bluuebunny/crossref_metadata_2025 huggingface dataset:
Dendrochronology raises questions about the nature of the AD 536 dust-veil event
Authors: Baillie M.G.L.
Published: November 2007

New evidence is presented which shows the response of a wide grid of tree-ring chronologies to the dust-veil of AD 536, the effects of which were historically recorded in the Mediterranean and eastern Asia. The tree-ring evidence, particularly that from European oaks (Quercus), shows a two-stage response which raises questions about whether only a single massive eruption was involved. The observations from precisely dated tree-ring series set the agenda for the interpretation of forthcoming ice-core evidence across the AD 530s and 540s.
Chronology and palaeoenvironmental interpretation of Holocene aeolian sands at the inland edge of the Sinai-Negev erg
Authors: Tsoar Haim , Goodfriend Glenn A.
Published: November 2007

Three Holocene dune units overlying Pleistocene loess were studied in a sand quarry near the limit of inland penetration of the Sinai-Negev erg from the Mediterranean coast. Radiocarbon dating of hearths in these units indicates ages of c. 4100 cal. BC, cal. AD 600-900, and cal. AD 1700-1950 for the units. Each of these dates corresponds to a period of relatively dense occupation of the region, i.e., the Chalcolithic period, the Late Byzantine-Early Islamic period, and the recent period of Bedouin settlement. Activation of the sands at these times is probably due to the grazing and trampling activity of livestock. The Chalcolithic sands have a high content of fines and appear to have accumulated under relatively moist conditions. Amino acid epimerization analysis of land-snail shells from the dune sands indicates that none of the shells is contemporary with the sands. The shells were incorporated during earlier periods of dune movement and subsequently redeposited along with the sands.
Neoglaciation and an early 'Little Ice Age' in western Norway: lichenometric evidence from the Sandane area
Authors: Evans David J.A. , Butcher Craig , Kirthisingha Arjan V.
Published: November 2007

Moraine sequences, protalus ramparts, rock glaciers and various slope deposits in seven separate glacier basins provide lichenometric ages for glacier retreat in an upland area of Sogn-og- Fjordane, southern Norway. Geomorphological mapping, relative dating based on section Rhizocarpon size-frequency distributions, observations on vegetation cover, and numeric dating based on a regional lichen dating curve for section Rhizocarpon, place moraines into three groups: Stage 1 moraines of likely Preboreal or Younger Dryas age; Stage 2 moraines of pre- or early 'Little Ice Age' but post-Preboreal age (thirteenth-fourteenth centuries); and Stage 3 moraines of fifteenth-century age and younger. The occurrence of thirteenth-sixteenth century (pre- or early 'Little Ice Age') moraines at low altitudes in the Sandane area is thought to relate to greater availability of moisture and to the capture of wind- drifted snow. These moraines are some of the oldest 'Little Ice Age' moraines dated by lichenometry in southern Norway. In some cirques, glaciers retreated from their fifteenth-century positions allowing protalus rampart development, scree accumulation and debris-flow activity to continue until the present.
AMS-radiocarbon dating of organic-poor lake sediment, an example from Linnévatnet, Spitsbergen, Svalbard
Authors: Snyder J.A. , Miller G.H. , Werner A. , Jull A.J.T. , Stafford T.W.
Published: November 2007

AMS-radiocarbon dating of specific organic fractions is used to evaluate sources of errors in dating of organic-poor lake sediment from Linnévatnet, a proglacial arctic lake. Dates on un differentiated (bulk) organic matter are much too old because of contamination from detrital coal. Attempts to remove coal from other organic matter were only partially successful, a consequence of the wide grain-size distribution of the coal. Even if coal contamination is fully removed, the bulk of the remaining organic matter is of aquatic origin and is unsuitable for 14C dating because the lake waters are depleted in 14 C due to dissolution of carbonate minerals. Terrestrial plant macrofossils provide the only reliable material to date the lake sediment; however, this material is present in sufficient quantity for AMS-radiocarbon dating only in cores proximal to the main inlet streams. Paired dates on terrestrial plants and aquatic insects from the same core level and paired dates on modern aquatic and terrestrial vegetation indicate differences in carbon reservoir activities of 1000 and 3000 years. In hard-water lakes, coring is recommended in inlet-proximal areas where inwashed terrestrial vegetation is most concen trated. Chronologies established in proximal cores can be transferred to central-basin cores using litho or chemo-stratigraphic indices.
Freshwater calving and anomalous glacier oscillations: recent behaviour of Moreno and Ameghino Glaciers, Patagonia
Authors: Warren Charles R.
Published: November 2007

Moreno Glacier has been consistently advancing during a period of general glacier retreat this century, and has repeatedly dammed an arm of Lago Argentino. The most recent episode of ice-dam failure and catastrophic lake drainage occurred in 1988. However, the recent periodicity of this behaviour has now been interrupted, and the current characteristics of the terminus suggest a future retreat. Because of the nature of calving dynamics, such a retreat would be rapid and irreversible in the short term. Neighbouring Ameghino Glacier, after almost a century of near-stagnation, commenced calving in a newly formed proglacial lake in about 1967 and then retreated 3 km at a mean rate of 334myr-1 for the next nine years in a fashion analagous to that predicted for Moreno Glacier. The behaviour of these glaciers cannot be related directly to regional climate trends; terminus response is more closely controlled by the interplay between calving dynamics and topography. Calving is therefore a potentially significant factor in glacio-climatic reconstruction, even in 'terrestrial' settings.
Holocene evolution of a lowland Scottish landscape: Kirkpatrick Fleming. Part II, regional vegetation and land-use change
Authors: Tipping Richard
Published: November 2007

