Comment on Leptophobic Bosons and νN\nu N Neutral Current Scattering Data

The relevance of existing $\nu N$ deep inelastic scattering data to models containing a leptophobic neutral vector boson is discussed. It is shown that this neutral current data is in good agreement with the Standard Model and disfavors such a leptophobic boson.Comment: LaTeX, 3 pages, 1 embedded PS figure, available at http://cordelia.fnal.gov/~ksmcf/publications/moriond_comment.ps.gz . Presented at the XXXIieme Rencontres de Moriond, Electroweak Interactions and Unified Theorie

A Precision Measurement of Electroweak Parameters in Neutrino-Nucleon Scattering

The CCFR collaboration reports a precise measurement of electroweak parameters derived from the ratio of neutral-current to charged-current cross-sections in neutrino-nucleon scattering at the Fermilab Tevatron. This ratio of cross-sections measures the neutral current couplings to quarks, which implies a determination of sin^2 theta_W (on-shell) = 0.2236 +/- 0.0028(expt.) +/- 0.0030(model) for m_top=175 GeV, m_Higgs=150 GeV. This is equivalent to M_W=80.35+/-0.21 GeV. The good agreement of this measurement with Standard Model expectations implies the exclusion of additional neutrino-neutrino-quark-quark contact interactions at 95% confidence at a mass scale of 1-8 TeV, depending on the form of the contact interaction.Comment: formatted in revtex, 5 pages, 3 eps figures included via psfig, submitted to Physical Review Letter

A Small Target Neutrino Deep-Inelastic Scattering Experiment at the First Muon Collider

Several different scenarios for neutrino scattering experiments using a neutrino beam from the muon collider complex are discussed. The physics reach of a neutrino experiment at the front end of a muon collider is shown to extend far beyond that of current neutrino experiments, since the high intensity neutrino beams one would see at the muon collider allow for a large flexibility in choosing neutrino targets. Measurements of quark spin, A-dependence of the structure function $xF_3$ and neutral current chiral couplings to quarks are outlined.Comment: 7 pages, 2 figures, to appear in the proceedings of the Workshop on Physics at the First Muon Collider and at the Front End of a Muon Collider, November 1997, Fermila

A tug-of-war between driver and passenger mutations in cancer and other adaptive processes

Cancer progression is an example of a rapid adaptive process where evolving new traits is essential for survival and requires a high mutation rate. Precancerous cells acquire a few key mutations that drive rapid population growth and carcinogenesis. Cancer genomics demonstrates that these few 'driver' mutations occur alongside thousands of random 'passenger' mutations-a natural consequence of cancer's elevated mutation rate. Some passengers can be deleterious to cancer cells, yet have been largely ignored in cancer research. In population genetics, however, the accumulation of mildly deleterious mutations has been shown to cause population meltdown. Here we develop a stochastic population model where beneficial drivers engage in a tug-of-war with frequent mildly deleterious passengers. These passengers present a barrier to cancer progression that is described by a critical population size, below which most lesions fail to progress, and a critical mutation rate, above which cancers meltdown. We find support for the model in cancer age-incidence and cancer genomics data that also allow us to estimate the fitness advantage of drivers and fitness costs of passengers. We identify two regimes of adaptive evolutionary dynamics and use these regimes to rationalize successes and failures of different treatment strategies. We find that a tumor's load of deleterious passengers can explain previously paradoxical treatment outcomes and suggest that it could potentially serve as a biomarker of response to mutagenic therapies. Collective deleterious effect of passengers is currently an unexploited therapeutic target. We discuss how their effects might be exacerbated by both current and future therapies