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Swinbank J.,University of Amsterdam | Baker J.,Nature | Barr J.,University of Oxford | Hook I.,University of Oxford | Bland-Hawthorn J.,University of Sydney
Monthly Notices of the Royal Astronomical Society | Year: 2012

We have used the Taurus Tunable Filter to search for Lyα emitters in the fields of three high-redshift quasars: two at z∼ 2.2 (MRC B1256-243 and MRC B2158-206) and one at z∼ 4.5 (BR B0019-1522). Our observations had a field of view of around 35arcmin 2, and reached AB magnitudes of ∼21 (MRC B1256-243), ∼22 (MRC B2158-206) and ∼22.6 (BR B0019-1522) depending on wavelength. We have identified candidate emission-line galaxies in all the three fields, with the higher redshift field being by far the richest. By combining our observations with simulations of the instrumental response, we estimate the total density of emission-line galaxies in each field. 17 candidate emission-line galaxies were found within 1.5Mpc of BR B0019-1522, a number density of (4.9 ± 1.2) × 10 -3Mpc -3, suggesting a significant galaxy overdensity at z∼ 4.5. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS. Source


Banerjee M.,Indian Institute of Technology Guwahati | Ray M.R.,Chittaranjan National Cancer Institute | Lahiri T.,Nature
Water, Air, and Soil Pollution | Year: 2010

Air pollution is a major contributor to several respiratory problems, it affects the whole population in general but children are more susceptible. Exposure to automobile exhaust is associated with increased respiratory symptoms and may impair lung function in children. In view of this, the study was conducted among the children of Delhi, the capital city of India, where ambient air quality was much above the National Ambient Air Quality Standards. The study was conducted in children aged 9-17 years. Pulmonary function test was carried out following the guideline of American Thoracic Society using a portable, electronic spirometer. Air quality data was collected from Central and State Pollution Control Boards. In addition, the level of particulate matter in indoor air was measured by portable laser photometer. Lung function was reduced in 43.5% schoolchildren of the urban area compared with 25.7% of control group. The urban children had increased prevalence of restrictive, obstructive, as well as combined type of lung functions deficits. Besides higher prevalence, the magnitude of lung function deficits was also much more in them. After controlling potential confounders like season, socioeconomic conditions and ETS, PM10 level in ambient air was found to be associated with restrictive (OR=1.35, 95% CI 1.07-1.58), obstructive (OR=1.45, 95% CI 1.16-1.82), and combined type of lung function deficits (OR=1.74, 95% CI 1.37-2.71) in children. Spearman's rank correlation test reaffirmed the association. The study confirms that the level of air pollution is affecting the children. © 2010 Springer Science+Business Media B.V. Source


Down E.J.,Oxford Astrophysics | Down E.J.,Herzberg Institute for Astrophysics | Rawlings S.,Oxford Astrophysics | Sivia D.S.,St Johns College | Baker J.C.,Nature
Monthly Notices of the Royal Astronomical Society | Year: 2010