In this second of three papers on the environmental changes that have affected a lowland Scottish landscape during the Holocene, pollen and microscopic charcoal counts, supported by radiocarbon dates, form the basis for interpreting vegetation changes that characterized 'dryland' soils around the raised bog of Burnfoothill Moss, on the Solway Firth. The migration of Corylus, and later of Quercus and Ulmus, appear to have been later than at nearby sites, but radiocarbon dates for these events are thought to be in error through lowered rates of peat accumulation. Establishment of Alnus coincided with anthropogenic woodland disturbance at around 7800 cal. BP, and supports arguments that imply disturbance prior to Alnus colonization. Two Ulmus declines are recorded. The first at c. 4830 cal. BP appears to have been exceedingly abrupt, and specific to elm, without evidence for anthropogenic interference. The second occurred some 250 years later, and is associated with agricultural activity. A phase of partial abandonment is recorded in the late Neolithic. The first major clearance is dated to the very latest prehistoric or to the earliest Romano-British period, and a subsequent resurgence of agricultural activity at c. 1350 cal. BP led to a fully utilized landscape by 1000 cal. BP.
Holocene environmental change in the Zacapu Basin, Mexico: a diatom-based record
Authors: Metcalfe Sarah E.
Published: November 2007

The Zacapu basin, Michoacán, Mexico, is one of a series of internally drained lake basins in the central highlands of Mexico. The basin has a history of occupation spanning at least 2000 years and before the arrival of the Spanish was a major centre for the Purépecha culture. Results are presented of diatom studies from four lacustrine sediment sequences which have Holocene radiocarbon dates: CEMCA Point 1, CEMCA Point 4, the Zacapu core and Zacapu Section 1. These lie along a transect from the former marsh floor up to the western slopes of the basin. Zacapu Section 1 indicates a deep lake in the basin at some time, but the date on this section is thought to be unreliable and the sediments are probably Pleistocene in age. The other sequences record few major changes in water level in the basin, although dry episodes occurred about 4500 BP and, more severely, about 1000 BP. A period of marked catchment disturbance about 7000 to 6000 BP is believed to be the result of volcanic activity on the western flank of the basin. Major anthropogenic disturbance is recorded over the Postclassic and Hispanic periods (since about AD 900).
The Hekla 3 volcanic eruption recorded in a Scottish speleothem?
Authors: Baker Andy , Smart Peter L. , Barnes W.L. , Edwards R. Lawrence , Farrant Andy
Published: November 2007

Recent research has demonstrated the presence of annual luminescent growth banding in a stalagmite from Sutherland, N.W. Scotland (Baker, Smart, Edwards and Richards, 1993). The banding record of this sample contains a short duration increase in annual band width, indicating a doubling of growth rate for a period of four years. Predicted growth rates derived from calcite precipitation kinetics are compared with observed growth-rate variability to demonstrate that such a doubling of growth rate would not be expected within the probable range of normal climate variation. The growth rate peak is dated to 1135 ± 130 BC by thermal ionization mass spectrometric 238U-234 U-230Th dating, not inconsistent with the timing of the Hekla 3 volcanic eruption. This event may explain the observed variation in growth rate, and provide a new source of evidence for interpretation of the effects of large explosive eruptions.
Late Holocene Neoglacial episodes in southern South America and southern Africa: a comparison
Authors: Jerardino A.
Published: November 2007

Palaeoenvironmental evidence from existing late-Holocene palaeoenvironmental sequences suggests that important atmospheric and oceanographic changes took place during the last 5000 years in southern South America and southern Africa. Several oscillations were contemporary with three well- known Neoglacial episodes that occurred between about 4500 and 4000 BP, between 3000 and 2000 BP and during the last 1000 years. The scale of change involved during these climatic episodes consisted of temperature departures of 1-2 °C, and sea-level oscillations of ± 1-2 m. In at least two winter rainfall regions, an increase in precipitation was concomitant with most of these Neoglacial episodes. Minor northward latitudinal shifts of frontal systems, and relatively strong atmospheric circulation, were probably involved in the detected climatological trends. Minor, but significant, expansions of polar waters into the Humboldt and Benguela Currents are probably additional, and important, role players during these Neoglacial phases. Further establishment of more palaeoenvironmental sequences is needed in order to generate and test explanatory models.
Charcoal evidence for Indian-set fires: a comment on Clark and Royall
Authors: Campbell I.D. , McAndrews J.H.
Published: November 2007

Clark and Royall (1995) present a charcoal influx curve for Crawford Lake in southern Ontario and conclude that the Indians were responsible for a succession from beech to oak and pine throughout southern Ontario. We present an alternative hypothesis, that the 'Little Ice Age' caused the forest succession and that domestic fires and burning of stubble in agricultural fields were responsible for the charcoal record.
Archaeological and environmental evidence for the Roman impact on vegetation near Carlisle, Cumbria
Authors: McCarthy Michael R.
Published: November 2007

