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Showing papers by "Cornell University published in 1993"


Journal ArticleDOI
TL;DR: Efficient algorithms for computing the Hausdorff distance between all possible relative positions of a binary image and a model are presented and it is shown that the method extends naturally to the problem of comparing a portion of a model against an image.
Abstract: The Hausdorff distance measures the extent to which each point of a model set lies near some point of an image set and vice versa. Thus, this distance can be used to determine the degree of resemblance between two objects that are superimposed on one another. Efficient algorithms for computing the Hausdorff distance between all possible relative positions of a binary image and a model are presented. The focus is primarily on the case in which the model is only allowed to translate with respect to the image. The techniques are extended to rigid motion. The Hausdorff distance computation differs from many other shape comparison methods in that no correspondence between the model and the image is derived. The method is quite tolerant of small position errors such as those that occur with edge detectors and other feature extraction methods. It is shown that the method extends naturally to the problem of comparing a portion of a model against an image. >

4,194 citations



Journal ArticleDOI
30 Jul 1993-Science
TL;DR: A reconciliation of findings with the traditional analysis is presented based on the "pseudospectra" of the linearized problem, which imply that small perturbations to the smooth flow may be amplified by factors on the order of 105 by a linear mechanism even though all the eigenmodes decay monotonically.
Abstract: Fluid flows that are smooth at low speeds become unstable and then turbulent at higher speeds. This phenomenon has traditionally been investigated by linearizing the equations of flow and testing for unstable eigenvalues of the linearized problem, but the results of such investigations agree poorly in many cases with experiments. Nevertheless, linear effects play a central role in hydrodynamic instability. A reconciliation of these findings with the traditional analysis is presented based on the "pseudospectra" of the linearized problem, which imply that small perturbations to the smooth flow may be amplified by factors on the order of 105 by a linear mechanism even though all the eigenmodes decay monotonically. The methods suggested here apply also to other problems in the mathematical sciences that involve nonorthogonal eigenfunctions.

1,773 citations


Journal ArticleDOI
TL;DR: It is suggested that it is possible to take advantage of the redundancy in continuous, but non-aligned features by associating the outputs of filters with similar tuning, and suggest that some of the processes involved in texture segregation may have a similar explanation.

1,609 citations


Journal ArticleDOI
26 Nov 1993-Science
TL;DR: A yeast artificial chromosome clone that spans the Pto region was identified and used to probe a leaf complementary DNA (cDNA) library, suggesting a role for Pto in a signal transduction pathway.
Abstract: The Pto gene in tomato confers resistance to races of Pseudomonas syringae pv. tomato that carry the avirulence gene avrPto. A yeast artificial chromosome clone that spans the Pto region was identified and used to probe a leaf complementary DNA (cDNA) library. A cDNA clone was isolated that represents a gene family, at least six members of which genetically cosegregate with Pto. When susceptible tomato plants were transformed with a cDNA from this family, they were resistant to the pathogen. Analysis of the amino acid sequence revealed similarity to serine-threonine protein kinases, suggesting a role for Pto in a signal transduction pathway.

1,439 citations


Journal ArticleDOI
TL;DR: In this paper, the authors studied the asymptotic behavior of stochastic strategy revision processes, including (myopic) best response and stochastically choice, in a lattice-based game, where each player interacts directly with only a finite set of neighbors and any two players indirectly interact through a finite chain of direct interactions.

1,397 citations


Journal ArticleDOI
TL;DR: This paper investigated whether exposure to the self-interest model commonly used in economics alters the extent to which people behave in self-interested ways, and they found that exposure to this model does in fact encourage people to behave in a more selfish manner.
Abstract: F rom the perspective of many economists, motives other than self-interest are peripheral to the main thrust of human endeavor, and we indulge them at our peril. In Gordon Tullock's (1976) words (as quoted by Mansbridge, 1990, p. 12), "the average human being is about 95 percent selfish in the narrow sense of the term." In this paper we investigate whether exposure to the self-interest model commonly used in economics alters the extent to which people behave in self-interested ways. The paper is organized into two parts. In the first, we report the results of several empirical studies-some our own, some by others -that suggest economists behave in more self-interested ways. By itself, this evidence does not demonstrate that exposure to the self-interest model causes more self-interested behavior, since it may be that economists were simply more self-interested to begin with, and this difference was one reason they chose to study economics. In the second part of the paper, we present preliminary evidence that exposure to the self-interest model does in fact encourage self-interested behavior.

