bluuebunny/crossref_metadata_2025 huggingface dataset:
The graft‐versus‐leukaemia effect after allogeneic bone‐marrow transplantation: assessment through competing risks approaches
Authors: Katsahian Sandrine , Porcher Raphaël , Mary Jean‐Yves , Chevret Sylvie
Published: December 2004

In failure time studies involving a chronic disease such as cancer, data often focus on one or more non‐fatal events, in addition to survival, to describe the course of the disease. In the example of allogeneic bone marrow transplantation in leukaemic patients, acute graft‐versus host disease (aGvHD), relapse and death were taken as the reported events, and we focused on testing the existence of graft‐versus‐leukaemia (GvL) effect, i.e. that the occurrence of aGvHD modifies the probability of relapse. One of the weaknesses of the standard competing risks models is their inability to model secondary relapses. We thus derived, from two competing risks models, two estimators of cumulative incidence functions of primary and secondary relapses, as well as statistics to test the GvL effect. The approach is illustrated by application to a data set from a cohort of 442 children with acute leukaemia who received an unrelated transplant. Copyright © 2004 John Wiley & Sons, Ltd.
A comparison of goodness of fit tests for the logistic GEE model
Authors: Evans Scott , Li Lingling
Published: December 2004

Generalized estimating equations have become a popular regression method for analysing clustered binary data. Methods to assess the goodness of fit of the fitted models have recently been developed. However, evaluations and comparisons of these methods are limited. We discuss these methods and develop two additional statistics to evaluate goodness of fit. We evaluate the performance of each of the statistics with respect to type I error rates and power in a simulation study. Guidance is provided regarding appropriate use of the statistics under various scenarios. Copyright © 2004 John Wiley & Sons, Ltd.
Choice of time‐scale in Cox's model analysis of epidemiologic cohort data: a simulation study
Authors: Thiébaut Anne C. M. , Bénichou Jacques
Published: December 2004

Cox's regression model is widely used for assessing associations between potential risk factors and disease occurrence in epidemiologic cohort studies. Although age is often a strong determinant of disease risk, authors have frequently used time‐on‐study instead of age as the time‐scale, as for clinical trials. Unless the baseline hazard is an exponential function of age, this approach can yield different estimates of relative hazards than using age as the time‐scale, even when age is adjusted for. We performed a simulation study in order to investigate the existence and magnitude of bias for different degrees of association between age and the covariate of interest. Age to disease onset was generated from exponential, Weibull or piecewise Weibull distributions, and both fixed and time‐dependent dichotomous covariates were considered. We observed no bias upon using age as the time‐scale. Upon using time‐on‐study, we verified the absence of bias for exponentially distributed age to disease onset. For non‐exponential distributions, we found that bias could occur even when the covariate of interest was independent from age. It could be severe in case of substantial association with age, especially with time‐dependent covariates. These findings were illustrated on data from a cohort of 84329 French women followed prospectively for breast cancer occurrence. In view of our results, we strongly recommend not using time‐on‐study as the time‐scale for analysing epidemiologic cohort data. Copyright © 2004 John Wiley & Sons, Ltd.
Construct validity of the Maslach Burnout Inventory‐General Survey
Authors: Kitaoka‐Higashiguchi Kazuyo , Nakagawa Hideaki , Morikawa Yuko , Ishizaki Masao , Miura Katsuyuki , Naruse Yuchi , Kido Teruhiko , Higashiyama Masako
Published: December 2004

The construct validity of the Maslach Burnout Inventory (MBI) has been a major point of focus for many studies. The validity of the MBI‐General Survey (MBI‐GS), a newly developed instrument intended for use outside the human services has not been sufficiently investigated. The aim of this present study is to investigate the validity of the MBI‐GS. The Japanese language version of the MBI‐GS was prepared for this research and it was administered to a sample of intermediate managers (n = 696) working for a manufacturing company in Japan. The total of 691 effective data were obtained. The exploratory factor analysis replicated the same three‐factor structure (Exhaustion, Cynicism, and Professional Efficacy) as the original whereas inter‐factor correlation between Exhaustion and Cynicism was moderate. Cronbach's alpha coefficients for all three subscales were above 0.80. The confirmatory factor analysis supported a three‐factor model whereas Exhaustion and Cynicism were moderately related. To investigate the construct validity, three subscales of the MBI‐GS were then related to selected work characteristics. Based on conservation of resources theory, differential patterns of effects were predicted among the correlates and the burnout subscales. A path analysis revealed that the expectations were largely supported, suggesting that the meaning of the three subscales is quite different with a path from Exhaustion to Cynicism. The study found support for the construct validity of the MBI‐GS. Copyright © 2004 John Wiley & Sons, Ltd.
Plastic changes of leaf mass per area and leaf nitrogen content in response to canopy openings in saplings of eight deciduous broad‐leaved tree species
Authors: Takahashi Koichi , Seino Tatsuyuki , Kohyama Takashi
Published: December 2004

