Cyclophytic effects on wood structure in Pinusradiata D. Don. II. Tracheid morphology

1988 ◽  
Vol 18 (4) ◽  
pp. 413-420 ◽  
Author(s):  
Richard S. Dodd
Keyword(s):  
Growth Ring ◽  
Anatomical Variation ◽  
Radiata Pine ◽  
Growth Rings ◽  
Tree Form ◽  
Ring Number ◽  
Tracheid Length ◽  
Rate Of Increase ◽  
The Difference

The effects of apical ontogeny on xylem morphology in Pinusradiata were examined in grafted trees and in clonal pairs of trees grown from cuttings from hedge- and tree-form donors (H and T). At the time of sampling the grafted rootstocks were 21 years old, and trees from H and T plants were 11 years old from the date of planting rooted cuttings. In grafted trees tracheids were longer, and the rate of increase in tracheid length was greater above the graft. Since growth rings were narrower above the graft, the difference in rate of increase in tracheid length above and below the graft was greater when plotted against distance from pith than against growth ring number. In comparisons of H and T plants, T plants (expected to be at a later stage of apical ontogeny) produced fewer but longer and wider tracheids. Cell wall volumes per tracheid were greater in T plants, but because the tracheid diameters in H plants were smaller, wall volumes per unit tracheid volumes were consistently greater in H plants. The role of apical ontogeny in explaining patterns of anatomical variation within the stem is discussed. H and T plants of radiata pine were from the three mainland populations: Año Nuevo, Monterey, and Cambria. The Año Nuevo population produced the greatest numbers and the largest tracheids. The Monterey population had the shortest tracheids amongst H plants, but their tracheid lengths were equal to those of the Año Nuevo population in T plants.

Distribution of juvenile wood in two stems of Larixlaricina

1986 ◽  
Vol 16 (5) ◽  
pp. 1041-1049 ◽  
Author(s):  
K. C. Yang ◽  
C. A. Benson ◽  
J. K. Wong
Keyword(s):  
Juvenile Wood ◽  
Growth Ring ◽  
Ring Width ◽  
Tree Level ◽  
Growth Rings ◽  
Vertical Variation ◽  
Strong Negative Correlation ◽  
Ring Number ◽  
Tracheid Length ◽  
Growth Ring Width

The distribution and vertical variation of juvenile wood was studied in an 81-year-old dominant tree and an 83-year-old suppressed tree of Larixlaricina (Du Roi) K. Koch. Two criteria, growth ring width and tracheid length, were used to demarcate the boundary of juvenile wood. The width of juvenile wood, expressed in centimetres and the number of growth rings, decreased noticeably from the base to the top of the tree. The volume of juvenile wood decreased in a similar pattern. These decreasing trends had a strong negative correlation with the year of formation of cambial initials at a given tree level. The length of these cambial initials decreased with increasing age of formation of the cambial initials. In the juvenile wood zone, there was a positive linear regression between the growth ring number (age) and the tracheid length. The slopes of these regression lines at various tree levels increased as the age of the year of formation of the cambial initials increased. At a given tree level, the length of tracheids increased from the pith to a more uniform length near the bark. However, the number of years needed to attain a more uniform tracheid length decreased from the base to the top of the tree. These relationships suggest that the formation of juvenile wood is related to the year of formation of the cambial initials. Consequently, the juvenile wood is conical in shape, tapering towards the tree top.

