2,425 research outputs found
Continuity of Optimal Control Costs and its application to Weak KAM Theory
We prove continuity of certain cost functions arising from optimal control of
affine control systems. We give sharp sufficient conditions for this
continuity. As an application, we prove a version of weak KAM theorem and
consider the Aubry-Mather problems corresponding to these systems.Comment: 23 pages, 1 figures, added explanations in the proofs of the main
theorem and the exampl
Optimal time decay of the non cut-off Boltzmann equation in the whole space
In this paper we study the large-time behavior of perturbative classical
solutions to the hard and soft potential Boltzmann equation without the angular
cut-off assumption in the whole space \threed_x with \DgE. We use the
existence theory of global in time nearby Maxwellian solutions from
\cite{gsNonCutA,gsNonCut0}. It has been a longstanding open problem to
determine the large time decay rates for the soft potential Boltzmann equation
in the whole space, with or without the angular cut-off assumption
\cite{MR677262,MR2847536}. For perturbative initial data, we prove that
solutions converge to the global Maxwellian with the optimal large-time decay
rate of O(t^{-\frac{\Ndim}{2}+\frac{\Ndim}{2r}}) in the
L^2_\vel(L^r_x)-norm for any .Comment: 31 pages, final version to appear in KR
Methyl 2-(methylthio)benzoate: the unique sulfur-containing sex pheromone of Phyllophaga crinita
The female-produced sex pheromone of Phyllophaga crinita (Burmeister) (Coleoptera: Scarabaeidae: Melolonthinae; the adult has no common name) is identified as methyl 2-(methylthio)benzoate. This is the first identification of a sulfur-containing, long-distance, female-produced sex attractant from any insect taxa. The root-feeding larvae of this species are serious pests in many crops in Texas and Mexico. In field tests, many P. crinita males were captured in traps baited with the authentic compound. Interestingly, a heteroatom analog, methyl 2-methoxybenzoate, also captured P. crinita males, but only at a dose 10,000 times higher than the lowest tested dose of the authentic pheromon
Celebrating Cercignani's conjecture for the Boltzmann equation
Cercignani's conjecture assumes a linear inequality between the entropy and
entropy production functionals for Boltzmann's nonlinear integral operator in
rarefied gas dynamics. Related to the field of logarithmic Sobolev inequalities
and spectral gap inequalities, this issue has been at the core of the renewal
of the mathematical theory of convergence to thermodynamical equilibrium for
rarefied gases over the past decade. In this review paper, we survey the
various positive and negative results which were obtained since the conjecture
was proposed in the 1980s.Comment: This paper is dedicated to the memory of the late Carlo Cercignani,
powerful mind and great scientist, one of the founders of the modern theory
of the Boltzmann equation. 24 pages. V2: correction of some typos and one
ref. adde
Global existence and full regularity of the Boltzmann equation without angular cutoff
We prove the global existence and uniqueness of classical solutions around an
equilibrium to the Boltzmann equation without angular cutoff in some Sobolev
spaces. In addition, the solutions thus obtained are shown to be non-negative
and in all variables for any positive time. In this paper, we study
the Maxwellian molecule type collision operator with mild singularity. One of
the key observations is the introduction of a new important norm related to the
singular behavior of the cross section in the collision operator. This norm
captures the essential properties of the singularity and yields precisely the
dissipation of the linearized collision operator through the celebrated
H-theorem
Mass Transportation on Sub-Riemannian Manifolds
We study the optimal transport problem in sub-Riemannian manifolds where the
cost function is given by the square of the sub-Riemannian distance. Under
appropriate assumptions, we generalize Brenier-McCann's Theorem proving
existence and uniqueness of the optimal transport map. We show the absolute
continuity property of Wassertein geodesics, and we address the regularity
issue of the optimal map. In particular, we are able to show its approximate
differentiability a.e. in the Heisenberg group (and under some weak assumptions
on the measures the differentiability a.e.), which allows to write a weak form
of the Monge-Amp\`ere equation
A Flexible Robotic Depalletizing System for Supermarket Logistics
Depalletizing robotic systems are commonly deployed to automatize and speed-up parts of logistic processes. Despite this, the necessity to adapt the preexisting logistic processes to the automatic systems often impairs the application of such robotic solutions to small business realities like supermarkets. In this work we propose a robotic depalletizing system designed to be easily integrated into supermarket logistic processes. The system has to schedule, monitor and adapt the depalletizing process considering both on-line perceptual information given by non-invasive sensors and constraints provided by the high-level management system or by a supervising user. We describe the overall system discussing two case studies in the context of a supermarket logistic process. We show how the proposed system can manage multiple depalletizing strategies and multiple logistic requests
The dissipative linear Boltzmann equation for hard spheres
We prove the existence and uniqueness of an equilibrium state with unit mass
to the dissipative linear Boltzmann equation with hard--spheres collision
kernel describing inelastic interactions of a gas particles with a fixed
background. The equilibrium state is a universal Maxwellian distribution
function with the same velocity as field particles and with a non--zero
temperature lower than the background one, which depends on the details of the
binary collision. Thanks to the H--theorem we then prove strong convergence of
the solution to the Boltzmann equation towards the equilibrium.Comment: 17 pages, submitted to Journal of Statistical Physic
Ukrainian refugee crisis management in the Local Health Authority Roma 1: the challenges of implementing public health policies and lessons learned
Background: The conflict between Russia and Ukraine has strained the health systems of countries that welcome war refugees on all levels, from national to local. Despite the Public Health guidelines regarding assistance being published on the topic, the scientific literature currently lacks evidence on the experience of applying theory in practice. This study aims to describe evidence-based practices that were implemented and to provide a detailed description of emerging problems and solutions pertaining Ukrainian refugee assistance in the context of one of the biggest Local Health Authorities in Italy (LHA Roma 1). Methods: LHA Roma 1 developed a strategic plan based on local expertise, national and international guidelines to ensure infectious disease prevention and control, as well as continuity of care for non-communicable diseases and mental health. Results: The insertion of Ukrainian refugees in the National Health System through an identification code assignment and other services such as COVID-19 swab and vaccination were provided either in one of the three major assistance hubs or in local district level ambulatories spread throughout the LHA. Many challenges were faced during the implementation phase of the outlined practice guidelines, which required sensible and timely solutions. These challenges include the necessity of rapid resource provision, overcoming linguistic and cultural barriers, guaranteeing a standard of care across multiple sites and coordination of interventions. Public Private Partnerships, the creation of a centralized multicultural and multidisciplinary team and the mutually beneficial collaboration with the local Ukrainian community were essential to guarantee the success of all operations. Conclusions: The experience of LHA Roma 1 helps shed light on the importance of leadership in emergency settings and how a dynamic relationship between policy and practice would allow each intervention to be modulated according to the local environment, to better realize the potential of local realities to provide appropriate health interventions to all those in need
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