5,960 research outputs found

    Magnon-induced non-Markovian friction of a domain wall in a ferromagnet

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    Motivated by the recent study on the quasiparticle-induced friction of solitons in superfluids, we theoretically study magnon-induced intrinsic friction of a domain wall in a one-dimensional ferromagnet. To this end, we start by obtaining the hitherto overlooked dissipative interaction of a domain wall and its quantum magnon bath to linear order in the domain-wall velocity and to quadratic order in magnon fields. An exact expression for the pertinent scattering matrix is obtained with the aid of supersymmetric quantum mechanics. We then derive the magnon-induced frictional force on a domain wall in two different frameworks: time-dependent perturbation theory in quantum mechanics and the Keldysh formalism, which yield identical results. The latter, in particular, allows us to verify the fluctuation-dissipation theorem explicitly by providing both the frictional force and the correlator of the associated stochastic Langevin force. The potential for magnons induced by a domain wall is reflectionless, and thus the resultant frictional force is non-Markovian similarly to the case of solitons in superfluids. They share an intriguing connection to the Abraham-Lorentz force that is well-known for its causality paradox. The dynamical responses of a domain wall are studied under a few simple circumstances, where the non-Markovian nature of the frictional force can be probed experimentally. Our work, in conjunction with the previous study on solitons in superfluids, shows that the macroscopic frictional force on solitons can serve as an effective probe of the microscopic degrees of freedom of the system.Comment: 13 pages, 2 figure

    Establishment of the Watershed Image Classified Rule-Set and Feasibility Assessment of Its Application

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    Extreme weather disasters are widely distributed. Moreover, the mutual relations between such disasters can easily make them even more extensive. Rapidly obtained satellite images of vast areas can be effective in helping to develop disaster prevention strategies. This study established a watershed satellite image classification rule-set by using the object-based image analysis methodology. Several surface features in the watershed image were been classified, including main channels, secondary channels, sandbars, alluvial fans, landslides and place of the geotechnical damage. This study practically applied this rule-set in different watersheds and different-resolution satellite image. Also assessed the feasibility of the rule-set by comparing with the investigation photos and statistical analysis. The results show that the rule-set logic can be applied flexibly in different watersheds and different images. The classification of the rule-set is reproducible and accurate. As this result, we can apply the rule-set to disaster management and the land use planning in the future work.極端氣候下的災害事件分布廣泛,且相互影響之關聯性易使災害規模擴大,藉由衛星 影像判釋具廣域且快速的特色能夠有效協助研擬防災策略。本研究建立一套流域衛星影像分類 之規則集,當中引入物件式影像分析方法,使分類流程依據人工判釋之經驗與知識,針對流域 影像分類出周邊河川地形單元、崩塌地以及地工災害的位置。實際應用此規則集於不同流域以 及不同解析度之衛星影像,透過比對現地勘查資料和計算誤差矩陣來評估其邏輯之可行程度。 結果顯示,本研究所建立之規則集邏輯泛用於不同流域、不同影像,且任何使用者之操作經過 適當的調整皆具有重現性及相當的判釋精度,提供災害管理、土地利用之深入探討一項工具

    A Study of Parton Energy Loss in Au+Au Collisions at RHIC using Transport Theory

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    Parton energy loss in Au+Au collisions at RHIC energies is studied by numerically solving the relativistic Boltzmann equation for the partons including 222 \leftrightarrow 2 and 22+finalstateradiation2 \to 2 + final state radiation collision processes. Final particle spectra are obtained using two hadronization models; the Lund string fragmentation and independent fragmentation models. Recent, preliminary π0\pi^0 transverse momentum distributions from central Au+Au collisions at RHIC are reproduced using gluon-gluon scattering cross sections of 5-12 mb, depending upon the hadronization model. Comparisons with the HIJING jet quenching algorithm are made.Comment: 6 pages, 6 figures, attached files are replaced (wrong files were uploaded in version 1

    Whole-genome sequencing of cultivated and wild peppers provides insights into Capsicum domestication and specialization

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    As an economic crop, pepper satisfies people's spicy taste and has medicinal uses worldwide. To gain a better understanding of Capsicum evolution, domestication, and specialization, we present here the genome sequence of the cultivated pepper Zunla-1 (C. annuum L.) and its wild progenitor Chiltepin (C. annuum var. glabriusculum). We estimate that the pepper genome expanded similar to 0.3 Mya (with respect to the genome of other Solanaceae) by a rapid amplification of retrotransposons elements, resulting in a genome comprised of similar to 81% repetitive sequences. Approximately 79% of 3.48-Gb scaffolds containing 34,476 protein-coding genes were anchored to chromosomes by a high-density genetic map. Comparison of cultivated and wild pepper genomes with 20 resequencing accessions revealed molecular footprints of artificial selection, providing us with a list of candidate domestication genes. We also found that dosage compensation effect of tandem duplication genes probably contributed to the pungent diversification in pepper. The Capsicum reference genome provides crucial information for the study of not only the evolution of the pepper genome but also, the Solanaceae family, and it will facilitate the establishment of more effective pepper breeding programs

