Development of an Arcellacean (testate lobose amoebae) based transfer function for sedimentary phosphorous in lakes.

Arcellacea (testate lobose amoebae) communities were assessed from 73 sediment-water interface samples collected from 33 lakes in urban and rural settings within the Greater Toronto Area (GTA), Ontario, Canada, as well as from forested control areas in the Lake Simcoe area, Algonquin Park and eastern Ontario. The results were used to: (1) develop a statistically rigorous arcellacean-based training set for sedimentary phosphorus (Olsen P (OP)) loading; and (2) derive a transfer function to reconstruct OP levels during the post-European settlement era (AD1870s onward) using a chronologically well-constrained core from Haynes Lake on the environmentally sensitive Oak Ridges Moraine, within the GTA. Ordination analysis indicated that OP most influenced arcellacean assemblages, explaining 6.5% (p < 0.005) of total variance. An improved training set where the influence of other important environmental variables (e.g. total organic carbon, total nitrogen, Mg) was reduced, comprised 40 samples from 31 lakes, and was used to construct a transfer function for lacustrine arcellaceans for sedimentary phosphorus (Olsen P) using tolerance downweighted weighted averaging (WA-Tol) with inverse deshrinking (RMSEPjack-77pp; r2jack = 0.68). The inferred reconstruction indicates that OP levels remained near pre-settlement background levels from settlement in the late AD 1970s through to the early AD 1970s. Since OP runoff from both forests and pasture is minimal, early agricultural land use within the lake catchment was as most likely pasture and/or was used to grow perennial crops such as Timothy-grass for hay. A significant increase in inferred OP concentration beginning ~ AD 1972 may have been related to a change in crops (e.g. corn production) in the catchment resulting in more runoff, and the introduction of chemical fertilizers. A dramatic decline in OP after ~ AD 1985 probably corresponds to a reduction in chemical fertilizer use related to advances in agronomy, which permitted a more precise control over required fertilizer application. Another significant increase in OP levels after ~ AD 1995 may have been related to the construction of a large golf course upslope and immediately to the north of Haynes Lake in AD 1993, where significant fertilizer use is required to maintain the fairways. These results demonstrate that arcellaceans have great potential for reconstructing lake water geochemistry and will complement other proxies (e.g. diatoms) in paleolimnological research.

Persistent and consistent poverty in the 1994 and 1995 waves of the European Community Household Panel Survey

This paper focuses on the mismatch between income and deprivation measures of poverty. Using the first two waves of the European Community Household Panel Survey, a measure of relative deprivation is constructed and the overlap between the relative income poor and relatively deprived is examined, There is very limited overlap with the lowest relative income threshold. The overlap increases as the income threshold is raised, but it remains true that less than half those below the 60 percent relative income line are among the most deprived. Relative deprivation is shown to be related to the persistence of income poverty, but also to a range of other resource and need factors. Income and deprivation measures each contain information that can profitably be employed to enhance our understanding of poverty and a range of other social phenomena. This is illustrated by the manner in which both income poverty and relative deprivation are associated with self-reported difficulty making ends meet.

Indications for penetrating keratoplasty and associated procedures, 1989-1995

Purpose. To identify changing trends in indications for penetrating keratoplasty and associated surgical procedures. Methods. Review of charts from all patients who underwent penetrating keratoplasty at Wills Eye Hospital from January 1, 1989 through December 31, 1995. Results. A total of 2,442 corneal transplants were performed in 2,186 patients. The leading indication for penetrating keratoplasty was pseudophakic corneal edema, accounting for 634 cases (26.0%); 54.7% of them were associated with anterior chamber intraocular lenses, 36.4% with posterior chamber intraocular lenses, and 3.1% with iris-fixated intraocular lenses. Regraft (17.8%), Fuchs' dystrophy (15.7%), and keratoconus (13.2%) followed pseudophakic corneal edema in frequency. Cataract extraction, with or without intraocular lens implantation, was combined with penetrating keratoplasty in 439 cases of 1,264 phakic eyes (34.7%). Intraocular lens exchange was performed in 285 of the 634 cases of pseudophakic cornea edema (44.9%). Conclusion. Pseudophakic corneal edema was the leading indication for penetrating keratoplasty, with an increasing number of cases associated with posterior chamber intraocular lenses during the study period (p = 0.001). The number of regrafts steadily increased between 1989 and 1995 (p = 0.001), being the second most common indication for corneal transplantation since 1992.

Ultrastructure of head organs (anterior adhesive apparatus) and posterior secretory systems of Caballeria liewi Lim, 1995 (Monogenea, Ancyrocephalidae)

Caballeria liewi Lim, 1995, uses adhesive secretions from the head organs and posterior secretory systems to assist in locomotion and attachment. Ultrastructural investigations show that the head organs of C. liewi consist of three pairs of antero-lateral pit-like openings bearing microvilli and ducts leading from two types of uninucleated gland cells (located lateral to the pharynx), one type producing rod-like (S1) bodies with an electron-dense matrix containing less electron-dense vesicles and the second type producing oval (S2) bodies with a homogeneous electron-dense matrix. Interlinking band-like structures are observed between S1 bodies and between S2 bodies. S1 body is synthesised in the granular endoplasmic reticulum, transported to a Golgi complex to be packaged into vesicles and routed into ducts for exudation. The synthesis of the S2 body is unresolved. Haptoral secretions manifested externally as net-like structures are derived from dual electron-dense (DED) secretory body produced in the peduncular gland cells. The DED body consists of a less electron-dense oval core in a homogeneous electron-dense matrix. On exocytosis into the pyriform haptoral reservoir, DED bodies are transformed into a secretion with two types of inclusions (less electron-dense oval and electron-dense spherical inclusions) in an electron-dense matrix. The secretions are further transformed (as small, oval, electron-dense bodies) when transported to the superficial anchor grooves, and on exudation into the gill tissues, the secretions become an electron-dense matrix. Secretory bodies associated with uniciliated structures, anchor sleeves and marginal hooks are also observed.