Extensive archaeological excavations on well-preserved Roman deposits at Carlisle, Cumbria, have revealed much 'environmental' evidence. These data not only shed light on ancient building technology and the uses to which individual buildings were put, but they are of great importance in attempting to reconstruct ancient landscapes. Timber, wood, cereals, weeds of cultivation, invertebrate remains and animal bones from dendrochronologically-dated deposits are used to focus attention on specific elements of land use in a way which the technique of palynology, combined with radiocarbon dating, cannot achieve. It is concluded that the Romans had a considerable impact on the landscape, but the balances between arable, pasture and woodland cannot yet be determined.
Lipid stratigraphy of a Flandrian peat bed (Northumberland, UK): comparison with the pollen record
Authors: Farrimond Paul , Flanagan Rachel L.
Published: November 2007

A Flandrian peat bed near Low Hauxley (Northumberland, UK) was studied both optically and geochemically to compare the pollen and lipid records of changing plant input during its accumulation. A progressive change in the predominant plant inputs from woodland trees to a more diverse assemblage with herbs, shrubs and Sphagnum is recorded in the pollen data, and associated lipid records. However, the pollen and lipid records do not correlate in detail; samples with near-identical lipid distributions can have markedly different pollen assemblages and vice versa. This apparent inconsistency between data sets is interpreted to be the result of different modes of incorporation of the signals. While the lipids will be largely derived from plant debris in situ, the pollen may have been transported over considerable distances, and will record an average signal of flora over a wider area. The records of local plant input (lipid data) and regional vegetation cover (pollen data) are complementary in the reconstruction of past environmental conditions.
Environmental change in eastern Greenland during the last 1300 years: evidence from foraminifera and lithofacies in Nansen Fjord, 68°N
Authors: Jennings Anne E. , Weiner Nancy J.
Published: November 2007

Lithofacies and benthic foraminiferal analyses of two sediment cores (BS1191-K13B and K14) from Nansen Fjord, eastern Greenland, show evidence of changing oceanographic and sea-ice conditions from AD 730 to the present. Radiocarbon dates on foraminifera provide century-scale resolution of events, but the frequency of events between dated levels can be estimated with a resolution of approximately 4 to 9 years per centimetre of core. Unstratified glacial-marine diamicton with a calcareous foraminiferal fauna gives way to interstratified diamicton and mud with a predominantly agglutinated foraminifera. The diamictons represent periods of season ally open water with strong continuous iceberg rafting. Mud layers were deposited during intervals of prolonged sea-ice cover. The evidence suggests that the climate in the region of Nansen Fjord was warmer and more stable than today during a 'Medieval Warm Period' between c. AD 730 to 1100. Variable climatic conditions with frequent intervals of severe cold characterize a 'Little Ice Age' type interval from c. AD 1630 to 1900. An earlier cold interval culminated c. AD 1370. The record is similar to the 1000-yr-long Icelandic sea-ice record and, to a lesser extent, to the central Greenland Crete ice-core record.
Holocene climatic and human influences on lakes of the Yucatan Peninsula, Mexico: an interdisciplinary, palaeolimnological approach
Authors: Whitmore Thomas J. , Brenner Mark , Curtis Jason H. , Dahlin Bruce H. , Leyden Barbara W.
Published: November 2007

We used palaeolimnological techniques to examine effects of Holocene climate change and human influence on lakes of the Yucatan Peninsula, Mexico. The three study lakes are located along a west-east transect that represents a gradient of increasing modern precipitation and density of former Maya settlement. At Lake Coba, an 880-cm sediment core yields a complete record of lacustrine sedimentation that began when the lake first filled ∼8000 BP as groundwater level rose in response to rising sea level and increased precipi tation. Diatom, ostracod, and δ 18O evidence indicate that Lake Coba was initially shallow and saline. Coba, presently in the region of greatest rainfall, showed more episodic water-level changes than Lake San Jose Chulchaca or Lake Sayaucil. High lake level and fresh water were evident at 440 cm (∼2600 BP), followed by a decline in water levels and an increase in total ionic salinity to the present time. In a 613-cm core from Sayaucil, in the intermediate precipitation zone, total salinity was high between 600 and 400 cm (∼3050 and 2000 BP), followed by consistently higher water levels. Salinity was high in the lower portion of a 110-cm San Jose Chulchaca core (beginning ∼1860 BP), followed by a gradual and consistent freshening of water to the present time.

Trophic state changes and human influence on lakes were evaluated using diatom, δ13C, total P, sedimentary organic matter, and preliminary pollen data. Maximal human disturbance at Lake Coba, a densely settled Maya urban site, occurred during a deep-water event at 440 cm, followed by a decline in human influence and trophic state to the present time. Trophic state and linear sedimentation rates in Sayaucil increased significantly above 400 cm (after ∼2000 BP), probably associated with initial Maya settlement near Xtojil and subsequent small- scale farming. Limnological disturbance may have preceded the period of maximal human occupation because initial land clearance and consequent soil erosion probably affected water quality substantially. San Jose Chul chaca lacks archaeological evidence of human occupation in the drainage, and shows gradual changes in trophic state not caused by human disturbance. With the exception of a 14C date on wood from the base of the Coba core, 14C dates and chronologies may be artificially old as a consequence of hard-water-lake error. Trophic state changes in the study lakes were generally consistent with known patterns of human settlement and popu lation change. Late-Holocene water-level fluctuations were most pronounced in Lake Coba in eastern Yucatan, where modern rainfall is currently greatest, but lake level is generally lower than during much of the past. Lake level was relatively constant in Sayaucil in the central peninsula, whereas lake level in San Jose Chulchaca in the arid western portion of the peninsula increased gradually over time.
PreColumbian agriculture and forest disturbance in Costa Rica: palaeoecological evidence from two lowland rainforest lakes
Authors: Northrop Lisa A. , Horn Sally P.
Published: November 2007

