Enumerating typical abelian prime-fold coverings of a circulant graph

Feng, R.,Kwak, J.H.,Kwon, Y.S. North-Holland Pub. Co ; Elsevier Science Ltd 2009 Discrete mathematics Vol.309 No.8

Enumerating the isomorphism classes of several types of graph coverings is one of the central research topics in enumerative topological graph theory (see [R. Feng, J.H. Kwak, J. Kim, J. Lee, Isomorphism classes of concrete graph coverings, SIAM J. Discrete Math. 11 (1998) 265-272; R. Feng, J.H. Kwak, Typical circulant double coverings of a circulant graph, Discrete Math. 277 (2004) 73-85; R. Feng, J.H. Kwak, Y.S. Kwon, Enumerating typical circulant covering projections onto a circulant graph, SIAM J. Discrete Math. 19 (2005) 196-207; SIAM J. Discrete Math. 21 (2007) 548-550 (erratum); M. Hofmeister, Graph covering projections arising from finite vector spaces over finite fields, Discrete Math. 143 (1995) 87-97; M. Hofmeister, Enumeration of concrete regular covering projections, SIAM J. Discrete Math. 8 (1995) 51-61; M. Hofmeister, A note on counting connected graph covering projections, SIAM J. Discrete Math. 11 (1998) 286-292; J.H. Kwak, J. Chun, J. Lee, Enumeration of regular graph coverings having finite abelian covering transformation groups, SIAM J. Discrete Math. 11 (1998) 273-285; J.H. Kwak, J. Lee, Isomorphism classes of graph bundles, Canad. J. Math. XLII (1990) 747-761]). A covering is called abelian (or circulant, respectively) if its covering graph is a Cayley graph on an abelian (or a cyclic, respectively) group. A covering p from a Cayley graph Cay(A,X) onto another Cay (Q,Y) is called typical if the map p:A->Q on the vertex sets is a group epimorphism. Recently, the isomorphism classes of connected typical circulant r-fold coverings of a circulant graph are enumerated in [R. Feng, J.H. Kwak, Typical circulant double coverings of a circulant graph, Discrete Math. 277 (2004) 73-85] for r=2 and in [R. Feng, J.H. Kwak, Y.S. Kwon, Enumerating typical circulant covering projections onto a circulant graph, SIAM J. Discrete Math. 19 (2005) 196-207; SIAM J. Discrete Math. 21 (2007) 548-550 (erratum)] for any r. As a continuation of these works, we enumerate in this paper the isomorphism classes of typical abelian prime-fold coverings of a circulant graph.

The exhumation along the Kenyase and Ketesso shear zones in the Sefwi terrane, West African Craton: a numerical study

Xiaojun Feng,Enyuan Wang,Jérôme Ganne,Roland Martin,Mark Jessell 한국지질과학협의회 2019 Geosciences Journal Vol.23 No.3

High-grade (amphibolite–granulite facies) tectono-metamorphic domains in the Sefwi terrane of Ghana are separated from adjacent lower-grade (greenschist facies) greenstone belts by two main shear zones. The high-grade rocks presumably exhumed along the sinistral shear zones during the D2 ENE-WSW transtension (~2073 Ma). To better understand the role boundary conditions and the spatial relationship of faults play in the exhumation of partially molten lower crust in the Sefwi terrane, ten 3D thermomechanical models have been constructed. The results show that the normal component of velocity boundary conditions mainly controls the exhumation (8–10 km) of the lower crust along pre-existing faults, while the exhumation in the relay zones between faults is controlled by the obliquity between the applied extensional velocity vector and the vertical wall on which it is applied. The strike of the exhumation belt made of partially molten lower crust rocks in the relay zone is sub-orthogonal to the horizontal maximum stretching axis. The isostatic compensation from low-density upper mantle to overlying crust (thinning) is higher under transtension than under extension. The lower crust exhumation influenced by inherited shear zones (ductile) can be used to better understand the loci of the high-grade rocks in the Sefwi terrane. We suggest that the Kukuom-Juaboso domain composed of amphibolite–migmatite facies rocks probably resulted from the concentration of partially molten rocks in the relay zone between the Ketesso and Kenyase shear zones during the D2 ENE-WSW transtension. The two shear zones probably underwent two main stages for growth and maturation from the D1 to D2 phases. The regional exhumation of the high-grade rocks in the Sefwi terrane probably occurred within < 5 Ma.

