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Algebraic elimination of nodes at discrete fracture intersections via the star-delta technique has proven to be a valuable tool for making multiphase numerical simulations more tractable and efficient. This study examines the assumptions of the star-delta technique and exposes its effects in a 3-D, multiphase context for advective and dispersive/diffusive fluxes. Key issues of relative permeability-saturation-capillary pressure ( kr-S-Pc) and capillary barriers at fracture-fracture intersections are discussed. This study uses a multiphase compositional, finite difference numerical model in discrete fracture network (DFN) and discrete fracture-matrix (DFM) modes. It verifies that the numerical model replicates analytical solutions and performs adequately in convergence exercises (conservative and decaying tracer, one and two-phase flow, DFM and DFN domains). The study culminates in simulations of a two-phase laboratory experiment in which a fluid invades a simple fracture intersection. The experiment and simulations evoke different invading fluid flow paths by varying fracture apertures as oil invades water-filled fractures and as water invades air-filled fractures. Results indicate that the node elimination technique as implemented in numerical model correctly reproduces the long-term flow path of the invading fluid, but that short-term temporal effects of the capillary traps and barriers arising from the intersection node are lost. [ABSTRACT FROM AUTHOR]

We study a class of homotopies between maps from 4-manifolds to surfaces which we call cusp merges. These homotopies naturally appear in the uniqueness problems for certain pictorial descriptions of 4-manifolds derived from maps to the 2-sphere (for example, broken Lefschetz fibrations, wrinkled fibrations, or Morse 2-functions). Our main results provide a classification of cusp merge homotopies in terms of suitably framed curves in the source manifold, as well as a fairly explicit description of a parallel transport diffeomorphism associated to a cusp merge homotopy. The latter is the key ingredient in understanding how the aforementioned pictorial descriptions change under homotopies involving cusp merges. We apply our methods to the uniqueness problem of surface diagrams of 4-manifolds and describe algorithms to obtain surface diagrams for total spaces of (achiral) Lefschetz fibrations and 4-manifolds of the form M × S1, where M is a 3-manifold. Along the way we provide extensive background material about maps to surfaces and homotopies thereof and develop a theory of parallel transport that generalizes the use of gradient flows in Morse theory [ABSTRACT FROM AUTHOR]

We present a Poisson formula for sparse resultants and a formula for the product of the roots of a family of Laurent polynomials, which are valid for arbitrary families of supports. To obtain these formulae, we show that the sparse resultant associated to a family of supports can be identified with the resultant of a suitable multiprojective toric cycle in the sense of R'emond. This connection allows to study sparse resultants using multiprojective elimination theory and intersection theory of toric varieties. [ABSTRACT FROM AUTHOR]

ABSTRACT A compact I-shaped λ/2 resonator is introduced in order to reduce the mutual coupling between antenna elements and eliminate the scan blindness in a microstrip array. The proposed λ/2 resonator is inserted between the adjacent E-shaped microstrip antenna elements separated by 0.45 λ, as a technique to suppress the occurrence of radiation in the horizontal direction. Simulated and measured results show that a reduction in mutual coupling of 35 dB is obtained between elements at the operation frequency of 3.94 GHz of the array. The scan properties of microstrip array with and without resonator have been studied and the result indicates that the scan blindness of the array can be well eliminated because of the effect of the resonator. We have developed experimental models that have proved this concept of scan blindness elimination. Finally, the influence of other antenna parameters at the presence of resonator in the array system has been studied. Prototype antennas of two-element and four-element array with and without resonator have been fabricated, measured, and the idea has been verified. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:334-338, 2014 [ABSTRACT FROM AUTHOR]

An efficient one-pot method for the regioselective bromination of allylic alcohol derivatives (two-step reaction sequence) followed by Sonogashira, Negishi, or Suzuki-Miyaura coupling reactions in the same reaction vessel (three-step reaction sequence) has been developed. The key reaction in these one-pot systems is the regioselective DBU-promoted trans HBr elimination of vicinal dibromides bearing an adjacent O-functional group. [ABSTRACT FROM AUTHOR]

