28,973 research outputs found
Origins of the Isospin Violation of Dark Matter Interactions
Light dark matter (DM) with a large DM-nucleon spin-independent cross section
and furthermore proper isospin violation (ISV) may provide
a way to understand the confusing DM direct detection results. Combing with the
stringent astrophysical and collider constraints, we systematically investigate
the origin of ISV first via general operator analyses and further via
specifying three kinds of (single) mediators: A light from chiral
, an approximate spectator Higgs doublet (It can explain the
anomaly simultaneously) and color triplets. In addition, although from an
exotic mixing with generating , we can combine it with
the conventional Higgs to achieve proper ISV. As a concrete example, we propose
the model where the charged light sneutrino is the inelastic
DM, which dominantly annihilates to light dark states such as with sub-GeV
mass. This model can address the recent GoGeNT annual modulation consistent
with other DM direct detection results and free of exclusions.Comment: References added and English greatly improve
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Economic policy uncertainty and mergers and acquisitions: Evidence from China
Complete genomic analysis of a kingdom-crossing Klebsiella variicola isolate
© 2018 Guo, Zhai, Zhang, Li, Wang, Li, He, Hu, Kang and Gao. Bacterial isolate X39 was isolated from a community-acquired pneumonia patient in Beijing, China. A phylogenetic tree based on rpoB genes and average nucleotide identity data confirmed that isolate X39 belonged to Klebsiella variicola. The genome of K variicola X39 contained one circular chromosome and nine plasmids. Comparative genomic analyses with other K variicola isolates revealed that K variicola X39 contained the most unique genes. Of these unique genes, many were prophages and transposases. Many virulence factors were shared between K variicola X39 and Klebsiella pneumoniae F1. The pathogenicity of K. variicola X39 was compared with that of K. pneumoniae F1 in an abdominal infection model. The results indicated that K. variicola X39 was less virulent than typical clinical K. pneumoniae F1. The genome of K. variicola X39 also contained some genes involved in plant colonization, nitrogen fixation, and defense against oxidative stress. GFP-labeled K. variicola X39 could colonize maize as an endophytic bacterium. We concluded that K. variicola X39 was a kingdom-crossing strain
Two-dimensional structures of ferroelectric domain inversion in LiNbO3 by direct electron beam lithography
We report on the fabrication of domain-reversed structures in LiNbO3 by means
of direct electron beam lithography at room temperature without any static
bias. The LiNbO3 crystals were chemically etched after the exposure of electron
beam and then, the patterns of domain inversion were characterized by atomic
force microscopy (AFM). In our experiment, an interesting phenomenon occurred
when the electron beam wrote a one-dimensional (1-D) grating on the negative
c-face: a two-dimensional (2-D) dotted array was observed on the positive c-
face, which is significant for its potential to produce 2-D and
three-dimensional photonic crystals. Furthermore, we also obtained 2-D
ferroelectric domain inversion in the whole LiNbO3 crystal by writing the 2-D
square pattern on the negative c-face. Such a structure may be utilized to
fabricate 2-D nonlinear photonic crystal. AFM demonstrates that a 2-D
domain-reversed structure has been achieved not only on the negative c-face of
the crystal, but also across the whole thickness of the crystal.Comment: 17 pages, 4 figure
Genomic characterization of an emerging Enterobacteriaceae species: the first case of co-infection with a typical pathogen in a human patient.
