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Objective:The aim of this study was to identify risk factors for early-onset group B Streptococcus (EOGBS) disease in neonates of mothers with negative antenatal screening.Study Design:We performed a retrospective cohort study of neonates born to mothers with negative antenatal GBS screening between 2002 and 2012. Our primary outcome was EOGBS infection. We used multivariable logistic regression to assess factors associated with EOGBS.Results:EOGBS was confirmed in 492 of the 179 818 neonates that met the study inclusion criteria. Risk factors for EOGBS included black race (reference: white, odds ratio (OR) =1.81 (95% confidence interval: 1.43, 2.31)), maternal age <18 years (reference: >35 years, OR=2.63 (1.54, 4.51)) and maternal age 18 to 35 years (reference: >35 years, OR=1.94 (1.30, 2.88)).Conclusion:Maternal age <18 years and black race were the strongest predictors of EOGBS. Further research investigating contributors to the discordance between screening results and neonatal outcomes in these populations is needed.

AbstractThe critical issue of divertor configuration for heat and particle flux control in a conceptual ARIES compact stellarator (CS) reactor is addressed. The goal is to determine a divertor location and geometry with a peak heat load of not more than 10 MW/m2for a CS equilibrium based on the configuration to be used in the NCSX experiment, optimized for high beta (6.4%) and designed for low alpha-particle power loss fraction (≤5%). The surface heat flux on the target has three components: thermal particles, lost energetic alphas, and radiation from the core and the scrape-off layer. The first two components are dominant and their magnitudes can be comparable. To maintain a tritium-breeding ratio of 1.1, the total target area should not exceed 15% of the boundary plasma surface area. The divertor concept consists of two pairs of target plates per field period, one pair each at the top and bottom of the plasma. The heat flux profile is assessed by assuming that the parallel transport can be represented by field line mapping and that cross-field transport can be modeled with a prescribed field line diffusion scheme. In this manner, the poloidal and toroidal extents of the plates and their shape and distance to the plasma are designed to intercept all the heat flux and to minimize the peak thermal heat load. An approximate scheme, based on particle drift orbits in the core and field line tracing in the edge, is derived to estimate the alpha-particle heat load distribution over the plates and the first wall. The best plate configuration to date yields total peak heat loads (thermal + alpha) ranging from 5 to 18 MW/m2. Further optimization of the target plates is required to reach the design goal, which will be addressed in a future study.

AbstractWithin the ARIES-CS project, design activities have focused on developing the first compact device that enhances the attractiveness of the stellarator as a power plant. The objectives of this paper are to review the nuclear elements that received considerable attention during the design process and provide a perspective on their successful integration into the final design. Among these elements are the radial build definition, the well-optimized in-vessel components that satisfy the ARIES top-level requirements, the carefully selected nuclear and engineering parameters to produce an economic optimum, the modeling - for the first time ever - of the highly complex stellarator geometry for the three-dimensional nuclear assessment, and the overarching safety and environmental constraints to deliver an attractive, reliable, and truly compact stellarator power plant.

AbstractThe ARIES-CS study focusing on the conceptual design and assessment of a compact stellarator power plant identified the important advantages and key issues associated with such a design. The coil configuration and structural support approach represent key design challenges, with the final design and material choices affected by a number of material and geometry constraints. This paper describes the design configuration and analysis and material choices for the ARIES-CS magnets and its structure. To meet aggressive cost and assembly/maintenance goals, the magnets are designed as lifetime components. Due to the very complex geometry, one of the goals of the study was to provide a robust operational design. This decision has significant implications on cost and manufacturing requirements. Concepts with both conventional and advanced superconductors have been explored. The coil structure design approach adopted is to wind all six modular coils of one field period in grooves in one monolithic coil structural shell (one per field period). The coil structural shells are then bolted together to form a strong structural shell to react the net radial forces. Extensive engineering analyses of the coil system have been performed using ANSYS shell and solid modeling. These include electromagnetic (EM) analyses to calculate the magnetic fields and EM forces and structural analyses to evaluate the structural responses and optimize the coil support system, which has a considerable impact on the cost of the ARIES-CS power plant.

