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Sample records for affected growth rate

  1. Family Poverty Affects the Rate of Human Infant Brain Growth

    PubMed Central

    Hanson, Jamie L.; Hair, Nicole; Shen, Dinggang G.; Shi, Feng; Gilmore, John H.; Wolfe, Barbara L.; Pollak, Seth D.

    2013-01-01

    Living in poverty places children at very high risk for problems across a variety of domains, including schooling, behavioral regulation, and health. Aspects of cognitive functioning, such as information processing, may underlie these kinds of problems. How might poverty affect the brain functions underlying these cognitive processes? Here, we address this question by observing and analyzing repeated measures of brain development of young children between five months and four years of age from economically diverse backgrounds (n = 77). In doing so, we have the opportunity to observe changes in brain growth as children begin to experience the effects of poverty. These children underwent MRI scanning, with subjects completing between 1 and 7 scans longitudinally. Two hundred and three MRI scans were divided into different tissue types using a novel image processing algorithm specifically designed to analyze brain data from young infants. Total gray, white, and cerebral (summation of total gray and white matter) volumes were examined along with volumes of the frontal, parietal, temporal, and occipital lobes. Infants from low-income families had lower volumes of gray matter, tissue critical for processing of information and execution of actions. These differences were found for both the frontal and parietal lobes. No differences were detected in white matter, temporal lobe volumes, or occipital lobe volumes. In addition, differences in brain growth were found to vary with socioeconomic status (SES), with children from lower-income households having slower trajectories of growth during infancy and early childhood. Volumetric differences were associated with the emergence of disruptive behavioral problems. PMID:24349025

  2. Family poverty affects the rate of human infant brain growth.

    PubMed

    Hanson, Jamie L; Hair, Nicole; Shen, Dinggang G; Shi, Feng; Gilmore, John H; Wolfe, Barbara L; Pollak, Seth D

    2013-01-01

    Living in poverty places children at very high risk for problems across a variety of domains, including schooling, behavioral regulation, and health. Aspects of cognitive functioning, such as information processing, may underlie these kinds of problems. How might poverty affect the brain functions underlying these cognitive processes? Here, we address this question by observing and analyzing repeated measures of brain development of young children between five months and four years of age from economically diverse backgrounds (n = 77). In doing so, we have the opportunity to observe changes in brain growth as children begin to experience the effects of poverty. These children underwent MRI scanning, with subjects completing between 1 and 7 scans longitudinally. Two hundred and three MRI scans were divided into different tissue types using a novel image processing algorithm specifically designed to analyze brain data from young infants. Total gray, white, and cerebral (summation of total gray and white matter) volumes were examined along with volumes of the frontal, parietal, temporal, and occipital lobes. Infants from low-income families had lower volumes of gray matter, tissue critical for processing of information and execution of actions. These differences were found for both the frontal and parietal lobes. No differences were detected in white matter, temporal lobe volumes, or occipital lobe volumes. In addition, differences in brain growth were found to vary with socioeconomic status (SES), with children from lower-income households having slower trajectories of growth during infancy and early childhood. Volumetric differences were associated with the emergence of disruptive behavioral problems.

  3. Crack growth rates of irradiated austenitic stainless steel weld heat affected zone in BWR environments.

    SciTech Connect

    Chopra, O. K.; Alexandreanu, B.; Gruber, E. E.; Daum, R. S.; Shack, W. J.; Energy Technology

    2006-01-31

    Austenitic stainless steels (SSs) are used extensively as structural alloys in the internal components of reactor pressure vessels because of their superior fracture toughness. However, exposure to high levels of neutron irradiation for extended periods can exacerbate the corrosion fatigue and stress corrosion cracking (SCC) behavior of these steels by affecting the material microchemistry, material microstructure, and water chemistry. Experimental data are presented on crack growth rates of the heat affected zone (HAZ) in Types 304L and 304 SS weld specimens before and after they were irradiated to a fluence of 5.0 x 10{sup 20} n/cm{sup 2} (E > 1 MeV) ({approx} 0.75 dpa) at {approx}288 C. Crack growth tests were conducted under cycling loading and long hold time trapezoidal loading in simulated boiling water reactor environments on Type 304L SS HAZ of the H5 weld from the Grand Gulf reactor core shroud and on Type 304 SS HAZ of a laboratory-prepared weld. The effects of material composition, irradiation, and water chemistry on growth rates are discussed.

  4. Temperature-induced elevation of basal metabolic rate does not affect testis growth in great tits.

    PubMed

    Caro, Samuel P; Visser, Marcel E

    2009-07-01

    The timing of reproduction varies from year to year in many bird species. To adjust their timing to the prevailing conditions of that year, birds use cues from their environment. However, the relative importance of these cues, such as the initial predictive (e.g. photoperiod) and the supplemental factors (e.g. temperature), on the seasonal sexual development are difficult to distinguish. In particular, the fine-tuning effect of temperature on gonadal growth is not well known. One way temperature may affect timing is via its strong effect on energy expenditure as gonadal growth is an energy-demanding process. To study the interaction of photoperiod and temperature on gonadal development, we first exposed 35 individually housed male great tits (Parus major) to mid-long days (after 6 weeks of 8 h L:16 h D at 15 degrees C, photoperiod was set to 13 h L:11 h D at 15 degrees C). Two weeks later, for half of the males the temperature was set to 8 degrees C, and for the other half to 22 degrees C. Unilateral laparotomies were performed at weeks 5 (i.e one week before the birds were transferred to mid-long days), 8 and 11 to measure testis size. Two measures of basal metabolic rate (BMR) were performed at the end of the experiment (weeks 11 and 12). Testis size increased significantly during the course of the experiment, but independently of the temperature treatment. BMR was significantly higher in birds exposed to the cold treatment. These results show that temperature-related elevation of BMR did not impair the long-day-induced testis growth in great tits. As a consequence, temperature may not be a crucial cue and/or constraint factor in the fine-tuning of the gonadal recrudescence in male great tits, and testis growth is not a high energy-demanding seasonal process. PMID:19525424

  5. Stiff mutant genes of phycomyces affect turgor pressure and wall mechanical properties to regulate elongation growth rate.

    PubMed

    Ortega, Joseph K E; Munoz, Cindy M; Blakley, Scott E; Truong, Jason T; Ortega, Elena L

    2012-01-01

    Regulation of cell growth is paramount to all living organisms. In plants, algae and fungi, regulation of expansive growth of cells is required for development and morphogenesis. Also, many sensory responses of stage IVb sporangiophores of Phycomyces blakesleeanus are produced by regulating elongation growth rate (growth responses) and differential elongation growth rate (tropic responses). "Stiff" mutant sporangiophores exhibit diminished tropic responses and are found to be defective in at least five genes; madD, E, F, G, and J. Prior experimental research suggests that the defective genes affect growth regulation, but this was not verified. All the growth of the single-celled stalk of the stage IVb sporangiophore occurs in a short region termed the "growth zone." Prior experimental and theoretical research indicates that elongation growth rate of the stage IVb sporangiophore can be regulated by controlling the cell wall mechanical properties within the growth zone and the magnitude of the turgor pressure. A quantitative biophysical model for elongation growth rate is required to elucidate the relationship between wall mechanical properties and turgor pressure during growth regulation. In this study, it is hypothesized that the mechanical properties of the wall within the growth zone of stiff mutant sporangiophores are different compared to wild type (WT). A biophysical equation for elongation growth rate is derived for fungal and plant cells with a growth zone. Two strains of stiff mutants are studied, C149 madD120 (-) and C216 geo- (-). Experimental results demonstrate that turgor pressure is larger but irreversible wall deformation rates within the growth zone and growth zone length are smaller for stiff mutant sporangiophores compared to WT. These findings can explain the diminished tropic responses of the stiff mutant sporangiophores. It is speculated that the defective genes affect the amount of wall-building material delivered to the inner cell wall.

  6. Density but not climate affects the population growth rate of guanacos ( Lama guanicoe) (Artiodactyla, Camelidae)

    PubMed Central

    Zubillaga, María; Skewes, Oscar; Soto, Nicolás; Rabinovich, Jorge E

    2014-01-01

    We analyzed the effects of population density and climatic variables on the rate of population growth in the guanaco ( Lama guanicoe), a wild camelid species in South America. We used a time series of 36 years (1977-2012) of population sampling in Tierra del Fuego, Chile. Individuals were grouped in three age-classes: newborns, juveniles, and adults; for each year a female population transition matrix was constructed, and the population growth rate (λ) was estimated for each year as the matrix highest positive eigenvalue. We applied a regression analysis with finite population growth rate (λ) as dependent variable, and total guanaco population, sheep population, annual mean precipitation, and winter mean temperature as independent variables, with and without time lags. The effect of guanaco population size was statistically significant, but the effects of the sheep population and the climatic variables on guanaco population growth rate were not statistically significant. PMID:25187878

  7. The thiamine content of phytoplankton cells is affected by abiotic stress and growth rate.

    PubMed

    Sylvander, Peter; Häubner, Norbert; Snoeijs, Pauline

    2013-04-01

    Thiamine (vitamin B1) is produced by many plants, algae and bacteria, but by higher trophic levels, it must be acquired through the diet. We experimentally investigated how the thiamine content of six phytoplankton species belonging to five different phyla is affected by abiotic stress caused by changes in temperature, salinity and photon flux density. Correlations between growth rate and thiamine content per cell were negative for the five eukaryotic species, but not for the cyanobacterium Nodularia spumigena. We demonstrate a high variability in thiamine content among phytoplankton species, with the highest content in N. spumigena. Salinity was the factor with the strongest effect, followed by temperature and photon flux density, although the responses varied between the investigated phytoplankton species. Our results suggest that regime shifts in phytoplankton community composition through large-scale environmental changes has the potential to alter the thiamine availability for higher trophic levels. A decreased access to this essential vitamin may have serious consequences for aquatic food webs. PMID:23263236

  8. Collaborative Project: Understanding the Chemical Processes tat Affect Growth rates of Freshly Nucleated Particles

    SciTech Connect

    McMurry, Peter; Smuth, James

    2015-11-12

    This final technical report describes our research activities that have, as the ultimate goal, the development of a model that explains growth rates of freshly nucleated particles. The research activities, which combine field observations with laboratory experiments, explore the relationship between concentrations of gas-phase species that contribute to growth and the rates at which those species are taken up. We also describe measurements of the chemical composition of freshly nucleated particles in a variety of locales, as well as properties (especially hygroscopicity) that influence their effects on climate.

  9. Final Report: "Collaborative Project. Understanding the Chemical Processes That Affect Growth Rates of Freshly Nucleated Particles"

    SciTech Connect

    Smith, James N.; McMurry, Peter H.

    2015-11-12

    This final technical report describes our research activities that have, as the ultimate goal, the development of a model that explains growth rates of freshly nucleated particles. The research activities, which combine field observations with laboratory experiments, explore the relationship between concentrations of gas-phase species that contribute to growth and the rates at which those species are taken up. We also describe measurements of the chemical composition of freshly nucleated particles in a variety of locales, as well as properties (especially hygroscopicity) that influence their effects on climate. Our measurements include a self-organized, DOE-ARM funded project at the Southern Great Plains site, the New Particle Formation Study (NPFS), which took place during spring 2013. NPFS data are available to the research community on the ARM data archive, providing a unique suite observations of trace gas and aerosols that are associated with the formation and growth of atmospheric aerosol particles.

  10. Runoff nutrient transport as affected by land application method, swine growth stage, and runoff rate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This study was conducted to measure the effects of slurry application method, swine growth stage, and flow rate on runoff nutrient transport. Swine slurry was obtained from production units containing grower pigs, finisher pigs, or sows and gilts. The swine slurry was applied using broadcast, disk, ...

  11. Growth rate and nutrient limitation affect the transport of Rhodococcus sp. strain DN22 through sand.

    PubMed

    Priestley, James T; Coleman, Nicholas V; Duxbury, Trevor

    2006-12-01

    Rhodococcus strain DN22 grows on the nitramine explosive RDX as a sole nitrogen source, and is potentially useful for bioremediation of explosives-contaminated soil. In order for strain DN22 to be effectively applied in situ, inoculum cells must reach zones of RDX contamination via passive transport, a process that is difficult to predict at field-scale. We examined the effect of growth conditions on the transport of DN22 cells through sand columns, using chemostat-grown cultures. Strain DN22 formed smaller coccoid cells at low dilution rate (0.02 h(-1)) and larger rods at high dilution rate (0.1 h(-1)). Under all nutrient limitation conditions studied, smaller cells grown at low dilution rate were retained more strongly by sand columns than larger cells grown at high dilution rate. At a dilution rate of 0.05, cells from nitrate-limited cultures were retained more strongly than cells from RDX-limited or succinate-limited cultures. Breakthrough concentrations (C/C (0)) from sand columns ranged from 0.04 (nitrate-limited, D=0.02 h(-1)) to 0.98 (succinate-limited, D=0.1 h(-1)). The observed strong effect of culture conditions on transport of DN22 cells emphasizes the importance of physiology studies in guiding the development of bioremediation technologies.

  12. Feed and feeding regime affect growth rate and gonadosomatic index of adult zebrafish (Danio rerio).

    PubMed

    Gonzales, John M; Law, Sheran Hiu Wan

    2013-12-01

    A 5-week study was conducted to evaluate commercially available Artemia, Ziegler zebrafish diet, and Calamac diet fed in five different feeding regimes on the growth and reproductive development of 7-month-old zebrafish. Zebrafish were fed to satiation three times daily during the normal work week and twice daily during the weekend and holidays. Zebrafish in dietary groups CCC (Calamac three times daily) and CCA (Calamac twice daily, Artemia once daily) had a significantly (p<0.05) greater weight gain and specific growth rate as compared to all other dietary groups. Male zebrafish in dietary group 5 had significantly larger gonadosomatic index (GSI) values than all other groups, while female zebrafish in dietary group CCC had significantly larger GSI values than all other groups. No differences in the fatty acid content of female gonads were detected. Zebrafish fed solely Artemia had the greatest weight loss and lowest GSI values. Preliminary evidence of protein sparing in zebrafish is reported. Collectively, this study sheds more light into the effects of the use of commercially available feeds and feeding regime on the rearing of zebrafish. PMID:23902461

  13. Feed and Feeding Regime Affect Growth Rate and Gonadosomatic Index of Adult Zebrafish (Danio Rerio)

    PubMed Central

    Law, Sheran Hiu Wan

    2013-01-01

    Abstract A 5-week study was conducted to evaluate commercially available Artemia, Ziegler zebrafish diet, and Calamac diet fed in five different feeding regimes on the growth and reproductive development of 7-month-old zebrafish. Zebrafish were fed to satiation three times daily during the normal work week and twice daily during the weekend and holidays. Zebrafish in dietary groups CCC (Calamac three times daily) and CCA (Calamac twice daily, Artemia once daily) had a significantly (p<0.05) greater weight gain and specific growth rate as compared to all other dietary groups. Male zebrafish in dietary group 5 had significantly larger gonadosomatic index (GSI) values than all other groups, while female zebrafish in dietary group CCC had significantly larger GSI values than all other groups. No differences in the fatty acid content of female gonads were detected. Zebrafish fed solely Artemia had the greatest weight loss and lowest GSI values. Preliminary evidence of protein sparing in zebrafish is reported. Collectively, this study sheds more light into the effects of the use of commercially available feeds and feeding regime on the rearing of zebrafish. PMID:23902461

  14. Feed and feeding regime affect growth rate and gonadosomatic index of adult zebrafish (Danio rerio).

    PubMed

    Gonzales, John M; Law, Sheran Hiu Wan

    2013-12-01

    A 5-week study was conducted to evaluate commercially available Artemia, Ziegler zebrafish diet, and Calamac diet fed in five different feeding regimes on the growth and reproductive development of 7-month-old zebrafish. Zebrafish were fed to satiation three times daily during the normal work week and twice daily during the weekend and holidays. Zebrafish in dietary groups CCC (Calamac three times daily) and CCA (Calamac twice daily, Artemia once daily) had a significantly (p<0.05) greater weight gain and specific growth rate as compared to all other dietary groups. Male zebrafish in dietary group 5 had significantly larger gonadosomatic index (GSI) values than all other groups, while female zebrafish in dietary group CCC had significantly larger GSI values than all other groups. No differences in the fatty acid content of female gonads were detected. Zebrafish fed solely Artemia had the greatest weight loss and lowest GSI values. Preliminary evidence of protein sparing in zebrafish is reported. Collectively, this study sheds more light into the effects of the use of commercially available feeds and feeding regime on the rearing of zebrafish.

  15. Bacterial Respiration and Growth Rates Affect the Feeding Preferences, Brood Size and Lifespan of Caenorhabditis elegans

    PubMed Central

    Yu, Li; Yan, Xiaomei; Ye, Chenglong; Zhao, Haiyan; Chen, Xiaoyun; Hu, Feng; Li, Huixin

    2015-01-01

    Bacteria serve as live food and nutrients for bacterial-feeding nematodes (BFNs) in soils, and influence nematodes behavior and physiology through their metabolism. Five bacterial taxa (Bacillus amyloliquefaciens JX1, Variovorax sp. JX14, Bacillus megaterium JX15, Pseudomonas fluorescens Y1 and Escherichia coli OP50) and the typical BFN Caenorhabditis elegans were selected to study the effects of bacterial respiration and growth rates on the feeding preferences, brood size and lifespan of nematodes. P. fluorescens Y1 and E. coli OP50 were found to be more active, with high respiration and rapid growth, whereas B. amyloliquefaciens JX1 and B. megaterium JX15 were inactive. The nematode C. elegans preferred active P. fluorescens Y1 and E. coli OP50 obviously. Furthermore, worms that fed on these two active bacteria produced more offspring but had shorter lifespan, while inactive and less preferred bacteria had increased nematodes lifespan and decreased the brood size. Based on these results, we propose that the bacterial activity may influence the behavior and life traits of C. elegans in the following ways: (1) active bacteria reproduce rapidly and emit high levels of CO2 attracting C. elegans; (2) these active bacteria use more resources in the nematodes’ gut to sustain their survival and reproduction, thereby reducing the worm's lifespan; (3) inactive bacteria may provide less food for worms than active bacteria, thus increasing nematodes lifespan but decreasing their fertility. Nematodes generally require a balance between their preferred foods and beneficial foods, only preferred food may not be beneficial for nematodes. PMID:26222828

  16. Atmospheric oxygen level affects growth trajectory, cardiopulmonary allometry and metabolic rate in the American alligator (Alligator mississippiensis)

    PubMed Central

    Owerkowicz, Tomasz; Elsey, Ruth M.; Hicks, James W.

    2009-01-01

    Summary Recent palaeoatmospheric models suggest large-scale fluctuations in ambient oxygen level over the past 550 million years. To better understand how global hypoxia and hyperoxia might have affected the growth and physiology of contemporary vertebrates, we incubated eggs and raised hatchlings of the American alligator. Crocodilians are one of few vertebrate taxa that survived these global changes with distinctly conservative morphology. We maintained animals at 30°C under chronic hypoxia (12% O2), normoxia (21% O2) or hyperoxia (30% O2). At hatching, hypoxic animals were significantly smaller than their normoxic and hyperoxic siblings. Over the course of 3 months, post-hatching growth was fastest under hyperoxia and slowest under hypoxia. Hypoxia, but not hyperoxia, caused distinct scaling of major visceral organs–reduction of liver mass, enlargement of the heart and accelerated growth of lungs. When absorptive and post-absorptive metabolic rates were measured in juvenile alligators, the increase in oxygen consumption rate due to digestion/absorption of food was greatest in hyperoxic alligators and smallest in hypoxic ones. Hyperoxic alligators exhibited the lowest breathing rate and highest oxygen consumption per breath. We suggest that, despite compensatory cardiopulmonary remodelling, growth of hypoxic alligators is constrained by low atmospheric oxygen supply, which may limit their food utilisation capacity. Conversely, the combination of elevated metabolism and low cost of breathing in hyperoxic alligators allows for a greater proportion of metabolised energy to be available for growth. This suggests that growth and metabolic patterns of extinct vertebrates would have been significantly affected by changes in the atmospheric oxygen level. PMID:19376944

  17. Rate of Physical Growth and Its Affect on Head Start Children's Motor and Cognitive Development.

    ERIC Educational Resources Information Center

    Marcon, Rebecca A.

    In the United States, growth retardation is higher among low-income children, with adverse cognitive effects of undernutrition more prevalent when combined with poverty. This study examined anthropometric indicators of physical development and their relationship to motor and cognitive development in Head Start children. Motor integration and…

  18. Freshwater environment affects growth rate and muscle fibre recruitment in seawater stages of Atlantic salmon (Salmo salar L.).

    PubMed

    Johnston, Ian A; Manthri, Sujatha; Alderson, Richard; Smart, Alistair; Campbell, Patrick; Nickell, David; Robertson, Billy; Paxton, Charles G M; Burt, M Louise

    2003-04-01

    The influence of freshwater environment on muscle growth in seawater was investigated in an inbred population of farmed Atlantic salmon (Salmo salar L.). The offspring from a minimum of 64 families per group were incubated at either ambient temperature (ambient treatment) or in heated water (heated treatment). Growth was investigated using a mixed-effect statistical model with repeated measures, which included terms for treatment effect and random fish effects for individual growth rate (alpha) and the instantaneous growth rate per unit change in temperature (gamma). Prior to seawater transfer, fish were heavier in the heated (61.6+/-1.0 g; N=298) than in the ambient (34.1+/-0.4 g; N=206) treatments, reflecting their greater growth opportunity: 4872 degree-days and 4281 degree-days, respectively. However, the subsequent growth rate of the heated group was lower, such that treatments had a similar body mass (3.7-3.9 kg) after approximately 450 days in seawater. The total cross-sectional area of fast muscle and the number (FN) and size distribution of the fibres was determined in a subset of the fish. We tested the hypothesis that freshwater temperature regime affected the rate of recruitment and hypertrophy of muscle fibres. There were differences in FN between treatments and a significant age x treatment interaction but no significant cage effect (ANOVA). Cessation of fibre recruitment was identified by the absence of fibres of <10 micro m diameter. The maximum fibre number was 22.4% more in the ambient (9.3 x 10(5)+/-2.0 x 10(4) than in the heated (7.6 x 10(5)+/-1.5 x 10(4)) treatments (N=44 and 40 fish, respectively; P<0.001). For fish that had completed fibre recruitment, there was a significant correlation between FN and individual growth rate, explaining 35% of the total variation. The density of myogenic progenitor cells was quantified using an antibody to c-met and was approximately 2-fold higher in the ambient than in the heated group, equivalent to 2-3% of

  19. Density-dependent processes in leaf beetles feeding on purple loosestrife: aggregative behaviour affecting individual growth rates.

    PubMed

    Hambäck, P A

    2010-10-01

    Aggregative responses are commonly observed in insects, including chrysomelids, affecting both individual and population growth rates. In two closely related chrysomelid beetles (Galerucella calmariensis and G. pusilla) feeding on purple loosestrife (Lythrum salicaria), recent studies suggest that male-produced pheromones may cause both inter- and intraspecific attraction. This paper further examines the causes and consequences of feeding aggregations in these species. Olfactometer studies confirm previous findings, showing cross-species attraction to damaged plants, but suggest that also damaged induced plant volatiles may be involved. In addition, the studies suggest that the cross-species attraction observed in previous studies have asymmetric effects on the two beetles. Galerucella pusilla was more attracted to damage by G. calmariensis than to damage by conspecifics. Laboratory and field data suggest that feeding aggregations in these species increase pupal mass, at least at low to intermediate larval densities. This positive feedback may have important consequences for the spatiotemporal dynamics and as a consequence on the role of the two chrysomelid beetles on biological control of purple loosestrife.

  20. Maternal deprivation in neonatal rats of different conditions affects growth rate, circadian clock, and stress responsiveness differentially.

    PubMed

    Yamazaki, Ayano; Ohtsuki, Yoshio; Yoshihara, Toshihiro; Honma, Sato; Honma, Ken-Ichi

    2005-09-15

    Effects of periodic maternal deprivation (MD) were examined in rat pups on growth rate, circadian phase and period at weaning, and stress responsiveness in adulthood. MD was performed from postnatal day 1 to day 6 or day 7, with or without keeping ambient temperature at 37 degrees C and humidity at 70-80% during deprivation. Times of day and length of MD were also changed. Body weights were significantly reduced at weaning in MD12 (MD for 12 h) and MD6am (MD for 6 h in the morning) pups, whereas they were not changed in MD6pm (MD in the afternoon) and all MD3 groups. At 8 weeks old, body weight was still significantly lower in MD12 than the control, but not different from the control in other groups. Circadian phases of free-running locomotor rhythm at weaning were almost reversed in MD12, MD6am and MD6pm as compared with those in the control. Intermediate phase-shifts were observed in MD3Eam (3 h MD in the first quarter of the light phase; early am) and MD3Lam (late am; the second quarter), whereas no phase-shift was detected in MD3Epm (early pm; the third quarter) and MD3Lpm (late pm; the fourth quarter). Elevation of plasma corticosterone level after novelty exposure at 8 weeks old was more robustly in MD12 and MD3Lam than in the control, but the hormone response in MD3Lpm was not different from the control. Keeping ambient temperature at 37 degrees C during MD did not rescue the MD-induced body weight loss, but attenuated the phase-shifts of the circadian clock, and completely cancelled the stress-induced hormone response in MD12 rats. These findings indicate that MD in rat pups differentially affects growth rate, circadian clock, and stress responsiveness in adulthood, depending on time of day, length of MD and ambient temperature during MD. PMID:16126237

  1. Growth rates made easy.

    PubMed

    Hall, Barry G; Acar, Hande; Nandipati, Anna; Barlow, Miriam

    2014-01-01

    In the 1960s-1980s, determination of bacterial growth rates was an important tool in microbial genetics, biochemistry, molecular biology, and microbial physiology. The exciting technical developments of the 1990s and the 2000s eclipsed that tool; as a result, many investigators today lack experience with growth rate measurements. Recently, investigators in a number of areas have started to use measurements of bacterial growth rates for a variety of purposes. Those measurements have been greatly facilitated by the availability of microwell plate readers that permit the simultaneous measurements on up to 384 different cultures. Only the exponential (logarithmic) portions of the resulting growth curves are useful for determining growth rates, and manual determination of that portion and calculation of growth rates can be tedious for high-throughput purposes. Here, we introduce the program GrowthRates that uses plate reader output files to automatically determine the exponential portion of the curve and to automatically calculate the growth rate, the maximum culture density, and the duration of the growth lag phase. GrowthRates is freely available for Macintosh, Windows, and Linux. We discuss the effects of culture volume, the classical bacterial growth curve, and the differences between determinations in rich media and minimal (mineral salts) media. This protocol covers calibration of the plate reader, growth of culture inocula for both rich and minimal media, and experimental setup. As a guide to reliability, we report typical day-to-day variation in growth rates and variation within experiments with respect to position of wells within the plates.

  2. Does coastal lagoon habitat quality affect fish growth rate and their recruitment? Insights from fishing and acoustic surveys

    NASA Astrophysics Data System (ADS)

    Brehmer, P.; Laugier, T.; Kantoussan, J.; Galgani, F.; Mouillot, D.

    2013-07-01

    Ensuring the sustainability of fish resources necessitates understanding their interaction with coastal habitats, which is becoming ever more challenging in the context of ever increasing anthropogenic pressures. The ability of coastal lagoons, exposed to major sources of disturbance, to provide resources and suitable habitats for growth and survival of juvenile fish is especially important. We analysed three lagoons with different ecological statuses and habitat quality on the basis of their eutrophication and ecotoxicity (Trix test) levels. Fish abundances were sampled using fishing and horizontal beaming acoustic surveys with the same protocols in the same year. The relative abundance of Anguilla anguilla, Dicentrarchus labrax or the Mugilidae group was not an indicator of habitat quality, whereas Atherina boyeri and Sparus aurata appeared to be more sensitive to habitat quality. Fish abundance was higher in the two lagoons with high eutrophication and ecotoxicity levels than in the less impacted lagoon, while fish sizes were significantly higher in the two most severely impacted lagoons. This leads us to suggest low habitat quality may increase fish growth rate (by the mean of a cascading effect), but may reduce lagoon juvenile abundance by increasing larval mortality. Such a hypothesis needs to be further validated using greater investigations which take into account more influences on fish growth and recruitment in such variable environments under complex multi-stressor conditions.

  3. Elevated atmospheric CO(2) affects the chemical quality of brassica plants and the growth rate of the specialist, Plutella xylostella, but not the generalist, Spodoptera littoralis.

    PubMed

    Reddy, Gadi V P; Tossavainen, Paula; Nerg, Anne-Marja; Holopainen, Jarmo K

    2004-06-30

    Cabbage, Brassica oleracea subsp. capitata (cv. Lennox and Rinda), and oilseed rape, Brassica rapa subsp. oleifera (cv. Valo and Tuli), plants were grown under ambient CO(2) (360 ppm) or elevated CO(2) (720 ppm) at 23/18 degrees C and under a photoperiod of 22/2 h light (250 micromol m(-)(2) s(-)(1))/dark regime for up to 5 weeks. Afterward, the performance of the crucifer specialist Plutella xylostella (Lepidoptera: Plutellidae) and the generalist Spodoptera littoralis (Lepidoptera: Noctuidae) on those plants was studied. The mean relative growth rate (RGR) of P. xylostella larvae, feeding on both cultivars of oilseed rape or on the Lennox cultivar of cabbage leaves grown at an elevated CO(2) concentration, was significantly reduced as compared to ambient CO(2). A negative larval growth rate at elevated CO(2) was observed for P. xylostella on both oilseed rape cultivars, but the growth rate was reduced but positive on cabbage. Conversely, the RGR of S. littoralis on either plant species was not affected by CO(2) treatment but was lower on cabbage cv. Rinda than on cv. Lennox. The mortality of the larvae was not affected by CO(2) treatment either. At the same time, elevated CO(2) significantly decreased the concentrations of leaf phytochemical constituents in oilseed rape, i.e., total phenolics and total nitrogen, but not in cabbage. The effect of elevated CO(2) on the leaf glucosinolate concentrations of both plant species was marginal. In addition, the observed significant changes in individual glucosinolate concentrations of oilseed rape leaves were not consistent among cultivars. However, our results demonstrate for the first time quite strong effects of CO(2) enrichment on the larval performance of P. xylostella, which is an important pest of Brassica plants around the world. Further studies are still required to increase our understanding of why elevated CO(2) differently affects the performance of specialist and generalist insect herbivores on Brassica

  4. Campylobacter colonization and proliferation in the broiler chicken upon natural field challenge is not affected by the bird growth rate or breed.

    PubMed

    Gormley, Fraser J; Bailey, Richard A; Watson, Kellie A; McAdam, Jim; Avendaño, Santiago; Stanley, William A; Koerhuis, Alfons N M

    2014-11-01

    The zoonotic association between Campylobacter bacteria in poultry and humans has been characterized by decades of research which has attempted to elucidate the epidemiology of this complex relationship and to reduce carriage within poultry. While much work has focused on the mechanisms facilitating its success in contaminating chicken flocks (and other animal hosts), it remains difficult to consistently exclude Campylobacter under field conditions. Within the United Kingdom poultry industry, various bird genotypes with widely varying growth rates are available to meet market needs and consumer preferences. However, little is known about whether any differences in Campylobacter carriage exist across this modern broiler range. The aim of this study was to establish if a relationship exists between growth rate or breed and cecal Campylobacter concentration after natural commercial flock Campylobacter challenge. In one investigation, four pure line genotypes of various growth rates were grown together, while in the second, eight different commercial broiler genotypes were grown individually. In both studies, the Campylobacter concentration was measured in the ceca at 42 days of age, revealing no significant difference in cecal load between birds of different genotypes both in mixed- and single-genotype pens. This is important from a public health perspective and suggests that other underlying reasons beyond genotype are likely to control and affect Campylobacter colonization within chickens. Further studies to gain a better understanding of colonization dynamics and subsequent proliferation are needed, as are novel approaches to reduce the burden in poultry.

  5. Greenhouse gas growth rates

    PubMed Central

    Hansen, James; Sato, Makiko

    2004-01-01

    We posit that feasible reversal of the growth of atmospheric CH4 and other trace gases would provide a vital contribution toward averting dangerous anthropogenic interference with global climate. Such trace gas reductions may allow stabilization of atmospheric CO2 at an achievable level of anthropogenic CO2 emissions, even if the added global warming constituting dangerous anthropogenic interference is as small as 1°C. A 1°C limit on global warming, with canonical climate sensitivity, requires peak CO2 ≈ 440 ppm if further non-CO2 forcing is +0.5 W/m2, but peak CO2 ≈ 520 ppm if further non-CO2 forcing is -0.5 W/m2. The practical result is that a decline of non-CO2 forcings allows climate forcing to be stabilized with a significantly higher transient level of CO2 emissions. Increased “natural” emissions of CO2, N2O, and CH4 are expected in response to global warming. These emissions, an indirect effect of all climate forcings, are small compared with human-made climate forcing and occur on a time scale of a few centuries, but they tend to aggravate the task of stabilizing atmospheric composition. PMID:15536130

  6. Greenhouse gas growth rates

    NASA Astrophysics Data System (ADS)

    Hansen, James; Sato, Makiko

    2004-11-01

    We posit that feasible reversal of the growth of atmospheric CH4 and other trace gases would provide a vital contribution toward averting dangerous anthropogenic interference with global climate. Such trace gas reductions may allow stabilization of atmospheric CO2 at an achievable level of anthropogenic CO2 emissions, even if the added global warming constituting dangerous anthropogenic interference is as small as 1°C. A 1°C limit on global warming, with canonical climate sensitivity, requires peak CO2 440 ppm if further non-CO2 forcing is +0.5 W/m2, but peak CO2 520 ppm if further non-CO2 forcing is -0.5 W/m2. The practical result is that a decline of non-CO2 forcings allows climate forcing to be stabilized with a significantly higher transient level of CO2 emissions. Increased "natural" emissions of CO2, N2O, and CH4 are expected in response to global warming. These emissions, an indirect effect of all climate forcings, are small compared with human-made climate forcing and occur on a time scale of a few centuries, but they tend to aggravate the task of stabilizing atmospheric composition.

  7. Greenhouse gas growth rates.

    PubMed

    Hansen, James; Sato, Makiko

    2004-11-16

    We posit that feasible reversal of the growth of atmospheric CH(4) and other trace gases would provide a vital contribution toward averting dangerous anthropogenic interference with global climate. Such trace gas reductions may allow stabilization of atmospheric CO(2) at an achievable level of anthropogenic CO(2) emissions, even if the added global warming constituting dangerous anthropogenic interference is as small as 1 degrees C. A 1 degrees C limit on global warming, with canonical climate sensitivity, requires peak CO(2) approximately 440 ppm if further non-CO(2) forcing is +0.5 W/m(2), but peak CO(2) approximately 520 ppm if further non-CO(2) forcing is -0.5 W/m(2). The practical result is that a decline of non-CO(2) forcings allows climate forcing to be stabilized with a significantly higher transient level of CO(2) emissions. Increased "natural" emissions of CO(2), N(2)O, and CH(4) are expected in response to global warming. These emissions, an indirect effect of all climate forcings, are small compared with human-made climate forcing and occur on a time scale of a few centuries, but they tend to aggravate the task of stabilizing atmospheric composition.

  8. Growth rate of Escherichia coli.

    PubMed Central

    Marr, A G

    1991-01-01

    It should be possible to predict the rate of growth of Escherichia coli of a given genotype in a specified environment. The idea that the rate of synthesis of ATP determines the rate of growth and that the yield of ATP determines the yield of growth is entrenched in bacterial physiology, yet this idea is inconsistent with experimental results. In minimal media the growth rate and yield vary with the carbon source in a manner independent of the rate of formation and yield of ATP. With acetate as the carbon source, anapleurotic reactions, not ATP synthesis, limit the growth rate. For acetate and other gluconeogenic substrates the limiting step appears to be the formation of triose phosphate. I conclude that the rate of growth is controlled by the rate of formation of a precursor metabolite and, thus, of monomers such as amino acids derived from it. The protein-synthesizing system is regulated according to demand for protein synthesis. I examine the conjecture that the signal for this regulation is the ratio of uncharged tRNA to aminoacyl-tRNA, that this signal controls the concentration of guanosine tetraphosphate, and that the concentration of guanosine tetraphosphate controls transcription of rrn genes. Differential equations describing this system were solved numerically for steady states of growth; the computed values of ribosomes and guanosine tetraphosphate and the maximal growth rate agree with experimental values obtained from the literature of the past 35 years. These equations were also solved for dynamical states corresponding to nutritional shifts up and down. PMID:1886524

  9. Effect of massing on larval growth rate.

    PubMed

    Johnson, Aidan P; Wallman, James F

    2014-08-01

    Estimation of minimum postmortem interval commonly relies on predicting the age of blowfly larvae based on their size and an estimate of the temperatures to which they have been exposed throughout their development. The majority of larval growth rate data have been developed using small larval masses in order to avoid excess heat generation. The current study collected growth rate data for larvae at different mass volumes, and assessed the temperature production of these masses, for two forensically important blow fly species, Chrysomya rufifacies and Calliphora vicina. The growth rate of larvae in a small mass, exposed to the higher temperatures equivalent to those experienced by large masses, was also assessed to determine if observed differences were due to the known temperature effects of maggot masses. The results showed that temperature production increased with increasing mass volume, with temperature increases of 11 °C observed in the large Ch. rufifacies masses and increases of 5 °C in the large C. vicina masses. Similarly, the growth rate of the larvae was affected by mass size. The larvae from small masses grown at the higher temperatures experienced by large masses displayed an initial delay in growth, but then grew at a similar rate to those larvae at a constant 23 °C. Since these larvae from masses of equivalent sizes displayed similar patterns of growth rate, despite differing temperatures, and these growth rates differed from larger masses exposed to the same temperatures, it can be concluded that larval growth rate within a mass may be affected by additional factors other than temperature. Overall, this study highlights the importance of understanding the role of massing in larval development and provides initial developmental data for mass sizes of two forensically important blowfly species commonly encountered in Australian forensic casework.

  10. Solar ultraviolet-B radiation affects seedling emergence, DNA integrity, plant morphology, growth rate, and attractiveness to herbivore insects in Datura ferox

    SciTech Connect

    Ballare, C.L.; Scopel, A.L.; Stapleton, A.E.

    1996-09-01

    To study functional relationships between the effects of solar ultraviolet-B radiation (UV0B) on different aspects of the physiology of a wild plant, we carried out exclusion experiments in the field with the summer annual Datura ferrox L. Solar UV-B incident over Buenos Aires reduced daytime seedling emergence, inhibited stem elongation and leaf expansion, and tended to reduce biomass accumulation during early growth. However, UV-B had no effect on calculated net assimilation rate. Using a monoclonal antibody specific to the cyclobutane-pyrimidine dimer (CPD), we found that plants receiving full sunlight had more CPDs per unit of DNA than plants shielded from solar UV-B, but the positive correlation between UV-B and CPD burden tended to level off at high (near solar) UV-B levels. At our field site, Datura plants were consumed by leaf beetles (Coleoptera), and the proportion of plants attacked by insects declined with the amount of UV-B received during growth. Field experiments showed that plant exposure to solar UV-B reduced the likelihood of leaf beetle attack by one-half. Our results highlight the complexities associated with scaling plant responses to solar UV-B, because they show: (a) a lack of correspondence between UV-B effects on net assimilation rate and whole-plant growth rate, (b) nonlinear UV-B dose-response curves, and (c) UV-B effects of plant attractiveness to natural herbivores. 56 refs., 7 figs.

  11. Different phycobilin antenna organisations affect the balance between light use and growth rate in the cyanobacterium Microcystis aeruginosa and in the cryptophyte Cryptomonas ovata.

    PubMed

    Kunath, Christfried; Jakob, Torsten; Wilhelm, Christian

    2012-03-01

    During the recent years, wide varieties of methodologies have been developed up to the level of commercial use to measure photosynthetic electron transport by modulated chlorophyll a-in vivo fluorescence. It is now widely accepted that the ratio between electron transport rates and new biomass (P (Fl)/B (C)) is not fixed and depends on many factors that are also taxonomically variable. In this study, the balance between photon absorption and biomass production has been measured in two phycobilin-containing phototrophs, namely, a cyanobacterium and a cryptophyte, which differ in their antenna organization. It is demonstrated that the different antenna organization exerts influence on the regulation of the primary photosynthetic reaction and the dissipation of excessively absorbed radiation. Although, growth rates and the quantum efficiency of biomass production of both phototrophs were comparable, the ratio P (Fl)/B (C) was twice as high in the cryptophyte in comparison to the cyanobacterium. It is assumed that this discrepancy is because of differences in the metabolic regulation of cell growth. In the cryptophyte, absorbed photosynthetic energy is used to convert assimilated carbon directly into proteins and lipids, whereas in the cyanobacterium, the photosynthetic energy is preferentially stored as carbohydrates.

  12. Growth rate for blackhole instabilities

    NASA Astrophysics Data System (ADS)

    Prabhu, Kartik; Wald, Robert

    2015-04-01

    Hollands and Wald showed that dynamic stability of stationary axisymmetric black holes is equivalent to positivity of canonical energy on a space of linearised axisymmetric perturbations satisfying certain boundary and gauge conditions. Using a reflection isometry of the background, we split the energy into kinetic and potential parts. We show that the kinetic energy is positive. In the case that potential energy is negative, we show existence of exponentially growing perturbations and further obtain a variational formula for the growth rate.

  13. Long-term data reveal a population decline of the tropical lizard Anolis apletophallus, and a negative affect of el nino years on population growth rate.

    PubMed

    Stapley, Jessica; Garcia, Milton; Andrews, Robin M

    2015-01-01

    Climate change threatens biodiversity worldwide, however predicting how particular species will respond is difficult because climate varies spatially, complex factors regulate population abundance, and species vary in their susceptibility to climate change. Studies need to incorporate these factors with long-term data in order to link climate change to population abundance. We used 40 years of lizard abundance data and local climate data from Barro Colorado Island to ask how climate, total lizard abundance and cohort-specific abundance have changed over time, and how total and cohort-specific abundance relate to climate variables including those predicted to make the species vulnerable to climate change (i.e. temperatures exceeding preferred body temperature). We documented a decrease in lizard abundance over the last 40 years, and changes in the local climate. Population growth rate was related to the previous years' southern oscillation index; increasing following cooler-wetter, la niña years, decreasing following warmer-drier, el nino years. Within-year recruitment was negatively related to rainfall and minimum temperature. This study simultaneously identified climatic factors driving long-term population fluctuations and climate variables influencing short-term annual recruitment, both of which may be contributing to the population decline and influence the population's future persistence.

  14. Growth rates of Chinese and American alligators.

    PubMed

    Herbert, J D; Coulson, T D; Coulson, R A

    2002-04-01

    Growth rates in two closely related species, Alligator mississippiensis (American alligator) and Alligator sinensis (Chinese alligator), were compared under identical conditions for at least 1 year after hatching. When hatched, Chinese alligators were approximately 2/3 the length and approximately 1/2 the weight of American alligator hatchlings. At the end of 1 year of growth in captivity in heated chambers, the Chinese alligators were approximately 1/2 as long and weighed approximately 1/10 as much as American alligator yearlings. When the animals were maintained at 31 degrees C, Chinese alligator food consumption and length gain rates dropped to near zero during autumn and winter and body weights decreased slightly, apparently in response to the change in day length. At constant temperature (31 degrees C), food consumption by American alligators remained high throughout the year. Length gain rates in American alligators decreased slowly as size increased, but were not affected by photoperiod. Daily weight gains in American alligators increased steadily throughout the year. In autumn, provision of artificial light for 18 h a day initially stimulated both length and weight gain in Chinese alligators, but did not affect growth in American alligators. Continuation of the artificial light regimen seemed to cause deleterious effects in the Chinese alligators after several months, however, so that animals exposed to the normal light cycle caught up to and then surpassed the extra-light group in size. Even after removal of the artificial light, it was several months before these extra-light animals reverted to a normal growth pattern. These findings may be of interest to those institutions engaged in captive growth programs intended to provide animals for reintroduction to the wild or to protected habitat. PMID:11897202

  15. Motivated behavioral outcomes affect ratings of attractiveness.

    PubMed

    Bernard, Larry C; Hardy, David J

    2014-12-01

    A relatively new theory of motivation posits that purposeful human behavior may be partly explained by multidimensional individual differences "traits of action" (motives). Its 15 motives can be characterized according to their purpose: individual integrity, competitiveness, and cooperativeness. Existing evidence supports the model on which the motives are based and the reliability and validity of strategies to assess them. This experiment tested whether the hypothetical results of consistent, motivated cooperative and competitive behavior could affect ratings of attractiveness. Male and female participants (N = 98; M age = 18.8, SD = 1.4) were shown 24 opposite-sex facial photos ranging in attractiveness. The photos were paired with one of three conditions representing theoretical outcomes that would result from low, control, and high levels of cooperative and competitive motives. As predicted, outcome descriptions representing high motive strength of six motives statistically significantly affected ratings of attractiveness. This result was independent of sex of participant and consistent with the theory. PMID:25457092

  16. A Werner syndrome protein homolog affects C. elegans development, growth rate, life span and sensitivity to DNA damage by acting at a DNA damage checkpoint.

    PubMed

    Lee, Se-Jin; Yook, Jong-Sung; Han, Sung Min; Koo, Hyeon-Sook

    2004-06-01

    A Werner syndrome protein homolog in C. elegans (WRN-1) was immunolocalized to the nuclei of germ cells, embryonic cells, and many other cells of larval and adult worms. When wrn-1 expression was inhibited by RNA interference (RNAi), a slight reduction in C. elegans life span was observed, with accompanying signs of premature aging, such as earlier accumulation of lipofuscin and tissue deterioration in the head. In addition, various developmental defects, including small, dumpy, ruptured, transparent body, growth arrest and bag of worms, were induced by RNAi. The frequency of these defects was accentuated by gamma-irradiation, implying that they were derived from spontaneous or induced DNA damage. wrn-1(RNAi) worms showed accelerated larval growth irrespective of gamma-irradiation, and pre-meiotic germ cells had an abnormal checkpoint response to DNA replication blockage. These observations suggest that WRN-1 acts as a checkpoint protein for DNA damage and replication blockage. This idea is also supported by an accelerated S phase in wrn-1(RNAi) embryonic cells. wrn-1(RNAi) phenotypes similar to those of Werner syndrome, such as premature aging and short stature, suggest wrn-1-deficient C. elegans as a useful model organism for Werner syndrome. PMID:15115755

  17. River chloride trends in snow-affected urban watersheds: increasing concentrations outpace urban growth rate and are common among all seasons.

    PubMed

    Corsi, Steven R; De Cicco, Laura A; Lutz, Michelle A; Hirsch, Robert M

    2015-03-01

    Chloride concentrations in northern U.S. included in this study have increased substantially over time with average concentrations approximately doubling from 1990 to 2011, outpacing the rate of urbanization in the northern U.S. Historical data were examined for 30 monitoring sites on 19 streams that had chloride concentration and flow records of 18 to 49 years. Chloride concentrations in most studied streams increased in all seasons (13 of 19 in all seasons; 16 of 19 during winter); maximum concentrations occurred during winter. Increasing concentrations during non-deicing periods suggest that chloride was stored in hydrologic reservoirs, such as the shallow groundwater system, during the winter and slowly released in baseflow throughout the year. Streamflow dependency was also observed with chloride concentrations increasing as streamflow decreased, a result of dilution during rainfall- and snowmelt-induced high-flow periods. The influence of chloride on aquatic life increased with time; 29% of sites studied exceeded the concentration for the USEPA chronic water quality criteria of 230 mg/L by an average of more than 100 individual days per year during 2006-2011. The rapid rate of chloride concentration increase in these streams is likely due to a combination of possible increased road salt application rates, increased baseline concentrations, and greater snowfall in the Midwestern U.S. during the latter portion of the study period. PMID:25514764

  18. River chloride trends in snow-affected urban watersheds: increasing concentrations outpace urban growth rate and are common among all seasons.

    PubMed

    Corsi, Steven R; De Cicco, Laura A; Lutz, Michelle A; Hirsch, Robert M

    2015-03-01

    Chloride concentrations in northern U.S. included in this study have increased substantially over time with average concentrations approximately doubling from 1990 to 2011, outpacing the rate of urbanization in the northern U.S. Historical data were examined for 30 monitoring sites on 19 streams that had chloride concentration and flow records of 18 to 49 years. Chloride concentrations in most studied streams increased in all seasons (13 of 19 in all seasons; 16 of 19 during winter); maximum concentrations occurred during winter. Increasing concentrations during non-deicing periods suggest that chloride was stored in hydrologic reservoirs, such as the shallow groundwater system, during the winter and slowly released in baseflow throughout the year. Streamflow dependency was also observed with chloride concentrations increasing as streamflow decreased, a result of dilution during rainfall- and snowmelt-induced high-flow periods. The influence of chloride on aquatic life increased with time; 29% of sites studied exceeded the concentration for the USEPA chronic water quality criteria of 230 mg/L by an average of more than 100 individual days per year during 2006-2011. The rapid rate of chloride concentration increase in these streams is likely due to a combination of possible increased road salt application rates, increased baseline concentrations, and greater snowfall in the Midwestern U.S. during the latter portion of the study period.

  19. River chloride trends in snow-affected urban watersheds: increasing concentrations outpace urban growth rate and are common among all seasons

    USGS Publications Warehouse

    Corsi, Steven R.; DeCicco, Laura A.; Lutz, Michelle A.; Hirsch, Robert M.

    2014-01-01

    Chloride concentrations in northern U.S. included in this study have increased substantially over time with average concentrations approximately doubling from 1990 to 2011, outpacing the rate of urbanization in the northern U.S. Historical data were examined for 30 monitoring sites on 19 streams that had chloride concentration and flow records of 18 to 49 years. Chloride concentrations in most studied streams increased in all seasons (13 of 19 in all seasons; 16 of 19 during winter); maximum concentrations occurred during winter. Increasing concentrations during non-deicing periods suggest that chloride was stored in hydrologic reservoirs, such as the shallow groundwater system, during the winter and slowly released in baseflow throughout the year. Streamflow dependency was also observed with chloride concentrations increasing as streamflow decreased, a result of dilution during rainfall- and snowmelt-induced high-flow periods. The influence of chloride on aquatic life increased with time; 29% of sites studied exceeded the concentration for the USEPA chronic water quality criteria of 230 mg/L by an average of more than 100 individual days per year during 2006–2011. The rapid rate of chloride concentration increase in these streams is likely due to a combination of possible increased road salt application rates, increased baseline concentrations, and greater snowfall in the Midwestern U.S. during the latter portion of the study period.

  20. The evolution of growth trajectories: what limits growth rate?

    PubMed

    Dmitriew, Caitlin M

    2011-02-01

    According to life-history theory, growth rates are subject to strong directional selection due to reproductive and survival advantages associated with large adult body size. Yet, growth is commonly observed to occur at rates lower than the maximum that is physiologically possible and intrinsic growth rates often vary among populations. This implies that slower growth is favoured under certain conditions. Realized growth rate is thus the result of a compromise between the costs and advantages of growing rapidly, and the optimal rate of growth is not equivalent to the fundamental maximum rate. The ecological and evolutionary factors influencing growth rate are reviewed, with particular emphasis on how growth might be constrained by direct fitness costs. Costs of accelerating growth might contribute to the variance in fitness that is not attributable to age or size at maturity, as well as to the variation in life-history strategies observed within and among species. Two main approaches have been taken to study the fitness trade-offs relating to growth rate. First, environmental manipulations can be used to produce treatment groups with different rates of growth. Second, common garden experiments can be used to compare fitness correlates among populations with different intrinsic growth rates. Data from these studies reveal a number of potential costs for growth over both the short and long term. In order to acquire the energy needed for faster growth, animals must increase food intake. Accordingly, in many taxa, the major constraint on growth rate appears to arise from the trade-off between predation risk and foraging effort. However, growth rates are also frequently observed to be submaximal in the absence of predation, suggesting that growth trajectories also impact fitness via other channels, such as the reallocation of finite resources between growth and other traits and functions. Despite the prevalence of submaximal growth, even when predators are absent, there

  1. Do organic ligands affect calcite dissolution rates?

    NASA Astrophysics Data System (ADS)

    Oelkers, Eric H.; Golubev, Sergey V.; Pokrovsky, Oleg S.; Bénézeth, Pascale

    2011-04-01

    Steady state Iceland-spar calcite dissolution rates were measured at 25 °C in aqueous solutions containing 0.1 M NaCl and up to 0.05 M dissolved bicarbonate at pH from 7.9 to 9.1 in the presence of 13 distinct dissolved organic ligands in mixed-flow reactors. The organic ligands considered in this study include those most likely to be present in either (1) aquifers at the conditions pertinent to CO 2 sequestration or (2) soil/early diagenetic environments: acetate, phthalate, citrate, EDTA 4-, succinate, D-glucosaminate, L-glutamate, D-gluconate, 2,4-dihydroxybenzoate, 3,4-dihydroxybenzoate, fumarate, malonate, and gallate. Results show that the presence of <0.05 mol/kg of these organic anions changes calcite dissolution rates by less than a factor of 2.5 with the exception of citrate and EDTA 4-. The presence of 0.05 mol/kg citrate and EDTA 4- increases calcite dissolution rates by as much as a factor of 35 and 500, respectively, compared to rates in organic anion-free solutions. Further calcite dissolution experiments were performed in the presence of organic polymers similar to bacterial exudates, cell exopolysaccharides, and analogs of microbial cell envelopes: alginate, lichen extract, humic acid, pectin, and gum xanthan. In no case did the presence of <100 ppm of these organics change calcite dissolution rates by more than a factor of 2.5. Results obtained in this study suggest that the presence of aqueous organic anions negligibly affects calcite forward dissolution rates in most natural environments. Some effect on calcite reactivity may be observed, however, by the presence of organic anions if they change substantially the chemical affinity of the fluid with respect to calcite.

  2. Effect of impurities on crystal growth rate of ammonium pentaborate

    NASA Astrophysics Data System (ADS)

    Şahin, Ö.; Özdemir, M.; Genli, N.

    2004-01-01

    The effect of sodium chloride, borax and boric acid of different concentrations on the growth rate of ammonium pentaborate octahydrate crystals (APBO) was measured and was found to depend on supersaturation in a fluidized bed crystallizer. The presence of impurities in APBO solution increases the growth rate compared with growth from pure solution. It was found that the presence of sodium chloride, borax and boric acid decreases the reaction rate constant kr, while it increases the mass-transfer coefficient, K, of APBO crystals. In pure aqueous solution, the crystal growth rate of APBO is mainly controlled by diffusion. However, both diffusion and integration steps affect the growth rate of APBO crystals in the presence of sodium chloride, borax and boric acid. The mass-transfer coefficient, K, reaction rate constant, kr and reaction order, r were calculated from general mass-transfer equation by using genetic algorithm method making no assumption.

  3. Improved national growth rate method: a comment.

    PubMed

    Begum, N

    1991-09-01

    Rahman's 1987 paper on an improvement in the National Growth Rate Method (NGRM) is discussed. Rahman's assumption is that migration in/out of a city of region is constant, and because the method requires minimal data, it is suitable for application in developing countries. This assumption means that the model is inappropriate for developing countries which are known to have nonuniform rates of population change. Size of city also affects the migration pattern, where larger cities with greater numbers of industrial and business concerns and social services receive a rapid influx of new migrants. This view is also reflected in Rahman's paper. The example is given that Dhaka SMA, Bangladesh received 60% more migrants in 2 periods: 130,000 in migrants/year from 1974 to 1981 vs. 82,000/year from 1961 to 1974. Chittagong, Khulna, and Rajshahi SMA's had similar growth from 1961 to 1981, but there was a slower rate in the 2nd period. Positive contributions of the Rahman paper are the identification of the problems of the nuisance parameter. Rahman points out that the definition of the migration rate is flawed by the traditional NGRM parameter describing the natural increase of migrants. It is stated that recognition of this flaw and the development of a simple case of uniform migration is a good beginning for developing a more realistic model of migration. It is suggested that an extra parameter to represent departure from uniformity in the estimation be introduced. More data would be required. If the task is to use only 2 censuses for estimation of a single parameter, then there is a seemingly insurmountable problem.

  4. Measurements of Protein Crystal Face Growth Rates

    NASA Technical Reports Server (NTRS)

    Gorti, S.

    2014-01-01

    Protein crystal growth rates will be determined for several hyperthermophile proteins.; The growth rates will be assessed using available theoretical models, including kinetic roughening.; If/when kinetic roughening supersaturations are established, determinations of protein crystal quality over a range of supersaturations will also be assessed.; The results of our ground based effort may well address the existence of a correlation between fundamental growth mechanisms and protein crystal quality.

  5. Growth Rates of Microbes in the Oceans.

    PubMed

    Kirchman, David L

    2016-01-01

    A microbe's growth rate helps to set its ecological success and its contribution to food web dynamics and biogeochemical processes. Growth rates at the community level are constrained by biomass and trophic interactions among bacteria, phytoplankton, and their grazers. Phytoplankton growth rates are approximately 1 d(-1), whereas most heterotrophic bacteria grow slowly, close to 0.1 d(-1); only a few taxa can grow ten times as fast. Data from 16S rRNA and other approaches are used to speculate about the growth rate and the life history strategy of SAR11, the most abundant clade of heterotrophic bacteria in the oceans. These strategies are also explored using genomic data. Although the methods and data are imperfect, the available data can be used to set limits on growth rates and thus on the timescale for changes in the composition and structure of microbial communities.

  6. Growth Rates of Microbes in the Oceans

    NASA Astrophysics Data System (ADS)

    Kirchman, David L.

    2016-01-01

    A microbe's growth rate helps to set its ecological success and its contribution to food web dynamics and biogeochemical processes. Growth rates at the community level are constrained by biomass and trophic interactions among bacteria, phytoplankton, and their grazers. Phytoplankton growth rates are approximately 1 d-1, whereas most heterotrophic bacteria grow slowly, close to 0.1 d-1; only a few taxa can grow ten times as fast. Data from 16S rRNA and other approaches are used to speculate about the growth rate and the life history strategy of SAR11, the most abundant clade of heterotrophic bacteria in the oceans. These strategies are also explored using genomic data. Although the methods and data are imperfect, the available data can be used to set limits on growth rates and thus on the timescale for changes in the composition and structure of microbial communities.

  7. Temperature influence on phytoplankton community growth rates

    NASA Astrophysics Data System (ADS)

    Sherman, Elliot; Moore, J. Keith; Primeau, Francois; Tanouye, David

    2016-04-01

    A large database of field estimates of phytoplankton community growth rates in natural populations was compiled and analyzed to determine the apparent temperature effect on phytoplankton community growth rate. We conducted an ordinary least squares regression to optimize the parameters in two commonly used growth-temperature relations (Arrhenius and Q10 models). Both equations fit the observational data equally with the optimized parameter values. The optimum apparent Q10 value was 1.47 ± 0.08 (95% confidence interval, CI). Microzooplankton grazing rates closely matched the temperature trends for phytoplankton growth. This likely reflects a dynamic adjustment of biomass and grazing rates by the microzooplankton to match their available food source, illustrating tight coupling of phytoplankton growth and microzooplankton grazing rates. The field-measured temperature effect and growth rates were compared with estimates from the satellite Carbon-based Productivity Model (CbPM) and three Earth System Models (ESMs), with model output extracted at the same month and sampling locations as the observations. The optimized, apparent Q10 value calculated for the CbPM was 1.51, with overestimation of growth rates. The apparent Q10 value in the Community Earth System Model (V1.0) was 1.65, with modest underestimation of growth rates. The GFDL-ESM2M and GFDL-ESM2G models produced apparent Q10 values of 1.52 and 1.39, respectively. Models with an apparent Q10 that is significantly greater than ~1.5 will overestimate the phytoplankton community growth response to the ongoing climate warming and will have spatial biases in estimated growth rates for the current era.

  8. The evolution of growth trajectories: what limits growth rate?

    PubMed

    Dmitriew, Caitlin M

    2011-02-01

    According to life-history theory, growth rates are subject to strong directional selection due to reproductive and survival advantages associated with large adult body size. Yet, growth is commonly observed to occur at rates lower than the maximum that is physiologically possible and intrinsic growth rates often vary among populations. This implies that slower growth is favoured under certain conditions. Realized growth rate is thus the result of a compromise between the costs and advantages of growing rapidly, and the optimal rate of growth is not equivalent to the fundamental maximum rate. The ecological and evolutionary factors influencing growth rate are reviewed, with particular emphasis on how growth might be constrained by direct fitness costs. Costs of accelerating growth might contribute to the variance in fitness that is not attributable to age or size at maturity, as well as to the variation in life-history strategies observed within and among species. Two main approaches have been taken to study the fitness trade-offs relating to growth rate. First, environmental manipulations can be used to produce treatment groups with different rates of growth. Second, common garden experiments can be used to compare fitness correlates among populations with different intrinsic growth rates. Data from these studies reveal a number of potential costs for growth over both the short and long term. In order to acquire the energy needed for faster growth, animals must increase food intake. Accordingly, in many taxa, the major constraint on growth rate appears to arise from the trade-off between predation risk and foraging effort. However, growth rates are also frequently observed to be submaximal in the absence of predation, suggesting that growth trajectories also impact fitness via other channels, such as the reallocation of finite resources between growth and other traits and functions. Despite the prevalence of submaximal growth, even when predators are absent, there

  9. Dinosaurian growth patterns and rapid avian growth rates.

    PubMed

    Erickson, G M; Rogers, K C; Yerby, S A

    2001-07-26

    Did dinosaurs grow in a manner similar to extant reptiles, mammals or birds, or were they unique? Are rapid avian growth rates an innovation unique to birds, or were they inherited from dinosaurian precursors? We quantified growth rates for a group of dinosaurs spanning the phylogenetic and size diversity for the clade and used regression analysis to characterize the results. Here we show that dinosaurs exhibited sigmoidal growth curves similar to those of other vertebrates, but had unique growth rates with respect to body mass. All dinosaurs grew at accelerated rates relative to the primitive condition seen in extant reptiles. Small dinosaurs grew at moderately rapid rates, similar to those of marsupials, but large species attained rates comparable to those of eutherian mammals and precocial birds. Growth in giant sauropods was similar to that of whales of comparable size. Non-avian dinosaurs did not attain rates like those of altricial birds. Avian growth rates were attained in a stepwise fashion after birds diverged from theropod ancestors in the Jurassic period. PMID:11473315

  10. Dinosaurian growth patterns and rapid avian growth rates.

    PubMed

    Erickson, G M; Rogers, K C; Yerby, S A

    2001-07-26

    Did dinosaurs grow in a manner similar to extant reptiles, mammals or birds, or were they unique? Are rapid avian growth rates an innovation unique to birds, or were they inherited from dinosaurian precursors? We quantified growth rates for a group of dinosaurs spanning the phylogenetic and size diversity for the clade and used regression analysis to characterize the results. Here we show that dinosaurs exhibited sigmoidal growth curves similar to those of other vertebrates, but had unique growth rates with respect to body mass. All dinosaurs grew at accelerated rates relative to the primitive condition seen in extant reptiles. Small dinosaurs grew at moderately rapid rates, similar to those of marsupials, but large species attained rates comparable to those of eutherian mammals and precocial birds. Growth in giant sauropods was similar to that of whales of comparable size. Non-avian dinosaurs did not attain rates like those of altricial birds. Avian growth rates were attained in a stepwise fashion after birds diverged from theropod ancestors in the Jurassic period.

  11. How population growth affects linkage disequilibrium.

    PubMed

    Rogers, Alan R

    2014-08-01

    The "LD curve" relates the linkage disequilibrium (LD) between pairs of nucleotide sites to the distance that separates them along the chromosome. The shape of this curve reflects natural selection, admixture between populations, and the history of population size. This article derives new results about the last of these effects. When a population expands in size, the LD curve grows steeper, and this effect is especially pronounced following a bottleneck in population size. When a population shrinks, the LD curve rises but remains relatively flat. As LD converges toward a new equilibrium, its time path may not be monotonic. Following an episode of growth, for example, it declines to a low value before rising toward the new equilibrium. These changes happen at different rates for different LD statistics. They are especially slow for estimates of [Formula: see text], which therefore allow inferences about ancient population history. For the human population of Europe, these results suggest a history of population growth.

  12. Effect of cultural conditions on the seed-to-seed growth of Arabidopsis and Cardamine - A study of growth rates and reproductive development as affected by test tube seals

    NASA Technical Reports Server (NTRS)

    Hoshizaki, T.

    1982-01-01

    The effects of test tube seals on the growth, flowering, and seed pod formation of Arabidopsis thaliana (L.) Heynh., mouse ear cress, and Cardamine oligosperma Nutt, bitter cress, are studied in order to assess the conditions used in weightlessness experiments. Among other results, it is found that the growth (height) and flowering (date of bud appearance) were suppressed in mouse ear cress in tubes sealed with Saran. Seed pod formation which occurred by day 45 in open-to-air controls, was still lacking in the sealed plants even up to day 124. The growth and flowering of bitter cress were also suppressed by the Saran seal, although up to day 55 the Saran-sealed plants were taller. It is suggested that atmospheric composition was the cause of the suppression of growth, flowering, and seed pod development in these plants, since the mouse ear cress renewed their growth and then set seed pods after the Saran seal was ruptured.

  13. Gearbox gene expression and growth rate.

    PubMed

    Aldea, M; Garrido, T; Tormo, A

    1993-07-01

    Regulation of gene expression in prokaryotic cells usually takes place at the level of transcription initiation. Different forms of RNA polymerase recognizing specific promoters are engaged in the control of many prokaryotic regulons. This also seems to be the case for some Escherichia coli genes that are induced at low growth rates and by nutrient starvation. Their gene products are synthesized at levels inversely proportional to growth rate, and this mode of regulation has been termed gearbox gene expression. This kind of growth-rate modulation is exerted by specific transcriptional initiation signals, the gearbox promoters, and some of them depend on a putative new σ factor (RpoS). Gearbox promoters drive expression of morphogenetic and cell division genes at constant levels per cell and cycle to meet the demands of cell division and septum formation. A mechanism is proposed that could sense the growth rate of the cell to alter gene expression by the action of specific σ factors.

