286 research outputs found
Discussant\u27s response to Using and evaluating audit decision aids
https://egrove.olemiss.edu/dl_proceedings/1034/thumbnail.jp
Acme Financial Statement Insurance Company Inc.: A case study
https://egrove.olemiss.edu/dl_proceedings/1056/thumbnail.jp
Synthesis and characterisation of aliphatic hyperbranched polyamidoamines and polyamides
Dendrimers are perfectly branched macromolecules possessing large internal cavities and a known number and location of terminal groups. This unique architecture leads to many interesting properties and countless potential applications have been discussed. Their synthesis involves numerous repetitive steps, often requiring protection and deprotection chemistry and complex purification procedures. This limits their availability and leads to extremely high costs, a factor that has limited their use. Polyamidoamine (PAMAM) dendrimers, the first well-established series of dendrimers, were reported in the mid nineteen eighties. For many applications the synthetic difficulties associated with dendrimers are so great that many potential applications are prohibited. Hyperbranched polymers are produced by a simpler synthetic route, the step growth polymerisation of AB(_x) monomers in a one-pot procedure. They lack the architectural perfection of dendrimers but retain the large number of terminal groups and high degree of branching. Crucially, these polymers can be produced for a fraction of the cost of dendrimers. The synthesis of hyperbranched analogues to both the full and half generation PAMAM dendrimers from AB(_2) monomers is reported here. Attempts to extend this method to control the molecular weight, degree of branching and the terminal group functionality are discussed, as is the synthesis of a related series of polyamides. The characterisation of these materials and their physical properties are also described
On the naturalness of Einstein's equation
We compute all 2-covariant tensors naturally constructed from a
semiriemannian metric which are divergence-free and have weight greater than
-2.
As a consequence, it follows a characterization of the Einstein tensor as the
only, up to a constant factor, 2-covariant tensor naturally constructed from a
semiriemannian metric which is divergence-free and has weight 0 (i.e., is
independent of the unit of scale). Since these two conditions are also
satisfied by the energy-momentum tensor of a relativistic space-time, we
discuss in detail how these theorems lead to the field equation of General
Relativity.Comment: 12 pages, added references, corrected typo
Quantitative analysis of harmonic convergence in mosquito auditory interactions
This article analyses the hearing and behaviour of mosquitoes in the context of inter-individual acoustic interactions. The acoustic interactions of tethered live pairs of Aedes aegypti mosquitoes, from same and opposite sex mosquitoes of the species, are recorded on independent and unique audio channels, together with the response of tethered individual mosquitoes to playbacks of pre-recorded flight tones of lone or paired individuals. A time-dependent representation of each mosquito's non-stationary wing beat frequency signature is constructed, based on Hilbert spectral analysis. A range of algorithmic tools is developed to automatically analyse these data, and used to perform a robust quantitative identification of the 'harmonic convergence' phenomenon. The results suggest that harmonic convergence is an active phenomenon, which does not occur by chance. It occurs for live pairs, as well as for lone individuals responding to playback recordings, whether from the same or opposite sex. Male-female behaviour is dominated by frequency convergence at a wider range of harmonic combinations than previously reported, and requires participation from both partners in the duet. New evidence is found to show that male-male interactions are more varied than strict frequency avoidance. Rather, they can be divided into two groups: convergent pairs, typified by tightly bound wing beat frequencies, and divergent pairs, that remain widely spaced in the frequency domain. Overall, the results reveal that mosquito acoustic interaction is a delicate and intricate time-dependent active process that involves both individuals, takes place at many different frequencies, and which merits further enquiry
Assertion based approach to auditing
https://egrove.olemiss.edu/dl_proceedings/1174/thumbnail.jp
Panel discussion on The impact of mergers of accounting firms on the auditing profession
https://egrove.olemiss.edu/dl_proceedings/1078/thumbnail.jp
Boundary terms and their Hamiltonian dynamics
It is described how the standard Poisson bracket formulas should be modified
in order to incorporate integrals of divergences into the Hamiltonian formalism
and why this is necessary. Examples from Einstein gravity and Yang-Mills gauge
field theory are given.Comment: Talk at 29th Ahrenshoop Symposium in Buckow 1995, 6 pages,
espcrc2.sty, twoside.sty, fleqn.sty, amssymb.sty, no figure
Variational Principles for Natural Divergence-free Tensors in Metric Field Theories
Let be a system of differential equations for the
components of a metric tensor on . Suppose that transforms
tensorially under the action of the diffeomorphism group on metrics and that
the covariant divergence of vanishes. We then prove that is
the Euler-Lagrange expression some Lagrangian density provided that is
of third order. Our result extends the classical works of Cartan, Weyl,
Vermeil, Lovelock, and Takens on identifying field equations for the metric
tensor with the symmetries and conservation laws of the Einstein equations
- …