UNLABELLED Synaptic dopamine is mainly regulated by presynaptic dopamine transporter (DAT) activity. We hypothesized that variations in synaptic dopamine are reflected by variations of DAT radioligand binding. The effect of haloperidol, which increases synaptic dopamine concentrations, was therefore assessed in the rat striatum using (123)I-N-omega-fluoropropyl-2beta-carbomethoxy-3beta-(4-iodop...

S-(+)-4-methyl-3-heptanone has been identified as the principal alarm pheromone of Atta texana and Atta cephalotes. Both enantiomers of 4methyl-3-heptanone have been synthesized and their biological activities have been compared on both species of ants. Comparison of the geometric averages of response ratios, at threshold concentration levels on A. texana, showed S(4)-4-methyl-3-heptanone to be...

A set S R d is C-Lipschitz in the x i-coordinate, where C > 0 is a real number, if for every two points a; b 2 S, we have ja i ? b i j C maxfja j ? b j j : j = 1; 2 Motivated by a problem of Laczkovich, the author asked whether every n-point set in R d contains a subset of size at least cn 1?1=d that is C-Lipschitz in one of the coordinates, for suitable constants C and c > 0 (depending on d). ...

The report by List, Lerner, and Barbas1 in 2000 of an intermolecular direct aldol reaction catalyzed by proline became an unexpected watershed for the field of organocatalysis.2-4 Pihko and co-workers4b,c were the first to observe significantly higher yields with addition of water to intermolecular aldol reactions, even allowing employment of stoichiometric substrate ratios in some cases. This ...

OBJECTIVE To characterise and compare the tensile characteristics after multi-proportional blending, to determine the proper blending ratio for new thermoplastic material and to compare its mechanical performance with commercial thermoplastics. METHODS PETG and PC2858 aggregates were blended in five different ratios. Standard specimens of each ratio were molded and tested to determine their m...

An assay was developed for simultaneous kinetic analysis of the activities of the bifunctional plant enzyme ribulose 1,5-bisphosphate carboxylase/oxygenase [EC 4.1.1.39]. [1-(14)C,5-(3)H]Ribulose 1,5-bisphosphate (RuBP) was used as the labeled substrate. Tritium enrichment of the doubly labeled 3-phosphoglycerate (3-PGA) product, common to both enzyme activities, may be used to calculate V(c)/V...

When ribulose-1,5-bisphosphate carboxylase is assayed under N(2) using [(3)H]ribulose 1,5-bisphosphate and (14)CO(2), [(3)H]3-phosphoglycerate and [(14)C]3-phosphoglycerate are produced in nonstoichiometric amounts in a ratio which approaches 7 at low concentrations of CO(2) (2 micromolar) assuming a 1:1 ratio at V(max) (280 micromolar). The log of the molar ratio varies as a linear function of...

This paper presents the results of X-ray CT imaging of the microstructure of sand particles subjected to high pressure one-dimensional compression leading to particle crushing. A high resolution X-ray CT machine capable of in situ imaging was employed to capture images of the whole volume of a sand sample subjected to compressive stresses up to 79.3 MPa. Images of the whole sample obtained at d...

We have selected and spatially separated the two conformers of 3-aminophenol (C6H7NO) present in a molecular beam. Analogous to the separation of ions based on their mass-to-charge ratios in a quadrupole mass filter, the neutral conformers are separated based on their different mass-to-dipole-moment ratios in an ac electric quadrupole selector. For a given ac frequency, the individual conformer...

One assumption of the matching approach to choice is that different independent variables control choice independently of each other. We tested this assumption for reinforcer rate and magnitude in an extensive parametric experiment. Five pigeons responded for food reinforcement on switching-key concurrent variable-interval variable-interval schedules. Across conditions, the ratios of reinforcer...