SUMMARY The most efficient way to parallelize computation is to build and evaluate the task graph constrained only by the data dependencies between the tasks. Both Intel's C++ Concurrent Collections (CnC) and Threading Building Blocks (TBB) libraries allow such task-based parallel programming. CnC also adapts the macro data flow model by providing only single-assignment data objects in its global data space. Although CnC makes parallel programming easier, by specifying data flow dependencies only through single-assignment data objects, its macro data flow model incurs overhead. Intel's C++ CnC library is implemented on top of its C++ TBB library. We can measure the overhead of CnC by comparing its performance with that of TBB. In this paper, we analyze all three types of data dependencies in the tiled in-place Gauss-Jordan elimination algorithm for the first time. We implement the task-based parallel tiled Gauss-Jordan algorithm in TBB using the data dependencies analyzed and compare its performance with that of the CnC implementation. We find that the overhead of CnC over TBB is only 12 %- 15 % of the TBB time, and CnC can deliver as much as 87 %- 89 % of the TBB performance for Gauss-Jordan elimination, using the optimal tile size. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper provides a first example of a model theoretically well-behaved structure consisting of a proper o-minimal expansion of the real field and a dense multiplicative subgroup of finite rank. Under certain Schanuel conditions, a quantifier elimination result will be shown for the real field with an irrational power function xτ and a dense multiplicative subgroup of finite rank whose elements are algebraic over ℚ(τ). Moreover, every open set definable in this structure is already definable in the reduct given by just the real field and the irrational power function. [ABSTRACT FROM AUTHOR]

To solve tridiagonal systems of linear equations, the Thomas Algorithm is a much more efficient method than, for instance, Gaussian elimination. The algorithm uses a series of elementary row operations and can solve a system of n equations in 𝒪( n) operations, instead of 𝒪( n3) . Many variations of the Thomas Algorithm have been developed over the years to solve very specific near-tridiagonal matrix. However, none of these methods address the situation of a system of linear equations that could easily be solved if elementary operations on columns are applied, instead of elementary operations on rows. The present paper proposes an efficient method that allows the use of elementary column operations to solve linear systems of equations using vector multiplication techniques, such as the one proposed by Thomas. Copyright © 2008 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The article presents a study on two due window scheduling problems in a two-machine flow shop. Several dominance properties are derived such as elimination and sequencing rules and lower penalty bounds. It showed that the problems have nonregular performance measures due to lack of optimality results and solution techniques. Pseudopolynomial dynamic programming algorithms for solving the problems were then developed as a result.

The threecomponent reactions of 1azabicyclo1.1.0butanes 1, dicyanofumarates E5, and MeOH or morpholine yielded azetidine enamines 8and 9with the cisorientation of the ester groups at the CC bond Econfiguration; Schemes3and 4. The structures of 8aand 9dwere confirmed by Xray crystallography. The formation of the products is explained viathe nucleophilic addition of 1onto E5, leading to a zwitterion of type 7Scheme2, which is subsequently trapped by MeOH or morpholine 10a, followed by elimination of HCN. Similarly, twocomponent reactions between secondary amines 10a–10cand E5gave products 12with an Eenamine structure and Zoriented ester groups. On the other hand, twocomponent reactions involving primary amines 10d–10for NH3led to the formation of the corresponding Zenamines, in which the Eorientation of ester groups was established. [ABSTRACT FROM AUTHOR]

In this paper we show some non-elementary speed-ups in logic calculi: Both a predicative second-order logic and a logic for fixed points of positive formulas are shown to have non-elementary speed-ups over first-order logic. Also it is shown that eliminating second-order cut formulas in second-order logic has to increase sizes of proofs super-exponentially, and the same in eliminating second-order epsilon axioms. These are proved by relying on results due to P. Pudlák. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

This work describes a multi-agent framework for developing autonomous applications of integer programming to playoff qualification and elimination problems in sports tournaments. These applications involve collecting results from several sources, processing them, and publishing a report on the situation of each team taking part in the competition, regarding qualification and elimination statistics. An instance of this framework was created to follow the Brazilian national football tournament, showing very good results in practice in terms of ease of use; speed of update, processing and publication; and attractiveness to the users. [ABSTRACT FROM AUTHOR]

