bluuebunny/crossref_metadata_2025_split huggingface dataset:
Robust output regulation for discrete‐time nonlinear systems
Authors: Lan Weiyao , Huang Jie 
Published: December 2004

AbstractIn this paper, we will establish a framework that can convert the robust output regulation problem for discrete‐time nonlinear systems into a robust stabilization problem for an appropriately augmented system consisting of the given plant and a specific dynamic system called internal model. We then apply this framework to solve the local robust output regulation problem for a general class of discrete‐time nonlinear systems. The results of this paper gives a discrete‐time counterpart of the recent results on the continuous‐time robust output regulation problem. Copyright © 2005 John Wiley & Sons, Ltd.
The analysis of peak expiratory flow data using a three‐level hierarchical model
Authors: Lambert Paul C. , Burton Paul R. , Abrams Keith R. , Brooke Adrian M. 
Published: December 2004

AbstractPeak expiratory flow (PEF) is a measure commonly used in clinical practice and research for respiratory diseases such as asthma. In research, PEF is usually recorded in a diary for a 2‐week period with two or more measurements per day. Interest may lie in whether certain groups of individuals tend to have higher or lower PEF. In addition the variability of PEF may be of interest as, for example, asthmatics tend to have more variable airways. In this paper we develop a three‐level hierarchical model that can simultaneously model the mean level and variability of PEF. The variability is broken down into three components, between‐subject variability, between‐day within‐subject variability, and within‐day within‐subject variability. The latter two components are of specific clinical interest. We fit both classical and Bayesian models. The Bayesian models have the advantage of taking the uncertainty in the variance component estimates into account when estimating the standard errors of the fixed effects. In addition, the Bayesian models provide an intuitive and simple way to investigate the within‐subject variance components. Copyright © 2004 John Wiley & Sons, Ltd.
Seasonal changes in soil arthropod abundance in the dry evergreen forest of north‐east Thailand, with special reference to collembolan communities
Authors: Wiwatwitaya Decha , Takeda Hiroshi 
Published: December 2004

AbstractA soil arthropod community was studied in a dry evergreen forest over a 3‐year period from May 1998 to April 2001. Population abundance, species composition, and community structure were investigated over the 3‐year study period. The soil arthropods consisted of Acari (75.38%), Collembola (16.11%), and others (8.51%), and their abundances showed a clear difference between the rainy and dry seasons. Population abundance of Collembola and Acari were low during drought conditions. The humidity was the most important factor determining distribution, abundance, and survival of soil Collembola in this tropical forest. High predation and low accumulation of organic matter caused low population abundance of Collembola in the tropical habitat. The collembolan community was dominated by a few dominant species over the study period. The pattern of seasonal changes in numbers of Collembola was similar over the 3‐year study period. The species composition of the collembolan community was constant and persistent throughout a 3‐year study period. Thus, the collembolan community showed constancy in its species composition with seasonal variability over the 3‐year study period.
Dynamics of the Ocean-Cryosphere System: Barbados Data
Authors: Matthews R.K. 
Published: December 2004

Renewed development of the Laurentide and Scandinavian ice sheets would have large effects on global climate. By one model, growth of a new ice sheet would be slow and would begin with systematic and easily measurable changes in remote regions of Northeastern Canada. By another model, growth of a new ice sheet would begin rapidly with the development of thin ice cover over a large area. Clearly, immediate global impact would be much greater with the second model than with the first.Because sea level fluctuations are the reciprocal of change in ice volume, interaction between Pleistocene coral reefs and sea level events provides an estimate of the dynamics of the ocean-cryosphere system. The data suggest rapid growth of continental sheets.
Fire in the Boreal Forest
Authors: Rowe J.S. , Scotter G.W. 
Published: December 2004

