У The problem of distribution of a set of objects, the state of which is determined by a set of controlled parameters, into a set of subsets of objects maximally homogeneous in their properties is ...considered. Relevance of the problem and important advantage of the clustering procedure: when its implementing it is possible to reduce the initial difficult problem of high dimensionality objects analysing to the solution of a number of simpler problems of lower dimensionality. This circumstance acquires additional attractiveness and importance if the initial data of the problem contain uncertainty, for example, are vaguely defined. Research object is the procedure of partitioning a set of objects into clusters under conditions of uncertainty. In this regard, the purpose of the study is to develop a method for solving the problem of clustering in conditions where the initial data on objects controlled parametersthe values contain uncertainty. The method of solving the problem is based on clustering procedure mathematical model development, containing analytical expressions for the criterion of its effectiveness, written in the form of a twice fractionally quadratic function. The impossibility of mathematical programming problem direct solution initiated the development of a heuristic algorithm for its solution. As a result, an iterative method was obtained and applied to solve the clustering problem under conditions of fuzzy initial data. The developed computational procedure is based on a reasonable system of rules for performing operations on fuzzy numbers. The situations when the belonging functions of problem fuzzy parameters are defined on infinite or compact media are considered. The developed system of rules allows to correctly perform operations in the metric of fuzzy defined states between clustering objects. The proposed method is easily generalised to the case when the uncertainty of the initial data is hierarchical.
Biological hydrogen production by anaerobic mixed communities was studied in laboratory-scale bioreactors using sucrose as the substrate. A bioreactor in which a fraction of the return sludge was ...exposed to repeated heat treatments performed better than a control bioreactor without repeated heat treatment of return sludge and produced a yield of 2.15 moles of hydrogen per mole of sucrose, with 50% hydrogen in the biogas. Terminal restriction fragment length polymorphism analysis showed that two different Clostridium groups (comprised of one or more species) were dominant during hydrogen production. The relative abundance of two other non-Clostridium groups increased during periods of decreased hydrogen production. The first group consisted of Bifidobacterium thermophilum, and the second group included one or more of Bacillus, Melissococcus, Spirochaeta, and Spiroplasma spp.
The oligonucleotide probe database ALM, E. W; OERTHER, D. B; LARSEN, N ...
Applied and environmental microbiology,
10/1996, Letnik:
62, Številka:
10
Journal Article
Recenzirano
Odprti dostop
In the fields of microbial ecology and environmental microbiology, the use of oligonucleotide hybridization probes and PCR primers has become widespread. Alm et al developed the Oligonucleotide Probe ...Database (OPD) to address some concerns concerning information on probes and primers.
Raskin L, Schwenter F, Freytsis M, Tischkowitz M, Wong N, Chong G, Narod SA, Levine DA, Bogomolniy F, Aronson M, Thibodeau SN, Hunt KS, Rennert G, Gallinger S, Gruber SB, Foulkes WD. Characterization ...of two Ashkenazi Jewish founder mutations in MSH6 gene causing Lynch syndrome.
Founder mutations are an important cause of Lynch syndrome and facilitate genetic testing in specific ethnic populations. Two putative founder mutations in MSH6 were analyzed in 2685 colorectal cancer (CRC) cases, 337 endometrial cancer (EnCa) cases and 3310 healthy controls of Ashkenazi Jewish (AJ) descent from population‐based and hospital‐based case–control studies in Israel, Canada and the United States. The carriers were haplotyped and the age of the mutations was estimated. MSH6*c.3984_3987dupGTCA was found in 8/2685 CRC cases, 2/337 EnCa cases, and 1/3310 controls, consistent with a high risk of CRC (odds ratio (OR) = 9.9, 95% confidence interval (CI) = 1.2–78.9, p = 0.0079) and a very high risk of EnCa (OR = 19.6, 95%CI = 1.8–217.2, p = 0.0006). MSH6*c.3959_3962delCAAG was identified in 3/2685 CRC cases, 2/337 EnCa cases and no controls. Each mutation was observed on separate conserved haplotypes. MSH6*c.3984_3987dupGTCA and MSH6*c.3959_3962delCAAG probably arose around 585 CE and 685 CE, respectively. No carriers were identified in Sephardi Jews (450 cases and 490 controls). Truncating mutations MSH6*c.3984_3987dupGTCA and MSH6*c.3959_3962delCAAG cause Lynch syndrome and are founder mutations in Ashkenazi Jews. Together with other AJ founder mutations, they contribute substantially to the incidence of CRC and EnCa and are important tools for the early diagnosis and appropriate management of AJ Lynch syndrome patients.
The availability of molecular biological tools for studying microbial communities in bioreactors and other engineered systems has resulted in remarkable insights linking diversity and dynamics to ...process stability. As engineered systems are often more manageable than large-scale ecosystems, and because parallels between engineered environments and other ecosystems exist, the former can be used to elucidate some unresolved ecological issues. For example, the process stability of methanogenic bioreactors containing well-defined trophic groups appears to depend on the diversity of the functional groups within each trophic level as well as on how these functional groups complement each other. In addition to using engineered systems to study general ecological questions, microbial ecologists and environmental engineers need to investigate conditions, processes, and interactions in engineered environments in order to make the ecological engineering of bioreactor design and operation more practicable.
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