6,078 research outputs found
Modelling take-up of Family Credit and Working Families' Tax Credit
Many people in the UK do not claim benefits to which they seem to be entitled. Amongst those of working-age, take-up rates for Family Credit ֠an in-work benefit available to those with children and working at least 16 hours a week ֠were the lowest of the main three means-tested benefits.
In 1999, the UK Government replaced Family Credit with Working Families' Tax Credit, which was more generous, and delivered in a different way from FC. As a prelude to further work (now published as an update to this in the final report), we have analysed the decision to take up FC, and how take-up changed during the initial 6 month phase-in period of WFTC.
Although there are differences in how well each records receipt of FC, we find reassuring similarities in comparable econometric models of take-up estimated on three different micro-data-sets. Entitlement, earnings, non-labour income, and education attainment are the most important determinants of FC take-up.
We investigated FC take-up in greater detail using only the Family Resources Survey. Social renters are more likely to claim FC than owner occupiers or those in the private rental market, and we find that housing benefit recipients seem to under-value the potential fall in HB when considering whether to claim FC. We find that the Family Credit childcare disregard had little impact on the likelihood of take-up.
Take-up of WFTC, conditional on entitlement, fell immediately after its introduction, compared to FC, but the majority of the effect is explained by the relatively low take-up rates of those families who were not previously entitled to FC. This is unsurprising, as we would not expect this group to have claimed WFTC on the first day of its existence. Work currently in progress is examining how take-up of WFTC, and the factors associated with take-up, changed between April 2000 and March 2003
Elaboration versus suppression of cued memories: influence of memory recall instruction and success on parietal lobe, default network, and hippocampal activity.
Functional imaging studies of episodic memory retrieval consistently report task-evoked and memory-related activity in the medial temporal lobe, default network and parietal lobe subregions. Associated components of memory retrieval, such as attention-shifts, search, retrieval success, and post-retrieval processing also influence regional activity, but these influences remain ill-defined. To better understand how top-down control affects the neural bases of memory retrieval, we examined how regional activity responses were modulated by task goals during recall success or failure. Specifically, activity was examined during memory suppression, recall, and elaborative recall of paired-associates. Parietal lobe was subdivided into dorsal (BA 7), posterior ventral (BA 39), and anterior ventral (BA 40) regions, which were investigated separately to examine hypothesized distinctions in sub-regional functional responses related to differential attention-to-memory and memory strength. Top-down suppression of recall abolished memory strength effects in BA 39, which showed a task-negative response, and BA 40, which showed a task-positive response. The task-negative response in default network showed greater negatively-deflected signal for forgotten pairs when task goals required recall. Hippocampal activity was task-positive and was influenced by memory strength only when task goals required recall. As in previous studies, we show a memory strength effect in parietal lobe and hippocampus, but we show that this effect is top-down controlled and sensitive to whether the subject is trying to suppress or retrieve a memory. These regions are all implicated in memory recall, but their individual activity patterns show distinct memory-strength-related responses when task goals are varied. In parietal lobe, default network, and hippocampus, top-down control can override the commonly identified effects of memory strength
Virtual light-by-light scattering and the g factor of a bound electron
The contribution of the light-by-light diagram to the g factor of electron
and muon bound in Coulomb field is obtained. For electron in a ground state,
our results are in good agreement with the results of other authors obtained
numerically for large Z. For relatively small Z our results have essentially
higher accuracy as compared to the previous ones. For muonic atoms, the
contribution is obtained for the first time with the high accuracy in whole
region of Z.Comment: 10 pages, 3 figures, RevTe
Search-Related Suppression of Hippocampus and Default Network Activity during Associative Memory Retrieval
