<i>In Situ</i> Sampling of Relative Dust Devil Particle Loads and Their Vertical Grain Size Distributions

During a field campaign in the Sahara Desert in southern Morocco, spring 2012, we sampled the vertical grain size distribution of two active dust devils that exhibited different dimensions and intensities. With these in situ samples of grains in the vortices, it was possible to derive detailed vertical grain size distributions and measurements of the lifted relative particle load. Measurements of the two dust devils show that the majority of all lifted particles were only lifted within the first meter (~46.5% and ~61% of all particles; ~76.5 wt % and ~89 wt % of the relative particle load). Furthermore, ~69% and ~82% of all lifted sand grains occurred in the first meter of the dust devils, indicating the occurrence of ‘‘sand skirts.’’ Both sampled dust devils were relatively small (~15m and ~4–5m in diameter) compared to dust devils in surrounding regions; nevertheless, measurements show that ~58.5% to 73.5% of all lifted particles were small enough to go into suspension (<31 mm, depending on the used grain size classification). This relatively high amount represents only ~0.05 to 0.15 wt % of the lifted particle load. Larger dust devils probably entrain larger amounts of fine-grained material into the atmosphere, which can have an influence on the climate. Furthermore, our results indicate that the composition of the surface, on which the dust devils evolved, also had an influence on the particle load composition of the dust devil vortices. The internal particle load structure of both sampled dust devils was comparable related to their vertical grain size distribution and relative particle load, although both dust devils differed in their dimensions and intensities. A general trend of decreasing grain sizes with height was also detected

Texturing Carbon-carbon Composite Radiator Surfaces Utilizing Atomic Oxygen

Future space nuclear power systems will require radiator technology to dissipate excess heat created by a nuclear reactor. Large radiator fins with circulating coolant are in development for this purpose and an investigation of how to make them most efficient is underway. Maximizing the surface area while minimizing the mass of such radiator fins is critical for obtaining the highest efficiency in dissipating heat. Processes to develop surface roughness are under investigation to maximize the effective surface area of a radiator fin. Surface roughness is created through several methods including oxidation and texturing. The effects of atomic oxygen impingement on carbon-carbon surfaces are currently being investigated for texturing a radiator surface. Early studies of atomic oxygen impingement in low Earth orbit indicate significant texturing due to ram atomic oxygen. The surface morphology of the affected surfaces shows many microscopic cones and valleys which have been experimentally shown to increase radiation emittance. Further study of this morphology proceeded in the Long Duration Exposure Facility (LDEF). Atomic oxygen experiments on the LDEF successfully duplicated the results obtained from materials in spaceflight by subjecting samples to 4.5 eV atomic oxygen from a fixed ram angle. These experiments replicated the conical valley morphology that was seen on samples subjected to low Earth orbit

Some Reflections on the Role of Legal History in Legal Education

Despite its recent increase in popularity, the subject of legal history is generally viewed as having relatively little importance in the law school curriculum. While there may at one time have been some justification for this view, the changes in legal history-both as a scholarly discipline and as a law school courseover the past several decades, and the shift away from an exclusive focus on medieval English law, have made legal history a subject with much potential for legal education. A course in legal history can enhance students\u27 understanding of the legal system and the long-term forces at work within it, can reveal the historical contingency of the present law, and can illustrate some of the ways law is affected by non-legal influences. Given these possible benefits, legal history-especially American legal history-deserves a more prominent place in legal education

Of collapses and continuities. A conceptual review on the study of societies in transition

El proceso de estudio de los fenómenos de orden social o natural requiere de categorías analíticas específicas como herramientas destinadas a describir la realidad. Una de las categorías comúnmente utilizadas en la bibliografía es la de colapso. Este artículo persigue dos objetivos fundamentales que convergen en la intención de matizar la definición de este término: (1) se realiza una revisión de su uso a través de la bibliografía que trata casos concretos de sociedades pasadas cuyo destino ha sido directamente relacionado con este fenómeno y (2) se presenta el caso de estudio del colapso de la sociedad argárica, sita en el sudeste peninsular. Finalmente se realiza un ejercicio de correspondencia entre los aspectos destacados en el caso de estudio y los rasgos postulados en la bibliografía acerca del concepto de colapso.El procés de l'estudi dels fenòmens de l'ordre social o natural requereix de categories analítiques especifiques, com eines destinades a descriure la realitat. Una de les categories comunament utilitzades en la bibliografia és el del col·lapse. Aquest article, persegueix dos objectius: (1) es realitza una revisió del seu ús a través de la bibliografia que tracta casos concrets de societats passades en el que el seu destí ha estat directament relacionat amb aquest fenomen i (2) es presenta el cas d'estudi del col·lapse de la societat argàrica, situat en el sud-est peninsular. Finalment, es realitza un exercici de correspondència entre els aspectes destacats en el cas d'estudi i el trets postulats en la bibliografia sobre el concepte de col·lapse.The process of studying social or natural phenomena requires specific analytical categories that serve as tools to describe reality. One of the commonly used categories among the literature is collapse. This article has two main objectives that converge on the intention to refine the definition of the term: (1) a review of its use through the literature dealing with specific instances of past societies whose fate has been directly related to this phenomenon and (2), presents the case study of the collapse of the argaric society, located in southeastern Spain. We carried out an exercise of correspondence between the aspects highlighted in the case study and the features postulated in the literature about the concept of collapse.Peer Reviewe

