Solid Couplings With Flexible Intermediate Shafts For High Speed Turbocompressor Trains.

LecturePg. 101-110The design and application of solid couplings combined with flexible quill shafts for high speed turbocompressors are presented. Solid couplings are rigid in the axial direction. They transmit any residual thrust from one compressor casing to another, and even into the gear. A single thrust bearing then positions the complete rotor train. Elimination of individual thrust bearings results in a smaller lube-oil system and a reduced power loss. Any additional thrust components from a prestressed flexible-disc coupling or a gear-type coupling (gear lock) are completely avoided. The use of a flexible intermediate shaft (quill shaft) gives the solid coupling the same lateral flexibility as for a geartype or flexible-disc coupling. Criteria for allowable misalignment are given in this paper. A solid coupling is neither exposed to any kind of wear nor endangered by corrosion or stress corrosion so that no maintenance is necessary. Couplings have a decisive influence on rotordynamics. The conventional arrangement of a multicasing train with gear-type or flexible-disc couplings incorporates individual thrust bearings located outboard of the journal bearings (long shaft over hangs). Introducing solid couplings leads to a stiffer rotor by eliminating individual thrust bearings. A comparison of critical speeds of a high-speed/high-power compressor train is made alternatively equipped with solid couplings, flexible-disc or gear-type couplings. The response of the different rotors and couplings to specified unbalance weights is calculated and compared throughout the complete speed range. Torsional and lateral critical frequencies can easily be influenced by modification of intermediate shafts, even after installation of a compressor train. Operating experience on nearly 1500 compressors equipped with solid couplings have proven their excellent reliability especially on high speed, high power turbocompressor applications

Analysis of the piggyBac transposase reveals a functional nuclear targeting signal in the 94 c-terminal residues

<p>Abstract</p> <p>Background</p> <p>The <it>piggyBac</it> transposable element is a popular tool for germ-line transgenesis of eukaryotes. Despite this, little is known about the mechanism of transposition or the transposase (TPase) itself. A thorough understanding of just how <it>piggyBac</it> works may lead to more effective use of this important mobile element. A PSORTII analysis of the TPase amino acid sequence predicts a bipartite nuclear localization signal (NLS) near the c-terminus, just upstream of a putative ZnF (ZnF).</p> <p>Results</p> <p>We fused the <it>piggyBac</it> TPase upstream of and in-frame with the enhanced yellow fluorescent protein (EYFP) in the <it>Drosophila melanogaster</it> inducible metallothionein protein. Using Drosophila Schneider 2 (S2) cells and the deep red fluorescent nuclear stain Draq5, we were able to track the pattern of <it>piggyBac</it> localization with a scanning confocal microscope 48 hours after induction with copper sulphate.</p> <p>Conclusion</p> <p>Through n and c-terminal truncations, targeted internal deletions, and specific amino acid mutations of the <it>piggyBac</it> TPase open reading frame, we found that not only is the PSORTII-predicted NLS required for the TPase to enter the nucleus of S2 cells, but there are additional requirements for negatively charged amino acids a short length upstream of this region for nuclear localization.</p

Mutational analysis of highly conserved aspartate residues essential to the catalytic core of the piggyBac transposase

<p>Abstract</p> <p>Background</p> <p>The <it>piggyBac </it>mobile element is quickly gaining popularity as a tool for the transgenesis of many eukaryotic organisms. By studying the transposase which catalyzes the movement of <it>piggyBac</it>, we may be able to modify this vector system to make it a more effective transgenesis tool. In a previous publication, Sarkar A, Sim C, Hong YS, Hogan JR, Fraser MJ, Robertson HM, and Collins FH have proposed the presence of the widespread 'DDE/DDD' motif for <it>piggyBac </it>at amino acid positions D268, D346, and D447.</p> <p>Results</p> <p>This study utilizes directed mutagenesis and plasmid-based mobility assays to assess the importance of these residues as the catalytic core of the <it>piggyBac </it>transposase. We have functionally analyzed individual point-mutations with respect to charge and physical size in all three proposed residues of the 'DDD' motif as well as another nearby, highly conserved aspartate at D450. All of our mutations had a significant effect on excision frequency in S2 cell cultures. We have also aligned the <it>piggyBac </it>transposase to other close family members, both functional and non-functional, in an attempt to identify the most highly conserved regions and position a number of interesting features.</p> <p>Conclusion</p> <p>We found all the designated DDD aspartates reside in clusters of amino acids that conserved among <it>piggyBac </it>family transposase members. Our results indicate that all four aspartates are necessary, to one degree or another, for excision to occur in a cellular environment, but D450 seems to have a tolerance for a glutamate substitution. All mutants tested significantly decreased excision frequency in cell cultures when compared with the wild-type transposase.</p

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency–Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe