bluuebunny/crossref_metadata_2025 huggingface dataset:
A short proof of a conjecture of De Remer and Pennello
Authors: Sager Thomas J.
Published: October 2002

In this paper we offer a short proof of the DeRemer-Pennello conjecture that if the LR(0) automaton for a grammar
G
contains a state
p
and a nonterminal
A
such that (
p
,
A
) is a nonterminal transition, (
p
,
A
)
includes
+
(
p
,
A
) and
Read
(
p
,
A
) is not empty, then grammar
G
is not LR(
k
) for any
k
.
From use to presence: on the expressions and aesthetics of everyday computational things
Authors: Redström Johan Hallnäs
Published: October 2002

The following abstracts are from recent issues and the forthcoming issue of ACM's
Transactions of Computer Human Interaction
(ToCHI). They are included here to alert
interactions'
readers to what research is being done in the field of Computer Human Interaction. The complete papers, when published, can be found in ACM's Digital Library at www.acm.org/pubs/contents/journals/tochi/
Business applications of data mining
Authors: Apte Chidanand , Liu Bing , Pednault Edwin P. D. , Smyth Padhraic
Published: October 2002

They help identify and predict individual, as well as aggregate, behavior, as illustrated by four application domains: direct mail, retail, automobile insurance, and health care.
Feature-based light field morphing
Authors: Zhang Zhunping , Wang Lifeng , Guo Baining , Shum Heung-Yeung
Published: October 2002

We present a feature-based technique for morphing 3D objects represented by light fields. Our technique enables morphing of image-based objects whose geometry and surface properties are too difficult to model with traditional vision and graphics techniques. Light field morphing is not based on 3D reconstruction; instead it relies on
ray correspondence,
i.e., the correspondence between rays of the source and target light fields. We address two main issues in light field morphing: feature specification and visibility changes. For feature specification, we develop an intuitive and easy-to-use user interface (UI). The key to this UI is
feature polygons,
which are intuitively specified as 3D polygons and are used as a control mechanism for ray correspondence in the abstract 4D ray space. For handling visibility changes due to object shape changes, we introduce
ray-space warping.
Ray-space warping can fill arbitrarily large holes caused by object shape changes; these holes are usually too large to be properly handled by traditional image warping. Our method can deal with non-Lambertian surfaces, including specular surfaces (with dense light fields). We demonstrate that light field morphing is an effective and easy-to-use technqiue that can generate convincing 3D morphing effects.
A rapid hierarchical rendering technique for translucent materials
Authors: Jensen Henrik Wann , Buhler Juan
Published: October 2002

This paper introduces an efficient two-pass rendering technique for translucent materials. We decouple the computation of irradianceat the surface from the evaluation of scattering inside the material.This is done by splitting the evaluation into two passes, where the first pass consists of computing the irradiance at selected points on the surface. The second pass uses a rapid hierarchical integration technique to evaluate a diffusion approximation based on the irradiance samples. This approach is substantially faster than previous methods for rendering translucent materials, and it has the advantage that it integrates seamlessly with both scanline rendering and global illumination methods. We show several images and animations from our implementation that demonstrate that the approach is both fast and robust, making it suitable for rendering translucent materials in production.
Interactive multiresolution hair modeling and editing
Authors: Kim Tae-Yong , Neumann Ulrich
Published: October 2002

Human hair modeling is a difficult task. This paper presents a constructive hair modeling system with which users can sculpt a wide variety of hairstyles. Our Multiresolution Hair Modeling (MHM) system is based on the observed tendency of adjacent hair strands to form clusters at multiple scales due to static attraction. In our system, initial hair designs are quickly created with a small set of hair clusters. Refinements at finer levels are achieved by subdividing these initial hair clusters. Users can edit an evolving model at any level of detail, down to a single hair strand. High level editing tools support curling, scaling, and copy/paste, enabling users to rapidly create widely varying hairstyles. Editing ease and model realism are enhanced by efficient hair rendering, shading, antialiasing, and shadowing algorithms.
Structural modeling of flames for a production environment
Authors: Lamorlette Arnauld , Foster Nick
Published: October 2002

In this paper we describe a system for animating flames. Stochastic models of flickering and buoyant diffusion provide realistic local appearance while physics-based wind fields and Kolmogorov noise add controllable motion and scale. Procedural mechanisms are developed for animating all aspects of flame behavior including moving sources, combustion spread, flickering, separation and merging, and interaction with stationary objects. At all stages in the process the emphasis is on total artistic and behavioral control while maintaining interactive animation rates. The final system is suitable for a high volume production pipeline.
Cluster assignment for high-performance embedded VLIW processors
Authors: Lapinskii Viktor S. , Jacome Margarida F. , De Veciana Gustavo A.
Published: October 2002

Clustering is an effective method to increase the available parallelism in VLIW datapaths without incurring severe penalties associated with a large number of register file ports. Efficient utilization of a clustered datapath requires careful binding/assignment of operations to clusters. The article proposes a binding algorithm that effectively explores trade-offs between in-cluster operation serialization and delays associated with data transfers between clusters. Extensive experimental evidence is provided showing that the algorithm generates high quality solutions for representative kernels, with up to 33% improvement over a state-of-the-art binding algorithm.
Estimation of state line statistics in sequential circuits
Authors: Saxena Vikram , Najm Farid N. , Hajj Ibrahim N.
Published: October 2002

