scholarly journals Evaluating Bayesian radiocarbon-dated event-count [REC] models for the study of long-term human and environmental processes

2020 ◽  
Author(s):  
William Christopher Carleton
Keyword(s):  
Forest Fires ◽  
Simulated Data ◽  
Radiocarbon Date ◽  
Radiocarbon Dates ◽  
New Class ◽  
Environmental Processes ◽  
Growth Decline ◽  
Marine Ingression ◽  
Event Times

Chronological uncertainty complicates attempts to use radiocarbon dates as proxies for processes like human population growth/decline, forest fires, and marine ingression. Established approaches involve turning databases of radiocarbon-date densities into single summary proxies that cannot fully account for chronological uncertainty. Here, I use simulated data to explore an alternate Bayesian approach that instead models the data as what they are, namely radiocarbon-dated event-counts. The approach involves assessing possible event-count sequences by sampling radiocarbon date densities and then applying MCMC to estimate the parameters of an appropriate count-based regression model. The regressions based on individual sampled sequences were placed in a multilevel framework, which allowed for the estimation of hyperparameters that account for chronological uncertainty in individual event times. Two processes were used to produce simulated data. One represented a simple monotonic change in event-counts and the other was based on a real palaeoclimate proxy record. In both cases, the method produced estimates that had the correct sign and were consistently biased toward zero. These results indicate that the approach is widely applicable and could form the basis of a new class of quantitative models for use in exploring long-term human and environmental processes.

scholarly journals Novel robust time series analysis for long-term and short-term prediction

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hiroshi Okamura ◽  
Yutaka Osada ◽  
Shota Nishijima ◽  
Shinto Eguchi
Keyword(s):  
Robust Regression ◽  
Simulated Data ◽  
New Method ◽  
Short Term ◽  
Least Absolute Deviations ◽  
Term Prediction ◽  
Regression Approach ◽  
Short Term Prediction ◽  
Long Term Prediction

AbstractNonlinear phenomena are universal in ecology. However, their inference and prediction are generally difficult because of autocorrelation and outliers. A traditional least squares method for parameter estimation is capable of improving short-term prediction by estimating autocorrelation, whereas it has weakness to outliers and consequently worse long-term prediction. In contrast, a traditional robust regression approach, such as the least absolute deviations method, alleviates the influence of outliers and has potentially better long-term prediction, whereas it makes accurately estimating autocorrelation difficult and possibly leads to worse short-term prediction. We propose a new robust regression approach that estimates autocorrelation accurately and reduces the influence of outliers. We then compare the new method with the conventional least squares and least absolute deviations methods by using simulated data and real ecological data. Simulations and analysis of real data demonstrate that the new method generally has better long-term and short-term prediction ability for nonlinear estimation problems using spawner–recruitment data. The new method provides nearly unbiased autocorrelation even for highly contaminated simulated data with extreme outliers, whereas other methods fail to estimate autocorrelation accurately.

scholarly journals Leopard Density Estimation within an Enclosed Reserve, Namibia Using Spatially Explicit Capture-Recapture Models

Animals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 724
Author(s):  
Noack ◽  
Heyns ◽  
Rodenwoldt ◽  
Edwards
Keyword(s):  
Management Strategies ◽  
Camera Traps ◽  
Spatially Explicit ◽  
Conservation Areas ◽  
Term Survival ◽  
New Class ◽  
Capture Recapture ◽  
Wildlife Populations ◽  
Effective Conservation

The establishment of enclosed conservation areas are claimed to be the driving force for the long-term survival of wildlife populations. Whilst fencing provides an important tool in conservation, it simultaneously represents a controversial matter as it stops natural migration processes, which could ultimately lead to inbreeding, a decline in genetic diversity and local extinction if not managed correctly. Thus, wildlife residing in enclosed reserves requires effective conservation and management strategies, which are strongly reliant on robust population estimates. Here, we used camera traps combined with the relatively new class of spatially explicit capture-recaptured models (SECR) to produce the first reliable leopard population estimate for an enclosed reserve in Namibia. Leopard density was estimated at 14.51 leopards/100 km2, the highest recorded density in Namibia to date. A combination of high prey abundance, the absence of human persecution and a lack of top-down control are believed to be the main drivers of the recorded high leopard population. Our results add to the growing body of literature which suggests enclosed reserves have the potential to harbour high densities and highlight the importance of such reserves for the survival of threatened species in the future.

