93,414 research outputs found
Intertwined Orders in Holography: Pair and Charge Density Waves
Building on [1], we examine a holographic model in which a U(1) symmetry and
translational invariance are broken spontaneously at the same time. The
symmetry breaking is realized through the St\"{u}ckelberg mechanism, and leads
to a scalar condensate and a charge density which are spatially modulated and
exhibit unidirectional stripe order. Depending on the choice of parameters, the
oscillations of the scalar condensate can average out to zero, with a frequency
which is half of that of the charge density. In this case the system realizes
some of the key features of pair density wave order. The model also admits a
phase with co-existing superconducting and charge density wave orders, in which
the scalar condensate has a uniform component. In our construction the various
orders are intertwined with each other and have a common origin. The fully
backreacted geometry is computed numerically, including for the case in which
the theory contains axions. The latter can be added to explicitly break
translational symmetry and mimic lattice-type effects.Comment: 37 pages, 17 figure
A Systemic Receptor Network Triggered by Human cytomegalovirus Entry
Virus entry is a multistep process that triggers a variety of cellular
pathways interconnecting into a complex network, yet the molecular complexity
of this network remains largely unsolved. Here, by employing systems biology
approach, we reveal a systemic virus-entry network initiated by human
cytomegalovirus (HCMV), a widespread opportunistic pathogen. This network
contains all known interactions and functional modules (i.e. groups of
proteins) coordinately responding to HCMV entry. The number of both genes and
functional modules activated in this network dramatically declines shortly,
within 25 min post-infection. While modules annotated as receptor system, ion
transport, and immune response are continuously activated during the entire
process of HCMV entry, those for cell adhesion and skeletal movement are
specifically activated during viral early attachment, and those for immune
response during virus entry. HCMV entry requires a complex receptor network
involving different cellular components, comprising not only cell surface
receptors, but also pathway components in signal transduction, skeletal
development, immune response, endocytosis, ion transport, macromolecule
metabolism and chromatin remodeling. Interestingly, genes that function in
chromatin remodeling are the most abundant in this receptor system, suggesting
that global modulation of transcriptions is one of the most important events in
HCMV entry. Results of in silico knock out further reveal that this entire
receptor network is primarily controlled by multiple elements, such as EGFR
(Epidermal Growth Factor) and SLC10A1 (sodium/bile acid cotransporter family,
member 1). Thus, our results demonstrate that a complex systemic network, in
which components coordinating efficiently in time and space contributes to
virus entry.Comment: 26 page
Holographic Fermions in Striped Phases
We examine the fermionic response in a holographic model of a low temperature
striped phase, working for concreteness with the setup we studied in
[Cremonini:2016rbd,Cremonini:2017usb], in which a U(1) symmetry and
translational invariance are broken spontaneously at the same time. We include
an ionic lattice that breaks translational symmetry explicitly in the UV of the
theory. Thus, this construction realizes spontaneous crystallization on top of
a background lattice. We solve the Dirac equation for a probe fermion in the
associated background geometry using numerical techniques, and explore the
interplay between spontaneous and explicit breaking of translations. We note
that in our model the breaking of the U(1) symmetry doesn't play a role in the
analysis of the fermionic spectral function. We investigate under which
conditions a Fermi surface can form and focus in particular on how the ionic
lattice affects its structure. When the ionic lattice becomes sufficiently
strong the spectral weight peaks broaden, denoting a gradual disappearance of
the Fermi surface along the symmetry breaking direction. This phenomenon occurs
even in the absence of spontaneously generated stripes. The resulting Fermi
surface appears to consist of detached segments reminiscent of Fermi arcs.Comment: v2: 43 pages, 20 figures. Major revision, title and abstract
modified, new discussion added, conclusions unchanged. To appear in JHE
Thermodynamic stability of small-world oscillator networks: A case study of proteins
We study vibrational thermodynamic stability of small-world oscillator
networks, by relating the average mean-square displacement of oscillators
to the eigenvalue spectrum of the Laplacian matrix of networks. We show that
the cross-links suppress effectively and there exist two phases on the
small-world networks: 1) an unstable phase: when , ; 2) a
stable phase: when , , \emph{i.e.}, . Here, is the parameter of small-world, is the number of
oscillators, and is the number of cross-links. The results are
exemplified by various real protein structures that follow the same scaling
behavior of the stable phase. We also show that it is the
"small-world" property that plays the key role in the thermodynamic stability
and is responsible for the universal scaling , regardless
of the model details.Comment: 7 pages, 5 figures, accepted by Physical Review
Massive Quiescent Cores in Orion: VI. The Internal Structures and a Candidate of Transiting Core in NGC 2024 Filament
We present a multi-wavelength observational study of the NGC 2024 filament
using infrared to sub-millimeter continuum and the NH and
inversion transitions centered on FIR-3, the most massive core therein. FIR-3
is found to have no significant infrared point sources in the Spitzer/IRAC
bands. But the NH kinetic temperature map shows a peak value at the core
center with K which is significantly higher than the surrounding
level ( K). Such internal heating signature without an
infrared source suggests an ongoing core collapse possibly at a transition
stage from first hydrostatic core (FHSC) to protostar. The eight dense cores in
the filament have dust temperatures between 17.5 and 22 K. They are much cooler
than the hot ridge ( K) around the central heating star IRS-2b.
Comparison with a dust heating model suggests that the filament should have a
distance of pc from IRS-2b. This value is much larger than the spatial
extent of the hot ridge, suggesting that the filament is spatially separated
from the hot region along the line of sight.Comment: 20 pages, 7 figures, 6 tables. Accepted to Ap
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