118 research outputs found
Bell Inequality in the Holographic EPR Pair
We study the Bell inequality in a holographic model of the casually
disconnected Einstein-Podolsky-Rosen (EPR) pair. The
Clauser-Horne-Shimony-Holt(CHSH) form of Bell inequality is constructed using
holographic Schwinger-Keldysh (SK) correlators. We show that the manifestation
of quantum correlation in Bell inequality can be holographically reproduced
from the classical fluctuations of dual accelerating string in the bulk
gravity. The violation of this holographic Bell inequality supports the
essential quantum property of this holographic model of an EPR pair.Comment: 8 pages, 2 figures; references and texts added; v3: matches published
versio
Emergent Dark Matter in Late Time Universe on Holographic Screen
We discuss a scenario that the dark matter in late time universe emerges as
part of the holographic stress-energy tensor on the hypersurface in higher
dimensional flat spacetime. Firstly we construct a toy model with a de Sitter
hypersurface as the holographic screen in the flat bulk. After adding the
baryonic matter on the screen, we assume that both of the dark matter and dark
energy can be described by the Brown-York stress-energy tensor. From the
Hamiltonian constraint equation in the flat bulk, we find an interesting
relation between the dark matter and baryonic matter's energy density
parameters, by comparing with the Lambda cold dark matter parameterization. We
further compare this holographic embedding of emergent dark matter with
traditional braneworld scenario and present an alternative interpretation as
the holographic universe. It can be reduced to our toy constraint in the late
time universe, with the new parameterization of the Friedmann equation. We also
comment on the possible connection with Verlinde's emergent gravity, where the
dark matter is treated as the elastic response of the baryonic matter on the de
Sitter spacetime background. We show that from the holographic de Sitter model
with elasticity, the Tully-Fisher relation and the dark matter distribution in
the galaxy scale can be derived.Comment: 28 pages, 2 figures; Matches published version and we thank the
referees for many insightful comments; v3: typos in the Friedmann equations
are fixe
Towards Searching for Entangled Photons in the CMB Sky
We explore the possibility of detecting entangled photon pairs from cosmic
microwave background or other cosmological sources coming from two patches of
the sky. The measurements use two detectors with different photon polarizer
directions. When two photon sources are separated by a large angle relative to
the earth, such that each detector has only one photon source in its field of
view, a null test of unentangled photons can be performed. The deviation from
this unentangled background is, in principle, the signature of photon
entanglement. To confirm whether the deviation is consistent with entangled
photons, we derive a photon polarization correlation to compare with, similar
to that in a Bell inequality measurement. However, since photon coincidence
measurement cannot be used to discriminate unentangled cosmic photons, it is
unlikely that the correlation expectation value alone can violate Bell
inequality to provide the signature for entanglement.Comment: 5 pages, 2 figure; references added, typos fixed. v3 revised version
with more discussions on detection possibilities; added references.v4
published version in PR
Emergent Dark Universe and the Swampland Criteria
We study a model of the emergent dark universe, which lives on the time-like
hypersurface in a five-dimensional bulk spacetime. The holographic fluid on the
hypersurface is assumed to play the role of the dark sector, mainly including
the dark energy and apparent dark matter. Based on the modified Friedmann
equations, we present a Markov-Chain-Monte-Carlo analysis with the
observational data, including type Ia Supernova and the direct measurement of
the Hubble constant. We obtain a good fitting result and the matter component
turns out to be small enough, which matches well with our theoretical
assumption that only the normal matter is required. After considering the
fitting parameters, an effective potential of the model with a dynamical scalar
field is reconstructed. The parameters in the swampland criteria are extracted,
and they satisfy the criteria at the present epoch but are in tension with the
criteria if the potential is extended to the future direction. The method to
reconstruct the potential is helpful to study the swampland criteria of other
models without an explicit scalar field.Comment: v2: 16 pages, 10 figures, 4 tables; References and figures are
updated. The problem in typesetting is fixed. Fitting functions of the
effective potentials in Sec 4 are improve
Dark Fluxes from Accreting Black Holes and Direct Detections
We show that accreting black hole systems could be sources for keV light dark
matter flux through several different mechanisms. We discuss two types of
systems: coronal thermal plasmas around supermassive black holes in active
galactic nuclei (AGNs), and accretion disks of stellar-mass X-ray black hole
binaries (BHBs). We explore how these black hole systems may produce keV light
dark matter fluxes and find that in order to account for the XENON1T excess,
the dark fluxes from the observed AGNs and BHBs sources have to exceed the
Eddington limit. We also extend the black hole mass region to primordial black
holes (PBHs) and discuss the possibility of contributing to keV light dark flux
via superradiance or Hawking radiation of PBHs. Besides, black holes can be
good accelerators to accrete and boost heavy dark matter particles. If
considering collisions or dark electromagnetism, those particles could then
