“Living in the world of the White”. The tensions between class and race in the experiences of persons racialized as Black in Bogotá's middle class

En este artículo se indaga por las relaciones entre clase y raza, desde diversos puntos de vista. En primer lugar, se hace una exploración desde el punto de vista histórico y teórico de las relaciones entre la formación de clases sociales y los procesos de racialización en el contexto latinoamericano y colombiano y, en segundo lugar, se analizan diversas experiencias de personas racializadas como negras en los sectores medios de la ciudad de Bogotá D.C. – Colombia, particularmente sobre la negociación que hacen, en la vida cotidiana, de su pertenencia/asignación racial y su pertenencia/asignación de clase, situación que se expresa como experiencia contradictoria de estatus, como situaciones de discriminación racial, o como actos cotidianos que retan o refuerzan el orden racial y de claseThis article analyzes the relations between class and race among persons racialized as Black in Bogotá's middle class, from several points of view. First, I draw on historical, theoretical works about the social class formation and the processes of racialization in the Colombian and Latin American context and, secondly, I analyze different experiences of persons racialized as Black in Bogotá's middle class (Colombia). I draw attention to the everyday tensions between their racial position/assignments and their class position/assignments to argue that these are lived as contradictory experiences of status – either as discriminatory situations or like everyday actions that alternately challenge or reinforce the racial and class order

Género y generación en las experiencias de ascenso social de personas negras en Bogotá

Este artículo presenta algunos de los resultados de la investigación “Raza”, género y ascenso social: la experiencia de las clases medias negras en Colombia (un estudio de caso en Bogotá y Cali). En él se analiza el ascenso social de personas negras, particularmente en la ciudad de Bogotá, haciendo énfasis en los efectos causados por las diferencias generacionales y de género. En primer lugar, se abordan aspectos teóricos y metodológicos generales sobre el estudio de las clases medias negras en Colombia. En segundo lugar, se expone el conjunto de biografías de las personas de raza negra consideradas en el marco del estudio, conjunto analizado a partir de los esquemas de sus trayectorias educativas. Luego, se presenta en detalle las experiencias de su ascenso social con base en el análisis de fragmentos de las narraciones de su historia de vida y familiar. Al final del escrito, se hacen algunas observaciones sobre las relaciones entre identidad negra y ascenso social.abstract. This article presents some of the results of the research project “Race”, Gender, and Social Ascent: The Experience of the Black Middle Classes in Colombia (A Case Study in Bogotá and Cali). It analyzes the social ascent of black people, particularly in Bogotá, emphasizing the effects of generational and gender differences on this process. Firstly, the article addresses the theoretical and methodological aspects of the study of black middle classes in Colombia. Secondly, it presents the biographies of the black people included in the study, a group that was analyzed on the basis of their educational experience. Thirdly, it provides a detailed presentation of social ascent experiences on the basis of the participants’ personal and family histories. Finally, it examines the relations between black identity and social ascent

Physiological responses and productivity of the seaweed Ulva ohnoi (Chlorophyta) under changing cultivation conditions in pilot large land-based ponds

Land based intensive cultivation systems have been proposed as an ideal option for the commercial production of high value products from seaweeds. However, many cultures on Ulva and other seaweeds are based on relatively small-scale facilities. The high variability of culture conditions can strongly affect the physiological performance of seaweeds, but few studies examine their phenotypic plasticity by integrating critical biological descriptors, e.g. photobiology, oxidative stress, nutrient acquisition. The purpose of this study was to determine the physiological plasticity and growth of Ulva ohnoi during its cultivation in land-based 40 m3 ponds. Through an entire culti-vation cycle (four-weeks), photosynthesis, respiration, pigments, antioxidant capacity and nutrient content were measured. Light, temperature, pH, and dissolved inorganic nitrogen (DIN) were simultaneously monitored in seawater. Additionally, the N-uptake kinetics of U. ohnoi were examined in the laboratory in order to explain the efficiency of the seaweed biomass for DIN-incorporation in the ponds after fertilization. Generally, the gradual increase in seaweed density throughout the cultivation period was directly associated to a drop in light avail-ability and dissolved inorganic carbon (i.e. higher pH) within the ponds. These changes in cultivation conditions were related to a reduction of photosynthetic capacities, nutrient content and growth of U. ohnoi. N-uptake kinetics of U. ohnoi and the behavior of DIN within the ponds after fertilization, indicated that U. ohnoi was able to incorporate ammonium more efficiently than nitrate, and the presence of the former likely inhibits nitrate acquisition. The understanding of the capacity of U. ohnoi to acclimate to the extreme changing culture condi-tions, could be applied to improve its productivity and chemical composition.En prens

