Search results for "Diffusion"

Neptunium(V) Sorption and Diffusion in Opalinus Clay

2009

The sorption and diffusion behavior of 8 x 10(-6) M Np(V) in Opalinus Clay (OPA) with synthetic pore water (pH 7.6) as mobile phase was studied under ambient conditions by batch and diffusion experiments, respectively. The Kd value determined by batch experiments with OPA suspensions is equal to 0.025 +/- 0.005 m3/kg. The diffusion-accessible porosity epsilon of intact OPA as determined by through- and out-diffusion experiments with tritiated water (HTO) is equal to 0.15 +/- 0.01. The diffusion coefficient De and the rock capacity factor alpha of 22Na+ in OPA were measured by through-, out-, and in-diffusion experiments and asserted the reliability of these diffusion techniques. For the dif…

Modeling multiple taxis: Tumor invasion with phenotypic heterogeneity, haptotaxis, and unilateral interspecies repellence

2021

We provide a short review of existing models with multiple taxis performed by (at least) one species and consider a new mathematical model for tumor invasion featuring two mutually exclusive cell phenotypes (migrating and proliferating). The migrating cells perform nonlinear diffusion and two types of taxis in response to non-diffusing cues: away from proliferating cells and up the gradient of surrounding tissue. Transitions between the two cell subpopulations are influenced by subcellular (receptor binding) dynamics, thus conferring the setting a multiscale character. We prove global existence of weak solutions to a simplified model version and perform numerical simulations for the full se…

A dynamic subgrid-scale tensorial eddy viscosity model

1999

In the Navier-Stokes equations the removal of the turbulent fluctuating velocities with a frequency above a certain fixed threshold, employed in the Large Eddy Simulation (LES), causes the appearance of a turbulent stress tensor that requires a number of closure assumptions. In this paper insufficiencies are demonstrated for those closure models which are based on a scalar eddy viscosity coefficient. A new model, based on a tensorial eddy viscosity, is therefore proposed; it employs the Germano identity [1] and allows dynamical evaluation of the single required input coefficient. The tensorial expression for the eddy viscosity is deduced by removing the widely used scalar assumption of the …

Critical Phenomena and Diffusion in Complex Systems

2008

How does diversity affect district innovation systems?Findings from a comparative study of european ceramics

2018

This research applies Nelson’s (1993) primary typology of enterprises to understand why the propensity for innovation varies across ceramics district innovation systems in Europe. We use innovation systems and industrial district theories to explore the innovation capacity of the two most important ceramic tile industrial districts in Europe—Emilia Romagna in Italy and Castellon in Spain. Our analysis shows that, in both districts, innovation plays a decisive role in allowing companies to maintain competitiveness in a globalizing market. However, by comparing the composition of their district innovation systems, our analysis shows that: (i) although levels of competition in both districts a…

Un museo de ciencia accesible a la sociedad. Contribución e impacto

2022

El conocimiento es objeto de investigación y discusión; la ciudadanía lo utiliza de manera crítica transformándolo en herramientas que les permiten mejorar su vida a nivel individual y colectivo. Las diferencias sociales y jerárquicas que históricamente determinaban el acceso al capital formativo se han difuminado en el último siglo, y cada vez más se consume una gran variedad de formas de cultura, independientemente del nivel social, económico o cultural. Entre los centros culturales más visitados por los y las ciudadanas encontramos los museos. Estos núcleos de conocimiento trabajan para que su finalidad comunicativa esté en sintonía con los contenidos que ofrecen y tratan de dar respuest…

De la diffusion des savoirs universitaires dans la formation des maîtres. L'exemple du mémoire professionnel des professeurs des écoles

2007

07076. 12 p.; En prenant appui sur une étude des bibliographies des mémoires professionnels, cette enquête a tenté d'évaluer quelques aspects de la diffusion des savoirs issus de la recherche universitaire dans la formation des maîtres du premier degré.

Atmospheric dry deposition processes of particles on urban and suburban surfaces: Modelling and validation works

2019

Abstract Dry deposition process is one of the important pathways for the removal of particles from atmosphere. It is the result of a combination of different environmental and physical factors as atmospheric conditions, particle properties, characteristics of the canopy. For this latter factor, urban canopy represents unevenly combinations of different types of surface elements that increases the complexity of deposition process phenomena. Therefore, particle dry deposition on urban surfaces is not easy to configure and, although empirical or semi-empirical models in literature have been developed to address this aspect, there is not standardized and commonly accepted criteria, especially f…

VESICAL IMAGING-REPORTING AND DATA SYSTEM – A NEW APPROACH TO BLADDER CANCER STAGING

2022

The aim: To present the assumptions and to show the usefulness of Vesical Imaging-Reporting and Data System (VI-RADS) based on multiparametric magnetic resonance imaging (mpMRI) in the diagnostic pathway management of patients with a bladder cancer. Materials and methods: The review is based on available literature from last 10 years from PubMed database and the Przegląd Urologiczny journal focusing on articles on VI-RADS. Overall, 18 articles were included. Presented magnetic resonance images come from the examinations of the patients who were diagnosed with bladder cancer from 2019 to 2021 at Department of Diagnostic Imaging in University Clinical Hospital in Opole, Poland. Conclusions: T…

An In Vitro Experiment for Postmortem Vascular Permeation. The Passage of Morphine and Morphine Glucuronides Across a Vascular Wall

1997

A venous blood sample taken at autopsy cannot be considered to represent the antemortem blood concentration of a particular substance. Autolytic processes cause disintegration and increasing permeability of the physiological and anatomical barriers such as vascular walls and lead to changes in substance concentrations. In the present study, the experimental design represents an in vitro postmortem simulation of a drug substance crossing a venous wall. The postmortem behavior of morphine, morphine-3- and morphine-6-glucuronide was investigated. A Chien-Valia-diffusion chamber with a patch of inferior vena cava as diffusion barrier was used. For optimal simulation of postmortem events, vein s…