Horizontal Growth Rate Research Articles

FC3 Assessment of growth rate of melanomas based on sequential dermatoscopic images

Introduction The aim of this study was to estimate the average growth rate of cutaneous melanomas in comparison with melanocytic nevi. Methods Matched-pairs case-control study. Morphometric analyses of sequential dermatoscopic images. 59 patients with 63 primary melanomas were included. Sequential images of melanocytic nevi as controls were available for 55 melanomas. The main outcome measure is the average growth rate (mm2) per month. Results The mean patient's age was 50.2 years (SD±15.8). Thirty-five (55.6%) melanomas were invasive. The mean monthly growth rate of melanomas (n=63) was 0.43 mm2 (SD±0.9) with a mean relative increase of size of 33.7% (SD±50.2). For melanomas the average size at baseline was 25.6 mm2 (SD±14.5) and 32.0 mm2 (SD±16.7) after follow-up (P<0.01). The mean monthly growth rate for melanoma in situ was 0.25 mm2 (SD±0.7) and 0.58 mm2 (SD±1.0) for invasive melanomas (P=0.15). There were no significant correlations between mean monthly growth rate and age of patient, anatomic site, and size of the melanoma at baseline. The mean increase of size was significantly higher for melanomas than for nevi. Conclusions Melanomas are growing significantly faster than nevi of the same patient. The average horizontal growth rate of melanoma was 0.43 mm2 per month, which is lower than expected, and supports the hypothesis that the growth rate of melanoma is not linear.

Characteristics of sprite and gravity wave convective sources present in satellite IR images during the SpreadFEx 2005 in Brazil

Abstract. We developed a technique to identify and estimate the size, intensity, and Tropopause overshoot of thunderstorm convective cores expected to be significant sources of gravity waves. The work was based on GOES IR images of South America on the night of 30 September to 1 October and 25–26 October 2005, as part of the Spread F Experiment (SpreadFEx) in Brazil in 2005. We also characterized, for the first time, the convective activity of three small TLE producing thunderstorms that yielded 11 TLEs on 25–26 October 2005. The campaign occurred during the dry to wet season transition in central Brazil, marked by the presence of extra-tropical cyclogenesis over the Atlantic Ocean, and cold fronts penetrating inland. The Tropopause temperature was typically −76°C with a corresponding altitude of ~15 200 m. Vigorous convective cores capable of generating strong gravity waves were located in convective regions having areas with cloud top temperatures ≤−76°C. They had typical cloud-top temperature deficits of ΔT−2.0°C to −8.0°C from the average surroundings, implying overshoot heights of 200 to 3100 m, which are within the typical range. Fast vertical development and high horizontal growth rates were associated with a large number of simultaneously active vigorous convective cores, indicating that their dynamics may have determined the spatial-temporal development of the thunderstorms analyzed. Moderate convective cores were also present in areas with cloud top −76°C≤T≤−70°C. They had ΔT of −1.9°C to −5.3°C producing overshoots between 80–300 m. All convective cores had typical diameters of 5–20 km and their size tended to increase with ΔT, there was a 57% correlation between the two parameters. Analysis of the relationship of cloud top T with positive and negative cloud-to-ground lightning (+/−CG) occurrence rate and with peak current showed that lighting activity may provide an independent way to identify convective cores and measure their intensity, since they were characterized by a high incidence of low peak current −CGs that forms the bulk of the −CG population.

Sensitivity of African easterly waves to boundary layer conditions

Abstract. A linearized version of the quasi-geostrophic model (QGM) with an explicit Ekman layer and observed static stability parameter and profile of the African easterly jet (AEJ), is used to study the instability properties of the environment of the West African wave disturbances. It is found that the growth rate, the propagation velocity and the structure of the African easterly waves (AEW) can be well simulated. Two different lower boundary conditions are applied. One assumes a lack of vertical gradient of perturbation stream function and the other assumes zero wind perturbation at the surface. The first case gives more realistic results since in the absence of horizontal diffusion, growth rate, phase speed and period have values of 0.5 day−1, 10.83 m s−1 and 3.1 day, respectively. The zero wind perturbation at the surface case leads to values of these parameters that are 50 percent lower. The analysis of the sensitivity to diffusion shows that the magnitude of the growth rate decreases with this parameter. Modelled total relative vorticity has its low level maximum around 900 hPa under no-slip, and 700 hPa under free slip condition.