AbstractA stellarator systems/optimization code is used to optimize the ARIES-CS fusion power plant parameters for minimum cost of electricity subject to a large number of physics, engineering, and in-vessel component constraints for a compact stellarator configuration. Different physics models, reactor component models, and costing algorithms are used to test sensitivities to models and assumptions. The most important factors determining the size of the fusion power core are the allowable neutron and radiative power fluxes to the wall, the distance needed between the edge of the plasma and the nonplanar magnetic field coils for the intervening components, and an adequate tritium breeding ratio. The magnetic field and coil parameters are determined from both plasma performance and constraints on the Nb3Sn superconductor. The same costing approach and algorithms used in previous ARIES studies are used with updated material costs. The result is a compact stellarator reactor with a major radius close to that of tokamaks. A one-dimensional power balance code is used to study the path to ignition and the effect of different plasma and confinement assumptions on plasma performance for the reference plasma and coil configuration. A number of variations are studied that affect the size and cost of the fusion power core: maximum field at the coils, component cost penalties, a different blanket and shield approach, alternative plasma and coil configurations, etc. Comparisons are made with some earlier ARIES power plant studies. A number of issues for the development of compact quasi-axisymmetric stellarators are identified.

AbstractNovel stellarator configurations have been developed for ARIES-CS. These configurations are optimized to provide good plasma confinement and flux surface integrity at high beta. Modular coils have been designed for them in which the space needed for the breeding blanket and radiation shielding was specifically targeted such that reactors generating GW electrical powers would require only moderate major radii (<10 m). These configurations are quasi-axially symmetric in the magnetic field topology and have small numbers of field periods (≤3) and low aspect ratios (≤6). The baseline design chosen for detailed systems and power plant studies has three field periods, aspect ratio 4.5, and major radius 7.5 m operating at β ~ 6.5% to yield 1 GW of electric power. The shaping of the plasma accounts for ≥75% of the rotational transform. The effective helical ripples are very small (<0.6% everywhere), and the energy loss of alpha particles is calculated to be ≤5% when operating in high-density regimes. An interesting feature in this configuration is that instead of minimizing all residues in the magnetic spectrum, we preferentially retained a small amount of the nonaxisymmetric mirror field. The presence of this mirror and its associated helical field alters the ripple distribution, resulting in the reduced ripple-trapped loss of alpha particles despite the long connection length in a tokamak-like field structure. Additionally, we discuss two other potentially attractive classes of configurations, both quasi-axisymmetric: one with only two field periods, very low aspect ratios (~2.5), and less complex coils, and the other with the plasma shaping designed to produce low-shear rotational transform so as to ensure the robustness and integrity of flux surfaces when operating at high β.

AbstractAn integrated study of compact stellarator power plants, ARIES-CS, has been conducted to explore attractive compact stellarator configurations and to define key research and development (R&D) areas. The large size and mass predicted by earlier stellarator power plant studies had led to cost projections much higher than those of the advanced tokamak power plant. As such, the first major goal of the ARIES-CS research was to investigate if stellarator power plants can be made to be comparable in size to advanced tokamak variants while maintaining desirable stellarator properties. As stellarator fusion core components would have complex shapes and geometry, the second major goal of the ARIES-CS study was to understand and quantify, as much as possible, the impact of the complex shape and geometry of fusion core components. This paper focuses on the directions we pursued to optimize the compact stellarator as a fusion power plant, summarizes the major findings from the study, highlights the key design aspects and constraints associated with a compact stellarator, and identifies the major issues to help guide future R&D.

AbstractWithin the ARIES-CS project, design activities have focused on developing the first compact device that enhances the attractiveness of the stellarator as a power plant. The objectives of this paper are to review the nuclear elements that received considerable attention during the design process and provide a perspective on their successful integration into the final design. Among these elements are the radial build definition, the well-optimized in-vessel components that satisfy the ARIES top-level requirements, the carefully selected nuclear and engineering parameters to produce an economic optimum, the modeling - for the first time ever - of the highly complex stellarator geometry for the three-dimensional nuclear assessment, and the overarching safety and environmental constraints to deliver an attractive, reliable, and truly compact stellarator power plant.

AbstractThe ideal magnetohydrodynamic (MHD) stability of the National Compact Stellarator Experiment (NCSX) is extensively analyzed using the most advanced three-dimensional MHD codes. It is shown that the NCSX is stable to finite-nMHD modes, including the vertical mode, external kink modes and ballooning modes. However, high-nexternal kink modes that peak near the plasma edge are found to be weakly unstable. A global calculation shows that finite-nballooning modes are significantly more stable than the local infinite-nmodes.

