scholarly journals Wood14C Dating with AixMICADAS: Methods and Application to Tree-Ring Sequences from the Younger Dryas Event in the Southern French Alps

Radiocarbon ◽  
2017 ◽  
Vol 60 (1) ◽  
pp. 51-74 ◽  
Author(s):  
Manuela Capano ◽  
Cécile Miramont ◽  
Frédéric Guibal ◽  
Bernd Kromer ◽  
Thibaut Tuna ◽  
...  
Keyword(s):  
Tree Ring ◽  
Younger Dryas ◽  
Delayed Response ◽  
French Alps ◽  
Average Value ◽  
Large Samples ◽  
Maximum Value ◽  
Subfossil Wood ◽  
Younger Dryas Event ◽  
Sixth International

AbstractThe AixMICADAS facility is in part dedicated to research on radiocarbon (14C) calibration by means of various archives. For this purpose, we are improving upon the capacity to accurately date subfossil wood. In the current study, nine chemical pretreatment protocols are tested on six wood samples of known ages. The optimization based on14C ages,13C/12C ratios, carbon % and overall mass yield % leads us to favor the acid-base-acid-bleaching pretreatment (ABA-B). This efficient method is shown to provide a residue of holocellulose with optimal blanks equivalent to an age of 51,30014C BP with a standard deviation of 1500 yr based on 25 analyses. The seven wood samples from the Sixth International Radiocarbon Intercomparison (SIRI) are then analyzed as a further verification of the accuracy of our method. As a first scientific contribution, we studied two tree-ring sequences from subfossil pines (Barb12 and Barb17) collected in the southern French Alps. New14C analyses were performed at high resolution (every third year) and are shown to agree well with results obtained previously by high precision β-counting on CO2from large samples at lower resolution for Barb17 and accelerator mass spectrometry (AMS) data for Barb12. The new14C series are then matched to the Kauri and YDB chronologies: the new sequence of Barb12-17 tentatively corresponds to the interval between 12,836 and 12,594 cal BP within the Younger Dryas cold period. The14C comparison between the Barb12-17 sequence from France and the Kauri sequence from New Zealand allows calculating the14C Inter-Hemispheric Gradient (IHG), with an average value of ca. 57 yr. The IHG stayed relatively high throughout the studied period. Interestingly, the IHG exhibits a transient maximum value (ca. 100 yr) during the period of rapid Δ14C rise (12,750–12,720 cal BP), a behavior that could be due to a delayed response of the Southern Hemisphere.

The chronology of the last Deglaciation: Implications to the cause of the Younger Dryas Event

1988 ◽  
Vol 3 (1) ◽  
pp. 1-19 ◽  
Author(s):  
W. S. Broecker ◽  
M. Andree ◽  
W. Wolfli ◽  
H. Oeschger ◽  
G. Bonani ◽  
...  
Keyword(s):  
Younger Dryas ◽  
Last Deglaciation ◽  
The Last Deglaciation ◽  
Younger Dryas Event

scholarly journals Evapotranspiration and estimation of aerodynamic and stomatal conductance in a fragment of Atlantic Forest in mantiqueira range region, MG

CERNE ◽  
2010 ◽  
Vol 16 (1) ◽  
pp. 32-40 ◽  
Author(s):  
Donizete dos Reis Pereira ◽  
Carlos Rogério de Mello ◽  
Antônio Marciano da Silva ◽  
Sílvia de Nazaré Monteiro Yanagi
Keyword(s):  
Stomatal Conductance ◽  
Water Balance ◽  
Atlantic Forest ◽  
Environmental Modeling ◽  
Average Value ◽  
Maximum Value ◽  
Minas Gerais State ◽  
Forest Remnants ◽  
Forested Areas ◽  
And Storage

Understanding hydrologic behavior in forested areas, not least the Brazilian Atlantic Forest, is of fundamental importance for environmental modeling. This work aimed to estimate evapotranspiration values in Atlantic Forest remnants of Mantiqueira Range region using water balance calculations, and to estimate parameters (stomatal and aerodynamic conductances) for this vegetation cover using the Penman-Monteith model. In terms of water balance, evapotranspiration accounted for 89% of total precipitation, deep percolation accounted for 13.6% and storage variation was slightly negative over the analysis period. Canopy aerodynamic conductance (g a) presented a minimum value of 0.0921 m s-1, a maximum value of 0.1000 m s-1 and an average value of 0.0993 m s-1. Stomatal conductance (g s) varied from 0.001 to 0.0046 m s-1, with an average value of 0.0022 m s-1, being influenced by environmental conditions, especially by soil water availability. It was observed that the application of the Penman-Monteith model with average parameter fit (g a and g s) provided good accuracy, especially over the dry season, therefore it can be applied to studies of forest hydrology in fragments of Atlantic Forest in the Mantiqueira Range region, Minas Gerais state.

scholarly journals Field and Laboratory-based Approach for the Determination of Friction Angle of Geological Discontinuities of Malaysian Granites