Simplifying large ecosystem models is essential if we are to understand the underlying causes of observed behaviors. However, such understanding is often employed to achieve simplification. This paper introduces two model simplification methods that can be applied without requiring intimate prior knowledge of the system. Their utility is measured by the resulting values of given model diagnostics relative to those of the large model. The first method is a simple automated procedure for nondimensionalizing large ecosystem models, which identifies and eliminates terms that have little effect on model diagnostics. Some of its limitations are then addressed by the rate elimination method, which measures the relative importance of model terms using least-squares regression. The methods are applied to a model of the nitrogen cycle in Port Phillip Bay, Victoria, Australia. The rate elimination method provided more insights into the causal relationships built into the model than the nondimensionalizing method. It also allowed the reduction of the model's dimension. Thus it is a useful first step in model simplification. [ABSTRACT FROM AUTHOR]

A mechanism for combining any two substructural logics (e.g. linear and intuitionistic logics) is studied from a proof-theoretic point of view. The main results presented are cut-elimination and simulation results for these combined logics called synthesized substructural logics. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The theory of algebraically closed non-Archimedean valued fields is proved to eliminate quantifiers in an analytic language similar to the one used by Cluckers, Lipshitz, and Robinson. The proof makes use of a uniform parameterized normalization theorem which is also proved in this paper. This theorem also has other consequences in the geometry of definable sets. The method of proving quantifier elimination in this paper for an analytic language does not require the algebraic quantifier elimination theorem of Weispfenning, unlike the customary method of proof used in similar earlier analytic quantifier elimination theorems. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The effects of ultraviolet (UV) radiation on the photosynthetic and UV-screening pigments in needles of Scots pine ( Pinus sylvestris L. ) saplings were studied in a UV-exclusion field chamber experiment in northern Finland (67°N) during 2001–2002. The chambers held filters that excluded both UVB and UVA, only UVB, transmitted all UV, or lacked filters. Analyses of control needles (no filter and polyethene filter) showed that the first changes to occur in spring (end of April) was an abrupt increase in the epoxidation state (EPS) of the xanthophyll cycle pigments, likely in relation with the beginning of the photosynthetic activity. The concentration of chlorophyll, lutein, neoxanthin, α-carotene, β-carotene, and the size of the xanthophyll cycle pool (violaxanthin+antheraxanthin+zeaxanthin=VAZ) changed only later when needles reached their summer photosynthesis state. Exclusion of UV radiation significantly affected the xanthophyll cycle but not the other photosynthetic pigments analysed. Interestingly, the effects on xanthophylls were dependent on the sampling date. Under UVA/B-exclusion, the EPS was increased and VAZ pool size was unchanged in April, whereas EPS remained unchanged and the VAZ pool size was reduced in May and June. The existence of two sustained and active antenna modes during winter and summer could be an explanation for the specific UV-exclusion effect in the different season. A high-performance liquid chromatography analysis of soluble phenolics showed that the exclusion of UVA/B radiation caused a significant effect on five compounds out of 46 studied, without affecting the concentration of the total soluble phenolics. Under UVA/B-exclusion, the concentration of three of them (secoisolariciresinol-glucopyranoside, two unknown) was reduced while the concentration of dicoumaroyl-astragalin and pinosylvin monomethylether was increased compared with both controls separately. In general, the exclusion of UVA/B caused a stronger effect than the exclusion of UVB on both photosynthetic and UV screening pigments. The effects of UV radiation on xanthophyll cycle pigments were season-specific and detectable only under stressful spring conditions (freezing temperatures and high irradiance due to snow reflection). The effect on the xanthophyll cycle could be a direct consequence of UV treatments, or an indirect consequence of the changed flavonoid composition, or a combination of both. [ABSTRACT FROM AUTHOR]

The standard rule of necessitation in systems of natural deduction for the modal logic S4 concludes □A from A whenever all assumptions A depends on are modal formulas. This condition prevents the composability and normalization of derivations, and therefore modifications of the rule have been suggested. It is shown that both properties hold if, instead of changing the rule of necessitation, all elimination rules are formulated in the manner of disjunction elimination, i.e. with an arbitrary consequence. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