AbstractThe boreal forest in North America owes much of its floristic and faunistic diversity to periodic fires ignited by lightning and by man since he appeared on the scene. The indirect evidences of buring in vegetation and soils, and recent direct observations of fires, are reviewed. Fire is shown to exert a significant effect on vegetational composition, on soil chemical properties and thermal regime, and on animal populations through the particular mosaic of habitats created. In turn, fire is itselt influenced by the nature of geographic landscape ecosystems according to their surface forms, accumulations of organic materials, and susceptibility to drought. It is concluded that fire should be viewed as a normal ecological process in the boreal forest. A thorough understanding of its long-term role in terrestrial and aquatic ecosystems is needed.
Paleoclimatic Investigation of a Late Pleistocene Caribbean Deep-Sea Core: Comparison of Isotopic and Faunal Methods
Authors: Imbrie John , van Donk Jan , Kipp Nilva G. 
Published: December 2004

AbstractA simplified and more accurate version of the quantitative paleoenvironmental method proposed by Imbrie and Kipp (1971) is described, which is based on untransformed rather than transformed species per cent data. The method yields faunal indices (Ts, Tw, S), useful both as objective measures of paleontological properties and as estimates of Pleistocene sea-surface summer and winter temperatures (Ts, Tw) and salinity (S). Similarly, the oxygen-isotope method yields objective measurements of δ O18, useful stratigraphically and as indications of past changes in isotopic water composition and temperature.Laboratory errors of the two methods have about the same magnitude relative to ranges observed in V12-122. Accuracy of faunal indices as estimates of oceanic conditions is evaluated by study of modern oceanographic data and sea-bed samples. Under favorable conditions, accuracy is apparently limited primarily by the degree of ecological control exercised by the estimated parameter. Accuracy of the isotopic paleotemperature estimates is limited primarily by uncertainty as to the magnitude of the water-correction term in the isotope equation, a value which combines global ice-volume and local evaporation-precipitation effects.Curves of δ O13 and S in V12-122 record all or part of seven major climatic cycles, and display a fundamental periodicity of about 85,000 years. Ts and Tw curves show small but significant differences: two phase shifts in estimated temperature minima, and a long-term increasing trend.Amplitude-frequency histograms of Tw and δ O18 indicate that only two percent of the time during the past 450,000 years have Caribbean temperatures been as warm and isotopic ratios as low as they are today.A comparison of the magnitude of δ O18 change (2.2%.) during the shift from late-glacial to post-glacial times, with that of the faunally estimated change in average temperature (2.2°C), provides a basis for estimating the associated change in isotopic water composition (1.8%.) by back-calculation in the isotope equation. At least 0.4%. of this change in A is attributed to an evaporation-precipitation effect, and the balance (≤1.4%.) to an icevolume effect.Isotopic and faunal methods monitor different responses to global climatic change. Used in conjunction, they provide deeper insights into the past than either could achieve alone.
Oxygen Isotope and Palaeomagnetic Stratigraphy of Equatorial Pacific Core V28-238: Oxygen Isotope Temperatures and Ice Volumes on a 105 Year and 106 Year Scale
Authors: Shackleton Nicholas John , Opdyke Neil D. 
Published: December 2004

AbstractCore Vema 28-238 preserves an excellent oxygen isotope and magnetic stratigraphy and is shown to contain undisturbed sediments deposited continuously through the past 870,000 yr. Detailed correlation with sequences described by Emiliani in the Caribbean and Atlantic Ocean is demonstrated. The boundaries of 22 stages representing alternating times of high and low Northern Hemisphere ice volume are recognized and dated. The record is interpreted in terms of Northern Hemisphere ice accumulation, and is used to estimate the range of temperature variation in the Caribbean.
Late Pleistocene-Holocene Oceanographic Changes in the Northeastern Pacific
Authors: Moore Ted C. 
Published: December 2004

AbstractThe distributions of the radiolarian assemblages in the Northeastern Pacific Ocean were determined and correlated with the average summer temperature of the near surface waters of this region. These assemblages were compared with those in three sediment cores taken beneath the Transition Zone waters. This comparison indicates that the assemblage off Oregon at the last maximum cold interval (24,000 yr B.P.) was like that now found off southern Alaska. The correlation of the radiolarian assemblages with temperature gives an estimate of 11°C for the average summer temperature at that time. This is approximately 4°C cooler than present day conditions in the area. Superimposed on the general warming trend that began 24,000 y.a., there are minor oscillations in the assemblages which correspond to estimates of temperature change of about 2°C in the Pleistocene and about 1°C in the Holocene. In the Holocene, these minor warm intervals appear to be approximately synchronous with advances in mountain glaciers.
Ice Ages and Orbital Variations: Some Simple Theory and Modeling
Authors: Schneider Stephen H. , Thompson Starley L. 
Published: December 2004

