100 research outputs found

    Exact results on ABJ theory and the refined topological string

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    We study the partition function of the ABJ theory, which is the N=6 superconformal Chern-Simons matter theory with gauge group U(N)xU(N+M) and Chern-Simons levels (k,-k). We exactly compute the ABJ partition function on a three sphere for various k, M and N via the Fermi gas approach. By using these exact data, we show that the ABJ partition function is completely determined by the refined topological string on local P^1 x P^1, including membrane instanton effects in the M-theory dual.Comment: 24+29 pages, 4 figures; v2:minor improvement

    Large N non-perturbative effects in N=4\mathcal{N}=4 superconformal Chern-Simons theories

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    We investigate the large NN instanton effects of partition functions in a class of N=4\mathcal{N}=4 circular quiver Chern-Simons theories on a three-sphere. Our analysis is based on the supersymmetry localization and the Fermi-gas formalism. The resulting matrix model can be regarded as a two-parameter deformation of the ABJM matrix model, and has richer non-perturbative structures. Based on a systematic semi-classical analysis, we find analytic expressions of membrane instanton corrections. We also exactly compute the partition function for various cases and find some exact forms of worldsheet instanton corrections, which appear as quantum mechanical non-perturbative corrections in the Fermi-gas system.Comment: 35+18 pages, 3 figures; v2: minor correction

    ABJM Wilson Loops in Arbitrary Representations

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    We study vacuum expectation values (VEVs) of circular half BPS Wilson loops in arbitrary representations in ABJM theory. We find that those in hook representations are reduced to elementary integrations thanks to the Fermi gas formalism, which are accessible from the numerical studies similar to the partition function in the previous studies. For non-hook representations, we show that the VEVs in the grand canonical formalism can be exactly expressed as determinants of those in the hook representations. Using these facts, we can study the instanton effects of the VEVs in various representations. Our results are consistent with the worldsheet instanton effects studied from the topological string and a prescription to include the membrane instanton effects by shifting the chemical potential, which has been successful for the partition function.Comment: 30 pages, 1 figure; v2: references added; v3: minor correction

    Multiscale expansion of the lattice potential KdV equation on functions of infinite slow-varyness order

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    We present a discrete multiscale expansion of the lattice potential Korteweg-de Vries (lpKdV) equation on functions of infinite order of slow-varyness. To do so we introduce a formal expansion of the shift operator on many lattices holding at all orders. The lowest secularity condition from the expansion of the lpKdV equation gives a nonlinear lattice equation, depending on shifts of all orders, of the form of the nonlinear Schr\"odinger (NLS) equationComment: 9 pages, submitted to Journ. Phys.

    Basal ganglia-cortical connectivity underlies self-regulation of brain oscillations in humans

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    Brain-Computer Interface操作の得手不得手に関わる脳回路を発見 --操作を「考える」か「感じる」か、個人差に合わせた技術開発へ期待--. 京都大学プレスリリース. 2022-08-10.Brain-computer interfaces provide an artificial link by which the brain can directly interact with the environment. To achieve fine brain-computer interface control, participants must modulate the patterns of the cortical oscillations generated from the motor and somatosensory cortices. However, it remains unclear how humans regulate cortical oscillations, the controllability of which substantially varies across individuals. Here, we performed simultaneous electroencephalography (to assess brain-computer interface control) and functional magnetic resonance imaging (to measure brain activity) in healthy participants. Self-regulation of cortical oscillations induced activity in the basal ganglia-cortical network and the neurofeedback control network. Successful self-regulation correlated with striatal activity in the basal ganglia-cortical network, through which patterns of cortical oscillations were likely modulated. Moreover, basal ganglia-cortical network and neurofeedback control network connectivity correlated with strong and weak self-regulation, respectively. The findings indicate that the basal ganglia-cortical network is important for self-regulation, the understanding of which should help advance brain-computer interface technology

    A calmodulin inhibitor, W-7 influences the effect of cyclic adenosine 3', 5'-monophosphate signaling on ligninolytic enzyme gene expression in Phanerochaete chrysosporium

