Stokes Phenomena and Non-perturbative Completion in the Multi-cut Two-matrix Models

The Stokes multipliers in the matrix models are invariants in the string-theory moduli space and related to the D-instanton chemical potentials. They not only represent non-perturbative information but also play an important role in connecting various perturbative string theories in the moduli space. They are a key concept to the non-perturbative completion of string theory and also expected to imply some remnant of strong coupling dynamics in M theory. In this paper, we investigate the non-perturbative completion problem consisting of two constraints on the Stokes multipliers. As the first constraint, Stokes phenomena which realize the multi-cut geometry are studied in the Z_k symmetric critical points of the multi-cut two-matrix models. Sequence of solutions to the constraints are obtained in general k-cut critical points. A discrete set of solutions and a continuum set of solutions are explicitly shown, and they can be classified by several constrained configurations of the Young diagram. As the second constraint, we discuss non-perturbative stability of backgrounds in terms of the Riemann-Hilbert problem. In particular, our procedure in the 2-cut (1,2) case (pure-supergravity case) completely fixes the D-instanton chemical potentials and results in the Hastings-McLeod solution to the Painlev\'e II equation. It is also stressed that the Riemann-Hilbert approach realizes an off-shell background independent formulation of non-critical string theory.Comment: 71 pages, v3: organization of Sec. 3, Sec. 4, App. C and App. D improved, final version to be published in Nucl. Phys.

Duality Constraints on String Theory: Instantons and spectral networks

We study an implication of $p-q$ duality (spectral duality or T-duality) on non-perturbative completion of $(p,q)$ minimal string theory. According to the Eynard-Orantin topological recursion, spectral $p-q$ duality was already checked for all-order perturbative analysis including instanton/soliton amplitudes. Non-perturbative realization of this duality, on the other hand, causes a new fundamental issue. In fact, we find that not all the non-perturbative completions are consistent with non-perturbative $p-q$ duality; Non-perturbative duality rather provides a constraint on non-perturbative contour ambiguity (equivalently, of D-instanton fugacity) in matrix models. In particular, it prohibits some of meta-stability caused by ghost D-instantons, since there is no non-perturbative realization on the dual side in the matrix-model description. Our result is the first quantitative observation that a missing piece of our understanding in non-perturbative string theory is provided by the principle of non-perturbative string duality. To this end, we study Stokes phenomena of $(p,q)$ minimal strings with spectral networks and improve the Deift-Zhou's method to describe meta-stable vacua. By analyzing the instanton profile on spectral networks, we argue the duality constraints on string theory.Comment: v1: 84 pages, 43 figures; v2: 86 pages, 43 figures, presentations are improved, references added; v3: 126 pages, 69 figures: a solution of local RHP, physics of resolvents, commutativity of integrals are newly added; organization is changed and explanations are expanded to improve representation with addition of review, proofs and calculations; some definitions are changed; references adde

Wronskians, dualities and FZZT-Cardy branes

The resolvent operator plays a central role in matrix models. For instance, with utilizing the loop equation, all of the perturbative amplitudes including correlators, the free-energy and those of instanton corrections can be obtained from the spectral curve of the resolvent operator. However, at the level of non-perturbative completion, the resolvent operator is generally not sufficient to recover all the information from the loop equations. Therefore it is necessary to find a sufficient set of operators which provide the missing non-perturbative information. In this paper, we study generalized Wronskians of the Baker-Akhiezer systems as a manifestation of these new degrees of freedom. In particular, we derive their isomonodromy systems and then extend several spectral dualities to these systems. In addition, we discuss how these Wronskian operators are naturally aligned on the Kac table. Since they are consistent with the Seiberg-Shih relation, we propose that these new degrees of freedom can be identified as FZZT-Cardy branes in Liouville theory. This means that FZZT-Cardy branes are the bound states of elemental FZZT branes (i.e. the twisted fermions) rather than the bound states of principal FZZT-brane (i.e. the resolvent operator).Comment: 131 pages, 4 figure

Relationships between stress, coping and depressive symptoms among overseas university preparatory Chinese students: a cross-sectional study

