Underwriting Apophenia and Cryptids: Are Cycles Statistical Figments of our Imagination?

This paper re-examines the evidence in favour of the existence of underwriting cycles in property and casualty insurance and their economical significance. Using a meta-analysis of published papers in the area of insurance economics, we show that the evidence supporting the existence of underwriting cycles is misleading. There is, in fact, little evidence in favour of insurance cycles with a linear autoregressive character. This means that any cyclicality in firm profitability in the property and casualty insurance industry is not predictable in a classical econometric framework. It follows that pricing in the property and casualty insurance industry is not incompatible with that of a competitive market

Tetraphenylborate Anion as a Phenylating Agent: Chemical and Electrochemical Reactivity of BPh4--Rh Complexes toward Mono- and Dienes and Carbon Dioxide

A few aspects of the chemical and electrochemical reactivity of mono-, di-, and trinuclear η6-tertraphenylborate-Rh complexes [(C2H4)2Rh(η6-PhBPh3) (1), {[(C2H4)2Rh(η6-Ph)]2BPh2}O3SCF3 (2), and {[(C2H4)2Rh(η6-Ph)]3BPh}(O3SCF3)2 (3)] are described. The factors governing the phenyl transfer reaction from coordinated BPh4- anion to monoenes and dienes are highlighted. Phenyl transfer to ethylene affords, among other products, styrene and ethylbenzene; styrene is converted into trans-stilbene. Complexes 1 and 2 react with isoprene affording 1,1-dimethylindene and 1,2-dihydro-2-methyl- and 1,2-dihydro-3-methylnaphthalene, species formally involving phenyl transfer from B to coordinated isoprene and intramolecular cyclization of the resulting intermediate. The reactivity of 1-3 toward CO2 was studied and compared with that of (diphos)Rh(η6-PhBPh3). Using complexes 1-3, coordinated ethylene competes with CO2 toward coupling with phenyl. The electrochemical behavior of the dinuclear complex, 2, was studied. It undergoes two consecutive irreversible 1-electron reductions at -1.53 and -1.74 V vs. SCE, respectively Analogous experiments carried out in the presence of CO2 have clearly shown that the reduced species are both able to react catalytically with the heterocumulene under controlled-potential conditions (-1.5 and -1.8 V). CO2 was coupled with both ethylene and Ph affording propionic acid and HOBz. The former species was the only product under an ethylene/carbon dioxide atmosphere

Quantifying the morphology of key species caught in the southern Brazilian penaeid-trawl fishery as a precursor to improving selection

Penaeid trawls are poorly selective fishing gears; contributing towards approximately 27% of global marine fisheries discards. Various options are available for mitigating penaeid-trawl bycatch, including gear modifications such as 'bycatch reduction devices' (BRDs) or codend mesh-size regulations. A precursor to developing modifications is information about the key target and bycatch species in terms of their sizes and morphology. Here we describe the relationships between these characteristics for the southern Brazilian industrial penaeid-trawl fishery within a broader objective of proposing more selective trawl configurations. Catches were sampled during 37 tows. Fifty-two species were caught, including two loggerhead turtles, Caretta caretta, one green turtle, Chelonia mydas, as well as 61 individuals of seven ray species classified as Endangered or Critically Endangered. One penaeid (Pleoticus muelleri) and 11 teleosts were assessed for various morphological relationships. The data demonstrated that both the existing conventionally used 26 mm (stretched mesh opening; SMO) mesh and a legislated size of 30 mm SMO are too small. Using morphological relationships, we propose testing a minimum diamond-shaped mesh size of at least 35 mm and a square-mesh window in the top of the codend comprising at least 48 mm mesh. Such a configuration would probably retain penaeids and larger teleosts, but allow many small teleosts to escape. Anteriorly located grids are also required to reduce the bycatch of charismatic species like turtles and rays. Wide-scale use of such BRDs should considerably reduce bycatches and the ancillary impacts of regional penaeid-trawl fisheries

Activities of the french standardisation group (AFNOR) in odours : revision of the standard for the measurement of the odour intensity and creation of a new standard for the area source sampling

International audienceIn the frame of the French regulation evolution and the European standardisation on odour issues, two French technical groups were created 3 years ago. They deal with : - the update of the French standard for the measurement of odour intensity to take account of the publication of the European standardisation (EN 13725); A two-part standard is proposed, the first one dealing with the measurement strategy and the second one defining the application domains of this methodology. - the elaboration of a new standard for the measurement of odour flow rate from area sources by a direct measurement approach, the enclosure approach using an emission flux chamber. Sources to study were classified and strategies measurement were described according to the source dimensions. The current discussions deal with two methods used for passive sources : the "dynamic" one and the "renewing" one. The terminology had been chosen to describe their most influential parameter on the resul

Production of acrylic acid through nickel-mediated coupling of ethylene and carbon dioxide - A DFT study

Copyright © 2007 American Chemical SocietyThe production of acrylic acid (CH₂=HCO₂H) via homogeneous nickel-mediated coupling of ethylene (CH₂=H₂) and carbon dioxide (CO₂) is industrially unattractive at present due to its stoichiometric, rather than catalytic, reaction profile. We utilize density functional theory (DFT) to describe the potential energy surface for both the nickel-mediated coupling reaction and an intramolecular deactivation reaction reported to hinder the desired catalytic activity. The calculated route for the catalytic production of acrylic acid can be divided into three main parts, none of which contain significantly large barriers that would be expected to prohibit the overall catalytic process. Investigation of the catalyst deactivation reaction reveals that the proposed product lies +102.6 kJ mol⁻¹ above the reactants, thereby ruling out this type of pathway as the cause of the noncatalytic activity. Instead, it is far more conceivable that the overall reaction thermodynamics are responsible for the lack of catalytic activity observed, with the solvation -corrected Gibbs free energy of the coupling reaction in question (i.e., CH₂=H₂ + CO₂ → CH₂=HCO₂H) calculated to be an unfavorable +42.7 kJ mol−1.David C. Graham, Cassandra Mitchell, Michael I. Bruce, Gregory F. Metha, John H. Bowie, and Mark A. Buntin