Leaf nitrogen content per area (Narea) is a good indicator of assimilative capacity of leaves of deciduous broad‐leaved trees. This study examined the degrees of increase in Narea in response to canopy openings as leaf mass per area (LMA) and leaf nitrogen content per mass (Nmass) in saplings of eight deciduous broad‐leaved tree species in Hokkaido, northern Japan. Five of the species were well‐branched species with a large number of small leaves (lateral‐growth type), and the other three species were less‐branched species with a small number of large leaves (vertical‐growth type). The degrees of increase in Narea were compared between the two crown types. In closed‐canopy conditions, leaves of the vertical‐growth species tended to have a lower LMA and higher Nmass than those of the lateral‐growth species, which resulted in similar Narea for both. LMA increased in canopy openings in the eight species, and the degrees of increase were not largely different between the lateral‐ and vertical‐growth species. On the contrary, Nmass was unchanged in canopy openings in the eight species. As a result, Narea of each species increased in canopy openings in proportion to the increase in LMA, and the degrees of increase in Narea were similar in the lateral‐ and vertical‐growth species. Therefore, this study showed that the degrees of increase in Narea were not correlated with the crown architecture (i.e., the lateral‐ and vertical‐growth types).
Spatio‐temporal variation of colony structure and eusociality level of the Japanese sweat bee Lasioglossum (Evylaeus) duplex (Hymenoptera: Halictidae)
Authors: Hirata Masanori , Cronin Adam L. , Kidokoro Midori , Azuma Noriko
Published: December 2004

Colony structure and eusociality level of the sweat bee Lasioglossum (Evylaeus) duplex were studied in 2001 in Sapporo and Assabu, Hokkaido, northern Japan. Sakagami and his colleagues had also studied this species in Sapporo in 1957–1968. Brood size, sex ratio and queen–worker size dimorphism were geographically and temporally variable, indicating spatio‐temporal variation at the eusociality level. Inseminated workers constituted only 7.9% of the populations in 1957–1968 Sapporo but about 60% in 2001 in Sapporo and Assabu. A few of the inseminated workers were believed to leave natal nests for independent colony founding. Thus, partial bivoltinism is likely in this sweat bee species. The presence of workers with developed ovaries and/or corpora lutea suggests the occurrence of worker oviposition.
Effect of temporal autocorrelation on apparent growth rate variation in forest tree census data and an alternative distribution function of tree growth rate
Authors: Kohyama Takashi , Kubo Takuya , Macklin Eric
Published: December 2004

Distributions of forest tree growth rates often display wide variation and positive skewness even within a narrow range of tree sizes. Temporal autocorrelation of growth rates is also commonly observed in forest trees. We suggest that temporal autocorrelation causes the positive skew in growth rate distributions. We propose the ‘passage’ distribution of growth rates, defined by the density of trees passing a particular size over a given inter‐census interval, as a superior description of growth performance of trees with temporally autocorrelated growth. We relate the passage distribution to the conventional ‘resident’ distribution of growth rates, defined by the growth rates of trees within a particular size range at a given census. The passage distribution is approximated by the resident distribution weighted by the absolute growth rate. For common rain forest tree populations, the average of the passage distribution is nearly twice that of the resident distribution. Simulation models which use growth rates estimated from resident distributions and assume a Markov process are valid only to reconstruct the dynamics of the overall size structure of a stand. When examining the influence of life history strategy on forest dynamics, models must incorporate the effect of temporal autocorrelation on growth rates.
Bacterial biomass on fine detritus particles in a woodland stream of Hokkaido, Japan
Authors: Kamauchi Hiromitsu
Published: December 2004

Bacterial biomass on four different size fractions of benthic fine particulate organic matter (FPOM) was measured throughout a year in a woodland stream in Hokkaido, Japan. Bacterial biomass per ash free dry mass (AFDM) of the FPOM was significantly different among the four size fractions, while the biomass per unit surface area of FPOM was not. Annual mean of bacterial biomass per particle mass positively correlated to the surface area per mass in the four size fractions. In addition, negative correlation was found between the C:N ratio and bacterial biomass per AFDM in FPOM when all fractions were pooled. There was also negative correlation between C:N ratio and the surface area per particle mass in the four size fractions. The difference of bacterial biomass on FPOM among the size fractions could be ascribed to surface area and/or C:N ratio of FPOM, although these effects were not separately evaluated in the present study.
Edge effects in a tropical montane forest mosaic: experimental tests of post‐dispersal acorn removal
Authors: López‐Barrera Fabiola , Newton Adrian , Manson Robert
Published: December 2004

Forest edges created by scattered‐patch clear‐cutting have become common in tropical montane cloud forests in the highlands of Chiapas, Mexico. It was hypothesised that forest edges may influence regeneration of oak species, which are canopy dominants in these forests, by affecting the activities of small mammal species. Acorns of different oak species varying in germination timing were offered to predators and/or dispersers at different positions along replicated forest edges during 2 consecutive years. We investigated the effects of (1) edge type (hard and soft), (2) distance from the edge (0, 15, 30, 45 and 60 m inside forest fragments) and (3) oak species, on the rate of acorn removal mainly by small mammals. During a non‐masting year, acorn removal was affected by the interaction of edge type and distance from the edge (P<0.05), with acorn removal being highest near hard edges compared to adjacent forest interiors. As predicted, acorn removal was greater along soft (100%) than along hard edges (82%), but this pattern was recorded only during the non‐masting year. This study partly supports previous studies of rodents preferentially consuming acorns with early germination rather than acorns exhibiting dormancy, however these patterns may change with variation in acorn abundance. These results suggest that patch clear‐cutting affects regeneration processes within forest fragments by influencing the activities of small mammals, but the nature of this effect also depends on acorn abundance and the characteristics of the forest edge created.
Niche construction and polymorphism maintenance in metapopulations
Authors: Hui Cang , Yue Dongxia
Published: December 2004

