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ABSTRACT. The Franklin expedition set sail in 1845 in search of the Northwest Passage through the Canadian Arctic. During the first winter in the Arctic, three crewmen died of unknown [...]

Until recently, domestication has been interpreted as a rapid process with little predomestication cultivation and a relatively rapid rise of the domestication syndrome. This interpretation has had a profound effect on the biological framework within which investigations into crop origins have been carried out. A major underlying assumption has been that artificial selection pressures were substantially stronger than natural selection pressures, resulting in genetic patterns of diversity that reflect genetic independence of geographic localities. Recent archaeobotanical evidence has overturned the notion of a rapid transition, resulting in a protracted model that undermines these assumptions. Conclusions of genome-wide multilocus studies remain problematic in their support of a rapid-transition model by indicating that domesticated crops appear to be associated by monophyly with only a single geographic locality. Simulations presented here resolve this conflict, indicating that the results observed in such studies are inevitable over time at a rate that is largely influenced by the long-term population size. Counterintuitively, multiple origin crops are shown to be more likely to produce monophyletic clades than crops of a single origin. Under the protracted transition, the importance of the rise of the domestication syndrome becomes paramount in producing the patterns of genetic diversity from which crop origins may be deduced. We identify four different interacting levels of organization that now need to be considered to track crop origins from modern genetic diversity, making crop origins a problem that could be addressed through system-based approaches. domestication | phylogenetics | protracted transition | simulation

We present a method to distinguish authentic ancient DNA from contaminating DNA in a human bone. This is achieved by taking account of the spatial distribution of the various sequence families within the bone and the extent of degradation of the template DNAs, as revealed by the error content of the sequences. To demonstrate the veracity of the method, we handled two ancient human tibiae in order to contaminate them with modern DNA, and then subjected segments of the bones to various decontaminating treatments, including removal of the outer 1-2 mm, before extracting DNA, cloning, and obtaining a total of 107 mitochondrial DNA sequences. Sequences resulting from the deliberate contamination were located exclusively in the outer 1-2 mm of the bones, and only one of these 27 sequences contained an error that could be ascribed to DNA degradation. A second, much smaller set of relatively error-free sequences, which we ascribe to contamination during excavation or curation, was also located exclusively in the outer 1-2 mm. In contrast, a family of 72 sequences, displaying extensive degradation products but identifiable as haplogroup U5ala, was distributed throughout one of the bones and represents the authentic ancient DNA content of this specimen. KEY WORDS biomolecular archaeology; mitochondrial DNA; haplogroups

A hybrid neural network model is constructed by characterizing the growth of Ga[As.sub.1-y][P.sub.y]-GaAs superlattices (SLs) grown on (001) GaAs substrates by molecular beam epitaxy. These heterostruetures are formed by the [P.sub.2] exposure of an As-stabilized GaAs surface, and ex situ high-resolution X-ray diffraction (HRXRD) is performed to determine the phosphorus composition at the interfaces. A first-order kinetic model is then developed to describe the mechanisms of anion exchange, surface desorption, and diffusion. A semi-empirical hybrid neural network is used to estimate the parameters of the kinetic model and analyze the microscopic processes occurring at the interfaces of the mixed anion III-V heterostructures. The phosphorus diffusion process in GaAs is estimated to have a diffusion coefficient of D = 1.4 x [10.sup.-14] exp(-0.11 eV/[k.sub.B][T.sub.s]) [cm.sup.2] * [s.sup.-1] for samples with [P.sub.As4] = 4 x [10.sup.-6] torr and exhibits enhanced phosphorus intermixing for samples with lower As-stabilizing fluxes. Index Terms--Anion exchange, hybrid neural networks, kinetic modeling, molecular beam epitaxy.

Irish Novelists and the Victorian Age, by James H. Murphy; pp. 304. Oxford and New York: Oxford University Press, 2011, 66.00 [pounds sterling], $110.00. Fiction by Irish men and women [...]

Since 1980 a number of studies have described changes in the for-hire trucking industry following the Motor Carrier Act of 1980.(1) However, little attention has been paid to the impact [...]

The genetic history of wheat is the story of the world's temperate staple food. Archaeologically, charred grains are the common way wheat is preserved. Study of burnt spelt wheat from [...]

