Sulla complessità di alcuni problemi di conteggio

This paper is intended to show that an algebraic approach can give useful suggestions to design efficient algorithms solving combinatorial problems. The problems we discusses in the paper are:

1. Counting strings of given length generated by a regular grammar. For this problem, we give an exact algorithm whose complexity is 0 (logn) (with respect to the number of executed operations), and an approximate algorithm which however still has the same order of complexity;
2. counting trees recognized by a tree automaton. For this problem, we give an exact algorithm of complexity 0(n) and an approximate one of complexity 0 (logn). For this approximate algorithm the relative error is shown to be 0 (1/n).

     

GPU-accelerated simulations of mass-action kinetics models with cupSODA

In the last years, graphics processing units (GPUs) witnessed ever growing applications for a wide range of computational analyses in the field of life sciences. Despite its large potentiality, GPU computing risks remaining a niche for specialists, due to the programming and optimization skills it requires. In this work we present cupSODA, a simulator of biological systems that exploits the remarkable memory bandwidth and computational capability of GPUs. cupSODA allows to efficiently execute in parallel large numbers of simulations, which are usually required to investigate the emergent dynamics of a given biological system under different conditions. cupSODA works by automatically deriving the system of ordinary differential equations from a reaction-based mechanistic model, defined according to the mass-action kinetics, and then exploiting the numerical integration algorithm, LSODA. We show that cupSODA can achieve a \(86 \times \) speedup on GPUs with respect to equivalent executions of LSODA on the CPU.     

A simple and robust Simulated Annealing algorithm for scheduling workover rigs on onshore oil fields

Onshore oil wells are dependent of maintenance services such as cleaning, reinstatement and stimulation. These services can be performed by a limited number of workover rigs. Usually, wells need maintenance services and a scheduling of the workover rigs must be defined. This scheduling must consider some factors such as the well production, the type of service to be performed and time windows for the service. There is a production loss associated to wells waiting for maintenance services, so it is important to attend them as soon as possible. Thus, the workover rig scheduling problem consists of finding the best schedule for the limited number of workover rigs, minimizing the production loss associated with the wells waiting for maintenance service. We present a simple and robust Simulated Annealing (SA) algorithm for solving this problem. Computational results on real problems obtained in Brazil are reported and SA presents better solutions than all those approaches reported in the literature.     

Ecotoxicity of naproxen and its phototransformation products

The occurrence of pharmaceuticals in the environment is of great concern and only few data are available about the adverse effects of such molecules and their derivatives on non-target aquatic organisms. This study was designed to assess the toxic potential of Naproxen, a nonsteroidal anti-inflammatory, Naproxen Na, its freely water soluble sodium salt and their photoproducts in the aquatic environment. Bioassays were performed on algae, rotifers and microcrustaceans to assess acute and chronic toxicity. Furthermore, possible genotoxic effects of photoderivatives were investigated using SOS chromotest and Ames fluctuation test. The results showed that photoproducts were more toxic than the parent compounds both for acute and chronic values, while genotoxic and mutagenic effects were not found. These findings suggested the opportunity to consider derivatives in ecotoxicology assessment of drugs.     

Usability,user experience and mental workload in a mobile Augmented Reality application for digital storytelling in cultural heritage

Virtual Reality - Augmented Reality (AR) has become an increasingly used technology to support and enhance the enjoyment of cultural heritage. Particularly relevant is its importance for...