12,203 research outputs found
Testing demand responsive shared transport services via agent-based simulations
Demand Responsive Shared Transport DRST services take advantage of
Information and Communication Technologies ICT, to provide on demand transport
services booking in real time a ride on a shared vehicle. In this paper, an
agent-based model ABM is presented to test different the feasibility of
different service configurations in a real context. First results show the
impact of route choice strategy on the system performance
Cenozoic seismic stratigraphy and tectonic evolution of the Algarve margin (offshore Portugal, southwestern Iberian Peninsula)
The Cenozoic seismic stratigraphy and tectonic evolution of the Algarve margin (southwestern border of the Iberian Peninsula) are documented from multichannel seismic reflection data, isochron and time-structure maps.http://www.sciencedirect.com/science/article/B6V6M-4KJV3F0-1/1/141771fd1c5ee441b6f226a499be5e2
Challenges in Collaborative HRI for Remote Robot Teams
Collaboration between human supervisors and remote teams of robots is highly
challenging, particularly in high-stakes, distant, hazardous locations, such as
off-shore energy platforms. In order for these teams of robots to truly be
beneficial, they need to be trusted to operate autonomously, performing tasks
such as inspection and emergency response, thus reducing the number of
personnel placed in harm's way. As remote robots are generally trusted less
than robots in close-proximity, we present a solution to instil trust in the
operator through a `mediator robot' that can exhibit social skills, alongside
sophisticated visualisation techniques. In this position paper, we present
general challenges and then take a closer look at one challenge in particular,
discussing an initial study, which investigates the relationship between the
level of control the supervisor hands over to the mediator robot and how this
affects their trust. We show that the supervisor is more likely to have higher
trust overall if their initial experience involves handing over control of the
emergency situation to the robotic assistant. We discuss this result, here, as
well as other challenges and interaction techniques for human-robot
collaboration.Comment: 9 pages. Peer reviewed position paper accepted in the CHI 2019
Workshop: The Challenges of Working on Social Robots that Collaborate with
People (SIRCHI2019), ACM CHI Conference on Human Factors in Computing
Systems, May 2019, Glasgow, U
On the Slow Drift of Solstices: Milankovic Cycles and Mean Global Temperature
The Earth's revolution is modified by changes in inclination of its rotation
axis. Despite the fact that the gravity field is central, the Earth's
trajectory is not closed and the equinoxes drift. Milankovic (1920) argued that
the shortest precession period of solstices is 20,7kyr: the Summer solstice in
one hemisphere takes place alternately every 11kyr at perihelion and at
aphelion. We have submitted the time series for the Earth's pole of rotation,
global mean surface temperature and ephemeris to iterative Singular Spectrum
Analysis. iSSA extracts from each a trend, a 1yr and a 60yr component. Both the
apparent drift of solstices of Earth around the Sun and the global mean
temperature exhibit a strong 60yr oscillation. The "fixed dates" of solstices
actually drift. Comparing the time evolution of the Winter and Summer solstices
positions of the rotation pole and the first iSSA component (trend) of the
temperature allows one to recognize some common features. A basic equation from
Milankovic links the derivative of heat received at a given location on Earth
to solar insolation, known functions of the location coordinates, solar
declination and hour angle, with an inverse square dependence on the Sun-Earth
distance. We have translated the drift of solstices as a function of distance
to the Sun into the geometrical insolation theory of Milankovic. Shifting the
inverse square of the 60yr iSSA drift of solstices by 15 years with respect to
the first derivative of the 60yr iSSA trend of temperature, that is exactly a
quadrature in time, puts the two curves in quasi-exact superimposition. The
probability of a chance coincidence appears very low. Correlation does not
imply causality when there is no accompanying model. Here Milankovic's equation
can be considered as a model that is widely accepted. This paper identifies a
case of agreement between observations and a mathematical formulation
Early changes in diaphragmatic function evaluated using ultrasound in cardiac surgery patients: a cohort study.