As-for-Sb and Sb-for-As anion exchange reactions are investigated in a molecular beam epitaxy environment, where the GaSb surfaces are exposed to [As.sub.2] and [As.sub.4] species and the GaAs is exposed to [Sb.sub.2], respectively. The As-for-Sb anion exchange reaction competes with the formation of isoelectronic As[Sb.sub.y] compounds and the Sb-for-As anion exchange does not occur due to the low diffusivity of Sb into GaAs.

The fundamental chemical and kinetic surface processes governing the P-for-As exchange reaction during epitaxial layer synthesis are examined. It is found that As-rich GaAs surface reconstructions inhibit P-for-As exchange and a chemical model is proposed that includes P chemisorption and indiffusion, and the competition between P-for-As anion exchange and the formation of AsP isoelectronic compounds.

Byline: Terence A. Brown Deregulation of trucking in the US led to the creation of a new industry - truck brokerage - to help market the trucking service. Brokers are particularly useful to small, newer carriers that need help finding shipments. Brokers help shippers by offering lower prices or more convenience, i.e. they can often find a carrier or a particular type of truck quicker than the shipper. Deregulation of trucking can help an economy improve efficiency and become more competitive on a global basis.

George Moore, 1852-1933: A Biography. Adrian Frazier. New Haven: Yale UP, 2000. 604 pp. $35.00. 'His [Frazier's] strategy to rescue Moore from the comparative obscurity into which he has sunk […]

We have used network analysis to study gene sequences of the Triticum and Aegilops 5S rDNA arrays, as well as the spacers of the 5S-DNA-A1 and 5S-DNA-2loci. Network analysis describes relationships between 5S rDNA sequences in a more realistic fashion than conventional tree building because it makes fewer assumptions about the direction of evolution, the extent of sexual isolation, and the pattern of ancestry and descent. The networks show that the 5S rDNA sequences of Triticum and Aegilops species are related in a reticulate manner around principal nodal sequences. The spacer networks have multiple principal nodes of considerable antiquity but the gene network has just one principal node, corresponding to the correct gene sequence. The networks enable orthologous groups of spacer sequences to be identified. When orthologs are compared it is seen that the patterns of intra- and interspecific diversity are similar for both genes and spacers. We propose that 5S rDNA arrays combine sequence conservation with a large store of mutant variations, the number of correct gene copies within an array being the result of neutral processes that act on gene and spacer regions together.

This paper presents the systematic characterization of the molecular beam epitaxy (MBE) process to quantitatively model the effects of process conditions on film qualities. A five-layer, undoped AIGaAs and InGaAs single quantum well structure grown on a GaAs substrate is designed and fabricated. Six input factors (time and temperature for oxide removal, substrate temperatures for AIGaAs and InGaAs layer growth, beam equivalent pressure of the As source and quantum well interrupt time) are examined by means of a fractional factorial experiment. Defect density, X-ray diffraction, and photoluminescence are characterized by a static response model developed by training back-propagation neural networks. In addition, two novel approaches for characterizing reflection high-energy electron diffraction (RHEED) signals used in the real-time monitoring of MBE are developed. In the first technique, principal component analysis is used to reduce the dimensionality of the RHEED data set, and the reduced RHEED data set is used to train neural nets to model the process responses. A second technique uses neural nets to model RHEED intensity signals as time series, and matches specific RHEED patterns to ambient process conditions. In each case, the neural process models exhibit good agreement with experimental results. Index Terms--Molecular beam epitaxy (MBE), neural networks, process modeling.

DEREK HAND A HISTORY OF THE IRISH NOVEL. CAMBRIDGE: CAMBRIDGE UNIVERSITY PRESS. 2011. HARDBACK 55.00 [pounds sterling]/US$ 90.00. A KEY PROBLEM (cogently discussed in he introduction to this work), for [...]

Forty thousand years ago, the planet was more crowded than we thought. For decades we believed that there were just two members of the genus Homo living at that time. [...]

By Peter McDonald. Pp. x+242. Oxford: Clarendon Press, 1991. 30 £. It is Peter McDonald's contention in this densely textured, closely argued study that MacNeice's poetic reputation has suffered since [...]