Effect of pre-existing faults on the distribution of lower crust exhumation under extension: numerical modelling and implications for NW Ghana

Xiaojun Feng,Enyuan Wang,Prince O. Amponsah,Jérôme Ganne,Roland Martin,Mark W. Jessell 한국지질과학협의회 2019 Geosciences Journal Vol.23 No.6

3D thermo-mechanical models have been constructed to explore the influence of pre-existing faults on the temporalspatial distribution of high-grade amphibolite-granulite facies metamorphic rocks during extension. The different dip amounts of three pre-existing faults (refer to the Bole-Nangodi shear zones, the Jirapa shear zone and the Bulenga shear zone in the study area) are studied in models. The results show the lower crust exhumes occur at a relatively low rate prior to attaining a Stretching Factor = 4.2%. The partially molten lower crustal rocks tend to move (up to 20 km) towards the center of the model and focus exhumation in regions where pre-existing faults intersect. The high-strain corridors in models are used to understand the loci of exhumation in the Bole-Bulenga domain of NW Ghana. Accordingly, in the eastern and western parts of the high-grade rock corridors in NW Ghana, partially molten rocks exhumed from the lower into middle-upper crustal levels are interpreted to have been dominantly facilitated by the km-scale high-strain corridors. In the central part of the Bole-Bulenga domain, the high-grade rocks are interpreted to have been exhumed because of a coupling between two mechanisms: (1) The exhumation of partially molten rocks between the Jirapa and Bole-Nangodi faults increases in spatially due to the reduction in space from north to south. (2) The exhumation of lower partially molten rocks in the central part, as a result of inherited orthogonal (E-W) structures.

재래 흑돼지와 중국 재래돈간의 Melanocortin Receptor 1(MC1R) 유전자의 유전자형 분석

이성수,양보석,정진관,고서봉,오성종,양영훈,김규일,이찬동,풍서당 한국동물자원과학회 2001 한국축산학회지 Vol.43 No.1

PCR-RFLP analysis of Melanocortin receptor 1 (MC1R) gene was carried out to investigate the genotype distribution in Korean-Native and Chinese-Native pig breeds(Neijiang, Putian, Wannanhua and Jinhua). Allelic variants of MC1R in pigs were analyzed by digestion of BspH I , AccII and Hha I . Ncijiang. Wannanhua and Jinhua had only MC1R*2 allele which is considered to be typical genotype for Meishan and Large Black. Among 20 Korean-Native Pigs and 5 Putian pigs, 10 and 2 heads had the MC1R*3 allele (*2/3 or 3/3), respectively, which was detected in European pig breeds such as Hampshire, Large White, and Pietrain. The remaining animals possessed the genotype MC1R*2/2, probably reflecting the genetic introgression of MC1R*3 allele into Korean-Native and Putian pig breeds by the crossbreeding for improvement. The alleles MC1R*l and MC1R*4, which are considered to be typical allele for European Wild Boar with wild-type coat color and Duroc with red coat color, respectively, were not detected in pig breeds used in this experiment. These results indicate that the analysis of genotype frequencies of MC1R gene may be a useful tool for the conservation of Korean-Native and Chinese-Native pig breeds.

