Robustness of Half-Integer Quantized Hall Conductivity against Disorder in an Anisotropic Dirac Semimetal with Parity Anomaly

Two-dimensional Dirac semimetals with a single massless Dirac cone exhibit the parity anomaly. Usually, such a kind of anomalous topological semimetallic phase in real materials is unstable where any amount of disorder can drive it into a diffusive metal and destroy the half-integer quantized Hall conductivity as an indicator of parity anomaly. Here, based on low-energy effective model, we propose an anisotropic Dirac semimetal which explicitly breaks time-reversal symmetry and carries a half-integer quantized Hall conductivity. This topological semimetallic phase can be realized on a deformed honeycomb lattice subjected to a magnetic flux. Moreover, we perceptively investigate the disorder correction to the Hall conductivity. The results show that the effects of disorder can be strongly suppressed and thereby the nearly half-integer quantization of Hall conductivity can exist in a wide region of disorder, indicating that our proposed anisotropic Dirac semimetal is an exciting platform to investigate the parity anomaly phenomena.Comment: 7 pages, 4 figure

Can we detect coronal mass ejections through asymmetries of Sun-as-a-star extreme-ultraviolet spectral line profiles?

Coronal mass ejections (CMEs) are the largest-scale eruptive phenomena in the solar system. Associated with enormous plasma ejections and energy release, CMEs have an important impact on the solar-terrestrial environment. Accurate predictions of the arrival times of CMEs at the Earth depend on the precise measurements on their three-dimensional velocities, which can be achieved using simultaneous line-of-sight (LOS) and plane-of-sky (POS) observations. Besides the POS information from routine coronagraph and extreme ultraviolet (EUV) imaging observations, spectroscopic observations could unveil the physical properties of CMEs including their LOS velocities. We propose that spectral line asymmetries measured by Sun-as-a-star spectrographs can be used for routine detections of CMEs and estimations of their LOS velocities during their early propagation phases. Such observations can also provide important clues for the detection of CMEs on other solar-like stars. However, few studies have concentrated on whether we can detect CME signals and accurately diagnose CME properties through Sun-as-a-star spectral observations. In this work, we constructed a geometric CME model and derived the analytical expressions for full-disk integrated EUV line profiles during CMEs. For different CME properties and instrumental configurations, full disk-integrated line profiles were synthesized. We further evaluated the detectability and diagnostic potential of CMEs from the synthetic line profiles. Our investigations provide important constraints on the future design of Sun-as-a-star spectrographs for CME detections through EUV line asymmetries.Comment: 28 pages, 13 figures. Accepted for publication in ApJS. Comments welcome

Detection of copy number variations and their effects in Chinese bulls

BACKGROUND: Copy number variations (CNVs) are a main source of genomic structural variations underlying animal evolution and production traits. Here, with one pure-blooded Angus bull as reference, we describe a genome-wide analysis of CNVs based on comparative genomic hybridization arrays in 29 Chinese domesticated bulls and examined their effects on gene expression and cattle growth traits. RESULTS: We identified 486 copy number variable regions (CNVRs), covering 2.45% of the bovine genome, in 24 taurine (Bos taurus), together with 161 ones in 2 yaks (Bos grunniens) and 163 ones in 3 buffaloes (Bubalus bubalis). Totally, we discovered 605 integrated CNVRs, with more “loss” events than both “gain” and “both” ones, and clearly clustered them into three cattle groups. Interestingly, we confirmed their uneven distributions across chromosomes, and the differences of mitochondrion DNA copy number (gain: taurine, loss: yak & buffalo). Furthermore, we confirmed approximately 41.8% (253/605) and 70.6% (427/605) CNVRs span cattle genes and quantitative trait loci (QTLs), respectively. Finally, we confirmed 6 CNVRs in 9 chosen ones by using quantitative PCR, and further demonstrated that CNVR22 had significantly negative effects on expression of PLA2G2D gene, and both CNVR22 and CNVR310 were associated with body measurements in Chinese cattle, suggesting their key effects on gene expression and cattle traits. CONCLUSIONS: The results advanced our understanding of CNV as an important genomic structural variation in taurine, yak and buffalo. This study provides a highly valuable resource for Chinese cattle’s evolution and breeding researches. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/1471-2164-15-480) contains supplementary material, which is available to authorized users

Pollen source areas of lakes with inflowing rivers: modern pollen influx data from Lake Baiyangdian, China

Comparing pollen influx recorded in traps above the surface and below the surface of Lake Baiyangdian in northern China shows that the average pollen influx in the traps above the surface is much lower, at 1210 grains cm−2 a−1 (varying from 550 to 2770 grains cm−2 a−1), than in the traps below the surface which average 8990 grains cm−2 a−1 (ranging from 430 to 22310 grains cm−2 a−1). This suggests that about 12% of the total pollen influx is transported by air, and 88% via inflowing water. If hydrophyte pollen types are not included, the mean pollen influx in the traps above the surface decreases to 470 grains cm−2 a−1 (varying from 170 to 910 grains cm−2 a−1) and to 5470 grains cm−2 a−1 in the traps below the surface (ranging from 270 to 12820 grains cm−2 a−1), suggesting that the contribution of waterborne pollen to the non-hydrophyte pollen assemblages in Lake Baiyangdian is about 92%. When trap assemblages are compared with sediment–water interface samples from the same location, the differences between pollen assemblages collected using different methods are more significant than differences between assemblages collected at different sample sites in the lake using the same trapping methods. We compare the ratios of terrestrial pollen and aquicolous pollen types (T/A) between traps in the water and aerial traps, and examine pollen assemblages to determine whether proportions of long-distance taxa (i.e. those known to only grow beyond the estimated aerial source radius); these data suggest that the pollen source area of this lake is composed of three parts, an aerial component mainly carried by wind, a fluvial catchment component transported by rivers and another waterborne component transported by surface wash. Where the overall vegetation composition within the ‘aerial catchment’ is different from that of the hydrological catchment, the ratio between aerial and waterborne pollen influx offers a method for estimating the relative importance of these two sources, and therefore a starting point for defining a pollen source area for a lake with inflowing rivers

