Ion activity in quasi-neutral current sheets and discharge plasma in crossed electric and magnetic fields

As part of a brief review, a classification is made and information is provided about four experimentally discovered plasma effects, where unexpected behavior of the ionic component appeared and for which there is no unambiguous interpretation. 1. Ions with the highest energies for a quasi-neutral current sheet were recorded at the O-point (island) with the direction of their movement opposite to the electric field at the X-point. 2. In a self-sustaining discharge in crossed electric and magnetic fields (E×B discharge), a large number of ions (not the tails of the distribution function) with energies significantly exceeding the energies equivalent to the discharge voltage are generated. This occurs in a certain range of pressures of the plasma-forming gas and magnetic fields. 3. The discovered region of effective ionization — the “anode layer”, with increasing pressure, moves abruptly from one plasma region to another, which is accompanied by a jump in the ion density up to 16 times. An increase in the magnetic field induction causes, on the contrary, the “anode layer” to jump in the opposite direction with the ion density decreasing 3–4 times. 4. Ion distribution functions in the E×B discharge contain isomagnetic density jumps with a relative amplitude from ~30 to 80 % of the total current at the released energy. Taking into account the “anomalous” behavior of ions in the plasma of quasi-neutral current sheets and discharges in crossed electric and magnetic fields will provide further insight into the processes in space plasma, the physics of coronal heating, and the formation of the solar wind

The impact of chronic stress on the rat brain lipidome

Chronic stress is a major risk factor for several human disorders that affect modern societies. The brain is a key target of chronic stress. In fact, there is growing evidence indicating that exposure to stress affects learning and memory, decision making and emotional responses, and may even predispose for pathological processes, such as Alzheimer's disease and depression. Lipids are a major constituent of the brain and specifically signaling lipids have been shown to regulate brain function. Here, we used a mass spectrometry-based lipidomic approach to evaluate the impact of a chronic unpredictable stress (CUS) paradigm on the rat brain in a region-specific manner. We found that the prefrontal cortex (PFC) was the area with the highest degree of changes induced by chronic stress. Although the hippocampus presented relevant lipidomic changes, the amygdala and, to a greater extent, the cerebellum presented few lipid changes upon chronic stress exposure. The sphingolipid and phospholipid metabolism were profoundly affected, showing an increase in ceramide (Cer) and a decrease in sphingomyelin (SM) and dihydrosphingomyelin (dhSM) levels, and a decrease in phosphatidylethanolamine (PE) and ether phosphatidylcholine (PCe) and increase in lysophosphatidylethanolamine (LPE) levels, respectively. Furthermore, the fatty-acyl profile of phospholipids and diacylglycerol revealed that chronic stressed rats had higher 38 carbon(38C)-lipid levels in the hippocampus and reduced 36C-lipid levels in the PFC. Finally, lysophosphatidylcholine (LPC) levels in the PFC were found to be correlated with blood corticosterone (CORT) levels. In summary, lipidomic profiling of the effect of chronic stress allowed the identification of dysregulated lipid pathways, revealing putative targets for pharmacological intervention that may potentially be used to modulate stress-induced deficits.Funding by Fundação para a Ciência e Tecnologia (PTDC/SAU-NMC/118971/2010) and by the North Region Operational Program (ON.2-O Novo Norte), under Quadro de Referência Estratégico Nacional (QREN) and through Fundo Europeu de Desenvolvimento Regional (FEDER). GDP is funded by NIH grants R01 NS056049 and P50 AG008702 (to Scott Small)