Self-Focused Pulse Propagation Is Mediated by Spatiotemporal Optical Vortices.

We show that the dynamics of high-intensity laser pulses undergoing self-focused propagation in a nonlinear medium can be understood in terms of the topological constraints imposed by the formation and evolution of spatiotemporal optical vortices (STOVs). STOVs are born from pointlike phase defects on the sides of the pulse nucleated by spatiotemporal phase shear. These defects grow into closed loops of spatiotemporal vorticity that initially exclude the pulse propagation axis, but then reconnect to form a pair of toroidal vortex rings that wrap around it. STOVs constrain the intrapulse flow of electromagnetic energy, controlling the focusing-defocusing cycles and pulse splitting inherent to nonlinear pulse propagation. We illustrate this in two widely studied but very different regimes, relativistic self-focusing in plasma and nonrelativistic self-focusing in gas, demonstrating that STOVs mediate nonlinear propagation irrespective of the detailed physics.

Loss-free shaping of few-cycle terawatt laser pulses.

We demonstrate loss-free generation of 3 mJ, 1 kHz, few-cycle (5 fs at 750 nm central wavelength) double pulses with a pulse peak separation from 10 to 100 fs, using a helium-filled hollow core fiber (HCF) and chirped mirror compressor. Crucial to our scheme are simulation-based modifications to the spectral phase and amplitude of the oscillator seed pulse to eliminate the deleterious effects of self-focusing and nonlinear phase pickup in the chirped pulse amplifier. The shortest pulse separations are enabled by tunable nonlinear pulse splitting in the HCF compressor.

[Evaluation of practices in the management of scabies in children]. / Évaluation des pratiques dans la prise en charge de la gale chez les enfants.

BACKGROUND: Scabies has been on the rise in France in recent years and has posed therapeutic problems, mainly due to the withdrawal of benzyl benzoate. The objective of this study was to describe prescribing practices for scabies in children. METHODS: A national survey was conducted by means of a standardized questionnaire covering various clinical situations of scabies and the drugs used preferentially according to age, which was sent out between December 2014 and March 2015 to members of the clinical research group of the French Society of Paediatric Dermatology. RESULTS: Of the 38 experts contacted, 20 replied. For a typical case of scabies, 55% of the experts initially prescribed oral ivermectin for children aged 6 years, 15% prescribed ivermectin in children aged 2 years, and 5% in infants aged 3 months. Ivermectin was more widely prescribed after failure of prior treatment or recurrence of scabies, on skin lesions or impetigo, if precarious, especially for profuse hyperkeratotic scabies. A total of 35% of the experts reported no prescribing restrictions with regard to patient age or weight. Discrepancies were observed concerning the mode of administration and the time between consecutive doses. Esdepallethrin remained the preferred local treatment among the experts (38% of all topical prescriptions) except in asthmatic children, while permethrin was the least-prescribed topical agent. DISCUSSION: This study confirms the heterogeneity of our practices. Formal expert recommendations are awaited, particularly concerning the use of ivermectin in infants.

A novel approach to pathogen reduction in biosolids: the enzymic hydrolyser.

Revision of the Sludge (Use in Agriculture) Regulations in the UK has resulted in the requirement of a final product standard in terms of E. coli per gram of dry solids. Conventional mesophilic digestion including 14-day secondary storage should normally provide adequate treatment to meet the Treated Sludge Standard. Any process capable of greater pathogen reduction would ensure more process security and compliance comfort. Such a process would be a welcome alternative to extra secondary storage where an existing works does not have sufficient capacity, particularly if the differences in costs between the options are small. Enzymic hydrolysis was found to be up to ten-fold more effective in E. coli reduction than conventional secondary digestion. A two-stage digestion process based on this technique has been developed by United Utilities and Montgomery Watson Harza (termed the enzymic hydrolyser, patent pending). Studies showed that the mean numbers of E. coli were significantly lower in the enzymic hydrolyser systems (P > 0.05; t = 13.19) compared to conventional digesters. Increased stability was a secondary benefit of the system (foam was eliminated or greatly reduced in the enzymic hydrolyser units). Another benefit of the system for retrofit to existing assets is the decreased tankage volumes required compared to secondary digestion to achieve more than twice the log kill of pathogens.

Selective left-lobe atrophy by nodularin treatment accompanied by reduced protein phosphatase 1/2A and increased peroxisome proliferation in rat liver.

The effect of nodularin on selective atrophy of left lobes in the liver was investigated in F344 rats. Nodularin was injected for 10 weeks from the third week of initiation with saline or N-nitrosodiethylamine (DEN), grouped as S/N and D/N, respectively. Nodularin significantly decreased weights of left (LL) and caudate (CL) lobes but increased right (RL) and middle (ML) lobes in S/N rats. Activity of protein phosphatases [types 1 (PPI) and 2A (PP2A)] was more severely reduced in S/N than D/N rats; moreover, in LL compared with RL of S/N rats, activity was significantly inhibited by nodularin treatment from week 4, which corresponded to 2 weeks after nodularin injection. However, nodularin significantly induced peroxisomal palmitoyl-CoA oxidase and cytochrome P-450 4A1 expression in S/N compared with D/N rats. An effect of nodularin on apoptosis was evident since expression of Bcl-Xs was clearly induced in LL of S/N rats as opposed to various inductions of Bcl-XL. However, Bcl-XL in RL was persistently induced, with undetectable Bcl-Xs expression. These results demonstrate biochemical evidence of selective atrophy of LL by inhibition of PP1 and PP2A activity, increase of peroxisomal enzymes and induction of Bcl-Xs expression, in contrast to proliferation of RL in rats treated with nodularin alone. However, nodularin endowed DEN-altered hepatocytes with regenerating power and concomitant restoration of phosphatase activity as well as persistent expression of Bcl-XL in D/N rats.