Spontaneous nucleation of structural defects in inhomogeneous ion chains

Structural defects in ion crystals can be formed during a linear quench of the transverse trapping frequency across the mechanical instability from a linear chain to a zigzag structure. The density of defects after the sweep can be conveniently described by the Kibble-Zurek mechanism (KZM). In particular, the number of kinks in the zigzag ordering can be derived from a time-dependent Ginzburg-Landau equation for the order parameter, here the zigzag transverse size, under the assumption that the ions are continuously laser cooled. In a linear Paul trap, the transition becomes inhomogeneous, since the charge density is larger in the center and more rarefied at the edges. During the linear quench, the mechanical instability is first crossed in the center of the chain, and a front, at which the mechanical instability is crossed during the quench, is identified that propagates along the chain from the center to the edges. If the velocity of this front is smaller than the sound velocity, the dynamics become adiabatic even in the thermodynamic limit and no defect is produced. Otherwise, the nucleation of kinks is reduced with respect to the case in which the charges are homogeneously distributed, leading to a new scaling of the density of kinks with the quenching rate. The analytical predictions are verified numerically by integrating the Langevin equations of motion of the ions, in the presence of a time-dependent transverse confinement. We argue that the non-equilibrium dynamics of an ion chain in a Paul trap constitutes an ideal scenario to test the inhomogeneous extension of the KZM, which lacks experimental evidence to date.

Structural Defects in Ion Chains by Quenching the External Potential: The Inhomogeneous Kibble-Zurek Mechanism

The nonequilibrium dynamics of an ion chain in a highly anisotropic trap is studied when the transverse trap frequency is quenched across the value at which the chain undergoes a continuous phase transition from a linear to a zigzag structure. Within Landau theory, an equation for the order parameter, corresponding to the transverse size of the zigzag structure, is determined when the vibrational motion is damped via laser cooling. The number of structural defects produced during a linear quench of the transverse trapping frequency is predicted and verified numerically. It is shown to obey the scaling predicted by the Kibble-Zurek mechanism, when extended to take into account the spatial inhomogeneities of the ion chain in a linear Paul trap.

Study of structural change in Wyodak coal in high pressure CO2 by small-angle neutron scattering

Small angle neutron scattering (SANS) has been applied to examine the effect of high pressure CO2 on the structure of Wyodak coal. Significant decrease in the scattering intensities upon exposure of the coal to high pressure CO2 showed that high pressure CO2 rapidly adsorbs on the coal and reaches to all pores in the structure. This is confirmed by strong and steep exothermic peaks observed on DSC scans during coal/ CO2 interactions. In situ small angle neutron scattering on coal at high pressure CO2 atmosphere showed an increase in scattering intensities with time suggesting that after adsorption, high pressure CO2 immediately begins to diffuse into the coal matrix, changes the macromolecular structure of the coal, swells the matrix and probably creates microporosity in coal structure by extraction of volatile components from coal. Significant decrease in the glass transition temperature of coal caused by high pressure CO2 also confirms that CO2 at elevated pressures dissolve in the coal matrix, results in significant plasticization and physical rearrangement of the coal’s macromolecular structure.

A voxel based morphometry study investigating brain structural changes in first episode psychosis.

Schizophrenia (SCZ) and bipolar disorder (BP) are associated with neuropathological brain changes, which are believed to disrupt connectivity between brain processes and may have common properties. Patients at first psychotic episode are unique, as one can assess brain alterations at illness inception, when many confounders are reduced or absent. SCZ (N=25) and BP (N=24) patients were recruited in a regional first episode psychosis MRI study. VBM methods were used to study gray matter (GM) and white matter (WM) differences between patient groups and case by case matched controls. For both groups, deficits identified are more discrete than those typically reported in later stages of illness. SCZ patients showed some evidence of GM loss in cortical areas but most notable were in limbic structures such as hippocampus, thalamus and striatum and cerebellum. Consistent with disturbed neural connectivity WM alterations were also observed in limbic structures, the corpus callosum and many subgyral and sublobar regions in the parietal, temporal and frontal lobes. BP patients displayed less evidence of volume changes overall, compared to normal healthy participants, but those changes observed were primarily in WM areas which overlapped with regions identified in SCZ, including thalamus and cerebellum and subgyral and sublobar sites. At first episode of psychosis there is evidence of a neuroanatomical overlap between SCZ and BP with respect to brain structural changes, consistent with disturbed neural connectivity. There are also important differences however in that SCZ displays more extensive structural alteration.

