École Polytechnique Fédérale de Lausanne

About: École Polytechnique Fédérale de Lausanne is a facility organization based out in Lausanne, Switzerland. It is known for research contribution in the topics: Population & Catalysis. The organization has 44041 authors who have published 98296 publications receiving 4372092 citations. The organization is also known as: EPFL & ETHL.

Motility: Mobility as capital

Abstract: Social and territorial structures form intricate relations that transcend a social stratification or spatial focus. Territorial features and geographic displacements are structuring principles for society, as societal features and social change effect the structure and use of territory. Based on our examination of the conceptual and theoretical links between spatial and social mobility, we propose a concept that represents a new form of inequality. Termed 'motility', this construct describes the potential and actual capacity of goods, information or people to be mobile both geographically and socially. Three major features of motility - access, competence and appropriation - are introduced. In this article, we focus on conceptual and theoretical contributions of motility. In addition, we suggest a number of possible empirical investigations. Motility presents us with an innovative perspective on societal changes without prematurely committing researchers to work within structuralist or postmodern perspectives. More generally, we propose to revisit the fluidification debate in the social sciences with a battery of questions that do not begin and end with whether or not society is in flux. Instead, we introduce a field of research that takes advantage of the insights from competing paradigms in order to reveal the social dynamics and consequences of displacements in geographic and social space.

Thermodynamically stabilized β-CsPbI3-based perovskite solar cells with efficiencies >18.

Abstract: Although β-CsPbI3 has a bandgap favorable for application in tandem solar cells, depositing and stabilizing β-CsPbI3 experimentally has remained a challenge. We obtained highly crystalline β-CsPbI3 films with an extended spectral response and enhanced phase stability. Synchrotron-based x-ray scattering revealed the presence of highly oriented β-CsPbI3 grains, and sensitive elemental analyses-including inductively coupled plasma mass spectrometry and time-of-flight secondary ion mass spectrometry-confirmed their all-inorganic composition. We further mitigated the effects of cracks and pinholes in the perovskite layer by surface treating with choline iodide, which increased the charge-carrier lifetime and improved the energy-level alignment between the β-CsPbI3 absorber layer and carrier-selective contacts. The perovskite solar cells made from the treated material have highly reproducible and stable efficiencies reaching 18.4% under 45 ± 5°C ambient conditions.

Embryonic stem cell potency fluctuates with endogenous retrovirus activity

Abstract: Embryonic stem (ES) cells are derived from blastocyst-stage embryos and are thought to be functionally equivalent to the inner cell mass, which lacks the ability to produce all extraembryonic tissues. Here we identify a rare transient cell population within mouse ES and induced pluripotent stem (iPS) cell cultures that expresses high levels of transcripts found in two-cell (2C) embryos in which the blastomeres are totipotent. We genetically tagged these 2C-like ES cells and show that they lack the inner cell mass pluripotency proteins Oct4 (also known as Pou5f1), Sox2 and Nanog, and have acquired the ability to contribute to both embryonic and extraembryonic tissues. We show that nearly all ES cells cycle in and out of this privileged state, which is partially controlled by histone-modifying enzymes. Transcriptome sequencing and bioinformatic analyses showed that many 2C transcripts are initiated from long terminal repeats derived from endogenous retroviruses, suggesting this foreign sequence has helped to drive cell-fate regulation in placental mammals.

Fibroblastic reticular cells in lymph nodes regulate the homeostasis of naive T cells.

Abstract: Interleukin 7 is essential for the survival of naive T lymphocytes. Despite its importance, its cellular source in the periphery remains poorly defined. Here we report a critical function for lymph node access in T cell homeostasis and identify T zone fibroblastic reticular cells in these organs as the main source of interleukin 7. In vitro, T zone fibroblastic reticular cells were able to prevent the death of naive T lymphocytes but not of B lymphocytes by secreting interleukin 7 and the CCR7 ligand CCL19. Using gene-targeted mice, we demonstrate a nonredundant function for CCL19 in T cell homeostasis. Our data suggest that lymph nodes and T zone fibroblastic reticular cells have a key function in naive CD4(+) and CD8(+) T cell homeostasis by providing a limited reservoir of survival factors.