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Excluding Any Graph As A Minor Allows A Low Tree-Width 2-Coloring, Matt Devos, Guoli Ding, Bogdan Oporowski, Daniel P. Sanders, Bruce Reed, Paul Seymour, Dirk Vertigan Jan 2004

Excluding Any Graph As A Minor Allows A Low Tree-Width 2-Coloring, Matt Devos, Guoli Ding, Bogdan Oporowski, Daniel P. Sanders, Bruce Reed, Paul Seymour, Dirk Vertigan

Faculty Publications

This article proves the conjecture of Thomas that, for every graph G, there is an integer k such that every graph with no minor isomorphic to G has a 2-coloring of either its vertices or its edges where each color induces a graph of tree-width at most k. Some generalizations are also proved. © 2003 Elsevier Inc. All rights reserved.

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Multiplicative Renormalization And Generating Functions Ii, Nobuhiro Asai, Izumi Kubo, Hui Hsiung Kuo Jan 2004

Multiplicative Renormalization And Generating Functions Ii, Nobuhiro Asai, Izumi Kubo, Hui Hsiung Kuo

Faculty Publications

Let μ be a probability measure on the real line with finite moments of all orders. Suppose the linear span of polynomials is dense in L 2(μ). Then there exists a sequence {Pn} n=0∞ orthogonal polynomials with respect to μ such that Pn is a polynomial of degree n with leading coefficient 1 and the equality (x -αn)Pn(x) = Pn+1(x) + wnPn-1(x) holds, where αn and w n are Szegö-Jacobi parameters. In this paper we use the concepts of pre-generating function, multiplicative renormalization, and generating function to derive {Pn,αn,wn} from a given μ Two types of pre-generating functions are studied. …

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Seiberg-Witten Vanishing Theorem For S1-Manifolds With Fixed Points, Scott Baldridge Jan 2004

Seiberg-Witten Vanishing Theorem For S1-Manifolds With Fixed Points, Scott Baldridge

Faculty Publications

We show that the Seiberg-Witten invariant is zero for all smooth 4-manifolds with b >1 that admit circle actions having at least one fixed point. We also show that all symplectic 4-manifolds that admit (possibly nonsymplectic) circle actions with fixed points are rational or ruled, and thus admit a symplectic circle action. +

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The Structure Of The 3-Separations Of 3-Connected Matroids, James Oxley, Charles Semple, Geoff Whittle Jan 2004

The Structure Of The 3-Separations Of 3-Connected Matroids, James Oxley, Charles Semple, Geoff Whittle

Faculty Publications

Tutte defined a k-separation of a matroid M to be a partition (A,B) of the ground set of M such that A , B ≥k and r(A)+r(B)-r(M)

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Fork-Decompositions Of Matroids, Rhiannon Hall, James Oxley, Charles Semple, Geoff Whittle Jan 2004

Fork-Decompositions Of Matroids, Rhiannon Hall, James Oxley, Charles Semple, Geoff Whittle

Faculty Publications

One of the central problems in matroid theory is Rota's conjecture that, for all prime powers q, the class of GF(q)-representable matroids has a finite set of excluded minors. This conjecture has been settled for q ≤ 4 but remains open otherwise. Further progress towards this conjecture has been hindered by the fact that, for all q ≥ 5, there are 3-connected GF(q)-representable matroids having arbitrarily many inequivalent GF(q)-representations. This fact refutes a 1988 conjecture of Kahn that 3-connectivity would be strong enough to ensure an absolute bound on the number of such inequivalent representations. This paper introduces fork-connectivity, a …

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A Short Proof Of Non-Gf(5)-Representability Of Matroids, Jim Geelen, James Oxley, Dirk Vertigan, Geoff Whittle Jan 2004

A Short Proof Of Non-Gf(5)-Representability Of Matroids, Jim Geelen, James Oxley, Dirk Vertigan, Geoff Whittle

Faculty Publications

Tutte proved that a matroid is binary if and only if it does not contain a U2,4-minor. This provides a short proof for non-GF(2)-representability in that we can verify that a given minor is isomorphic to U2,4 in just a few rank evaluations. Using excluded-minor characterizations, short proofs can also be given of non-representablity over GF(3) and over GF(4). For GF(5), it is not even known whether the set of excluded minors is finite. Nevertheless, we show here that if a matroid is not representable over GF(5), then this can be verified by a short proof. Here a "short proof" …

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Homogeneous Multivariate Polynomials With The Half-Plane Property, Young Bin Choe, James G. Oxley, Alan D. Sokal, David G. Wagner Jan 2004

