Characterizing the Delaunay decompositions of compact hyperbolic surfaces

Given a Delaunay decomposition of a compact hyperbolic surface, one may record the topological data of the decomposition, together with the intersection angles between the `empty disks' circumscribing the regions of the decomposition. The main result of this paper is a characterization of when a given topological decomposition and angle assignment can be realized as the data of an actual Delaunay decomposition of a hyperbolic surface.Comment: Published by Geometry and Topology at http://www.maths.warwick.ac.uk/gt/GTVol6/paper12.abs.htm

The Role of Information Theory in Gap-Filler Dependencies

The current study examines how formal grammar and information-theoretic complexity metrics can combine to account for processing cost incurred during incremental sentence comprehension. To this end, we modeled the eye-movement reading measures obtained from an experiment on the wh-in-situ construction in Mandarin Chinese. Framing our syntactic analysis in minimalist grammars, we obtained estimates of grammatical choice-point probabilities from the Penn Chinese Tree Bank, and derived values for two different complexity metrics, suprisal and entropy reduction, at each word of the target sentences. Both metrics accounted for a small but significant amount of the eye-movement data

Microbial electrocatalysis with Geobacter sulfurreducens biofilm on stainless steel cathodes

Stainless steel and graphite electrodes were individually addressed and polarized at−0.60V vs. Ag/AgCl in reactors filled with a growth medium that contained 25mM fumarate as the electron acceptor and no electron donor, in order to force the microbial cells to use the electrode as electron source. When the reactor was inoculated with Geobacter sulfurreducens, the current increased and stabilized at average values around 0.75Am−2 for graphite and 20.5Am−2 for stainless steel. Cyclic voltammetry performed at the end of the experiment indicated that the reduction started at around −0.30V vs. Ag/AgCl on stainless steel. Removing the biofilm formed on the electrode surface made the current totally disappear, confirming that the G.sulfurreducens biofilm was fully responsible for the electrocatalysis of fumarate reduction. Similar current densities were recorded when the electrodes were polarized after being kept in open circuit for several days. The reasons for the bacteria presence and survival on non-connected stainless steel coupons were discussed. Chronoamperometry experiments performed at different potential values suggested that the biofilm-driven catalysis was controlled by electrochemical kinetics. The high current density obtained, quite close to the redox potential of the fumarate/succinate couple, presents stainless steel as a remarkable material to support biocathodes

A meteorological overview of the Pacific Exploratory Mission (PEM) Tropics period

NASA's Pacific Exploratory Mission-Tropics (PEM-T) experiment investigated the atmospheric chemistry of a large portion of the tropical and subtropical Pacific Basin during August to October 1996. This paper summarizes meteorological conditions over the PEM-T domain. Mean flow patterns during PEM-T are described. Important circulation systems near the surface include subtropical anticyclones, the South Pacific Convergence Zone (SPCZ), the Intertropical Convergence Zone (ITCZ), and middle latitude transient cyclones. The SPCZ and ITCZ are areas of widespread ascent and deep convection; however, there is relatively little lightning in these oceanic regions. A large area of subsidence is associated with the subtropical anticyclone centered near Easter Island. PEM-T occurred during a period of near normal sea surface temperatures. When compared to an 11 year climatology (1986-1996), relatively minor circulation anomalies are observed during PEM-T. Some of these circulation anomalies are consistent with much stronger anomalies observed during previous La Nina events. In general, however, the 1996 PEM-T period appears to be climatologically representative. Meteorological conditions for specific flights from each major operations area are summarized. The vertical distribution of ozone along selected DC-8 flights is described using the DIAL remote sensing system. These ozone distributions are related to thermodynamic soundings obtained during aircraft maneuvers and to backward trajectories that arrived at locations along the flight tracks. Most locations in the deep tropics are found to have relatively small values of tropospheric ozone. Backward trajectories calculated from global gridded analyses show that much of this air originates from the east and has not passed over land within 10 days. The deep convection associated with the ITCZ and SPCZ also influences the atmospheric chemistry of these regions. Flights over portions of the subtropics and middle latitudes document layers of greatly enhanced tropospheric ozone, sometimes exceeding 80 ppbv. In situ carbon monoxide in these layers often exceeds 90 ppbv. These regions are located near, and especially south of Tahiti, Easter Island, and Fiji. The layers of enhanced ozone usually correspond to layers of dry air, associated with widespread subsiding air. The backward trajectories show that air parcels arriving in these regions originate from the west, passing over Australia and even extending back to southern Africa. These are regions of biomass burning. The in situ chemical measurements support the trajectory-derived origins of these ozone plumes. Thus the enhanced tropospheric ozone over the central Pacific Basin may be due to biomass burning many thousands of kilometers away. Middle-latitude portions of the PEM-T area are influenced by transient cyclones, and the DC-8 traversed tropopause folds during several flights. The flight area just west of Ecuador experiences outflow from South America. Thus the biomass burning that is prevalent over portions of Brazil influences this area. Copyright 1999 by the American Geophysical Union

QCD at Finite temperature and density with staggered and Wilson quarks

One of the most challenging issues in particle physics is to study QCD in extreme conditions. Precise determination of the QCD phase diagram on temperature $T$ and chemical potential $\mu$ plane will provide valuable information for quark-gluon plasma (QGP) and neutron star physics. We present results for phase structure on the $(\mu, T)$ plane for lattice QCD with Wilson fermions from strong coupling Hamiltonian analysis and Kogut-Susskind Fermions from Lagrangian Monte Carlo simulations at intermediate coupling.Comment: Lattice 2004 (nonzero

An advanced cost estimation methodology for engineering systems

A mathematically advanced method for improving the fidelity of cost estimation for an engineering system is presented. In this method historical cost records can be expanded either through the use of local metamodels or by using an engineering build‐up model. In either case, the expanded data set is analyzed using principal component analysis (PCA) in order to identify the physical parameters, and the principal components (PCs) which demonstrate the highest correlation to the cost. A set of predictor variables, composed of the physical parameters and of the multipliers of the principal components which demonstrate the highest correlation to the cost, is developed. This new set of predictor variables is regressed, using the Kriging method, thus creating a cost estimation model with a high level of predictive capability and fidelity. The new methodology is used for analyzing a set of cost data available in the literature, and the new cost model is compared to results from a neural network based analysis and to a cost regression model. Further, a case study addressing the fabrication of a submarine pressure hull is developed in order to illustrate the new method. The results from the final regression model are presented and compared to results from other cost regression methods. The technical characteristics of the new novel general method are presented and discussed. © 2011 Wiley Periodicals, Inc. Syst EngPeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90246/1/20192_ftp.pd