bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolutionary Trends in the Physciaceae
Authors: Scheidegger C. , Mayrhofer H. , Moberg R. , Tehler A.
Published: September 2002

The current delimitation of the family Physciaceae has been generally accepted since detailed descriptions of ascus characters allowed for a more natural circumscription of lichenized ascomycetes. The generic relations within the family are, however, still controversial and depend on the importance different authors attribute to specific morphological or chemical characteristics. The aim of this paper is to describe ascospore ontogeny and to test the present taxonomic structure of the family against a parsimony-based cladistic analysis, which includes three different scenarios of a priori character weighting. A study of ascospore ontogeny revealed two distinct developmental lines. One line revealed a delayed septum formation, which clearly showed transitions from spores with apical and median thickenings to spores without apical, but still well developed median thickenings, and to spores without any thickenings. In the second developmental line with an early septum formation again taxa with no thickenings, median thickenings, and both median and apical thickenings were found. Although these characters were constant at a species level, median wall thickenings especially varied among otherwise closely related taxa. In the cladistic analyses the current taxonomic structure of the Physciaceae was only obtained after the five character groups, namely morphology and anatomy of the vegetative thallus, conidiomata and conidia, morphology and anatomy of the apothecia, ontogeny of the ascospores, and secondary metabolites of the thallus, were given equal importance, and after a subjective a priori weighting further increased the weight of the three characters ‘conidial shape’, ‘presence of apical thickenings’, and ‘spore septation delayed’. This structure was not supported by a cladistic analysis with equally weighted characters but reflected the biased character weighting of the present day Physdaceae taxonomy. The taxonomic importance of conidial characters and of anatomical and ontogenetical spore characteristics need, therefore, a careful reconsideration in future.
Amphorothecium, a new pyrenocarpous lichen genus from New South Wales, Australia
Authors: McCarthy P. M. , Kantvilas G. , Elix J. A.
Published: September 2002

Amphorothecium occultum P. M. McCarthy, Kantvilas & Elix gen. et sp. nov. is described from deeply shaded, saxicolous bryophytes in south-eastern New South Wales, Australia. This genus is characterized by a trentepohlioid photobiont, distinctive thallus chemistry, pale, simple perithecia, largely unbranched paraphyses and periphyses, thin-walled, non-amyloid asci and very large, multiseptate ascospores. Its systematic position is uncertain.
The Trichotheliaceae of Christmas Island, Indian Ocean
Authors: McCarthy P. M.
Published: September 2002

Twenty-six taxa of Trichotheliaceae are reported from rock, bark and leaves on Christmas Island in the north-eastern Indian Ocean. Trichothelium oceanicum P. M. McCarthy sp. nov., a common foliicolous species, is described.
A new Erioderma taxon from the Azores
Authors: Jørgensen Per M. , James Peter W.
Published: September 2002

The Azorean lichen previously and erroneously referred in the literature to Erioderma wnghtii, belongs to the complex, widespread species E. leylandii, and is escribed as subsp. azoricum, possibly representing a relic, ancestral form with a composite chemistry. It is presently only known from Pico where it is under threat owing to the destruction of the forests.
Geoarchaeology and Geochronology of the Miami (Clovis) Site, Southern High Plains of Texas
Authors: Holliday Vance T. , Haynes C. Vance , Hofman Jack L. , Meltzer David J.
Published: September 2002

The Miami site, excavated in 1937, is in a small "playa" basin on the High Plains surface. The site is one of the earliest documented co-occurrences of Clovis points and mammoth. Reinvestigation of the site and related collections was undertaken to better understand the stratigraphy, geochronology, and archaeology. The basin, 23 m diameter × 1.6 m deep, filled with (1) dark gray silty clay, and (2) near the top of the section, a lens of well-sorted silt or loess. The basin started to fill ca. 13,700 yr B.P., the loess dates to ca. 11,400 yr B.P., and the bone bed probably dates to ca. 11,400-10,500 yr B.P. The loess may be the local manifestation of a "Clovis drought." The partial remains of five mammoths (three adults and two juveniles) were recovered in 1937; no other animal remains are known. The bone is heavily weathered and there are no clear indications of human modification. Artifacts found at the site include three Clovis points and a scraper found among the bones and two flakes and a scraper found on the surface near the playa. The origins of the bone and stone assemblage are uncertain but four scenarios are offered: a successful mammoth kill, an unsuccessful kill with wounded animals dying at the watering hole, opportunistic scavenging following natural deaths, or a palimpsest of multiple deaths following both natural and human causes.
Loess of the Upper Mississippi Valley Driftless Area
Authors: Leigh David S. , Knox James C.
Published: September 2002

Loess of the Driftless Area includes four distinct late Quaternary lithostratigraphic units: the Wyalusing (new), Loveland, Roxana, and Peoria formations. Erosion has removed parts or all of the pre-late Wisconsian loess at many sites. These formations consist largely of loess and retransported loess that typically occurs on uplands, terraces, and valley margins in the region. The oldest widespread formation (probably > 125,000 yr B.P.) is here formally named the Wyalusing Formation. The three younger formations correlate with the Loveland (probably > 125,000 yr B.P.), Roxana (55,000-25,000 yr B.P.), and Peoria (25,000-12,000 yr B.P.) loesses recognized elsewhere in the midcontinental United States. The soil/stratigraphic morphology of the Wyalusing-Loveland and Roxana-Peoria couplets appears to represent two distinct loess sedimentation sequences related to major expansion and contraction of the Laurentide Ice Sheet during oxygen isotope stages 6 and 3-2, respectively. The occurrence-frequency of loess units is inversely related to age, illustrating the erosional nature of the Driftless area landscape. The occurrence of four loess units at some sites in Driftless Area stratigraphic sections corroborates loess stratigraphy along the length of the Mississippi Valley, where typically not more than four or five loess units are found and they represent only the late and middle Pleistocene (<790,000 yr B.P.). Past climatic conditions, which favored erosion of loess, as well as a temporally erratic spatial extent of former continental ice sheets in North America, which provided the dust supply, probably account for the low number of loess units along the Mississippi Valley.
Tropical Climatic Variation on the Pacific Slopes of the Ecuadorian Andes Based on a 25,000-Year Pollen Record from Deep-Sea Sediment Core Tri 163-31B
Authors: Heusser Linda E. , Shackleton Nicholas J.
Published: September 2002