  14. On growth rate hysteresis and catastrophic crystal growth

    NASA Astrophysics Data System (ADS)

    Ferreira, Cecília; Rocha, Fernando A.; Damas, Ana M.; Martins, Pedro M.

    2013-04-01

    Different crystal growth rates as supersaturation is increasing or decreasing in impure media is a phenomenon called growth rate hysteresis (GRH) that has been observed in varied systems and applications, such as protein crystallization or during biomineralization. We have recently shown that the transient adsorption of impurities onto newly formed active sites for growth (or kinks) is sensitive to the direction and rate of supersaturation variation, thus providing a possible explanation for GRH [6]. In the present contribution, we expand on this concept by deriving the analytical expressions for transient crystal growth based on the energetics of growth hillock formation and kink occupation by impurities. Two types of GRH results are described according to the variation of kink density with supersaturation: for nearly constant density, decreasing or increasing supersaturation induce, respectively, growth promoting or inhibiting effects relative to equilibrium conditions. This is the type of GRH measured by us during the crystallization of egg-white lysozyme. For variable kink density, slight changes in the supersaturation level may induce abrupt variations in the crystal growth rate. Different literature examples of this so-called 'catastrophic' crystal growth are discussed in terms of their fundamental consequences.

  15. Ultraslow growth rates of giant gypsum crystals

    PubMed Central

    Van Driessche, A. E. S.; García-Ruíz, J. M.; Tsukamoto, K.; Patiño-Lopez, L. D.; Satoh, H.

    2011-01-01

    Mineralogical processes taking place close to equilibrium, or with very slow kinetics, are difficult to quantify precisely. The determination of ultraslow dissolution/precipitation rates would reveal characteristic timing associated with these processes that are important at geological scale. We have designed an advanced high-resolution white-beam phase-shift interferometry microscope to measure growth rates of crystals at very low supersaturation values. To test this technique, we have selected the giant gypsum crystals of Naica ore mines in Chihuahua, Mexico, a challenging subject in mineral formation. They are thought to form by a self-feeding mechanism driven by solution-mediated anhydrite-gypsum phase transition, and therefore they must be the result of an extremely slow crystallization process close to equilibrium. To calculate the formation time of these crystals we have measured the growth rates of the {010} face of gypsum growing from current Naica waters at different temperatures. The slowest measurable growth rate was found at 55 °C, 1.4 ± 0.2 × 10-5 nm/s, the slowest directly measured normal growth rate for any crystal growth process. At higher temperatures, growth rates increase exponentially because of decreasing gypsum solubility and higher kinetic coefficient. At 50 °C neither growth nor dissolution was observed indicating that growth of giant crystals of gypsum occurred at Naica between 58 °C (gypsum/anhydrite transition temperature) and the current temperature of Naica waters, confirming formation temperatures determined from fluid inclusion studies. Our results demonstrate the usefulness of applying advanced optical techniques in laboratory experiments to gain a better understanding of crystal growth processes occurring at a geological timescale. PMID:21911400

  16. Ultraslow growth rates of giant gypsum crystals.

    PubMed

    Van Driessche, A E S; García-Ruíz, J M; Tsukamoto, K; Patiño-Lopez, L D; Satoh, H

    2011-09-20

    Mineralogical processes taking place close to equilibrium, or with very slow kinetics, are difficult to quantify precisely. The determination of ultraslow dissolution/precipitation rates would reveal characteristic timing associated with these processes that are important at geological scale. We have designed an advanced high-resolution white-beam phase-shift interferometry microscope to measure growth rates of crystals at very low supersaturation values. To test this technique, we have selected the giant gypsum crystals of Naica ore mines in Chihuahua, Mexico, a challenging subject in mineral formation. They are thought to form by a self-feeding mechanism driven by solution-mediated anhydrite-gypsum phase transition, and therefore they must be the result of an extremely slow crystallization process close to equilibrium. To calculate the formation time of these crystals we have measured the growth rates of the {010} face of gypsum growing from current Naica waters at different temperatures. The slowest measurable growth rate was found at 55 °C, 1.4 ± 0.2 × 10(-5) nm/s, the slowest directly measured normal growth rate for any crystal growth process. At higher temperatures, growth rates increase exponentially because of decreasing gypsum solubility and higher kinetic coefficient. At 50 °C neither growth nor dissolution was observed indicating that growth of giant crystals of gypsum occurred at Naica between 58 °C (gypsum/anhydrite transition temperature) and the current temperature of Naica waters, confirming formation temperatures determined from fluid inclusion studies. Our results demonstrate the usefulness of applying advanced optical techniques in laboratory experiments to gain a better understanding of crystal growth processes occurring at a geological timescale.

  17. Can we estimate bacterial growth rates from ribosomal RNA content?

    SciTech Connect

    Kemp, P.F.

    1995-12-31

    Several studies have demonstrated a strong relationship between the quantity of RNA in bacterial cells and their growth rate under laboratory conditions. It may be possible to use this relationship to provide information on the activity of natural bacterial communities, and in particular on growth rate. However, if this approach is to provide reliably interpretable information, the relationship between RNA content and growth rate must be well-understood. In particular, a requisite of such applications is that the relationship must be universal among bacteria, or alternately that the relationship can be determined and measured for specific bacterial taxa. The RNA-growth rate relationship has not been used to evaluate bacterial growth in field studies, although RNA content has been measured in single cells and in bulk extracts of field samples taken from coastal environments. These measurements have been treated as probable indicators of bacterial activity, but have not yet been interpreted as estimators of growth rate. The primary obstacle to such interpretations is a lack of information on biological and environmental factors that affect the RNA-growth rate relationship. In this paper, the available data on the RNA-growth rate relationship in bacteria will be reviewed, including hypotheses regarding the regulation of RNA synthesis and degradation as a function of growth rate and environmental factors; i.e. the basic mechanisms for maintaining RNA content in proportion to growth rate. An assessment of the published laboratory and field data, the current status of this research area, and some of the remaining questions will be presented.

  18. Abortion Rates Rising in Zika-Affected Countries, Study Shows

    MedlinePlus

    ... page: https://medlineplus.gov/news/fullstory_159500.html Abortion Rates Rising in Zika-Affected Countries, Study Shows ... from mosquito-borne Zika may be driving up abortion rates in Latin American countries affected by the ...

  19. Growth, nitrogen uptake and flow in maize plants affected by root growth restriction.

    PubMed

    Xu, Liangzheng; Niu, Junfang; Li, Chunjian; Zhang, Fusuo

    2009-07-01

    The objective of the present study was to investigate the influence of a reduced maize root-system size on root growth and nitrogen (N) uptake and flow within plants. Restriction of shoot-borne root growth caused a strong decrease in the absorption of root: shoot dry weight ratio and a reduction in shoot growth. On the other hand, compensatory growth and an increased N uptake rate in the remaining roots were observed. Despite the limited long-distance transport pathway in the mesocotyl with restriction of shoot-borne root growth, N cycling within these plants was higher than those in control plants, implying that xylem and phloem flow velocities via the mesocotyl were considerably higher than in plants with an intact root system. The removal of the seminal roots in addition to restricting shoot-borne root development did not affect whole plant growth and N uptake, except for the stronger compensatory growth of the primary roots. Our results suggest that an adequate N supply to maize plant is maintained by compensatory growth of the remaining roots, increased N uptake rate and flow velocities within the xylem and phloem via the mesocotyl, and reduction in the shoot growth rate.

  20. Environmental factors affecting rates of nitrogen cycling

    SciTech Connect

    Lipschultz, F.

    1984-01-01

    The nitrogen cycle in the eutrophic Delaware river was studied in late summer, 1983 using /sup 15/N tracer additions of NHG/sub 4//sup +/, NO/sub 2//sup -/, and NO/sub 3//sup -/. Rates for nine different transformations were calculated simultaneously with a least-squares minimization analysis. Light was found to stimulate ammonium uptake and to inhibit ammonium oxidation. Rates for nitrification, ammonium uptake by phytoplankton, and photosynthesis were integrated over 24 hours and river depth. High turbidity lifted the effect of light inhibition on nitrification and restricted phytoplankton uptake. Uptake of ammonium contributed over 95% of the inorganic nitrogen ration for phytoplankton, with dark uptake accounting for more than 50%. A mass-conservation, box model of river was used to calculate rate constants required to reproduce observed nutrient concentration changes. The calculated constants correlated well with the measured /sup 15/N and oxygen integrated rates. Water-column nitrification was the major loss term for NH/sub 4//sup +/, while water column regeneration was the primary source. Loss of oxidized nitrogen was insignificant. Oxygen consumption and air-water exchange far exceeded net photosynthetic oxygen production. Nitrification contributed less than 1% to the oxygen demand near Philadelphia but up to 25% further downstream. Production of NO and N/sub 2/O was measured under varying oxygen concentrations in batch cultures of the nitrifying bacteria Nitrosomonas europaea and Nitrosococcus oceanus. Production of both gases increased relative to nitrite production as oxygen levels decreased.

  1. Does cosmic weather affect infant mortality rate?

    PubMed

    Shamir, Lior

    2010-01-01

    In this article, the author proposes to consider a link between infant mortality rate (IMR) and galactic cosmic radiation (CR) density. The periodical increase in solar activity increases the effect of the magnetic field of the sun, and therefore weakens galactic cosmic rays hitting the Earth's surface. As a result, embryos in their early stages of development may be less exposed to high-energy ionizing cosmic rays when the solar activity peaks. In the study discussed here, cosmic ray density data were correlated with the U.S. infant mortality rate in the following year. Statistical analysis shows that in the past 30 years, Pearson correlation between the change in galactic CR flux and IMR decrease in the following year was -0.36 (p < .05). PMID:20687328

  2. Major genes affecting ovulation rate in sheep

    PubMed Central

    2005-01-01

    Research conducted since 1980 in relation to inheritance patterns and DNA testing of major genes for prolificacy has shown that major genes have the potential to significantly increase the reproductive performance of sheep flocks throughout the world. Mutations that increase ovulation rate have been discovered in the BMPR-1B, BMP15 and GDF9 genes, and others are known to exist from the expressed inheritance patterns although the mutations have not yet been located. In the case of BMP15, four different mutations have been discovered but each produces the same phenotype. The modes of inheritance of the different prolificacy genes include autosomal dominant genes with additive effects on ovulation rate (BMPR-1B; Lacaune), autosomal over-dominant genes with infertility in homozygous females (GDF9), X-linked over-dominant genes with infertility in homozygous females (BMP15), and X-linked maternally imprinted genes (FecX2). The size of the effect of one copy of a mutation on ovulation rate ranges from an extra 0.4 ovulations per oestrus for the FecX2 mutation to an extra 1.5 ovulations per oestrus for the BMPR-1B mutation. A commercial DNA testing service enables some of these mutations to be used in genetic improvement programmes based on marker assisted selection. PMID:15601592

  3. Revisiting the Estimation of Dinosaur Growth Rates

    PubMed Central

    Myhrvold, Nathan P.

    2013-01-01

    Previous growth-rate studies covering 14 dinosaur taxa, as represented by 31 data sets, are critically examined and reanalyzed by using improved statistical techniques. The examination reveals that some previously reported results cannot be replicated by using the methods originally reported; results from new methods are in many cases different, in both the quantitative rates and the qualitative nature of the growth, from results in the prior literature. Asymptotic growth curves, which have been hypothesized to be ubiquitous, are shown to provide best fits for only four of the 14 taxa. Possible reasons for non-asymptotic growth patterns are discussed; they include systematic errors in the age-estimation process and, more likely, a bias toward younger ages among the specimens analyzed. Analysis of the data sets finds that only three taxa include specimens that could be considered skeletally mature (i.e., having attained 90% of maximum body size predicted by asymptotic curve fits), and eleven taxa are quite immature, with the largest specimen having attained less than 62% of predicted asymptotic size. The three taxa that include skeletally mature specimens are included in the four taxa that are best fit by asymptotic curves. The totality of results presented here suggests that previous estimates of both maximum dinosaur growth rates and maximum dinosaur sizes have little statistical support. Suggestions for future research are presented. PMID:24358133

  4. The effect of size and competition on tree growth rate in old-growth coniferous forests

    USGS Publications Warehouse

    Das, Adrian

    2012-01-01

    Tree growth and competition play central roles in forest dynamics. Yet models of competition often neglect important variation in species-specific responses. Furthermore, functions used to model changes in growth rate with size do not always allow for potential complexity. Using a large data set from old-growth forests in California, models were parameterized relating growth rate to tree size and competition for four common species. Several functions relating growth rate to size were tested. Competition models included parameters for tree size, competitor size, and competitor distance. Competitive strength was allowed to vary by species. The best ranked models (using Akaike’s information criterion) explained between 18% and 40% of the variance in growth rate, with each species showing a strong response to competition. Models indicated that relationships between competition and growth varied substantially among species. The results also suggested that the relationship between growth rate and tree size can be complex and that how we model it can affect not only our ability to detect that complexity but also whether we obtain misleading results. In this case, for three of four species, the best model captured an apparent and unexpected decline in potential growth rate for the smallest trees in the data set.

  5. Floral symmetry affects speciation rates in angiosperms.

    PubMed Central

    Sargent, Risa D.

    2004-01-01

    Despite much recent activity in the field of pollination biology, the extent to which animal pollinators drive the formation of new angiosperm species remains unresolved. One problem has been identifying floral adaptations that promote reproductive isolation. The evolution of a bilaterally symmetrical corolla restricts the direction of approach and movement of pollinators on and between flowers. Restricting pollinators to approaching a flower from a single direction facilitates specific placement of pollen on the pollinator. When coupled with pollinator constancy, precise pollen placement can increase the probability that pollen grains reach a compatible stigma. This has the potential to generate reproductive isolation between species, because mutations that cause changes in the placement of pollen on the pollinator may decrease gene flow between incipient species. I predict that animal-pollinated lineages that possess bilaterally symmetrical flowers should have higher speciation rates than lineages possessing radially symmetrical flowers. Using sister-group comparisons I demonstrate that bilaterally symmetric lineages tend to be more species rich than their radially symmetrical sister lineages. This study supports an important role for pollinator-mediated speciation and demonstrates that floral morphology plays a key role in angiosperm speciation. PMID:15156918

  6. SPATULA links daytime temperature and plant growth rate.

    PubMed

    Sidaway-Lee, Kate; Josse, Eve-Marie; Brown, Alanna; Gan, Yinbo; Halliday, Karen J; Graham, Ian A; Penfield, Steven

    2010-08-24

    Plants exhibit a wide variety of growth rates that are known to be determined by genetic and environmental factors, and different plants grow optimally at different temperatures, indicating that this is a genetically determined character. Moderate decreases in ambient temperature inhibit vegetative growth, but the mechanism is poorly understood, although a decrease in gibberellin (GA) levels is known to be required. Here we demonstrate that the basic helix-loop-helix transcription factor SPATULA (SPT), previously known to be a regulator of low temperature-responsive germination, mediates the repression of growth by cool daytime temperatures but has little or no growth-regulating role under warmer conditions. We show that only daytime temperatures affect vegetative growth and that SPT couples morning temperature to growth rate. In seedlings, warm temperatures inhibit the accumulation of the SPT protein, and SPT autoregulates its own transcript abundance in conjunction with diurnal effects. Genetic data show that repression of growth by SPT is independent of GA signaling and phytochrome B, as previously shown for PIF4. Our data suggest that SPT integrates time of day and temperature signaling to control vegetative growth rate.

  7. Kinetics of nucleation with decreasing rate of growth

    NASA Astrophysics Data System (ADS)

    Kurasov, Victor

    2015-10-01

    Extension of analytical description of the stage of nucleation to the case of the slow growth rates of the embryos growth has been constructed. The metastable phase consumption by the already formed embryos affects the nucleation rate which leads to the non-linear evolution. The power exponentials which are smaller than that for the diffusion growth are chosen as the model laws of the embryos growth. All main characteristics of the nucleation period including the form of the embryos sizes spectrum are found. Analytical description of nucleation in the closed systems as well as in the open systems with the metastable phase influx is presented. It is shown that the relative errors of this description are small.

  8. Growth Rate Fluctuations in Phycomyces Sporangiophores 1

    PubMed Central

    Ensminger, Peter A.; Lipson, Edward D.

    1992-01-01

    The growth rate of the Phycomyces sporangiophore fluctuates under constant environmental conditions. These fluctuations underlie the well-characterized sensory responses to environmental changes. We compared growth fluctuations in sporangiophores of unstimulated wild type and behavioral mutants by use of maximum entropy spectral analysis, a mathematical technique that estimates the frequency and amplitude of oscillations in a time series. The mutants studied are believed to be altered near the input (“night-blind”) or output (“stiff” and “hypertropic”) of the photosensory transduction chain. The maximum entropy spectrum of wild type shows a sharp drop-off in spectral density above 0.3 millihertz, several minor peaks between 0.3 and 10 millihertz, and a broad maximum near 10 millihertz. Similar spectra were obtained for a night-blind mutant and a hypertropic mutant. In contrast, the spectra of three stiff mutants, defective in genes madD, madE, or madG, had distinctive peaks near 1.6 mHz and harmonics of this frequency. A madF stiff mutant, which is less stiff than madD, madE, and madG mutants, had a spectrum intermediate between wild type and the three other stiff mutants. Our results indicate that alterations in one or more steps associated with growth regulation output cause the Phycomyces sporangiophore to express a rhythmic growth rate. PMID:16669047

  9. Controlling Growth Rates of Protein Samples

    NASA Technical Reports Server (NTRS)

    Herrmann, Frederick T.; Herren, Blair J.

    1987-01-01

    Apparatus enables control of humidity in chamber to control rates of growth of crystalline samples of protein. Size of drop of solution from which protein is grown made larger or smaller by condensation or evaporation of water. Situated between desiccant and water source, drop of protein solution shrinks or swells, according to which valve operator opens. Growing protein crystal viewed through polarizing film. Readily adapted to automation.

  10. China's fertility drop lowers world growth rate.

    PubMed

    Haub, C

    1993-06-01

    China practices a stringent and compulsory program of family planning and population control. This approach has, however, served to increase the number of domestic IUD insertions and sterilizations. Contraceptive prevalence has reached 83% and total fertility (TFR) is estimated to be 1.9. This Chinese accomplishment has helped reduce TFR for all East Asia to 1.8, which is lower than that for northern Europe, and bring the world population growth rate down from the 1992 level of 1.68% to 1.63%. This latter rate is reported in the 1993 Population Reference Bureau's (PRB) World Population Data Sheet and is the lowest world population growth rate since PRB's first annual edition in 1962. Despite these reductions, world population still grows by 90 million annually. No one can say for sure whether or not observed fertility decline in China is permanent. China's birth rate rose twice in the 1980s and it could certainly rebound once again. A popular backlash to population policy or a relaxing of policy due to international pressure to reduce the level of compulsion in the program are 2 factors which might increase overall fertility and population growth. Fertility is also declining in subSaharan Africa, but not universally. Birth rates are rapidly declining in eastern Europe and the former USSR as economic conditions and outlooks pale. The populations of Estonia, Latvia, Ukraine, and possible Russia are even declining, while only mixed data are available from Yugoslavia. New statistical publications reflect changing borders. Finally, while Slovakia is the only country added to this year's sheet, Eritrea and the Channel Islands will likely be included in next year's.

  11. Speeding up Growth: Selection for Mass-Independent Maximal Metabolic Rate Alters Growth Rates.

    PubMed

    Downs, Cynthia J; Brown, Jessi L; Wone, Bernard W M; Donovan, Edward R; Hayes, Jack P

    2016-03-01

    Investigations into relationships between life-history traits, such as growth rate and energy metabolism, typically focus on basal metabolic rate (BMR). In contrast, investigators rarely examine maximal metabolic rate (MMR) as a relevant metric of energy metabolism, even though it indicates the maximal capacity to metabolize energy aerobically, and hence it might also be important in trade-offs. We studied the relationship between energy metabolism and growth in mice (Mus musculus domesticus Linnaeus) selected for high mass-independent metabolic rates. Selection for high mass-independent MMR increased maximal growth rate, increased body mass at 20 weeks of age, and generally altered growth patterns in both male and female mice. In contrast, there was little evidence that the correlated response in mass-adjusted BMR altered growth patterns. The relationship between mass-adjusted MMR and growth rate indicates that MMR is an important mediator of life histories. Studies investigating associations between energy metabolism and life histories should consider MMR because it is potentially as important in understanding life history as BMR.

  12. Effect of growth rate on TEP production and aggregation by Thalassiosira weissflogii

    NASA Astrophysics Data System (ADS)

    Chen, J.; Thornton, D. C.

    2012-12-01

    Aggregation into larger particles is important in carbon cycling as it affects the vertical flux of carbon through the water column and the efficiency of the biological carbon pump. Thalassiosira weissflogii was grown in semi-continuous culture at a sequence of growth rates to test the hypothesis that growth rate affects the production of transparent exopolymer particles (TEP) by diatoms. As the growth rate increased, steady-state cell abundances decreased and cell volume increased. Carbohydrate concentration per cell was positively correlated with growth rate due to the larger volume of cells at higher growth rates. TEP particle concentration decreased with increasing growth rate. However the mean size of individual TEP particles and TEP production rate increased with increasing growth rate. Therefore, the total area of TEP was the same in all cultures, irrespective of growth rate. SYTOX green staining showed that the relative permeability of cells increased with decreasing growth rate, indicating that slow growing cells may potentially leak more dissolved organic matter into the surrounding environment. There were larger aggregates in cultures grown at relatively high growth rates. These data show that diatom growth rate affected TEP production, particle stickiness, and aggregates formation. Image of TEP

  13. Net Assimilation Rate Determines the Growth Rates of 14 Species of Subtropical Forest Trees

    PubMed Central

    Li, Xuefei; Schmid, Bernhard; Wang, Fei; Paine, C. E. Timothy

    2016-01-01

    Growth rates are of fundamental importance for plants, as individual size affects myriad ecological processes. We determined the factors that generate variation in RGR among 14 species of trees and shrubs that are abundant in subtropical Chinese forests. We grew seedlings for two years at four light levels in a shade-house experiment. We monitored the growth of every juvenile plant every two weeks. After one and two years, we destructively harvested individuals and measured their functional traits and gas-exchange rates. After calculating individual biomass trajectories, we estimated relative growth rates using nonlinear growth functions. We decomposed the variance in log(RGR) to evaluate the relationships of RGR with its components: specific leaf area (SLA), net assimilation rate (NAR) and leaf mass ratio (LMR). We found that variation in NAR was the primary determinant of variation in RGR at all light levels, whereas SLA and LMR made smaller contributions. Furthermore, NAR was strongly and positively associated with area-based photosynthetic rate and leaf nitrogen content. Photosynthetic rate and leaf nitrogen concentration can, therefore, be good predictors of growth in woody species. PMID:26953884

  14. Net Assimilation Rate Determines the Growth Rates of 14 Species of Subtropical Forest Trees.

    PubMed

    Li, Xuefei; Schmid, Bernhard; Wang, Fei; Paine, C E Timothy

    2016-01-01

    Growth rates are of fundamental importance for plants, as individual size affects myriad ecological processes. We determined the factors that generate variation in RGR among 14 species of trees and shrubs that are abundant in subtropical Chinese forests. We grew seedlings for two years at four light levels in a shade-house experiment. We monitored the growth of every juvenile plant every two weeks. After one and two years, we destructively harvested individuals and measured their functional traits and gas-exchange rates. After calculating individual biomass trajectories, we estimated relative growth rates using nonlinear growth functions. We decomposed the variance in log(RGR) to evaluate the relationships of RGR with its components: specific leaf area (SLA), net assimilation rate (NAR) and leaf mass ratio (LMR). We found that variation in NAR was the primary determinant of variation in RGR at all light levels, whereas SLA and LMR made smaller contributions. Furthermore, NAR was strongly and positively associated with area-based photosynthetic rate and leaf nitrogen content. Photosynthetic rate and leaf nitrogen concentration can, therefore, be good predictors of growth in woody species.

  15. Net Assimilation Rate Determines the Growth Rates of 14 Species of Subtropical Forest Trees.

    PubMed

    Li, Xuefei; Schmid, Bernhard; Wang, Fei; Paine, C E Timothy

    2016-01-01

    Growth rates are of fundamental importance for plants, as individual size affects myriad ecological processes. We determined the factors that generate variation in RGR among 14 species of trees and shrubs that are abundant in subtropical Chinese forests. We grew seedlings for two years at four light levels in a shade-house experiment. We monitored the growth of every juvenile plant every two weeks. After one and two years, we destructively harvested individuals and measured their functional traits and gas-exchange rates. After calculating individual biomass trajectories, we estimated relative growth rates using nonlinear growth functions. We decomposed the variance in log(RGR) to evaluate the relationships of RGR with its components: specific leaf area (SLA), net assimilation rate (NAR) and leaf mass ratio (LMR). We found that variation in NAR was the primary determinant of variation in RGR at all light levels, whereas SLA and LMR made smaller contributions. Furthermore, NAR was strongly and positively associated with area-based photosynthetic rate and leaf nitrogen content. Photosynthetic rate and leaf nitrogen concentration can, therefore, be good predictors of growth in woody species. PMID:26953884

  16. Growth rate degeneracies in kinematic dynamos

    NASA Astrophysics Data System (ADS)

    Favier, B.; Proctor, M. R. E.

    2013-09-01

    We consider the classical problem of kinematic dynamo action in simple steady flows. Due to the adjointness of the induction operator, we show that the growth rate of the dynamo will be exactly the same for two types of magnetic boundary conditions: the magnetic field can be normal (infinite magnetic permeability, also called pseudovacuum) or tangent (perfect electrical conductor) to the boundaries of the domain. These boundary conditions correspond to well-defined physical limits often used in numerical models and relevant to laboratory experiments. The only constraint is for the velocity field u to be reversible, meaning there exists a transformation changing u into -u. We illustrate this surprising property using S2T2 type of flows in spherical geometry inspired by [Dudley and James, Proc. R. Soc. London A1364-502110.1098/rspa.1989.0112 425, 407 (1989)]. Using both types of boundary conditions, it is shown that the growth rates of the dynamos are identical, although the corresponding magnetic eigenmodes are drastically different.

  17. A generic mechanism for adaptive growth rate regulation.

    PubMed

    Furusawa, Chikara; Kaneko, Kunihiko

    2008-01-01

    How can a microorganism adapt to a variety of environmental conditions despite the existence of a limited number of signal transduction mechanisms? We show that for any growing cells whose gene expression fluctuate stochastically, the adaptive cellular state is inevitably selected by noise, even without a specific signal transduction network for it. In general, changes in protein concentration in a cell are given by its synthesis minus dilution and degradation, both of which are proportional to the rate of cell growth. In an adaptive state with a higher growth speed, both terms are large and balanced. Under the presence of noise in gene expression, the adaptive state is less affected by stochasticity since both the synthesis and dilution terms are large, while for a nonadaptive state both the terms are smaller so that cells are easily kicked out of the original state by noise. Hence, escape time from a cellular state and the cellular growth rate are negatively correlated. This leads to a selection of adaptive states with higher growth rates, and model simulations confirm this selection to take place in general. The results suggest a general form of adaptation that has never been brought to light--a process that requires no specific mechanisms for sensory adaptation. The present scheme may help explain a wide range of cellular adaptive responses including the metabolic flux optimization for maximal cell growth.

  18. Crank inertial load affects freely chosen pedal rate during cycling.

    PubMed

    Hansen, Ernst Albin; Jørgensen, Lars Vincents; Jensen, Kurt; Fregly, Benjamin Jon; Sjøgaard, Gisela

    2002-02-01

    Cyclists seek to maximize performance during competition, and gross efficiency is an important factor affecting performance. Gross efficiency is itself affected by pedal rate. Thus, it is important to understand factors that affect freely chosen pedal rate. Crank inertial load varies greatly during road cycling based on the selected gear ratio. Nevertheless, the possible influence of crank inertial load on freely chosen pedal rate and gross efficiency has never been investigated. This study tested the hypotheses that during cycling with sub-maximal work rates, a considerable increase in crank inertial load would cause (1) freely chosen pedal rate to increase, and as a consequence, (2) gross efficiency to decrease. Furthermore, that it would cause (3) peak crank torque to increase if a constant pedal rate was maintained. Subjects cycled on a treadmill at 150 and 250W, with low and high crank inertial load, and with preset and freely chosen pedal rate. Freely chosen pedal rate was higher at high compared with low crank inertial load. Notably, the change in crank inertial load affected the freely chosen pedal rate as much as did the 100W increase in work rate. Along with freely chosen pedal rate being higher, gross efficiency at 250W was lower during cycling with high compared with low crank inertial load. Peak crank torque was higher during cycling at 90rpm with high compared with low crank inertial load. Possibly, the subjects increased the pedal rate to compensate for the higher peak crank torque accompanying cycling with high compared with low crank inertial load. PMID:11784546

  19. Strength of Rocks Affected by Deformation Enhanced Grain Growth

    NASA Astrophysics Data System (ADS)

    Kellermann Slotemaker, A.; de Bresser, H.; Spiers, C.

    2005-12-01

    One way of looking into the possibility of long-term strength changes in the lithosphere is to study transient effects resulting from modifications of the microstructure of rocks. It is generally accepted that mechanical weakening may occur due to progressive grain size refinement resulting from dynamic recrystallization. A decrease in grain size may induce a switch from creep controlled by grain size insensitive dislocation mechanisms to creep governed by grain size sensitive (GSS) mechanisms involving diffusion and grain boundary sliding processes. This switch forms a well-known scenario to explain localization in the lithosphere. However, fine-grained rocks in localized deformation zones are prone to grain coarsening due to surface energy driven grain boundary migration (SED-GBM). This might harden the rock, affecting its role in localizing strain in the long term. The question has arisen if grain growth by SED-GBM in a rock deforming in the GSS creep field can be significantly affected by strain. The broad aim of this study is to shed more light onto this. We have experimentally investigated the microstructural and strength evolution of fine-grained (~0.6 μm) synthetic forsterite and Fe-bearing olivine aggregates that coarsen in grain size while deforming by GSS creep at elevated pressure (600 MPa) and temperature (850-1000 °C). The materials were prepared by `sol-gel' method and contained 0.3-0.5 wt% water and 5-10 vol% enstatite. We performed i) static heat treatment tests of various time durations involving hot isostatic pressing (HIP), and ii) heat treatment tests starting with HIP and continuing with deformation up to 45% axial strain at strain rates in the range 4x10-7 - 1x10-4 s-1. Microstructures were characterized by analyzing full grain size distributions and textures using SEM/EBSD. In addition to the experiments, we studied microstructural evolution in simple two-dimensional numerical models, combining deformation and SED-GBM by means of the

  20. Factors Affecting Growth of Pinus radiata in Chile

    NASA Astrophysics Data System (ADS)

    Alvarez-Munoz, Jose Santos

    (2005--2009) for a network of permanent sample plots in Pinus radiata plantations in Chile. In 2009, we calculated LAI from ground measurements using LI-COR LAI-2000 and TRAC instruments on each one hectare plot. These values of LAI were regressed against Simple Ratio (SR), Normalized Difference Vegetation Index (NDVI) and Reduced Simple Ratio (RSR), derived from the TM 2009 data. Linear relationships were strong with R2 values of 0.65 for SR, 0.61 for NDVI and 0.67 for RSR. Using the RSR relationship, LAI values were estimated for the network of permanent sample plots of Pinus radiata plantations over the whole period. For project 3, we examined environmental factors affecting growth rates of Pinus radiata in Chile. Water availability (as affected by precipitation, soil water holding capacity, and potential evapotranspiration) appeared to be the factor most limiting to leaf area and growth. Maximum growing season temperature also negatively affected growth. Sites with highest productivities had the lowest annual water deficits and the most productive sites used water and light more efficiently. Good sites produced 1.6 as compared to 0.49 kg of wood per m3 of evapotranspired water for less productive sites. In addition, productive stands produced 0.5 as compared to 0.31 g of wood per MJ for less productive sites.

  1. A novel method for measurement of crystal growth rate

    NASA Astrophysics Data System (ADS)

    Kim, Do Yeon; Yang, Dae Ryook

    2013-06-01

    A new method for measurement of crystal growth rate is proposed, in an attempt to make the measuring of growth rate more convenient than the existing methods. In this newly proposed method, the point of nucleation under a constant cooling rate condition was measured as changing the amount of seeds. The growth kinetics parameters were then estimated using the experimental data to match the points of nucleation. Experiments were performed with potash alum in the water system and growth kinetic parameters were estimated. Compared with existing results, the proposed method showed tolerable discrepancy in the growth kinetic parameters. The proposed method can be an alternative technique for measurement of growth rate.

  2. Slower Economic Growth Affects the 1995 Labor Market.

    ERIC Educational Resources Information Center

    Gardner, Jennifer M.; Hayghe, Howard V.

    1996-01-01

    Shows how job growth slowed dramatically in 1995, but the unemployment rate remained little changed. Discusses trends in nonfarm payroll employment by industry and changes in employment status of people in various demographic and occupational groups. (Author)

  3. Effects of bismarck brown R on the growth rates of large and small potassium alum crystals

    NASA Astrophysics Data System (ADS)

    Girolami, Martha W.; Rousseau, Ronald W.

