Period Of Linear Growth Research Articles

BREEDING BIOLOGY OF THE WHISKERED AUKLET (AETHIA PYGMAEA) AT BULDIR ISLAND, ALASKA

Abstract We quantified aspects of the breeding biology of Whiskered Auklets (Aethia pygmaea) at Buldir Island, western Aleutian Islands, Alaska, from 1993 to 1998 to provide a better understanding of this poorly known species' ecological relationship to other auklets (Aethia spp.). Whiskered Auklets nest in rock crevices in a range of habitats including talus slopes, cliffs, and beaches. No physical characteristic of nesting crevices predicted breeding success. Hatching dates varied among years; mean hatching dates averaged 20 June ±6.8 days (range 16–27 June). Chicks remained in the nest for 39 ± 2 days, with mean annual fledging from 27 to 29 July. Eggs were 44.1 ± 1.6 mm in length and 31.1 ± 1.61 mm in breadth, and varied significantly in size among years. Chicks weighed 17.4 ± 2.4 g (15.6% of adult mass) within two days of hatching and gained 3.8 g day−1 in mass and 3.2 mm day−1 in wing length during the linear growth period. Chicks fledged at 101.3 ± 11.3 g (90.5% adult mass) after a prefledging mass...

Growth patterns of Belgian Blue replacement heifers and growing males in commercial farms

A survey was carried out to propose models of growth curves in Belgian Blue cattle less than 20 months of age and raised in commercial farms in southern Belgium. Live weight data were recorded between 1993 and 1999 from 1104 breeding heifers, and 924 growing males. The linear, polynomial group, power, logistic, Brody, Gompertz, von Bertalanffy and Richards models were used and compared. A step-wise linear growth model characterized by two periods of linear growth was also evaluated. This last model has been proposed as the reference model to characterize the growth curves of Belgian Blue cattle less than 20 months old. The animals were then ranked and divided in subgroups based on percentiles and quartiles in order to compare their performances. The subgroups performing better presented a greater homogeneity. The males ranked above the 90th percentile presented a growth rate comparable to that of young males selected for artificial insemination. Cattle ranked above the third quartile presented a growth rate comparable to that of licensed animals. When reproduction performances were related to the growth rate, it appeared that the better growing heifers were bred younger and heavier than lesser performing animals.

VARIATION OF SUNFLOWER GROWTH, SOIL MOISTURE AND SOIL TEMPERATURE IN RELATION TO PLANTING PATTERNS AT A HIGH LATITUDE SITE

HALLE-WITTENBERG, HALLE(SAALE), GERMANY Received: 13 June, 2001; accepted: 6 August, 2001 Field experiments were conducted at a high latitude site for sunflower (Helianthus annuus L.) production in central Germany (51 o 24' N, 11 o 53' E) in 1996, 1997 and 1998. The responses of sunflower development to various planting patterns differed in the duration from emergence to the middle of the linear growth period as calculated via a tangent hyperbolic model F(t)=(. +ß)×tanh[. ×(t–.)]. Final dry matter accumulation showed few differences among the planting patterns: 12 plants m –2 at 50 cm row spacing at 75 cm row spacing (RS2PD2) and 4 plants m –2 at 100 cm row spacing (RS3PD1). The actual and simulated values for final dry matter were close to 1200 g m –2 . The responses of soil moisture and temperature to planting patterns changed from the upper to the deep soil layers. In a normal year, e.g. 1997, the soil water to 150 cm depth was sufficient for sunflower growth. In a drought year, e.g. 1998, soil water deeper than 150 cm was used by sunflower crops. The soil temperature was mostly lower in RS1PD3 and RS2PD2 than in RS3PD1, particularly in the upper soil, at depths of 5 and 20 cm. The most important factor defining the responses of soil moisture and temperature to planting patterns seems to be the amount of radiation penetrating the ground, which may depend on latitude, wind and row orientation.

Numerical Studies of Tearing Mode Instability and Magnetic Reconnection in Anisotropic Plasma

AbstractThe tearing mode instability and magnetic reconnection process in an anisotropic plasma (P┴ ≠ P∕∕ ,T┴ ≠ T∕∕) are numerically studied by a two‐dimensional, three‐component, time‐dependant compressible MHD simulation. It is found that, after a short period of linear growth, the instability tends to become nonlinear saturation. The growth rate will increase when the intensity of pressure anisotropy |P┴/P|‌ increases, while it will decrease with the decrease of the plasma β and the augment in the y component By of magnetic field . In case of a large perpendicular anisotropy(P┴ > P∕∕), when the magnetic island formed in the current sheet by magnetic reconnection becomes nonlinear saturation, there will be cavity structures formed near the X‐type points. The cavities become larger gradually while the magnetic islands become smaller and vanish at last. In the plasma with a parallel anisotropy (P┴ < P<), the fire hose instability can only be excited in the central region of current sheet, and large magnetic island can't be formed in the current sheet.

Cloning of the malic enzyme gene from Corynebacterium glutamicum and role of the enzyme in lactate metabolism.

Malic enzyme is one of at least five enzymes, known to be present in Corynebacterium glutamicum, capable of carboxylation and decarboxylation reactions coupling glycolysis and the tricarboxylic acid cycle. To date, no information is available concerning the physiological role of the malic enzyme in this bacterium. The malE gene from C. glutamicum has been cloned and sequenced. The protein encoded by this gene has been purified to homogeneity, and the biochemical properties have been established. Biochemical characteristics indicate a decarboxylation role linked to NADPH generation. Strains of C. glutamicum in which the malE gene had been disrupted or overexpressed showed no detectable phenotype during growth on either acetate or glucose, but showed a significant modification of growth behavior during lactate metabolism. The wild type showed a characteristic brief period of exponential growth on lactate followed by a linear growth period. This growth pattern was further accentuated in a malE-disrupted strain (Delta malE). However, the strain overexpressing malE maintained exponential growth until all lactate had been consumed. This strain accumulated significantly larger amounts of pyruvate in the medium than the other strains.

Changes in body composition during reproduction and postnatal growth in the little brown bat, Myotis lucifugus (Chiroptera: Vespertilionidae)

Body composition of little brown bats, Myotis lucifugus was quantified to evaluate the proximate costs of reproduction in a small temperate mammal. Changes in the major components of body composition (water, lean dry, and fat mass) during the breeding season were analyzed in adult females and in young during the postnatal growth period. Changes in body composition of reproductive females were small relative to their level of reproductive effort, suggesting that most of the increased costs of reproduction are not met by mobilizing body reserves. The reduction of lean dry and fat mass in adult females suggest that mineral and fat stores are mobilized to promote high postnatal growth rates in pups. Changes in the gastrointestinal (GI) tract of adult females support the hypothesis that increased food intake and assimilation are the primary morphological and physiological responses to the increased energy demands of lactation. A two-week period of linear growth during the postnatal period when pups were dependent on their mothers was followed by a rapid transition to adult body composition.

Kinetics of Ceramic‐Metal Composite Formation by Reactive Metal Penetration

The rate of composite formation via reactive metal penetration has been determined. The metal penetration depth (i.e., the reaction‐layer thickness) was measured from cross sections of partially reacted samples. Samples were fabricated by immersing dense mullite preforms in a bath of molten aluminum at temperatures of 900°–1300°C and reacting the combination for up to 250 min. In general, the reaction‐layer thickness increased linearly as the time increased. Penetration rates as high as 6.0 mm/h were measured; however, the aluminum penetration rate varied dramatically with time and temperature. The penetration rate increased when the reaction temperature was increased from 900°C to 1100°C, and the reaction‐layer thickness increased linearly as the time increased in this temperature range. At temperatures of 1150°C and above, reaction‐layer formation slowed or stopped after a relatively short period of rapid linear growth, because of an increase in silicon concentration near the reaction interface. The duration of the rapid linear growth period decreased from 25 min at 1150°C to <1 min at 1250°C. At temperatures of 1300°C and above, no reaction layer was detected by using optical microscopy. Kinetics data and transmission electron microscopy analysis suggest that the reaction was inhibited at higher reaction temperatures and longer times, because of silicon buildup and saturation at the reaction front. Calculations show that, as the reaction temperature increased, the silicon production increased faster than the silicon transport. The two rates were approximately equal at a temperature of 1100°C.

Hypervelocity Richtmyer–Meshkov instability

The Richtmyer–Meshkov instability is numerically investigated for strong shocks, i.e., for hypervelocity cases. To model the interaction of the flow with non-equilibrium chemical effects typical of high-enthalpy flows, the Lighthill–Freeman ideal dissociating gas model is employed. Richtmyer’s linear theory and the impulse model are extended to include equilibrium dissociation chemistry. Numerical simulations of the compressible Euler equations indicate no period of linear growth even for amplitude to wavelength ratios as small as one percent. For large Atwood numbers, dissociation causes significant changes in density and temperature, but the change in growth of the perturbations is small. A Mach number scaling for strong shocks is presented which holds for frozen chemistry at high Mach numbers. A local analysis is used to determine the initial baroclinic circulation generation for interfaces corresponding to both positive and negative Atwood ratios.

Atomic force microscopy investigations of rapid thermal carbonized silicon

Thin cubic silicon carbide layers grown by carbonization in a rapid thermal processing equipment were investigated by atomic force microscopy. Different roughness descriptions were applied and compared for the characterisation. A special attention was drawn on the morphology evolution during the initial stages of the growth. The surface roughness increases during the first, i.e. the linear growth period, run through a maximum at the point where the growth rate is decreasing, i.e. the saturation set in, and decreases slightly with further growth. Regarding to the common growth model, at the maximum point, the laterally grown crystallites are touching and sealing off the surface. Decreasing the propane concentration in hydrogen results in a slight decreasing of the density of the crystallites and increase of its size. Additionally pits in the surface and well shaped objects were also observed. In increasing the temperature the surface features were shaped more clearly. This indicates predominant three-dimensional growth.

Variation in maternal investment in a small cervid; the effects of cohort, sex, litter size and time of birth in roe deer (Capreolus capreolus) fawns.

We investigated the effects of cohort, sex, litter size and time of birth on birth weights and postnatal growth rates of roe deer fawns in a highly reproductive Norwegian population. By repeatedly recapturing radio-collared individuals, a total of 950 weights were obtained from 231 fawns of known age. In accordance with earlier studies, there was a period of linear growth during the first month following birth. Mean postnatal growth rates of 155 g/day are the highest yet recorded for roe deer; however, the mean birth weights of fawns were lower than those reported from populations in continental Europe. During the period of linear growth, we found no sex differences. However, growth rates were affected both by time of birth and litter size; fawns born early had lower growth rates than fawns born during or after the peak calving period, and fawns in triplet - groups had lower growth rates than either fawns in twin - groups or single fawns. Despite a fourfold increase in population density during the study, this factor was not able to explain variation in postnatal growth rates, although cohort effects on birth weight were evident.

FRUITING PHENOLOGY AND FRUIT SET OF CAROB, CERATONIA SILIQUA L. (CESALPINACEAE)

The fruiting phenology of two female and two hermaphroditic carob (Ceratonia siliqua L.) cultivars was studied in NE Spain. After flower pollination (September–November), fruit growth followed a sigmoidal curve, with an initial period of slow growth (December–March), a period of linear growth (April–June), and a final period of slow growth and maturation (June–Au–gust). Shedding of flowers and young fruits was high in October–December, and slowed down in January–February. Then, fruit drop again increased until May, and from June to August fruit shedding was almost nil. Fruit initiation was 12.6–35.0%, and fruit shedding was high (79.2–90.2% of the fruits initiated dropped before maturity). In the two female cultivars, larger inflorescences had higher rates of fruit initiation, fruit set, and seed set per flower than smaller inflorescences.

SF6−3He Tracer Release Experiment: A New Method of Determining Longitudinal Dispersion Coefficients in Large Rivers

Longitudinal dispersion coefficients have been determined in the tidal Hudson River using sulfur hexafluoride. For this purpose, SF6, a nonreactive synthetic gas, was injected into the Hudson south of Albany, NY, and used in a fashion similar to a fluorescent dye. Three days after injection, SF6 distributions along the main axis of the river were approximately Gaussian. The change in variance with time showed two periods of linear growth. During the first period (days 3−8), the longitudinal dispersion coefficient was estimated to be 47 ± 6 m2 s-1, and during the second period (days 8−13), it was 162 ± 22 m2 s-1. A second gas, 3He, which was injected simultaneously with SF6, allowed for the determination of gas exchange rates across the air−water interface. Gas transfer velocities normalized to a Schmidt number of 600 ranged from 2.8 to 9.2 cm h-1 and correlated well with mean wind speed.

An idealized study of African easterly waves. II: A nonlinear view

The nonlinear behaviour of an easterly-wave normal mode has been examined. Significant differences from normal-mode character become apparent after saturation of the instability. The easterly wave is initially dominated by barotropic energy conversions (CK) but later grows mainly through baroclinic energy conversions (CE). The eddy kinetic energy of the wave peaks and then decays with both CK and CE contributing to this decay. The energy conversions associated with the nonlinear growth of the wave have more in common with those found in the GATE study over west Africa and GCM integrations than do the previous linear studies of African easterly waves. The life cycle is described using EP flux diagnostics and Rossby wave propagation ideas. After the linear growth period, characterized by divergent, mostly horizontal, EP flux vectors and barotropic growth, the life cycle becomes dominated mostly by vertical EP fluxes associated with vertical wave propagation from the jet region both above and below the wave, and by baroclinic growth. This results in increased wave amplitudes in the upper troposphere and at low levels. This mechanism for increased amplitudes at upper levels may help to explain the observed winds in the waves at these levels—a feature not found in linear studies. The effect of including simple parametrizations of different diabatic processes is also examined. The main effect of including boundary-layer fluxes is merely to damp the large surface amplitudes which occur in the nonlinear part of the life cycle. Including a restoration of the basic-state results in stronger growth and larger amplitudes at all levels. Two life cycles with different latent heating parametrizations are also examined. One has a CISK scheme driven by low-level ascent, and the other a scheme based on the conservation of a prescribed value of the equivalent potential temperature. In each case CE becomes comparable to CK but does not dominate as in the basic life cycle. This is due to significant changes in the synoptic structure of the wave when latent heating is included: in particular the vertical velocity field changes dramatically. Indeed, with the CISK scheme it compares well with GATE observations, with a deep ascent region present throughout the troposphere ahead of the main cyclonic region. The maximum is also larger than in the dry case, although still somewhat less than observed. Two life cycles were also examined with both CISK and boundary-layer fluxes included; the second also including zonal flow restoration. In the case of both life cycles CE dominates over CK in the nonlinear part of the life cycle, unlike the case with CISK alone. The structures found are similar to those with CISK alone except that the surface amplitude is considerably weakened by the boundary layer. However, the magnitude of the ascent is increased with the boundary layer and increased further with the restoration, making it comparable with observed values.

An idealized study of African easterly waves. II: A nonlinear view

AbstractThe nonlinear behaviour of an easterly‐wave normal mode has been examined. Significant differences from normal‐mode character become apparent after saturation of the instability. The easterly wave is initially dominated by barotropic energy conversions (CK) but later grows mainly through baroclinic energy conversions (CE). The eddy kinetic energy of the wave peaks and then decays with both CK and CE contributing to this decay. The energy conversions associated with the nonlinear growth of the wave have more in common with those found in the GATE study over west Africa and GCM integrations than do the previous linear studies of African easterly waves.The life cycle is described using EP flux diagnostics and Rossby wave propagation ideas. After the linear growth period, characterized by divergent, mostly horizontal, EP flux vectors and barotropic growth, the life cycle becomes dominated mostly by vertical EP fluxes associated with vertical wave propagation from the jet region both above and below the wave, and by baroclinic growth. This results in increased wave amplitudes in the upper troposphere and at low levels. This mechanism for increased amplitudes at upper levels may help to explain the observed winds in the waves at these levels—a feature not found in linear studies.The effect of including simple parametrizations of different diabatic processes is also examined. The main effect of including boundary‐layer fluxes is merely to damp the large surface amplitudes which occur in the nonlinear part of the life cycle. Including a restoration of the basic‐state results in stronger growth and larger amplitudes at all levels.Two life cycles with different latent heating parametrizations are also examined. One has a CISK scheme driven by low‐level ascent, and the other a scheme based on the conservation of a prescribed value of the equivalent potential temperature. In each case CE becomes comparable to CK but does not dominate as in the basic life cycle. This is due to significant changes in the synoptic structure of the wave when latent heating is included: in particular the vertical velocity field changes dramatically. Indeed, with the CISK scheme it compares well with GATE observations, with a deep ascent region present throughout the troposphere ahead of the main cyclonic region. The maximum is also larger than in the dry case, although still somewhat less than observed.Two life cycles were also examined with both CISK and boundary‐layer fluxes included; the second also including zonal flow restoration. In the case of both life cycles CE dominates over CK in the nonlinear part of the life cycle, unlike the case with CISK alone. The structures found are similar to those with CISK alone except that the surface amplitude is considerably weakened by the boundary layer. However, the magnitude of the ascent is increased with the boundary layer and increased further with the restoration, making it comparable with observed values.

Changes in biliary lipid secretion during normal development and diurnal cycling in the rat

Biliary lipid secretion in conjunction with hepatic cholesterol synthesis was determined in normal male rats at 4, 5, 7, and 9 weeks of age, during a period of linear growth and a near fourfold increase in liver size. Studies were performed both at periods of low (mid-light cycle) and high (mid-dark cycle) hepatic cholesterol synthesis. Biliary bile salt, phospholipid, and cholesterol secretion (per g of liver) markedly decreased with an increase in liver size. Whereas the secretion of bile salts and phospholipid was not significantly different in mid-dark and mid-light periods for animals of the same age, cholesterol secretion was greater in the mid-dark than in the mid-light period at 5, 7, and 9 weeks of age. Relationships between biliary cholesterol secretion and bile salt and phospholipid secretion differed at mid-dark and mid-light periods, as follows: cholesterol secretion was not significantly related to bile salt secretion at mid-dark (r = 0.49, P > 0.05) but was related at mid-light (r = 0.73, P = 0.003); and although cholesterol secretion was significantly related to phospholipid secretion at mid-dark, this relationship was not nearly as strong as at mid-light (P < 0.005, comparing r = 0.95 at mid-light with r = 0.53 at mid-dark). In contrast, at mid-dark, biliary cholesterol secretion was strongly related to hepatic cholesterol synthesis (r = 0.84, P < 0.0001) whereas at mid-light the two were not significantly related (r = 0.13, P > 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Synchronous germination of Streptomyces antibioticus spores: tool for the analysis of hyphal growth in liquid cultures.

We have devised a method for obtaining synchronous and dispersed growth of Streptomyces antibioticus in liquid cultures. After ultrasonic treatment, most of the spores germinated at the same time, yielding hyphae very similar in length. Dispersed growth was achieved in media without Ca2+ and in which the levels of Fe2+ and Mg2+ were carefully controlled. Studies on the kinetics of growth carried out with synchronous cultures of young hyphae revealed a multiphasic pattern of hyphal elongation, with successive periods of linear growth and changes in growth rate at defined intervals.

Cell growth and accumulation of Thiobacillus thiooxidans S3 in a pH-controlled thiosulfate medium.

The Thiobacillus thiooxidans S3 strain was grown on modified Silverman 9K medium containing thiosulfate as a sole energy source instead of sulfur. When the pH of medium was controlled at 5.0 during the cultivation, the growth rate greatly increased to 0.067h-1 and the cell yield obtained with 1% thiosulfate was 210mg/l. When cell growth declined, placing the culture in fresh medium effectively prolonged the period of linear growth and the cell concentration reached 891mg/l in 309h of cultivation. The cells obtained in the replacement culture efficiently oxidized the sulfite.

ERRATUM

Delete “In contrast, under 5% CO2, the cells grew even at 40 μm NaCl (Fig. 3), and the growth rate at 0.5–10 mm NaCl during the linear-growth period was 0.24 μg Chl·(ml culture)−1·h−1”

Effects of post-transplant water deficits on leaf development and yield of winter planted tobacco in north Queensland

The effect of water deficit on floral initiation, leaf development and yield of commercial leaf of tobacco planted in the winter was studied in northern Queensland. The deficits were induced by different watering treatments at transplanting in combination with a range of times during which irrigation was withheld after transplanting. In addition, the effect of two periods of water deficits on flower and leaf development was investigated in a pot experiment under controlled environment conditions. Water deficits after transplanting delayed floral initiation and allowed more leaves to be produced. Moreover, the size of most leaves of commercial value was increased by water deficit; for example, withholding water for 28 days after transplanting increased the area and dry weight of commercial yield per plant by 33%. Results from the pot experiment demonstrated that the larger leaf area resulted from an extended period of linear growth and a greater rate of expansion after water deficits were relieved.

Litter Size and Postnatal Growth Rate in the Pallid Bat, Antrozous pallidus

Factors intrinsic to the maternity roost and factors determining maternal nutrition affect postnatal growth rates of bats in the field (Tuttle and Stevenson, 1982). For example, roost temperature significantly influences growth rates, although few field studies of ontogeny have determined the thermal environment of the maternity roost. Ectoparasite populations within a maternity roost may also influence postnatal growth. In addition, factors extrinsic to the maternity roost such as weather and food availability, which determine the nutritional status of the mother, influence postnatal growth rates. Litter size in most species of bats is one, but the number of young ranges up to five in certain species (Tuttle and Stevenson, 1982). The number of young per litter also varies within a species depending on the mother's age, geographic location, season, and general climatic conditions. Pallid bats, Antrozous pallidus, produce twins in 80% of births and single offspring in the remaining 20% (Orr, 1954). I present here data on the effects of litter size on the size of young at birth and on postnatal growth rate in pallid bats in a laboratory setting. Also, the effect on the growth rate of the remaining animal of removing one member of a pair of twins at birth is discussed. Finally, growth rates determined for A. pallidus in the laboratory will be compared to those measured in the field. Pregnant A. pallidus were collected in an attic roost near Napa, Napa Co., California, during late May 1979, 1980, 1981, and 1982 and were transported to Seattle, Washington, by air freight. Bats were housed as a group in the laboratory and were maintained on a diet of mealworms supplemented with vitamins and minerals. Cage temperature was maintained between 26-28?C with a relative humidity of 55-65%, and the animals were exposed to a 12L:12D cycle. Parturition occurred in the middle of June. Newborn bats remained with the mother until weaned. A portion of the animals born each year were used in studies of the ontogeny of microvascular function in the cutaneous circulation of the wing. Experimental manipulation of these animals had no effect on growth rate compared to control bats (F = 1.24, dMf. = 1, 40, P > 0.05); therefore, data for all animals reared in the laboratory were pooled. Growth rates were determined for 63 bats, which resulted from 33 twin and seven single births. Growth rate was determined by measuring forearm length to the nearest 0.01 mm with a vernier caliper during the period of linear growth between birth and 22 days of age. The initial measurement (day 1) was made within 12 to 18 hours after birth; newborns were not handled until 12 hours after birth to allow completion of mother-young bonding. Forearm length was then measured periodically between days 1 and 22, but no attempt was made to measure all animals at specific ages. Growth rate was determined by regressing forearm length on age (Sokal and Rohlf, 1969) after forearm length was normalized to adult forearm length. Forearm length of adults used in this study averaged 57.4 mm (n = 43, SE = 0.31 mm) and was not significantly different from year to year. Forearm length was normalized to allow comparison of growth rates among different populations of A. pallidus and with other bat species. Growth rates were expressed as percent of adult forearm length per day, and forearm lengths were expressed as percent of adult forearm length. Comparisons of growth rate (slope of regression line) and size at birth (Y-intercept of regression line) among subgroups of interest were made with regression analyses and dummy variable tests for parallelism and coincidence found in Sokal and Rohlf (1969) and Kleinbaum and Kupper (1978). Forearm length on days 1 and 22 was compared among subgroups using a one-way ANOVA (Sokal and Rohlf, 1969). Pallid bats reared in the laboratory developed on a schedule similar to that described by Orr (1954) for field- and laboratory-reared animals and by Davis (1969) for field-reared animals. The mother provided the sole source of nutrition; weaning in A. pallidus occurs at 40 to 45 days of age (Orr, 1954). Growth of newborns did not appear to be limited by nutritional status of the mother because females in this study