MICROFIBRIL ANGLES IN THE ROOT WOOD OF PINUS RADIATA AND PINUS NIGRA

IAWA Journal ◽  
2001 ◽  
Vol 22 (1) ◽  
pp. 57-62 ◽  
Author(s):  
Junji Matsumura ◽  
Brian G. Butterfield
Keyword(s):  
Pinus Radiata ◽  
Growth Ring ◽  
Microfibril Angle ◽  
Pinus Nigra ◽  
Growth Rings ◽  
Stem Wood ◽  
The Third ◽  
Tracheid Length ◽  
Angle Change ◽  
Wood Tracheid

Microfibril angles of the S2 layer and tracheid lengths were measured in the root wood of Pinus nigra, and the root and stem wood of Pinus radiata. Within 10 mm (the first 2–3 growth rings) from the root centre, microfibril angles were large in the wood of both species, ranging from 25° to 40°. Beyond 10 mm (the fourth growth ring and beyond) from the root centre, microfibril angles were small. This pattern of microfibril angle change in root wood differs from those normally found in stems where angles are large until the 10–15th rings. Root wood tracheid length also showed a different pattern in radial direction from that normally observed in stem wood. Tracheids of Pinus radiata root wood were long in the first ring, decreasing to the third ring and then increased to the seventh ring. Beyond the seventh ring tracheid length was stable at around 3 to 3.5 mm. It was noted that microfibril angles were not influenced by tracheid length in root wood.

Growth and Fire Response of Selected Epacridaceae of South-Western Australia

1996 ◽  
Vol 44 (5) ◽  
pp. 509 ◽  
Author(s):  
TL Bell ◽  
JS Pate
Keyword(s):  
Growth Ring ◽  
Shoot Biomass ◽  
Ring Extension ◽  
Growth Rings ◽  
Ring Number ◽  
Root Stock ◽  
Xylem Growth ◽  
Root Starch ◽  
Shoot Removal ◽  
Bud Initiation

Recruiting populations of seeder (Astroloma xerophyllum (DC.) Sond. and Leucopogon conostephioides DC.) and resprouter (Leucopogon verticillatus R.Br. and Conostephium pendulum. Benth.) epacrids were examined over an 8 year period, using time of fire, shoot morphology and root xylem ring number to age plants. The seeders commenced flowering earlier, achieved three-fold higher shoot:root ratios but accumulated much smaller root starch reserves than the resprouters. The resprouting potential of L. verticillatus was 'bud initiation-limited', since progressive shoot removal exhausted the bud-producing potential but did not fully deplete the starch reserves of the root stock. Apparent conversion efficiency of starch to new shoot biomass was 88%. The corresponding response in C. pendulum was 'energy reserve-limited', with shoot removal eliminating root starch but leaving many unexpanded buds. Dendroecological analyses of root xylem growth rings were undertaken on 15 year-old plants of C. pendulum recruiting from seed in unburnt and adjacent periodically burnt habitats. Growth ring extension of burnt plants resumed after each fire at rates faster than their unburnt counterparts, suggesting that improved access by resprouting shoots to light, water and nutrients compensated for destruction of the previous shoot system.

Cyclophytic effects on wood structure in Pinus radiata D. Don. I. Densitometry and grain angle

1988 ◽  
Vol 18 (4) ◽  
pp. 406-412 ◽  
Author(s):  
Richard S. Dodd ◽  
Nancy K. Walker
Keyword(s):  
Pinus Radiata ◽  
Growth Ring ◽  
Structural Characteristics ◽  
Wood Formation ◽  
Density Variation ◽  
Wood Structure ◽  
Growth Rings ◽  
Tree Form ◽  
Ring Density ◽  
Latewood Density

Wood structural characteristics were compared in 11-year-old Pinusradiata trees from hedge- and tree-form donors (H and T) to examine the effects of apical ageing (cyclophysis) on wood formation. Although the differences were small, T plants tended to produce wood with narrower growth rings and lower density in the first two rings. T plants showed a greater contrast between density at the end of one growth ring and the beginning of the next. The lower mean growth ring density in T plants was mainly due to a lower earlywood density with little difference in latewood density or latewood percentage. Although differences in density from early- to late-wood were greater in T plants, there was no difference between H and T plants in within-ring density variation. This was due to greater fluctuations in density across growth rings of H plants, perhaps because these plants were less buffered against the environment. Differences in wood structure between H and T plants were not the same for all clones, as shown by significant interactions in the analyses of variance. These different responses may have resulted from differences in the effectiveness of hedging in slowing apical maturation, or from differences in rates of maturation.

