Evolution of central pattern generators for the control of a five-link bipedal walking mechanism

Central pattern generators (CPGs), with a basis is neurophysiological studies, are a type of neural network for the generation of rhythmic motion. While CPGs are being increasingly used in robot control, most applications are hand-tuned for a specific task and it is acknowledged in the field that generic methods and design principles for creating individual networks for a given task are lacking. This study presents an approach where the connectivity and oscillatory parameters of a CPG network are determined by an evolutionary algorithm with fitness evaluations in a realistic simulation with accurate physics. We apply this technique to a five-link planar walking mechanism to demonstrate its feasibility and performance. In addition, to see whether results from simulation can be acceptably transferred to real robot hardware, the best evolved CPG network is also tested on a real mechanism. Our results also confirm that the biologically inspired CPG model is well suited for legged locomotion, since a diverse manifestation of networks have been observed to succeed in fitness simulations during evolution.Comment: 11 pages, 9 figures; substantial revision of content, organization, and quantitative result

Sociobiological Control of Plasmid copy number

Background:
All known mechanisms and genes responsible for the regulation of plasmid replication lie with the plasmid rather than the chromosome. It is possible therefore that there can be copy-up mutants. Copy-up mutants will have within host selective advantage. This would eventually result into instability of bacteria-plasmid association. In spite of this possibility low copy number plasmids appear to exist stably in host populations. We examined this paradox using a computer simulation model.

Model:
Our multilevel selection model assumes a wild type with tightly regulated replication to ensure low copy number. A mutant with slightly relaxed replication regulation can act as a “cheater” or “selfish” plasmid and can enjoy a greater within-host-fitness. However the host of a cheater plasmid has to pay a greater cost. As a result, in host level competition, host cell with low copy number plasmid has a greater fitness. Furthermore, another mutant that has lost the genes required for conjugation was introduced in the model. The non-conjugal mutant was assumed to undergo conjugal transfer in the presence of another conjugal plasmid in the host cell.

Results:
The simulatons showed that if the cost of carrying a plasmid was low, the copy-up mutant could drive the wild type to extinction or very low frequencies. Consequently, another mutant with a higher copy number could invade the first invader. This process could result into an increasing copy number. However above a certain copy number within-host selection was overcompensated by host level selection leading to a rock-paper-scissor (RPS) like situation. The RPS situation allowed the coexistence of high and low copy number plasmids. The non-conjugal “hypercheaters” could further arrest the copy numbers to a substantially lower level.

Conclusions:
These sociobiological interactions might explain the stability of copy numbers better than molecular mechanisms of replication regulation alone

Tamanho amostral na identificação de subpopulações espermáticas em carneiros Santa Inês.

A cinética espermática é importante por estar correlacionada positivamente com a fertilidade do sêmen. Estudos de cinética utilizam ferramentas estatísticas multivariadas para incrementar a acurácia na identificação de subpopulações espermáticas em ovinos; assim o tamanho amostral é importante na variabilidade do agrupamento de células. Objetivou-se estudar a influência do n amostral aleatório na identificação de subpopulações espermáticas. Foi utilizado o banco de informações digitais da análise seminal feita em 35 carneiros adultos no Laboratório de Biotecnologia da Reprodução Animal ? Embrapa Tabuleiros Costeiros; constituindo um total de 77070 observações espermáticas contendo dados de velocidades curvilínea (VCL), em linha reta (VSL) e do percurso médio (VAP), linearidade (LIN), retilinearidade (STR), índice de oscilação (WOB), deslocamento lateral da cabeça (ALH) e batimento flagelar Cruzado (BCF) dos espermatozoides. Foi utilizada a metodologia estatística de análise dos componentes principais sendo testados diferentes n amostrais: 10, 50, 100, 250, 500, 750, 1000, 1500, 2000, 3000, 5000 e 15000. A influência do n amostral na identificação de subpopulações espermáticas em carneiros Santa Inês, considerando cinco parâmetros cinéticos espermáticos foi significativa (p<0,05), onde o n amostral abaixo de 50 espermatozoides avaliados mostrou uma maior variabilidade numérica comparada aos outros tamanhos amostrais. Conclui-se que para identificar subpopulações espermáticas homogêneas, pode ser simulado o n amostral igual ou maior de 50 espermatozoides selecionados aleatoriamente e com pelo menos 10 repetições

Stomatal Density and its Relationship with Yield of Radish (Raphanus Sativus L.) Fertilized with Biol Produced from Sugar Cane Residues

The impact of agro-industrial waste can be reduced by using it in crop fertilization. The aim of this study was to evaluate the stomatal density and yield of radish (Raphanus Sativus L.) fertilized with biol at different concentrations, produced from sugar cane residues. A completely randomized blocks design statistical model was used, which consisted of 5 tests with 3 repetitions for each one, being T1 the control trial, and T2, T3, T4 and T5 the treatments using 2, 3, 4 and 5 L of biol in 200 L of water respectively. In terms of crop physical characteristics, the T5 treatment excelled in plant length, equatorial diameter, plant weight, as well as yield with 12.71 t/ha. Likewise, in the chemical analysis of the radish leaves, the T5 treatment showed an increase in K, Ca, Zn and MN, while the T2 did it in N, P and Cu, the T3 in Fe and the T4 in Mg. In terms of stomatal density, T5 stood out with 122 stomatal/mm2. Based on this, it is concluded that the increase in the dose of biol influences the increase in nutrient and stomatal density and hence the yield of the radish crop

Engineering of III-Nitride Semiconductors on Low Temperature Co-fired Ceramics

This work presents results in the feld of advanced substrate solutions in order to achieve high crystalline quality group-III nitrides based heterostructures for high frequency and power devices or for sensor applications. With that objective, Low Temperature Co-fred Ceramics has been used, as a noncrystalline substrate. Structures like these have never been developed before, and for economic reasons will represent a groundbreaking material in these felds of Electronic. In this sense, the report presents the characterization through various techniques of three series of specimens where GaN was deposited on this ceramic composite, using diferent bufer layers, and a singular metal-organic chemical vapor deposition related technique for low temperature deposition. Other single crystalline ceramic-based templates were also utilized as substrate materials, for comparison purposes