We give an example of an affinoid curve without analytic continuation. We use this to produce an example of an affinoid morphism that cannot be flattened by a finite sequence of local blow-ups. Thus the global rigid analogue of Hironaka's complex analytic flattening theorem given by T. Gardener and H. Schoutens, in Theorem 2.3 of ‘Flattening and subanalytic sets in rigid analytic geometry’, Proc. London Math. Soc (3) 83 (2001) 681–707, is not true. Since this is a key step in the proof of the affinoid elimination theorem (loc. cit. Theorem 3.12), that proof contains a serious gap. We also give an example of an affinoid subset of the plane that is not the image under a proper rigid analytic map of a set that is globally semianalytic in the domain of that map. This clarifies the relationship among several natural categories of rigid subanalytic sets. [ABSTRACT FROM AUTHOR]

The structures of coordination complexes of methylmagnesium chloride with 1‐halogen‐3‐methoxy‐1‐propynes have been studied by means of ab initio methods (RHF/3‐21G*, RHF/6‐31G* and RHF/6‐31G**), taking into account the electron correlation by Møller‐Plesset perturbation theory (MP2). Two pathways of the nucleophilic halogen substitution reaction between the reagents have been considered. The calculations predict the addition–elimination mechanism as advantageous for the reaction. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 [ABSTRACT FROM AUTHOR]

It is well known that some pivoting strategies are backward stable for Gauss elimination but are not backward stable for Gauss–Jordan elimination (GJE) when these procedures are used to solve a linear system Ax=b. We analyse the simultaneous backward stability for Gauss and GJE of several pivoting strategies, including a pivoting strategy which we call double partial pivoting. Copyright © 2002 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Small angle X-ray scattering measurements, bulk and skeleton density data and an in-situ study by dilatometric thermal analysis about the nanoporosity elimination above 800 °C in TEOS sonogels are presented. Apparently, two processes act during the nanoporosity elimination, which precedes the foaming phenomenon often observed in such systems. The first, with an activation energy of (3.9 ± 0.4) × 102 kJ/mol and high frequency factor, is the controlling process of the most nanoporosity elimination at higher temperature. The value of this activation energy is compatible to that for viscous flux throughout densification process in typical silica-based materials. The second, with an activation energy of (49 ± 5) kJ/mol and low frequency factor, seems to be the controlling process of the first and extremely slow nanoporosity elimination at low temperature. [ABSTRACT FROM AUTHOR]

Iterated elimination of strictly dominated strategies is an order dependent procedure. It can also generate spurious Nash equilibria, fail to converge in countable steps, or converge to empty strategy sets. If best replies as well-defined, then spurious Nash equilibria cannot appear; if strategy spaces are compact and payoff functions are uppersemicontinuous in own strategies, then order does not matter; if strategy sets are compact and payoff functions are continuous in all strategies, then a unique and nonempty maximal reduction exists. These positive results extend neither to the better-reply secure games for which Reny has established the existence of a Nash equilibrium, nor to games in which (under iterated eliminations) any dominated strategy has an undominated dominator. [ABSTRACT FROM AUTHOR]

This paper introduces a method for finding the non-dominated set in criterion space of an MOLP problem based on Fourier–Motzkin Elimination. The method incorporates a procedure that eliminates decision variables from constraints and transforms a feasible region from decision space to criterion space. While avoiding characterization of the efficient set in decision space, it finds the non-dominated set in criterion space. After the decision maker's most preferred criterion vector has been identified, the corresponding efficient solutions can be found by backward substitution. The method was implemented in MATLAB using a tabular form and computational experiments were conducted. The results indicate that although the method performs well for relatively small problems, it can be computationally intensive for larger problems. Nonetheless, the method is intuitively appealing and it provides useful insights into the geometry and theory of MOLP. As such it makes it a valuable educational tool for students of multi-criteria decision analysis. Copyright © 2003 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Genera connections between quantifier elimination and decidability for first order theories are studied and exemplified. [ABSTRACT FROM AUTHOR]

Based on the computation mode introduced in [13], we deal with the time complexity of computations over arbitrary first-order structures.The main emphasis is on parameter-free computations. Some transfer results for solutions of P versus NP problems as well as relationships to quantifier elimination are discussed. By computation tree analysis using first-order formulas, it follows that P versus NP solutions and other results of structural complexity theory are invariant under elementary equivalence of structures. [ABSTRACT FROM AUTHOR]

Recently Ekman gave a derivation in natural deduction such that it either contains a substantial redundant part or else is not normal. It is shown that this problem is caused by a non-normality inherent in the usual modus ponens rule. [ABSTRACT FROM AUTHOR]

