Determination Of Growth Rate Research Articles

Fatty acid composition of Scenedesmus obliquus: Correlation to dilution rates

To test the influence of growth rate on the pattern of fatty acids, Scenedesmus obliquus was exposed, in a chemostat culture, to different dilution rates, as these determine growth rates. Dilution rates varied from 0.0 to 0.48 d −1 (0.0 – 0.15 – 0.33 – 0.45 – 0.48 d −1). In total, only few fatty acids showed a significant correlation to the dilution rate. However it seemed, that algae from the chemostat with zero flow-through differed more from steady state growing algae (i.e. positive dilution rates) in their patterns of fatty acids than within positive growth rates. Also, carbon and nitrogen were measured and C:N-ratios were calculated. The C:N-ratios support the grouping of the samples into two categories: “zero dilution rate” and “positive growth rates at steady state”.

Influence of Trophic State on Spotted Bass and Largemouth Bass Spawning Time and Age-0 Population Characteristics in Alabama Reservoirs

Abstract We described and compared spawning periodicity, abundance, and growth of age-0 largemouth bass Micropterus salmoides and spotted bass M. punctulatus from six Alabama reservoirs in 1993 and 1994 that displayed a wide range of limnological and morphological characteristics. One reservoir was divided into three distinct areas based on limnological conditions and thus, eight reservoir study areas were examined. Reservoirs fell along a continuum from deep, long-retention reservoirs with fluctuating water levels and low phytoplankton biomass to shallower, short-retention reservoirs with minimum water level fluctuations and generally high phytoplankton biomass. Fish were collected with rotenone in 0.02-ha enclosed shoreline areas. Daily rings on sagittal otoliths were counted to determine growth rates and to back-calculate spawning times. Trophic states included oligotrophic (chlorophyll a, 8 mg/m3; N = 3) sy...

Analysis of Radiative Heat Transfer and Mass Transfer During Multi-Wafer Low Pressure Chemical Vapor Deposition Process

An analysis of heat and mass transfer has been carried out for multi-wafer Low Pressure Chemical Vapor Deposition (LPCVD). Surface radiation analysis considering specular radiation among wafers, heaters, quartz tube and side plates of the reactor has been done to determine temperature distributions of 150 wafers in two dimensions. Velocity, temperature and concentration fields of chemical gases flowing in a reactor with multi-wafers have been then determined, which determines Si deposition growth rate and uniformity on wafers using two different surface reaction models. The calculation results of temperatures and Si deposition have been compared and found to be in a reasonable agreement with the previous experiments.

Desempenho da tilápia nilótica Oreochromis niloticus (L.) em gaiolas de pequeno volume

Alevinos de tilápia nilótica Oreochromis niloticus (L.) com peso médio de 18,85 g, foram estocados em gaiolas de 1,7 m3 cada, em densidades de 75, 150, 300 e 600 peixes/m3 (T75; T150; T300 e T600), num delineamento inteiramente casualizado (4 tratamentos e 3 repetições), e criados por 196 dias, com ração comercial extrusada, flutuante, contendo 28% de proteína bruta. A cada 30 dias, 20% do lote de peixes de cada gaiola foi medido e pesado para determinar ganho de peso (GDP) e conversão alimentar (CA) de cada tratamento. Os resultados finais de CA e GDP para cada tratamento foram, respectivamente: para T75, 6,31:1 e 71,52g; para T150, 4,08:1 e 65.14g; para T300, 3,57:1 e 59,60g; e para T600, 2,96:1 e 69,17g. Em relação ao ganho de peso, T600 e T75 foram semelhantes (P > 0,01) sendo que T600 apresentou melhor CA que T75 (P < 0,01). Os tratamentos T150 e T300 apresentaram desempenho inferior a T600 ou T75. Os índices de CA e GDP obtidos no experimento, resultaram da interação de fatores como estresse térmico e luminoso, a baixa qualidade da ração comercial utilizada e a baixa taxa de reversão sexual do lote de alevinos adquiridos de produtores comerciais.

