Commentary

Elsen comments on articles by Deborah DeMott and James Cox. He agrees with them that the rules governing conduct are often different from the rules written in compliance programs and as part of codes of conduct

Getting research findings into practice : when to act on the evidence.

There is increasing interest in providing evidence based health care—that is, care in which healthcare professionals, provider managers, those who commission health care, the public, and policymakers consistently consider research evidence when making decisions. Purchasers, for example, should be able to influence the organisation and delivery of care (such as for cancer and stroke services) and the type and content of services (such as using chiropractic for back pain or dilatation and curettage and drug treatment for menorrhagia). Policymakers should ensure that policies on treatment reflect and are consistent with research evidence, and that the incentive structure within the health system promotes cost effective practice. They must also ensure that there is an adequate infrastructure for monitoring changes in practice and for producing, gathering, summarising, and disseminating evidence. Clinicians determine the day to day care patients receive in healthcare systems, and user groups (for example, patients, their families, and their representatives) are also beginning to play an important role in influencing healthcare decisions

Zeroes of the Neutrino Mass Matrix

We assume there to be precisely three left-handed neutrino states whose Majorana masses are generated by an unspecified mechanism. Were CP conserved, the symmetric neutrino mass matrix M would be real and all six of its distinct entries could be experimentally determined. But CP is not conserved so that M is likely to be complex. As a result, not all nine of its convention-independent real parameters can be determined without an appeal to theory. Thus we examine the possibility that a restricted class of neutrino mass matrices may suffice to describe current data, namely those complex symmetric matrices several of whose entries vanish. We find that there are seven acceptable textures with two independent zeroes, and we explore their contrasting phenomenological implications. Textures with more than two independent zeroes appear to be excluded by experiment.Comment: Version to appear in PL

Can the Zee ansatz for neutrino masses be correct?

Working in the framework of three chiral neutrinos with Majorana masses, we investigate a scenario first realized in an explicit model by Zee: that the neutrino mass matrix is strictly off-diagonal in the flavor basis, with all its diagonal entries precisely zero. This CP-conserving ansatz leads to two relations among the three mixing angles $(\theta_1, \theta_2, \theta_3)$ and two squared mass differences. We impose the constraint $|m_3^2 - m_2^2| \gg |m^2_2 - m_1^2|$ to conform with experiment, which requires the $\theta_i$ to lie nearby one of four 1-parameter domains in $\theta$-space. We exhibit the implications for solar and atmospheric neutrino oscillations in each of these cases. A unique version of the Zee {\it ansatz} survives confrontation with experimental data, one which necessarily involves maximal just-so vacuum oscillations of solar neutrinos.Comment: 7 pages, harvmac, typo corrected, ref. added, text modifie

Top-Quark Mass and Bottom-Quark Decay

The possibility of a long B-meson lifetime is explored, in which case the weak mixing angles θ_2 and θ_3 are quite small. This allows the derivation of a lower bound on the top-quark mass as a function of the B-meson lifetime, by comparison of the short-distance prediction for the CP-nonconservation parameter ε with its experimental value. The bound is significant for τ_B>4×10^(-13) s

EXPORT SUBSIDIES AND PROFIT-SHIFTING IN VERTICAL MARKETS

This study examines the interaction between export subsidies and profit-shifting in a vertical production system consisting of agricultural commodity production, and intermediate and final good processing, where the latter two stages may be characterized by imperfect competition. Using a model with general functional forms for demand, comparative statics indicate that an export subsidy to an unprocessed agricultural commodity, under certain circumstances, can have greater profit-shifting effects at the final processing stage compared to an export subsidy targeted at the final processed good.International Relations/Trade,