TEST OF A LIQUID ARGON CHAMBER WITH 20-u m RMS RESOLUTION

A measurement of the spatial resolution of a liquid-argon filled chamber was performed with minimum ionizing particles. Two multi-strip chambers with 20-{micro}m strip spacing operating in the ionization mode were used in the experiment. They perform in accordance with a simple model based on electron diffusion. An estimate of the amount of electron diffusion in liquid argon is given and the time jitter distribution has a FWHM of 200 ns. Under best conditions, the spatial resolution is better than 20 {micro}m rms with an efficiency of nearly 100%

Analysis of the proteins synthesized in ultraviolet light-irradiated Escherichia coli following infection with the bacteriophages λ drif d 18 and λ dfus -3

The presence of EF-Tu, RNA polymerase subunit α, and EF-G on the λ dfus -3 genome and EF-Tu, ribosomal proteins L7/L12, and RNA polymerase subunit β on the λ drif d 18 genome has been confirmed using a two-dimensional gel electrophoresis technique sensitive to changes in isoelectric point and molecular weight. In this system two EF-Tu gene products could not be resolved. Following infection of ultraviolet light-irradiated Escherichia coli with either λ dfus -3 or λ drif d 18, the EF-Tu gene, tufA , near 65 minutes on the genetic map is expressed as 3–4 copies per EF-G molecule. The EF-Tu gene, tufB , near 79 minutes on the genetic map, is expressed at about one-third of this rate. α is expressed as 1 copy per EF-G molecule, β as 0.14 per EF-G molecule and L7/L12 as 2.5 per EF-G. These figures compare well with the relative amounts found in exponentially-growing cells, in which the ratio of EF-Tu to EF-G is approximately 5. Almost 90% of the total number of proteins (calculated on a molecular weight basis) which theoretically can be encoded on the λ drif d 18 have been identified on the two-dimensional gel.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/47541/1/438_2004_Article_BF00341733.pd

I=3/2 KπK \pi Scattering in the Nonrelativisitic Quark Potential Model

We study $I=3/2$ elastic $K\pi$ scattering to Born order using nonrelativistic quark wavefunctions in a constituent-exchange model. This channel is ideal for the study of nonresonant meson-meson scattering amplitudes since s-channel resonances do not contribute significantly. Standard quark model parameters yield good agreement with the measured S- and P-wave phase shifts and with PCAC calculations of the scattering length. The P-wave phase shift is especially interesting because it is nonzero solely due to $SU(3)_f$ symmetry breaking effects, and is found to be in good agreement with experiment given conventional values for the strange and nonstrange constituent quark masses.Comment: 12 pages + 2 postscript figures, Revtex, MIT-CTP-210