bluuebunny/crossref_metadata_2025 huggingface dataset:
COMPACTLY-ALIGNED DISCRETE PRODUCT SYSTEMS, AND GENERALIZATIONS OF ${\mathcal O}_\infty$
Authors: FOWLER NEAL J.
Published: September 2002

The universal C*-algebras of discrete product systems generalize the Toeplitz–Cuntz algebras and the Toeplitz algebras of discrete semigroups. We consider a semigroup P which is quasi-lattice ordered in the sense of Nica, and, for a product system p : E→ P, we study those representations of E, called covariant, which respect the lattice structure of P. We identify a class of product systems, which we call compactly aligned, for which there is a purely C*-algebraic characterization of covariance, and study the algebra [Formula: see text] which is universal for covariant representations of E. Our main theorem is a characterization of the faithful representations of [Formula: see text] when P is the positive cone of a free product of totally-ordered amenable groups.
ON DISCONTINUITY OF THE BERGMAN KERNEL FUNCTION
Authors: DIEDERICH KLAS , HERBORT GREGOR
Published: September 2002

Let [Formula: see text] be a Ck-smoothly (with k≥1) bounded pseudoconvex domain and [Formula: see text] denote its Bergman kernel function. In this article the question is investigated, whether the function [Formula: see text] is continuous up to the boundary in the topology of the extended real line [Formula: see text]. We give two counterexamples: one in the class of finite type domains with k = ∞ and one in the class of convex domains with k = 1.
CR-MEROMORPHIC EXTENSION AND THE NONEMBEDDABILITY OF THE ANDREOTTI–ROSSI CR STRUCTURE IN THE PROJECTIVE SPACE
Authors: SARKIS FRÉDÉRIC
Published: September 2002

Let [Formula: see text] be a polynomially convex compact set and let M be a (2p-1) dimensional (p ≥ 2) maximally complex bounded scarred C1 submanifold of [Formula: see text], irreducible in the current sense. According to Harvey–Lawson [14] and Chirka [4], there exists a bounded irreducible analytic set [Formula: see text] such that [M]=±d[T]. In this paper, we prove that every CR-meromorphic map carrying M into a projective manifold V extends to a meromorphic map F:T → V. We extend the notion of CR-meromorphic maps to CR submanifolds of [Formula: see text] and give another proof of our extension theorem which extends to the greater codimensional case. We also apply our extension result to prove a Lewy type extension theorem for CR-meromorphic maps, a Hartogs type theorem in [Formula: see text] and the non embedding of the Andreotti–Rossi CR structure in [Formula: see text].
THERMODYNAMICS OF ANISOTROPIC-GAP AND MULTIBAND CLEAN BCS SUPERCONDUCTORS
Authors: MISHONOV TODOR , PENEV EVGENI
Published: September 2002

The free energy, non-gradient terms of the Ginzburg–Landau (GL) expansion, and the jump of the specific heat of a multiband anisotropic-gap BCS superconductor are derived in the framework of a separable-kernel approximation. Results for a two-band superconductor, d-wave superconductor, and some recent models for MgB 2 are worked out as special cases of the general approach. The classical results for the GL coefficients are derived in a simple way, directly from the general expression for the free energy of a BCS superconductor.
ELECTRON-PHONON INTERACTION AND PHONON RESPONSE IN HEAVY FERMION SYSTEMS
Authors: NAYAK P. , OJHA B. , MOHANTY S. , BEHERA S. N.
Published: September 2002

The phonon response property of the Heavy Fermion (HF) systems are investigated within the Periodic Anderson Model (PAM) to explain the observed phonon anomalies. To understand the microscopic origin of these anomalies, two different mechanisms of electron-phonon interaction, namely, the usual interaction between the phonons and the electrons in the f-bands as well as the interaction due to the hybridization term of PAM, are considered. The influence of coulomb correlation U on the phonon excitation spectrum and the spectral density function are studied for various model parameters, namely, the position of the f-level E0, the ratio r of the electron-phonon coupling strengths f1(q) and f2(q), and the effective coupling strength g. The numerical evaluations of these phonon response functions are carried out for small temperatures in the long wavelength limit, while retaining terms which are linear in correlation. The observed behavior agrees well with the general features obtained in experiment.
TUNNELING EFFECT OF COOPER PAIRS IN A SUPERCONDUCTOR-INSULATOR-SUPERCONDUCTOR-INSULATOR-SUPERCONDUCTOR STRUCTURE
Authors: MEI T.
Published: September 2002

The tunneling effect of the Cooper pairs in a superconductor-insulator-superconductor-insulator-superconductor structure is analyzed by Feynman-like method, and the equations describing the electric current are obtained. For the case when both junctions are in the zero voltage state, the exact solution of the equations is obtained. It is found that, because of the tunneling effect of the Cooper pairs, an alternating current exists which can be expressed by an elliptic function. And then, on second thoughts, the conclusion that the SISIS cannot emit electromagnetic radiation when both junctions are in the zero voltage state, though an alternating current exists, is pointed out.
SHAPE-BASED IMAGE RETRIEVAL APPLIED TO TRADEMARK IMAGES
Authors: EL BADAWY OSSAMA , KAMEL MOHAMED
Published: September 2002

