Probing Hadronic Structure with The Decay Δ→Nl+l−\Delta\rightarrow Nl^+l^-

We compute the branching ratio for $\Delta\rightarrow Ne^+e^-$ and $\Delta\rightarrow N\mu^+\mu^-$ in chiral perturbation theory and find that both decays should be observable at CEBAF. With sufficiently low thresholds on the $e^+e^-$ invariant mass a branching ratio of $\sim 10^{-5}$ may be observed for $\Delta\rightarrow Ne^+e^-$. For the $\Delta\rightarrow N\mu^+\mu^-$ decay mode we predict a branching ratio of $3\times 10^{-7}$. The dependence of the M1 and E2 amplitudes on the momentum transfer will provide a useful test of chiral perturbation theory which predicts $\sim 20\%$ variation over the allowed kinematic range.Comment: 6 pages, 3 figures, UCSD/PTH 93-06, QUSTH-93-02, Duke-TH-93-4

Microscopes and computers combined for analysis of chromosomes

Scanning machine CHLOE, developed for photographic use, is combined with a digital computer to obtain quantitative and statistically significant data on chromosome shapes, distribution, density, and pairing. CHLOE permits data acquisition about a chromosome complement to be obtained two times faster than by manual pairing

The relational ethics of conflict and identity

The contemporary psychoanalytically inflected vocabulary of relational ethics centres on acknowledgement, witnessing and responsibility. It has become an important code for efforts to connect with otherness across fractures of hurt, oppression and suffering. One can see the deployment of this vocabulary to challenge patterns of exclusion and dehumanisation in zones of intense political conflict in many situations in which destructive hatred reigns. This paper traces some of the use of and disputes over this ‘acknowledgement-based’ relational ethics in the recent work of Jessica Benjamin and Judith Butler. The field of application is their response to Israel’s treatment of the Palestinians, given their position as Jews. The challenge of the acknowledgement agenda leads back to an issue of general concern – the degree to which relational ethics can prise open apparently closed and defensive psychosocial identities

Comment on "Valence QCD: Connecting QCD to the Quark Model"

I criticize certain conclusions about the physics of hadrons drawn from a "valence QCD" approximation to QCD.Comment: 12 pages, 8 figures; some minor improvements made to the tex

Decuplet baryon magnetic moments in a QCD-based quark model beyond quenched approximation

We study the decuplet baryon magnetic moments in a QCD-based quark model beyond quenched approximation. Our approach for unquenching the theory is based on the heavy baryon perturbation theory in which the axial couplings for baryon - meson and the meson-meson-photon couplings from the chiral perturbation theory are used together with the QM moment couplings. It also involves the introduction of a form factor characterizing the structure of baryons considered as composite particles. Using the parameters obtained from fitting the octet baryon magnetic moments, we predict the decuplet baryon magnetic moments. The $\Omega^-$ magnetic moment is found to be in good agreement with experiment: $\mu_{\Omega^-}$ is predicted to be $-1.97 \mu_N$ compared to the experimental result of ($-$2.02 $\pm$ 0.05) $\mu_N$.Comment: 19 pages, 2 figure

Robust ecological pattern formation induced by demographic noise

We demonstrate that demographic noise can induce persistent spatial pattern formation and temporal oscillations in the Levin-Segel predator-prey model for plankton-herbivore population dynamics. Although the model exhibits a Turing instability in mean field theory, demographic noise greatly enlarges the region of parameter space where pattern formation occurs. To distinguish between patterns generated by fluctuations and those present at the mean field level in real ecosystems, we calculate the power spectrum in the noise-driven case and predict the presence of fat tails not present in the mean field case. These results may account for the prevalence of large-scale ecological patterns, beyond that expected from traditional non-stochastic approaches.Comment: Revised version. Supporting simulation at: http://guava.physics.uiuc.edu/~tom/Netlogo

The Impact of Recent Banking Regulations on the Market for Corporate Control

Part II of this Article briefly discusses the historical development of the regulation of bank capital, focusing on the 1989 risk-based capital adequacy regulations as well as the 1989 highly leveraged transaction guidelines and their impact on the banking industry\u27s involvement in takeover transactions. This section also shows how the perverse incentives created by the present system of federal deposit insurance impact on the takeover market. Part III discusses the role of thrifts in corporate takeovers and the effect of the Financial Institutions Reform, Recovery and Enforcement Act of 1989, including its prohibition on thrifts\u27 purchasing junk bonds. The concluding section speculates as to why these seemingly unwise regulations were adopted