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Improved oil recovery in Mississippian carbonate reservoirs of Kansas near term Class 2. Annual report, September 18, 1994--March 15, 1997
This annual report describes progress during the second year of the project entitled {open_quotes}Improved Oil Recovery in Mississippian Carbonate Reservoirs in Kansas{close_quotes}. This project funded under the Department of Energy`s Class 2 program targets improving the reservoir performance of mature oil fields located in shallow shelf carbonate reservoirs. The focus of this project is development and demonstration of cost-effective reservoir description and management technologies to extend the economic life of mature reservoirs in Kansas and the mid-continent. As part of the project, several tools and techniques for reservoir description and management were developed, modified and demonstrated. These include: (1) a new approach to subsurface visualization using electric logs ({open_quotes}Pseudoseismic{open_quotes}); (2) a low-cost easy-to-use spreadsheet log analysis software (PfEFFER); and (3) an extension of the BOAST-3 computer program for full field reservoir simulation. The world-wide-web was used to provide rapid and flexible dissemination of the project results through the Internet. Included in this report is a summary of significant project results at the demonstration site (Schaben Field, Ness County, Kansas). These results include an outline of the reservoir description based on available and newly acquired data and reservoir simulation results. Detailed information is available on-line through the Internet. Based on the reservoir simulation, three infill wells will be drilled to validate the reservoir description and demonstrate the effectiveness of the proposed reservoir management strategies. The demonstration phase of the project has just begun and will be presented in the next annual report
One-loop Correction and the Dilaton Runaway Problem
We examine the one-loop vacuum structure of an effective theory of gaugino
condensation coupled to the dilaton for string models in which the gauge
coupling constant does not receive string threshold corrections. The new
ingredients in our treatment are that we take into account the one-loop
correction to the dilaton K\"ahler potential and we use a formulation which
includes a chiral field corresponding to the gaugino bilinear. We find
through explicit calculation that supersymmetry in the Yang-Mills sector is
broken by gaugino condensation.
The dilaton and field have masses on the order of the gaugino
condensation scale independently of the dilaton VEV. Although the calculation
performed here is at best a model of the full gaugino condensation dynamics,
the result shows that the one-loop correction to the dilaton K\"ahler potential
as well as the detailed dynamics at the gaugino condensation scale may play an
important role in solving the dilaton runaway problem.Comment: 19 page
Non-Abelian Born-Infeld Action and Type I - Heterotic Duality (II): Nonrenormalization Theorems
Type I - heterotic duality in D=10 predicts various relations and constraints
on higher order F^n couplings at different string loop levels on both sides. We
prove the vanishing of two-loop corrections to the heterotic F^4 terms, which
is one of the basic predictions from this duality. Furthermore, we show that
the heterotic F^5 and (CP even) F^6 couplings are not renormalized at one loop.
These results strengthen the conjecture that in D=10 any Tr F^(2n) coupling
appears only at the disc tree-level on type I side and at (n-1)-loop level on
the heterotic side. Our non-renormalization theorems are valid in any heterotic
string vacuum with sixteen supercharges.Comment: 35 pages, harvmac; cosmetic changes; final version to appear in NP
Direct Production of Lightest Regge Resonances
We discuss direct production of Regge excitations in the collisions of
massless four-dimensional superstring states, focusing on the first excited
level of open strings ending on D-branes extending into higher dimensions. We
construct covariant vertex operators and identify ``universal'' Regge states
with the internal parts either trivial or determined by the world-sheet SCFT
describing superstrings propagating on an arbitrary Calabi-Yau manifold. We
evaluate the amplitudes involving one such massive state and up to three
massless ones and express them in the helicity basis. The most important
phenomenological applications of our results are in the context of low-mass
string (and large extra dimensions) scenarios in which excited string states
are expected to be produced at the LHC as soon as the string mass threshold is
reached in the center-of-mass energies of the colliding partons. In order to
facilitate the use of partonic cross sections, we evaluate them and tabulate
for all production processes: gluon fusion, quark absorbing a gluon,
quark-antiquark annihilation and quark-quark scattering.Comment: 43 pages, RevTeX 4.
Study of the three-dimensional shape and dynamics of coronal loops observed by Hinode/EIS
We study plasma flows along selected coronal loops in NOAA Active Region
10926, observed on 3 December 2006 with Hinode's EUV Imaging Spectrograph
(EIS). From the shape of the loops traced on intensity images and the Doppler
shifts measured along their length we compute their three-dimensional (3D)
shape and plasma flow velocity using a simple geometrical model. This
calculation was performed for loops visible in the Fe VIII 185 Ang., Fe X 184
Ang., Fe XII 195 Ang., Fe XIII 202 Ang., and Fe XV 284 Ang. spectral lines. In
most cases the flow is unidirectional from one footpoint to the other but there
are also cases of draining motions from the top of the loops to their
footpoints. Our results indicate that the same loop may show different flow
patterns when observed in different spectral lines, suggesting a dynamically
complex rather than a monolithic structure. We have also carried out magnetic
extrapolations in the linear force-free field approximation using SOHO/MDI
magnetograms, aiming toward a first-order identification of extrapolated
magnetic field lines corresponding to the reconstructed loops. In all cases,
the best-fit extrapolated lines exhibit left-handed twist (alpha < 0), in
agreement with the dominant twist of the region.Comment: 17 pages, 6 figure
Axion Couplings and Effective Cut-Offs in Superstring Compactifications
We use the linear supermultiplet formalism of supergravity to study axion
couplings and chiral anomalies in the context of field-theoretical Lagrangians
describing orbifold compactifications beyond the classical approximation. By
matching amplitudes computed in the effective low energy theory with the
results of string loop calculations we determine the appropriate counterterm in
this effective theory that assures modular invariance to all loop order. We use
supersymmetry consistency constraints to identify the correct ultra-violet
cut-offs for the effective low energy theory. Our results have a simple
interpretation in terms of two-loop unification of gauge coupling constants at
the string scale.Comment: 25 page
Lectures on Heterotic-Type I Duality
We present a review of heterotic-type I string duality. In particular, we
discuss the effective field theory of six- and four-dimensional
compactifications with N>1 supersymmetries. We then describe various duality
tests by comparing gauge couplings, N=2 prepotentials, as well as
higher-derivative F-terms. Based on invited lectures delivered at: 33rd Karpacz
Winter School of Theoretical Physics ``Duality, Strings and Fields,''
Przesieka, Poland, 13 - 22 February 1997; Trieste Conference on Duality
Symmetries in String Theory, Trieste, Italy, 1 - 4 April 1997; Cargese Summer
School ``Strings, Branes and Dualities,'' Cargese, France, 26 May - 14 June
1997.Comment: 14 pages, LaTeX, espcrc2.st
A microbubble-sparged yeast propagation–fermentation process for bioethanol production
Background
Industrial biotechnology will play an increasing role in creating a more sustainable global economy. For conventional aerobic bioprocesses supplying O2 can account for 15% of total production costs. Microbubbles (MBs) are micron-sized bubbles that are widely used in industry and medical imaging. Using a fluidic oscillator to generate energy-efficient MBs has the potential to decrease the costs associated with aeration. However, little is understood about the effect of MBs on microbial physiology. To address this gap, a laboratory-scale MB-based Saccharomyces cerevisiae Ethanol Red propagation–fermentation bioethanol process was developed and analysed.
Results
Aeration with MBs increased O2 transfer to the propagation cultures. Titres and yields of bioethanol in subsequent anaerobic fermentations were comparable for MB-propagated and conventional, regular bubble (RB)-propagated yeast. However, transcript profiling showed significant changes in gene expression in the MB-propagated yeast compared to those propagated using RB. These changes included up-regulation of genes required for ergosterol biosynthesis. Ergosterol contributes to ethanol tolerance, and so the performance of MB-propagated yeast in fed-batch fermentations sparged with 1% O2 as either RBs or MBs were tested. The MB-sparged yeast retained higher levels of ergosteryl esters during the fermentation phase, but this did not result in enhanced viability or ethanol production compared to ungassed or RB-sparged fermentations.
Conclusions
The performance of yeast propagated using energy-efficient MB technology in bioethanol fermentations is comparable to that of those propagated conventionally. This should underpin the future development of MB-based commercial yeast propagation
Fast evaluation of appointment schedules for outpatients in health care
We consider the problem of evaluating an appointment schedule for outpatients in a hospital. Given a fixed-length session during which a physician sees K patients, each patient has to be given an appointment time during this session in advance. When a patient arrives on its appointment, the consultations of the previous patients are either already finished or are still going on, which respectively means that the physician has been standing idle or that the patient has to wait, both of which are undesirable. Optimising a schedule according to performance criteria such as patient waiting times, physician idle times, session overtime, etc. usually requires a heuristic search method involving a huge number of repeated schedule evaluations. Hence, the aim of our evaluation approach is to obtain accurate predictions as fast as possible, i.e. at a very low computational cost. This is achieved by (1) using Lindley's recursion to allow for explicit expressions and (2) choosing a discrete-time (slotted) setting to make those expression easy to compute. We assume general, possibly distinct, distributions for the patient's consultation times, which allows us to account for multiple treatment types, as well as patient no-shows. The moments of waiting and idle times are obtained. For each slot, we also calculate the moments of waiting and idle time of an additional patient, should it be appointed to that slot. As we demonstrate, a graphical representation of these quantities can be used to assist a sequential scheduling strategy, as often used in practice
A pulsating white dwarf in an eclipsing binary
White dwarfs are the burnt-out cores of Sun-like stars and are the fate of 97 per cent of the stars in our Galaxy. The internal structure and composition of white dwarfs are hidden by their high gravities, which causes all elements apart from the lightest ones to settle out of their atmospheres. The most direct method of probing the inner structure of stars and white dwarfs in detail is via asteroseismology. Here we present a pulsating white dwarf in an eclipsing binary system, enabling us to place extremely precise constraints on the mass and radius of the white dwarf from the lightcurve, independent of the pulsations. This 0.325-solar-mass white dwarf—one member of the SDSS J115219.99+024814.4 system—will serve as a powerful benchmark with which to constrain empirically the core composition of low-mass stellar remnants and to investigate the effects of close binary evolution on the internal structure of white dwarfs
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