Non-perturbative double scaling limits

Recently, the author has proposed a generalization of the matrix and vector models approach to the theory of random surfaces and polymers. The idea is to replace the simple matrix or vector (path) integrals by gauge theory or non-linear sigma model (path) integrals. We explain how this solves one of the most fundamental limitation of the classic approach: we automatically obtain non-perturbative definitions in non-Borel summable cases. This is exemplified on the simplest possible examples involving O(N) symmetric non-linear sigma models with N-dimensional target spaces, for which we construct (multi)critical metrics. The non-perturbative definitions of the double scaled, manifestly positive, partition functions rely on remarkable identities involving (path) integrals.Comment: 18 pages, one figur

The Slate all metal airship

The development of the Slate all metal airship City of Glendale built and completed in 1930 is presented. The airship facilities are discussed. Pertinent data which led to other engineering accomplishments for aviation are shown. The SMD-100 concept is presented along with a brief commentary on the costs and problems involved in such an airship design and the application of the hoisting and elevator facilities to airship development

The elliptic genus of Calabi-Yau 3- and 4-folds, product formulae and generalized Kac-Moody algebras

In this paper the elliptic genus for a general Calabi-Yau fourfold is derived. The recent work of Kawai calculating N=2 heterotic string one-loop threshold corrections with a Wilson line turned on is extended to a similar computation where K3 is replaced by a general Calabi-Yau 3- or 4-fold. In all cases there seems to be a generalized Kac-Moody algebra involved, whose denominator formula appears in the result.Comment: 10 pages, latex, no figure

Raman spectroscopy on mechanically exfoliated pristine graphene ribbons

We present Raman spectroscopy measurements of non-etched graphene nanoribbons, with widths ranging from 15 to 160 nm, where the D-line intensity is strongly dependent on the polarization direction of the incident light. The extracted edge disorder correlation length is approximately one order of magnitude larger than on previously reported graphene ribbons fabricated by reactive ion etching techniques. This suggests a more regular crystallographic orientation of the non-etched graphene ribbons here presented. We further report on the ribbons width dependence of the line-width and frequency of the long-wavelength optical phonon mode (G-line) and the 2D-line of the studied graphene ribbons

Back action of graphene charge detectors on graphene and carbon nanotube quantum dots

We report on devices based on graphene charge detectors (CDs) capacitively coupled to graphene and carbon nanotube quantum dots (QDs). We focus on back action effects of the CD on the probed QD. A strong influence of the bias voltage applied to the CD on the current through the QD is observed. Depending on the charge state of the QD the current through the QD can either strongly increase or completely reverse as a response to the applied voltage on the CD. To describe the observed behavior we employ two simple models based on single electron transport in QDs with asymmetrically broadened energy distributions of the source and the drain leads. The models successfully explain the back action effects. The extracted distribution broadening shows a linear dependency on the bias voltage applied to the CD. We discuss possible mechanisms mediating the energy transfer between the CD and QD and give an explanation for the origin of the observed asymmetry.Comment: 6 pages, 4 figure

Abell 3627: A Nearby, X-ray Bright, and Massive Galaxy Cluster

The cluster A3627 was recently recognized to be a very massive, nearby cluster in a galaxy survey close to the galactic plane. We are reporting on ROSAT PSPC observations of this object which confirm that the cluster is indeed very massive. The X-ray emission detected from the cluster extends over almost 1 degree in radius. The X-ray image is not spherically symmetric and shows indications of an ongoing cluster merger. Due to the strong interstellar absorption the spectral analysis and the gas temperature determination are difficult. The data are consistent with an overall gas temperature in the range 5 to 10 keV. There are signs of temperature variations in the merger region. A mass estimate based on the X-ray data yields values of $0.4 - 2.2 \cdot 10^{15}$ \msu \ if extrapolated to the virial radius of $3 h_{50}^{-1}$ Mpc. In the ROSAT energy band (0.1 - 2.4 keV) the cluster emission yields a flux of about $2 \cdot 10^{-10}$ erg s$^{-1}$ cm$^{-2}$ which makes A3627 the 6$^{th}$ brightest cluster in the ROSAT All Sky Survey. The cluster was missed in earlier X-ray surveys because it was confused with a neighbouring X-ray bright, galactic X-ray binary (1H1556-605). The large X-ray flux makes A3627 an important target for future studies.Comment: 14 pages, Latex file, including aaspp.sty, 9 postscript figures and 1 table, accepted for publication by the Astrophysical Journa

The Dynamics of Relief Spending and the Private Urban Labor Market During the New Deal

During the New Deal the Roosevelt Administration dramatically expanded relief spending to combat extraordinarily high rates of unemployment. We examine the dynamic relationships between relief spending and local private labor markets using a new panel data set of monthly relief, private employment and private earnings for major U.S. cities in the 1930s. Impulse response functions derived from a panel VAR model that controls for time and city fixed effects show that a work relief shock in period t-1 led to a decline in private employment and a rise in private monthly earnings. The finding offers evidence consistent with contemporary employers' complaints that work relief made it more difficult to hire, even though work relief officials followed their stated policies to avoid affecting private labor markets directly. Meanwhile, negative shocks to private employment led to increases in work relief, consistent with Roosevelt's stated goal of using relief to promote relief and recovery.

Translation termination depends on the sequential ribosomal entry of eRF1 and eRF3.

Translation termination requires eRF1 and eRF3 for polypeptide-and tRNA-release on stop codons. Additionally, Dbp5/DDX19 and Rli1/ABCE1 are required; however, their function in this process is currently unknown. Using a combination of in vivo and in vitro experiments, we show that they regulate a stepwise assembly of the termination complex. Rli1 and eRF3-GDP associate with the ribosome first. Subsequently, Dbp5-ATP delivers eRF1 to the stop codon and in this way prevents a premature access of eRF3. Dbp5 dissociates upon placing eRF1 through ATP-hydrolysis. This in turn enables eRF1 to contact eRF3, as the binding of Dbp5 and eRF3 to eRF1 is mutually exclusive. Defects in the Dbp5-guided eRF1 delivery lead to premature contact and premature dissociation of eRF1 and eRF3 from the ribosome and to subsequent stop codon readthrough. Thus, the stepwise Dbp5-controlled termination complex assembly is essential for regular translation termination events. Our data furthermore suggest a possible role of Dbp5/DDX19 in alternative translation termination events, such as during stress response or in developmental processes, which classifies the helicase as a potential drug target for nonsense suppression therapy to treat cancer and neurodegenerative diseases

A Theory of Errors in Quantum Measurement

It is common to model random errors in a classical measurement by the normal (Gaussian) distribution, because of the central limit theorem. In the quantum theory, the analogous hypothesis is that the matrix elements of the error in an observable are distributed normally. We obtain the probability distribution this implies for the outcome of a measurement, exactly for the case of 2x2 matrices and in the steepest descent approximation in general. Due to the phenomenon of `level repulsion', the probability distributions obtained are quite different from the Gaussian.Comment: Based on talk at "Spacetime and Fundamental Interactions: Quantum Aspects" A conference to honor A. P. Balachandran's 65th Birthda