Naked Singularity Explosion in Higher Dimensions

Motivated by the recent argument that in the TeV-scale gravity trans-Planckian domains of spacetime as effective naked singularities would be generated by high-energy particle (and black-hole) collisions, we investigate the quantum particle creation by naked-singularity formation in general dimensions. Background spacetime is simply modeled by the self-similar Vaidya solution, describing the spherical collapse of a null dust fluid. In a generic case the emission power is found to be proportional to the quadratic inverse of the remaining time to a Cauchy horizon, as known in four dimensions. On the other hand, the power is proportional to the quartic inverse for a critical case in which the Cauchy horizon is `degenerate'. According to these results, we argue that the backreaction of the particle creation to gravity will be important in particle collisions, in contrast to the gravitational collapse of massive stellar objects, since the bulk of energy is carried away by the quantum radiation even if a quantum gravitational effect cutoff the radiation just before the appearance of naked singularity.Comment: 19 pages, 2 figures; v2: typos fixe

Heterogeneous integration approach based on flip-chip bonding and misalignment self-correction elements for electronics-optics integration applications

This paper presents a high precision bonding approach, capable of submicron alignment accuracy, based on the thermosonic flip-chip bonding technique and misalignment self-correction elements. The precision of the bonding technique is guaranteed by using of misalignment self-correction bump (convex) and hollow (concave) elements. Metal cone bump and conductive sloped hollow bonding pad elements are created using micro-machining techniques, on a chip specimen and substrate, respectively. The chip and substrate are bonded face-to-face using of an ultrasonic-enhanced flip-chip bonder. By introducing of misalignment self-correction elements, repeatable bonding accuracies of less than 500 nm were confirmed through experimental investigation. Bond properties, including electrical and mechanical properties, are also characterized to confirm the success of the bonding approach. With the obtained results, the proposed bonding approach is capable of being use in electronics-optics heterogeneous integration applications

Extracellular calcium increases fibroblast growth factor 2 gene expression via extracellular signal-regulated kinase 1/2 and protein kinase A signaling in mouse dental papilla cells

We previously reported that elevated extracellular calcium (Ca2+) levels increase bone morphogenetic protein 2 expression in human dental pulp (hDP) cells. However, it is unknown whether extracellular Ca2+ affects the expression of other growth factors such as fibroblast growth factor 2 (FGF2). Objective: The present study aimed to examine the effect of extracellular Ca2+ on FGF2 gene expression in hDP and immortalized mouse dental papilla (mDP) cells. Materials and Methods: Cells were stimulated with 10 mM CaCl2 in the presence or absence of cell signaling inhibitors. FGF2 gene expression was assessed using real-time polymerase chain reaction. The phosphorylation status of signaling molecules was examined by Western blotting. Results: Extracellular Ca2+ increased FGF2 gene expression in mDP and hDP cells. Gene expression of the calcium-sensing receptor and G protein-coupled receptor family C group 6 member A, both of which are extracellular Ca2+ sensors, was not detected. Ca2+-mediated Fgf2 expression was reduced by pretreatment with the protein kinase A (PKA) inhibitor H-89 or extracellular signal-regulated kinase (ERK) 1/2 inhibitor PD98059 but not by pretreatment with the protein kinase C inhibitor GF-109203X or p38 inhibitor SB203580. Extracellular Ca2+ increased PKA activity and ERK1/2 phosphorylation. Ca2+-induced PKA activity decreased by pretreatment with PD98059. Conclusions: These findings indicate that elevated extracellular Ca2+ levels led to increased Fgf2 expression through ERK1/2 and PKA in mDP cells and that this mechanism may be useful for designing regenerative therapies for dentin

Optimization of Ladle Tilting Speed for Preventing Temperature Drops in the Die Casting Process

In die casting, molten metal poured into a shot sleeve is pressed into a mold by a plunger at high speed. The temperature of the metal drops significantly while it is being poured from the ladle to the shot sleeve, resulting in casting defects such as misrun flow lines. Although it is important to control the temperature at all stages of the process, a method for minimizing temperature loss has not yet been clarified to date. In this study, the cause of the temperature drop in the shot sleeve was clarified, and a method of optimizing the ladle tilting speed was proposed to prevent temperature drop. First, experiments were conducted to measure the decrease in metal temperature in the sleeve during pouring. These experiments revealed that the metal cools significantly from the moment it touches the shot sleeve. Therefore, the time from the first contact between the shot sleeve and the metal to the start of pouring was set as the objective function. A genetic algorithm was then used to derive the optimal ladle tilting speed pattern to suppress the temperature drop. This analysis confirmed that the metal was poured without flowing out or running ahead and that the immediate liquid level vibration after pouring was suppressed, thus ensuring stable pouring

