Non-hemolytic α-AApeptides as antimicrobial peptidomimetics

We report a new class of peptide mimetics, α-AApeptides, that display broad-spectrum activity against both Gram-negative and Gram-positive bacteria and fungi. With non-hemolytic activity, resistance to protease hydrolysis, and easy sequence programmability, α-AApeptides may emerge as a novel class of antibiotics.     

Pionization effects in nucleon-nucleus scattering

A simple unitary model for meson production in nucleon-nucleon scattering is extended to nucleon-nucleus scattering. In the high energy limit the produced mesons remain coherent with the projectile over the entire depth of the nucleus and tend to increase the total cross sections. A crude estimate of the size of the effect gives an increase of the total cross section for proton-deuteron scattering of 13 mb at NAL energies.     

Spin-orbit and Pauli-correlation effects in intermediate-energy proton-nucleus inelastic scattering

The excitation of the 3^? (6.13 MeV) state of ¹⁶O by 0.8 GeV protons is studied using Glauber theory with a spin-orbit NN amplitude. Two previously suggested approaches for handling the z-ordered non-commuting NN profile functions, γ, are compared and found to give nearly identical results for the usual observables. Transitions to certain LM substates which are forbidden in one approach are allowed in the other, but their cross sections are proportional to the fourth power of the strength of the NN spin-orbit amplitude and thus quite small. It is also shown that, in this energy region, an expansion in powers of the strength of the spin-orbit interaction converges rapidly and consequently any convenient ordering of the γ's can be used without serious errors. Using this result an estimate of the effects of Pauli correlations on the cross section and the polarization is given.     

Renormalization point invariance,twisted fans,and critical exponents at finite ϵ in the reggeon calculus.

A procedure for calculating critical exponents directly at finite ? is proposed. It relies on the invariance of the critical exponents at the critical coupling g^c of the full theory with respect to finite changes in the renormalization point. This is expressed as the coincidence of curves at the point β = 0 in the plane of β versus a critical exponent parametrically described by the renormalized coupling for various values of the renormalization point (the “twisted fan”). If more than one critical exponent is present the fan is a set of curves in a multidimensional space with the twist at β = 0 and the exact values of the critical exponents. In perturbative approximations, an approximate invariance may result whether or not a zero of β exists to that order. We show that in the one and two loop approximations to the Reggeon calculus this approximate invariance does occur. The values of the critical exponents at the approximate twists show remarkable stability properties. We obtain σ_tot ≈ (lns)^?γ where ?γ ≈ 0.11 and 0.17 for one and two loops respectively.     

The n-loop expansion of the Reggeon calculus

We apply the technique known in solid state physics as the n-loop expansion to calculate the critical indices of the φ³ Gribov Reggeon calculus directly in two transverse dimensions. Infrared pathologies of the massless theory require the calculation to be done in the infinite momentum limit of the massive theory. For n = 1 the results are close to those of the ε-expansion in O(ε). For n = 2 the β function has no zero, analogously to the case in solid state physics. Use of a Padé approximant for β yields σ_tot ≈ (1n s)^0.27 at infinity, close to the O(ε²) result.     

Study of pp and ΛΛ production in π±p reactions at 18.5 GeV/c

Studies have been made of the rare reactions $\text{π}{}^{\mathrm{+}}\text{p}\text{→ π}{}^{\mathrm{+}}\text{pp}\text{p}$ and $\text{Λ +}\text{Λ}\text{+}\text{anything}$, and of $\text{π}{}^{\mathrm{?}}\text{p}\text{→ π}{}^{\mathrm{?}}\text{pp}\text{p}$ and $\text{Λ +}\text{Λ}\text{+}\text{anything}$, with cross sections of 18.5 ± 5.5, 10.7 ± 3.0, 12.0 ± 5.0, and 19.7 ± 4.8 μb, respectively. Production characteristics of these reactions are examined and effective-mass spectra are presented. There is no significant evidence in the data for production of Ψ(3095) in the baryon-antibaryon system, or for any other high-mass resonances.     

Test of correlation expansions for inelastic scattering of protons from 16O and 40Ca in Glauber theory

Two different versions of a correlation expansion for the A-body nuclear transition density required to evaluate the Glauber amplitude for inelastic proton-nucleus scattering are tested. Antisymmetrized oscillator wave functions, containing only Pauli correlations, are used to calculate the “exact” amplitude as well as various terms in the correlation expansions for the excitation of the 3^? (6.13 MeV) state of ¹⁶O and the 5^? (4.49 MeV) state of ⁴⁰Ca. The leading term in both expansions, which ignores all correlations and corresponds to the Glauber theory version of the DWIA, leads to errors which are larger than present experimental errors, especially at large momentum transfers. In one version of the correlation expansion, due to Alkhazov et al., the first-order correction contains both elastic and inelastic two-body correlations and leads to satisfactory results. In the other version, used by Abgrall et al., the first-order correction contains only inelastic two-body correlations. In this case the first- and second-order corrections are needed to obtain accuracy comparable to that of the latest experiments.