6,035 research outputs found
Push & Pull: autonomous deployment of mobile sensors for a complete coverage
Mobile sensor networks are important for several strategic applications
devoted to monitoring critical areas. In such hostile scenarios, sensors cannot
be deployed manually and are either sent from a safe location or dropped from
an aircraft. Mobile devices permit a dynamic deployment reconfiguration that
improves the coverage in terms of completeness and uniformity.
In this paper we propose a distributed algorithm for the autonomous
deployment of mobile sensors called Push&Pull. According to our proposal,
movement decisions are made by each sensor on the basis of locally available
information and do not require any prior knowledge of the operating conditions
or any manual tuning of key parameters.
We formally prove that, when a sufficient number of sensors are available,
our approach guarantees a complete and uniform coverage. Furthermore, we
demonstrate that the algorithm execution always terminates preventing movement
oscillations.
Numerous simulations show that our algorithm reaches a complete coverage
within reasonable time with moderate energy consumption, even when the target
area has irregular shapes. Performance comparisons between Push&Pull and one of
the most acknowledged algorithms show how the former one can efficiently reach
a more uniform and complete coverage under a wide range of working scenarios.Comment: Technical Report. This paper has been published on Wireless Networks,
Springer. Animations and the complete code of the proposed algorithm are
available for download at the address:
http://www.dsi.uniroma1.it/~novella/mobile_sensors
Dystonia: sparse synapses for D2 receptors in striatum of a DYT1 knock-out mouse model
Dystonia pathophysiology has been partly linked to downregulation and dysfunction of dopamine D2 receptors in striatum. We aimed to investigate the possible morpho-structural correlates of D2 receptor downregulation in the striatum of a DYT1 Tor1a mouse model. Adult control Tor1a+/+ and mutant Tor1a+/â mice were used. The brains were perfused and free-floating sections of basal ganglia were incubated with polyclonal anti-D2 antibody, followed by secondary immune-fluorescent antibody. Confocal microscopy was used to detect immune-fluorescent signals. The same primary antibody was used to evaluate D2 receptor expression by western blot. The D2 receptor immune-fluorescence appeared circumscribed in small disks (~0.3â0.5 ÎŒm diameter), likely representing D2 synapse aggregates, densely distributed in the striatum of Tor1a+/+ mice. In the Tor1a+/â mice the D2 aggregates were significantly smaller (ÎŒm2 2.4 ± SE 0.16, compared to ÎŒm2 6.73 ± SE 3.41 in Tor1a+/+) and sparse, with ~30% less number per microscopic field, value correspondent to the amount of reduced D2 expression in western blotting analysis. In DYT1 mutant mice the sparse and small D2 synapses in the striatum may be insufficient to âgateâ the amount of presynaptic dopamine release diffusing in peri-synaptic space, and this consequently may result in a timing and spatially larger nonselective sphere of influence of dopamine action
Mismatch repair testing in breast cancer: the path to tumor-specific immuno-oncology biomarkers
Biomarkers for precision immunotherapy in the metastatic setting: Hope or reality?
Precision immunotherapy is a crucial approach to improve the efficacy of anti-cancer treatments, particularly in the metastatic setting. In this respect, accurate patient selection takes advantage of the multidimensional integration of patients' clinical information and tumour-specific biomarkers status. Among these biomarkers, programmed death-ligand 1, tumour-infiltrating lymphocytes, microsatellite instability, mismatch repair and tumour mutational burden have been widely investigated. However, novel tumour-specific biomarkers and testing methods will further improve patients' outcomes. Here, we discuss the currently available strategies for the implementation of a precision immunotherapy approach in the clinical management of metastatic solid tumours and highlight future perspectives
Some homogenization and corrector results for nonlinear monotone operators
This paper deals with the limit behaviour of the solutions of quasi-linear
equations of the form \ \ds -\limfunc{div}\left(a\left(x, x/{\varepsilon
_h},Du_h\right)\right)=f_h on with Dirichlet boundary conditions.