Lake-sediment cores from Laguna Bonilla and Laguna Bonillita provide some of the first evidence of prehistoric human impacts on lowland rainforests in Costa Rica. The longer Bonillita sediment record docu ments permanent settlement of the lake shores by 2560 BP, about 600 years earlier than previously inferred from the archaeological record. Zea pollen and charcoal fragments in cores from both lakes indicate a subsist ence strategy that included maize cultivation and some use of fire. A dramatic decline in Myrsine pollen percentages about 1300 BP suggests local eradication of this woody plant, likely as a result of land clearance and/or the use of Myrsine for construction.
Late-Holocene glacier variations in the Cordillera Darwin, Tierra del Fuego, Chile
Authors: Kuylenstierna J.L. , Rosqvist G.C. , Holmlund P.
Published: November 2007

Radiocarbon dates obtained on peat and macrofossils, sampled both proximally and distally, of a terminal moraine in the Bahia Pia area, Cordillera Darwin, Tierra del Fuego, Chile, indicate that the glacier system reached maxima sometime before 3060 BP, prior to 940 BP and between 940 BP and 675 BP. The glacier retreated 4 km to a pinning-point position where it dammed a lake before 2605 ± 80 BP, between 1950 ± 75 and 1790 ± 75 BP and some time shortly after 1790 ± 75 BP. By 250 BP the glacier system had receded more than 15 km towards the fjord head and probably reached close to its present position. Thus we obtained no evidence from Bahia Pia of any glacial advance occurring during the global 'Little Ice Age' maximum (seventeenth to nineteenth centuries).
Lake sediment studies of Holocene glacial activity in the Kårsa valley, northern Sweden: contrasts in interpretation
Authors: Snowball I. , Sandgren P.
Published: November 2007

A multidisciplinary study of lake sediments deposited in lake basins in the Kårsa valley, northern Sweden, suggests the complete disappearance of the Kårsa glacier during the early and mid-Holocene. Glacier reformation, indicated by the deposition of sediment with a fine particle size distribution and low organic content in the three lakes, took place at c. 3000 14 C years BP. This interpretation contrasts with a study based on the weight loss-on-ignition of the same sediments, which suggests several glacier advances throughout the entire Holocene. The contrasting interpretation is due to different methodological approaches. Single-core (site) studies should be avoided in the future and only features that are consistently reproducible and can be dated in spatially distributed cores should be interpreted in terms of variations in glacial activity, environmental conditions and ultimately, climate.
Reassessment of supposed early 'Little Ice Age' and older Neoglacial moraines in the Sandane area of western Norway: a reply to Matthews, Nesje and Dahl
Authors: Evans David J.A.
Published: November 2007

Further evidence for an early 'Little Ice Age' in the Sandane area, southern Norway, is presented in support of the lichen data of Evans et al. (1994) and in response to the reassessment of Matthews et al. (1996). The geomorphological evidence for three phases of moraine deposition is clarified and relative age dating based upon Schmidt hammer R-values and soil development is presented. These data, in combination with the lichenometry reported earlier, indicate that the moraines of the Jardalen/Fagerdalen cirque in particular are not all of the same age (pre 'Little Ice Age' as suggested by Matthews et al. (1996) but instead date either to post-Preboreal/Younger Dryas times (Stage 1 moraines) or to the 'Little Ice Age' (Stage 2 and 3 moraines). The gradual increase in lichen diameters, R-values and soil depths from the youngest 'Little Ice Age' (Stage 3) moraine to the outermost and oldest Stage 2 moraine lends further support to the suggestion that the 'Little Ice Age' in western Nor way may have begun much earlier than previously documented in the literature. Problems in using the Schmidt hammer for relative age dating in mountainous terrain, where the moraines being dated are often con structed from old glacial deposits and fresh rock fall debris, are also dis cussed.
Mid- and late-Holocene limnogeology of Laguna del Negro Francisco, northern Chile, and its palaeoclimatic implications
Authors: Grosjean Martin , Valero-Garcés Blas L. , Geyh Mebus A. , Messerli Bruno , Schotterer Ulrich , Schreier Hans , Kelts Kerry
Published: November 2007

Lacustrine sediments from the high elevation, endorheic, saline lake Negro Francisco (27°28'S/69°14'W, 4125 m) provide a detailed mid- and late-Holocene environmental history of the Southern Chilean Altiplano. Mineralogy, chemical composition and sedimentary facies analyses of the deposits confirm the regional significance of mid-Holocene aridity between 6000 and 3800 BP. Precipitation rates were signifi cantly lower than the c. 250 mm yr-1 of today. Fully arid conditions were interrupted by short-term moist spells with an average return period of about 200 years. Effective moisture increased after 3800 BP and peaked between 3000 and 2600 BP and between 2200 and 1800 BP in two phases with conditions more humid than today. Comparison with regional palaeodata suggest that these two late-Holocene humid spells were most likely related to Pacific moisture sources. Salinity levels increased again in Laguna del Negro Francisco after 1800 BP. The onset of modern climatic conditions was a stepwise, nonlinear process. However, the functioning of modern climate in this remote part of the world is not understood well enough to explain fully possible mech anisms of climatic changes in the past.
Early-Holocene vegetation and the human impact in central Provence (Var, France): charcoal analysis of the Baume de Fontbrégoua
Authors: Thiebault Stéphanie
Published: November 2007

