Radiative damping: a case study

We are interested in the motion of a classical charge coupled to the Maxwell self-field and subject to a uniform external magnetic field, B. This is a physically relevant, but difficult dynamical problem, to which contributions range over more than one hundred years. Specifically, we will study the Sommerfeld-Page approximation which assumes an extended charge distribution at small velocities. The memory equation is then linear and many details become available. We discuss how the friction equation arises in the limit of "small" B and contrast this result with the standard Taylor expansion resulting in a second order equation for the velocity of the charge.Comment: 4 figure

Pentaquarks: review of the experimental evidence

Pentaquarks, namely baryons made by 4 quarks and one antiquark have been predicted and searched for since several decades without success. Theoretical and experimental advances in the last 2 years led to the observation of a number of pentaquark candidates. We review the experimental evidence for pentaquarks as well as their non-observations by some experiments, and discuss to which extend these sometimes contradicting informations may lead to a consistent picture.Comment: Contribution to the International Conference on 'Strangeness in Quark Matter', 15-21 Sept. 2004, Cape Tawn, South Afric

Polarization in Hyperon Photo- and Electro- Production

Multiple polarization observables must be measured to access the amplitude structure of pseudoscalar meson photoproduction off the proton. The hyperon-producing reactions are especially attractive to study, since the weak decays allow straightforward measurement of the induced and recoil polarization observables. In this paper we emphasize $\gamma + p \to K^+ + \Lambda$, discussing recent measurements of $C_x$, $C_z$, and $P$ for this reaction. An empirical constraint on the helicity amplitudes is obtained. A simplified model involving spin-flip and spin non-flip amplitudes is presented. Finally, a semi-classical model of how the polarization may arise is presented.Comment: Invited paper at NStar2007, Accepted for EPJ A 1-21-08, 6 pages, 6 figure

Sixty Years of Drug Discovery for Type 2 Diabetes: Where Are We Now?

The control of blood glucose is a dynamic interplay involving several complex systems. In diabetes these systems are perturbed, resulting in a disease continuum of progressive decline over many years. Today, excluding insulin, there are eight classes of anti-diabetic agent which have taken over 60 years to add to the pharmacy chest. In this review I have examined each of these classes with some bias towards drug discovery thinking. Based on history, future science here will be strong, progressive and innovative; the huge test for industry is their response to enormous challenges besetting drug discovery and successfully turn the drug discovery praxis into affordable, effective and safe medicines