In this article, we present a simulation-based technique for estimation of signal statistics (switching activity and signal probability) at the flip-flop output nodes (state signals) of a general sequential circuit. Apart from providing an estimate of the power consumed by the flip-flops, this information is needed for calculating power in the combinational portion of the circuit. The statistics are computed by collecting samples obtained from fast RTL simulation of the circuit under input sequences that are either randomly generated or independently selected from user-specified pattern sets. An important advantage of this approach is that the desired accuracy can be specified up front by the user; with some approximation, the algorithm iterates until the specified accuracy is achieved. This approach has been implemented and tested on a number of sequential circuits and has been shown to handle very large sequential circuits that can not be handled by other existing methods, while using a reasonable amount of CPU time and memory (the circuit s38584.1, with 1426 flip-flops, can be analyzed in about 10 minutes).
Bias on the web
Authors: Mowshowitz Abbe , Kawaguchi Akira
Published: October 2002

When it comes to measuring bias on the Web, there is clearly strength in numbers (of search engines, that is).
A general-purpose compression scheme for large collections
Authors: Cannane Adam , Williams Hugh E.
Published: October 2002

Compression of large collections can lead to improvements in retrieval times by offsetting the CPU decompression costs with the cost of seeking and retrieving data from disk. We propose a semistatic phrase-based approach called xray that builds a model offline using sample training data extracted from a collection, and then compresses the entire collection online in a single pass. The particular benefits of xray are that it can be used in applications where individual records or documents must be decompressed, and that decompression is fast. The xray scheme also allows new data to be added to a collection without modifying the semistatic model. Moreover, xray can be used to compress general-purpose data such as genomic, scientific, image, and geographic collections without prior knowledge of the structure of the data. We show that xray is effective on both text and general-purpose collections. In general, xray is more effective than the popular gzip and compress schemes, while being marginally less effective than bzip2. We also show that xray is efficient: of the popular schemes we tested, it is typically only slower than gzip in decompression. Moreover, the query evaluation costs of retrieval of documents from a large collection with our search engine is improved by more than 30% when xray is incorporated compared to an uncompressed approach. We use simple techniques for obtaining the training data from the collection to be compressed and show that with just over 4% of data the entire collection can be effectively compressed. We also propose four schemes for phrase-match selection during the single pass compression of the collection. We conclude that with these novel approaches xray is a fast and effective scheme for compression and decompression of large general-purpose collections.
Building a Chinese-English wordnet for translingual applications
Authors: Chen Hsin-Hsi , Lin Chi-Ching , Lin Wen-Cheng
Published: October 2002

A WordNet-like linguistic resource is useful, but difficult to construct. This article proposes a method to integrate five linguistic resources, including English/Chinese sense-tagged corpora, English/Chinese thesauruses, and a bilingual dictionary. Chinese words are mapped into WordNet. A Chinese WordNet and a Chinese-English WordNet are derived by following the structures of WordNet. Experiments with Chinese-English information retrieval are developed to evaluate the applicability of the Chinese-English WordNet. The best model achieves 0.1010 average precision, 69.23% of monolingual information retrieval. It also gains a 10.02% increase relative to a model that resolves translation ambiguity and target polysemy problems together.
Remark on algorithm 705
Authors: Hopkins Tim
Published: October 2002

We present a number of corrections to Algorithm 705 [Gardiner et al. 1992].
Data abstraction and information hiding
Authors: Leino K. Rustan M. , Nelson Greg
Published: October 2002

This article describes an approach for verifying programs in the presence of data abstraction and information hiding, which are key features of modern programming languages with objects and modules. This article draws on our experience building and using an automatic program checker, and focuses on the property ofmodular soundness: that is, the property that the separate verifications of the individual modules of a program suffice to ensure the correctness of the composite program. We found this desirable property surprisingly difficult to achieve. A key feature of our methodology for modular soundness is a new specification construct: theabstraction dependency, which reveals which concrete variables appear in the representation of a given abstract variable, without revealing the abstraction function itself. This article discusses in detail two varieties of abstraction dependencies: static and dynamic. The article also presents a new technical definition of modular soundness as a monotonicity property of verifiability with respect to scope and uses this technical definition to formally prove the modular soundness of a programming discipline for static dependencies.
Applying model-integrated computing to component middleware and enterprise applications
Authors: Gokhale Aniruddha , Schmidt Douglas C. , Natarajan Balachandran , Wang Nanbor
Published: October 2002

Combining the best elements of these two technologies can address the key challenges associated with developing enterprise applications.
Concurrency in heavily loaded neighborhood-constrained systems
Authors: Barbosa Valmir C. , Gafni Eli
Published: October 2002

Let
G
be a connected undirected graph in which each node corresponds to a process and two nodes are connected by an edge if the corresponding processes share a resource. We consider distributed computations in which processes are constantly demanding all of their resources in order to operate, and in which neighboring processes may not operate concurrently. We advocate that such a system is general enough for representing a large class of resource-sharing systems under heavy load.

