Dependence of the ion energy on the parameters of the laser pulse and target in the radiation-pressure-dominated regime of acceleration

When the dominant mechanism for ion acceleration is the laser radiation pressure, the conversion efficiency of the laser energy into the energy of relativistic ions may be very high. Stability analysis of a thin plasma layer accelerated by the radiation pressure shows that Raleigh-Taylor instability may enhance plasma inhomogeneity. In the linear stage of instability, the plasma layer decays into separate bunches, which are accelerated by the radiation pressure similarly to clusters accelerated under the action of an electromagnetic wave. The energy and luminosity of an ion beam accelerated in the radiation-pressure-dominated regime are calculated.

Enhanced Laser-Driven Ion Acceleration in the Relativistic Transparency Regime

We report on the acceleration of ion beams from ultrathin diamondlike carbon foils of thickness 50, 30, and 10 nm irradiated by ultrahigh contrast laser pulses at intensities of similar to 7 X 10(19) W/cm(2). An unprecedented maximum energy of 185 MeV (15 MeV/u) for fully ionized carbon atoms is observed at the optimum thickness of 30 nm. The enhanced acceleration is attributed to self-induced transparency, leading to strong volumetric heating of the classically overdense electron population in the bulk of the target. Our experimental results are supported by both particle-in-cell (PIC) simulations and an analytical model.

The inferential monitoring of the screw disturbance torque to predict process fluctuations in polymer extrusion

Polymer extrusion is one of the major methods of processing polymer materials and advanced process monitoring is important to ensure good product quality. However, commonly used process monitoring devices, e.g. temperature and pressure sensors, are limited in providing information on process dynamics inside an extruder barrel. Screw load torque dynamics, which may occur due to changes in solids conveying, melting, mixing, melt conveying, etc., are believed to be a useful indicator of process fluctuations inside the extruder barrel. However, practical measurement of the screw load torque is difficult to achieve. In this work, inferential monitoring of the screw load torque signal in an extruder was shown to be possible by monitoring the motor current (armature and/or field) and simulation studies were used to check the accuracy of the proposed method. The ability of this signal to aid identification and diagnosis of process issues was explored through an experimental investigation. Power spectral density and wavelet frequency analysis were implemented together with a covariance analysis. It was shown that the torque signal is dominated by the solid friction in the extruder and hence it did not correlate well with melting fluctuations. However, it is useful for online identification of solids conveying issues.

Regulatory regime change in Turkish banks:Reactive or proactive?

This paper examines the positive contributions made toward restructuring the regulatory framework of Turkey's banking and financial sectors prior to and post the 2000–2001 financial crisis. Drawing on a framework initially developed by Onis and Senses, 2007 and Onis and Senses, 2009 and further referred to by Onis, 2009 and Onis, 2010 it argues that financial reforms undertaken by the Turkish government would not have been successful without the strong support of domestic coalitions. While the external pressures put on the Turkish government from the International Monetary Fund, The World Bank and the European Union for financial reforms were necessary to kick start the reforms as a reactive process, these pressures on their own may have served only the interests of financial business elites at the expense of the broader stakeholders. Empirical data for the study was collected from documentary analysis of key financial institutions and interviews with twenty major Turkish regulatory agents and other stakeholders. The paper then discusses how the perceptions of these stakeholders are embodied into, and have influenced, regulatory regime change in Turkey from a reactive state to a more proactive one.

Plasma surface dynamics and smoothing in the relativistic few-cycle regime

Efficient production of coherent harmonic radiation from solid targets relies critically on the formation of smooth, short density scalelength plasmas. Recent experimental results (Dromey et al 2009 Nat. Phys. 5 146) suggest, however, that the target roughness on the scale of the emitted harmonic wavelength does not result in diffuse reflection-in apparent contradiction to the Rayleigh criterion for coherent reflection. In this paper we show, for the first time, using analytic theory and 2D PIC simulations, that the interaction of relativistically strong laser pulses with corrugated target surfaces results in a highly effective smoothing of the interaction surface and consequently the generation of highly collimated and temporally confined XUV pulses from rough targets, in excellent agreement with experimental observations.

Spectral Enhancement in the Double Pulse Regime of Laser Proton Acceleration

The use of two separate ultraintense laser pulses in laser-proton acceleration was compared to the single pulse case employing the same total laser energy. A double pulse profile, with the temporal separation of the pulses varied between 0.75-2.5 ps, was shown to result in an increased maximum proton energy and an increase in conversion efficiency to fast protons by up to a factor of 3.3. Particle-in-cell simulations indicate the existence of a two stage acceleration process. The second phase, induced by the main pulse preferentially accelerates slower protons located deeper in the plasma, in contrast to conventional target normal sheath acceleration.

TRANSITION TO FILAMENTARY REGIME IN LASER-PLASMA INTERACTION EVIDENCED BY 2-OMEGA-EMISSION

The level of second-harmonic light emitted from a laser-exploded foil plasma at nominal irradiance up to 3.10(13) W/cm2 was found to be extremely sensitive to both target position and irradiance on target. Either a small target displacement or a small increase in irradiance resulted in a jump of the 2omega level of more than three orders of magnitude. Correspondingly, a transition was observed from a 2omega source pattern clearly signed by the original laser spot pattern to unstable patterns of filaments whose size is consistent with the maximum growth of the instability.

Influence of aggregate and curing regime on the mechanical properties of ultra-high performance fibre reinforced concrete (UHPFRC)

A new generation of concrete, Ultra-high performance fibre reinforced concrete (UHPFRC) has been developed for its outstanding mechanical performance and shows a very promising future in construction applications. In this paper, several possibilities are examined for reducing the price of producing UHPFRC and for bringing UHPFRC away from solely precast applications and onto the construction site as an in situ material. Recycled glass cullet and two types of local natural sand were examined as replacement materials for the more expensive silica sand normally used to produce UHPFRC. In addition, curing of UHPFRC cubes and prisms at 20 degrees C and 90 degrees C has been investigated to determine differences in both mechanical and ductility.

Components of Shame and Eating Disturbance among Clinical and Non-Clinical Populations

OBJECTIVE: To examine the association between components of shame (characterological, behavioural and bodily) and eating disturbance.

METHOD: This was a cross sectional study of 859 female and 256 male participants from the general population [non-clinical (NCP)] and 167 female participants from an eating disordered population [clinical (CP)] completing the Experience of Shame Scale. The NCP samples also completed the Eating Attitudes Test-26, and the CP samples completed the Eating Disorder Risk Composite of the Eating Disorder Inventory-3. Participants were recruited via schools/colleges, eating disorder charities and the Internet.

RESULTS: Bodily and characterological shame were independently predictive of eating disturbance in female NCP samples (both, p?<?.001); bodily shame was uniquely predictive of eating disturbance for the male NCP (p?<?.05) and female CP samples (p?<?.001).

CONCLUSION: The aetiology of eating disturbance may be different for male and female NCP samples. The male NCP and the female CP samples displayed a similar pathway to eating disturbance. It is important to acknowledge the different components of shame associated with eating disturbance in different populations.