Astrocytic water channel aquaporin-4 modulates brain plasticity in both mice and humans: a potential gliogenetic mechanism underlying language-associated learning

Woo, J,Kim, J E,Im, J J,Lee, J,Jeong, H S,Park, S,Jung, S-Y,An, H,Yoon, S,Lim, S M,Lee, S,Ma, J,Shin, E Y,Han, Y-E,Kim, B,Lee, E H,Feng, L,Chun, H,Yoon, B-E,Kang, I,Dager, S R,Lyoo, I K,Lee, C J Macmillan Publishers Limited, part of Springer Nat 2018 Molecular psychiatry Vol.23 No.4

<P>The role of astrocytes in brain plasticity has not been extensively studied compared with that of neurons. Here we adopted integrative translational and reverse-translational approaches to explore the role of an astrocyte-specific major water channel in the brain, aquaporin-4 (AQP4), in brain plasticity and learning. We initially identified the most prevalent genetic variant of AQP4 (single nucleotide polymorphism of rs162008 with C or T variation, which has a minor allele frequency of 0.21) from a human database (n = 60 706) and examined its functionality in modulating the expression level of AQP4 in an in vitro luciferase reporter assay. In the following experiments, AQP4 knock-down in mice not only impaired hippocampal volumetric plasticity after exposure to enriched environment but also caused loss of long-term potentiation after theta-burst stimulation. In humans, there was a cross-sectional association of rs162008 with gray matter (GM) volume variation in cortices, including the vicinity of the Perisylvian heteromodal language area (Sample 1, n = 650). GM volume variation in these brain regions was positively associated with the semantic verbal fluency. In a prospective follow-up study (Sample 2, n = 45), the effects of an intensive 5-week foreign language (English) learning experience on regional GM volume increase were modulated by this AQP4 variant, which was also associated with verbal learning capacity change. We then delineated in mice mechanisms that included AQP4-dependent transient astrocytic volume changes and astrocytic structural elaboration. We believe our study provides the first integrative evidence for a gliogenetic basis that involves AQP4, underlying language-associated brain plasticity.</P>

Determination of the molar mass of argon from high-precision acoustic comparisons

Feng, X J,Zhang, J T,Moldover, M R,Yang, I,Plimmer, M D,Lin, H BUREAU INTERNATIONAL DES POIDS ET MESURES 2017 METROLOGIA -BERLIN- Vol.54 No.3

<P>This article describes the accurate determination of the molar mass <I>M</I> of a sample of argon gas used for the determination of the Boltzmann constant. The method of one of the authors (Moldover <I>et al</I> 1988 <I>J. Res. Natl. Bur. Stand</I>. <B>93</B> 85–144) uses the ratio of the square speed of sound in the gas under analysis and in a reference sample of known molar mass. A sample of argon that was isotopically-enriched in <SUP>40</SUP>Ar was used as the reference, whose unreactive impurities had been independently measured. The results for three gas samples are in good agreement with determinations by gravimetric mass spectrometry; (〈<I>M</I> <SUB>acoustic</SUB>/<I>M</I> <SUB>mass-spec</SUB>〉  −  1)  =  (−0.31  ±  0.69)  ×  10<SUP>−6</SUP>, where the indicated uncertainty is one standard deviation that does not account for the uncertainties from the acoustic and mass-spectroscopy references.</P>

FACILE AND LARGE-SCALE FABRICATION OF Ni NANOCHAINS BY A CHEMICAL REDUCTION METHOD WITH THE ASSISTANCE OF EXTERNAL MAGNETIC FIELD

J. Y. LIAO,H. LI,J. J. LIANG,Y. F. FENG,X. B. ZHANG,Y. Q. YIN,H. X. TAO 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2013 NANO Vol.8 No.1

Magnetic Ni micro/nanostructures with controlled morphology have drawn intensive attention due to their interesting physicochemical properties and potential applications in micro/nanodevices. In this study, one-dimensional Ni nanochains with an average diameter of about 140 nm were prepared by a magnetic-field-assisted chemical reduction of Ni2+ with hydrazine hydrate free of any template or surfactant. It was found that the morphology and the size of the Ni chains could be adjusted by changing the complexant used in the synthesis. The usage of surfactant in the synthesis would retard the firm connection of Ni nanoparticles and thus resulted in the formation of Ni nanochains consisting of loosely aggregated Ni nanoparticles. The magnetic measurement at room temperature indicated that the coercivity of the Ni sample reached 133.2 Oe, which was much higher than that of bulk Ni metal.

