A Survey of Complex Object Technologies for Digital Libraries

Many early web-based digital libraries (DLs) had implicit assumptions reflected in their architecture that the unit of focus in the DL (frequently "reports" or "e-prints") would only be manifested in a single, or at most a few, common file formats such as PDF or PostScript. DLs have now matured to the point where their contents are commonly no longer simple files. Complex objects in DLs have emerged in response to various requirements, including: simple aggregation of formats and supporting files, bundling additional information to aid digital preservation, creating opaque digital objects for e-commerce applications, and the incorporation of dynamic services with the traditional data files. We examine a representative (but not necessarily exhaustive) number of current and recent historical web-based complex object technologies and projects that are applicable to DLs: Aurora, Buckets, ComMentor, Cryptolopes, Digibox, Document Management Alliance, FEDORA, Kahn-Wilensky Framework Digital Objects, Metadata Encoding & Transmission Standard, Multivalent Documents, Open eBooks, VERS Encapsulated Objects, and the Warwick Framework

Selective Breeding of Pacific White Shrimp (Litopenaeus vannamei) for Growth and Resistance to Taura Syndrome Virus

From 1995 to 1998, the Oceanic Institute operated a breeding program for Pacific white shrimp, Litopenaeus vannamei, based on a selection index weighted equally for growth and resistance to Taura Syndrome Virus (TSV). In 1998, two separate breeding lines were established. One line was selected 100% for growth (Growth line) and a second line was selected on an index weighted 70% for TSV resistance and 30% for growth (TSV line). After one generation of selection, select shrimp from the Growth line were 21% larger than unselected control shrimp (24.2 vs. 20.0 g). The half-sib heritability (h(2)) estimate for growth was 0.84 +/- 0.43(s.e.) and realized h(2) was 1.0 +/- 0.12. Females were 12.7% larger than males. Shrimp tails accounted for 65.1% of total body weight and males had a significantly higher percent tail than females (65.7% vs. 64.5%; P \u3c 0.001). Half-sib h(2) for percent tail was 0.15 +/- 0.12. In the TSV line, there was an 18.4% increase in survival to TSV between select and control shrimp after one generation of selection (46.4% vs. 39.2%). Realized h(2) for TSV resistance was 0.28 +/- 0.14 and h(2) on the underlying scale was 0.30 +/- 0.13. However, select shrimp in the TSV line were 4.6% smaller than control shrimp (22.6 vs. 23.7 g) and there was a negative genetic correlation between mean family growth and mean family survival to TSV [-0.46 +/- 0.18(s.e.)]. Percent females per family ranged from 39.7% to 69.2% and averaged 51 % female, but h(2) for sex ratio was zero, indicating that it is not feasible to select for a higher percentage of females. Significant improvements in growth and TSV resistance can be made in L. vannamei through selective breeding; however, the negative genetic correlation between growth and TSV resistance must be considered when developing breeding plans. (C) 2002 Elsevier Science B.V. All rights reserved

High-Density Linkage Maps and Sex-Linked Markers for the Black Tiger Shrimp (Penaeus monodon)

We report on the construction of sex-specific high-density linkage maps and identification of sex-linked markers for the black tiger shrimp (Penaeus monodon). Overall, we identified 44 male and 43 female linkage groups (2n = 88) from the analysis of 2306 AFLP markers segregating in three full-sib families, covering 2378 and 2362 cM, respectively. Twenty-one putatively homologous linkage groups, including the sex-linkage groups, were identified between the female and male linkage maps. Six sex-linked AFLP marker alleles were inherited from female parents in the three families, suggesting that the P. monodon adopts a WZ–ZZ sex-determining system. Two sex-linked AFLP markers, one of which we converted into an allele-specific assay, confirmed their association with sex in a panel of 52 genetically unrelated animals