 35 observations. The QPO frequency of the full data set ranged between ~4.5 and ~8.1 mHz with an average fractional rms amplitude of the order of ~2%. The X-ray colour analysis strongly suggests that 4U 1730--22 was in a soft spectral state during the QPO detections. Our findings are consistent with those reported for other sources where the mHz QPOs have been interpreted as the result of a special mode of He burning on the NS surface called marginally stable nuclear burning (MSNB). We conclude that the mHz QPOs reported in this work are also associated with the MSNB, making 4U 1730--22 the eighth source that shows this phenomenology. We discuss our findings in the context of the heat flux from the NS crust., Comment: 9 pages, 6 figures. Accepted for publication in MNRAS

The neutron star low-mass X-ray binary SWIFT J1749.4–2807 is the only known eclipsing accreting millisecond X-ray pulsar. In this manuscript, we perform a spectral characterization of the system throughout its 2021, 2-week-long outburst, analysing 11 NICER observations and quasi-simultaneous XMM-Newton and NuSTAR single observations at the outburst peak. The broad-band spectrum is well-modelled with a blackbody component with a temperature of ∼0.6 keV, most likely consistent with a hotspot on the neutron star surface, and a Comptonization spectrum with power-law index Γ ∼ 1.9, arising from a hot corona at ∼12 keV. No direct emission from the disc was found, possibly due to it being too cool. A high truncation radius for the disc, i.e. at ∼20–30 RG, was obtained from the analysis of the broadened profile of the Fe line in the reflection component. The significant detection of a blue-shifted Fe XXVI absorption line at ∼7 keV indicates weakly relativistic X-ray disc winds, which are typically absent in the hard state of X-ray binaries. By comparing the low flux observed during the outburst and the one expected in a conservative mass-transfer, we conclude that mass-transfer in the system is highly non-conservative, as also suggested by the wind detection. Finally, using the NICER spectra alone, we followed the system while it was fading to quiescence. During the outburst decay, as the spectral shape hardened, the hotspot on the neutron star surface cooled down and shrank, a trend which could be consistent with the pure power-law spectrum observed during quiescence., AM acknowledges a financial contribution from the agreement ASI-INAF n.2017-14-H.0 and the INAF mainstream grant (PI: T. Belloni, A. De Rosa). AM, TDS, AA, and RI acknowledge financial contribution from the HERMES project financed by the Italian Space Agency (ASI) Agreement n.2016/13 U.O. AM is supported by the H2020 ERC Consolidator Grant ‘MAGNESIA’ under grant agreement No. 817661 (PI: Rea) and National Spanish grant PGC2018-095512-BI00. This work was also partially supported by the program Unidad de Excelencia Maria de Maeztu CEX2020-001058-M and the PHAROS COST Action (No. CA16214). PB acknowledges support from the CRESST II cooperative agreement (80GSFC21M0002). SG acknowledges the support of the Centre National d’Etudes Spatiales (CNES). GCM was partially supported by Proyecto de Investigación Plurianual (PIP) 0102 (Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)) and PICT-2017-2865 (Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT)). DA acknowledges support from the Royal Society.

We present results from quasi-simultaneous multiwavelength observations of the Galactic black hole X-ray transient MAXI J1820$+$070 during the decay of the 2018 outburst and its entire subsequent mini-outburst in March 2019. We fit the X-ray spectra with phenomenological and Comptonizaton models and discuss the X-ray spectral evolution comparing with the multiwavelength behaviour of the system. The system showed a rebrightening in UV/Optical/NIR bands 7-days after the soft-to-hard transition during the main outburst decay while it was fading in X-rays and radio. In contrast, the mini-outburst occurred 165-days after the hard state transition of the initial outburst decay and was detected in all wavelengths. For both events, the measured timescales are consistent with those observed in other black hole systems. Contemporaneous hard X-ray/soft $\gamma$-ray observations indicate a non-thermal electron energy distribution at the beginning of the UV/Optical/NIR rebrightening, whereas a thermal distribution can fit the data during the hard mini-outburst activity. The broadband spectral energy distributions until the rebrightening are consistent with the irradiated outer accretion disc model. However, both the SEDs produced for the peak of rebrightening and close to the peak of mini-outburst provided good fits only with an additional power-law component in the UV/Optical/NIR frequency ranges which is often interpreted with a jet origin., Comment: 15 pages, 6 figures, 8 tables. Accepted for publication in MNRAS

