49,929 research outputs found
Evidence from the Very Long Baseline Array that J1502SE/SW are Double Hotspots, not a Supermassive Binary Black Hole
SDSS J150243.09+111557.3 is a merging system at z = 0.39 that hosts two
confirmed AGN, one unobscured and one dust-obscured, offset by several
kiloparsecs. Deane et al. recently reported evidence from the European VLBI
Network (EVN) that the dust-obscured AGN exhibits two flat-spectrum radio
sources, J1502SE/SW, offset by 26 mas (140 pc), with each source being
energized by its own supermassive black hole (BH). This intriguing
interpretation of a close binary BH was reached after ruling out a
double-hotspot scenario, wherein both hotspots are energized by a single,
central BH, a configuration occuring in the well-studied Compact Symmetric
Objects. When observed with sufficient sensitivity and resolution, an object
with double hotspots should have an edge-brightened structure. We report
evidence from the Very Long Baseline Array (VLBA) for just such a structure in
an image of the obscured AGN with higher sensitivity and resolution than the
EVN images. We thus conclude that a double-hotspot scenario should be
reconsidered as a viable interpretation for J1502SE/SW, and suggest further
VLBA tests of that scenario. A double-hotspot scenario could have broad
implications for feedback in obscured AGNs. We also report a VLBA detection of
high-brightness-temperature emssion from the unobscured AGN that is offset
several kiloparsecs from J1502SE/SW.Comment: 12 pages, 1 figure, accepted by ApJL on 2014 July 2
National counter-terrorism (C-T) policies and challenges to human rights and civil liberties: Case study of United Kingdom
In the UK the rise post-2005 in âhome-grownâ terrorism, relying to a significant extent on strikes on soft targets by âself-starters,â means that the search for effective preventive measures remains a continuing concern. Below a number of the preventive counter-terror measures adopted post-9/11, and incrementally strengthened in response to the current threat, are found to fall into three categories and represent interventions at the stages in the path toward attacks. This chapter focuses on selected examples of these preventive measures. In terms of three key stages, firstly, there is the attempt to prevent radicalization, under the âPreventâ strategy. A second strategy relies on taking certain measures to control the activities of those considered likely â on the balance of probabilities â to engage in terrorist-related activity. A third preventive strategy relies on the special terrorism offences under the Terrorism Acts 2000 and 2006, as amended, intended to allow for intervention at a very early stage in terrorist plots and in preparing or instigating terrorist acts (âprecursorâ offences)
Numerical residual perturbation solutions applied to the problem of a close satellite of the smaller body in the restricted three-body problem
Numerical residual perturbation solution for prediction of satellite position in restricted three-body proble
Molecular hydrogen in the young starburst in NGC 253
Shocked molecular hydrogen has been observed around the nucleus of the nearby galaxy, NGC 253. This galaxy has a relatively modest luminosity (approx. 3 x 10 to the 10th power solar luminosities) and appears to have no distortions or companions that would indicate a possible interaction. The energy of the galaxy appears to be derived primarily from a starburst. Thus, our observations have caused us to examine the starburst process in some detail to identify how the molecular hydrogen is excited. It is proposed that the molecular hydrogen emission is produced by collisions of dense molecular clouds accelerated by supernovae explosions. Within the nucleus, this process occurs early in the life of the starbust. This suggest a sequence of nuclear starburst development; examples along this sequence from young to old would include NGC 253, M82, NGC 1097, and M31
Study protocol for a randomised controlled trial of electronic cigarettes versus nicotine patch for smoking cessation
PMCID: PMC3602285This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
Stimulation of bioprocesses by ultrasound
Ultrasound (US) has become a ubiquitous technological process in a large variety of scientific disciplines. However, little information exists on the use of ultrasound to enhance biological processes and/or processing and consequently this paper provides an overview of work reported to date on this topic. This review provides a brief introduction to ultrasound and the history of ultrasound as applied to bioprocesses. This is followed by a discussion of the influence of US on discrete enzyme systems, enzymes used in bioremediation, microbial fermentations and enzymatic hydrolysis of biopolymers. Augmentation of anaerobic digestion by US is then considered along with enhancement of enzymes in food science and technology. The use of ultrasonically stimulated enzymes in synthesis is then considered and other relevant miscellaneous topics are described. It is concluded that the precise mechanism of action of US in bio-processing remains to be elucidated though a variety of plausible suggestions are made
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