Astrophysical parameters and orbital solution of the peculiar X-ray transient IGR J00370+6122

Context. BD + 60° 73 is the optical counterpart of the X-ray source IGR J00370+6122, a probable accretion-powered X-ray pulsar. The X-ray light curve of this binary system shows clear periodicity at 15.7 d, which has been interpreted as repeated outbursts around the periastron of an eccentric orbit. Aims. We aim to characterise the binary system IGR J00370+6122 by deriving its orbital and physical parameters. Methods. We obtained high-resolution spectra of BD + 60° 73 at different epochs. We used the fastwind code to generate a stellar atmosphere model to fit the observed spectrum and obtain physical magnitudes. The synthetic spectrum was used as a template for cross-correlation with the observed spectra to measure radial velocities. The radial velocity curve provided an orbital solution for the system. We also analysed the RXTE/ASM and Swift/BAT light curves to confirm the stability of the periodicity. Results. BD + 60° 73 is a BN0.7 Ib low-luminosity supergiant located at a distance ~3.1 kpc, in the Cas OB4 association. We derive Teff = 24 000 K and log gc = 3.0, and chemical abundances consistent with a moderately high level of evolution. The spectroscopic and evolutionary masses are consistent at the 1-σ level with a mass M∗ ≈ 15 M⊙. The recurrence time of the X-ray flares is the orbital period of the system. The neutron star is in a high-eccentricity (e = 0.56 ± 0.07) orbit, and the X-ray emission is strongly peaked around orbital phase φ = 0.2, though the observations are consistent with some level of X-ray activity happening at all orbital phases. Conclusions. The X-ray behaviour of IGR J00370+6122 is reminiscent of “intermediate” supergiant X-ray transients, though its peak luminosity is rather low. The orbit is somewhat wider than those of classical persistent supergiant X-ray binaries, which when combined with the low luminosity of the mass donor, explains the low X-ray luminosity. IGR J00370+6122 will very likely evolve towards a persistent supergiant system, highlighting the evolutionary connection between different classes of wind-accreting X-ray sources.

O cartaz serigráfico

Dissertação apresentada à Escola Superior de Artes Aplicadas do Instituto Politécnico de Castelo Branco em associação com a Faculdade de Arquitetura da Universidade de Lisboa para cumprimento dos requisitos necessários à obtenção do grau de Mestre em Design Gráfico.

Sedimentology, geochemistry and paleomagnetic of ODP Hole 151-913B

The Eocene and Oligocene epochs (55 to 23 million years ago) comprise a critical phase in Earth history. An array of geological records (Zachos et al., 2001, doi:10.1126/science.1059412; Lear et al., 2000, doi:10.1126/science.287.5451.269; Coxall et al., 2005, doi:10.1038/nature03135; Pekar et al., 2005; doi:10.1130/B25486.1; Strand et al., 2003, doi:10.1016/S0031-0182(03)00396-1) supported by climate modelling (DeConto and Pollard, 2003, doi:10.1038/nature01290) indicates a profound shift in global climate during this interval, from a state that was largely free of polar ice caps to one in which ice sheets on Antarctica approached their modern size. However, the early glaciation history of the Northern Hemisphere is a subject of controversy (Coxall et al., 2005, doi:10.1038/nature03135; Tripati et al., 2005, doi:10.1038/nature03874; Wolf-Welling et al., 1996, doi:10.2973/odp.proc.sr.151.139.1996; Moran et al., 2006, doi:10.1038/nature04800). Here we report stratigraphically extensive ice-rafted debris, including macroscopic dropstones, in late Eocene to early Oligocene sediments from the Norwegian-Greenland Sea that were deposited between about 38 and 30 million years ago. Our data indicate sediment rafting by glacial ice, rather than sea ice, and point to East Greenland as the likely source. Records of this type from one site alone cannot be used to determine the extent of ice involved. However, our data suggest the existence of (at least) isolated glaciers on Greenland about 20 million years earlier than previously documented (Winkler et al., 2002, doi:10.1007/s005310100199), at a time when temperatures and atmospheric carbon dioxide concentrations were substantially higher.

The history of Georgia.

v. 1. Aboriginal and colonial epochs.--v. 2. Revolutionary epoch.

Studies on the use of perennial forage legumes as living mulches for no-till small grains /

Typescript (photocopy)

The United States, analytical reference,

Plates accompanied by guard sheets with descriptive letterpress.