Marine sediments from 3°37′S, 83°58′W yield a well-dated pollen record of equatorial Andean vegetation. Moderate development of Podocarpus -high montane rainforest (∼34,000-28,000 yr B.P.) and increase of high Andean grassland pollen (∼28,000-16,000 yr B.P.) imply an extended dry, cool glacial period following a brief interstade. Rapid stepwise expansion in coastal and montane forest pollen characterizes the deglacial interval. The general correspondence between pollen and oxygen isotope variations in Tri 163-31B suggests that tropical climatic variations in the northern Andes were basically coherent with northern hemisphere glacier variations.
Determining Paleosol Topography Using Seismic Refraction
Authors: Rolph Tim C. , Shaw John , Derbyshire Edward , Zhisheng An
Published: September 2002

The seismic refraction reversed profiling technique has been used to investigate the topography of the last interglacial soil (paleosol S1) within the central Chinese Loess Plateau near Xifeng. The results suggest an essentially flat-lying soil at a depth which varies by only a few meters over an area of more than 10 km2. In addition, the results indicate a high-velocity layer at 50-60 m depth which is thought to coincide with a layer of carbonate concretions at the base of paleosol S5. The results agree well with the local loess-paleosol stratigraphy for this area and indicate that the seismic refraction method is a rapid technique for investigating paleotopography.
Holocene Sea-Level Rise Recorded by a Radiocarbon-Dated Mussel in a Submerged Speleothem beneath the Mediterranean Sea
Authors: Antonioli Fabrizio , Oliverio Marco
Published: September 2002

Fossil shells of the boring mussel Lithophaga lithophaga provide a means for dating changes in relative sea level. These bivalves, being among the first colonizers of bare calcareous substrates, can mark the earliest stages of marine submergence of caves. Here we report data concerning the deepest submerged speleothem presently sampled in a temperate area, at 48 m below present sea level off the west coast of Italy (Mediterranean Sea). A fossil mussel shell beneath encrusting layers from later marine colonists gave an AMS age of 9580 ± 35 14C yr B.P. (10,253 ± 72 cal yr B.P.).
Radiocarbon Dating of Soil Organic Matter
Authors: Wang Yang , Amundson Ronald , Trumbore Susan
Published: September 2002

Radiocarbon ages of soil organic matter are evaluated with a model which incorporates the dynamics of the 14C content of soil organic matter. Measured 14C ages of soil organic matter or its fractions are always younger than the true ages of soils due to continuous input of organic matter into soils. Differences in soil C dynamics due to climate or soil depth will result in significantly different 14C signatures of soil organic matter for soils of the same age. As a result, the deviation of the measured 14C age from the true age of soil formation could differ significantly among different soils or soil horizons. Our model calculations also suggest that 14C ages of soil organic matter will eventually reach a steady state provided that no climatic or ecological perturbations occur. Once a soil or a soil horizon has reached a steady state, 14C dating of soil organic matter will provide no useful information regarding the age of the soil. However, for soils in which steady state has not been reached, it is possible to estimate the age of soil formation by modeling the measured 14C contents of soil organic matter. Radiocarbon dating of buried soils could, in general, overestimate the true age of the burial by as much as the steady-state age of the soil or soil horizon.
Atmospheric Circulation and Variations in Scandinavian Glacier Mass Balance
Authors: Pohjola Veijo Allan , Rogers Jeffrey C.
Published: September 2002

Mountain glaciers in Scandinavia are currently advancing while most of the monitored mountain glaciers of the world are retreating. We examine atmospheric circulation variability and compare changes in air pressure indices to changes in the mass balance of glaciers in the northeastern part of the Atlantic Ocean. The glacier mass balance correlates well with the strength of maritime flow in both winter and summer, the presence of high pressure over the Barents Sea being a critical factor in summer. The advance of Scandinavian glaciers is due partly to persistently strong westerlies over the northeastern Atlantic during post-1980 winters and partly to cold summertime flow, which together have helped maintain positive glacier net balance by decreasing ablation since 1980.
Quaternary Stratigraphy and Trace-Element Indices of the Yangtze Delta, Eastern China, with Special Reference to Marine Transgressions
Authors: Chen Zhongyuan , Chen Zhenglou , Zhang Weigou
Published: September 2002

