Multi-wavelength properties of IGR J05007-7047 (LXP 38.55) and identification as a Be X-ray binary pulsar in the LMC

We report on the results of a $\sim$40 d multi-wavelength monitoring of the Be X-ray binary system IGR J05007-7047 (LXP 38.55). During that period the system was monitored in the X-rays using the Swift telescope and in the optical with multiple instruments. When the X-ray luminosity exceeded $10^{36}$ erg/s we triggered an XMM-Newton ToO observation. Timing analysis of the photon events collected during the XMM-Newton observation reveals coherent X-ray pulsations with a period of 38.551(3) s (1 {\sigma}), making it the 17$^{th}$ known high-mass X-ray binary pulsar in the LMC. During the outburst, the X-ray spectrum is fitted best with a model composed of an absorbed power law ($\Gamma =0.63$) plus a high-temperature black-body (kT $\sim$ 2 keV) component. By analysing $\sim$12 yr of available OGLE optical data we derived a 30.776(5) d optical period, confirming the previously reported X-ray period of the system as its orbital period. During our X-ray monitoring the system showed limited optical variability while its IR flux varied in phase with the X-ray luminosity, which implies the presence of a disk-like component adding cooler light to the spectral energy distribution of the system.Comment: 11 pages, 11 figures, Accepted for publication in MNRA

RBF neural net based classifier for the AIRIX accelerator fault diagnosis

The AIRIX facility is a high current linear accelerator (2-3.5kA) used for flash-radiography at the CEA of Moronvilliers France. The general background of this study is the diagnosis and the predictive maintenance of AIRIX. We will present a tool for fault diagnosis and monitoring based on pattern recognition using artificial neural network. Parameters extracted from the signals recorded on each shot are used to define a vector to be classified. The principal component analysis permits us to select the most pertinent information and reduce the redundancy. A three layer Radial Basis Function (RBF) neural network is used to classify the states of the accelerator. We initialize the network by applying an unsupervised fuzzy technique to the training base. This allows us to determine the number of clusters and real classes, which define the number of cells on the hidden and output layers of the network. The weights between the hidden and the output layers, realising the non-convex union of the clusters, are determined by a least square method. Membership and ambiguity rejection enable the network to learn unknown failures, and to monitor accelerator operations to predict future failures. We will present the first results obtained on the injector.Comment: 3 pages, 4 figures, LINAC'2000 conferenc

Multi-wavelength observations of 3FGL J2039.6-5618: a candidate redback millisecond pulsar

We present multi-wavelength observations of the unassociated gamma-ray source 3FGL J2039.6-5618 detected by the Fermi Large Area Telescope. The source gamma-ray properties suggest that it is a pulsar, most likely a millisecond pulsar, for which neither radio nor $\gamma$-ray pulsations have been detected yet. We observed 3FGL J2039.6-5618 with XMM-Newton and discovered several candidate X-ray counterparts within/close to the gamma-ray error box. The brightest of these X-ray sources is variable with a period of 0.2245$\pm$0.0081 d. Its X-ray spectrum can be described by a power law with photon index $\Gamma_X =1.36\pm0.09$, and hydrogen column density $N_{\rm H} < 4 \times 10^{20}$ cm$^{-2}$, which gives an unabsorbed 0.3--10 keV X-ray flux of $1.02 \times 10^{-13}$ erg cm$^{-2}$ s$^{-1}$. Observations with the Gamma-Ray Burst Optical/Near-Infrared Detector (GROND) discovered an optical counterpart to this X-ray source, with a time-average magnitude $g'\sim 19.5$. The counterpart features a flux modulation with a period of 0.22748$\pm$0.00043 d that coincides, within the errors, with that of the X-ray source, confirming the association based on the positional coincidence. We interpret the observed X-ray/optical periodicity as the orbital period of a close binary system where one of the two members is a neutron star. The light curve profile of the companion star, with two asymmetric peaks, suggests that the optical emission comes from two regions at different temperatures on its tidally-distorted surface. Based upon its X-ray and optical properties, we consider this source as the most likely X-ray counterpart to 3FGL J2039.6-5618, which we propose to be a new redback system.Comment: 35 pages, 8 figures, accepted for publication on Astrophysical Journa

Transregional Slave Networks of the Northern Arc, 700–900 C.E.:

Thesis advisor: Robin FlemingThis dissertation charts the movement of slaves from Western Europe, through Scandinavia, and into the frontiers of the Caliphate, a movement which took shape in the early 700s and flourished into the late 800s. The victims of this movement are well attested in texts from either end of their journey, and the movement of everyday things allows us to trace the itineraries they followed. Necklace beads—produced in the east, carried to the north, and worn in the west—serve as proxies for human traffic that traveled the same routes in opposite directions. Attention to this traffic overcomes four impasses—between regional particularism and interregional connectivity; between attention to exchange and focus on production; between privileging textual or material evidence; and between definitions of slavery that obscure practices of enslavement. The introduction outlines problems of studying medieval slavery with regard to transregional approaches to the Middle Ages, the transition to serfdom, and the use of material evidence. Chapter One gathers narrative texts previously dealt with anecdotally to establish patterns for the Viking-Age slave trade, with eastward traffic thriving by the late 800s. Chapter Two confirms these patterns by graphically comparing viking violence to reports of captive taking in the annals and archival documents of Ireland, Francia, and Anglo-Saxon England. Chapter Three investigates how viking captive taking impacted Western societies and the creation of written records in Carolingian Europe. Chapter Four turns to the material record, using beads to trace the intensity and flow of human traffic that fed from early viking violence. Chapter Five establishes a corresponding demand for slaves in the ʿAbbāsid Caliphate through Arabic archival, legal, historical, and geographic texts. The conclusion places this research in the context of global history. By spanning periods, regions, and disciplines, this dissertation brings to focus people who crossed boundaries unwillingly, but whose movements contributed to epochal change.Thesis (PhD) — Boston College, 2019.Submitted to: Boston College. Graduate School of Arts and Sciences.Discipline: History

Correlation between the optical veiling and accretion properties: A case study of the classical T Tauri star DK Tau

Classical T Tauri stars (cTTs) accrete from their circumstellar disk. The material falls onto the stellar surface, producing an accretion shock, which generates veiling in a star's spectra. In addition, the shock causes a localized accretion spot at the level of the chromosphere. Our goal is to investigate the accretion, particularly the mass accretion rates (Macc), for the cTTs DK Tau, over two periods of 17 and 29 days, using two different procedures for comparison purposes. The first method relies on the derivation of the accretion luminosity via accretion-powered emission lines. The second compares the variability of the optical veiling with accretion shock models to determine mass accretion rates. We used observations taken in 2010 and 2012 with the ESPaDOnS spectropolarimeter at the CFHT. We find peak values of the veiling (at 550 nm) ranging from 0.2 to 1.3, with a steeper trend across the wavelength range for higher peak values. When using the accretion-powered emission lines, we find mass accretion rate values ranging from log(Macc[Msol/yr]) = -8.20 to log(Macc[Msol/yr]) = -7.40. This agrees with the values found in the literature, as well as the values calculated using the accretion shock models and the veiling. In addition, we identify a power-law correlation between the values of the accretion luminosity and the optical veiling. For the 2010 observations, using the values of the filling factors (which represent the area of the star covered by an accretion spot) derived from the shock models, we infer that the accretion spot was located between +45 degrees and +75 degrees in latitude. We show that both methods of determining the mass accretion rate yield similar results. We also present a helpful means of confirming the accretion luminosity values by measuring the veiling at a single wavelength in the optical

Non-colliding Brownian Motions and the extended tacnode process

We consider non-colliding Brownian motions with two starting points and two endpoints. The points are chosen so that the two groups of Brownian motions just touch each other, a situation that is referred to as a tacnode. The extended kernel for the determinantal point process at the tacnode point is computed using new methods and given in a different form from that obtained for a single time in previous work by Delvaux, Kuijlaars and Zhang. The form of the extended kernel is also different from that obtained for the extended tacnode kernel in another model by Adler, Ferrari and van Moerbeke. We also obtain the correlation kernel for a finite number of non-colliding Brownian motions starting at two points and ending at arbitrary points.Comment: 38 pages. In the revised version a few arguments have been expanded and many typos correcte

До питання підготовки музейної експозиції з історії культури первісного суспільства

In Europe, water management is moving from flood defense to a risk management approach, which takes both the probability and the potential consequences of flooding into account. In this report, we will look at Directives and (non-)EU- initiatives in place to deal with flood risk in Europe indirectly and directly. Emphasis will lie on the two Directives most specifically aimed at floods: the Water Framework Directive (WFD) and the Floods Directive (FD) – how are they related and how they have been or are implemented in the Member States (MSs)? In February 1995, the Netherlands and France took the initiative for a discussion on streamlining the water legislation of the European Union (EU) which resulted in the creation of the WFD in 2000. The WFD provided a new system for the protection and improvement of Europe’s water environment – its rivers, lakes, estuaries, coastal waters and groundwaters. Its main innovation is the requirement that water be managed in an integrated way, with river basin management as leading managing unit. Since flood protection is not explicitly addressed in the WFD, the need to clarify the role of the WFD in flood protection was put on the European agenda as early as 2003, and in 2007, the FD became a fact. The FD is to be implemented in coordination with the WFD, notably by coordinating Flood Risk Management Plans (FRMPs) and River Basin Management Plans (RBMPs). Both the WFD and the FD reflect a shift in EU-governance. Instead of the more traditional top-down legalistic approach they emphasise the importance of more bottom up initiatives from the actors who have to implement the Directives. Combined with the expanded freedom and flexibility for national and local governments, with this new approach, the FD is the first Water Directive in EU law that does not offer an equal minimum level of protection for EU citizens. While both Directives are meant to harmonise European legislation, much flexibility on objectives and measures in the FD is left to the MSs, justified by the nature of flooding and the subsidiarity principle. This creates multi-actor, multi-level and multi-sector challenges addressed in report D1.1.2 (Hegger et al. 2013). For instance, the FD sets out general obligations for transboundary cooperation, but at the national level, the scope and distributions of duties, rights and powers of the various organizations involved should be set out in law. Other challenges identified in the literature are concrete issues related to mandatory flood risks assessments, flood risk maps, and Flood Risk Management plans, but also the involvement of the public and stakeholders, the science-policy interface, uncertainties related to climate change predictions and effects, the coordination with the WFD, the lack of safety standards, the lack of possibilities for EU citizens to rely on substantive provisions before the administrative courts and finally, transboundary aspects such as issues of scale, mismatches between national policies, the assessment of transboundary effects and division of costs related to this. In sum, this report has clarified the development, content and implementation of the current European flood risk governance policies, possible synergies between the two most important Directives linked to floods, and identified topics and questions for more in-depth questions relevant for the next work packages, pertaining to, in no particular order, a) the level of implementation and level of ambition as well as the competent authorities in the case study countries; b) the transboundary nature of floods; c) synergies and conflicts between FD and WFD and other issues not mentioned in these Directives; d) the degree of harmonization, for instance when it comes to flood safety standards and e) the subsidiarity principle – is this conform the requirements set out in the FD? Because while current European flood regulation specified in the WFD and FD provides several potential opportunities for improving flood risk governance, it is not self-evident that all of these opportunities will materialise in all MSs