AbstractThe National Compact Stellarator Experiment (NCSX) will study the physics of low-aspect ratio, high-β, quasi-axisymmetric stellarators. To achieve the scientific goals of the NCSX mission, the device must be capable of supporting a wide range of variations in plasma configuration about a reference baseline equilibrium. We demonstrate the flexibility of NCSX coils to support such configuration variations and demonstrate the robustness of performance of NCSX plasmas about reference design values of the plasma current Ip, β, and profile shapes. The robustness and flexibility calculations make use of free-boundary plasma equilibrium constructions using a combination of nonaxisymmetric modular coils and axisymmetric toroidal and poloidal field coils. The primary computational tool for the studies is STELLOPT, a free-boundary optimization code that varies coil currents to target configurations with specific physics properties.

AbstractEquilibrium issues encountered in the design of the National Compact Stellarator Experiment (NCSX) are discussed, focusing particularly on equilibrium magnetic islands. Significant improvements have been made to the VMEC equilibrium code to deal with numerical challenges at the low aspect ratios characterizing the NCSX design. Modifications to the PIES code have increased its speed, allowing routine evaluation of flux surfaces for candidate configurations. An optimizer has been built around the PIES code for healing magnetic islands, modifying the coil shapes to suppress resonant components of the magnetic field while preserving desired physics and engineering properties. The modified coils produce improved flux surface quality for a range of configurations. Neoclassical effects, which are not included in the PIES calculations, are estimated using a cylindrical model and are found to further reduce island widths significantly.

AbstractWe have identified and developed new classes of quasi-axially symmetric configurations that have attractive properties from the standpoint of both near-term physics experiments and long-term power-producing reactors. These include configurations with very small aspect ratios (~2.5) having superior quasi-symmetry and energetic particle confinement characteristics, and configurations with strongly negative global magnetic shear from the shaping fields so that the overall rotational transform, when combined with the transform from bootstrap currents at finite plasma pressures, will have a small but positive shear, making the avoidance of low-order rational surfaces at a given operating beta possible. Additionally, we have found configurations with National Compact Stellarator Experiment–like characteristics but with the biased components in the magnetic spectrum that allow us to improve the confinement of energetic particles. For each new class of configurations, we have also designed coils to ensure that the new configurations are realizable and engineering-wise feasible. The coil designs typically have the properties of R/Δmin(C-P) < 6 and R/Δmin(C-C) < 10, where Ris the plasma major radius and Δmin(C-P) and Δmin(C-C) are the minimum coil-to-plasma and coil-to-coil separations, respectively. These coil properties allow power-producing reactors to be designed with R< 9 m for deuterium-tritium plasmas with a full breeding blanket. The good quasi-axisymmetry limits the energy loss of alpha particles to below 10%.

AbstractIt is widely recognized among stellarator researchers that the minimum distance between the plasma boundary and the middle of the coil (Δmin) is of great importance for stellarators as it impacts the machine parameters considerably. Techniques for minimizing the radial build have made impressive progress during the first year of the ARIES-CS study. A novel approach has been developed for ARIES-CS where the blanket at the critical area surrounding Δminhas been replaced by a highly efficient WC-based shield. As a result, an appreciable 20-90 cm savings in the radial build has been achieved, reducing the major radius by more than 20%, which is significant. The economic benefit of this approach is yet to be determined and the added engineering problems and complexity will be addressed during the remaining period of the study. This paper covers the details of the radial build optimization process that contributed to the compactness of ARIES-CS. Compared with previous designs, the major radius of ARIES-CS has more than halved, dropping from 24 m to less than 10 m, making a step forward toward the feasibility of a compact stellarator power plant.

AbstractFour quasi-axisymmetric compact stellarator plasma and coil configurations are analyzed for their potential as reactors. A 0-D (volume-average) approach for optimizing the main reactor parameters allows study of the relationship between global parameters and the compatibility of different constraints for a given power output including plasma-coil spacing, coil-coil spacing, maximum field and coil current density, neutron wall loading, plasma beta value, etc. The result is reactor candidates with average major radii in the 6-7 m range, a factor of two smaller than those of previous studies. A 1-D power balance code is used to study the ignited operating point and the effect of different plasma and confinement assumptions including density and temperature profiles, alpha particle losses, and helium particle confinement time for the different plasma and coil configurations.

