bluuebunny/crossref_metadata_2025_split huggingface dataset:
EXCITED SCALAR MESONS IN A CHIRAL QUARK MODEL
Authors: VOLKOV M. K. , YUDICHEV V. L. 
Published: April 2003

First radial excitations of the scalar and pseudoscalar meson nonets as well as their ground states are described as quark–antiquark bound systems in the framework of a nonlocal chiral quark model of the NJL type. Glueball states and their possible mixing with members of the [Formula: see text] multiplets are not considered. Radial excitations are described by means of simple polynomial form factors in the momentum–space which are introduced into the four-quark vertices of the quark Lagrangian. The form factors are chosen in the regime of spontaneous chiral symmetry breaking so that the gap equations do not change their standard form, which provides fulfillment of the low energy theorems. All free parameters of the form factors are fixed by experimentally observed masses of pseudoscalar mesons. All masses of the scalar mesons are predicted. The local six-quark 't Hooft interaction is introduced to solve the so-called UA(1)-problem. The (four particle) singlet–octet mixing for the ground and radially excited states of scalar and pseudoscalar mesons is taken into account. The widths of the main strong decays of the first radial excitation of the scalar meson nonet are calculatedin satisfactory agreement with experimental data. Classification of the considered meson nonets is given. It is shown that the meson states a0(1450), f0(1370), fJ(1710) and [Formula: see text] are the first radial excitations of a0(980), f0(400-1200), f0(980), [Formula: see text].
OPERATOR-PRODUCT EXPANSION AND ANALYTICITY
Authors: FISCHER JAN , VRKOČ IVO 
Published: April 2003

We discuss the current use of the operator-product expansion in QCD calculations. Treating the OPE as an expansion in inverse powers of an energy-squared variable (with possible exponential terms added), approximating the vacuum expectation value of the operator product by several terms and assuming a bound on the remainder along the Euclidean region, we observe how the bound varies with increasing deflection from the Euclidean ray down to the cut (Minkowski region). We argue that the assumption that the remainder is constant for all angles in the cut complex plane down to the Minkowski region is not justified. Making specific assumptions on the properties of the expanded function, we obtain bounds on the remainder in explicit form and show that they are very sensitive both to the deflection angle and to the class of functions considered. The results obtained are discussed in connection with calculations of the coupling constant αs from the τ decay.
MODIFIED BACKJUMPING ALGORITHMS FOR SOLVING CONSTRAINT SATISFACTION PROBLEMS
Authors: CHOWDHURY U. , GUPTA D. K. 
Published: April 2003

The backtracking algorithm is a prominent search technique in AI, particularly due to its use in Constraint Satisfaction Problems (CSPs), Truth Maintenance Systems (TMS), and PROLOG. In the context of CSPs, Dechter5 and Gashnig10 proposed two variants of the backtracking algorithm known as backjumping algorithms. One is graph-based and the other is failure-based backjumping algorithm. These algorithms attempt to backjump to the source of failure in case of a dead-end situation. This improves the backtracking performance. However, these algorithms are not consistent in the selection of the variable to backjump. In this paper, the modifications of both types of backjumping algorithms are proposed. These algorithms adopt a technique to select the variable to backjump in a consistent manner. This further increases the search efficiency in them. The merits of these modified algorithms are investigated theoretically. Experimental results on the zebra problem and random problems show that the modified algorithms give better results on most occasions.
Empirically downscaled temperature scenarios for Svalbard
Authors: Benestad R. E. , Førland E. J. , Hanssen‐Bauer I. 
Published: April 2003

AbstractEmpirically downscaled climate scenarios are presented for the Svalbard region, based on mixed 2‐meter temperature and sea level pressure fields. The scenarios are derived using the large‐scale fields from the ECHAM4‐GSDIO, HadCM3, and NCAR‐CSM climate change experiments, and utilizing common empirical orthogonal functions.There are substantial differences between the scenarios derived from the various models. Those downscaled from the HadCM3 model indicate significantly stronger warming than those based on the ECHAM4‐GSDIO and NCAR‐CSM models. Much of these differences can be explained in terms of the different descriptions of the sea‐ice extent. The sea‐ice in the HadCM3 scenario is subject to a substantial retreat in the Barents Sea, whereas there is no melting in the same region in the NCAR‐CSM model. Copyright © 2003 Royal Meteorological Society.
Abrupt Cooling of Antarctic Surface Waters and Sea Ice Expansion in the South Atlantic Sector of the Southern Ocean at 5000 cal yr B.P.
Authors: Hodell David A. , Kanfoush Sharon L. , Shemesh Aldo , Crosta Xavier , Charles Christopher D. , Guilderson Thomas P. 
Published: April 2003

