bluuebunny/crossref_metadata_2025_split huggingface dataset:
Late Holocene Paleoclimatic Changes in Western Central Africa Inferred from Mineral Abundance in Dated Sediments from Lake Ossa (Southwest Cameroon)
Authors: Wirrmann Denis , Bertaux Jacques , Kossoni Alice 
Published: April 2003

AbstractMinerals derived from catchment soils were determined using FTIR spectroscopy in the well-dated core OW4 from Lake Ossa, a lowland rainforest area in Cameroon. This quantification provides a hydrologic record indicating that the magnitude of runoff events, and by inference, rainfall pattern, has varied during the Late Holocene. The comparison between minerogenic inputs and vegetation changes improves the understanding of the inferred climate dynamics. Since at least 5400 cal yr B.P., the paleomonsoon rainfall intensity decreased, as shown by a general decrease in mineral fluxes. This observation is consistent with a gradual weakening of the boreal summer insolation in tropical latitudes. However, the major vegetational change lags behind the onset of the decrease in mineral fluxes. From 2800 to ca 1000 cal yr B.P., the forest receded: the amount of rainforest taxa decreased and is replaced by pioneer trees and Poaceae, when the mineral fluxes attained their lowest values. This episode of maximum dryness is attributed to an abrupt climatic event of global significance which is superimposed onto the paleomonsoon variability. It is related to a cold event, which in turn produced a change in the lower atmospheric circulation that was characterized by a strengthening of northern trade winds, probably correlated with sea-surface temperature variations in the eastern tropical Atlantic area.
Holocene Vegetation History from Fossil Rodent Middens near Arequipa, Peru
Authors: Holmgren Camille A. , Betancourt Julio L. , Rylander Kate Aasen , Roque Jose , Tovar Oscar , Zeballos Horacio , Linares Eliana , Quade Jay 
Published: April 2003

AbstractRodent (Abrocoma, Lagidium, Phyllotis) middens collected from 2350 to 2750 m elevation near Arequipa, Peru (16°S), provide an ∼9600-yr vegetation history of the northern Atacama Desert, based on identification of >50 species of plant macrofossils. These midden floras show considerable stability throughout the Holocene, with slightly more mesophytic plant assemblages in the middle Holocene. Unlike the southwestern United States, rodent middens of mid-Holocene age are common. In the Arequipa area, the midden record does not reflect any effects of a mid-Holocene mega drought proposed from the extreme lowstand (100 m below modern levels, >6000 to 3500 yr B.P.) of Lake Titicaca, only 200 km east of Arequipa. This is perhaps not surprising, given other evidence for wetter summers on the Pacific slope of the Andes during the middle Holocene as well as the poor correlation of summer rainfall among modern weather stations in the central Andes-Atacama Desert. The apparent difference in paleoclimatic reconstructions suggests that it is premature to relate changes observed during the Holocene to changes in El Niño Southern Oscillation modes.
Long Plio-Pleistocene Terrestrial Record of Climate Change and Mammal Turnover in Southern Spain
Authors: Agustı́ Jordi , Oms Oriol , Remacha Eduard 
Published: April 2003

AbstractCyclostratigraphic analysis of the Pliocene Zújar section (Guadix-Baza Basin, southeastern Spain) has enabled the recognition of a number of climatically forced cycles reflecting alternating dry and wet periods. Peaks of aridity are recorded at ca. 3.95, 3.55, 3.2, 2.8, and 1.8 myr B.P. The first dry period at about 4.0 myr B.P. corresponds to the early Ruscinian Mammal age, while the second arid interval at about 3.6 myr B.P. corresponds to the establishment of the Mediterranean double seasonality. The significant mammal turnover between the late Ruscinian and early Villanyian stages is placed between chron 2An.2n and the very base of chron 2An.1n, coincident with the dry phase recognized at about 3.2 myr B.P. The fourth aridity maximum at 2.8 myr B.P. roughly coincides with the Equus event in western Europe and is probably related to the beginning of the glacial–interglacial dynamics in the Northern Hemisphere. Finally, the last dry peak at about 1.8 myr B.P. is probably related to the set of mammalian events characterizing the transition from the late Pliocene faunas to those of the early Pleistocene.
Late Quaternary Water-Level Variations and Vegetation History at Crooked Pond, Southeastern Massachusetts
Authors: Shuman Bryan , Bravo Jennifer , Kaye Jonathan , Lynch Jason A. , Newby Paige , Webb Thompson 
Published: April 2003

