117,544 research outputs found
Aubry sets and the differentiability of the minimal average action in codimension one
No full textLet \L(x,u,\nabla u) be a Lagrangian periodic of period in
. We shall study the non self intersecting
functions \fun{u}{\R^n}{\R} minimizing \L; non self intersecting
means that, if
for some and , then
. J. Moser has shown that each of these
functions is at finite distance from a plane
and thus
has an average slope \r; moreover, W. Senn has proven that it is
possible to define the average action of , which is usually called
\b(\r) since it only depends on the slope of .
Aubry and Senn have noticed a connection between \b(\r) and the
theory of crystals in , interpreting \b(\r) as the energy
per area of a crystal face normal to . The polar of \b is usually
called -\a; Senn has shown that \a is and that the
dimension of the flat of \a which contains depends only on the
``rational space'' of \ader. We prove a similar result for the
faces (or the faces of the faces, etc.) of the flats of \a: they
are and their dimension depends only on the rational space of
their normals
Upper bounds on Arnold diffusion times via Mather theory
No full textThis paper considers five examples of hamiltonian systems for which the existence of Arnold's mechanism for diffusion has been shown. These systems have in common that each of them is the perturbation that couples a number of rotators to a pendulum. The main result is that, for all systems considered and for all suffiently small values of the perturbation paramenter, there are orbits whose action variables have a drift of order one in a time which is inversely proportional to the splitting of the homoclinic whiskers. The paper reviews the necessary results concerning the Hamiltonian and uses them to apply Mather theory to the estimate on the drift. These results are important in veryfying the optimality of Nekhoroshev-type theorems
Harmonic embeddings of the Stretched Sierpinski Gasket.
No full textP. Alonso-Ruiz, U. Freiberg and J. Kigami have defined a large family of resistance forms on the Stretched Sierpinski Gasket . In the present paper we introduce a system of coordinates on (technically, an embedding of into ) such that
\noindent) these forms are defined on and
\noindent) all affine functions are harmonic for them.
We do this adapting a standard method from the Harmonic Sierpinski Gasket: we start finding a sequence of pre-fractals such that all affine functions are harmonic on
. After showing that this property is inherited by the stretched harmonic gasket , we use the formula for the Laplacian of a composition to prove that, for a natural measure
on , C^2(\R^2,\R)\subset\dc(\Delta) and Teplyaev's formula for the Laplacian of functions holds. Lastly, we use the expression for to show that the form we have found is closable in
Harmonic embeddings of the Stretched Sierpinski Gasket
No full textP. Alonso-Ruiz, U. Freiberg and J. Kigami have defined a large family of resistance forms on the Stretched Sierpinski Gasket . In the present paper we introduce a system of coordinates on (technically, an embedding of into ) such that
\noindent) these forms are defined on and
\noindent) all affine functions are harmonic for them.
We do this adapting a standard method from the Harmonic Sierpinski Gasket: we start finding a sequence of pre-fractals such that all affine functions are harmonic on
. After showing that this property is inherited by the stretched harmonic gasket , we use the formula for the Laplacian of a composition to prove that, for a natural measure
on , C^2(\R^2,\R)\subset\dc(\Delta) and Teplyaev's formula for the Laplacian of functions holds. Lastly, we use the expression for to show that the form we have found is closable in
I centri antifumo in Italia e il progetto 6elle
No full textFumare tabacco si configura spesso come una dipendenza patologica, cronica e recidivante, che
è causata dalla nicotina (tabagismo). Favorire la cessazione del fumo dovrebbe essere parte integrante dell’approccio
clinico di ogni medico o altro operatore sanitario nell’ambito della sua pratica professionale quotidiana.
Le linee guida basate sull’evidenza scientifica raccomandano interventi di I e II livello per la cessazione del fumo,
efficaci e con ottimo rapporto costo/benefico. Il Pediatra si trova in una posizione privilegiata per poter svolgere
azioni volte a favorire la cessazione del fumo in soggetti fumatori adulti, perché questi in virtù della stretta relazione
con i pazienti pediatrici, possono essere più motivati ad intraprendere un tentativo di cessazione del fumo.