The detection of coherent X-ray pulsations at ~314 Hz (3.2 ms) classifies MAXI J1957+032 as a fast-rotating, accreting neutron star. We present the temporal and spectral analysis performed using NICER observations collected during the latest outburst of the source. Doppler modulation of the X-ray pulsation revealed the ultra-compact nature of the binary system characterised by an orbital period of ~1 hour and a projected semi-major axis of 14 lt-ms. The neutron star binary mass function suggests a minimum donor mass of 1.7e-2 Msun, assuming a neutron star mass of 1.4 Msun and a binary inclination angle lower than 60 degrees. This assumption is supported by the lack of eclipses or dips in the X-ray light curve of the source. We characterised the 0.5-10 keV energy spectrum of the source in outburst as the superposition of a relatively cold black-body-like thermal emission compatible with the emission from the neutron star surface and a Comptonisation component with photon index consistent with a typical hard state. We did not find evidence for iron K-alpha lines or reflection components., 5 pages, 4 figures. Accepted for publication in MNRAS

All disc-accreting astrophysical objects produce powerful outflows. In binaries containing neutron stars (NS) or black holes, accretion often takes place during violent outbursts. The main disc wind signatures during these eruptions are blue-shifted X-ray absorption lines, which are preferentially seen in disc-dominated "soft states". By contrast,optical wind-formed lines have recently been detected in "hard states", when a hot corona dominates the luminosity. The relationship between these signatures is unknown, and no erupting system has revealed wind-formed lines between the X-ray and optical bands yet, despite the many strong resonance transitions in this ultraviolet (UV) region. Here, we show that the transient NS binary Swift J1858.6-0814 exhibits wind-formed, blue-shifted absorption associated with C IV, N V and He II in time-resolved UV spectroscopy during a luminous hard state. This represents the first evidence for a warm, moderately ionized outflow component in this state. Simultaneously observed optical lines also display transient blue-shifted absorption. Decomposing the UV data into constant and variable components, the blue-shifted absorption is associated with the former. This implies that the outflow is not connect to the luminous flares in the data. The joint presence of UV and optical wind features reveals a multi-phase and/or stratified outflow from the outer disc. This type of persistent mass loss across all accretion states has been predicted by radiation-hydrodynamic simulations and helps to explain the shorter-than-expected outbursts duration., Comment: Published in Nature. Submitted: 9 July 2021

The radiative counterpart of the supermassive black hole at the Galactic Centre, Sagittarius A*, displays flaring emission in the X-ray band atop a steady, quiescent level. Flares are also observed in the near-infrared band. The physical process producing the flares is not fully understood and it is unclear if the flaring rate varies, although some recent works suggest it has reached unprecedented variability in recent years. Using over a decade of regular X-ray monitoring of Neil Gehrels Swift Observatory, we studied the variations in count rate of Sgr A* on time scales of years. We decomposed the X-ray emission into quiescent and flaring emission, modelled as a constant and power law process, respectively. We found that the complete, multi-year dataset cannot be described by a stationary distribution of flare fluxes, while individual years follow this model better. In three of the ten studied years, the data is consistent with a purely Poissonian quiescent distribution, while for five years only an upper limit of the flare flux distribution parameter could be determined. We find that these possible changes cannot be explained fully by the different number of observations per year. Combined, these results are instead consistent with a changing flaring rate of Sgr A*, appearing more active between 2006-2007 and 2017-2019, than between 2008-2012. Finally, we discuss this result in the context of flare models and the passing of gaseous objects, and discuss the extra statistical steps taken, for instance to deal with the background in the Swift observations., 14 pages, 10 figures, Accepted for publication in MNRAS

