966 resultados para Smith Ketchum, Milo S.


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Mode of access: Internet.

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Mode of access: Internet.

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Mode of access: Internet.

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Microfiche (negative). Louisville, Ky. : Lost Cause Press, 1979.--7 sheets ; 11 x 15 cm.--(New Cambridge bibliography of English literature ; group 16)

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"Three volumes complete in one."

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Tetratheca juncea Smith (Tremandraceae) has undergone a range contraction of approx. 50 km in the last 100 years and is now listed as a vulnerable sub-shrub restricted to the central and north coast regions of New South Wales, Australia. There are approx. 250 populations in a 110 km north-south distribution and populations are usually small with fewer than 50 plants/clumps. The reproductive ecology of the species was studied to determine why seed-set is reportedly rare. Flowers are bisexual, odourless and nectarless. Flowers are presented dependentally and there are eight stamens recurved around the pistil. Anthers are poricidal, contain viable pollen and basally contain a deep-red tapetal fluid that is slightly oily. Thus flowers are presented for buzz pollinators, although none were observed at flowers during our study. The species was found to be facultatively xenogamous with only one in 50 glasshouse flowers setting seed autogamously, i.e. without pollinator assistance. Field studies revealed fertile fruit in 24 populations but production varied significantly across sites from exceedingly low (0.6 fruits per plant clump) to low (17 fruits per plant clump). Fruit-set ranged from 0 to 65%, suggesting that pollen vectors exist or that autogamy levels in the field are variable and higher than glasshouse results. Fruit production did not vary with population size, although in three of the five populations in the south-west region more than twice as much fruit was produced as in populations elsewhere. A moderately strong relationship between foliage volume and fruit : flower ratios suggests that bigger plants may be more attractive than smaller plants to pollinators. A review of Tetratheca pollination ecology revealed that several species are poorly fecund and pollinators are rare. The habitat requirements for Tetratheca, a genus of many rare and threatened species, is discussed. (C) 2003 Annals of Botany Company.

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In Mesoamerica, tropical dry forest is a highly threatened habitat, and species endemic to this environment are under extreme pressure. The tree species, Lonchocarpus costaricensis is endemic to the dry northwest of Costa Rica and southwest Nicaragua. It is a locally important species but, as land has been cleared for agriculture, populations have experienced considerable reduction and fragmentation. To assess current levels and distribution of genetic diversity in the species, a combination of chloroplast-specific (cpDNA) and whole genome DNA markers (amplified fragment length polymorphism, AFLP) were used to fingerprint 121 individual trees in 6 populations. Two cpDNA haplotypes were identified, distributed among populations such that populations at the extremes of the distribution showed lowest diversity. A large number (487) of AFLP markers were obtained and indicated that diversity levels were highest in the two coastal populations (Cobano, Matapalo, H = 0.23, 0.28 respectively). Population differentiation was low overall, F-ST = 0.12, although Matapalo was strongly differentiated from all other populations (F-ST = 0.16-0.22), apart from Cobano (F., = 0.11). Spatial genetic structure was present in both datasets at different scales: cpDNA was structured at a range-wide distribution scale, whilst AFLP data revealed genetic neighbourhoods on a population scale. In general, the habitat degradation of recent times appears not to have yet impacted diversity levels in mature populations. However, although no data on seed or saplings were collected, it seems likely that reproductive mechanisms in the species will have been affected by land clearance. It is recommended that efforts should be made to conserve the extant genetic resource base and further research undertaken to investigate diversity levels in the progeny generation.

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Background Evaluation of anterior chamber depth (ACD) can potentially identify those patients at risk of angle-closure glaucoma. We aimed to: compare van Herick’s limbal chamber depth (LCDvh) grades with LCDorb grades calculated from the Orbscan anterior chamber angle values; determine Smiths technique ACD and compare to Orbscan ACD; and calculate a constant for Smiths technique using Orbscan ACD. Methods Eighty participants free from eye disease underwent LCDvh grading, Smiths technique ACD, and Orbscan anterior chamber angle and ACD measurement. Results LCDvh overestimated grades by a mean of 0.25 (coefficient of repeatability [CR] 1.59) compared to LCDorb. Smiths technique (constant 1.40 and 1.31) overestimated ACD by a mean of 0.33 mm (CR 0.82) and 0.12 mm (CR 0.79) respectively, compared to Orbscan. Using linear regression, we determined a constant of 1.22 for Smiths slit-length method. Conclusions Smiths technique (constant 1.31) provided an ACD that is closer to that found with Orbscan compared to a constant of 1.40 or LCDvh. Our findings also suggest that Smiths technique would produce values closer to that obtained with Orbscan by using a constant of 1.22.