The Database of Abstracts of Reviews of Effects (DARE)

Systematic reviews are useful tools for busy decision-makers because they identify, appraise and synthesise the available research evidence on a particular topic. Many thousands of systematic reviews relevant to health care have been published. However, they can be difficult to locate and their quality is variable. DARE (the Database of Abstracts of Reviews of Effects) contains summaries of systematic reviews which have met strict quality criteria. Each summary also provides a critical commentary on the quality of the review. DARE covers a broad range of health care related topics and can be used for answering questions about the effects of health care interventions, as well as for developing clinical guidelines and policy making. DARE is available free of charge on the internet (http://nhscrd.york.ac.uk), and as part of the Cochrane Library. Alternatively, DARE can be searched, on your behalf, by CRD information staff (tel: 01904 433707 or email [email protected])

Hopf instantons, Chern-Simons vortices, and Heisenberg ferromagnets

The dimensional reduction of the three-dimensional fermion-Chern-Simons model (related to Hopf maps) of Adam et el. is shown to be equivalent to (i) either the static, fixed--chirality sector of our non-relativistic spinor-Chern-Simons model in 2+1 dimensions, (ii) or a particular Heisenberg ferromagnet in the plane.Comment: 4 pages, Plain Tex, no figure

Information Services in the CGIAR

Paper by the TAC Standing Committee for External Reviews, drawing on the consultant paper by John Woolston, and several inputs from the CGIAR Secretariat concerning the role of information in the CGIAR. It argues for the centers to play a role in the development and use of a more coherent global information system for research in agriculture, forestry, and fisheries. The NARS should in the long term be able to participate in such a system as full fledged actors. The paper urges the CGIAR to take the lead in organizing a conference on global information needs and opportunities.Agenda document, TAC 56

Quantum Hall effect anomaly and collective modes in the magnetic-field-induced spin-density-wave phases of quasi-one-dimensional conductors

We study the collective modes in the magnetic-field-induced spin-density-wave (FISDW) phases experimentally observed in organic conductors of the Bechgaard salts family. In phases that exhibit a sign reversal of the quantum Hall effect (Ribault anomaly), the coexistence of two spin-density waves gives rise to additional collective modes besides the Goldstone modes due to spontaneous translation and rotation symmetry breaking. These modes strongly affect the charge and spin response functions. We discuss some experimental consequences for the Bechgaard salts.Comment: Final version (LaTex, 8 pages, no figure), to be published in Europhys. Let

Is "just-so" Higgs splitting needed for t-b-\tau Yukawa unified SUSY GUTs?

Recent renormalization group calculations of the sparticle mass spectrum in the Minimal Supersymmetric Standard Model (MSSM) show that t-b-\tau Yukawa coupling unification at M_{\rm GUT} is possible when the mass spectra follow the pattern of a radiatively induced inverted scalar mass hierarchy. The calculation is entirely consistent with expectations from SO(10) SUSY GUT theories, with one exception: it seems to require MSSM Higgs soft term mass splitting at M_{\rm GUT}, dubbed "just-so Higgs splitting" (HS) in the literature, which apparently violates the SO(10) gauge symmetry. Here, we investigate three alternative effects: {\it i}). SO(10) D-term splitting, {\it ii}). inclusion of right hand neutrino in the RG calculation, and {\it iii}). first/third generation scalar mass splitting. By combining all three effects (the DR3 model), we find t-b-\tau Yukawa unification at M_{\rm GUT} can be achieved at the 2.5% level. In the DR3 case, we expect lighter (and possibly detectable) third generation and heavy Higgs scalars than in the model with HS. In addition, the light bottom squark in DR3 should be dominantly a right state, while in the HS model, it is dominantly a left state.Comment: 21 pages with 11 .eps figures; revised version added two reference

Critical Exponents of the Three Dimensional Random Field Ising Model

The phase transition of the three--dimensional random field Ising model with a discrete ($\pm h$) field distribution is investigated by extensive Monte Carlo simulations. Values of the critical exponents for the correlation length, specific heat, susceptibility, disconnected susceptibility and magnetization are determined simultaneously via finite size scaling. While the exponents for the magnetization and disconnected susceptibility are consistent with a first order transition, the specific heat appears to saturate indicating no latent heat. Sample to sample fluctuations of the susceptibilty are consistent with the droplet picture for the transition.Comment: Revtex, 10 pages + 4 figures included as Latex files and 1 in Postscrip

D-branes and Closed String Field Theory

We construct BRST invariant solitonic states in the OSp invariant string field theory for closed bosonic strings. Our construction is a generalization of the one given in the noncritical case. These states are made by using the boundary states for D-branes, and can be regarded as states in which D-branes or ghost D-branes are excited. We calculate the vacuum amplitude in the presence of solitons perturbatively and show that the cylinder amplitude for the D-brane is reproduced. The results imply that these are states with even number of D-branes or ghost D-branes.Comment: 36 pages, 3 figures, LaTeX; typos correcte

Neutrino masses in the Lepton Number Violating MSSM

We consider the most general supersymmetric model with minimal particle content and an additional discrete Z_3 symmetry (instead of R-parity), which allows lepton number violating terms and results in non-zero Majorana neutrino masses. We investigate whether the currently measured values for lepton masses and mixing can be reproduced. We set up a framework in which Lagrangian parameters can be initialised without recourse to assumptions concerning trilinear or bilinear superpotential terms, CP-conservation or intergenerational mixing and analyse in detail the one loop corrections to the neutrino masses. We present scenarios in which the experimental data are reproduced and show the effect varying lepton number violating couplings has on the predicted atmospheric and solar mass^2 differences. We find that with bilinear lepton number violating couplings in the superpotential of the order 1 MeV the atmospheric mass scale can be reproduced. Certain trilinear superpotential couplings, usually, of the order of the electron Yukawa coupling can give rise to either atmospheric or solar mass scales and bilinear supersymmetry breaking terms of the order 0.1 GeV^2 can set the solar mass scale. Further details of our calculation, Lagrangian, Feynman rules and relevant generic loop diagrams, are presented in three Appendices.Comment: 48 pages, 7 figures, v2 references added, typos corrected, published versio