Possible physical mechanisms relating orbital-element variations (i.e., the “Milankovitch mechanism” of insolation regime changes) to Quaternary glacial/interglacial transitions are explored quantitatively. These include the seasonal cycle of albedo and the zonal distribution of thermal inertia. These mechanisms can interact with the perturbations to zonal average and seasonal average insolation caused by orbital-element variations to cause a global annual temperature residual, even though such variations can cause only a negligible change in global annual insolation.Numerical model experiments with a zonal energy balance model show that the relative interactions between insolation regime changes and seasonally and latitudinally varying albedo and latitudinally varying thermal inertia are roughly of comparable magnitude. Encouraging agreements between model experiments and data are evident, but these (and others') simulations are still a long way away from providing a satisfying explanation of the physical processes that could fully explain the apparent connections between orbital-element variations and Quaternary glaciations.It seems likely that no single physical process can be identified as predominate, and rather, the hypothesized physical connection between insolation regime changes and glacial/interglacial transitions will have to be built on the interactions of a number of processes on both short and long time scales.
Surge Moraines of the Klutlan Glacier, Yukon Territory, Canada: Origin, Wastage, Vegetation Succession, Lake Development, and Application to the Late-Glacial of Minnesota
Authors: Wright H. E. 
Published: December 2004

AbstractThe Klutlan Glacier in the St. Elias Mountains of the Yukon Territory has surged repeatedly during the last few hundred years, and its drift-covered stagnant ice provides an analog for the downwastage, landform development, vegetational succession, and lake formation on Late Wisconsin moraines of Minnesota. Melting of the buried ice caused collapse of the drift mantle and the formation of lakes, which become filled with sediment that slumps in from receding ice walls. Topographic reversals are common, as the sediment cover of drained lakes inhibits local under-melting, and collapse occurs elsewhere. As the drift mantle thickens the land surface becomes stabilized and pioneer herbs are succeeded by shrubs and then by white spruce. The oldest moraines (600–1200 yr old) have a multiple-generation spruce forest, yet melting of buried ice still locally forms young lakes. Cores of organic sediment from the oldest lakes contain a stratigraphic sequence of pollen, diatoms and cladocerans that record the early stages in lake and landscape succession.
Wastage of the Klutlan Ice-Cored Moraines, Yukon Territory, Canada
Authors: Driscoll Fletcher G. 
Published: December 2004

AbstractA series of ice-cored Neoglacial moraines at the terminus of the Klutlan Glacier covers an area of 90 km2. Studies were made to determine empirically how long ice persisted in the Klutlan moraines and to develop models that can accurately predict wastage rates under current climatic conditions. A meltout curve based on climatological data reflects the sum of three melting processes: surficial melting, melting by lake water, and melting by geothermal heat. About 950 yr are required to melt 180 m of ice with a debris concentration of 1%, or about 1200 yr for a 1.5% debris load. Another meltout curve, based on seismic data, suggests total meltout in about 875 yr. When all geologic factors are considered, the empirical meltout curve is remarkably similar to that derived by considering the major heat-flux parameters. Meltout rates can be predicted if (1) the fundamental climatic parameters can be ascertained, and (2) the sediment concentration in the ice is known.
Modern Pollen Assemblages and Vegetational History of the Moraines of the Klutlan Glacier and Its Surroundings, Yukon Territory, Canada
Authors: Birks H. J. B. 
Published: December 2004

