36,954 research outputs found
PKI Interoperability: Still an Issue? A Solution in the X. 509 Realm
There exist many obstacles that slow the global adoption of public key infrastructure (PKI) technology. The PKI interoperability problem, being poorly understood, is one of the most confusing. In this paper, we clarify the PKI interoperability issue by exploring both the juridical and technical domains. We demonstrate the origin of the PKI interoperability problem by determining its root causes, the latter being legal, organizational and technical differences between countries, which mean that relying parties have no one to rely on. We explain how difficult it is to harmonize them. Finally, we propose to handle the interoperability problem from the trust management point of view, by introducing the role of a trust broker which is in charge of helping relying parties make informed decisions about X.509 certificates
Attracting capital for electric power development in sub-Saharan Africa: a multipronged approach
Cost efficiency and UK building societies. An econometric panel-data study employing a flexible fourier functional form
The paper empirically quantifies firm specific 'distribution free' cost efficiency,
economies of scale and economies of scope in the UK building society sector between
1990-1995. Both a flexible Fourier and a translog functional form are employed with
an intermediation representation of depository institution production. Differences in
the performance of these two functional forms are found. A broad distribution of cost
efficiency over the sample period is observed, with a mean efficiency of 76 per cent
estimated using the flexible Fourier form and a mean efficiency of 72.52 per cent
estimated employing the translog form. Distinct results for economies of scale are
produced with the two models
The valuation of riparian fisheries in Southern and Eastern Africa
This paper reviews the published and gray literature concerning economic valuations of river fisheries in eastern and southern Africa, extracting the best available information on their direct economic values and on the impacts of changes in water management on this value. It then assesses the methods used and makes recommendations regarding approaches to be used in future. The review concentrates on rivers with their associated floodplains and major deltas. The values and issues associated with estuaries and lakes are not considered
Fish distribution in a small domestic water supply reservoir: a case study of Kangimi Reservoir, Kaduna, Nigeria
A study of the composition and distribution of fish populations in the inshore, surface and bottom water habitats of Kangimi Reservoir showed that the most abundant family was the Cichlidae followed in order of abundance by the familiesCyprinidae, Schilbeidae, Mormyridae, Mochokidae, Characidae, centropomidae and Bagridae. Though the overall composition of families caught inn the three habitats did not vary significantly (P>0.05) only family Cichlidae showed habitat preference: there was a preponderance of Cichlidae in the inshore water habitat (P<0.05). The families Bagridae and Centropomidae were caught only in the inshore and bottom water habitats while the other families were caught from all habitats and showed no habitat preference. The dominance of primary and secondary consumers indicates high fish production potential under adequate managemen
Composite Fermions and Landau Level Mixing in the Fractional Quantum Hall Effect
The reduction of the energy gap due to Landau level mixing, characterized by
the dimensionless parameter , has
been calculated by variational Monte Carlo for the fractional quantum Hall
effect at filling fractions and 1/5 using a modified version of
Jain's composite fermion wave functions. These wave functions exploit the
Landau level mixing already present in composite fermion wave functions by
introducing a partial Landau level projection operator. Results for the energy
gaps are consistent with experimental observations in -type GaAs, but we
conclude that Landau level mixing alone cannot account for the significantly
smaller energy gaps observed in -type systems.Comment: 11 pages, RevTex, 2 figures in compressed tar .ps forma
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