Cosmic Chemical Evolution

Numerical simulations of standard cosmological scenarios have now reached the degree of sophistication required to provide tentative answers to the fundamental question: Where and when were the heavy elements formed? Averaging globally, these simulations give a metallicity that increases from 1% of the solar value at $z=3$ to 20% at present. This conclusion is, in fact, misleading, as it masks the very strong dependency of metallicity on local density. At every epoch higher density regions have much higher metallicity than lower density regions. Moreover, the highest density regions quickly approach near solar metallicity and then saturate, while more typical regions slowly catch up. These results are much more consistent with observational data than the simpler picture (adopted by many) of gradual, quasi-uniform increase of metallicity with time.Comment: ApJ(Letters) in press, 15 latex pages and 4 figure

Mycobacterium as Polycyclic Aromatic Hydrocarbons (PAHs) Degrader

The genus Mycobacterium has the ability to degrade various environmental pollutants including polycyclic aromatic hydrocarbons (PAHs). Mycobacterium has an ability to withstand adverse environmental conditions and it has been considered for future bioremediation applications for the removal of PAH contaminants from crude oil–polluted sites. The degradation of PAHs using a cost-effective laboratory microcosm system was discussed. The various conditions such as environmental habitat, degradation behavior, enzymatic mechanisms, and ecological survival are thoroughly discussed in this chapter. Based on the above study, Mycobacterium has proved to be a better candidate in bioremediation of PAH-contaminated sites

Axial Flow Fan Use At San Manuel Mine

A case study is presented for the use of multiple axial flow main fans as the principle source of the primary mine ventilation system for a large multi level mine. Formerly owned by Magma Copper, BHP Copper Inc.\u27s San Manuel Mine is a large underground block caving copper mine which started producing copper in 1955. The San Manuel Mine produces over 50,000 tons per day sulfide copper ore. The total airflow into this mine is approximately 800 m3/s (1,600,000 cfm). Providing adequate ventilation has been a very challenging experience as new, deeper levels are developed. BHP relies on operation of axial flow main fans which offer the flexibility of blade pitch changes to satisfy airflow requirements. The system provides the airflow requirements for development, production, mine dewatering pump stations and underground maintenance shops. The ability to adjust blade pitch manually, provides flexibility and has been a preferred feature to variable speed drives typical of centrifugal fans. In addition, axial flow fans can often be located more conveniently in underground environments where space availability is at a premium. The ventilation practice described in this paper may be useful to other mines with similar layouts

The Stability of Quantum Concatenated Code Hamiltonians

Protecting quantum information from the detrimental effects of decoherence and lack of precise quantum control is a central challenge that must be overcome if a large robust quantum computer is to be constructed. The traditional approach to achieving this is via active quantum error correction using fault-tolerant techniques. An alternative to this approach is to engineer strongly interacting many-body quantum systems that enact the quantum error correction via the natural dynamics of these systems. Here we present a method for achieving this based on the concept of concatenated quantum error correcting codes. We define a class of Hamiltonians whose ground states are concatenated quantum codes and whose energy landscape naturally causes quantum error correction. We analyze these Hamiltonians for robustness and suggest methods for implementing these highly unnatural Hamiltonians.Comment: 18 pages, small corrections and clarification

Big data scalability of bayesPhylogenies on Harvard’s ozone 12k cores

Computational Phylogenetics is classed as a grand challenge data driven problem in the fourth paradigm of scientific discovery due to the exponential growth in genomic data, the computational challenge and the potential for vast impact on data driven biosciences. Petascale and Exascale computing offer the prospect of scaling Phylogenetics to big data levels. However the computational complexity of even approximate Bayesian methods for phylogenetic inference requires scalable analysis for big data applications. There is limited study on the scalability characteristics of existing computational models for petascale class massively parallel computers. In this paper we present strong and weak scaling performance analysis of BayesPhylogenies on Harvard’s Ozone 12k cores. We perform evaluations on multiple data sizes to infer the scaling complexity and find that strong scaling techniques along with novel methods for communication reduction are necessary if computational models are to overcome limitations on emerging complex parallel architectures with multiple levels of concurrency. The results of this study can guide the design and implementation of scalable MCMC based computational models for Bayesian inference on emerging petascale and exascale systems

Purification and properties of an endoglucanase from Thermoascus aurantiacus

AbstractAn Endo-cellulase was purified to homogeneity using ammonium sulfate precipitation, ion exchange and size exclusion chromatography from newly isolated strain of Thermoascus aurantiacus RBB-1. The recovery and purification fold were 13.3% and 6.6, respectively, after size exclusion chromatography. The purified cellulase has a molecular mass (M) of 35kDa. Optimum temperature for the enzyme was found to be 70°C and stability was upto 80°C for 1h. Along with higher stability at 80°C, enzyme showed half lives of 192h and 144h at 50 and 70°C respectively. The purified cellulase was optimally active at pH 4.0 and was stable over a broad pH range of 3.0–7.0. The enzyme purified showed apparent Km and Vmax values of 37mg/ml and 82.6U/min/mg protein respectively with higher salt tolerance of 10% for 1h

The Advantage of Increased Resolution in the Study of Quasar Absorption Systems

We compare a new R = 120,000 spectrum of PG1634+706 (z_QSO = 1.337,m_V = 14.9) obtained with the HDS instrument on Subaru to a R = 45, 000 spectrum obtained previously with HIRES/Keck. In the strong MgII system at z = 0.9902 and the multiple cloud, weak MgII system at z = 1.0414, we find that at the higher resolution, additional components are resolved in a blended profile. We find that two single-cloud weak MgII absorbers were already resolved at R = 45,000, to have b = 2 - 4 km/s. The narrowest line that we measure in the R = 120, 000 spectrum is a component of the Galactic NaI absorption, with b = 0.90+/-0.20 km/s. We discuss expectations of similarly narrow lines in various applications, including studies of DLAs, the MgI phases of strong MgII absorbers, and high velocity clouds. By applying Voigt profile fitting to synthetic lines, we compare the consistency with which line profile parameters can be accurately recovered at R = 45,000 and R = 120,000. We estimate the improvement gained from superhigh resolution in resolving narrowly separated velocity components in absorption profiles. We also explore the influence of isotope line shifts and hyperfine splitting in measurements of line profile parameters, and the spectral resolution needed to identify these effects. Super high resolution spectra of quasars, which will be routinely possible with 20-meter class telescopes, will lead to greater sensitivity for absorption line surveys, and to determination of more accurate physical conditions for cold phases of gas in various environments.Comment: To appear in AJ. Paper with better resolution images available at http://www.astro.psu.edu/users/anand/superhigh.AJ.pd

Efficient Quantum Circuits for Schur and Clebsch-Gordan Transforms

The Schur basis on n d-dimensional quantum systems is a generalization of the total angular momentum basis that is useful for exploiting symmetry under permutations or collective unitary rotations. We present efficient (size poly(n,d,log(1/\epsilon)) for accuracy \epsilon) quantum circuits for the Schur transform, which is the change of basis between the computational and the Schur bases. These circuits are based on efficient circuits for the Clebsch-Gordan transformation. We also present an efficient circuit for a limited version of the Schur transform in which one needs only to project onto different Schur subspaces. This second circuit is based on a generalization of phase estimation to any nonabelian finite group for which there exists a fast quantum Fourier transform.Comment: 4 pages, 3 figure