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    The capacity of white-rot fungi to degrade wood lignin may be highly applicable to the development of novel bioreactor systems, but the mechanisms underlying this function are not yet fully understood. Lignin peroxidase (LiP) and manganese peroxidase (MnP), which are thought to be very important for the ligninolytic property, demonstrated increased activity in Phanerochaete chrysosporium RP-78 (FGSC #9002, ATCC MYA-4764™) cultures following exposure to 5 mM cyclic adenosine 3', 5'-monophosphate (cAMP) and 500 μM 3'-isobutyl-1-methylxanthine (IBMX), a phosphodiesterase inhibitor. Real-time reverse transcription polymerase chain reaction (RT-PCR) analysis revealed that transcription of most LiP and MnP isozyme genes was statistically significantly upregulated in the presence of the cAMP and IBMX compared to the untreated condition. However, 100 μM calmodulin (CaM) inhibitor N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7), which had insignificant effects on fungal growth and intracellular cAMP concentration, not only offset the increased activity and transcription induced by the drugs, but also decreased them to below basal levels. Like the isozyme genes, transcription of the CaM gene (cam) was also upregulated by cAMP and IBMX. These results suggest that cAMP signaling functions to increase the transcription of LiP and MnP through the induction of cam transcription

    Expression of chondroitin-glucuronate C5-epimerase and cellular immune responses in patients with hepatocellular carcinoma

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    Background & Aims: Chondroitin-glucuronate C5-epimerase is an enzyme that converts D-glucuronic acid to L-iduronic acid residues in dermatan sulphate biosynthesis. It is also identified to be a tumour-associated antigen recognized by cytotoxic T cells (CTLs) and its enhanced expression in many cancers has been reported. In the present study, we investigated the usefulness of this molecule as an immunotherapeutic target in hepatocellular carcinoma (HCC). Methods: The expression of chondroitin-glucuronate C5-epimerase in hepatoma cell lines and HCC tissues was confirmed by immunofluorescence and immunohistochemical analysis. CTL responses were investigated by several immunological techniques using peripheral blood mononuclear cells (PBMCs) or tumour-infiltrating lymphocytes. To determine the safety of immunotherapy using chondroitin-glucuronate C5-epimerase-derived peptide, 12 patients with HCC were administered s.c. vaccinations of the peptides and analysed. Results: Chondroitin-glucuronate C5-epimerase was expressed in HCC cell lines and human tissues including alpha-foetoprotein (AFP)-negative individuals. Chondroitin-glucuronate C5-epimerase-specific CTLs could be generated by stimulating PBMCs of HCC patients with peptides and they showed cytotoxicity against HCC cells expressing the protein. The frequency of CTL precursors investigated by enzyme-linked immunospot (ELISPOT) assay was 0-34 cells/3 × 10 5 PBMCs and the infiltration of interferon-gamma-producing CTLs into the tumour site was confirmed. In the vaccination study, no severe adverse events were observed and the peptide-specific CTLs were induced in 4 of 12 patients tested. Conclusions: Chondroitin-glucuronate C5-epimerase is a potential candidate for tumour antigen with immunogenicity and the peptides derived from this antigen could be useful in HCC immunotherapy. © 2012 John Wiley & Sons A/S

    ABJ theory in the higher spin limit

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    This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are creditedArticle funded by SCOAP3 .Article funded by SCOAP3 .The work of SH was supported in part by the National Research Foundation of South Africa and DSTNRF Centre of Excellence in Mathematical and Statistical Sciences (CoE-MaSS). Opinions expressed and conclusions arrived at are those of the author and are not necessarily to be attributed to the NRF or the CoE-MaSS. The work of KO was supported in part by JSPS Grant-in-Aid for Young Scientists (B) 23740178. MS is grateful to the Weizmann Institute for the stimulating environment at the “Black Holes and Quantum Information” workshop. The work of MS was supported in part by Grant-in-Aid for Young Scientists (B) 24740159 from the Japan Society for the Promotion of Science (JSPS)

    Association between self-reported walking speed and calcaneal stiffness index in postmenopausal Japanese women

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    Background: Osteoporosis and related fractures, a worldwide public health issue of growing concern, is characterized by compromised bone strength and an increased risk of fracture. Here we show an association between self-reported walking speed and bone mass among community-dwelling postmenopausal Japanese women aged 50 years and older. Design; cross-sectional study: Setting and Participants; The survey population included 1008 postmenopausal women 50?92 years of age residing in rural communities. Methods: Self-reported walking speed was ascertained by asking the participants: “Is your walking speed faster than others of the same age and sex?” to which participants responded “yes (faster)” or “no (moderate/slower).” Calcaneal stiffness index was measured. Results: Women with a faster self-reported walking speed were younger and had a lower BMI, higher stiffness index, and higher grip strength than women with a slower walking speed. Multiple linear regression analysis adjusted for age, BMI, grip strength, comorbidity, current smoking, and alcohol drinking status showed a significant association between faster self-reported walking speed and higher calcaneal stiffness index (p < 0.001). Conclusions: Our findings suggest that questionnaires of walking speed may be useful for predicting bone mass and that a fast self-reported walking may benefit bone health in postmenopausal women
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