Absence of structural correlations of magnetic defects in heavy fermion LiV2O4

Magnetic defects have pronounced effects on the magnetic properties of the face-centered cubic compound LiV2O4. The magnetic defects arise from crystal defects present within the normal spinel structure. High-energy x-ray diffraction studies were performed on LiV2O4 single crystals to search for superstructure peaks or any other evidence of periodicity in the arrangement of the crystal defects present in the lattice. Entire reciprocal lattice planes are mapped out with help of synchrotron radiation. No noticeable differences in the x-ray diffraction data between a crystal with high magnetic defect concentration and a crystal with low magnetic defect concentration have been found. This indicates the absence of any long-range periodicity or short-range correlations in the arrangements of the crystal/magnetic defects.Comment: 6 pages, 4 figure

Intrinsic Variability and Field Statistics for the Vela Pulsar: 3. Two-Component Fits and Detailed Assessment of Stochastic Growth Theory

The variability of the Vela pulsar (PSR B0833-45) corresponds to well-defined field statistics that vary with pulsar phase, ranging from Gaussian intensity statistics off-pulse to approximately power-law statistics in a transition region and then lognormal statistics on-pulse, excluding giant micropulses. These data are analyzed here in terms of two superposed wave populations, using a new calculation for the amplitude statistics of two vectorially-combined transverse fields. Detailed analyses show that the approximately power-law and lognormal distributions observed are fitted well at essentially all on-pulse phases by Gaussian-lognormal and double-lognormal combinations, respectively. These good fits, plus the smooth but significant variations in fit parameters across the source, provide strong evidence that the approximately power-law statistics observed in the transition region are not intrinsic. Instead, the data are consistent with normal pulsar emission having lognormal statistics at all phases. This is consistent with generation in an inhomogeneous source obeying stochastic growth theory (SGT) and with the emission mechanism being purely linear (either direct or indirect). A nonlinear mechanism is viable only if it produces lognormal statistics when suitably ensemble-averaged. Variations in the SGT fit parameters with phase imply that the radiation is relatively more variable near the pulse edges than near the center, as found in earlier work. In contrast, Vela's giant micropulses come from a very restricted phase range and have power-law statistics with indices ($6.7 \pm 0.6$) not inconsistent with nonlinear wave collapse. These results imply that normal pulses have a different source and generation mechanism than giant micropulses, as suggested previously on other grounds.Comment: 10 pages and 14 figures. Accepted by Monthly Notices of the Royal Astronomical Society in April 200

Nature of the Magnetic Order in BaMn2As2

Neutron diffraction measurements have been performed on a powder sample of BaMn2As2 over the temperature T range from 10 K to 675 K. These measurements demonstrate that this compound exhibits collinear antiferromagnetic ordering below the Neel temperature T_N = 625(1) K. The ordered moment mu = 3.88(4) mu_B/Mn at T = 10 K is oriented along the c axis and the magnetic structure is G-type, with all nearest-neighbor Mn moments antiferromagnetically aligned. The value of the ordered moment indicates that the oxidation state of Mn is Mn^{2+} with a high spin S = 5/2. The T dependence of mu suggests that the magnetic transition is second-order in nature. In contrast to the closely related AFe2As2 (A = Ca, Sr, Ba, Eu) compounds, no structural distortion is observed in the magnetically ordered state of BaMn2As2.Comment: 4 pages, 3 figures, 1 table; v2: additional discussion of Mn-Mn interactions; accepted for publication as a Rapid Communication in Phys. Rev.

Magnetic ordering in EuRh2As2 studied by x-ray resonant magnetic scattering

Element-specific x-ray resonant magnetic scattering investigations were performed to determine the magnetic structure of Eu in EuRh2As2. In the temperature range from 46 K down to 6 K, an incommensurate antiferromagnetic (ICM)structure with a temperature dependent propagation vector (0 0 0.9) coexists with a commensurate antiferromagnetic (CM) structure. Angular-dependent measurements of the magnetic intensity indicate that the magnetic moments lie in the tetragonal basal plane and are ferromagnetically aligned within the a-b plane for both magnetic structures. The ICM structure is a spiral-like magnetic structure with a turn angle of 162 deg between adjacent Eu planes. In the CM structure, this angle is 180 deg. These results are consistent with band-structure calculations which indicate a strong sensitivity of the magnetic configuration on the Eu valence.Comment: 5 pages, 5 figures (technical problem with abstract corrected, no other changes