We employ a distributed scheduling mechanism based on acyclic orientations of
G
and investigate the amount of concurrency that it provides. We show that this concurrency is given by a number akin to
G
's chromatic and multichromatic numbers, and that, among scheduling schemes which require neighbors in
G
to alternate in their turns to operate, ours is the one that potentially provides the greatest concurrency. However, we also show that the decision problem corresponding to optimizing concurrency is
NP
-complete.
A method for specializing logic programs
Authors: Bossi A. , Cocco N. , Dulli S.
Published: October 2002

A specialization method for logic programs that allows one to restrict a general program to special cases by means of constraint predicates is presented. A set of basic transformation operations, which are shown to produce equivalent programs, is defined. The method uses these operations for propagating the constraint information through the program and for consequently simplifying it whenever possible. Some examples of specializations are given, and some improvements and developments of the method are discussed.
Adding liveness properties to coupled finite-state machines
Authors: Aggarwal S. , Courcoubetis C. , Wolper P.
Published: October 2002

Informal specifications of protocols are often imprecise and incomplete and are usually not sufficient to ensure the correctness of even very simple protocols. Consequently, formal specification methods, such as finite-state models, are increasingly being used. The selection/resolution (S/R) model is a finite-state model with a powerful communication mechanism that makes it easy to describe complex protocols as a collection of simple finite-state machines. A software environment, called SPANNER, has been developed to specify and analyze protocols specified with the S/R model. SPANNER provides the facility to compute the joint behavior of a number of finite-state machines and to check if the “product” machine has inaccessible states, states corresponding to deadlocks, and loops corresponding to livelocks. So far, however, SPANNER has had no facility to systematically deal with liveness conditions. For example, one might wish to specify that, although a communication channel is unreliable, a message will get through if it is sent infinitely often, and to check that the infinite behavior of the protocol viewed as an infinite sequence will always be in some ω-regular set (possibly specified in terms of a formula in temporal logic or as an ω-automata). In this paper we show that with very minor modifications to the implemented system it is possible to substantially extend the type of properties that can be specified and checked by SPANNER. This is done by extending the S/R model to include acceptance conditions found in automatons on infinite words, which permits the incorporation of arbitrary liveness conditions into the model. We show how these extensions can be easily incorporated into SPANNER (and into essentially any finite-state verification system) and how the resulting system is used to automatically verify the correctness of protocols.
Remembrance of Things Past: Chromatin Remodeling in Plant Development
Authors: Goodrich Justin , Tweedie Susan
Published: October 2002

▪ Abstract  Chromatin remodeling in plants has usually been discussed in relation to aspects of genome defense such as transgene silencing and the resetting of transposon activity. The role of remodeling in controlling development has been less emphasized, although well established in animal systems. This is because cell fate in plants is often held to be entirely specified on the basis of position, apparently excluding any significant role for cell ancestry and chromatin remodeling. We argue that chromatin remodeling is used to confer mitotically heritable cell fates at late stages in pattern formation. Several examples in which chromatin remodeling factors are used to confer a memory of transient events in plant development are discussed. Because the precise biochemical functions of most remodeling factors are obscure, and little is known of plant chromatin structure, the underlying mechanisms remain poorly understood.
Vascular Endothelin-B Receptor System In Vivo Plays a Favorable Inhibitory Role in Vascular Remodeling After Injury Revealed by Endothelin-B Receptor–Knockout Mice
Authors: Murakoshi Nobuyuki , Miyauchi Takashi , Kakinuma Yoshihiko , Ohuchi Takashi , Goto Katsutoshi , Yanagisawa Masashi , Yamaguchi Iwao
Published: October 2002

Background—

Two subtypes of endothelin (ET) receptors, ET
A
and ET
B
, are distributed in vascular smooth muscle cells to cause contraction and proliferation. Vascular endothelial cells express only ET
B
receptors, which cause NO release. Although ET
A
receptor blockade is reported to be effective in ameliorating vascular remodeling, there is no report on the long-term effect of ET
B
receptor blockade on vascular remodeling after injury.

Methods and Results—

ET
B
receptor–knockout (KO) mice, which were genetically rescued from lethal intestinal aganglionosis, and wild-type (WT) mice underwent complete ligation of the right common carotid artery, ie, a blood flow cessation model of vascular remodeling. Fourteen days after ligation, the intimal area, the ratio of intimal to medial areas, and the stenotic ratio in the ligated artery of KO mice were significantly increased compared with those of WT mice. The expression level of ET-1 mRNA in the ligated artery of KO mice was increased similarly to that of WT mice, whereas tissue NO
x
levels in lesions of KO mice were significantly lower than those of WT mice. Long-term treatment with the ET
A
receptor antagonist TA-0201 (0.5 mg · kg
−1
· d
−1
) significantly ameliorated vascular stenosis in both groups. Long-term treatment with the ET
B
receptor antagonist A-192621 (30 mg · kg
−1
· d
−1
) worsened vascular remodeling in WT mice.

