1,435 research outputs found
AGRESTE Program. Part 2: French test-sites
There are no author-identified significant results in this report
A semi-Lagrangian scheme for the game -Laplacian via -averaging
We present and analyze an approximation scheme for the two-dimensional game
-Laplacian in the framework of viscosity solutions. The approximation is
based on a semi-Lagrangian scheme which exploits the idea of -averages. We
study the properties of the scheme and prove that it converges, in particular
cases, to the viscosity solution of the game -Laplacian. We also present a
numerical implementation of the scheme for different values of ; the
numerical tests show that the scheme is accurate.Comment: 34 pages, 3 figures. To appear on Applied Numerical Mathematic
Agricultural resources investigations in northern Italy and southern France (AGRESTE Project). Part 1: Italian test-sites
There are no author-identified significant results in this report
A new mathematical model for traveling sand dunes: analysis and approximation
We present a new two-layer closed form model for the dynamics of desert dunes under the effect of a horizontal wind blowing in an arbitrary direction. This model is an extension of a very simplified model previously introduced by Hadeler and Kuttler [12]. Our extension, inspired by the sandpile dynamics approach, includes the effects of gravity on both sides (upwind and downwind) of the dune, and allows to describe erosion and deposition in a more accurate way. After a discussion of the model and its properties we present a numerical scheme based on finite differences in 1D and we prove its consistency and stability. Some numerical tests show a good qualitative behavior and a realistic shape for the evolving dunes. Finally, we discuss the preliminary steps of a possible extension of this model to the 2D case
An existence result for the sandpile problem on flat tables with walls
We derive an existence result for solutions of a differential system which
characterizes the equilibria of a particular model in granular matter theory,
the so-called partially open table problem for growing sandpiles. Such result
generalizes a recent theorem of Cannarsa and Cardaliaguet established for the
totally open table problem. Here, due to the presence of walls at the boundary,
the surface flow density at the equilibrium may result no more continuous nor
bounded, and its explicit mathematical characterization is obtained by domain
decomposition techniques. At the same time we show how these solutions can be
numerically computed as stationary solutions of a dynamical two-layer model for
growing sandpiles and we present the results of some simulations.Comment: 15 pages, 11 figure
A Real-time Calculus Approach for Integrating Sporadic Events in Time-triggered Systems
In time-triggered systems, where the schedule table is predefined and
statically configured at design time, sporadic event-triggered (ET) tasks can
only be handled within specially dedicated slots or when time-triggered (TT)
tasks finish their execution early. We introduce a new paradigm for
synthesizing TT schedules that guarantee the correct temporal behavior of TT
tasks and the schedulability of sporadic ET tasks with arbitrary deadlines. The
approach first expresses a constraint for the TT task schedule in the form of a
maximal affine envelope that guarantees that as long as the schedule generation
respects this envelope, all sporadic ET tasks meet their deadline. The second
step consists of modeling this envelope as a burst limiting constraint and
building the TT schedule via simulating a modified Least-Laxity-First (LLF)
scheduler. Using this novel technique, we show that we achieve equal or better
schedulability and a faster schedule generation for most use-cases compared to
other approaches inspired by, e.g., hierarchical scheduling. Moreover, we
present an extension to our method that finds the most favourable schedule for
TT tasks with respect to ET schedulability, thus increasing the probability of
the computed TT schedule remaining feasible when ET tasks are later added or
changed
Mixed mucus-secreting and oncocytic carcinoma of the thyroid - Pathologic, histochemical, immunohistochemical, and ultrastructural study of a case
We report a carcinoma that is, to the best of our knowledge, the first case of a mixed mucus-secreting and oncocytic carcinoma of the thyroid. We also describe the histochemical, immunohistochemical, and ultrastructural features of this tumor. A 59-year-old man complaining of severe bone pain and weight loss underwent clinical and radiologic investigations. The studies revealed a nodule in the left thyroid lobe that was "cold" by (131)I scintiscan and multiple lytic lesions of the skeleton that showed increased uptake by (99m)Tc-Sestamibi scintiscan. Left hemithyroidectomy was performed and the surgical specimen contained a well-circumscribed nodule of 3 cm in the greatest diameter. Light microscopy showed an oncocytic carcinoma with an area of glandular and papillary proliferation of mucin-producing cells. A double histochemical approach (Alcian blue-periodic acid-Schiff and Alcian blue-high-iron diamine) combined with ultrastructural investigation confirmed the presence of true mucus, ruling out the presence of breakdown products of thyroglobulin. Ultrastructural and immunohistochemical studies, together with clinical findings, excluded a possible metastatic origin of the mucin-producing componen
Model for Gravitational Interaction between Dark Matter and Baryons
We propose a phenomenological model where the gravitational interaction
between dark matter and baryons is suppressed on small, subgalactic scales. We
describe the gravitational force by adding a Yukawa contribution to the
standard Newtonian potential and show that this interaction scheme is
effectively suggested by the available observations of the inner rotation
curves of small mass galaxies. Besides helping in interpreting the cuspy
profile of dark matter halos observed in N-body simulations, this potential
regulates the quantity of baryons within halos of different masses.Comment: 4 pages, 2 figures, final versio
Damage in step-overs may enable large cascading earthquakes
Seismic hazard analysis relies on the ability to predict whether an earthquake will terminate at a fault tip or propagate onto adjacent faults, cascading into a larger, more devastating event. While ruptures are expected to arrest at fault discontinuities larger than 4–5 km, scientists are often puzzled by much larger rupture jumps. Here we show that material properties between faults significantly affect the ability to arrest propagating ruptures. Earthquake simulations accounting for fault step-over zones weakened by accumulated damage provide new insights into rupture propagation. Revealing that lowered rigidity and material interfaces promote rupture propagation, our models show for the first time that step-overs as wide as 10 km may not constitute effective earthquake barriers. Our results call for re-evaluation of seismic hazard analyses that predict rupture length and earthquake magnitude based on historic records and fault segmentation models
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(E)motion and creativity: Hacking the function of motor expressions in emotion regulation to augment creativity
Positive emotion can help augment human creativity. To utilize this potential in an interactive system, we propose that such a system should be designed to regulate the emotions that are caused by a creative task. We argue that this can be done by hacking the function of motor expressions in emotion regulation. To this end, we have conceived and made an interactive system that is designed to regulate positive emotion during an idea generation and an insight problem solving task. The system regulates emotion by letting users interact using arm gestures that are designed based on motor expressions, choreographed in a way that enables emotion regulation. Using this interactive system we experimentally test the hypotheses that positive approaching, rather than negative avoiding arm gestures, used to interact with a system, can heighten positive emotion, and augment creativity. The findings demonstrate that an interactive system can be designed to use the function of motor expressions in emotion regulation to help people perform better on certain creative tasks
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