Structural changes in the hippocampus and amygdala at first episode of psychosis

Hippocampus and amygdala changes have been implicated in the pathophysiology and symptomatology of both schizophrenia (SCZ) and bipolar disorder (BD). However relationships between illness course, neuropathological changes and variations in symptomatology remain unclear. This investigation examined the associations between hippocampus and amygdala volumes and symptom dimensions in schizophrenia and bipolar disorder patients after their first episode of psychosis. Symptom severity was associated with decreases in hippocampus/amygdala complex volume across groups. In keeping with previous work bilateral hippocampus and amygdala volume reductions were also identified in the SCZ patients while in BD patients only evidence of amygdala inflation reached significance. The study concludes that there appear to be important relationships between volume changes in the hippocampus and amygdala and dimensions and severity of symptomatology in psychosis. Structural alterations are apparent in both SCZ and BD after first episode of psychosis but present differently in each illness and are more severe in SCZ.

Justice as Fairness in Planning Policy-Making

This paper considers a moral basis for planning theory and endeavours to establish principles of justice which might be relevant to the regulation of development. Whilst the investigation recognises that there is a need for a deeper understanding of the dynamics of governance, it suggests that many of the inefficiencies, inequities and public disquiet concerns relating to planning centre on a drift from a perception that the system is both fair and just, and that practice needs to be anchored on founding values concerned with redistribution and equality. In this context, John Rawls’ theory of justice is employed as a vehicle to capture moral ideas of equality and liberty within a constitutional democracy and as a basis for scrutinising emerging justice based issues which impact upon planning. Using National Policy Statements as a case study, the paper concludes that, whilst there are serious concerns over current policymaking practices, the principles of justice offer a foundation for practical critique which can help overcome problems of mistrust.

The use of Ecological and Carbon Footprint Analysis in regional policy making: application and insights using the REAP model

This paper builds on and extends previous research to contribute to ongoing discussion on the use of resource and carbon accounting tools in regional policy making. The Northern Visions project has produced the first evidence-based footpath setting out the actions that need to be taken to achieve the step changes in the Ecological and Carbon Footprint of Northern Ireland. A range of policies and strategies were evaluated using the Resources and Energy Analysis Programme. The analysis provided the first regional evidence base that current sustainable development policy commitments would not lead to the necessary reductions in either the Ecological Footprint or carbon dioxide emissions. Building on previous applications of Ecological Footprint analysis in regional policy making, the research has demonstrated that there is a valuable role for Ecological and Carbon Footprint Analysis in policy appraisal. The use of Ecological and Carbon Footprint Analysis in regional policy making has been evaluated and recommendations made on ongoing methodological development. The authors hope that the research can provide insights for the ongoing use Ecological and Carbon Footprint Analysis in regional policy making and help set out the priorities for research to support this important policy area

The use of material flow analysis and the ecological footprint in regional policy-making: application and insights from Northern Ireland.

This paper aims to contribute to the ongoing debate on the use of resource accounting tools in regional policy making. The Northern Limits project applied Material Flow Analysis and Ecological Footprinting to regional policy making in Northern Ireland over a number of years. The early phase of the research informed the regions first sustainable development strategy which was published in 2006 with key targets relating to the Ecological Footprint and improving the resource efficiency of the economy. Phase II identified the next steps required to address data availability and quality and the use of MFA and EF in providing a measurement and monitoring framework for the strategy and in the development of the strategy implementation plan. The use of MFA and Ecological Footprinting in sustainable regional policy making and the monitoring of its implementation is an ongoing process which has raised a number of research issues which can inform the ongoing application and development of these and other resource accounting tools to within Northern Ireland, provide insights for their use in other regions and help set out the priorities for research to support this important policy area.