2011 ◽  
Vol 28 (2) ◽  
pp. 151 ◽  
Author(s):  
R. A Ghani ◽  
T. L Goh ◽  
A. M Hariri ◽  
Y. N Baizura
Keyword(s):  
Friction Angle ◽  
Roughness Coefficient ◽  
Average Value ◽  
Peak Friction Angle ◽  
Maximum Value ◽  
Wide Range ◽  
Discontinuity Surfaces ◽  
Geological Discontinuities ◽  
Range Of Values

The basic friction angle, Φb for artificially sawn discontinuity planes for fresh granite, as determined by tilt testing, has an average value of 30º. For the natural rough discontinuity surfaces, a wide range of values have been determined for the peak friction angle, Φpeak ranging from 47º to a maximum value of 80º, depending on the joint roughness coefficient (JRC). The average values of the friction angles for the different degrees of roughness were as follows: JRC 2–4 = 58°; JRC 6–8 = 60°; JRC 8–10 = 47°; JRC 12–14 = 60°; JRC 14–16 = 71° ; JRC 18–20 = 80°.

scholarly journals Physiological Values of P-Wave Dispersion in Silesian Breed Horses and Polish Primitive Horses

2013 ◽  
Vol 57 (1) ◽  
pp. 85-89
Author(s):  
Katarzyna Michlik ◽  
Agnieszka Noszczyk-Nowak ◽  
Urszula Pasławska ◽  
Izabela Janus ◽  
Józef Nicpoń
Keyword(s):  
Body Mass ◽  
Wave Dispersion ◽  
P Wave ◽  
P Wave Dispersion ◽  
Average Value ◽  
Maximum Value ◽  
Physiological Values ◽  
Physiological Value

Abstract Electrocardiographic examinations were performed on 45 Silesian breed horses (group K, 3-16-year-old, 16 stallions, 29 mares) and on 25 Polish Primitive breed horses (group P, 1.5-19-year-old, two stallions, six geldings, 17 mares). Einthoven and chest leads were used. P-wave dispersion was electronically evaluated. There was no correlation between P-wave dispersion and other ECG parameters, age, sex, body mass, or month of pregnancy. The average value of P-wave dispersion for all horses was 30.77 ms (SD 3.92 ms), however in particular groups it was: in group P - 31.89 ms (SD 3.07 ms), and in group K - 30.15 ms (SD 4.27 ms). The maximum value of P-wave dispersion in the studied population was 40 ms, in groups P and K - 37,6 ms and 40 ms, respectively. The physiological value of P-wave dispersion for the group of horses was below 45 ms.

scholarly journals Tree-ring radiocarbon reveals reduced solar activity during Younger Dryas cooling

2020 ◽  
Author(s):  
Adam Sookdeo ◽  
Bernd Kromer ◽  
Florian Adolphi ◽  
Jürg Beer ◽  
Nicolas Brehm ◽  
...  
Keyword(s):  
Solar Activity ◽  
Tree Ring ◽  
North Atlantic ◽  
Little Ice Age ◽  
Ice Core ◽  
Younger Dryas ◽  
Ice Age ◽  
The North ◽  
Long Duration ◽  
Clear Sign

<p>The Younger Dryas stadial (YD) was a return to glacial-like conditions in the North Atlantic region that interrupted deglacial warming around 12900 cal BP (before 1950 AD). Terrestrial and marine records suggest this event was initiated by the interruption of deep-water formation arising from North American freshwater runoff, but the causes of the millennia-long duration remain unclear. To investigate the solar activity, a possible YD driver, we exploit the cosmic production signals of tree-ring radiocarbon (<sup>14</sup>C) and ice-core beryllium-10 (<sup>10</sup>Be). Here we present the highest temporally resolved dataset of <sup>14</sup>C measurements (n = 1558) derived from European tree rings that have been accurately extended back to 14226 cal BP (±8, 2-σ), allowing precise alignment of ice-core records across this period. We identify a substantial increase in <sup>14</sup>C and <sup>10</sup>Be production starting at 12780 cal BP is comparable in magnitude to the historic Little Ice Age, being a clear sign of grand solar minima. We hypothesize the timing of the grand solar minima provides a significant amplifying factor leading to the harsh sustained glacial-like conditions seen in the YD.</p>

scholarly journals Identification of Disease on Leaves Soybean using Modified Otsu and Learning Vector Quantization Neural Networks

Kursor ◽  
2018 ◽  
Vol 9 (3) ◽  
Author(s):  
Candra Dewi ◽  
Muhammad Sa’idul Umam ◽  
Imam Cholissodin
Keyword(s):  
Vector Quantization ◽  
Threshold Value ◽  
Learning Vector Quantization ◽  
Training Data ◽  
Blue Color ◽  
Phakopsora Pachyrhizi ◽  
Average Value ◽  
Maximum Value ◽  
Otsu Method ◽  
Soybean Leaf