The Quaternary stratigraphy of the Yangtze delta has been revealed by a deep (344.64 m) continuous borehole, the sediments of which are divided into four sections, the Early (Q1), Middle (Q2), and Late Pleistocene (Q3), and the Holocene (Q4). Six lithofacies include lacustrine, fluvial, coastal, drowned river channel, deltaic, and shallow marine in these time periods. The fluvial and lacustrine lithofacies prevailed during Q1and Q2; coastal and drowned river channel lithofacies periodically appeared in Q1, Q2, and Q3; shallow marine lithofacies dominated Q3; and deltaic lithofacies occurred in Q4. Based on stratigraphy, four transgressive events are inferred. Trace-element (Sr, Ba, B, Ga, V) content and ratios of Sr/Ba and B/Ga are considered with regard to their distribution in the various lithofacies. Geochemical facies criteria are established based on combined diagnostic indices: Sr > 160 ppm, B > 90 ppm, Sr/Ba > 0.35, B/Ga > 4.0 for the shallow marine lithofacies; Sr < 90 ppm, B < 50 ppm, Sr/Ba < 0.2, B/Ga < 2.5 for the terrigenous lithofacies. These indices correspond well to paleosalinity data obtained using the sedimentary phosphate method (Ca/Ca + Fe). Transgressive events identified by the geochemical indices are mostly the same as reflected by marine fossils. Nevertheless, geochemical indices can indicate the occurrence of a weak transgression, where marine fossils are rare.
Continuous Lake-Sediment Records of Glaciation in the Sierra Nevada between 52,600 and 12,50014C yr B.P
Authors: Benson Larry V. , May Howard M. , Antweiler Ronald C. , Brinton Terry I. , Kashgarian Michaele , Smoot Joseph P. , Lund Steve P.
Published: September 2002

The chemistry of the carbonate-free clay-size fraction of Owens Lake sediments supports the use of total organic carbon and magnetic susceptibility as indicators of stadial–interstadial oscillations. Owens Lake records of total organic carbon, magnetic susceptibility, and chemical composition of the carbonate-free, clay-size fraction indicate that Tioga glaciation began ∼24,500 and ended by ∼13,60014C yr B.P. Many of the components of glacial rock flour (e.g., TiO2, MnO, BaO) found in Owens Lake sediments achieved maximum values during the Tioga glaciation when valley glaciers reached their greatest extent. Total organic carbon and SiO2(amorphous) concentrations reached minimum values during Tioga glaciation, resulting from decreases in productivity that accompanied the introduction of rock flour into the surface waters of Owens Lake. At least 20 stadial–interstadial oscillations occurred in the Sierra Nevada between 52,600 and 14,00014C yr B.P. Total organic carbon data from a Pyramid Lake sediment core also indicate oscillations in glacier activity between >39,500 and ∼13,60014C yr B.P. Alpine glacier oscillations occurred on a frequency of ≤1900 yr in both basins, suggesting that millennial-scale oscillations occurred in California and Nevada during most of the past 52,600 yr.
Quaternary Moraines vs Catastrophic Rock Avalanches in the Karakoram Himalaya, Northern Pakistan
Authors: Hewitt Kenneth
Published: September 2002

A history and conception of glacial events for the central Karakoram Himalaya, proposed some 80 years ago by Giotto Dainelli, are largely accepted today. However, certain deposits identified as terminal moraine complexes marking glacial episodes were actually emplaced by rock avalanches. In the Skardu and Shigar intermontane basins of Baltistan, at least 15 rock avalanche events were previously mapped as moraine or till. Criteria used for distinguishing these catastrophic landslide deposits emphasize homogeneous lithology of rubble and matrix, clast shape, facies characteristics, the large scale unity of emplacement, and morphological relations to valley topography. The deposits of three events, at Katzarah, Satpura, and the north end of Shigar Valley, have been reconstructed in detail. Thick supraglacial debris does not result in similar deposits. Extensive valley fills, river terraces, large sediment fans, and lacustrine sediments formerly attributed to late-glacial conditions are reinterpreted as postglacial events involving rock avalanches that interrupted fluvial development. Existing reconstructions of glaciations are left in doubt, especially late-glacial events in the central Karakoram, as are the roles assigned to Karakoram, main Indus Valley, and western Himalayan ice.
High-Resolution Paleoclimatic Information from Chinese Eolian Sediments Based on Grayscale Intensity Profiles
Authors: Porter Stephen C.
Published: September 2002

Grayscale intensity profiles from photographic images offer a rapid means of obtaining paleoclimate proxy records from Chinese loess, dune sand, and paleosols. Although the data can be obtained using conventional 35-mm film images, a digital camera and laptop computer will produce a high-resolution grayscale profile at a field site within minutes. Comparison of grayscale profiles with profiles of magnetic susceptibility measured down loess and dune-sand sections at sites on the Loess Plateau and Tibetan Plateau in a range of altitudes and climatic regimes shows that the two parameters are highly correlated. Therefore, grayscale intensity is a convenient alternative to magnetic susceptibility for generating paleoclimatic data in the loess and desert-margin regions of China. The resolution of both grayscale and susceptibility profiles ultimately is limited by bioturbation, which is most pronounced in paleosols.
Interglacial Growth of Tufa in Croatia
Authors: Horvatinčić Nada , Čalić Romana , Geyh Mebus A.
Published: September 2002

Tufa samples from the Krka River area in Croatia were dated by 14C and 230Th/234U methods. The study area is situated in the karst region of the southern Dinarides. 14C ages of 40 tufa samples collected at the waterfalls coincide with the early Holocene interglaciation, up to 6000 14C yr B.P. Comparison of conventional 14C dates of Holocene tufa and those of speleothems in the Dinaric Karst shows that speleothem formation started several thousand years earlier than tufa growth. Samples of old tufa deposits from the Krka River (17) and Plitvice Lakes (12) area and speleothem samples from caves in Dinaric Karst (5) yield 34 230Th/234U dates, most of which cluster around interglacial marine δ18O stage 5 (21). Eight of 13 older dates belong to interglacial stages 7 and 9; only 5 dates fall within stage 6 and 8 glaciations. 230Th/234U dates of speleothems and tufa samples from central Europe have indicated that these were formed preferentially during warm and humid interglacial and interstadial periods, and it appears that this is true of southern Croatia as well. Stable isotope (δ13C, δ18O) analyses of 40 tufa samples from the Krka River area were compared with stable isotope analyses of tufa from the Plitvice Lakes area. The δ13C values for both locations are similar and range from −10 to −6‰, indicating similar conditions of tufa formation. A systematic difference between the δ18O values of tufa in these two areas reflects the regional distribution of the oxygen composition of precipitation.
Modeling a 200-Yr Interruption of the Holocene Sapropel S1
Authors: Myers Paul G. , Rohling Eelco J.
Published: September 2002

An oceanic general circulation model, previously used to simulate the conditions associated with the Holocene Sapropel S1, is used to simulate the effects of a climate deterioration (represented as a cooling event) on the sapropelic circulation mode. The enhanced cooling (2°–3°C) induces deep convection in the Adriatic and the Gulf of Lions and intermediate water formation in the Aegean, where in all cases there had previously been only stagnant unventilated waters. The depths of ventilation (to ∼1250 m) are in agreement with core data from this period. The short decadal timescales involved in modifying the sapropelic circulation suggest that such a climatic deterioration may be associated with the interruption of S1 between 7100 and 6900 14C yr B.P., which divided the sapropel into two subunits.
Late-Glacial Environmental Changes South of the Wisconsinan Terminal Moraine in the Eastern United States
Authors: Russell Emily W.B. , Stanford Scott D.
Published: September 2002

Palynological analyses of two sediment cores, one 2.4 m long from northern Delaware, dated about 16,300 to 14,70014C yr B.P., and one 1.8 m long from New Jersey just south of the Wisconsinan terminal moraine and dated about 13,600 to 12,50014C yr B.P., give the first detailed evidence of vegetation in this area during these periods. The overall assemblages are similar to each other, withPiceaandPinusdominating the arboreal pollen and Poaceae and Cyperaceae the herbaceous flora. Nonarboreal pollen contributes about 30–50% of the total, indicating a very open vegetation or a mix of forest patches and open areas. Especially in Delaware, there is a diversity of other herbaceous pollen, including members of the Asteraceae, Fabaceae, and Ranunculaceae. The assemblages do not resemble current North American tundra or boreal forest assemblages; rather, they resemble assemblages characteristic of tundra on recently exposed land surfaces north of the Wisconsinan terminal moraine. The persistence of the assemblages for 1500–2000 years in late-glacial time suggests stable and cold climate during this time of glacier retreat.
Ancient Meteorite Finds and the Earth's Surface Environment
Authors: Bland Philip A. , Bevan Alex W. R. , Jull A. J. Tim
Published: September 2002

The flux of meteorites to the Earth over the last 50,000 yr has remained approximately constant. Most meteorites that fall in temperate or tropical areas are destroyed on a time scale which is short compared to the rate of infall; however, in arid regions (both “hot” deserts and the “cold” desert of Antarctica) weathering is slower and accumulations of meteorites may occur. The initial composition for many meteorite groups is well known from modern falls, and terrestrial ages may be established from analyses of the abundance of cosmogenic radionuclides, providing an absolute chronology for recording terrestrial processes. As samples are falling constantly, and are distributed approximately evenly over the Earth, meteorites may thus be thought of as an appropriate “standard sample” for studying aspects of the terrestrial surface environment. Studies involving 14C and 36Cl terrestrial ages of meteorites, 57Fe Mössbauer spectroscopy (to quantify the degree of oxidation in samples), stable isotopes, and determination of halogen abundances are yielding information on the terrestrial history of meteorites: (i) terrestrial age and oxidation-frequency distributions for populations of samples allow the ages of surfaces to be estimated; (ii) differences in the weathering rate of samples between sites allows constraints to be imposed on the effect of climate on rock weathering rates; (iii) carbon isotopic compositions of generations of carbonate growth within meteorites allows, in some cases, temperatures of formation of carbonates to be estimated; (iv) structure in the oxidation–terrestrial age distribution for meteorites from some arid accumulation sites (specifically, the Nullarbor of Australia) appears to be linked to previous humid/arid cycles; (v) meteorite accumulations in Antarctica have been used to constrain aspects of the Quaternary evolution of the ice sheet, and terrestrial age and oxidation data have been used to constrain ice flow.
Precise Temporal Correlation of Holocene Mollusk Shells Using Sclerochronology
Authors: Marchitto Thomas M. , Jones Glenn A. , Goodfriend Glenn A. , Weidman Christopher R.
Published: September 2002

Annual growth bands of mollusk shells record several types of paleoenvironmental information, including geochemical proxies for water properties and morphological characteristics of growth and mortality. Sclerochronology, the marine counterpart of dendrochronology, offers a way to link individual shells together to form long continuous records of such parameters. It also allows for precise dating of recent shells and identification of contemporaneous fossil individuals. The longevity of the ocean quahogArctica islandica(commonly >100 yr) makes this species well suited for sclerochronology. Band width records of contemporaneousA. islandicaspecimens from the same region exhibit high correlations (ρ = 0.60–0.80 for spans of ≥30 bands), indicating some common environmental influences on shell growth. By adopting several strict criteria, fossil (dead-collected) shells can be linked into composite sclerochronologies. A seven-shell 154-yr chronology was constructed for Georges Bank using three live-collected and four dead-collected shells. Band width matching indicates that the dead-collected individuals died in A.D. 1950, 1971, 1978, and 1989. Sclerochronological age assignments were verified using aspartic acid racemization dating. Construction of a 1000-yr sclerochronology is judged to be feasible using the described methods.
Paleobiogeographic Changes at the Pleistocene–Holocene Boundary near Pintwater Cave, Southern Nevada
Authors: Hockett Bryan Scott
Published: September 2002

