Cluster X-ray line at 3.5 keV3.5\,{\rm keV} from axion-like dark matter

The recently reported X-ray line signal at $E_\gamma \simeq 3.5\, {\rm keV}$ from a stacked spectrum of various galaxy clusters and the Andromeda galaxy may be originating from a decaying dark matter particle of the mass $2 E_\gamma$. A light axion-like scalar is suggested as a natural candidate for dark matter and its production mechanisms are closely examined. We show that the right amount of axion relic density with the preferred parameters, $m_a \simeq 7 \,{\rm keV}$ and $f_a \simeq 4\times 10^{14}\, {\rm GeV}$, can be naturally obtainable from the decay of inflaton. If the axions were produced from the saxion decay, it could not have constituted the total relic density due to the bound from structure formation. Nonetheless, the saxion decay is an interesting possibility, because the $3.5\, {\rm keV}$ line and dark radiation can be addressed simultaneously, being consistent with the Planck data. Small misalignment angles of the axion, ranging between $\theta_a\sim 10^{-4} -10^{-1}$ depending on the reheating temperature, can also be the source of axion production. The model with axion misalignment can satisfy the constraints for structure formation and iso-curvature perturbation.Comment: 14 pages, significant changes in the form, matched to the journal versio

Genomic understanding of clonal variation in recombinant CHO cells

In the current manufacturing platform for large-scale production of therapeutic proteins, recombinant Chinese hamster ovary (rCHO) cell line generation is probably the most time-consuming step. The high degree of phenotypic heterogeneity in the absolute transgene expression level and variable responses to culture conditions among the selected clones, which has been referred to as “clonal variation”, makes the cell line generation process laborious and time-consuming. Upon transfection, a transgene is randomly integrated into the chromosomes of the host cells, and the integration site of the transgene is believed to be responsible for this clonal variation. However, the lack of understanding the molecular basis involved in clonal variation has hindered rapid cell line generation with a predicted culture performance. With the availability of CHO genome sequences and targeted genome sequencing/editing technologies, we investigated “clonal variation” with an emphasis on the transgene integration sites and configuration of the integrated transgenes. rCHO cell clones expressing GFP, which were constructed by random integration of the GFP expression vector into CHOK1 host cells, revealed a remarkable variability in GFP expression at 37°C. Furthermore, they showed different responses to culture temperature shifts from 37°C to 33°C confirming the existence of clonal variation. Application of targeted sequencing by the proximity ligation to the transgenes enabled the mapping of the integrated transgenes, and thereby the genomic integration sites of the transgene in the representative rCHO cell clones showing different responses to hypothermia were identified. To determine whether the different responses of the rCHO clones to hypothermia were due to the different integration sites of the transgenes, rCHO cell clones expressing GFP were also constructed by CRISPR/Cas9-mediated targeted integration of an intact transgene into CHOK1 host cells at the integration sites that were identified in the rCHO cells exhibiting different responses to hypothermia. Surprisingly, the rCHO clones constructed with targeted integration, regardless of the integration site of the gene, had similar expression patterns in terms of the absolute expression level and responses to hypothermia. They all exhibited enhanced GFP expression with hypothermia. Evidence of several rearrangements in the integrated transgene was detected in the rCHO clones constructed with random integration, which may interrupt the normal function of regulatory elements, particularly promoters. Promoter replacement and dissection results support the crucial role of promoter elements in the differential transgene expression patterns at the identical genomic site. Taken together, we demonstrate the complex nature of “clonal variation” in rCHO cells which encompasses the concept of vector elements and their rearrangement upon random integration besides just the genomic integration sites. Further characterization of the interactions between the integration sites and vector regulatory elements together with controlled integration of transgenes could lead to the tailored control of recombinant gene expression in rCHO cells while minimizing clonal variation

Diboson Excesses Demystified in Effective Field Theory Approach

We study the collider implication of a neutral resonance which decays to several diboson final states such as $W^+W^-$, $ZZ$, and $Z\gamma$ via a minimal set of effective operators. We consider both CP-even and CP-odd bosonic states with spin 0, 1, or 2. The production cross sections for the bosonic resonance states are obtained with the effective operators involving gluons (and quarks), and the branching fractions are obtained with the operators responsible for the interactions with electroweak gauge bosons. We demonstrate that each scenario allows for a broad parameter space which could accommodate the recently-reported intriguing excesses in the ATLAS diboson final states, and discuss how the CP states and spin information of the resonance can be extracted at the LHC run II.Comment: 22 pages, 6 figures, main text slightly modified with results unchange

Radicalization of Airspace Security: Prospects and Botheration of Drone Defense System Technology

The development of a comprehensive and decisive drone defense integrated control system that can provide maximum security is crucial for maintaining territorial integrity and accelerating smart aerial mobility to sustain the emerging drone transportation system (DTS) for priority-based logistics and mobile communication. This study explores recent developments in the design of robust drone defense control systems that can observe and respond not only to drone attacks inside and outside a facility but also to equipment data such as CCTV security control on the ground and security sensors in the facility at a glance. Also, it considered DDS strategies, schema, and innovative security setups in different regions. Finally, open research issues in DDs designs are discussed, and useful recommendations are provided. Effective means for drone source authentication, delivery package verification, operator authorization, and dynamic scenario-specific engagement are solicited for comprehensive DDS design for maximum security Received: 2023-03-07 Revised: 2023-04-2

Positivity Bounds on Higgs-Portal Dark Matter

We consider the positivity bounds for WIMP scalar dark matter with effective Higgs-portal couplings up to dimension-8 operators. Taking the superposed states for Standard Model Higgs and scalar dark matter, we show that the part of the parameter space for the effective couplings, otherwise unconstrained by phenomenological bounds, is ruled out by the positivity bounds on the dimension-8 derivative operators. We find that dark matter relic density, direct and indirect detection and LHC constraints are complementary to the positivity bounds in constraining the effective Higgs-portal couplings. In the effective theory obtained from massive graviton or radion, there appears a correlation between dimension-8 operators and other effective Higgs-portal couplings for which the strong constraint from direct detection can be evaded. Nailing down the parameter space mainly by relic density, direct detection and positivity bounds, we find that there are observable cosmic ray signals coming from the dark matter annihilations into a pair of Higgs bosons, $WW$ or $ZZ$.Comment: 31 pages, 6 figures, v2: one-loop corrections to the positivity bounds added, version to be published in JHE

Interfacial chemical bonding-mediated ionic resistive switching.

In this paper, we present a unique resistive switching (RS) mechanism study of Pt/TiO2/Pt cell, one of the most widely studied RS system, by focusing on the role of interfacial bonding at the active TiO2-Pt interface, as opposed to a physico-chemical change within the RS film. This study was enabled by the use of a non-conventional scanning probe-based setup. The nanoscale cell is formed by bringing a Pt/TiO2-coated atomic force microscope tip into contact with a flat substrate coated with Pt. The study reveals that electrical resistance and interfacial bonding status are highly coupled together. An oxygen-mediated chemical bonding at the active interface between TiO2 and Pt is a necessary condition for a non-polar low-resistance state, and a reset switching process disconnects the chemical bonding. Bipolar switching mode did not involve the chemical bonding. The nature of chemical bonding at the TiO2-metal interface is further studied by density functional theory calculations