The ovine HIAT1 gene: mRNA expression, InDel mutations, and growth trait associations

BackgroundThe hippocampal abundant transcript 1 (HIAT1) gene, also known as major facilitator superfamily domain-containing 14A (MFSD14A), encodes for a transmembrane transporter protein and has been previously shown to be associated with milk production in buffalo and sheep breeds, as well as growth traits in chicken and goats. However, tissue level distribution of the ovine HIAT1 gene, as well as its effect on body morphometric traits in sheep, has yet to be studied.MethodsThe HIAT1 mRNA expression profile of Lanzhou fat-tailed (LFT) sheep was determined by quantitative real-time PCR (qPCR). A total of 1498 sheep of three indigenous Chinese sheep breeds were PCR-genotyped for polymorphisms of HIAT1 gene. Student's t-test was used to observe the association between the genotype and sheep morphometric traits.ResultsHIAT1 was widely expressed in all examined tissues, and was particularly abundant in the testis of male LFT sheep. Additionally, a 9-bp insertion mutation (rs1089950828) located within the 5'-upstream region of HIAT1 was investigated in Luxi black-headed (LXBH) sheep and Guiqian semi-fine wool (GSFW) sheep. The wildtype allele frequency 'D' was found to be more prevalent than that of the mutant allele ‘I'. Furthermore, low genetic diversity was confirmed in all sampled sheep populations. Subsequent association analyses indicated an association between the 9-bp InDel mutation of interest and the morphometric traits of LXBH and GSFW sheep. Furthermore, yearling ewes with a heterozygous genotype (ID) demonstrated smaller body sizes, while yearling rams and adult ewes with the heterozygous genotype were found to have overall better growth performance.ConclusionThese findings imply that functional InDel polymorphism (rs1089950828) has the potential to be utilized for marker-assisted selection (MAS) of growth traits in domestic Chinese sheep populations

Epigenome-wide association data implicates DNA methylation-mediated genetic risk in psoriasis

Abstract Background Psoriasis is a chronic inflammatory skin disease characterized by epidermal hyperproliferation and altered keratinocyte differentiation and inflammation and is caused by the interplay of genetic and environmental factors. Previous studies have revealed that DNA methylation (DNAm) and genetic makers are closely associated with psoriasis, and strong evidences have shown that DNAm can be controlled by genetic factors, which attracted us to evaluate the relationship among DNAm, genetic makers, and disease status. Methods We utilized the genome-wide methylation data of psoriatic skin (PP, N = 114) and unaffected control skin (NN, N = 62) tissue samples in our previous study, and we performed whole-genome genotyping with peripheral blood of the same samples to evaluate the underlying genetic effect on skin DNA methylation. Causal inference test (CIT) was used to assess whether DNAm regulate genetic variation and gain a better understanding of the epigenetic basis of psoriasis susceptibility. Results We identified 129 SNP-CpG pairs achieving the significant association threshold, which constituted 28 unique methylation quantitative trait loci (MethQTL) and 34 unique CpGs. There are 18 SNPs were associated with psoriasis at a Bonferoni-corrected P < 0.05, and these 18 SNPs formed 93 SNP-CpG pairs with 17 unique CpG sites. We found that 11 of 93 SNP-CpG pairs, composed of 5 unique SNPs and 3 CpG sites, presented a methylation-mediated relationship between SNPs and psoriasis. The 3 CpG sites were located on the body of C1orf106, the TSS1500 promoter region of DMBX1 and the body of SIK3. Conclusions This study revealed that DNAm of some genes can be controlled by genetic factors and also mediate risk variation for psoriasis in Chinese Han population and provided novel molecular insights into the pathogenesis of psoriasis

A modified ‘skeleton/skin’ strategy for designing CoNiP nanosheets arrayed on graphene foam for on/off switching of NaBH4_{4} hydrolysis

CoNiP nanosheet array catalysts were successfully prepared on three-dimensional (3D) graphene foam using hydrothermal synthesis. These catalysts were prepared using 3D Ni–graphene foam (Ni/GF), comprising nickel foam as the ‘skeleton’ and reduced graphene oxide as the ‘skin’. This unique continuous modified ‘skeleton/skin’ structure ensure that the catalysts had a large surface area, excellent conductivity, and sufficient surface functional groups, which promoted in situ CoNiP growth, while also optimizing the hydrolysis of sodium borohydride. The nanosheet arrays were fully characterized and showed excellent catalytic performance, as supported by density functional theory calculations. The hydrogen generation rate and activation energy are 6681.34 mL min$_{−1}$ g$_{−1}$ and 31.2 kJ mol$_{−1}$, respectively, outperforming most reported cobalt-based catalysts and other precious metal catalysts. Furthermore, the stability of mockstrawberry-like CoNiP catalyst was investigated, with 74.9% of the initial hydrogen generation rate remaining after 15 cycles. The catalytic properties, durability, and stability of the catalyst were better than those of other catalysts reported previously