AbstractSediment cores collected along a transect in Crooked Pond, southeastern Massachusetts, provide evidence of water-level changes between 15,000 cal yr B.P. and present. The extent of fine-grained, detrital, organic accumulation in the basin, inferred from sediment and pollen stratigraphies, varied over time and indicates low water levels between 11,200 and 8000 cal yr B.P. and from ca. 5300 to 3200 cal yr B.P. This history is consistent with the paleohydrology records from nearby Makepeace Cedar Swamp and other sites from New England and eastern Canada and with temporal patterns of regional changes in effective soil moisture inferred from pollen data. The similarities among these records indicate that (1) regional conditions were drier than today when white pine (Pinus strobus) grew abundantly in southern New England (11,200 to 9500 cal yr B.P.); (2) higher moisture levels existed between 8000 and 5500 cal yr B.P., possibly caused by increased meridonal circulation as the influence of the Laurentide ice sheet waned; and (3) drier conditions possibly contributed to the regional decline in hemlock (Tsuga) abundances at 5300 cal yr B.P. Although sea-level rise may have been an influence, moist climatic conditions during the late Holocene were the primary reason for a dramatic rise in water-table elevations.
Dating Early and Middle (Reid) Pleistocene Glaciations in Central Yukon by Tephrochronology
Authors: Westgate John A. , Preece Shari J. , Froese Duane G. , Walter Robert C. , Sandhu Amanjit S. , Schweger Charles E. 
Published: April 2003

AbstractThe late Cenozoic deposits of central Yukon contain numerous distal tephra beds, derived from vents in the Wrangell Mountains and Aleutian arc–Alaska Peninsula region. We use a few of these tephra beds to gain a better understanding on the timing of extensive Pleistocene glaciations that affected this area. Exposures at Fort Selkirk show that the Cordilleran Ice Sheet advanced close to the outer limit of glaciation about 1.5 myr ago. At the Midnight Dome Terrace, near Dawson City, exposed outwash gravel, aeolian sand, and loess, related to valley glaciers in the adjacent Ogilvie Mountains, are of the same age. Reid glacial deposits at Ash Bend on the Stewart River are older than oxygen isotope stage (OIS) 6 and likely of OIS 8 age, that is, about 250,000 yr B.P. Supporting evidence for this chronology comes from major peaks in the rates of terrigeneous sediment input into the Gulf of Alaska at 1.5 and 0.25 myr B.P.
Holocene Soil Development on Till and Outwash Inferred from Lake-Sediment Geochemistry in Michigan and Wisconsin
Authors: Ewing Holly A. , Nater Edward A. 
Published: April 2003

AbstractTwo geochemical techniques from soil mineralogy were used with lake sediment to reconstruct soil development in the catchments of two lakes—one on outwash and the other on till—in the Great Lakes region. A sodium pyrophosphate extraction provides information about leaching of exchangeable and organically complexed cations from terrestrial sources, while an acidified ammonium oxalate extraction removes mineral materials without well-developed crystalline structure that are indicative of podzolization. More evidence of pedogenesis is preserved in sediment of the lake on outwash—likely a result of greater retention of material within the soil profile in the catchment on till. This difference between the records suggests that excessively well-drained (leaky) catchments may provide better records of soil development than those with higher water-holding capacity. Evidence of acidification and podzolization appeared first at the lake on till and 4500 years later at the lake on outwash. Both records reveal a late Holocene intensification of weathering that coincided with a regional climatic change to greater moisture availability. The variability in weathering rates observed presents a more complex picture of weathering than the simple exponential functions often assumed in chronosequence studies. Use of lake sediment records provides better temporal resolution of significant events in soil formation than could be achieved using a chronosequence approach.
Timing and Extent of Allerød and Younger Dryas Age (ca. 12,500–10,00014C yr B.P.) Oscillations of the Cordilleran Ice Sheet in the Fraser Lowland, Western North America
Authors: Kovanen Dori J. , Easterbrook Don J. 
Published: April 2003