Differential activation of the thoracic multifidus and longissimus thoracis during trunk rotation

Study Design. Cross-sectional study. Objective. To develop a technique to measure electromyographic (EMG) activity of deep and superficial paraspinal muscles at different thoracic levels and to investigate activity of these muscles during seated trunk rotation. Summary of Background Data. Few studies have compared activity of deep and superficial paraspinal muscles of the thorax during trunk rotation, and conflicting results have been presented. Conflicting data may result from recording techniques or variation in activity between thoracic regions. Methods. EMG recordings were made from deep (multifidus/ rotatores) and superficial ( longissimus) paraspinal muscles at T5, T8, and T11 using selective intramuscular electrodes. Ten subjects rotated the trunk to end of range in each direction. EMG amplitude was measured in neutral, at end of range, and during four epochs, which represented four quarters of the movement. Results. During trunk rotation in sitting, longissimus EMG either increased with ipsilateral rotation ( T5) or decreased with contralateral rotation ( T5, T8, T11). In contrast, multifidus EMG was more variable and was either active with rotation in both directions ( particularly T5) or with one movement direction. Conclusions. The deep and superficial muscles of the thorax are differentially active, and the patterns of activity differ between the regions of the thorax. Data from this study support the hypothesis that multifidus may have a role in control of segmental motion at T5. Variability in multifidus activity at T8 and T11 suggests that this muscle may also control coupling between rotation and lateral flexion.

Farmers' strategies for managing acid upland soils in Southeast Asia: an evolutionary perspective

The acid soils of the uplands of Southeast Asia have resisted intensive agricultural use for centuries. In recent decades, however, due to rapid population growth, escalating market demand for agricultural produce, and govemment policies for land development and settlement, the acid uplands have become the focus of more intensive land-use systems, placing greater demands on farmers and requiring the development and dissemination of improved practices for soil management. In order to develop appropriate soil management technologies and plan effective interventions to facilitate their adoption, it is important to understand the goals and circumstances of farmers in the acid uplands, the range of farming systems they have developed, and the variety of socio-economic factors and trends influencing the evolution of these farming systems. Building on Boserup's model of agrarian change, an evolutionary framework is developed and applied to five case studies: a long-fallow (shifting) cultivation system in Sarawak, Malaysia; a short-fallow system in South Kalimantan, Indonesia; a continuous cropping system in Bukidnon, Philippines; a tree crop (with intercropping) system in Southern Thailand; a livestock grazing system in Daclac, Vietnam. The framework provides a useful tool to interpret and categorise farmers' evolving soil management strategies and to plan more effective soil management research and interventions. (c) 2004 Elsevier B.V. All rights reserved.

Comparison of the distributions of classical and adaptively aligned EEG power spectra

The distributions of eyes-closed resting electroencephalography (EEG) power spectra and their residuals were described and compared using classically averaged and adaptively aligned averaged spectra. Four minutes of eyes-closed resting EEG was available from 69 participants. Spectra were calculated with 0.5-Hz resolution and were analyzed at this level. It was shown that power in the individual 0.5 Hz frequency bins can be considered normally distributed when as few as three or four 2-second epochs of EEG are used in the average. A similar result holds for the residuals. Power at the peak Alpha frequency has quite different statistical behaviour to power at other frequencies and it is considered that power at peak Alpha represents a relatively individuated process that is best measured through aligned averaging. Previous analyses of contrasts in upper and lower alpha bands may be explained in terms of the variability or distribution of the peak Alpha frequency itself.

Neural control of a batch distillation

The purpose of the work reported here was to investigate the application of neural control to a common industrial process. The chosen problem was the control of a batch distillation. In the first phase towards deployment, a complex software simulation of the process was controlled. Initially, the plant was modelled with a neural emulator. The neural emulator was used to train a neural controller using the backpropagation through time algorithm. A high accuracy was achieved with the emulator after a large number of training epochs. The controller converged more rapidly, but its performance varied more widely over its operating range. However, the controlled system was relatively robust to changes in ambient conditions.

