Mass spectrometric methods prove the use of beeswax and ruminant fat in late Roman cooking pots

Lipid extracts of sherds of archaeological late Roman cooking pots were analysed using high temperature-gas chromatography coupled to a mass spectrometer and liquid chromatography with atmospheric pressure chemical ionization mass spectrometer detection (LC-APCI-MS). With these advanced techniques the use of beeswax was shown through identification of the constituting alkanes, mono and diesters. The detection of high amounts of saturated triacylglycerols (TAGs) further indicated that animal fat was processed in these pots. Part of the animal fat was characterised as originating from ruminants due to the presence of trans-fatty acids. The distribution of saturated TAGs and the higher concentration of stearic acid compared to palmitic acid in the transesterified lipid extract indicated that this was sheep fat. The results illustrate how complex mixtures can be unravelled and original contents of ancient ceramic vessels can be determined using specialised analytical equipment.     

The bromopentadienyl acrylate approach to himbacine

[reaction: see text] The syntheses of 4,4a-didehydrohimbacine and 4,4a-didehydrohimandravine are presented. Key steps include an intramolecular Diels-Alder reaction of a bromopentadienyl acrylate and Suzuki-Miyaura and Stille coupling reactions.     

Rho(0) meson production in the pp-->pppi(+)pi(-) reaction at 3.67 GeV/c

Total and differential cross sections for the exclusive reaction pp-->pp rho observed via the pi(+)pi(-) decay channel have been measured at p(beam)=3.67 GeV/c. The observed total meson production cross section is determined to be (23.4+/-0.8+/-8) mu b and is significantly lower than typical cross sections used in model calculations for heavy-ion collisions. The differential cross sections measured indicate a strong anisotropy (approximately cos(theta(CM)(rho)) in the rho(0) meson production.     

Spiral wave generation in heterogeneous excitable media

As the coupling in a heterogeneous excitable medium is reduced, three different types of behavior are encountered: plane waves propagate without breaking up, plane waves break up into spiral waves, and plane waves block. We illustrate these phenomena in monolayers of chick embryonic heart cells using calcium sensitive fluorescent dyes. Following the addition of heptanol, an agent that reduces the electrical coupling between cells, we observe breakup of spiral waves. These results are modeled in a heterogeneous cellular automaton model in which the neighborhood of interaction is modified.     

Introduction: Mapping and control of complex cardiac arrhythmias

This paper serves as an introduction to the Focus Issue on mapping and control of complex cardiac arrhythmias. We first introduce basic concepts of cardiac electrophysiology and describe the main clinical methods being used to treat arrhythmia. We then provide a brief summary of the main themes contained in the articles in this Focus Issue. In recent years there have been important advances in the ability to map the spread of excitation in intact hearts and in laboratory settings. This work has been combined with simulations that use increasingly realistic geometry and physiology. Waves of excitation and contraction in the heart do not always propagate with constant velocity but are often subject to instabilities that may lead to fluctuations in velocity and cycle time. Such instabilities are often treated best in the context of simple one- or two-dimensional geometries. An understanding of the mechanisms of propagation and wave stability is leading to the implementation of different stimulation protocols in an effort to modify or eliminate abnormal rhythms. (c) 2002 American Institute of Physics.     

Calculation of the hyperfine spectrum for H2Ne,H2Ar,H2Kr dimers.

The weakly bound dimers H₂Ne, Ar, Kr are treated such that the H₂, rotation (quantum number j) remains unperturbed except for orientational effects. The orientation of the ortho H₂(j = 1) is mainly influenced by the anisotropic forces between the dimer constituents. We develop a method which allows to extract from a measured hyperfine dimer transition the value of a simple molecular parameter containing mainly the strength of the anisotropic interaction sandwiched between the dimer-stretch vibrational eigenfunctions. An analytic expression is derived permitting an easy comparison between measurements and results from simple model potentials. In addition, where necessary due to the existence of quasi-bound states, the influence of continuum states can be properly taken into account, by our method.     

The decay of140Pr to levels in140Ce

The decay of¹⁴⁰Pr was investigated by means of a Ge(Li) spectrometer. Excited states of¹⁴⁰Ce at 1,596.2, 1,903.1, 2,348.9, 2,522.5, 3,016.8 and 3,119.6 keV are fed in the beta decay of¹⁴⁰Pr. Spin and parity assignments for all observed levels have been made from electron capture and positon disintegration considerations and gamma branches. The experimental level scheme of¹⁴⁰Ce is compared with the results of shell model calculations forN=82 nuclei.     

On the method of Eilenberger for inhomogeneous superconductors

The theory of Eilenberger, modified to take into account the effect of the surface, is applied to the problem of the penetration of a weak magnetic field into a semiinfinite superconductor, and the standard result for the vector potential is derived by linearizing the Eilenberger equations. The dominant term in the asymptotic behaviour is argued to be monotonic for both large and small values of the Ginzburg-Landau parameterk _gl . ForT≠ 0, there is a small intermediate range of values ofk _gl for which the dominant term is oscillatory, but these oscillations are not related to those found by Eilenberger and Büttner in the isolated vortex problem for smallK _gl . From an analysis of these results, we conclude that the absence of the Eilenberger-Büttner oscillations in the field penetration problem cannot be used as an argument against their existence in other problems; in particular, a separate investigation is required for the isolated vortex problem.