Monte Carlo simulation with Tensor Network States

It is demonstrated that Monte Carlo sampling can be used to efficiently extract the expectation value of projected entangled pair states with large virtual bond dimension. We use the simple update rule introduced by Xiang et al. to obtain the tensors describing the ground state wavefunction of the antiferromagnetic Heisenberg model and evaluate the finite size energy and staggered magnetization for square lattices with periodic boundary conditions of sizes up to L=16 and virtual bond dimensions up to D=16. The finite size magnetization errors are 0.003(2) and 0.013(2) at D=16 for a system of size L=8,16 respectively. Finite D extrapolation provides exact finite size magnetization for L=8, and reduces the magnetization error to 0.005(3) for L=16, significantly improving the previous state of the art results.Comment: 6 pages, 7 figure

Mirroring Mobile Phone in the Clouds

This paper presents a framework of Mirroring Mobile Phone in the Clouds (MMPC) to speed up data/computing intensive applications on a mobile phone by taking full advantage of the super computing power of the clouds. An application on the mobile phone is dynamically partitioned in such a way that the heavy-weighted part is always running on a mirrored server in the clouds while the light-weighted part remains on the mobile phone. A performance improvement (an energy consumption reduction of 70% and a speed-up of 15x) is achieved at the cost of the communication overhead between the mobile phone and the clouds (to transfer the application codes and intermediate results) of a desired application. Our original contributions include a dynamic profiler and a dynamic partitioning algorithm compared with traditional approaches of either statically partitioning a mobile application or modifying a mobile application to support the required partitioning

CloudJet4BigData: Streamlining Big Data via an Accelerated Socket Interface

Big data needs to feed users with fresh processing results and cloud platforms can be used to speed up big data applications. This paper describes a new data communication protocol (CloudJet) for long distance and large volume big data accessing operations to alleviate the large latencies encountered in sharing big data resources in the clouds. It encapsulates a dynamic multi-stream/multi-path engine at the socket level, which conforms to Portable Operating System Interface (POSIX) and thereby can accelerate any POSIX-compatible applications across IP based networks. It was demonstrated that CloudJet accelerates typical big data applications such as very large database (VLDB), data mining, media streaming and office applications by up to tenfold in real-world tests

Time evolution of projected entangled pair states in the single-layer picture

We propose an efficient algorithm for simulating quantum many-body systems in two spatial dimensions using projected entangled pair states. This is done by approximating the environment, arising in the context of updating tensors in the process of time evolution, using a single-layered tensor network structure. This significantly reduces the computational costs and allows simulations in a larger submanifold of the Hilbert space as bounded by the bond dimension of the tensor network. We present numerical evidence for stability of the method on an antiferromagnetic isotropic Heisenberg model where good agreement is found with the available accurate results

Selective partition of plasmid DNA and RNA in aqueous two-phase systems by the addition of neutral salt.

The selective partition of plasmid DNA (pDNA) and RNA in polyethylene glycol (PEG) and di-potassium hydrogen phosphate aqueous two-phase systems (ATPSs) by addition of NaCl salt was studied with pure pDNA and RNA solutions. The pDNA is increasingly excluded from top phases upon the addition of 0.5% and 3% (w/w) NaCl. With 3% (w/w) NaCl, the logarithmic partition coefficient of RNA was 1.2 and as a result, the RNA concentration in the top phase was 3.3-fold higher than that in the bottom phase. It is demonstrated that 47%, 13.7% and 7.5% (w/v) of PEG were required to achieve identical precipitation effects with PEG 300, 1450 and 6000, respectively. The precipitation efficiency of 6.3% (w/v) PEG 300 corresponds to that of 1% (w/v) PEG 6000. The excluded volume effects in the top phase were probably responsible for the selective exclusion of different nucleic acids species. The results obtained in this study contribute to the basic knowledge of partition of macromolecules in ATPSs in terms of excluded volume theory

Partition of plasmid DNA in polymer-salt aqueous two phase systems

The partition of plasmid DNA (pDNA) in polyethylene glycol (PEG)–phosphate aqueous two-phase systems (ATPS) is presented. A high molecular weight (HMW) and a low molecular weight (LMW) polymer, PEG-1450 and -300, were used in combination with di-potassium hydrogen phosphate. The experimental results demonstrated that the plasmid pTX0161 displays a varied partition behaviour in PEG–phosphate ATPS. In HMW PEG (PEG-1450–phosphate systems), pDNA partitioned to the bottom phase only. In LMW PEG (PEG-300–phosphate systems), pDNA partitioned to all of the phases with respect to the phase composition, system temperature and concentration of lysate used in the ATPS. In systems with volume ratios higher than one, pDNA was mainly recovered in the top phase. For volume ratios between 0.5 and 1, pDNA mainly partitioned to the interface. In systems with volume ratios below 0.5, most of the pDNA was recovered in the bottom phase. For temperatures between 4 and 25°C, the partition to the top phase decreased whereas partition to the interface steadily increased. At 25°C, over 80% of pDNA was recovered in the interface. The partition to the bottom phase increased steadily with increasing temperatures up to 40°C and the partition to the interface decreased. At 20°C, the recovery of pDNA in the interface gradually increased and reached a maximum at 60% (w/w) lysate with 80% recovery recorded. At 25°C, over 80% of pDNA was recovered in the interface from lysate concentrations greater than 35% (w/w). At 30°C, the top phase preference changed to an interface preference between 0 and 20% (w/w) lysate

Physical characterisations of a single-stage Kühni-type aqueous two-phase extraction column

The main parameters which influence the behaviour of phase separation in a single-stage Kühni-type aqueous two-phase extraction column containing polyethylene (PEG) and di-potassium hydrogen phosphate were characterised. Two aqueous two-phase system (ATPS) composed of 12% (w/w) PEG 1450 and 12% (w/w) di-potassium hydrogen phosphate (designated as 12/12) and 12% (w/w) PEG 1450 and 11% (w/w) di-potassium hydrogen phosphate (designated as 12/11) were chosen in this study. The hold-up D increased with increasing impeller speeds and mobile phase flow rates. Phase separation for the 12/11 system was slower than that for the 12/12 system, which resulted in higher dispersed phase hold-up values for the 12/11 system. For 12/12 system, mass transfer of plasmid DNA (pDNA) from the dispersed mobile phase to the stationary phase increased rapidly with increasing impeller speeds of 130, 160 and 200 rpm which was reflected in the decreased values for CT/CTo. The degree of back-mixing quantified by the axial dispersion coefficient Dax was estimated to be 2.7 × 10−6 m2 s−1