Morphological Features of Tracheid Tips Associated With Compression Wood Formation in Larix Leptolepis Gord.

IAWA Journal ◽  
1985 ◽  
Vol 6 (3) ◽  
pp. 245-253 ◽  
Author(s):  
Nobuo Yoshizawa ◽  
Shuichi Matsumoto ◽  
Toshinaga Idei
Keyword(s):  
Compression Wood ◽  
Growth Ring ◽  
Wood Formation ◽  
Morphological Features ◽  
Larix Leptolepis ◽  
Growth Rings ◽  
Wood Development ◽  
Tracheid Length ◽  
Ring Compression ◽  
Angular Displacements

Variation in the morphological features of tracheid tips was observed within and among sterns of larch (Larix leptolepis Gord.) with several different angular displacements from the vertical. The formation of compression wood increased with an increasing angle of stern deviation. Decrease in tracheid length occurred with thc development of compression wood within a growth ring. Compression wood also was accompanied by an increase in the occurrence of abnormal tips. Flattened and Lshaped tips of tracheids increased in number with the development of compression wood and the number of smoothly tapered tips decreased, indicating that the intrusive growth between adjacent cells does not proceed smoothIy in compression wood. It is considered that the spatial readjustment of developing cells is restricted in compression wood, and results from the great increase in the rate of cell division. A negative correlation between tracheid length and morphological abnormalities of tracheid tips was found within growth rings, apparently associated with the severity of compression wood development.

The role of differential phase contrast in electron microscopy

1978 ◽  
Vol 36 (1) ◽  
pp. 176-177
Author(s):  
E.M. Waddell ◽  
J.N. Chapman ◽  
R.P. Ferrier
Keyword(s):  
Phase Contrast ◽  
Practical Method ◽  
Position Vector ◽  
Differential Phase ◽  
Pure Phase ◽  
Differential Phase Contrast ◽  
The Difference ◽  
Image Position ◽  
First Moment

Dekkers and de Lang (1977) have discussed a practical method of realising differential phase contrast in a STEM. The method involves taking the difference signal from two semi-circular detectors placed symmetrically about the optic axis and subtending the same angle (2α) at the specimen as that of the cone of illumination. Such a system, or an obvious generalisation of it, namely a quadrant detector, has the characteristic of responding to the gradient of the phase of the specimen transmittance. In this paper we shall compare the performance of this type of system with that of a first moment detector (Waddell et al.1977).For a first moment detector the response function R(k) is of the form R(k) = ck where c is a constant, k is a position vector in the detector plane and the vector nature of R(k)indicates that two signals are produced. This type of system would produce an image signal given bywhere the specimen transmittance is given by a (r) exp (iϕ (r), r is a position vector in object space, ro the position of the probe, ⊛ represents a convolution integral and it has been assumed that we have a coherent probe, with a complex disturbance of the form b(r-ro) exp (iζ (r-ro)). Thus the image signal for a pure phase object imaged in a STEM using a first moment detector is b2 ⊛ ▽ø. Note that this puts no restrictions on the magnitude of the variation of the phase function, but does assume an infinite detector.

On the Role of Transferrin in 67Ga Uptake by Tumor Cells

1988 ◽  
Vol 27 (04) ◽  
pp. 151-153
Author(s):  
P. Thouvenot ◽  
F. Brunotte ◽  
J. Robert ◽  
L. J. Anghileri
Keyword(s):  
Specific Binding ◽  
Subcellular Fractionation ◽  
Animal Blood ◽  
Tumor Bearing ◽  
Cell Structures ◽  
The Difference ◽  
Sarcoma Cells ◽  
In Vitro Uptake

