bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationships within Eucalyptus using chloroplast DNA
Authors: Sale MM , Potts BM , West AK , Reid JB
Published: April 2005

The potential use of restriction fragment length polymorphisms (RFLPs) of chloroplast DNA to determine relationships at higher taxonomic levels in the genus Eucalptus was examined. Chloroplast DNA from 24 species, encompassing representatives of all the subgenera of Eucalyptus as well as one representative of the genus Angophora, was analysed using four 6-base restriction endonucleases. Eighty-four polymorphisms were obtained (twenty-eight autopomorphic) and the data matrix analysed using both cladistic and phenetic approaches. Results provided relatively good congruence with taxonomic perceptions based on morphological traits. Eucalyptus subgenera Blakella and Corymbia appear to be genetically similar to each other and to Angophora, although their phylogenetic relationships are not resolved in this study. Using Angophora alone, or together with the bloodwoods Blakella and Corynthia, as the outgroup for cladistic analysis, the two representatives of Eudesmia examined form a distinctly separate monophyletic group, which appears to be the sister taxon to Idiogenes, Gaubaen, Monocalyptus and Symphyomyrtus. The results provide some support for the close association of Idiogenes, Gauhaea and Monocalyptus and the hypothesis that they are the sister group of Symphyomyrtus. Taxonomically problematic species Eucalyptus guilfoylei, E. microcorys and E. deglupta were included in the study and it was found that E. guilfoylei appeared to diverge prior to the rest of the Symphyomyrtus, E. microcorys near the root of this clade, while the Telocalyptus representative E. deglupta fell within Symplgvontyrtus. The results obtained from the chloroplast DNA data provided independent support for previous morphological studies while generating new hypotheses and highlighting areas requiring closer examination.
Tropical Australian freshwater fungi. V.* Bombardia sp., Jahnula australiensis sp. nov., Savoryella aquatica sp. nov. and S. lignicola sp. nov.
Authors: Hyde KD
Published: April 2005

Four aquatic ascomycetes are reported from freshwater habitats in Australia for the first time. Three taxa: Bombardia sp., Jahnula australiensis sp. nov., and Savoryella aquatica sp. nov, are illustrated with interference contrast light micrographs. The new fungi are described and their taxonomic placement discussed.* Part IV, Aust. Syst. Bot. 1992, 5, 407–14.
Notes on Strychnos L. (Loganiaceae) in Australia
Authors: Conn BJ , Broen EA
Published: April 2005

Four species of Strychnos are recognised for Australia (S. arboren, S. lucida, S. minor and S. psilosperma). The South-east Asian species, Strychnos axillaris is excluded from Australia, being regarded as extending no further south than New Guinea. A key to the Australian species, together with descriptions, distributional, habitat. and other notes are provided.
Two New Species of Brachyscome (Asteraceae: Astereae) from Eastern Australia
Authors: Short PS , Watanabe K
Published: April 2005

Two new species of Brachyscome Cass. (Asteraceae: Astereae), B. nodosa and B. smithwhitei, from eastern Australia are described and illustrated and notes on their relationships are provided.
Taxonomic Relationships and Status of the Genus Dorystephania (Asclepiadaceae: Marsdenieae) from the Phillipines and Borneo
Authors: Forster PI
Published: April 2005

The taxonomic history and relationships of the genus Dorystephania Warb. (Asclepiadaceae) with two species from Bomeo and the Philippines respectively, are reviewed. It is concluded that Dorystephania belongs in the Marsdenieae and is congeneric with Sarcolobus R. Br. The new combinations Sarcolobus luzonensis (D. luzonensis Warb.) and S. borneensis (D. borneensis Steen.) are made. Both species are described in detail and S. borneensis is lectotypified. Regional keys to Sarcolobus in the Philippines and Borneo are provided.
The Oligocene Berwick Quarry Flora — Rainforest in a Drying Environment
Authors: Pole MS , Hill RS , Green N , Macphail MK
Published: April 2005

The Late Oligocene to possibly earliest Early Miocene Benvick Quany macrofossil flora was first described very early in this century by Henry Deane, but has since been largely ignored. Recent work at the quarry has led to major new collections and a reinvestigation of the flora. Seventeen taxa of macrofossils have been recovered, including Agathis, Dacrycarpus, four species of Lauraceae, Gymnostoma, Nothofagus, Eucalyptus, an indeterminate Myrtaceae and Proteaceae, three possible Cunoniaceae, and six unidentified taxa. Fagus maideni Deane is formally transferred to Nothofagus Blume. Nothofagus johnstoni Hill, Fagus luemanni Deane, and Atherosperma berwickense Deane, are considered to be junior synonyms of the species N. maideni (Deane) comb. nov. Only one of the seven fossil species of Eucalyptus established by Deane can be recognised in our material: E kitsoni Deane. His Lomatia species are probably Cunoniaceae. The Berwick Quarry flora contains species which are consistent with rainforest in the region, however, the flora is also notable for the presence of leaves of Eucalyptus, leaving little doubt that the flora at Berwick Quarry represents a mixture of rainforest and open forest taxa. The vegetation was probably a mosaic of open and closed forest, representing some of the earliest evidence for seasonality in Australia during the development of the modem flora. Palynological samples are dominated by Nothofagus subgenus Brassospora and Fuscospora.
The Palaeovegetation of the Murray Basin, Late Eocene to Mid-Miocene
Authors: Martin HA
Published: April 2005

