Talking About My Generation: the Date of the West Kennet Long Barrow

Thirty-one radiocarbon results are now available from the West Kennet long barrow, and are presented within an interpretive Bayesian statistical framework. Two alternative archaeological interpretations of the sequence are given, each with a separate Bayesian model. In our preferred interpretation, the barrow is seen as a unitary construction (given the lack of dating samples from the old ground surface, ditches or constructional features themselves), with a series of deposits of human remains made in the chambers following construction. Primary deposition in the chambers is followed by further secondary deposition of some human remains, including children, and layers of earth and chalk, the latest identifiable finds in which are Beaker sherds. In the Bayesian model for this sequence, the construction of the monument at West Kennet, as dated from the primary mortuary deposits, occurred in 3670–3635 cal. BC, probably in the middle decades of the thirty-seventh century cal. BC. The last interments of this initial use of the chambers probably occurred in 3640–3610 cal. BC. The difference between these two distributions suggests that this primary mortuary activity probably continued for only 10–30 years. After a hiatus probably lasting for rather more than a century, the infilling of the chambers began in 3620–3240 cal. BC and continued into the second half of the third millennium cal. BC. In an alternative interpretation, we do not assume that all the people dated from the primary mortuary deposits were placed in the monument in a fleshed or partially articulated condition; they could therefore have died before the monument was built, although they must have died before the end of the formation of the mortuary deposit. In the Bayesian model for this interpretation, the monument appears to belong either to the thirty-seventh century cal. BC or the mid-thirty-sixth century cal. BC, and deposition again appears short-lived, but the model is unstable. Results are discussed in relation to the setting and sequence of the local region

Serious mortality: the date of the Fussell's Lodge long barrow

Twenty-seven radiocarbon results are now available from the Fussell’s Lodge long barrow, and are presented within an interpretive Bayesian statistical framework. Three alternative archaeological interpretations of the sequence are given, each with a separate Bayesian model. It is hard to decide between these, though we prefer the third. In the first (following the excavator), the construction is a unitary one, and the human remains included are by definition already old. In the second, the primary mortuary structure is seen as having two phases, and is set within a timber enclosure; these are later closed by the construction of a long barrow. In that model of the sequence, deposition began in the 38th century cal BC and the mortuary structure was extended probably in the 3660s–3650s cal BC; the long barrow was probably built in the 3630s–3620s cal BC; ancestral remains are not in question; and the use of the primary structure may have lasted for a century or so. In the third, preferred model, a variant of the second, we envisage the inclusion of some ancestral remains in the primary mortuary structure alongside fresh remains. This provides different estimates of the date of initial construction (probably in the last quarter of the 38th century cal BC or the first half of the 37th century cal BC) and the duration of primary use, but agrees in setting the date of the long barrow probably in the 3630s–3620s cal BC. These results are discussed in relation to the development and meanings of long barrows at both national and local scales

Once in a lifetime: the date of the Wayland's Smithy long barrow

Twenty-three radiocarbon results are now available from the Wayland’s Smithy long barrow, and are presented within an interpretive Bayesian statistical framework. Four alternative archaeological interpretations of the sequence are considered, each with a separate Bayesian model, though only two are presented in detail. The differences are based on different readings of the sequence of Wayland’s Smithy II. In our preferred interpretation of the sequence, the primary mortuary structure was some kind of lidded wooden box, accessible for deposition over a period of time, and then closed by the mound of Wayland’s Smithy I; Wayland’s Smithy II was a unitary construction, with transepted chambers, secondary kerb and secondary ditches all constructed together. In the Bayesian model for this interpretation, deposition began in the earlier 36th century cal BC, and probably lasted for a generation. A gap of probably 40–100 years ensued, before the first small mound was constructed in 3520–3470 cal BC. After another gap, probably of only 1–35 years, the second phase of the monument was probably constructed in the middle to later part of the 35th century cal BC (3460–3400 cal BC), and its use probably extended to the middle decades of the 34th century cal BC. Results are discussed in relation to the local setting, the nature of mortuary rites and the creation of tradition

A Method to Partially Suppress IS1 and MA1 for DS SS CDMA Wireless Networks

We propose a method to partially suppress ISI and MAI for US SS CDMA schemes in wireless LANs. The method can be regarded as an alternative approach to combat ISI and in particular MAI by the use of advanced multiuser detection. Instead of using very sophisticated detectors, we propose introduction of a simple modification to the carrier waveform which results in very substaiitial reduction in cross-correlation belween users and an off-peak auto-correlation. The method can be applied to any DS SS CDMA scheme, but should be particularly useful in the case of short spreading signatures, as is the case of WLAN

Spin injection from a half-metal at finite temperatures

Spin injection from a half-metallic electrode in the presence of thermal spin disorder is analyzed using a combination of random matrix theory, spin-diffusion theory, and explicit simulations for the tight-binding s-d model. It is shown that efficient spin injection from a half-metal is possible as long as the effective resistance of the normal metal does not exceed a characteristic value, which does not depend on the resistance of the half-metallic electrode, but is rather controlled by spin-flip scattering at the interface. This condition can be formulated as \alpha<(l/L)/T, where \alpha is the relative deviation of the magnetization from saturation, l and L the mean-free path and the spin-diffusion length in the non-magnetic channel, and T the transparency of the tunnel barrier at the interface (if present). The general conclusions are confirmed by tight-binding s-d model calculations. A rough estimate suggests that efficient spin injection from true half-metallic ferromagnets into silicon or copper may be possible at room temperature across a transparent interface.Comment: 9 pages, 4 figures, revtex4-1; expanded introduction, added references, additional comments in Section V, fixed typo

Agribusiness Extension: The Past, Present, and Future?

The IFAMR is publish by (IFAMA) the International Food and Agribusiness Management Association. www.ifama.orgagribusiness extension, future, Agribusiness, Teaching/Communication/Extension/Profession, Q130,