Moderate Growth Rate Research Articles

Mediterranean deep-water fish age determination and age validation: the state of the art

Studies on age and growth of deep-water fish in the Mediterranean have mainly centred on the macrourid fishes. Although in some studies length–frequency analysis has been carried out, the majority of studies have estimated age using annual increments in the sagittal otoliths. However, validation of the annual increments has been limited to a few studies involving the seasonal changes in the structure of the otolith margin. Most species reach relatively old ages of up to 30 years with moderate growth rates, except for the mesopelagic Lepidopus caudatus which has younger ages and a faster growth rate.

In-situ evaluation of the anodic oxide growth on Hg1−xCdxTe (MCT) using ellipsometry and second harmonic generation

In-situ measurements of ellipsometry and second harmonic generation (SHG) were carried out to monitor the electrochemical growth of native anodic oxide films on Hg1−xCdxTe (MCT). Growth of the anodic oxide was performed using two different methods viz., by linear sweep voltammetry and by applying a constant current density. The influence of scan rate and the magnitude of the applied current density on the properties of the growing films were examined. From the ellipsometry data, we have shown that the measured refractive index value of 2.19 for the oxide film remains unchanged for moderate and high oxide growth rates. Only at very slow growth rates were significant increases in the refractive index observed (n=2.4), indicating an increase in the compactness of the layer. For film thicknesses in excess of ∼1200 A, a non-zero value for the extinction coefficient was found, indicating the incorporation of HgTe particles within the anodic oxide film. SHG rotational anisotropy measurements, performed on the MCT with and without an anodic oxide film showed only the four-fold symmetry associated with the MCT and so confirmed that the oxide was centrosymmetric. However, an increase in the SH intensity was observed in the presence of the oxide and this has been attributed to multiple reflections in the thin oxide film and also to the increase in the χ(2) non-linear susceptibility tensor as a result of charge accumulation at the MCT/anodic oxide interface.

Relationship between Nutritionally-Mediated Placental Growth Restriction and Fetal Growth, Body Composition and Endocrine Status During Late Gestation in Adolescent Sheep

The aim was to investigate the consequences of nutritionally-mediated placental growth restriction on fetal organ growth, conformation, body composition and endocrine status during late gestation. Embryos recovered from superovulated adult ewes inseminated by a single sire were transferred in singleton to the uterus of peripubertal adolescent recipients. Post-transfer, adolescent dams were offered a high (H) or moderate (M) level of a complete diet to promote rapid or moderate maternal growth rates, respectively (n=7 per group). After day 100 of gestation the feed intake of the M dams was adjusted weekly to maintain body condition score. Liveweight gain during the first 100 days of gestation was 301±24 and 90±4.6g/day for the H and M groups, respectively. Maternal plasma concentrations of insulin, IGF-I and urea were significantly higher and non-esterified fatty acid concentrations significantly lower in H compared with M dams prior to slaughter on day 128 of gestation. At this stage of gestation, total placentome weight was 50 per cent lower in H compared with M groups (P< 0.001) and was associated with a 37 per cent reduction in fetal weight (P< 0.01). All variables of fetal conformation and absolute fetal organ weights, with the exception of the adrenal glands, were lower (P< 0.05) in the fetuses from H intake dams. However, relative fetal organ weights expressed as g/kg fetal body weight, with the exception of the gut, were not influenced by maternal dietary intake. Furthermore, fetal weight but not maternal nutritional group were predictive of individual organ weight for all organs dissected. Together these results imply that growth restriction in the fetuses derived from H intake dams was largely symmetrical. Fetal plasma concentrations of insulin, IGF-I and glucose were attenuated (P< 0.05) in fetuses from H compared with M groups. The lower fetal body weight in the former group was associated with a reduction in absolute but not relative crude protein (P< 0.01) and fat content (P< 0.05). Total fetal liver glycogen content but not concentration was (P< 0.05) reduced in H versus M groups. The lower mass of both the placenta and fetal liver was due to a reduction in cell number rather than an alteration in cell size. Thus, over-nourishing adolescent sheep is associated with a major restriction in placental growth which mediates a gradual slowing of fetal growth during the final third of pregnancy.

A prospective longitudinal study of urinary excretion of a bone resorption marker in adolescents

In growing subjects, the rates of bone resorption and bone deposition are substantially larger than in non-growing individuals. The purpose of this study was to measure the urinary excretion of a specific bone resorption marker in function of adolescent growth stages in a prospective longitudinal study. A cohort of 60 adolescents (28 male and 32 female) was followed for 3.4 years (range 1.7-4.6 years). Monthly measurements of height, weight and urinary excretion of a bone resorption marker, collagen type I N-telopeptides (NTx), were made. Changes in standing height were used to classify the adolescents into one or more of six adolescent growth stages: pre-pubertal growth (continuous moderate growth rate), ascending growth spurt (increasing growth rate), peak growth spurt (growth rate higher than 7cm/year for at least 6 months), descending growth spurt (continuous decrease in growth rate), end of growth (growth rate between 0 and 2cm/year), and no growth. An increase in NTx excretion from the pre-pubertal to peak growth spurt of about 33% was found (44% and 27% for females and males respectively). The decreasing growth rate after the pubertal growth spurt coincided with a clear decrease in NTx excretion. These differences were statistically significant, except between the prepubertal and ascending growth stage. Individual mean NTx excretion during each growth stage was correlated with the individual's growth rate during that time (r = 0.81). There was large inter-and intra individual variability. In non-growing adolescents (growth rate 0cm/y) NTx excretion levels were 4-7 times greater than in adults. In all females, menarche was followed by a decrease in NTx excretion. In conclusion, the excretion of a specific bone resorption marker, NTx, was correlated with the changes in growth rate during adolescence, both for males and females. There were large inter and intra-individual differences in NTx excretion during the different growth stages. In adolescents who reached their adult height at the end of the pubertal growth spurt, bone resorption decreased dramatically but remained 4-7 fold higher than in adults.

Switching maternal dietary intake at the end of the first trimester has profound effects on placental development and fetal growth in adolescent ewes carrying singleton fetuses.

The aim was to investigate whether placental growth and hence pregnancy outcome could be altered by switching adolescent dams from a high to a moderate nutrient intake, and vice-versa, at the end of the first trimester. Embryos recovered from adult ewes inseminated by a single sire were transferred in singleton to peripubertal adolescents. After transfer, adolescent ewes were offered a high (H, n = 33) or moderate (M, n = 32) level of a diet calculated to promote rapid or moderate maternal growth rates, respectively. At Day 50 of gestation, half the ewes had their dietary intakes switched, yielding 4 treatment groups: HH, MM, HM, and MH. A subset of ewes were killed at Day 104 of gestation to determine maternal body composition in relation to growth of the products of conception. Maternal body composition measurements revealed that the higher live weight in the high-intake dams was predominantly due to an increase in body fat deposition, with a less pronounced increase in body protein. At Day 104, HH and MH groups (high intake during second trimester) compared with MM and HM groups (moderate intake during second trimester) had a lower (p < 0.002) total fetal cotyledon weight; but fetal weight, conformation, and individual organ weights were not significantly influenced by maternal dietary intake. In ewes delivering live young at term, a high plane of nutrition from the end of the first trimester (HH and MH groups) compared with moderate levels (MM and HM groups) was associated with a reduction in gestation length (p < 0.009), total placental weight (p < 0.002), total fetal cotyledon weight (p < 0.001), and mean fetal cotyledon weight per placenta (p < 0.001). Fetal cotyledon number was dependent on maternal dietary intake during the first trimester only and was lower (p < 0.007) in HH and HM ewes compared to MM and MH ewes. The inhibition of fetal cotyledon growth in HH and MH groups was associated with a major decrease (p < 0.001) in lamb birth weight at term relative to the MM and HM groups. Thus, reducing maternal dietary intake from a high to a moderate level at the end of the first trimester stimulates placental growth and enhances pregnancy outcome, and increasing maternal dietary intake at this time point has a deleterious effect on placental development and fetal growth.

Adsorption of potassium onCr2O3(0001)at ionic and metallic coverages and uv-laser-induced desorption

Translational energy distributions of neutral potassium atoms are reported as a function of potassium coverage after uv-laser-induced desorption from well-characterized adsorption sites on an epitaxial film of ${\mathrm{Cr}}_{2}{\mathrm{O}}_{3}(0001)/\mathrm{C}\mathrm{r}(110).$ Measurements using x-ray photoelectron spectroscopy, low-energy electron diffraction, and work-function measurements revealed that potassium adsorbs in a nonmetallic phase for deposition temperatures around 280--300 K allowing only a maximal saturation coverage to be grown for moderate growth rates. Aggregates are observed after deposition at 90 K; at this temperature any layer thickness is obtainable. The uv-laser-induced desorption for these two different phases was studied using excitation energies of 3.5 eV, 5.0 eV, and 6.4 eV and $(1+1)$-resonantly enhanced multiphonon ionization via the $6p{}^{2}P$ state for detection. Desorption of potassium atoms from the nonmetallic phase proves to be ten times $[\ensuremath{\sigma}(6.4\mathrm{eV})=(2\ifmmode\pm\else\textpm\fi{}1)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}19}{\mathrm{cm}}^{2}]$ more efficient than desorption from metallic potassium aggregates. The mechanism of desorption from the nonmetallic phase appears to be the inverse harpooning process starting with an ion pair followed by a transfer of hot electrons from the substrate to unoccupied potassium states to neutralize the initially positively charged potassium. The maximum of the translational energy distribution (starting at 0.65 eV for low coverages) decreases with increasing potassium coverage and is by a factor of approximately 4 smaller for desorption from large potassium aggregates (0.16 eV). The decrease of the translational energy with increasing coverages for isolated atoms is ascribed to an increasing lateral interaction between the adsorbates and a concomittant smooth change of the ionicity of the atoms from partially ionic to neutral.

Resistance of a food chain to invasion by a top predator

We study the invasion of a top predator into a food chain in a chemostat. For each trophic level, a bioenergetic model is used in which maintenance and energy reserves are taken into account. Bifurcation analysis is performed on the set of nonlinear ordinary differential equations which describe the dynamic behaviour of the food chain. In this paper, we analyse how the ability of a top predator to invade the food chain depends on the values of two control parameters: the dilution rate and the concentration of the substrate in the input. We investigate invasion by studying the long-term behaviour after introduction of a small amount of top predator. To that end we look at the stability of the boundary attractors; equilibria, limit cycles as well as chaotic attractors using bifurcation analysis. It will be shown that the invasibility criterion is the positiveness of the Lyapunov exponent associated with the change of the biomass of the top predator. It appears that the region in the control parameter space where a predator can invade increases with its growth rate. The resulting system becomes more resistant to further invasion when the top predator grows faster. This implies that short food chains with moderate growth rate of the top predator are liable to be invaded by fast growing invaders which consume the top predator. There may be, however, biological constraints on the top predator's growth rate. Predators are generally larger than prey while larger organisms commonly grow slower. As a result, the growth rate generally decreases with the trophic level. This may enable short food chains to be resistant to invaders. We will relate these results to ecological community assembly and the debate on the length of food chains in nature.

Morphology and polytype disturbances in sublimation growth of SiC epitaxial layers

Epitaxial layers of 6H and 4H-SiC have been grown with high growth rate by sublimation epitaxy on SiC substrates with different surface orientation. Polytype disturbances, i.e. regions within the layer where the polytype differs from that of the underlying substrate, may be observed at domain boundaries, defects and along the edges of the samples. The formation of polytype disturbances is more pronounced as the off-axis angle of the substrate decreases. For on-axis substrates, due to a dislocation controlled growth mechanism, many nucleation centers are formed thus creating several domains with polycrystalline growth along the boundaries. This results in a severe roughening of the layer surfaces. With increasing substrate off-orientation, the morphology improves and the appearance of polytype disturbances is diminished or prevented. For thick layers obtained with high growth rates, the surfaces of the layers grown on vicinal substrates are specular with some defects which are formed from obstacles. The growth proceeds via step-flow growth mechanism. A polytype change at the edge, where the growth steps start, may occur indicating a change in the growth mechanism from step-flow growth to 2D nucleation. 3C-SiC can become the dominant polytype in the epitaxial layer grown on 6H- or 4H-SiC substrates. The polytype disturbance at the edge is considerably reduced or has completely disappeared if the layer thickness does not exceed 300–400 μm as obtained with moderate growth rate of 100–200 μm/h.

Effects of sire growth potential, growing-finishing strategy, and time on feed on performance, composition, and efficiency of steers.

Beef production systems that increase use of unharvested forages and use animals with greater potential for gain affect age and size of animals placed on a finishing regimen. This experiment was conducted to evaluate effects of genetic potential for gain, age at the start of a finishing period, and time on feed on composition, quantity, and quality of beef produced and efficiency of production during finishing. Crossbred cows were bred by AI to Charolais or Line 1 Hereford bulls that represented potentially high (HG) or moderate growth (MG) rates, respectively, to produce spring- or fall-born calves. Steer calves from these matings were placed on an individually fed finishing diet at three ages (A). Spring-born steers were started at 6 or 18 mo of age (A6 and A18), and fall-born steers were started at 12 mo of age (A12). Slaughter times (T) were at 0, 90, 180, and 270 d for A6; 68, 136, and 204 d for A12; and 0, 45, 90, and 135 d for A18. Data collected on each animal included feed intake, growth, chemical composition of the complete body and carcass, and quantitative and qualitative assessment of the meat produced. Four steers of each sire group were slaughtered in each of the 11 A-T treatment groups, and the experiment was repeated for 2 yr in the A12 groups and 3 yr in the A6 and A18 groups (n = 237). Steers sired by HG bulls were larger and produced larger carcasses and more carcass protein than MG-sired steers (S, P < .05 or .01). Steers sired by MG bulls were fatter, had higher quality grades, and accumulated fat at a faster rate than HG-sired steers, and this effect was greater in older steers (G and GA, P < .05 or .01). Sire growth potential did not affect gain, intake, live weight efficiency, tenderness, or taste panel scores (P > .2). Steers sired by HG bulls were more efficient at producing carcass weight and carcass protein at A12 and A18 than were MG-sired steers. At the end of the finishing period, older (A18), HG-sired steers were too large with insufficient fat by current industry standards, and younger (A6), MG-sired steers were too small. Our conclusions are that both HG- and MG-sired steers can produce acceptable carcasses for current market standards with comparable efficiencies of live-weight gain, but the growing and finishing strategy must be adapted to the genotype.

Short communication

We study the invasion of a top predator into a food chain in a chemostat. For each trophic level, a bioenergetic model is used in which maintenance and energy reserves are taken into account. Bifurcation analysis is performed on the set of nonlinear ordinary differential equations which describe the dynamic behaviour of the food chain. In this paper, we analyse how the ability of a top predator to invade the food chain depends on the values of two control parameters: the dilution rate and the concentration of the substrate in the input. We investigate invasion by studying the long-term behaviour after introduction of a small amount of top predator. To that end we look at the stability of the boundary attractors; equilibria, limit cycles as well as chaotic attractors using bifurcation analysis. It will be shown that the invasibility criterion is the positiveness of the Lyapunov exponent associated with the change of the biomass of the top predator. It appears that the region in the control parameter space where a predator can invade increases with its growth rate. The resulting system becomes more resistant to further invasion when the top predator grows faster. This implies that short food chains with moderate growth rate of the top predator are liable to be invaded by fast growing invaders which consume the top predator. There may be, however, biological constraints on the top predator's growth rate. Predators are generally larger than prey while larger organisms commonly grow slower. As a result, the growth rate generally decreases with the trophic level. This may enable short food chains to be resistant to invaders. We will relate these results to ecological community assembly and the debate on the length of food chains in nature.

Optimization of plasma-enhanced chemical vapor deposition of hydrogenated amorphous silicon

An experimental study of the optimization of plasma-enhanced chemical vapor deposition of hydrogenated amorphous silicon is presented. The correlations between deposition parameters and layer properties are discussed. The conditions involve two deposition regimes, collisional “wave riding” at the sheath boundaries (the so-called α-regime) and “Joule heating” in the bulk (the so-called γ′-regime). For low growth rates in the α-regime optimum density of states values and the lowest microvoid densities are obtained in layers with a high compressive stress. For high growth rates in the γ′-regime, layers with a high density of states and a high microvoid density are obtained. The stress in these layers is tensile and correlates with the microvoid density. For moderate growth rate hydrogen-diluted deposition conditions in the γ′-regime near optimum density of states values and low microvoid densities can be obtained in layers with a low compressive stress. Furthermore, using hydrogen-diluted growth, an improved reproducibility and layer-thickness uniformity is obtained in a wider process window. For device applications, a design adapted for the use of hydrogen-diluted growth in the γ′-regime is recommended.

Frequent Irrigation Increases Growth of Pot-in-Pot Sugar and Red Maple

In Virginia, pot-in-pot production of shade trees is normally accomplished by growing bareroot whips in 56-L containers for two complete growing seasons (production cycles). This study monitored the growth of Acer saccharum L. `Green Mountain' (sugar maple), a species with moderate growth rate, and Acer rubrum L. `Franksred' (red maple), a species with a fast growth rate, under standard once-a-day irrigation regime (1X) and a cyclic three-times-a-day regime (3X). Equal daily volumes of water were applied under each regime. Height growth rate increased for sugar maples but decreased for red maples in production cycle two compared to production cycle one. Stem diameter growth rates remained steady for red maple, but increased slightly for sugar maple. A 3X irrigation regime increased stem diameter of red maples, but had no other effect on either species in year one. Height and stem diameter growth of both species were increased by the 3X treatment during production cycle two. This study indicates that the standard production period results in decreased growth in the second production cycle for red maple, but not for sugar maple. Growth rates can be enhanced with a 3X irrigation regime for both species in production cycle two. The 3X irrigation regime only increases the stem diameter growth of red maple in the first production cycle.

Batch and fed-batch bioreactor cultivations of a Thermus species with thermophilic BTEX-degrading activity

The thermophilic bacterium, Thermus species ATCC 27978, which is capable of aerobically degrading benzene, toluene, ethylbenzene, and the xylenes (BTEX), was cultured in 5-1 fermentors on a Castenholz salts-tryptone medium. This bacterium can be cultivated more conveniently at 45 °C, a temperature substantially lower than its optimal growth temperature (approx. 60 °C). Yet, the washed harvested cells from such cultures display the same initial BTEX-degrading activity as those when Thermus sp. is grown at its higher optimal temperature. Two bioreactor cultivation modes, batch and fed batch, were investigated. More biomass and more BTEX-degrading activity (assayed at 60 °C) were generated in fed-batch cultures than in the growth-limited batch cultures. The former yielded a biomass concentration of 2.5 g dry cell weight (DCW) l−1 and whole-cell degrading specific activities of 7.6 ± 1.3, 10.1 ± 1.9, 9.8 ± 2.1, 2.3 ± 0.5, and 4.6 ± 0.9 nmol degraded (mg DCW)−1 min−1 for benzene, toluene, ethylbenzene, m-xylene, and the o- plus p-xylenes (unresolved mixture), respectively. Although the formation of cellular BTEX-degrading activity is growth-associated, a slow to moderate specific growth rate of 0.02–0.07 h−1 favors the production of BTEX-degrading activity, while a high growth rate, of the order of 0.16 h−1, is detrimental to its production. The washed harvested Thermus sp. cells were capable of degrading BTEX over a broad range of thermophilic incubation temperatures, 45–77 °C.

Epitaxial growth of nonlinear optical 4′-nitrobenzylidene-3-acetamino-4-methoxy-aniline thin films on ethylenediammonium terephthalate single crystals

Thin layers of nonlinear optical 4'-nitrobenzylidene-3-acetamino-4-methoxy-aniline (MNBA) were grown heteroepitaxially by organic molecular beam epitaxy (OMBE) on the b-plane of lattice-matched single crystals of the organic salt ethylenediammonium terephthalate (EDT). Epitaxy was realized at a substrate temperature of 80°C and moderate growth rates of 0.1–0.2 Å/s. Optical microscopy showed formation of oriented elongated islands aligned normally to the [001] direction of the substrate. The in-plane orientation of the MNBA overgrowth coincided with that of the EDT surface. Second harmonic generation (SHG) experiments showed as theoretically expected a cos 4θ dependence on the angle θ of the linear polarization of the fundamental beam for an oriented MNBA thin film.

Non-planar crystal growth of Ga 0.5In 0.5P by metalorganic chemical vapour deposition

Layers of Ga 0.5In 0.5P have been grown by low pressure metalorganic vapour phase epitaxy on (100) substrates, which where patterned with normal-mesa and re-entrant grooves. The experiments show fast growth at the groove's side walls at temperatures of 680°C and below, whereas all other facets and all layers grown on planar substrates show but moderate growth rates. The large growth rates are attributed to the small preference for the incorporation of Ga over In at (111)A-like surfaces, which is enhanced in growth on non-planar substrates. The non-stoichiometric incorporation of Ga and In causes the development of strain and subsequently a growth mode transition from two to three-dimensional growth. The resulting rough surface of the side wall facets enables fast growth, whereby the interaction with slower growing facets through the gas phase in the non-planar epitaxy enables the supply of the necessary amount of growth species. At the higher temperatures the preference for incorporation of Ga at the side wall surfaces disappears, and the growth rates and compositions of the side wall facets becomes roughly equal to the growth rates and compositions of the non-planar (100) surfaces and the planar (111)A substrates.

Growth periodicity of introduced pastures on the northern tablelands of New South Wales

This paper reports on the growth periodicity of introduced temperate perennial pastures in a summer-rainfall environment in the high-rainfall zone of eastern Australia. Data were derived from an experiment (1985-87) directed at evaluating pasture cultivars when sown in binary mixtures grazed by sheep. The data were also simulated by using the decision support system SheepO (Version 4·0) and validated by visual techniques, deviance measures, and statistical tests. The model simulated pasture growth rate and total biomass with acceptable accuracy. The study provided a quantification of the growth rhythm of temperate perennial pastures in this environment. The data show that growth rhythm comprises a high growth rate (&gt;50 kg DM/ha·day) during the primary growth cycle in spring, a moderate growth rate (20-50 kg DM/ha·day) during the secondary growth cycle in summer-autumn, and low growth rate (&lt;20 kg DM/ha·day) in winter. The growth performance of introduced pastures based on cv. Demeter tall fescue (Festuca arundinacea) exceeded that of pastures based on cv. Sirosa phalaris (Pharlaris aquatica) in all seasons, at low and high stocking rates, and in all 3 years. The results highlight the potential for pasture cultivars with enhanced seasonal growth rate to increase the pasture feed supply for grazing animals.

Influence of sire growth potential, time on feed, and growing-finishing strategy on cholesterol and fatty acids of the ground carcass and longissimus muscle of beef steers.

The purpose of this study was to determine how diverse beef cattle production systems affect fatty acids and cholesterol of meat. Crossbred cows were bred by AI to high (H) or moderate (M) growth rate potential bulls to produce spring- or fall-born calves. Steer calves from these matings were placed on finishing diets at three ages. Spring-born steers were started at 6 or 18 mo of age (A6 and A18), and fall-born calves were started at 12 mo of age (A12). Slaughter times were 0, 90, 180, and 270 d for A6; 68, 136, and 204 d for A12; and 0, 45, 90, and 135 d for A18. Four steers of each type were slaughtered in each of 2 yr for each sire type x time on feed x slaughter group. Fatty acids and cholesterol of ground carcass and longissimus muscle (LM) were determined by GLC. Carcass fat increased faster in M than in H steers (P < .01). Ground carcass cholesterol was greater for M steers (P = .06) than for H steers because of the greater fat content in the M ground carcass. No differences in LM cholesterol were observed for sire growth potential or time on feed. Fatty acid differences in ground carcass with time on feed were due primarily to decreases in 18:0 and increases in 18:1. The LM saturated and monounsaturated fatty acids changed little with time on feed, but total saturates were greater for M steers (44.5%) than for H steers (42.8%) (P = .02). A18 steers of H sires had the greatest (P = .04) ratio of 18:0 plus unsaturates to 14:0 plus 16:0 (most hypocholesterolemic). We conclude that cholesterol in lean muscle is not altered by the sire growth potential x time on feed x growing-finishing strategy imposed, and that lean beef from steers sired by H bulls and backgrounded before finishing may produce meat with the healthiest lipid composition.

Nonlinear oscillatory evolution of a baroclinically unstable geostrophic vortex

Abstract In a two-layer quasi-geostrophic model, we numerically investigate the nonlinear evolution of a baroclinically unstable geostrophic vortex. For perturbations with a moderate growth rate and a weak amplitude and weak viscosity, a regime of regular oscillation is attained. This regime has a quasi-periodic reversal of the vertical phase shift between the flow patterns in each layer, with a corresponding back-and-forth potential energy transfer between the mean vortex state and the fluctuation pattern. This oscillating vortex, averaged in a frame of reference co-rotating with the angular velocity of each layer, has an elliptical horizontal configuration with a simple relation between potential vorticity and co-rotating streamfunction. Simulations with smaller Burger or Reynolds number or larger initial perturbation amplitude show less regularity in the oscillation and eventually result in vortex breaking.

サロマ湖における移植アサリの生殖周期と殻成長

The reproductive cycle and shell growth of the Manila clam Ruditapes philippinarum, transplant-ed from Lake Akkeshi to Saroma Lagoon, Hokkaido, northern Japan, were studied from April 1991 to August 1992. Histological examination revealed that the spawning season is from July to Septem-ber, with a peak in August. The shell lengths at first maturity were 25mm (2 years) and 27mm (2 or 3 years) for males and females, respectively. Disturbance rings on the shells formed upon trans-plantation were used to estimate growth, which mainly occurred in May and June. Growth is described by the von Bertalanffy growth equation for both sexes Lt=49.71 (1-exp (-0.416 t)), where Lt is the shell length (mm) at age t (year). The clams in the lagoon had a shorter spawning and growing season, were larger and older at first maturity, and had a more moderate shell length growth rate than clams from southern Japan. Finally, some reproductive and growth-related responses to various habitats were discussed.

Organic molecular beam deposition of highly nonlinear optical 4′-nitrobenzylidene-3-acetamino-4-methoxy-aniline

Thin films of the nonlinear optical material 4′-nitrobenzylidene-3-acetamino-4-methoxy-aniline have been prepared using the organic molecular beam deposition technique. High quality homoepitaxial layers have been grown at substrate temperatures of 80 °C and moderate growth rates of 0.1–0.5 Å/s. The samples have been characterized by optical polarization and interference microscopy as well as atomic force microscopy. Growth experiments on inorganic substrates, including silicon and glass, have been performed in a substrate temperature range of −190 to 100 °C and led to amorphous films at low temperatures and polycrystalline films at temperatures above 50 °C.