Tracking the motions of transient jets launched by low-mass X-ray binaries (LMXBs) is critical for determining the moment of jet ejection, and identifying any corresponding signatures in the accretion flow. However, these jets are often highly variable and can travel across the resolution element of an image within a single observation, violating a fundamental assumption of aperture synthesis. We present a novel approach in which we directly fit a single time-dependent model to the full set of interferometer visibilities, where we explicitly parameterise the motion and flux density variability of the emission components, to minimise the number of free parameters in the fit, while leveraging information from the full observation. This technique allows us to detect and characterize faint, fast-moving sources, for which the standard time binning technique is inadequate. We validate our technique with synthetic observations, before applying it to three Very Long Baseline Array (VLBA) observations of the black hole candidate LMXB MAXI J1803-298 during its 2021 outburst. We measured the proper motion of a discrete jet component to be $1.37\pm0.14$ mas/hr, and thus we infer an ejection date of MJD $59348.08_{-0.06}^{+0.05}$, which occurs just after the peak of a radio flare observed by the Australia Telescope Compact Array (ATCA) and the Atacama Large Millimeter/Sub-Millimeter Array (ALMA), while MAXI J1803-298 was in the intermediate state. Further development of these new VLBI analysis techniques will lead to more precise measurements of jet ejection dates, which, combined with dense, simultaneous multi-wavelength monitoring, will allow for clearer identification of jet ejection signatures in the accretion flow., 15 pages, 9 figures, 4 tables; Accepted for publication in MNRAS

Fast transitions between different types of power density spectra (PDS) happening over time-scales of several tens of seconds are rare phenomena in black hole X-ray binaries. In this paper, we report a broad-band spectral-timing analysis of the fast transitions observed in the 2021 outburst of GX 339−4 using NICER and Insight-HXMT observations. We observe transitions between band-limited noise-dominated PDS and type-B quasi-periodic oscillations (QPOs), and their rapid appearance or disappearance. We also make a detailed comparison between the fast transitions in GX 339−4 with those seen in MAXI J1820+070 and MAXI J1348−630. By comparing the spectra of the periods with and without type-B QPOs, we find that the spectral ratios above 10 keV are nearly constant or slightly decreasing, and the values are different between sources. Below 10 keV, the flux change of the Comptonization component is inversely proportional to the flux change of the thermal component, suggesting that the appearance of type-B QPOs is associated with a redistribution of the accretion power between the disc and the Comptonizing emission region. The spectral ratios between the periods with type-B QPO and those with broad-band noise are significantly different from that with type-B QPO and without type-B QPO, where the ratios (type-B QPO/broad-band noise) show a maximum at around 4 keV and then decrease gradually towards high energies. Finally, we discuss the possible change of the geometry of the inner accretion flow and/or jet during the transitions.

Accretion disks around compact objects are expected to enter an unstable phase at high luminosity. One instability may occur when the radiation pressure generated by accretion modifies the disk viscosity, resulting in the cyclic depletion and refilling of the inner disk on short timescales. Such a scenario, however, has only been quantitatively verified for a single stellar-mass black hole. Although there are hints of these cycles in a few isolated cases, their apparent absence in the variable emission of most bright accreting neutron stars and black holes has been a lingering puzzle. Here we report the presence of the same multiwavelength instability around an accreting neutron star. Moreover, we show that the variability across the electromagnetic spectrum-from radio to X-ray-of both black holes and neutron stars at high accretion rates can be explained consistently if the accretion disks are unstable, producing relativistic ejections during transitions that deplete or refill the inner disk. Such new association allows us to identify the main physical components responsible for the fast multiwavelength variability of highly accreting compact objects., Comment: Published in Nature. 26 pages, 10 figures. DOI: 10.1038/s41586-022-05648-3