AbstractThe use of shaded digital topographic models to visualizes suites of topographic features, stratigraphy, and field mapping reveals newly recognized multiple moraines associated with oscillations of the remnants of the Cordilleran Ice Sheet in the Fraser Lowland along the western Washington–British Columbia border. Morphologic features show the extent of ice represented by Sumas Drift (ca. 11,600–10,00014C yr B.P.), following ca. 3000 yr of retreat from the glacial maximum (Fraser Glaciation) positions 80 km south of Seattle and in the Strait of Juan de Fuca. The paleogeography of the ice margin and timing of ice retreat during the Sumas Stade is reconstructed and bracketed by 70 radiocarbon dates (24 on marine shells, 46 on wood and peat), which are secured by morphologic and stratigraphic evidence. Four topographically distinct phases of the Sumas deglaciation model are suggested.Phase SI: 11,600–<11,40014C yr B.P., outermost drift, scattered remnants of ice-contact depositsPhase SII: 11,600–11,40014C yr B.P., glacier readvance, building prominent moraine followed by glacier retreatPhase SIII: 10,980–10,25014C yr B.P., glacier readvance building of multiple moraines followed by glacier retreatPhase SIV: >10,250–10,000?14C yr B.P., glacier readvance, building of inner moraine followed by glacier retreat
Holocene Lake-Effect Precipitation in Northern Michigan
Authors: Delcourt Paul A. , Nester Peter L. , Delcourt Hazel R. , Mora Claudia I. , Orvis Kenneth H. 
Published: April 2003

AbstractHolocene sediments from Nelson Lake, on Michigan's eastern Upper Peninsula, provide isotopic, pollen, and charcoal evidence for a two-step sequence of changes in moisture source and increased lake-effect precipitation during the late Holocene. Between 8000 and 5300 cal yr B.P., a warm, dry climate and zonal atmospheric circulation produced enriched stable oxygen and carbon isotopic values in combination with high percentages of pine pollen and sustained influx of charcoal particles. After 5300 cal yr B.P., decreasing isotopic values in marl and increasing pollen percentages of mesic hardwoods and northern white cedar indicate increased meridional air flow and precipitation from cold winter storms generated in Alberta, Canada. After 3000 cal yr B.P., abrupt declines in values of δ13C and δ18O and increased pollen representation of hemlock, American beech, spruce, and aquatic plants indicate paludification from increased lake-effect snowfall. The moisture was derived from the Great Lakes and transported by Alberta cyclonic storms that were steered across Lakes Superior and Michigan by a southward shift in the modal winter position of the polar jet stream.
The relationship of placenta previa and history of induced abortion
Authors: Johnson L.G. , Mueller B.A. , Daling J.R. 
Published: April 2003

AbstractObjectives: We evaluated the risk of placenta previa being associated with a history of induced abortion by different surgical procedures. Methods: Cases (n=192) were women who had a singleton delivery complicated by placenta previa at a major obstetric care hospital in western Washington state between April 1, 1990 and December 31, 1992. Controls (n=622) were women with singleton deliveries not complicated by placenta previa or abruption. Odds ratios, determined by logistic regression, approximate the relative risks. Results: Vacuum aspiration abortion was not associated with an increased risk of placenta previa (OR 0.9, 95% CI 0.6–1.5). However, the risk of placenta previa increased with the number of sharp curettage abortions (OR 2.9, 95% CI 1.0–8.5 for ≥3). Conclusions: Risk of placenta previa may be increased in a dose response fashion by multiple sharp curettage abortions. However, vacuum aspiration does not confer an increased risk, and may be a better alternative.
Management of diabetic pregnant patients in a tertiary center in the developing world
Authors: Daponte A , Guidozzi F , Moisuc D , Marineanu A 
Published: April 2003

AbstractObjectives: To audit our insulin regimen in our antenatal diabetics. Methods: 170 pregnant diabetic patients were retrospectively analyzed. Results: The perinatal mortality rate was 37/1000, vs. a perinatal mortality rate of 30/1000 in our setting. Cesarean section rate was 49%. Strict blood‐glucose control reduced the incidence of macrosomia and polyhydramnios. Routine amniocentesis for fetal‐lung maturity was not practiced. Conclusion: Satisfactory results in pregnant diabetic patients are achievable with an established insulin regimen in a developing country.
Mathematical relationships between uterine contractions, cervical dilatation, descent and rotation in spontaneous vertex deliveries
Authors: Sallam H.N , Abdel‐Dayem A , Sakr R.A , Sallam A , Loutfy I 
Published: April 2003

AbstractObjective: To determine the mathematical relationships between the strength and duration of the uterine contractions, the descent and rotation of the fetal head and the degree of cervical dilatation in 50 multiparous women with spontaneous vaginal deliveries using a simple device applied to the fetal vertex. Method: A simple device for monitoring the progress of labor was applied to the fetal vertex. The device allows the continuous monitoring of descent and rotation of the fetal head. The amount of descent and the degree of rotation were also determined by repeated vaginal examinations as well as the degree of cervical dilatation. The frequency of uterine contractions was also recorded on a partogram. Result: A good correlation was found between the amount of descent of the fetal vertex (r=0.975) and between the degree of rotation of the fetal head (0.83) determined by both methods. Multiple regression analysis was then performed and the degree of cervical dilatation in cm at any given time during the first stage of labor was found to be equal to 2.859+0.583 fetal head station in (cm) +0.1983 internal rotation in degrees −0.0493 (station × internal rotation) +0.1599 station2 +0.3622 uterine contractions per 10 min. A nomogram was constructed allowing the calculation of cervical dilatation for a given station of the head, degree of rotation and frequency of uterine contractions. Conclusion: There is a defined mathematical relationship between the degree of descent and rotation of the fetal head, the degree of cervical dilatation and the frequency of uterine contractions in multiparous women with vertex presentation. The first three variables can be continuously determined by using the described device. Incorporation of the device into a reusable fetal scalp electrode allows the dual mechanical and electronic monitoring during labor with minimal vaginal examinations.
Dating fluvial terraces by230Th/U on pedogenic carbonate, Wind River Basin, Wyoming
Authors: Sharp Warren D. , Ludwig Kenneth R. , Chadwick Oliver A. , Amundson Ronald , Glaser Laura L. 
Published: April 2003

AbstractReliable and precise ages of Quaternary pedogenic carbonate can be obtained with230Th/U dating by thermal ionization mass spectrometry applied to carefully selected milligram-size samples. Datable carbonate can form within a few thousand years of surface stabilization allowing ages of Quaternary deposits and surfaces to be closely estimated. Pedogenic carbonate clast-rinds from gravels of glacio-fluvial terraces in the Wind River Basin have median concentrations of 14 ppm U and 0.07 ppm232Th, with median (230Th/232Th) = 270, making them well suited for230Th/U dating. Horizons as thin as 0.5 mm were sampled from polished slabs to reduce averaging of long (≥105yr), and sometimes visibly discontinuous, depositional histories. Dense, translucent samples with finite230Th/U ages preserve within-rind stratigraphic order in all cases. Ages for terraces WR4 (167,000 ± 6,400 yr) and WR2 (55,000 ± 8600 yr) indicate a mean incision rate of 0.26 ± 0.05 m per thousand years for the Wind River over the past glacial cycle, slower than inferred from cosmogenic-nuclide dating. Terrace WR3, which formed penecontemporaneously with the final maximum glacial advance of the penultimate Rocky Mountain (Bull Lake) glaciation, has an age of 150,000 ± 8300 yr indicating that it is broadly synchronous with the penultimateglobalice volume maximum.
Vegetation response to rapid climate change in Central Europe during the past 140,000 yr based on evidence from the Füramoos pollen record
Authors: Müller Ulrich C , Pross Jörg , Bibus Erhard 
Published: April 2003

AbstractThe response of Central European vegetation to rapid climate change during the late Quaternary period (Eemian to Holocene) is assessed by data from the new pollen record of Füramoos, southwestern Germany. This record represents the longest late Quaternary pollen record north of the Alps as currently known. Its high degree of completeness allows detailed correlations with Greenland ice cores and sea–surface temperature records from the North Atlantic. Our data show that if climate deteriorations were not long or severe enough to extirpate refugia of arboreal taxa north of the Alps such as during marine oxygen isotope stage (MIS) 5 (i.e., Würm Stadial A, Stadial B, and Stadial C), reforestation with the onset of warmer conditions in Central Europe occurred on a centennial scale. If arboreal taxa became completely extinct north of the Alps such as during MIS 4 (i.e., Würm Stadial D), several thousand years were necessary for the reimmigration from refugia situated in regions south of the Alps. Thus, Dansgaard–Oeschger interstades (DOIS) 24 to 20 and 15 to 11 are expressed in Central European pollen records, whereas DOIS 19 to 16 are not recorded due to migration lags.
Accuracy of cosmogenic ages for moraines
Authors: Putkonen Jaakko , Swanson Terry 
Published: April 2003

AbstractAnalyses of all published cosmogenic exposure ages for moraine boulders show an average age range of 38% between the oldest and youngest boulders from each moraine. This range conflicts with the common assumption that ages of surface boulders are the same as the age of the landform. The wide spread in boulder ages is caused by erosion of the moraine surface and consequent exhumation of fresh boulders. A diffusion model of surface degradation explains the age range and shows that a randomly sampled small set of boulders (n = 3–7) will always yield a lower age limit for the moraine. The model indicates that for identical dating accuracy, six to seven boulders are needed from old and tall moraines (40,000–100,000 yr, 50–100 m initial height) but only one to four boulders from small moraines (20,000–100,000 yr, 10–20 m). By following these guidelines the oldest obtained boulder age will be ≥90% of the moraine age (95% probability). This result is only weakly sensitive to a broad range of soil erosion rates. Our analysis of published boulder ages indicates that <3% of all moraine boulders have prior exposure, and 85% of these boulders predate the dated moraine.
Electromyography of scoliotic patients treated with a brace
Authors: Odermatt Daniel , Mathieu Pierre A. , Beauséjour Marie , Labelle Hubert , Aubin Carl‐Éric 
Published: April 2003

AbstractWhen a brace is used to correct spinal deviation, patients may seek to ease the discomfort from the pressure exerted by the orthosis by actively recruiting specific trunk muscles. The effect of bracing on trunk electromyography (EMG) has been reported in only one study where a limited number of electrodes were placed mainly in the thoracic region. Our hypothesis was that a multi‐electrode mapping of the activity of the thoracic, lumbar, and abdominal trunk muscles would provide a more representative picture of the muscular reaction in response to bracing. With a larger number of EMG measuring sites, the presence of any brace‐induced trunk muscle activity should be detected. Therefore, EMG signals of 11 adolescent idiopathic scoliosis patients who had been undergoing Boston brace treatment for 0.7‐3 years were collected during four isometric tasks to evaluate the response of trunk muscles in the minutes following the application of the brace. Twenty‐two pairs of bipolar electrodes were used to measure the EMG signals of the main superficial trunk muscles during four isometric tasks. EMG signals of trunk muscles were compared in braced and unbraced conditions. Brace‐induced increases in EMG activity were significant in 43% of the individual measurements and in three of the four tasks for the group mean values. Increases were greater in the lumbar area, especially on the convex side of the secondary (lumbar) curve. These results thus suggest that immediately following the application of the brace, significant muscular responses can be observed in some patients. © 2003 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Chemotherapeutic agents sensitize sarcoma cell lines to tumor necrosis factor‐related apoptosis‐inducing ligand‐induced caspase‐8 activation, apoptosis and loss of mitochondrial membrane potential
Authors: Hotta Takahito , Suzuki Hidekazu , Nagai Shuzou , Yamamoto Kengo , Imakiire Atsuhiro , Takada Eiko , Itoh Mizue , Mizuguchi Junichiro 
Published: April 2003

AbstractChemotherapeutic agents have been used for the treatment of patients with osteosarcoma (OS). However, inherent or acquired resistance to these agents is a serious problem in the management of OS patients. Tumor necrosis factor‐related apoptosis‐inducing ligand (TRAIL) is considered to induce apoptosis in a variety of cancer cells but not normal cells. In the present study, we examined whether chemotherapeutic agents enhance TRAIL‐induced apoptosis in the sarcoma cell lines MG‐63 and SaOS‐2. Pretreatment with sub‐toxic or slightly toxic concentrations of chemotherapeutic agents (cis‐diammine dichloroplatinum, CDDP and doxorubicin, DXR) sensitized both cell lines to TRAIL‐induced apoptosis, as assessed by the propidium iodide or Annexin V‐Cy5 staining method. These cell lines expressed death receptors TRAIL‐receptor 1 (TRAIL‐R1) and TRAIL‐R2, which were unaltered by treatment with CDDP, as assessed by flow cytometry. The decoy receptors TRAIL‐R3 and ‐R4 were barely detected in both cell lines. CDDP down‐regulated c‐FLIP, tending to lower the activation threshold required for TRAIL‐induced caspase‐8 activation. The CDDP‐pretreated cells indeed demonstrated more increased TRAIL‐mediated caspase‐8 activation, loss of mitochondrial membrane potential (ΔΨm), and apoptosis than untreated cells. Consequently, the activated caspase‐8 might lead to either activation of effector caspases such as caspase‐3 or loss in ΔΨm. Both the increased caspase activation and mitochondrial dysfunction induced by combination of CDDP and TRAIL would contribute to enhanced apoptotic cell death. The results of the present study would be valuable for the design of novel treatment modalities for patients with OS. © 2003 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.