Conclusions—

We demonstrated that inhibition of the ET
B
receptor system is harmful for vascular remodeling after injury, the mechanism of which is partly attributed to decreased NO release, in KO mice. These results suggest that the overall effect of vascular ET
B
receptors is antiproliferative in the injured artery.
Time, Number, and History in the Maya World
Authors: Aveni Anthony
Published: October 2002

What better way to understand ourselves than to compare our habits, our customs, our behavior with those of another? This is the goal of anthropology: to comprehend our own culture by reflecting it from the mirror of otherness. When most effective its results can be unsettling. Consider the possibility of discovering other ways of knowing that challenge our own - that can even cause us to doubt whether the knowledge we hold dear really constitutes the whole of the matter. When it comes to the study of time there are few cultures, past or present, worth reflecting upon that match the ancient Maya of Yucatan. They have been characterized in their classical (AD 200-900) heyday as a people preoccupied with time, obsessed by time; they were worshipers of time: "The great theme of Maya civilization is the passage of time . . ." (Thompson 1954, p. 13). "The central importance of the calendar . . . and the central importance of religion to everything else conspire to make the history of [their] calendar something of a key to the general cultural history of the region." (Edmonson 1988, p. 4). "Nothing in man's life would be set apart as being unrelated to the realm of the destinies of time" (Leon Portilla 1989, p. 222). The study of Maya time offers us the added bonus that since all pre-Columbian cultures were hermetically sealed by two oceans from outside influence prior to Hispanic contact, whatever we may glean concerning the perception of time from its artifacts offers us the unique opportunity to seek cultural universals and to address specifically whether diverse civilizations might develop similar practices and ideas in their encounters with the problem of time. This essay examines the connections between time and history,with special emphasis upon the unusual role played by the concept of number, in the ancient Maya world.The resources for such a study are many and varied. I begin with a discussion of the content of the monumental inscriptions.A major focus of Mayanists since great advances in decoding the Maya script were made in the 1970's, most texts are carved on impressive stone stelae erected about the Maya ruins, well remembered by visitors to Tikal, Copan and Calakmul. I then move on to the esoteric world of the sacred books.Though scarcely a handful of them remain, they hold the keys to the deepest understanding of what time meant to the elite daykeepers who devised them. Along the way we supplement our understanding of these texts by referring to colonial period documents and ethnological studies of contemporary cultures descended from the ancient Maya. Here we discover a remarkable continuity of culture, which greatly illuminates our understanding of the Maya past.
The Procedure for Evaluating the Adsorption Energy Distribution from an Analysis of Thermodesorption Spectra Based on the Statistical Rate Theory
Authors: Panczyk Tomasz , Rudzinski Wladyslaw , Borowiecki Tadeusz , Dominko Anna
Published: October 2002

We have recently proposed a new method for evaluating the adsorption energy distribution function χ(ε) from the numerical analysis of thermodesorption spectra. This method is based on an application of the Statistical Rate Theory developed by Ward et al. (1982). In this paper, we present some simplifications of this method thereby allowing its ready application. Illustrative calculations for the nitrogen thermodesorption spectra from the surface of molecular sieve carbon fibres (MSCF) are presented.
Optimal Control of Aeroacoustic Noise Generated by Cylinder Vortex Interaction
Authors: Collis S.S. , Ghayour K. , Heinkenschloss M.
Published: October 2002

This paper presents an optimal control formulation and solution for an idealized Blade Vortex Interaction (BVI) problem. This problem consists of the interaction of an inviscid vortex pair with a circular cylinder in a steady Mach 0.3 uniform flow with wall-normal velocity used as control on the cylinder surface. This model problem captures the fundamental noise generation process of the BVI phenomena while mitigating many of the complexities of the full rotorcraft problem. The optimal control problem is solved using a gradient based method where gradient information is computed from a continuous adjoint analysis of the governing unsteady Euler equations. The BVI wave packet is targeted by defining an objective function that measures the square amplitude of pressure fluctuations in an observation region over a time interval of interest. When the observation region encloses the entire flow a 6 dB reduction in overall BVI noise is obtained. When the observation region is limited to the region of greatest BVI noise, a 13dB reduction is obtained. The optimal control, unlike most common mitigation methods, does not target the interaction directly — instead, the computed boundary control modulates the potential flow about the cylinder, producing a wave packet of the correct amplitude and phase to approximately cancel the BVI noise in the observation region.
Krogia coralloides, a new lichen genus and species from Mauritius
Authors: Timdal Einar
Published: October 2002

The new corticolous lichen genus Krogia and species K. coralloidesare described from humid forest in Mauritius. The genus shows affinities with Phyllopsora, but differs in characters of the ascus, ascospores, and thallus anatomy. The ascal characters make its inclusion in the Bacidiaceae or Phyllopsoraceae problematic. The lichen contains boninic acid and an apparently related compound.
Kroswia, a new genus in the Pannariaceae (lichenized ascomycetes)
Authors: Jørgensen Per M.
Published: October 2002

A characteristic, sterile lichen genus with homoiomerous thallus containing terpenoids is described, with one subtropical species, Kroswia crystalliferum sp. nov., occurring scattered in Africa from Kenya south to the Cape, southern India (with Sri Lanka) and Taiwan. Another temperate species, Kroswia gemmascens (Nyl.) comb, nov., is restricted to Eastern Asia. in spite of its gelatinous, homoiomerous thallus, the genus appears to belong to the Pannariaceae.
Holocene Relict Woodlands at the Eastern Canadian Treeline
Authors: Payette Serge , Morneau Claude
Published: October 2002

