Lightening gravity-mediated dark matter Kang, Yoo-Jin; Lee, Hyun Min
The European physical journal. C, Particles and fields,
07/2020, Letnik:
80, Številka:
7
Journal Article
Recenzirano
Odprti dostop
We revisit the scenario of a massive spin-2 particle as the mediator for communicating between dark matter of arbitrary spin and the Standard Model. Taking the general couplings of the spin-2 ...particle in the effective theory, we discuss the thermal production mechanisms for dark matter with various channels and the dark matter self-scattering. For WIMP and light dark matter cases, we impose the relic density condition and various experimental constraints from direct and indirect detections, precision measurements as well as collider experiments. We show that it is important to include the annihilation of dark matter into a pair of spin-2 particles in both allowed and forbidden regimes, thus opening up the consistent parameter space for dark matter. The benchmark models of the spin-2 mediator are presented in the context of the warped extra dimension and compared to the simplified models.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The risk of developing tuberculosis (TB) in allogeneic hematopoietic stem cell transplantation (HSCT) recipients is expected to be relatively high in an intermediate TB burden country. This ...single-center retrospective study was conducted to investigate risk factors and the incidence of TB after allogeneic HSCT.
From January 2004 to March 2011, 845 adult patients were enrolled. Starting April 2009, patients were given isoniazid (INH) prophylaxis based on interferon-γ release assay results. The incidence of TB was analyzed before and after April 2009, and compared it with that of the general population in Korea.
TB was diagnosed in 21 (2.49%) of the 845 allogeneic HSCT patients. The median time to the development of TB was 386 days after transplantation (range, 49-886). Compared with the general population, the standardized incidence ratio of TB was 9.10 (95% CI; 5.59-14.79). Extensive chronic graft-versus-host disease (GVHD) was associated with the development of TB (P = 0.003). Acute GVHD, conditioning regimen with total body irradiation and conditioning intensity were not significantly related. INH prophylaxis did not reduce the incidence of TB (P = 0.548). Among 21 TB patients, one patient had INH prophylaxis.
Allogeneic HSCT recipients especially those who suffer from extensive chronic GVHD are at a high risk of developing TB. INH prophylaxis did not statistically change the incidence of TB, however, further well-designed prospective studies are needed.
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Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
All‐solid‐state batteries (ASSBs) comprising solidified cathodes, electrolytes, and Li–metal anodes have attracted notable attention as promising future batteries for electric vehicles owing to their ...exceptional stability and expectation of achieving high energy density. However, its permanent operation has been hindered by Li dendrite growth, chemo–mechanical degradation, and interfacial instability, leading to Li exhaustion, increased resistance, and internal short‐circuiting. Herein, for the first time, the authors report the effects of a lithium nitride (Li3N) sacrificial cathode on the cycling performance of ASSBs combined with a Li‐free In layer. Through in situ evolved gas and internal pressure change analyses of the cells, it is found that, as with the liquid electrolyte cell, the decomposed Li3N compensates for active Li consumed by side reactions in the cell. Moreover, it is demonstrated that the improved interparticle contact by volume expansion of In through additionally supplied Li as well as the interfacial stability at the anode side by the dendrite‐free In layer, are strongly responsible for the improved cyclability of the ASSBs. The findings reveal the effectiveness of the Li compensation approach for the stable cycling of ASSBs based on the secured interfacial stability at the anode side.
A sulfide‐based all‐solid‐state battery consisting of a lithium nitride (Li3N) sacrificial cathode and a Li‐free indium layer shows stable cycling performance owing to the combined effects of the Li3N compensating for Li loss caused by interfacial side reactions along with contributing to improved interparticle contact by additional volume expansion of In and the dendrite‐free In layer exhibiting exceptional interfacial stability.
Microvilli on T cells have been proposed to survey surfaces of antigen-presenting cells (APC) or facilitate adhesion under flow; however, whether they serve essential functions during T cell ...activation remains unclear. Here we show that antigen-specific T cells deposit membrane particles derived from microvilli onto the surface of cognate antigen-bearing APCs. Microvilli carry T cell receptors (TCR) at all stages of T cell activation and are released as large TCR-enriched, T cell microvilli particles (TMP) in a process of trogocytosis. These microvilli exclusively contain protein arrestin-domain-containing protein 1, which is directly involved in membrane budding and, in combination with vacuolar protein-sorting-associated protein 4, transforms large TMPs into smaller, exosome-sized TMPs. Notably, TMPs from CD4
T cells are enriched with LFA-2/CD2 and various cytokines involved in activating dendritic cells. Collectively, these results demonstrate that T cell microvilli constitute "immunological synaptosomes" that carry T cell messages to APCs.
Unitary inflaton as decaying dark matter Choi, Soo-Min; Kang, Yoo-Jin; Lee, Hyun Min ...
