Massive Accretion Disks

Recent high resolution near infrared (HST-NICMOS) and mm-interferometric imaging have revealed dense gas and dust accretion disks in nearby ultra-luminous galactic nuclei. In the best studied ultraluminous IR galaxy, Arp 220, the 2 micron imaging shows dust disks in both of the merging galactic nuclei and mm-CO line imaging indicates molecular gas masses approx. 10^9 M_sun for each disk. The two gas disks in Arp 220 are counterrotating and their dynamical masses are approx. 2x10^9 M_sun, that is, only slightly larger than the gas masses. These disks have radii approx 100 pc and thickness 10-50 pc. The high brightness temperatures of the CO lines indicate that the gas in the disks has area filling factors of approx. 25-50% and mean densities of >~ 10^4 cm^(-3). Within these nuclear disks, the rate of massive star formation is undoubtedly prodigious and, given the high viscosity of the gas, there will also be high radial accretion rates, perhaps >~ 10 M_sun/yr. If this inflow persists to very small radii, it is enough to feed even the highest luminosity AGNs.Comment: LaTex, 6 pages with 1 postscript and 1 jpg figure, and 1 postscript table, To appear in the proc. of the Ringberg workshop on "Ultraluminous Galaxies: Monsters or Babies" (Ringberg castle, Sept. 1998), Ap&SS, in pres

The Extreme Nuclear Environments of Sgr A* and Arp 220

The dense ISM which is the fuel for both nuclear starbursts is believed to be accreted to the nucleus by stellar bars and galactic interactions. In this contribution, I summarize the observational results for two galactic nuclei at the extreme ends of starburst/AGN activity − our own Galactic nucleus with SgrA* and the ULIRG Arp 220. I discuss theoretical considerations for the properties of the ISM − its density and scale height, whether it is likely to clump into gravitational bound GMCs − and the self-regulation of SB and AGN fueling due to radiation pressure support of the ISM. The latter yields an Eddington-like limit on the activity for both SB and AGN, corresponding to approximately 500 L_ʘ/M_ʘ for optically thick regions in which the radiation has been degraded to the NIR

Polaron Energy Spectrum in Quantum Dots

Energy spectrum of a weak coupling polaron is considered in a cylindrical quantum dot. An analytical expression for the polaron energy shift is obtained using a modified pertubation theory.Comment: 7 pages, IOP style LaTeX fil

Energy Dependence of the Pomeron Spin-Flip

There is no theoretical reason to think that the spin-flip component of the Pomeron is zero. One can measure the spin-flip part using Coulomb-nuclear interference (CNI). Perturbative QCD calculations show that the spin-flip component is sensitive to the smallest quark separation in the proton, while the non-flip part probes the largest separation. According to HERA results on the proton structure function at very low x the energy dependence of the cross-section correlates with the size of the color dipole. Analysing the data from HERA we predict that the ratio of the spin-flip to non-flip amplitude grows with energy as $r(s)\propto (1/x)^{0.1-0.2}$, violating Regge factorisation of the Pomeron.Comment: A few comments and references are added. Based on invited talks at the International Workshop on Diffraction Physics, Rio de Janeiro, February 16-20, 1998, and at DIS'98, Brussels, April 4-8, 199

Aneuploidy and proteotoxic stress in cancer

Although nearly ubiquitous in cancer, aneuploidy exerts detrimental effects on human cells. We recently demonstrated that aneuploid human cells exhibit impaired heat shock factor protein 1 (HSF1) and HSP90 function, suggesting a functional link between two recurring features of cancer cells: aneuploidy and proteotoxic stress. Further, our fi ndings implicate HSF1 as a key factor in mitigating the effects of aneuploid