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

When accreting X-ray pulsars (XRPs) undergo bright X-ray outbursts, their luminosity-dependent spectral and timing features can be analysed in detail. The XRP GRO J1750-27 recently underwent one of such episodes, during which it was observed with $NuSTAR$ and monitored with $NICER$. Such a data set is rarely available, as it samples the outburst over more than a month at a luminosity that is always exceeding ${\sim}5\times10^{37}\,$erg/s. This value is larger than the typical critical luminosity value, where a radiative shock is formed above the neutron star's surface. Our data analysis of the joint spectra returns a highly ($N_H\sim(5-8)\times10^{22}\,$cm$^{-2}$) absorbed spectrum showing a K$\alpha$ iron line, a soft blackbody component likely originating from the inner edge of the accretion disk, and confirms the discovery of one of the deepest cyclotron lines, at a centroid energy of ${\sim}44\,$keV corresponding to a magnetic field strength of $4.7\times10^{12}\,$G. This value is independently supported by the best-fit physical model for spectral formation in accreting XRPs which, in agreement with recent findings, favours a distance of $14$ kpc and also reflects a bulk-Comptonization dominated accretion flow. Contrary to theoretical expectations and observational evidence from other similar sources, the pulse profiles as observed by $NICER$ through the outburst raise, peak and decay remain remarkably steady. The $NICER$ spectrum, including the iron K$\alpha$ line best-fit parameters, also remain almost unchanged at all probed outburst stages, similar to the pulsed fraction behaviour. We argue that all these phenomena are linked and interpret them as resulting from a saturation effect of the accretion column's emission, which occurs in the high-luminosity regime., Comment: Accepted on A&A -- proof version

Context: Massive colliding-wind binaries (CWBs) can be non-thermal sources. The emission produced in their wind-collision region (WCR) encodes information of both the shocks properties and the relativistic electrons accelerated in them. The recently discovered system Apep, a unique massive system hosting two Wolf-Rayet stars, is the most powerful synchrotron radio emitter among the known CWBs, being an exciting candidate to investigate the non-thermal processes associated with stellar wind shocks. Aims: We intend to break the degeneracy between the relativistic particle population and the magnetic field strength in the WCR of Apep by probing its hard X-ray spectrum, where inverse-Compton (IC) emission is expected to dominate. Methods: We observe Apep with NuSTAR for 60 ks and combine this with a re-analysis of a deep archival XMM-Newton observation to better constrain the X-ray spectrum. We use a non-thermal emission model to derive physical parameters from the results. Results: We detect hard X-ray emission consistent with a power-law component. This is compatible with IC emission produced in the WCR for a magnetic field of 100-160 mG and a fraction of ~1.5e-4 of the total wind kinetic power being converted into relativistic electron acceleration. Conclusions: This is the first time that the non-thermal emission from a CWB is detected both in radio and high energies. This allows us to derive the most robust constraints of the particle acceleration efficiency and magnetic field intensity in a CWB so far, reducing the typical uncertainty of a few orders of magnitude to just within a factor of two. This constitutes an important step forward in our characterisation of the physical properties of CWBs., Comment: 12 pages, 6 figures, accepted for publication in A&A