Princeton Plasma Physics Laboratory, in collaboration with the Naval Research Laboratory, is currently investigating various novel materials (single-crystal silicon, 〈100〉, 〈110〉, and 〈111〉) for use as electron beam transmission windows in a krypton fluoride (KrF) excimer laser system. The primary function of the window is to isolate the active medium (excimer gas) from the excitation mechanism (field-emission diodes). The chosen window geometry must accommodate electron energy transfer >80% (750 keV) while maintaining the structural integrity during the mechanical load (1.3- to 2.0-atm base pressure differential, ~0.5-atm cyclic pressure amplitude, 5-Hz repetition rate) and the thermal load across the entire hibachi area (~0.9 W⋅cm−2). In addition, the window must be chemically resistant to attack by fluorine free radicals (hydrofluoric acid, secondary). In accordance with these structural, functional, and operational parameters, a 22.4-mm square silicon prototype window, coated with 500-nm thin-film silicon nitride (Si3N4), has been fabricated. The window consists of 81 square panes 0.019 ± 0.001 mm thick. The stiffened (orthogonal) sections are 0.065 mm wide and 0.500 mm thick (approximate). Assessment of silicon (and silicon nitride) material properties and computer-aided design modeling/analysis of the window design suggest that silicon may be a viable solution to inherent parameters and constraints.

In current-free stellarators, the parallel current density is normally too weak to drive global external kink modes. However, at finite values of β, the bootstrap current (BC) can provide sufficient free energy to trigger this class of mode in some stellarator systems. The effect of the BC in the collisionless 1/ν regime has been investigated in several different types of stellarator reactor systems all with a volume V~1000 m³. In quasiaxisymmetric and quasihelically symmetric stellarators, the BC is large at finite β and this can cause low order resonances to move into and emerge out of the plasma which in turn can destabilize global internal and external kink modes. In a six-field period system with poloidally closed contours of the magnetic field strength B, the BC is small and decreases the rotational transform only slightly. As a result, only intermediate to high n modes can become weakly destabilized. Furthermore, it is demonstrated in this system that the contours of the second adiabatic invariant &calJ;_&Vert; close poloidally for all trapped particles at finite β*~6&percent;. This condition leads to the loss of a very small fraction of the collisionless α-particle orbits. In Sphellamak configurations with peaked toroidal currents required to generate nearly isodynamic maximum-B confining field structures, the BC accounts only for a small fraction of the total current. The loss of α-particles born within the inner quarter of the plasma volume is negligible while about (1/3) of those born at half volume escape the device within a slowing down time.

Fully kinetic assessments of the stability properties of toroidal drift modes have been obtained for cases for the large helical device (LHD). This calculation employs the comprehensive linear microinstability code FULL, as recently extended for nonaxisymmetric systems. The code retains the important effects in the linearized gyrokinetic equation, using the lowest-order `ballooning representation' for high toroidal mode number instabilities in the electrostatic limit. These effects include trapped particles, FLR, transit and bounce and magnetic drift frequency resonances, etc. for any number of plasma species. Results for toroidal drift waves destabilized by trapped electrons and ion temperature gradients are presented, using numerically-calculated three-dimensional MHD equilibria. These are reconstructed from experimental measurements. Quasilinear fluxes of particles and energy for each species are also calculated. Pairs of LHD discharges with different magnetic axis positions and with and without pellet injection are compared. The properties of the calculated linearly unstable modes are compared with the experimentally observed anomalous transport.