IL-7 promotes long-term in vitro survival of unique long-lived memory subset generated from mucosal effector memory CD4(+) T cells in chronic colitis mice

Colitogenic memory CD4(+) T cells are important in the pathogenesis of inflammatory bowel disease (IBD). Although memory stem cells with high survival and self-renewal capacity were recently identified in both mice and humans, it is unclear whether a similar subset is present in chronic colitis mice. We sought to identify and purify a long-lived subset of colitogenic memory CD4(+) T cells, which may be targets for treatment of IBD. A long-lived subset of colitogenic memory CD4(+) T cells was purified using a long-term culture system. The characteristics of these cells were assessed. Interleukin (IL)-7 promoted the in vitro survival for >8 weeks of lamina propria (LP) CD4(+) T cells from colitic SOD mice previously injected with CD4(+)CD45RB(high) T cells. These cells were in a quiescent state and divided a maximum of 5 times in 4 weeks. LP CD4(+) T cells expressed higher levels of Bcl-2, integrin-alpha 4 beta 7, CXCR3 and CD25 after than before culture, as well as secreting high concentrations of IL-2 and low concentrations of IFN-gamma and IL-17 in response to intestinal bacterial antigens. LP CD4(+) T cells from colitic mice cultured with IL-7 for 8 weeks induced more severe colitis than LP CD4(+) T cells cultured for 4 weeks. We developed a novel culture system to purify a long-lived, highly pathogenic memory subset from activated LP CD4(+) T cells. IL-7 promoted long-term in vitro survival of this subset in a quiescent state. This subset will be a novel, effective target for the treatment of IBD

Application of precise neutron focusing mirrors for neutron reflectometry: latest results and future prospects

超精密中性子集束ミラーによる電極界面のナノ構造解析技術の実用化 --測定精度の劇的な向上に向けた大きなマイルストーン--. 京都大学プレスリリース. 2020-10-28.Neutron reflectometry (NR) is a powerful tool for providing insight into the evolution of interfacial structures, for example via operando measurements for electrode–electrolyte interfaces, with a spatial resolution of nanometres. The time resolution of NR, which ranges from seconds to minutes depending on the reflection intensity, unfortunately remains low, particularly for small samples made of state-of-the-art materials even with the latest neutron reflectometers. To overcome this problem, a large-area focusing supermirror manufactured with ultra-precision machining has been employed to enhance the neutron flux at the sample, and a gain of approximately 100% in the neutron flux was achieved. Using this mirror, a reflectivity measurement was performed on a thin cathode film on an SrTiO3 substrate in contact with an electrolyte with a small area of 15 × 15 mm. The reflectivity data obtained with the focusing mirror were consistent with those without the mirror, but the acquisition time was shortened to half that of the original, which is an important milestone for rapid measurements with a limited reciprocal space. Furthermore, a method for further upgrades that will reveal the structural evolution with a wide reciprocal space is proposed, by applying this mirror for multi-incident-angle neutron reflectometry

NCRT with S-1 plus irinotecan for LALRC

Background and purpose: Preoperative 5-fluorouracil-based chemoradiotherapy is a standard treatment for locally advanced lower rectal cancer (LALRC). We performed a phase I study to develop a new regimen combining irinotecan and S-1. Materials and methods: Patients with LALRC (T3-4, N0-2) were studied. The radiation dose was 45 Gy in 25 fractions. S-1 (80 mg/m2/day) was administered on days 1–5, 8–12, 22–26, and 29–33. Irinotecan was administered on days 1, 8, 22, and 29. The dose of irinotecan was initially 60 mg/m2 (level 1). Surgery was performed 6–10 weeks after the chemoradiotherapy. Results: Twenty patients were enrolled, of whom 18 patients were analyzed. Dose-limiting toxicity (DLT) did not occur in the first 3 patients treated with irinotecan at 80 mg/m2 (level 2), but developed in 3 of the 6 patients who received irinotecan at 90 mg/m2 (level 3). Then DLT occurred in 3 other patients at level 2. At level 2 or 3, DLT comprised neutropenia, thrombocytopenia, and diarrhea. Level 2 was designated as the maximum tolerated dose, and level 1 as a recommended dose (RD). The pathological complete response rate was 28%, and the down-staging rate was 56%. Conclusions: Our results suggested that the RD of irinotecan when combined with preoperative S-1 and pelvic radiation was 60 mg/m2