Homogeneous Multivariate Polynomials With The Half-Plane Property, Young Bin Choe, James G. Oxley, Alan D. Sokal, David G. Wagner

Faculty Publications

A polynomial P in n complex variables is said to have the "half-plane property" (or Hurwitz property) if it is nonvanishing whenever all the variables lie in the open right half-plane. Such polynomials arise in combinatorics, reliability theory, electrical circuit theory and statistical mechanics. A particularly important case is when the polynomial is homogeneous and multiaffine: then it is the (weighted) generating polynomial of an r-uniform set system. We prove that the support (set of nonzero coefficients) of a homogeneous multiaffine polynomial with the half-plane property is necessarily the set of bases of a matroid. Conversely, we ask: For which …

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Bounded-From-Below Solutions Of The Hamilton-Jacobi Equation For Optimal Control Problems With Exit Times: Vanishing Lagrangians, Eikonal Equations, And Shape-From-Shading, Michael Malisoff Jan 2004

Bounded-From-Below Solutions Of The Hamilton-Jacobi Equation For Optimal Control Problems With Exit Times: Vanishing Lagrangians, Eikonal Equations, And Shape-From-Shading, Michael Malisoff

Faculty Publications

We study the Hamilton-Jacobi equation for undiscounted exit time control problems with general nonnegative Lagrangians using the dynamic programming approach. We prove theorems characterizing the value function as the unique bounded-from-below viscosity solution of the Hamilton-Jacobi equation that is null on the target. The result applies to problems with the property that all trajectories satisfying a certain integral condition must stay in a bounded set. We allow problems for which the Lagrangian is not uniformly bounded below by positive constants, in which the hypotheses of the known uniqueness results for Hamilton-Jacobi equations are not satisfied. We apply our theorems to …

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Comment On "Quantum Measurement And Decoherence", D. Gobert, J. Von Delft, V. Ambegaokar, R. F. O'Connell, G. W. Ford Jan 2004

Comment On "Quantum Measurement And Decoherence", D. Gobert, J. Von Delft, V. Ambegaokar, R. F. O'Connell, G. W. Ford

Faculty Publications

No abstract provided.

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Canonical Quantum Gravity And Consistent Discretizations, Rodolfo Gambini, Jorge Pullin Jan 2004

Canonical Quantum Gravity And Consistent Discretizations, Rodolfo Gambini, Jorge Pullin

Faculty Publications

This paper covers some developments in canonical quantum gravity that occurred since ICGC-2000, emphasizing the recently introduced consistent discretizations of general relativity.

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An Existence Theorem For Neutral Variational Problems Of Bolza, Norma L. Ortiz, Peter R. Wolenski Jan 2004

An Existence Theorem For Neutral Variational Problems Of Bolza, Norma L. Ortiz, Peter R. Wolenski

Faculty Publications

This note proves an existence theorem for a generalized Bolza-type problem that has time delays in both the state and velocity variables. The assumptions are stated in terms of a modification of the classical Hamiltonian, and extend ideas of Rockafellar to the delay case. © 2003 Elsevier Inc. All rights reserved.

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An Inequality Among Equals: Disparities In The Judicial Treatment Of Free Speech And Religious Exercise Claims, Patrick Garry Jan 2004

An Inequality Among Equals: Disparities In The Judicial Treatment Of Free Speech And Religious Exercise Claims, Patrick Garry

Faculty Publications

The constitutional models governing the religion clauses of the First Amendment have undergone significant transformations. These transformations have sought to bring a greater consistency and historical harmony to the Court's religious liberty decisions. The success of this endeavor can be gauged in part by comparing the judicial treatment of religion clause claims with free speech claims. However, such a comparison reveals that the former occupy a lower constitutional status than do the latter.

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What Do You Mean, Rhetoric Is Epistemic?, William D. Harpine Jan 2004

What Do You Mean, Rhetoric Is Epistemic?, William D. Harpine

Faculty Publications

The thesis that rhetoric is epistemic has gained widespread acceptance and has influenced rhetorical theory. The thesis suggests that argumentative justification in rhetorical contexts is fundamentally epistemic. Unfortunately, however, much of the literature developing the thesis has employed vague or inconsistent definitions of key terms, resulting in theoretical errors and needless complications. This essay clarifies the definitions of “rhetoric,” “knowledge,” and “certainty,” showing how the notion that rhetoric is epistemic might be developed in a clearer and more useful way.