The principles of pollen dispersal and deposition show that the pollen spectrum is produced by the plants of the locality, with a little transported in from long distances. The 'locality' has a radius of no more than 500 m, and it could be much less. Adherence to these principles has allowed a detailed reconstruction of the palaeovegetation. Nothofagus grew throughout the Murray Basin, probably on the dry ground in the flood plain complex. Occasionally it was dominant, but most of the forests were mixed. The fusca-type flourished on well drained sites, especially in the north-east. The menziesii-type became prominent in the mid-Miocene, when the climate was becoming drier. The brassii-type was probably the only type in the deeper, swampier parts of the basin. Gymnosperms were intimately connected with the semi-swamp forest. Araucariaceae–Casuarinaceae forests formed a coastal zone around the Miocene marine incursion. Herbaceous fresh water swamps were found in the north-west, where they formed disjuncts from the swampy margin of Lake Frome. Myrtaceae was found throughout, sometimes abundantly, but eucalypts were rare. Geographic variation, changes through time and forest dynamics, including possibly one very rare modification after burning, are detailed.
An account of Southern Australian Species of Mesophyllum (Corallinaceae, Rhodophyta)
Authors: Woelkerling WJ , Harvey A
Published: April 2005

Mesophyllum (Corallinaceae, Rhodophyta) is represented in southern Australia by at least four species. M. engelhartii and M. incisum have been reported from the region previously, M. macroblastum is newly recorded, and M. printzianum is newly described. Detailed accounts are provided for each species along with information on etymology, nomenclature and synonymy, collections examined, infraspecific taxonomy, and distribution, seasonality and habitat. Comparisons of southern Australian species with the type species of Mesophyllum, M. lichenoides, also are included. Of the nine additional entities that have been recorded from southern Australia under the generic name Mesophyllum, three (M. fumigatum, M. lemniscatum, M. versicolor) are considered heterotypic synonyms of M. engelhartii, three are referable to other genera of Corallinaceae (M. gabrielii to Lithothamnion; M. patena to Synarthrophyton; M. rupestre to Hydrolithon), two (M. lichenoides, M. neglectum) are based on misidentifications or questionable records, and one (M. squamuliforme) is treated as a species of uncertain status. Southern Australian specimens previously referred to Clathromorphum have been found to belong to Mesophyllum. As a prelude to the taxonomic accounts, a short historical introduction is provided along with a brief consideration of general morphological and anatomical features of Mesophyllum and a detailed analysis of characters that have been or could be used to delimit species within the genus. None of the at least 26 characters used by previous authors or the 34 quantitative characters examined during the present study were found to be of diagnostic value. By contrast, qualitative characters associated with tetrasporangial / bisporangial conceptacle roof morphology and anatomy have provided a reliable basis for delimiting the four southern Australian species from one another and from the type species of the genus, M. lichenoides. Concluding remarks, acknowledgments and references follow the taxonomic accounts.
Nucleotide sequences of rbcL confirm the capparalean affinity of the Australian endemis Gyrostemonaceae
Authors: Rodman JE , Karol KG , PRice RA , Conti E , Systma KJ
Published: April 2005

Nucleotide sequences (1452 base pairs) from the chloroplast gene for the large subunit of ribulose-1, 5-bisphosphate carboxylase/oxygenase (rbcL) were obtained for three species of Gyrostemon and Tersonia of the Australian endemic family Gyrostemonaceae. Phylogenetic reconstruction based on parsimony robustly allies the family with other mustard oil-producing plants in Dahlgren's expanded order Capparales. Within this clade, Gyrostemonaceae are the sister group to Resedaceae, but the sequence data provide only weak support for this particular linkage. The new molecular data corroborate recent embryological and ultrastructural findings for Gyrosternonaceae and confirm results from Rodman's cladistic analysis of traditional morphological features of these plants. The rbcL sequences for the three species of Gyrostemonaceae were consistent in possessing a stop codon ending at position 1452, well beyond the usual 1428 site for many dicots. An extended terminus for the rbcL gene appears to be a marker within the expanded order Capparales for a derived clade that comprises the traditional core Capparales (Brassicaceae, Capparaceae, Resedaceae and Tovariaceae) plus Gyrostemonaceae, the sister taxa Batis + Koeberlinia, and Limnanthaceae.
The genus Lagenocypsela (Asteraceae, Astereae) in New Guinea
Authors: Swenson U , Bremer K
Published: April 2005

The new genus Lugenocypsela Swenson & K. Bremer is described. The genus comprises two species, with the new combinations Lagenocypsela latifolia (Mattf.) Swenson & K. Bremer, based on Ischnea latifolia Mattf., and Lugenocypsela papuana (J. Kost.) Swenson & K. Bremer, based on Rhamphogyne papuana J. Kost. A key, descriptions, illustrations and distribution maps to both species are included.
A taxonomic revision of Tylophora (Asclepiadaceae: Marsdenieae) in Papuasia*
Authors: Forster PI
Published: April 2005

The genus Tylophora R.Br. is revised for Papuasia (Irian Jaya, Papua New Guinea, Solomon Islands). Seven species are recognised, T. bilobata sp. nov., T. brassii sp. nov., T. cissoides Blume, T. flexuosa R.Br., T. glabriflora (Warb.) K.Schum., T. hellwigii Warb. and T. minima sp. nov., with a key to distinguish them. A neotype is selected for T. glabriflora. T. kenejiana Schltr. is reduced to synonymy under T. cissoides. Asclepias tetrapetala Dennst., Asclepias tenuissima Roxb. ex Schult., T. tenuis Blume. T. cuspidata Zipp. ex Decne. and T. polyantha Volkens are reduced to synonymy under T. flexuosa.*Christensen Research Institute Contribution No. 116.
A mangrove hybrid Sonneratia xurama (Sonneratiaceae) from northern Australia and southern New Guinea
Authors: Duke NC
Published: April 2005

