The social consequences of mild head injury and executive dysfunction /

Mild head injury (MHI) is a serious cause of neurological impairment as is evident by the substantial percentage (15%) of individuals who remain symptomatic at least 1-year following "mild" head trauma. However, there is a paucity of research investigating the social consequences following a MHI. The first objective of this study was to examine whether measures of executive functioning were predictive of specific forms of antisocial behaviour, such as reactive aggression, impulsive antisocial behaviour, behavioural disinhibition, and deficits in social awareness after controlling for the variance accounted for by sex differences. The second objective was to investigate whether a history of MHI was predictive of these same social consequences after controlling for both sex differences and executive functioning. Ninety university students participated in neuropsychological testing and filled out self-report questionnaires. Fifty-two percent of the sample self-reported experiencing a MHI. As expected, men were more reactively aggressive and antisocial than women. Furthermore, executive dysfunction predicted reactive aggression and impulsive antisocial behaviour after controlling for sex differences. Finally, as expected, MHI status predicted reactive aggression, impulsive antisocial behaviour, and behavioural disinhibition after controlling for sex and executive fimctioning. MHI status and executive functioning did not predict social awareness or sensitivity to reward or punishment. These results suggest that incurring a MHI has serious social consequences that mirror the neurobehavioural profile following severe cases of brain injury. Therefore, the social sequelae after MHI imply a continuum of behavioural deficits between MHI and more severe forms of brain injury.

The Molecular Consequences of CK2-mediated Phosphorylation of the TGA2 Transcription Factor within Systemic Acquired Resistance of Arabidopsis thaliana

During infection, the model plant Arabidopsis thaliana is capable of activating long lasting defence responses both in tissue directly affected by the pathogen and in more distal tissue. Systemic acquired resistance (SAR) is a type of systemic defence response deployed against biotrophic pathogens resulting in altered plant gene expression and production of antimicrobial compounds. One such gene involved in plant defence is called pathogenesis-related 1 (PR1) and is under the control of several protein regulators. TGA II-clade transcription factors (namely TGA2) repress PR1 activity prior to infection by forming large oligomeric complexes effectively blocking gene transcription. After pathogen detection, these complexes are dispersed by a mechanism unknown until now and free TGA molecules interact with the non-expressor of pathogenesis-related gene 1 (NPR1) protein forming an activating complex enabling PR1 transcription. This study elucidates the TGA2 dissociation mechanism by introducing protein kinase CK2 into this process. This enzyme efficiently phosphorylates TGA2 resulting in two crucial events. Firstly, the DNA-binding ability of this transcription factor is completely abolished explaining how the large TGA2 complexes are quickly evicted from the PR1 promoter. Secondly, a portion of TGA2 molecules dissociate from the complexes after phosphorylation which likely makes them available for the formation of the TGA2-NPR1 activating complex. We also show that phosphorylation of a multiserine motif found within TGA2’s N terminus is responsible for the change of affinity to DNA, while modification of a single threonine in the leucine zipper domain seems to be responsible for deoligomerization. Despite the substantial changes caused by phosphorylation, TGA2 is still capable of interacting with NPR1 and these proteins together form a complex on DNA promoting PR1 transcription. Therefore, we propose a change in the current model of how PR1 is regulated by adding CK2 which targets TGA2 displacing it’s complexes from the promoter and providing solitary TGA2 molecules for assembly of the activating complex. Amino acid sequences of regions targeted by CK2 in Arabidopsis TGA2 are similar to those found in TGA2 homologs in rice and tobacco. Therefore, the molecular mechanism that we have identified may be conserved among various plants, including important crop species, adding to the significance of our findings.