We propose a new shape-based, query-by-example, image database retrieval method that is able to match a query image to one of the images in the database, based on a whole or partial match. The proposed method has two key components: the architecture of the retrieval and the features used. Both play a role in the overall retrieval efficacy. The proposed architecture is based on the analysis of connected components and holes in the query and database images. The features we propose to use are geometric in nature, and are invariant to translation, rotation and scale. Each of the suggested three features is not new per se, but combining them to produce a compact and efficient feature vector is. We use hand-sketched, rotated and scaled query images to test the proposed method using a database of 500 logo images. We compare the performance of the suggested features with the performance of the moment invariants (a set of commonly-used shape features). The suggested features match the moment invariants in rotated and scaled queries and consistently surpass them in hand-sketched queries. Moreover, results clearly show that the proposed architecture significantly increases the performance of the two feature sets.
AN OBJECT-ORIENTED BSP TREE ALGORITHM FOR HIDDEN SURFACE REMOVAL
Authors: WANG TAEHYUNG , SHEU PHILLIP C. Y.
Published: September 2002

Since the BSP tree algorithm was introduced, many extended or applied algorithms for the original BSP tree algorithm have been reported. Most of the previous work dealt with polygons that are components of polyhedra. If a scene consists of many polyhedra and they are allowed to move, the management cost of a BSP tree becomes expensive and the size of the tree becomes large. This paper presents an object-oriented BSP tree algorithm that can more efficiently deal with a large number of moving polyhedra.
The incidence of venous thromboembolism in thrombophilic children: a prospective cohort study
Authors: Tormene Daniela , Simioni Paolo , Prandoni Paolo , Franz Francesca , Zerbinati Patrizia , Tognin Giulio , Girolami Antonio
Published: September 2002

Antithrombin and protein C and S defects, factor V Leiden mutation, and G20210A prothrombin gene mutation are well-recognized risk factors for venous thromboembolism (VTE) in adults, especially during circumstantial situations such as trauma, immobilization, surgery, or oral contraceptive treatment. The relevance of these defects in predisposing children to VTE is still undefined. In a prospective cohort study we assessed the incidence of spontaneous and risk period–related VTE in asymptomatic children (aged 1-14 years), who were family members of a proband with an objectively diagnosed venous thromboembolic event and a documented single thrombophilic abnormality. We enrolled 143 children from 63 families. Of them, 81 (56.6%) were carriers of an inherited defect, whereas the remaining 62 were free from known genetic or acquired causes of thrombophilia. The mean observation period was 5 years (range, 1-8 years) in each group. Thirty-one risk periods occurred in the carriers group and 20 in noncarriers. Neither spontaneous nor risk period–related VTE occurred in either group during 395 and 296 observation years, respectively. However, circumstances where most of the pediatric thromboses occur (insertion of central venous lines, cancer, and cardiovascular surgery) were not encountered. In conclusion, the thrombotic risk in otherwise healthy children with a single identified thrombophilic defect appears to be very low. Common triggering conditions for VTE in thrombophilic adults do not seem to increase the thrombotic risk in children carrying the same inherited defect. Accordingly, screening for thrombophilia in otherwise healthy children younger than 15 years who belong to families with inherited defects predisposing to thrombosis seems unjustified.
Dendritic cells for NK/LAK activation: rationale for multicellular immunotherapy in neuroblastoma patients
Authors: Valteau-Couanet Dominique , Leboulaire Christophe , Maincent Kim , Tournier Muriel , Hartmann Olivier , Bénard Jean , Beaujean Françoise , Boccaccio Catherine , Zitvogel Laurence , Angevin Eric
Published: September 2002

Natural killer (NK)/lymphokine-activated killer (LAK) cell-based immunotherapy could be beneficial against major histocompatibility complex class I–negative tumor residual disease such as neuroblastoma (NB), provided that interleukin 2 (IL-2) or surrogate nontoxic NK cell stimulatory factors could sustain NK cell activation and survival in vivo. Here we show that human monocyte–derived dendritic cells (MD-DCs) promote potent NK/LAK effector functions and long-term survival, circumventing the need for IL-2. This study demonstrates (1) the feasibility of differentiating granulocyte colony-stimulating factor–mobilized hematopoietic peripheral blood stem cells (PBSCs) into high numbers of functional MD-DCs and NK/LAK cells in a series of 12 children with stage 4 neuroblastoma (NB); (2) potent DC-mediated NK cell activation in autologous settings; (3) the reciprocal capacity of NK/LAK cells to turn immature DCs into maturing cells electively capable of triggering NK cell functions; and (4) the unique capacity of maturing DCs to sustain NK cell survival, superior to that achieved in IL-2. These data show a reciprocal interaction between DCs and NK/LAK cells, leading to the amplification of NK cell effector functions, and support the implementation of DC/NK cell–based immunotherapy for purging the graft and/or controlling minimal residual disease after autologous stem cell transplantation.
Expression of Vascular Endothelial Growth/Permeability Factor by Endometrial Glandular Epithelial and Stromal Cells in Baboons during the Menstrual Cycle and after Ovariectomy
Authors: Niklaus Andrea L. , Babischkin Jeffery S. , Aberdeen Graham W. , Pepe Gerald J. , Albrecht Eugene D.
Published: September 2002

Vascular endothelial growth/permeability factor (VEG/PF) has a crucial role in angiogenesis, and neovascularization is essential in preparing the uterine endometrium for implantation. However, the regulation of VEG/PF synthesis by particular cell types of the endometrium during the human menstrual cycle is not well understood. Therefore, in the present study the baboon was used as a nonhuman primate to determine the role of the ovary in vivo in endometrial VEG/PF expression. VEG/PF mRNA levels were quantified by competitive RT-PCR in whole uterine endometrium and in glandular epithelial and stromal cells isolated from the endometrium by laser capture microdissection of baboons during the normal menstrual cycle and after ovariectomy, which decreased serum estradiol and progesterone to undetectable levels. Mean (±se) levels (attomoles per micrograms of total RNA) of the 323-bp VEG/PF mRNA product, which reflected collective expression of all VEG/PF isoforms, in whole endometrium were 785 and 727 ± 158 during the mid and late follicular phases, respectively, and 1108 ± 320 during the midcycle surge in serum estradiol. VEG/PF mRNA levels then declined briefly before increasing to 1029 ± 365 attomoles/μg RNA during the late luteal phase of the menstrual cycle. VEG/PF mRNA levels (attomoles per femtomole of 18S rRNA) were similar in glandular epithelial (2.27 ± 1.11) and stromal (2.54 ± 0.70) cells at the midcycle estradiol peak and the midluteal phase of the menstrual cycle (2.34 ± 1.30 and 1.49 ± 0.53, respectively). Immunocytochemical expression of VEG/PF protein was abundant in glandular and luminal epithelium, stroma, and vascular endothelium. Endometrial vessel density and percent vascularized area, determined by morphometric image analysis, were similar during the various stages of the baboon menstrual cycle. After ovariectomy, VEG/PF mRNA levels (attomoles per femtomole of 18S rRNA) in the endometrial glands (0.52 ± 0.21) and stroma (0.22 ± 0.11) were decreased to values that were approximately 20% and 10% (P < 0.05), respectively, of those in intact baboons during the midcycle estrogen surge. Moreover, there was relatively little VEG/PF protein immunostaining in the endometrial glands, stroma, and vascular endothelium after ovariectomy.

In summary, VEG/PF mRNA and protein expression in glandular epithelial and stromal cells were markedly suppressed after ovariectomy, indicating that synthesis of this angiogenic factor in these endometrial cells is dependent upon a product(s) secreted by the ovary. Moreover, endometrial VEG/PF expression remained relatively constant and thus was available as a component of the angiogenic system throughout the menstrual cycle, presumably to progressively promote vascular reconstruction of the endometrium.
Lecanora Vacillans H. Magn., a Remarkable Species and its Taxonomic Significance
Authors: Lumbsch H. Thorsten , Guderley Roland
Published: September 2002

The anatomy and chemistry of Lecanora vacillans H. Magn. has been studied. This saxicolous species combines key characters of both the L. subfusca and L. subcarnea groups and indicates that the representative groups should not be segregated at generic level. More particularly L. vacillans resembles the L. subfusca group in its apothecial anatomy but contains chemical substances typical of the L. subcamea group, whereas the morphology is reminiscent of both groups. Lecanora vacillans f. infuscate is reduced to synonymy with L. vacillans.
Inhibition of Fungal Growth by Water Extracts from the Lichen Nephroma Arcticum
Authors: Land Carl Johan , Lundström Hans
Published: September 2002

Water extracts from Nephroma arcticum were prepared and tested for inhibitory effects against various yeast, mould, blue-stain and rot fungi. A water extract from Peltigera aphthosa was used as a reference. Two different diffusion assays were used, wells (cupplate method) and droplets (drop-plate method). For the majority of fungi studied using the former method there were clear zones with a sharp boundary (fungicidal effect), whereas the latter method yielded more or less hazy zones with inhibition or reduction in growth (fungistatic effect). No clear or hazy zones were seen with the extract from P. aphthosa. For Candida glabrata E, Saccharomyces cerevisiae K and Hormonema dematioides S there were clear zones for both methods. The MIC (Minimum Inhibitory Concentration) values were determined in liquid medium for S. cerevisiae K and C. glabrata E and were, respectively, 1 and 10 mg ml−1 of a crude extract from N. arcticum. The MFC (Minimum Fungicidal Concentration) values were found to be identical to the MIC values.
The Genus Fulgensia A. Massal. & De Not., a Diverse Group in the Teloschistaceae
Authors: Westberg Martin , Kärnefelt Ingvar
Published: September 2002

The morphology and the anatomy of the 13 species presently included in the genus Fulgensia were surveyed. Caloplaca aurea and C. paulii, two speciesregarded as closely related to Fulgensia by earlier authors, were also included in the study. Fulgensia was found to exhibit a great variation in both morphology and anatomy. The differences in size, shape and septation of the spores, in the anatomy of cortex and exciple, and in the gross morphology, will presumably motivate a different taxonomic treatment in the future. A tentative separation of the species into four different groups is proposed here. Group A comprises F. australis and F. chanousiae, which appear close to species in Caloplaca sect. Gasparrinia. Groups B and C, each comprises one species, F. schistidii and F. canariensis respectively and group D comprises the remaining nine species, including the type species F. fulgens. The last group may be further split by a more detailed investigation. The present separation of Fulgensia into two subgenera cannot be regarded as taxonomically sound. The genus is probably polyphyletic and the different groups are probably related to different groups within the large genus Caloplaca.
Peltigera Phyllidiosa (Peltigeraceae, Ascomycotina), A New Species from the Southern Appalachians Corroborated by its Sequences
Authors: Goffinet B. , Miadlikowska J.
Published: September 2002

The new species Peltigera phyllidiosa Goffinet & Miadlikowska from the Southern Appalachians, eastern U.S.A., is closely related to P. collina and P. neckeri. Like these species it has a glabrous upper cortex and black fingernail- or saddleshaped apothecial discs, but differs in its laminal phyllidia. Variation in nucleotide sequences of the Internal Transcribed Spacer (ITS) of the nrDNA repeat region correlates with the presence or absence of phyllidia, supporting the distinction of P. phyllidiosa from P. collina and P. neckeri.
Alternative Methods of extracting and Amplifying Dna from lichens
Authors: Martín Maria P. , Winka Katarina
Published: September 2002

We have investigated whether DNA extraction protocols designed specifically for fungi and/or lichens perform better on lichens than do corresponding protocols designed for plants and insects. Two different PCR-amplification protocols were used to evaluate the quality of the DNA extracted with each method. The DNA extractions with highest quality were obtained with the protocols designed for insects and plants, and the most successful amplifications were obtained with Ready-To-Go PCR Beads. This indicates that fungal or lichen specific protocols might not be necessary for successful extraction of high quality DNA from lichens.
The Sorediate Punctelia Species With lecanoric Acid in Europe
Authors: van Herk Kok , Aptroot André
Published: September 2002

A revision is presented of the sorediate, lecanoric acid-containing Punctelia species occurring in Europe. Two species are common in western andcentral Europe, viz. Punctelia subrudecta s. str. and Punctelia ulophylla comb. nov.They differ in several morphological characters, most notably in the colour andpruinosity of the margin. Both species occur sympatrically, often together on onetree. A third species, Punctelia perreticulata, is known in Europe only from the Mediterranean.
Lichenochora Mediterraneae (phyllacorales, Ascomycota) a new Lichenicolous Fungus from Spain
Authors: Calatayud Vicent , Navarro-Rosinés Pere , Calvo Esperanza
Published: September 2002

Lichenochora mediterraneae Calatayud, Nav.-Ros & E. Calvo (Phyllachorales)a new species of non-lichenized lichenicolous fungi, is described from the provinces of Cádiz and León (Spain)growing on Fuscopannaria mediterranea. is mainly characterised by having bispored asci, and 3–4-septate, narrowly cylindrical or bacilliform spores. The new species is compared with L. clauzadei and L. bellemerei, the two previously known species with pluriseptate spores.
The Identity of Buellia Ericina (Nyl.) Jatta and Its Generic Position
Authors: Giralt Mireia
Published: September 2002

The study of the type material of Buellia ericina (Nyl.) Jatta has revealed that this species is characterized by the same diagnostic characters as Rinodina madeirensis Kalb & Hafellner, and both taxa are here considered to be conspecific. The generic position of Buellia ericina is discussed and it is concluded that the species is better placed within the genus Rinodina (Ach.) Gray. New chemical data on this taxon are provided, and its sorediate variety, R. ericina var. boomii, is described as new from Portugal. Its closest affinities are shown to be with Rinodina kalbii Giralt & Matzer and probably also R. insularis (Arnold) Hafellner.This group stands apart in the family Physciaceae. It shows affinities with Diploicia A. Massal. and is included provisionally in Rinodina.
Verrucaria Elaeina, A Misunderstood European Lichen
Authors: Orange Alan
Published: September 2002

Verrucaria elaeina Borrer is a misunderstood species of shaded which is widespread in the British Isles. It resembles the freshwater species V. praetermissa, but differs in the more prominent perithecia, the lack of a layer, the slightly smaller ascospores, and the lack of a perispore.
Fellhanera Ochracea, a New Corticolous Lichen Species From Sheltered Habitats in Western Europe
Authors: Sparrius Laurens , Aptroot André
Published: September 2002

Fellhanera ochracea Sparrius & Aptroot is described from material found in sheltered habitats in Great Britain, Switzerland and The Netherlands, where it grows on acidic and neutral bark of, for example Pinus, Pseudotsuga, Ulmus, Quercus, Acer, Hedera and Sambucus. The species is close to Fellhanera subtilis and Fellhaneropsis myrtillicola, but distinguished by the abundant tiny, pale or orange-brown pigmented frequently discolouring to bluish green conidiomata with paler centrum, containing small, pyriform conidia, and by the 3-septate ascospores and the absence of lichen products in the thallus. A key to Fellhanera and Fellhaneropsis species known from western Europe is provided.
Thyrea Porphyrella, a new Species of the Lichinaceae from inselbergs in tropical South America
Authors: Schultz M. , Büdel B. , Porembski S.
Published: September 2002

The new species Thyrea porphyrella Schultz, Büdel & Porembski, in the Lichinaceae, is described from tropical South America. It grows on granite inselbergs in SE Brazil and in southern Guyana. Diagnostic characters are the very thin, superficially smooth but conspicuously uneven to folded thallus lobes of reddish-brown to crimson colour.
Two New Sorediate Species of Lichens in the Catillariaceae from the Iberian Peninsula
Authors: van den Boom P. P. G. , J. Etayo
Published: September 2002

Two new species of lichens are described from the Iberian Peninsula. Halecania giraltiae is the first sorediate saxicolous species known in the genus and has been collected growing on lichens and sometimes directly on rock in localities from northern Portugal to central Spain. Catillaria fungoides, a sorediate, corticolous representative of the C. nigroclavata group, is known from southern Portugal and northern Spain.
The Lichen Flora of Coastal Saline Lagoons in England
Authors: Gilbert Oliver
Published: September 2002

The lichen flora associated with twenty saline lagoons in England is described. Though often scarce, lichens were present on shingle, miscellaneous stones, half-submerged concrete structures, retaining walls, salt marsh vegetation, wooden posts, and strand-line materials. Sites that had been modified by the activity of man often held richer assemblages than ones in a more natural condition. The lichen flora is a mixture of common-place species and maritime specialists. The large lagoon behind Chesil Beach, known as ‘The Fleet’, was the most important site surveyed. Many of the marine lichens present are typical of very sheltered coastlines. Caloplaca suaedae, found at two sites, is described as new to science.
Lepraria atlantica, a new species from the British Isles
Authors: Orange Alan
Published: September 2002

Lepraria atlantica is described as new from acidic rocks in the British Isles; it contains porphyrilic acid, cf. rangiformic acid or rarely cf. roccellic acid, and atranorin. It differs from L. cacumimim in the diffuse, powdery thallus. It is morphologically similar to L. jackii, but differs in the possession of porphyrilic acid.
Aminostratigraphic Relations and Age of Quaternary Deposits, Northern Española Basin, New Mexico
Authors: Dethier David P. , McCoy William D.
Published: September 2002

Amino acid ratios of gastropods provide a useful basis for correlation and approximate dating of middle to late Quaternary fluvial deposits from the northern Española basin, New Mexico. Sparsely fossiliferous slackwater deposits in the Rio Chama-Rio Grande floodplain were buried episodically by piedmont alluvium during periods of climatic change as the axial river system cut down 120 m during the past 620,000 yr. Alloisoleucine/isoleucine (alle/Ile) ratios in the total hydrolysate and free fraction of amino acids in Succinea and Vallonia are strongly correlated with elevation. Ratios in Succinea range from 0.01 to 0.79 in the total hydrolysate and from 0.00 to 1.15 in the free fraction for deposits that range in age from modern to ⩾620,000 yr old. Amino acid ratios are tightly clustered for deposits that contain the 620,000-yr-old Lava Creek B tephra layer, demonstrating their utility for correlation and providing a calibration point for a local dating curve. Two 14C ages from younger deposits and limiting ages for erosion surfaces that lie above gastropod-bearing units tend to support the validity of much of the curve. Combining the dating curve with the geologic constraints suggests that aggradation events, separated by episodes of net incision, occurred at about 620,000, 310,000 ± 70,000, 170,000 ± 40,000, 95,000 ± 15,000 yr ago, after 19,000 yr ago, and during two minor periods between 80,000 and 25,000 yr ago.
Delayed Postglacial Uplift and Synglacial Sea Levels in Coastal Central New England
Authors: Koteff Carl , Robinson Gilpin R. , Goldsmith Richard , Thompson Woodrow B.
Published: September 2002

The postglacial uplift pattern indicated by elevations of ice-marginal glaciomarine deltas in coastal New England, deposited between approximately 15,000 and 14,000 yr B.P. during ice retreat from northeastern Massachusetts into southwestern Maine, is very similar to that previously recorded for glaciolacustrine deltas of similar age from inland areas of New England. Multiple regression analyses of elevations from both sets of deltas show an extremely close fit to tilted flat surfaces that rise 0.852 m/km to the N 28.5°W along the coast and 0.889 m/km to the N 20.5°W in western New England. The close similarity of uplift pattern in areas where elevation data are from different base-level media, along with additional shore-line evidence, indicates (1) that both areas are part of the same crustal postglacial uplift block, (2) that postglacial uplift was delayed until after 14,000 yr B.P., and (3) that little or no eustatic sea-level change occurred between 15,000 and 14,000 yr B.P., during which time the margin of the late Wisconsinan Laurentide ice sheet retreated about 100 km from Boston, Massachusetts, into southwestern Maine. Elevation data from even younger glaciomarine deltas in the coastal area indicate that soon after the ice margin reached southwestern Maine and adjacent New Hampshire (ca, 14,000 yr B.P.), eustatic sea level rose rapidly 7-10 m during the time that the ice margin retreated 5-10 km, which may have occurred during an interval of only 50-100 yr, Our new data not only confirm the delayed postglacial uplift model previously described for western New England, but also indicate that little or no eustatic sea-level change occurred during a substantial period of early deglaciation. However, at about 14,000 yr B.P., sea level rose rapidly. Postglacial uplift in the region apparently began between 14,000 and 13,300 yr B.P., before the retreating ice margin reached eastern Maine.
Pollen-Derived Rainfall and Temperature Estimates from Lake Tanganyika and Their Implication for Late Pleistocene Water Levels
Authors: Vincens Annie , Chalié Françoise , Bonnefille Raymonde , Guiot Joel , Tiercelin Jean-Jacques
Published: September 2002

Palaeoclimatic estimates of mean annual temperature and rainfall in the southern Tanganyika basin between 25,000 and 9000 yr B.P. have been established from two pollen sequences based on the best-analogue method. The results give evidence of a mean temperature decrease of about 4.2°C during the last glaciation, a value consistent with that previously obtained in the catchment area on the Burundi Highlands. This cooling was synchronous with a decrease of mean annual precipitation of about 180 mm/yr. Postglacial climatic conditions were established by 12,700 yr B.P., with warming and wetness continuing to increase from this date onward. These new palaeoclimatic data will be useful for hydrological reconstructions of Lake Tanganyika, particularly during the last glacial age for which the magnitude of water-level fall has been a controversial issue; our rainfall estimates are more consistent with low values (-250 to -300 m fall) than with high ones (-600 m) previously proposed.
Paleoclimatic Inferences from a 120,000-Yr Calcite Record of Water-Table Fluctuation in Browns Room of Devils Hole, Nevada
Authors: Szabo Barney J. , Kolesar Peter T. , Riggs Alan C. , Winograd Issac J. , Ludwig Kenneth R.
Published: September 2002