The putative hybrid tree taxon, Sonneratia alba x S. lanceolata, previously reported for two incomplete herbarium specimens from northern Australia and south-east West Irian, has since been observed and collected in mangrove forests of southern Papua New Guinea. It is morphologically uniform and is described as S. xurama. Notes on its floral phenology, distribution and ecology are given, including a key to all major Sonneratia taxa in this region.
A morphometric analysis of Eucalyptus urophylla and related taxa with descriptions of two new species
Authors: Pryor LD , Williams ER , Gunn BV
Published: April 2005

Over 400 specimens from 26 locations, mainly in the Lesser Sunda Islands and some from New Guinea and northern Cape York, were examined. These were representative of an array of forms ordinarily assigned to Eucalyptus urophylla, E. pellita and an undescribed species as well as those considered by some to be hybrid between E. alba and E. urophylla. The latter has long been considered to show considerable polymorphism. Re-examination of the available material and records suggest that interspecific hybridisation is not significantly involved in this variability. Although this examination pointed to the existence of some differentiation at the level of species in this array, there was still a core of material which could not be separated readily into subgroups. Measurements were taken of selected floral and foliar morphological features which were then subject to statistical analysis to ascertain if subgroups were discernible on this basis. As a result, the separation of two species, Eucalyptus orophila sp. nov. and Eucalyptus wetarensis sp. nov. from Eucalyptus urophylla sensu lato in the Lesser Sunda Islands, is supported. The related populations called species A by Pinyopusarerk et al. (1993), from New Guinea and northern Cape York, were to a somewhat lesser extent separated on these criteria. These results were paralleled by evidence from seedling morphology and oil characteristics. Isozyme analysis gave a similar grouping for the material from Wetar, but did not indicate other separations from the core E. urophylla.
Revision of Brachysema (Fabaceae: Mirbelieae)
Authors: Crisp MD
Published: April 2005

Brachysema is revised for the first time since Bentham's (1864) treatment in Flora Australiensis last century . In the meantime. B . sect . Leptosema has been segregated as a genus. and Brachysema as circumscribed more narrowly here includes 10 species. three of which are new . A new phylogenetic analysis of the species is used as a basis for dividing the genus into two sections . Taxa described as new are Brachysema minor. B. modestum. B. papilio and B. sect . Gastrocalyx. Cupulanthus is reduced to a taxonomic synonym of Brachysema . In addition. some names are reinstated to conform with the rules of nomenclature (B. celsianum). as a result of changes in genera (B. bracteolosum), and due to change in rank (B. melanopetalum).
Three new species of Millerocaulis (Osmundaceae) from Queensland, Australia
Authors: Tidwell WD , Clifford HT
Published: April 2005

Three new species of Millerocaulis Erasmus ex Tidwell emend. Tidwell, M. juundahensis, M. donponii, and M. limewoodensis, are described from the Middle Jurassic Birkhead Formation at 'Cattle Downs' north-west of Wandoan and near 'Limewood' Station, north-east of Orallo in Queensland, Australia. Their xylem cylinders essentially lack leaf gaps as do those of Millerocaulis dunlopii from New Zealand, M. indica from India, M. indentata from Tasmania, and M. chubutensis from Argentina with which the new species are compared.
A new species of Phloeosporella (Deuteromycotina) on leaves of Cassia oligoclada from central Australia
Authors: Yuan Ziqing , Old KM
Published: April 2005

Phloeosporella cassiae sp. nov., which causes leaf spot in Cassia oligoclada is described and illustrated. The differences between the new species and the known species of the genus, as well as other similar fungi recorded on Cassia are discussed.
Biogeography of palawan mosses
Authors: Tan BC
Published: April 2005

The moss flora of Palawan was updated and consists of 192 species in 88 genera. Because of the dry, semi-deciduous forest, Palawan has a relatively depauperate moss flora compared with the flora of moist forest on other islands of similar area. The number of species is higher in riverine forest than in inland forest, and highest at mid-mountain elevation. Its flora is mainly an extension of the Philippine moss flora, showing little influence from Borneo. Likewise, its floristic affinity is with the moss floras of the Philippine archipelago, Java, and Lesser Sundas, but not with the Bornean moss flora. Additionally, the role of Palawan Island as a refugium for the survival of a past, xeric moss flora in South-East Asia is discussed on the basis of evidence from moss distribution. Clastobryum asperrimum (Dix.) Tan was proposed as a new combination and Leucoloma mittenii Heisch. was considered to be a new synonym of L. walkeri Broth.
Biodiversity of microfungi in north Queensland
Authors: Hyde KD
Published: April 2005

Whereas about 85% of Australian higher plants are either named or known, as few as 5–10% of fungi are named or known. This is compounded by the fact that there are few taxonomic mycologists (32 working on up to 250 000 species of fungi) compared with higher plant taxonomists (e.g. 25 taxonomists working on 600 Eucalyptus sp.). Part of the reason for this is related to the size of the plants. Microfungi can only be seen with a microscope and are often overlooked. Fungi from three habitats are discussed: rainforests, freshwater streams and mangroves. Important reasons for research into these fungi are reported.
Phylogenetic reconstruction in Myrtaceae using matK, with particular reference to the position of Psiloxylon and Heteropyxis
Authors: Gadek PA , Wilson PG , Quinn CJ
Published: April 2005

