Transient and long-term antioxidant gene responses in Medicago truncatula following application of exogenous nitric oxide

Nitric oxide (NO) is a bioactive molecule involved in many biological events that has been reported to act as both a prooxidant and an antioxidant in plants. Several reports exist which investigate the protective action of low (f.lM) concentrations of sodium nitroprusside (SNP), a NO donor. It is now commonly accepted that NO acts as a signal molecule in plants possibly playing a role to induce/stabilize the expression of many antioxidant enzymes. This study attempts to provide novel insight into the effect of application of exogenous NO on transient and long-term antioxidant gene expression levels in the model plant Medicago truncatula following inhibition studies and a quantitative real-time peR approach. Our data suggest that exogenous NO leads to a transient (3hour) induction of several antioxidant genes examined including A ox, Apx and Cat, while expression levels appear to decline after 24 hours. NO- and ROS-dependent signalling pathways were detected to operate and differentially affect induction of the different antioxidant genes. Our data suggest that Cat expression is not affected directly by NO or ROS-signalling cascades. Aox induction by NO is affected by NO- and ROS-dependent signalling pathways while Apx induction by NO has NO-dependent but not ROS-dependent signalling components

Binary neutron star mergers: a jet engine for short gamma-ray bursts

We perform magnetohydrodynamic simulations in full general relativity (GRMHD) of quasi-circular, equal-mass, binary neutron stars that undergo merger. The initial stars are irrotational, $n=1$ polytropes and are magnetized. We explore two types of magnetic-field geometries: one where each star is endowed with a dipole magnetic field extending from the interior into the exterior, as in a pulsar, and the other where the dipole field is initially confined to the interior. In both cases the adopted magnetic fields are initially dynamically unimportant. The merger outcome is a hypermassive neutron star that undergoes delayed collapse to a black hole (spin parameter $a/M_{\rm BH} \sim 0.74$) immersed in a magnetized accretion disk. About $4000M \sim 60(M_{\rm NS}/1.625M_\odot)$ ms following merger, the region above the black hole poles becomes strongly magnetized, and a collimated, mildly relativistic outflow --- an incipient jet --- is launched. The lifetime of the accretion disk, which likely equals the lifetime of the jet, is $\Delta t \sim 0.1 (M_{\rm NS}/1.625M_\odot)$ s. In contrast to black hole--neutron star mergers, we find that incipient jets are launched even when the initial magnetic field is confined to the interior of the stars.Comment: 6 pages, 3 figures, 1 table, matches published versio

Male patient with mild cognitive impairment and extremely high P300 and Slow-wave latencies: a case report

We present a case of a 74-year-old Greek male who suffered from paraphasias, memory and orientation problems. The patient was assessed with neuropsychometric tests, auditory event-related potentials and cerebrospinal fluid proteins and was diagnosed with mild cognitive impairment. The emphasis on the case is on the unexplained high levels of P300 and Slow wave of the auditory event-related potentials

Integrating TAM with EEG Frontal Asymmetry

Recent evolution in the Information Systems (IS) community has involved neuroscience tools and methods in order to develop new theories concerning Human-Computer Interaction (HCI) and further understand IS acceptance models. Thus, the field of NeuroIS has emerged. Moreover, NeuroIS researchers have proposed encephalograph (EEG) as valuable usability metric. Particularly, EEG frontal asymmetry has been related to approach/withdraw behaviour and positive/negative affect concerning users’ perceptions. Furthermore, Technology Acceptance Model (TAM) has been established as the most notable model regarding IS acceptance. This study is a first attempt to integrate EEG frontal asymmetry with TAM in order to associate brain activation with the two most important variables of TAM: Perceived Usefulness and Perceived Ease of Use. Specifically, thirty one undergraduate students were chosen to use a Computer-Based Assessment (while being connected to the EEG) in the context of an introductory informatics course. Results indicate a direct positive association of frontal asymmetry on the aforementioned variables. These findings suggest that frontal asymmetry could be useful for validating and developing Information Technology (IT) theories, as well as designing and explaining the acceptance and adoption of new IS systems or products

Magnetic Skyrmions in FePt Square-Based Nanoparticles Around Room-Temperature

Magnetic skyrmions formed around room-temperature in square-based parallelepiped magnetic nanoparticles with perpendicular magnetocrystalline anisotropy similar to that of partially chemically ordered FePt were studied during the magnetization reversal using micromagnetic simulations. Finite Differences (FD) discretizations were used for the solution of the Landau-Lifshitz-Gilbert equation. Magnetic configurations exhibiting N\'eel chiral stripe and N\'eel skyrmionic formations were detected. The magnetic skyrmions can be created in different systems generated by the variation of external field, side length and width of the squared-based parallelepiped magnetic nanoparticles. Micromagnetic configurations revealed a variety of states which include skyrmionic textures with one distinct skyrmion formed and being stable for a range of external fields around room-temperature. The size of the formed N\'eel skyrmion is calculated as a function of the external field, temperature, magnetocrystalline anisotropy and nanoparticle's geometrical characteristic lengths which can be adjusted to produce N\'eel type skyrmions on demand having diameters down to 12 nm. The micromagnetic simulations revealed that stable skyrmions at the temperature range 270K-330K can be created for FePt magnetic nanoparticle systems lacking of chiral interactions such as Dzyaloshinsky-Moriya, providing new perspectives in the new magnetic writing era.Comment: 11 pages,12 Figures, research articl

Binary Black-Hole Mergers in Magnetized Disks: Simulations in Full General Relativity

We present results from the first fully general relativistic, magnetohydrodynamic (GRMHD) simulations of an equal-mass black hole binary (BHBH) in a magnetized, circumbinary accretion disk. We simulate both the pre and post-decoupling phases of a BHBH-disk system and both "cooling" and "no-cooling" gas flows. Prior to decoupling, the competition between the binary tidal torques and the effective viscous torques due to MHD turbulence depletes the disk interior to the binary orbit. However, it also induces a two-stream accretion flow and mildly relativistic polar outflows from the BHs. Following decoupling, but before gas fills the low-density "hollow" surrounding the remnant, the accretion rate is reduced, while there is a prompt electromagnetic (EM) luminosity enhancement following merger due to shock heating and accretion onto the spinning BH remnant. This investigation, though preliminary, previews more detailed GRMHD simulations we plan to perform in anticipation of future, simultaneous detections of gravitational and EM radiation from a merging BHBH-disk system.Comment: 5 pages, 5 figure