32P-Postlabeling of a DNA adduct derived from 4,4′-methylenedianiline, in the olfactory epithelium of rats exposed by inhalation to 4,4′-methylenediphenyl diisocyanate

Tissues obtained from female Wistar rats exposed to a 0.9 μm aerosol of 4,4′-methylenediphenyl diisocyanate (MDI) for 17 h per day, 5 days per week, for one year, at levels of 0, 0.3, 0.7 and 2.0 mg/m3, were analyzed for DNA adducts. A 32P-postlabeling method was used to detect (i). adducts formed by the reaction of the isocyanate group(s) of MDI with DNA; and a 32P-postlabeling method was adapted to detect (ii), a DNA adduct formed by 4,4′-methylenedianiline (MDA), a hydrolysis/decarboxylation product of MDI. In the lung, neither isocyanate adducts nor the arylamine adduct were detectable. The same negative result was seen in the liver, the bladder, the kidney, the respiratory epithelium and in peripheral lymphocytes. In the olfactory epithelium, on the other hand, the aryl-amine-derived DNA adduct was detected, at the very low levels of 5, 9 and 10 adduct-nucleotides per 1010 nucleotides, for the three dose groups, respectively. The adduct co-chromatographed with the one formed in the liver of rats after oral gavage of MDA. The results are discussed in terms of the importance of genotoxic versus nongenotoxic aspects of carcinogenesi

Validity of Landauer's principle in the quantum regime

We demonstrate the validity of Landauer's erasure principle in the strong coupling quantum regime by treating the system-reservoir interaction in a consistent way. We show that the initial coupling to the reservoir modifies both energy and entropy of the system and provide explicit expressions for the latter in the case of a damped quantum harmonic oscillator. These contributions are related to the Hamiltonian of mean force and dominate in the strong damping limit. They need therefore to be fully taken into account in any low-temperature thermodynamic analysis of quantum systems.Comment: 4 pages, 2 figure

Dense Ionized and Neutral Gas Surrounding Sgr A*

We present high resolution H41a hydrogen recombination line observations of the 1.2' (3 pc) region surrounding Sgr A* at 92 GHz using the OVRO Millimeter Array with an angular resolution of 7" x 3" and velocity resolution of 13 km/s. New observations of H31a, H35a, H41a, and H44a lines were obtained using the NRAO 12-m telescope, and their relative line strengths are interpreted in terms of various emission mechanisms. These are the most extensive and most sensitive observations of recombination line to date. Observations of HCO+ (1 - 0) transition at 89 GHz are also obtained simultaneously with a 40% improved angular resolution and 4-15 times improved sensitivity over previous observations, and the distribution and kinematics of the dense molecular gas in the circumnuclear disk (CND) are mapped and compared with those of the ionized gas. The line brightness ratios of the hydrogen recombination lines are consistent with purely spontaneous emission from 7000 K gas with n_e = 20,000 cm$^{-3}$ near LTE condition. A virial analysis suggests that the most prominent molecular gas clumps in the CND have mean densities of 10^7 cm^{-3}, sufficient to withstand the tidal shear in the Galactic Center region. Therefore, these clumps may survive over several dynamical times, and the CND may be a dynamically stable structure. We estimate a total gas mass of 3 x 10^5 solar mass for the CND. \Comment: 34 pages including 11 figures (4 jpgs), Latex, uses aastex. The full pdf format file including high resolution figures is available at http://www.astro.umass.edu/~myun/papers/SgrA.pdf . To appear in the 20 November 2004 (V616) issue of the Astrophysical Journa

Effective thermodynamics of strongly coupled qubits

Interactions between a quantum system and its environment at low temperatures can lead to violations of thermal laws for the system. The source of these violations is the entanglement between system and environment, which prevents the system from entering into a thermal state. On the other hand, for two-state systems, we show that one can define an effective temperature, placing the system into a `pseudo-thermal' state where effective thermal laws are upheld. We then numerically explore these assertions for an n-state system inspired by the spin-boson environment.Comment: 9 pages, 3 figure

Fractional transport equations for Levy stable processes

The influence functional method of Feynman and Vernon is used to obtain a quantum master equation for a Brownian system subjected to a Levy stable random force. The corresponding classical transport equations for the Wigner function are then derived, both in the limit of weak and strong friction. These are fractional extensions of the Klein-Kramers and the Smoluchowski equations. It is shown that the fractional character acquired by the position in the Smoluchowski equation follows from the fractional character of the momentum in the Klein-Kramers equation. Connections among fractional transport equations recently proposed are clarified.Comment: 4 page

Dewetting of thin films on heterogeneous substrates: Pinning vs. coarsening

We study a model for a thin liquid film dewetting from a periodic heterogeneous substrate (template). The amplitude and periodicity of a striped template heterogeneity necessary to obtain a stable periodic stripe pattern, i.e. pinning, are computed. This requires a stabilization of the longitudinal and transversal modes driving the typical coarsening dynamics during dewetting of a thin film on a homogeneous substrate. If the heterogeneity has a larger spatial period than the critical dewetting mode, weak heterogeneities are sufficient for pinning. A large region of coexistence between coarsening dynamics and pinning is found.Comment: 4 pages, 4 figure

