Transport properties of heavily AsF5 doped polyacetylene

We report measurements of the temperature dependence of the thermoelectric power and electrical conductivity for polyacetylene heavily doped (more than 10%) with arsenic pentafluoride. The thermopower is small, positive and linear with temperature. The conductivity is very large for a polymeric system, about 1000 (Ω cm)^-1 at room temperature, and as temperature is decreased drops in value by less than a factor of two, becoming essentially temperature independent below 4 K. The samples exhibited ohmic behavior at the current densities used and did not show any frequency dependence up to 1000 Hz. No evidence for superconductivity was found down to 30 mK. The results are interpreted as the first conclusive evidence for the existence of a metallic state at all temperatures in this material.     

A Flaw in the Use of Minimal Defining Sets for Secret Sharing Schemes

It is shown that in some cases it is possible to reconstruct a block design uniquely from incomplete knowledge of a minimal defining set for . This surprising result has implications for the use of minimal defining sets in secret sharing schemes.     

PAST AND FUTURE MANAGEMENT OF A COLLAPSED FISHERY: THE BAY OF BISCAY ANCHOVY

Abstract We analyze the efficiency of the international management of the Bay of Biscay anchovy. While a sharing agreement between France and Spain has been in place since 1992, the fish stock collapsed in 2005 and the fishery closed from 2005 to spring 2010. We consider differences in production technologies between both countries and calibrate our model using data from 1987 to 2009. Our results suggest two sources of rent dissipation under the existing sharing agreement: inefficient quota allocation and production inefficiencies due to inflexible national regulations. We discuss several alternatives to improve management.     

ConFlo III - an interface for high precision delta(13)C and delta(15)N analysis with an extended dynamic range

A newly developed interface coupling a CHN combustion device (elemental analyser 'EA') to an isotope ratio mass spectrometer is described and evaluated. The purpose of the device is to extend the dynamic range of delta(13)C and delta(15)N analysis from less than 2 orders of magnitude to more than 3 orders of magnitude. Carbon isotope ratio measurements of atropine as a model compound have been performed analysing between 1 μg to 5 mg C with acceptable to excellent precision (0.6 to 0.06 per thousand, delta-notation). The correction due to the blank signal is critical for sample amounts smaller than 4 μg C. The maximum sample weight is determined by the combustion capacity of the EA. Larger sample amounts are measured using dilution of a small part of the EA effluent with helium. The dilution mechanism works virtually free of isotope fractionation. Copyright 1999 John Wiley & Sons, Ltd.     

DEFORMATION OF SOFT COLLOIDAL CRYSTALLINE STRUCTURE-THEORETICAL CONSIDERATIONS AND EXPERIMENTAL EVIDENCES BY SYNCHROTRON SMALL-ANGLE X-RAY SCATTERING ON TENSILE STRETCHED POLYMERIC LATEX FILM

Films obtained via drying a polymeric latex dispersion are normally colloidal crystalline where latex particles are packed into a face centered cubic (fcc) structure.Different from conventional atomic crystallites or hard sphere colloidal crystallites,the crystalline structure of these films is normally deformable due to the low glass transition temperature of the latex particles.Upon tensile deformation,depending on the drawing direction with respect to the normal of specific crystallographic plane,one ...     

Overlarge sets and partial geometries

We extend our earlier work on overlarge sets of Fano planes, obtaining three results of particular interest. We find seven new partial geometries pg(8,7,4) and nine new strongly regular graphs, by means of switching cliques of points with spreads of lines. One of these new strongly regular graphs supports four different partial geometries. Then we give a new construction of the recently discovered eightfold cover of the complete graph K₁₆.Supported by NSERC grant OGP0008651Supported by ARC grant A49130102 and an Australian Senior Research Fellowship     

Bicategories of spans and relations

A new kind of bicategorical limit is used to characterize bicategories of the form Spant($\text{E}$) and Rel($\text{E}$) where in the former case $\text{E}$ is a category with pullbacks and in the latter $\text{E}$ is a regular category. The characterization of Rel($\text{E}$) differs from those in the literature which require involutions on the bicategories.