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Termination-Dependent Diversity Performance Of Coupled Antennas: Network Theory Analysis, Michael A. Jensen, Jon W. Wallace Jan 2004

Termination-Dependent Diversity Performance Of Coupled Antennas: Network Theory Analysis, Michael A. Jensen, Jon W. Wallace

Faculty Publications

A new analysis of mutually coupled diversity antenna systems is presented that includes the effects of coupling on the radiation pattern and received power. This analysis, based upon the network scattering parameters, makes use of the singular value decomposition to both specify the characteristics of and analyze terminated antenna networks. The approach facilitates a simplified proof of the multiport conjugate matching condition as well as development of expressions for diversity performance as a function of various impedance terminations. Application of the analysis to coupled dipole antennas characterized using full-wave electromagnetic analysis leads to a comprehensive examination of the diversity performance …

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Effect Of Porosity On The Capacity Fade Of A Lithium-Ion Battery: Theory, Godfrey Sikha, Branko N. Popov, Ralph E. White Jan 2004

Effect Of Porosity On The Capacity Fade Of A Lithium-Ion Battery: Theory, Godfrey Sikha, Branko N. Popov, Ralph E. White

Faculty Publications

A mathematical model is presented to predict the performance of a lithium-ion battery. It includes the changes in the porosity of the material due to the reversible intercalation processes and the irreversible parasitic reaction. The model was also extended to predict the capacity fade in a lithium-ion battery based on the unwanted parasitic reaction that consumes Li+ along with the changes in the porosities of the electrodes with cycling due to the continuous parasitic side reaction. The model can be used to predict the drop in the voltage profile, change in the state of charge, and the effects of …

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Content Analysis Of The Leading General Academic Databases, Kelly D. Blessinger, Maureen Olle-Lajoie Jan 2004

Content Analysis Of The Leading General Academic Databases, Kelly D. Blessinger, Maureen Olle-Lajoie

Faculty Publications

Title lists from the three leading general academic databases were compared to evaluate journal content. Some of the elements that were analyzed include subject coverage, the quality of titles provided, accessibility issues, and trends over time for these databases. While database title lists are now readily available on the Internet for comparison, as our article illustrates, these lists need further evaluation for proper assessment.

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Superior 5' Homogeneity Of Rna From Atp-Initiated Transcription Under The T7 Φ2.5 Promoter, Tricia M. Coleman, Guocan Wang, Faqing Huang Jan 2004

Superior 5' Homogeneity Of Rna From Atp-Initiated Transcription Under The T7 Φ2.5 Promoter, Tricia M. Coleman, Guocan Wang, Faqing Huang

Faculty Publications

Transcription from the commonly used GTP- initiating T7 class III promoter phi6.5 frequently produces heterogeneous RNA at both 3' and 5' ends. We demonstrate here that RNA transcripts from the T7 class II promoter phi2.5 have superior 5' homogeneity over those from the phi6.5 promoter, with comparable total RNA yields. The overall homogeneity of RNA transcripts is improved to different degrees depending on RNA sequences, although transcription under phi2.5 does not affect the 3' heterogeneity of RNA. In combination with 3' RNA trimming by DNAzymes or ribozymes, this ATP- initiated transcription system based on the T7 phi2.5 promoter can provide …

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Numerical Solution Of Fractional Advection-Dispersion Equation, Zhi Qiang Deng, Vijay P. Singh, Lars Bengtsson Jan 2004

Numerical Solution Of Fractional Advection-Dispersion Equation, Zhi Qiang Deng, Vijay P. Singh, Lars Bengtsson

Faculty Publications

Numerical schemes and stability criteria are developed for solution of the one-dimensional fractional advection-dispersion equation (FRADE) derived by revising Fick's first law. Employing 74 sets of dye test data measured on natural streams, it is found that the fractional order F of the partial differential operator acting on the dispersion term varies around the most frequently occurring value of F=1.65 in the range of 1.4 to 2.0. Two series expansions are proposed for approximation of the limit definitions of fractional derivatives. On this ground, two three-term finite-difference schemes - "1.3 Backward Scheme"having the first-order accuracy and "F.3 Central Scheme"possessing the …

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Diel Activity Patterns Of The Louisiana Pine Snakes (Pituophis Ruthveni) In Eastern Texas, Marc J. Ealy, Robert R. Fleet, D. Craig Rudolph Jan 2004

Diel Activity Patterns Of The Louisiana Pine Snakes (Pituophis Ruthveni) In Eastern Texas, Marc J. Ealy, Robert R. Fleet, D. Craig Rudolph

