21 research outputs found
Guidance for the integrated use of hydrological, geochemical, and isotopic tools in mining operations
This paper summarizes international state-of-the-art applications and opportunities for employing and deploying hydrological, geochemical, and isotopic tools in an integrated manner for investigations of mining operations. It is intended to aid formulation of more integrated approaches for evaluating the overall sustainability of mining projects. The focus is particularly on mine waters, including: environmental water sources, mine water dynamics, and as a source and vector for pollution in the wider environment. The guidance is generic to mining projects and not just reflective of a particular extraction (e.g. coal, metalliferous, uranium) industry. A mine life cycle perspective has been adopted to highlight the potential for more integrated investigations at each stage of a mining operation. Three types of mines have been considered: new (i.e. those in the planning stage), active (i.e. working mines), and historical mines (i.e. inactive and abandoned mines). The practical usage of geochemical analyses and isotopic studies described here emphasise characterisation, dynamics, and process understanding for water quality considerations in tandem with water resource and environmental impact implications. Both environmental (i.e. ambient) and applied (i.e. injected) tracers are considered. This guide is written for scientists (including isotope specialists) who have limited or no mine water experience, environmental managers, planners, consultants, and regulators with key interests in planned, active, and legacy mining projects.The authors thank the IAEA for inviting us to
collate an initial report on guidelines from 2018-06-25–28 in Vienna.
We thank Chris Gammons for allowing us to use one of his fgures.
We especially thank Umaya Doss Saravana Kumar, Lucia Ortega, and
Araguás-Araguás from IAEA for assistance, and Andrea Nick for input
during the meeting. Special thanks to our reviewers who substantially
helped improve the structure and content of this guidance document
Dynamical heterogeneity in aging colloidal glasses of Laponite
Glasses behave as solids due to their long relaxation time; however the
origin of this slow response remains a puzzle. Growing dynamic length scales
due to cooperative motion of particles are believed to be central to the
understanding of both the slow dynamics and the emergence of rigidity. Here, we
provide experimental evidence of a growing dynamical heterogeneity length scale
that increases with increasing waiting time in an aging colloidal glass of
Laponite. The signature of heterogeneity in the dynamics follows from dynamic
light scattering measurements in which we study both the rotational and
translational diffusion of the disk-shaped particles of Laponite in suspension.
These measurements are accompanied by simultaneous microrheology and
macroscopic rheology experiments. We find that rotational diffusion of
particles slows down at a faster rate than their translational motion. Such
decoupling of translational and orientational degrees of freedom finds its
origin in the dynamic heterogeneity since rotation and translation probe
different length scales in the sample. The macroscopic rheology experiments
show that the low frequency shear viscosity increases at a much faster rate
than both rotational and translational diffusive relaxation times.Comment: 12 pages, 5 figures, Accepted in Soft Matter 201
Human Wavelength Discrimination of Monochromatic Light Explained by Optimal Wavelength Decoding of Light of Unknown Intensity
We show that human ability to discriminate the wavelength of monochromatic light
can be understood as maximum likelihood decoding of the cone absorptions, with a
signal processing efficiency that is independent of the wavelength. This work is
built on the framework of ideal observer analysis of visual discrimination used
in many previous works. A distinctive aspect of our work is that we highlight a
perceptual confound that observers should confuse a change in input light
wavelength with a change in input intensity. Hence a simple ideal observer model
which assumes that an observer has a full knowledge of input intensity should
over-estimate human ability in discriminating wavelengths of two inputs of
unequal intensity. This confound also makes it difficult to consistently measure
human ability in wavelength discrimination by asking observers to distinguish
two input colors while matching their brightness. We argue that the best
experimental method for reliable measurement of discrimination thresholds is the
one of Pokorny and Smith, in which observers only need to distinguish two
inputs, regardless of whether they differ in hue or brightness. We
mathematically formulate wavelength discrimination under this
wavelength-intensity confound and show a good agreement between our theoretical
prediction and the behavioral data. Our analysis explains why the discrimination
threshold varies with the input wavelength, and shows how sensitively the
threshold depends on the relative densities of the three types of cones in the
retina (and in particular predict discriminations in dichromats). Our
mathematical formulation and solution can be applied to general problems of
sensory discrimination when there is a perceptual confound from other sensory
feature dimensions
Traumatic Brain Injury Patient, Injury, Therapy, and Ancillary Treatments Associated With Outcomes at Discharge and 9 Months Postdischarge
Long-range Transport of NH3, CO, HCN and C2H6 from the 2014 Canadian Wildfires
We report the first long-term measurements of ammonia (N