Niche construction, a term referring to the modification of their environments by any organism, can profoundly influence the genetic dynamics and structure of a metapopulation. Through niche construction, we give the dynamics and spatial structure of genotype frequencies using one‐ and two‐dimensional metapopulation lattice models, and these models generate archipelago‐like structures in space through an ecological imprint in order to maintain polymorphism with low genetic load within demes, which do not need heterozygote superiority. With habitat deterioration and restoration, niche construction generates a threshold phenomenon and obstructs the changes in environments. Hence, in practice, restoration is a more difficult process than deterioration. Furthermore, niche construction may serve as an important mechanism for maintaining diversity in nature, including genetic, species and ecosystem diversity.
Biomass and production of a naturally regenerated oak forest in southern Korea
Authors: Park In Hyeop , Son Yowhan , Kim Dong Yeob , Jin Hyun O , Yi Myong Jong , Kim Rae Hyun , Hwang Jung Ok
Published: December 2004

Biomass and production of two stands with Quercus variabilis Bl. as the dominant species (stands 1 and 3) and one with Q. mongolica Fisch. as the dominant species (stand 2) were investigated in southern Korea. Stands 1 and 3 naturally occurred on sites with southerly aspects while stand 2 naturally occurred on northerly aspects; stand ages were similar for the three stands (36–38 years old). Total above‐ and belowground biomass including understory vegetation (Mg ha−1) was 108.4 for stand 1, 115.6 for stand 2, and 132.0 for stand 3, respectively. Understory vegetation constituted 17.4% of the total biomass in stand 1 but only 3.7–4.5% in stand 2 and stand 3. Roots constituted 20.1–24.6% of the biomass of the overstory vegetation. Although stand 3 showed the highest total biomass, net production was highest in stand 2 at 12.6 (Mg ha−1 year−1); net production levels for stands 1 and 3 were 11.7 and 11.1 (Mg ha−1 year−1), respectively. It appeared that the differences in site conditions related to aspect influenced the distribution of naturally regenerated oak species within a relatively small area and resulted in differences in biomass and production among the stands.
Foraging modes of stream benthic fishes in relation to their predation effects on local prey density
Authors: Inoue Mikio , Miyayoshi Masanobu , Sone Shin
Published: December 2004

Habitat use and foraging behavior of two benthic insectivorous gobies, Rhinogobius sp. CO (cobalt type) and Rhinogobius sp. DA (dark type), were examined in relation to their predation effects on local prey density in a small coastal stream in southwestern Shikoku, Japan. Correlations among the foraging range, frequency of foraging attempts and current velocity indicated that individuals using fast‐current habitats had small foraging ranges and infrequently made foraging attempts while those in slow currents frequently foraged over large areas. The former and the latter were recognized as ambush and wandering foragers, respectively. Interspecific comparisons of habitat use, foraging behavior and prey preference suggested that Rhinogobius sp. CO selectively forage mobile prey by ambushing in fast currents, whereas Rhinogobius sp. DA randomly forage available prey by wandering in slow‐current habitats. A cage experiment was conducted to assess prey immigration rate and the degree of predation effects on local prey density in relation to current velocity. The results of the experiment support, at least in part, our initial predictions: (1) prey immigration rates increase with current velocity and (2) the effects of fish predation on local prey density are reduced as current velocity increases. Overall results illustrated a link between the foraging modes of the stream gobies and their predation effects on local prey density: fish adopt ambush foraging in fast currents, where the decrease in prey density tends to be less, whereas fish actively forage over large areas in slow currents, where the decrease in prey is relatively large.
Quaternary Periglacial Records of Voles of the Genus Phenacomys Merriam (Cricetidae: Rodentia)
Authors: Guilday John E. , Parmalee Paul W.
Published: December 2004

Quaternary occurrences of voles of the genusPhenacomyssouth of the North American continental glaciation range in age from Kansan through early Recent times and are mapped from twenty fossil localities.Phenacomyscannot be used as an index fossil, but makes a good climatic indicator because of its modern boreal affinities. It is largely confined to the present day Canadian and Hudsonian Life Zones of North America.
Quaternary Paleoecology and Stratigraphy of the Sea Cliffs, Western Olympic Peninsula, Washington
Authors: Florer Linda E.
Published: December 2004

The sea cliffs of the western Olympic Peninsula are composed chiefly of discontinuous beds of unconsolidated gravel, sand, silt, and peat of Pleistocene age. Two lower stratigraphic units, the “Steamboat Creek gravel” and “Joe Creek silt”, were deposited probably during the Puyallup Interglaciation; the upper unit, the “Kalaloch silt”, was deposited during an interval that extends from Salmon Springs Glaciation through Fraser Glaciation. Radiocarbon dates of the Kalaloch silt range from about 17,000 to > 48,000 BP.