Revelation of nuclear tracks and dislocations: A Monte Carlo simulation of mineral etching

A simple atomistic Monte Carlo simulation suggests that there are up to four stages in the evolution of an etch pit in the (0 0 1)-surface of an idealised regular lattice. During the first stage, the etch pit is an inverted pyramid; its horizontal and vertical dimensions increase at a constant rate; the apparent horizontal ( v h) and vertical ( v d) growth rates are faster than during all subsequent stages but nevertheless less than the step retreat rate ( v s) on account of surface etching ( v v). The pyramid apex is truncated in the second stage; it is thereafter bounded by an expanding bottom plane and shrinking lateral walls; this is accompanied by a gradual decrease of v h; v d drops to a negative value indicating a slow decrease of the etch-pit depth; the bottom plane acquires a concave-up curvature; the outward curvature of the walls, initiated during the first stage, increases. During the third stage the etch pit consists of a single concave-up bottom plane; v h and v d decrease at declining rates; consecutive etch-pit profiles are scalable in the horizontal direction. The hypothetical fourth stage is inferred but not documented by the simulations; it sets in when v h is reduced to zero; unless this corresponds to an as yet unidentified steady-state condition, the etch pit from here on forth shrinks until it eventually disappears altogether. The sole cause for this succession is the process of stochastic rounding of confined steps and faces. The triangular footprint of recoil-track, fission-track, ion-track and dislocation etch pits in trioctahedral mica and its compliance with the monoclinic symmetries implies that the relevant periodic bond chains are O–Mg/Fe–O chains in the octahedral layer. The size distribution of etched recoil tracks is due to (1) depth variations resulting from the size distribution of the latent tracks, (2) the random truncation of the surface tracks, (3) the variable rate of etch-pit enlargement and (4) the fact that new tracks are exposed at the surface due to surface etching. The greater size of dislocation, fission-track and ion-track etch pits is due to their greater extent below the surface. The increase of the number of etched tracks with etching time due to bulk etching is non-linear because the bulk etch rate v v is not constant. The evolution of etch-pit shape with continued etching can also cause loss of tracks due to observation effects related to loss of contrast.

Three-dimensionalization of freely-decaying two-dimensional turbulence

The three-dimensionalization of freely-decaying two-dimensional turbulence is studied numerically. Using two different basic states, it is shown that the hyperbolic instability of steady mixing layers generalizes to unsteady flow. The growth of three-dimensional (3D) perturbations is interpreted in terms of a “pressureless” analysis in which horizontal pressure gradients are neglected and the underlying physical mechanism is advective in nature. For a steady, pressureless base flow the (asymptotic) growth rate is exactly determined, in a few special cases, by variants of the so-called Weiss criterion; more generally, local growth rate estimates are obtained. For freely-decaying two-dimensional turbulence there is analogous behavior: while the 3D perturbation remains small the pressureless approximation holds at large horizontal scales and local growth rate estimates apply. The pressureless modes have a determining influence on the growth (the damping effect of the horizontal pressure gradient is small).

Horizontal transport and dispersion in the surface layer of a medium‐sized lake

Lagrangian GPS drifter experiments, carried out in the surface layer of stratified Lake Kinneret (Israel), are presented. Differential kinematic properties and Lagrangian statistics were calculated and used to estimate the dominant mechanisms for horizontal dispersion. On time scales smaller than a few internal wave periods, internal waves lead to strong divergence and convergence events, causing instantaneous apparent horizontal growth rates that were larger, by up to an order of magnitude, than the actual mean dispersion coefficient. It is shown that the internal wave field modulated the vorticity field so as to satisfy conservation of potential vorticity. On time scales larger than a few internal wave periods, unbounded horizontal shear dispersion was of the same order as the actual mean observed dispersion coefficient (Kxy = 17.1 m2 s−1), while vertical shear dispersion was negligible.

