Optimal Sparse Matrix Dense Vector Multiplication in the I/O-Model

We study the problem of sparse-matrix dense-vector multiplication (SpMV) in external memory. The task of SpMV is to compute y:=Ax, where A is a sparse N×N matrix and x is a vector. We express sparsity by a parameter k, and for each choice of k consider the class of matrices where the number of nonzero entries is kN, i.e., where the average number of nonzero entries per column is k.     

A genetic algorithm approach for group formation in collaborative learning considering multiple student characteristics

Considering that group formation is one of the key processes in collaborative learning, the aim of this paper is to propose a method based on a genetic algorithm approach for achieving inter-homogeneous and intra-heterogeneous groups. The main feature of such a method is that it allows for the consideration of as many student characteristics as may be desired, translating the grouping problem into one of multi-objective optimization. In order to validate our approach, an experiment was designed with 135 college freshmen considering three characteristics: an estimate of student knowledge levels, an estimate of student communicative skills, and an estimate of student leadership skills. Results of such an experiment allowed for the validation, not only from the computational point of view by measuring the algorithmic performance, but also from the pedagogical point of view by measuring student outcomes, and comparing them with two traditional group formation strategies: random and self-organized.     

Reading and Phonological Awareness in Williams Syndrome.

This article describes the relationship between reading, phonological awareness abilities (PA), and intelligence in a group of 16 individuals with Williams syndrome (WS) and in a group of 16 typically developing children, matched for mental age. The individuals with WS were impaired in passage comprehension, in some areas of PA investigated (syllable deletion and rhyme detection), and in nonword reading accuracy, a measure of grapheme-phoneme conversion. This latter finding is relevant, considering that in Italy regular print-to-sound correspondence is the most practiced teaching routine in the early phases of learning to read. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Lyoprotected nanosphere formulations for paclitaxel controlled delivery

The preparation and technological characterization of nanosphere formulations (NS) containing the anticancer drug paclitaxel (PTX) are reported. Poly(lactide) (PLA) and poly(lactide-co-glycolide) (PLGA) nanospheres (NS) were prepared by a solvent displacement method. They showed a mean particle size in the range 150-300 nm, with a high homogeneity (polydispersity index < 0.3). For long term stability, NS require additional procedures, such as freeze-drying. In this study, the effect on NS particle size and surface charge of different lyoprotectants (mono- and disaccharides, polyalcohols, and hydroxypropyl-beta-cyclodextrin) at various concentrations was tested by means of light scattering size analysis. The formulations freeze-dried with the addition of 10% glucose (w/v) showed interesting characteristics after freeze-drying. They were chosen for specific studies on drug encapsulation efficiency, in vitro drug release and biological activity on the human anaplastic thyroid carcinoma cell line 8305C. The PLGA NS, in particular, showed a cell growth inhibitory activity comparable to the free drug.     

Language in Italian children with Down syndrome and with specific language impairment.

This article compares lexical and grammatical abilities of a mental-age-matched sample of Italian preschoolers with Down syndrome (DS), specific language impairment (SLI), or typical development. Results showed that the children with DS or with SLI performed significantly worse than did the typically developing children. Although no significant differences emerged in lexical abilities and morphosyntactic comprehension abilities between the children with DS or with SLI, significant differences did emerge in morphosyntactic production capacities. Qualitative analysis of the morphosyntactic errors revealed strong similarities between the two groups. The results are discussed in terms of the role of verbal memory abilities and the linguistic features of Italian. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spatial and temporal coherence of filtered thermal light

When a filter is placed in front of a double slit illuminated by a primary source of finite extent, the theory of partial coherence predicts that in general the interference fringes do not acquire unit visibility even as the passband of the filter is made arbitrarily narrow. The effect of reducing the filter bandwidth is that the visibility of the fringes tends to the modulus of the spectral degree of coherence and that more interference fringes become visible. A systematic experimental verification of these theoretical predictions is lacking so far and is provided here from the use of a highly sensitive CCD camera.     

Dynamic thermal behaviour of a wall

A new technique for dealing with the problem of the numerical simulation of heat conduction in solids is presented. This method is based on that of Milne but does not have any limitation in the time step amplitude. It has, therefore, the advantage of being more accurate and requires less computational time than the traditional methods. The mathematics of the method are shown and a comparison with the Crank-Nicolson technique is made.