1,282 research outputs found
Measure valued solutions of sub-linear diffusion equations with a drift term
In this paper we study nonnegative, measure valued solutions of the initial
value problem for one-dimensional drift-diffusion equations when the nonlinear
diffusion is governed by an increasing function with . By using tools of optimal transport, we will show
that this kind of problems is well posed in the class of nonnegative Borel
measures with finite mass and finite quadratic momentum and it is the
gradient flow of a suitable entropy functional with respect to the so called
-Wasserstein distance. Due to the degeneracy of diffusion for large
densities, concentration of masses can occur, whose support is transported by
the drift. We shall show that the large-time behavior of solutions depends on a
critical mass , which can be explicitely characterized in terms of
and of the drift term. If the initial mass is less then ,
the entropy has a unique minimizer which is absolutely continuous with respect
to the Lebesgue measure. Conversely, when the total mass of the solutions
is greater than the critical one, the steady state has a singular part in which
the exceeding mass is accumulated.Comment: 30 page
Toward third order ghost imaging with thermal light
Recently it has been suggested that an enhancement in the visibility of ghost
images obtained with thermal light can be achieved exploiting higher order
correlations [3]. This paper reports on the status of an higher order ghost
imaging experiment carried on at INRIM labs exploiting a pseudo-thermal source
and a CCD camera.Comment: To be published in Proceedings of Recent advances in Foundations of
Quantum Mechanics and Quantum Informatio
Radiation Balance and Production of Forage Crops in a Mediterranean Region
This study is devoted to measure the radiation use efficiency (RUE) and the extinction light coefficient (k) of a sainfoin crop, cultivated in a site of Southern Italy. The same parameters are measured also for the global solar radiation (in this case kg and RUEg, respectively). The crop was maintened in well watered conditions and the measures were carried out during four cut cycles, one during 1994 and three during 1995. Transmitted, incident, soil and canopy reflected radiations were measured continously during the growth season. The results were given a mean of 2.61 and 1.2 g MJ-1 for RUE and RUEg, respectively and 0.86 and 0.71 for k and kg, respectively. These values, comparable with other similar results, confirm the good adaption of this forage crop to the Mediterranean conditions
Kernel estimates for nonautonomous Kolmogorov equations with potential term
Using time dependent Lyapunov functions, we prove pointwise upper bounds for
the heat kernels of some nonautonomous Kolmogorov operators with possibly
unbounded drift and diffusion coefficients and a possibly unbounded potential
term
Generation of large scale digital evaluation models via synthetic aperture radar interferometry
We investigate the possibility to generate a large-scale Digital Elevation Model by applying the Synthetic Aperture Radar interferometry technique and using tandem data acquired by the ERS-1/ERS-2 sensors. The presented study
is mainly focused on the phase unwrapping step that represents the most critical point of the overall processing chain. In particular, we concentrate on the unwrapping problems related to the use of a large ERS tandem data set that, in order to be unwrapped, must be partitioned. The paper discusses the inclusion of external information (even rough) of the scene topography, the application of a region growing unwrapping technique and the insertion of possible constraints on the phase to be
retrieved in order to minimize the global unwrapping errors. Our goal is the generation of a digital elevation model relative to an area of 300 km by 100km located in
the southern part of Italy. Comparisons between the achieved result and a precise digital terrain model, relative to a smaller area, are also included
Joint multi-baseline SAR interferometry
We propose a technique to provide interferometry by combining multiple images of the same area. This technique differs from the multi-baseline approach in literature as (a) it exploits all the images simultaneously, (b) it performs a spectral shift preprocessing to remove most of the decorrelation, and (c) it exploits distributed targets. The technique is mainly intended for DEM generation at centimetric accuracy, as well as for differential interferometry. The problem is framed in the contest of single-input multiple-output (SIMO) channel estimation via the cross-relations (CR) technique and the resulting algorithm provides significant improvements with respect to conventional approaches based either on independent analysis of single interferograms or multi-baselines phase analysis of single pixels of current literature, for those targets that are correlated in all the images, like for long-term coherent areas, or for acquisitions taken with a short revisit time (as those gathered with future satellite constellations)
The combination of DInSAR and facility damage data for the updating of slow-moving landslide inventory maps at medium scale
Abstract. Testing innovative procedures and techniques to update landslide inventory maps is a timely topic widely discussed in the scientific literature. In this regard remote sensing techniques â such as the Synthetic Aperture Radar Differential Interferometry (DInSAR) â can provide a valuable contribution to studies concerning slow-moving landslides in different geological contexts all over the world. In this paper, DInSAR data are firstly analysed via an innovative approach aimed at enhancing both the exploitation and the interpretation of remote sensing information; then, they are complemented with the results of an accurate analysis of survey-recorded damage to facilities due to slow-moving landslides. In particular, after being separately analysed to provide independent landslide movement indicators, the two datasets are combined in a DInSAR-Damage matrix which can be used to update the state of activity of slow-moving landslides. Moreover, together with the information provided by geomorphological maps, the two datasets are proven to be useful in detecting unmapped phenomena. The potentialities of the adopted procedure are tested in an area of southern Italy where slow-moving landslides are widespread and accurately mapped by using geomorphological criteria
Full characterization of Gaussian bipartite entangled states by a single homodyne detector
We present the full experimental reconstruction of Gaussian entangled states
generated by a type--II optical parametric oscillator (OPO) below threshold.
Our scheme provides the entire covariance matrix using a single homodyne
detector and allows for the complete characterization of bipartite Gaussian
states, including the evaluation of purity, entanglement and nonclassical
photon correlations, without a priori assumptions on the state under
investigation. Our results show that single homodyne schemes are convenient and
robust setups for the full characterization of OPO signals and represent a tool
for quantum technology based on continuous variable entanglement.Comment: 4 pages, 3 figures, slightly longer version of published PR
The FDA âblack boxâ warning on antidepressant suicide risk in young adults: More harm than benefits?
The decision made in the year 2004 by the U.S. Food and Drug Administration (FDA) to require a boxed warning on antidepressants regarding the risk of suicidality in young adults still represents a matter of controversy. The FDA warning was grounded on industry-sponsored trials carried one decade ago or earlier. However, within the past decade, an increasing number of reports have questioned the actual validity of the FDA warning, especially considering a decline in the prescription of the antidepressant drugs associated with an increase in the rate of suicidal events among people with severe depression. The present report provides an overview of the FDA black box warning, also documenting two Major Depressive Disorder patients whose refusal to undergo a pharmacological antidepressant treatment possibly led to an increased risk for suicidal behaviors. The concerns raised by the FDA black box warning need to be considered in real-world clinical practice, stating the associated clinical and public health implications
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