1,328 citations


Journal ArticleDOI
TL;DR: There are reliable age differences in suggestibility but that even very young children are capable of recalling much that is forensically relevant, and a synthesis of this research posits three "families" of factors--cognitive, social, and biological--that must be considered if one is to understand seemingly contradictory interpretations of the findings.
Abstract: The field of children's testimony is in turmoil, but a resolution to seemingly intractable debates now appears attainable. In this review, we place the current disagreement in historical context and describe psychological and legal views of child witnesses held by scholars since the turn of the 20th century. Although there has been consistent interest in children's suggestibility over the past century, the past 15 years have been the most active in terms of the number of published studies and novel theorizing about the causal mechanisms that underpin the observed findings. A synthesis of this research posits three "families" of factors--cognitive, social, and biological--that must be considered if one is to understand seemingly contradictory interpretations of the findings. We conclude that there are reliable age differences in suggestibility but that even very young children are capable of recalling much that is forensically relevant. Findings are discussed in terms of the role of expert witnesses.

1,328 citations


Journal ArticleDOI
TL;DR: In the case of the Southern Puna Plateau, central Andes, the most deformation occurs at the top of the mantle and bottom of the crust, where most of the negative buoyancy lies.

1,323 citations


Journal ArticleDOI
TL;DR: In this paper, the authors present a quantitative model for the Galactic free electron distribution, which abandons the assumption of axisymmetry and explicitly incorporates spiral arms; their shapes and locations are derived from existing radio and optical observations of H II regions.
Abstract: The present quantitative model for Galactic free electron distribution abandons the assumption of axisymmetry and explicitly incorporates spiral arms; their shapes and locations are derived from existing radio and optical observations of H II regions. The Gum Nebula's dispersion-measure contributions are also explicitly modeled. Adjustable quantities are calibrated by reference to three different types of data. The new model is estimated to furnish distance estimates to known pulsars that are accurate to about 25 percent.

1,312 citations


Book ChapterDOI
01 Jan 1993
TL;DR: This work presents two semidecision procedures for verifying safety properties of piecewiselinear hybrid automata, in which all variables change at constant rates, and demonstrates that for many of the typical workshop examples, the procedures do terminate and thus provide an automatic way for verifying their properties.
Abstract: We introduce the framework of hybrid automata as a model and specification language for hybrid systems. Hybrid automata can be viewed as a generalization of timed automata, in which the behavior of variables is governed in each state by a set of differential equations. We show that many of the examples considered in the workshop can be defined by hybrid automata. While the reachability problem is undecidable even for very restricted classes of hybrid automata, we present two semidecision procedures for verifying safety properties of piecewiselinear hybrid automata, in which all variables change at constant rates. The two procedures are based, respectively, on minimizing and computing fixpoints on generally infinite state spaces. We show that if the procedures terminate, then they give correct answers. We then demonstrate that for many of the typical workshop examples, the procedures do terminate and thus provide an automatic way for verifying their properties.

Journal ArticleDOI
TL;DR: High resolution structures for the complexes formed by the immunosuppressive agents FK506 and rapamycin with the human immunophilin FKBP-12 have been determined by X-ray diffraction and suggest ways in which this catalytic activity could operate.

Journal ArticleDOI
TL;DR: In this paper, a modified Benedict-Webb-Rubin (MBWR) equation of state for the Lennard-Jones (LJ) fluid is presented and compared with the simulation data of this work, and previously published Gibbs ensemble data.
Abstract: We review the existing simulation data and equations of state for the Lennard-Jones (LJ) fluid, and present new simulation results for both the cut and shifted and the full LJ potential. New parameters for the modified Benedict-Webb-Rubin (MBWR) equation of state used by Nicolas, Gubbins, Streett and Tildesley are presented. In contrast to previous equations, the new equation is accurate for calculations of vapour-liquid equilibria. The equation also accurately correlates pressures and internal energies from the triple point to about 4·5 times the critical temperature over the entire fluid range. An equation of state for the cut and shifted LJ fluid is presented and compared with the simulation data of this work, and previously published Gibbs ensemble data. The MBWR equation of state can be extended to mixtures via the van der Waals one-fluid theory mixing rules. Calculations for binary fluid mixtures are found to be accurate when compared with Gibbs ensemble simulations.