We present the pulsar timing analysis of the accreting millisecond X-ray pulsar SWIFT J1749.4-2807 monitored by NICER and XMM-Newton during its latest outburst after almost eleven years of quiescence. From the coherent timing analysis of the pulse profiles, we updated the orbital ephemerides of the system. Large phase jumps of the fundamental frequency phase of the signal are visible during the outburst, consistent with what was observed during the previous outburst. Moreover, we report on the marginally significant evidence for non-zero eccentricity ($e\simeq 4\times 10^{-5}$) obtained independently from the analysis of both the 2021 and 2010 outbursts and we discuss possible compatible scenarios. Long-term orbital evolution of SWIFT J1749.4-2807 suggests a fast expansion of both the NS projected semi-major axis $(x)$, and the orbital period $(P_{\rm orb})$, at a rate of $\dot{x}\simeq 2.6\times 10^{-13}\,\text{lt-s}\,\text{s}^{-1}$ and $\dot{P}_{\rm orb}\simeq 4 \times 10^{-10}\,\text{s}\,\text{s}^{-1}$, respectively. SWIFT J1749.4-2807 is the only accreting millisecond X-ray pulsar, so far, from which the orbital period derivative has been directly measured from appreciable changes on the observed orbital period. Finally, no significant secular deceleration of the spin frequency of the compact object is detected, which allowed us to set a constraint on the magnetic field strength at the polar caps of $B_{PC}, 13 pages, 3 figures, 1 table. Accepted for publication in MNRAS

We present a catalogue of 362 million stellar parameters, distances, and extinctions derived from Gaia's early third data release (EDR3) cross-matched with the photometric catalogues of Pan-STARRS1, SkyMapper, 2MASS, and AllWISE. The higher precision of the Gaia EDR3 data, combined with the broad wavelength coverage of the additional photometric surveys and the new stellar-density priors of the {\tt StarHorse} code allow us to substantially improve the accuracy and precision over previous photo-astrometric stellar-parameter estimates. At magnitude $G=14\, (17)$, our typical precisions amount to 3% (15%) in distance, 0.13 mag (0.15 mag) in $V$-band extinction, and 140 K (180 K) in effective temperature. Our results are validated by comparisons with open clusters, as well as with asteroseismic and spectroscopic measurements, indicating systematic errors smaller than the nominal uncertainties for the vast majority of objects. We also provide distance- and extinction-corrected colour-magnitude diagrams, extinction maps, and extensive stellar density maps that reveal detailed substructures in the Milky Way and beyond. The new density maps now probe a much greater volume, extending to regions beyond the Galactic bar and to Local Group galaxies, with a larger total number density. We publish our results through an ADQL query interface ({\tt gaia.aip.de}) as well as via tables containing approximations of the full posterior distributions. Our multi-wavelength approach and the deep magnitude limit make our results useful also beyond the next Gaia release, DR3., Comment: A&A, accepted, 27 pages, 25 figures. Fig. 5 has changed with respect to v1 (post-processing bug corrected). For various options to access the data see https://data.aip.de/projects/starhorse2021.html

Introduction Cligosiban is an orally administered, centrally penetrant oxytocin receptor antagonist being developed to treat premature ejaculation (PE). Aim To determine the efficacy of 3 dose levels of cligosiban caplets to prolong intravaginal ejaculation latency time (IELT) and improve patient-reported outcomes in men with lifelong PE. Methods Patients recorded details of at least 4 sexual intercourse events during a 4-week run-in period, after which they underwent baseline assessments. Patients were eligible for the study if their stopwatch-assessed IELT was ≤1 minute in ≥75% of intercourse attempts and if they met other diagnostic criteria for lifelong PE. Eligible patients (target 220 evaluable) were randomized to double-blind cligosiban 400, 800, or 1200 mg or matching placebo caplets (to be taken 1 to 6 hours prior to sexual activity). Assessments were conducted at 2, 4, and 8 weeks. Main Outcome Measure Efficacy measures were comprised of IELT, self-rating of ejaculation control and ejaculation-related distress (recorded in an electronic diary after each intercourse attempt), premature ejaculation profile, Patient’s Global Impression of Severity, and the Clinical Global Impression of Change. Results There were no clinically or statistically significant differences between cligosiban (at any dose level) and placebo for the primary endpoint (change in geometric IELT) or any of the secondary endpoints. Cligosiban was well tolerated with a side-effect profile similar to placebo. Clinical Implications This Phase IIb study failed to demonstrate the potential for cligosiban, an oxytocin antagonist, to successfully treat symptoms of severe lifelong PE at doses up to 1200 mg. Strengths and Limitations This was a Phase IIb, randomized, double-blind, placebo-controlled study that was adequately powered but failed to detect a clinically meaningful or statistical difference in change in IELT between cligosiban at 3 dose levels and placebo. This is in contrast to a similarly designed proof-of-concept study where cligosiban was flexibly dosed at doses up to 800 mg and did demonstrate clinically meaningful and statistically significant changes in efficacy parameters. The reasons for this disparity are not known. Conclusions Cligosiban was well tolerated but failed to demonstrate efficacy for the treatment of men with lifelong PE at doses up to 1200 mg.