    Transcriptomic analyses of regenerating adult feathers in chicken

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    Transcriptome Expression Data. Table of mapped reads to Galgal4 transcripts for all 15 data sets. FPKM (Fragments per kilobase of exon per million fragments mapped): normalized transcript abundance values for each gene in the indicated tissues. (CSV 1314 kb

    Parton-Hadron-String Dynamics: an off-shell transport approach for relativistic energies

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    The dynamics of partons, hadrons and strings in relativistic nucleus-nucleus collisions is analyzed within the novel Parton-Hadron-String Dynamics (PHSD) transport approach, which is applied to Pb+Pb collisions from 20 to 160 A GeV in order to explore the space-time regions of 'partonic matter'. We find that even central collisions at the top-SPS energy of 158 A GeV show a large fraction of non-partonic, i.e. hadronic or string-like matter, which can be viewed as a hadronic corona. Furthermore, we observe that the partonic phase has a very low impact on rapidity distributions of hadrons but a sizeable influence on the transverse mass distribution of final kaons due to the repulsive partonic mean fields. We also find a significant effect on the production of multi-strange antibaryons due to a slightly enhanced ssˉs{\bar s} pair production in the partonic phase from massive time-like gluon decay and a larger formation of antibaryons in the hadronization process. All differential hadron spectra are analyzed in comparison to the data of experimental collaborations.Comment: 33 pages, 23 figures, submitted to Nulc. Phys.

    High-Performance Flexible Quasi-Solid-State Supercapacitors Realized by Molybdenum Dioxide@Nitrogen-Doped Carbon and Copper Cobalt Sulfide Tubular Nanostructures

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    Flexible quasi‐/all‐solid‐state supercapacitors have elicited scientific attention to fulfill the explosive demand for portable and wearable electronic devices. However, the use of electrode materials faces several challenges, such as intrinsically slow kinetics and volume change upon cycling, which impede the energy output and electrochemical stability. This study presents well‐aligned molybdenum dioxide@nitrogen‐doped carbon (MoO2@NC) and copper cobalt sulfide (CuCo2S4) tubular nanostructures grown on flexible carbon fiber for use as electrode materials in supercapacitors. Benefiting from the chemically stable interfaces, affluent active sites, and efficient 1D electron transport, the MoO2@NC and CuCo2S4 nanostructures integrated on conductive substrates deliver excellent electrochemical performance. A flexible quasi‐solid‐state asymmetric supercapacitor composed of MoO2@NC as the negative electrode and CuCo2S4 as the positive electrode achieves an ultrahigh energy density of 65.1 W h kg−1 at a power density of 800 W kg−1 and retains a favorable energy density of 27.6 W h kg−1 at an ultrahigh power density of 12.8 kW kg−1. Moreover, it demonstrates good cycling performance with 90.6% capacitance retention after 5000 cycles and excellent mechanical flexibility by enabling 92.2% capacitance retention after 2000 bending cycles. This study provides an effective strategy to develop electrode materials with superior electrochemical performance for flexible supercapacitors

    Genomic, Pathway Network, and Immunologic Features Distinguishing Squamous Carcinomas

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    This integrated, multiplatform PanCancer Atlas study co-mapped and identified distinguishing molecular features of squamous cell carcinomas (SCCs) from five sites associated with smokin

    An Integrated TCGA Pan-Cancer Clinical Data Resource to Drive High-Quality Survival Outcome Analytics

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    For a decade, The Cancer Genome Atlas (TCGA) program collected clinicopathologic annotation data along with multi-platform molecular profiles of more than 11,000 human tumors across 33 different cancer types. TCGA clinical data contain key features representing the democratized nature of the data collection process. To ensure proper use of this large clinical dataset associated with genomic features, we developed a standardized dataset named the TCGA Pan-Cancer Clinical Data Resource (TCGA-CDR), which includes four major clinical outcome endpoints. In addition to detailing major challenges and statistical limitations encountered during the effort of integrating the acquired clinical data, we present a summary that includes endpoint usage recommendations for each cancer type. These TCGA-CDR findings appear to be consistent with cancer genomics studies independent of the TCGA effort and provide opportunities for investigating cancer biology using clinical correlates at an unprecedented scale. Analysis of clinicopathologic annotations for over 11,000 cancer patients in the TCGA program leads to the generation of TCGA Clinical Data Resource, which provides recommendations of clinical outcome endpoint usage for 33 cancer types
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