Solitons and giants in matrix models

We present a method for solving BPS equations obtained in the collective-field approach to matrix models. The method enables us to find BPS solutions and quantum excitations around these solutions in the one-matrix model, and in general for the Calogero model. These semiclassical solutions correspond to giant gravitons described by matrix models obtained in the framework of AdS/CFT correspondence. The two-field model, associated with two types of giant gravitons, is investigated. In this duality-based matrix model we find the finite form of the $n$-soliton solution. The singular limit of this solution is examined and a realization of open-closed string duality is proposed.Comment: 17 pages, JHEP cls; v2: final version to appear in JHEP, 2 references added, physical motivation and interpretation clarifie

Multi-vortex solution in the Sutherland model

We consider the large-$N$ Sutherland model in the Hamiltonian collective-field approach based on the $1/N$ expansion. The Bogomol'nyi limit appears and the corresponding solutions are given by static-soliton configurations. They exist only for \l<1, i.e. for the negative coupling constant of the Sutherland interaction. We determine their creation energies and show that they are unaffected by higher-order corrections. For \l=1, the Sutherland model reduces to the free one-plaquette Kogut-Susskind model.Comment: Latex, using ioplppt.sty, 11 page

Waves and Solitons in the Continuum Limit of the Calogero-Sutherland Model

We examine a collection of particles interacting with inverse-square two-body potentials in the thermodynamic limit. We find explicit large-amplitude density waves and soliton solutions for the motion of the system. Waves can be constructed as coherent states of either solitons or phonons. Therefore, either solitons or phonons can be considered as the fundamental excitations. The generic wave is shown to correspond to a two-band state in the quantum description of the system, while the limiting cases of solitons and phonons correspond to particle and hole excitations.Comment: Version to appear in Physical Rerview Letters; contains some new results and explanation

Density Correlation Functions in Calogero Sutherland Models

Using arguments from two dimensional Yang-Mills theory and the collective coordinate formulation of the Calogero-Sutherland model, we conjecture the dynamical density correlation function for coupling $l$ and $1/l$, where $l$ is an integer. We present overwhelming evidence that the conjecture is indeed correct.Comment: 12 pages phyzzx, CERN-TH/94.7243 One reference change

New theory for. Mode I crack-tip dislocation emission

A material is intrinsically ductile under Mode I loading when the critical stress intensity K-Ie for dislocation emission is lower than the critical stress intensity K-Ic for cleavage. K-Ie is usually evaluated using the approximate Rice theory, which predicts a dependence on the elastic constants and the unstable stacking fault energy gamma(usf) for slip along the plane of dislocation emission. Here, atomistic simulations across a wide range of fcc metals show that K-Ie is systematically larger (10-30%) than predicted. However, the critical (crack tip) shear displacement is up to 40% smaller than predicted. The discrepancy arises because Mode I emission is accompanied by the formation of a surface step that is not considered in the Rice theory. A new theory for Mode I emission is presented based on the ideas that (i) the stress resisting step formation at the crack tip creates lattice trapping against dislocation emission such that (ii) emission is due to a mechanical instability at the crack tip. The new theory is formulated using a Peierls-type model, naturally includes the energy to form the step, and reduces to the Rice theory (no trapping) when the step energy is small. The new theory predicts a higher K-Ie at a smaller critical shear displacement, rationalizing deviations of simulations from the Rice theory. Specific predictions of K-Ie for the simulated materials, usually requiring use of the measured critical crack tip shear displacement due to complex material non-linearity, show very good agreement with simulations. An analytic model involving only gamma(usf), the surface energy gamma(s), and anisotropic elastic constants is shown to be quite accurate, serves as a replacement for the analytical Rice theory, and is used to understand differences between Rice theory and simulation in recent literature. The new theory highlights the role of surface steps created by dislocation emission in Mode I, which has implications not only for intrinsic ductility but also for crack tip twinning and fracture due to chemical interactions at the crack tip. (C) 2017 Elsevier Ltd. All rights reserved

Comment on ``Low-dimensional Bose liquids: beyond the Gross-Pitaevskii approximation''

This is a comment on the work of Kolomeisky et al., Phys. Rev. Lett. 85, 1146 (2000). We point out that they are using the wrong form of the energy functional for one-dimensional fermions. We point out two possible forms of the energy functional, both of which can be derived from first principles but using different methods. One is obtained from the collective field theory method, while the other is derived from the extended Thomas-Fermi method. These two forms of the energy functional do not support the soliton solutions which are obtained by Kolomeisky et al.Comment: Revtex, 2 page

