Los nudos del sistema

Pieza central del antiguo régimen; pacto, acuerdo o trato con algunos actores decisivos del sistema político susceptible de ser revisado; forma cultural de relaciones de poder o de intercambio; pirámide de organizaciones o estructura sectorial: ¿qué tan invisible sigue siendo, qué tan montada sigue estando la pirámide del corporativismo mexicano antes y después del 2 de julio de 2000? Este fenómeno constituye el eje central de las reflexiones del presente ensayo. En torno al mismo, se presenta información para reconstruir o conocer con más detalle los contenidos, alcances y perfiles de aquel proceso de ruptura del pacto corporativo forjado entre el PRI y los sectores que lo conformaban históricamente, como datos que podrían explicar la pérdida de la base electoral tradicionalmente leal a este partido; identificar el papel que han venido desempeñando en dicho proceso los actores políticos más diversos —PAN, PRD, organizaciones laborales independientes—, para identificar las formas que podría adoptar un “contrato corporativo” en un orden político democrático y un nuevo sistema de partidos, y formular algunas hipótesis sobre el curso que podría tomar la inevitable reforma del PRI, considerando los elementos anteriores y algunos puntos de comparación tomados de la transición española. Para ello se toman exclusivamente los ejemplos de mayor peso histórico y social, considerados como los más nítidos y representativos del corporativismo mexicano: el del sector obrero y el de las organizaciones campesinas

Guarantee Funds: A Success Factor in Microfinance?

Microfinance is described for grantmakers and non-profit organisations that are interested in making grants in the form of guarantee funds. A basic definition is given, advantages and disadvantages of this scheme are described. Documentation from a seminar on guarantee funds is also included

Salt crystallization dynamics in building rocks: a 4D study using laboratory X-ray micro-CT

We employ laboratory X-ray micro-computed tomography (μCT) during climate-controlled salt weathering experiments to acquire data on the kinetics of drying and salt precipitation and the distribution of crystals within the pore space of Mšené sandstone. For that purpose, a custom-designed setup was built at the UGCT’s scanners of the Ghent University Centre for X-ray Tomography (UGCT) that allows to acquire 4D scans while drying. Samples were initially capillary saturated with a saturated NaCl-solution and subsequently dried at 20% RH and at 50% RH, at room temperature. These RH-values are representative for winter and summer conditions for the salt NaCl, which is not temperature sensitive. Different salt precipitation dynamics result in different drying kinetics at the two RH’s. These crystallization and transport dynamics can be directly linked as revealed by the 4D X-ray μCT datasets

Energy-selective neutron imaging for materials science

Common neutron imaging techniques study the attenuation of a neutron beam penetrating a sample of interest. The recorded radiograph shows a contrast depending on traversed material and its thickness. Tomography allows separating both and obtaining 3D spatial information about the material distribution, solving problems in numerous fields ranging from virtually separating fossils from surrounding rock to water management in fuel cells. It is nowadays routinely performed at PSI¿s neutron imaging facilities. Energy-selective neutron imaging studies the wavelength-dependency of the cross-section by using a beam of reduced wavelength bandwidth instead of averaging out the cross-section over the incident beam spectrum. The range of observed contrasts/image information is than extended and can largely be understood in the context of the Bragg law. Different types of monochromator (mechanical neutron velocity selector, double crystal monochromator, filter materials) are characterized for use in neutron imaging. In polycrystalline samples, sharp Bragg edges are observed as coherent elastic scattering at the (hkl) plane can occur for all wavelengths up to 2dhkl, after which a sharp increase in transmission intensity is observed. Much like diffraction peaks, they contain information on e.g. crystal phase or projected strain. The absence of coherent elastic scattering past the last Bragg edge (Bragg cut-off) allows for quantification. In samples with few grains or even single crystals, all orientations w.r.t. the beam are no longer present and rather than Bragg edges, the cross section now exhibits distinct peaks, the ensemble of which holds information on the crystallite¿s phase, orientation and shape. A spatial variation in contrast appears across the sample, between those grains fulfilling the Bragg condition ¿ scattering and decreasing the transmitted beam intensity ¿ and those that do not. After initial qualitative assessments, recent advances on the quantitative grain orientation mapping are made based on time-of-flight measurements of high energy resolution recorded at the ISIS pulsed neutron source. But where do these scattered neutrons go to? A new set-up was developed to permit simultaneous transmission and diffractive neutron imaging. Capturing the neutrons diffracted by a grain also yields a projection of that grain, with the position on the detector indicative of the orientation. These projections can in turn be used for algebraic reconstruction, which yields a grain volume as well. After feasibility studies on an iron single crystal cube the recent push towards polycrystalline samples will is illustrated with a neutron diffraction contrast tomography (nDCT) of a coarse-grained aluminium strain sample

An energy and area efficient, all digital entropy source compatible with modern standards based on jitter pipelining

This paper proposes an energy and area efficient entropy source, suitable for true random number generation, accompanied with a stochastic model in a 28nm CMOS technology. The design uses a jitter pipelining architecture together with an increased timing resolution to achieve a maximal throughput of 298 Mbit/s and a best energy efficiency of 1.46 pJ/bit at a supply of 0.8V. The generated random bits pass the NIST SP 800-90B IID tests with a min entropy rate of 0.933 bit/bit, which is more than required by the AIS-31 standard. The all digital design allows for effortless transfer to other technology nodes, taking advantage of all benefits related to further technology scaling

Een toevalsvondst in het Sint-Angela-instituut in de Kruineikenstraat 5b te Tildonk-Haacht (Vlaams-Brabant). Eindverslag van een toevalsvondst.

In het Sint-Angela-instituut te Tildonk, deelgemeente van Haacht, werden tijdens restauratiewerken van de Art Nouveau zaal (het uitgraven van de ondergrond om een nieuwe geïsoleerde vloerplaat en nieuwe ventilatie kanalen aan te leggen) bakstenen funderingen aangetroffe

Structural Characterization of Iron Meteorites through Neutron Tomography

In this communication, we demonstrate the use of neutron tomography for the structural characterization of iron meteorites. These materials prevalently consist of metallic iron with variable nickel content. Their study and classification is traditionally based on chemical and structural analysis. The latter requires cutting, polishing and chemical etching of large slabs of the sample in order to determine the average width of the largest kamacite lamellae. Although this approach is useful to infer the genetical history of these meteorites, it is not applicable to small or precious samples. On the base of different attenuation coefficient of cold neutrons for nickel and iron, neutron tomography allows the reconstruction of the Ni-rich (taenite) and Ni-poor (kamacite) metallic phases. Therefore, the measure of the average width of the largest kamacite lamellae could be determined in a non-destructive way. Furthermore, the size, shape, and spatial correlation between kamacite and taenite crystals were obtained more efficiently and accurately than via metallographic investigation