Excavation at Aguas Buenas, Robinson Crusoe Island, Chile, of a gunpowder magazine and the supposed campsite of Alexander Selkirk, together with an account of early navigational dividers

Excavations were undertaken of a ruined building at Aguas Buenas, identified as an 18th-century Spanish gunpowder magazine. Evidence was also found for the campsite of an early European occupant of the island. A case is made that this was Alexander Selkirk, a castaway here from 1704 to 1709. Selkirk was the model for Defoe’s Robinson Crusoe. A detailed discussion is given of a fragment of copper alloy identifi ed as being from a pair of navigational dividers

Methods for Optical Calibration of the BigBite Hadron Spectrometer

The techniques for optical calibration of Jefferson Lab's large-acceptance magnetic hadron spectrometer, BigBite, have been examined. The most consistent and stable results were obtained by using a method based on singular value decomposition. In spite of the complexity of the optics, the particles' positions and momenta at the target have been precisely reconstructed from the coordinates measured in the detectors by means of a single back-tracing matrix. The technique is applicable to any similar magnetic spectrometer and any particle type. For 0.55 GeV/c protons, we have established the vertex resolution of 1.2 cm, angular resolutions of 7 mrad and 16 mrad (in-plane and out-of-plane, respectively), and a relative momentum resolution of 1.6%.Comment: 26 pages, 13 figure

Measurement of the single-spin asymmetry A y 0 in quasi-elastic 3He↑(e,e′n) scattering at 0.4 < Q 2 < 1.0 GeV/c 2

No abstract available

Estimativa de carbonato de cálcio aplicado via água de irrigação nas regiões da Chapada do Apodi e Baixo Açu, RN Estimate of the calcium carbonate applied through irrigation water in Chapada do Apodi and Baixo Açu regions of Rio Grande do Norte, Brazil

A aplicação de água com elevados teores de carbonato e bicarbonato pela irrigação, pode contribuir para o aumento do pH dos solos após alguns anos de cultivo. Esse trabalho teve como objetivo avaliar a água de irrigação quanto a seu teor de carbonato e bicarbonato, baseado no conceito do equivalente carbonato de cálcio (E CACO3) da água de irrigação nas regiões da Chapada do Apodi e Baixo Açu no Estado do Rio Grande do Norte. Considerando uma lâmina de irrigação de 400 mm, os resultados mostraram que as águas da região da Chapada do Apodi apresentaram maiores valores de E CACO3 quando comparadas com as água da região do Baixo Açu. Na região da Chapada do Apodi os maiores valores de E CACO3 independente da origem foram para as águas da região de Mossoró, com média de 765 kg ha-1 e o menor valor foi para a região de Grossos e Upanema com 626 kg ha-1. Para a região do Baixo Açu, verifica-se que, independente da origem das águas, a região de Ipanguassu apresentou os maiores valores de E CACO3 com média de 654 kg ha-1, e o menor valor foi para a região de Carnaubais com 580 kg ha-1.<br>The application of irrigation water with high contents of carbonate and bicarbonate can contribute to pH elevation of the soils after some years of cultivation. This study had as its objective the evaluation of the irrigation water with respect to its carbonate and bicarbonate content, based on the concept of the Equivalent Calcium Carbonate (E CACO3) in the region of the Chapada do Apodi and Baixo Açu in the state of Rio Grande do Norte, Brazil. Considering an irrigation water depth of 400 mm, the results showed that the waters of the region of the Chapada do Apodi presented larger values of E CACO3 compared to those of the region of Baixo Açu. In the region of the Chapada do Apodi, independent of the origin, largest values of E CACO3 were found for the waters of the region of Mossoró, with an average of 765 kg ha-1 and the smallest value was observed for Grossos and Upanema with 626 kg ha-1. For the region of Baixo Açu, independent of the origin of the waters, the region of Ipanguassu presented the highest values of E CACO3 with an average of 654 kg ha-1 whereas the smallest values were found for the region of Carnaubais, with 580 kg ha-1