Low-Temperature Rapid Synthesis and Superconductivity of Fe-Based Oxypnictide Superconductors

we were able to develop a novel method to synthesize Fe-based oxypnictide superconductors. By using LnAs and FeO as the starting materials and a ball-milling process prior to solid-state sintering, Tc as high as 50.7 K was obtained with the sample of Sm 0.85Nd0.15FeAsO0.85F0.15 prepared by sintering at temperatures as low as 1173 K for times as short as 20 min.Comment: 2 pages,2 figures, 1 tabl

Banda Aceh-The Value of Earth Observation Data in Disaster Recovery and Reconstruction: A Case Study

On 26 December 2004, Banda Aceh in Indonesia was at the center of one of the worst natural disasters to affect mankind. Large amounts of international aid poured in to assist in the relief and reconstruction efforts. Amongst this effort, were investments in basic earth observation data from in-situ, airborne and space observations. While the use of this data is assumed to be crucial, few efforts have gone into quantifying the benefits of its acquisition. The objectives of this study were to interview a cross-section of agencies operating in Banda Aceh and across the province of Nanggroe Aceh Darussalam on the use, sources and quality of earth observation data in the relief/reconstruction effort; and to analyze and quantify the value that earth observation data brings to the relief/reconstruction effort based on the survey results and specific examples. Key findings from the interviews point to an overall improvement in the spatial data situation since the tsunami. Problems identified included insufficient training, lack of timely data and sometimes poor spatial resolution. Specific examples of the cost-benefits of earth observation data were typically on the order of millions of dollars and involved large time savings. IIASA is one of 12 partners in the European Union sponsored project "Global Earth Observation/Benefit Estimation: Now, Next and Emerging" (GEO-BENE). Additional GEO-BENE partner countries include Germany, Switzerland, Slovakia, Netherlands, Finland, South Africa and Japan. Within GEO-BENE we are developing methodologies and analytical tools to assess societal benefits of GEO in nine societal benefit areas- one of which is disasters. The tsunami affected province of Nanggroe Aceh Darussalam, and specifically Banda Aceh, has been selected as a case study. Other case studies representing different societal benefit areas include: biodiversity in South Africa, health and climate in Finland, fire in Europe, etc. For more information please refer to: www.geo-bene.eu

GEO Information For Disaster Recovery -- Case Study: The Use of Orthophotos in Aceh, Indonesia

This study, carried out between July-September 2008, looks specifically at the use of a high resolution aerial photograph (orthophoto) data set acquired in June 2005 over post tsunami Aceh, Indonesia. The study clearly demonstrates the benefit of the use of EO data for disaster recovery showing that the orthophoto data set, costing 1.4 million Euro, critically supported projects (primary users of the data set), worth over 16 times its actual cost (28 million Euro) and provided support to projects worth over 600 times its actual cost (880 million Euro). The study concludes that a simple robust methodology to quantify the benefit of EO data in disaster recovery may be implemented by monitoring the total costs of projects that are critically supported by the EO data set. To implement that monitoring mechanism, a robust and straightforward method must be in place with the EO data distributor that records simple criteria for each of the data users and related projects. The report provides a number of lessons that have been learnt from the spatial data initiatives between Official Development Agencies and the Government of Indonesia in response to the Tsunami. The report recommends that in order to ensure that the spatial data is used to its greatest benefit, prior to the initiation of any campaign, the donor funding the project must ensure that there is a defined and clearly proven, transparent, and accountable mechanism to ensure that the data is effectively delivered to the humanitarian aid community in a timely and efficient manner

High superconducting anisotropy and weak vortex pinning in Co doped LaFeAsO

Here, we present an electrical transport study in single crystals of LaFe$_{0.92}$Co$_{0.08}$AsO ($T_c \simeq 9.1$ K) under high magnetic fields. In contrast to most of the previously reported Fe based superconductors, and despite its relatively low $T_c$, LaFe$_{1-x}$Co$_x$AsO shows a superconducting anisotropy which is comparable to those seen for instance in the cuprates or $\gamma_H = H_{c2}^{ab}/H_{c2}^{c} = m_c/m_{ab} \simeq 9$, where $m_c/m_{ab}$ is the effective mass anisotropy. Although, in the present case and as in all Fe based superconductors, $\gamma \rightarrow 1$ as $T \rightarrow 0$. Under the application of an external field, we also observe a remarkable broadening of the superconducting transition particularly for fields applied along the inter-planar direction. Both observations indicate that the low dimensionality of LaFe$_{1-x}$Co$_x$AsO is likely to lead to a more complex vortex phase-diagram when compared to the other Fe arsenides and consequently, to a pronounced dissipation associated with the movement of vortices in a possible vortex liquid phase. When compared to, for instance, F-doped compounds pertaining to same family, we obtain rather small activation energies for the motion of vortices. This suggests that the disorder introduced by doping LaFeAsO with F is more effective in pinning the vortices than alloying it with Co.Comment: 7 figures, 7 pages, Phys. Rev. B (in press