<p>Abstract</p> <p>Background</p> <p>Mental health problems in young people are an important public health issue. Students leaving their hometown and family at a young age to pursue better educational opportunities overseas are confronted with life adjustment stress, which in turn affects their mental health and academic performance. This study aimed to examine the relationships among stress, coping strategies, and depressive symptoms using the stress coping framework in overseas Chinese university preparatory students in Taiwan.</p> <p>Methods</p> <p>A cross-sectional study was conducted at an overseas Chinese university preparatory institute in Taiwan. Of enrolled overseas Chinese university preparatory students at 2009, 756 completed a structured questionnaire measuring stress, strategies for coping with it, and the Center for Epidemiologic Studies Depression Scale.</p> <p>Results</p> <p>High levels of stress significantly predicted the adoption of active, problem-focused coping strategies (<it>R</it>²= 0.13<!-- entity --><it>, p </it>< .01) and passive, emotion-focused coping strategies (<it>R</it>²= 0.24<!-- entity --><it>, p </it>< .01). Acceptable CFI, SRMR, and RMSEA values from the structural equation modeling analysis demonstrated that the model satisfactorily fits the stress coping framework, after active coping strategies were eliminated from the model. Results from the Sobel test revealed that passive coping strategies mediated the relation between stress and depressive symptoms (<it>z </it>= 8.06, <it>p </it>< .001).</p> <p>Conclusion</p> <p>Our study results suggested that stress is associated with coping strategies and depressive symptoms and passive strategies mediate the relation between stress and depressive symptoms in overseas Chinese university preparatory students.</p

Ganoderma lucidum polysaccharides enhance CD14 endocytosis of LPS and promote TLR4 signal transduction of cytokine expression

We have previously reported that a well-characterized glycoprotein fraction containing fucose residues in an extract of Ganoderma lucidum polysaccharides (EORP) exerts certain immuno-modulation activity by stimulating the expression of inflammatory cytokines via TLR4. Continuing our studies, we have demonstrated that EORP increases the surface expression of CD14 and TLR4 within murine macrophages J774A.1 cells in vitro, and further promotes LPS binding and uptake by J774A.1 cells in a CD14-dependent fashion. Moreover, we observed the co-localization of internalized LPS with lysosome- and Golgi-apparatus markers within 5 min after J774A.1 cells stimulated with LPS. In addition, EORP pretreatment of J774A.1 cells and human blood-derived primary macrophages, followed by LPS stimulation, results in the super-induction of interleukin-1beta (IL-1) expression. Endocytosis inhibitors: such as cytochalasin D and colchicine effectively block EORP-enhanced LPS internalization by J774A.1 cells; yet they fail to decrease the LPS-induced phosphorylation of certain mitogen-activated protein kinases, and IL-1 mRNA and proIL-1 protein expression, indicating that LPS internalization by J774A.1 cells is not associated with LPS-dependent activation. Our current results could provide a potential EORP-associated protection mechanism for bacteria infection by enhancing IL-1 expression and the clearance of contaminated LPS by macrophages. J. Cell. Physiol. 212: 537–550, 2007. © 2007 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/56052/1/21050_ftp.pd

Analytic Study for the String Theory Landscapes via Matrix Models

We demonstrate a first-principle analysis of the string theory landscapes in the framework of non-critical string/matrix models. In particular, we discuss non-perturbative instability, decay rate and the true vacuum of perturbative string theories. As a simple example, we argue that the perturbative string vacuum of pure gravity is stable; but that of Yang-Lee edge singularity is inescapably a false vacuum. Surprisingly, most of perturbative minimal string vacua are unstable, and their true vacuum mostly does not suffer from non-perturbative ambiguity. Importantly, we observe that the instability of these tachyon-less closed string theories is caused by ghost D-instantons (or ghost ZZ-branes), the existence of which is determined only by non-perturbative completion of string theory.Comment: v1: 5 pages, 2 figures; v2: references and footnote added; v3: 7 pages, 4 figures, organization changed, explanations expanded, references added, reconstruction program from arbitrary spectral curves shown explicitl

PROGRESS IN LABORATORY RESEARCH FOR FUNDAMENTAL PHYSICS SPACE MISSIONS USING OPTICAL DEVICES

ABSTRACT In this paper, we present the progress in our laboratory studies for fundamental physics space missions using optical devices. Specifically, we report on our progress in long fibre-linked heterodyne interferometry, tunable fibre directional coupler, fibre delay-line and picometer real-time motion control