Discovery of Five Recycled Pulsars in a High Galactic Latitude Survey

We present five recycled pulsars discovered during a 21-cm survey of approximately 4,150 deg^2 between 15 deg and 30 deg from the galactic plane using the Parkes radio telescope. One new pulsar, PSR J1528-3146, has a 61 ms spin period and a massive white dwarf companion. Like many recycled pulsars with heavy companions, the orbital eccentricity is relatively high (~0.0002), consistent with evolutionary models that predict less time for circularization. The four remaining pulsars have short spin periods (3 ms < P < 6 ms); three of these have probable white dwarf binary companions and one (PSR J2010-1323) is isolated. PSR J1600-3053 is relatively bright for its dispersion measure of 52.3 pc cm^-3 and promises good timing precision thanks to an intrinsically narrow feature in its pulse profile, resolvable through coherent dedispersion. In this survey, the recycled pulsar discovery rate was one per four days of telescope time or one per 600 deg^2 of sky. The variability of these sources implies that there are more millisecond pulsars that might be found by repeating this survey.Comment: 15 pages, 3 figures, accepted for publication in Ap

The Joint Vienna Institute

"How does the intellectual role played by international training organisations fit into the contemporary architecture of global governance? The international diffusion of economic policy ideas represents one of the core dimensions of contemporary global governance, which has generated heated controversy in recent years with international institutions such as the International Monetary Fund (IMF) and the World Bank castigated for championing a ‘one-size-fits-all’ brand of neoliberal economic reform. Yet while substantial scholarly attention has focused on analysing the effects of the formal compliance mechanisms that the IMF and the World Bank rely on to implement neoliberal policy changes in borrowing countries, such as loan conditionality, less attention has been devoted to exploring the intermediate avenues through which neoliberal ideas travel from global governance institutions to national governance contexts. This article aims to address this gap in the study of contemporary global governance and neoliberal policy diffusion through critically examining the evolving role of the Joint Vienna Institute (JVI), an international training organisation set up after the end of the Cold War to transmit global ‘best practice’ economic policy ideas to national officials in post-communist economies.

Comparisons of various configurations of the edge delamination test for interlaminar fracture toughness

Various configurations of Edge Delamination Tension (EDT) test specimens, of both brittle (T300/5208) and toughened-matrix (T300/BP907) graphite reinforced composite laminates, were manufactured and tested. The mixed-mode interlaminar fracture toughness, G sub C, was measured using (30/30 sub 2/30/90 sub N)sub s, n=1 or 2, (35/-35/0/90) sub s and (35/0/-35/90) sub s layups designed to delaminate at low tensile strains. Laminates were made without inserts so that delaminations would form naturally between the central 90 deg plies and the adjacent angle plies. Laminates were also made with Teflon inserts implanted between the 90 deg plies and the adjacent angle (theta) plies at the straight edge to obtain a planar fracture surface. In addition, interlaminar tension fracture toughness, GIc, was measured from laminates with the same layup but with inserts in the midplane, between the central 90 deg plies, at the straight edge. All of the EDT configurations were useful for ranking the delamination resistance of composites with different matrix resins. Furthermore, the variety of layups and configurations available yield interlaminar fracture toughness measurements needed to generate delamination failure criteria. The influence of insert thickness and location, and coupon size on G sub c values were evaluated

Detection of Giant Pulses from the Pulsar PSR B0031-07

Giant pulses have been detected from the pulsar PSR B0031-07. A pulse with an intensity higher than the intensity of the average pulse by a factor of 50 or more is encountered approximately once per 300 observed periods. The peak flux density of the strongest pulse is 530 Jy, which is a factor of 120 higher than the peak flux density of the average pulse. The giant pulses are a factor of 20 narrower than the integrated profile and are clustered about its center.Comment: 7 pages, 2 figures, to appear in: Pis'ma v Astronomicheskii Zhurnal, 2004, v.30, No.4, and will be translated as: Astronomy Letters, v.30, No.