In 1996, approximately 70,000 mammal and lizard bones were recovered from Pintwater Cave in the northern Mojave Desert of southern Nevada. These bones date between 32,000 and 735014C yr B.P. Between 32,000 and 10,10014C yr B.P. the local fauna consisted of a mix of xeric- and cool/mesic-adapted species.Ochotona princepsandThomomys talpoidesthen occupied the region, although these animals were extirpated by the onset of the middle Holocene.Sauromalus obesusandDipodomys desertiprobably migrated to the region during the latest Pleistocene.Dipsosaurus dorsalisentered the Pintwater Cave record after 800014C yr B.P. Consistent with climatic interpretations for the northern Great Basin, these data suggest a cool and moist latest Pleistocene climate for the northern Mojave Desert. In contrast to the northern Great Basin, however, this region experienced predictable summer precipitation coupled with increasingly warmer winters by 10,10014C yr B.P. In both regions, the warm middle Holocene began ca. 830014C yr B.P. However, whereas the northern Great Basin probably experienced warm and dry conditions at that time, the northern Mojave Desert remained warm with relatively predictable summer precipitation. The modern northern Mojave Desert biota probably was not established until after 830014C yr B.P.
Comparison of Conventional K–Ar and 40Ar/39Ar Dating of Young Mafic Volcanic Rocks
Authors: Lanphere Marvin A.
Published: September 2002

K–Ar and 40Ar/39Ar ages have been measured on nine mafic volcanic rocks younger than 1 myr from the Snake River Plain (Idaho), Mount Adams (Washington), and Crater Lake (Oregon). The K–Ar ages were calculated from Ar measurements made by isotope dilution and K2O measurements by flame photometry. The 40Ar/39Ar ages are incremental-heating experiments using a low-blank resistance-heated furnace. The results indicate that high-quality ages can be measured on young, mafic volcanic rocks using either the K–Ar or the 40Ar/39Ar technique. The precision of an 40Ar/39Ar plateau age generally is better than the precision of a K–Ar age because the plateau age is calculated by pooling the ages of several gas increments. The precision of a plateau age generally is better than the precision of an isotope correlation (isochron) age for the same sample. For one sample the intercept of the isochron yielded an 40Ar/36Ar value significantly different from the atmospheric value of 295.5. Recalculation of increment ages using the isochron intercept for the composition of nonradiogenic Ar in the sample resulted in much better agreement of ages for this sample. The results of this study also indicate that, given suitable material and modern equipment, precise K–Ar and 40Ar/39Ar ages can be measured on volcanic rocks as young as the latest Pleistocene, and perhaps even the Holocene.
Glacio-isostasy and Glacial Ice Load at Law Dome, Wilkes Land, East Antarctica
Authors: Goodwin Ian D. , Zweck Christopher
Published: September 2002

The Holocene sea-level high stand or “marine limit” in Wilkes Land, East Antarctica, reached ∼30 m above present sea level at a few dispersed sites. The most detailed marine limit data have been recorded for the Windmill Islands and Budd Coast at the margin of the Law Dome ice cap, a dome of the East Antarctic Ice Sheet (EAIS). Relative sea-level lowering of 30 m and the associated emergence of the Windmill Islands have occurred since 6900 14C (corr.) yr B.P. Numerical modeling of the Earth's rheology is used to determine the glacio-isostatic component of the observed relative sea-level lowering. Glaciological evidence suggests that most of EAIS thickening occurred around its margin, with expansion onto the continental shelf. Consequently, a regional ice history for the last glacial maximum (LGM) was applied in the glacio-isostatic modeling to test whether the observed relative sea-level lowering was primarily produced by regional ice-sheet changes. The results of the modeling indicate that the postglacial (13,000 to 8000 14C yr B.P) removal of an ice load of between 770 and 1000 m from around the margin of the Law Dome and adjacent EAIS have produced the observed relative sea-level lowering. Such an additional ice load would have been associated with a 40- to 65-km expansion of the Law Dome to near the continental shelf break, together with a few hundred meters of ice thickening on the adjoining coastal slope of the EAIS up to 2000 m elevation. Whereas the observed changes in relative sea level are shown to be strongly influenced by regional ice sheet changes, the glacio-isostatic response at the Windmill Islands results from a combination of regional and to a lesser extent, Antarctic-wide effects. The correspondence between the Holocene relative sea-level lowering interpreted at the margin of the Law Dome and the lowering interpreted along the remainder of the Wilkes Land and Oates Land coasts (105°–160° E) suggests that a similar ice load of up to 1000 m existed along the EAIS margin between Wilkes Land and Oates Land.
Probability That a Fossil Absent from a Sample Is Also Absent from the Paleolandscape
Authors: Nowak Robert S. , Nowak Cheryl L. , Tausch Robin J.
Published: September 2002

