Search

A novel symmetric cryptosystem of the substitution permutation network type is presented for image encryption in 14 rounds. An algorithm is developed to generate 15 keys to encrypt images where each key is the image size. These keys are calculated using an elliptic curve with a constant zero value. The proposed curve is non-singular, non-supersingular, nor trace one. Chaos is employed to find a generating element in a cyclic subgroup and it is produced using the logistic map equation. In addition, a 16 × 16 substitution box is constructed using both chaos and an algorithm that defines a bijective function. The following tools are used in order to measure the degree of randomness of the encrypted figures: entropy, correlation, the discrete Fourier transform and a goodness-of-fit test with the chi-square distribution. Furthermore, an image size variable permutation is applied in the first round, and its inverse in the fourteenth.

Let Kbe a finite field. Let X*be a subset of the a ne space Kn, which is parameterized by odd cycles. In this paper we give an explicit Gröbner basis for the vanishing ideal, I(X*), of X*. We give an explicit formula for the regularity of I(X*) and finally if X*is parameterized by an odd cycle of length k, we show that the Hilbert function of the vanishing ideal of X*can be written as linear combination of Hilbert functions of degenerate torus.

We introduce a computational agent‐based model of innovation diffusion that allows us to analyse the influence of information and communication technology (ICT) development on decision‐making. Model dynamics are based on local emulation between pairs of individuals that generate an evolving social network on which an innovation is virally spread (by word of mouth). Results suggest that ICT development affects the data usefulness for decision‐making by changing the topology of the social network (the means whereby the innovation is propagated). Paradoxically, a higher level of ICT development (providing a larger volume of data) narrows the differences between better and worse launch strategies, thus reducing data‐driven decision‐making usefulness, which then shows diminishing returns on the ICT level.

En este artículo se propone un análisis comparado entre los artistas brasileños Graciliano Ramos y Candido Portinari a partir de la forma en que ambos realizan estructuralmente la construcción corporal y el problema de la identidad. Se comenzará por revisar la manera en que ambos abordan su propia corporeidad para después contrastar esto con otros ejemplos extraídos de sus propias obras. Además se revisará la forma en que el cuerpo se relaciona con el espacio a fin de determinar cómo la simbiosis entre los dos sirve como mecanismo de expresión al ser humano.

In this paper we estimate the main parameters of some evaluation codes which are known as projective parameterized codes. We find the length of these codes and we give a formula for the dimension in terms of the Hilbert function associated to two ideals, one of them being the vanishing ideal of the projective torus. Also we find an upper bound for the minimum distance and, in some cases, we give some lower bounds for the regularity index and the minimum distance. These lower bounds work in several cases, particularly for any projective parameterized code associated to the incidence matrix of uniform clutters and then they work in the case of graphs.

The karyotypes of 2 northeastern Pacific abalone species, Haliotis fulgens and H. rufescens, were evaluated from trochophore larvae cells, finding that for both species the diploid number is 36. There were differences between the two species in karyotype according to centromere position classification. H. fulgens karyotype was composed by 10 pairs of metacentric, 3 pairs of metacentric-submetacentric, 4 pairs of submetacentric, and 1 pair of submetacentric-subtelocentric chromosomes, and H. rufescens karyotypes by 8 pairs of metacentric, 6 pairs of metacentric-submetacentric, 3 pairs of submetacentric, and 1 pair of submetacentric-subtelocentric chromosomes. The relative length of chromosomes 1 to 18 was not different between the species, but 5 of their chromosomes (numbers 4, 7, 9, 11, & 18) were significantly different in relative lengths of short and long arm and in centromeric index, differences that can be explained by pericentric inversions. These observed differences in karyotype between the two species support the previous contention of evolutionary divergence by lysine studies. The chromosome number of the two species evaluated was the same than that reported for other abalones distributed in the northeast Pacific (H. cracherodii) and other abalone species distributed in the west Pacific (H. discus, H. gigantea, and H. madaka), although as between these two species, the karyotype of those previously described was also different. [ABSTRACT FROM AUTHOR]

Current data support the notion that the thymus is seeded by a yet uncommitted progenitor cell able to generate T cells, B cells, natural killer (NK) cells, and dendritic cells (DCs). We assess in this report the developmental relationship of DCs and NK cells derived from a small subset of CD34+ human postnatal thymocytes that, like the earliest precursors in the fetal thymus, display low CD33 surface expression. Culture of these isolated CD34+CD33lo thymic progenitors with a mixture of cytokines, including interleukin-7 (IL-7), IL-1α, IL-6, granulocyte-macrophage colony-stimulating factor, and stem cell factor, results in predominant generation of DCs. However, the addition of IL-2 to the cytokine mixture leads to the simultaneous development of DCs and NK cells. Both developmental pathways progress through a transient population of CD34+CD44brightCD5lo/−CD33+ large-sized cells, distinct from small-sized T-lineage precursors, that contain bipotential NK/DC progenitors. These data provide evidence of linked pathways of NK cell and DC development from intrathymic precursors and suggest that NK cells and DCs branch off the T lineage through a common intermediate progenitor.

Current data support the notion that the thymus is seeded by a yet uncommitted progenitor cell able to generate T cells, B cells, natural killer (NK) cells, and dendritic cells (DCs). We assess in this report the developmental relationship of DCs and NK cells derived from a small subset of CD34+human postnatal thymocytes that, like the earliest precursors in the fetal thymus, display low CD33 surface expression. Culture of these isolated CD34+CD33lothymic progenitors with a mixture of cytokines, including interleukin-7 (IL-7), IL-1α, IL-6, granulocyte-macrophage colony-stimulating factor, and stem cell factor, results in predominant generation of DCs. However, the addition of IL-2 to the cytokine mixture leads to the simultaneous development of DCs and NK cells. Both developmental pathways progress through a transient population of CD34+CD44brightCD5lo/−CD33+large-sized cells, distinct from small-sized T-lineage precursors, that contain bipotential NK/DC progenitors. These data provide evidence of linked pathways of NK cell and DC development from intrathymic precursors and suggest that NK cells and DCs branch off the T lineage through a common intermediate progenitor.