We present direct evidence for the relict nature of lichenspruce woodlands thriving at treeline, using 14C-dated stands growing in the humid climate of eastern Hudson Bay in northern Québec. Black spruce, Picea mariana (Mill.) BSP, forms two groups of relict stands: a Neoglacial group of postfire origin dating between 2000 and 900 yr B.P. and a pre-Neoglacial group most likely established between 4500 and 3200 yr B.P. The latter group shows no evidence of fire (absence of charcoal under topsoil organic horizon). The stands are exceptional because they probably are the direct lineages of the primeval forests that colonized the land sometime after deglaciation. The structure of the relict lichen-spruce communities gives strong support to the current thesis that considers lichen-spruce woodland as a self-perpetuating open forest, typical of the subarctic environment.
Climatic Implications of Macro- and Microfossil Assemblages from Late Pleistocene Deposits in Northern New Zealand
Authors: Ogden John , Newnham Rewi M. , Palmer Jonathan G. , Serra Richard G. , Mitchell Neil D.
Published: October 2002

Twenty-two plant species were identified from leaves, fruits, or flowers, and 41 taxa from pollen, present in a macrofossil (leaf) layer in a peat swamp formed on Pleistocene dunes on the Aupouri Peninsula in northern New Zealand. Eight genera of gymnosperms are represented. With the exception of Lagarostrobos colensoi, all tree species abundant as macrofossils are also common as pollen. Macrofossils enabled the on-site flora to be compared with the regional flora, represented by the pollen rain. Studies on leaf decomposition rates indicate bias toward sclerophyllous species in the macrofossils. Identification to species level and treering data from preserved kauri logs allow quantitative comparisons with similar extant communities. Current climatic conditions at those analogue sites are cooler (2° to 3°C), cloudier (11%), and much wetter (85%) than those currently prevailing on the Aupouri Peninsula. Dendrochronological results also suggest that the far north of New Zealand had a cooler, cloudier, and wetter climate at the time the fossil leaf assemblage was formed. Radiocarbon dates from possibly contaminated samples suggest that a diverse mixed gymnosperm/angiosperm forest, dominated by kauri (Agathis australis), was present about (or sometime before) 41,00034,000 yr B.P., when the leaf layer was formed. Similar temperature reductions have been postulated for this period in New Zealand by other authors.
Neoglacial Glacier Fluctuations in the Canadian Rockies
Authors: Luckman Brian H. , Holdsworth Gerald , Osborn Gerald D.
Published: October 2002

The Little Ice Age was the most extensive Neoglacial glacier advance in the Canadian Rockies. Evidence of earlier, less-extensive Neoglacial glacier advances is based on wood recovered from several glacier forefields. Wood flushed out of Athabasca Glacier (7550-8230 yr B.P., three dates) and Dome Glacier (6120-6380 yr B.P., two dates) indicates that forests occurred upvalley of present glacier termini during the Hypsithermal. Detrital logs from Peyto (14 dates), Saskatchewan (3 dates), Robson (3 dates), and Yoho (1 date) Glaciers, plus in situ slumps at Peyto and Robson Glaciers, have yielded 14 C dates between 2490 and 3300 yr B.P. (12 dates between 2800 and 2990). This wood is derived from sources at or upvalley from present glacier termini and represents forests overridden by glaciers between ca. 3100 and 2500 yr B.P. (Treeline was higher than present immediately prior to this advance.) This advance, which did not extend beyond the Little Ice Age maximum position, is designated the Peyto Advance and correlated with the Tiedemann Advance in western British Columbia. Earliest Little Ice Age advances at Peyto and Robson Glaciers are dated ca. 800-600 yr B.P. at positions ca. 500 m upvalley from Little Ice Age limits.
Pollen Response-Surface Estimates of Late-Quaternary Changes in the Moisture Balance of the Northeastern United States
Authors: Webb Robert S. , Anderson Katherine H. , Webb Thompson
Published: October 2002

Quantitative estimates of late-Quaternary climate in the northeastern United States are reconstructed from fossil pollen data to evaluate changes in the regional moisture balance inferred from water-level fluctuations. We use environmental response surfaces to calibrate modern pollen data (for 17 different taxa) to an index of effective soil moisture and mean annual precipitation. We apply these response surfaces to fossil pollen data from 60 sites in the region to reconstruct changes in soil moisture and mean annual precipitation at 3000-yr intervals from 12,000 yr B.P. to present. The mapped reconstructions of soil moisture and mean annual precipitation illustrate how the regional moisture balance of the Northeast may have changed over the last 12,000 yr in response to changing climate. Reconstructions of annual precipitation show a gradual increase from 30% below modern values at 12,000 yr B.P. to near-modern values by 6000 yr B.P. and then remain relatively constant thereafter. Reconstructed changes in the index of effective soil moisture, however, show a pattern of near-modern values at 12,000, 6000, and 3000 yr B.P., with significantly lower values estimated for 9000 yr B.P., the time of maximum pine pollen abundances in the Northeast. This pattern of change is similar to the change in regional moisture balance inferred from stratigraphic records of water-level fluctuations. These results confirm previous interpretations, based on records of water-level fluctuations, that conditions in the Northeast were significantly drier during the early to middle Holocene than at other times during the last 12,000 yr.
Transport Direction of Wisconsinan Loess in Southeastern Minnesota
Authors: Mason Joseph A. , Nater Edward A. , Hobbs Howard C.
Published: October 2002

