1,224 research outputs found
The One-dimensional Chiral Anomaly and its Disorder Response
The condensed-matter realization of chiral anomaly has attracted tremendous
interest in exploring unexpected phenomena of quantum field theory. Here, we
show that one-dimensional (1D) chiral anomaly (i.e., 1D nonconservational
chiral current under a background electromagnetic field) can be realized in a
generalized Su-Schrieffer-Heeger model where a single gapless Dirac cone
occurs. Based on the topological Thouless pump and anomalous dynamics of chiral
displacement, we elucidate that such a system possesses the half-integer
quantization of winding number. Moreover, we investigate the evolution of 1D
chiral anomaly with respect to two typical types of disorder, i.e., on-site
disorder and bond disorder. The results show that the on-site disorder tends to
smear the gapless Dirac cone. However, we propose a strategy to stabilize the
half-integer quantization, facilitating its experimental detection.
Furthermore, we demonstrate that the bond disorder causes a unique crossover
with disorder-enhanced topological charge pumping, driving the system into a
topological Anderson insulator phase
Learning to Rank when Grades Matter
Graded labels are ubiquitous in real-world learning-to-rank applications,
especially in human rated relevance data. Traditional learning-to-rank
techniques aim to optimize the ranked order of documents. They typically,
however, ignore predicting actual grades. This prevents them from being adopted
in applications where grades matter, such as filtering out ``poor'' documents.
Achieving both good ranking performance and good grade prediction performance
is still an under-explored problem. Existing research either focuses only on
ranking performance by not calibrating model outputs, or treats grades as
numerical values, assuming labels are on a linear scale and failing to leverage
the ordinal grade information. In this paper, we conduct a rigorous study of
learning to rank with grades, where both ranking performance and grade
prediction performance are important. We provide a formal discussion on how to
perform ranking with non-scalar predictions for grades, and propose a
multiobjective formulation to jointly optimize both ranking and grade
predictions. In experiments, we verify on several public datasets that our
methods are able to push the Pareto frontier of the tradeoff between ranking
and grade prediction performance, showing the benefit of leveraging ordinal
grade information
Road profile estimation for suspension system based on the minimum model error criterion combined with a Kalman filter
This paper presents a novel approach for improving the estimation accuracy of the road profile for a vehicle suspension system. To meet the requirements of road profile estimation for road management and reproduction of system excitation, previous studies can be divided into data-driven and model based approaches. These studies mainly focused on road profile estimation while seldom considering the uncertainty of parameters. However, uncertainty is unavoidable for various aspects of suspension system, e.g., varying sprung mass, damper and tire nonlinear performance. In this study, to improve the estimation accuracy for a varying sprung mass, a novel algorithm was derived based on the Minimum Model Error (MME) criterion and a Kalman Filter (KF). Since the MME criterion method utilizes the minimum value principle to solve the model error based on a model error function, the MME criterion can effectively deal with the estimation error. Then, the proposed algorithm was applied to a 2 degree-of-freedom (DOF) suspension system model under ISO Level-B, ISO Level-C and ISO Level-D road excitations. Simulation results and experimental data obtained using a quarter-vehicle test rig revealed that the proposed approach achieves higher road estimation accuracy compared to traditional KF methods
[3,5-Bis(benzyloxy)phenyl]methanol
In the title compound, C21H20O3, the two terminal phenyl rings are each approximately perpendicular to the central benzene ring, making dihedral angles of 84.40 (16) and 75.12 (15)°. The H atom of the hydroxy group is disordered over two positions with equal occupancies. The molecules are linked by O—H⋯O hydrogen bonds, forming a chain along the a axis
Y Chromosomes of 40% Chinese Are Descendants of Three Neolithic Super-grandfathers
Demographic change of human populations is one of the central questions for
delving into the past of human beings. To identify major population expansions
related to male lineages, we sequenced 78 East Asian Y chromosomes at 3.9 Mbp
of the non-recombining region (NRY), discovered >4,000 new SNPs, and identified
many new clades. The relative divergence dates can be estimated much more
precisely using molecular clock. We found that all the Paleolithic divergences
were binary; however, three strong star-like Neolithic expansions at ~6 kya
(thousand years ago) (assuming a constant substitution rate of 1e-9/bp/year)
indicates that ~40% of modern Chinese are patrilineal descendants of only three
super-grandfathers at that time. This observation suggests that the main
patrilineal expansion in China occurred in the Neolithic Era and might be
related to the development of agriculture.Comment: 29 pages of article text including 1 article figure, 9 pages of SI
text, and 2 SI figures. 5 SI tables are in a separate ancillary fil
Evaluation of a novel saliva-based epidermal growth factor receptor mutation detection for lung cancer: A pilot study.
BackgroundThis article describes a pilot study evaluating a novel liquid biopsy system for non-small cell lung cancer (NSCLC) patients. The electric field-induced release and measurement (EFIRM) method utilizes an electrochemical biosensor for detecting oncogenic mutations in biofluids.MethodsSaliva and plasma of 17 patients were collected from three cancer centers prior to and after surgical resection. The EFIRM method was then applied to the collected samples to assay for exon 19 deletion and p.L858 mutations. EFIRM results were compared with cobas results of exon 19 deletion and p.L858 mutation detection in cancer tissues.ResultsThe EFIRM method was found to detect exon 19 deletion with an area under the curve (AUC) of 1.0 in both saliva and plasma samples in lung cancer patients. For L858R mutation detection, the AUC of saliva was 1.0, while the AUC of plasma was 0.98. Strong correlations were also found between presurgery and post-surgery samples for both saliva (0.86 for exon 19 and 0.98 for L858R) and plasma (0.73 for exon 19 and 0.94 for L858R).ConclusionOur study demonstrates the feasibility of utilizing EFIRM to rapidly, non-invasively, and conveniently detect epidermal growth factor receptor mutations in the saliva of patients with NSCLC, with results corresponding perfectly with the results of cobas tissue genotyping
Large-scale phosphoproteome analysis in seedling leaves of Brachypodium distachyon L.
BACKGROUND: Protein phosphorylation is one of the most important post-translational modifications involved in the regulation of plant growth and development as well as diverse stress response. As a member of the Poaceae, Brachypodium distachyon L. is a new model plant for wheat and barley as well as several potential biofuel grasses such as switchgrass. Vegetative growth is vital for biomass accumulation of plants, but knowledge regarding the role of protein phosphorylation modification during vegetative growth, especially in biofuel plants, is far from comprehensive. RESULTS: In this study, we carried out the first large-scale phosphoproteome analysis of seedling leaves in Brachypodium accession Bd21 using TiO(2) microcolumns combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) and MaxQuant software. A total of 1470 phosphorylation sites in 950 phosphoproteins were identified, and these phosphoproteins were implicated in various molecular functions and basic cellular processes by gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses. Among the 950 phosphoproteins identified, 127 contained 3 to 8 phosphorylation sites. Conservation analysis showed that 93.4% of the 950 phosphoproteins had phosphorylation orthologs in other plant species. Motif-X analysis of the phosphorylation sites identified 13 significantly enriched phosphorylation motifs, of which 3 were novel phosphorylation motifs. Meanwhile, there were 91 phosphoproteins with both multiple phosphorylation sites and multiple phosphorylation motifs. In addition, we identified 58 phosphorylated transcription factors across 21 families and found out 6 significantly over-represented transcription factor families (C3H, Trihelix, CAMTA, TALE, MYB_related and CPP). Eighty-four protein kinases (PKs), 8 protein phosphatases (PPs) and 6 CESAs were recognized as phosphoproteins. CONCLUSIONS: Through a large-scale bioinformatics analysis of the phosphorylation data in seedling leaves, a complicated PKs- and PPs- centered network related to rapid vegetative growth was deciphered in B. distachyon. We revealed a MAPK cascade network that might play the crucial roles during the phosphorylation signal transduction in leaf growth and development. The phosphoproteins and phosphosites identified from our study expanded our knowledge of protein phosphorylation modification in plants, especially in monocots. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/1471-2164-15-375) contains supplementary material, which is available to authorized users
Major Population Expansion of East Asians Began before Neolithic Time: Evidence of mtDNA Genomes
It is a major question in archaeology and anthropology whether human populations started to grow primarily after the advent of agriculture, i.e., the Neolithic time, especially in East Asia, which was one of the centers of ancient agricultural civilization. To answer this question requires an accurate estimation of the time of lineage expansion as well as that of population expansion in a population sample without ascertainment bias. In this study, we analyzed all available mtDNA genomes of East Asians ascertained by random sampling, a total of 367 complete mtDNA sequences generated by the 1000 Genome Project, including 249 Chinese (CHB, CHD, and CHS) and 118 Japanese (JPT). We found that major mtDNA lineages underwent expansions, all of which, except for two JPT-specific lineages, including D4, D4b2b, D4a, D4j, D5a2a, A, N9a, F1a1'4, F2, B4, B4a, G2a1 and M7b1'2'4, occurred before 10 kya, i.e., before the Neolithic time (symbolized by Dadiwan Culture at 7.9 kya) in East Asia. Consistent to this observation, the further analysis showed that the population expansion in East Asia started at 13 kya and lasted until 4 kya. The results suggest that the population growth in East Asia constituted a need for the introduction of agriculture and might be one of the driving forces that led to the further development of agriculture
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