Pollen analysis and stratigraphic correlation of the sea cliff sediments indicate that the present vegetation of the Olympic Peninsula has existed in this part of western Washington since the Puyallup Interglacial. During the Puyallup, the low elevation Tsuga heterophylla-Picea forest or its seral stages were predominant. During subsequent glaciations the low elevation forest was replaced by montane or alpine plant communities in areas near the ice front. At sites farther removed from glacial termini, low elevation forest apparently persisted, thriving in centers from which constituent species spread during interstadials.
Stratigraphy and Origin of the Paha Topography of Northwestern Illinois
Authors: Flemal Ronald C. , Odom I. Edgar , Vail Ronald G.
Published: December 2004

The paha of northwestern Illinois are longitudinal dunes developed in toto during Woodfordian time. Cores of noneolian materials, such as are typical in the paha of northeastern Iowa, are either not present or much reduced in numbers in the paha of Illinois. Variation in the thickness of the surface blanket of Peoria Loess accounts for the total topographic expression of the Illinois paha.

Underlying the Peoria Loess is a sequence of Pleistocene deposits consisting of two tills of Illinoian age, and the Plano Silt and Roxana Loess of Altonian age. Radiocarbon ages obtained from the Plano Silt range from 41,900 ± 1300 to 34,630 ± 710 radiocarbon years B.P.
Some Effects of Partial Recrystallisation on 14C dating Late Pleistocene Corals and Molluscs
Authors: Chappell John , Polach Henry A.
Published: December 2004

The issue of sea level during the last interstadial revolves largely around the problem of achieving reliable 14C dates for shell carbonate from Late Pleistocene shallow marine and littoral deposits. A set of 27 samples were collected from Late Pleistocene reefs in New Guinea, and measurements made of 13C, 14C, plus the degree of recrystallisation (determined by X-ray diffraction). The original fibrous aragonite structure of the samples (corals and clams) is seen in thin section to recrystallise in two quite different modes. The carbon isotope results strongly suggest that one mode, the sparry calcite recrystallisation, represents an open geochemical system which allows contamination by more recent 14C, while the subtle coarsening mode of recrystallisation represents a closed system, often yielding reliable results. The reliability of the latter can be validated if a similarly recrystallised sample, known to be outside the range of 14C dating, shows a background 14C count.
Climatology of a Glacial Cycle
Authors: Fairbridge Rhodes W.
Published: December 2004

A “glacial cycle” is defined as a major global climatic oscillation of the order of 105yr, developed within an “ice age”sensu latowhich may last 106–107yr and which recurs at widely spaced intervals in geologic time (ca. 2 × 108yr). The ice age situation thus only persists during 5–10% of all geologic time and is preconditioned by geotectonics andnotby extraterrestrial controls.

The repetitive nature of the glacial cycle is demonstrated by independent records from (a) glacigenic, ice-melt deposits, i.e., tills and fluvioglacial terrace accumulations; (b) eolian by-products, i.e., loess; (c) marine terraces and beach deposits, eustasy inversely reflecting the ice volumes; and (d) deep-sea deposits, biologically and lithologically reflecting the climatic events. Only the marine section offers a continuous, uninterrupted record. Different chronometric techniques confirm a major cycle of the order of 105yr (eight repetitions in the last 700,000 yr), but there are multiple types of modulation, in part related to self-accelerating feedback, either negative (retardation) or positive, leading to acceleration.

Within any given cycle there is an Interglacial, Anaglacial, Pleniglacial and Kataglacial phase, characteristics of which are repeated on a small scale in minor cycles. Their timing is variable in a latitudinal sense, apparently steered by radiation changes that first affect the tropics.

Interglacials are defined in their classical stratotype areas of NW Europe, by sedimentary sequences characterized by the pollen of deciduous forests, pointing to climates at least as warm as those of the present time. The present cycle began ca. 10,000 YBP, with the start of the Holocene epoch, and the contemporary warm phase is seen as a typical interglacial stage. Such warm peaks characteristically last about 10,000 yr. Symptoms of the expected ensuing glaciation range from a global fall in temperature since mid Holocene, to tropical desiccation (growth of deserts) and high latitude retreat of tree lines.
Appraisal of the Future Climate of the Holocene in the Rocky Mountains
Authors: Richmond Gerald M.
Published: December 2004

Consideration of the history of Holocene climate in the Rocky Mountains indicates that the over-all trend during the past 2500 yr has been toward increasing warmth, interrupted by cooler times of minor advances of cirque glaciers. Comparison of Holocene climatic history with the record of past interglacials in the region suggests that the present interglacial is not complete and that the climate may become first warmer and subsequently wetter before it is completed. Correlation of the timing of the regional glacial-interglacial record for the past 140,000 yr with the record of major sea level changes and with the calculated changes in the earth's insolation suggest that the present interglacial may be completed within a few millenia and that it may be followed by a significant cooling of the climate.
Diatom Evidence Bearing on the Holocene in the South Atlantic
Authors: Burckle Lloyd H.
Published: December 2004