Journal ArticleDOI
TL;DR: In this article, a 1,749-bp fragment from the 5'-flanking region of the iNOS gene was cloned from a mouse genomic library, and used S1 nuclease mapping and primer extension to identify the mRNA transcription start site within it.
Abstract: Inducible nitric oxide synthase (iNOS) can be expressed by many types of mammalian cells in response to diverse signals acting synergistically, including cytokines and microbial products. We previously showed that induction of iNOS in mouse macrophages by interferon gamma (IFN-gamma) and lipopolysaccharide (LPS) was at the transcriptional level. From a mouse genomic library, we now cloned a 1,749-bp fragment from the 5'-flanking region of the iNOS gene, and used S1 nuclease mapping and primer extension to identify the mRNA transcription start site within it. The mRNA initiation site is preceded by a TATA box and at least 22 oligonucleotide elements homologous to consensus sequences for the binding of transcription factors involved in the inducibility of other genes by cytokines or bacterial products. These include 10 copies of IFN-gamma response element; 3 copies of gamma-activated site; 2 copies each of nuclear factor-kappa B, IFN-alpha-stimulated response element, activating protein 1, and tumor necrosis factor response element; and one X box. Plasmids in which all or the downstream one half or one third of this region of iNOS were linked to a reporter gene encoding chloramphenicol acetyltransferase were transfected into cells of the RAW264.7 macrophage-like line. All these constructs conferred inducibility of the iNOS promoter by LPS, but only the construct containing all 1,749 bp conferred synergistic inducibility by IFN-gamma plus LPS.

Journal ArticleDOI
TL;DR: In this paper, the pore size distribution of porous sorbents is determined by fitting the correlation of the experimental adsorption isotherm of the sorbent to the mean field density functional theory.
Abstract: We present an improved method, based upon density functional theory, for the determination of the pore size distribution (PSD) of porous sorbents. The adsorption isotherms predicted by nonlocal mean field theory for individual slit pores are correlated as a function of pressure and pore width. The PSD is then calculated by fitting this correlation to the experimental adsorption isotherm of the sorbent. We apply the analysis method to adsorption data for nitrogen on several porous carbons. In this application, the porous network is modeled as a continuous size distribution of noninteracting slit-shaped graphitic pores. The PSDs obtained by using the Kelvin equation and using the local and nonlocal versions of the mean field density functional theory are compared and evaluated. The results demonstrate that nonlocal theory provides a more accurate interpretation of the PSD than previous methods have achieved, particularly when the analysis is applied to highly microporous sorbents.

Proceedings ArticleDOI
22 Jun 1993
TL;DR: In this article, a method for clustering words according to their distribution in particular syntactic contexts is described and evaluated experimentally, where words are represented by the relative frequency distributions of contexts in which they appear, and relative entropy between those distributions is used as the similarity measure for word clustering.
Abstract: We describe and evaluate experimentally a method for clustering words according to their distribution in particular syntactic contexts. Words are represented by the relative frequency distributions of contexts in which they appear, and relative entropy between those distributions is used as the similarity measure for clustering. Clusters are represented by average context distributions derived from the given words according to their probabilities of cluster membership. In many cases, the clusters can be thought of as encoding coarse sense distinctions. Deterministic annealing is used to find lowest distortion sets of clusters: as the annealing parameter increases, existing clusters become unstable and subdivide, yielding a hierarchical "soft" clustering of the data. Clusters are used as the basis for class models of word coocurrence, and the models evaluated with respect to held-out test data.

Posted Content
TL;DR: It is shown that if objective measures are sufficiently close to perfect then no implicit contracts are feasible (because the firm's fallback position after reneging on an implicit contact is too attractive), and that objective and subjective measures can reinforce each other.
Abstract: Objective measures of performance are seldom perfect. In response, incentive contracts often include important subjective components that mitigate incentive distortions caused by imperfect objective measures. This paper explores the combined use of subjective and objective performance measures in (respectively) implicit and explicit incentive contracts. Naturally, objective and subjective measures often are substitutes, sometimes strikingly so: we show that if objective measures are sufficiently close to perfect then no implicit contracts are feasible (because the firm's fallback position after reneging on an implicit contact is too attractive). We also show, however, that objective and subjective measures can reinforce each other: if objective measures become more accurate then in some circumstances the optimal contract puts more weight on subjective measures (because the improved objective measures increase the value of the ongoing relationship, and so reduce the firm's incentive to renege). We also analyze the use of subjective weights on objective performance measures, and provide case-study evidence consistent with our analyses.