Optimization of sublimation growth of SiC bulk crystals using modeling

Analysis of factors determining growth rate and shape of the crystallization front during sublimation growth of bulk SiC crystals is presented. For this purpose, mass transport of species in the graphite crucible coupled with global heat transfer in a sublimation growth system is studied. Specific features of the growth process in a tantalum container are discussed.

Determination of Bacterial Biomass from Flow Cytometric Measurements of Forward Light Scatter Intensity

This unit presents methods for measuring biomass of bacteria by flow cytometry. Such measurements are an integral part of determining growth rates and kinetics. This unit discusses calibration and standardization methods for bacterial studies using flow cytometry and provides a detailed discussion of the components involved. The serious microbiologist will appreciate the advantages flow cytometry brings to many aspects of microbial study, and this unit is no exception.

Why aren't countries rich?: Weak states and bad neighbourhoods

This article challenges a common viewpoint that the policy choices made by state leaders are central to explanations of economic growth. It argues that there are two possible flaws in this viewpoint. First, that state leaders have a free choice in policy decisions; second, that it is policies that in large part determine growth rates. Using a set of variables designed to capture the weakness of the policy autonomy of the state and possible non‐policy influences on growth rates, the article concludes that initial conditions are a better determinant of wealth and growth than free policy choice.

Effects of Morphine in Decomposing Bodies on the Development of Lucilia sericata (Diptera: Calliphoridae)

This study concerns the effects of morphine in tissues on the rate of development of Lucilia sericata (Diptera: Calliphoridae) using those tissues as a food source. Lucilia sericata is a species of fly commonly found on human corpses in Europe during the early stages of decomposition and thus of forensic interest. Three rabbits were administered 12.5, 25.0 and 50.0 mg/h of morphine chlorhydrate via ear perfusion over a period of 3 h. These dosages and duration of perfusion were calculated to give tissue concentrations of morphine similar to those encountered in fatal human overdoses. A fourth rabbit was used as a control. Following administration of the drug, rabbits were sacrificed and 400 eggs of Lucilia sericata, all of the same age, were placed in the eyes, nostrils and mouth of each rabbit. Developing larvae were sampled daily to determine growth rate and weight. Puparia and emerging adult flies were also sampled. Data were analyzed using analysis of variance (ANOVA) and Student's T-test. Results of this study show that an underestimation of the postmortem interval of 24 h is possible if the presence of morphine in tissues is not considered. This study demonstrates again the necessity of considering the possible effects of drugs in tissues on insect growth rates when estimating the postmortem interval using entomological techniques.

Reflection high-energy electron diffraction oscillations on rotating substrates

We compare different methods to measure reflection high-energy electron diffraction oscillations on rotating substrates. The best signal-to-noise ratio as well as the highest accuracy is obtained by measuring the full width at half maximum of the specular spot perpendicular to the surface. The accuracy of the method is well within 1% and offers a practical way to accurately determine growth rates for device fabrication.

Epitaxial Si1−yCy alloys: The role of surface and gas phase reactions

We have studied substitutional carbon incorporation in Si1−yCy alloys grown on Si (100) by ultrahigh vacuum chemical vapor deposition using silane and methylsilane as silicon and carbon precursors. Carbon incorporation has been studied in the growth temperature range of 550–650 °C. The total carbon content of the alloys increases linearly with the methylsilane partial pressure and a methylsilane sticking coefficient approximately two times higher than that of silane was determined from the data. Substitutional carbon content in the alloys tends to saturate at higher methylsilane flows. Our results, together with other previous reports, provide new insight into the roles of gas phase and surface reactions in determining growth rates and carbon incorporation efficiency.

Delineation of the three brown rot fungi of fruit crops (Monilinia spp.) on the basis of quantitative characteristics

The three Monilinia spp., known as the brown rot fungi of fruit crops, are usually distinguished from each other on the basis of (qualitative) colony characteristics. We linked these qualitative features to unambiguously defined, quantitative colony and germ tube characteristics. A wide collection of isolates of Monilinia fructicola (Winter) Honey, Monilinia laxa (Aderhold & Ruhland) Honey, and Monilinia fructigena (Aderhold & Ruhland) Honey was used to determine growth rate and sporulation intensity on potato dextrose agar (PDA) at 22°C under two light regimes (darkness, 12 h light : 12 h dark). The following germ tube characteristics were determined on water agar after incubation for 18 h at 22°C in darkness: length of the (leading) germ tube, distance to the first branch, and the number of germ tubes per conidium. Increase in colony diameter from day 3 to day 5 and sporulation intensity measured after 14 days was the highest in M. fructicola, whilst M. laxa and M. fructigena showed considerable overlap in these features. The length of the germ tube after 18 h incubation was shortest in M. laxa, ranging from 161 to 466 µm. In M. fructicola and M. fructigena these ranges were 465-851 and 307-806 µm, respectively. The occurrence of more than one germ tube per conidium was most prominent in M. fructigena. Discriminant analysis on the basis of different combinations of the quantitative characteristics measured, showed that the combination of growth rate on PDA and length of the germ tube was sufficient to delineate the three brown rot fungi. One of 11 M. fructicola isolates was misclassified, the same held for M. fructigena (one misclassification of nine isolates). No misclassifications occurred in M. laxa.Key words: brown rot fungi, growth characteristics, Monilinia spp., taxonomy.

Estimation of growth and mortality parameters from size frequency distributions lacking age patterns: the red sea urchin (Strongylocentrotus franciscanus) as an example

We present a maximum likelihood procedure for estimating population growth and mortality parameters by simultaneously analysing size frequency and growth increment data. The model uses von Bertalanffy growth with variability among individuals in the two parameters that determine growth rate, and size-dependent mortality. Analyzing growth increments together with size frequencies reduces the statistical confounding of the natural mortality rate with von Bertalanffy's K parameter. We assume steady-state (constant recruitment) conditions for the size distributions; hence the method does not depend on age modes in the distribution. We evaluate the bias and precision of estimates obtained for growth-dominated distributions typical of the red sea urchin (Strongylocentrotus franciscanus) in northern California, although the method and its evaluation could be applied as easily to mortality-dominated or bimodal distributions. The method provides good estimates with sample sizes as low as 200 individuals in a size distribution and 30 growth increments. Results are robust to random variability in recruitment, measurement error, and sampling selectivity up to the size where about one third of the distribution is affected. Estimation of the fishing mortality rate could require size distributions from both an unharvested and a harvested population. Estimates of growth and mortality rates depend critically on reliable growth data.

Beta convergence in Finland: regional differences in speed of convergence

This paper estimates β convergence across the 88 Finnish small-scale subregions from 1934 to 1993 using taxable per capita income as an indicator of income level. The results resemble those obtained in other studies for larger areas: regional β convergence in Finland has been about 2% per year in the long run, whereas in the short run β has tended to be unstable. Furthermore, this paper finds that it is possible to identify regional factors which tend to determine growth rates and steady-state income levels. These determinants are found to affect regions' individual β convergences. The steady-state level and speed of a region's individual β seems to be inversely related: the higher the β the lower the steady-state level.

RNA content of copepods as a tool for determining adult growth rates in the field

We propose a method to determine growth rates of adult copepods based on their nucleic acid contents. We investigated the suitability of this method on the marine copepod Acartia gruni in a range of food concentrations and temperatures. There was a good linear relationship between growth rate (estimated as egg production) and RNA contents of the adult copepods. The slope of the relationship was dependent on temperature. We also built a multiple regression model to predict egg production rates of A. grani as a function of RNA contents and temperature. This method allows very intensive field sampling and does not require incubations onboard. Samples are preserved frozen and analyzed in the laboratory using a very sensitive fluorometric technique that allows working with small numbers of individuals of the desired species.

Characterization of III nitride materials and devices by secondary ion mass spectrometry

Secondary ion mass spectrometry (SIMS) is an excellent technique to characterize III nitride materials and devices (dopants, impurities, and composition). Using empirical standards, the ion yield trends are derived for III nitride matrices to enable quantitative and high precision characterization of both major and impurity elements. The technique can be employed to investigate the control of purity and doping, determine growth rate and composition, as well as reveal the structure of finished optoelectronic and electronic devices. SIMS is thus a powerful tool for failure analysis, reverse engineering, and concurrent engineering.

Photo Modified Growth of GaAs by Chemical Beam Epitaxy

AbstractWe report the photo modified growth of GaAs by chemical beam epitaxy at substrate temperatures in the range 335 to 670°C using triethygallium (TEG) and arsine. A mercury-xenon lamp (electrical power 200 W) provided the irradiation for the photoassisted growth. The growth was monitored in real time by laser reflectometry (LR) using a 670 nm semiconductor laser, and the optically determined growth rate agreed with that obtained from the layer thickness measured by cross sectional transmission electron microscopy. The observed photo-enhancement of the growth rate at low substrate temperatures and inhibition at high substrate temperatures is thermal in origin, consistent with raising the substrate temperature by 10±3°C. Cross sectional transmission electron microscopy showed that the photoassisted layers are essentially free from dislocations

Model of the adsorption/desorption kinetics on a growing III–V compound surface

A kinetic approach for surface processes occurring on growing III–V compound (001)-oriented surfaces is proposed. The model assumes the processes proceeding in a single adsorption layer. Four kinetic constants are introduced to describe species desorption, incorporation of atoms from adsorption layer to crystal and decomposition of the crystal. The approach allows one to determine growth rate of the crystal, conditions of extra phase appearance on the surface, minimum temperature of epitaxy and temperature of congruent evaporation, sticking coefficients of Group V species on the growing surface, etc. The proposed model is verified by comparing the theoretical predictions with available experimental data obtained for the GaAs(001) surface.

Validation of Predictive Mathematical Models Describing the Growth of Listeria monocytogenes

Growth of Listeria monocytogenes and Listeria innocua in commercially available sterile homogeneous foods was investigated at different temperatures, pH values, and NaCl concentrations. Growth data were fitted to the Gompertz equation and the resulting growth kinetics were compared with predictions from the Pathogen Modeling Program and Food MicroModel. In general, good agreement was obtained when comparing growth rates and generation times for both models. Differences were observed when comparing lag phases, which ranged from 117 h shorter to 4.9 h longer than predicted for L. monocytogenes. Despite differences in lag phase, under most conditions, the models gave good predictions of microbial growth. Predictive modeling appears to be a useful tool in determining growth rates of Listeria in foods.

Diurnal patterns of stem extension growth in peach (Prunus persica): Temperature and fluctuations in water status determine growth rate

Field measurements of stem extension growth rate in peach (Prunus persica [L.] Batsch) exhibited a consistent diurnal pattern. Stem extension rate was lowest in the early morning and increased throughout the day. In the late afternoon, 2–3‐fold increases in extension rate occurred and were sustained for 2 to 4 h. After this growth surge, rates precipitously declined and remained low during the night. The temperature response of stem growth rate at constant water potential was determined using potted trees in a dark growth chamber. Under such conditions, stem growth rate was strongly dependent on air temperature. In the field, the observed stem growth rate deviated from that predicted on the basis of temperature. These deviations were proportional to the rate of change in stem water potential. A model was constructed to predict diurnal patterns of stem extension rate using temperature and water potential data. The model was tested using data from undisturbed trees and from trees in which water potential was artificially manipulated. Growth patterns predicted by the model were in general agreement with observed rates.

Diurnal patterns of stem extension growth in peach (Prunus persica): Temperature and fluctuations in water status determine growth rate

Diurnal patterns of stem extension growth in peach (Prunus persica): Temperature and fluctuations in water status determine growth rate