3,834 research outputs found
Dissipationless Layertronics in Axion Insulator
Surface electrons in axion insulators are endowed with a topological layer
degree of freedom followed by exotic transport phenomena, e.g., the layer Hall
effect [Gao et al., Nature 595, 521 (2021)]. Here, we propose that such a layer
degree of freedom can be manipulated in a dissipationless way based on the
antiferromagnetic with tailored domain structure. This makes
a versatile platform to exploit the "layertronics" to encode,
process, and store information. Importantly, the layer filter, layer valve, and
layer reverser devices can be achieved using the layer-locked chiral domain
wall modes. The dissipationless nature of the domain wall modes makes the
performance of the layertronic-devices superior to those in spintronics and
valleytronics. Specifically, the layer reverser, a layer version of Datta-Das
transistor, also fills up the blank in designing the valley reverser in
valleytronics. Our work sheds light on constructing new generation electronic
devices with high performance and low energy consumption in the framework of
layertronics.Comment: 7 pages, 4 figures (+Supplementary Materials: 5 pages, 6 figures
Order picking optimization with order assignment and multiple workstations in KIVA warehouses
We consider the problem of allocating orders and racks to multiple stations
and sequencing their interlinked processing flows at each station in the
robot-assisted KIVA warehouse. The various decisions involved in the problem,
which are closely associated and must be solved in real time, are often tackled
separately for ease of treatment. However, exploiting the synergy between order
assignment and picking station scheduling benefits picking efficiency. We
develop a comprehensive mathematical model that takes the synergy into
consideration to minimize the total number of rack visits. To solve this
intractable problem, we develop an efficient algorithm based on simulated
annealing and dynamic programming. Computational studies show that the proposed
approach outperforms the rule-based policies used in practice in terms of
solution quality. Moreover, the results reveal that ignoring the order
assignment policy leads to considerable optimality gaps for real-world-sized
instances
Neutralization of Diverse Human Cytomegalovirus Strains Conferred by Antibodies Targeting Viral gH/gL/pUL128-131 Pentameric Complex
Human cytomegalovirus (HCMV) is the leading cause of congenital viral infection, and developing a prophylactic vaccine is of high priority to public health. We recently reported a replication-defective human cytomegalovirus with restored pentameric complex glycoprotein H (gH)/gL/pUL128-131 for prevention of congenital HCMV infection. While the quantity of vaccine-induced antibody responses can be measured in a viral neutralization assay, assessing the quality of such responses, including the ability of vaccine-induced antibodies to cross-neutralize the field strains of HCMV, remains a challenge. In this study, with a panel of neutralizing antibodies from three healthy human donors with natural HCMV infection or a vaccinated animal, we mapped eight sites on the dominant virus-neutralizing antigen-the pentameric complex of glycoprotein H (gH), gL, and pUL128, pUL130, and pUL131. By evaluating the site-specific antibodies in vaccine immune sera, we demonstrated that vaccination elicited functional antiviral antibodies to multiple neutralizing sites in rhesus macaques, with quality attributes comparable to those of CMV hyperimmune globulin. Furthermore, these immune sera showed antiviral activities against a panel of genetically distinct HCMV clinical isolates. These results highlighted the importance of understanding the quality of vaccine-induced antibody responses, which includes not only the neutralizing potency in key cell types but also the ability to protect against the genetically diverse field strains. IMPORTANCE HCMV is the leading cause of congenital viral infection, and development of a preventive vaccine is a high public health priority. To understand the strain coverage of vaccine-induced immune responses in comparison with natural immunity, we used a panel of broadly neutralizing antibodies to identify the immunogenic sites of a dominant viral antigen-the pentameric complex. We further demonstrated that following vaccination of a replication-defective virus with the restored pentameric complex, rhesus macaques can develop broadly neutralizing antibodies targeting multiple immunogenic sites of the pentameric complex. Such analyses of site-specific antibody responses are imperative to our assessment of the quality of vaccine-induced immunity in clinical studies
Moir\'{e} Flat Bands of Twisted Few-layer Graphite
We report that the twisted few layer graphite (tFL-graphite) is a new family
of moir\'{e} heterostructures (MHSs), which has richer and highly tunable
moir\'{e} flat band structures entirely distinct from all the known MHSs. A
tFL-graphite is composed of two few-layer graphite (Bernal stacked multilayer
graphene), which are stacked on each other with a small twisted angle. The
moir\'{e} band structure of the tFL-graphite strongly depends on the layer
number of its composed two van der Waals layers. Near the magic angle, a
tFL-graphite always has two nearly flat bands coexisting with a few pairs of
narrowed dispersive (parabolic or linear) bands at the Fermi level, thus,
enhances the DOS at . This coexistence property may also enhance the
possible superconductivity as been demonstrated in other multiband
superconductivity systems. Therefore, we expect strong multiband correlation
effects in tFL-graphite. Meanwhile, a proper perpendicular electric field can
induce several isolated nearly flat bands with nonzero valley Chern number in
some simple tFL-graphites, indicating that tFL-graphite is also a novel
topological flat band system.Comment: Submitted version,supplementary materials are adde
The Energy-dependent Checkerboard Patterns in Cuprate Superconductors
Motivated by the recent scanning tunneling microscopy (STM) experiments [J.
E. Hoffman {\it et al.}, Science {\bf 297}, 1148 (2002); K. McElroy {\it et
al.}, Nature (to be published)], we investigate the real space local density of
states (LDOS) induced by weak disorder in a d-wave superconductor. We first
present the energy dependent LDOS images around a single weak defect at several
energies, and then point out that the experimentally observed checkerboard
pattern in the LDOS could be understood as a result of quasiparticle
interferences by randomly distributed defects. It is also shown that the
checkerboard pattern oriented along to the Cu-O bonds at low energies
would transform to that oriented parallel to the Cu-O bonds at higher energies.
This result is consistent with the experiments.Comment: 3 pages, 3 figure
Generation of GHZ-type and \emph{W}-type entangled coherent states of three-cavity fields
We present experimental schemes to prepare the three-cavity GHZ-type and
\emph{W}-type entangled coherent states in the context of dispersive cavity
quantum electrodynamics. The schemes can be easily generalized to prepare the
GHZ-type and \emph{W}-type entangled coherent states of -cavity fields. The
discussion of our schemes indicates that it can be realized by current
technologies.Comment: 4 pages, 2 figure
Molecular genetic analysis reveals that a nonribosomal peptide synthetase-like (NRPS-like) gene in Aspergillus nidulans is responsible for microperfuranone biosynthesis
Genome sequencing of Aspergillus species including Aspergillus nidulans has revealed that there are far more secondary metabolite biosynthetic gene clusters than secondary metabolites isolated from these organisms. This implies that these organisms can produce additional secondary metabolites, which have not yet been elucidated. The A. nidulans genome contains 12 nonribosomal peptide synthetase (NRPS), one hybrid polyketide synthase/NRPS, and 14 NRPS-like genes. The only NRPS-like gene in A. nidulans with a known product is tdiA, which is involved in terrequinone A biosynthesis. To attempt to identify the products of these NRPS-like genes, we replaced the native promoters of the NRPS-like genes with the inducible alcohol dehydrogenase (alcA) promoter. Our results demonstrated that induction of the single NRPS-like gene AN3396.4 led to the enhanced production of microperfuranone. Furthermore, heterologous expression of AN3396.4 in Aspergillus niger confirmed that only one NRPS-like gene, AN3396.4, is necessary for the production of microperfuranone
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