Experimental investigation of laminar turbulent intermittency in pipe flow

In shear flows turbulence first occurs in the form of localized structures (puffs/spots) surrounded by laminar fluid. We here investigate such spatially intermittent flows in a pipe experiment showing that turbulent puffs have a well defined interaction distance, which sets the minimum spacing of puffs as well as the maximum observable turbulent fraction. Two methodologies are employed here. Starting from a laminar flow puffs can be created by locally injecting a jet of fluid through the pipe wall. When the perturbation is applied periodically at low frequencies, as expected, a regular sequence of puffs is observed where the puff spacing is given by the ratio of the mean flow speed to the perturbation frequency. On the other hand, at large frequencies puffs are found to interact and annihilate each other. Varying the perturbation frequency an interaction distance can be determined. In the second set of experiments, the Reynolds number is reduced suddenly from fully developed turbulence to the intermittent regime.The resulting flow reorganizes itself to a sequence of constant size puffs which, unlike in Couette and Taylor Couette flow are randomly spaced. The minimum distance between the turbulent patches is identical to the puff interaction length. The puff interaction length is found to be in excellent agreement with the wavelength of regular stripe and spiral patterns in plane Couette and Taylor-Couette flow. We propose that the same interaction mechanism is present in these flows

Carlo Sigonios De dialogo liber

Since Antiquity dialogue was one of the paradigmatic genres in theoretical discourse and its cognitive function was of fundamental significance in Renaissance theory of dialogue. This importance was considered for the first time by Carlo Sigonio in his De dialogo liber. Referring to Aristotle’s Topica, Sigonio defined dialogue as a written imitation of a dialectical disputation. He considered the arguments in a dialogue as well as in a dialectical disputation not to be based on scientific propositions, which are necessarily true, but to be based on commonly accepted premises. In consequence thereof, dialogue is not intended to generate indubitable knowledge but to foster „opinions“ (opinio), „beliefs“ and „convictions“ (fides), whose epistemological value is a matter of discussion. The intention of this paper is to present the arguments developed by Sigonio in order to explain that opinio and fides are not only legitimate epistemic goals, but sometimes the only reasonable ones. A further topic is the functions of dialectic and rhetoric within the framework of this cognitive concept

Descartes, pionir prosvjetiteljstva

The article addresses the fundamental elements of Descartes’ embeddedness in the mediaeval and ancient tradition. The more elaborate explication of the common elements, shared by Descartes and his predecessors, enables us to reveal more clearly the rupture point in Descartes’ thought, and shows clearly in the direction of his undisputed legacy for the later times, including French Materialism. Special attention is paid to M. Heidegger’s claim, based on his specific understanding of the history of philosophy, that Descartes represents the paradigmatic shift in the self-understanding of man, which crucially marks the latter development of philosophy, both idealistic and materialistic. Yet another author worthy of explicating in this context is M. A. Gillespie, who clearly adopts Heidegger’s view and further corroborates Descartes’ ontological shift to be read from his markedly different theology.Članak se bavi osnovnim elementima Descartesove uklopljenosti u srednjovjekovnu i antičku tradiciju. Opširnije objašnjenje zajedničkih elemenata koje je Descartes dijelio sa svojim prethodnicima omogućuje nam da preciznije odredimo točku raskida u Descartesovoj misli te jasno ukazuje na njegovo neosporno naslijeđe za kasnija razdoblja, uključujući i francuski materijalizam. Posebna pažnja posvećena je tvrdnji M. Heideggera, koja se temelji na njegovom specifičnom shvaćanju povijesti filozofije, da Descartes predstavlja paradigmatski pomak u samoshvaćanju čovjeka, koja je značajno obilježila kasniji razvoj filozofije, kako one idealističke tako i materijalističke. Još jedan autor kojega vrijedi spomenuti u ovom kontekstu je M. A. Gillespie, koji jasno prihvaća Heideggerov stav te nadalje potvrđuje kako bi se Descartesov ontološki pomak trebao sagledati sa stajališta njegove izrazito drukčije teologije

Modernidad, búsqueda de sentido y resistencias: Más allá de la hermenéutica del poder

Reseñas de - Karatzogianni, Athina y Robinson, Andrew. Power, Resistance and Conflict in the Contemporary World: Social movements, networks and hierarchies. Nueva York: Routledge, 2010, 324 páginas - Laïdi, Zaki. Un monde privé de sens. Paris : Fayard, 1994, 333 páginas - Shilliam, Robbie (ed.). International Relations and Non-Western Thought: Imperialism, colonialism and investigations of global modernity. Nueva York: Routledge, 2011, 272 página

Claves para la búsqueda y selección de trabajadores con discapacidad

Ponencias de las Terceras Jornadas sobre Empleo y Discapacidad celebradas el 29 de abril de 2009 en la Universidad Carlos III de MadridNo publicad

Turismo gastronómico : dinamización del territorio y desarrollo local de la provincia de Castellón.

La gastronomía asociada al turismo puede ser valorada como uno de los productos inseparables que conforman el producto integral turístico, el que le aporta quizás mayor valor añadido, o valorada como parte del patrimonio cultural de una ciudad, región o país. En una u otra línea, su demanda está creciendo aceleradamente dando lugar a un nuevo segmento turístico.2 Algo más del 10% de los turistas que visitaron España en 2009, unos 5,5 millones, mencionaron la gastronomía como principal motivo para visitar el país, según datos facilitados por Turespaña en el I Congreso Europeo de Turismo y Gastronomía, celebrado en Madrid. 3 . Y otros productos más valorados y con distintivos de calidad como Denominación de Origen (DO), Identificación Geográfica Protegida (IGP) y Especialidad Tradicional Garantizada (ETG), por ello realizaremos una comparación del destino turístico gastronómico del País Vasco, y el desarrollo de su marca Eusko Label, en los productos agroalimentarios de calidad

A Comparison of the Effects of Two Therapeutic Exercises on the Muscle Action Potential of the Vastus Medialis

Electromyography was utilized to compare the effects of two therapeutic exercises at two work loads in knee extension on the muscle action potential in the vastus medialis. One exercise was extension to 180 degrees with a four second isometric hold and flexion to 90 degrees. The other exercise was extension to 180 degrees, 15 degrees flexion, 15 degrees extension and flexion to 90 degrees. Each exercise lasted for 10 seconds. The subjects in the study were 11 varsity female athletes from the fall and winter interscholastic athletic program at Eastern Illinois University. The subjects met for the first time to determine their work loads and to practice each exercise. The work loads were determined to be one-half and three-fourths of the maximum weight lifted to full knee extension. At a second meeting, data was collected from each subject for each exercise performed during two trials at two different work loads. The research design consisted of a single-group with two variables. The amplitude of the spikes was measured and the frequencies of the spikes on each interference pattern were counted. A quantitative figure was obtained by multiplying mean amplitude by frequency for each trial. This score was utilized with a multiple analysis of variance program by the Eastern Illinois University Data Processing Center. A null hypothesis was tested at the .05 level of significance. The null hypothesis stated: Exercising the quadriceps femoris through a full range of motion plus repetition of the last 15 degrees does not increase the muscle action potential of the vastus medialis when compared to a full extension and flexion exercise with the same time duration. Major findings of the study concluded that there was no difference in the muscle action potential in the two exercises. There was a significant difference in the muscle action potential due to the increase in weights between one-half maximum weight and three-fourths maximum weight