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Leveraging legacy codes to distributed problem solving environments: A web service approach
This paper describes techniques used to leverage high performance legacy codes as CORBA components to a distributed problem solving environment. It first briefly introduces the software architecture adopted by the environment. Then it presents a CORBA oriented wrapper generator (COWG) which can be used to automatically wrap high performance legacy codes as CORBA components. Two legacy codes have been wrapped with COWG. One is an MPI-based molecular dynamic simulation (MDS) code, the other is a finite element based computational fluid dynamics (CFD) code for simulating incompressible Navier-Stokes flows. Performance comparisons between runs of the MDS CORBA component and the original MDS legacy code on a cluster of workstations and on a parallel computer are also presented. Wrapped as CORBA components, these legacy codes can be reused in a distributed computing environment. The first case shows that high performance can be maintained with the wrapped MDS component. The second case shows that a Web user can submit a task to the wrapped CFD component through a Web page without knowing the exact implementation of the component. In this way, a user’s desktop computing environment can be extended to a high performance computing environment using a cluster of workstations or a parallel computer
Novel transaminases from thermophiles: from discovery to application
Transaminases (TAs) are promising biocatalysts for chiral amine synthesis; however, only few thermophilic TAs have been described to date. In this work, a genome mining approach was taken to seek novel TAs from nine thermophilic microorganisms. TA sequences were identified from their respective genome sequences and their Pfam were predicted confirming that TAs class I–II are the most abundant (50%), followed by class III (26%), V (16%), IV (8%) and VI (1%). The percentage of open reading frames (ORFs) that are TAs ranges from 0.689% in Thermococcus litoralis to 0.424% in Sulfolobus solfataricus. A total of 94 putative TAs were successfully cloned and expressed into E. coli, showing mostly good expression levels when using a chemical chaperone media containing d-sorbitol. Kinetic and end-point colorimetric assays with different amino donors–acceptors confirmed TAs activity allowing for initial exploration of the substrate scope. Stereoselective and non-stereoselective serine-TAs were selected for the synthesis of hydroxypyruvate (HPA). Low HPA reaction yields were observed with four non-stereoselective serine-TAs, whilst two stereoselective serine-TAs showed significantly higher yields. Coupling serine-TA reactions to a transketolase to yield l-erythrulose (Ery) substantially increased serine conversion into HPA. Combining both stereoselective serine-TAs and transketolase using the inexpensive racemic D/L-serine led to high Ery yield (82%). Thermal characterization of stereoselective serine-TAs confirmed they have excellent thermostability up to 60°C and high optimum temperatures
Inflation from D3-brane motion in the background of D5-branes
We study inflation arising from the motion of a BPS D3-brane in the
background of a stack of k parallel D5-branes. There are two scalar fields in
this set up-- (i) the radion field R, a real scalar field, and (ii) a complex
tachyonic scalar field chi living on the world volume of the open string
stretched between the D3 and D5 branes. We find that inflation is realized by
the potential of the radion field, which satisfies observational constraints
coming from the Cosmic Microwave Background. After the radion becomes of order
the string length scale l_s, the dynamics is governed by the potential of the
complex scalar field. Since this field has a standard kinematic term, reheating
can be successfully realized by the mechanism of tachyonic preheating with
spontaneous symmetry breaking.Comment: 10 pages, 4 figures. Minor clarifications and references added.
Version to appear in Phys. Rev.