A procedure to calculate probability limits for the inference that the absence of a taxon from a woodrat (Neotoma) midden implies absence from the paleolandscape uses paired samples of modern vegetation communities and paired samples of paleocommunities. Assumptions are: (1) each member of a sample pair is an independent measure of the same vegetation assemblage; (2) behavioral patterns of woodrats are the same as each midden in a paired sample is constructed; and (3) the probability of fossilization is zero when a taxon is absent from the vegetation. The procedure provides a logical test of data consistency: the upper probability limit of making a false inference should be greater than the lower limit. Averaged over 140 plant taxa, the upper and lower probability limits for a false inference were 11 and 7%, respectively. More than 70% of taxa passed the logical test, indicating a reliable procedure. For many taxa that failed the logical test, four potential explanations account for this failure, two of which can be solved by simply increasing sample sizes. Using analogous assumptions, the procedures are applicable to other types of stratigraphic sampling such as macrofossils from sediment cores or fossils from biostratigraphic units.
Whole-Rock Aminostratigraphy and Quaternary Sea-Level History of the Bahamas
Authors: Hearty Paul J. , Kaufman Darrell S.
Published: September 2002

The surficial geology of the tectonically stable Bahamian archipelago preserves one of the most complete records of middle to late Quaternary sea-level-highstand cycles in the world. However, with the exception of deposits from marine isotope substage (MIS) 5e, fossil corals for radiometric dating of this rich stratigraphic sequence are rare. This study utilizes the previously published, independent lithostratigraphic framework as a testing ground for amino acid racemization in whole-rock limestone samples. At least six limestone–soil couplets provide a relative age sequence of events that encompass as many interglacial–glacial cycles. D-Alloisoleucine/L-isoleucine data fall into six clusters, or “aminozones.” On the basis of independent dating and the inferred correlation with global MIS, the ages of several aminozones are known, while the ages of others are calculated from calibrated amino acid geochronology. This study demonstrates the utility of the whole-rock aminostratigraphy method for dating and correlating widespread emergent marine deposits, constitutes the first regional geochronological framework for the Bahamas, and highlights major sea-level events over the past half million years.
Wisconsin Glaciation of the Sierra Nevada (79,000–15,000 yr B.P.) as Recorded by Rock Flour in Sediments of Owens Lake, California
Authors: Bischoff James L. , Cummins Kathleen
Published: September 2002

Chemical analyses of the clay-sized fractions of 564 continuous sediment samples (200-yr resolution) from composite core OL90/92 allow quantification of an abundance of glacial rock flour. Rock flour produced during glacier advances is represented by clay-sized plagioclase, K-feldspar, and biotite in homogeneous internal composition. The abundance of rock flour is deemed proportional to the intensity of glacies advances. Age control for the composite section is provided by combining previously published radiocarbon dates on organics, U/Th dates on ostracode shells, and U/Th dates on saline minerals from nearby Searles Lake correlated to OL92 by pollen. The rock flour record displays three levels of variability: (1) a dominant one of about 20,000 yr related to summer insolation and precipitation; (2) an intermediate one of 3000–5000 yr, perhaps related to North Atlantic Heinrich events; and (3) a minor one of 1000–2000 yr, perhaps related to North Atlantic thermohaline-driven air-temperature variation.
Late Quaternary Upwelling Intensity and East Asian Monsoon Forcing in the South China Sea
Authors: Jian Zhimin , Huang Baoqi , Kuhnt Wolfgang , Lin Hui-Ling
Published: September 2002

Foraminifera from two cores off eastern Vietnam and the northwestern Philippines, where modern summer and winter monsoon-driven upwelling occurs in the South China Sea, respectively, were analyzed to evaluate the changes in paleoproductivity and upper water structure over the last 220,000 yr. We observed enhanced organic carbon flux and a shoaled thermocline when upwelling intensified off eastern Vietnam during interglacial ages and off the northwestern Philippines during glacial ages. This indicates that the East Asian summer monsoon increased while the winter monsoon decreased during interglacial ages. Particularly, the upwelling reached a maximum off eastern Vietnam during late marine isotopic stage (MIS) 5 and off the northwestern Philippines during MIS 2, implying that the summer monsoon decreased gradually since MIS 5 while the winter monsoon displayed an opposite trend. The variations in upwelling proxies exhibit a distinct cyclicity with frequencies near 41,000 yr and 23,000 yr off eastern Vietnam, in contrast to a strong frequency peak near 100,000 yr off the northwestern Philippines. We suggest that the East Asian summer monsoon has been forced by changes in solar insolation associated with precession and obliquity, while ice-volume forcing is probably a primary factor in determining the strength and timing of the East Asian winter monsoon but with less important insolation forcing.
Implications of a 24,000-Yr Palynological Record for a Younger Dryas Cooling and for Boreal Forest Development in Northeastern Siberia
Authors: Anderson Patricia M. , Lozhkin Anatoly V. , Brubaker Linda B.
Published: September 2002

A sediment core from Smorodinovoye Lake (SML), northeastern Siberia (area to the east of the Verkhoyansk Range) spanning the last 24,000 14C yr indicates that vegetational and climatic changes in the upper Indigirka basin resemble those in eastern Siberia (Lena basin and westward). For example, maximum postglacial summer temperatures at SML probably occurred 6000–4000 14C yr B.P., an age more in accordance with eastern than northeastern records. Larix arrived near the lake by 9600 14C yr B.P., approximately when forests expanded in the east but ca. 1500 14C yr later than forests were established in the neighboring upper Kolyma basin. Paleobotanical data further suggest that Larix possibly migrated southward from populations in the arctic lowlands of eastern Siberia and did not originate from interior refugia of the upper Kolyma basin. Although a Younger Dryas cooling has been noted in eastern Siberia, SML provides the first evidence from the northeast for a similar climatic reversal. Climatic variations seemingly have persisted between the Indigirka and Kolyma basins over at least the last 11,000 14C yr, despite the proximity of the two drainages and the occurrence of major changes in boundary conditions (e.g., seasonal insolation, sea levels) that have influenced other regional climatic patterns.
Environments of the Russian Plain during the Middle Valdai Briansk Interstade (33,000–24,000 yr B.P.) Indicated by Fossil Mammals and Plants
Authors: Markova Anastasia K. , Simakova Alexandra N. , Puzachenko Andrei Yu , Kitaev Lev M.
Published: September 2002

