Circular Clustering with Polar Coordinate Reconstruction

There is a growing interest in characterizing circular data found in biological systems. Such data are wide ranging and varied, from signal phase in neural recordings to nucleotide sequences in round genomes. Traditional clustering algorithms are often inadequate due to their limited ability to distinguish differences in the periodic component. Current clustering schemes that work in a polar coordinate system have limitations, such as being only angle-focused or lacking generality. To overcome these limitations, we propose a new analysis framework that utilizes projections onto a cylindrical coordinate system to better represent objects in a polar coordinate system. Using the mathematical properties of circular data, we show our approach always finds the correct clustering result within the reconstructed dataset, given sufficient periodic repetitions of the data. Our approach is generally applicable and adaptable and can be incorporated into most state-of-the-art clustering algorithms. We demonstrate on synthetic and real data that our method generates more appropriate and consistent clustering results compared to standard methods. In summary, our proposed analysis framework overcomes the limitations of existing polar coordinate-based clustering methods and provides a more accurate and efficient way to cluster circular data.Comment: Manuscript is under review in IEEE Transactions on Computational Biology and Bioinformatics. Copyright holder is credited to IEE

A Petunia homeodomain-leucine zipper protein, PhHD-Zip, plays an important role in flower senescence.

Flower senescence is initiated by developmental and environmental signals, and regulated by gene transcription. A homeodomain-leucine zipper transcription factor, PhHD-Zip, is up-regulated during petunia flower senescence. Virus-induced gene silencing of PhHD-Zip extended flower life by 20% both in unpollinated and pollinated flowers. Silencing PhHD-Zip also dramatically reduced ethylene production and the abundance of transcripts of genes involved in ethylene (ACS, ACO), and ABA (NCED) biosynthesis. Abundance of transcripts of senescence-related genes (SAG12, SAG29) was also dramatically reduced in the silenced flowers. Over-expression of PhHD-Zip accelerated petunia flower senescence. Furthermore, PhHD-Zip transcript abundance in petunia flowers was increased by application of hormones (ethylene, ABA) and abiotic stresses (dehydration, NaCl and cold). Our results suggest that PhHD-Zip plays an important role in regulating petunia flower senescence

Investigations of CO2-water wettability of coal : NMR relaxation method

Acknowledgments We acknowledge financial support from the National Natural Science Foundation of China (41472137), the Key Research and Development Projects of The Xinjiang Uygur Autonomous Region (2017B03019-01), and the National Major Research Program for Science and Technology of China (2016ZX05043-001), and the Royal Society Edinburgh and National Natural Science Foundation China (NSFC 41711530129).Peer reviewedPostprin

Does Culture Matter to Pro-Social Behavior? Evidence from a Cross-Ethnic Lab Experiment

Recent investigations have uncovered large, consistent deviations from the predictions of Homo economics that individuals are entirely self-regarding. Our study undertook a cross-cultural study of behavior search for the evidences of other-regarding behaviors and its ethnic difference, and accounted for by anatomy of culture. This study recruited 90 subjects of three ethnic groups from market trade-based (ethnic Han), nomadism-based (ethnic Zang) and agriculture-based (ethnic Bouyei) areas in China and conducted public good provision experiment with stranger-treatment design. Under the assumption of self-regarding preferences, the Nash equilibrium is zero contribution by all in public account using backward induction. However, we found contributions did not reduce to zero over all three sessions. Besides, the differences in contributions between ethnicities strongly depended on the degree of ethnic dominance, and Zang harbored the strongest reciprocal preference generally over all group structures. A particular set of measurable factors was identified as proxies for cultural influences on behavioral differences observed in experiments between ethnicities. The results showed all of the cultural factors accounted for the behavioral differences between the ethnic Han and the other two minor ethnicities. However, behavioral difference between minor ethnicities was attributed to group structure only. (1) People may harbor various forms of prosocial emotions in economic affairs, and especially exhibit stronger at the initial phase rather than what canonical model assumes. (2) Behavioral differences between ethnicities are prominent and can be explained by differences in cultural influence

Preliminary aerodynamic design methodology for aero engine lean direct injection combustors

The Lean Direct Injection (LDI) combustor is one of the low-emissions combustors with great potential in aero-engine applications, especially those with high overall pressure ratio. A preliminary design tool providing basic combustor sizing information and qualitative assessment of performance and emission characteristics of the LDI combustor within a short period of time will be of great value to designers. In this research, the methodology of preliminary aerodynamic design for a second-generation LDI (LDI-2) combustor was explored. A computer code was developed based on this method covering the design of air distribution, combustor sizing, diffuser, dilution holes and swirlers. The NASA correlations for NOx emissions are also embedded in the program in order to estimate the NOx production of the designed LDI combustor. A case study was carried out through the design of an LDI-2 combustor named as CULDI2015 and the comparison with an existing rich-burn, quick-quench, lean-burn combustor operating at identical conditions. It is discovered that the LDI combustor could potentially achieve a reduction in liner length and NOx emissions by 18% and 67%, respectively. A sensitivity study on parameters such as equivalence ratio, dome and passage velocity and fuel staging is performed to investigate the effect of design uncertainties on both preliminary design results and NOx production. A summary on the variation of design parameters and their impact is presented. The developed tool is proved to be valuable to preliminarily evaluate the LDI combustor performance and NOx emission at the early design stage

SIVALHIPPUS PTYCHODUS AND SIVALHIPPUS PLATYODUS (PERISSODACTYLA, MAMMALIA) FROM THE LATE MIOCENE OF CHINA

  Herein, the authors report on skulls, mandibles and postcranial specimens of two species of Chinese Sivalhippus, S. ptychodus and S. platyodus. We frame our description and analyses within the context of newly described characters of the cheek teeth of Hippotherium from the Pannonian C of the Vienna Basin, the oldest and most primitive Old World hipparions. Our report includes original skull, mandibular and limited postcranial material of Sivalhippus ptychodus and skulls and dentitions of Sivalhippus platyodus from the Paleontological Museum of Uppsala (PMU, Uppsala, Sweden), the American Museum of Natural History (AMNH, New York, USA) and the Licent Collection in Tianjin Natural History Museum (Tianjin, China). The skull, maxillary and mandibular material we attribute to Sivalhippus ptychodus and Sivalhippus platyodus exhibit some primitive features for Old World hipparions and synapamorphies of the face and dentition that unite it with the Sivalhippus clade. Our analysis shows that S. ptychodus and S. platyodus differ significantly from the Cormohipparion occidentale – Hippotherium primigenium clade. Species belonging to the Sivalhippus clade are found in IndoPakistan (S. nagriensis, S. theobaldi, S. perimensis and S. anwari), Libya and Kenya (S. turkanensis) and Uganda (S. macrodon). We hypothesize that the Sivalhippus clade originated in South Asia where it is earliest represented by Sivalhipus nagriensis, ca. 10.4 Ma and underwent range extension into Africa and China circa 9-7 Ma