Rate Of Increase In Diameter Research Articles

A Contribution to the Life History of the Rare Indonesian Holoparasite Rafflesia patma (Rafflesiaceae)1

Fates and growth of Rafflesia patma buds and insect visitation to the flowers were monitored in an evergreen tropical rain forest in the Pangandaran Nature Reserve, Java, Indonesia. Of 59 buds marked in December 1985, 44 percent died before flowering, 7 percent flowered, and 49 percent were still in bud in May 1986. Mammals and birds caused the deaths of buds before they reached maturity. Only four buds flowered between December 1985 and May 1986; all were male. Rate of increase in diameter (cm/d) was much faster in large than in small buds. Once opening began, the flower opened fully in 24 to 48 hours; the flower remained open for three to five days before rotting. Only two genera of insects visited a male flower of R. patma: Lucilia and Sarcophaga (Diptera). Insect visitation was highest in the afternoon (1300–1700 h) and on the second or third day after flower opening. The increased number of flies visiting the flower coincided with the increasing odor emitted from it. Results of the present study were combined with information from the literature to construct a life cycle diagram of R. patma.

Polarized light scattering for rapid observation of bacterial size changes

The effect of changing growth conditions on the diameter of rod-shaped bacteria was studied in vivo with the use of polarized light scattering. The value of a ratio of scattering matrix elements was measured as a function of scattering angle at various times after nutritional "upshift" for two strains of Escherichia coli cells. The peak locations of the scattering function were calibrated against the diameter for rod-shaped bacteria. The peaks moved toward smaller angles as a function of time after upshift, indicating that the diameter was increasing. Under special conditions, substantial peak shifts occurred within a few minutes of growth condition change, indicating a rapid onset of growth in diameter. The rate of increase of the diameters after upshift was obtained from the angular shift of peak location. This rate was approximately 14 nm/min for E. coli K12 and approximately 9 nm/min for E. coli B/r at 37 degrees C. The rate of diameter increase is smaller at lower temperatures. Experiments with Bacillus megaterium showed that any diameter change after nutritional upshift at 37 degrees C is limited to at most a very small increase, at least for the strain and medium tested.

Distinct mechanical relaxation components in pairs of erythrocyte ghosts undergoing fusion

It was previously reported (Chernomordik and Sowers, 1991) that erythrocyte ghosts which were exposed to a 42 degrees C, 10-min heat treatment would, upon electrofusion, produce over 15-20 s a fusion product with an "open lumen" (i.e., the fusion product became converted to one large sphere), while electrofusion of ghost membranes not so exposed would lead to chains of polyghosts. In phase optics the chains of polyghosts showed a "flat diaphragm" at virtually every ghost-ghost junction (i.e., the ghosts do not appear to be fused even though fluorescent-labeled lipid analogs can laterally diffuse from a labeled ghost to an adjacent unlabeled ghost). In the present study we found that the diameter increase in open lumen- and flat diaphragm-producing fusion processes both had a rapid but short early phase (0-5 s after fusion) which was exponential or nearly so and a slow but long late phase (5-120 s after fusion) which was essentially linear. Heat treatments at 39 or 42 degrees C caused a minor acceleration in only the late phase, while temperatures of 45 or 50 degrees C caused an immediate and dramatic acceleration in the rate of diameter increase (spheres in 1-2 s). Ghost membranes in the presence of glycerol at 20% (v/v) did not form open lumens when exposed to the 42 degrees C (but not the > or = 45 degrees C) heat treatment. This suggested that the heat treatment was denaturing a critical protein. Both of these observations are consistent with the involvement of the spectrin network since it is the only protein in the erythrocyte membrane which is known (Brandts et al., 1977) to have a calorimetric transition over the same temperature range used in our heat treatments. The diameter versus time curves were sensitive to: (i) the residual effects of the fusogenic electric pulse only up to about 1 s after the pulse, (ii) the strength of the dielectrophoretic field after the pulse, but not before the pulse,(iii) the ambient temperature during the measurement.

Study of directional crystallization process in a cold container with direct radio-frequency heating

The growth process of cubic zirconia crystals by the directional crystallization technique in a cold container was examined. It was found that the rate of increase in diameter of crystals of preferred orientation during growth of the crystalline aggregate depends on the value of the density of power absorbed by the melt at the beginning of crystallization, which determines the axial thermal gradient in the melt. This effect is in accordance with the theory developed by Tiller regarding the growth mechanism in the grooves formed at the interfaces between growing crystals. Under equivalent conditions, the axial thermal gradient determines the depths of the grooves, which in turn controls the rate of displacement of some crystals by others.

Growth rates of glasshouse tomato fruit in relation to final size

The individual growth rates of the first five tomato fruits on 25 trusses of similar age within a crop grown in commercial glasshouse conditions were assessed from anthesis to ripening during April and May. Final size of fruit at ripening was proportional to the maximum rate of increase in fresh weight, about 40 d after anthesis, and related to the maximum rate of increase in diameter, between 15 and 20 d after anthesis, even though ripe fruit fresh weight varied from 20 g to over 100 g. On any one truss these fruit ripened within the same week, regardless of fruit size and prevailing growth rate. These findings suggest that final size was related to the peak fruit growth rate rather than the duration of development. A high growth rate late in development did not delay fruit ripening. The implications for recent continuous measurements of the diameter growth rate in young fruit are discussed.

Growth rates of subclinical abdominal aortic aneurysms—implications for review and rescreening programmes

One hundred and six patients with abdominal aortic aneurysms (AAAs) of 2.5 to 3.9 cm in anteroposterior diameter were reexamined by ultrasound every 6 months for up to 3 years after diagnosis. Annual growth rates were 0.11 cm +/- 0.03 (mean +/- SE) for AAAs 2.5 to 2.9 cm and 0.29 cm +/- 0.08 for AAAs 3.5 to 3.9 cm (P = 0.002). In 73 patients (69%) the annual rate of increase in diameter was 0.2 cm or less and only 12 aneurysms (11%) grew at more than 0.5 cm per annum. We conclude that: (1) for AAAs less than 4.0 cm diameter remeasurement more often than every 6 months is unnecessary; (2) interval screening (rescreening) for AAAs more frequently than 5 yearly is unlikely to detect sufficient clinically significant aneurysms to be worthwhile.

Growth of surface colonies of the gliding bacterium Myxococcus xanthus.

1. Colonies of several gliding, semi-motile and non-motile strains ofMyxococcus xanthus demonstrate a constant rate of diameter increase. Colonies of motile strains, characterized by a predominance of cell swarms at the leading edges, expand more rapidly than those with single, gliding cells at their peripheries. 2. Colony growth rate is proportional to the growth rate of cells in shake culture and on agar and to the square root of nutrient concentration over a wide concentration range. The rate of colony growth is affected by temperature and by agar concentration and depth but not by hight nor gravity.