Quantum key distribution using a triggered quantum dot source emitting near 1.3 microns
We report the distribution of a cryptographic key, secure from photon number
splitting attacks, over 35 km of optical fiber using single photons from an
InAs quantum dot emitting ~1.3 microns in a pillar microcavity. Using below
GaAs-bandgap optical excitation, we demonstrate suppression of multiphoton
emission to 10% of the Poissonian level without detector dark count
subtraction. The source is incorporated into a phase encoded interferometric
scheme implementing the BB84 protocol for key distribution over standard
telecommunication optical fiber. We show a transmission distance advantage over
that possible with (length-optimized) uniform intensity weak coherent pulses at
1310 nm in the same system.Comment: 4 pages, 4 figure
Chern-Simons Solitons, Chiral Model, and (affine) Toda Model on Noncommutative Space
We consider the Dunne-Jackiw-Pi-Trugenberger model of a U(N) Chern-Simons
gauge theory coupled to a nonrelativistic complex adjoint matter on
noncommutative space. Soliton configurations of this model are related the
solutions of the chiral model on noncommutative plane. A generalized
Uhlenbeck's uniton method for the chiral model on noncommutative space provides
explicit Chern-Simons solitons. Fundamental solitons in the U(1) gauge theory
are shaped as rings of charge `n' and spin `n' where the Chern-Simons level `n'
should be an integer upon quantization. Toda and Liouville models are
generalized to noncommutative plane and the solutions are provided by the
uniton method. We also define affine Toda and sine-Gordon models on
noncommutative plane. Finally the first order moduli space dynamics of
Chern-Simons solitons is shown to be trivial.Comment: latex, JHEP style, 23 pages, no figur
An infrared study of the double nucleus in NGC3256
We present new resolved near and mid-IR imaging and N-band spectroscopy of
the two nuclei in the merger system NGCA3256, the most IR luminous galaxy in
the nearby universe. The results from the SED fit to the data are consistent
with previous estimates of the amount of obscuration towards the nuclei and the
nuclear star formation rates. However, we also find substantial differences in
the infrared emission from the two nuclei which cannot be explained by
obscuration alone. We conclude that the northern nucleus requires an additional
component of warm dust in order to explain its properties. This suggests that
local starforming conditions can vary significantly within the environment of a
single system.Comment: Accepted for publication (MNRAS
Estimation of the Serviceability of Forest Access Roads
The purpose of this study was to ascribe attributes to forest access roads, to allow for estimation of their serviceability on the basis of their current condition. The approach estimates the quantity of timber that may be hauled through without critically damaging the flexible pavements. Seventy-two roads were classified on the basis of their surface conditions, subgrade material, and surface deflection as the strength parameter, for 40 and 60 t Gross Vehicle Weight. Using non-parametric statistical techniques, it was found that the surface quality of pavements was largely dependent on drainage conditions (coefficient of determination r2 = 0.84), and that a strong relationship (r2 = 0.90) also existed between drainage and the number of potholes. Pavements with peat subgrades were found to exhibit significantly higher critical deflections (5.6 mm) than pavements with mineral subgrades (1 mm), coupled with their inherent variability, it is arguable that visual classification may not be suitable for such pavements. On the basis of these results, the serviceability of individual roads, in Equivalent Standard Axle Loads (ESAL) was estimated. Potential pavement damage by a standard 6 axle timber haulage truck, of 40 t Gross Vehicle Weight, with a payload of 27 t, was evaluated to be triple that due to a standard axle (8.16 t). Increasing the payload by about 10%, increased the ESAL required to transport a unit volume of timber, hence potential pavement damage, by 20%. Consequently, a significant reduction in the serviceability of forest access roads may be incurred by small overload margins that are usually ignored
Scattering of Noncommutative Waves and Solitons in a Supersymmetric Chiral Model in 2+1 Dimensions
Interactions of noncommutative waves and solitons in 2+1 dimensions can be
analyzed exactly for a supersymmetric and integrable U(n) chiral model
extending the Ward model. Using the Moyal-deformed dressing method in an
antichiral superspace, we construct explicit time-dependent solutions of its
noncommutative field equations by iteratively solving linear equations. The
approach is illustrated by presenting scattering configurations for two
noncommutative U(2) plane waves and for two noncommutative U(2) solitons as
well as by producing a noncommutative U(1) two-soliton bound state.Comment: 1+13 pages; v2: reference added, version published in JHE
Detection of the (OIII)88.16Mu line in M17
The detection of a predicted transition, the fine structure line of O3 at 88.16 microns in the H 2 region M17, was reported. Line intensity was measured at 2.2 sub + 7 sub -0.7 times 10 to the 15th power
Membrane amplitude and triaxial stress in twisted bilayer graphene deciphered using first-principles directed elasticity theory and scanning tunneling microscopy
Twisted graphene layers produce a moir\'e pattern (MP) structure with a
predetermined wavelength for given twist angle. However, predicting the
membrane corrugation amplitude for any angle other than pure AB-stacked or
AA-stacked graphene is impossible using first-principles density functional
theory (DFT) due to the large supercell. Here, within elasticity theory we
define the MP structure as the minimum energy configuration, thereby leaving
the height amplitude as the only unknown parameter. The latter is determined
from DFT calculations for AB and AA stacked bilayer graphene in order to
eliminate all fitting parameters. Excellent agreement with scanning tunneling
microscopy (STM) results across multiple substrates is reported as function of
twist angle.Comment: to appear in Phys. Rev.
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