Parsimony analysis of matK sequence data for representatives of Myrtaceae s.1. provides evidence of its potential in phylogenetic inference in this family. Psiloxylon and Heteropyxis comprise a robust clade, basal to representatives of Myrtaceae s. str., and strongly clustered with it. In a limited sample of Myitaceae s. str., several strongly supported groups are identified: the myrtoid genera (excluding Syzygium), representatives of the Chamelaucium alliance, and the Chamelaucium plus Leptospennum alliances.
Reassessment of Cyathodes (Epacridaceae)
Authors: Weiller CM
Published: April 2005

Examination of the 20 species currently included in Cyathodes Labill. has shown a number of distinct species groups that warrant recognition at generic level. Accordingly, Cyathodes Labill. s. str, is restricted to three species endemic to Tasmania, including one new species, C. platystoma C.M.Weiller, which is described below.
A cladistic analysis of Banksia (Proteaceae)
Authors: Thiele K , Ladiges PY
Published: April 2005

Banksia is a genus of more than 90 taxa, many of which are common and characteristic in sclerophyll communities in eastern and south-western Australia. Cladistic analyses based on morphological and anatomical characters were used to resolve relationships in the genus. An initial analysis of 35 terminal taxa, including 9 infrageneric taxa assumed to be monophyletic on the basis of one or more synapomorphies, allowed resolution of basal nodes. Subsequent analyses of the putatively monophyletic infrageneric taxa allowed resolution of distal nodes. Some of these lower-level analyses used a mixture of qualitative characters and coded morphometric characters. Together, the analyses afforded a high degree of resolution within the genus, although relationships of some taxa were not well supported. A new infrageneric classification, in which Banksia is divided into 2 subgenera, 12 series and 11 subseries, is proposed. The classification is broadly similar to previously published classifications of the genus, but discards a number of taxa shown to be para- or poly-phyletic. The following new names are published: Banksia series Lindleyanae K.Thiele, series Ochraceae K.Thiele, subseries Leptophyllae K.Thiele, subseries Longistyles K.Thiele, subseries Nutantes K.Thiele, subseries Sphaerocarpae K.Thiele, subseries Cratistyles K.Thiele, subseries Acclives K.Thiele, subseries Integrifoliae K.Thiele, subseries Ericifoliae K.Thiele, subseries Occidentales K.Thiele and subseries Spinulosae K.Thiele. New combinations are provided for Banksia penicillata (A.S.George) K.Thiele, B. brevidentata (A.S.George) K.Thiele, B. hiemalis (A.S.George) K.Thiele and B. dolichostyla (A.S.George) K.Thiele.
A new species of Fitzroya (Cupressaceae) from oligocene sediments in north-western Tasmania
Authors: Hill RS , Whang SS
Published: April 2005

Vegetative twigs from Oligocene sediments in north-western Tasmania are assigned to a new fossil species of Fitzroya, F. tasmanensis. These twigs differ from extant F. cupressoides in leaf shape and stomatal orientation and morphology. This is the first fossil record of Fitzroya from outside the current range of the genus (South America). Previous fossil records of Fitzroya from South America are almost certainly erroneous. These fossils occur in sediments with leaves and cupules of Nothofagus subgenus Nothofagus, which is also restricted to South America today. This suggests that some current plant associations in southern South America provide good analogues for vegetation in Oligocene Tasmania.
Architectural and synaptic mechanisms underlying coherent spontaneous activity in V1
Authors: Cai David , Rangan Aaditya V. , McLaughlin David W.
Published: April 2005

To investigate the existence and the characteristics of possible cortical operating points of the primary visual cortex, as manifested by the coherent spontaneous ongoing activity revealed by real-time optical imaging based on voltage-sensitive dyes, we studied numerically a very large-scale (≈5 × 10
5
) conductance-based, integrate-and-fire neuronal network model of an ≈16-mm
2
patch of 64 orientation hypercolumns, which incorporates both isotropic local couplings and lateral orientation-specific long-range connections with a slow NMDA component. A dynamic scenario of an intermittent desuppressed state (IDS) is identified in the computational model, which is a dynamic state of (
i
) high conductance, (
ii
) strong inhibition, and (
iii
) large fluctuations that arise from intermittent spiking events that are strongly correlated in time as well as in orientation domains, with the correlation time of the fluctuations controlled by the NMDA decay time scale. Our simulation results demonstrate that the IDS state captures numerically many aspects of experimental observation related to spontaneous ongoing activity, and the specific network mechanism of the IDS may suggest cortical mechanisms and the cortical operating point underlying observed spontaneous activity.
Macrofilaricidal and microfilaricidal effects of Neurolaena lobata, a Guatemalan medicinal plant, on Brugia pahangi
Authors: Fujimaki Y. , Kamachi T. , Yanagi T. , Cáceres A. , Maki J. , Aoki Y.
Published: April 2005