In order to reconstruct the history of the arboreal vegetation in central Provence (southeast France), charcoal analysis was undertaken on the charred remains excavated in the prehistoric settlement of Fontbrégoua. The results allow us to understand the evolution of vegetation during the first four millennia of the Holocene. After an open vegetation typical of the beginning of the Holocene, there follows a deciduous oak vegetation with Pinus halepensis prevalent at an early stage. The emergence and the development of vegetation in which Pinus halepensis and Quercus cf. pubescens dominate one after the other relate to human occupation and pastoral activities during the middle Neolithic.
Tree-ring based reconstruction of summer temperatures at the Columbia Icefield, Alberta, Canada, AD 1073-1983
Authors: Luckman B.H. , Briffa K.R. , Jones P.D. , Schweingruber F.H.
Published: November 2007

April-August temperatures are reconstructed from maximum latewood density and ring-width data for a tree-line site in the Canadian Rockies of Alberta close to Athabasca Glacier. The chronology primarily utilizes Picea engelmannii with some Abies lasiocarpa snags. This reconstruction (AD 1073-1983) is the longest densitometrically based summer temperature record from boreal North America. Mean temperatures from 1101- 1900 were 0.71°C below the 1961-1990 reference period and 0.33°C below the 1891-1990 mean of the instru mental record. The coldest interval was the first half of the nineteenth century and the major cold intervals, c. 1200-1350, 1690s and the nineteenth century, coincide with local and regional periods of glacier expansion. Warmer periods, c. 1350-1440 and in the present century, are also periods of higher tree-line or tree-line advance at the site. The 1961-1990 reference period is clearly warmer than any equivalent-length period over the last 800 years. This record of summer warmth reinforces evidence of significant warming at several high- altitude and high-latitude sites around the Northern Hemisphere in the late twentieth century. The reconstruction also indicates that glacier advances of the 'Little Ice Age' in the Rockies occurred during a period of fluctuating climatic conditions rather than a long period of sustained cold of several centuries duration.
Prehistoric fires and land-cover change in western Kenya: evidences from pollen, charcoal, grass cuticles and grass phytoliths
Authors: Mworia-Maitima Joseph
Published: November 2007

High rates of sediment accumulation in Lake Simbi, western Kenya, has enabled fine-resolution fossil assemblages to reveal short-term changes in vegetation cover between 4320 ± 250 yr BP and 2880 ± 90 yr BP. Pollen analysis of a 4.2 sediment core covering this period reveals a vegetation change around 3300 yr BP. Analysis of charcoal shows that wildfires were prominent prior to the pollen-inferred vegetation change. Remains of grass cuticles and grass phytoliths show an expansion of grasslands and an increase in the diversity of grass types following the period of extensive fires. Also following the period of wildfires and the vegetation change, there were shifts within the grass flora to more Chloridoid grass types and less Panicoid grass types. This paper addresses one of the major problems of environmental reconstruction in lowland savannah: namely differentiating palaeoecological changes within the Gramineae.
Martingale methods for the analysis of epidemic data
Authors: Becker NG
Published: November 2007

After explaining why martingale methods play an important role in statistical inference for parameters of epidemic models, we give a tutorial introduction to these methods in the more familiar context of data on independent and identically distributed survival times. In this simpler setting we introduce requisite results from martingale theory and demonstrate that martingale methods simply lead to well known estimates and their standard errors. We then turn to the context of epidemics, and illustrate how martingale methods can be used to derive a method of inference for the infection potential in a simple model with removal of infectives. The resulting method involves only simple computations and we demonstrate that the method applies under much more general assumptions. There follows a critical review of several applications of martingale methods for the analysis of infectious disease data. It emerges that the approach provides simple methods of inference in some situations where standard methods of inference are not available, or are too cumbersome. The range of applications seems limited, but new applications continue to be found. Little has been done to confirm high efficiency of martingale methods in epidemic applications.
Effects of frailty in survival analysis
Authors: Aalen OO
Published: November 2007

Unobserved individual heterogeneity, also called frailty, is a major concern in the application of survival analysis. Hazard rates do not give direct information on the change over time in the individual risk, but are strongly influenced by selection effects operating in the population. The individuals surviving up to a certain time will on average be less frail than the original population. Models are reviewed that account for this phenomenon, and some medical examples are discussed. It is emphasized that the frailty phenom enon may be modelled in many different ways, and a stochastic process approach is discussed as an alternative to the common proportional frailty model.
The AB/BA crossover: past, present and future?
Authors: Senn Stephen
Published: November 2007

The AB/BA design is reviewed from a historical perspective. Particular attention is paid to the problem of carry-over and various attempts to deal with it. The two-stage procedure, an approach which was popular for many years, is shown to be unsafe. The analysis of AB/BA designs with baseline data is also considered. It is shown that such baselines do not provide a cure for the problem of carry-over; and it is concluded that any rational analysis of such trials will always be dependent on assumptions regarding carry-over, and that it is necessary to pay particular attention to washout periods. Under such circumstances analysis of covariance may be useful. In conclusion, some speculative comments about future lines of research are offered.
An introduction to multivariate adaptive regression splines
Authors: Friedman Jerome H , Roosen Charles B
Published: November 2007

Multivariate Adaptive Regression Splines (MARS) is a method for flexible modelling of high dimensional data. The model takes the form of an expansion in product spline basis functions, where the number of basis functions as well as the parameters associated with each one (product degree and knot locations) are automatically determined by the data. This procedure is motivated by recursive partitioning (e.g. CART) and shares its ability to capture high order interactions. However, it has more power and flexibility to model relationships that are nearly additive or involve interactions in at most a few variables, and produces continuous models with continuous derivatives. In addition, the model can be represented in a form that separately identifies the additive contributions and those associated with different multivariable interactions.

