ABSTRACT
Management of travelers' cognitive load is crucial for efficient information processing for optimal railway operations. We investigated variations in travelers' cognitive load with different expertise levels, in a field study. We aimed to assess the use of three eye metrics: pupil diameter, saccade amplitude and gaze of fixation duration for cognitive load analysis between expert and novice travelers in a Mass Transit train station: Saint-Michel Notre Dame. Physiological measures of emotional activity through skin conductance responses were also investigated, together with subjective measures of mental load using NASA-Task Load Index. Our results followed our expectations, where novice travelers expressed higher cognitive load than expert travelers, characterized by wider pupil diameter, larger amplitude of saccade and longer gaze duration, as well as higher electrodermal activity and NASA-TLX. Additional observations showed that experts used hierarchical and symmetrical scan paths, with more intense exposure on relevant information, characterized by brighter heat maps. This difference in behavior showed a clear difference in strategies for information retrieval at different expertise levels. Metrics of eye tracking device, together with electrodermal activity, proved to be potent in cognitive load analysis of train travelers, and helped to provide insights for real-life information processing.
Subject(s)
Cognition/physiology , Eye Movements/physiology , Mental Processes/physiology , Railroads , Travel/psychology , Adult , Emotions/physiology , Eye Movement Measurements , Female , Fixation, Ocular/physiology , Humans , Male , Mental Competency/psychology , Paris , Pupil/physiology , Saccades/physiologyABSTRACT
Thermonuclear fusion neutrons produced by D(d,n)3He reactions have been measured from the interaction of a high-intensity laser with underdense deuterium plasmas. For an input laser energy of 62 J, more than (1.0+/-0.2)x10(6) neutrons with a mean kinetic energy of (2.5+/-0.2) MeV were detected. These neutrons were observed to have an isotropic angular emission profile. By comparing these measurements with those using a secondary solid CD2 target it was determined that neutrons are produced from direct ion heating during this interaction.
ABSTRACT
A short-pulse laser beat wave scheme for advanced particle accelerator applications is examined. A short, intense (3-ps, >10(18)-W cm(-2)) two-frequency laser pulse is produced by use of a modified chirped-pulse amplification scheme and is shown to produce relativistic plasma waves during interactions with low-density plasmas. The generation of plasma waves was observed by measurement of forward Raman scattering. Resonance was found to occur at an electron density many times that expected, owing to ponderomotive displacement of plasma within the focal region.
ABSTRACT
Sites polluted with 2,4,6-trinitrotoluene (TNT) constitute a worldwide problem. In this work, chemical reactions for binding TNT to amino-compounds are proposed as an initial step for developing new remediation techniques to clean-up groundwater and soils contaminated with TNT. Indeed, addition of aniline and an amino acid-like cysteine caused a decrease in free TNT of 86% and 68-100%, respectively. Using 13C-NMR spectroscopy, it was shown that TNT chemically forms a Meisenheimer complex with cysteine and aniline in 1/1 (by vol.) H2O/d6-acetone.
Subject(s)
Amines/chemistry , Amino Acids/chemistry , Decontamination/methods , Trinitrotoluene/chemistry , Water Purification/methods , Aniline Compounds/chemistry , Biodegradation, Environmental , Carbon Isotopes , Cysteine/chemistry , Fourier Analysis , Humans , Magnetic Resonance Spectroscopy , Soil Pollutants , Water Pollutants, ChemicalABSTRACT
The homogeneity of the microbial community structure of a sediment landfill was examined by a culture-independent method and compared with physico-chemical parameters, i.e. organic matter, CaCO3 content, pH, and texture. Total genomic DNA was extracted from samples derived from different places and depths. After amplification with two different primer sets of partial bacterial 16S rRNA genes, the products were separated by denaturing gradient gel electrophoresis (DGGE). The DGGE fingerprints of different sediment samples taken in regular patterns at the same depth were similar, which indicates a spatial homogeneity in the numerically dominant bacterial populations in a landfill over 10,000 m2 in size. In a vertical column of approx. 10 m, only some differences in a few bands of the bacterial community structure were observed between samples taken from different depths. This DNA homogeneity coincided with a similar homogeneity of the physico-chemical parameters in the landfill at this site. Nevertheless, the DGGE technique revealed small differences in less prominent bacteria and was capable of separating the upper and lower samples of one column into two clusters. It therefore seems more sensitive than the physico-chemical approach for characterising the homogeneity of an environmental habitat.