Twelve extracts of 11 Guatemalan medicinal plants were initially screened in vitro for potential macrofilaricidal activity against Brugia pahangi, a lymphatic dwelling filarial worm, using concentrations from 125 to 1000 μg ml−1 of each extract that could be dissolved in the culture medium. Of 12 extracts used, the ethanol extract of leaves of Neurolaena lobata showed the strongest activity against the motility of adult worms. Subsequently, the extract of N. lobata was extensively examined in vitro for macro- and micro-filaricidal effects using a series of concentrations of 500, 250, 100, 50 and 10 μg ml−1. The effects were assessed by worm motility, microfilarial release by female worms and a MTT assay. The effect on the motility of adult worms was observed in a concentration- and time-dependent manner. The time required to stop motility of both sexes of adult worms was 6 h at 500 μg ml−1, 24 h at 250 μg ml−1, and 3 days for females and 4 days for males at 100 μg ml−1. The movement of females ceased at 4 days at a concentration of 50 μg ml−1 whereas the motility of males was only reduced. The loss of worm's viability was confirmed by the MTT assay and was similar to the motility results. These concentrations, including 10 μg ml−1, prevented microfilarial release by females in a concentration- and time-dependent manner. Concentrations higher than 100 μg ml−1 even induced mortality of the microfilariae. The present study suggested that the ethanol extract of Neurolaena lobata has potential macro- and micro-filaricidal activities.
Life history constraints on the evolution of abbreviated life cycles in parasitic trematodes
Authors: Lefebvre F. , Poulin R.
Published: April 2005

Abbreviations of the complex life cycle of trematodes, from three to two hosts, have occurred repeatedly and independently among trematode lineages. This is usually facultative and achieved via progenesis: following encystment in the second intermediate host, the metacercaria develops precociously into an egg-producing adult, bypassing the need to reach a definitive host. Given that it provides relatively cheap insurance against a shortage of definitive hosts, it is not clear why facultative progenesis has only evolved in a few taxa. Here a comparative approach is used to test whether progenetic trematodes are characterized by larger body size and egg volumes, two traits that correlate with other key life history features, than other trematodes. These traits may constrain the evolution of progenesis, because precocious maturation might be impossible when the size difference between the metacercaria and a reproductive adult is too large. First, trematode species belonging to genera in which progenesis has been documented were found not to differ significantly from other trematode species. Second, using within-genus paired comparisons across 19 genera in which progenesis has been reported, progenetic species did not differ, with respect to body size or egg size, from their non-progenetic congeners. Third, using intraspecific paired comparisons in species where progenesis is facultative, no difference was observed in the sizes of eggs produced by worms in both the intermediate and definitive host, suggesting that opting for progenesis does not influence the size of a worm's eggs. Overall, the lack of obvious differences in body or egg size between trematodes with truncated life cycles and those with the normal three-host cycle indicates that basic life history characteristics are not acting as constraints on the evolution of progenesis; trematodes of all sizes can do it. Why facultative progenesis is not more widespread remains a mystery.
Support for Integration: Élite or Mass‐Driven?
Authors: Wessels Bernhard
Published: April 2005

The general question addressed in this chapter is whether or not support for the European Community among the mass public is generated by elite action. More precisely, it asks whether opinion flow and opinion formation concerning the EC function according to the cascade model proposed by Deutsch. Its empirical findings provide evidence for a cascade model by showing that the development of support is more congruent between opinion leaders and the highly attentive publics than between opinion leaders and the less attentive strata of society. In the second stage of the analysis, the chapter employs a dynamic model to show that generating support for the EC follows the logic of the normal political process, with stages of articulation, aggregation, and output.
Measuring and Optimizing Portfolio Credit Risk: A Copula‐based Approach*
Authors: Di Clemente Annalisa , Romano Claudio
Published: April 2005

In this work, we present a methodology for measuring and optimizing the credit risk of a loan portfolio taking into account the non‐normality of the credit loss distribution. In particular, we aim at modelling accurately joint default events for credit assets. In order to achieve this goal, we build the loss distribution of the loan portfolio by Monte Carlo simulation. The times until default of each obligor in portfolio are simulated following a copula‐based approach. In particular, we study four different types of dependence structure for the credit assets in portfolio: the Gaussian copula, the Student's t‐copula, the grouped t‐copula and the Clayton n‐copula (or Cook–Johnson copula). Our aim is to assess the impact of each type of copula on the value of different portfolio risk measures, such as expected loss, maximum loss, credit value at risk and expected shortfall. In addition, we want to verify whether and how the optimal portfolio composition may change utilizing various types of copula for describing the default dependence structure. In order to optimize portfolio credit risk, we minimize the conditional value at risk, a risk measure both relevant and tractable, by solving a simple linear programming problem subject to the traditional constraints of balance, portfolio expected return and trading. The outcomes, in terms of optimal portfolio compositions, obtained assuming different default dependence structures are compared with each other. The solution of the risk minimization problem may suggest us how to restructure the inefficient loan portfolios in order to obtain their best risk/return profile. In the absence of a developed secondary market for loans, we may follow the investment strategies indicated by the solution vector by utilizing credit default swaps.
Intraspecific variation in the external morphology of the sand skate
Authors: Braccini J. M. , Chiaramonte G. E.
Published: April 2005

