Dynamical Influence of a Central Massive Object on Double-Barred Galaxies: Self-Destruction Mechanism of Secondary Bars

Double-barred galaxies exhibit sub-kpc secondary stellar bars that are crucial for channeling gases towards a central massive object (CMO) such as a supermassive black hole or a nuclear star cluster. Recent $N$-body simulations have uncovered a novel galaxy evolution scenario wherein the mass of the CMO increases owing to the secondary bar, resulting in the eventual destruction of the latter. Consequently, the CMO mass growth halts, thus suggesting a maximum CMO mass of $\approx 10^{-3}$ of the stellar mass of the galaxy. This study focused on backbone orbit families, particularly double-frequency orbits, within double-barred galaxies. Consequently, the dynamic influence of a CMO on these orbits was investigated. The results of the study revealed the emergence of a new orbital resonance within the central region of the galaxy upon the introduction of a CMO. Orbits subjected to this resonance become chaotic and fail to support the secondary bar, ultimately resulting in the destruction of the entire structure. This is partly because of the inability of the secondary bar to obtain support from the newly generated orbit families following the appearance of resonance. Through the estimation of the condition of secondary bar destruction in realistic double-bar galaxies with varying pattern speeds, the results of the study established that such destruction occurred when the CMO mass reached $\approx 10^{-3}$ of the galaxy mass. Furthermore, a physical explanation of the galaxy evolution scenario was provided, thereby elucidating the interaction between the CMO and the secondary bar. The understanding of the co-evolution of the secondary bar and the CMO, based on stellar orbital motion, is a crucial step towards future observational studies of stars within the bulge of the Milky Way.Comment: submitte

Generalized equilibria for color-gradient lattice Boltzmann model based on higher-order Hermite polynomials: A simplified implementation with central moments

We propose generalized equilibria of a three-dimensional color-gradient lattice Boltzmann model for two-component two-phase flows using higher-order Hermite polynomials. Although the resulting equilibrium distribution function, which includes a sixth-order term on the velocity, is computationally cumbersome, its equilibrium central moments (CMs) are velocity-independent and have a simplified form. Numerical experiments show that our approach, as in Wen et al. [{Phys. Rev. E \textbf{100}, 023301 (2019)}] who consider terms up to third order, improves the Galilean invariance compared to that of the conventional approach. Dynamic problems can be solved with high accuracy at a density ratio of 10; however, the accuracy is still limited to a density ratio of 1000. For lower density ratios, the generalized equilibria benefit from the CM-based multiple-relaxation-time model, especially at very high Reynolds numbers, significantly improving the numerical stability.Comment: 22 pages, 8 figure

Probabilistic tsunami hazard assessment based on the Gutenberg–Richter law in eastern Shikoku, Nankai subduction zone, Japan

Earthquake and tsunami predictions comprise huge uncertainties, thus necessitating probabilistic assessments for the design of defense facilities and urban planning. In recent years, computer development has advanced probabilistic tsunami hazard assessments (PTHAs), where hazard curves show the exceedance probability of the maximum tsunami height. However, owing to the lack of historical and geological tsunami records, this method is generally insufficient for validating the estimated hazard curves. The eastern coast of Shikoku in the Nankai subduction zone, Japan, is suitable for validation because tsunami records from historical Nankai Trough earthquakes are available. This study evaluated PTHAs by comparing the tsunami hazard curves and exceedance frequencies of historical Nankai Trough tsunamis. We considered 3480 earthquake scenarios representing the rupture patterns of past Nankai earthquakes and calculated all tsunamis. The probability of earthquake occurrence was based on the Gutenberg–Richter law. We considered uncertainty in tsunami calculations with astronomical tide variations. The estimated tsunami hazard curves are consistent with the exceedance frequencies obtained from historical tsunamis. In addition, sensitivity tests indicate the significance of the earthquake slip heterogeneity and tsunami defense facilities in PTHAs. We also extended the PTHAs to tsunami inundation maps in high resolution and proposed an effective new method for reducing the tsunami computation load

ALMA ACA detection of submillimeter emission associated with the west hot spot of the radio galaxy Pictor A

In order to investigate the far-infrared excess detected from the west hot spot of the radio galaxy Pictor A with the Herschel observatory, a submillimeter photometry is performed with the Atacama Compact Array (ACA) of the Atacama Large Millimeter/submillimeter Array at Band 8 with the reference frequency of 405 GHz. A submillimeter source is discovered at the radio peak of the hot spot. Because the 405 GHz flux density of the source, $80.7\pm3.1$ mJy, agrees with the extrapolation of the synchrotron radio spectrum, the far-infrared excess is suggested to exhibit no major contribution at the ACA band. In contrast, by subtracting the power-law spectrum tightly constrained by the radio and ACA data, the significance of the excess in the Herschel band is well confirmed. No diffuse submillimeter emission is detected within the ACA field of view, and thus, the excess is ascribed to the west hot spot itself. In comparison to the previous estimate based on the Herschel data, the relative contribution of the far-infrared excess is reduced by a factor of $\sim 1.5$. The spectrum of the excess below the far-infrared band is determined to be harder than that of the diffusive shock acceleration. This strengthens the previous interpretation that the excess originates via the magnetic turbulence in the substructures within the hot spot. The ACA data are utilized to evaluate the magnetic field strength of the excess and of diffuse radio structure associated to the hot spot.Comment: 10 pages,4 figures, 3 tables, accepted for Ap