Little is known about the evolution of diaphragmatic function in the early post-cardiac surgery period. The main purpose of this work is to describe its evolution using ultrasound measurements of muscular excursion and thickening fraction (TF). Single-center prospective study of 79 consecutive uncomplicated elective cardiac surgery patients, using motion-mode during quiet unassisted breathing. Excursion and TF were measured sequentially for each patient [pre-operative (D1), 1 day (D2) and 5 days (D3) after surgery]. Pre-operative median for right and left hemidiaphragmatic excursions were 1.8 (IQR 1.6 to 2.1) cm and 1.7 (1.4 to 2.0) cm, respectively. Pre-operative median right and left thickening fractions were 28 (19 to 36) % and 33 (22 to 51) %, respectively. At D2, there was a reduction in both excursion (right: 1.5 (1.1 to 1.8) cm, p < 0.001, left: 1.5 (1.1 to 1.8), p = 0.003) and thickening fractions (right: 20 (15 to 34) %, p = 0.021, left: 24 (17 to 39) %, p = 0.002), followed by a return to pre-operative values at D3. A positive moderate correlation was found between excursion and thickening fraction (Spearman's rho 0.518 for right and 0.548 for left hemidiaphragm, p < 0.001). Interobserver reliability yielded a bias below 0.1 cm with limits of agreement (LOA) of ± 0.3 cm for excursion and - 2% with LOA of ± 21% for thickening fractions. After cardiac surgery, the evolution of diaphragmatic function is characterized by a transient impairment followed by a quick recovery. Although ultrasound diaphragmatic excursion and thickening fraction are correlated, excursion seems to be a more feasible and reproducible method in this population
Midday measurements of leaf water potential and stomatal conductance are highly correlated with daily water use of Thompson Seedless grapevines
A study was conducted to determine the relationship between midday measurements of vine water status and daily water use of grapevines measured with a weighing lysimeter. Water applications to the vines were terminated on August 24th for 9 days and again on September 14th for 22 days. Daily water use of the vines in the lysimeter (ETLYS) was approximately 40 L vine−1 (5.3 mm) prior to turning the pump off, and it decreased to 22.3 L vine−1 by September 2nd. Pre-dawn leaf water potential (ΨPD) and midday Ψl on August 24th were −0.075 and −0.76 MPa, respectively, with midday Ψl decreasing to −1.28 MPa on September 2nd. Leaf g s decreased from ~500 to ~200 mmol m−2 s−1 during the two dry-down periods. Midday measurements of g s and Ψl were significantly correlated with one another (r = 0.96) and both with ETLYS/ETo (r = ~0.9). The decreases in Ψl, g s, and ETLYS/ETo in this study were also a linear function of the decrease in volumetric soil water content. The results indicate that even modest water stress can greatly reduce grapevine water use and that short-term measures of vine water status taken at midday are a reflection of daily grapevine water us
Is the Earth's magnetic field a constant ? a legacy of Poisson
In the report he submitted to the Acad\'emie des Sciences, Poisson imagined a
set of concentric spheres at the origin of the Earth's magnetic field. It may
come as a surprise to many that Poisson as well as Gauss both considered the
magnetic field to be constant. We propose in this study to test this surprising
assertion for the first time evoked by Poisson (1826). First, we will present a
development of Maxwell's equations in the framework of a static electric field
and a static magnetic field in order to draw the necessary consequences for the
Poisson hypothesis. In a second step, we will see if the observations can be in
agreement with Poisson (1826). To do so, we have chosen to compare 1) the polar
motion drift and the secular variation of the Earth's magnetic field, 2) the
seasonal pseudo-cycles of day length together with those of the sea level
recorded by different tide gauges around the globe and those of the Earth's
magnetic field recorded in different magnetic observatories. We then propose a
mechanism, in the spirit of Poisson, to explain the presence of the 11-year in
the magnetic field. We test this mechanism with observations and finally we
study closely the evolution of the g10 coefficient of the IGFR over time
On variations of global mean surface temperature: When Laplace meets Milankovi\'c
In his mathematical theory, Milankovic finds a link between the heat received
by the Earth surface per unit time as a function of the solar ephemerids and
derives a model of climate changes at periods longer than a few thousand years
and more. In this paper, we investigate the potential connections of global
temperature and Earth rotation at much shorter periods, in the complementary
range of one to a few hundred years. For temperature, we select the HadCrut05.
For Earth rotation, defined by pole coordinates and length of day, we use the
IERS data sets. Using iterative Singular Spectrum Analysis (iSSA), we extract
the trend and quasi-periodic components of these time series. The first
quasi-periodic components (period ~80-90 years) are expressions of the
Gleissberg cycle and are identical (at the level of uncertainty of the data).
Taken together, the trend and Gleissberg components allow one to reconstruct
87% of the variance of the data for lod and 48% for temperature. The next four
iSSA components, with periods ~40, 22, 15 and 9 years. The Lagrange and Laplace
theories imply that the derivative of pole motion should be identical to lod
variations: this strong check is passed by the trend + Gleissberg
reconstructions. The annual oscillations of pole motion and lod are linked to
annual variations in Sun-Earth distance, in agreement with an astronomical, but
not a climatic origin. The results obtained in this paper for the observed
temperature/rotation couple add to the growing list of evidence of solar and
planetary forcings of gravitational nature on a number of geophysical processes
(including sea-level, sea-level pressure, sea-ice extent, oceanic climate
indices).Comment: 13 pages, 13 figure
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A tele-assessment system for monitoring treatment effects in subjects with spinal cord injury.
We developed a method for remote measurement of balance and leg force in patients with spinal cord injury (SCI). In a group of 21 patients, both telemedicine and conventional clinical assessments were conducted at baseline and six months later. Telemedicine assessments were successfully acquired and transmitted at first attempt. The time required to set up the telemedicine equipment, position the subject, perform the measurements, and then send the data to the university laboratory was approximately 30 minutes. After six months, several motor and sensory functions showed significant changes. There were significant correlations between changes in remotely-measured leg force and changes in several of the American Spinal Injury Association (ASIA) sensory and motor scores. Changes in balance did not show any significant correlations with changes in the ASIA scores. Intra-rater reliability was better than inter-rater reliability. Use of telemedicine to remotely monitor changes in patients with SCI appears promising
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