In male sand skate Psammobatis extenta, from the commercial fishery of Puerto Quequén, Argentina, six of 13 proportional dimensions analysed were constant (isometric) with total length, while seven proportions remained constant in females. The nature of the allometric and isometric relationships of disc length, disc width, interspiracular distance and interorbital distance did not vary between the sexes, and no sexual dimorphism occurred between these morphometric dimensions. A stepwise discriminant function analysis separated the sexes and was able to correctly classify 90·8% of the original grouped cases. The variables that best discriminated between sexes were prenasal length, distance from the cloaca to caudal fin tip, and distance from the snout to cloaca. The study also revealed that several of the meristic characters studied showed much intraspecific variation and, therefore, should be used with caution in taxonomic studies.
Social enhancement and social inhibition of foraging behaviour in hatchery‐reared Atlantic salmon
Authors: Brown C. , Laland K.
Published: April 2005

The results of two experiments showed that observation of a trained conspecific Atlantic salmon Salmo salar significantly increased the rate at which naïve hatchery‐reared fish accepted novel, live prey items, whereas the presence of an untrained conspecific actually decreased learning rates due to social inhibition. Pre‐release training involving exposure of hatchery‐reared fish to live prey items in the presence of pre‐trained demonstrators would result in a significant enhancement in their foraging success on release and help prevent starvation, which is thought to be one of the principal causes of post‐release mortality in hatchery‐reared fishes.
Maturation of walleye by age, size and surplus energy
Authors: Henderson B. A. , Morgan G. E.
Published: April 2005

The probability of annual sexual maturation by male and female walleye Stizostedion vitreum was related to age, size and an index of condition, IVF=[arcsine(visceral fat)0·5(body mass)−0·5]. Most males first matured at ages 2 and 3 years; size explained first maturation, but condition explained later maturation. In contrast, most females first matured at ages 4 and 5 years; maturity of females was more dependent upon condition. Maturity of females at ages 4 and 5 years was significantly correlated with average IVF of the population (PIVF). The size reached by age 2 years (early growth) was correlated with the PIVF. Growing degree‐days, Secchi depth, latitude and lake morphology were not correlated with the PIVF. Annual variations in female spawning stock size were related to the condition of the females, presumably reflecting the net acquisition of energy in the preceding growing season. Annual variations within lakes in the net acquisition of energy may exceed the variations in energy availability between lakes, dictated by lake morphology and geography. Thus, assessment of condition could be used to predict annual potential spawning stock size and egg production.
Kinetic and Thermodynamic Analyses of Chemical Vapor Deposition of Aluminum Nitride
Authors: Lee Woo Y. , Lackey W. J. , Agrawal P. K.
Published: April 2005

AIN coatings were prepared by chemical vapor deposition from the AlCl3—NH3—Ar reagent system using an impinging jet reactor in the temperature range of 700° to 1100°C. A mass transfer model and thermodynamic calculations were used to analyze the deposition data. The AIN‐CVD process could be approximated by calculating mass transfer—thermodynamic limits at low AlCl3 concentrations. The AIN deposition rate decreased drastically with increasing temperature above 1000°C in agreement with thermodynamic predictions. At high AlCl3 concentrations, a surface kinetic mechanism involving AlCl3 adsorbed on the deposition surface appeared to be the rate‐limiting step. The AIN deposition rate decreased on increasing the AlCl3 concentration or total pressure. The crystalline structure of AIN was strongly influenced by the processing parameters. The AIN coatings became highly crystalline and preferentially oriented with an increase in the AlCl3 concentration or pressure.
Packing Density of Composite Powder Mixtures
Authors: Zok Frank , Lange Fred F. , Porter John R.
Published: April 2005

A model of particle packing in binary composite systems is developed. The effects of both inclusion surfaces and touching inclusions on the packing density are taken into account. To implement the model, a statistical approach is used to determine the number of inclusion contacts as a function of inclusion content. The statistical approach indicates that the average number of inclusion contacts is a linear function of the inclusion volume fraction, a result which agrees very well with independent computer simulations. The model suggests that the packing efficiency, defined by the ratio of the packing density to the ideal packing density (as originally derived by Furnas), is governed by the inclusion volume fraction (fi) and the particle to inclusion size ratio (r). Good agreement is obtained between the theory and experimental literature data.
High‐Temperature Creep Deformation of Alumina — SiC‐Whisker Composites
Authors: Lin Hua‐Tay , Becher Paul F.
Published: April 2005

The creep resistance at temperatures between 1200° and 1300°C in air of alumina—SiC‐whisker composites was investigated via four‐point flexure to examine (1) the effect of whisker content and (2) the influence of densification additives (i.e., Y2O3 (plus MgO)). The creep resistance of polycrystalline alumina is greatly improved with the addition of ≤ 20 vol% SiC whiskers. The interlocking/pinning of grains by whiskers which limits grain‐boundary sliding contributes to the improvement in creep resistance. However, the creep rates of alumina composites in air increase at whisker contents ≥ 30 vol%. Electron microscopy observations suggested that the degradation in creep resistance for whisker content ≥ 30 vol% originated from (1) the promotion of creep cavitation and subsequent microcrack generation from the higher number density of nucleation sites and (2) more extensive formation of grain‐boundary amorphous phase(s) associated with an observed increased oxidation rate. Along this one, the excellent creep resistance of alumina composites containing 20 vol% SiC whiskers was significantly degraded by the presence of the intergranular amorphous phases introduced by the addition of the Y2O3 densification additive.
Thermal Expansion of Solid Solutions in the ZrTiO4—In2O3—M2O5 (M = Sb, Ta) System
Authors: Ikawa Hiroyuki , Shimojima Hiromasa , Urabe Kazuyori , Fukunaga Osamu
Published: April 2005