Infrared spectroscopy of the Hα emission lines of a subsample of 19 high-redshift (0.8 < z < 2.3) Molonglo quasars, selected at 408 MHz, is presented. These emission lines are fitted with composite models of broad and narrow emission, which include combinations of classical broad-line regions (BLRs) of fast-moving gas clouds lying outside the quasar nucleus, and/or a theoretical model of emission from an optically thick, flattened, rotating accretion disc, with velocity shifts allowed between the components. All bar one of the 19 sources are found to have emission consistent with the presence of an optically emitting accretion disc, with the exception appearing to display complex emission including at least three broad components. 10 of the quasars have strong Bayesian evidence for broad-line emission arising from an accretion disc together with a standard BLR, selected in preference to a model with two simple broad lines. Thus, the best explanation for the complexity required to fit the broad Hα lines in this sample is optical emission from an accretion disc in addition to a region of fast-moving clouds. We derive estimates of the angle between the rotation axis of the accretion disc and the line of sight. Deprojecting radio sources on the assumption of jets emerging perpendicular to the accretion disc gives rough agreement with expectations of radio source models. The distribution in disc angles is broadly consistent with models in which a Doppler boosted core contributes to the chances of observing a source at low inclination to the line of sight, and in which the radio jets expand at constant speed up to a size of ∼1 Mpc. A weak correlation is found between the accretion disc angle and the logarithm of the low-frequency radio luminosity. This is direct, albeit tenuous, evidence for the receding torus model in which the opening angle of the torus widens with increasing radio luminosity. The highest accretion disc angle measured is 48°, consistent with the opening angle predicted for radio-luminous sources. Velocity shifts of the broad Hα components are analysed and the results found to be consistent with a two-component model comprising one single-peaked broad line emitted at the same redshift as the narrow lines, and emission from an accretion disc which appears to be preferentially redshifted with respect to the narrow lines for high-redshift sources and blueshifted relative to the narrow lines for low-redshift sources. An additional analysis is performed in which the disc emission is fixed at the redshift of the narrow-line region; although only two quasars show a robust change in fitted angle, the radio luminosity - disc angle correlation falls sharply in probability, and so is strongly model dependent in this sample. © 2009 RAS. Source


Siddique S.,Environmental Health Center | Banerjee M.,Indian Institute of Technology Guwahati | Ray M.R.,Chittaranjan National Cancer Institute | Lahiri T.,Nature
European Journal of Pediatrics | Year: 2011

The purpose of this study is to explore whether sustained exposure to vehicular air pollution affects the behavior and activities of children. The prevalence of attention-deficit hyperactivity disorder (ADHD) was assessed in two childhood populations. In a cross-sectional study 969 school-going children (9-17 years) and 850 age- and sex-matched children from rural areas were assessed, following the criteria of Diagnostic and Statistical Manual of conduct disorders (DSM-IV) of American Pediatric Association. Data of ambient particulate matter with a diameter of less than 10 μm (PM 10) were obtained from Central Pollution Control Board and aerosol monitor. ADHD was found in 11.0% of urban children in contrast to 2.7% of the control group (p<0.001). Major risk factors were male gender, lower socioeconomic status, 12-14 year age group, and PM 10 level in breathing air. ADHD was more prevalent among boys both in urban and rural areas. It was prevalent among 18.0% of the boys enrolled in Delhi against 4.0% of the girls, giving a male/female ratio of 4.5:1. Inattentive type of ADHD was predominant followed by hyperactive-impulsive type and combined type of ADHD. Controlling potential confounder, ambient PM 10 level was positively correlated with ADHD (OR=2.07; 95% CI, 1.08-3.99). Conclusion: The results of this study point to a possible association between air pollution and behavioral problems in children. Though gender, socioeconomic status, and age play a very important factor in ADHD prevalence, the association is highest and strongest between particulate pollution and prevalence of ADHD. © 2010 Springer-Verlag. Source


Campbell P.,Nature
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences | Year: 2011

Although much work has been done by scientists in developing communications to nonscientist audiences, much less attention has been given by them to the ways in which those messages are interpreted. Here, I look at the published work that examines the issue. I focus on three contexts in particular: debates over the triple vaccine for measles, mumps and rubella, the impacts of the Soufrière Hills volcano on the inhabitants of the island of Montserrat and the public communication of the results of climate change research. Several common themes emerge. The most important conclusions are that scientists communicating with the public need to develop their methods deliberatively, involving their target audiences; and that they need to avoid undue dependence on traditional media and public authorities for such communication, and to develop multiple channels to those audiences, including Internet-based and more traditional social networks. Their approach to communicating uncertainty should depend on the context but, except in some extreme emergencies, transparency is generally a virtue. Above all, they need to persist in such public engagements even when the going is rough and extends over long periods. They need support in doing so. This journal is © 2011 The Royal Society. Source

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