12,902 research outputs found
Extraction of comprehensible logical rules from neural networks: application of TREPAN in bio and cheminformatics
The colour of the narrow line Sy1-blazar 0324+3410
Aims. We investigate the properties of the host galaxy of the blazar
J0324+3410 (B2 0321+33) by the analysis of B and R images obtained with the NOT
under good photometric conditions. Methods: The galaxy was studied using
different methods: Sersic model fitting, unsharp-masked images, B-R image and
B-R profile analysis. Results: The images show that the host galaxy has a
ring-like morphology. The B-R colour image reveals two bluish zones: one that
coincides with the nuclear region, interpreted as the signature of emission
related to the active nucleus, the other zone is extended and is located in the
host ring-structure. We discuss the hypothesis that the later is thermal
emission from a burst of star formation triggered by an interacting/merging
process
Pensioner poverty over the next decade: what role for tax and benefit reform?
Recent falls in poverty amongst those aged 65 and over are unlikely to continue after 2007-08, even after the implementation of the proposals outlined in the Government's Pensions White Paper.
This report looks at the prospects for pensioner poverty in England over the next decade. The authors find that that the proportion of those aged 65 and over living in poverty is set to remain at its current level - around one-in-five - between 2007-08 and 2017-18. This is despite the overall increase in the generosity of state pensions arising from the Pensions White Paper, and the fact that younger cohorts are expected to have more private pension income and higher employment rates at older ages than those preceding them
Blueprint for fault-tolerant quantum computation with Rydberg atoms
We present a blueprint for building a fault-tolerant universal quantum computer with Rydberg atoms. Our scheme, which is based on the surface code, uses individually addressable, optically trapped atoms as qubits and exploits electromagnetically induced transparency to perform the multiqubit gates required for error correction and computation. We discuss the advantages and challenges of using Rydberg atoms to build such a quantum computer, and we perform error correction simulations to obtain an error threshold for our scheme. Our findings suggest that Rydberg atoms are a promising candidate for quantum computation, but gate fidelities need to improve before fault-tolerant universal quantum computation can be achieved
ARCS, The Arcminute Radio Cluster-lens Search - I. Selection Criteria and Initial Results
We present the results of an unbiased radio search for gravitational lensing
events with image separations between 15 and 60 arcsec, which would be
associated with clusters of galaxies with masses >10^{13-14}M_{\sun}. A parent
population of 1023 extended radio sources stronger than 35 mJy with stellar
optical identifications was selected using the FIRST radio catalogue at 1.4 GHz
and the APM optical catalogue. The FIRST catalogue was then searched for
companions to the parent sources stronger than 7 mJy and with separation in the
range 15 to 60 arcsec. Higher resolution observations of the resulting 38 lens
candidates were made with the VLA at 1.4 GHz and 5 GHz, and with MERLIN at 5
GHz in order to test the lens hypothesis in each case. None of our targets was
found to be a gravitational lens system. These results provide the best current
constraint on the lensing rate for this angular scale, but improved
calculations of lensing rates from realistic simulations of the clustering of
matter on the relevant scales are required before cosmologically significant
constraints can be derived from this null result. We now have an efficient,
tested observational strategy with which it will be possible to make an
order-of-magnitude larger unbiased search in the near future.Comment: Accepted for publication in MNRAS. 12 pages, 29 included PostScript
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The Co-occurrence of child and intimate partner maltreatment in the family: characteristics of the violent perpetrators
This study considers the characteristics associated with mothers and fathers who maltreat their child and each other in comparison to parents who only maltreat their child. One hundred and sixty-two parents who had allegations of child maltreatment made against them were considered. The sample consisted of 43 fathers (Paternal Family—PF) and 23 mothers (Maternal Family—MF) who perpetrated both partner and child maltreatment, together with 23 fathers (Paternal Child—PC) and 26 mothers (Maternal Child—MC) who perpetrated child maltreatment only. In addition, 2 fathers (Paternal Victim—PV) and 23 mothers (Maternal Victim—MV) were victims of intimate partner maltreatment and perpetrators of child maltreatment and 7 fathers (Paternal Non-abusive Carer—PNC) and 15 mothers (Maternal Non-abusive Carer—MNC) did not maltreat the child but lived with an individual who did. Within their family unit, 40.7% of parents perpetrated both intimate partner and child maltreatment. However, fathers were significantly more likely to maltreat both their partner and child than mothers and mothers were significantly more likely to be victims of intimate partner violence than fathers. PF fathers conducted the highest amount of physical and/or sexual child maltreatment while MC and MV mothers perpetrated the highest amount of child neglect. Few significant differences between mothers were found. PF fathers had significantly more factors associated with development of a criminogenic lifestyle than PC fathers. Marked sex differences were demonstrated with PF fathers demonstrating significantly more antisocial characteristics, less mental health problems and fewer feelings of isolation than MF mothers. MC mothers had significantly more childhood abuse, mental health problems, parenting risk factors and were significantly more likely to be biologically related to the child than PC fathers. This study suggests that violent families should be assessed and treated in a holistic manner, considering the effects of partner violence upon all family members, rather than exclusively intervening with the violent man
Quantum Criticality and Incipient Phase Separation in the Thermodynamic Properties of the Hubbard Model
Transport measurements on the cuprates suggest the presence of a quantum
critical point hiding underneath the superconducting dome near optimal hole
doping. We provide numerical evidence in support of this scenario via a
dynamical cluster quantum Monte Carlo study of the extended two-dimensional
Hubbard model. Single particle quantities, such as the spectral function, the
quasiparticle weight and the entropy, display a crossover between two distinct
ground states: a Fermi liquid at low filling and a non-Fermi liquid with a
pseudogap at high filling. Both states are found to cross over to a marginal
Fermi-liquid state at higher temperatures. For finite next-nearest-neighbor
hopping t' we find a classical critical point at temperature T_c. This
classical critical point is found to be associated with a phase separation
transition between a compressible Mott gas and an incompressible Mott liquid
corresponding to the Fermi liquid and the pseudogap state, respectively. Since
the critical temperature T_c extrapolates to zero as t' vanishes, we conclude
that a quantum critical point connects the Fermi-liquid to the pseudogap
region, and that the marginal-Fermi-liquid behavior in its vicinity is the
analogous of the supercritical region in the liquid-gas transition.Comment: 18 pages, 9 figure
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