AbstractModern pollen assemblages have been studied from surficial lake muds and moss polsters collected from five vegetated ice-cored moraines of the Klutlan Glacier. The youngest vegetated moraine (K-II) is characterized by high pollen values for Salix and Hedysarum, K-III by high Salix and Shepherdia canadensis and low Hedysarum and Picea, K-IV by high Betula, Salix, and Shepherdia, and K-V and the Harris Creek moraine (HCM) by high Picea. Variations are summarized by canonical variates analysis. A percentage pollen diagram from Gull Lake on the upland east of the glacier records vegetational development since the deposition of the White River volcanic ash 1220 14C yr ago. An initial species-rich treeless vegetation was replaced by birch-alder-willow shrub-tundra, and this by open Picea glauca forest similar to present vegetation around the lake. Sites on HCM show two basic stratigraphies. Triangle Lake reflects vegetational succession from Salix-Shepherdia canadensis scrub similar to that on K-III today, through open Picea woodland of K-IV type, to closed Picea forests of K-V and HCM. Heart Lake and Cotton Pond reflect vegetational development following melting of ice underlying the spruce forests of HCM. These two types are summarized by positioning the fossil spectra on the first two canonical variate axes of the modern surface spectra.
A Reported Early-Man Site Adjacent to Southern Alaska's Continental Shelf: A Geologic Solution to an Archeologic Enigma
Authors: Thorson Robert M. , Plaskett David C. , Dixon E.James 
Published: December 2004

AbstractAn extensive ancient archeologic site containing lithic artifacts and associated with mammoth remains was reported at Chinitna Bay, southern Alaska in 1943. The presence of such a site adjacent to the continental shelf at the base of the rugged Aleutian Range suggested that humans may have inhabited the inner shelf environment during the late Pleistocene at times of lowered sea level. Because of the site's potential significance, an interdisciplinary research team relocated and reinvestigated the area in 1978, but failed to find evidence of prehistoric human habitation. Geologic studies and radiocarbon dating indicate that the strata reported at the site are intertidal in origin, very late Holocene in age, and have undergone significant tectonic movement in the recent past. These observations indicate that the previously published observations of the Chinitna Bay site are probably invalid.
Radiocarbon Dating of the Rate of Movement of Two Solifluction Lobes in the Ruby Range, Yukon Territory
Authors: Alexander Charles S. , Price Larry W. 
Published: December 2004

AbstractThe rates of solifluction of two lobes in the Ruby Range have been determined by 14C dates of samples taken from buried organic layers in the lobes. Twenty-one dates are available from one lobe, and seven from another. When plotted against distance back from control points at the lobe fronts the dates show considerable scatter. In part the scatter is thought to be due to a potential age range of 340 ± 100 yr in the organic layers. Linear and polynomial regressions were calculated for the time/distance relationships shown by the dates. The rates of lobe advance established by these means for the lobe with seven dates are not thought to be reliable. Reasonably good estimates of movement rate were determined for the second lobe by both the linear and polynomial methods. However, the rates established by the two methods are quite similar. Because of this and other uncertainties it is difficult to draw inferences of climatic change from the changes in movement rate shown by the polynomial solution.
Pollen Analysis of the 1973 Ice Core from Devon Island Glacier, Canada
Authors: McAndrews John H. 
Published: December 2004

Meltwater from a 299-m-long ice core was filtered and analyzed for fossil pollen and spores. Pollen concentration was higher in the late Holocene and interglacial intervals (ca. 7 liter−1) than in the early Holocene and Wisconsinan (ca. 1–2 liter−1) ones. The late Holocene and interglacial assemblages were dominated byAlnus(alder), whereas the early Holocene and Wisconsinan ones were dominated byBetula(birch) andArtemisia(sage). During the Holocene and probably the last interglaciation, most of the pollen and spores were blown a minimum of 1000 km from low arctic shrub tundra and adjacent subarcticPicea(spruce) forest; these areas were dominated by the arctic air mass during the summer pollinating season. During the Wisconsinan-early Holocene, glacier ice and arctic air were more widespread and pollen sources were more distant; thus, at this time relatively little pollen was incorporated into the ice.The Devon ice-core data suggest that there should have been pollen in the continental ice sheet of Wisconsin time. When the ice sheet retreated this pollen would be carried by meltwater and redeposited with silt and clay together with contemporary pollen, producing an ecologically anomalous assemblage.
Stratigraphy and Isotope Records of Middle and Late Pleistocene Mollusks from a Continuous Corehole in the Hula Basin, Northern Jordan Valley, Israel
Authors: Moshkovitz Shimon , Magaritz Mordeckai 
Published: December 2004

