Irradiation of the secondary star in X-ray Nova Scorpii 1994 (=GRO J1655--40)

We have obtained intermediate resolution optical spectra of the black-hole candidate Nova Sco 1994 in June 1996, when the source was in an X-ray/optical active state (R~15.05). We measure the radial velocity curve of the secondary star and obtain a semi-amplitude of 279+/-10 km/s; a value which is 30 per cent larger than the value obtained when the source is in quiescence. Our large value for K_2 is consistent with 60 +9,-7 per cent of the secondary star's surface being heated; compared to 35 per cent, which is what one would expect if only the inner face of the secondary star were irradiated. Effects such as irradiation-induced flows on the secondary star may be important in explaining the observed large value for K_2.Comment: 5 pages, 2 figures, accepted by MNRA

Terrorists, rioters and crocodiles: The political symbolism of an Olympic monster

This is a post-peer-review, pre-copyedit version of an article published in British Politics. The definitive publisher-authenticated version - British Politics, 2014, 9(2), pp. 161-181 - is available online at: http://www.palgrave-journals.com/bp/journal/v9/n2/full/bp201317a.htmlIn August 2005, just a month after the announcement that London had succeeded in its bid to host the 2012 Olympic Games, the UK national press witnessed a brief rash of stories alleging the presence of a crocodile or similar water monster lurking beneath the surface of the River Lea – the river that runs from the town of Luton in Bedfordshire down to join the Thames adjacent to the Olympic site. This story re-emerged in November 2011 when a campaigner against the environmental impact of the Olympics on the river area claimed to have seen further evidence of crocodilian activity. This paper will explore the reasons for the proliferation of this story, in terms both of its function as a metonymic news-hook (it opened up directly related concerns as to the impact, organization and security of the Games) and of its metaphorical significance (its incarnation of a superstructure’s fears of an emerging threat of a monstrous underclass – one which might at once comprise terrorists, rioters and anti-establishment campaigners). It will conclude by suggesting that this monstrous myth might hold within it the possibility of the convergence of populist news media and popular democracy

Unveiling the nature of INTEGRAL objects through optical spectroscopy. VIII. Identification of 44 newly detected hard X-ray sources

(abridged) Hard X-ray surveys performed by the INTEGRAL satellite have discovered a conspicuous fraction (up to 30%) of unidentified objects among the detected sources. Here we continue our identification program by selecting probable optical candidates using positional cross-correlation with soft X-ray, radio, and/or optical archives, and performing optical spectroscopy on them. As a result, we identified or more accurately characterized 44 counterparts of INTEGRAL sources: 32 active galactic nuclei, with redshift 0.019 < z < 0.6058, 6 cataclysmic variables (CVs), 5 high-mass X-ray binaries (2 of which in the Small Magellanic Cloud), and 1 low-mass X-ray binary. This was achieved by using 7 telescopes of various sizes and archival data from two online spectroscopic surveys. The main physical parameters of these hard X-ray sources were also determined using the available multiwavelength information. AGNs are the most abundant population among hard X-ray objects, and our results confirm this tendency when optical spectroscopy is used as an identification tool. The deeper sensitivity of recent INTEGRAL surveys enables one to begin detecting hard X-ray emission above 20 keV from sources such as LINER-type AGNs and non-magnetic CVs.Comment: 22 pages, 14 figures, 6 tables, accepted for publication on A&A, main journa

Accurate classification of 29 objects detected in the 39 months Palermo Swift/BAT hard X-ray catalogue