Abundant mammal (45 localities) and plant (52 sections) fossil data collected from the Russian Plain deposits of the Middle Valdai Briansk Interstade indicate a period of noticeable warming. These materials were jointly analyzed. The data were organized in the database software PARADOX and then moved to the GIS program ARC/INFO. Mathematical methods as well as traditional research methods were used for the analysis. The reconstructed biogeographical provinces illustrate the specific environmental and climatic conditions of the Briansk Interstade. Analogues of modern natural zones did not exist at this time on the Russian Plain. The Briansk landscapes reflect the moderate-cool climate of this period, when the majority of northern subarctic plant and mammal species extended their ranges considerably to the south to the Central Russian Plain. At the same time, steppe species penetrated farther north and west. This combination shows that the continuous forest zone was destroyed during the Briansk Inter-stade. Five biogeographical provinces have been reconstructed from the north to the south for the Russian Plain during the Briansk warming on the basis of joint analysis of mammalian and botanical data.
Charybdotoxin‐sensitive small conductance KCa channel activated by bradykinin and substance P in endothelial cells
Authors: Sollini M , Frieden M , Bény J‐L
Published: September 2002

In cultured porcine coronary artery endothelial cells, we have recently shown that substance P and bradykinin stimulated different types of Ca2+‐dependent K+ (KCa) current. A large part of this current was insensitive to iberiotoxin and apamin. The aim of the present study was to characterize the KCa channel responsible for this current.

In cell‐attached configuration and asymmetrical K+ concentration, 100 nM bradykinin or substance P activated a 10 pS K+ channel. In inside‐out configuration, the channel was half‐maximally activated by 795 nM free Ca2+.

Apamin (1 μM) added to the pipette solution failed to inhibit the channel activity while charybdotoxin (50 nM), completely blocked it. Perfusion at the intracellular face of the cell, of an opener of intermediate conductance KCa channel, 500 μM 1‐ethyl‐benzimidazolinone (1‐EBIO) increased the channel activity by about 4.5 fold.

In whole‐cell mode, bradykinin and substance P stimulated an outward K+ current of similar amplitude. Charybdotoxin inhibited by 75% the bradykinin‐induced current and by 80% the substance P‐induced current. Charybdotoxin plus iberiotoxin (50 nM each) inhibited by 97% the bradykinin‐response. Charybdotoxin plus apamin did not increase the inhibition of the substance P‐response obtained in the presence of charybdotoxin alone.

1‐EBIO activated a transient outward K+ current and hyperpolarized the membrane potential by about 13 mV. Charybdotoxin reduced the hyperpolarization to about 3 mV.

Taken together these results show that bradykinin and substance P activate a 10 pS KCa channel, which largely contributes to the total K+ current activated by these agonists. Despite its small conductance, this channel shares pharmacological characteristics with intermediate conductance KCa channels.

British Journal of Pharmacology (2002) 136, 1201–1209. doi:10.1038/sj.bjp.0704819
Pharmacology and thermosensitivity of the dartos muscle isolated from rat scrotum
Authors: Gibson Alan , Akinrinsola Adetokunbo , Patel Tejesh , Ray Arijit , Tucker John , McFadzean Ian
Published: September 2002

The dartos is a thin sheet of smooth muscle closely associated with the skin of the scrotum. Although known to play an important role in scrotal thermoregulation, there has been no detailed study into the pharmacology, or thermosensitivity, of the dartos from any species. Here, we investigate these two parameters in the isolated dartos muscle from rat.

Field stimulation of the rat dartos caused contractions that were abolished by tetrodotoxin, phentolamine and guanethidine, but unaffected by atropine or L‐NG‐nitroarginine. Exogenous noradrenaline also produced contractions blocked by both phentolamine and prazosin. In muscles with raised tone and negated sympathetic function, field stimulation failed to elicit relaxation. The dartos muscle did not contract in response to carbachol, nicotine, histamine, 5‐hydroxytryptamine (all up to 100 μM) or substance P (up to 1 μM).

Contractile responses to field stimulation and noradrenaline were much greater at 30°C compared with 40°C; indeed, contractions to 1 μM noradrenaline at 30°C were relaxed by around 80% on heating to 40°C. Similar heat‐induced relaxations were observed during contractions to both U46619 (100 nM) and high K (70 mM).

In contrast, contractile responses to the myosin phosphatase inhibitor calyculin‐A (1 μM), either in the presence or absence of external calcium, were resistant to relaxation by heating. In calcium‐free medium at 30°C, U46619 continued to produce contractions that were again relaxed by 80% on heating to 40°C. However, in the presence of calyculin‐A, this heat‐induced relaxation was greatly reduced.

Thus, the rat dartos muscle receives a functional sympathetic innervation and contracts to noradrenaline via α‐adrenoceptors. There is no functional inhibitory innervation. Experiments with calyculin‐A suggest that myosin phosphatase is a major contributor to the marked thermosensitivity of the dartos muscle.