Selective inhibition of hepatitis C virus replication by alpha-zam, a Nigella sativa seed formulation

Background: Hepatitis C virus (HCV) infection became curable because of the development of direct acting antivirals (DAAs). However, the high cost of DAAs has greatly impeded their potential impact on the treatment of HCV infection. As a result, hepatitis C will continue to cause substantial morbidity, and mortality among chronically infected individuals in low and middle income countries. Thus, urgent need exists for developing cheaper drugs available to hepatitis C patients in these countries.Materials and Methods: Alpha-zam, an indigenous herbal formulation from Nigella sativa seed, was examined for its anti-HCV activity and cytotoxicity in genotype 1b HCV replicon cells. The antiviral activity was determined by luciferase expression and viral RNA synthesis, while the cytotoxicity was assessed by viable cell number and glyceraldehyde-3-phosphate dehydrogenase RNA synthesis in the replicon cells.Results: Alpha-zam was found to be a selective inhibitor of HCV replication. The 50% effective dilution and 50% cytotoxic dilution of Alpha-zam were 761- and < 100-fold, respectively, in the subgenomic replicon cells LucNeo#2. Its selective inhibition of HCV was also confirmed by HCV RNA levels in LucNeo#2 and in the full-genome HCV replicon cells NNC#2 using real-time reverse transcriptase polymerase chain reaction. Furthermore, the anti-HCV activity of Alpha-zam was not due to the induction of interferon.Conclusion: Alpha-zam selectively inhibits HCV replication and therefore has potential for a novel antiviral agent against HCV infection.Keywords: Alpha-zam, chronic hepatitis, hepatitis C virus, antiviral assay, Nigella sativ

Phase I clinical trial of the vaccination for the patients with metastatic melanoma using gp100-derived epitope peptide restricted to HLA-A*2402

<p>Abstract</p> <p>Background</p> <p>The tumor associated antigen (TAA) gp100 was one of the first identified and has been used in clinical trials to treat melanoma patients. However, the gp100 epitope peptide restricted to HLA-A*2402 has not been extensively examined clinically due to the ethnic variations. Since it is the most common HLA Class I allele in the Japanese population, we performed a phase I clinical trial of cancer vaccination using the HLA-A*2402 gp100 peptide to treat patients with metastatic melanoma.</p> <p>Methods</p> <p>The phase I clinical protocol to test a HLA-A*2402 gp100 peptide-based cancer vaccine was designed to evaluate safety as the primary endpoint and was approved by The University of Tokyo Institutional Review Board. Information related to the immunologic and antitumor responses were also collected as secondary endpoints. Patients that were HLA-A*2402 positive with stage IV melanoma were enrolled according to the criteria set by the protocol and immunized with a vaccine consisting of epitope peptide (VYFFLPDHL, gp100-in4) emulsified with incomplete Freund's adjuvant (IFA) for the total of 4 times with two week intervals. Prior to each vaccination, peripheral blood mononuclear cells (PBMCs) were separated from the blood and stored at -80°C. The stored PBMCs were thawed and examined for the frequency of the peptide specific T lymphocytes by IFN-γ- ELISPOT and MHC-Dextramer assays.</p> <p>Results</p> <p>No related adverse events greater than grade I were observed in the six patients enrolled in this study. No clinical responses were observed in the enrolled patients although vitiligo was observed after the vaccination in two patients. Promotion of peptide specific immune responses was observed in four patients with ELISPOT assay. Furthermore, a significant increase of CD8⁺gp100-in4⁺CTLs was observed in all patients using the MHC-Dextramer assay. Cytotoxic T lymphocytes (CTLs) clones specific to gp100-in4 were successfully established from the PBMC of some patients and these CTL clones were capable of lysing the melanoma cell line, 888 mel, which endogenously expresses HLA-restricted gp100-in4.</p> <p>Conclusion</p> <p>Our results suggest this HLA-restricted gp100-in4 peptide vaccination protocol was well-tolerated and can induce antigen-specific T-cell responses in multiple patients. Although no objective anti-tumor effects were observed, the effectiveness of this approach can be enhanced with the appropriate modifications.</p