Episodic memory retrieval involves the coordinated interaction of several cognitive processing stages such as mental search, access to a memory store, associative re-encoding, and post-retrieval monitoring. The neural response during memory retrieval is an integration of signals from multiple regions that may subserve supportive cognitive control, attention, sensory association, encoding, or working memory functions. It is particularly challenging to dissociate contributions of these distinct components to brain responses in regions such as the hippocampus, which lies at the interface between overlapping memory encoding and retrieval, and “default” networks. In the present study, event-related functional magnetic resonance imaging (fMRI) and measures of memory performance were used to differentiate brain responses to memory search from subcomponents of episodic memory retrieval associated with successful recall. During the attempted retrieval of both poorly and strongly remembered word pair associates, the hemodynamic response was negatively deflected below baseline in anterior hippocampus and regions of the default network. Activations in anterior hippocampus were functionally distinct from those in posterior hippocampus and negatively correlated with response times. Thus, relative to the pre-stimulus period, the hippocampus shows reduced activity during intensive engagement in episodic memory search. Such deactivation was most salient during trials that engaged only pre-retrieval search processes in the absence of successful recollection or post-retrieval processing. Implications for interpretation of hippocampal fMRI responses during retrieval are discussed. A model is presented to interpret such activations as representing modulation of encoding-related activity, rather than retrieval-related activity. Engagement in intensive mental search may reduce neural and attentional resources that are otherwise tonically devoted to encoding an individual’s stream of experience into episodic memory
Muon-spin-rotation measurements of the penetration depth in Li_2Pd_3B
Measurements of the magnetic field penetration depth in the ternary
boride superconductor LiPdB ( K) have been carried out by
means of muon-spin rotation (SR). The absolute values of , the
Ginzburg-Landau parameter , and the first and the second
critical fields at T=0 obtained from SR were found to be
nm, , mT, and
T, respectively. The zero-temperature value of the
superconducting gap 1.31(3) meV was found, corresponding to the
ratio . At low temperatures saturates and
becomes constant below , in agreement with what is expected for
s-wave BCS superconductors. Our results suggest that LiPdB is a s-wave
BCS superconductor with the only one isotropic energy gap.Comment: 6 pages, 7 figure
The use of geomorphological mapping and modelling for identifying land affected by metal contamination on river floodplains
Local Magnetic Susceptibility of the Positive Muon in the Quasi 1D S=1/2 Antiferromagnet KCuF
We report muon spin rotation measurements of the local magnetic
susceptibility around a positive muon in the paramagnetic state of the quasi
one-dimensional spin 1/2 antiferromagnet KCuF. Signals from two distinct
sites are resolved which have a temperature dependent frequency shift which is
different than the magnetic susceptibility. This difference is attributed to a
muon induced perturbation of the spin 1/2 chain.Comment: 13 pages, 4 figures, The 2002 International Conference on Muon Spin
Rotation, Relaxation and Resonance, Virginia. US
Dissecting magnetar variability with Bayesian hierarchical models
Neutron stars are a prime laboratory for testing physical processes under
conditions of strong gravity, high density, and extreme magnetic fields. Among
the zoo of neutron star phenomena, magnetars stand out for their bursting
behaviour, ranging from extremely bright, rare giant flares to numerous, less
energetic recurrent bursts. The exact trigger and emission mechanisms for these
bursts are not known; favoured models involve either a crust fracture and
subsequent energy release into the magnetosphere, or explosive reconnection of
magnetic field lines. In the absence of a predictive model, understanding the
physical processes responsible for magnetar burst variability is difficult.
Here, we develop an empirical model that decomposes magnetar bursts into a
superposition of small spike-like features with a simple functional form, where
the number of model components is itself part of the inference problem. The
cascades of spikes that we model might be formed by avalanches of reconnection,
or crust rupture aftershocks. Using Markov Chain Monte Carlo (MCMC) sampling
augmented with reversible jumps between models with different numbers of
parameters, we characterise the posterior distributions of the model parameters
and the number of components per burst. We relate these model parameters to
physical quantities in the system, and show for the first time that the
variability within a burst does not conform to predictions from ideas of
self-organised criticality. We also examine how well the properties of the
spikes fit the predictions of simplified cascade models for the different
trigger mechanisms.Comment: accepted for publication in The Astrophysical Journal; code available
at https://bitbucket.org/dhuppenkothen/magnetron, data products at
http://figshare.com/articles/SGR_J1550_5418_magnetron_data/129242
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