in this work, we investigate the transfer of some homological properties from a ring $r$ to its amalgamated duplication along some ideal $i$ of $r$ $rbowtie i$, and then generate new and original families of rings with these properties.

Abs t r ac t . We consider a restricted variant of the prefix-sufñx duplication operation, called bounded prefix-sufñx duplication. It consists in the iterative duplication of a prefix or suffix, whose length is bounded by a constant, of a given word. We give a sufncient condition for the closure under bounded prefix-sufñx duplication of a class of languages. Consequently, the class of regular ...

We present a novel approach to deal with the problem of reconstructing the duplication history of tandemly repeated genes that are supposed to have arisen from unequal recombination. We first describe the mathematical model of evolution by tandem duplication and introduce duplication histories and duplication trees. We then provide a simple recursive algorithm which determines whether or not a ...

Salmonella typhimurium strains containing a duplication of nearly a third of the genome have been isolated by a simple procedure involving selection for improved utilization of L-malate as sole carbon source. The duplication occurs at a very high spontaneous frequency. Strains containing the duplication can be isolated selectively on malate medium, or by a non-selective procedure involving Hfr ...

Duplication is thought to be one of the main processes providing a substrate on which the effects of evolution are visible. The mechanisms underlying this chromosomal rearrangement were investigated here in the yeast Saccharomyces cerevisiae. Spontaneous revertants containing a duplication event were selected and analyzed. In addition to the single gene duplication described in a previous study...

Duplication is an operation generating a language from a single word by iterated application of rewriting rules u → uu on factors. We extend this operation to entire languages and investigate, whether the classes of the Chomsky hierarchy are closed under duplication. Here we treat mainly bounded duplication, where the factors duplicated cannot exceed a given length. While over two letters the r...

Pyloroduodenal duplication is the rarest alimentary tract duplication known so far. A 1-year-old female patient presented with abdominal pain, lump in the epigastrium and occasional vomiting. On ultrasound and CT scan of abdomen suspicion of duplication cyst was made. Operation revealed a duplication cyst along pylorus and first part of the duodenum. Excision of free part and mucosal stripping ...

In this paper, we present the JUCSE system, designed for the TempEval-3 shared task. The system extracts events and temporal information from natural text in English. We have participated in all the tasks of TempEval-3, namely Task A, Task B & Task C. We have primarily utilized the Conditional Random Field (CRF) based machine learning technique, for all the above tasks. Our system seems to perf...

There is an extensive literature on task modelling related to the design of computer systems. Task analysis and task modelling have been widely recognized as central components in human-centred approaches. The aim of this paper is to report on some results of a worldwide survey about actual practices of task descriptions languages (TDL) in SIGCHI community. Results suggest that academic TDL are...