Journal ArticleDOI
TL;DR: The Kochen-Specker Theorem as discussed by the authors is one of the most famous no-hidden-variables theorems, and it has transparently simple proofs, which can be converted without additional analysis into a powerful form of the Bell's Theorem.
Abstract: Although skeptical of the prohibitive power of no-hidden-variables theorems, John Bell was himself responsible for the two most important ones. I describe some recent versions of the lesser known of the two (familiar to experts as the "Kochen-Specker theorem") which have transparently simple proofs. One of the new versions can be converted without additional analysis into a powerful form of the very much better known "Bell's Theorem," thereby clarifying the conceptual link between these two results of Bell.

Book
24 Feb 1993
TL;DR: The body in context but are there really no biological differences beyond the body? as discussed by the authors is an alternative hypothesis to the Body in Context But are There Really No Biological Differences Beyond the Body?.
Abstract: Part 1 Introduction and overview. Part 2 Biological essentialism: the Biological Politics of the Late-l9th and Early 20th Centuries The Modern Period I - Just-So Stories of Socio-Biology The Modern Period II - Prenatal Hormone Theory An Alternative Hypothesis - The Body in Context But Are There Really No Biological Differences Beyond the Body?. Part 3 Andocentrism: Judaeo-Christian Theology Ancient Greek Philosophy Freudian Psychoanalytic Theory American Equal-Rights Law. Part 4 Gender Polarization: The Nineteenth Century: Sexual Inversion The Twentieth Century I - Homosexuality The Twentieth Century II - Masculinity/Femininity Beyond Science: The Feminist Celebration of Female Differences. Part 5 The Construction of Individual Gender Identity: Previous Theoretical Perspectives The Process of Enculturation The Process of Self-Construction Resisting the Culture's Lenses - The Making of a Gender Nonconformist. Part 6 Transforming the Debate on Sexual Inequality: The Conundrum of Difference Toward True Gender Neutrality - Eradicating Androcentrism Toward Utopia - Eradicating Gender Polarization.

Journal ArticleDOI
TL;DR: 13 non-indigenous species have been identified that have substantially influenced the Great Lakes ecosystem, both economically and ecologically.

Journal ArticleDOI
TL;DR: The most significant changes in milk fat quality relate to rheological (melting) properties, which influence numerous aspects of character and quality of manufactured dairy products.

Journal ArticleDOI
TL;DR: Six years of on ISIS is reviewed, describing the model, its implementation challenges, and the types of applications to which ISIS has been applied.
Abstract: The difficulty of developing reliable distributed software is an impediment to applying distributed computing technology in many settings. Experience with the ISIS system suggests that a structured approach based on virtually synchronous process groups yields systems which are substantially easier to develop, fault-tolerance, and self-managing. Six years of research on ISIS are reviewed, describing the model, the types of applications to which ISIS was applied, and some of the reasoning that underlies a recent effort to redesign and reimplement ISIS as a much smaller, lightweight system.

Journal ArticleDOI
TL;DR: The hypothesis that silencing in yeast results from heterochromatin formation is fortified and it is argued that the silencing proteins participate in this formation.
Abstract: Two classes of sequences in the yeast Saccharomyces cerevisiae are subject to transcriptional silencing: the silent mating-type cassettes and telomeres. In this report we demonstrate that the silencing of these regions is strictly associated with acetylation of the epsilon-amino groups of lysines in the amino-terminal domains of three of the four core histones. Both the silent mating-type cassettes and the Y domains of telomeres are packaged in nucleosomes in vivo that are hypoacetylated relative to those packaging active genes. This difference in acetylation is eliminated by genetic inactivation of silencing: The silent cassettes from sir2, sir3, or sir4 cells show the same level of acetylation as other active genes. The correspondence of silencing and hypoacetylation of the mating-type cassettes is observed even for an allele lacking a promoter, indicating that silencing per se, rather than the absence of transcription, is correlated with hypoacetylation. Finally, overexpression of Sir2p, a protein required for transcriptional silencing in yeast, yields substantial histone deacetylation in vivo. These studies fortify the hypothesis that silencing in yeast results from heterochromatin formation and argue that the silencing proteins participate in this formation.

