Effets de la perfusion de facteurs natriurétiques auriculaires synthétiques sur quelques flux régionaux chez le volontaire sain [Effect of synthetic atrial natriuretic factors on various regional blood flows in the healthy subject]

The effects of continuous infusions of 2 synthetic atrial natriuretic peptides Ile12-(3-28) (rANP) and Meth12-(3-28) (hANP) eicosahexapeptides on blood pressure, heart rate, skin blood flow, glomerular filtration rate, renal plasma flow, apparent hepatic blood flow, and carotid blood flow were evaluated in normal volunteers. A rANP infusion at increasing rates (1-40 micrograms/min) induced a decrease in blood pressure, an increase in heart rate and in skin blood flow linearly related to the dose administered. In contrast, hANP infusion at 1 microgram/min for 4 hours induced an initial increase followed by a secondary fall in skin blood flow without blood pressure changes. A 4-hour rANP infusion at 0.5 and 5 mcg/min did not alter glomerular filtration rate but induced a delayed and dose-related fall in renal plasma flow from 531 to 461 (p less than 0.05), and from 554 to 342 ml/min (p less than 0.001) respectively, with a consequential rise in the filtration fraction. The 5 mcg/min dose furthermore significantly reduced blood pressure following a latency period of 2.5 hours. A 2-hours rANP infusion at 0.5 micrograms/min induced a fall in apparent hepatic blood flow from 1,087 to 863 ml/min (p less than 0.01), without simultaneously altering blood pressure. Similarly, a 2-hour hANP infusion at 2 micrograms/min altered neither blood pressure nor carotid blood flow. In conclusion, ANP infusion induced changes in systemic and regional hemodynamics varying in direction, intensity and duration.

Particle dispersion in synthetic turbulent flows

We study particle dispersion advected by a synthetic turbulent flow from a Lagrangian perspective and focus on the two-particle and cluster dispersion by the flow. It has been recently reported that Richardson¿s law for the two-particle dispersion can stem from different dispersion mechanisms, and can be dominated by either diffusive or ballistic events. The nature of the Richardson dispersion depends on the parameters of our flow and is discussed in terms of the values of a persistence parameter expressing the relative importance of the two above-mentioned mechanisms. We support this analysis by studying the distribution of interparticle distances, the relative velocity correlation functions, as well as the relative trajectories.

Langevin approach to generate synthetic turbulent flows

We present an analytical scheme, easily implemented numerically, to generate synthetic Gaussian turbulent flows by using a linear Langevin equation, where the noise term acts as a stochastic stirring force. The characteristic parameters of the velocity field are well introduced, in particular the kinematic viscosity and the spectrum of energy. As an application, the diffusion of a passive scalar is studied for two different energy spectra. Numerical results are compared favorably with analytical calculations.

Diffusive transport in spatially periodic hydrodynamic flows

We calculate the effective diffusion coefficient in convective flows which are well described by one spatial mode. We use an expansion in the distance from onset and homogenization methods to obtain an explicit expression for the transport coefficient. We find that spatially periodic fluid flow enhances the molecular diffusion D by a term proportional to D-1. This enhancement should be easy to observe in experiments, since D is a small number.

The reconstruction of social meaning in the space of flows

Artikkeli on alunperin julkaistu teoksessa: The informational city (1989) / Manuel Castells

Inter-firm labor mobility and knowledge diffusion: a theoretical approach

[cat] Analitzem una economia amb dues característiques principals: la mobilitat dels treballadors implica transferència de coneixement i la productivitat de l’empresa augmenta amb l’intercanvi de coneixement. Cada empresa desenvolupa un tipus de coneixement que serà trasmès a la resta de la indústria mitjançant la mobilitat de treballadors. Estudiem dues estructures de mercat laboral i utilitzant un anàlisi comparatiu derivem les implicacions del model. Els resultats revelen com la mobilitat de treballadors depèn en la varietat i nivell del coneixement, la presència de costos de mobilitat, les institucions, la capacitat d’absorvir coneixement per part de les empreses i la mida de la indústria. Els resultats no depenen de l’estructura del mercat laboral.

Knowledge hierarchy and professional knowledge

The aim of this article is to substantiate, in the sociological point of view, the distinction between the social and cognitive processes that produce knowledge in knowledge abstract systems - KAS - to generate cultural inequality and the micro processes of knowledge usage, which build local and cultural knowledge from common sense. It is circumscribed to this aim a problematization of knowledge usage developed by middle class salaried professional groups, rich in cultural capital but without equivalent symbolical capital, in a capitalist society at risk. In order to achieve this goal, the classical contributions of Pierre Bourdieu, Boaventura Sousa Santos, Donald Schön and Basil Bernstein (among others) are taken as a basis regarding the limitation of critical and reflexive thinking and the virtues of professional knowledge to support an epistemology of professional practice.

A process for mining science & technology documents databases, illustrated for the case of "knowledge discovery and data mining"

This paper presents a process of mining research & development abstract databases to profile current status and to project potential developments for target technologies, The process is called "technology opportunities analysis." This article steps through the process using a sample data set of abstracts from the INSPEC database on the topic o "knowledge discovery and data mining." The paper offers a set of specific indicators suitable for mining such databases to understand innovation prospects. In illustrating the uses of such indicators, it offers some insights into the status of knowledge discovery research*.

The construction process of pedagogical knowledge among nursing professors

Didactic knowledge about contents is constructed through an idiosyncratic synthesis between knowledge about the subject area, students' general pedagogical knowledge and the teacher's biography. This study aimed to understand the construction process and the sources of Pedagogical Content Knowledge, as well as to analyze its manifestations and variations in interactive teaching by teachers whom the students considered competent. Data collection involved teachers from an undergraduate nursing program in the South of Brazil, through non-participant observation and semistructured interviews. Data analysis was submitted to the constant comparison method. The results disclose the need for initial education to cover pedagogical aspects for nurses; to assume permanent education as fundamental in view of the complexity of contents and teaching; to use mentoring/monitoring and the value learning with experienced teachers with a view to the development of quality teaching.

Long-Life Concrete: How Long Will My Concrete Last? A Synthesis of Knowledge of Potential Durability of Concrete, TPF-5(159), 2013

There is an ongoing discussion about moving toward performance-based specifications for concrete pavements. This document seeks to move the discussion forward by outlining the needs and the challenges, and proposing some immediate actions. However, this approach may increase risk for all parties until performance requirements are agreed upon and, more importantly, how the requirements can be measured. A fundamental issue behind pavement construction activities is that the owner/designer needs to be assured that the concrete in place will survive for the intended period (assuming there are no changes in the environment or loading) and, therefore, that full payment should be made. At the same time, each party along the supply chain needs to be assured that the material being supplied to them is able to meet the required performance, as is the product/system they are delivering. The focus of this document is a discussion of the issues behind this need, and the technologies that are available, or still needed, to meet this need, particularly from the point of view of potential durability