A study of Wisconsinan loess in part of southeastern Minnesota confirms earlier suggestions that much of the loess in this region was not derived flora the floodplain of the Mississippi River. Two Wisconsinan loess units, the Peoria Loess and Roxana Silt, occur in the study area. Peoria Loess, 1-8 m thick, fines systematically eastward from an abrupt western border toward the Mississippi. There are no apparent grain-size trends away from other adjacent rivers. Peoria Loess thickness generally decreases eastward, but is highly variable, probably because of differential erosion. Potential sources for this unit are pre-Wisconsinan sediments on the Iowan Erosion Surface immediately west of the border of thick loess and Wisconsinan glacial sources tens or hundreds of kilometers to the west. The underlying Roxana Silt, up to 1 m thick, occurs only near the Mississippi and fines away from that river. The Roxana Silt deposit could reflect aggradation of the Mississippi floodplain because of glacial activity upstream and does not have clear implications for upland vegetation near the study area. By contrast, transport of the Peoria Loess from distant glacial sources or wind erosion of upland surfaces closer to the loess deposit both imply extensive, very sparsely vegetated surfaces west of the study area when the Peoria Loess accumulated.
Atmospheric Aerosol Loading and Transport Due to the 1783-84 Laki Eruption in Iceland, Interpreted from Ash Particles and Acidity in the GISP2 Ice Core
Authors: Fiacco R. Joseph , Thordarson Thorvaldur , Germani Mark S. , Self Stephen , Palais Julie M. , Whitlow Sallie , Grootes Peter M.
Published: October 2002

Glass shards from the A.D. 1783 Laki fissure eruption in Iceland have been identified in the GISP2 ice core from Summit, Greenland, at a level just preceding the major acidity/sulfate peak. Detailed reconstruction of ice stratigraphy, coupled with analyses of solid particles from filtered samples, indicate that a small amount of Laki ash was carried via atmospheric transport to Greenland in the summer of 1783, whereas the main aerosol precipitation occurred in the summer and early fall of 1784. Sulfate concentrations in the ice increase slightly during late summer and fall of 1783 and remain steady throughout the winter due to slow oxidation rates during this season in the Arctic. The sulfate concentration rises dramatically in the spring and summer of 1784, producing a massive sulfate peak, previously believed to have accumulated during the summer of 1783 and commonly used as the marker horizon in Greenland ice core studies. The chronology of ash and acid fallout at the GISP2 site suggests that a significant portion of the Laid eruption plume penetrated the tropopause and that aerosol generated from it remained aloft for at least 1 yr after the eruption. Based on comparisons with other glaciochemical seasonal indicators, abnormally cool conditions prevailed at Summit during the summer of 1784. This further supports the claim that a significant volume of sulfate aerosol remained in the Arctic middle atmosphere well after the eruption had ceased.
Abrupt Climatic Changes during the Last Glaciation Based on Pollen Analysis of the Abric Romani, Catalonia, Spain
Authors: Burjachs Francesc , Julià Ramon
Published: October 2002

The Abric Romani continental pollen record provides evidence of abrupt climate variations during the last glaciation. The pollen record reveals a pattern of high-frequency variations similar to that in ice cores as shown by oxygen isotopes or dust content. Analyses of 14 travertine samples yield coherent U-series ages in correct stratigraphic order, ranging from 40,000 to 70,000 yr. According to changes in the composition and structure of the vegetation, five paleoclimatic phases have been differentiated; the oldest, ranging from 70,200 to 65,500 yr ago, records thermophilous taxa which correspond to the last warm events of isotopic stage 5. The next phase, from 65,500 to 56,800 yr, records a cold, humid climate that correlates with isotope stage 4. During the third phase, from 56,800 to 49,500 yr, relatively warm and cold events alternate. The fourth phase, from 49,500 to 46,200 yr, records a cold, dry climate. The fifth phase, ranging from 46,200 to 40,800 yr, records a milder phase that is similar in appearance to the beginning of the Holocene.
Correlation of a Tephra Layer in Western Greece with a Late Pleistocene Eruption in the Campanian Province of Italy
Authors: St. Seymour Karen , Christanis Kimon
Published: October 2002

The Kalodiki fen is a 2-km2mire in a small basin within a tectonic depression in Epirus, western Greece. Since the last glaciation the basin has been occupied by a freshwater lake and has accumulated as much as 9 m of peat, which continues to form today. A 10-cm-thick, light-brown to olive fine sandy layer appears in cores at depths ranging from 2.9 to 5.7 m. The sand fraction of this layer consists mostly of pumice fragments and brown and colorless glass shards with similar major-element compositions, and it also contains crystal fragments of feldspars (mainly sanidine), ferromagnesian minerals, and probably sphene and apatite. The colorless glass has an index of refraction 1.519 ± 0.002. A sample of the overlying peat layer gave a minimum radiocarbon age of about 31,800 ± 1200 yr B.P. for the deposition of the tephra. The likely age of the tephra, its index of refraction, and its mineralogical and chemical characteristics display strong similarities to tephra from the Campanian province of Italy. Mineralogically similar tephra layers have also been reported from a peat deposit at Philippi, in northeastern Greece.
A 110,000-Yr Record of Explosive Volcanism from the GISP2 (Greenland) Ice Core
Authors: Zielinski Gregory A. , Mayewski Paul A. , Meeker L. David , Whitlow S. , Twickler Mark S.
Published: October 2002