Journal ArticleDOI
TL;DR: In this paper, a causal model was hypothesized and tested that involved simultaneous consideration of cross-sectional and longitudinal effects between job and life satisfaction, which allowed the strongest conclusions to date regarding the causality between these constructs.
Abstract: The relationship between job satisfaction and life satisfaction has been heavily researched over the years. In spite of this research interest, results have not proved conclusive in demonstrating the causal nature of the relationship. In the present study, a causal model was hypothesized and tested that involved simultaneous consideration of cross-sectional and longitudinal effects between job and life satisfaction. This type of analysis has not previously been conducted and allows the strongest conclusions to date regarding the causality between these constructs. Results based on a national probability sample of workers indicated that job and life satisfaction were significantly and reciprocally related. The cross-sectional results suggested a relatively strong relationship between job and life satisfaction, but the longitudinal results suggested a weaker relationship over a 5-year period, particularly with respect to the effect of job satisfaction on life satisfaction. The meaning of these results in the context of past research on the job satisfaction-life satisfaction relationship is discussed. Recently, Tail, Padgett, and Baldwin (1989) provided the first meta-analytic estimate of the relationship between job satisfaction and life satisfaction. Using correlations from 34 studies, Tail et al. (1989) estimated the average corrected correlation between the constructs to be .44. The authors concluded their review with this comment: "On the basis of the substantial relationship between job and life satisfaction documented here, further explanatory research of this nature is now clearly warranted" (p. 505). In a recent review of the literature, Rain, Lane, and Steiner (1991) held that although Tail et al.'s study was useful in providing an overall assessment of the job satisfactionlife satisfaction relationship, it did not address the direction of causality between the constructs. Rain et al. argued that more efforts investigating the causality between job and life satisfaction were needed. Thus, despite extensive research, the critical question concerning what the direction of influence between job and life satisfaction is remains unanswered. The correlation estimated in Tait et al.'s (1989) meta-analysis suggests that a positive relationship exists, but this study provided no information regarding whether job satisfaction causes life satisfaction, life satisfaction causes job satisfaction, or the two constructs are mutually causative. A causal influence from life satisfaction to job satisfaction is supportive of the dispositional perspective (Judge & Hulin, in press; Judge & Locke, 1993; Staw, Bell, & Clausen,

Journal ArticleDOI
TL;DR: The generalized assignment problem can be viewed as the following problem of scheduling parallel machines with costs; each job is to be processed by exactly one machine; processing jobj on machinei requires timepij and incurs a cost ofcij; each machinei is available forTi time units, and the objective is to minimize the total cost incurred.
Abstract: The generalized assignment problem can be viewed as the following problem of scheduling parallel machines with costs. Each job is to be processed by exactly one machine; processing jobj on machinei requires timep ij and incurs a cost ofc ij ; each machinei is available forT i time units, and the objective is to minimize the total cost incurred. Our main result is as follows. There is a polynomial-time algorithm that, given a valueC, either proves that no feasible schedule of costC exists, or else finds a schedule of cost at mostC where each machinei is used for at most 2T i time units. We also extend this result to a variant of the problem where, instead of a fixed processing timep ij , there is a range of possible processing times for each machine—job pair, and the cost linearly increases as the processing time decreases. We show that these results imply a polynomial-time 2-approximation algorithm to minimize a weighted sum of the cost and the makespan, i.e., the maximum job completion time. We also consider the objective of minimizing the mean job completion time. We show that there is a polynomial-time algorithm that, given valuesM andT, either proves that no schedule of mean job completion timeM and makespanT exists, or else finds a schedule of mean job completion time at mostM and makespan at most 2T.

Journal ArticleDOI
TL;DR: In this paper, the problem of estimating the number of kinds in a population of animals and plants is discussed. But the focus is not on estimating the relative sizes of the classes, but on the estimation of C itself.
Abstract: How many kinds are there? Suppose that a population is partitioned into C classes. In many situations interest focuses not on estimation of the relative sizes of the classes, but on estimation of C itself. For example, biologists and ecologists may be interested in estimating the number of species in a population of plants or animals, numismatists may be concemed with estimating the number of dies used to produce an ancient coin issue, and linguists may be interested in estimating the size of an author's vocabulary. In this article we review the problem of statistical estimation of C. Many approaches have been proposed, some purely data-analytic and others based in sampling theory. In the latter case numerous variations have been considered. The population may be finite or infinite. If finite, samples may be taken with replacement (multinomial sampling) or without replacement (hypergeometric sampling), or by Bernoulli sampling; if infinite, sampling may be multinomial or Bernoulli, or the sample may be th...

