Continuous quantum error correction

We describe new implementations of quantum error correction that are continuous in time, and thus described by continuous dynamical maps. We evaluate the performance of such schemes using numerical simulations, and comment on the effectiveness and applicability of continuous error correction for quantum computing.Comment: 6 pages, 3 figures. Presented at QCMC '04 (Univ. of Strathclyde, Glasgow, UK, July 25-29, 2004

Instant restore after a media failure

Media failures usually leave database systems unavailable for several hours until recovery is complete, especially in applications with large devices and high transaction volume. Previous work introduced a technique called single-pass restore, which increases restore bandwidth and thus substantially decreases time to repair. Instant restore goes further as it permits read/write access to any data on a device undergoing restore--even data not yet restored--by restoring individual data segments on demand. Thus, the restore process is guided primarily by the needs of applications, and the observed mean time to repair is effectively reduced from several hours to a few seconds. This paper presents an implementation and evaluation of instant restore. The technique is incrementally implemented on a system starting with the traditional ARIES design for logging and recovery. Experiments show that the transaction latency perceived after a media failure can be cut down to less than a second and that the overhead imposed by the technique on normal processing is minimal. The net effect is that a few "nines" of availability are added to the system using simple and low-overhead software techniques

A High Galactic Latitude HI 21cm-line Absorption Survey using the GMRT: II. Results and Interpretation

We have carried out a sensitive high-latitude (|b| > 15deg.) HI 21cm-line absorption survey towards 102 sources using the GMRT. With a 3-sigma detection limit in optical depth of ~0.01, this is the most sensitive HI absorption survey. We detected 126 absorption features most of which also have corresponding HI emission features in the Leiden Dwingeloo Survey of Galactic neutral Hydrogen. The histogram of random velocities of the absorption features is well-fit by two Gaussians centered at V(lsr) ~ 0 km/s with velocity dispersions of 7.6 +/- 0.3 km/s and 21 +/- 4 km/s respectively. About 20% of the HI absorption features form the larger velocity dispersion component. The HI absorption features forming the narrow Gaussian have a mean optical depth of 0.20 +/- 0.19, a mean HI column density of (1.46 +/- 1.03) X 10^{20} cm^{-2}, and a mean spin temperature of 121 +/- 69 K. These HI concentrations can be identified with the standard HI clouds in the cold neutral medium of the Galaxy. The HI absorption features forming the wider Gaussian have a mean optical depth of 0.04 +/- 0.02, a mean HI column density of (4.3 +/- 3.4) X 10^{19} cm^{-2}, and a mean spin temperature of 125 +/- 82 K. The HI column densities of these fast clouds decrease with their increasing random velocities. These fast clouds can be identified with a population of clouds detected so far only in optical absorption and in HI emission lines with a similar velocity dispersion. This population of fast clouds is likely to be in the lower Galactic Halo.Comment: 19 pages, 19 figures. Accepted for publication in Journal of Astrophysics & Astronom

Tensile and creep rupture behavior of P/M processed Nb-base alloy, WC-3009

Due to its high strength at temperatures up to 1600 K, fabrication of niobium base alloy WC-3009 (Nb30Hf9W) by traditional methods is difficult. Powder metallurgy (P/M) processing offers an attractive fabrication alternative for this high strength alloy. Spherical powders of WC-3009 produced by electron beam atomizing (EBA) process were successfully consolidated into a one inch diameter rod by vacuum hot pressing and swaging techniques. Tensile strength of the fully dense P/M material at 300-1590 K were similar to the arc-melted material. Creep rupture tests in vacuum indicated that WC-3009 exhibits a class 1 solid solution (glide controlled) creep behavior in the 1480 to 1590 K temperature range and stress range of 14 to 70 MPa. The creep behavior was correlated with temperature and stress using a power law relationship. The calculated stress exponent n, was about 3.2 and the apparent activation energy, Q, was about 270 kJ/mol. The large creep ductility exhibited by WC-3009 was attributed to its high strain rate sensitivity

Fisheries Stakeholders and Their Livelihoods in Tamil Nadu and Puducherry

Fisheries Management for Sustainable Livelihoods (FIMSUL), is a project implemented by the Food and Agriculture Organization of the United Nations (FAO) with the Government of Tamil Nadu and Puducherry in India under the World Bank Trust Fund. The project aims at establishing frameworks, processes and building capacities of various stakeholders especially the Government, to facilitate the planning, design and implementation of appropriate fisheries development and management policies. The project includes a series of stakeholder consultations and consensus building apart from detailed review and analysis in the areas of stakeholders, livelihoods, policy, legal and institutional frame work and fisheries management. Based on this, the project comes up with various options. Stakeholder and livelihoods analysis is an essential part of the project. Hence, the team developed a detailed methodology for stakeholder consultations which includes district level stake holder consultation, focus group discussions, household interviews and validation meetings. The stakeholder and livelihoods analysis following the above steps were done through six NGO partners working along the coast of Tamil Nadu and Puducherry who were initially trained on the methodology. The NGO partners : PLANT, GUIDE, FERAL, SIFFS, DHAN Foundation and TMSSS, especially a team of dedicated staff engaged by them had done an excellent work in completing comprehensive field exercises and bringing out 12 district/regional reports. These are published separately. This report is a compilation, and complete analysis of the stakeholders and livelihoods based on all the field level consultations.This report is expected to be an important reference to primary stakeholders' perspective of the important stakeholders in the sector, the livelihoods and livelihoods changes, the adaptive and coping mechanism, the relationships between the stakeholders and their hopes and aspirations. For any development intervention for any sector or stakeholder group, region-wise in marine fisheries in Tamil Nadu and Puducherry, the information from this report could be an important starting point

Elevated temperature tension, compression and creep-rupture behavior of (001)-oriented single crystal superalloy PWA 1480

Tensile and compressive flow behavior at various temperatures and strain rates, and tensile creep rupture behavior at 850 and 1050 C and various stresses were studied for (001)-oriented single crystals of the Ni-base superalloy PWA 1480. At temperatures up to 760 C, the flow stress is insensitive to strain rate and of greater magnitude in tension than in compression. At temperatures of 800 C and above, the flow stress decreases continuously with decreasing strain rate and the tension/compression anisotropy diminishes. The second stage creep rate and rupture time exhibited power law relationships with the applied stress for both 850 and 1050 C, however with different stress dependencies. The stress exponent for the steady state creep rate was about 7 at 1050 C, but much higher at 850 C, about 12. Directional coarsening of the gamma' phase occurred during creep at 1050 C, but not at 850 C

Structural adjustment

Structural adjustment may sound technical, but refers to the comprehensive economic programs that the major international lenders require of developing countries when they are granted a loan. These structural adjustment programs – called SAPs - require liberalization of the economy so that markets can function more easily and the recipient countries are more open to foreign investment. The impacts of these programs have been limited with a few success stories, and in the main produced negligible or negative impacts. Worst hit are the poor and vulnerable, who suffer unemployment, job insecurity, rising prices, reduced services, and ecological marginalization. Politically, SAPs signal a further erosion of sovereignty for developing countries and they create parallel governments run by unaccountable technical experts. This centralization is set against claims to decentralize control and decision-making to the localities. SAPs have changed name in the last decade, but are set to stay a key part of the international development scene