The Roles of Sink Size and Location in the Partitioning of Assimilates in Wheat Ears

1983 ◽  
Vol 10 (3) ◽  
pp. 313 ◽  
Author(s):  
MG Cook ◽  
LT Evans
Keyword(s):  
Relative Size ◽  
Experimental System ◽  
Relative Distance ◽  
Vascular Connection ◽  
Factors Influencing ◽  
Geometric Factors ◽  
Sink Size ◽  
Stem Reserves

Geometric factors influencing the partitioning of 14C-labelled photosynthate between two sinks were examined in wheat ears. An awn on one spikelet was the only source of current assimilate while grains in two other spikelets were the competing sinks. The number of grains in these and their distance and vascular connection to the source were varied, while access to stem reserves could be cut off by heat ringing. Even this apparently simple experimental system presented a number of complications, such as a bias in favour of 14C movement to the upper spikelets within an ear and to the upper grains within a spikelet. These are considered before results on the effect of relative size, distance and vascular connection are described. The larger sink obtained more than its pro-rata share of 14C, usually more than the square of its size relative to the smaller sink. Partitioning between sinks of differing distance was in proportion to 1/d�, where d is the relative distance of the two sinks from the source. A sink on the opposite side of the ear received only one-tenth to one-thirtieth as much as a comparable sink on the same side as the source and the competing sink.

Effect of Relative Size and Distance of Competing Sinks on the Distribution of Photosynthetic Assimilates in Wheat

1978 ◽  
Vol 5 (4) ◽  
pp. 495 ◽  
Author(s):  
MG Cook ◽  
LT Evans
Keyword(s):  
Flag Leaf ◽  
Relative Size ◽  
Experimental System ◽  
Common Source ◽  
Storage Organ ◽  
Significant Bias ◽  
Sink Size ◽  
Stem Reserves ◽  
Unambiguous Conclusion

The objective of these experiments was to examine to what extent the size of a storage organ influences its ability to compete for a limited supply of assimilate. The experimental system consisted of wheat plants reduced to one main source of current photosynthate, usually the flag leaf of the main stem, and two main competing sinks, the ears of the first two tillers. The size of the two sinks was varied by the differential removal of grains 9 days after anthesis to give competing sinks comparable in every way except in the number of grains. 14C was assimilated by the flag leaf 2 days after grain removal, and its distribution determined after a further 2 days. When the relative size of the two sinks was varied, the grains in the larger sink received more than their pro rata share of 14C-labelled assimilate from the flag leaf, the bias in favour of the larger sink increasing with increase in its relative size. Grain growth in the smaller sink depended to a greater extent on local sources of assimilate, from ear photosynthesis and stem reserves. The more completely ear photosynthesis was inhibited by DCMU the less was the advantage of the larger sink in securing flag leaf assimilates but, even under the most severe competition, there was a significant bias in favour of the larger sink. Reserve carbohydrates in the stem could not be completely eliminated although they were greatly reduced by early defoliation and inhibition of photosynthesis. Their presence precluded an unambiguous conclusion as to the role of sink size in the competition for assimilates from a common source. Relative distance of the competing sinks from the source was varied by using one of the three uppermost leaves on one tiller as the source of labelled assimilate. Proximity to source conferred a marked advantage, and greater sink size was particularly important in securing assimilates from distant sources.

Relative-size Magnification versus Relative-distance Magnification: Effect on the Reading Performance of Adults with Normal and Low Vision

1998 ◽  
Vol 92 (7) ◽  
pp. 433-446 ◽  
Author(s):  
Jan Lovie-Kitchin ◽  
Steve Whittaker
Keyword(s):  
Low Vision ◽  
Relative Size ◽  
Reading Performance ◽  
Relative Distance ◽  
Normal Vision ◽  
Optical Correction ◽  
Character Size ◽  
Print Size ◽  
Reading Distance ◽  
Magnification Effect

In the study reported here, the effect of character size on the reading rates of adults with normal and low vision was measured using both relative-size magnification (by which the print size is increased) and relative-distance magnification (by which the reading distance is decreased with appropriate optical correction). With relative-distance magnification, the reading rates of the subjects with normal vision were slower at close distances, but the results were small and inconsistent. For the subjects with low vision, the magnification method did not affect their reading rates.

scholarly journals Corporate Takeovers in Malaysia: The Determinants of Financing Decision

2016 ◽  
Vol 23 (02) ◽  
pp. 38-60
Author(s):  
Kien Cao Dinh ◽  
Thuy Nguyen Thu ◽  
Ha Ngo Thi Thu
Keyword(s):  
Relative Size ◽  
High Technology ◽  
Payment Method ◽  
Financial Leverage ◽  
Credit Constraint ◽  
Corporate Takeovers ◽  
Factors Influencing ◽  
Acquiring Firms ◽  
Potential Factors

In this article we examine the role of potential factors influencing the choice of payment method in takeover transactions of Malaysian acquirers. We document that the financial leverage, the size of acquiring firms, the relative size of the transactions to acquiring firms, and the high technology status of the targets are key determinants to explain the methods of payment in their transactions. Moreover, the acquirers are found to be able to use equity to finance their foreign M&A transactions during the credit constraint periods.

scholarly journals Geometric factors influencing the diet of vertebrate predators in marine and terrestrial environments

2014 ◽  
Vol 17 (12) ◽  
pp. 1553-1559 ◽  
Author(s):  
Chris Carbone ◽  
Daryl Codron ◽  
Conrad Scofield ◽  
Marcus Clauss ◽  
Jon Bielby
Keyword(s):  
Factors Influencing ◽  
Geometric Factors ◽  
Terrestrial Environments ◽  
Vertebrate Predators

Geometric factors influencing dosimetric sparing of the parotid glands using IMRT

2006 ◽  
Vol 66 (1) ◽  
pp. 296-304 ◽  
Author(s):  
Margie A. Hunt ◽  
Andrew Jackson ◽  
Ashwatha Narayana ◽  
Nancy Lee
Keyword(s):  
Parotid Glands ◽  
Factors Influencing ◽  
Geometric Factors

III. Autoradiographisches Auflösungsvermögen

1968 ◽  
Vol 23 (11) ◽  
pp. 1478-1495 ◽  
Author(s):  
S. Bleecken
Keyword(s):  
Signal To Noise Ratio ◽  
Theoretical Treatment ◽  
General Validity ◽  
Basic Model ◽  
Maximum Resolution ◽  
Factors Influencing ◽  
Geometric Factors ◽  
Optimal Value ◽  
Quantitative Manner ◽  
Resolution Problem

A resolution criterion of general validity is given, and the dependence of autoradiographic resolution on all essential parameters is calculated.The effects of geometric factors (thickness of the emulsion, thickness, size, and number of radioactive objects, and the interspace between the emulsion and the object) and of beta energy on resolution are described first, with the simplifying assumption of linear autoradiographic transfer.The totality of factors influencing resolution can be understood only by considering nonlinear autoradiographic transfer. Here the exposure, the properties of emulsion (sensitivity; maximum number of grains per unit volume of emulsion; diameter of grains; background grain density) and the conditions of observation (autoradiographic “signal-to-noise ratio”; area of measurement) are considered. Increasing the exposure leads to an optimal value of autoradiographic resolution at the beginning of nonlinear transfer; overexposure decreases resolution again.The maximum resolution equals twice the diameter of grains. This parameter is not contained in the basic model and must be considered separately.This theoretical treatment of the resolution problem explains the experimental results quoted in literature in at least a semi-quantitative manner. Possible improvements of the model are discussed.

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