287 research outputs found
Mathematical theory for the interface mode in a waveguide bifurcated from a Dirac point
In this paper, we prove the existence of a bound state in a waveguide that
consists of two semi-infinite periodic structures separated by an interface.
The two periodic structures are perturbed from the same periodic medium with a
Dirac point and they possess a common band gap enclosing the Dirac point. The
bound state, which is called interface mode here, decays exponentially away
from the interface with a frequency located in the common band gap and can be
viewed as a bifurcation from the Dirac point. Using the layer potential
technique and asymptotic analysis, we first characterize the band gap opening
for the two perturbed periodic media and derive the asymptotics of the Bloch
modes near the band gap edges. By formulating the eigenvalue problem for the
waveguide with two semi-infinite structures using a boundary integral equation
over the interface and analyzing the characteristic values of the associated
boundary integral operator, we prove the existence of the interface mode for
the waveguide when the perturbation of the periodic medium is small
The -convergence at the Neumann boundary for Liouville equations
In this paper, we study the blow-up analysis for a sequence of solutions to
the Liouville type equation with exponential Neumann boundary condition. For
interior case, i.e. the blow-up point is an interior point, Li \cite{Li} gave a
uniform asymptotic estimate. Later, Zhang \cite{Zhang} and Gluck \cite{Gluck}
improved Li's estimate in the sense of -convergence by using the method of
moving planes or classification of solutions of the linearized version of
Liouville equation. If the sequence blows up at a boundary point, Bao-Wang-Zhou
\cite{Bao-Wang-Zhou} proved a similar asymptotic estimate of Li \cite{Li}. In
this paper, we will prove a -convergence result in this boundary blow-up
process. Our method is different from \cite{Zhang,Gluck}.Comment: 26 page
Charge transport and electron-hole asymmetry in low-mobility graphene/hexagonal boron nitride heterostructures
Graphene/hexagonal boron nitride (G/-BN) heterostructures offer an
excellent platform for developing nanoelectronic devices and for exploring
correlated states in graphene under modulation by a periodic superlattice
potential. Here, we report on transport measurements of nearly
-twisted G/-BN heterostructures. The heterostructures
investigated are prepared by dry transfer and thermally annealing processes and
are in the low mobility regime (approximately
at 1.9 K). The replica
Dirac spectra and Hofstadter butterfly spectra are observed on the hole
transport side, but not on the electron transport side, of the
heterostructures. We associate the observed electron-hole asymmetry to the
presences of a large difference between the opened gaps in the conduction and
valence bands and a strong enhancement in the interband contribution to the
conductivity on the electron transport side in the low-mobility G/-BN
heterostructures. We also show that the gaps opened at the central Dirac point
and the hole-branch secondary Dirac point are large, suggesting the presence of
strong graphene-substrate interaction and electron-electron interaction in our
G/-BN heterostructures. Our results provide additional helpful insight into
the transport mechanism in G/-BN heterostructures.Comment: 7 pages, 4 figure
PhaBOX: A web server for identifying and characterizing phage contigs in metagenomic data
Motivation: There is accumulating evidence showing the important roles of
bacteriophages (phages) in regulating the structure and functions of
microbiome. However, lacking an easy-to-use and integrated phage analysis
software hampers microbiome-related research from incorporating phages in the
analysis.
Results: In this work, we developed a web server, PhaBOX, to comprehensively
identify and analyze phage contigs in metagenomic data. To our best knowledge,
this is the first web server that supports integrated phage analysis, including
detecting phage contigs from the metagenomic assembly, lifestyle prediction,
taxonomic classification, and host prediction. Instead of treating the
algorithms as a black box, PhaBOX also supports visualization of the essential
features for making predictions. With the user-friendly graphical interface,
users with or without informatics training can easily use the web server for
analyzing phages in microbiome data.
Availability: The web server of PhaBOX is available via:
https://phage.ee.cityu.edu.hk. The source code of PhaBOX is available via:
https://github.com/KennthShang/PhaBOXComment: 5 pages, 1 figur
COMPUTE N-WAY DE-DUPLICATED REACH USING PRIVACY SAFE VECTOR OF COUNTS
Systems and methods for determining the union of the set of user identifiers across multiple publishers are described. Each publisher computing device can use a list of hash functions to hash the respective set of de-duplicated user identifiers. Each publisher can assemble a vector of counts using the respective hashed set of user identifiers, where each coordinate in the vector of counts corresponds to a select of bit positions from the hashed set of user identifiers. Each publisher can add noise to each of the vector of counts to enhance the privacy of the system. Each publisher can transmit the respective vector of counts to a server to compute the union of the multiset without exposing any private or protected information about the user identifiers to any third-party. The server can compute the union of the sets described by the vectors of counts from each of the publishers using at least one of the methods described herein
Phage family classification under Caudoviricetes: A review of current tools using the latest ICTV classification framework
Bacteriophages, which are viruses infecting bacteria, are the most ubiquitous and diverse entities in the biosphere. There is accumulating evidence revealing their important roles in shaping the structure of various microbiomes. Thanks to (viral) metagenomic sequencing, a large number of new bacteriophages have been discovered. However, lacking a standard and automatic virus classification pipeline, the taxonomic characterization of new viruses seriously lag behind the sequencing efforts. In particular, according to the latest version of ICTV, several large phage families in the previous classification system are removed. Therefore, a comprehensive review and comparison of taxonomic classification tools under the new standard are needed to establish the state-of-the-art. In this work, we retrained and tested four recently published tools on newly labeled databases. We demonstrated their utilities and tested them on multiple datasets, including the RefSeq, short contigs, simulated metagenomic datasets, and low-similarity datasets. This study provides a comprehensive review of phage family classification in different scenarios and a practical guidance for choosing appropriate taxonomic classification pipelines. To our best knowledge, this is the first review conducted under the new ICTV classification framework. The results show that the new family classification framework overall leads to better conserved groups and thus makes family-level classification more feasible
Managing rather than Avoiding âDifficultiesâ in Building Landscape Resilience
Building landscape resilience inspires the cultivation of the landscapeâs capacity to recover from disruption and live with changes and uncertainties. However, integrating ecosystem and society within such a unified lensâthat is, socioâecological system (SES) resilienceâclashes with many cornerstone concepts in social science, such as power, democracy, rights, and culture. In short, a landscape cannot provide the same values to everyone. However, can building landscape resilience be an effective and just environmental management strategy? Research on this question is limited. A scoping literature review was conducted first to synthesise and map landscape management change based on 111,653 records. Then, we used the Nuozhadu (NZD) catchment as a case study to validate our findings from the literature. We summarised current critiques and created a framework including seven normative categories, or common difficulties, namely resilience for âwhomâ, âwhatâ, âwhenâ, âwhereâ, âwhyâ, as well as âcanâ and âhowâ we apply resilience normatively. We found that these difficulties are overlooked and avoided despite their instructive roles to achieve just landscape management more transparently. Without clear targets and boundaries in building resilience, we found that some groups consume resources and services at the expense of others. The NZD case demonstrates that a strategy of building the NZDâs resilience has improved the conservation of the NZDâs forest ecosystems but overlooked trade-offs between sustaining people and the environment, and between sustainable development for people at different scales. Future researchers, managers, and decision-makers are thereby needed to think resilience more normatively and address the questions in the âseven difficultiesâ framework before intervening to build landscape resilience.This work was supported by the Key Foundation of China Academy of Engineering
Physics, China (Grant No. 2019-ZD-012); the China Postdoctoral Innovative Talents Program (Grant
No. BX201907170); and the China Scholarship Council (CSC) (Grant No. 201808190012)
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