BackgroundOpportunistic pathogens are important for clinical practice as they often cause antibiotic-resistant infections. However, little is documented for many emerging opportunistic pathogens and their biological characteristics. Here, we isolated a strain of extended-spectrum β-lactamase-producing Enterobacteriaceae from a patient with a biliary tract infection. We explored the biological and genomic characteristics of this strain to provide new evidence and detailed information for opportunistic pathogens about the co-infection they may cause.ResultsThe isolate grew very slowly but conferred strong protection for the co-infected cephalosporin-sensitive Klebsiella pneumoniae. As the initial laboratory testing failed to identify the taxonomy of the strain, great perplexity was caused in the etiological diagnosis and anti-infection treatment for the patient. Rigorous sequencing efforts achieved the complete genome sequence of the isolate which we designated as AF18. AF18 is phylogenetically close to a few strains isolated from soil, clinical sewage, and patients, forming a novel species together, while the taxonomic nomenclature of which is still under discussion. And this is the first report of human infection of this novel species. Like its relatives, AF18 harbors many genes related to cell mobility, various genes adaptive to both the natural environment and animal host, over 30 mobile genetic elements, and a plasmid bearing blaCTX-M-3 gene, indicating its ability to disseminate antimicrobial-resistant genes from the natural environment to patients. Transcriptome sequencing identified two sRNAs that critically regulate the growth rate of AF18, which could serve as targets for novel antimicrobial strategies.ConclusionsOur findings imply that AF18 and its species are not only infection-relevant but also potential disseminators of antibiotic resistance genes, which highlights the need for continuous monitoring for this novel species and efforts to develop treatment strategies
CentralNet: a Multilayer Approach for Multimodal Fusion
This paper proposes a novel multimodal fusion approach, aiming to produce
best possible decisions by integrating information coming from multiple media.
While most of the past multimodal approaches either work by projecting the
features of different modalities into the same space, or by coordinating the
representations of each modality through the use of constraints, our approach
borrows from both visions. More specifically, assuming each modality can be
processed by a separated deep convolutional network, allowing to take decisions
independently from each modality, we introduce a central network linking the
modality specific networks. This central network not only provides a common
feature embedding but also regularizes the modality specific networks through
the use of multi-task learning. The proposed approach is validated on 4
different computer vision tasks on which it consistently improves the accuracy
of existing multimodal fusion approaches
Genetic factors related to the widespread dissemination of ST11 extensively drug-resistant carbapenemase-producing Klebsiella pneumoniae strains within hospital.
BackgroundCarbapenemase-producing Klebsiella pneumoniae (CP-Kp) poses distinct clinical challenges due to extensively drug resistant (XDR) phenotype, and sequence type (ST) 11 is the most dominant blaKPC-2-bearing CP-Kp clone in China. The purpose of this current retrospective study was to explore the genetic factors associated with the success of XDR CP-Kp ST11 strains circulated in the intensive care unit (ICU) of a Chinese tertiary hospital.MethodsSix ST11 XDR CP-Kp strains were identified between May and December 2014 and validated by minimum inhibitory concentration examination, polymerase chain reaction, and pyrosequencing. The six ST11 XDR CP-Kp, as well as three multi-drug resistant (MDR) and four susceptible strains, were sequenced using single-molecule real-time method. Comprehensively structural and functional analysis based on comparative genomics was performed to identify genomic characteristics of the XDR ST11 CP-Kp strains.ResultsWe found that ST11 XDR blaKPC-2-bearing CP-Kp strains isolated from inpatients spread in the ICU of the hospital. Functionally, genes associated with information storage and processing of the ST11 XDR CP-Kp strains were more abundant than those of MDR and susceptible strains, especially genes correlative with mobile genetic elements (MGEs) such as transposons and prophages. Structurally, eleven large-scale genetic regions taken for the unique genome in these ST11 XDR CP-Kp strains were identified as MGEs including transposons, integrons, prophages, genomic islands, and integrative and conjugative elements. Three of them were located on plasmids and eight on chromosomes; five of them were with antimicrobial resistance genes and eight with adaptation associated genes. Notably, a new blaKPC-2-bearing ΔΔTn1721-blaKPC-2 transposon, probably transposed and truncated from ΔTn1721-blaKPC-2 by IS903D and ISKpn8, was identified in all six ST11 XDR CP-Kp strains.ConclusionOur findings suggested that together with clonal spread, MGEs identified uniquely in the ST11 XDR CP-Kp strains might contribute to their formidable adaptability, which facilitated their widespread dissemination in hospital
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