The time series of volcanically produced sulfate from the GISP2 ice core is used to develop a continuous record of explosive volcanism over the past 110,000 yr. We identified ∼850 volcanic signals (700 of these from 110,000 to 9000 yr ago) with sulfate concentrations greater than that associated with historical eruptions from either equatorial or mid-latitude regions that are known to have perturbed global or Northern Hemisphere climate, respectively. This number is a minimum because decreasing sampling resolution with depth, source volcano location, variable circulation patterns at the time of the eruption, and post-depositional modification of the signal can result in an incomplete record. The largest and most abundant volcanic signals over the past 110,000 yr, even after accounting for lower sampling resolution in the earlier part of the record, occur between 17,000 and 6000 yr ago, during and following the last deglaciation. A second period of enhanced volcanism occurs 35,000–22,000 yr ago, leading up to and during the last glacial maximum. These findings further support a possible climate-forcing component in volcanism. Increased volcanism often occurs during stadial/interstadial transitions within the last glaciation, but this is not consistent over the entire cycle. Ages for some of the largest known eruptions 100,000–9000 yr ago closely correspond to individual sulfate peaks or groups of peaks in our record.
Vegetational History of a Site in the Central Amazon Basin Derived from Phytolith and Charcoal Records from Natural Soils
Authors: Piperno Dolores R. , Becker Peter
Published: October 2002

Analysis of phytoliths and macroscopic charcoal from natural soils near Manaus, Brazil shows that the central Amazonian terra firme forest has not been stable during the Holocene. Phytolith taxonomic composition and radiocarbon ages indicate that a closed forest has continuously existed in the area since at least 4600 yr B.P., but that forest composition and species abundance changed significantly sometime during the Holocene Epoch. There is no evidence that the vegetation experienced swidden cultivation. The distribution and dates of the charcoal in the soils indicate that forest fires between 1795 and 550 yr B.P. burned an area of about 200 hectares. Vegetational changes and fires appear to be a result of climatic drying that may have affected large areas of the Amazon Basin over the past 5000 to 7000 years. Soil phytolith analysis is a promising tool for the study of environmental history in the humid tropics and may reduce the previous dependence on lake and swamp sediments, at least for the Holocene Epoch.
Sea-Level Changes and δ18O Record for the Past 34,000 yr from Mayotte Reef, Indian Ocean
Authors: Colonna Michel , Casanova Joel , Dullo Wolf-Christian , Camoin Gilbert
Published: October 2002

New sea-level and δ18O curves for the past 34,000 yr, based on uranium–thorium chronology, are proposed for the southwestern part of the Indian Ocean. The archives include cores drilled from onshore coral reefs and submersed samples from foreslope corals of Mayotte in the Comoro Islands. The Mayotte sea-level curve shows a lowstand of 145 ± 5 m below the present level during the last glacial maximum dated at 18,400 yr. This lowstand is supported by the maximum18O enrichment in the coral colonies. The residual signal (Δδ18O), controlled by sea-surface temperature changes, indicates that surface waters 18,400 yr ago were approximately 5°C cooler than present. The deglacial sea-level rise is clearly recorded, with a mean rate of about 1.7 cm yr−1between 18,400 and 10,000 yr ago. The deglaciation phase is characterized by a strong18O depletion marked by two pulses related to meltwater discharges into the North Atlantic Ocean but also characterized by responses specific to the tropical Indian Ocean.
Paleomagnetic Investigation of Lake Lahontan Sediments and Its Application for Dating Pluvial Events in the Northwestern Great Basin
Authors: Liddicoat Joseph C. , Coe Robert S.
Published: October 2002

A comparison of paleomagnetic secular variation in sediment of Pleistocene Lake Lahontan in the northwestern Great Basin with secular variation in lake sediment in the Mono Basin, California, indicates that Lake Lahontan was in the valley of the Truckee River between Pyramid Lake and Wadsworth, Nevada, from about 19,000 to 13,000 yr B.P. The secular variation in older Lake Lahontan sediment in the Truckee River valley has the general features of secular variation in middle Pleistocene lacustrine sediments near Rye Patch Dam, Nevada, 125 km to the east. On the basis of field mapping and tephrochronology, the sections of older lacustrine sediments are not coeval. The apparent, but erroneous, correlation of those sediments emphasizes the need for multiple dating methods when paleomagnetic secular variation is used to date stratigraphy.
Climatic Reconstruction in Europe for 18,000 YR B.P. from Pollen Data
Authors: Peyron Odile , Guiot Joël , Cheddadi Rachid , Tarasov Pavel , Reille Maurice , de Beaulieu Jacques-Louis , Bottema Sytze , Andrieu Valérie
Published: October 2002