Rotating Nuclear Rings and Extreme Starbursts in Ultraluminous Galaxies

New high resolution interferometer data of 10 IR ultraluminous galaxies shows the molecular gas is in rotating nuclear rings or disks with radii 300 to 800 pc. Most of the CO flux comes from a moderate-density, warm, intercloud medium rather than self-gravitating clouds. Gas masses of ~ 5 x 10^9 Msun, 5 times lower than the standard method are derived from a model of the molecular disks. The ratio of molecular gas to dynamical mass, is M_gas/M_dyn ~ 1/6 with a maximum ratio of gas to total mass surface density of 1/3. For the galaxies VIIZw31, Arp193, and IRAS 10565+24, there is good evidence for rotating molecular rings with a central gap. In addition to the rotating rings a new class of star formation region is identified which we call an Extreme Starburst. They have a characteristic size of only 100 pc., about 10^9 Msun of gas and an IR luminosity of ~3 x 10^11 Lsun. Four extreme starbursts are identified in the 3 closest galaxies in the sample Arp220, Arp193 and Mrk273. They are the most prodigious star formation events in the local universe, each representing about 1000 times as many OB stars as 30 Doradus. In Arp220, the CO and 1.3 mm continuum maps show the two ``nuclei'' embedded in a central ring or disk and a fainter structure extending 3 kpc to the east, normal to the nuclear disk. There is no evidence that these sources really are the pre-merger nuclei. They are compact, extreme starburst regions containing 10^9 Msun of dense molecular gas and new stars, but no old stars. Most of the dust emission and HCN emission arises in the two extreme starbursts. The entire bolometric luminosity of Arp~220 comes from starbursts, not an AGN. In Mrk231, the disk geometry shows that the molecular disk cannot be heated by the AGN; the far IR luminosity of Mrk~231 is powered by a starburst, not the AGN. (Abridged)Comment: 97 pages Latex with aasms.sty, including 29 encapsulated Postscript figures. Figs 18 and 23 are GIFs. 31 figures total. Text and higher quality versions of figures available at http://sbastk.ess.sunysb.edu/www/RINGS_ESB_PREPRINT.html To be published in Ap. J., 10 Nov. 199

A prototype liquid Argon Time Projection Chamber for the study of UV laser multi-photonic ionization

This paper describes the design, realization and operation of a prototype liquid Argon Time Projection Chamber (LAr TPC) detector dedicated to the development of a novel online monitoring and calibration system exploiting UV laser beams. In particular, the system is intended to measure the lifetime of the primary ionization in LAr, in turn related to the LAr purity level. This technique could be exploited by present and next generation large mass LAr TPCs for which monitoring of the performance and calibration plays an important role. Results from the first measurements are presented together with some considerations and outlook.Comment: 26 pages, 27 figure

Hyperon-nucleon scattering and hyperon masses in the nuclear medium

We analyze low-energy hyperon-nucleon scattering using an effective field theory in next-to-leading order. By fitting experimental cross sections for laboratory hyperon momenta below 200 MeV/c and using information from the hypertriton we determine twelve contact-interaction coefficients. Based on these we discuss the low-density expansion of hyperon mass shifts in the nuclear medium.Comment: 10 pages, 2 figure

Stellar Dynamics and the implications on the merger evolution in NGC6240

We report near-infrared integral field spectroscopy of the luminous merging galaxy NGC 6240. Stellar velocities show that the two K-band peaks separated by 1.6arcsec are the central parts of inclined, rotating disk galaxies with equal mass bulges. The dynamical masses of the nuclei are much larger than the stellar mass derived from the K-band light, implying that the progenitor galaxies were galaxies with massive bulges. The K-band light is dominated by red supergiants formed in the two nuclei in starbursts, triggered ~2x10^7 years ago, possibly by the most recent perigalactic approach. Strong feedback effects of a superwind and supernovae are responsible for a short duration burst (~5x10^6 years) which is already decaying. The two galaxies form a prograde-retrograde rotating system and from the stellar velocity field it seems that one of the two interacting galaxies is subject to a prograde encounter. Between the stellar nuclei is a prominent peak of molecular gas (H_2, CO). The stellar velocity dispersion peaks there indicating that the gas has formed a local, self-gravitating concentration decoupled from the stellar gravitational potential. NGC 6240 has previously been reported to fit the paradigm of an elliptical galaxy formed through the merger of two galaxies. This was based on the near-infrared light distribution which follows a r^1/4-law. Our data cast strong doubt on this conclusion: the system is by far not relaxed, rotation plays an important role, as does self-gravitating gas, and the near-infrared light is dominated by young stars.Comment: 34 pages, 11 figures, using AASTEX 5.0rc3.1, paper submitted to the Astrophysical Journal, revised versio