AbstractMorphological changes in Melanopsis shells and the sudden disappearance of Viviparus were observed in a continuous core, representing about 700,000 yr, taken from the L-12 corehole in the Hula Basin, northern Jordan Valley, Israel. Two major events in δ18O values are recorded. The first, at about 435,000 yr B.P., is accompanied by a shift in δ13C values and indicates a shallowing phase with slightly higher evaporation. This event is concurrent with the abundant occurrence of a monotypic “distorted” Melanopsis, suggesting an “ecophenotypic event” during deposition of the lake's Pleistocene lower Lacustrine beds. The second major isotopic event is evidenced in the lower part of the section as a gradual depletion in 18O toward the bottom of the corehole. Minor shifts of 1–20‰ in the oxygen isotope content along the core may represent changes in the δ18O values of the water from glacial to interglacial periods representing the major climatic cycles of the Pleistocene. Five of these cycles were observed along the core.
South Carolina Interglacial Sites and Stage 5 Sea Levels
Authors: Hollin John T. , Hearty Paul J. 
Published: December 2004

AbstractAmino acid and other studies have been made on the 30-km Pleistocene sections of the Intracoastal Waterway between Myrtle Beach and Little River, South Carolina. Our ratios differentiate the long-established Waccamaw (oldest), Canepatch, and Socastee formations. The ratios from the four laboratories that have worked in this area agree very well, and apparent conflicts with U-series dates may merely reflect an abundance of reworked corals. Our amino acid correlations with U-series coral dates in South Carolina, Bermuda, and the Mediterranean all argue that the classical Canepatch and its Horry Clay date from isotope stage 5e and not, as has been implied, from stage 7, 9, 11, or 13. Excavations and erosion have increased position-fixing problems along the Waterway, and “Canepatch” amino acid ratios and U-series dates (460,000 ± 100,000 yr B.P.) at “ICW5” may be from an older unit. The Canepatch shows the double marine transgression visible in many stage 5e deposits. Pollen shows that the second transgression occurred late in the interglaciation, and stratigraphic studies show that it reached 14 m. It therefore fits very well Antarctic ice-surge models of stage 5 sea level and climate. The Socastee adds to the evidence for one or more sea levels above 0 m late in stage 5.
Pleistocene glaciation of the King Valley, Western Tasmania, Australia
Authors: Fitzsimons Sean J. , Colhoun Eric A. 
Published: December 2004

AbstractAnalysis of the geomorphology, geology, and palynology of deposits in the King Valley permits the identification of four glaciations and two interglaciations and has led to a revision of the Pleistocene stratigraphy of the West Coast Range. The oldest late-Cenozoic deposits in the valley appear to predate glaciation, contain extinct pollen types, and are probably of late-Tertiary age. Overlying deposits of the Linda Glaciation show intense chemical weathering and have a reversed detrital remanent magnetization indicating deposition before 730,000 yr B.P. The highly weathered tills are conformably overlain by organic deposits of the Regency Interglaciation which show a transition from montane scrub rainforest to lowland temperate rainforest. Deposits formed during the later Moore Glaciation record advances of the King Glacier and glaciers from the West Coast Range. A pollen-bearing fluvial deposit records an interstade during this glaciation. On the basis of weathering rinds, amino acid dating, and palaeomagnetism the deposits are estimated to have formed between 730,000 and 390,000 yr B.P. The Moore Glaciation deposits are overlain by sediments of the Henty Glaciation which are believed to predate 130,000 yr B.P. These deposits record multiple advances of the King Glacier and the development of a large lake during an interstade. Deposits of the subsequent Pieman Interglaciation consist of organic fine sands and silts that record a lowland scrub rainforest. Deposits of the last (Margaret) glaciation are restricted to small areas in the northern part of the valley. Although the most recent ice advance culminated after 19,000 yr B.P., evidence of older deposits of the Margaret Glaciation suggests that an early last-glaciation ice advance may have occurred. When combined with earlier studies, the recent work in the King Valley has provided one of the more complete records of Pleistocene glaciation in the Southern Hemisphere. Comparison of the deposits with the record of glaciation in southern South America and Westland, New Zealand, suggests some similarities exist between pre-last-glaciation events and indicates that glacial events in Southern Hemisphere middle latitude areas were synchronous during the last glaciation.