The Logical Problem of Language Change

This paper considers the problem of language change. Linguists must explain not only how languages are learned but also how and why they have evolved along certain trajectories and not others. While the language learning problem has focused on the behavior of individuals and how they acquire a particular grammar from a class of grammars ${cal G}$, here we consider a population of such learners and investigate the emergent, global population characteristics of linguistic communities over several generations. We argue that language change follows logically from specific assumptions about grammatical theories and learning paradigms. In particular, we are able to transform parameterized theories and memoryless acquisition algorithms into grammatical dynamical systems, whose evolution depicts a population's evolving linguistic composition. We investigate the linguistic and computational consequences of this model, showing that the formalization allows one to ask questions about diachronic that one otherwise could not ask, such as the effect of varying initial conditions on the resulting diachronic trajectories. From a more programmatic perspective, we give an example of how the dynamical system model for language change can serve as a way to distinguish among alternative grammatical theories, introducing a formal diachronic adequacy criterion for linguistic theories.

A review of the potential impacts of climate change on surface water quality

It is now accepted that some human-induced climate change is unavoidable. Potential impacts on water supply have received much attention, but relatively little is known about the concomitant changes in water quality. Projected changes in air temperature and rainfall could affect river flows and, hence, the mobility and dilution of contaminants. Increased water temperatures will affect chemical reaction kinetics and, combined with deteriorations in quality, freshwater ecological status. With increased flows there will be changes in stream power and, hence, sediment loads with the potential to alter the morphology of rivers and the transfer of sediments to lakes, thereby impacting freshwater habitats in both lake and stream systems. This paper reviews such impacts through the lens of UK surface water quality. Widely accepted climate change scenarios suggest more frequent droughts in summer, as well as flash-flooding, leading to uncontrolled discharges from urban areas to receiving water courses and estuaries. Invasion by alien species is highly likely, as is migration of species within the UK adapting to changing temperatures and flow regimes. Lower flows, reduced velocities and, hence, higher water residence times in rivers and lakes will enhance the potential for toxic algal blooms and reduce dissolved oxygen levels. Upland streams could experience increased dissolved organic carbon and colour levels, requiring action at water treatment plants to prevent toxic by-products entering public water supplies. Storms that terminate drought periods will flush nutrients from urban and rural areas or generate acid pulses in acidified upland catchments. Policy responses to climate change, such as the growth of bio-fuels or emission controls, will further impact freshwater quality.

A moving-mesh finite element method and its application to the numerical solution of phase-change problems

A distributed Lagrangian moving-mesh finite element method is applied to problems involving changes of phase. The algorithm uses a distributed conservation principle to determine nodal mesh velocities, which are then used to move the nodes. The nodal values are obtained from an ALE (Arbitrary Lagrangian-Eulerian) equation, which represents a generalization of the original algorithm presented in Applied Numerical Mathematics, 54:450--469 (2005). Having described the details of the generalized algorithm it is validated on two test cases from the original paper and is then applied to one-phase and, for the first time, two-phase Stefan problems in one and two space dimensions, paying particular attention to the implementation of the interface boundary conditions. Results are presented to demonstrate the accuracy and the effectiveness of the method, including comparisons against analytical solutions where available.

The economic consequences of mortgage debt

Unsurprisingly, a great deal of attention has been paid to the economic consequences of the credit crunch. However, this paper shows that the credit crunch was preceded by a strong build-up of mortgage debt internationally, which, in the long run, could turn out to be more significant than the credit crunch itself. Indeed, the debt build-up suggests that the credit crunch is more likely to reoccur, because highly-indebted households have weaker buffers to withstand unexpected shocks to their incomes or to interest rates. The paper presents a model that can explain the debt build-up and changes to the distribution of debt between existing owners and first-time buyers, which hinders access to home-ownership for the latter, even amongst those households who would be considered as credit-worthy.

The distributional consequences of a fiscal food policy: evidence from the UK

The literature on fiscal food policies focuses on their effectiveness in altering diets and improving health, while this paper focuses on their welfare costs. A formal welfare economics framework is developed to calculate the combined individualistic and distributional impacts of a tax-subsidy. Distributional characteristics of foods targeted by a tax tend to be concentrated in lower-income households. Further, consumption of fruit and vegetables tends to be concentrated in higher-income households; therefore, a subsidy on such foods increases regressivity. Aggregate welfare changes that result from a fiscal food policy are found to range from an increase of 1.41 per cent to a reduction of 2.06 per cent according to whether a subsidy is included, the degree of inequality aversion, and whether substitution among foods is allowed.