Time-dependent backgrounds of two dimensional string theory from the c=1c=1 matrix model

The aim of this paper is to use correspondence between solutions in the $c=1$ matrix model collective field theory and coupled dilaton-gravity to a massless scalar field. First, we obtain the incoming and outgoing fluctuations for the time-dependent backgrounds with the lightlike and spacelike boundaries. In the case of spacelike boundaries, we have done here for the first time. Then by using the leg-pole transformations we find corresponding tachyon field in two dimensional string theory for lightlikes and spacelikes boundary.Comment: 10 page

Collective Field Description of Matrix Cosmologies

We study the Das-Jevicki collective field description of arbitrary classical solutions in the c=1 matrix model, which are believed to describe nontrivial spacetime backgrounds in 2d string theory. Our analysis naturally includes the case of a Fermi droplet cosmology: a finite size droplet of Fermi fluid, made up of a finite number of eigenvalues. We analyze properties of the coordinates in which the metric in the collective field theory is trivial, and comment on the form of the interaction terms in these coordinates.Comment: 16 pages, 1 figure. v2: Typos corrected, JHEP styl

Condensing Momentum Modes in 2-d 0A String Theory with Flux

We use a combination of conformal perturbation theory techniques and matrix model results to study the effects of perturbing by momentum modes two dimensional type 0A strings with non-vanishing Ramond-Ramond (RR) flux. In the limit of large RR flux (equivalently, mu=0) we find an explicit analytic form of the genus zero partition function in terms of the RR flux $q$ and the momentum modes coupling constant alpha. The analyticity of the partition function enables us to go beyond the perturbative regime and, for alpha>> q, obtain the partition function in a background corresponding to the momentum modes condensation. For momenta such that 0<p<2 we find no obstruction to condensing the momentum modes in the phase diagram of the partition function.Comment: 22 page

Survivin antiapoptotic gene expression as a prognostic factor in non-small cell lung cancer: in situ hybridization study.

Survivin is an inhibitor of apoptosis that plays a significant role in cell cycle regulation and is important for survival prognosis in many neoplasms. Survivin expression was assessed by in situ hybridization (ISH) in 60 consecutive patients (54 males and 4 females) with NSCLC treated between 1993 and 1997. The examined patients had IIB and IIIA stage according to TNM system. In all cases the chemotherapy with cisplatin and etoposide (2 cycles) was administered prior the surgery; in patients responding to the therapy one more cycle was applied. Survivin gene overexpression was observed in 35 patients (58.3%). There was no correlation between survivin mRNA level and histological type of tumor, stage of cell differentiation, stage of disease according to TNM classification, performance status according to WHO and number of chemotherapy regimens administered (p > 0.05). However, the correlation between survivin gene expression and response to the chemotherapy was statistically significant (p = 0.04). Statistical analysis showed that median survival in patients with survivin gene overexpression was shorter (14.0 months) as compared to patients with no expression (60.0 months; p = 0.00002). In survival assessment by means of Kaplan-Meier test, 14.3% of five-year survival was achieved in the former group versus 60% in the latter (p = 0.00003). Univariate analysis (log-rank test) showed that significant independent prognostic factors in NSCLC included: stage of the disease according to TNM classification (p = 0.006), response to chemotherapy (p = 0.005) and pattern of survivin gene expression (p = 0.00003). Multivariate analysis utilizing Cox's model showed that for survival assessment the stage according to TNM, response to the chemotherapy and survivin expression estimated by means of ISH are of statistical significance (p=0.00001). The calculated predictive values showed that ISH technique was quite accurate in assessment of five-year survival. Our data show that survivin expression may be used as a prognostic factor and a target for therapy

c < 1 String from Two Dimensional Black Holes

We study a topological string description of the c < 1 non-critical string whose matter part is defined by the time-like linear dilaton CFT. We show that the topologically twisted N=2 SL(2,R)/U(1) model (or supersymmetric 2D black hole) is equivalent to the c < 1 non-critical string compactified at a specific radius by comparing their physical spectra and correlation functions. We examine another equivalent description in the topological Landau-Ginzburg model and check that it reproduces the same scattering amplitudes. We also discuss its matrix model dual description.Comment: 36 pages, harvmac; acknowledgements, comments and references adde

Energy Quantisation in Bulk Bouncing Tachyon

We argue that the closed string energy in the bulk bouncing tachyon background is to be quantised in a simple manner as if strings were trapped in a finite time interval. We discuss it from three different viewpoints; (1) the timelike continuation of the sinh-Gordon model, (2) the dual matrix model description of the (1+1)-dimensional string theory with the bulk bouncing tachyon condensate, (3) the c_L=1 limit of the timelike Liouville theory with the dual Liouville potential turned on. There appears to be a parallel between the bulk bouncing tachyon and the full S-brane of D-brane decay. We find the critical value \lambda_c of the bulk bouncing tachyon coupling which is analogous to \lambda_o=1/2 of the full S-brane coupling, at which the system is thought to be at the bottom of the tachyon potential.Comment: 25 pages, minor changes, one reference adde

On The Problem of Particle Production in c=1 Matrix Model

We reconsider and analyze in detail the problem of particle production in the time dependent background of $c=1$ matrix model where the Fermi sea drains away at late time. In addition to the moving mirror method, which has already been discussed in hep-th/0403169 and hep-th/0403275, we describe yet another method of computing the Bogolubov coefficients which gives the same result. We emphasize that these Bogolubov coefficients are approximately correct for small value of the deformation parameter. We also study the time evolution of the collective field theory stress-tensor with a special point-splitting regularization. Our computations go beyond the approximation of the previous treatments and are valid at large coordinate distances from the boundary at a finite time and up-to a finite coordinate distance from the boundary at late time. In this region of validity our regularization produces a certain singular term that is precisely canceled by the collective field theory counter term in the present background. The energy and momentum densities fall off exponentially at large distance from the boundary to the values corresponding to the static background. This clearly shows that the radiated energy reaches the asymptotic region signaling the space-time decay.Comment: 37 pages, 5 figures. Section 6 is modified to clarify main accomplishments of the paper including a discussion comparing stress-tensor analysis with those preexisted in literature. Other modifications include minor changes in the text and addition of one reference. Version accepted for publication in JHE