Growth rate of melanoma in vivo and correlation with dermatoscopic and dermatopathologic findings

Objectives: The aim of this study was to calculate the horizontal growth rate of melanoma in vivo and to correlate it with morphologic findings.&#x0D; Patients and Methods: We searched our database for melanomas for which sequential dermatoscopic images and histopathologic slides were available. The final sample consisted of 50 melanomas of 48 patients (mean age: 50 ± 15 years, 62% females). We calculated the horizontal growth rate in mm2 per year by morphometric analysis of digital dermatoscopic images. Dermatoscopic and dermatopathologic findings were assessed according to predefined criteria and correlated with the horizontal growth rate.&#x0D; Results: The median time interval between baseline and follow-up image was 12 months (range: 2-100 months). The majority of melanomas were in situ (n=28, 56%). The mean horizontal growth rate of all melanomas was 5.3 mm2/year (SD: ± 5.8 mm2/year). The histopathologic findings of numerous and large epidermal nests were associated with rapid growth. This histopathologic pattern corresponded to a pattern of clods (“globules”) dermatoscopically. From a dermatoscopic point of view, melanomas with a main pattern of clods grew significantly faster (mean horizontal growth rate: 10.4 mm2/year, 95% CI: 6.4-14.4 mm2/year) than melanomas with mainly a reticular pattern (4.8 mm2/year, 95% CI: 2.7-7.0 mm2/year) or with other patterns (2.6 mm2/year, 95% CI: -0.5-5.6 mm2/year, p=0.01).&#x0D; Conclusion: Morphologic characteristics of melanoma are associated with biologic behavior. Large and numerous epidermal nests (corresponding to a pattern of clods dermatoscopically) indicate more rapid growth.

Mapping and Monitoring of Submerged Aquatic Vegetation in Escambia-Pensacola Bay System, Florida

Recently, the distribution and changes in submerged aquatic vegetation (SAY) in the Escambia-Pensacola Bay System in northeastern Florida were monitored by two techniques. One technique used divers to measure changes in the deepwater margin of beds and provided horizontal growth measurements to the nearest centimeter, the other used a differential global positioning system (DGPS) on a small boat to map the perimeter of SAY beds in shallow water. Current distribution of SAY in Escambia Bay shows that most of the SAY losses that occurred during the 1950s to 1970s have been recovered. In Santa Rosa Sound and Pensacola Bay, SAY showed significant increased growth with horizontal growth rates of some beds averaging more than 50 em over the past year. In Big Lagoon, however, SAY has declined an average of 10 em in horizontal coverage along the deepwater edge. Water quality and photosynthetically active radiation light measurements from the Escambia-Pensacola Bay System suggest that increased light availability was associated with the increased seagrass coverage in Santa Rosa Sound and Pensacola Bay, and elevated nutrient concentrations were associated with the seagrass declines in Big Lagoon.

Lateral growth of focused ion beam deposited platinum for stencil mask repair

Focused ion beams can repair conventional lithography masks through milling and deposition. Repairs to stencil masks for ion projection lithography present a greater challenge than conventional mask repair, as the standard model of ion induced deposition requires a surface for deposition to take place. In a stencil mask, a bridge must be formed across the open area, anchored to the mask on either side of a slot. Focused ion beam deposition can induce such horizontal growth of material. Ion-induced growth of platinum over slots up to 3 μm wide in a 2.75 μm silicon membrane is demonstrated for an average beam current density of 7 mA/cm2. The primary method used to accomplish this is by scanning the focused ion beam in a rectangular pattern that extends over the slot. Material is built up from the edges, and grows inwards to span the slot and form a bridge. The direction of gas flow is an important consideration. When gas flow is perpendicular to the slot, the downstream side of the bridge will grow much faster than the upstream side. Gas flow parallel to the slot results in uniform growth from both sides. Platinum deposition was not found to be gas flow limited within the deposition parameters used. The horizontal growth as a function of time was measured, and found linear. The slope of this line is the horizontal growth rate, 23±0.05 nm/s. The x intercept of this line yields the minimum time for deposition to begin, which is 5.96±0.11 s. Sample bridges were deposited, and trimmed of excess material and redeposited platinum. These are presented as examples that uniformly wide bridges may be obtained at submicron dimensions, both in simple spanning and zig-zag configurations.

Fabrication of nano-size conic diamond arrays by bias assisted PCVD

Abstract This study successfully fabricates gate conic diamond field emission arrays on the Si wafer utilizing a two-step deposition method by bias-assisted microwave plasma chemical vapor deposition (BAMPCVD) system. The 4 inch n-type silicon wafer is used as the substrate. In addition, a set of arrays of circular patterns (8 μm radius) is exposed using a micro-electronic technique. The conic diamonds are deposited in the patterns as well. Experimental results indicate that the negative bias voltage improves the conic diamond's density and shape. Various methane concentrations also affect the conic diamond's quality, size, growth rate and I–V characteristics. Restated, the amorphous carbon increases with an increasing methane concentration, thereby enhancing the emission current as well. Moreover, with the various methane concentrations, the vertical and horizontal growth rates differ from each other. Furthermore, the horizontal growth rate is faster than the vertical one when increasing the methane concentration. Owing to this reason, the radius of conic diamond's apex can be increased with an increasing methane concentration.