    1985-02-01

    Experimental data show that Bismarck Brown R, at a concentration of 10 ppm, substantially inhibited growth rates of potassium alum. All faces of the crystal were affected similarly, although there was some evidence that inhibition of the (111) faces was slightly greater. Growth rates of small crystals were inhibited more than larger crystals; this is explained using observations of growth rate dispersion believed due to variations in screw dislocation activities. Data showing time-dependent inhibition of growth was used to support the hypothesis that Bismarck Brown R forms complexes or chelates that completely inhibited growth.

  4. Fingernail Growth and Time-Distance Rates in Geology.

    ERIC Educational Resources Information Center

    Rowland, Stephen M.

    1983-01-01

    Fingernail growth rates are easily measured over a period of a few weeks and provide opportunities for students to improve graphing skills. Fingernail growth rates are approximately the same as sea-floor spreading rates and can be used for comparing the rates of other geological processes such as tectonic uplift. (Author/JN)

  5. A high standard metabolic rate constrains juvenile growth.

    PubMed

    Steyermark, Anthony C

    2002-01-01

    The allocation of energy to various components of an individual's energy budget is often viewed as a competitive process. As such, a tradeoff may exist between production (growth) and maintenance metabolism. One view of a potential tradeoff, termed "the principle of allocation", suggests that individuals with lower maintenance metabolic expenditures may have higher growth rates. To determine whether such a tradeoff exists, I analyzed the relationship between growth rate and maintenance metabolism of 225 juvenile snapping turtles housed in the laboratory. I measured growth from hatching to 6 months of age, and then measured oxygen consumption and calculated standard metabolic rate. Mean growth rate was 0.19 g d(-) and mean standard metabolic rate (SMR) was 1.41 kJ d(-). Maintenance metabolism and growth were negatively correlated after both were adjusted for body mass. The results support the "principle of allocation" theory: individuals with higher standard metabolic rates tended to have low growth rates. PMID:16351863

  6. Adoption of multivariate copulae in prognostication of economic growth by means of interest rate

    NASA Astrophysics Data System (ADS)

    Saputra, Dewi Tanasia; Indratno, Sapto Wahyu, Dr.

    2015-12-01

    Inflation, at a healthy rate, is a sign of growing economy. Nonetheless, when inflation rate grows uncontrollably, it will negatively influence economic growth. Many tackle this problem by increasing interest rate to help protecting the value of money which is detained by inflation. There are few, however, who study the effects of interest rate in economic growth. The main purposes of this paper are to find how the change of interest rate affects economic growth and to use the relationship in prognostication of economic growth. By using expenditure model, a linear relationship between economic growth and interest rate is developed. The result is then used for prediction by normal copula and Vine Archimedean copula. It is shown that increasing interest rate to tackle inflation is a poor solution. Whereas implementation of copula in predicting economic growth yields an accurate result, with not more than 0.5% difference.

  7. Ice cream structural elements that affect melting rate and hardness.

    PubMed

    Muse, M R; Hartel, R W

    2004-01-01

    Statistical models were developed to reveal which structural elements of ice cream affect melting rate and hardness. Ice creams were frozen in a batch freezer with three types of sweetener, three levels of the emulsifier polysorbate 80, and two different draw temperatures to produce ice creams with a range of microstructures. Ice cream mixes were analyzed for viscosity, and finished ice creams were analyzed for air cell and ice crystal size, overrun, and fat destabilization. The ice phase volume of each ice cream were calculated based on the freezing point of the mix. Melting rate and hardness of each hardened ice cream was measured and correlated with the structural attributes by using analysis of variance and multiple linear regression. Fat destabilization, ice crystal size, and the consistency coefficient of the mix were found to affect the melting rate of ice cream, whereas hardness was influenced by ice phase volume, ice crystal size, overrun, fat destabilization, and the rheological properties of the mix.

  8. Estimation of alga growth stage and lipid content growth rate

    NASA Technical Reports Server (NTRS)

    Embaye, Tsegereda N. (Inventor); Trent, Jonathan D. (Inventor)

    2012-01-01

    Method and system for estimating a growth stage of an alga in an ambient fluid. Measured light beam absorption or reflection values through or from the alga and through an ambient fluid, in each of two or more wavelength sub-ranges, are compared with reference light beam absorption values for corresponding wavelength sub-ranges for in each alga growth stage to determine (1) which alga growth stage, if any, is more likely and (2) whether estimated lipid content of the alga is increasing or has peaked. Alga growth is preferably terminated when lipid content has approximately reached a maximum value.

  9. Calcite crystal growth rate inhibition by polycarboxylic acids

    USGS Publications Warehouse

    Reddy, M.M.; Hoch, A.R.

    2001-01-01

    Calcite crystal growth rates measured in the presence of several polycarboxyclic acids show that tetrahydrofurantetracarboxylic acid (THFTCA) and cyclopentanetetracarboxylic acid (CPTCA) are effective growth rate inhibitors at low solution concentrations (0.01 to 1 mg/L). In contrast, linear polycarbocylic acids (citric acid and tricarballylic acid) had no inhibiting effect on calcite growth rates at concentrations up to 10 mg/L. Calcite crystal growth rate inhibition by cyclic polycarboxyclic acids appears to involve blockage of crystal growth sites on the mineral surface by several carboxylate groups. Growth morphology varied for growth in the absence and in the presence of both THFTCA and CPTCA. More effective growth rate reduction by CPTCA relative to THFTCA suggests that inhibitor carboxylate stereochemical orientation controls calcite surface interaction with carboxylate inhibitors. ?? 20O1 Academic Press.

  10. Salamander growth rates increase along an experimental stream phosphorus gradient.

    PubMed

    Bumpers, Phillip M; Maerz, John C; Rosemond, Amy D; Benstead, Jonathan P

    2015-11-01

    Nutrient-driven perturbations to the resource base of food webs are predicted to attenuate with trophic distance, so it is unclear whether higher-level consumers will generally respond to anthropogenic nutrient loading. Few studies have tested whether nutrient (specifically, nitrogen [N] and phosphorus [P]) enrichment of aquatic ecosystems propagates through multiple trophic levels to affect predators, or whether N vs. P is relatively more important in driving effects on food webs. We conducted two-year whole-stream N and P additions to five streams to generate gradients in N and P concentration and N:P ratio (target N:P = 2, 8, 16, 32, 128). Larval salamanders are vertebrate predators of primary and secondary macroinvertebrate consumers in many heterotrophic headwater streams in which the basal resources are detritus and associated microorganisms. We determined the effects of N and P on the growth rates of caged and free-roaming larval Desmognathus quadramaculatus and the average body size of larval Eurycea wilderae. Growth rates and average body size increased by up to 40% and 60%, respectively, with P concentration and were negatively related to N:P ratio. These findings were consistent across both species of salamanders using different methodologies (cage vs. free-roaming) and at different temporal scales (3 months vs. 2 yr). Nitrogen concentration was not significantly related to increased growth rate or body size of the salamander species tested. Our findings suggest that salamander growth responds to the relaxation of ecosystem-level P limitation and that moderate P enrichment can have relatively large effects on vertebrate predators in detritus-based food webs.

  11. Salamander growth rates increase along an experimental stream phosphorus gradient.

    PubMed

    Bumpers, Phillip M; Maerz, John C; Rosemond, Amy D; Benstead, Jonathan P

    2015-11-01

    Nutrient-driven perturbations to the resource base of food webs are predicted to attenuate with trophic distance, so it is unclear whether higher-level consumers will generally respond to anthropogenic nutrient loading. Few studies have tested whether nutrient (specifically, nitrogen [N] and phosphorus [P]) enrichment of aquatic ecosystems propagates through multiple trophic levels to affect predators, or whether N vs. P is relatively more important in driving effects on food webs. We conducted two-year whole-stream N and P additions to five streams to generate gradients in N and P concentration and N:P ratio (target N:P = 2, 8, 16, 32, 128). Larval salamanders are vertebrate predators of primary and secondary macroinvertebrate consumers in many heterotrophic headwater streams in which the basal resources are detritus and associated microorganisms. We determined the effects of N and P on the growth rates of caged and free-roaming larval Desmognathus quadramaculatus and the average body size of larval Eurycea wilderae. Growth rates and average body size increased by up to 40% and 60%, respectively, with P concentration and were negatively related to N:P ratio. These findings were consistent across both species of salamanders using different methodologies (cage vs. free-roaming) and at different temporal scales (3 months vs. 2 yr). Nitrogen concentration was not significantly related to increased growth rate or body size of the salamander species tested. Our findings suggest that salamander growth responds to the relaxation of ecosystem-level P limitation and that moderate P enrichment can have relatively large effects on vertebrate predators in detritus-based food webs. PMID:27070018

  12. Recovery rate affects the effective epidemic threshold with synchronous updating.

    PubMed

    Shu, Panpan; Wang, Wei; Tang, Ming; Zhao, Pengcheng; Zhang, Yi-Cheng

    2016-06-01

    Accurate identification of effective epidemic threshold is essential for understanding epidemic dynamics on complex networks. In this paper, we systematically study how the recovery rate affects the susceptible-infected-removed spreading dynamics on complex networks, where synchronous and asynchronous updating processes are taken into account. We derive the theoretical effective epidemic threshold and final outbreak size based on the edge-based compartmental theory. To validate the proposed theoretical predictions, extensive numerical experiments are implemented by using asynchronous and synchronous updating methods. When asynchronous updating method is used in simulations, recovery rate does not affect the final state of spreading dynamics. But with synchronous updating, we find that the effective epidemic threshold decreases with recovery rate, and final outbreak size increases with recovery rate. A good agreement between the theoretical predictions and the numerical results are observed on both synthetic and real-world networks. Our results extend the existing theoretical studies and help us to understand the phase transition with arbitrary recovery rate. PMID:27368773

  13. Recovery rate affects the effective epidemic threshold with synchronous updating

    NASA Astrophysics Data System (ADS)

    Shu, Panpan; Wang, Wei; Tang, Ming; Zhao, Pengcheng; Zhang, Yi-Cheng

    2016-06-01

    Accurate identification of effective epidemic threshold is essential for understanding epidemic dynamics on complex networks. In this paper, we systematically study how the recovery rate affects the susceptible-infected-removed spreading dynamics on complex networks, where synchronous and asynchronous updating processes are taken into account. We derive the theoretical effective epidemic threshold and final outbreak size based on the edge-based compartmental theory. To validate the proposed theoretical predictions, extensive numerical experiments are implemented by using asynchronous and synchronous updating methods. When asynchronous updating method is used in simulations, recovery rate does not affect the final state of spreading dynamics. But with synchronous updating, we find that the effective epidemic threshold decreases with recovery rate, and final outbreak size increases with recovery rate. A good agreement between the theoretical predictions and the numerical results are observed on both synthetic and real-world networks. Our results extend the existing theoretical studies and help us to understand the phase transition with arbitrary recovery rate.

  14. growl: Growth factor and growth rate of expanding universes

    NASA Astrophysics Data System (ADS)

    Hamilton, Andrew J. S.

    2015-12-01

    Growl calculates the linear growth factor Da and its logarithmic derivative dln D/dln a in expanding Friedmann-Robertson-Walker universes with arbitrary matter and vacuum densities. It permits rapid and stable numerical evaluation.

  15. Observational tests of Galileon gravity with growth rate

    NASA Astrophysics Data System (ADS)

    Hirano, Koichi

    2016-10-01

    We compare observational data of growth rate with the prediction by Galileon theory. For the same value of the energy density parameter Ω_{m,0}, the growth rate in Galileon models is enhanced compared with the Λ CDM case, due to the enhancement of Newton's constant. The smaller Ω_{m,0} is, the more suppressed growth rate is. Hence the best fit value of Ω_{m,0} in the Galileon model is 0.16 from only the growth rate data, which is considerably smaller than such value obtained from observations of supernovae Ia, the cosmic microwave background and baryon acoustic oscillations. We also find the upper limit of the Brans-Dicke parameter to be ω < -1000 (1σ ), from the growth rate data. In this paper, specific galileon models are considered, not the entire class. More and better growth rate data are required to distinguish between dark energy and modified gravity.

  16. Measurement of seedling growth rate by machine vision

    NASA Astrophysics Data System (ADS)

    Howarth, M. Scott; Stanwood, Phillip C.

    1993-05-01

    Seed vigor and germination tests have traditionally been used to determine deterioration of seed samples. Vigor tests describe the seed potential to emerge and produce a mature crop under certain field conditions and one measure is seedling growth rate. A machine vision system was developed to measure root growth rate over the entire germination period. The machine vision measurement technique was compared to the manual growth rate technique. The vision system provided similar growth rate measurements as compared to the manual growth rate technique. The average error between the system and a manual measurement was -0.13 for the lettuce test and -0.07 for the sorghum test. This technique also provided an accurate representation of the growth rate as well as percent germination.

  17. Rate of language evolution is affected by population size

    PubMed Central

    Bromham, Lindell; Hua, Xia; Fitzpatrick, Thomas G.; Greenhill, Simon J.

    2015-01-01

    The effect of population size on patterns and rates of language evolution is controversial. Do languages with larger speaker populations change faster due to a greater capacity for innovation, or do smaller populations change faster due to more efficient diffusion of innovations? Do smaller populations suffer greater loss of language elements through founder effects or drift, or do languages with more speakers lose features due to a process of simplification? Revealing the influence of population size on the tempo and mode of language evolution not only will clarify underlying mechanisms of language change but also has practical implications for the way that language data are used to reconstruct the history of human cultures. Here, we provide, to our knowledge, the first empirical, statistically robust test of the influence of population size on rates of language evolution, controlling for the evolutionary history of the populations and formally comparing the fit of different models of language evolution. We compare rates of gain and loss of cognate words for basic vocabulary in Polynesian languages, an ideal test case with a well-defined history. We demonstrate that larger populations have higher rates of gain of new words whereas smaller populations have higher rates of word loss. These results show that demographic factors can influence rates of language evolution and that rates of gain and loss are affected differently. These findings are strikingly consistent with general predictions of evolutionary models. PMID:25646448

  18. Dinosaurian growth rates and bird origins.

    PubMed

    Padian, K; de Ricqlès, A J; Horner, J R

    2001-07-26

    Dinosaurs, like other tetrapods, grew more quickly just after hatching than later in life. However, they did not grow like most other non-avian reptiles, which grow slowly and gradually through life. Rather, microscopic analyses of the long-bone tissues show that dinosaurs grew to their adult size relatively quickly, much as large birds and mammals do today. The first birds reduced their adult body size by shortening the phase of rapid growth common to their larger theropod dinosaur relatives. These changes in timing were primarily related not to physiological differences but to differences in growth strategy. PMID:11473307

  19. Socioeconomic factors affecting marriage, divorce and birth rates in a Japanese population.

    PubMed

    Uchida, E; Araki, S; Murata, K

    1993-10-01

    The effects of low income, urbanisation and young age population on age-adjusted rates of first marriage, divorce and live birth among the Japanese population in 46 prefectures were analysed by stepwise regression for 1970 and for 1975. During this period, Japanese society experienced a drastic change from long-lasting economic growth to serious recession in 1973. In both 1970 and 1975, the first marriage rate for females was inversely related to low income and the divorce rates for both males and females were positively related to low income. The live birth rate was significantly related to low income, urbanisation and young age population only in 1975. The first marriage rate for females and the divorce rates for both sexes increased significantly but the first marriage rate for males and live birth rate significantly decreased between 1970 and 1975. These findings suggest that low income was the essential factor affecting first marriage for females and divorce for males and females.