Disease of the soybean crop is one of the obstacles to increase soybean production in Indonesia. Some of these diseases usually are found in the leaves and resulted to the crop become unhealthy. This study aims to identify disease on soybean leaf through leaves image by applying the Learning Vector Quantization (LVQ) algorithm. The identification begins with preprocessing using modified Otsu method to get part of the diseases on the leaves with a certain threshold value. The next process is to identify the type of disease using LVQ. This process uses the minimum value, the maximum value and the average value of the red, green and blue color of the image. The testing conducted in this study is to identify two diseases called Peronospora manshurica (Downy Mildew) and phakopsora pachyrhizi (Karat). The result of testing by using 60 training data and the value of all recommendations parameters obtained the highest accuracy of identification is 95% %, but the more stable accuracy is 90%. This result shows that the method perform quite well identification of two mentioned disease.

scholarly journals Tree-Ring Records of Near-Younger Dryas Time in Central North America—Preliminary Results from the Lincoln Quarry Site, Central Illinois, Usa

Radiocarbon ◽  
2004 ◽  
Vol 46 (2) ◽  
pp. 933-941 ◽  
Author(s):  
Irina P Panyushkina ◽  
Steven W Leavitt ◽  
Alex Wiedenhoeft ◽  
Sarah Noggle ◽  
Brandon Curry ◽  
...  
Keyword(s):  
North America ◽  
Tree Ring ◽  
Environmental Changes ◽  
Ring Width ◽  
Younger Dryas ◽  
Late Glacial ◽  
Radiocarbon Dates ◽  
Initial Sampling ◽  
Central Illinois ◽  
A Site

The abrupt millennial-scale changes associated with the Younger Dryas (YD) event (“chronozone”) near the dawn of the Holocene are at least hemispheric, if not global, in extent. Evidence for the YD cold excursion is abundant in Europe but fairly meager in central North America. We are engaged in an investigation of high-resolution environmental changes in mid-North America over several millennia (about 10,000 to 14,000 BP) during the Late Glacial–Early Holocene transition, including the YD interval. Several sites containing logs or stumps have been identified and we are in the process of initial sampling or re-sampling them for this project. Here, we report on a site in central Illinois containing a deposit of logs initially thought to be of YD age preserved in alluvial sands. The assemblage of wood represents hardwood (angiosperm) trees, and the ring-width characteristics are favorable to developing formal tree-ring chronologies. However, 4 new radiocarbon dates indicate deposition of wood may have taken place over at least 8000 14C yr (6000–14,000 BP). This complicates the effort to develop a single floating chronology of several hundred years at this site, but it may provide wood from a restricted region over a long period of time from which to develop a sequence of floating chronologies, the timing of deposition and preservation of which could be related to paleoclimatic events and conditions.

scholarly journals Comparison of the SRmax, SRave, and color map of strain-elastography in differentiating malignant from benign breast lesions

2018 ◽  
Vol 60 (1) ◽  
pp. 28-34
Author(s):  
Jin Hee Moon ◽  
Sung Hye Koh ◽  
Sun-Young Park ◽  
Ji-Young Hwang ◽  
Ji Young Woo
Keyword(s):  
Statistical Significance ◽  
Roc Curves ◽  
Strain Ratio ◽  
Breast Lesions ◽  
Strain Elastography ◽  
Average Value ◽  
Maximum Value ◽  
Significant Difference ◽  
Malignant Breast ◽  
Color Map

Background The maximum value of the strain ratio (SR) is a newly developed measure in strain-elastography. Purpose To prospectively compare the diagnostic performance of three different measures of strain-elastography, the maximum value of the SR (SRmax), the average value of the SR (SRave), and the color map, for differentiating benign and malignant breast lesions. Material and Methods We obtained the SRmax and SRave of 314 lesions from 290 patients with the tissue to nodule SR and color map using a five-degree scoring system. The diagnostic performances of the SRmax, SRave, and color map were compared after obtaining the area under the receiver operating characteristic (ROC) curves (AUCs) of each parameter. Results The AUC of the SRmax (0.7674) was larger than the AUCs of the SRave (0.7138) and color map (0.6324), with statistical significance ( P = 0.0383 for SRmax vs. SRave, P = 0.0000 for SRmax vs. color map). The AUC of the SRave was larger than that of the color map; however, there was no significant difference. The optimal cut-off point of the SRmax that balanced the sensitivity (91.12%) and specificity (50.81%) was 5.16. Conclusion The SRmax is a more reliable diagnostic tool than the SRave and color map for differentiating benign and malignant breast lesions.

scholarly journals The global hydroclimate response during the Younger Dryas event

2018 ◽  
Vol 193 ◽  
pp. 84-97 ◽  
Author(s):  
Hans Renssen ◽  
Hugues Goosse ◽  
Didier M. Roche ◽  
Heikki Seppä
Keyword(s):  
Younger Dryas ◽  
Younger Dryas Event
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