147 research outputs found
False investigators and coercive citation are widespread in academic research
A recent study has revealed widespread unethical behaviour in academic research. Allen Wilhite focuses on two activities in particular; the addition to funding proposals of investigators not expected to contribute to the research, and editors who coerce authors to add citations to manuscripts even though those citations were not part of the scholars' reference material. Research institutions, funders, rankings bodies, and scholars themselves can and should do more to address such behaviours
An extension of the SHARC survey
We report on our search for distant clusters of galaxies based on optical and
X-ray follow up observations of X-ray candidates from the SHARC survey. Based
on the assumption that the absence of bright optical or radio counterparts to
possibly extended X-ray sources could be distant clusters. We have obtained
deep optical images and redshifts for several of these objects and analyzed
archive XMM-Newton or Chandra data where applicable. In our list of candidate
clusters, two are probably galaxy structures at redshifts of z0.51 and
0.28. Seven other structures are possibly galaxy clusters between z0.3
and 1. Three sources are identified with QSOs and are thus likely to be X-ray
point sources, and six more also probably fall in this category. One X-ray
source is spurious or variable. For 17 other sources, the data are too sparse
at this time to put forward any hypothesis on their nature. We also
serendipitously detected a cluster at z=0.53 and another galaxy concentration
which is probably a structure with a redshift in the [0.15-0.6] range. We
discuss these results within the context of future space missions to
demonstrate the necessity of a wide field of view telescope optimized for the
0.5-2 keV range.Comment: Accepted in A&
Shining Light on Merging Galaxies I: The Ongoing Merger of a Quasar with a `Green Valley' Galaxy
Serendipitous observations of a pair z = 0.37 interacting galaxies (one
hosting a quasar) show a massive gaseous bridge of material connecting the two
objects. This bridge is photoionized by the quasar (QSO) revealing gas along
the entire projected 38 kpc sightline connecting the two galaxies. The emission
lines that result give an unprecedented opportunity to study the merger process
at this redshift. We determine the kinematics, ionization parameter (log U ~
-2.5 +- 0.03), column density (N_H ~ 10^{21} cm^{-2}), metallicity ([M/H] ~
-0.20 +- 0.15), and mass (~ 10^8 Msun) of the gaseous bridge. We simultaneously
constrain properties of the QSO-host (M_DM>8.8x 10^{11} Msun) and its companion
galaxy (M_DM>2.1 x 10^{11} Msun; M_star ~ 2 x 10^{10} Msun; stellar burst
age=300-800 Myr; SFR~6 Msun/yr; and metallicity 12+log (O/H)= 8.64 +- 0.2). The
general properties of this system match the standard paradigm of a
galaxy-galaxy merger caught between first and second passage while one of the
galaxies hosts an active quasar. The companion galaxy lies in the so-called
`green valley', with a stellar population consistent with a recent starburst
triggered during the first passage of the merger and has no detectable AGN
activity. In addition to providing case-studies of quasars associated with
galaxy mergers, quasar/galaxy pairs with QSO-photoionized tidal bridges such as
this one offer unique insights into the galaxy properties while also
distinguishing an important and inadequately understood phase of galaxy
evolution.Comment: 23 pages, 12 figures, 5 tables, Submitted to ApJ, revised to address
referee's comment
The question of energy reduction: The problem(s) with feedback
With smart metering initiatives gaining increasing global popularity, the present paper seeks to challenge the increasingly entrenched view that providing householders with feedback about their energy usage, via an in-home-display, will lead them to substantially reduce their energy consumption. Specifically, we draw on existing quantitative and qualitative evidence to outline three key problems with feedback, namely: (a) the limited evidence of efficacy, (b) the need for user engagement, and (c) the potential for unintended consequences. We conclude by noting that, in their current form, existing in-home-displays may not induce the desired energy-reduction response anticipated by smart metering initiatives. Instead, if smart metering is to effectively reduce energy consumption there is a clear need to develop and test innovative new feedback devices that have been designed with user engagement in mind
Heterogeneous beliefs in over-the-counter markets
The behavior and stability of over-the-counter markets is of central concern to regulators. Little is known, however, about how the structure of these markets determine their properties. In this paper we consider an over-the-counter market populated by boundedly rational heterogeneous traders in which the structure is represented by a network. Stability is found to decrease as the market becomes less well connected, however, the configuration of connections has a significant effect. The presence of hubs, such as those found in scale free networks increases stability and decreases volatility whilst small-world short-cut links have the opposite effect. Volatility in the fundamental value increases market volatility, however, volatility in the riskless asset returns has an ambiguous effect
Unusual quasars from the Sloan Digital Sky Survey selected by means of Kohonen self-organising maps
We exploit the spectral archive of the Sloan Digital Sky Survey (SDSS) Data
Release 7 to select unusual quasar spectra. The selection method is based on a
combination of the power of self-organising maps and the visual inspection of a
huge number of spectra. Self-organising maps were applied to nearly 10^5
spectra classified as quasars by the SDSS pipeline. Particular attention was
paid to minimise possible contamination by rare peculiar stellar spectral
types. We present a catalogue of 1005 quasars with unusual spectra. This large
sample provides a useful resource for both studying properties and relations
of/between different types of unusual quasars and selecting particularly
interesting objects. The spectra are grouped into six types. All these types
turn out to be on average more luminous than comparison samples of normal
quasars after a statistical correction is made for intrinsic reddening. Both
the unusual broad absorption line (BAL) quasars and the strong iron emitters
have significantly lower radio luminosities than normal quasars. We also
confirm that strong BALs avoid the most radio-luminous quasars. Finally, we
create a sample of quasars similar to the two "mysterious" objects discovered
by Hall et al. (2002) and briefly discuss the quasar properties and possible
explanations of their highly peculiar spectra. (Abstract modified to match the
arXiv format)Comment: Added reference to section 6; a few typos corrected; corrections
according to the version published in Astronomy and Astrophysic
Dinosaur Speed Demon: The Caudal Musculature of Carnotaurus sastrei and Implications for the Evolution of South American Abelisaurids
In the South American abelisaurids Carnotaurus sastrei, Aucasaurus garridoi, and, to a lesser extent Skorpiovenator bustingorryi, the anterior caudal ribs project at a high dorsolateral inclination and have interlocking lateral tips. This unique morphology facilitated the expansion of the caudal hypaxial musculature at the expense of the epaxial musculature. Distinct ridges on the ventrolateral surfaces of the caudal ribs of Aucasaurus garridoi are interpreted as attachment scars from the intra caudofemoralis/ilio-ischiocaudalis septa, and confirm that the M. caudofemoralis of advanced South American abelisaurids originated from a portion of the caudal ribs. Digital muscle models indicate that, relative to its overall body size, Carnotaurus sastrei had a substantially larger M. caudofemoralis than any other theropod yet studied. In most non-avian theropods, as in many extant sauropsids, the M. caudofemoralis served as the primary femoral retractor muscle during the locomotive power stroke. This large investment in the M. caudofemoralis suggests that Carnotaurus sastrei had the potential for great cursorial abilities, particularly short-burst sprinting. However, the tightly interlocking morphology of the anterior caudal vertebrae implies a reduced ability to make tight turns. Examination of these vertebral traits in evolutionary context reveals a progressive sequence of increasing caudofemoral mass and tail rigidity among the Abelisauridae of South America
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