10,283 research outputs found
Influence of spatial variability of hydraulic characteristics of soils on surface parameters obtained from remote sensing data in infrared and microwaves
The correct interpretation of thermal and hydraulic soil parameters infrared from remotely sensed data (thermal infrared, microwaves) implies a good understanding of the causes of their temporal and spatial variability. Given this necessity, the sensitivity of the surface variables (temperature, moisture) to the spatial variability of hydraulic soil properties is tested with a numerical model of heat and mass transfer between bare soil and atmosphere. The spatial variability of hydraulic soil properties is taken into account in terms of the scaling factor. For a given soil, the knowledge of its frequency distribution allows a stochastic use of the model. The results are treated statistically, and the part of the variability of soil surface parameters due to that of soil hydraulic properties is evaluated quantitatively
Droplets displacement and oscillations induced by ultrasonic surface acoustic waves: a quantitative study
We present an experimental study of a droplet interacting with an ultrasonic
surface acoustic wave (SAW). Depending on the amplitude of the wave, the drop
can either experience an internal flow with its contact-line pinned, or (at
higher amplitude) move along the direction of the wave also with internal flow.
Both situations appear together with oscillations of the drop free-surface. The
physical origins of the internal mixing flow as well as the drop displacement
and surface waves are still not well understood. In order to give insights of
the underlying physics involved in these phenomena, we carried out an
experimental and numerical study. The results suggest that the surface
deformation of the drop can be related as a combination between acoustic
streaming effect and radiation pressure inside the drop.Comment: 9 pages, 14 figures. To appear in Physical Review
Seeing but not perceiving: Inattentional blindness as a cause of missed cues in the general practice (GP) consultation
Background
It is well known that healthcare professionals, including GPs, frequently fail to respond to cues made by their patients. A possible explanation for this behaviour is that the phenomenon of IB could lead to a failure to observe the cue, rather than a deliberate choice to ignore it. This study sought to explore that possibility, and to consider whether GP trainees are more susceptible to IB than GP trainers.
Aim
A pre-recorded video of a simulated consultation was used, where the patient gave two significant cues which were not picked up by the doctor in the video. The aim was to compare the rates with which both trainee GPs and GP trainers observed these missed cues.
Methods
The research was a case study involving two groups of participants - GP trainees and GP trainers from a localised GP Training Scheme. Actors were used to record a video of a pre-defined GP consultation involving a patient affected by headaches, who gave two significant cues which were not responded to in the video. Participants observed the video while being asked to focus on the diagnosis and management of the patient’s headaches, following which they completed a questionnaire, including questions about the cues.
Results
Cues were missed by 24-53% of participants, suggesting a high rate of IB within the GP consultation. Unexpected findings included the recording by some participants of false observations from the video. There was no significant difference between trainers and trainees in the rates of IB.
Conclusions
IB appears to be a real and significant phenomenon within the GP consultation, and is likely to have important implications for patient care. More research is needed to confirm these findings, establish IB rates as a cause of missed cues among healthcare professionals and evaluate possible interventions to reduce susceptibility to IB
A uniform isotopic and chemical signature of dust exported from Patagonia: Rock sources and occurrence in southern environments
Patagonia is considered to be the most important source of dust from South America that is deposited in surrounding areas, and
we present here a systematic Sr and Nd isotopic study of sediment currently being exported. Eolian and suspended riverine
sediments from Patagonia have a homogeneous chemical and isotopic composition that results from the mixing of by-products
from explosive Andean volcanism, derived from the extensive Jurassic silicic Province of Chon Aike and pyroclastic materials
from the basic to intermediate southern Andean Quaternary arc, which are easily denudated and dispersed. The main Andean uplift
and the glaciations that began in the Late Tertiary account for the extensive distribution of these sediments in the extra-Andean
region. The present geochemical signature of Patagonian sediments was produced during the Pleistocene, along with the onset of
the southern Andean explosive arc volcanism. Previously published compositions of sediments from other southern South
American source regions, assumed to be representative of Patagonia, are distinct from our data. Considering the alleged importance
of Patagonia as a dust source for different depositional environments in southern latitudes, it is surprising to verify that the chemical
and isotopic signatures of Patagonian-sourced sediments are different from those of sediments from the Southern Ocean, the
Pampean Region or the Antarctic ice. Sediments from these areas have a crustal-like geochemical signature reflecting a mixed
origin with sediment from other southern South American sources, whereas Patagonian sediments likely represent the basic to
intermediate end-member composition
Controlling the composition of a confined fluid by an electric field
Starting from a generic model of a pore/bulk mixture equilibrium, we propose
a novel method for modulating the composition of the confined fluid without
having to modify the bulk state. To achieve this, two basic mechanisms -
sensitivity of the pore filling to the bulk thermodynamic state and electric
field effect - are combined. We show by Monte Carlo simulation that the
composition can be controlled both in a continuous and in a jumpwise way. Near
the bulk demixing instability, we demonstrate a field induced population
inversion in the pore. The conditions for the realization of this method should
be best met with colloids, but being based on robust and generic mechanisms, it
should also be applicable to some molecular fluids.Comment: 9 pages, 5 figure
A phenomenological theory giving the full statistics of the position of fluctuating pulled fronts
We propose a phenomenological description for the effect of a weak noise on
the position of a front described by the Fisher-Kolmogorov-Petrovsky-Piscounov
equation or any other travelling wave equation in the same class. Our scenario
is based on four hypotheses on the relevant mechanism for the diffusion of the
front. Our parameter-free analytical predictions for the velocity of the front,
its diffusion constant and higher cumulants of its position agree with
numerical simulations.Comment: 10 pages, 3 figure
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