Through an optical campaign performed at 4 telescopes located in the northern and the southern hemispheres, plus archival data from two on-line sky surveys, we have obtained optical spectroscopy for 29 counterparts of unclassified or poorly studied hard X-ray emitting objects detected with Swift/BAT and listed in the 39 months Palermo catalogue. All these objects have also observations taken with Swift/XRT or XMM-EPIC which not only allow us to pinpoint their optical counterpart, but also to study their X-ray spectral properties (column density, power law photon index and F2-10 keV flux). We find that 28 sources in our sample are AGN; 7 are classified as type 1 while 21 are of type 2; the remaining object is a galactic cataclysmic variable. Among our type 1 AGN, we find 5 objects of intermediate Seyfert type (1.2-1.9) and one Narrow Line Seyfert 1 galaxy; for 4 out of 7 sources, we have been able to estimate the central black hole mass. Three of the type 2 AGN of our sample display optical features typical of the LINER class and one is a likely Compton thick AGN. All galaxies classified in this work are relatively nearby objects since their redshifts lie in the range 0.008-0.075; the only galactic object found lies at an estimated distance of 90 pc. We have also investigated the optical versus X-ray emission ratio of the galaxies of our sample to test the AGN unified model. For them, we have also compared the X-ray absorption (due to gas) with the optical reddening (due to dust): we find that for most of our sources, specifically those of type 1.9-2.0 the former is higher than the latter confirming early results by Maiolino et al. (2001); this is possibly due to the properties of dust in the circumnuclear obscuring torus of the AGN.Comment: 15 pages, 4 figures, 8 tables, accepted for publication on Astronomy and Astrophysic

BlackCAT: A catalogue of stellar-mass black holes in X-ray transients

During the last ~50 years, the population of black hole candidates in X-ray binaries has increased considerably with 59 Galactic objects detected in transient low-mass X-ray binaries, plus a few in persistent systems (including ~5 extragalactic binaries). We collect near-infrared, optical and X-ray information spread over hundreds of references in order to study the population of black holes in X-ray transients as a whole. We present the most updated catalogue of black hole transients, which contains X-ray, optical and near-infrared observations together with their astrometric and dynamical properties. It provides new useful information in both statistical and observational parameters providing a thorough and complete overview of the black hole population in the Milky Way. Analysing the distances and spatial distribution of the observed systems, we estimate a total population of ~1300 Galactic black hole transients. This means that we have already discovered less than ~5% of the total Galactic distribution. The complete version of this catalogue will be continuously updated online and in the Virtual Observatory, including finding charts and data in other wavelengths.Comment: http://www.astro.puc.cl/BlackCAT - Accepted for publication in Astronomy & Astrophysics. 20 pages, 8 figures, 5 Table

Amplitude Reduction and Phase Shifts of Melatonin, Cortisol and Other Circadian Rhythms after a Gradual Advance of Sleep and Light Exposure in Humans

Background: The phase and amplitude of rhythms in physiology and behavior are generated by circadian oscillators and entrained to the 24-h day by exposure to the light-dark cycle and feedback from the sleep-wake cycle. The extent to which the phase and amplitude of multiple rhythms are similarly affected during altered timing of light exposure and the sleepwake cycle has not been fully characterized. Methodology/Principal Findings: We assessed the phase and amplitude of the rhythms of melatonin, core body temperature, cortisol, alertness, performance and sleep after a perturbation of entrainment by a gradual advance of the sleep-wake schedule (10 h in 5 days) and associated light-dark cycle in 14 healthy men. The light-dark cycle consisted either of moderate intensity ‘room ’ light (,90–150 lux) or moderate light supplemented with bright light (,10,000 lux) for 5 to 8 hours following sleep. After the advance of the sleep-wake schedule in moderate light, no significant advance of the melatonin rhythm was observed whereas, after bright light supplementation the phase advance was 8.1 h (SEM 0.7 h). Individual differences in phase shifts correlated across variables. The amplitude of the melatonin rhythm assessed under constant conditions was reduced after moderate light by 54 % (17–94%) and after bright light by 52 % (range 12–84%), as compared to the amplitude at baseline in the presence of a sleep-wake cycle. Individual differences in amplitude reduction of the melatonin rhythm correlated with the amplitude of body temperature, cortisol and alertness

