Unfactored Multiblock Methods: Part I - Initial Method Development. G.U. Aero Report 9511

The use of implicit multiblock methods is discussed and an unfactored method based on a conjugate gradient type solution is described. Preconditioners appropriate to multiblock are considered along with future extensions to parallel computing

Interferon beta in multiple sclerosis: experience in a British specialist multiple sclerosis centre

Background: The efficacy of interferon beta (IFN beta) is well established in relapsing-remitting multiple sclerosis (MS). However, the use of this drug in clinical practice is complex, especially because it is only partially effective, its long term efficacy and side effects are unknown, its efficacy may be abrogated by the development of neutralising antibodies, compliance is variable, and its cost effectiveness is controversial. Objectives and Methods: Analysis of a prospectively followed up series of 101 MS patients treated with IFN beta was undertaken to: (1) monitor the outcome of IFN beta treatment in clinical practice; (2) compare the immunogenicity of the three commercial IFN beta preparations available; (3) assess the proportion of patients fulfilling the current guidelines of the Association of British Neurologists for stopping IFN beta therapy. Results: During a median treatment period of 26 months (range 2–85), the relapse rate decreased by 41%. Although the reduction in the relapse rate was similar for all three commercial products, none of the Avonex treated patients were relapse free, compared with 19% of the Betaferon treated and 27% of the Rebif treated patients (p=0.02). Neutralising antibodies were not detected in Avonex treated patients (0 of 18), compared with 12 of 32 (38%) Betaferon treated and 10 of 23 (44%) Rebif treated patients (p=0.02). Forty of 101 (40%) patients satisfied the current (2001) Association of British Neurologists criteria for stopping IFN beta treatment at some stage during their treatment. Conclusion: IFN beta is effective in reducing the relapse rate in patients with relapsing-remitting MS in routine clinical practice. However, after a median treatment duration of 26 months, 40% of initially relapsing-remitting MS patients seem to have ongoing disease activity, presenting as disabling relapses or insidious progression

Organizational and Leadership Implications for Transformational Development

Transformational development is a concept of change that originated in the Christian context but has now become generally used in the work of both secular and faith-based organizations. The growing use of the concept by organizations that are fundamentally different has naturally led to some confusion about what the concept means and what it takes to effectively implement it. In this article, we describe the key features of the concept and how they are important in determining the organizational requirements for its effective implementation. Drawing on a few cases, the paper highlights the centrality of faith in transformational development work

Demonstration of the temporal matter-wave Talbot effect for trapped matter waves

We demonstrate the temporal Talbot effect for trapped matter waves using ultracold atoms in an optical lattice. We investigate the phase evolution of an array of essentially non-interacting matter waves and observe matter-wave collapse and revival in the form of a Talbot interference pattern. By using long expansion times, we image momentum space with sub-recoil resolution, allowing us to observe fractional Talbot fringes up to 10th order.Comment: 17 pages, 7 figure

Azimuthal anisotropy at RHIC: the first and fourth harmonics

We report the first observations of the first harmonic (directed flow, v_1), and the fourth harmonic (v_4), in the azimuthal distribution of particles with respect to the reaction plane in Au+Au collisions at the Relativistic Heavy Ion Collider (RHIC). Both measurements were done taking advantage of the large elliptic flow (v_2) generated at RHIC. From the correlation of v_2 with v_1 it is determined that v_2 is positive, or {\it in-plane}. The integrated v_4 is about a factor of 10 smaller than v_2. For the sixth (v_6) and eighth (v_8) harmonics upper limits on the magnitudes are reported.Comment: 6 pages with 3 figures, as accepted for Phys. Rev. Letters The data tables are at http://www.star.bnl.gov/central/publications/pubDetail.php?id=3

Magnetic Field Amplification in Galaxy Clusters and its Simulation

We review the present theoretical and numerical understanding of magnetic field amplification in cosmic large-scale structure, on length scales of galaxy clusters and beyond. Structure formation drives compression and turbulence, which amplify tiny magnetic seed fields to the microGauss values that are observed in the intracluster medium. This process is intimately connected to the properties of turbulence and the microphysics of the intra-cluster medium. Additional roles are played by merger induced shocks that sweep through the intra-cluster medium and motions induced by sloshing cool cores. The accurate simulation of magnetic field amplification in clusters still poses a serious challenge for simulations of cosmological structure formation. We review the current literature on cosmological simulations that include magnetic fields and outline theoretical as well as numerical challenges.Comment: 60 pages, 19 Figure

Azimuthal anisotropy and correlations in p+p, d+Au and Au+Au collisions at 200 GeV

We present the first measurement of directed flow ($v_1$) at RHIC. $v_1$ is found to be consistent with zero at pseudorapidities $\eta$ from -1.2 to 1.2, then rises to the level of a couple of percent over the range $2.4 < |\eta| < 4$. The latter observation is similar to data from NA49 if the SPS rapidities are shifted by the difference in beam rapidity between RHIC and SPS. Back-to-back jets emitted out-of-plane are found to be suppressed more if compared to those emitted in-plane, which is consistent with {\it jet quenching}. Using the scalar product method, we systematically compared azimuthal correlations from p+p, d+Au and Au+Au collisions. Flow and non-flow from these three different collision systems are discussed.Comment: Quark Matter 2004 proceeding, 4 pages, 3 figure

Azimuthal anisotropy: the higher harmonics

We report the first observations of the fourth harmonic (v_4) in the azimuthal distribution of particles at RHIC. The measurement was done taking advantage of the large elliptic flow generated at RHIC. The integrated v_4 is about a factor of 10 smaller than v_2. For the sixth (v_6) and eighth (v_8) harmonics upper limits on the magnitudes are reported.Comment: 4 pages, 6 figures, contribution to the Quark Matter 2004 proceeding

Kaon Production and Kaon to Pion Ratio in Au+Au Collisions at \snn=130 GeV

Mid-rapidity transverse mass spectra and multiplicity densities of charged and neutral kaons are reported for Au+Au collisions at \snn=130 GeV at RHIC. The spectra are exponential in transverse mass, with an inverse slope of about 280 MeV in central collisions. The multiplicity densities for these particles scale with the negative hadron pseudo-rapidity density. The charged kaon to pion ratios are $K^+/\pi^- = 0.161 \pm 0.002 {\rm (stat)} \pm 0.024 {\rm (syst)}$ and $K^-/\pi^- = 0.146 \pm 0.002 {\rm (stat)} \pm 0.022 {\rm (syst)}$ for the most central collisions. The $K^+/\pi^-$ ratio is lower than the same ratio observed at the SPS while the $K^-/\pi^-$ is higher than the SPS result. Both ratios are enhanced by about 50% relative to p+p and $\bar{\rm p}$+p collision data at similar energies.Comment: 6 pages, 3 figures, 1 tabl

Plasma Wakefield Acceleration with a Modulated Proton Bunch

The plasma wakefield amplitudes which could be achieved via the modulation of a long proton bunch are investigated. We find that in the limit of long bunches compared to the plasma wavelength, the strength of the accelerating fields is directly proportional to the number of particles in the drive bunch and inversely proportional to the square of the transverse bunch size. The scaling laws were tested and verified in detailed simulations using parameters of existing proton accelerators, and large electric fields were achieved, reaching 1 GV/m for LHC bunches. Energy gains for test electrons beyond 6 TeV were found in this case.Comment: 9 pages, 7 figure