GA-BASED PID AND FUZZY LOGIC CONTROL FOR ACTIVE VEHICLE SUSPENSION SYSTEM

J. Z. FENG,J. LI,F. YU 한국자동차공학회 2003 International journal of automotive technology Vol.4 No.4

Since the nonlinearity and uncertainties which inherently exist in vehicle system need to be considered in active suspension control law design, this paper proposes a new control strategy for active vehicle suspension systems by using a combined control scheme, i.e., respectively using a genetic algorithm (GA) based self-tuning PID controller and a fuzzy logic controller in two loops. In the control scheme, the PID controller is used to minimize vehicle body vertical acceleration, the fuzzy logic controller is to minimize pitch acceleration and meanwhile to attenuate vehicle body vertical acceleration further by tuning weighting factors. In order to improve the adaptability to the changes of plant parameters, based on the defined objectives, a genetic algorithm is introduced to tune the parameters of PID controller, the scaling factors, the gain values and the membership functions of fuzzy logic controller on-line. Taking a four degree-or-freedom nonlinear vehicle model as example, the proposed control scheme is applied and the simulations are carried out in different road disturbance input conditions. Simulation results show that the present control scheme is very effective in reducing peak values of vehicle body accelerations, especially within the most sensitive frequency range of human response, and in attenuating the excessive dynamic tire load to enhance road holding performance. The stability and adaptability are also showed even when the system is subject to severe road conditions, such as a pothole, an obstacle or a step input. Compared with conventional passive suspensions and the active vehicle suspension systems by using, e.g., linear fuzzy logic control, the combined PID and fuzzy control without parameters self-tuning, the new proposed control system with GA-based self-learning ability can improve vehicle ride comfort performance significantly and offer better system robustness.<br/>

Letter to the Editor, 'Osterix Regulates Tooth Root Formation in a Site-specific Manner'.

Feng, J Q,Zhang, H,Qin, C Journal of Dental Research, Inc 2015 Journal of dental research Vol.94 No.9

Effect of Yb₂SiO₅ addition on the physical and mechanical properties of sintered mullite ceramic as an environmental barrier coating material

Feng, F.J.,Jang, B.K.,Park, J.Y.,Lee, K.S. Ceramurgica ; Elsevier Science Ltd 2016 CERAMICS INTERNATIONAL Vol.42 No.14

In this study, ytterbium monosilicate (Yb<SUB>2</SUB>SiO<SUB>5</SUB>)-added sintered mullite ceramics are prepared as candidate materials for environmental barrier coatings (EBCs). The effect of adding Yb<SUB>2</SUB>SiO<SUB>5</SUB> on the physical and mechanical properties of the sintered mullite ceramics is investigated. The Yb<SUB>2</SUB>O<SUB>3</SUB>-SiO<SUB>2</SUB>-Al<SUB>2</SUB>O<SUB>3</SUB> ternary phase diagram indicates that adding Yb<SUB>2</SUB>SiO<SUB>5</SUB> to the mullite goes beyond simply mixing; instead, liquid sintering occurs. Therefore, when we add Yb<SUB>2</SUB>SiO<SUB>5</SUB> to the mullite, the sintered body possesses a denser microstructure and faster densification rate than does pure mullite. The density rapidly increases with the addition of 6wt% Yb<SUB>2</SUB>SiO<SUB>5</SUB> in the mullite, and almost full densifications are achieved with the addition of 12wt% and 18wt% Yb<SUB>2</SUB>SiO<SUB>5</SUB>. In this study, mullite ceramic that contains 12wt% Yb<SUB>2</SUB>SiO<SUB>5</SUB> exhibits the smallest plastic deformation and the highest elastic modulus among ceramics containing 6, 12, and 18wt% Yb<SUB>2</SUB>SiO<SUB>5</SUB>, according to Hertzian indentation results. The results suggest that 12wt% Yb<SUB>2</SUB>SiO<SUB>5</SUB>-doped mullite may be expected to act as a potential EBC material based on its excellent elastic properties, dense microstructure, and appropriate coefficient of thermal expansion.