Faculty Publications

This study examined the diel activity patterns of six Louisiana pine snakes in eastern Texas using radio-telemetry. snakes were monitored for 44 days on two study areas from May to October 1996. Louisana pine snakes were primarily diurnal with moderate crepuscular activity, spending the night within pocket gopher burrows or inactive on the surface. During daylight hours, snakes spent approximately 59% of their time underground within gopher burrows, burned out/rotten stumps, or nine-branded armadillo (Dasypus novemcinctus) burrows. Remaining time was spent on the surface either close to subteranean refuge, or in long distance movements that generally terminet at …

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Taking Back The Law School Classroom: Using Technology To Foster Active Student Learning , Rafael Gely, Paul L. Caron Jan 2004

Taking Back The Law School Classroom: Using Technology To Foster Active Student Learning , Rafael Gely, Paul L. Caron

Faculty Publications

Law schools (and indeed all of higher education) have witnessed an explosive growth in the use of technology in the classroom. Many law teachers now deploy a wide array of technological bells and whistles, including PowerPoint slides, Web-based course platforms, in-class Internet access, and the like. Students, in turn, increasingly come to class armed with laptop computers to harvest the fruits of the classroom experience. Yet in recent years there has been something of a backlash, with various law teachers arguing that this technology is interfering with, rather than improving, pedagogy in the classroom. According to the critics, the technology …

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Microstructure Design Of A Two Phase Composite Using Two-Point Correlation Functions, Brent L. Adams, H. Garmestani, G. Saheli Jan 2004

Microstructure Design Of A Two Phase Composite Using Two-Point Correlation Functions, Brent L. Adams, H. Garmestani, G. Saheli

Faculty Publications

This work has been funded under the AFOSR Grant no. F49620-03-1-0011 and Army Research Lab contract no. DAAD17-02-P-0398 and DAAD 19-01-1-0742. Two-point distribution functions are used here as to introduce "Microstructure Sensitive Design" in two-phase composites. Statistical distribution functions are commonly used for the representation of microstructures and also for homogenization of materials properties. The use of two-point statistics allows the composite designer to include the morphology and distribution in addition to the properties of the individual phases and components. Statistical continuum mechanics is used to make a direct link between the microstructure and properties (elastic and plastic) in terms …

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Resolving Automatic Prepositional Phrase Attachments By Non-Statistical Means, Deryle W. Lonsdale, Michael B. Manookin Jan 2004

Resolving Automatic Prepositional Phrase Attachments By Non-Statistical Means, Deryle W. Lonsdale, Michael B. Manookin

Faculty Publications

Prepositional-phrase attachment is a topic of active research in the field of computational linguistics. Properly attaching prepositional phrases to their pertinent constituent proves straightforward for humans, but inferring these attachments in a cognitive modeling system becomes difficult. For example, in the sentence, ‘Ralph threw the frisbee to John,’ the prepositional phrase ‘to John’ will attach to the verb phrase ‘threw’. In another example, ‘Joe saw the dog with fur,’ the prepositional phrase ‘with fur’ will attach directly to the noun phrase ‘the dog.’ Humans would have little difficulty resolving these examples, but for computers this would be difficult.

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Effects Of Low Tide Rainfall On Intertidal Zone Material Cycling, Raymond Torres, Miguel A. Goni, George Voulgaris, Charles R. Lovell, James T. Morris Jan 2004

Effects Of Low Tide Rainfall On Intertidal Zone Material Cycling, Raymond Torres, Miguel A. Goni, George Voulgaris, Charles R. Lovell, James T. Morris

Faculty Publications

Sediment transport by rainfall-runoff processes is well documented for terrestrial landscapes but few studies have focused on rainfall-runoff effects in intertidal areas. Here we present geochemical analyses performed on sediment samples collected during low tide irrigation experiments, and tidal channel turbidity measurements taken during natural rainfall over North Inlet Marsh, South Carolina. Order of magnitude approximations indicate that a single 10 minute storm may entrain 8-15% of the local annual average sediment accumulation. This rainfall-entrained material is enriched in organic nitrogen and marine algal matter, and therefore of high nutritional quality.

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Series Solution To The Transient Convective Diffusion Equation For A Rotating Disk Electrode, Shiriram Santhanagopalan, Ralph E. White Jan 2004

Series Solution To The Transient Convective Diffusion Equation For A Rotating Disk Electrode, Shiriram Santhanagopalan, Ralph E. White

Faculty Publications

A series solution to the transient convective diffusion equation for the rotating disc electrode system is presented and compared to previously reported solutions. The solution presented here is for the entire time domain and agrees well with both the short and long time solutions presented earlier in the literature.

