806 research outputs found
Semi-Galerkin approximation and strong solutions to the equations of the nonhomogeneous asymmetric fluids
This paper analyzes an initial/boundary value problem for a system of equations modelling the nonstationary flow of a nonhomogeneous incompressible asymmetric (polar) fluid. Under conditions similar to those usually imposed to the nonhomogeneous 3D Navier-Stokes equations,
by using a spectral semi-Galerkin method, we prove the existence of a local in time strong solution. We also prove the uniqueness of the strong solution and some global existence results. Several estimates for the solutions and their approximations are given. These can be used to find useful error bounds of the Galerkin approximations.Dans ce papier, on analyse un problème de valeurs initiales et
valeurs aux limites pour un système d’équations aux dérivées
partielles qui modélise le flux instationnaire d’un fluide asymmétrique
incompressible non homogène. Sous des conditions similaires aux conditions usuellement imposées aux équations tridimensionelles de Navier-Stokes non homogènes, à l’aide d’une méthode de type semi-Galerkin, nous démontrons l’éxistence d’une solution forte locale en temps. On établit aussi l’unicité de solution forte et quelques résultats d’éxistence globale. Tous ces résultats reposent sur des estimations appropriées pour les solutions et leurs approximations qui permettent d’ailleurs d´eduire des estimations de l’erreur.Conselho Nacional de Desenvolvimento CientÃfico e Tecnológico (Brasil)Fundação de Amparo à Pesquisa do Estado de São PauloDirección General de Enseñanza Superio
An optimal control problem for a generalized Boussinesq model: The time dependent case
We consider an optimal control problem governed by a system of nonlinear
partial differential equations modelling viscous incompressible flows submitted
to variations of temperature. We use a generalized Boussinesq approximation.
We obtain the existence of the optimal control as well as first order optimality
conditions of Pontryagin type by using the Dubovitskii-Milyutin formalism.Ministerio de Educación y CienciaConselho Nacional de Desenvolvimento CientÃfico e TecnológicoFundação de Amparo à Pesquisa do Estado de São Paul
Lutein and Neurodevelopment in Preterm Infants
No abstract availabl
Existence and uniqueness of strong solutions for the incompressible micropolar fluid equations in domains of R3
We consider the initial boundary value problem for the system of equations describing the nonstationary flow of an incompressible micropolar fluid in a domain Ω of R3.Under hypotheses that are similar to the Navier-Stokes equations ones, by using an iterative scheme, we prove the existence and uniqueness of strong solution in Lp(Ω), for p > 3
Compensatory Feto-Placental Upregulation of the Nitric Oxide System during Fetal Growth Restriction
Background: Fetal Growth Restriction is often associated with a feto-placental vascular dysfunction conceivably involving endothelial cells. Our study aimed to verify this pathogenic role for feto-placental endothelial cells and, coincidentally, demonstrate any abnormality in the nitric oxide system. Methods: Prenatal assessment of feto-placental vascular function was combined with measurement of nitric oxide (in the form of S-nitrosohemoglobin) and its nitrite byproduct, and of the endogenous nitric oxide synthase inhibitor asymmetric dimethylarginine. Umbilical vein endothelial cells were also harvested to determine their gene profile. The study comprised term pregnancies with normal (n = 40) or small-for-gestational-age (n = 20) newborns, small-for-gestational-age preterm pregnancies (n = 15), and bi-chorial, bi-amniotic twin pregnancies with discordant fetal growth (n = 12). Results: Umbilical blood nitrite (p<0.001) and S-nitrosohemoglobin (p = 0.02) rose with fetal growth restriction while asymmetric dimethylarginine decreased (p = 0.003). Nitrite rise coincided with an abnormal Doppler profile from umbilical arteries. Fetal growth restriction umbilical vein endothelial cells produced more nitrite and also exhibited reciprocal changes in vasodilator (upwards) and vasoconstrictor (downwards) transcripts. Elevation in blood nitrite and S-nitrosohemoglobin persisted postnatally in the fetal growth restriction offspring. Conclusion: Fetal growth restriction is typified by increased nitric oxide production during pregnancy and after birth. This response is viewed as an adaptative event to sustain placental blood flow. However, its occurrence may modify the endothelial phenotype and may ultimately represent an element of risk for cardiovascular disease in adult life.Fil: Pisaneschi, Silvia. Università degli Studi di Pisa; Italia. Scuola Superiore Sant’Anna; ItaliaFil: Strigini, Francesca A. L.. Università degli Studi di Pisa; ItaliaFil: Sanchez, Angel Matias. Università degli Studi di Pisa; Italia. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Centro CientÃfico Tecnológico Conicet - Mendoza. Instituto de Medicina y BiologÃa Experimental de Cuyo; ArgentinaFil: Begliuomini, Silvia. Università degli Studi di Pisa; ItaliaFil: Casarosa, Elena. Università degli Studi di Pisa; ItaliaFil: Ripoli, Andrea. National Research Council. Institute of Clinical Physiology, ; ItaliaFil: Ghirri, Paolo. Università degli Studi di Pisa; ItaliaFil: Boldrini, Antonio. Università degli Studi di Pisa; ItaliaFil: Fink, Bruno. Noxygen Science Transfer and Diagnostics; AlemaniaFil: Genazzani, Andrea R.. Università degli Studi di Pisa; ItaliaFil: Coceani, Flavio. Scuola Superiore Sant’Anna; ItaliaFil: Simoncini, Tommaso. Università degli Studi di Pisa; Itali
On an iterative method for approximate solutions of a generalized Boussinesq model
An iterative method is proposed for nding approximate solutions of an initial and boundary value problem for a nonstationary generalized Boussinesq model for thermally driven convection of fluids with temperature
dependent viscosity and thermal conductivity. Under certain conditions, it is
proved that such approximate solutions converge to a solution of the original
problem; moreover, convergence-rate bounds for the constructed approximate solutions are also obtained
catheter and laryngeal mask endotracheal surfactant therapy the calmest approach as a novel mist technique
AbstractPurpose: Neonatal respiratory distress syndrome (RDS) is a major cause of mortality and morbidity among preterm infants. Although the INSURE (INtubation, SURfactant administration, Estubation) technique for surfactant replacement therapy is so far the gold standard method, over the last years new approaches have been studied, i.e. less invasive surfactant administration (LISA) or minimally invasive surfactant therapy (MIST). Here we propose an originally modified MIST, called CALMEST (Catheter And Laryngeal Mask Endotracheal Surfactant Therapy), using a particular laryngeal mask as a guide for a thin catheter to deliver surfactant directly in the trachea.Materials and methods: We performed a preliminary study on a mannequin and a subsequent in vivo pilot trial.Results and conclusions: This novel procedure is quick, effective and well tolerated and might represent an improvement in reducing neonatal stress. Ultimately, CALMEST offers an alternative approach that could be extremely useful for medica..
A sensitivity study of triboson production processes to dimension-6 EFT operators at the LHC
We present the first parton-level study of anomalous effects in triboson
production in both fully and semi-leptonic channels in proton-proton collisions
at 13 TeV at the Large Hadron Collider (LHC). The sensitivity to anomalies
induced by a minimal set of bosonic dimension-6 operators from the Warsaw basis
is evaluated with specific analyses for each final state. A likelihood-based
strategy is employed to assess the most sensitive kinematic observables per
channel, where the contribution of Effective Field Theory operators is
parameterized at either the linear or quadratic level. The impact of the mutual
interference terms of pairs of operators on the sensitivity is also examined.
This benchmark study explores the complementarity and overlap in sensitivity
between different triboson measurements and paves the way for future analyses
at the LHC experiments. The statistical combination of the considered final
states allows setting stringent bounds on five bosonic Wilson coefficients
Massage accelerates brain development and the maturation of visual function
Environmental enrichment (EE) was shown recently to accelerate brain development
in rodents. Increased levels of maternal care, and particularly tactile
stimulation through licking and grooming, may represent a key component in the
early phases of EE. We hypothesized that enriching the environment in terms of
body massage may thus accelerate brain development in infants. We explored the
effects of body massage in preterm infants and found that massage accelerates the
maturation of electroencephalographic activity and of visual function, in
particular visual acuity. In massaged infants, we found higher levels of blood
IGF-1. Massage accelerated the maturation of visual function also in rat pups and
increased the level of IGF-1 in the cortex. Antagonizing IGF-1 action by means of
systemic injections of the IGF-1 antagonist JB1 blocked the effects of massage in
rat pups. These results demonstrate that massage has an influence on brain
development and in particular on visual development and suggest that its effects
are mediated by specific endogenous factors such as IGF-1
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