An early medieval lead-smelting bole from Banc Tynddol, Cwmystwyth, Ceredigion

Excavations in 2002 at Cwmystwyth, in Central Wales, found an ancient lead smelting site. There are remains of the medieval and the Roman periods. This paper describes in brief the excavation of the medieval lead bole (Timberlake 2002a) but also provides an archaeological reconstruction of this and details of an experimental lead smelt carried out at the site in 2003 (by ST). The analytical study (by LA) is of the medieval metallurgical debris excavated in 2002, mostly slag, but also ore and lead. The aim was to understand the raw material, the metal produced and the smelting process. The ore smelted was predominantly galena but with no detectable silver, showing it was probably exploited to produce lead. The extremely high sulphur content of the slag indicates that the ore was not roasted before smelting. It is argued that the medieval activity was small-scale, smelting a very rich ore. The furnaces apparently did not require much capital investment, enabling a short-lived and/or exploratory smelting operation

Floquet Analysis of Atom Optics Tunneling Experiments

Dynamical tunneling has been observed in atom optics experiments by two groups. We show that the experimental results are extremely well described by time-periodic Hamiltonians with momentum quantized in units of the atomic recoil. The observed tunneling has a well defined period when only two Floquet states dominate the dynamics. Beat frequencies are observed when three Floquet states dominate. We find frequencies which match those observed in both experiments. The dynamical origin of the dominant Floquet states is identified.Comment: Accepted in Physical Review

Comparing periodic-orbit theory to perturbation theory in the asymmetric infinite square well

An infinite square well with a discontinuous step is one of the simplest systems to exhibit non-Newtonian ray-splitting periodic orbits in the semiclassical limit. This system is analyzed using both time-independent perturbation theory (PT) and periodic-orbit theory and the approximate formulas for the energy eigenvalues derived from these two approaches are compared. The periodic orbits of the system can be divided into classes according to how many times they reflect from the potential step. Different classes of orbits contribute to different orders of PT. The dominant term in the second-order PT correction is due to non-Newtonian orbits that reflect from the step exactly once. In the limit in which PT converges the periodic-orbit theory results agree with those of PT, but outside of this limit the periodic-orbit theory gives much more accurate results for energies above the potential step.Comment: 22 pages, 2 figures, 2 tables, submitted to Physical Review

FASTER MT: Isolation of Pure Populations of a and α Ascospores from Saccharomyces cerevisiae

The budding yeast Saccharomyces cerevisiae has many traits that make it useful for studies of quantitative inheritance. Genome-wide association studies and bulk segregant analyses often serve as first steps toward the identification of quantitative trait loci. These approaches benefit from having large numbers of ascospores pooled by mating type without contamination by vegetative cells. To this end, we inserted a gene encoding red fluorescent protein into the MATa locus. Red fluorescent protein expression caused MATa and a/α diploid vegetative cells and MATa ascospores to fluoresce; MATα cells without the gene did not fluoresce. Heterozygous diploids segregated fluorescent and nonfluorescent ascospores 2:2 in tetrads and bulk populations. The two populations of spores were separable by fluorescence-activated cell sorting with little cross contamination or contamination with diploid vegetative cells. This approach, which we call Fluorescent Ascospore Technique for Efficient Recovery of Mating Type (FASTER MT), should be applicable to laboratory, industrial, and undomesticated, strains

Valency Affecting Rules in Extended Categorial Grammar

An extension of categorial grammar is formally defined in which (C1,…Cn)/(D1…Dn) is a category whenever the C. and D. occur. Expressions in such categories combine with those of category D. to form those of category C .. all i I<=i<=n. Within this framework we show how to formulate Valency Affecting Rules (VAR's) such as Passive. Causative. Raising to Object. etc. E.g. Passive is defined as a way of deriving P:s (n place predicates) from Pn+ls. So it has an n-tuple category as above in which for each i. D. is an n+I place predicate category and C. is the appropriate n-place predicate category. (n place predicates. P :s. are expressions which combine with those of an appropriate argument category An to form Pn-I's. Pn is identified with S)

Computation in Classical Mechanics

There is a growing consensus that physics majors need to learn computational skills, but many departments are still devoid of computation in their physics curriculum. Some departments may lack the resources or commitment to create a dedicated course or program in computational physics. One way around this difficulty is to include computation in a standard upper-level physics course. An intermediate classical mechanics course is particularly well suited for including computation. We discuss the ways we have used computation in our classical mechanics courses, focusing on how computational work can improve students' understanding of physics as well as their computational skills. We present examples of computational problems that serve these two purposes. In addition, we provide information about resources for instructors who would like to include computation in their courses.Comment: 6 pages, 3 figures, submitted to American Journal of Physic

Haploinsufficiency of SF3B2 causes craniofacial microsomia

Craniofacial microsomia (CFM) is the second most common congenital facial anomaly, yet its genetic etiology remains unknown. We perform whole-exome or genome sequencing of 146 kindreds with sporadic (n = 138) or familial (n = 8) CFM, identifying a highly significant burden of loss of function variants in SF3B2 (P = 3.8 × 10−10), a component of the U2 small nuclear ribonucleoprotein complex, in probands. We describe twenty individuals from seven kindreds harboring de novo or transmitted haploinsufficient variants in SF3B2. Probands display mandibular hypoplasia, microtia, facial and preauricular tags, epibulbar dermoids, lateral oral clefts in addition to skeletal and cardiac abnormalities. Targeted morpholino knockdown of SF3B2 in Xenopus results in disruption of cranial neural crest precursor formation and subsequent craniofacial cartilage defects, supporting a link between spliceosome mutations and impaired neural crest development in congenital craniofacial disease. The results establish haploinsufficient variants in SF3B2 as the most prevalent genetic cause of CFM, explaining ~3% of sporadic and ~25% of familial cases

Scattering properties of a cut-circle billiard waveguide with two conical leads

We examine a two-dimensional electron waveguide with a cut-circle cavity and conical leads. By considering Wigner delay times and the Landauer-B\"{u}ttiker conductance for this system, we probe the effects of the closed billiard energy spectrum on scattering properties in the limit of weakly coupled leads. We investigate how lead placement and cavity shape affect these conductance and time delay spectra of the waveguide.Comment: 18 pages, 11 figures, accepted for publication in Phys. Rev. E (Jan. 2001