In vitro uptake of 67Ga-citrate and 59Fe-citrate by DS sarcoma cells in the presence of tumor-bearing animal blood plasma showed a dramatic inhibition of both 67Ga and 59Fe uptakes: about ii/io of 67Ga and 1/5o of the 59Fe are taken up by the cells. Subcellular fractionation appears to indicate no specific binding to cell structures, and the difference of binding seems to be related to the transferrin chelation and transmembrane transport differences

REFLECTION COEFFICIENT OF AN ELECTROMAGNETIC WAVE IN CONDUCTIVE MEDIA

2018 ◽  
pp. 100-106
Author(s):  
M. S. Sudakova ◽  
M. L. Vladov ◽  
M. R. Sadurtdinov
Keyword(s):  
Reflection Coefficient ◽  
Ground Penetrating Radar ◽  
Electromagnetic Waves ◽  
Water Contamination ◽  
Survey Design ◽  
Direct And Inverse Problems ◽  
The Difference ◽  
Ground Penetrating ◽  
Ideal Dielectric

Within the ground penetrating radar bandwidth the medium is considered to be an ideal dielectric, which is not always true. Electromagnetic waves reflection coefficient conductivity dependence showed a significant role of the difference in conductivity in reflection strength. It was confirmed by physical modeling. Conductivity of geological media should be taken into account when solving direct and inverse problems, survey design planning, etc. Ground penetrating radar can be used to solve the problem of mapping of halocline or determine water contamination.

Speculative Realism and Science Fiction

2017 ◽  
Author(s):  
Brian Willems
Keyword(s):  
Science Fiction ◽  
Identity Formation ◽  
Cormac Mccarthy ◽  
Doris Lessing ◽  
Speculative Realism ◽  
Neil Gaiman ◽  
The World ◽  
The Difference ◽  
Quentin Meillassoux

A human-centred approach to the environment is leading to ecological collapse. One of the ways that speculative realism challenges anthropomorphism is by taking non-human things to be as valid objects of investivation as humans, allowing a more responsible and truthful view of the world to take place. Brian Willems uses a range of science fiction literature that questions anthropomorphism both to develop and challenge this philosophical position. He looks at how nonsense and sense exist together in science fiction, the way in which language is not a guarantee of personhood, the role of vision in relation to identity formation, the difference between metamorphosis and modulation, representations of non-human deaths and the function of plasticity within the Anthropocene. Willems considers the works of Cormac McCarthy, Paolo Bacigalupi, Neil Gaiman, China Miéville, Doris Lessing and Kim Stanley Robinson are considered alongside some of the main figures of speculative materialism including Graham Harman, Quentin Meillassoux and Jane Bennett.

On the Use of Quantum Thermal Bath in Unimolecular Fragmentation Simulations

2019 ◽  
Author(s):  
Riccardo Spezia ◽  
Hichem Dammak
Keyword(s):  
Degrees Of Freedom ◽  
Molecular Simulations ◽  
Zero Point ◽  
Thermal Bath ◽  
Unimolecular Dissociation ◽  
Point Energy ◽  
Rotational Degrees Of Freedom ◽  
The Difference ◽  
Nuclear Effects

<div> <div> <div> <p>In the present work we have investigated the possibility of using the Quantum Thermal Bath (QTB) method in molecular simulations of unimolecular dissociation processes. Notably, QTB is aimed in introducing quantum nuclear effects with a com- putational time which is basically the same as in newtonian simulations. At this end we have considered the model fragmentation of CH4 for which an analytical function is present in the literature. Moreover, based on the same model a microcanonical algorithm which monitor zero-point energy of products, and eventually modifies tra- jectories, was recently proposed. We have thus compared classical and quantum rate constant with these different models. QTB seems to correctly reproduce some quantum features, in particular the difference between classical and quantum activation energies, making it a promising method to study unimolecular fragmentation of much complex systems with molecular simulations. The role of QTB thermostat on rotational degrees of freedom is also analyzed and discussed. </p> </div> </div> </div>

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