The Pleistocene/Holocene boundary is easily recognized in deep-sea cores from the South Atlantic as an upward change from predominantly shelf and meroplanktonic diatoms to holoplanktonic forms. Those cores with high sedimentation rates show several climatic fluctuations during the Holocene. One core (E 7-1) from the Scotia Sea has a sufficiently expanded Holocene to reveal three distinct coolings at approximately 4600 yr BP, 2800 yr BP and 1000 yr BP. This compares favorably with the results of other workers.
When Will the Present Interglacial End?
Authors: Mörner Nils-Axel
Published: December 2004

We are now living under interglacial climatic conditions, the Present Interglacial or Flandrian Interglacial Age. It will certainly be followed by the Future Ice Age. The major cold/warm changes seem to have a cyclicity of 10,500 yr. We have been in the second cycle (characterized by cooler climate) after the Last Ice Age for 2200 yr and will continue to be so for another 8300 yr. By analogy with the conditions during the Last Interglacial it is concluded that this cycle will remain moderately warm. With the end of the third cycle at about 18,800 years AP, the Present Interglacial will end and the First Future Glacial Age begin. Further information about the climatic conditions during the “cold” cycle 117,700–107,200 y. a. is necessary, however, before a really well-founded prediction can be made.
Climatic Record in North Atlantic Deep-Sea Core V23-82: Comparison of the Last and Present Interglacials Based on Quantitative Time Series
Authors: Sancetta Constance , Imbrie John , Kipp N.G. , McIntyre Andrew , Ruddiman W.F.
Published: December 2004

In North Atlantic deep-sea core V23-82, changing surface water conditions are revealed by changing composition of fauna and flora. Sedimentation rate seems to vary little so that approximate dating of climatic events within the X zone of Ericson is possible. These include an interglacial temperature maximum at 124,000 YBP; start of the post-Eemian cooling at about 116,000 YBP; and peak cool conditions at about 110,000 YBP, followed by warming.

Drop in summer and winter temperatures about two-thirds of the way towards full glacial values and a significant drop of salinity is suggested by quantitative paleoenvironmental analysis of the 110,000 YBP cold episode.

If the Eemian is taken as the analog of the present interglacial, a point in time 116,000 YBP becomes the historical model for today's ocean, and the North Atlantic is now approaching a time of severe cooling.
Abrupt Climatic Change at 90,000 yr BP: Faunal Evidence from Gulf of Mexico Cores
Authors: Kennett James P. , Huddlestun Paul
Published: December 2004

Planktonic foraminiferal studies have been carried out on 28 piston cores of late Pleistocene age from the western Gulf of Mexico, an area of high sedimentation rates. For the interval between 73 × 103 and 95 × 103 yr BP, two of these cores have sedimentation rates of 12 and 15 cm/1000 yr. Calculation of the speed of faunal changes within this interval reveals an extremely rapid paleoclimatic-paleooceanographic change at approximately 90 × 103 years BP. Several species including distinctly warm-sensitive forms, then disappeared from the Gulf of Mexico in less than 350 yr, leaving a depleted planktonic foraminiferal fauna greatly dominated by only three species with little apparent temperature preference. This fauna existed for 2.5 × 103 yr after which distinctly cooler water elements increased in abundance rapidly and formed a high frequency peak approx 83.5–85 × 103 years BP. This increase in cooler water elements reflects either a return to more stable environmental conditions or a lag in their migration to the Gulf of Mexico after the severe climatic cooling, rather than further cooling.

The faunal event in the Gulf of Mexico correlates with an even more spectacular event recorded in the Greenland ice sheet by a drop in 18O values within a time interval of only about 100 yr (Dansgaard et al., 1971, 1972). A possibly correlative climatic event of similarly rapid nature has also been reported for speleothems from southern France (Duplessy et al., 1970).

The paleoclimatic event is closely associated stratigraphically with a widespread volcanic ash layer, although it is possibly significant that the increased volcanism occurred 1000 yr after the paleoclimatic event. A rapid lowering of the lysocline occurs simultaneously with the paleoclimatic event although faunal diversity is low in the succeeding fauna despite decreased calcium carbonate solution. Both the association with volcanism and changes in the position of the lysocline may be significant in consideration of mechanisms of such rapid climatic changes. In turn, such rapid paleoclimatic-paleooceanographic changes as observed in tropical Gulf of Mexico cores, in the Greenland ice sheet and in caves of southern France must be considered in the evaluation of causal mechanisms of glacial and interglacial oscillations.
The Salinity of the North Atlantic Ocean and the Next Glaciation
Authors: Weyl Peter K.
Published: December 2004

A reduction in the surface salinity of the North Atlantic, by causing an extension of sea ice, could initiate the next Glacial period. Such a salinity reduction could be the result of a slight persistent change in surface pressure in the Caribbean area, that reduces the transfer of water vapor from the Atlantic to the Pacific across the Isthmus of Panama.
On Climatic Changes
Authors: Stuiver Minze
Published: December 2004

Some tentative ideas concerning correlations between solar radiation, gravity, and geomagnetism are given. It is suggested that long-term gravitational effects, associated with planetary configurations, may cause variable solar output.
Atmospheric Particles and Climate: can we Evaluate the Impact of man's Activities?
Authors: Schneider Stephen H.
Published: December 2004

