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Stable carbon isotope ratios in prehistoric human bone collagen have been used extensively to document the introduction and intensification of maize horticulture in notheastern North America. Most previous studies are based on small samples of adults who are assumed to characterize the diet of the population. In this study, all 29 individuals buried within an Ontario Iroquoian village site dated A.D. 1530-1580 were analysed for stable isotopes of carbon and nitrogen. Age distribution of the sample ranges from preterm to elderly. Significant negative correlations between age and delta 13C, and age and delta 15N values were found. High delta 13C values in infants and young children (delta 13C = -6.8 to -12.3) suggest a weaning diet high in maize. High delta 15N values in infants relative to adults suggest a trophic level effect during breast-feeding which has been reported in a modern sample by Tuross et al. (Am. J. Phys. Anthropol., 1993). In addition to the isotopic evidence for extremely high carbohydrate (maize) intake, the MacPherson sample includes two juveniles aged 3-4 years, exhibiting circular caries. No other cases of this condition are known in the extensively studied southern Ontario skeletal collections. Together the evidence from dentition and stable carbon isotopes indicates a very high carbohydrate diet in subadults. Circular caries result from developmental stress during enamel formation with subsequent caries formation in areas of thinner enamel. These findings are relevant to studies of infant and early childhood morbidity and mortality among prehistoric maize horticulturists.

We present a visible-infrared sum-frequency spectroscopic technique that is capable of simultaneously determining the magnitude and phase of the sample response from a single set of experimental conditions. This is especially valuable in cases where the phase stability is high, as in collinear beam geometries, as it enables multiple experiments to be performed without re-measuring the local oscillator phase or the reference phase. After illustrating the phase stability achievable with such a geometry, we provide a technique for quantitatively determining the magnitude and phase from a single set of two-dimensional spectral-temporal interference fringes. A complete demonstration is provided for the C-H stretching frequency region at the surface of an octadecyltricholosilane film.

The crystal structure of the title compounds [Cu(bipy)(C204)]-2H20 (1) and [Cu(bipy)(C204) (OH2)].2H20 (2) have been determined by X-ray analysis. Compound (1) crystallises in the triclinic space group P i with a = 9.673(3), b = 8.940(3), c = 9.103(3) A, a = 105.718(3), p = 110.347(3), y = 97.539(3)', and2 = 2. The six-co-ordinate C U N ~O ~O ' ~ chromophore of (1 ) involvesan elongated rhombic octahedralstereochemistryinvolving a symmetrically co-ordinated bipy ligand (mean CU-N 2.007 A) and unsymmetrically co-ordinated bridging oxalate groups (mean Cu-0 1.988 and 2.320 A). Compound (2) crystallises in the triclinic space group Pi with a = 10.565(3), b = 7.246(3), c = 10.806(3) A, a = 102.467(3), p = 62.119(3), y = 98.134(3)", and 2 = 2. TheCuN2020' chromophore of (2) is basically square pyramidal with a symmetrically co-ordinated bipy ligand (mean CU-N 1.989 A), and a symmetrically co-ordinated oxalate group (mean Cu-0 1.953 A) in the plane of the square pyramid, and a water molecule at 2.341 A out of the plane. The electronic reflectance spectrum of (1) involves a main band at 14 500 cm-' with a resolved broad band at 9 300 cm-l, while that of (2) involves a single broad band at 15 600 cm-I, a difference that is consistent with the structures and suggests an ' electronic criterion of stereochemistry ' to distinguish these two structures.

Summary:Person to person spread of leptospirosis has not been previously reported. We describe two cases occurring in a man and wife which tantalisingly raise this possibility.

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MXBA)] [C104]2 and [Cu2(MXPNB)][C104]2 complexes,respectively. Steric factors may also be important in these displacement reactions, since accommodation of imidazole rings within the copper coordination spheres may cause excessive crowding with the various phenyl residues of the ligands.In conclusion, the present investigation shows that by proper choice of the residues to be conjugated with the xylyl frame I it is possible to obtain stable binuclear copper(I) complexes with nitrogen donor ligands. The metal centers of these systems can come in close proximity by proper conformational arrangement of the flexible xylyl side chains,13b,14b,d though in the absence of structural determinations, only magnetic studies on the copper(II) analogues can give an estimate of the metal-metal interaction. Binding of the various functional groups of the ligand to copper(I) can, however, be conveniently deduced by careful examination of their IR and NMR spectra.Besides the donor groups of the ligands, the binuclear copper(I) complexes described here have other coordination sites available. These can be filled by solvent molecules or binding to external ligands such as carbon monoxide or imidazole. This is an important requisite in model studies based on binuclear copper(I) systems such as those derived from I, where small differences in structure or donor set can produce significant changes in reactivity.

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