The use of radiocarbon-derived ΔC as a paleoclimate indicator: applications in the Lower Alentejo of Portugal

Values of δ¹³C are frequently reported with radiocarbon dates from organic materials. In C₃ plants δ¹³C values have been linked to changes in water use efficiency as a response to arid conditions. By calculating ¹³C discrimination (Δ¹³C) from ¹³C isotopic composition (δ¹³C), archaeologists can gain potentially valuable inference into past climate conditions. Values of Δ¹³C reflect the process of discrimination against heavier ¹³C isotopes of carbon by comparing the δ¹³C of samples to that of the atmosphere, and can be calculated when records of atmospheric δ¹³CO₂ are available. The present study examines a 1300 year history of radiocarbon-derived Δ¹³C from the Lower Alentejo of Portugal using charcoal recovered from excavations of a series of medieval habitation sites in the study area. To calculate Δ¹³C, the posterior means generated from Bayesian change-point analysis of δ¹³CO₂ records were used. Archaeological data were then compared to contemporary ecological studies of Δ¹³C of the same taxa against instrumental records of climate. Values of Δ¹³C fell within mean ranges for the taxa through a period of population growth between the 7th and 10th centuries AD. During the height of the Medieval Warm Period in the 11th century AD Δ¹³C values frequently fell to low levels associated with arid conditions. At this time environmental degradation and erosion were documented. Values of Δ¹³C increased for a brief period in the early 12th century AD before the rural Lower Alentejo was largely abandoned for nearly two centuries. Another period of aridity occurred in the 16th and 17th centuries AD. Radiocarbon-derived Δ¹³C is a potentially useful paleoclimate proxy for archaeologists provided that results can be paired with observed Δ¹³C variation in studies that pair these data with instrumental climate records.     

Calcium oxalate AMS C dating and chronology of post-Palaeolithic rock paintings in the Iberian Peninsula. Two dates from Abrigo de los Oculados (Henarejos,Cuenca, Spain)

Since 2005 we have been utilizing accelerator mass spectrometry (AMS) ¹⁴C dating in research on calcium oxalate crusts associated with open air rock art of the Iberian Peninsula. In this paper we present two dates linked with three eye-idol pictographs at Abrigo de los Oculados (Henarejos, Cuenca, Spain). Radiocarbon ages for these motifs agree with the expected iconography-based archaeological chronology. Such oxalate dates could provide an independent basis for evaluating chronological theories for post-Palaeolithic sites, designated in the UNESCO World Heritage List as Rock Art of the Mediterranean Basin on the Iberian Peninsula.     

激光治疗仪中C8051单片机FLASH存储器的应用

本文针对基于C8051的激光治疗仪提出了一种新的数据存储方法,通过单片机自带的FLASH存储器进行存储,节省了硬件资源。文中详细介绍了单片机中FLASH存储器的使用方法,给出了设计的程序框图和简单的例程．     

SIMULATION OF THE CYCLIC BEHAVIOUR OF R/C RECTANGULAR HOLLOW SECTION BRIDGE PIERS VIA A DETAILED NUMERICAL MODEL

In the search for robust constitutive models suitable for reproducing the performance of bridge piers during a seismic event, this paper details the simulation of the cyclic responses of four rectangular hollow section R/C bridge piers. These four R/C bridge piers were built at scale 1/2.5 and tested experimentally. Both tall and short piers are considered, covering situations where bending or shear are of relevance. Furthermore, the four piers were reinforced according to rather different design strategies: (I) the first is a 30-year-old bridge designed without allowance to the seismic action, and (ii) the second is a bridge fulfilling the EC8 provisions. The detailed constitutive model that provides the numerical predictions includes two submodels: one with two scalar damage variables, reproducing the tensile and compressive degradations of concrete, and the other is based on the Giuffre-Menegotto-Pinto formulation, simulating the cyclic behaviour of the re-inforcement. The Damage Mechanics submodel is implemented at the Gauss points of the finite elements that discretize the concrete, whereas the steel submodel is implemented on the 2-noded truss elements adopted for the rebars. A comparison between the numerical and the experimental results is discussed in detail in this paper.     

Corruption European Style: The 1861 Frémont Scandal and Popular Fears in the Civil War North

Union General John C. Frémont excited considerable controversy during the Civil War, and not just due to his dubious military competence and early advocacy of emancipation. Many republican‐influenced citizens suspected Frémont of the corrupt misuse of power, and undermining the essential moral basis of the republic. While ultimately his ineffectual generalship might have reassured Northerners that “the Pathfinder” was hardly likely to succeed in his suspected schemes, it is striking that even during the war for national survival, citizens remained deeply concerned with the possible threat of power (particularly in the hands of corrupt, designing men) to liberty.     

Hemp in ancient rope and fabric from the Christmas Cave in Israel: talmudic background and DNA sequence identification

The “Christmas Cave”, a cave in the Qidron Valley near the Dead Sea and Qumran, has yielded a complex collection of plant-derived rope and fabric artifacts. Using polymerase chain reaction (PCR) to amplify DNA of the samples, we estimated the sizes and determined restriction patterns and base sequences of chloroplast genes, primarily rbcL (gene for the large subunit of ribulose bisphosphate carboxylase). DNA was successfully extracted from all samples, but was limited to sizes of approximately 200–300 base pairs. As expected, the DNA extracted from the samples was identified as coming primarily from flax (Linum usitatissamum L.), but two samples had a significant fraction, and all samples had at least a trace, of hemp (Cannabis sativa L.) DNA. Artifacts from the Christmas Cave were thought to date from Roman times, but it was thought possible that some could be much older. Accelerator mass spectrometry (AMS)-based ¹⁴C dating confirmed that the samples contained representatives from both the Roman and Chalcolithic periods. This paper provides a synthesis of DNA, isotope, and literary analysis to illuminate textile history at the Christmas Cave site.     

Increasing contextual information by merging existing archaeological data with state of the art laser scanning in the prehistoric funerary deposit of Pastora Cave,Eastern Spain

In this paper we present a virtual reconstruction of prehistoric funerary practices in Pastora Cave, a collective burial site in Eastern Spain that dates from the Late Neolithic, Chalcolithic and Bronze Age. Modern data of the cave was captured by 3D laser scanning techniques and added to recorded archaeological data and 3D graphic information. The combination of these data sets allowed us to create a hypothetical reconstruction to analyze the material excavated in the 1940s and 50s in greater spatial context. A 3D model of the current cave was created in order to serve as a basis for modeling the relative stratigraphic information available. We present the methodology employed and the results and implications of the analysis for Pastora Cave with particular emphasis on the spatial and chronological data.     

The Rolt Memorial Lecture 2018: Science and Engineering at War in Orkney

Initially conceived as a contribution to a conference which was to have been based in Caithness and was to have included a visit to Orkney, this paper examines the scientific and technological background to some of the wartime remains associated with the defence of Scapa Flow, the Royal Navy’s principal fleet anchorage in home waters in World Wars I and II. Summarising the surviving evidence of selected aspects of vessel-related, marine and aerial science and engineering around Scapa Flow, it is prefaced by a short account of Tom Rolt’s own wartime career, and concludes with a comparative appreciation of his place in the pantheon of literary engineers.