This paper summarizes the basic MARS algorithm, as well as extensions for binary response, categorical predictors, nested variables and missing values. It presents tips on interpreting the output of the standard FORTRAN implementation of MARS, and provides an example of MARS applied to a set of clinical data.
The use of sampling weights for survey data analysis
Authors: Pfeffermann Danny
Published: November 2007

The use of the sampling weights when fitting models to complex survey data is considered. It is shown that when the sample is selected with unequal selection probabilities that are related to the values of the response variables even after conditioning on all the available design information, ignoring the sample selection scheme in the inference process, can yield misleading results. Probability weighting of the sample observations yields consistent estimators of the model parameters and protects against model misspecification, although in a limited sense. Other methods of incorporating the sampling weights in the inference process are discussed and compared to the use of probability weighting.
Mucoepidermoid Carcinoma of Major and Minor Salivary Glands
Authors: Fonseca Isabel , Clode Ana Luisa , Soares Jorge
Published: November 2007

Forty-three consecutive cases of mucoepidermoid carcinoma of the major and minor salivary glands were studied to evaluate the influence of the following parameters on prognosis: age, sex, location, local extension, mitotic counts, vascular invasion, grade of differentiation, and nuclear DNA ploidy assessed by image cytometry. The age of the patients ranged between 7 and 84 years. Twenty-eight patients were male and 15 female. Thirty-five tumors were in the major salivary glands and 8 in the minor glands of the oral cavity. According to Healey's criteria, 14 tumors were classified as grade 1, 17 as grade 2, and 12 as grade 3 and, according to the 1990 World Health Organization proposal, 17 tumors were classified as low-grade and 26 as high-grade neoplasms. Image cytophotometric DNA analysis revealed 15 euploid and 6 aneuploid tumors. The range of the follow-up study was 3-156 months (mean, 40.7 months). The 5- year actuarial survival for each of the above-cited parameters was: 100% and 59.1 % for patients aged less than 20 and over 55 years, respectively; 49.6% for male and 85.7% for female patients; 61.3% for major gland and 73.3% for minor gland tumors; 100% and 57.5% for intraglandular and extraglandular major salivary gland neo plasms, respectively; 46.2% for cases with high mitotic rate and 83.1% for those with low mitotic rate; 38.7% and 81.6% for tumors respectively with and without vascular invasion; 100% for grade 1 and 64.7% for grade 2; none of the patients with grade 3 neoplasms were alive at 5 years. Survival was of 100% for low-grade and 40.7% for high-grade tumors. Survival was 92.8% for euploid tumors and 61.3% for the aneuploid ones. In conclusion, survival of patients with mucoepidermoid carcinoma is significantly related to the histological grade of differentiation, the mitotic count, the presence of vascular invasion and the DNA ploidy of the tumor cells. Int J Surg Pathol 1(1):3-12, 1993
Uterine Glandular Carcinoma
Authors: Costa Michael J. , Kenny Mary , Judd Randy
Published: November 2007

This study correlated the histologic and immunohistochemical features of cervical and endometrial glandular carcinomas (adenosquamous carcinoma [ADENSQ] and ade nocarcinoma [AC] ) with clinical outcome. A series of 87 uterine glandular carcinomas (53 cervical, 33 endometrial, and 1 arising in both cervix and endometrium) were histologically classified into mullerian subtypes: 28 ADENSQ, 19 serous AC, 19 mu cinous AC, 15 endometrioid AC, and 6 clear cell AC. Utilizing both nuclear and archi tectural features, 66 glandular carcinomas were high histologic grade (3) and 21 were low histologic grade (1 or 2). Immunohistochemical studies performed on 83 of the cases showed: 33 + for monoclonal carcinoembryonic antigen (CEA-M); 38 + for polyclonal CEA (CEA-P); 26 + for placental alkaline phosphatase; 18 + for CA 125; 29 + for CA 19-9; 24 + for vimentin; 60 + for cytokeratin CAM 5.2; and 81 + for cytokeratin AE 1 : 3. The following significant correlations were identified. ADENSQ histology was associated with CEA-M staining (P < .025), and mucinous histology was associated with CA 19-9 staining (P < .025). Cervical primary site was associated with ADENSQ histology (P < .001) and staining with CEA-M (P < .025) and CEA-P (P < .05). Endometrial primary site was associated with endometrioid histology (P < .001). Forty-five patients had recurrent disease, 30 patients were disease-free for more than 1 year, and 12 patients had insufficient follow-up evaluation. Recurrent disease was associated with stage III or IV tumors (P < .001), grade 3 histology (P < .001), serous differentiation (P < .001), invasion to at least the middle third of the myometrium (P < .001) and large size of residual tumor at hysterectomy (mean 3.9 cm versus 1.3 cm, P < .005). Disease-free survival was associated with endometrioid differentiation (P < .05), strong CEA-M staining (P < .001), CEA-P staining (P < .025), and CA 19-9 staining (P < .05). Considering only stage 1 and 2 patients, grade 3 histology ( P < .025), deep myometrial invasion (P < .01), and size (P < .05) were still associated with recurrence and strong CEA-M staining (P < .025) was still associ ated with disease-free survival. However, strong CEA-M staining, deep myometrial invasion, and size of tumor after hysterectomy were all associated with histologic grade. Considering just histologic grade 3 carcinomas in stage 1 and 2 patients, absence of strong CEA-M staining, deep myometrial invasion, and size of tumor was no longer associated with recurrent disease. Histologic grade was the only independent predictor of prognosis in stage I and II patients. Int J Surg Pathol 1 (1): 13-24, 1993
Immunohistochemical Localization of Placental Hormones as Markers for Differentiating Uterine Abortion vs Ectopic Pregnancy
Authors: Strom Janelle K. , Bewtra Chhanda , Monif Gilles R. G.
Published: November 2007

