Observation of ion temperatures exceeding background electron temperatures in petawatt laser-solid experiments

Neutron time of flight signals have been observed with a high resolution neutron spectrometer using the petawatt arm of the Vulcan laser facility at Rutherford Appleton Laboratory from plastic sandwich targets containing a deuterated layer. The neutron spectra have two elements: a high-energy component generated by beam-fusion reactions and a thermal component around 2.45 MeV. The ion temperatures calculated from the neutron signal width clearly demonstrate a dependence on the front layer thickness and are significantly higher than electron temperatures measured under similar conditions. The ion heating process is intensity dependent and is not observed with laser intensities on target below 10(20) W cm(-2). The measurements are consistent with an ion instability driven by electron perturbations.

Quantification of DNA damage by PFGE: development of an analytical approach to correct for the background distribution

Purpose: To analyse the currently existing methods to infer the extent of cellular DNA damage induced by ionizing radiation when the pulsed field gel electrophoresis (PFGE) technique is used.

Detection of a novel porcine boca-like virus in the background of porcine circovirus type 2 induced postweaning multisystemic wasting syndrome

Porcine circovirus type 2 (PCV-2) has been found to be the causative agent of postweaning multisystemic wasting syndrome (PMWS). However, PCV-2 is a ubiquitous virus in the swine population and a majority of pigs infected with PCV-2 do not develop the disease. Different factors such as age, maintenance, the genetics of PCV-2, other pathogens, etc. have been suggested to contribute to the development of PMWS. However, so far no proven connection between any of these factors and the disease development has been found. In this study we explored the possible presence of other so far unknown DNA containing infectious agents in lymph nodes collected from Swedish pigs with confirmed PMWS through random amplification and high-throughput sequencing. Although the vast majority of the amplified genetic sequences belonged to PCV-2, we also found genome sequences of Torque Teno virus (TTV) and of a novel parvovirus. The detection of TTV was expected since like PCV-2, TTV has been found to have high prevalence in pigs around the world. We were able to amplify a longer region of the parvovirus genome, consisting of the entire NP1 and partial VP1/2. By comparative analysis of the nucleotide sequences and phylogenetic studies we propose that this is a novel porcine parvovirus, with genetic relationship to bocaviruses.

Magneto-optical trapping and background-free imaging for atoms near nanostructured surfaces

We demonstrate a combined magneto-optical trap and imaging system that is suitable for the investigation of cold atoms near surfaces. In particular, we are able to trap atoms close to optically scattering surfaces and to image them with an excellent signal-to-noise ratio. We also demonstrate a simple magneto-optical atom cloud launching method. We anticipate that this system will be useful for a range of experimental studies of novel atom-surface interactions and atom trap miniaturization.

Regularized Online Mixture of Gaussians for Background Subtraction

Mixture of Gaussians (MoG) modelling [13] is a popular approach to background subtraction in video sequences. Although the algorithm shows good empirical performance, it lacks theoretical justification. In this paper, we give a justification for it from an online stochastic expectation maximization (EM) viewpoint and extend it to a general framework of regularized online classification EM for MoG with guaranteed convergence. By choosing a special regularization function, l1 norm, we derived a new set of updating equations for l1 regularized online MoG. It is shown empirically that l1 regularized online MoG converge faster than the original online MoG .

Gaussian mixture background modelling optimisation for micro-controllers

This paper proposes an optimisation of the adaptive Gaussian mixture background model that allows the deployment of the method on processors with low memory capacity. The effect of the granularity of the Gaussian mean-value and variance in an integer-based implementation is investigated and novel updating rules of the mixture weights are described. Based on the proposed framework, an implementation for a very low power consumption micro-controller is presented. Results show that the proposed method operates in real time on the micro-controller and has similar performance to the original model. �� 2012 Springer-Verlag.

Whole grains and health:attitudes to whole grains against a prevailing background of increased marketing and promotion

To explore current awareness and perceptions of whole grain foods and perceived barriers and facilitators of whole grain consumption.

Hardware Acceleration of Background Modeling in the Compressed Domain

In intelligent video surveillance systems, scalability (of the number of simultaneous video streams) is important. Two key factors which hinder scalability are the time spent in decompressing the input video streams, and the limited computational power of the processor. This paper demonstrates how a combination of algorithmic and hardware techniques can overcome these limitations, and significantly increase the number of simultaneous streams. The techniques used are processing in the compressed domain, and exploitation of the multicore and vector processing capability of modern processors. The paper presents a system which performs background modeling, using a Mixture of Gaussians approach. This is an important first step in the segmentation of moving targets. The paper explores the effects of reducing the number of coefficients in the compressed domain, in terms of throughput speed and quality of the background modeling. The speedups achieved by exploiting compressed domain processing, multicore and vector processing are explored individually. Experiments show that a combination of all these techniques can give a speedup of 170 times on a single CPU compared to a purely serial, spatial domain implementation, with a slight gain in quality.