Doing audience history: questions, sources, methods.

Audience history poses a methodological as well as an intellectual challenge. Everyday practices of readers, viewers and listeners are typically beyond the remit of sources found in institutional archival collections, and the researcher is often left with a plethora of sources that only marginally address the object of study, and rarely amount to a clear-cut, homogeneous understanding of audiences and their historical practices. Contemporary audience surveys, documents produced by governmental, administrative and legal bureaucracies, professional testimonies, oral history interviews and other sources each offer their own vision of the audience. How does one move beyond these multiple, often contradictory visions, to a reasonably coherent history of the actual everyday practices and thoughts of media users? Given the overwhelming variety, yet in some sense also paucity of relevant sources, it is of no surprise that media historiography has often given preference to safer fields: the history of institutions and media content. Recent years have of course seen some notable advances in the field of audience historiography – most prominently Richard Butsch’s (2000) path-breaking study of American audiences in the 19th and the 20th century, Butsch and Livingstone’s (2013) the edited collection exploring the variegated meanings of audiences historically and globally, as well as the fast growing body of historical studies of film reception and movie-going (e.g. Staiger 1992, Stacey 1994, Maltby et al. 2007, Kuhn 2004). Nonetheless, it is fair to say that historical research on media audiences is still in its infancy. There have been only very few attempts to systematically address its key concerns and methodological principles (see Biltereyst et al. 2012 for an exception), and the empirical focus of existing work has been somewhat uneven, with most research focusing on film and cinema-going and much less on broadcasting, for instance. Furthermore, despite the growth of single country case studies from beyond the western world, we have yet to develop a more synthetic and explanatory account of the differences and similarities between audience histories globally

Rapid response of erosion to recent climatic changes: New insights from uranium-series

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Weathering and transport of sediments in the Bolivian Andes: time constraints from uranium-series isotopes

Rivers from the upper Rio Madeira basin (Bolivia) have been studied with uranium-series isotopes in order to constrain the timescales of weathering and sediment transfer from the Andes through the Amazon tropical plain. Uranium (U), thorium (Th) and radium (Ra) isotopes (238U–234U–230Th–226Ra and 232Th) have been analyzed in the suspended load (\u3e0.2 μm) of rivers. Increasing 230Th excesses relative to 238U in suspended particles from the Andes to the tropical plain is interpreted as an increasing duration of weathering during sediment transport and storage in the foreland basin. Model calculations for (230Th/238U) and (226Ra/230Th) activity ratios in suspended particles using a continuous weathering model indicates that: (i) the timescale for production, storage and transport of sediments in the Andean Cordillera is only a few kyr, (ii) the storage time of suspended sediments in the foreland basin is 5±1 kyr and (iii) the average transfer time of suspended sediments from the Andes to the confluence of Rio Madeira with the Amazon River is 17±3 kyr. An implication of these short timescales is that the bedrock eroded must have lost part of its uranium during one or several past erosion cycles. This demonstrates the recycling of sediments through several erosion cycles before transfer to the oceans. The calculation of long-term (\u3e1 kyr), steady-state erosion rates indicates that they are much lower than present-day rates. This increase in denudation rates must be recent and could be explained by an increase in precipitation ∼4 ka ago, as suggested by palaeoclimatic evidences and the draining of transient sedimentary basins encountered on the Altiplano and easily eroded. This suggests that climatic variability rather than tectonics alone produces high erosion rates

Putative pectate lyase PLL12 and callose deposition through polar CALS7 are necessary for long-distance phloem transport in Arabidopsis

In plants, the phloem distributes photosynthetic products for metabolism and storage over long distances. It relies on specialized cells, the sieve elements, which are enucleated and interconnected through large so-called sieve pores in their adjoining cell walls. Reverse genetics identified PECTATE LYASE LIKE 12 (PLL12) as critical for plant growth and development. Using genetic complementations, we established that PLL12 is required exclusively late during sieve element differentiation. Structural homology modeling, enzyme inactivation, and overexpression suggest a vital role for PLL12 in sieve element specific pectin remodeling. While short distance symplastic diffusion is unaffected, the pll12 mutant is unable to accommodate sustained plant development due to an incapacity to accommodate increasing hydraulic demands on phloem long distance transport as the plant grows – a defect that is aggravated when combined with another sieve element specific mutant callose synthase 7 (cals7). Establishing CALS7 as a specific sieve pore marker, we investigated the subcellular dynamics of callose deposition in the developing sieve plate. Using fluorescent CALS7 then allowed identifying structural defects in pll12 sieve pores that are moderate at the cellular level but become physiologically relevant due to the serial arrangement of sieve elements in the sieve tube. Overall, pectin degradation through PLL12 appears subtle in quantitative terms. We therefore speculate that PLL12 may act as a regulator to locally remove homogalacturonan thus potentially enabling further extracellular enzymes to access and modify the cell wall during sieve pore maturation.Peer reviewe

Développement d'un outil pour la sélection assistée par marqueurs chez le ray-grass anglais

Forage varieties are synthetic varieties obtained by the intercross of a small number of elite genotypes selected in recurrent selection programs. This breeding method has been successful to improve forage species but its efficiency could be increased by the use of molecular markers. The goal of this study was to develop a tool for an easy genotyping of thousands of individuals with an hundred markers evenly spread across the genome in perennial ryegrass. The strategy was to design primer pairs in conserved regions on both sides of an intron for amplification and sequencing in genotypes of interest (polycross parents). Sequences were used to develop SNP markers. We developed 363 primer pairs evenly distributed across the genome with good amplification in perennial ryegrass. Moreover, these primer pairs showed an excellent transferability to other forage grass species (between 73 and 97% in fescues and 77% in cocksfoot). Polymorphism study on seven perennial ryegrass genotypes revealed one SNP every 42 bases on average. Only 38% of the SNPs were heterozygous in more than one genotype. This required to develop specific SNP markers in order to study segregating progenies within each of the seven genotypes.Les variétés fourragères sont des variétés synthétiques obtenues par intercroisement en panmixie d’un certain nombre de constituants sélectionnés selon des schémas de sélection récurrente. Cette stratégie d’amélioration a permis un progrès génétique indéniable, mais son efficacité pourrait être accrue grâce à l’utilisation de marqueurs moléculaires. L’objectif de cette étude était de développer un outil permettant de génotyper facilement plusieurs milliers d’individus avec une centaine de marqueurs répartis sur l’ensemble du génome chez le ray-grass anglais. La stratégie a été de développer des couples d’amorces dans des régions conservées encadrant un intron pour amplification et séquençage dans les génotypes d’intérêt (parents de polycross). Les séquences ont ensuite été utilisées pour développer des marqueurs SNP. Au total, nous avons développé 363 couples d’amorces bien répartis sur le génome et présentant une amplification correcte chez le ray-grass anglais. De plus, ces amorces ont montré une excellente transférabilité à d’autres espèces de graminées fourragères (de 73 à 97 % pour les fétuques et 77 % pour le dactyle). L’étude du polymorphisme sur sept génotypes de ray-grass anglais a révélé en moyenne un SNP toutes les 42 bases. Seulement 38 % des SNP étaient hétérozygotes chez plus d’un génotype, ceci a conduit à développer des marqueurs SNP spécifiques à chacun des sept génotypes pour l’étude de la ségrégation de leurs descendances respectives

Politique et television

Available at INIST (FR), Document Supply Service, under shelf-number : AR 13699 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc