Regenerasi Fungsi x2-9x-99 Dalam Pembangkit Bilangan Acak Berbasis CSRPNG Chaos

This study examines whether the function f(x)=x2-9x-99 can be used as a key generator in cryptography. The quadratic function is regenerated using the fixed point iteration method into an iteration function. The distribution of digits to the output of iterative function to generate a number of chaos. Randomization testing uses run test and monobit testing. Followed by cryptographic testing to get the correlation between ciphertext and key which will be used as a decision whether the resulting key is random or not. Based on research that has been done iteration function xi = (xi-12-9xi-1-99)/9 can generate CSRPNG Chaos random numbers with the correlation level closest to the value of 0.

Effect of high temperature on germination of four legumes from a forest-grassland mosaic in Southern Brazil

Passage of a fire can break dormancy of the seeds of many plant species in fire-prone ecosystems. This response to fire is especially well known for the Fabaceae family, but has been poorly studied in Southern Brazil. We collected seeds of four Fabaceae species present in grasslands-forest mosaics of Southern Brazil: Mimosa bimucronata, Desmodium barbatum, Sesbania virgata and Collaea stenophylla. Seeds were exposed to different heat treatments (exposure to 60° and 80 °C for 5 minutes, to 100 °C for 2 minutes, control without heat treatment); not all species were tested in all treatments. After the treatment, the seeds were kept in a germination chamber with a light period of 12/12 hours and temperature of 25 °C. Germinated seeds were counted every 2 days. The results were analyzed by randomization testing. Germination of D. barbatum and S. virgata was increased after exposure to high temperatures (80° and 60 °C, respectively), while M. bimucronata showed reduced germination after temperatures of 80 °C and C. stenophylla no response. This study is the first for Southern Brazil to show a positive response of germination for grassland species exposed to high temperatures, simulating fire effects. As the study presented distinct responses of species to the heat treatment, it seems important to conduct more works with other species from the family, in order to be able to detect more general patterns.

Spatial patterns and relations with site factors in a campos grassland under grazing

Spatial distribution patterns and their relations with environmental factors at different scales were identified in ca. 100-ha grassland under cattle and sheep grazing, in Eldorado do Sul, RS, Brazil (30º05'S, 51º40'W). The field survey used 138 0.5 x 0.5 m quadrats located systematically on transects along relief gradients. The quadrats were arranged in groups of 3 contiguous quadrats, which were pooled for the analysis, thus forming 46 quadrats 1.5 x 0.5 m, in this way defining two observation scales. Vegetation description involved recording the presence and the visual estimation of cover-abundance of species in each quadrat. A total of 148 species belonging to 30 families was detected. The environmental conditions at each site were described by 30 variables related to soil chemical and physical properties, slope, exposure and relief position. Data analysis used cluster analysis, evaluation of group partition sharpness, ordination, significance of ordination axes, evaluation of environmental congruence and randomization testing. The results of the analysis with 46 quadrats supported those found with 138 quadrats. The vegetation patterns in the study area are associated to relief position and other related factors such as soil moisture. Two clearly defined grassland community types were detected, one occurring on the slopes and another on the wet lowlands.

Use of randomization testing to detect multiple epistatic QTLs

Here, we describe a randomization testing strategy for mapping interacting quantitative trait loci (QTLs). In a forward selection strategy, non-interacting QTLs and simultaneously mapped interacting QTL pairs are added to a total genetic model. Simultaneous mapping of epistatic QTLs increases the power of the mapping strategy by allowing detection of interacting QTL pairs where none of the QTL can be detected by their marginal additive and dominance effects. Randomization testing is used to derive empirical significance thresholds for every model selection step in the procedure. A simulation study was used to evaluate the statistical properties of the proposed randomization tests and for which types of epistasis simultaneous mapping of epistatic QTLs adds power. Least squares regression was used for QTL parameter estimation but any other QTL mapping method can be used. A genetic algorithm was used to search for interacting QTL pairs, which makes the proposed strategy feasible for single processor computers. We believe that this method will facilitate the evaluation of the importance at epistatic interaction among QTLs controlling multifactorial traits and disorders.