Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Cinco reflexiones sobre las reformas políticas en América Latina

In general, Latina America is going through a process of exhaustion of its political parties due to a debilitation in the framework of constitutional law or because this framework has contributed to the political crises, citizenry disappointment, and weakening of democracies, among others. This situation emphasizes the fact that the need of a political reform goes beyond reformulating the constitutional architecture, the functioning of the political regime, the electoral and/or political systems provided that the Latin American democracy is a democracy in which the characteristics of the presidential system and the political party systems that have proliferated increase the probability of a political paralysis in the regionAmérica Latina en general se encuentra en un proceso de agotamiento de sus sistemas políticos, ya sea por una extenuación en el marco de derecho constitucional o porque este marco ha contribuido a las crisis políticas, descontento ciudadano, debilitamiento de la democracias, entre otros. Esta coyuntura evidencia que la necesidad de una reforma política va más allá de replantear la arquitectura constitucional, el funcionamiento del régimen político, el sistema electoral y/o los partidos políticos, ya que la democracia latinoamericana es una democracia en la que las características del sistema presidencial y de los sistemas de partidos que han proliferado, aumentan la probabilidad de una parálisis política en la regió

Paying for democracy in Latin America : political finance and state funding for parties in Costa Rica and Uruguay

EThOS - Electronic Theses Online ServiceGBUnited Kingdo