An improved concept of the best analogs method is used to reconstruct the climate of the last glacial maximum from pollen data in Europe. In order to deal with the lack of perfect analogs of fossil assemblages and therefore to obtain a more accurate climate reconstruction, we used a combination of pollen types grouped according to plant phenology and present climate constraints rather than pollen percentages for each individual taxon. The distribution of pollen taxa into plant functional types (PFTs) is aimed to reflect the vegetation in terms of biomes which have a wider distribution than a species. The climatic variables are then calibrated on these PFTs using an artificial neural network technique. The use of PFTs allowed us to deal with situations where pollen assemblages have only partial modern analogs. The method is applied to the glacial steppic vegetation in Europe, using 15 pollen records. North of the Pyrenees–Alps line, the reconstructed temperatures were lower than today: −30 ± 10°C for the temperature of the coldest month ( Tc) and −12 ± 3°C for the annual mean ( Tann). South of that line, Tc and Tann anomalies were respectively, −15 ± 5°C and −10 ± 5°C. The available moisture index and annual precipitation were also lower than present: −60 ± 20% north of Mediterranean Sea, (−800 ± 100 mm for precipitation). In Italy and Greece, the available moisture was 20% lower, with a precipitation anomaly of ca. −600 ± 200 mm. Southward, the moisture index was close to that at present (±20%), and precipitation was lower (−300 ± 300 mm).
Characterization and Palaeoecological Significance of Archaeological Charcoal Assemblages during Late and Post-Glacial Phases in Southern France
Authors: Heinz Christine , Thiébault Stéphanie
Published: October 2002

Archaeological sites at Abeurador and Font-Juvénal have produced extensive charcoal-rich horizons. The results of the charcoal analysis, based on the identification of woody species from anatomical features, contribute to the elaboration of plain phases within the development of vegetation in southern France. They are presented here in a new diagram and are interpreted as four major vegetation phases from 11,00014C yr B.P. to the recent past. In order to interpret the palaeoecological significance of the charcoal assemblages we have used multivariate analysis. The data base consists of 42 taxa and 48 archaeological levels. The division into four vegetation phases based on analytical interpretation is complemented by the more synthetic interpretation based on correspondence factor analysis (CFA). The results reveal the patterns of the vegetation history over the last 11 millennia, each being characterized by a key plant species.
Continental Oxygen Isotopic Record of the Last 170,000 Years in Jerusalem
Authors: Frumkin Amos , Ford Derek C. , Schwarcz Henry P.
Published: October 2002

A long radiometrically dated oxygen isotopic record of continental climatic variations since the penultimate glaciation was obtained from a stalagmite deposited in a sealed cave in Jerusalem. This record shows that speleothems have the potential of assigning dates to long- and short-term climatic events, with possible refining of Milankovitch tuning of ice and marine records which themselves are not datable. Short-term (∼1000-yr) events are very significant in the region, reaching ∼50% of glacial/interglacial fluctuations. The Mediterranean Sea was the most probable source of local precipitation throughout the last glacial cycle.
Interaction of ALG‐2 with ASK1 influences ASK1 localization and subsequent JNK activation
Authors: Hwang In-Sik , Jung Yong-Sam , Kim Eunhee
Published: October 2002

ALG‐2 (apoptosis linked gene‐2) is an essential protein for the execution of apoptosis whose function is largely unknown. Here, we demonstrate that ALG‐2 could interact with the C‐terminus (amino acids 941–1375) of the apoptosis signal‐regulating kinase 1 (ASK1) in BOSC23 cells as well as in vitro. ASK1 failed to bind to an isotype of ALG‐2 found in the liver, ALG‐2,1, in which two amino acids (Gly‐121 and Phe‐122) are deleted. This implies that the interaction is very specific. Cotransfection with ALG‐2 resulted in the nuclear presence of ASK1 and inhibited the activation of c‐Jun N‐terminal kinase (JNK) by ASK1 in BOSC23 cells. This study reports that ALG‐2 could regulate the subcellular localization and the JNK activity modulation of ASK1 by direct interaction.
H2O2 generation during the auto‐oxidation of coniferyl alcohol drives the oxidase activity of a highly conserved class III peroxidase involved in lignin biosynthesis
Authors: Pomar Federico , Caballero Nuria , Pedreño Marı́a A , Ros Barceló A
Published: October 2002

Characterization of lignified Zinnia elegans hypocotyls by both alkaline nitrobenzene oxidation and thioacidolysis reveals that coniferyl alcohol units are mainly found as part of 4‐O‐linked end groups and aryl‐glycerol‐β‐aryl ether (β‐O‐4) structures. Z. elegans hypocotyls also contain a basic peroxidase (EC 1.11.1.7) capable of oxidizing coniferyl alcohol in the absence of H2O2. Results showed that the oxidase activity of the Z. elegans basic peroxidase is stimulated by superoxide dismutase, and inhibited by catalase and anaerobic conditions. Results also showed that the oxidase activity of this peroxidase is due to an evolutionarily gained optimal adaptation of the enzyme to the μM H2O2 concentrations generated during the auto‐oxidation of coniferyl alcohol, the stoichiometry of the chemical reaction (mol coniferyl alcohol auto‐oxidized/mol H2O2 formed) being 0.496. These results therefore suggest that the H2O2 generated during the auto‐oxidation of coniferyl alcohol is the main factor that drives the unusual oxidase activity of this highly conserved lignin‐synthesizing class III peroxidase.