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Analytical Solution For The Impedance Of A Porous Electrode, Sheba Devan, Venkat R. Subramanian, Ralph E. White Jan 2004

Analytical Solution For The Impedance Of A Porous Electrode, Sheba Devan, Venkat R. Subramanian, Ralph E. White

Faculty Publications

A macrohomogeneous model is presented for a porous electrode that includes coupled potential and concentration gradients with linear kinetics. The equations are solved to obtain an analytical expression for the impedance of a porous electrode. Complex plane plots are presented that illustrate two well-defined arcs: a kinetic arc and a diffusion arc with their time constants far apart. The effects of parameters such as exchange current density, porosity, diffusion coefficient, thickness, and interfacial area on the impedance spectra are presented. The usefulness of the analytical solution in investigating the effect of solution phase diffusion is also presented.

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A Steady-State Impedance Model For A Pemfc Cathode, Qingzhi Guo, Ralph E. White Jan 2004

A Steady-State Impedance Model For A Pemfc Cathode, Qingzhi Guo, Ralph E. White

Faculty Publications

A model for the simulation of the steady-state impedance response of a polymer electrolyte membrane fuel cell (PEMFC) cathode is presented. The catalyst layer of the electrode is assumed to consist of many flooded spherical agglomerate particles surrounded by a small volume fraction of gas pores. Stefan-Maxwell equations are used to describe the multicomponent gas-phase transport occurring in both the gas diffusion layer and the catalyst layer of the electrode. Liquid-phase diffusion of O2 is assumed to take place in the flooded agglomerate particles. Newman’s porous electrode theory is applied to determine over-potential distributions. © 2004 The Electrochemical Society. All …

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Employee Stock Purchase Plans, Gary V. Engelhardt, Brigitte C. Madrian Jan 2004

Employee Stock Purchase Plans, Gary V. Engelhardt, Brigitte C. Madrian

Faculty Publications

Employee stock purchase plans (ESPPs) are designed to promote employee stock ownership broadly within the firm and provide another tax-deferred vehicle for individual capital accumulation in addition to traditional pensions, 401(k)s, and stock options. We outline the individual and corporate tax treatment of ESPPs and the circumstances under which ESPPs will be preferred to cash compensation from a purely tax perspective. We then examine empirically ESPP participation using administrative data from 1997-2001 for a large health services company that employs approximately 30,000 people. The picture that emerges from the analysis of these data suggests that there is substantial non-participation in …

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Rectification Of Thermal Fluctuations In Ideal Gases, Alejandro Garcia, P. Meurs, C. Van De Broeck Jan 2004

Rectification Of Thermal Fluctuations In Ideal Gases, Alejandro Garcia, P. Meurs, C. Van De Broeck

Faculty Publications

We calculate the systematic average speed of the adiabatic piston and a thermal Brownian motor, introduced by C. Van den Broeck, R. Kawai and P. Meurs [Phys. Rev. Lett. 93, 090601 (2004)], by an expansion of the Boltzmann equation and compare with the exact numerical solution.

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A Computational Approach To Resolving Certain Issues In Spanish Stress Placement, David Eddington Jan 2004

A Computational Approach To Resolving Certain Issues In Spanish Stress Placement, David Eddington

Faculty Publications

Previous research into Spanish stress assignment suggests that accentuation involves learning and storing individual word tokens along with their inherent stress patterns, and analogizing on stored words when the need arises to determine the stress pattern of an unknown or unavailable word. Exactly what variables are most relevant to stress assignment has been hotly debated. In the present study, a number of analogical simulations were carried out to determine whether elements of the CV tier, syllable weight, phonemic representation, or a combination of these, best accounts for accentuation in Spanish.

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Digital Mountain: From Granite Archive To Global Access, William A. Barrett, Luke A. D. Hutchison, Douglas J. Kennard, Heath E. Nielson, Dallan Quass Jan 2004

Digital Mountain: From Granite Archive To Global Access, William A. Barrett, Luke A. D. Hutchison, Douglas J. Kennard, Heath E. Nielson, Dallan Quass

Faculty Publications

Large-scale, multi-terabyte digital libraries are becoming feasible due to decreasing costs of storage, CPU, and bandwidth. However, costs associated with preparing content for input into the library remain high due to the amount of human labor required. This paper describes the Digital Microfilm Pipeline – a sequence of image processing operations used to populate a large-scale digital library from a “mountain” of microfilm and reduce the human labor involved. Essential parts of the pipeline include algorithms for document zoning and labeling, consensus-based template creation, reversal of geometric transformations and Just-In-Time Browsing, an interactive technique for progressive access of image content …

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