British Journal of Pharmacology (2002) 136, 1194–1200. doi:10.1038/sj.bjp.0704830
Sphingosine 1‐phosphate enhances spontaneous transmitter release at the frog neuromuscular junction
Authors: Brailoiu Eugen , Cooper Robin L , Dun Nae J
Published: September 2002

Intracellular recordings were made from isolated frog sciatic‐sartorius nerve‐muscle preparations, and the effects of sphingosine 1‐phosphate (S1‐P) on miniature endplate potentials (MEPPs) were studied. Extracellular application of S1‐P (1 and 30 μM) had no significant effects on the frequency and amplitude of MEPPs. Delivery into nerve terminals by liposomes containing 10−5, 10−4 or 10−3 M S1‐P was associated with a concentration‐dependent increase in MEPP frequency of 37, 63 and 86%. The per cent of median MEPP amplitude was not significantly changed, but there was an increase in the number of ‘giant’ MEPPs. Pre‐exposure of the preparations to S1‐P 10−5 but not 10−8 M entrapped in liposomes for 15 min blocked the effects of subsequent superfusion of S1‐P (10−4 M)‐filled liposomes on MEPP frequency. Thus, intracellular S1‐P receptors seem to undergo ‘desensitization’ to higher concentrations of S1‐P. The result provides the first evidence that S1‐P acting intracellularly but not extracellularly enhances spontaneous transmitter release at the frog neuromuscular junction.

British Journal of Pharmacology (2002) 136, 1093–1097. doi:10.1038/sj.bjp.0704839
Stem cell transplantation for paroxysmal nocturnal haemoglobinuria in childhood
Authors: Flotho Christian , Strahm Brigitte , Kontny Udo , Duffner Ulrich , Peters Anke M. J. , Dupuis Wolfgang , Niemeyer Charlotte M.
Published: September 2002

Summary.  Paroxysmal nocturnal haemoglobinuria (PNH) is a clonal haematopoietic disorder characterized by chronic or intermittent intravascular haemolysis, variable cytopenia and an increased risk of thrombosis. Stem cell transplantation (SCT) is a curative therapeutic option, but its risks must be carefully weighed against the natural course of PNH. World‐wide experience with SCT for PNH in the paediatric age group is scarce. We report on two adolescents suffering from PNH with life‐threatening complications who were successfully transplanted from unrelated donors. Indications and techniques of SCT in childhood PNH are discussed and an overview of the literature is given.
Blast crisis of Philadelphia chromosome‐positive chronic myeloid leukaemia carrying micro‐bcr breakpoint (e19a2 and e191a)
Authors: Ohsaka Akimichi , Hoshino Shigeru , Kobayashi Masaru , Kudo Hideyuki , Kawaguchi Ryuji
Published: September 2002

Summary.  We describe two Philadelphia chromosome‐positive chronic myeloid leukaemia (Ph‐positive CML) patients carrying micro‐bcr (µ‐bcr) breakpoint, who developed blast crisis within 5 years of diagnosis. Reverse transcription polymerase chain reaction analysis of bone marrow cells using primers specific for the p210BCR–ABL fusion transcript showed aberrant large‐sized bands in both cases (986 bp in patient 1 and 1031 bp in patient 2). Sequencing analysis of these products revealed BCR–ABL fusion transcripts with e19a2 in patient 1 and e191a in patient 2. These findings suggest that CML carrying µ‐bcr breakpoint may exhibit a similar clinical course to classical CML, and that it may not be a mild form of the disease.
Treatment responses of childhood aplastic anaemia with chromosomal aberrations at diagnosis
Authors: Ohga Shouichi , Ohara Akira , Hibi Shigeyoshi , Kojima Seiji , Bessho Fumio , Tsuchiya Shigeru , Ohshima Yukio , Yoshida Nobuyuki , Kashii Yoshifumi , Nishimura Shinichiro , Kawakami Kiyoshi , Nishikawa Kenichi , Tsukimoto for the Aplastic Anaemia Committee of the Japanese Ichiro
Published: September 2002

Summary.  The clinical outcome of childhood aplastic anaemia (AA) with aberrant cytogenetic clones at diagnosis was surveyed. Among 198 children with newly diagnosed AA registered with the AA Committee of the Japanese Society of Paediatric Hematology between 1994 and 1998, cytogenetic studies of bone marrow (BM) cells were completed in 159 patients. Apart from one Robertsonian translocation, seven patients (4·4%) showed clonal chromosomal abnormalities in hypoplastic BM without myelodysplastic features. The patients included six girls and one boy with a median age of 11 years (range 5–14 years). Sixpatients had del(6), del(5), del(13), del(20), or −7, and one showed add(9). Four patients responded to the first immunosuppressive therapy (IST: cyclosporin A plus anti‐thymocyte globulin) and one obtained a spontaneous remission. Cytogenetic abnormalities remained in two patients with an IST response. On the other hand, two patients showed no IST response. One did not respond to repeat IST and died of acute graft‐versus‐host disease after an unrelated‐BM transplant. Another obtained a complete response after a successful BM transplant. No haematological findings at diagnosis predicted the treatment response. No significant morphological changes developed during the course of the illness. A literature review revealed that half of 24 AA patients with chromosomal abnormalities responded to the first IST, and that +6 was the sole predictable marker for IST unresponsiveness. These results suggest that IST can be applied as the initial therapy for AA with cytogenetic abnormalities in the absence of completely matched donors.