Is consumption growth consistent with intertemporal optimization? evidence from the consumer expenditure survey

In this paper we show that some of the predictions of models of consumer intertemporal optimization are in line with the patterns of nondurable expenditure observed in U.S. household-level data. We propose a flexible specification of preferences that allows multiple commodities and yields empirically tractable equations. We estimate preference parameters using the only U.S. micro data set with complete consumption information. We show that previous rejections can be explained by the simplifying assumptions made in previous studies. We also show that results obtained using good consumption or aggregate data can be misleading

Molecular Evidence Suggests Multiple Evolutionary Origins of Sociality in the Polyphenic Spider \u3cem\u3eAnelosimus studiosus\u3c/em\u3e (Araneae: Theridiidae).

Anelosimus studiosus exhibits two behavioral phenotypes: subsocial and social. This is the only documented spider inhabiting a temperate climate exhibiting social behavior. While the subsocial phenotype is most common throughout the range, the social behavior occurs in isolated pockets in northern latitudes. This study examines the origins of the social phenotype within a segment of the spider\u27s range. Two hypotheses are tested: 1) pockets of social behavior represent a single origin or 2) pockets of social behavior represent local evolutions, thus leading to multiple origins of evolution. Microsatellite loci were used to determine genetic structure of the population and to estimate the origins of social behavior. All loci showed lower observed than expected heterozygosities and all populations show indications of high levels of inbreeding. A phylogeny indicates four of the six populations fall out by location, not phenotype. We propose these results reflect multiple local evolutions of the social strategy

Note on Polarographic Determination of Small Amounts of Lead

The composition and characteristics of a new supporting electrolyte for the polarographic determination of small amounts of lead are described. The electrolyte is a 0.5 N aqueous solution of succinic acid containing 0.008 % gelatine. The analysis of the results obtained with this electrolyte shows that it can be used even when concentrations of the order of 10-6 M Pb (or 1 ug Pb/ml.) are involved. It has been shown that the electrode reaction consists in a reversible cathodic reduction of bivalent lead ions to the uncharged metallic lead