Measurement of Z0 decays to hadrons, and a precise determination of the number of neutrino species

We have made a precise measurement of the cross section for e+e--->Z0-->hadrons with the L3 detector at LEP, covering the range from 88.28 to 95.04 GeV. From a fit to the Z0 mass, total width, and the hadronic cross section to be MZ0=91.160 +/- 0.024 (experiment) +/-0.030(LEP) GeV, [Gamma]Z0=2.539+/-0.054 GeV, and [sigma]h(MZ0)=29.5+/-0.7 nb. We also used the fit to the Z0 peak cross section and the width todetermine [Gamma]invisible=0.548+/-0.029 GeV, which corresponds to 3.29+/-0.17 species of light neutrinos. The possibility of four or more neutrino flavors is thus ruled out at the 4[sigma] confidence level.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28683/3/0000500.pd

An invasion history for Cercopagis pengoi based on mitochondrial gene sequences

The predatory cladoceran Cercopagis pengoi has extended its range over the past decade from the Ponto-Caspian basin into the Baltic Sea and the Laurentian Great Lakes. This study employs mitochondrial DNA (mtDNA) sequence analysis to elucidate the invasion corridors exploited during this range expansion. The Caspian and Black Sea populations of C. pengoi exhibit marked genetic divergence, enabling their discrimination as potential sources of the Baltic and Great Lakes populations. The limited mtDNA haplotype diversity detected in the Baltic populations suggests they were founded by a small number of colonists from the Black Sea. The colonization of North America was apparently a result of the transfer of animals from the Baltic Sea in ballast water