Graphical modelling for brain connectivity via partial coherence

Spectral and coherence methodologies are ubiquitous for the analysis of multiple time series. Partial coherence analysis may be used to try to determine graphical models for brain functional connectivity. The outcome of such an analysis may be considerably influenced by factors such as the degree of spectral smoothing, line and interference removal, matrix inversion stabilization and the suppression of effects caused by side-lobe leakage, the combination of results from different epochs and people, and multiple hypothesis testing. This paper examines each of these steps in turn and provides a possible path which produces relatively ‘clean’ connectivity plots. In particular we show how spectral matrix diagonal up-weighting can simultaneously stabilize spectral matrix inversion and reduce effects caused by side-lobe leakage, and use the stepdown multiple hypothesis test procedure to help formulate an interaction strength.

Resonance studies of artificial earth satellites

Orbit determination from artificial satellite observations is a key process in obtaining information about the Earth and its environment. A study of the perturbations experienced by these satellites enables knowledge to be gained of the upper atmosphere, the gravity field, ocean tides, solid-Earth tides and solar radiation. The gravity field is expressed as a double infinite series of associated Legendre functions (tesseral harmonics). In contemporary global gravity field models the overall geoid is well determined. An independent check on these gravity field harmonics of a particular order may be made by analysis of satellites that pass through resonance of that order. For such satellites the perturbations of the orbital elements close to resonance are analysed to derive lumped harmonic coefficients. The orbital parameters of 1984-106A have been determined at 43 epochs, during which time the satellite was close to 14th order resonance. Analysis of the inclination and eccentricity yielded 6 lumped harmonic coefficients of order 14 whilst analysis of the mean motion yielded additional pairs of lumped harmonics of orders 14, 28 and 42, with the 14th order harmonics superseding those obtained from analysis of the inclination. This thesis concentrates in detail on the theoretical changes of a near-circular satellite orbit perturbed by the Earth's gravity field under the influence of minimal air-drag whilst in resonance with the Earth. The satellite 1984-106A experienced the interesting property of being temporarily trapped with respect to a secondary resonance parameter due to the low air-drag in 1987. This prompted the theoretical investigation of such a phenomenon. Expressions obtained for the resonance parameter led to the determination of 8 lumped harmonic coefficients, coincidental to those already obtained. All the derived lumped harmonic values arc used to test the accuracy of contemporary gravity field models and the underlying theory in this thesis.

Dynamic joint sentiment-topic model

Social media data are produced continuously by a large and uncontrolled number of users. The dynamic nature of such data requires the sentiment and topic analysis model to be also dynamically updated, capturing the most recent language use of sentiments and topics in text. We propose a dynamic Joint Sentiment-Topic model (dJST) which allows the detection and tracking of views of current and recurrent interests and shifts in topic and sentiment. Both topic and sentiment dynamics are captured by assuming that the current sentiment-topic-specific word distributions are generated according to the word distributions at previous epochs. We study three different ways of accounting for such dependency information: (1) Sliding window where the current sentiment-topic word distributions are dependent on the previous sentiment-topic-specific word distributions in the last S epochs; (2) skip model where history sentiment topic word distributions are considered by skipping some epochs in between; and (3) multiscale model where previous long- and shorttimescale distributions are taken into consideration. We derive efficient online inference procedures to sequentially update the model with newly arrived data and show the effectiveness of our proposed model on the Mozilla add-on reviews crawled between 2007 and 2011. © 2013 ACM 2157-6904/2013/12-ART5 $ 15.00.

A Limit Theorem for Multi-Type Subcritical Age-Dependent Branching Processes with two Types of Immigration

Марусия Н. Славчова-Божкова - В настоящата работа се обобщава една гранична теорема за докритичен многомерен разклоняващ се процес, зависещ от възрастта на частиците с два типа имиграция. Целта е да се обобщи аналогичен резултат в едномерния случай като се прилагат “coupling” метода, теория на възстановяването и регенериращи процеси.

An unsupervised Bayesian modelling approach to storyline detection from news articles

Storyline detection from news articles aims at summarizing events described under a certain news topic and revealing how those events evolve over time. It is a difficult task because it requires first the detection of events from news articles published in different time periods and then the construction of storylines by linking events into coherent news stories. Moreover, each storyline has different hierarchical structures which are dependent across epochs. Existing approaches often ignore the dependency of hierarchical structures in storyline generation. In this paper, we propose an unsupervised Bayesian model, called dynamic storyline detection model, to extract structured representations and evolution patterns of storylines. The proposed model is evaluated on a large scale news corpus. Experimental results show that our proposed model outperforms several baseline approaches.