The equilibrium temperature of the Earth is maintained by a balance between the unreflected part of the incoming solar energy, which is absorbed by the Earth-atmosphere system, and the outgoing long-wave radiation escaping from the Earth to space. It has long been suspected that suspended atmospheric particles (aerosols) might affect this balance, primarily by affecting the albedo or reflectivity of the Earth, thereby altering the amount of solar energy absorbed by the Earth. In light of some recent evidence suggesting the existence of an increase in atmospheric particle concentrations (presumably related to man's activities), the need for development of adequate numerical models to study this problem is apparent. Recent numerical models studying the effect of particles on climate are often based on multiple scattering radiative transfer calculations, and use global averages for particle concentrations and optical properties. By contrasting certain existing models, some major problems in modeling studies that attempt to answer the question of the effects of increased atmospheric particles on climate can be illustrated. It will also be apparent that another uncertainty in the results of such studies arises from a lack of adequate observed input data on the geographic and vertical distributions of particle concentrations and their optical properties. Furthermore, a model that could realistically simulate the impact of increasing atmospheric particle concentration on climate must eventually include the simultaneous coupled effects of all the important atmospheric processes, such as fluid motions and cloud microphysics, in addition to the radiative transfer effects. Current modeling studies already do predict that increases in particle concentrations could have a significant effect on climate. Now, it remains for us to develop the kinds of refined models needed to verify or deny these predictions.
Stratigraphic and Paleoclimatic Analysis of Late Pleistocene Tropical Southeast Pacific Cores (with an Appendix by N. J. Shackleton)
Authors: Luz Boaz
Published: December 2004

Factor analysis of dissolution-resistant species of planktonic foraminifera in the >250 μm fraction of seabed and core samples from the tropical southeast Pacific yields five mappable varimax assemblages. The distribution of these assemblages in core tops is more related to the subsurface thermal structure than to the surface temperature. A transfer function relating the assemblages in core tops to the temperature at 200 m is applied to five cores. Cycles of estimated temperature in three cores are approximately in phase with climatic cycles in Atlantic cores spanning the past 200,000 yr, and display amplitudes on the order of 5°C. Two zones of increased calcium carbonate dissolution occur in these three cores. These zones occur in the transition from interglacial to glacial intervals. Temperature variations inferred are ascribed to fluctuations of the main thermocline, and the inference is made that during cold intervals the thermocline was displaced upward as the central water mass was areally diminished. A model of circulation dynamics suggests that such areal diminution would be associated with an intensified circulation. No significant fluctuations in the estimated 200 m temperature are inferred for a core in the Galápagos area during the last glacial, but a pronounced peak of high-latitude species Globorotalia inflata does occur. This peak is judged to reflect the removal of a low-oxygen ecological barrier.
North Pacific Radiolarian Assemblages and their Relationship to Oceanographic Parameters
Authors: Sachs Harvey Maurice
Published: December 2004

A quantitative study of the distribution of Radiolaria in surface sediments of the North Pacific has demonstrated the feasibility of utilizing complete radiolarian thanatocoenoses as indicators of past oceanographic conditions.

In samples from 36 core tops from the region 33° N-54° N, 148° E-140° W, 87–96% of all radiolarians encountered could be assigned to one of 120 taxa recognized. Q-mode factor analysis of distributional data for the 57 most abundant species yields four independent assemblages. Three of these reflect near-surface oceanographic conditions, and the fourth responds to bottom conditions. Regression-developed transfer functions describe the relationship between the assemblages and oceanographic parameters.
Climatic Record of the Past 130,000 Years in North Atlantic Deep-Sea Core V23-82: Correlation with the Terrestrial Record
Authors: Sancetta Constance , Imbrie John , Kipp N.G.
Published: December 2004

Quantitative paleo-environmental analyses of planktonic foraminifera in 182 samples covering the past 130,000 years in North Atlantic deep-sea core V23-82 yield time series interpreted in terms of changing surface-water conditions. An absolute chronology is estimated by linear interpolation between levels dated by 14C or by stratigraphic correlation with other radiometrically dated climatic records. Significant events include: (1) rapid warming at 127,000 YBP, marking the start of the penultimate North Atlantic and European interglacial; (2) 124,000 YBP temperature maximum (Eemian); (3) 109,000 YBP cooling, correlated with the beginning of the last European glaciation (Würm), and representing a temporary cooling of the North Atlantic; (4) severe cooling 73,000 YBP, marking the start of the last full glacial regime in the North Atlantic; (5) short warm intervals within the last glacial regime dated at 59,000 YBP, 48,000 YBP, and 31,000 YBP; (6) rapid termination of the last glacial interval at 11,000 YBP; (7) a 6000 YBP hypsi-saline, followed by lowering salinity values presumably associated with decreasing flux of Gulf Stream waters over the core site.
Relative Elevation of Late Pleistocene High Sea Level Stands: Barbados Uplift Rates and their Implications
Authors: Matthews R.K.
Published: December 2004

Calculations confirm that the uplift of Barbados during the past 130,000 yr has been at nearly constant relative rates in the Clermont and Christ Church standard traverses, and that sea levels responsible for Barbados terraces I (82,000 yr B.P.) and II (105,000 yr B.P.) attained approximately the same level which was 20–25 m below the level represented by Barbados III (125,000 yr B.P.).