escape and reach the benchmark speed of 0.1c at the XENON1T detector.Comment: 10 pages, 4 figure
Design of Artificial Neurons of Memristive Neuromorphic Networks Based on Biological Neural Dynamics and Structures
© 2024, IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. This is the accepted manuscript version of a conference paper which has been published in final form at https://doi.org/10.1109/TCSI.2023.3332496Memristive neuromorphic networks have great potentialand advantage in both technology and computationalprotocols for artificial intelligence. Efficient hardware design ofbiological neuron models forms the core of research problems inneuromorphic networks. However, most of the existing researchhas been based on logic or integrated circuit principles, limitedto replicating simple integrate-and-fire behaviors, while morecomplex firing characteristics have relied on the inherent propertiesof the devices themselves, without support from biologicalprinciples. This paper proposes a memristor-based neuron circuitsystem (MNCS) according to the microdynamics of neuronsand complex neural cell structures. It leverages the nonlinearityand non-volatile characteristics of memristors to simulate thebiological functions of various ion channels. It is designed basedon the Hodgkin-Huxley (HH) model circuit, and the parametersare adjusted according to each neuronal firing mechanism. BothPSpice simulations and practical experiments have demonstratedthat MNCS can replicate 24 types of repeating biological neuronalbehaviors. Furthermore, the results from the Joint Inter-spikeInterval(JISI) experiment indicate that as the background noiseincreases, MNCS exhibits pulse emission characteristics similarto those of biological neurons.Peer reviewe
BmILF and I-motif Structure Are Involved in Transcriptional Regulation of \u3cem\u3eBmPOUM2\u3c/em\u3e in \u3cem\u3eBombyx mori\u3c/em\u3e
Guanine-rich and cytosine-rich DNA can form four-stranded DNA secondary structures called G-quadruplex (G4) and i-motif, respectively. These structures widely exist in genomes and play important roles in transcription, replication, translation and protection of telomeres. In this study, G4 and i-motif structures were identified in the promoter of the transcription factor gene BmPOUM2, which regulates the expression of the wing disc cuticle protein gene (BmWCP4) during metamorphosis. Disruption of the i-motif structure by base mutation, anti-sense oligonucleotides (ASOs) or inhibitory ligands resulted in significant decrease in the activity of the BmPOUM2 promoter. A novel i-motif binding protein (BmILF) was identified by pull-down experiment. BmILF specifically bound to the i-motif and activated the transcription of BmPOUM2. The promoter activity of BmPOUM2 was enhanced when BmILF was over-expressed and decreased when BmILF was knocked-down by RNA interference. This study for the first time demonstrated that BmILF and the i-motif structure participated in the regulation of gene transcription in insect metamorphosis and provides new insights into the molecular mechanism of the secondary structures in epigenetic regulation of gene transcription
Design and Characterization of a Human Monoclonal Antibody that Modulates Mutant Connexin 26 Hemichannels Implicated in Deafness and Skin Disorders
Background: Mutations leading to changes in properties, regulation, or expression of connexin-made channels have been implicated in 28 distinct human hereditary diseases. Eight of these result from variants of connexin 26 (Cx26), a protein critically involved in cell-cell signaling in the inner ear and skin. Lack of non-toxic drugs with defined mechanisms of action poses a serious obstacle to therapeutic interventions for diseases caused by mutant connexins. In particular, molecules that specifically modulate connexin hemichannel function without affecting gap junction channels are considered of primary importance for the study of connexin hemichannel role in physiological as well as pathological conditions. Monoclonal antibodies developed in the last three decades have become the most important class of therapeutic biologicals. Recombinant methods permit rapid selection and improvement of monoclonal antibodies from libraries with large diversity.Methods: By screening a combinatorial library of human single-chain fragment variable (scFv) antibodies expressed in phage, we identified a candidate that binds an extracellular epitope of Cx26. We characterized antibody action using a variety of biochemical and biophysical assays in HeLa cells, organotypic cultures of mouse cochlea and human keratinocyte-derived cells.Results: We determined that the antibody is a remarkably efficient, non-toxic, and completely reversible inhibitor of hemichannels formed by connexin 26 and does not affect direct cell-cell communication via gap junction channels. Importantly, we also demonstrate that the antibody efficiently inhibits hyperative mutant Cx26 hemichannels implicated in autosomal dominant non-syndromic hearing impairment accompanied by keratitis and hystrix-like ichthyosis-deafness (KID/HID) syndrome. We solved the crystal structure of the antibody, identified residues that are critical for binding and used molecular dynamics to uncover its mechanism of action.Conclusions: Although further studies will be necessary to validate the effect of the antibody in vivo, the methodology described here can be extended to select antibodies against hemichannels composed by other connexin isoforms and, consequently, to target other pathologies associated with hyperactive hemichannels. Our study highlights the potential of this approach and identifies connexins as therapeutic targets addressable by screening phage display libraries expressing human randomized antibodies
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