V341 Ara was recently recognised as one of the closest (d ~ 150 pc) and brightest (V~ 10) nova-like cataclysmic variables. This unique system is surrounded by a bright emission nebula, likely to be the remnant of a recent nova eruption. Embedded within this nebula is a prominent bow-shock, where the system's accretion disc wind runs into its own nova shell. In order to establish its fundamental properties, we present the first comprehensive multi-wavelength study of the system. Long-term photometry reveals quasi-periodic, super-orbital variations with a characteristic time-scale of 10-16 days and typical amplitude of ~1 mag. High-cadence photometry from TESS reveals for the first time both the orbital period and a "negative superhump" period. The latter is usually interpreted as the signature of a tilted accretion disc. We propose a recently developed disc instability model as a plausible explanation for the photometric behaviour. In our spectroscopic data, we clearly detect anti-phased absorption and emission line components. Their radial velocities suggest a high mass ratio, which in turn implies an unusually low white dwarf mass. We also constrain the wind mass-loss rate of the system from the spatially resolved [O iii] emission produced in the bow-shock; this can be used to test and calibrate accretion disc wind models. We suggest a possible association between V341 Ara and a "guest star" mentioned in Chinese historical records in AD1240. If this marks the date of the system's nova eruption, V341 Ara would be the oldest recovered nova of its class and an excellent laboratory for testing nova theory., Accepted in MNRAS

El objetivo de la presente investigación es la elaboración de un índice de competitividad para medir la eficiencia microeconómica de las MiPyMES. El Índice de Competitividad de las empresas manufactureras de Tehuacán fue de 71.56%, representando un nivel de competitividad semidesarrollada, se explica por la deficiente participación del Financiamiento, Tesorería e Inversión, en esta región de Tehuacán no se cuenta con créditos de riesgo para desarrollar inversiones en sus organizaciones. Por su parte, la Innovación y Tecnología no llegan a ser determinantes en la eficiencia de las empresas manufactureras. Resalta, por otra parte, que la importancia de los Recursos Humanos y la Administración Estratégica en estas empresas es muy relevante por los cursos de capacitación enfocados a sus diferentes puestos de trabajo incrementando la productividad, es decir, llegar a ser más eficientes. Estas empresas tendrán que atender las deficiencias para poder alcanzar el siguiente nivel de competitividad.

The geometry of the accretion flow around stellar-mass black holes can change on timescales of days to months

The SDR devices along with GNU Radio Software tool have taken the design of radio communications systems to a new level. This technology uses blocks-processing software that substitutes everything that is far implemented at the physical layer hardware. By designing a software radio system, this paper shows the implementation of a real time voice Tx and Rx using GNU Radio as Software, and some modulation schemes through USRP E110 and N210 devices.

The SDR devices along with GNU Radio Software tool have taken to a new level in designing radio communications systems. This technology uses blocks-processing software that substitutes everything that is far implemented at the physical layer hardware. By designing a software radio system, this paper presents the implementation of a real time voice Tx/Rx using an embedded GMSK modulation in USRP E110 devices, the system performance was evaluated from an cualitative and cuantitative viewpoint using Mean Opinion Score (MOS) and Modified Bark Spectral Distortion (MBSD) algorithm, another tests were also performed.