Axial and dilatometric thermal expansions and phase transformations were studied for solid solutions having the α‐PbO2 structure in the ZrTiO4—In2O3—M2O5 (M = Sb, Ta) system with nominal formulas of ZrxTiyInzSbzO4 and ZrxTiyInzTazO4 where x+y+ 2z= 2. With increased substitution of z, the cell volume increased, the difference in the b parameters at room temperature between those quenched from 1400° and 1000°C decreased, and the thermal expansion decreased. The axial thermal expansion of ZrTiyInz· TazO4 with z= 0.3 was almost identical with that of HfTiO4, and those with z= 0.4 and z= 0.45 were smaller than that of HfTiO4. Unit‐cell volumes of these compound were compared with those of single oxides to make it clear that the unit‐cell volume of ZrTiO4 was small anomalously and to distinguish the normal and abnormal substitution systems. These results were explained by the working hypothesis proposed for these compounds.
Phase Stability, Phase Transformation Kinetics, and Conductivity of Y2O3—Bi2O3 Solid Electrolytes Containing Aliovalent Dopants
Authors: Fung Kuan Zong , Virkar Anil V.
Published: April 2005

Single‐phase, cubic solid solutions of baseline composition 25% Y2O3—75% Bi2O3 with and without aliovalent dopants were fabricated by pressureless sintering of powder compacts. CaO, SrO, ZrO2, or ThO2 was added as an aliovalent dopant. Sintered samples were annealed between 600° and 650°C for up to 4000 h. Samples doped with ZrO2 or ThO2 remained cubic, depending upon the dopant concentration, even after long‐term annealing. By contrast, undoped, CaO‐doped, and SrO‐doped samples transformed to the low‐temperature, rhombohedral phase within ∼ 200 h. Conductivity measurements showed no degradation of conductivity in samples that did not undergo the transformation. In samples that underwent the transformation, a substantial decrease in conductivity occurred. The enhanced stability of the ZrO2‐ and ThO2‐doped samples is rationalized on the basis of suppressed interdiffusion on the cation sublattice.
Crack Stability and T‐Curves Due to Macroscopic Residual Compressive Stress Profiles
Authors: Tandon Rajan , Green David J.
Published: April 2005

Stabilization of the fracture process and resistance to strength degradation have been observed for materials with increasing T‐curves. In this study, the possibility of using residual compressive stresses to induce crack stabilization is examined theoretically. Nonmonotonic forms for the residual compressive stress profiles are assumed. The stress intensity factors for linear through‐the‐thickness cracks subjected to these profiles are derived. The stress intensity factors are then used to construct the T‐curves for the stress profiles considered. It is demonstrated that the presence of these T‐curves leads to crack stability under the action of applied tensile stresses, and to strength insensitivity to the initial flaw size. The effects of additional localized stress fields (similar to those produced by indentation) on crack growth in these materials are also considered. In this case, the strength is found to be relatively insensitive to the magnitude of the localized loading. It is therefore concluded that residual stresses can be used to improve mechanical reliability in ways which are usually associated with microstructural toughening mechanisms.
Thermodynamic Model of the Cubic → Tetragonal Transition in Nonstoichiometric Zirconia
Authors: Hillert Mats
Published: April 2005

Nonstoichiometric zirconia is described with a model recently developed for ZrO2—Y2O3 alloys. It is thus possible to rationalize the experimental information on the cubic/tetragonal phase boundaries in zirconia.
Intrinsic Kinetics of Carbon Dioxide Degradation of YBa2Cu3O7‐x
Authors: Borowiec Krzysztof , Przyluski Jan , Kolbrecka Krystyna
Published: April 2005

The intrinsic kinetics, unaffected by diffusional and masstransfer effects, of the CO2 degradation of superconducting particles have been determined using a nonisothermal technique. Below 900°C, the carbonization of YBa2Cu3O7‐x leads to formation of BaCO3, Y2Cu2O5, CuO, and Cu2O. A further increase in temperature results in formation of BaCuO2 from BaCO3 and CuO. The carbonization rate shows the 1.5th‐order dependence on the amount of unreacted YBa2Cu3O7‐x for the temperature range of 550° to 815°C. The activation energy of carbonization was determined to be 95.1 kJ · mol−1.
Interaction of Chemically Vapor Deposited YBa2Cu3Ox with Yttria‐Stabilized Zirconia Substrates
Authors: Shapiro M. J. , More Karren L. , Lackey W. J. , Hanigofsky John A. , Hill D. Norman , Carter W. B. , Barefield E. K. , Judson Elizabeth A. , O'Brien D. F. , Patrick R. , Chung Y. S. , Moss T. S.
Published: April 2005

High‐resolution transmission electron microscopy and optical diffractograms have revealed that chemically vapor deposited films of superconducting YBa2Cu3Ox react to form an interaction layer with single‐crystal yttriastabilized zirconia. The approximately 5 nm thick interlayer was identified as BaZrO3. Zirconium was also found to diffuse through the entire YBa2Cu3Ox film.
Grain‐Size‐Dependent Transformation Behavior in Polycrystalline Tetragonal Zirconia
Authors: Becher Paul F. , Swain Michael V.
Published: April 2005

