Presence Of 2H Research Articles

A recursive Byzantine-resilient protocol

To solve the consensus problem, the classical consensus protocols require t+1 rounds of message exchange to tolerate t faulty processors, where t=⌊(n−1)/3⌋ and n is the total number of processors in the network. With advancement of software and hardware technologies in recent years, the “actual number of faulty processors” (fact) in a network is usually smaller than t, and fact≪t. However, the classical consensus protocols still need to execute t+1 rounds of message exchange even if there are no faulty processors in the network. To address this issue, we propose a new consensus protocol called Recursive Byzantine-Resilient protocol (RBR protocol). We integrate the concepts of parallel computing, grouping, hierarchy and recursion into this protocol to reduce its time and space complexity. Specifically, the RBR protocol can solve the consensus problem in the presence of 2h(⌊((n/4h)−1)/3⌋+1)−1 Byzantine faulty processors, where h=⌊(lg(n)−2)/2⌋. The time complexity and space complexity of RBR protocol are O(lg(n)) and O(nklg(n)) respectively. The results reveal that RBR protocol outperforms previous protocols in terms of time complexity and in terms of space complexity. In this paper, we also discuss how to enhance the fault-tolerance capability of RBR protocol in achieving consensus through repetitive execution of the protocol when the number of Byzantine faulty processors is greater than 2h(⌊((n/4h)−1)/3⌋+1)−1.

A simple risk score effectively predicted type 2 diabetes in Iranian adult population: population-based cohort study

Although several strategies to predict the development of diabetes have been developed the question is whether better scores can be developed without sacrificing simplicity. Data on 3242 participants of Tehran Lipid and Glucose Study aged ≥20 years, without diabetes at the baseline that completed a ~6-year follow-up were used to develop prediction models by running a series of logistic regression model. A simple score system was then developed based on the most important variables selected with forward stepwise approach. During follow-up, 231 individuals developed diabetes. The area under the receiver operating characteristic curve for the score system based on the model including systolic blood pressure (SBP), family history of diabetes, waist-to-height ratio (WHtR), triglyceride-to-high-density lipoprotein cholesterol ratio (TG/HDL-C) ≥3.5 and fasting plasma glucose (FPG) levels ≥5 mmol l(-1) was 0.83 (95% CI 0.80-0.86); the model discriminated subjects with substantial risk for diabetes, appreciably better than 2-h post-challenge plasma glucose (2h-PCPG) alone (0.78; 95% CI 0.75-0.82) (P < 0.001). Scoring ≥25 yielded a positive likelihood ratio of 3.27. FPG levels even in the presence of 2h-PCPG predicted incident diabetes. We presented a simple model based on SBP, family history of diabetes, WHtR, TG/HDL-C and FPG; concluding that this approach is superior to relying exclusively on the 2h-PCPG for identifying individuals at high risk for developing diabetes in a Middle Eastern adult population.

Stable isotope labelling studies on the biosynthesis of pinguisane-type sesquiterpenes in axenic cultures of Aneura pinguis

H. Tazaki, H. Soutome, T. Iwasaki, K. Nabeta and D. Arigoni, Chem. Commun., 1997, 1101 DOI: 10.1039/A701784G

Biosynthesis of (1S)-7-methoxy-1,2-dihydrocadalene. Incorporation of 2H- and 13C-labelled mevalonates by cultured cells of Heteroscyphus planus

2 H and 13C NMR analyses of (1S)-7-methoxy-1, 2-dihydrocadalene produced by cell cultures of the liverwort Heteroscyphus planus in the presence of 2H- and 13C-labelled mevalonates verified 1,2 and 1,3-hydride shifts and the hydroxylation of an aromatic ring without an NIH shift in the biosynthesis of MDC.

Incorporation of [1,2-13C2]cadaverine and the enantiomeric [1-2H]cadaverines into the quinolizidine alkaloids in Baptisia australis

The mode of incorporation of [1,2-13C2]cadaverine (2) dihydrochloride into (–)-N-methylcytisine (14) in Baptisia australis was established by 13C n.m.r. spectroscopy. The tricyclic alkaloid (–)-N-methylcytisine displayed a labelling pattern (16) which was consistent with degradation of a tetracyclic intermediate. The (R)-[1-2H]-(11) and (S)-[1-2H]-cadaverine (12) dihydrochlorides were prepared and fed to Baptisia australis, and labelling patterns in the alkaloids were determined by 2H n.m.r. spectroscopy. After feeding the (R)-precursor (11), 2H was retained in (+)-sparteine (13) at C-2α, -6α, -11β, -15α, and -17β, whereas C-2β, -10β, and -15β were labelled from the (S)-precursor (12). The presence of 2H at C-17β in (+)-sparteine after feeding the (R)-isomer (11) shows that 17-oxosparteine [enantiomer of (10)] cannot be an intermediate in the formation of (+)-sparteine. With (–)-N-methylcytisine (14), 2H was retained after feeding the (R)-isomer (11) at C-10β and C-11β; the (S)-isomer (12) labelled C-13β. Comparison of these labelling patterns (19) with those of (+)-sparteine (17) establishes which outer ring of a tetracyclic intermediate is cleaved and which is converted into a pyridone during the formation of (–)-N-methylcytisine (14).

Application of 2H n.m.r. spectroscopy to study the incorporation of enantiomeric 2H-labelled cadaverines into quinolizidine alkaloids

The biosynthesis of a number of quinolizidine alkaloids has been studied in two Lupinus species using cadaverine precursors chirally labelled with deuterium. The labelling patterns in lupinine (2), sparteine (3), lupine (6), and angustifoline (8), derived biosynthetically from (R)-[1-2H]-(11) and (S)-[1-2H]cadaverine (12) have been established by 2H n.m.r. spectroscopy. The stereochemistry of a number of the steps involved in the conversion of cadaverine into lupinine (2) and the tetracyclic quinolizidine alkaloids has been established. The presence of 2H at C-17 in samples of sparteine (3), lupanine (6), and angustifoline (8) derived from the (R)-isomer (11) demonstrates that 17-oxosparteine (9) cannot be an intermediate in the biosynthesis of tetracyclic quinolizidine alkaloids. The presence of 2H at C-2 in both samples of sparteine (3) after feeding the precursors (11) and (12) disproves the theory that lupanine (6) is a precursor of sparteine (3).

Incorporation of chiral [1-2H]cadaverines into the quinolizidine alkaloids sparteine, lupanine, and angustifoline

2 H N.m.r. Spectroscopy has been used to establish the labelling patterns in sparteine (3), lupanine (5), and angustifoline (7), derived biosynthetically from (R)-[1-2H]-(8) and (S)[1-2H]-cadaverine (9); the presence of 2H at C-17 in these three alkaloids from the former precursor (8) demonstrates that 17-oxosparteine cannot be an intermediate in quinolizidine alkaloid biosynthesis.

Density-labelling evidence for the blue-light-mediated activation of phenylalanine ammonia lyase in Cucumis sativus seedlings

Evidence is presented which demonstrates that both acid phosphatase (EC 3.1.3.2) and phenylalanine ammonia-lyase (EC 4.3.1.5) are synthesised in the hypocotyls of dark-grown gherkin seedlings. When blue light or cycloheximide treatment is given in the presence of 2H 2 O the buoyant density of the lyase is observed to be lower than the appropriate dark control. This effect is not found for the phosphatase, the buoyant density of which is unaffected by blue ligh. These data appear to be best interpreted as a blue-light- and cycloheximide-mediated activation of previously synthesised, inactivated phenylalanine ammonia-lyase.