An ancient eelgrass clone in the Baltic

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 183:301-304 (1999) - doi:10.3354/meps183301 An ancient eelgrass clone in the Baltic Thorsten B. H. Reusch1,*, Christoffer Boström2, Wytze T. Stam1, Jeanine L. Olsen1 1Department of Marine Biology, University of Groningen, PO Box 14, 9750 AA Haren, The Netherlands 2Husö Biological Station, Åbo Akademi University, FIN-22220 Emkarby, Åland Islands, Finland *Present address: Max-Planck-Institut für Limnologie, August-Thienemann-Str. 2, D-24306 Plön, Germany. E-mail: reusch@mpil-ploen.mpg.de ABSTRACT: We report that an eelgrass bed Zostera marina L. at the Åland Islands, northern Baltic Sea, is dominated by a single genotype which extends over an area of approximately 160 x 40 m. In total, 47 individuals were sampled and genotyped for 6 highly polymorphic microsatellite loci. Forty-four of the ramets revealed the same 6-locus genotype, including 3 identical heterozygous loci. They were thus assigned to the same genet (= clone). To our knowledge, it represents the largest marine plant identified thus far. Based on estimates of horizontal rhizome growth rates, this clone may be more than 1000 yr old. The remarkable phenotypic plasiticity of a single genotype which dominates this site illustrates that there is no simple one-to-one relationship between genetic diversity and population persistence in changing and stressful environments. KEY WORDS: Baltic Sea · Clonal reproduction · Eelgrass · Genet · Microsatellites · Ramet · Zostera marina Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 183. Publication date: July 06, 1999 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1999 Inter-Research.

Singular vectors and estimates of the analysis‐error covariance metric

AbstractAn important ingredient of ensemble forecasting is the computation of initial perturbations. Various techniques exist to generate initial perturbations. All these aim to produce an ensemble that, at initial time, reflects the uncertainty in the initial condition. In this paper a method for computing singular vectors consistent with current estimates of the analysis‐error statistics is proposed and studied. The singular‐vector computation is constrained at initial time by the Hessian of the three‐dimensional variational assimilation (3D‐Var) cost function in a way which is consistent with the operational analysis procedure. The Hessian is affected by the approximations made in the implementation of 3D‐Var; however, it provides a more objective representation of the analysis‐error covariances than other metrics previously used to constrain singular vectors.Experiments are performed with a T21L5 Primitive‐Equation model. To compute the singular vectors we solve a generalized eigenvalue problem using a recently developed algorithm. It is shown that use of the Hessian of the cost function can significantly influence such properties of singular vectors as horizontal location, vertical structure and growth rate. The impact of using statistics of observational errors is clearly visible in that the amplitude of the singular vectors reduces in data‐rich areas. Finally, the use of an approximation to the Hessian is discussed.

Within population genetic differentiation in traits affecting clonal growth: Festuca rubra in a mountain grassland

Abstract Festuca rubra , a clonal grass of mountain grasslands, possesses a considerable variability in traits related to spatial spreading (rhizome production, length and branching; tussock architecture). Since these traits highly influence the success of the species in a spatially heterogeneous system of grasslands, a combined field and growth chamber approach was adopted to determine the within‐population variation in these parameters. Clones were sampled in a mountain grassland (The Krkonoše Mts., Czech Republic); the environment (mean neighbour density) of individual clones varied highly. Before the clones were collected, shoot demography and tussock architecture within these clones were recorded in the field for four seasons. Their clone identity was determined using DNA RAPD. Vegetatively propagated plants from these clones were cultivated in a common garden experiment to demonstrate variation in tussock growth and architecture. Their response to change in red/far red light ratio was determined in the growth chamber.Highly significant variation among clones was found in almost all parameters. In the common garden, the clones differed in tussock growth (mean tillering rate), architecture (mean shoot angle, mean tussock density) and proportion of flowering shoots. In the growth chamber, both the aboveground parameters and parameters of the rhizome system were strongly affected by red/far red ratio; among‐clone variation was also almost always significant. The genotype × environment interaction was significant for tillering rate and rhizome architecture. The structure of the rhizome system (which is the major component of clonal spread in space) is a complex result of several components whose inter‐clone variations differ: (i) genetically determined mean rhizome system size, (ii) overall plasticity in rhizome system size (with no significant genetic variation in plasticity), and (iii) genetically determined plasticity in rhizome architecture. Because of the variation in plasticity in rhizome architecture, some c lones seemed to possess the ability to exploit a favourable habitat patch by producing short branches when there; whereas the remaining clones appeared to possess only a simple escape mechanism from unfavourable patches.Environmental variation in the light levels in the studied grassland is fine grained; horizontal growth rates of F. rubra are sufficient to make genets experience different patches in their lifetime. The high variation in both genotype means and plasticities is likely to be due to selection early in genet life in an environment which is heterogeneous at a fine scale.

Growth and population dynamics of Thalassodendron ciliatum in a Kenyan back-reef lagoon

The size, rhizome growth, and demography of a Thalassodendron ciliatum (Forssk.) den Hartog population in a back-reef lagoon (Chale lagoon, Kenya), was examined using techniques based on age determinations. The results obtained reveal that vertical growth of the T. ciliatum shoots is very fast, involving the production of, on average, 42 internodes (i.e. 42 leaves) per year. Annual length increments declined from young shoots (17 cm year −1) to older shoots (6 cm year −1). Vertical growth is not constant over the year with internodal length sequences suggesting the presence of two adverse periods for vertical growth in a year. As a result, the T. ciliatum population allocated a significant fraction of their biomass production (31%) to upright stems, which can grow for up to 5 years (the maximum life span of vertical shoots). The vertical growth of this species is the fastest reported to date for an undisturbed seagrass population, whereas the horizontal growth rates (16 cm year −1) rank amongst the slowest. The turnover time of the shoots was about 1 year (i.e. the median shoot life span), with shoot mortality and recruitment maintaining a close balance (0.71 ± 0.04 natural log units year −1 and 0.65 natural log units year −1, respectively), indicating that the population is in a steady state condition. Because horizontal rhizome growth was slow (producing six shoots per rhizome apex year −1), shoot recruitment through branching of vertical shoots (20% of the vertical shoots bearing branches) is an important component of clonal growth of this population. These results demonstrate that vertical growth is an essential component of the production of T. ciliatum, to which it allocates considerable resources. This allocation is used to raise the photosynthetic tissues well above the sediments, thereby preventing competition with other benthic phototrophs. It also guarantees sufficient shoot recruitment for maintenance of the population.

Forest gap formation and closure along an altitudinal gradient in Tongariro National Park, New Zealand

Abstract24 treefall gaps accumulated over a 10 year period along an altitudinal transectcovering 4.6ha on Mt. Hauhungatahi, Tongariro National Park, New Zealand were described quantitatively in terms of the area of damage (‘expanded gap’), the canopy opening (‘Tight‐gap’) and the size of the root mound. Tree mortality and branch loss following cyclone Bola, 1988, were recorded. In each gap saplings were ranked by species according to their vigour. Pre‐gap and post‐gap vertical and horizontal branch growth rates were calculated. Effects in the subalpine forest (&gt; 1050 m) were compared with those in the montane zone.Tree mortality was highly episodic, associated with major storms, and patchy. Falling canopy trees destroyed, on average, 1.3 additional trees (&gt; 10 cm diameter at 1 m). About half the trees were uprooted and the remainder broken off. Uprooted angiosperm (canopy) trees frequently resprouted from their bases, gymnosperms rarely. Expanded gap area averaged 56 m2 in the sub‐alpine forest and 88 m2 in the montane zone. Median expanded gap areas were about twice those of light gaps. Gap size frequency distribution was highly skewed. The largest gap was formed by a single Dacrydium cupressinum which destroyed six other trees creating a gap of ca. 0.03 ha.Expanded gaps, light gaps, and root mounds comprised 4.5, 2.8 and 0.1 % of the forest area in the sub‐alpine zone, and 3.8, 2.5 and 0.06 % in the montane forest. These values represent 10 years of accumulation, and imply light gap ‘return times’ of 360 years for the sub‐alpine and 400 years for the montane forest. These periods are in agreement with the known longevities of the canopy and emergent trees.Vertical shoot growth rate was about twice that in the horizontal plane, and both increased following gap formation. The relative increase was greatest in the subalpine forest. Using the measured growth rates it is estimated that gaps of median dimensions are filled by lateral extension growth in 31–44 yr. Saplings require longer to reach the mean canopy height and consequently require large (multiple tree) gaps or sequential gap events.

A new method for estimating horizontal growth of the peat mat in basin-filling peatlands

A newly developed technique was used to determine the long-term horizontal growth rate of the peat mat in Fallison Bog, a poor fen in northern Wisconsin. This technique consisted of carbon-dating material that was alive when the lake edge was at a particular location in the peatland and then measuring the distance from that location to the current lake edge. In Fallison Bog, Chamaedaphne calyculata stems currently buried at the mat peat – debris peat interface were alive when the lake edge was at that horizontal location. Radiocarbon dates of stem material from six locations in the peatland were used to estimate when the lake edge was at each location. To calculate the average long-term horizontal growth rate, the slope of the least-squares linear regression of distance from lake edge versus age of stems was computed. The estimated rate in Fallison Bog was 2.5 cm/year (95% confidence interval was 1.6–3.5 cm/year). The linear regression explained 95.6% of the variance in the data. The author suggests that this technique may be applicable in peatlands bordering acid lakes throughout northeastern North America.

Growth rates ofLithophyllum incrustans(Corallinales, Rhodophyta) from South West Wales

Growth rates of Lithophyllum incrustans, a rock-encrusting coralline red alga, have been studied at three sites on the coast of Pembroke, south-west Wales. Horizontal and vertical growth rates and calcium carbonate deposition rates were determined. There are some significant differences between sites, especially in vertical growth rates which include the formation of reproductive tissue. The data indicates that L. incrustans is, on average, 2·25 years old before reproduction is initiated. Growth rates of this alga were found to be similar to other arctic and temperate encrusting red algae, but an order of magnitude less than those in the tropics.

Intrabeam scattering at high energies

The growth of a beam of charged particles due to intrabeam scattering is studied in the high energy limit. The variation of the β-functions and the dispersion around the accelerator are included. In the high γ limit, analytical results are found for the horizontal, vertical and longitudinal growth rates. For a lattice consisting only of regular cells, with no insertions, a time invariant is found and the longitudinal and transverse growth rates are simply related. The dependence of the final state of the beam on the final energy is also studied.

Carbonate production of the coral Diploria labyrinthiformis in south Florida patch reefs

Average annual production of CaCO 3 (aragonite) by the hermatypic coral Diploria labyrinthiformis in the Florida reef tract is 11.8 ± 0.3 kg/m 2 of reef space occupied by the coral. Annual production was estimated from a population of 271 Diploria colonies measured in situ. The mass produced annually is the volume of annual growth times the skeletal density. Cores of thirty-one Diploria colonies were slabbed and X-rayed to reveal annual growth bands. The mean vertical growth rate is 0.35 ± 0.06 cm/yr for skeletal density bands representing up to 34 years of growth. The annual volume of growth is approximated by a simple geometric shell whose thickness is determined by the horizontal and vertical growth rates of the colony. Horizontal growth rates are estimated from the ratio of the two lateral axes to the vertical axis. Bulk density determined by dry weight/volume of 9 cyclindrical cores is 1.64 ± 0.13 g/cm 3. Productivity of 11.8 kg/m 2/yr for area occupied by the coral does not vary appreciably among a nearshore patch reef and two outer-shelf patch reefs. For comparison, production rates for 244 Porites astreoides near Key West, Florida, is 14 ± 3.3 kg/m 2/yr for area occupied by the coral. The 271 colonies of D. labyrinthiformis potentially produce sediment which, if spread evenly, would accumulate at a rate of 0.026 m/10 3 yr for 9008 m 2 of reef surveyed. Potential vertical accretion by all corals for the patch reef surveyed is estimated at 2.2 to 6.6 m/10 3 yr.

Free convection about a rectangular prismatic crystal growing from a solution

Sodium chlorate crystals growing from unstirred aqueous solutions were observed by schlieren techniques. Growth rate data were best correlated by Sh = 0.48 Ra 0.25 with finite interface kinetics and a characteristic length L equal to the crystal height plus the inverse reciprocal sum of the horizontal dimensions. The growth rate was slightly higher when the plume was laminar than when it was irregular. The horizontal growth rate was greater than the vertical growth rate, with the ratio tending to decrease with increasing plume instability. The threshold Grashof number for plume instability was greatly decreased with decreasing height for crystals with the same horizontal dimensions. The frequency of eddy emission was proportional to L −2 Ra 0.8. The velocity of the eddies approached a constant value with increasing distance above the crystal surface, the terminal value being roughly proportional to Ra 1 2 /L .