AbstractAntarctic surface waters were warm and ice free between 10,000 and 5000 cal yr B.P., as judged from ice-rafted debris and microfossils in a piston core at 53°S in the South Atlantic. This evidence shows that about 5000 cal yr B.P., sea surface temperatures cooled, sea ice advanced, and the delivery of ice-rafted detritus (IRD) to the subantarctic South Atlantic increased abruptly. These changes mark the end of the Hypsithermal and onset of Neoglacial conditions. They coincide with an early Neoglacial advance of mountain glaciers in South America and New Zealand between 5400 and 4900 cal yr B.P., rapid middle Holocene climate changes inferred from the Taylor Dome Ice Core (Antarctica), cooling and increased IRD in the North Atlantic, and the end of the African humid period. The near synchrony and abruptness of all these climate changes suggest links among the tropics and both poles that involved nonlinear response to gradual changes in Northern Hemisphere insolation. Sea ice expansion in the Southern Ocean may have provided positive feedback that hastened the end of the Hypsithermal and African humid periods in the middle Holocene.
Late Pleistocene Cosmogenic 36Cl Glacial Chronology of the Southwestern Ahklun Mountains, Alaska
Authors: Briner Jason P. , Swanson Terry W. , Caffee Marc 
Published: April 2003

AbstractThirty-two cosmogenic 36Cl surface exposure ages constrain the timing of two late Pleistocene glacial advances in the western Ahklun Mountains, southwestern Alaska. Boulders were sampled from one early Wisconsin (sensu lato) and six late Wisconsin moraines deposited by ice-cap outlet glaciers and local alpine glaciers. Four moraine boulders deposited during an extensive early Wisconsin ice-cap outlet glacier advance have a mean surface exposure age of 60,300±3200 yr. A moraine deposited by an ice-cap outlet glacier during the restricted late Wisconsin advance has a mean surface exposure age of 19,600±1400 yr. Five moraines deposited by late Wisconsin alpine glaciers have mean ages that range between 30,000 and 17,000 yr. The 36Cl ages are consistent with limiting 14C and thermoluminescence ages from related deposits and indicate that Ahklun Mountains glaciers reached their most extensive position of the last glaciation early during the late Pleistocene, in contrast to the deep-sea isotopic record of global ice volume.1
Late Quaternary Climate Changes in Central Africa as Inferred from Terrigenous Input to the Niger Fan
Authors: Zabel Matthias , Schneider Ralph R. , Wagner Thomas , Adegbie Adesina T. , de Vries Uwe , Kolonic Sadat 
Published: April 2003

AbstractTime series of terrigenous source elements (Al, K, Ti, Zr) from core GeoB4901-8 recovered from the deep-sea fan of the Niger River record variations in riverine sediment discharge over the past 245,000 yr. Although the flux rates of all the elements depend on physical erosion, which is mainly controlled by the extent of vegetation coverage in central Africa, element/Al ratios reflect conditions for chemical weathering in the river basin. Maximum sediment input to the ocean occurs during cold and arid periods, when precipitation intensity and associated freshwater runoff are reduced. High carbonate contents during the same periods indicate that the sediment supply has a positive effect on river-induced marine productivity. In general, variations in the terrestrial signals contain a strong precessional component in tune with changes in low-latitude solar radiation. However, the terrestrial signal lags the insolation signal by several thousand years. K/Al, Ti/Al, and Zr/Al records reveal that African monsoonal precipitation depends on high-latitude forcing. We attribute the shift between insolation cycle and river discharge to the frequently reported nonlinear response of African climate to primary orbital configurations, which may be caused by a complex interaction of the secondary control parameters, such as surface albedo and/or thermohaline circulation.
Late Pleistocene Environments of the Central Ukraine
Authors: Rousseau Denis-Didier , Gerasimenko Natalia , Matviischina Zhanna , Kukla George 
Published: April 2003

