Search results for "BIF"
showing 10 items of 539 documents
On the numerical solution of some finite-dimensional bifurcation problems
1981
We consider numerical methods for solving finite-dimensional bifurcation problems. This paper includes the case of branching from the trivial solution at simple and multiple eigenvalues and perturbed bifurcation at simple eigenvalues. As a numerical example we treat a special rod buckling problem, where the boundary value problem is discretized by the shooting method.
Ruolo dei parassitoidi oofagi nel controllo naturale dei fitofagi del nocciolo responsabili del “cimiciato delle nocciole” nel Parco dei Nebrodi (ME).
2009
Role of oophagous parasitoids in the natural control of hazelnut bugs inducing the “cimiciato seeds” in Nebrodi Park (ME) Oophagous parasitoids of bugs collected on hazelnut cultivations and seasonal parasitism on eggs of Gonocerus acutengulatus (Goeze) were studied from 2004 to 2006 in the Nebrodi Park (ME). Samples of bug eggs were collected in three altitude areas, 300-590, 600-890 and 900-1100 m above sea level, and examined in laboratory. Parasitoid adults obtained from all eggs were identified. Parasitization levels, detected on G. acuteangulatus in all areas showed a similar trend with the most value on August. Significant regression between the total number of eggs and the number of…
Pattern formation and transition to chaos in a chemotaxis model of acute inflammation
2021
We investigate a reaction-diffusion-chemotaxis system that describes the immune response during an inflammatory attack. The model is a modification of the system proposed in Penner, Ermentrout, and Swigon [SIAM J. Appl. Dyn. Syst., 11 (2012), pp. 629-660]. We introduce a logistic term in the immune cell dynamics to reproduce the macrophages' activation, allowing us to describe the disease evolution from the early stages to the acute phase. We focus on the appearance of pattern solutions and their stability. We discover steady-state (Turing) and wave instabilities and classify the bifurcations deriving the corresponding amplitude equations. We study stationary radially symmetric solutions an…
Gallium-68 and scandium-44 labelled radiotracers based on curcumin structure linked to bifunctional chelators: Synthesis and characterization of pote…
2019
Abstract Curcumin metal complexes showed widespread applications in medicine and can be exploited as a lead structure for developing new tracers for nuclear medicine application. Herein, the synthesis, chemical characterization and radiolabelling with gallium-68 and scandium-44 of two new targeting vectors based on curcumin scaffolds and linked to the chelators 1,4,7-triazacyclononane,1-glutaric acid-4,7-acetic acid (NODAGA) and 1,4-bis(carboxymethyl)-6-[bis(carboxymethyl)]amino-6-methylperhydro-1,4-diazepine (AAZTA) are reported. Synthesis of the precursors could be achieved with a 13% and 11% yield and radiolabelling generally afforded rapid incorporation under mild conditions (>95%). Sta…
Bifurcations of cuspidal loops
1997
A cuspidal loop for a planar vector field X consists of a homoclinic orbit through a singular point p, at which X has a nilpotent cusp. This is the simplest non-elementary singular cycle (or graphic) in the sense that its singularities are not elementary (i.e. hyperbolic or semihyperbolic). Cuspidal loops appear persistently in three-parameter families of planar vector fields. The bifurcation diagrams of unfoldings of cuspidal loops are studied here under mild genericity hypotheses: the singular point p is of Bogdanov - Takens type and the derivative of the first return map along the orbit is different from 1. An analytic and geometric method based on the blowing up for unfoldings is propos…
Reinforced cyclam derivatives functionalized on the bridging unit
2016
International audience; A new synthetic method has been developed for the preparation of reinforced cyclams (1,4,8,11-tetraazacyclotetradecane) C-functionalized on the bridging unit, by using a "one pot" reaction starting from the appropriate bis-aminal cyclam intermediate. The high reactivity of quaternized aminal moiety toward nucleophilic agent has been used to elaborate a new class of cross-bridged and side-bridged cyclam derivatives containing cyanide group on the ethylene bridge. Several chelators and corresponding copper(II) complexes have been prepared and characterized by X-ray diffraction. These new constrained polyazamacrocycles are valuable precursors of bifunctional chelating a…
POSS-Al-porphyrin-imidazolium cross-linked network as catalytic bifunctional platform for the conversion of CO2 with epoxides
2023
Two heterogeneous catalysts were prepared with the aim of following the promising path of CO2 fixation into epoxides. The synthetic procedure involves a radical copolymerization of an octavinylsilsesquioxane as inorganic core building block and tetrastyrylporphyrin aluminum chloride monomer (TSP-AlCl) in presence (POSS-TSP-AlCl-imiBr) or in absence (POSS-TSP-AlCl) of a bis-vinylimidazolium bromide salt (bis-imiBr), in order to investigate if the bifunctional heterogeneous material can display better catalytic performance than the separate species. All the solids were fully characterized and tested in the synthesis of cyclic carbonates starting from CO2 and several epoxides. The synergic coo…
Contribution of Molecular Structure to Self-Assembling and Biological Properties of Bifunctional Lipid-Like 4-(N-Alkylpyridinium)-1,4-Dihydropyridines
2019
The design of nanoparticle delivery materials possessing biological activities is an attractive strategy for the development of various therapies. In this study, 11 cationic amphiphilic 4-(N-alkylpyridinium)-1,4-dihydropyridine (1,4-DHP) derivatives differing in alkyl chain length and propargyl moiety/ties number and position were selected for the study of their self-assembling properties, evaluation of their cytotoxicity in vitro and toxicity on microorganisms, and the characterisation of their interaction with phospholipids. These lipid-like 1,4-DHPs have been earlier proposed as promising nanocarriers for DNA delivery. We have revealed that the mean diameter of freshly prepared nanoparti…
Adaptive control of a seven mode truncation of the Kolmogorov flow with drag
2009
Abstract We study a seven dimensional nonlinear dynamical system obtained by a truncation of the Navier–Stokes equations for a two dimensional incompressible fluid with the addition of a linear term modelling the drag friction. We show the bifurcation sequence leading from laminar steady states to chaotic solutions with increasing Reynolds number. Finally, we design an adaptive control which drives the state of the system to the equilibrium point representing the stationary solution.
Novel Probiotic Bifidobacterium longum subsp. infantis CECT 7210 Strain Active against Rotavirus Infections
2011
ABSTRACT Rotavirus is the leading cause of severe acute gastroenteritis among children worldwide. It is well known that breast-feeding and vaccination afford infants protection. Since breast-feeding has drastically decreased in developed countries, efforts have been focused on the potential use of probiotics as preventive agents. In this study, a novel Bifidobacterium longum subsp. infantis strain was isolated from infant feces and selected, based on its capacity to inhibit in vitro rotavirus Wa replication (up to 36.05% infectious foci reduction) and also to protect cells from virus infection (up to 48.50% infectious foci reduction) in both MA-104 and HT-29 cell lines. Furthermore, studies…