Saberes, Culturas y Derechos Sexuales en Colombia

Este libro reúne artículos de gran pertinencia académica en el tema, ponencias y discusiones que realizaron distintos grupos de trabajo en el marco del seminario Hacia una Agenda sobre Sexualidad y Derechos Humanos en Colombia, realizado en Bogotá durante los días 18, 19 y 20 de marzo de 2004. Este texto acerca a un público más amplio el debate que vienen desarrollando en Colombia investigadores, militantes, responsables y ejecutores de políticas públicas en materia de sexualidad y de derechos sexuales y reproductivos. La divulgación de los trabajos presentados en este libro permitirá a los lectores identificar las líneas de debate que orientan la investigación, las políticas públicas, los programas de intervención social y el derecho en este ámbito. El texto presenta hallazgos en torno a estos temas, con el objetivo de construir un referente común sobre la sexualidad como una construcción sociocultural e histórica objeto de una regulación pública. Igualmente, pretende inscribir la sexualidad en el ámbito de la construcción de ciudadanía y de la reivindicación de los derechos humanos

Gamma-induced background in the KATRIN main spectrometer

International audienceThe KArlsruhe TRItium Neutrino (KATRIN) experiment aims to make a model-independent determination of the effective electron antineutrino mass with a sensitivity of 0.2 eV/c 2 . It investigates the kinematics of β -particles from tritium β -decay close to the endpoint of the energy spectrum. Because the KATRIN main spectrometer (MS) is located above ground, muon-induced backgrounds are of particular concern. Coincidence measurements with the MS and a scintillator-based muon detector system confirmed the model of secondary electron production by cosmic-ray muons inside the MS. Correlation measurements with the same setup showed that about 12% of secondary electrons emitted from the inner surface are induced by cosmic-ray muons, with approximately one secondary electron produced for every 17 muon crossings. However, the magnetic and electrostatic shielding of the MS is able to efficiently suppress these electrons, and we find that muons are responsible for less than 17% (90% confidence level) of the overall MS background

Analysis methods for the first KATRIN neutrino-mass measurement

We report on the dataset, data handling, and detailed analysis techniques of the first neutrino-mass measurement by the Karlsruhe Tritium Neutrino (KATRIN) experiment, which probes the absolute neutrino-mass scale via the β-decay kinematics of molecular tritium. The source is highly pure, cryogenic T2 gas. The β electrons are guided along magnetic field lines toward a high-resolution, integrating spectrometer for energy analysis. A silicon detector counts β electrons above the energy threshold of the spectrometer, so that a scan of the thresholds produces a precise measurement of the high-energy spectral tail. After detailed theoretical studies, simulations, and commissioning measurements, extending from the molecular final-state distribution to inelastic scattering in the source to subtleties of the electromagnetic fields, our independent, blind analyses allow us to set an upper limit of 1.1 eV on the neutrino-mass scale at a 90% confidence level. This first result, based on a few weeks of running at a reduced source intensity and dominated by statistical uncertainty, improves on prior limits by nearly a factor of two. This result establishes an analysis framework for future KATRIN measurements, and provides important input to both particle theory and cosmology

Reduction of stored-particle background by a magnetic pulse method at the KATRIN experiment

The KATRIN experiment aims to determine the effective electron neutrino mass with a sensitivity of 0.2 eV/c2 (%90 CL) by precision measurement of the shape of the tritium β-spectrum in the endpoint region. The energy analysis of the decay electrons is achieved by a MAC-E filter spectrometer. A common background source in this setup is the decay of short-lived isotopes, such as 219Rn and 220Rn, in the spectrometer volume. Active and passive countermeasures have been implemented and tested at the KATRIN main spectrometer. One of these is the magnetic pulse method, which employs the existing air coil system to reduce the magnetic guiding field in the spectrometer on a short timescale in order to remove low- and high-energy stored electrons. Here we describe the working principle of this method and present results from commissioning measurements at the main spectrometer. Simulations with the particle-tracking software Kassiopeia were carried out to gain a detailed understanding of the electron storage conditions and removal processes

Precision measurement of the electron energy-loss function in tritium and deuterium gas for the KATRIN experiment

The KATRIN experiment is designed for a direct and model-independent determination of the effective electron anti-neutrino mass via a high-precision measurement of the tritium $\beta$-decay endpoint region with a sensitivity on $m_\nu$ of 0.2$\,$eV/c$^2$ (90% CL). For this purpose, the $\beta$-electrons from a high-luminosity windowless gaseous tritium source traversing an electrostatic retarding spectrometer are counted to obtain an integral spectrum around the endpoint energy of 18.6$\,$keV. A dominant systematic effect of the response of the experimental setup is the energy loss of $\beta$-electrons from elastic and inelastic scattering off tritium molecules within the source. We determined the \linebreak energy-loss function in-situ with a pulsed angular-selective and monoenergetic photoelectron source at various tritium-source densities. The data was recorded in integral and differential modes; the latter was achieved by using a novel time-of-flight technique. We developed a semi-empirical parametrization for the energy-loss function for the scattering of 18.6-keV electrons from hydrogen isotopologs. This model was fit to measurement data with a 95% T$_2$ gas mixture at 30$\,$K, as used in the first KATRIN neutrino mass analyses, as well as a D$_2$ gas mixture of 96% purity used in KATRIN commissioning runs. The achieved precision on the energy-loss function has abated the corresponding uncertainty of $\sigma(m_\nu^2)<10^{-2}\,\mathrm{eV}^2$ [arXiv:2101.05253] in the KATRIN neutrino-mass measurement to a subdominant level.Comment: 12 figures, 18 pages; to be submitted to EPJ