La circulation de monnaie carolingienne dans la péninsule ibérique. À propos d’un denier de l’atelier de Roda

Les trouvailles de monnaies carolingiennes dans la péninsule ibérique sont peu abondantes, surtout pour les pièces frappées dans la Marche d’Espagne. Cet article présente l’état des connaissances sur cette question à propos d’un fragment de denier carolingien trouvé dans les fouilles archéologiques du site d’El Tolmo de Minateda (Hellín, Albacete, Espagne). Il s’agit d’une émission de Charlemagne de l’atelier de Roda, situé dans la Marche d’Espagne, atelier dont on ne connaissait jusqu’à maintenant qu’une seule pièce pour ce souverain franc. Le contexte stratigraphique de ce denier apporte une donnée intéressante sur le moment de son utilisation et en fait un des plus anciens exemples de la circulation de monnaies carolingiennes dans la Péninsule ibérique.

Producción en masa, economía monetaria y vitalidad comercial del Mediterráneo

Se argumenta que la arqueología y la historia monetaria reúnen entre sí el potencial para proyectar una imagen de la economía romana muy diferente a la que sugieren los estereotipos minimalistas. Se discuten las implicancias de esta argumentación para el período tardoantiguo en particular, rechazando el catastrofismo con el que Rostovtzeff concluía su célebre historia del temprano imperio. En el imperio tardío la fortaleza de los intereses privados se mantuvo tan firme como siempre, en una economía caracterizada por la integración de los negocios públicos y privados antes que por un supuesto conflicto o antagonismo entre ambos. El imperio de Oriente conservó estas tendencias en forma pura, con niveles sostenidos de comercio y circulación monetaria hasta las décadas centrales del siglo VII. En este trabajo se argumenta que pensar en términos de ciclos económicos sería para los historiadores más razonable que la patología convencional de la "declinación", "decadencia", etc. Este patrón es notablemente evidente en la historia económica bizantina, marcada por abruptas fluctuaciones entre los siglos V y XII.

Producción en masa, economía monetaria y vitalidad comercial del Mediterráneo

Se argumenta que la arqueología y la historia monetaria reúnen entre sí el potencial para proyectar una imagen de la economía romana muy diferente a la que sugieren los estereotipos minimalistas. Se discuten las implicancias de esta argumentación para el período tardoantiguo en particular, rechazando el catastrofismo con el que Rostovtzeff concluía su célebre historia del temprano imperio. En el imperio tardío la fortaleza de los intereses privados se mantuvo tan firme como siempre, en una economía caracterizada por la integración de los negocios públicos y privados antes que por un supuesto conflicto o antagonismo entre ambos. El imperio de Oriente conservó estas tendencias en forma pura, con niveles sostenidos de comercio y circulación monetaria hasta las décadas centrales del siglo VII. En este trabajo se argumenta que pensar en términos de ciclos económicos sería para los historiadores más razonable que la patología convencional de la "declinación", "decadencia", etc. Este patrón es notablemente evidente en la historia económica bizantina, marcada por abruptas fluctuaciones entre los siglos V y XII.

Producción en masa, economía monetaria y vitalidad comercial del Mediterráneo

Se argumenta que la arqueología y la historia monetaria reúnen entre sí el potencial para proyectar una imagen de la economía romana muy diferente a la que sugieren los estereotipos minimalistas. Se discuten las implicancias de esta argumentación para el período tardoantiguo en particular, rechazando el catastrofismo con el que Rostovtzeff concluía su célebre historia del temprano imperio. En el imperio tardío la fortaleza de los intereses privados se mantuvo tan firme como siempre, en una economía caracterizada por la integración de los negocios públicos y privados antes que por un supuesto conflicto o antagonismo entre ambos. El imperio de Oriente conservó estas tendencias en forma pura, con niveles sostenidos de comercio y circulación monetaria hasta las décadas centrales del siglo VII. En este trabajo se argumenta que pensar en términos de ciclos económicos sería para los historiadores más razonable que la patología convencional de la "declinación", "decadencia", etc. Este patrón es notablemente evidente en la historia económica bizantina, marcada por abruptas fluctuaciones entre los siglos V y XII.

Liquidity, business cycles and monetary policy: A simulation

A Masters Thesis, presented as part of the requirements for the award of a Research Masters Degree in Economics from NOVA – School of Business and Economics

The fragility of two monetary regimes: The European Monetary System and the Eurozone. National Bank of Belgium Working Paper No. 243, October 2013

The purpose of these working papers is to promote the circulation of research results (Research Series) and analytical studies (Documents Series) made within the National Bank of Belgium or presented by external economists in seminars, conferences and conventions organised by the Bank. The aim is therefore to provide a platform for discussion. The opinions expressed are strictly those of the authors and do not necessarily reflect the views of the National Bank of Belgium.

A naturally shaped silicone ventricle evaluated in a mock circulation loop : a preliminary study

Mock circulation loops are used to evaluate the performance of cardiac assist devices prior to animal and clinical testing. A compressible, translucent silicone ventricle chamber that mimics the exact size, shape and motion of a failing heart is desired to assist in flow visualization studies around inflow cannulae during VAD support. The aim of this study was therefore to design and construct a naturally shaped flexible left ventricle and evaluate its performance in a mock circulation loop. The ventricle shape was constructed by the use of CT images taken from a patient experiencing cardiomyopathic heart failure and used to create a 3D image and subsequent mould to produce a silicone ventricle. Different cardiac conditions were successfully simulated to validate the ventricle performance, including rest, left heart failure and VAD support.

Simulation and development of a mock circulation loop with variable compliance

Heart disease is attributed as the highest cause of death in the world. Although this could be alleviated by heart transplantation, there is a chronic shortage of donor hearts and so mechanical solutions are being considered. Currently, many Ventricular Assist Devices (VADs) are being developed worldwide in an effort to increase life expectancy and quality of life for end stage heart failure patients. Current pre-clinical testing methods for VADs involve laboratory testing using Mock Circulation Loops (MCLs), and in vivo testing in animal models. The research and development of highly accurate MCLs is vital to the continuous improvement of VAD performance. The first objective of this study was to develop and validate a mathematical model of a MCL. This model could then be used in the design and construction of a variable compliance chamber to improve the performance of an existing MCL as well as form the basis for a new miniaturised MCL. An extensive review of literature was carried out on MCLs and mathematical modelling of their function. A mathematical model of a MCL was then created in the MATLAB/SIMULINK environment. This model included variable features such as resistance, fluid inertia and volumes (resulting from the pipe lengths and diameters); compliance of Windkessel chambers, atria and ventricles; density of both fluid and compressed air applied to the system; gravitational effects on vertical columns of fluid; and accurately modelled actuators controlling the ventricle contraction. This model was then validated using the physical properties and pressure and flow traces produced from a previously developed MCL. A variable compliance chamber was designed to reproduce parameters determined by the mathematical model. The function of the variability was achieved by controlling the transmural pressure across a diaphragm to alter the compliance of the system. An initial prototype was tested in a previously developed MCL, and a variable level of arterial compliance was successfully produced; however, the complete range of compliance values required for accurate physiological representation was not able to be produced with this initial design. The mathematical model was then used to design a smaller physical mock circulation loop, with the tubing sizes adjusted to produce accurate pressure and flow traces whilst having an appropriate frequency response characteristic. The development of the mathematical model greatly assisted the general design of an in vitro cardiovascular device test rig, while the variable compliance chamber allowed simple and real-time manipulation of MCL compliance to allow accurate transition between a variety of physiological conditions. The newly developed MCL produced an accurate design of a mechanical representation of the human circulatory system for in vitro cardiovascular device testing and education purposes. The continued improvement of VAD test rigs is essential if VAD design is to improve, and hence improve quality of life and life expectancy for heart failure patients.

A compact mock circulation loop for the in vitro testing of cardiovascular devices

In vitro cardiovascular device performance evaluation in a mock circulation loop (MCL) is a necessary step prior to in vivo testing.A MCL that accurately represents the physiology of the cardiovascular system accelerates the assessment of the device’s ability to treat pathological conditions. To serve this purpose, a compact MCL measuring 600 ¥ 600 ¥ 600 mm (L ¥ W¥ H) was constructed in conjunction with a computer mathematical simulation.This approach allowed the effective selection of physical loop characteristics, such as pneumatic drive parameters, to create pressure and flow, and pipe dimensions to replicate the resistance, compliance, and fluid inertia of the native cardiovascular system. The resulting five-element MCL reproduced the physiological hemodynamics of a healthy and failing heart by altering ventricle contractility, vascular resistance/compliance, heart rate, and vascular volume. The effects of interpatient anatomical variability, such as septal defects and valvular disease, were also assessed. Cardiovascular hemodynamic pressures (arterial, venous, atrial, ventricular), flows (systemic, bronchial, pulmonary), and volumes (ventricular, stroke) were analyzed in real time. The objective of this study is to describe the developmental stages of the compact MCL and demonstrate its value as a research tool for the accelerated development of cardiovascular devices.

Modeling circulation of train-set with multiple routing

Planning on utilization of train-set is one of the key tasks of transport organization for passenger dedicated railway in China. It also has strong relationships with timetable scheduling and operation plans at a station. To execute such a task in a railway hub pooling multiple railway lines, the characteristics of multiple routing for train-set is discussed in term of semicircle of train-sets' turnover. In programming the described problem, the minimum dwell time is selected as the objectives with special derive constraints of the train-set's dispatch, the connecting conditions, the principle of uniqueness for train-sets, and the first plus for connection in the same direction based on time tolerance σ. A compact connection algorithm based on time tolerance is then designed. The feasibility of the model and the algorithm is proved by the case study. The result indicates that the circulation model and algorithm about multiple routing can deal with the connections between the train-sets of multiple directions, and reduce the train's pulling in or leaving impact on the station's throat.

Replication of the Frank-Starling response in a Mock Circulation loop

Mock circulation loops (MCLs) are used to evaluate cardiovascular devices prior to in-vivo trials; however they lack the vital autoregulatory responses that occur in humans. This study aimed to develop and implement a left and right ventricular Frank-Starling response in a MCL. A proportional controller based on ventricular end diastolic volume was used to control the driving pressure of the MCL’s pneumatically operated ventricles. Ventricular pressure-volume loops and end systolic pressure-volume relationships were produced for a variety of healthy and pathological conditions and compared with human data to validate the simulated Frank-Starling response. The non-linear Frank-Starling response produced in this study successfully altered left and right ventricular contractility with changing preload and was validated with previously reported data. This improvement to an already detailed MCL has resulted in a test rig capable of further refining cardiovascular devices and reducing the number of in-vivo trials.