Applications and accuracy of the parallel diagonal dominant algorithm

The Parallel Diagonal Dominant (PDD) algorithm is a highly efficient, ideally scalable tridiagonal solver. In this paper, a detailed study of the PDD algorithm is given. First the PDD algorithm is introduced. Then the algorithm is extended to solve periodic tridiagonal systems. A variant, the reduced PDD algorithm, is also proposed. Accuracy analysis is provided for a class of tridiagonal systems, the symmetric, and anti-symmetric Toeplitz tridiagonal systems. Implementation results show that the analysis gives a good bound on the relative error, and the algorithm is a good candidate for the emerging massively parallel machines

A simple parallel prefix algorithm for compact finite-difference schemes

A compact scheme is a discretization scheme that is advantageous in obtaining highly accurate solutions. However, the resulting systems from compact schemes are tridiagonal systems that are difficult to solve efficiently on parallel computers. Considering the almost symmetric Toeplitz structure, a parallel algorithm, simple parallel prefix (SPP), is proposed. The SPP algorithm requires less memory than the conventional LU decomposition and is highly efficient on parallel machines. It consists of a prefix communication pattern and AXPY operations. Both the computation and the communication can be truncated without degrading the accuracy when the system is diagonally dominant. A formal accuracy study was conducted to provide a simple truncation formula. Experimental results were measured on a MasPar MP-1 SIMD machine and on a Cray 2 vector machine. Experimental results show that the simple parallel prefix algorithm is a good algorithm for the compact scheme on high-performance computers

Thermoelectric DC conductivities with momentum dissipation from higher derivative gravity

We present a mechanism of momentum relaxation in higher derivative gravity by adding linear scalar fields to the Gauss-Bonnet theory. We analytically computed all of the DC thermoelectric conductivities in this theory by adopting the method given by Donos and Gauntlett in [arXiv:1406.4742]. The results show that the DC electric conductivity is not a monotonic function of the effective impurity parameter $\beta$: in the small $\beta$ limit, the DC conductivity is dominated by the coherent phase, while for larger $\beta$, pair creation contribution to the conductivity becomes dominant, signaling an incoherent phase. In addition, the DC heat conductivity is found independent of the Gauss-Bonnet coupling constant.Comment: 1+19 pages, 2 figures,typos in Eq.(40) correcte

Financial market integration and the value of global diversification: evidence from US acquirers in cross-border mergers and acquisitions

Using theories of internal capital markets, this paper examines the link between financial market integration and the value of global diversification. Based on a sample of 1,491 completed cross-border mergers and acquisitions (M&As) conducted by US acquirers during the 1990–2003 period, we find that, in general, US shareholders gain significant positive abnormal returns following the announcement of the merger/acquisition. Specifically, firms that acquire/merge with targets from countries with financially segmented markets experience significantly higher positive abnormal returns than those that acquire/merge with targets from countries with financially integrated capital markets. We find that the significantly higher positive returns are driven particularly by deals between firms from unrelated industries. These firms with higher announcement returns are also characterized by positive and significant post-merger operating performance. This finding is consistent with our event study results and suggests that the overall improvement in the merged firms’ performance is likely due to the influx of internal capital from wholly integrated acquirers to segmented targets, firms that, on average are usually faced with higher capital constraints.financial market integration; global diversification; internal capital markets; mergers; acquisitions

Political connections and the process of going public: evidence from China

We examine how political connections impact the process of going public. Specifically, we test how political connections impact the pricing of newly offered shares, the magnitude of underpricing, and the fixed cost of going public. Based on experiences of the new public firms in the Chinese security markets and using multiple measures of political connections, we find robust evidence that issuing firms with political connections reap significant preferential benefits from going public. To be specific, we find that firms – irrespective of ownership arrangements – with greater political connections have higher offering prices, less underpricing, and lower fixed costs during the going-public process.political connections; IPO; emerging markets