AbstractThe Vyazivok loess sequence from the Dnieper Plain, Ukraine, documents regional environmental changes during the late Pleistocene and Holocene. Pedological and palynological analyses and low-field magnetic susceptibility document changes from dense temperate forest during the last interglacial maximum to open, harsh, loess–steppe during the latest Pleistocene. The Vyazivok section overlies hillwash derived from a lower Pleistocene terrace and consists of two stratified soil complexes (Kaydaky and Pryluky; marine isotope stage [MIS] 5 equivalent) separated by a layer of eolian dust (Tyasmyn silt). The lower soils in both complexes formed within forest. These soils are overlain by the Uday (MIS4) and Bug (MIS2) loess units, which are separated by boreal soils of the Vytachiv (MIS3) complex. The coldest conditions within the record occurred in the youngest loess. Holocene soils cap the Bug loess. The Vyazivok section shows remarkable similarities with other classical loess sequences in western Europe, the Czech Republic, and Austria. The Kaydaky, Pryluky, and Vytachiv deposits, correlate with the PKIII, PKII, and PKI soil complexes, respectively, of the Czech Republic. The Tyasmyn and Prylyky silt layers correspond to marker horizons from central Europe.
Age of the Cutler Dam Alloformation (Late Pleistocene), Bonneville Basin, Utah
Authors: Kaufman Darrell S. , Forman Steve L. , Bright Jordon 
Published: April 2003

AbstractLuminescence geochronology, especially infrared stimulated luminescence analyses on marsh mud, shows that a relatively deep lake reached its peak (∼1340 m above sea level) in the Bonneville basin 59,000±5000 yr ago. The age is consistent with nonfinite14C ages and with amino acid geochronology on ostracodes. The Cutler Dam Alloformation was deposited during this lake cycle, which, like the subsequent Bonneville lake cycle, appears to have reached its maximum highstand following the peak of a global glacial stage (marine oxygen-isotope stage 4) but at a time when other records from North America show evidence for cold climate and expanded glacier ice.
Stable Isotopes in Pocket Gopher Teeth as Evidence of a Late Matuyama Climate Shift in the Southern Rocky Mountains
Authors: Rogers Karel L. , Wang Yang 
Published: April 2003

AbstractPrevious work in the San Luis Valley of south-central Colorado and northern New Mexico at the Hansen Bluff and SAM Cave localities has allowed reconstruction of the paleoclimate in the region during the interval from ∼0.6 myr to ∼2.6 myr. Surface exposures at Hansen Bluff have been correlated to deep-sea oxygen isotope core stages 18–23 and one of the glacial periods contained therein to the oldest “Nebraskan” till in southwestern Iowa. Deposits in SAM Cave correlate to Hansen Bluff on the basis of paleomagnetics, climate interpretation, and microtine rodent biochronology. In this paper, carbon and oxygen stable isotope data of herbivorous rodent teeth are used as indicators of change in the predominance of C3, C4, and CAM plants and of changes in temperature and precipitation. Taken together with other previously analyzed data from these localities, the evidence indicates a shift in the severity of glacial events that is mainly related to the hydrologic characteristics of the climate. This shift may have been caused by broad regional uplift that may have been instrumental in shifting global climate cycles from the 41,000-yr Matuyama cycles to the Brunhes 100,000-yr-dominated cycles.
Holocene History of Desertification along the Woodland-Steppe Border in Northern China
Authors: Liu Hongyan , Xu Lihong , Cui Haiting 
Published: April 2003

AbstractThe woodland-steppe ecotone of the southeastern Inner Mongolian Plateau in northern China is located at the northwestern limit of the Pacific monsoon influence, where the landscape may have been a sensitive recorder of past climatic changes. Physical, chemical, and biological analyses of AMS14C-dated sediment sequences from two lakes of this region were used to reconstruct the Holocene vegetation and desertification history and distinguish four periods: (1) a cold and humid period from 10000 to 800014C yr B.P., (2) a warm and humid period from 8000 to 590014C yr B.P., (3) a warm and dry period from 5900 to 290014C yr B.P., and (4) a cool and dry period from 290014C yr B.P. to the present. The increased aridity during the middle Holocene was likely caused by increased winter temperatures and enhanced winter evaporation. The transition from a humid to an arid climate after ∼590014C yr B.P. coincided with enhanced aeolian activity, and deciduous woodlands were replaced by pine woodlands and then by steppes in response to the climatic deterioration. These transitions led to the present desertification. The records suggest that a simple association of thermal and moisture conditions, such as warm/wet or cold/dry, may be misleading.
Wetland Diagenesis and Traces of Early Hominids, Olduvai Gorge, Tanzania
Authors: Deocampo Daniel M. , Blumenschine Robert J. , Ashley Gail M. 
Published: April 2003

AbstractLateral variations in whole-rock and clay geochemistry of basal Bed II claystones in Olduvai Gorge, Tanzania, reflect water quality differences across the Eastern Lacustrine Plain ∼1.75 myr ago. Bulk Ba/Sr and (Na2O+K2O+MgO)/Al2O3range from 1.4 to 4.2 and from 0.7 to 1.4, respectively, and indicate leaching of lacustrine claystones beneath freshwater wetlands at times following lake retreat. Bulk MgO/Al2O3(0.3–1.0) and molar Mg/Al (0.5–3.9) ratios of <0.2-μm clays reflect alteration of Mg-rich lacustrine clays. These indicators point to freshest conditions near Locality 43 of Hay (1976; HWK-East; Leakey, 1971), moderate conditions to the east (Locality 40-MCK), and high salinity and alkalinity to the west (Localities 85-VEK, 45-FLK).Clay geochemistry and artifact abundances are well correlated (r=−0.67,p<0.005), suggesting a relationship between paleo-water quality and hominid paleoecology. This pattern is consistent with predictions of greatest artifact discard/loss around freshwater sources where scavanging opportunities were greatest for hominids. This quantifies a relationship between artifact density distribution and a paleoecological proxy over landscape scales for the first time in Early Stone Age archaeology. In contrast, fossil bone abundance is uncorrelated (r=0.14,p=0.6), reflecting more complex taphonomic processes. Quantitative tests of landscape-scale land-use models are important for understanding early hominid behavior and its evolution.
Placental transfer of rubella‐specific IgG in fullterm and preterm newborns
Authors: Doroudchi M. , Samsami Dehaghani A. , Emad K. , Ghaderi A. 
Published: April 2003

AbstractObjectives: This study was undertaken to investigate placental transfer of anti‐rubella IgG immunoglobulins in Iranian mothers. Methods: In total, 231 pregnant women and their paired infants enrolled in this study of which, 197 gave birth to fullterm and 26 gave birth to preterm infants. Rubella specific antibodies were detected by an in‐house whole‐virus ELISA assay in maternal and cord sera of 188 fullterm and 26 preterm infants. Results: A highly significant correlation was observed between anti‐rubella IgG in newborns in total, in preterm and fullterm neonates with their paired mothers (P‐values=0.0001, 0.002, 0.0001, respectively). A borderline significant difference was observed between mean anti‐rubella IgG in fullterm and preterm neonates (P=0.04). Mean cord/maternal ratio of anti‐rubella IgG was 0.83 which was surprisingly low. A significant lower anti‐rubella IgG was observed in newborns born from mothers with blood group B+ than those born from mothers with blood groups A+ (P=0.04) and O+ (P=0.02), respectively. The same difference was observed between mean maternal anti‐rubella IgG in those with blood groups B+ and A+ (P=0.04) and those with blood groups B+ and O+ (P=0.05). In addition, a low frequency of B+ blood group in high positive sera and a high frequency of this blood group among low positive and negative sera was detected. Conclusions: Our data suggest that the main factors that influence the infants’ rubella‐specific IgG concentration are maternal concentration of this immunoglobulin, maternal blood group, and neonatal gestational age.
Oxygen isotope stage 3 fluvial and eolian successions in Europe compared with climate model results
Authors: van Huissteden K.o , Pollard David 
Published: April 2003

AbstractFluvial and eolian successions of oxygen isotope stage 3 are compared with global (GCM) and regional climate (RCM) modeling experiments of the stage 3 and last glacial maximum climate in Europe. Differences in precipitation between stage-3 stades and interstades were minor, which is confirmed by the fluvial successions. The fluvial response to climate variation is non-uniform, and in southern Europe more pronounced than in northern Europe. The model simulations indicate a strong western winter circulation over Europe during stage 3, which is supported by the eolian deposits data. Wind speeds in the last glacial maximum simulation appear modest compared with those of stage 3, which contrasts with the abundance of eolian deposits. This suggests that during glacial climates the stabilizing effect of vegetation determines eolian sedimentation rates, rather than wind speed. Stage 3 can be divided into an older part (>45,000 cal yr B.P.) with a relatively stable landscape and moist climate and a younger part with more frequent climate change and decreasing landscape stability.
The effect of Holocene temperature fluctuations on the evolution and ecology ofNeotoma(woodrats) in Idaho and northwestern Utah
Authors: Smith Felisa A. , Betancourt Julio L. 
Published: April 2003

AbstractAnimals respond to climatic change by adapting or by altering distributional patterns. How an animal responds is influenced by where it is positioned within its geographic range; the probability of extirpation is increased near range boundaries. Here, we examine the impact of Holocene climatic fluctuations on a small mammalian herbivore, the bushy-tailed woodrat (Neotoma cinerea), at five locations within south central Idaho and northwestern Utah. Previous work demonstrated that woodrats adapt to temperature shifts by altering body size. We focus here on the relationship between body mass, temperature, and location within the geographic range. Body mass is estimated by measuring fossil fecal pellets, a technique validated in earlier work. Overall, we find the predicted phenotypic response to climate change: animals were larger during cold periods, and smaller during warmer episodes. However, we also identify several time periods when changes in environmental temperature exceeded the adaptive flexibility ofN. cinerea.A smaller-bodied species, the desert woodrat (N. lepida) apparently invaded lower elevation sites during the mid-Holocene, despite being behaviorally and physically subordinate toN. cinerea.Analysis of contemporary patterns of body size and thermal tolerances for both woodrat species suggests this was because of the greater heat tolerance ofN. lepida. The robust spatial relationship between contemporary body size and ambient temperature is used as a proxy to reconstruct local climate during the Holocene.
Effects of transcutaneous topical injection of oxygen on vascular endothelial growth factor gene into the healing ligament in rats
Authors: Ishii Yoshimasa , Ushida Takashi , Tateishi Tetsuya , Miyanaga Yutaka 
Published: April 2003

AbstractThe effects of intermittent exposure to oxygen injection on an experimentally induced ligament tear were studied in the right hind limb of 17 male Sprague–Dawley rats. Two rats were used for monitoring the partial oxygen pressure (pO2) of subcutaneous tissue and 15 rats were divided into the following three groups of 5 after an experimentally induced ligament tear: Group A, control group; Group B, injection of 0.5 ml hyaluronan to the wound transcutaneously; Group C, injection of 0.5 ml hyaluronan mixed with haemoglobin and oxygen (n = 5). At 7 days post‐ligament injury, we compared the ligaments of the three treatment groups for gross appearance, histology and expression of vascular endothelial growth factor (VEGF) mRNA by RT‐PCR. Our results indicate that the pO2 was immediately elevated to 334.6 mmHg by topical oxygen injection and this method was effective in promoting vessel formation in comparison to the control group (p < 0.01). However, the expression of VEGF mRNA in the topical oxygen injection group (Group C) was lower than that in control group (p < 0.05). Our results suggest that oxygen is able to accelerate vessel formation in spite of its effect of decreasing VEGF mRNA. Our method of using topical injection proved to be useful in healing the ligament and the wound. © 2003 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.
Quantitative measurement of patellofemoral joint stability: Force–displacement behavior of the human patella in vitro
Authors: Senavongse W. , Farahmand F. , Jones J. , Andersen H. , Bull A. M. J. , Amis A. A. 
Published: April 2003

AbstractPatellofemoral joint instability is a common clinical problem. However, little quantitative data are available describing the stability characteristics of this joint. We measured the stability of the patella against both lateral and medial displacements across a range of knee flexion angles while the quadriceps were loaded physiologically. For eight fresh‐frozen knee specimens a materials testing machine was used to displace the patella 10 mm laterally and 10 mm medially while measuring the required force, with 175 N quadriceps tension. The patella was connected via a ball‐bearing patellar mounting 10 mm deep to the anterior surface to allow natural tilt and other rotations. Patellar force–displacement behavior was tested at flexion angles of 0°, 10°, 20°, 30°, 45°, 60°, and 90°. Significant differences were found between the lateral and medial restraining forces at 10 mm displacement. For lateral displacement, the restraining force was least at 20° of knee flexion (74 N at 10 mm displacement), rising to 125 N at 0° and 90° of knee flexion. The restraining force increased progressively with knee flexion for medial patellar displacement, from 147 N at 0° to 238 N at 90°. With quadriceps tension, the patella was more resistant to medial than lateral displacement. Our finding that lateral patellar displacement occurred at the lowest restraining force when the knee was flexed 20° agrees with clinical experience of patellar instability. © 2003 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved.