Effect ofPremna latifolia Roxb andImperata arundinacea Cyril onin vitro oxalate crystal growth

Two indigenous drugsPremna latifolia Roxb (Agnimandha) andImperata arundinacea Cyril (Darbha) were studied for their anticalculogenic effect at 20 and 100 mg concentrations. Both the concentrations were found to be equally effective in reducing the size of oxalate crystal growthin vitro over a period of 30 days. There was no change in infra red spectra while scanning electron microscope analysis showed development of cracks in the interior of the crystals and a tendency for rupture of crystals. Chemolysis appears to be the mechanism of action of the drugs.     

A uniformly loaded infinite-length thin plate bent to a cylindrical surface in the presence of couple-stresses

Exact solutions, based on couple-stresses plane strain theory of elasticity, are presented for the normal, shear and couple-stresses, displacements and rotations of an infinite-length (in z-axis) rectangular thin plate simply supported at two opposite edges (i.e.x=±L) and bent by a uniform load. Exact solutions reduce to classical values as l→0. Here l is defined as the new elastic material constant taking account of couple stresses.     

Is the Internet a US invention?—an economic and technological history of computer networking

Although the inventions embodied in the Internet originated in a diverse set of industrial economies, the US was consistently the source of critical innovations and an early adopter of new applications. Why did other nations, including several that made important inventive contributions to the Internet, not play a larger role in its development, particularly in the creation of new business organizations, governance institutions, and applications? We argue that the role of the US “national innovation system” in the creation of the Internet echoes several key themes of US technological development before 1940. The presence of a large domestic market, a set of antitrust and regulatory policies that weakened the power of incumbent telecommunications firms, and a diverse private/public research community that was willing to work with both domestic and foreign inventions were important preconditions for US leadership in computer networking innovation.     

A citation-based document retrieval system for finding research expertise

Current citation-based document retrieval systems generally offer only limited search facilities, such as author search. In order to facilitate more advanced search functions, we have developed a significantly improved system that employs two novel techniques: Context-based Cluster Analysis (CCA) and Context-based Ontology Generation frAmework (COGA). CCA aims to extract relevant information from clusters originally obtained from disparate clustering methods by building relationships between them. The built relationships are then represented as formal context using the Formal Concept Analysis (FCA) technique. COGA aims to generate ontology from clusters relationship built by CCA. By combining these two techniques, we are able to perform ontology learning from a citation database using clustering results. We have implemented the improved system and have demonstrated its use for finding research domain expertise. We have also conducted performance evaluation on the system and the results are encouraging.     

Information Economy and Changing Occupational Structure in Singapore

Using population census data since 1921, this article traces changes in employment and occupational structure in Singapore in the past 80 years. This is a follow-up to an earlier paper by Kuo and Chen (1987) that reported the nascent formation of the information society in Singapore till the 1980s. It also makes an assessment of the role of proactive government policies in directing industrial restructuring and occupational changes in this city-state. It is found that the long-term growing trend in information-related occupations has been in tandem and supportive of industrial changes in Singapore. One more wave of growth of information producers (and certainly, innovators) and information distributors is expected in the next couple of decades. The momentum has started, and competition from regional countries similarly aspiring to be information and knowledge economies will quicken the pace. The government has initiated fundamental changes in the educational system to meet the challenges of the knowledge-based economy. The small city-state has also long adopted an adaptive philosophy to be responsive to the ever-changing environment, either in technology or in regional politics. Based on the trend analysis, it is expected that the emergent information society will graduate into full status when Singapore attains a developed country status in the forthcoming decades.     

On recursive averaging processes and Hilbert space extensions of the contraction mapping principle

If T maps a convex domain D_T into itself, and if {ω_n} is a real sequence with range in (0, 1] then the recursive averaging process,

$\text{X}{}_{\mathrm{n+1}}\text{=(1?omega;}{}_{\mathrm{n}}\text{)}\text{X}{}_{\mathrm{n}}\text{+ω}{}_{\mathrm{n}}\text{+ω}{}_{\mathrm{n}}\text{T}\text{x}{}_{\mathrm{n}}\text{,}\text{x}{}_0\text{=ξ?D}{}_{\mathrm{T}}$

generates a sequence {x?_n}; with range in D_T. Under suitable conditions on D_T, T and {ω_n} the sequence {x?_n} will converge in some sense to a fixed point of T. We prove that if D_T is a closed convex subset of a complex Hilbert space H, if Tω = (1 ? ω) I + ωT is a strict contraction for some ω ? (0, 1], and if {ω_n} satisfies the conditions,

$\text{ω}{}_{\mathrm{n}}\text{→ 0}$

and

$\text{∑}\text{n=0}\text{∞}\text{ω}{}_{\mathrm{n}}\text{=∞}$

then, for arbitrary ξ ? D_T, {x?_n} converges strongly to (the unique) fixed point of T. We also prove that if D_T and {ω_n} satisfy the foregoing conditions, if T has at least one fixed point, and if Tω is non-expansive for some ω ? (0, 1], then for all ξ ? D_T, {x?_n} converges at least weakly to some fixed point of T. Finally, we apply these results to linear equations involving bounded normal operators and obtain an extension of the classical Neumann operator series.     

Propagation through a slab of irregularities in a magneto-ionic medium

A theory is developed to describe the propagation of characteristics waves through an infinite slab of irregularities in a magneto-ionic medium. The theory makes use of the asymptotic Green's dyadic. The results show that mode conversion is possible through scattering from irregularities in an anisotropic background. Some special cases are discussed and an example is given.