611 research outputs found
Revising inelastic dark matter direct detection by including the cosmic ray acceleration
The null signal from collider and dark matter (DM) direct detector
experiments makes the interaction between DM and visible matter too small to
reproduce the correct relic density for many thermal DM models. The remaining
parameter space indicates that two almost degenerated states in the dark
sector, the inelastic DM scenario, can co-annihilate in the early universe to
produce the correct relic density. Regarding the direct detection of the
inelastic DM scenario, the virialized DM component from the nearby halo is
nonrelativistic and not able to excite the DM ground state, even if the
relevant couplings can be considerable. Thus, a DM with a large mass splitting
can evade traditional virialized DM direct detection. In this study, we connect
the concept of cosmic-ray accelerated DM in our Milky Way and the direct
detection of inelastic scattering in underground detectors to explore spectra
that result from several interaction types of the inelastic DM. We find that
the mass splitting can still be reachable for
cosmic ray accelerated DM with mass range and sub-GeV light mediator using the latest PandaX-4T data, even though
we conservatively use the astrophysical parameter (effective length) kpc.Comment: 38 pages, 12 figures, JHEP accepted versio
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The Nuclear Chaperone Nucleophosmin Escorts an Epstein-Barr Virus Nuclear Antigen to Establish Transcriptional Cascades for Latent Infection in Human B Cells
Epstein-Barr Virus (EBV) is an oncogenic γ-herpesvirus that capably establishes both latent and lytic modes of infection in host cells and causes malignant diseases in humans. Nuclear antigen 2 (EBNA2)-mediated transcription of both cellular and viral genes is essential for the establishment and maintenance of the EBV latency program in B lymphocytes. Here, we employed a protein affinity pull-down and LC-MS/MS analysis to identify nucleophosmin (NPM1) as one of the cellular proteins bound to EBNA2. Additionally, the specific domains that are responsible for protein-protein interactions were characterized as EBNA2 residues 300 to 360 and the oligomerization domain (OD) of NPM1. As in c-MYC, dramatic NPM1 expression was induced in EBV positively infected B cells after three days of viral infection, and both EBNA2 and EBNALP were implicated in the transactivation of the NPM1 promoter. Depletion of NPM1 with the lentivirus-expressed short-hairpin RNAs (shRNAs) effectively abrogated EBNA2-dependent transcription and transformation outgrowth of lymphoblastoid cells. Notably, the ATP-bound state of NPM1 was required to induce assembly of a protein complex containing EBNA2, RBP-Jκ, and NPM1 by stabilizing the interaction of EBNA2 with RBP-Jκ. In a NPM1-knockdown cell line, we demonstrated that an EBNA2-mediated transcription defect was fully restored by the ectopic expression of NPM1. Our findings highlight the essential role of NPM1 in chaperoning EBNA2 onto the latency-associated membrane protein 1 (LMP1) promoters, which is coordinated with the subsequent activation of transcriptional cascades through RBP-Jκ during EBV infection. These data advance our understanding of EBV pathology and further imply that NPM1 can be exploited as a therapeutic target for EBV-associated diseases
The Influence of Ingestion Glucose Beverage before Graded Exercise to Exhaustion on Saliva IgA Concentration in Hypoxia and Normoxia Environment
In addition to exercise, hypoxia environment might induce higher immune stress. The present study was to investigate the ingestion of glucose before graded exercise to exhaustion in hypoxia environment on immune responses. Eight healthy college students
Epitaxial Growth of Two-dimensional Insulator Monolayer Honeycomb BeO
The emergence of two-dimensional (2D) materials launched a fascinating
frontier of flatland electronics. Most crystalline atomic layer materials are
based on layered van der Waals materials with weak interlayer bonding, which
naturally leads to thermodynamically stable monolayers. We report the synthesis
of a 2D insulator comprised of a single atomic sheet of honeycomb structure BeO
(h-BeO), although its bulk counterpart has a wurtzite structure. The h-BeO is
grown by molecular beam epitaxy (MBE) on Ag(111) thin films that are
conveniently grown on Si(111) wafers. Using scanning tunneling microscopy and
spectroscopy (STM/S), the honeycomb BeO lattice constant is determined to be
2.65 angstrom with an insulating band gap of 6 eV. Our low energy electron
diffraction (LEED) measurements indicate that the h-BeO forms a continuous
layer with good crystallinity at the millimeter scale. Moir\'e pattern analysis
shows the BeO honeycomb structure maintains long range phase coherence in
atomic registry even across Ag steps. We find that the interaction between the
h-BeO layer and the Ag(111) substrate is weak by using STS and complimentary
density functional theory calculations. We not only demonstrate the feasibility
of growing h-BeO monolayers by MBE, but also illustrate that the large-scale
growth, weak substrate interactions, and long-range crystallinity make h-BeO an
attractive candidate for future technological applications. More significantly,
the ability to create a stable single crystalline atomic sheet without a bulk
layered counterpart is an intriguing approach to tailoring novel 2D electronic
materials.Comment: 25 pages, 7 figures, submitted to ACS Nano, equal contribution by Hui
Zhang and Madisen Holbroo
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