Comparison of the mineralogical effects of an experimental forest fire on a goethite/ferrihydrite soil with a topsoil that contains hematite, maghemite and goethite

Clay Minerals ◽  
2009 ◽  
Vol 44 (2) ◽  
pp. 239-247 ◽  
Author(s):  
P. Nørnberg ◽  
A. L. Vendelboe ◽  
H. P. Gunnlaugsson ◽  
J. P. Merrison ◽  
K. Finster ◽  
...  
Keyword(s):  
Organic Matter ◽  
High Temperature ◽  
Forest Fire ◽  
Forest Fires ◽  
Organic Matter Content ◽  
Matter Content ◽  
Humid Climate ◽  
Fe Mineralogy ◽  
Reducing Environment

AbstractA long-standing unresolved puzzle related to the Danish temperate humid climate is the presence of extended areas with large Fe contents, where goethite and ferrihydrite are present in the topsoil along with hematite and maghemite. Hematite and, particularly, maghemite would normally be interpreted as the result of high temperature as found after forest fires. However, a body of evidence argues against these sites having been exposed to fire. In an attempt to get closer to an explanation of this Fe mineralogy, an experimental forest fire was produced. The results showed a clear mineralogical zonation down to 10 cm depth. This was not observed at the natural sites, which contained a mixture of goethite/ferrihydrite, hematite and maghemite down to 20 cm depth. The experimental forest fire left charcoal and ashes at the topsoil, produced high pH and decreased organic matter content, all of which is in contrast to the natural sites. The conclusion from this work is that the mineralogy of these sites is not consistent with exposure to forest fire, but may instead result from long-term transformation in a reducing environment, possibly involving microbiology.

New Light on the Midland Discovery

1959 ◽  
Vol 25 (1) ◽  
pp. 66-78 ◽  
Author(s):  
Fred Wendorf ◽  
Alex D. Krieger
Keyword(s):  
Small Mammals ◽  
Radiocarbon Date ◽  
High Plains ◽  
Faunal Assemblage ◽  
Southern High Plains ◽  
Stratigraphic Sequence ◽  
Radiocarbon Dates ◽  
Cultural Events ◽  
Animal Bones

AbstractAdditional excavation in 1955 confirmed the previously reported stratigraphic sequence at Midland, Texas. Within the gray sand, which had yielded a fragmentary human calvarium, there were found additional flint flakes, burned rocks, and animal bones. Besides several small mammals, a four-horned antelope (probably Capromeryx) was present in the gray sand; horse bones occurred in the gray sand and overlying red sand. These finds make the two radiocarbon dates published in the 1955 Midland report, giving an age of about 7000 years to the gray sand, even less acceptable than previously thought. Experimental dating by the uranium daughter products technique suggests an age of about 20,000 years for the gray sand, somewhat excessive in terms of cultural correlations although supported by a single radiocarbon date and not unreasonable for the faunal assemblage. Ten radiocarbon dates from the Midland, Blackwater Draw, Lubbock Lake, and Plainview sites are discussed in terms of three possible correlations of the geological, climatic, faunal, and cultural events in the Southern High Plains.

Pleistocene Mammals from Gold Run Creek, Yukon Territory

1973 ◽  
Vol 10 (5) ◽  
pp. 697-759 ◽  
Author(s):  
C. R. Harington ◽  
F. V. Clulow
Keyword(s):  
Yukon Territory ◽  
Radiocarbon Date ◽  
Common Elements ◽  
Radiocarbon Dates ◽  
Equus Asinus ◽  
Wild Ass ◽  
Pleistocene Mammals ◽  
First Time

Remains of thirteen species of mammals are reported from Pleistocene deposits at Gold Run Creek near Dawson, Yukon Territory. Eight of the thirteen species are extinct and two are no longer living in the Yukon. The most common elements of the fauna are Equus (Asinus) lambei (Yukon wild ass), and Bison crassicornis (large-horned bison). Taxidea (badger) and Bison alaskensis (Alaskan bison) are reported for the first time from the Yukon Pleistocene. A kiang-like horse is also reported from deposits at Gold Run Creek.These mammals may have inhabited a cool grassland or open parkland during late Wisconsin time. Bison crassicornis and mammoth bone from deposits at Gold Run Creek have yielded radiocarbon dates of 22 200 ± 1400 yr B.P. and 32 250 ± 1750 yr B.P. respectively. Bison alaskensis is evidently older than the remainder of the fauna as bone from the specimen yielded a radiocarbon date of over 39 900 yr B.P.

Is Age the New Class? Economic Crisis and Demographics in European Politics

2016 ◽  
Vol 43 (1) ◽  
pp. 59-71 ◽  
Author(s):  
Jan Erk
Keyword(s):  
Age Groups ◽  
The Political ◽  
Economic Downturn ◽  
New Class ◽  
Political Landscape ◽  
Younger Age ◽  
Material Interests ◽  
Post War ◽  
The Welfare State

As the crisis turns into long-term economic downturn, younger age-groups in Europe seem to be hit with higher levels of unemployment while the welfare state is steadily shrinking. The young have suddenly become a social group united by collective material interests, but does this translate into a sense of a collective political interest? The paper examines to what extent the dominant class-based social science of the post-war years can help us understand the politics of age-groups. The analysis highlights four changes since post-war years: the workplace has changed, impacting socialization; modern media has changed, impacting mobilization; the political landscape is fairly institutionalized, tempering the possibilities for new political concerns to find voice; and those who would define and articulate the political priorities of the young are leaving the Old Continent.

scholarly journals Paleoclimatic Implications of Radiocarbon Dating Of Speleothems from the Cracow-Wieluń Upland, Southern Poland

Radiocarbon ◽  
1995 ◽  
Vol 37 (2) ◽  
pp. 103-110 ◽  
Author(s):  
Anna Pazdur ◽  
Mieczysław F. Pazdur ◽  
Jacek Pawlyta ◽  
Andrzej Górny ◽  
Michał Olszewski
Keyword(s):  
Systematic Study ◽  
Radiocarbon Dating ◽  
Karst Region ◽  
Radiocarbon Dates ◽  
Preliminary Results ◽  
Last Glaciation ◽  
Geological Museum ◽  
Paleoclimatic Records ◽  
Age Range

We report preliminary results of a long-term systematic study intended to gather paleoclimatic records from precisely dated speleothems. The research project is limited to speleothems deposited in caves of the Cracow-Wieluń Upland, the largest and best-explored karst region in Poland, covering ca. 2900 km2 with >1000 caves. Speleothem samples were selected from collections of the Geological Museum of the Academy of Mining and Metallurgy in Cracow. Radiocarbon dates of these samples from ca. 45–20 ka bp almost exactly coincide with age range of the Interplenivistulian. A break in speleothem formation between ca. 20 and 10 ka bp may be interpreted as a result of serious climatic deterioration associated with the maximum extent of the last glaciation. We observed differences among 14C, U/Th and AAR dating results. Changes of δ13C and δ18O in speleothems that grew between ca. 30 and 20 ka bp may be interpreted as changes of paleoclimatic conditions.

Insect faunas of late Devensian and Flandrian age from Church Stretton, Shropshire

1972 ◽  
Vol 263 (852) ◽  
pp. 327-367 ◽  
Keyword(s):  
Pollen Analysis ◽  
Thermal Environment ◽  
Radiocarbon Date ◽  
Radiocarbon Dates ◽  
Number Of Species ◽  
Summer Temperatures ◽  
Zone Ii ◽  
Climatic Optimum ◽  
The Church

