Ant colony optimization, which is one of the metaheuristics imitating real ant foraging behavior, is an effective method to find a solution for the traveling salesman problem. The rank-based ant system has been proposed as a developed version of the fundamental model AS of ACO. In the ASrank, since only ant agents that have found one of some excellent solutions are let to regulate the pheromone, the pheromone concentrates on a specific route. As a result, although the ASrank can find (...) a relatively good solution in a short time, it has the disadvantage of being prone falling into a local solution because the pheromone concentrates on a specific route. This problem seems to come from the loss of diversity in route selection according to the rapid accumulation of pheromones to the specific routes. Some ACO models, not just the ASrank, also suffer from this problem of loss of diversity in route selection. It can be considered that the diversity of solutions as well as the selection of solutions is an important factor in the solution system by swarm intelligence such as ACO. In this paper, to solve this problem, we introduce the ant system using individual memories aiming to improve the ability to solve TSP while maintaining the diversity of the behavior of each ant. We apply the existing ACO algorithms and ASIM to some TSP benchmarks and compare the ability to solve TSP. (shrink)

The Komori–Kashima problem, that asks whether the implicational intermediate logics axiomatizable by formulas minimal in classical logic are only intuitionistic logic and classical logic, has stood for over a decade. In this paper, we give a counter-example to this problem. Additionally, we also give some open problems derived from this result.

Microbial ecology is flourishing, and in the process, is making contributions to how the ecology and biology of large organisms is understood. Ongoing advances in sequencing technology and computational methods have enabled the collection and analysis of vast amounts of molecular data from diverse biological communities. While early studies focused on cataloguing microbial biodiversity in environments ranging from simple marine ecosystems to complex soil ecologies, more recent research is concerned with community functions and their dynamics over time. Models and concepts (...) from traditional ecology have been used to generate new insight into microbial communities, and novel system-level models developed to explain and predict microbial interactions. The process of moving from molecular inventories to functional understanding is complex and challenging, and never more so than when many thousands of dynamic interactions are the phenomena of interest. We outline the process of how epistemic transitions are made from producing catalogues of molecules to achieving functional and predictive insight, and show how those insights not only revolutionize what is known about biological systems but also about how to do biology itself. Examples will be drawn primarily from analyses of different human microbiota, which are the microbial consortia found in and on areas of the human body, and their associated microbiomes (the genes of those communities). Molecular knowledge of these microbiomes is transforming microbiological knowledge, as well as broader aspects of human biology, health and disease. (shrink)

In 1981, the Atlantic Council's Energy Policy Committee, in collaboration with the Japanese Committee for Energy Policy Promotion and the Japanese Institute of Energy Economics, published a joint policy paper entitled 'U.S.-Japan Energy Relationships in the 1980s.'.

国学考証派の登場と学問領域を築き深化させた過程を、考証の方法や実践などに着目して追究。近代の実証的学問への継承まで論じる。.

This study is aimed to address the problems associated with questionnaire-based research. Twelve hypothetical cases are presented and checked for ethical validity. The problems are categorized under seven headings: Whether the participation of the subject is truly voluntary; whether consent to participate in the study has been obtained or proxy consent is required; whether consent to participate has been obtained from "authentic" participants and their privacy is protected; whether participants are fully informed before they consent to participate; whether the validity (...) of questionnaire-based research has been determined in terms of its possible harm; how the roles of the research ethics committee are defined; and what content should be presented in reports and articles. It is important that the ethics of questionnaire-based research should be reviewed with consideration to maintaining a balance between the protection of a subject's human rights and the promotion of research for the improvement of medical science and health care. (shrink)

The identification of Smad proteins as molecular components of the transforming growth factor-β (TGF-β) signaling cascade has enhanced our understanding of how ligand-mediated activation of TGF-β receptors leads to modulation of target gene transcription. Recent studies have identified a distinct, structurally related class of Smads which inhibits, rather than transduces, TGF-β family signals. The molecular mechanism of action and the exact signaling pathways that are targeted by antagonistic Smads are not completely understood. These proteins appear to participate in autoregulatory negative (...) feedback loops in which signaling initiated by specific TGF-β family ligands induces the expression of an inhibitory Smad that then functions to modulate the amplitude or duration of signaling. Negative feedback circuits such as these play important roles in fine-tuning the activity of multifunctional signaling molecules during embryonic patterning and in response to pathologic stimuli in adults. BioEssays 21:382–390, 1999. © 1999 John Wiley & Sons, Inc. (shrink)

Specificities of enzymes involved in plant specialized metabolism, including flavonoid biosynthesis, are generally promiscuous. This enzyme promiscuity has served as an evolutionary basis for new enzyme functions and metabolic pathways in land plants adapting to environmental challenges. This phenomenon may lead, however, to inefficiency in specialized metabolism and adversely affect metabolite‐mediated plant survival. How plants manage enzyme promiscuity for efficient specialized metabolism is, thus, an open question. Recent studies of flavonoid biosynthesis addressing this issue have revealed a conserved strategy, namely, (...) a homolog of chalcone isomerase with no catalytic activity binds to chalcone synthase, a key flavonoid pathway enzyme, to narrow (or rectify) the enzyme's highly promiscuous product specificity. Reducing promiscuity via specific protein–protein interactions among metabolic enzymes and proteins may be a solution adopted by land plants to achieve efficient operation of specialized metabolism, while the intrinsic promiscuity of enzymes has likely been retained incidentally. (shrink)

Trata-se de uma resenha da tradução de Celi Hirata das Questões sobre a Liberdade, a Necessidade e o Acaso de Thomas Hobbes.