Experimental observations of the tetragonal phase transformation behavior in polycrystalline zirconias and the related toughening contribution are presented. An analysis which considers transformation thermodynamics and residual stresses is developed to describe the influence of grain size on tetragonal‐to‐monoclinic transformation temperature. The model is based on the promotion of the transformation by local internal tensile stress concentrations whose effects scale with grain size. The analysis is supported by observations of the martensite start temperature–grain size behavior in polycrystalline tetragonal zirconia containing 12 mol% ceria (12CeTZP). Next, the analysis considers the grain‐size‐dependent behavior of the transformation‐toughening contribution, ΔKT, and the transformation zone size, rT. The tetragonal‐to‐monoclinic (t‐to‐m) formation temperature, Ms, increases with increase in tetragonal grain size, d. Experimental results for zirconia‐12 mol% ceria (12CeTZP) and 2YTZP ceramics illustrate the predicted forms of the grain size dependencies for ΔKT and rT. The analytical model also describes the temperature dependence of the transformation‐toughening contribution ΔKT observed in 2 mol% yttriadoped polycrystalline tetragonal zirconias (2YTZP).
Elastic Properties and Molar Volume of Rare‐Earth Aluminosilicate Glasses
Authors: Tanabe Setsuhisa , Hirao Kazuyuki , Soga Naohiro
Published: April 2005

The elastic properties, molar volume, and glass transition temperature (Tg) of rare‐earth‐containing aluminosilicate glasses were investigated in the compositions of SiO2–LnAlO3 and SiO2–Ln3/4Al5/4O3, where Ln is Y, La, Nd, Eu, or Yb. The molar volume decreased with decreased ionic size of the Ln3+ ion, and Tg and elastic moduli increased in the same order. The Yb‐containing glasses showed the highest Young's modulus among all the oxide glasses, even higher than the highest value ever known for glass containing Y2O3, as expected from the smaller ionic radius of Yb3+ than that of Y3+. The bulk modulus was found to be almost proportional to the inverse four‐thirds power of the molar volume of glasses in each composition, indicating that Ln3+ ions can substitute for each other without changing the glass structure except for the size of the local structure around themselves. From the comparison of these properties, the structural role of rare‐earth ions in these glasses is discussed.
Heterocoagulation as an Inclusion Coating Technique for Ceramic Composite Processing
Authors: Garino Terry
Published: April 2005

Colloidal heterocoagulation in aqueous media was used to form coatings of alumina or polystyrene latex particles on alumina spheres and of alumina or latex particles on silicon carbide whiskers. The polyelectrolyte dispersants poly‐(ammonium methacrylate) and poly(ethylenimine) were used to alter the inherent surface potentials of the materials to increase the applicability of this technique. In most cases, the coatings formed were partial monolayers, although thicker coatings of alumina were formed on the SiC due to aggregation of the alumina. The oxide coatings were relatively well adhered while the latex coatings were easily removed in aqueous media. The adherence of the latex coatings was improved by adding low alcohols to the heterocoagulating suspension.
High‐Resolution Electron Microscopy of the Silicon Carbide/Aluminum Carbide Interface
Authors: Yano Toyohiko , Kato Satoshi , Iseki Takayoshi
Published: April 2005

The interface of single‐crystal SiC and Al brazed at 1273 K is investigated by high‐resolution electron microscopy. The orientation relationship of SiC to the Al4C3 reaction layer that forms between the SiC and the Al can be expressed as (0001)SiC∥(0001)Al4C3 and [11∼00]SiC∥[11∼00]Al4C3. Furthermore, a very thin (two tetrahedral layers thick) transition phase and misfit dislocations are observed between the SiC and Al4C3 lattices. The structure of the transition phase is discussed based on the high‐resolution electron microscopy, the stacking of the (Al,Si)C4 tetrahedral layers, and the charge balance. The same reaction product, with the same orientation relationship, is observed at the interface of a polycrystalline SiC and Al brazed joint.
Origin of the Creep‐Crack Growth Threshold in a Glass‐Ceramic
Authors: Chan Kwai S. , Page Richard A.
Published: April 2005

The growth threshold, Kth, of large creep cracks in a glass‐ceramic has been investigated to determine the causes of the arrest and nonpropagating behaviors below a characteristic stress intensity, K, value. Using replication techniques, the dominant creep demage mechanisms during creep‐crack growth, which included grain‐boundary cavity and microcrack formation, were identified as a function of K levels and crack extension rates. Quantitative measurements of cavity density, D(r), and microcrack density, Ψ(r), revealed that the values of D(r) and Ψ(r) both decrease with the K level and with increasing distance, r, from the crack tip at a given K level. At K values below Kth, the cavity density became zero as preexisting grain‐boundary cavities were sintered, suggesting that the growth threshold originated from sintering of creep cavities. At K levels above Kth, microcracks located in the wake of the main crack were observed to be sintered also. Possible mechanisms responsible for the apparent self‐healing of microcracks and creep cavities in the glass‐ceramic are provided, together with theoretical and experimental support.
Effects of Joining Pressure and Deformation on the Strength and Microstructure of Diffusion‐Bonded Silicon Carbide
Authors: DeLeeuw David
Published: April 2005

The effects of joining pressure and deformation on the strength and microstructure of diffusion‐bonded SiC were examined using a hot‐press to apply varying amounts of interfacial pressure and a close‐fitting die to restrict deformation. SiC substrates were successfully diffusion bonded at 1950° and 2100°C. Joints which had uniform grain structure across the joint interface and bend strengths up to 300 MPa (44 ksi) were achieved. Pressing pressure was found to be a requirement for producing reasonable joint strength. It was also found that macroscopic deformation (>4% joint area expansion) is not necessary for effective diffusion bonding. Various methods for joining SiC are reviewed with regard to ease of processing, use limitations, and joint strength.