The predominance of retinal breaks in the superior temporal quadrant is well known. This predominance was found to be related to age and refraction (p > 0.001) with a predominance in the 10-11 and 12-1 o'clock section (if we consider the right eye). The H/T ratio (holes/tears for each case) is positive for patients under 40 years of age and becomes negative after 50 years.

We present preliminary results from the analysis of simultaneous multiwavelength observations of the black hole candidate Swift J1753.5-0127. The source is still continuing its outburst started in May 2005, never leaving the Low/Hard State. In the X-ray energy spectra we confirm evidence for a thermal component at a very low luminosity possibly extending close to but not at the innermost stable orbit. This is unusual for black hole candidates in the Low/Hard State. Furthermore, we confirm that its radio emission is significantly fainter than expected from the relation observed in other black hole candidates between the observed radio/X-ray fluxes., 4 pages, 1 figure; to be published in proceedings of "A Population Explosion: The Nature and Evolution of X-ray Binaries in Diverse Environments", 28 Oct. - 2 Nov. 2007, St. Petersburg Beach, FL (R.M. Bandyopadhyay, S. Wachter, D. Gelino, & C.R. Gelino, eds.)

Intermittent accreting millisecond X-ray pulsars are an exciting new type of sources. Their pulsations appear and disappear either on timescales of hundreds of seconds or on timescales of days. The study of these sources add new observational constraints to present models that explain the presence or not of pulsations in neutron star LMXBs. In this paper we present preliminary results on spectral and aperiodic variability studies of all intermittent AMSPs, with a particular focus on the comparison between pulsating and non pulsating periods., 4 pages, 2 figures; to appear in the proceedings of the workshop "A Decade of Accreting Millisecond X-ray Pulsars", Amsterdam, April 2008, eds. R. Wijnands et al. (AIP Conf. Proc.)

BACKGROUND The pressure lowering effect of Argon laser trabeculoplasty (ALT) has been well demonstrated in the past. Today some clinicians tend to avoid ALT perhaps because it has been used in erroneous indications. The aim of this study was to re-evaluate the usefulness of ALT and to define its indication in the treatment of glaucoma. PATIENTS AND METHODS A collective of 81 patients treated by ALT entered in a data bank between 1989 and 1991 were analysed retrospectively, focussing on: the percentage of patients requiring trabeculectomy (TE) after ALT, the mean time from ALT to TE, the stage of disease progression at which the decision for ALT was taken and the post-ALT evolution of ocular pressure (IOP), visual field and optic disc. RESULTS After a mean follow-up of 28 +/- 10.5 months a TE was performed in 25% of cases. It was found that in our clinical practice the decision for ALT tended to be taken at a rather late stage of disease. For the patients that did not need a TE, the mean decrease of IOP at the end of follow-up was 5.4 mm Hg and the analysis of glaucoma parameters showed that there was no significant worsening of disease. The disease progression in the group of patients that were operated was already significantly worse than the total collective before ATL was performed. CONCLUSIONS ALT is useful in the treatment of glaucoma, as long as it is not considered as an alternative to TE and as long as the patients benefit from a strict follow-up. Advanced cases should however be operated without delay.

Genital Chlamydia trachomatis infection is a sexually transmitted disease of special relevance because of its high frequency and severe complications. Sexually active adolescents are among the highest risk groups for this STD. As the infection is usually asymptomatic it is necessary to apply screening methods to determine its real prevalence. The enzyme immunoassay (EIA) in first catch urine seems to be a simple and practical method for this purpose in males. This investigation was designed to establish the prevalence of C trachomatis and Neisseria gonorrhoeae genital infection in a group of asymptomatic adolescent males in Santiago Chile using urine samples. (excerpt)