The ability of immunohistochemical staining for human chorionic gonadotropin (hCG) and human placental lactogen (hPL) in tissue obtained by endometrial curetting to distinguish first trimester spontaneous abortions from ectopic pregnancy (EP) was evaluated. Material from 25 patients with uterine bleeding during the first trimester and whose specimens did not contain chorionic villi (CV) on routine histology was stained, and positive results for one or both placental hormones were correlated with subsequent clinical confirmation. Results showed immunohistochemical presence of trophoblasts containing hCG and/or hPL in eight (75%) of the intrauterine pregnancy cases (IUP) with no CV identifiable in routine histological analysis. Human chorionic gonadotropin and hPL were positive in all (100%) cases of IUP with CV (positive control) and negative (0%) in all EP (negative control) cases (P = 0.044). Increased acute inflammation (66% vs 30%, P = .163), vascular wall thickening and occlusion (83% vs 53.8%, P = .25), and decreased Arias-Stella cell changes (50% vs 61%, P = .859) in IUP cases were noted, although none were significant. While the specificities of hCG/hPL positivity and CV are 100% in diagnosing IUP, the sensitivity of CV alone was 45.4% and hCG/hPL positivity was 81.7%. Therefore, in suspected IUP cases, where no CV are seen, hCG and hPL immunostaining may aid in differentiation from EP. Int J Surg Pathol 1(1): 51-56, 1993
Ductal Adenocarcinoma Arising in Duodeno-pyloric Heterotopic Pancreas
Authors: Brotman Steven J. , Pan Wayne , Pozner Jason , Weiss Marshall , Bleiweiss Ira J.
Published: November 2007

The occurrence of heterotopic pancreatic tissue in the abdomen has been well described and is of more than occasional frequency. It has further been noted that this tissue may be subject to most of the pathologic changes ascribed to the pancreas itself; however, malignant transformation in pancreatic heterotopia has only rarely been described. We encountered such a case occurring in a duodeno-pyloric focus in an 82-year-old woman; the lesion was rapidly fatal. Int J Surg Pathol 2(1):37-42, 1994
Immunohistochemical and Ultrastructural Studies of Oligodendrogliomas Revealed Features of Neuronal Differentiation
Authors: Ng Ho-Keung , Ko Hardy C. W. , Tse Christopher C. H.
Published: November 2007

In an attempt to characterize differentiation in oligodendrogliomas, 39 cases were examined immunohistochemically with 5 neuronal markers, synaptophysin, neuron- specific enolase, neurofilament proteins, protein gene product (PGP) 9.5, and micro tubule-associated protein 2 (MAP2), in addition to glial fibrillary acidic protein (GFAP). Positive immunolabeling was obtained for neuron-specific enolose in 29 cases (74%), synaptophysin in 21 cases (54%), PGP 9.5 in 33 cases (85%), and MAP2 in 23 cases (59%). All cases were negative for neurofilament, and 90% stained for GFAP. Eight cases were further studied ultrastructurally, and in five cases features of neuronal differentiation were identified in some of the typical neoplastic oligodendro cytes—small neuritic cellular processes with microtubules and focal synapse-like junc tions, as well as sparse neurosecretory granules. It was concluded that, both immuno histochemically and ultrastructurally, oligodendrogliomas may exhibit features of neuronal differentiation. These previously unreported features of oligodendrogliomas call into question conventional immunohistochemical and electron microscopic crite ria used in distinguishing oligodendrogliomas from tumors showing similar histologic appearance, especially central neurocytomas and dysembryoplastic neuroepithelial tu mors. Int J Surg Pathol 2(1):47-56 1994
Prognostic Value of Proliferating Cell Nuclear Antigen in Phyllodes Tumor of the Breast
Authors: Ng W.F. , Poon C.S.P. , Alagaratnam T.T. , Leung E.Y.F. , Yip P.S.F. , So M.K.P.
Published: November 2007

The proliferating cell nuclear antigen (PCNA), a nuclear protein essential for cellular DNA synthesis, has been used to assess cellular proliferation in many tumors. To evaluate the potential value of PCNA in predicting the outcome of phyllodes tumor of the breast, we retrospectively studied 17 tumors diagnosed during the period 1985-1991. PC 10, a monoclonal antibody that recognizes PCNA, was applied to for malin-fixed, paraffin-embedded sections. The PCNA index ranged from 0.2% to 66.3%. The tumors were stratified into high (>9.8%, n = 4) or low (≤9.8%, n = 13) PCNA index groups. No significant correlation between high PCNA index and the clinicopath ologic parameters with the exception of infiltrative margin was sound. However, the difference in recurrence-free survival between the two groups was significant (log rank test P < .01). The Cox's regression analysis showed that high PCNA index was an important prognostic factor for tumor recurrence. PCNA staining could be used as an objective prognostic factor for the local recurrence of phyllodes tumor of the breast. Int J Surg Pathol 2(2):125-132, 1994
Malignant Lymphomas of the Bone in Korea
Authors: Park Yong-Koo , Lee Juhie , Moon Ho Yang  , Hye Rim Park  , Ja Jun Jang  , Kim Chul-Woo , Jung Dal Lee  , Woo Ick Yang
Published: November 2007

