Plasma ion evolution in the wake of a high-intensity ultrashort laser pulse

Experimental investigations of the late-time ion structures formed in the wake of an ultrashort, intense laser pulse propagating in a tenuous plasma have been performed using the proton imaging technique. The pattern found in the wake of the laser pulse shows unexpectedly regular modulations inside a long, finite width channel. On the basis of extensive particle in cell simulations of the plasma evolution in the wake of the pulse, we interpret this pattern as due to ion modulations developed during a two-stream instability excited by the return electric current generated by the wakefield.

Observation of Magnetized Soliton Remnants in the Wake of Intense Laser Pulse Propagation through Plasmas

Slowly evolving, regularly spaced patterns have been observed in proton projection images of plasma channels drilled by intense (greater than or similar to 10(19) W cm(-2)) short (similar to 1 ps) laser pulses propagating in an ionized gas jet. The nature and geometry of the electromagnetic fields generating such patterns have been inferred by simulating the laser-plasma interaction and the following plasma evolution with a two-dimensional particle-in-cell code and the probe proton deflections by particle tracing. The analysis suggests the formation of rows of magnetized soliton remnants, with a quasistatic magnetic field associated with vortexlike electron currents resembling those of magnetic vortices.

Field testing a full-scale tidal turbine Part 2: In-line Wake Effects

Recent research has shown that higher ambient turbulence leads to better wake recovery, so turbines could be installed in closer proximity in real tidal flows than might be assumed from typical towing tank tests that do not take into account turbulent inflow conditions. The standard tools to assess flow velocities in field conditions are Doppler based sonar devices, such as Acoustic Doppler Profilers (ADPs) or Acoustic Doppler Velocimeters (ADVs). The use of these devices poses some challenges when assessing the wake of a tidal turbine. While ADPs allow the three-dimensional measurement of a velocity profile over a distance, the data is calculated as a mean of three diverging beams and with low temporal resolution. ADVs can measure with higher sampling frequency but only at a single point in the flow. During the MaRINET testing of the SCHOTTELSIT turbine at the QUB tidal test site in Portaferry, Northern Ireland, ADP and ADV measurements were successfully tested.Two methods were employed for measuring the wake: firstly, with a rigidly mounted ADP and secondly, with a submerged ADV which was streamed behind the turbine. This paper presents the experimental set-up and results and discusses limitations and challenges of the two methods used.

Food fraud and consumers' choices in the wake of the horsemeat scandal

Purpose – In 2012, the European food industry was hit by a food fraud: horsemeat was found in
pre-prepared foods, without any declaration on the package. This is commonly referred to as the
“horsemeat scandal”. The purpose of this paper is to investigate consumers’ preferences across
Europe for a selected ready meal, ready to heat (RTH) fresh lasagne, to consider whether the effects of
potential food frauds on consumers’ choices can be mitigated by introducing enhanced standards of
RTH products.
Design/methodology/approach – An online survey was administered to 4,598 consumers of RTH
lasagne in six European countries (Republic of Ireland, France, Italy, Spain, Germany and Norway),
applying discrete choice experiments to estimate consumers’ willingness to pay for enhanced food
safety standards and highlight differences between countries.
Findings – Many similarities across countries emerged, as well as some differences. Consumers in
Europe are highly concerned with the authenticity of the meat in ready meals and strongly prefer to
know that ingredients are nationally sourced. Strong regional differences in price premiums exist for
enhanced food safety standards.
Originality/value – This research adds relevant insights in the analysis of consumers’ reaction to
food fraud, providing practical guidelines on the most appropriate practices that producers should
adopt and on the information to reduce food risk perception among consumers. This would prove
beneficial for the food processing industry and the European Union. The survey is based on a
representative sample of European consumers making this the largest cross-country study of this kind.

Transition Between Open and Closed Wake in 3D Linear Aerospike Nozzles

Linear aerospike nozzles are envisaged as a possible device able to improve launcher engine performance. One of the most interesting properties of these nozzles is the possibility of a good integration with the vehicle. Tb improve the knowledge of the flow-field and performance of aerospike nozzles, they are studied numerically, with particular attention to the differences between the basic two-dimensional nozzle, usually considered in the design phase, and the more realistic three-dimensional nozzle. The study considers different plug lengths and ambient pressures to assess the role of the linear plug side truncation on the base pressure behavior. Numerical tests are carried out at supersonic flight Mach number. Copyright © 2005 by M. Geron and R. Paciorri.F. Nasuti, F. Sabetta, E. Martelli.

Non-contact Pressure-based Sleep/Wake Discrimination

Poor sleep is increasingly being recognised as an important prognostic parameter of health. For those with suspected sleep disorders, patients are referred to sleep clinics which guide treatment. However, sleep clinics are not always a viable option due to their high cost, a lack of experienced practitioners, lengthy waiting lists and an unrepresentative sleeping environment. A home-based non-contact sleep/wake monitoring system may be used as a guide for treatment potentially stratifying patients by clinical need or highlighting longitudinal changes in sleep and nocturnal patterns. This paper presents the evaluation of an under-mattress sleep monitoring system for non-contact sleep/wake discrimination. A large dataset of sensor data with concomitant sleep/wake state was collected from both younger and older adults participating in a circadian sleep study. A thorough training/testing/validation procedure was configured and optimised feature extraction and sleep/wake discrimination algorithms evaluated both within and across the two cohorts. An accuracy, sensitivity and specificity of 74.3%, 95.5%, and 53.2% is reported over all subjects using an external validation
dataset (71.9%, 87.9% and 56%, and 77.5%, 98% and 57% is reported for younger and older subjects respectively). These results compare favourably with similar research, however this system provides an ambient alternative suitable for long term continuous sleep monitoring, particularly amongst vulnerable populations.