Let f:M’N be a stable map between orientable 4-manifolds, where M is closed and N is stably parallelisable. It is shown that the signature of M vanishes if and only if there exists a stable map g:M’N homotopic to f which has only fold and cusp singularities. This together with results of Ando and Èliaaberg shows that, in this situation, the Thom polynomials are the only obstructions to the elimination of the singularities except for the fold singularity. Also studied are some topological properties (including those of the discriminant set) of stable maps between 4-manifolds with only Ak-type singularities. [ABSTRACT FROM AUTHOR]

In this paper we introduce and analyse a new Schur complement approximation based on incomplete Gaussian elimination. The approximate Schur complement is used to develop a multigrid method. ibis multigrid method has an algorithmic structure that is very similar to the algorithmic structure of classical multigrid methods. The resulting method is almost purely algebraic and has increasing robustness properties with respect to variation in problem parameters. [ABSTRACT FROM AUTHOR]

Excised etiolated cotyledons of cucumber (Cucumis sativus L. cv. Aonagajibai) were continuously irradiated under various intensities of white light. The rate of chlorophyII (Chi) formation during the lag phase reaches a plateau at fluence rates above 1.4 urmol m−2 s−1. This is true in both water‐control and benzyladenine (BA)‐pretreated cotyledons. In cotyledons pretreated for 14 h with BA in darkness (in which case, Chl formation is stimulated by BA during both the lag and the steady‐state phases), the increase in the steady‐state rate of Chl formation with increasing light in tensity is stimulated compared to that of the water control over the range of fluence rates, 0. 25‐43 urmol m−2 s−1. In cotyledons pretreated for 6 h with BA in darkness (only Chl formation during the lag phase is stimulated), only an increase in fluence rate from 0.25 to 1.4 umol m−2 s−1 causes a higher increase in the Chl formation in the BA‐treated cotyledons than in the water control. The time course of Chl formation shows that the BA‐induced late‐appearing effect (stimulation of the steady‐state rate) is almost absent at low intensity illumination, but the BA‐induced fast‐appearing effect (elimination of the lag phase) is effective at all intensities. From this evidence, the Chl‐forming process apparently consists of two components, whose periods of operation or light‐intensity requirements are different. BA stimulates the rates of the respective components in both the fast and the late‐appearing effects. [ABSTRACT FROM AUTHOR]

The article focuses on developing tree-sequent calculi for normal modal logics (NLs). It shows the direct relation of modal rules to modal axioms as well as the Kripke availability relation in calculus. It states that the modal operators correspond to the movement of formulas along trees. Moreover, it exhibits the proof methods and cut-elimination theorems for main NLs.

The article describes a modification of LD and proves the cut-elimination theorem for it. It establishes a weak version of cut-elimination theorem for LD, stating that all cuts except some special forms can be eliminated from a proof in LD. It obtains some corollaries on syntactical properties of CD from these cut-elimination theorems.

This article examines the definition of the coproduction concept in public administration. The past decade has witnessed increasing pressures on urban government to provide more and better quality services while at the same time holding the line on costs. Local government officials, therefore, must strike a delicate balance between the fiscal capabilities of the city on the one hand and the service expectations of the citizenry on the other. While the response of many municipalities has been to resort to drastic solutions such as the elimination of certain types of services, the assessment of service user fees or adopting broad cut-back management programs, academics as well as some city officials have identified another alternative: "coproduction" of municipal services. Coproduction is an emerging conception of the service delivery process which envisions direct citizen involvement in the design and delivery of city services with professional service agents. Perhaps the novelty of the coproduction concept or its considerable promise as a remedy for service delivery problems has obscured critical appraisal of the meaning and implications of coproduction from both a conceptual and a policy-making perspective.

The article explores the condition that happens to the desirability of two choice alternatives when one of them is eliminated by a second person. The increase in desirability for an eliminated choice alternative should also occur when the elimination is carried out by another person rather than simply by impersonal events. According to a theory, when a person feels he is free to engage in a given behavior if he wants to, elimination of that freedom will amuse "psychological reactance" in him. Psychological reactance is defined as a motivational state directed toward the re-establishment of the eliminated freedom. In a choice situation in which a person can select any one of several alternatives, the individual may be conceived as having the freedom "to have" each alternative prior to his making a selection. When there are only two choice alternatives, unlike the case in which there are several, the elimination of one of them practically eliminates all freedom in the situation. For not only is one alternative made unavailable but the only remaining behavioral possibility is to select the other alternative.