Eleven cases of primary non-Hodgkin's lymphoma of the bone collected from several institutes in Seoul, Korea were histologically and immunologically reclassified accord ing to U.S. National Cancer Institute working formulation, and the results were com pared with those in Western countries and in one Asian country (Japan). No significant differences were found in sex or in the distribution of primary lymphomas of bone between Korea, Japan, or the Western countries. Six cases previously diagnosed as "histiocytic lymphoma" were reclassified as diffuse large cell type lymphoma according to the working formulation. Two cases were diffuse small cell type and three cases were diffuse mixed small and large cell type. B cell immunophenotype was shown in 10 of 11 cases and T cell type was exhibited in 1 case. Patients with stage IE tumors had a better prognosis than those with stage IV. Histologic grade according to the U.S. National Cancer Institute working formulation correlated with clinical stage. A tendency towards better prognosis with lower grade tumors was possible but not statistically significant. Int J Surg Pathol 2(3):187-192, 1995
Delineation of the Proliferative Component of Inflammatory Fibroid Polyps of the Intestine
Authors: Hui Yun-Zhong , Noffsinger Amy E. , Guo Qian-Xin , Yochman Lucy K. , Hurtubise Paul , Fenoglio-Preiser Cecilia M.
Published: November 2007

Formalin-fixed, paraffin-embedded tissues from eight intestinal inflammatory fibroid polyps were analyzed using immunohistochemistry and flow cytometry to determine their immunohistochemical properties, DNA content, and the nature of the proliferat ing cells. In all cases, stromal cells stained diffusely for vimentin and focally for actin and histiocytic markers. Cell proliferative activity was assessed by flow cytometry and proliferating cell nuclear antigen staining. The S phase fraction was significantly in creased in inflammatory fibroid polyp when compared to control normal bowel tissues (10.8% ± 8.6% vs 6.7% ± 1.6%, P < .02). S phase fraction and proliferating cell nuclear antigen correlated in the stromal cells (r = 0.78, P < .05). Our data indicate that inflammatory fibroid polyps represent reactive, benign lesions containing poly clonal cell populations with diploid DNA content, and they have increased proliferative activity compared with normal intestinal tissues. Both the stromal cells and the vascu lar cells contributed to the proliferative activity of the lesion. Int J Surg Pathol 2(3): 207-214, 1995
Sucrase-Isomaltase Expression in Dysplasia Associated With Barrett's Esophagus and Chronic Gastritis
Authors: Nikulasson Sigfus , Andrews Charles W. , Goldman Harvey , Hallgrimsson Jonas , Cukor Barry , Mercurio Arthur M. , Steele Glenn D.
Published: November 2007

Aberrant cytoplasmic sucrase-isomaltase has been detected in colonic neoplasia, including dysplasia in ulcerative colitis. We investigated expression by immunostaining in 28 cases of Barrett's esophagus and 67 cases of chronic gastritis. Staining location (membrane or cytoplasmic) and percent positivity (< 1% = 0; 1-50% = 1+; > 50% = 2+) were record ed. Fifteen cases with Barrett's esophagus were negative for dysplasia, 1 was indefinite, and 12 were positive. All demonstrated surface membrane staining, while 2 of the 15 neg ative (1+) cases, 0 of the 1 indefinite case, and 11 of the 12 dysplastic (2+ in 7) cases revealed cytoplasmic positivity (P < .001). In chronic gastritis (23 were negative, 5 were indefinite, and 39 were positive) all revealed surface membrane staining, whereas cyto plasmic positivity was present in 1 of 23 negative (1+) cases, 1 of 5 indefinite cases, and 37 of 39 dysplastic (2+ in 18) cases (P < .001). In Barrett's esophagus and chronic gastri tis, cytoplasmic sucrase-isomaltase expression strongly correlates with the presence of dys plasia. Int J Surg Pathol 2(4).-281-286, 1995
Histologic and Cytogenetic Patterns in Benign, Atypical, and Malignant Meningiomas
Authors: Cerdá-Nicolás M. , López-Ginés C. , Peydró-Olaya A. , Barcia-Salorio J.L. , Llombart-Bosch A.
Published: November 2007

Atypical meningiomas comprise an intermediate category of meningeal neoplasmas with some microscopic features of aggressivity and a capacity for recurrence. We present a clin ical, morphologic, and cytogenetic study of 15 meningiomas. Morphologic and cytogenetic analysis suggested the existence of morphologically typical meningiomas with normal karyotype or monosomy 22 and morphologically atypical meningiomas, with increasing chromosomal abnormalities (complex karyotype) between these two types. Present results suggest the existence of a third type of morphologically typical meningioma that lacks a phenotypical aggressivity but has a complex karyotype. These genotypical characteristics may be related to the aggressivity of these neoplasms. Int J Surg Pathol 2(4):301-310, 1995