Invertebrate faunas consisting mainly of insects, from deposits in the Church Stretton valley, are described and discussed. These deposits fall into two periods: ( a ) Late Devensian, which follows an episode of glaciation and precedes a period of accumulation of frost-shattered gravel fans; and ( b ) Flandrian, which post-dates the gravels and has been placed in the post-Glacial pollen zones VI and VII. The faunas of these two episodes are dealt with separately in Parts I and II respectively. Part I. From two sites in which sequences containing clays, peats and silts were examined five radiocarbon dates are available, the oldest being 13 555 ± 620 years B.P. and the most recent 11 000 ± 200 years B.P. The faunas include a substantial number of species not now found in Shropshire, many not in Britain. Inferences on the changing ecology and thermal environment of the area are drawn from these faunas and are compared with the pollen analytical zones. This comparison shows that, according to the insects, the warmest part of the episode was late zone I, and that zone II (the Allerod), often considered to be the climatic optimum of the period, appears to have been a time of gradually deteriorating summer temperatures. Part II. Deposits from three late Flandrian sites are discussed. Although only one radiocarbon date was obtained, of 8101 ± 138 years B.P., pollen analysis was carried out by Rowlands throughout each sequence and this showed that the earliest deposit, at Little Stretton, dated from zone VI a and at all three localities deposition continued into zone VII b. An examination of the insect assemblages shows that completely different biotopes, from open pasture to dense woodland, were existing side by side in the Church Stretton valley in late Flandrian time. Summer temperatures at least as high as those of today are inferred. The possibility exists that during the period represented here the climate was even warmer than that of the present but until more information is available it is not possible to be more definite on this point.

scholarly journals Quantification of Internal Filtration in Hollow Fiber Hemodialyzers with Medium Cut-Off Membrane

2018 ◽  
Vol 46 (3) ◽  
pp. 196-204 ◽  
Author(s):  
Anna Lorenzin ◽  
Mauro Neri ◽  
Andrea Lupi ◽  
Martina Todesco ◽  
Monica Santimaria ◽  
...  
Keyword(s):  
Nuclear Imaging ◽  
Chronic Hemodialysis ◽  
Transmembrane Pressure ◽  
Hydraulic Permeability ◽  
Dialysate Flow ◽  
New Class ◽  
Inner Diameter ◽  
Marker Molecule

Background: Inadequate removal of molecules between 5 and 50 KDa may cause long-term complication in chronic hemodialysis. Medium cut-off (MCO) is a new class of membranes with enhanced sieving properties and negligible albumin loss. MCO membrane makes it possible to perform expanded hemodialysis (HDx), a technique based on high internal filtration (IF).The present study is designed to quantify IF in 2 MCO dialyzers (Theranova 400 and 500, Baxter, Deerfield, USA) using a nuclear imaging technique previously validated. Methods: Blood and dialysate compartment pressure drop along with transmembrane pressure; they were measured in a closed in vitro circuit with human blood (blood flow [QB] = 300 and 400 mL/min; dialysate flow 500 mL/min; net ultrafiltration rate 0 mL/min). A non-diffusible marker molecule (albumin macro-aggregates labeled with 99Tc metastable) was injected in the blood compartment and nuclear emission was recorded by a gamma camera. Relative variations in the concentration of the marker molecule along the length of the filter were used to calculate local cross filtration. Results: Based on marker concentration profiles, IF was estimated. For Theranova 400, IF were 29.7 and 41.6 mL/min for QB of 300 and 400 mL/min. For Theranova 500, IF were 31.6 and 53.1 mL/min for QB of 300 and 400 mL/min respectively. Conclusions: MCO membrane provides significant amounts of IF due to the particular combination between hydraulic permeability of the membrane and reduced inner diameter of the fibers. High IF combined with enhanced sieving profile of MCO membrane leads to improved removal of a wider spectrum of uremia retention molecules in HDx, without requiring complex equipment.

Visible Light-Activatable Q-dye Molecular Beacons for Long-Term mRNA Monitoring in Neurons

2021 ◽  
Author(s):  
Robin Klimek ◽  
Paul Donlin-Asp ◽  
Claudio Polisseni ◽  
Vanessa Hanff ◽  
Erin Schuman ◽  
...  
Keyword(s):  
Visible Light ◽  
Hippocampal Neurons ◽  
Molecular Beacons ◽  
New Class ◽  
Monitoring Time

Herein, we present a new class of Q-dye molecular beacons (MBs) that can be locally activated with visible light in hippocampal neurons. Our novel architecture increases the available monitoring time...

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