Compact optimized stellarators offer novel solutions for confining high-β plasmas and developing magnetic confinement fusion. The three-dimensional plasma shape can be designed to enhance the magnetohydrodynamic (MHD) stability without feedback or nearby conducting structures and provide drift-orbit confinement similar to tokamaks. These configurations offer the possibility of combining the steady-state low-recirculating power, external control, and disruption resilience of previous stellarators with the low aspect ratio, high β limit, and good confinement of advanced tokamaks. Quasi-axisymmetric equilibria have been developed for the proposed National Compact Stellarator Experiment (NCSX) with average aspect ratio 4-4.4 and average elongation ~1.8. Even with bootstrap-current consistent profiles, they are passively stable to the ballooning, kink, vertical, Mercier, and neoclassical-tearing modes for β>4%, without the need for external feedback or conducting walls. The bootstrap current generates only 1/4 of the magnetic rotational transform at β = 4% (the rest is from the coils); thus the equilibrium is much less non-linear and is more controllable than similar advanced tokamaks. The enhanced stability is a result of `reversed' global shear, the spatial distribution of local shear, and the large fraction of externally generated transform. Transport simulations show adequate fast-ion confinement and thermal neoclassical transport similar to equivalent tokamaks. Modular coils have been designed which reproduce the physics properties, provide good flux surfaces, and allow flexible variation of the plasma shape to control the predicted MHD stability and transport properties.

The biochemical basis for the therapeutic effects of thiamin in thiamin-responsive maple-syrup-urine disease (MSUD) was investigated in intact and disrupted fibroblast cultures from normals and patients with various forms of MSUD. Decarboxylation of alpha-keto[1-14C]isovalerate (KIV) by intact cells from a thiamin-responsive MSUD patient was at 30-40% of the normal rate with or without thiamin in the incubation medium. Under similar conditions, intact classical MSUD fibroblasts failed to decarboxylate KIV. Branched-chain alpha-keto acid (BCKA) dehydrogenase activity measured in disrupted cells from the thiamin-responsive subject showed sigmoidal kinetics in the absence of thiamin pyrophosphate (TPP), with an increased concentration of substrate needed for half-maximal velocity (K0.5 for KIV = 7 mM vs. 0.05 mM in normal cells). When assayed with 0.2 mM TPP present, the mutant enzyme showed (i) a shift in kinetics to near Michaelis-Menten type as observed with the normal BCKA dehydrogenase and (ii) a lower K0.5 value of 4 mM for KIV, suggesting a TPP-mediated increase in the mutant enzyme's affinity for substrate. By contrast, TPP increased only the Vmax and was without effect on the apparent Km for KIV of the BCKA dehydrogenase from cells of normals and patients with classical MSUD and variant thiamin-responsive MSUD (grade 3). Measurement of the apparent Km for TPP of the BCKA dehydrogenase from thiamin-responsive mutant MSUd cells showed a 16-fold increase in the constant to 25 microM compared to enzymes from normal or classical MSUD cells. These findings demonstrate that the primary defect in the thiamin-responsive MSUD patient is a reduced affinity of the mutant BCKA dehydrogenase for TPP that results in impaired oxidative decarboxylation of BCKA.

Branched-chain alpha-keto acid dehydrogenase is a multienzyme complex consisting of three catalytic components, i.e. branched-chain alpha-keto acid decarboxylase (E1), dihydrolipoyl transacylase (E2), and dihydrolipoyl dehydrogenase (E3). In this report the E2 component of highly purified branched-chain alpha-keto acid dehydrogenase from bovine kidney and liver was characterized with an independent radiochemical assay for this component. The assay uses the model reaction: R-14CO-S-CoA + Lip-(SH)2 in equilibrium R-14CO-S-Lip-SH + CoA-SH, which is similar to that catalyzed by the transacetylase component of the pyruvate dehydrogenase complex. In this reaction, exogenous dihydrolipoamide substitutes for the protein (E2)-bound dihydrolipoyl moiety, and [1-14C]acyl-CoA synthesized enzymatically is the acyl-CoA substrate. The thioester structure of the reaction product, S-acyldihydrolipoamide, was identified by mass spectrometry, its characteristic absorption at 232-245 nm and by formation of hydroxamate with hydroxylamine. Rates of the E2-catalyzed transacylation reaction with various [1-14C]acyl-CoAs are in the order of [1-14C]isobutyryl-CoA greater than [1-14C] isovaleryl-CoA greater than [1-14C]acetyl-CoA. The activity with acetyl-CoA is 15% of that with isobutyryl-CoA. The E2 activity is strongly inhibited by arsenite. Modification of the covalently bound lipoyl moiety through reductive acylation in the presence of N-ethylmaleimide is without effect on the transacylation reaction. These data, along with results of initial velocity and product inhibition suggest that the model reaction proceeds via a random Bi Bi mechanism. Limited proteolysis of purified bovine liver branched-chain alpha-keto acid dehydrogenase with trypsin results in complete loss of the overall activity catalyzed by the complex. Nonetheless the activity of the E2 component is not affected. The tryptic digestion cleaves E2 subunits (Mr = 52,600) into a major fragment of Mr = 25,700. By contrast, E1 alpha and E1 beta subunits of the complex are relatively resistant to proteolysis with trypsin. The results indicate that structural properties of the E2 component of branched-chain alpha-keto acid dehydrogenase are similar but not identical to those of the transacetylase component of the pyruvate dehydrogenase complex.

Limited proteolysis has been used to probe the subunit structure (Mr = 52,000) of the dihydrolipoyl transacylase (E2) component of the branched-chain alpha-keto acid dehydrogenase complex from bovine liver. Digestion of the complex at 0 degrees C with a low concentration of trypsin produces an inner E2 core that retains the activity for the transacylation reaction and is completely dissociated from the decarboxylase (E1) component. The trypsinized E2 maintains the highly assembled structure and migrates faster than the native E2 in the Sepharose 4B column. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis shows that the inner E2 core consists of two lipoate-free tryptic fragments, i.e. fragment A and fragment B with Mr = 26,000 and 22,000, respectively. Both fragments apparently fail to bind the E1 component. Fragment A is converted into fragment B by increasing trypsin concentrations. Fragment B is a stable limit polypeptide containing the intersubunit-binding sites for E2. The assemblage of fragment B confers the cubelike appearance of the inner E2 core in electron micrographs. Activity measurements indicate that the larger fragment A, but not fragment B, possesses transacylation activity. It is likely that a critical portion of the active site is present in the 4,000-dalton fragment that is lost during the conversion of fragment A to B.

The authors consider the optimum partitioning problem defined as follows: given a rectilinear layout L consisting of n rectangles, it is desirable to partition (decompose) the remaining free space into rectangular free blocks using horizontal and/or vertical partition edges such that the number of free blocks is minimised. The authors give a new formula for counting the number of free blocks in any partition of a given layout. Based on the new formula, they show that the optimum partitioning problem reduces to the problem of finding a maximum independent vertex set (MIS) in a bipartite graph. They then give an O(n2.5) optimum partitioning algorithm (OPA) for computing an optimum partition. This optimum partitioning algorithm can be used to improve the space and time complexities of many applications where space partitioning is encountered. One example is the corner stitching data structure used for design rule checker (DRC) in the layout system Magic. In the experiments, the space complexity of the corner stitching data structure can be improved by an average of 13% by using the proposed optimum partitioning. Other applications are also presented.

We have recently shown that insulin-like growth factor I (IGF I) is a mediator of angiotensin II-induced mitogenesis in vascular smooth muscle cells (Delafontaine, P., and Lou H. (1993) J. Biol. Chem. 268, 16866-16870). To study the role of the IGF I receptor in vascular smooth muscle cell growth, phosphorothioate oligonucleotides were used to modulate IGF I receptors. An antisense oligonucleotide targeting the ATG site inhibited basal and serum-induced DNA synthesis in vascular smooth muscle cells. Mismatch oligonucleotide had no effect, while surprisingly sense oligonucleotide increased IGF I receptor number and basal and serum-induced DNA synthesis. A 51% reduction in IGF I receptor number following exposure to 5 microM antisense oligonucleotide markedly inhibited angiotensin II-induced mitogenesis. A 70% increase in IGF I receptor number following exposure to 5 microM sense oligonucleotide resulted in a 4-fold increase in basal [3H]thymidine incorporation, and angiotensin II (1-1000 nM) had no additive stimulatory effect. An antisense oligonucleotide targeting a sequence starting at +109 base pairs (relative to ATG) also reduced IGF I receptor number, however, the corresponding sense oligonucleotide was without effect. These findings demonstrate that alterations in vascular smooth muscle cell IGF I receptor density play a critical role in the proliferative response of vascular smooth muscle cells to serum and to angiotensin II. In addition, the surprising observation that an ATG-directed sense oligonucleotide up-regulates IGF I receptors identifies a novel effect of oligonucleotides on gene expression.

An OTP algorithm for solving the optimal tile-partitioning problem has recently been published. The OTP algorithm makes use of an elimination algorithm to find a maximum set of nonintersecting critical partition edges. It is shown that this elimination algorithm is flawed.