Psychophysical stress disturbs expression of mitochondrial biogenesis markers in hypothalamus and adenohypophysis

Summary. Although psychophysical stress is widespread in human society and a major contributor to a range of pathological conditions, it is not known if this form of stress regulates mitochondrial biogenesis in the hypothalamus or adenohypophysis, the main organs involved in compensatory specifc response of the organism to stress (so called “fght or flight” response). Accordingly, this study was designed to evaluate the effects of acute and repeated psychophysical stress on a profle of mitochondrial biogenesis markers in the hypothalamus and adenohypophysis. Rats were either lef undisturbed (freely moving, control group) or exposed to psychophysical stress by immobilization (IMO) for 2 h (acute, 1xIMO) or 2 h daily for 2 (repeated, 2xIMO) or 10 consecutive days (repeated, 10xIMO). Result suggest that all types of immobilization stress signifcantly increase expression of hypothalamic NRF1 (nuclear respiratory factor 1; acts on the genes for subunits of the OXPHOS encoded by the nuclear genome) as well as its downstream target TFAM (mitochondrial transcription factor A), the essential ubiquitous factors for mtDNA replication and expression. In the same samples, TFB1M (markedly enhance mtDNA transcription) significantly decreased, while the level of COX4 (mitochondrial complex IV cytochrome C oxidase) protein was reduced only in hypothalamuses isolated from repeatedly stressed rats. Independently of the type of stress, the level of PGC1 protein, the master regulator of mitochondrial biogenesis involved in transcriptional control of all processes related to mitochondrial homeostasis and integrator of environmental signals, remained unchanged. In adenohypophyses of the same animals, 10xIMO signifcantly increased expression of adenohypophyseal PGC1 as well as its downstream target TFB1M, while NRF1 and TFAM remained unchanged. Similarly to hypothalamuses, the level of COX4 protein was reduced in adenohypophyses isolated from repeatedly stressed rats. Our results provide new molecular insights into the relationship between stress and hypothalamo-adenohypophyseal axis, as well as mitochondrial biology

A platform in the use of medicines to treat chronic hepatitis C (PLATINUM C) protocol for a prospective treatment registry of real world o

Background Safe, highly curative, short course, direct acting antiviral (DAA) therapies are now available to treat chronic hepatitis C. DAA therapy is freely available to all adults chronically infected with the hepatitis C virus (HCV) in Australia. If left untreated, hepatitis C may lead to progressive hepatic fibrosis, cirrhosis and hepatocellular carcinoma. Australia is committed to eliminating hepatitis as a public health threat by 2030 set by the World Health Organization. However, since the introduction of funded DAA treatment, uptake has been suboptimal. Australia needs improved strategies for testing, treatment uptake and treatment completion to address the persisting hepatitis C public health problem. PLATINUM C is a HCV treatment registry and research platform for assessing the comparative effectiveness of alternative interventions for achieving virological cure. Methods PLATINUM C will prospectively enrol people with active HCV infection confirmed by recent detection of HCV ribonucleic acid (RNA) in blood. Those enrolled will agree to allow standardised collection of demographic, lifestyle, treatment, virological outcome and other relevant clinical data to better inform the future management of HCV infection. The primary outcome is virological cure evidenced by sustained virological response (SVR), which is defined as a negative HCV PCR result 6 to 18 months after initial prescription of DAA therapy and no less than 12 weeks after the completion of treatment. Study participants will be invited to opt-in to medication adherence monitoring and quality of life assessments using validated self-reported instruments (EQ-5D-5L). Discussion PLATINUM C is a treatment registry and platform for nesting pragmatic trials. Data collected will inform the design, development and implementation of pragmatic trials. The digital infrastructure, study procedures and governing systems established by the registry will allow PLATINUM C to support a wider research platform in the management of hepatitis C in primary care. Trial registration The trial is registered with the Australia and New Zealand Clinical Trials Register (ACTRN12619000023156). Date of registration: 10/01/2019

Particle Production in Matrix Cosmology

We consider cosmological particle production in 1+1 dimensional string theory. The process is described most efficiently in terms of anomalies, but we also discuss the explicit mode expansions. In matrix cosmology the usual vacuum ambiguity of quantum fields in time-dependent backgrounds is resolved by the underlying matrix model. This leads to a finite energy density for the "in" state which cancels the effect of anomalous particle production.Comment: 24 pages, 1 figure; v2: references added, minor change