Preference for the correlation of Barbados III with the prominent first interglacial 18O peak in stage 5 is stated once again. Further, correlation with Eemian and Pangaion of the European pollen record is suggested.
Changes in the Poleward Energy Flux by the Atmosphere and Ocean as a Possible Cause for Ice Ages
Authors: Newell Reginald E.
Published: December 2004

It is proposed that the two preferred modes of temperature and circulation of the atmosphere which occurred over the past 100,000 yr correspond to two modes of partitioning of the poleward energy flux between the atmosphere and ocean. At present the ocean carries an appreciable fraction of the transport, for example about three-eighths at 30°N. In the cold mode it is suggested that the ocean carries less, and the atmosphere more, than at present. During the formation of the ice, at 50,000 BP, for example, the overall flux is expected to be slightly lower than at present and during melting, at 16,000 BP, slightly higher. The transition between the modes is seen as a natural imbalance in the atmosphere-ocean energy budget with a gradual warming of the ocean during an Ice Age eventually cluminating in its termination. At the present the imbalance is thought to correspond to a natural cooling of the ocean, which will lead to the next Ice Age.

The magnitude of temperature changes in the polar regions differ between the hemispheres in the same way as present seasonal changes, being larger in the northern than in the southern hemisphere.

Overall the atmospheric energy cycle was more intense during the Ice Ages than now.

Observational tests are proposed by which predictions from the present arguments may be compared with deductions about the environment of the past.

Data used for the present state of the atmospheric general circulation are the latest global data available and contain no known major uncertainties. However, data for the oceanic circulation and energy budget are less well known for the present and almost unknown for the past. Hence the proposed imbalances must be treated as part of a speculative hypothesis, but one which eventually may be subject to observational test as no solar variability is invoked.
Geological and Ecological Perspectives on the Middle Pleistocene
Authors: Butzer Karl W.
Published: December 2004

This paper evaluates the geological and paleoecological implications of a Wenner-Gren symposium Stratigraphy and Patterns of Cultural Change in the Middle Pleistocene. The deep-sea, glacial-eustatic, loess, alluvial, and palynological records suggest between six and eight cold-warm cycles since the Brunhes-Matuyama magnetic reversal of 700,000 BP. Till and outwash stratigraphies are inadequate to provide a valid nomenclature for the numerous glacials preceding the Würm. Since at least five of the glacials since 700,000 BP were sufficiently severe to produce permafrost in midlatitude Europe, the “glacial Pleistocene” begins with the Brunhes-Matuyama. Although earlier cold-warm cycles extend well back into the early Pleistocene, with extensive glaciation and repeated floral decimations in higher latitudes, the first record of permafrost in the Rhine Basin 700,000 BP argues that major climatic oscillations of the Brunhes epoch were of glacial-interglacial amplitude. It is therefore recommended that a Lower-Middle Pleistocene boundary be linked to the practicable and universally applicable chronometric horizon provided by the Brunhes-Matuyama reversal, while the Middle-Upper Pleistocene limit can continue to be drawn at the base of the last, Eemian Interglacial (130,000 BP). The tropical African record presently contributes little to general understanding of the Middle Pleistocene, while the climatic cycles of higher latitudes are of limited value in analyzing mid-Pleistocene records of the tropical continents. Problems of stratigraphic control and environmental contexts for archeological sites are discussed.
Faunal Dating of the Late Cenozoic of Southern Africa, with Special Reference to the Carnivora
Authors: Hendey Q.B.
Published: December 2004

Since chronometric data comparable to that available from the late Cenozoic succession of East Africa have not, and probably cannot be obtained in southern Africa, faunal dating methods retain their traditional significance in the latter area. Five successive late Cenozoic mammal ages, the Namibian, Langebaanian, Makapanian, Cornelian, and Florisian have been proposed as a framework for discussions relating to the chronology of southern African mammalian faunas. The Namibian fauna is poorly known, but is evidently of Miocene age. It is not discussed in this paper. The Langebaanian fauna is well known only from the prolific occurrence at the type site of Langebaanweg and is Pliocene in age. Makapanian faunas are best represented at the Transvaal Australopithecine sites and probably overlap the Plio-Pleistocene boundary. The Cornelian fauna is not as well known as others, the largest assemblage having been recorded from Elandsfontein, although this assemblage is one which is unfortunately temporally heterogeneous. Florisian faunas have been recovered from a relatively large number of localities, including several for which there are radiometric dates. The recorded southern African fossil Carnivora are listed and the local evolution of this group is discussed in terms of the mammal age chronology. It is concluded that secure faunal dating of individual fossil occurrences is enhanced by an appreciation of the nature of changes undergone in evolutionary lineages, while an uncritical knowledge of recoreded taxa is less useful.
Late Quaternary Vegetational Changes on the East Side of Yellowstone Park, Wyoming
Authors: Waddington Jean C.B. , Wright H.E.
Published: December 2004