Analoge vs. digitale Uhrzeitformate

Die Zeit ist eine fundamentale physikalische Größe, die auch für die Schulphysik einen unbestritten hohen Stellenwert besitzt. Bereits in der Primarstufe wird ein Grundverständnis des Zeitbegriffs vermittelt, insbesondere in den Fächern Sachunterricht und Mathematik wird auf verschiedene Aspekte des Phänomens „Zeit“ eingegangen: Kennenlernen von Zeitstrukturen, Einführung des Kalenders, mit Zeitintervallen und -punkten rechnen, aber vor allem die Uhr zu lesen sind grundlegende Kompetenzen, die die Schüler*innen erlernen sollen.In Bezug auf die Fähigkeit des Uhr-Ablesens stellt sich die Frage nach der Aktualität des analogen Uhrzeitformats und ob dieses weiterhin gelehrt werden solle. Im Rahmen dieses Beitrags werden analoge und digitale Repräsentationsformen der Uhrzeit u.a. auf deren didaktische Potentiale und Grenzen hin kritisch beleuchtet, um der teilweise sehr subjektiv und emotional geführten Debatte rund um die Abschaffung analoger Formate mehr Substanz zu verleihen. Als hilfreich können sich dabei beispielsweise Befunde aus Studien der Kognitionspsychologie erweisen, anhand derer sich didaktische Empfehlungen ableiten lassen

The Strength of Diversity : Macrolithic Artefacts and Productive Forces During the Chalcolithic of Southern Iberia

Altres ajuts: acords transformatius de la UABPublished Online 10 October 2023Any approach to the economic organization of a society depends on our knowledge of the productive forces and relations of production involved. In archaeology, this line of research requires an analysis of the technical quality and quantity of the means of production, as well as their spatial distribution and contextualisation. Macrolithic artefacts constituted the means of production in many of the productive processes of past communities, from the Neolithic period to the end of prehistory. This article seeks to utilize macrolithic data to gain a more comprehensive understanding of the economic organisation of the Chalcolithic communities in the southern half of the Iberian Peninsula between c. 3100 and 2200 cal BC. These communities produced one of the most outstanding, but at the same time puzzling archaeological records known in later prehistory. The main aim of this exploratory approach, the first of its kind, is to determine if the different forms of occupation of the Chalcolithic, namely monumental, ditched enclosures, fortified and unfortified hill-top settlements, and simple, open settlements were distinguished by specific modes of production. This issue is crucial to the on-going debate about the meaning and relevance of the notion of social complexity in the context of Chalcolithic societies and their political organisation. Our study describes the productive forces of the Chalcolithic settlements as highly variable, both in the type of productive tasks performed and in their intensity, and such variability is not explained by aspects like geographic location, form of occupation, or monumentality. The observed wealth and productive diversity, without signs of marked social hierarchies, emerge as a characteristic feature of what can be defined as cooperative affluent societies

Analoge vs. digitale Uhrzeitformate

Die Zeit ist eine fundamentale physikalische Größe, die auch für die Schulphysik einen unbestritten hohen Stellenwert besitzt. Bereits in der Primarstufe wird ein Grundverständnis des Zeitbegriffs vermittelt, insbesondere in den Fächern Sachunterricht und Mathematik wird auf verschiedene Aspekte des Phänomens „Zeit“ eingegangen: Kennenlernen von Zeitstrukturen, Einführung des Kalenders, mit Zeitintervallen und -punkten rechnen, aber vor allem die Uhr zu lesen sind grundlegende Kompetenzen, die die Schüler*innen erlernen sollen.In Bezug auf die Fähigkeit des Uhr-Ablesens stellt sich die Frage nach der Aktualität des analogen Uhrzeitformats und ob dieses weiterhin gelehrt werden solle. Im Rahmen dieses Beitrags werden analoge und digitale Repräsentationsformen der Uhrzeit u.a. auf deren didaktische Potentiale und Grenzen hin kritisch beleuchtet, um der teilweise sehr subjektiv und emotional geführten Debatte rund um die Abschaffung analoger Formate mehr Substanz zu verleihen. Als hilfreich können sich dabei beispielsweise Befunde aus Studien der Kognitionspsychologie erweisen, anhand derer sich didaktische Empfehlungen ableiten lassen

Relaciones pasadas: explorando sus potencialidades. Conversaciones sobre el impacto de nuestras relaciones pasadas en el yo relacional

El concepte del jo relacional proposa que les persones es contitueixen per les seves relacions. En la present indagació s’explora l’efecte de les relacions passades en el jo relacional. Per a això es mantenen converses amb parelles materno-filials impulsades per mètodes basats en l´art. L’anàlisi de les dades es presenta des de diferents perspectives, les quals poden ser identificades com a éssers relacionals de l’autora principal d’aquest treball. A partir d’això, la tesi agafa forma i estructura pròpies, presentant vuit capítols que responen a invitacions relacionals rebudes al llarg del procés d’investigació.El concepto del yo relacional propone que las personas se constituyen por sus relaciones. En la presente indagación se explora el efecto de las relaciones pasadas en el yo relacional. Se mantienen para ello conversaciones con parejas materno-filiales impulsadas por métodos basados en el arte. El análisis de los datos es presentado desde distintas perspectivas, las cuales pueden ser identificadas como seres relacionales de la autora principal del trabajo. A partir de ello, la tesis toma su forma y estructura propias, presentando ocho capítulos que responden a invitaciones relacionales recibidas a lo largo del proceso investigativo.The concept of relational being proposes that people are constituted by their relationships. In the present inquiry the effect of past relationships on the relational being is explored. With this purpose art-based methods are used in conversations with mothers and their daughters or sons. Data analysis is presented from many different perspectives, which can be identified as relational selfs of the principal author of this work. This fact gives the form and structure the dissertation takes: eight chapters that respond to relational invitations obtained throughout the investigative process