scholarly journals Signal strength and climate calibration of a European tree-ring isotope network

2007 ◽  
Vol 34 (24) ◽  
Author(s):  
K. Treydte ◽  
D. Frank ◽  
J. Esper ◽  
L. Andreu ◽  
Z. Bednarz ◽  
...  
Keyword(s):  
Tree Ring ◽  
Signal Strength

scholarly journals Signal strength and climate relationships in13C/12C ratios of tree ring cellulose from oak in east England

1997 ◽  
Vol 102 (D16) ◽  
pp. 19507-19516 ◽  
Author(s):  
I. Robertson ◽  
V. R. Switsur ◽  
A. H. C. Carter ◽  
A. C. Barker ◽  
J. S. Waterhouse ◽  
...  
Keyword(s):  
Tree Ring ◽  
Signal Strength ◽  
Tree Ring Cellulose

scholarly journals Evaluating the dendroclimatological potential of blue intensity on multiple conifer species from Australasia

2021 ◽  
Author(s):  
Rob Wilson ◽  
Kathy Allen ◽  
Patrick Baker ◽  
Sarah Blake ◽  
Gretel Boswijk ◽  
...  
Keyword(s):  
New Zealand ◽  
Tree Ring ◽  
High Frequency ◽  
Ring Width ◽  
Signal Strength ◽  
Summer Temperature ◽  
Weak Signal ◽  
Conifer Species ◽  
Blue Intensity ◽  
Blue Reflectance

Abstract. We evaluate a range of blue intensity (BI) tree-ring parameters in eight conifer species (12 sites) from Tasmania and New Zealand for their dendroclimatic potential, and as surrogate wood anatomical proxies. Using a dataset of ca. 10–15 trees per site, we measured earlywood maximum blue reflectance intensity (EWB), latewood minimum blue reflectance intensity (LWB) and the associated delta blue intensity (DB) parameter for dendrochronological analysis. No resin extraction was performed, impacting low frequency trends. Therefore, we focused only on the high frequency signal by detrending all tree-ring and climate data using a 20-year cubic smoothing spline. All BI parameters express low relative variance and weak signal strength compared to ring-width. Correlation analysis and principal component regression experiments identified a weak and variable climate response for most ring-width chronologies. However, for most sites, the EWB data, despite weak signal strength, expressed strong calibrations with summer temperatures. Significant correlations for LWB were also noted, but the sign of the relationship for most species is opposite to that reported for all conifer species in the Northern Hemisphere. DB performed well for the Tasmanian sites but explained minimal temperature variance in New Zealand. Using the full multi-species/parameter network, excellent summer temperature calibration was identified for both Tasmania and New Zealand ranging from 52 % to 78 % explained variance, with equally robust independent validation (Coefficient of Efficiency = 0.41 to 0.77). Comparison of the Tasmanian BI reconstruction with a wood anatomical reconstruction shows that these parameters record essentially the same strong high frequency summer temperature signal. Despite these excellent results, a substantial challenge exists with the capture of potential secular scale climate trends. Although DB, band-pass and other signal processing methods may help with this issue, substantially more experimentation is needed in conjunction with comparative analysis with ring density and quantitative WA measurements.

scholarly journals Signal strength and climate relationships in13C/12C ratios of tree ring cellulose from oak in southwest Finland

1997 ◽  
Vol 24 (12) ◽  
pp. 1487-1490 ◽  
Author(s):  
I. Robertson ◽  
J. Rolfe ◽  
V. R. Switsur ◽  
A. H. C. Carter ◽  
M. A. Hall ◽  
...  
Keyword(s):  
Tree Ring ◽  
Signal Strength ◽  
Tree Ring Cellulose

scholarly journals Signal Strength In Sub-Annual Tree-Ring Chronologies fromPinus ponderosaIn Northern New Mexico

2013 ◽  
Vol 69 (2) ◽  
pp. 81-86 ◽  
Author(s):  
Becky Brice ◽  
Kara K. Lorion ◽  
Daniel Griffin ◽  
Alison K. Macalady ◽  
Christopher H. Guiterman ◽  
...  
Keyword(s):  
New Mexico ◽  
Tree Ring ◽  
Signal Strength

Identification of a CVD Synthetic Diamond with a 'Tree Ring' Growth Pattern

2015 ◽  
Vol 34 (8) ◽  
pp. 702-710
Author(s):  
Yan Lan ◽  
Rong Liang ◽  
Taijin Lu ◽  
Yong Zhu ◽  
Tianyang Zhang ◽  
...  
Keyword(s):  
Tree Ring ◽  
Growth Pattern ◽  
Synthetic Diamond

Improved Contrast in Ultra-Low-Field MRI with Time-Dependent Bipolar Prepolarizing Fields: Theory and NMR Demonstrations

2013 ◽  
Vol 20 (3) ◽  
pp. 327-336 ◽  
Author(s):  
Jaakko O. Nieminen ◽  
Jens Voigt ◽  
Stefan Hartwig ◽  
Hans Jürgen Scheer ◽  
Martin Burghoff ◽  
...  
Keyword(s):  
Field Strength ◽  
Time Course ◽  
Signal Strength ◽  
Relaxation Rates ◽  
Resonance Imaging ◽  
New Approach ◽  
Spin Lattice ◽  
Low Field ◽  
Low Field Mri ◽  
Magnetic Resonance Imaging Mri

Abstract The spin-lattice (T1) relaxation rates of materials depend on the strength of the external magnetic field in which the relaxation occurs. This T1 dispersion has been suggested to offer a means to discriminate between healthy and cancerous tissue by performing magnetic resonance imaging (MRI) at low magnetic fields. In prepolarized ultra-low-field (ULF) MRI, spin precession is detected in fields of the order of 10-100 μT. To increase the signal strength, the sample is first magnetized with a relatively strong polarizing field. Typically, the polarizing field is kept constant during the polarization period. However, in ULF MRI, the polarizing-field strength can be easily varied to produce a desired time course. This paper describes how a novel variation of the polarizing-field strength and duration can optimize the contrast between two types of tissue having different T1 relaxation dispersions. In addition, NMR experiments showing that the principle works in practice are presented. The described procedure may become a key component for a promising new approach of MRI at ultra-low fields

Sign in / Sign up

Export Citation Format

Share Document