Questo articolo descrive brevemente la storia e le caratteristiche operative della rete dei centri antifumo in Italia,
come strutture di servizio per svolgere interventi di II livello, e descrive inoltre il progetto 6elle, che propone un
modello per svolgere interventi individuali di I livello per la cessazione del fumo, facilmente applicabile nella
pratica clinica e basato sull’uso di semplici strumenti operativi, accessibili attraverso un sito web dedicato e applicabili
seguendo una procedura modulare
PGP Bacteria as Key Drivers for Cadmium Mitigation in Agricultural Ecosystems
No full textCadmium (Cd) contamination in agricultural ecosystems poses a critical challenge due to its toxicity, impact on human health, and threats to environmental sustainability (Massa et al., Microorganisms 2022). As a highly mobile and bioavailable metal, Cd readily migrates from soil and water into the edible portions of crops. Current management strategies to mitigate Cd levels focus on reducing its bioavailability in soil and minimizing its transfer to plant tissues. Among these, the use of Cd-tolerant plant growth-promoting (PGP) bacteria has emerged as a promising solution offering a sustainable strategy for mitigating Cd contamination in agricultural systems (Xiao et al., Ecotoxicology and Environmental Safety, 2023).
The aim of this study is to characterize Cd resistant bacterial strains with PGP activity towards edible plants in the presence of the metal in order to assess the possibility to use bioinoculants to reduce Cd uptake.
Within the screened collection, Serratia plymuthica strains As3-5a(5) (Cd MIC > 3 mM) and SC3-I2 (Cd MIC > 4 mM), and Pseudomonas koreensis strain 69RS (Cd MIC > 2 mM) exhibited PGP activities also in the presence of Cd. Particularly, their ACC deaminase activity was higher in the presence of 0.4 mM Cd(II). In plant growth pouches experiments, root and shoot biomass and seed germination of Oryza sativa (L.) and Solanum Lycopersicon (L.) increased in inoculated plants in the presence of 0.1 and 0.5 mM Cd(II).
The present work highlighted the ability of Cd-resistant PGP bacteria to increase Cd resistance of plants and ongoing experiments will ascertain their effect on metal uptake in plant tissues. Acknowledgments: This work was supported by PSR 2021 Linea 6 1H_HUB project. A.M. is awarded by a PhD fellowship by the University of Milan - Food Systems PhD Program
Molecular characterization of intestinal microbiota in infants fed with soymilk
No full textIntestinal bacteria play an important role in the postnatal development of the immune system. The composition of gut microbiota is profoundly influenced by the infant's diet, but there is little information about the effects of soymilk on the composition of intestinal biota. The present study was designed to investigate the intestinal ecosystem of the newborn in relation to the consumption of soymilk.
Twelve infants had their bovine milk-based formula replaced with soymilk. The intestinal microbial composition of the infants was investigated before and after the change by means of polymerase chain reaction-denaturing gradient gel electrophoresis. In addition, species-specific amplification of 10 Bifidobacterium species, 3 Ruminococcus species, and the Bacteroides group was performed.
Denaturing gradient gel electrophoresis analysis revealed bacterial profiles characterized by numerous bands typical for each subject. No variations were detected by species-specific polymerase chain reaction.
The data demonstrate that soymilk feeding does not alter the intestinal flora of infants and decrease the intestinal bifidobacterial population
Molecular characterization of intestinal microbiota in infants fed with soymilk
No full textIntestinal bacteria play an important role in the postnatal development of the immune system. The composition of gut microbiota is profoundly influenced by the infant's diet, but there is little information about the effects of soymilk on the composition of intestinal biota. The present study was designed to investigate the intestinal ecosystem of the newborn in relation to the consumption of soymilk.Twelve infants had their bovine milk-based formula replaced with soymilk. The intestinal microbial composition of the infants was investigated before and after the change by means of polymerase chain reaction-denaturing gradient gel electrophoresis. In addition, species-specific amplification of 10 Bifidobacterium species, 3 Ruminococcus species, and the Bacteroides group was performed.Denaturing gradient gel electrophoresis analysis revealed bacterial profiles characterized by numerous bands typical for each subject. No variations were detected by species-specific polymerase chain reaction.The data demonstrate that soymilk feeding does not alter the intestinal flora of infants and decrease the intestinal bifidobacterial population
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