The petrographic and morphologic differences between calcite precipitated below, at, or above the present water table and uranium-series dating were used to reconstruct a chronology of water-table fluctuation for the past 120,000 yr in Browns Room, a subterranean air-filled chamber of Devils Hole fissure adjacent to the discharge area of the large Ash Meadows groundwater flow system in southern Nevada. The water table was more than 5 m above present level between about 116,000 and 53,000 yr ago, fluctuated between about +5 and +9 m during the period between about 44,000 and 20,000 yr ago, and declined rapidly from +9 to its present level during the past 20,000 yr. Because the Ash Meadows groundwater basin is greater than 12,000 km2in extent, these documented water-table fluctuations are likely to be of regional significance. Although different in detail, water-level fluctuation recorded by Browns Room calcites generally correlate with other Great Basin proxy palcoclimatic data.
Holocene Paleoecology of an Estuary on Santa Rosa Island, California
Authors: Cole Kenneth L. , Liu Geng-Wu
Published: September 2002

The middle to late Holocene history and early Anglo-European settlement impacts on Santa Rosa Island, California, were studied through the analysis of sediments in a small estuarine marsh. A 5.4-m-long sediment core produced a stratigraphic and pollen record spanning the last 5200 yr. Three major zones are distinguishable in the core. The lowermost zone (5200 to 3250 yr B.P.) represents a time of arid climate with predominantly marine sediment input and high Chenopodiaceae andAmbrosiapollen values. The intermediate zone (3250 yr B.P. to 1800 A.D.) is characterized by greater fresh water input and high values for Asteraceae and Cyperaceae pollen and charcoal particles. The uppermost zone (1800 A.D. to present) documents the unprecedented erosion, sedimentation, and vegetation change that resulted from the introduction of large exotic herbivores and exotic plants to the island during Anglo-European settlement. The identification of pollen grains of Torrey Pine (Pinus torreyana) documents the persistence of this endemic species on the island throughout the middle to late Holocene.
Extent and Timing of the Last Glacial Maximum in Southwestern Alaska
Authors: Mann Daniel H. , Peteet Dorothy M.
Published: September 2002

A glacier complex composed of confluent alpine glaciers, island ice caps, and piedmont lobes covered much of the Alaska Peninsula and Kodiak Island during the last glacial maximum (LGM). Because this glacier complex formed the southeastern border of Beringia, its dynamics may have been important in the timing and feasibility of the northwest coast route for human migration into lower-latitude North America. Radiocarbon dates from stratigraphic sections on Kodiak Island and in the Bristol Bay lowlands bracket the LGM in southwestern Alaska between 23,000 and 14,700 yr B.P. Reconstruction of ice thickness based on glacier trimlines, moraines, and calculations of basal-shear stress depict the Alaska Peninsula Glacier Complex flowing to the outer edge of the continental shelf in the Gulf of Alaska. Equilibrium-line altitudes (ELAs) were 300 to 700 m lower than today and approached sea level on the southwestern Alaska Peninsula. In northeastern areas where ELAs were higher, bedrock topography largely controlled ice flow except where ice saddles bridged straits and inlets.
Development and Environmental Significance of an Eolian Sand Ramp of Last-Glacial Age, Central Iran
Authors: Thomas David S.G. , Bateman Mark D. , Mehrshahi Daryoush , O'Hara Sarah L.
Published: September 2002

A 25-m-thick section of mostly eolian sediment is exposed in the stream-cut flank of a sand ramp accumulated in a mountain saddle near Ardakan playa, central Iran. The well-sorted eolian sediments of the ramp contain talus beds and incipient paleosols. Morphology and bedding structures imply that southeasterly winds were primarily responsible for deposition of the eolian sand. Optical dating shows that the sand was deposited near the last glacial maximum within about 5000 yr. Surface stabilization, lack of surface scree, and the development of a stream cut between the mountain and the ramp show that sediment accumulation ceased after this time. The Siberian high pressure system may have been established over central Iran during the last glacial maximum, causing cooler temperatures and a prevalence of southeasterly winds. These colder, windier conditions would have led to frost shattering and eolian transport, both of which are not significant processes today but which are evident as past processes from the ramp sediments.
Paleobiology of the Sand Beneath the Valders Diamicton at Valders, Wisconsin
Authors: Maher Louis J. , Miller Norton G. , Baker Richard G. , Curry B.Brandon , Mickelson David M.
Published: September 2002

Previously undescribed pollen, plant macrofossils, molluscs, and ostracodes were recovered from a 2.5-m-thick glaciolacustrine unit of silty sand and clay at Valders, Wisconsin. The interstadial sediment was deposited about 12,200 14C yr B.P. after retreat of the Green Bay lobe that deposited diamicton of the Horicon Formation, and before advance of the Lake Michigan lobe that deposited the red-brown diamicton of the Valders Member of the Kewaunee Formation. Fluctuations of abundance of Candona subtriangulata, Cytherissa lacustris, and three other species define four ostracode biozones in the lower 1.7 m, suggesting an open lake environment that oscillated in depth and proximity to glacial ice. Pollen is dominated by Picea and Artemisia, but the low percentages of many other types of long-distance origin suggest that the terrestrial vegetation was open and far from the forest border. The upper part of the sediment, a massive sand deposited in either a shallow pond or a sluggish stream, contains a local concentration of plant macrofossils. The interpretation of a cold open environment is supported by the plant macrofossils of more than 20 species, dominated by those of open mineral soils ( Arenaria rubella, Cerastium alpinum type, Silene acaulis, Sibbaldia procumbens, Dryas integrifolia, Vaccinium uliginosum var. alpinum, Armeria maritima, etc.) that in North America occur largely in the tundra and open tundra–forest ecotone of northern Canada. Ice-wedge casts occur in the sand.
Mammalian Faunas as Indicators of Environmental and Climatic Changes in Spain during the Pliocene–Quaternary Transition
Authors: Montuire Sophie
Published: September 2002

The study of mammal communities provides useful knowledge of paleoenvironments and paleoclimates during the Quaternary Period, and better documentation about the main fossil sites is making this task easier. Paleoecological reconstructions of this study are based on (i) rodent evolution and species richness, (ii) the cenogram method, and (iii) methods for quantifying climatic parameters. These analyses applied to a Pliocene–Quaternary faunal sequence of Spain indicate that a climatic change occurred at the end of the Pliocene when considerable cooling led to the onset of the glacial–interglacial cycles. Subsequently, during the Quaternary Period, alternating environmental patterns occurred, with a rather open and arid environment during the cold phases that contrasts with a somewhat more closed and comparatively wet environment during warmer phases. These observations are generalized from Spain to the remainder of the continent, noting that climatic conditions were less harsh and more arid in Spain than elsewhere in Europe.
High-Resolution Modeling of the Advance of the Younger Dryas Ice Sheet and Its Climate in Scotland
Authors: Hubbard Alun
Published: September 2002

Ice-sheet modeling tightly constrained by empirical studies provides an effective framework to reconstruct past climatic and environmental conditions. Scotland was severely affected by the abrupt climate change associated with the Younger Dryas Stade, during which an extensive ice sheet formed across the west highlands after a period of ice-free conditions. Here, a quasi-three-dimensional, time-dependent ice flow/mass-balance model is developed and applied to Scotland at 1 km resolution. The flow model is based on the driving stress approximation with an additional longitudinal correction term, essential at this scale of operation. Surface mass balance is driven by temperature and precipitation changes and further mass wastage is achieved through an empirically defined calving term. The ice dynamics and mass-balance components are coupled through the equation for mass continuity, which is integrated through time over a finite-difference grid which yields the geometric evolution of the ice sheet. Initial experiments reveal the model to be relatively insensitive to internal parameters but highly sensitive to mass balance. Furthermore, these experiments indicate that Scotland is readily susceptible to glaciation with large glaciers building up on the flanks of Ben Nevis after a temperature depression of 2.5°C, under present-day precipitation.

The Younger Dryas is modeled using a GRIP temperature series locally adjusted for amplitude and a systematic series of runs enables the isolation of the climate which best matches mapped ice limits. This “optimum-fit” configuration requires an annual temperature cooling of 8°C and the introduction of substantial west–east and south–north precipitation gradients of 40 and 50%, respectively, to the present-day regime. Under these conditions, a series of substantial independent regional ice centers develop in agreement with trimline studies and after 550 year the modeled ice sheet closely resembles the maximum limits as indicated by field mapping. However, modeled ice continues to expand beyond 550 yr, in conflict with the mapped ice limits which suggest a prolonged period of stability. This discrepancy may be explained by the onset of extreme aridity ca. 400 yr into the Stade associated with a southern migration of the Polar Front, leading to a reduction in atmospheric circulation which effectively starved the ice sheet of its moisture source, preventing further expansion. Introduction of an additional 20% reduction in precipitation to the “optimum-fit” regime after 350 yr brings the modeled ice sheet to equilibrium, substantiating this conclusion.
The Full-Glacial Environment of the Northern Seward Peninsula, Alaska, Reconstructed from the 21,500-Year-Old Kitluk Paleosol
Authors: Höfle Claudia , Edwards Mary E. , Hopkins David M. , Mann Daniel H. , Ping Chien-Lu
Published: September 2002

Paleoenvironmental conditions are reconstructed from soils buried under volcanic ash ca. 21,500 years ago on the Seward Peninsula. Soil development was minimal, reflecting the continuous regional deposition of loess, which originated from river floodplains and the exposed Chukchi shelf. Cryoturbated soil horizons, ice wedges, and ice-lens formation indicate a permafrost environment and mean annual temperatures below −6° to −8°C. Shallow active layers (average 45 cm), minimal evidence for chemical leaching of soils, and the presence of earthen hummocks indicate a cold and seasonally dry climate. Neither steppe nor polar desert soils are appropriate analogues for these zonal soils of loess-covered central Beringia. No exact analogues are known; however, soils underlying dry tundra near the arctic coast of northern Yakutia, Russia, and under moist, nonacidic tundra of the Alaskan North Slope have properties in common with the buried soils.
Geochemical Evidence for an Eolian Sand Dam across the North and South Platte Rivers in Nebraska
Authors: Muhs Daniel R. , Swinehart James B. , Loope David B. , Been Josh , Mahan Shannon A. , Bush Charles A.
Published: September 2002

Geochemical and geomorphic data from dune fields in southwestern Nebraska provide new evidence that the Nebraska Sand Hills once migrated across the North and South Platte rivers and dammed the largest tributary system to the Missouri River. The Lincoln County and Imperial dune fields, which lie downwind of the South Platte River, have compositions intermediate between the Nebraska Sand Hills (quartz-rich) and northeastern Colorado dunes (K-feldspar-rich). The most likely explanation for the intermediate composition is that the Lincoln County and Imperial dunes are derived in part from the Nebraska Sand Hills and in part from the South Platte River. The only mechanism by which the Nebraska Sand Hills could have migrated this far south is by complete infilling of what were probably perennially dry North Platte and South Platte river valleys. Such a series of events would have required an extended drought, both for activation of eolian sand and decreased discharges in the Platte River system. A nearby major tributary of the North Platte River is postulated to have been blocked by eolian sand about 12,00014C yr B.P. We propose that an eolian sand dam across the Plattes was constructed at about this same time.
Skeleton of Extinct North American Sea Mink (Mustela macrodon)
Authors: Mead Jim I. , Spiess Arthur E. , Sobolik Kristin D.
Published: September 2002

Mustela macrodon(extinct sea mink) is known only from prehistoric and historic Native American shell middens dating less than 5100 years old along coastal islands of the Gulf of Maine, northeastern North America. The species is distinct from all known extant subspecies ofM. vison(American mink) but still belongs to the North American subgenusVison.Metric comparisons betweenM. macrodonand five subspecies ofM. vison,using skull, mandible, humerus, radius, femur, and tibia skeletal elements, show thatM. macrodonis larger in overall size and robustness and is proportionately larger in the dental region. Many habitat-related parallels exist between coastal island mink of the Gulf of Maine and those of the Alexander Archipelago, southeastern Alaska, where the overall largest living subspecies of mink is found (M. v. nesolestes).
Late-Quaternary Recharge Determined from Chloride in Shallow Groundwater in the Central Great Plains
Authors: Macfarlane P. Allen , Clark Jordan F. , Davisson M. Lee , Hudson G. Bryant , Whittemore Donald O.
Published: September 2002

An extensive suite of isotopic and geochemical tracers in groundwater has been used to provide hydrologic assessments of the hierarchy of flow systems in aquifers underlying the central Great Plains (southeastern Colorado and western Kansas) of the United States and to determine the late Pleistocene and Holocene paleotemperature and paleorecharge record. Hydrogeologic and geochemical tracer data permit classification of the samples into late Holocene, late Pleistocene–early Holocene, and much older Pleistocene groups. Paleorecharge rates calculated from the Cl concentration in the samples show that recharge rates were at least twice the late Holocene rate during late Pleistocene–early Holocene time, which is consistent with their relative depletion in16O andD.Noble gas (Ne, Ar, Kr, Xe) temperature calculations confirm that these older samples represent a recharge environment approximately 5°C cooler than late Holocene values. These results are consistent with the global climate models that show a trend toward a warmer, more arid climate during the Holocene.
Hydrologic Variation in the Northern Great Plains During the Last Two Millennia
Authors: Fritz Sherilyn C. , Ito Emi , Yu Zicheng , Laird Kathleen R. , Engstrom Daniel R.
Published: September 2002

Reconstructions of lake-water salinity at decadal resolution for the last 2000 yr are compared among three lakes in North Dakota to infer regional patterns of drought. The intersite comparisons are used to distinguish local variation in climate or hydrology from regional patterns of change. At one lake, diatom-inferred salinity and lake-water Mg/Ca inferred from ostracode shell chemistry are coherent, both in terms of direction and magnitude of change, indicating that each is a robust technique for reconstructing lake-water chemistry. The data show that the last 2000 yr have been characterized by frequent shifts between high and low salinity, suggesting shifts between dry and moist periods. Long intervals of high salinity suggest periods of multiple decades when droughts were intense and frequent, thus indicating times when drought was more persistent than in the 20th century. Both the Medieval Period and Little Ice Age were hydrologically complex, and there is no clear evidence to suggest that either interval was coherent or unusual in effective moisture relative to long-term patterns. Differences among the three sites may be attributed to variation in local hydrology, and these differences emphasize the need for multiple sites in deriving regional climate interpretations from paleoecological data.
Vegetation, Climate, and Sea Level in the Past 55,000 Years, Hanjiang Delta, Southeastern China
Authors: Zheng Zhuo , Li Qianyu
Published: September 2002

Pollen in Quaternary deposits from the subtropical Hanjiang Delta records three major phases in the local vegetation and climate history during the last 55,000 yr: (1) a prevalent cool-to-temperate and humid climate at ca. 24,000 14C yr B.P. is indicated by abundant pollen of temperate trees including conifers; (2) between 20,000 and 15,000 14C yr B.P., a cold, dry environment was associated with low sea level during the last glaciation, leading to subaerial exposure, weathering, and interruption of sedimentation, as well as departure from the region of Dacrydium and Sonneratia; (3) a short-term expansion of grassland at ca. 10,300 14C yr B.P. reduced the predominant Lauraceae-Fagaceae evergreen forest, possibly corresponding to the Younger Dryas cooling. The combined data indicate a maximum sea-level rise in the mid-Holocene (7500–4000 14C yr B.P.) and a marine influence in the late Pleistocene at 45,000–20,000 14C yr B.P. The Holocene warming, however, did not bring back moisture-sensitive taxa, indicating high seasonal aridity probably caused by renewed monsoon conditions.