The sequence tends to and the map is
periodic in , monotone in and satisfies suitable continuity
conditions. It is proved that weakly in , where is the solution of a homogenized problem \
-\limfunc{div}(b(x,Du))=f on . We also prove some corrector results,
i.e. we find such that in
New algorithms for adaptive optics point-spread function reconstruction
Context. The knowledge of the point-spread function compensated by adaptive
optics is of prime importance in several image restoration techniques such as
deconvolution and astrometric/photometric algorithms. Wavefront-related data
from the adaptive optics real-time computer can be used to accurately estimate
the point-spread function in adaptive optics observations. The only
point-spread function reconstruction algorithm implemented on astronomical
adaptive optics system makes use of particular functions, named .
These functions are derived from the mirror modes, and their number
is proportional to the square number of these mirror modes. Aims. We present
here two new algorithms for point-spread function reconstruction that aim at
suppressing the use of these functions to avoid the storage of a
large amount of data and to shorten the computation time of this PSF
reconstruction. Methods. Both algorithms take advantage of the eigen
decomposition of the residual parallel phase covariance matrix. In the first
algorithm, the use of a basis in which the latter matrix is diagonal reduces
the number of functions to the number of mirror modes. In the second
algorithm, this eigen decomposition is used to compute phase screens that
follow the same statistics as the residual parallel phase covariance matrix,
and thus suppress the need for these functions. Results. Our
algorithms dramatically reduce the number of functions to be computed
for the point-spread function reconstruction. Adaptive optics simulations show
the good accuracy of both algorithms to reconstruct the point-spread function.Comment: Accepte
Shape of the Galactic Orbits in the CNOC1 Clusters
We present an analysis of the orbital properties in 9 intermediate-redshifts
cluster of the CNOC1 survey and we compare them to a control sample of 12
nearby clusters. Similar to the nearby elliptical galaxies, the bulge-dominated
galaxies in clusters at redshifts ~0.1-0.4 present orbits that are more
eccentric than those for disk-dominated galaxies. However, the orbital
segregation is less significant than that found for elliptical and spiral
galaxies in nearby cluster. When galaxies are separated by colors - red
galaxies with colors in the rest frame (U-V)_o > 1.4, and blue galaxies with
(U-V)_o =< 1.4 - the strongest orbital segregation is found. Therefore, the
segregation we found seems to modify more efficiently the star formation
activity than the internal shape of the galaxies. When we compare the orbits of
early-type galaxies at intermediate-redshift with those for z=0, they seem to
develop significant changes getting much more eccentric. A different behavior
is observed in the late-type galaxies, which present no-significant evolution
in their orbit shapes.Comment: Accepted for publication in ApJ, April 2000. Latex with aaspp4.sty,
20 pages, 4 tables, 6 eps figure
A microscopic 2D lattice model of dimer granular compaction with friction
We study by Monte Carlo simulation the compaction dynamics of hard dimers in
2D under the action of gravity, subjected to vertical and horizontal shaking,
considering also the case in which a friction force acts for horizontal
displacements of the dimers. These forces are modeled by introducing effective
probabilities for all kinds of moves of the particles. We analyze the dynamics
for different values of the time during which the shaking is applied to
the system and for different intensities of the forces. It turns out that the
density evolution in time follows a stretched exponential behavior if is
not very large, while a power law tail develops for larger values of .
Moreover, in the absence of friction, a critical value exists which
signals the crossover between two different regimes: for the
asymptotic density scales with a power law of , while for
it reaches logarithmically a maximal saturation value. Such behavior smears out
when a finite friction force is present. In this situation the dynamics is
slower and lower asymptotic densities are attained. In particular, for
significant friction forces, the final density decreases linearly with the
friction coefficient. We also compare the frictionless single tap dynamics to
the sequential tapping dynamics, observing in the latter case an inverse
logarithmic behavior of the density evolution, as found in the experiments.Comment: 10 pages, 15 figures, to be published in Phys. Rev.
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