Summary: In multiprocessor environments, the scheduling algorithms play a significant role in maximizing system performance. In this paper, we propose a clustering‐based task scheduling algorithm called Edge Priority Scheduling (EPS) for multiprocessor environments. The proposed algorithm extends the idea of edge zeroing heuristic and uses the concept of edge priority to minimize the makespan of the task graph. The complexity of the EPS algorithm is O(|V||E|(|V| + |E|)), where |E| represents the number of edges and |V| denotes the number of nodes in the task graph. The experiments are performed for random task graphs and the task graphs generated from some representative real‐world applications such as Gaussian Elimination and Fast Fourier Transform. The performance of the EPS algorithm is compared with six well‐known algorithms such as EZ (Edge Zeroing), LC (Linear Clustering), CPPS (Cluster Pair Priority Scheduling), DCCL (Dynamic Computation Communication Load), RDCC (Randomized Dynamic Computation Communication), and LOCAL. The results show that the EPS algorithm outperforms the compared algorithms in terms of the normalized schedule length and speedup. [ABSTRACT FROM AUTHOR]

Summary: In this paper, an investigation into the behavior of modern narrowband power‐line communication systems when concatenated with both a fountain code named Luby transform code and a combination of nonlinear preprocessing techniques called signal clipping with blanking is presented. The new systems can be used in applications such as the automatic meter reading component of smart grid technology. Testing is performed on a range of systems provided by the G3 standard and the results show that a bit error rate improvement can be achieved with the correct encoder/decoder settings. The recommended settings include an adaptive technique that uses Gaussian elimination for Luby transform code decoding and code rates that depend on the system specifications used. From there, it is shown that a further improvement is achieved when both the Luby transform code and adaptive signal clipping/blanking based on signal power are combined. It is found that these modifications present a complexity trade‐off, which is higher on the receiver side. This added complexity can be well‐tolerated in automatic meter‐reading systems because of the star topology and asymmetric nature of the network, which has a centralized agent acting as a receiver that collects data from various transmitter nodes. [ABSTRACT FROM AUTHOR]

A fractional-N multiplying delay-locked loop (MDLL) with delaylocked loop (DLL)-based injection clock generation is presented. By exploiting multiphase output of DLL which delay is locked to the period of output frequency, the proposed architecture performs a fractional clock multiplication with MDLL, while eliminating deterministic jitter from fractional divider. The proposed MDLL is designed in a 0.18 μm CMOS process and achieves 31.25 kHz frequency resolution with 1 MHz reference frequency. It occupies an active area of 0.055 mm2, and consumes 45 μW for 10 MHz frequency generation, showing energy efficiency figure-of-merit (FoM) of 4.5 μW/MHz. [ABSTRACT FROM AUTHOR]

Earthworms (Eisenia foetida) were given food contaminated with hexachlorobenzene (HxCBz) and 20 tetra- to heptachlorinated biphenyls (PCBs). The PCBs were selected to cover a wide range of physicochemical properties. The uptake efficiencies, uptake rate constants, and elimination rate constants in worms varied between the 20 PCBs. The uptake efficiencies were between 10 and 68%. The PCBs that were eliminated fastest contained few chlorine atoms, had more polar characteristics, and were sterically hindered. Slowest was the elimination for less polar PCBs with six or seven chlorine atoms such as the non-ortho-substituted PCB 169. Elimination half-lives varied between 6 and 25 d. Thebiomagnification factors (BMFs) for the PCBs and HxCBz averaged 0.1 based on lipids and 0.04 based on wet (worms) and dry (food) weight. Worm cocoons were analyzed for PCBs for the first time. The PCB pattern in the cocoons differed from the adult worms by the comparatively higher load of non-ortho PCBs. By studying congeners covering a largerange of PCB physicochemical characteristics, their fate within the environmental and the factors influencing biological responses can bebetter understood. [ABSTRACT FROM AUTHOR]