The journal of high energy physics,
05/2019, Letnik:
2019, Številka:
5
Journal Article
Recenzirano
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A
bstract
We consider the inflation model of a singlet scalar field (sigma field) with both quadratic and linear non-minimal couplings where unitarity is ensured up to the Planck scale. We assume ...that a
Z
2
symmetry for the sigma field is respected by the scalar potential in Jordan frame but it is broken explicitly by the linear non-minimal coupling due to quantum gravity. We discuss the impacts of the linear non-minimal coupling on various dynamics from inflation to low energy, such as a sizable tensor-to-scalar ratio, a novel reheating process with quartic potential dominance, and suppressed physical parameters in the low energy, etc. In particular, the linear non-minimal coupling leads to the linear couplings of the sigma field to the Standard Model through the trace of the energy-momentum tensor in Einstein frame. Thus, regarding the sigma field as a decaying dark matter, we consider the non-thermal production mechanisms for dark matter from the decays of Higgs and inflaton condensate and show the parameter space that is compatible with the correct relic density and cosmological constraints.
We propose a new mechanism for rendering dark matter self-interacting in the presence of a massive spin-2 mediator. The derived Yukawa-type potential for dark matter is independent of the spins of ...dark matter in the leading order of the momentum expansion, so are the resulting non-perturbative effects for the dark matter self-scattering. We find that both the Born cross section and relatively mild resonance effects assist to make the self-scattering cross section velocity-dependent. We discuss how to evade the current indirect bounds on dark matter annihilations and show that the model is marginally compatible with perturbative unitarity in the ghost-free realization of the massive spin-2 particle.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Lepto-quark portal dark matter Choi, Soo-Min; Kang, Yoo-Jin; Lee, Hyun Min ...
The journal of high energy physics,
10/2018, Letnik:
2018, Številka:
10
Journal Article
Recenzirano
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A
bstract
We consider the extension of the Standard Model with scalar leptoquarks as a portal to dark matter (DM), motivated by the recent anomalies in semi-leptonic
B
-meson decays. Taking singlet ...and triplet scalar leptoquarks as the best scenarios for explaining
B
-meson anomalies, we discuss the phenomenological constraints from rare meson decays, muon (
g
− 2)
μ
, and leptoquark searches at the Large Hadron Collider (LHC). Introducing leptoquark couplings to scalar dark matter, we find that the DM annihilations into a pair of leptoquarks open a wide parameter space, being compatible with XENON1T bound, and show that there is an interesting interplay between LHC leptoquark searches and distinct signatures from cascade annihilations of dark matter.
Natural killer (NK) cells are suitable targets for cancer immunotherapy owing to their potent cytotoxic activity. To maximize the therapeutic efficacy of cancer immunotherapy, adjuvants need to be ...identified. Resveratrol is a well-studied polyphenol with various potential health benefits, including antitumor effects. We previously found that resveratrol is an NK cell booster, suggesting that it can serve as an adjuvant for cancer immunotherapy. However, the molecular mechanism underlying the activation of NK cells by resveratrol remains unclear. The present study aimed to determine this mechanism. To this end, we investigated relevant pathways in NK cells using Western blot, real-time polymerase chain reaction, pathway inhibitor, protein/DNA array, and cytotoxicity analyses. We confirmed the synergistic effects of resveratrol and interleukin (IL)-2 on enhancing the cytolytic activity of NK cells. Resveratrol activated Akt by regulating Mammalian Target of Rapamycin (mTOR) Complex 2 (mTORC2) via phosphatase and tensin homolog (PTEN) and ribosomal protein S6 kinase beta-1 (S6K1). Moreover, resveratrol-mediated NK cell activation was more dependent on the mTOR pathway than the Akt pathway. Importantly, resveratrol increased the expression of c-Myb, a downstream transcription factor of Akt and mTORC2. Moreover, c-Myb was essential for resveratrol-induced NK cell activation in combination with IL-2. Our results demonstrate that resveratrol activates NK cells through Akt- and mTORC2-mediated c-Myb upregulation.
The influence of hydrogen on the mechanical behavior of the CoCrFeMnNi high-entropy alloy (HEA) was examined through tensile and nanoindentation experiments on specimens hydrogenated via gaseous and ...electrochemical methods. Results show that the HEA's resistance to gaseous hydrogen embrittlement is better than that of two representative austenitic stainless steels, in spite of the fact that it absorbs a larger amount of hydrogen than the two steels. Reasons for this were discussed in terms of hydrogen-enhanced localized plasticity mechanism and the critical amount of hydrogen required for it. These were further substantiated by additional experiments on electrochemically charged specimens.
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A
bstract
We consider models where a massive spin-two resonance acts as the mediator between Dark Matter (DM) and the SM particles through the energy-momentum tensor. We examine the effective theory ...for fermion, vector and scalar DM generated in these models and find novel types of DM-SM interaction never considered before. We identify the effective interactions between DM and the SM quarks when the mediator is integrated out, and match them to the gravitational form factors relevant for spin-independent DM-nucleon scattering. We also discuss the interplay between DM relic density conditions, direct detection bounds and collider searches for the spin-two mediator.
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