K Shortest Path Implementation

The problem of computing K shortest loopless paths, or ranking of the K shortest loopless paths between a pair of given vertices in a network is a well-studied generalization of shortest path problem. The K shortest paths problem determines not only one shortest path but the K best shortest paths from s to t in an increasing order of weight of the paths. Yen’s algorithm is known to be the efficient and widely used algorithm for determining K shortest loopless paths. Here, we introduce a new algorithm by modifying the Yen’s algorithm in the following way: instead of removing the vertices and the edges from the graph, we store them in two different sets. Then we modified the Dijkstra’s algorithm by taking these two sets into consideration. Thus the algorithm applies glass box methodology by using the modified Dijkstra’s algorithm for our dedicated purpose. Thus the efficiency is improved. The computational results conducted over different datasets, shows the proposed algorithm has better performance results

La determinación del sexo en Cícadas (Cycadales)

Plants are organisms that offer unique reproductive systems to study sex determination, in other words, the expression of masculinity or femininity. Within the plant kingdom, the separation of sex has emerged over the evolutionary history in more than one hundred occasions. With each new phylogenetically-independent event there is a new reproductive system which may be similar or completely different from the previous system, so in plants there is not an only one mechanism to explain the dioecism. Cycads are a group of primitive dioecious plants that offers an extraordinary opportunity to study the emergence of dioecism in plant species. Several studies have shown that sex in cycads may be determined by homomorphic or heteromorphic sexual chromosomes; although the possibility of epigenetic factors influencing sex determination in these plants cannot be ruled out. The possibility to anticipate the sex of the cycads would allow us to establish management plans focused to the production of quality seeds in sufficient quantity to meet the demand for these ornamental plants