A bog pond 4 km east of Yellowstone Lake has a pollen record starting with an Artemisia spruce assemblage, implying alpine vegetation. A layer of volcanic ash, dated as 14,360 ± 400 BP (probably Glacier Peak or Mt. St. Helens J), occurs within the zone, which terminates at 11,630 ± 180 BP. The rest of the pollen sequence is dominated by lodgepole pine, with reappearance of spruce pollen in modest quantities about 4500 BP, according to dating provided by a layer of Mt. Mazama ash (6600 BP). The present vegetation of the area is marked by forests of lodgepole pine with some stands of spruce and fir. The pollen sequence suggests that the upper treeline before 11,600 y. a. was perhaps 500 m lower than today. The climate then became warmer and/or drier than today (Altithermal interval). About 4500 y. a., a slight climatic reversal took place, roughly contemporaneous with the regrowth of glaciers in the western mountains (neoglaciation).
Quaternary Sea Level Fluctuations on a Tectonic coast: New 230Th/234U Dates from the Huon Peninsula, New Guinea
Authors: Bloom A.L. , Broecker W.S. , Chappell J.M.A. , Matthews R.K. , Mesolella K.J.
Published: December 2004

Emerged coral reef terraces on the Huon Peninsula in New Guinea were reported in a reconnaissance dating study by Veeh and Chappell 1970. Age definition achieved was not good for several important terraces, and we report here a series of new 230Th/234U dates, which further clarify the history of late Quaternary eustatic sea level fluctuations. More than 20 reef complexes are present, ranging well beyond 250,000 yr old: we are concerned with the seven lowest complexes. Major reef-building episodes dated by 30Th/234U are reef complex I at 5–9 ka (kilo anno = 1000 yr), r.c. IIIb at 41 ka (four dates), r.c. IV at 61 ka (four dates), r.c. V at 85 ka (two dates), r.c. VI at 107 ka (two dates), and r.c. VII at 118–142 ka. Complex II was previously dated by 14C at 29 ka: this age has not yet been confirmed, and may be only a lower limit. The reef crests were built during or immediately before intervals of sea level maxima, when rates of rising sea level and tectonic uplift briefly coincided. The culmination of each reef-building episode was only a few thousand years in duration, and multiple dates from the same reef complex generally group within the statistical errors of the individual dates.

Several methods can be used to estimate the altitude of each sea level maximum relative to present sea level. The least complicated is to calculate mean tectonic uplift rate for each profile of the terraces, and use the mean rate to calculate the tectonic displacement of each dated reef complex on that profile. The difference between the present altitude of a reef complex and its calculated tectonic uplift gives the paleosea level at the time the reef grew. We estimate uplift rates for six surveyed sections by calibrating against published paleosea level estimates from Barbados and elsewhere, viz 125 ka, paleosea at +6 m; 103 ka, −15 m; 82 ka, −13 m. For each section the individual uplift rates for reefs V, VI, and VIIb are within 5% of their section means. Using the mean rates. paleosea level estimates for reef crests II, IIIB, and IV are made for each section. Consistency of estimates between sections is good, giving −28 m for the 60 ka paleosea level, around −38 m for the 42 ka level and −41 m for the 28 ka level (if the age is older the paleosea level would be lower. Using the mean uplift rates, the 82 ka and 103 ka paleosea levels are also estimated for each section: all individual estimates are plotted graphically, and a sea level curve drawn. The reef stratigraphy indicates sea level lowerings between each dated reef crest: the crests probably represent the interstadials of the Wisconsin (Würm, Weichsel) Glaciation, and intervening lower levels correspond to stadials. Since the last time of eustatic sea level higher than the present (about 125 ka), five sea level maxima occurred at roughly 20-ka intervals, none being as high as the present.
A Study of Late Pleistocene Loess Deposits, South Canterbury, New Zealand Part II. Paleosols and their Stratigraphic Implications
Authors: Tonkin P.J. , Runge E.C.A. , Ives D.W.
Published: December 2004

Examination of loess columns in coastal South Canterbury, New Zealand, and the recognition of paleosols with comparable morphology to surface soils allowed the division of the loess column into six members. The upper loess members 1–4 are grouped into a proposed Dashing Rocks Formation. This commonly overlies an erosion surface on Timaru Basalt, but in some situations is underlain by loess member 5 and mixed loess and weathered basalt member 6. The paleosol developed on loess member 5, on both morphological and chemical evidence, is indicative of a period of soil formation of longer duration or greater intensity than is indicated by the overlying paleosols or surface soils. Therefore members 5 and 6 are grouped into a separate formation.

A radiocarbon chronology for loess members 1 and 2 of the Dashing Rocks Formation, suggests loess accumulation phases from 9900 to 11,800 and prior to 31,000 radiocarbon yr BP, followed by periods of soil formation and contemporary peat development in surface depressions.

A hypothesis is presented suggesting that at least loess members 1 and 2 of the Dashing Rocks Formation accumulated during periods of glacial recession which in turn precipitated fluvial and eolian erosion, transport and redeposition of fluvioglacial deposits. The periods of soil development indicated by the paleosols were initiated during warm interstadial conditions and continued throughout the cooling of the following stadial. Such an interpretation has its parallels in the northern hemisphere but is in slight disagreement with previous glacial and fluvioglacial chronologies accepted in New Zealand.