Previous reproductive history and post-natal family planning among HIV-infected women in Ukraine

BACKGROUND: Ukraine has the highest antenatal HIV prevalence in Europe. The national prevention of mother-to-child transmission (MTCT) programme has reduced the MTCT rate, but less attention has been given to the prevention of unintended pregnancy among HIV-positive women. Our objectives were to describe the reproductive health, condom use and family planning (FP) practices of HIV-positive childbearing Ukrainian women and to identify factors associated with different methods of post-natal contraception. METHODS: HIV-infected childbearing women, diagnosed before or during pregnancy, were enrolled prospectively in a post-natal cohort study in four regional HIV/AIDS centres in Ukraine from December 2007. Logistic regression models were used to identify factors associated with post-natal FP practices. RESULTS: Data were available for 371 women enrolled by March 2009; 82% (n = 303) were married or cohabiting, 27% (97 of 363) reported a current HIV-negative sexual partner and 69% were diagnosed with HIV during their most recent pregnancy. Overall, 21% (75 of 349) of women were not using contraception post-natally (of whom 80% reported no current sexual activity), 50% (174 of 349) used condoms, 20% (74 of 349) relied solely/partially on coitus interruptus and 4% used hormonal methods or intrauterine device. Among married/cohabiting women, consistent use of condoms in the previous pregnancy [AOR 1.96 (95%CI 1.06–3.62)], having an HIV-positive partner [AOR 0.42 (0.20–0.87)], current sexual activity [AOR 4.53 (1.19–17.3)] and study site were significantly associated with post-natal condom use; 16% of those with HIV-negative partners did not use condoms. Risk factors for non-use of FP were lack of affordability [AOR 6.34 (1.73–23.2)] and inconsistent use of condoms in the previous pregnancy [AOR 7.25 (1.41–37.2)]. CONCLUSIONS: More than 40% of HIV-positive women in this population are at risk of unintended pregnancy and the one in six women in HIV-discordant couples not using barrier methods risk transmitting HIV to their partners. Our study results are limited by the observational nature of the data and the potential for both measured and unmeasured confounding

Super-solar metallicity at the position of the ultra-long GRB130925A

Over the last decade there has been immense progress in the follow-up of short and long GRBs, resulting in a significant rise in the detection rate of X-ray and optical afterglows, in the determination of GRB redshifts, and of the identification of the underlying host galaxies. Nevertheless, our theoretical understanding on the progenitors and central engines powering these vast explosions is lagging behind, and a newly identified class of `ultra-long' GRBs has fuelled speculation on the existence of a new channel of GRB formation. In this paper we present high signal-to-noise X-shooter observations of the host galaxy of GRB130925A, which is the fourth unambiguously identified ultra-long GRB, with prompt gamma-ray emission detected for ~20ks. The GRB line of sight was close to the host galaxy nucleus, and our spectroscopic observations cover both this region along the bulge/disk of the galaxy, in addition to a bright star-forming region within the outskirts of the galaxy. From our broad wavelength coverage we obtain accurate metallicity and dust-extinction measurements at both the galaxy nucleus, and an outer star-forming region, and measure a super-solar metallicity at both locations, placing this galaxy within the 10-20% most metal-rich GRB host galaxies. Such a high metal enrichment has implications on the progenitor models of both long and ultra-long GRBs, although the edge-on orientation of the host galaxy does not allow us to rule out a large metallicity variation along our line of sight. The spatially resolved spectroscopic data presented in this paper offer important insight into variations in the metal and dust abundance within GRB host galaxies. They also illustrate the need for IFU observations on a larger sample of GRB host galaxies at varies metallicities to provide a more quantitative view on the relation between the GRB circumburst and the galaxy-whole properties.Comment: 9 pages, 3 figures, A&A in press, matches published versio