Oxygen as a Driver of Early Arthropod Micro-Benthos Evolution

BACKGROUND: We examine the physiological and lifestyle adaptations which facilitated the emergence of ostracods as the numerically dominant Phanerozoic bivalve arthropod micro-benthos. METHODOLOGY/PRINCIPAL FINDINGS: The PO(2) of modern normoxic seawater is 21 kPa (air-equilibrated water), a level that would cause cellular damage if found in the tissues of ostracods and much other marine fauna. The PO(2) of most aquatic breathers at the cellular level is much lower, between 1 and 3 kPa. Ostracods avoid oxygen toxicity by migrating to waters which are hypoxic, or by developing metabolisms which generate high consumption of O(2). Interrogation of the Cambrian record of bivalve arthropod micro-benthos suggests a strong control on ecosystem evolution exerted by changing seawater O(2) levels. The PO(2) of air-equilibrated Cambrian-seawater is predicted to have varied between 10 and 30 kPa. Three groups of marine shelf-dwelling bivalve arthropods adopted different responses to Cambrian seawater O(2). Bradoriida evolved cardiovascular systems that favoured colonization of oxygenated marine waters. Their biodiversity declined during intervals associated with black shale deposition and marine shelf anoxia and their diversity may also have been curtailed by elevated late Cambrian (Furongian) oxygen-levels that increased the PO(2) gradient between seawater and bradoriid tissues. Phosphatocopida responded to Cambrian anoxia differently, reaching their peak during widespread seabed dysoxia of the SPICE event. They lacked a cardiovascular system and appear to have been adapted to seawater hypoxia. As latest Cambrian marine shelf waters became well oxygenated, phosphatocopids went extinct. Changing seawater oxygen-levels and the demise of much of the seabed bradoriid micro-benthos favoured a third group of arthropod micro-benthos, the ostracods. These animals adopted lifestyles that made them tolerant of changes in seawater O(2). Ostracods became the numerically dominant arthropod micro-benthos of the Phanerozoic. CONCLUSIONS/SIGNIFICANCE: Our work has implications from an evolutionary context for understanding how oxygen-level in marine ecosystems drives behaviour

Os dividendos como estratégia de investimentos em ações

Na Teoria de Finanças, o papel dos dividendos nas cotações é um tema controverso, uma vez que há diferentes teorias que abordam sua relevância para o valor das ações e, em conseqüência, para a riqueza dos acionistas. Além disso, as descobertas empíricas que originaram a Hipótese de Mercado Eficiente de Capitais (HME) não apenas contradizem a Análise Técnica, mas também impõem um desafio à declarada habilidade superior da Análise Fundamentalista em gerar retornos superiores, com base em fatores ou variáveis contábeis, financeiros e econômicos, tais como o dividend yield (retorno em dividendos). A fim de se verificar a relação entre dividend yields e as taxas de retornos das ações, bem como a viabilidade de uma estratégia baseada em dividend yields históricos de "bater" o mercado, foram construídas, mensalmente, durante o período que vai do Plano Real em julho de 1994 a dezembro de 1999, três diferentes carteiras (alto, baixo e zero). Seus riscos, retornos e indicadores de desempenho ajustados ao risco foram calculados e comparados entre si e com seu paradigma (benchmark), o Índice da Bolsa de Valores de São Paulo - Ibovespa. A evidência empírica é incapaz de sugerir que as ações de altos dividend yield tendem a possuir maiores ou menores taxas de retorno do que as ações de baixo ou zero yield. Ademais, as evidências sugerem que não é possível demonstrar, usando o método empírico aplicado, uma clara associação entre dividend yield e taxas de retorno das ações.In Finance Theory, the role of dividends in stock prices is a controversial issue, considering the different theories that exist on their relevance for stock value and, consequently, for shareholders' wealth. Furthermore, empirical findings that have originated the Efficient Market Hypothesis (EMH) not only contradict Technical Analysis, but also pose a challenge to the Fundamental Analysis' supposedly superior ability to generate higher returns based on accounting, financial and economic factors or variables such as the dividend yield. In order to assess the relationship between dividend yields and stocks returns as well as the viability of a strategy based on historic dividend yield to "beat" the market, with reference to the period from the beginning of the Real Plan in July 1994 until December 1999, three different yield portfolios (high, low and zero) were formed on a monthly basis.Their risks, returns and risk-adjusted portfolio performance measurements were calculated, and then compared both among themselves and to the benchmark (São Paulo Stock Exchange Index - Ibovespa). Empirical evidence is unable to suggest either that stocks with a high dividend yield tend to have higher or lower returns than those with a low or zero yield. Moreover, the evidences suggest that, using the applied empirical method, no clear association between dividend yield and stock returns can be demonstrated