566 research outputs found
Archaeometric Characterization of Roman Tile Fabrics from the Sangro Valley, Italy
In this paper, I use archaeometric methods to investigate the raw materials and manufacture of terracotta roof tiles from three Roman sites in the Sangro Valley, Abruzzo, Italy. Although fragmentary remains of the tegula and imbrex roof system are commonly uncovered at sites throughout the ancient world, these tiles are woefully understudied. Equally obscure are the workings of the economy of Samnium during and after its conquest by the Romans. As mass-produced industrial materials generally manufactured and used within a small radius, tiles may prove to be the ideal medium through which to explore the regional ceramic economy. This study applies ceramic petrography and x-ray fluorescence to tiles from the Sangro Valley Project\u27s excavations at Monte Pallano, Acquachiara, and San Giovanni, as well as to samples of local clays and regional coarsewares, in order to identify mineralogical and chemical patterns related to clay sourcing and tile production. These efforts cast doubt on the validity of current methods for identifying ceramic groups and creating fabric typologies, yet they simultaneously shed light on the nature of tile manufacturing in the ancient Sangro Valley, suggesting a pattern of decentralized production in a diffusely settled area. This, in turn, may prove significant for the archaeological interpretation of social and economic trends in the region
REVERSAL OF POLICY: THE DEPARTMENTS OF STATE AND DEFENSE, AND THE ARMING OF THE FEDERAL REPUBLIC OF GERMANY, 1946-1955
Between 1946 and 1950, the U.S. State Department repeatedly expressed its determination to keep Germany disarmed and demilitarized and offered pledges regarding the extended presence of U.S. troops in Western Europe. At the same time, and initially unbeknownst to the State Department, the U.S. Joint Chiefs of Staff were making plans to arm Germany in response to the growing Soviet threat to Western Europe. In September 1950, in reaction to the communist invasion of South Korea that had prompted fears the same would happen in Germany, the United States decided to arm the Federal Republic of Germany. Although coupled with a pledge to increase the number of U.S. troops in Europe, the U.S. decision resulted in a number of unintended consequences including a Congressional challenge to Presidential power, opposition by and discord among U.S. Allies, loss of control over the rearmament process, and the establishment of a new set of relations with its erstwhile enemy. While the actual outcome of that 1950 decision was positive, i.e., the arming of the Federal Republic of Germany was approved, the creation of a national German army was not what official U.S. policy had intended
Genome-Wide Localization And Novel Deposition Pathways Of Histone Variant H3.3 In Embryonic Stem And Neuronal Precursor Cells
The eukaryotic genome is composed of chromatin, a complex polymer of genomic DNA, RNA, and closely associated proteins. Histone proteins form the core of the nucleosome, the fundamental repeating unit of chromatin. Variant histone proteins play critical roles in the epigenetic regulation of gene expression and in the development of multicellular organisms. In this thesis, I describe the first genome-wide profiles of histone H3 variants in pluripotent mammalian embryonic stem (ES) cells, and I establish the dependence and independence of these patterns on the histone chaperone Hira. To distinguish H3 variants, I use designed zinc finger nucleases (ZFNs) to rapidly knock epitope tags into a single allele of the endogenous histone H3.3B gene in mouse ES cells. Genome-wide analysis reveals that H3.3 is enriched in specific patterns at active and repressed genes with high CpG content promoters, including developmentally repressed bivalent H3K4me3 / H3K27me3 genes in ES cells, in addition to transcribed non-coding regions, telomeres, ribosomal DNA (rDNA), and genic and intergenic transcription factor binding sites (TFBS). Transcriptional termination sites of highly transcribed genes are marked by peaks of H3.3 and phosphorylated RNA polymerase II. Differentiation of ES cells into neural precursor cells (NPCs) leads to specific changes in H3.3 localization, demonstrating that the localization of H3.3 is dependent on cellular state. Targeted gene editing of H3.3B to H3.2 or H3.1 using ZFNs demonstrates that these patterns are dependent on the amino acid sequence of endogenous H3.3. Using wild-type and Hira -/- ES cells, I show that the H3.3 chaperone Hira is required for H3.3 enrichment at active and repressed genes. Strikingly, Hira is not essential for deposition of H3.3 at rDNA, telomeres, and specific TFBS. Immunoaffinity purification and mass spectrometry reveal that the proteins Atrx and Daxx associate with H3.3 in a Hira-independent manner. Using Atrxflox and Atrxnull mouse ES cells, I find that Atrx is specifically required for Hira-independent enrichment of H3.3 at telomeres and rDNA, and for repression of telomeric and ribosomal RNA. Overall, the data in this thesis demonstrate that multiple and distinct pathways are responsible for H3.3 deposition at specific genomic locations in mammalian cells
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