We develop and experiment with a new parallel algorithm to approximate the maximum weight cut in a weighted undirected graph. Our implementation starts with the recent (serial) algorithm of Goemans and Williamson for this problem. We consider several different versions of this algorithm, varying the interior-point part of the algorithm in order to optimize the parallel efficiency of our method....

We propose a new randomized pruning method (called “submodular sparsification (SS)”) to reduce the cost of submodular maximization. The pruning is applied via a “submodularity graph” over the n ground elements, where each directed edge is associated with a pairwise dependency defined by the submodular function. In each step, SS prunes a 1 1/ p c (for c > 1) fraction of the nodes using weights o...

This paper addresses the problem of designing parallel message passing programs with a reasonable idea of how well they will actually perform before they are run. Models with very few parameters (e.g. LogP, PRAM) sacrifice accuracy to simplify design. By contrast, simulation techniques provide a good degree of accuracy by incorporating sophisticated architectural models, but present a “black bo...

In this work was designed to investigate the effects of two steroid-dihydropyrimidine derivatives on glucose levels in a rat diabetic model. Additionally, to delineate the structural chemical requirements of the dihydropyrimidine derivatives as antidiabetic agents; several parameters such as, the descriptors LogP and π were calculated. The results showed that dihydrotestosterone-dihydropyrimidi...

The tomographic reconstruction for cone-beam geometries is a computationally intensive task requiring large memory and computational power to investigate interesting objects. The analysis of its parallel implementation on widely available clusters of SMPs requires an extension of the original LogP model to account for the various communication channels, called LogSMP. The LogSMP model is used i...

In metal-based photoactivated chemotherapy (PACT), two photoproducts are generated by light-triggered photosubstitution of a metal-bound ligand: the free ligand itself and an aquated metal complex. By analogy with cisplatin, the aquated metal complex is usually presented as the biologically active species, as it can typically bind to DNA. In this work, we show that this qualitative assumption i...

We present the results of a comprehensive theoretical investigation on the Period-Radius (PR) relation of classical Cepheids based on new sequences of full amplitude, nonlinear convective models constructed by adopting a wide range of both stellar masses and chemical compositions. In the period range 0.9 ≤ logP ≤ 1.8 a very good agreement is found between theoretical predictions and current ava...

Designing new and optimal algorithms for a specific architecture requires accurate modelling of this architecture. This is especially needed to choose one out of different solutions for the same problem or to proof a lower bound to a problem. Assumed that the model is highly accurate, a given algorithm can be seen as optimal solution if it reaches the lower bound. Therefore the accuracy of a mo...

The performance of the barrier operation can be crucial for many parallel codes. Especially distributed shared memory systems have to synchronize frequently to ensure the proper ordering of memory accesses. The barrier operation is often performed on top of point-to-point messages and the best algorithm scales with O(log2P · L) in the LogP model. We propose a cheap hardware extension which is a...

Let {Zt, t ≥ 0} be a strictly stable process on R with index α ∈ (0, 2]. We prove that for every p > α, there exists γ = γ(α, p) and K = K(α, p) ∈ (0,+∞) such that lim ε↓0 ε logP [||Z||p ≤ ε] = −K, where ||Z||p stands for the strong p-variation of Z on [0, 1]. The critical exponent γ(α, p) takes a different shape according as |Z| is a subordinator and p > 1, or not. The small ball constant K(α,...