Microstructure and Magnetic Properties of Grain Refined Pr2Co14B Melt-Spun Ribbons

The correlation between the grain refining effect of TiC on the microstructure of Pr2Co14B melt-spun ribbons and the magnetic properties is presented in this study. TiC enabled greater control of microstructure both in the as-spun and heat treated Pr2Co14B, compared with the material without TiC. As a result, coercivity of the sample with TiC was nearly twice that of the sample without TiC. In addition to Pr2Co14B, two other phases were found in the sample with TiC: one rich in Co and the other having a composition near PrCo2. TiC was found near the grain boundaries and at triple junctions. Also no Ti or C was found in the matrix phase indicating extreme low solubility of the elements when both are present with Pr2Co14B. As expected, both the samples with and without TiC have similar anisotropy field but the presence of room temperature non-ferromagnetic phases (TiC and PrCo2), caused a small decrease in magnetization of the sample with TiC although the romance of the isotropic materials were comparable

The demography of free-roaming dog populations and applications to disease and population control

Understanding the demography of domestic dog populations is essential for effective disease control, particularly of canine-mediated rabies. Demographic data are also needed to plan effective population management. However, no study has comprehensively evaluated the contribution of demographic processes (i.e. births, deaths and movement) to variations in dog population size or density, or determined the factors that regulate these processes, including human factors. We report the results of a 3-year cohort study of domestic dogs, which is the first to generate detailed data on the temporal variation of these demographic characteristics. The study was undertaken in two communities in each of Bali, Indonesia and Johannesburg, South Africa, in rabies-endemic areas and where the majority of dogs were free-roaming. None of the four communities had been engaged in any dog population management interventions by local authorities or animal welfare organizations. All identified dogs in the four communities were monitored individually throughout the study. We observed either no population growth or a progressive decline in population size during the study period. There was no clear evidence that population size was regulated through environmental resource constraints. Rather, almost all of the identified dogs were owned and fed regularly by their owners, consistent with population size regulated by human demand. Finally, a substantial fraction of the dogs originated from outside the population, entirely through the translocation of dogs by people, rather than from local births. These findings demonstrate that previously reported growth of dog populations is not a general phenomenon and challenge the widely held view that free-roaming dogs are unowned and form closed populations. Synthesis and applications. These observations have broad implications for disease and population control. The accessibility of dogs for vaccination and evaluation through owners and the movement of dogs (some of them infected) by people will determine the viable options for disease control strategies. The impact of human factors on population dynamics will also influence the feasibility of annual vaccination campaigns to control rabies and population control through culling or sterilization. The complex relationship between dogs and people is critically important in the transmission and control of canine-mediated rabies. For effective management, human factors must be considered in the development of disease and population control programmes

Probing fractal magnetic domains on multiple length scales in Nd2Fe14B

Using small-angle neutron scattering, we demonstrate that the complex magnetic domain patterns at the surface of Nd2Fe14B, revealed by quantitative Kerr and Faraday microscopy, propagate into the bulk and exhibit structural features with dimensions down to 6 nm, the domain wall thickness. The observed fractal nature of the domain structures provides an explanation for the anomalous increase in the bulk magnetization of Nd2Fe14B below the spin-reorientation transition. These measurements open up a rich playground for studies of fractal structures in highly anisotropic magnetic systems.Comment: Accepted for publication in Phys. Rev. Lett. (4 pages, 4 figures

Discovery of a binary icosahedral quasicrystal in Sc12_12Zn88_88

We report the discovery of a new binary icosahedral phase in a Sc-Zn alloy obtained through solution-growth, producing millimeter-sized, facetted, single grain, quasicrystals that exhibit different growth morphologies, pentagonal dodecahedra and rhombic triacontahedra, under only marginally different growth conditions. These two morphologies manifest different degrees of quasicrystalline order, or phason strain. The discovery of i-Sc$_12$Zn$_88$ suggests that a reexamination of binary phase diagrams at compositions close to crystalline approximant structures may reveal other, new binary quasicrystalline phases.Comment: Incorrect spelling in author list resolve