Journal ArticleDOI
TL;DR: Hydraulic lift need not only occur in arid or semi-arid environments where chronic water deficits prevail, but can be important in relatively mesic environments when subjected to periodic soil water deficits, that plants neighboring trees which conduct hydraulic lift can use a significant proportion of this water source, and that the HLW source can effectively ameliorate the influence of drought on the performance and growth of neighboring vegetation.
Abstract: During drought periods, sugar maple (Acer saccharum) demonstrates “hydraulic lift”; nocturnal uptake of water by roots from deep soil layers that is released from shallow roots into upper soil layers. Using standard water relations methods and stable hydrogen isotope analysis of both source-water and plant-water, I investigated (1) the magnitude and radial extent of hydraulic lift by mature, relatively open-grown trees, of A. saccharum, (2) the proportion of hydraulically-lifted water (HLW) used by shallow-rooted neighbors growing at different distances from target trees, and (3) the influence that this water source had on stomatal conductance to water vapor (g), water balance and growth of these neighbors. Soil water potentials (ψs) at −20 and −35 cm showed a distinct diel fluctuation. Soil pits dug beneath three mature trees revealed a distinct hard-pan (e.g. fragipan) layer at a depth of approximately 50 cm. Examination of root distributions obtained from soil cores and soil pits revealed that some larger diameter roots (1.9–3.7 cm) did penetrate the fragipan and were established in the ground water table. The presence of the fragipan indicated that the “rewetting” of the upper soil layer during the night could not be explained by capillary rise from the shallow water table; it was the trees that were taking up ground water and then redepositing it at night into the upper 35 cm of soil, above the fragipan. The greatest fluctuations in ψs occurred within 2.5 m of trees and only extended out to approximately 5 m. Application of a two-end-member linear mixing model which used stable hydrogen isotopic data obtained from environmental water sources and xylem-sap demonstrated that all neighbors used some fraction (3–60%) of HLW supplied by sugar maple trees. Plants that used a high proportion of HLW (e.g. rhizomatous or stoloniferous perennials) maintained significantly higher leaf water potentials and g, and showed greater aboveground growth when compared with (i) neighbors that used little or no HLW or (ii) conspecifics found growing at distances greater than about 3 m away from maple trees. Three important conclusions can be drawn from the results of this investigation that have not been demonstrated before: (1) hydraulic lift need not only occur in arid or semi-arid environments where chronic water deficits prevail, but can be important in relatively mesic environments when subjected to periodic soil water deficits, (2) that plants neighboring trees which conduct hydraulic lift can use a significant proportion of this water source, and (3) that the HLW source can effectively ameliorate the influence of drought on the performance and growth of neighboring vegetation. The results are also discussed in terms of their influence on plant nutrient relations (including plant-mycorrhizal associations), the nature of plant-plant interactions and the water balance of individuals, communities and floristic regions.

Book ChapterDOI
TL;DR: The technology has currently reached the point at which it can be readily and reliably used for a wide range of applications, and new applications can be optimized fairly readily.
Abstract: The biolistic process is still rapidly evolving. We do not anticipate further major improvements in biolistic apparatus. There will probably still be further major improvements in particles, DNA coating, and vectors, as well as significant further advances in understanding of biological determinants of cell penetration and survival. The technology has currently reached the point at which it can be readily and reliably used for a wide range of applications. Given the information presented in this chapter, new applications can be optimized fairly readily.

Journal ArticleDOI
TL;DR: The results suggest that non-healing ulcers develop an environment containing high levels of activated metalloproteinases, which may result in chronic tissue turnover and failed wound closure.

Journal ArticleDOI
22 Apr 1993-Nature
TL;DR: In this article, the authors report the sedimentary fluxes into eight trenches around the globe of trace elements that are enriched in arc volcanics (Ba, Sr, K, Rb, Cs, La, Th and U) and show that the volcanic outputs clearly reflect the sediment inputs, once the effects of melting are taken into account.
Abstract: AT ocean trenches, sea-floor sediments may either be scraped off the subducting plate, or accompany it into the mantle. Some of the subducted sediment may then be recycled to the arc crust by magmatism1; the rest may be recycled into the mantle, and contribute to mantle heterogeneity2. Strong evidence for sediment contributions to arc volcanism has come from isotope tracers, such as 207Pb and 10Be (refs 3–5), but a global mass balance requires consideration of element fluxes6. Here we report the sedimentary fluxes into eight trenches around the globe of trace elements that are enriched in arc volcanics (Ba, Sr, K, Rb, Cs, La, Th and U)7 We show that the volcanic outputs clearly reflect the sediment inputs, once the effects of melting are taken into account8. Where the sediment flux into a trench is high for a particular element, the associated volcanics are enriched in this same element. Thus, some of the geochemical characteristics of arc volcanics can be traced back to the sediments at the trench. A mass balance of the inputs and outputs will ultimately provide estimates for how much sediment is recycled to the arc, and how much to the deeper mantle.