  20. Are physicians' ratings of pain affected by patients' physical attractiveness?

    PubMed

    Hadjistavropoulos, H D; Ross, M A; von Baeyer, C L

    1990-01-01

    The degree to which physical attractiveness and nonverbal expressions of pain influence physicians' perceptions of pain was investigated. Photographs of eight female university students were represented in four experimental conditions created by the manipulation of cosmetics, hairstyles, and facial expressions: (a) attractive-no pain, (b) attractive-pain, (c) unattractive-no pain, and (d) unattractive-pain. Each photograph was accompanied by a brief description of the patient's pain problem that was standard across conditions. Medical residents (N = 60) viewed the photographs and rated each patient's pain, distress, negative affective experience, health, personality, blame for the situation, and the physician's own solicitude for the patient. The results showed that physicians' ratings of pain were influenced both by attractiveness of patients and by nonverbal expressions of pain. Unattractive patients, and patients who were expressing pain, were perceived as experiencing more pain, distress, and negative affective experiences than attractive patients and patients who were not expressing pain. Unattractive patients also received higher ratings of solicitude on the doctor's part and lower ratings of health than attractive patients. Physician's assessments of pain appear to be influenced by the physical attractiveness of the patient. PMID:2367884

  1. Are physicians' ratings of pain affected by patients' physical attractiveness?

    PubMed

    Hadjistavropoulos, H D; Ross, M A; von Baeyer, C L

    1990-01-01

    The degree to which physical attractiveness and nonverbal expressions of pain influence physicians' perceptions of pain was investigated. Photographs of eight female university students were represented in four experimental conditions created by the manipulation of cosmetics, hairstyles, and facial expressions: (a) attractive-no pain, (b) attractive-pain, (c) unattractive-no pain, and (d) unattractive-pain. Each photograph was accompanied by a brief description of the patient's pain problem that was standard across conditions. Medical residents (N = 60) viewed the photographs and rated each patient's pain, distress, negative affective experience, health, personality, blame for the situation, and the physician's own solicitude for the patient. The results showed that physicians' ratings of pain were influenced both by attractiveness of patients and by nonverbal expressions of pain. Unattractive patients, and patients who were expressing pain, were perceived as experiencing more pain, distress, and negative affective experiences than attractive patients and patients who were not expressing pain. Unattractive patients also received higher ratings of solicitude on the doctor's part and lower ratings of health than attractive patients. Physician's assessments of pain appear to be influenced by the physical attractiveness of the patient.

  2. Growth rate determinations from radiocarbon in bamboo corals (genus Keratoisis)

    NASA Astrophysics Data System (ADS)

    Farmer, Jesse R.; Robinson, Laura F.; Hönisch, Bärbel

    2015-11-01

    Radiocarbon (14C) measurements are an important tool for determining growth rates of bamboo corals, a cosmopolitan group of calcitic deep-sea corals. Published growth rate estimates for bamboo corals are highly variable, with potential environmental or ecological drivers of this variability poorly constrained. Here we systematically investigate the application of 14C for growth rate determinations in bamboo corals using 55 14C dates on the calcite and organic fractions of six bamboo corals (identified as Keratoisis sp.) from the western North Atlantic Ocean. Calcite 14C measurements on the distal surface of these corals and five previously published bamboo corals exhibit a strong one-to-one relationship with the 14C of dissolved inorganic carbon (DI14C) in ambient seawater (r2=0.98), confirming the use of Keratoisis sp. calcite 14C as a proxy for seawater 14C activity. Radial growth rates determined from 14C age-depth regressions, 14C plateau tuning and bomb 14C reference chronologies range from 12 to 78 μm y-1, in general agreement with previously published radiometric growth rates. We document potential biases to 14C growth rate determinations resulting from water mass variability, bomb radiocarbon, secondary infilling (ontogeny), and growth rate nonlinearity. Radial growth rates for Keratoisis sp. specimens do not correlate with ambient temperature, suggesting that additional biological and/or environmental factors may influence bamboo coral growth rates.

  3. Environmental Crack Growth Behavior Affected by Thickness/Geometry Constraint

    NASA Astrophysics Data System (ADS)

    Kujawski, Daniel

    2013-03-01

    This article gives a short review on the effects of thickness/constraint and environment on crack growth behavior under cyclic and static loadings. Fatigue crack growth data taken from the literature, corresponding to different environments, ranging from vacuum to air and NaCl solution for a number of alloys and different specimens geometries are presented and analyzed. Reported results indicate that for relatively inert material/environment systems, there is a weak thickness/constraint effect on fatigue crack growth behavior. On the other hand, for corrosive material/environment systems, there is a significant thickness/constraint effect on crack growth rate behavior under both cyclic and static loadings. Some implications related to crack growth modeling are suggested.

  4. Adaptation to Low Temperature Exposure Increases Metabolic Rates Independently of Growth Rates.

    PubMed

    Williams, Caroline M; Szejner-Sigal, Andre; Morgan, Theodore J; Edison, Arthur S; Allison, David B; Hahn, Daniel A

    2016-07-01

    Metabolic cold adaptation is a pattern where ectotherms from cold, high-latitude, or -altitude habitats have higher metabolic rates than ectotherms from warmer habitats. When found, metabolic cold adaptation is often attributed to countergradient selection, wherein short, cool growing seasons select for a compensatory increase in growth rates and development times of ectotherms. Yet, ectotherms in high-latitude and -altitude environments face many challenges in addition to thermal and time constraints on lifecycles. In addition to short, cool growing seasons, high-latitude and - altitude environments are characterized by regular exposure to extreme low temperatures, which cause ectotherms to enter a transient state of immobility termed chill coma. The ability to resume activity quickly after chill coma increases with latitude and altitude in patterns consistent with local adaptation to cold conditions. We show that artificial selection for fast and slow chill coma recovery among lines of the fly Drosophila melanogaster also affects rates of respiratory metabolism. Cold-hardy fly lines, with fast recovery from chill coma, had higher respiratory metabolic rates than control lines, with cold-susceptible slow-recovering lines having the lowest metabolic rates. Fast chill coma recovery was also associated with higher respiratory metabolism in a set of lines derived from a natural population. Although their metabolic rates were higher than control lines, fast-recovering cold-hardy lines did not have faster growth rates or development times than control lines. This suggests that raised metabolic rates in high-latitude and -altitude species may be driven by adaptation to extreme low temperatures, illustrating the importance of moving "Beyond the Mean". PMID:27103615

  5. Some factors affecting the growth and decay of plages

    NASA Astrophysics Data System (ADS)

    Howard, Robert F.

    1993-09-01

    The Mount Wilson coarse array magnetograph data set is analyzed to examine the dependence of growth and decay rates on the tilt angles of the magnetic axes of the regions. It is found that there is a relationship between these quantities which is similar to that found earlier for sunspot groups. Regions near the average tilt angle show larger average (absolute) growth and decay rates. The percentage growth and decay rates show minima (in absolute values) at the average tilt angles because the average areas of regions are largest near this angle. This result is similar to that derived earlier for sunspot groups. As in the case of spot groups, this suggests that, for decay, the effect results from the fact that the average tilt angle may represent the simplest subsurface configuration of the flux loop or loops that make up the region. In the case of region growth, it was suggested that the more complicated loop configuration should result in increased magnetic tension in the flux loop, and thus in a slower ascent of the loop to the surface, and thus a slower growth rate.

  6. Factors affecting production rates of cosmogenic nuclides in extraterrestrial matter

    NASA Astrophysics Data System (ADS)

    Reedy, R. C.

    2015-10-01

    Good production rates are needed for cosmic-ray-produced nuclides to interpret their measurements. Rates depend on many factors, especially the pre-atmospheric object's size, the location of the sample in that object (such as near surface or deep inside), and the object's bulk composition. The bulk composition affects rates, especially in objects with very low and very high iron contents. Extraterrestrial materials with high iron contents usually have higher rates for making nuclides made by reactions with energetic particles and lower rates for the capture of thermal neutrons. In small objects and near the surface of objects, the cascade of secondary neutrons is being developed as primary particles are being removed. Deep in large objects, that secondary cascade is fully developed and the fluxes of primary particles are low. Recent work shows that even the shape of an object in space has a small but measureable effect. Work has been done and continues to be done on better understanding those and other factors. More good sets of measurements in meteorites with known exposure geometries in space are needed. With the use of modern Monte Carlo codes for the production and transport of particles, the nature of these effects have been and is being studied. Work needs to be done to improve the results of these calculations, especially the cross sections for making spallogenic nuclides.

  7. Contact density affects protein evolutionary rate from bacteria to animals.

    PubMed

    Zhou, Tong; Drummond, D Allan; Wilke, Claus O

    2008-04-01

    The density of contacts or the fraction of buried sites in a protein structure is thought to be related to a protein's designability, and genes encoding more designable proteins should evolve faster than other genes. Several recent studies have tested this hypothesis but have found conflicting results. Here, we investigate how a gene's evolutionary rate is affected by its protein's contact density, considering the four species Escherichia coli, Saccharomyces cerevisiae, Drosophila melanogaster, and Homo sapiens. We find for all four species that contact density correlates positively with evolutionary rate, and that these correlations do not seem to be confounded by gene expression level. The strength of this signal, however, varies widely among species. We also study the effect of contact density on domain evolution in multidomain proteins and find that a domain's contact density influences the domain's evolutionary rate. Within the same protein, a domain with higher contact density tends to evolve faster than a domain with lower contact density. Our study provides evidence that contact density can increase evolutionary rates, and that it acts similarly on the level of entire proteins and of individual protein domains.

  8. Spaceflight and age affect tibial epiphyseal growth plate histomorphometry

    NASA Technical Reports Server (NTRS)

    Montufar-Solis, Dina; Duke, Pauline J.; Durnova, G.

    1992-01-01

    Growth plate histomorphometry of rats flown aboard the Soviet biosatellite Cosmos 2044, a 14-day spaceflight, was compared with that of control groups. In growth plates of flight animals, there was a significant increase in cell number per column and height of the proliferative zone and a reduction in height and cell number in the hypertrophy/calcification zone. No significant differences were found in matrix organization at the ultrastructural level of flight animals, indicating that although spacefligfht continues to affect bone growth of 15-wk-old rats, extracellular matrix is not altered in the same manner as seen previously in younger animals. All groups showed growth plate characteristics attributed to aging: lack of calcification zone, reduced hypertrophy zone, and unraveling of collagen fibrils. Tail-suspended controls did not differ from other controls in any of the parameters measured. The results suggest that growth plates of older rats are less responsive to unloading by spaceflight or suspension than those of younger rats and provide new evidence about the modifying effect of spaceflight on the growth plate.

  9. Courting disaster: How diversification rate affects fitness under risk.

    PubMed

    Ratcliff, William C; Hawthorne, Peter; Libby, Eric

    2015-01-01

    Life is full of risk. To deal with this uncertainty, many organisms have evolved bet-hedging strategies that spread risk through phenotypic diversification. These rates of diversification can vary by orders of magnitude in different species. Here we examine how key characteristics of risk and organismal ecology affect the fitness consequences of variation in diversification rate. We find that rapid diversification is strongly favored when the risk faced has a wide spatial extent, with a single disaster affecting a large fraction of the population. This advantage is especially great in small populations subject to frequent disaster. In contrast, when risk is correlated through time, slow diversification is favored because it allows adaptive tracking of disasters that tend to occur in series. Naturally evolved diversification mechanisms in diverse organisms facing a broad array of environmental risks largely support these results. The theory presented in this article provides a testable ecological hypothesis to explain the prevalence of slow stochastic switching among microbes and rapid, within-clutch diversification strategies among plants and animals.

  10. Courting disaster: How diversification rate affects fitness under risk

    PubMed Central

    Ratcliff, William C; Hawthorne, Peter; Libby, Eric

    2015-01-01

    Life is full of risk. To deal with this uncertainty, many organisms have evolved bet-hedging strategies that spread risk through phenotypic diversification. These rates of diversification can vary by orders of magnitude in different species. Here we examine how key characteristics of risk and organismal ecology affect the fitness consequences of variation in diversification rate. We find that rapid diversification is strongly favored when the risk faced has a wide spatial extent, with a single disaster affecting a large fraction of the population. This advantage is especially great in small populations subject to frequent disaster. In contrast, when risk is correlated through time, slow diversification is favored because it allows adaptive tracking of disasters that tend to occur in series. Naturally evolved diversification mechanisms in diverse organisms facing a broad array of environmental risks largely support these results. The theory presented in this article provides a testable ecological hypothesis to explain the prevalence of slow stochastic switching among microbes and rapid, within-clutch diversification strategies among plants and animals. PMID:25410817

  11. Population growth rate and its determinants: an overview.

    PubMed Central

    Sibly, Richard M; Hone, Jim

    2002-01-01

    We argue that population growth rate is the key unifying variable linking the various facets of population ecology. The importance of population growth rate lies partly in its central role in forecasting future population trends; indeed if the form of density dependence were constant and known, then the future population dynamics could to some degree be predicted. We argue that population growth rate is also central to our understanding of environmental stress: environmental stressors should be defined as factors which when first applied to a population reduce population growth rate. The joint action of such stressors determines an organism's ecological niche, which should be defined as the set of environmental conditions where population growth rate is greater than zero (where population growth rate = r = log(e)(N(t+1)/N(t))). While environmental stressors have negative effects on population growth rate, the same is true of population density, the case of negative linear effects corresponding to the well-known logistic equation. Following Sinclair, we recognize population regulation as occurring when population growth rate is negatively density dependent. Surprisingly, given its fundamental importance in population ecology, only 25 studies were discovered in the literature in which population growth rate has been plotted against population density. In 12 of these the effects of density were linear; in all but two of the remainder the relationship was concave viewed from above. Alternative approaches to establishing the determinants of population growth rate are reviewed, paying special attention to the demographic and mechanistic approaches. The effects of population density on population growth rate may act through their effects on food availability and associated effects on somatic growth, fecundity and survival, according to a 'numerical response', the evidence for which is briefly reviewed. Alternatively, there may be effects on population growth rate of

  12. Allometries of maximum growth rate versus body mass at maximum growth indicate that non-avian dinosaurs had growth rates typical of fast growing ectothermic sauropsids.

    PubMed

    Werner, Jan; Griebeler, Eva Maria

    2014-01-01

    We tested if growth rates of recent taxa are unequivocally separated between endotherms and ectotherms, and compared these to dinosaurian growth rates. We therefore performed linear regression analyses on the log-transformed maximum growth rate against log-transformed body mass at maximum growth for extant altricial birds, precocial birds, eutherians, marsupials, reptiles, fishes and dinosaurs. Regression models of precocial birds (and fishes) strongly differed from Case's study (1978), which is often used to compare dinosaurian growth rates to those of extant vertebrates. For all taxonomic groups, the slope of 0.75 expected from the Metabolic Theory of Ecology was statistically supported. To compare growth rates between taxonomic groups we therefore used regressions with this fixed slope and group-specific intercepts. On average, maximum growth rates of ectotherms were about 10 (reptiles) to 20 (fishes) times (in comparison to mammals) or even 45 (reptiles) to 100 (fishes) times (in comparison to birds) lower than in endotherms. While on average all taxa were clearly separated from each other, individual growth rates overlapped between several taxa and even between endotherms and ectotherms. Dinosaurs had growth rates intermediate between similar sized/scaled-up reptiles and mammals, but a much lower rate than scaled-up birds. All dinosaurian growth rates were within the range of extant reptiles and mammals, and were lower than those of birds. Under the assumption that growth rate and metabolic rate are indeed linked, our results suggest two alternative interpretations. Compared to other sauropsids, the growth rates of studied dinosaurs clearly indicate that they had an ectothermic rather than an endothermic metabolic rate. Compared to other vertebrate growth rates, the overall high variability in growth rates of extant groups and the high overlap between individual growth rates of endothermic and ectothermic extant species make it impossible to rule out either of

  13. Allometries of Maximum Growth Rate versus Body Mass at Maximum Growth Indicate That Non-Avian Dinosaurs Had Growth Rates Typical of Fast Growing Ectothermic Sauropsids

    PubMed Central

    Werner, Jan; Griebeler, Eva Maria

    2014-01-01

    We tested if growth rates of recent taxa are unequivocally separated between endotherms and ectotherms, and compared these to dinosaurian growth rates. We therefore performed linear regression analyses on the log-transformed maximum growth rate against log-transformed body mass at maximum growth for extant altricial birds, precocial birds, eutherians, marsupials, reptiles, fishes and dinosaurs. Regression models of precocial birds (and fishes) strongly differed from Case’s study (1978), which is often used to compare dinosaurian growth rates to those of extant vertebrates. For all taxonomic groups, the slope of 0.75 expected from the Metabolic Theory of Ecology was statistically supported. To compare growth rates between taxonomic groups we therefore used regressions with this fixed slope and group-specific intercepts. On average, maximum growth rates of ectotherms were about 10 (reptiles) to 20 (fishes) times (in comparison to mammals) or even 45 (reptiles) to 100 (fishes) times (in comparison to birds) lower than in endotherms. While on average all taxa were clearly separated from each other, individual growth rates overlapped between several taxa and even between endotherms and ectotherms. Dinosaurs had growth rates intermediate between similar sized/scaled-up reptiles and mammals, but a much lower rate than scaled-up birds. All dinosaurian growth rates were within the range of extant reptiles and mammals, and were lower than those of birds. Under the assumption that growth rate and metabolic rate are indeed linked, our results suggest two alternative interpretations. Compared to other sauropsids, the growth rates of studied dinosaurs clearly indicate that they had an ectothermic rather than an endothermic metabolic rate. Compared to other vertebrate growth rates, the overall high variability in growth rates of extant groups and the high overlap between individual growth rates of endothermic and ectothermic extant species make it impossible to rule out either

  14. Identification of factors affecting birth rate in Czech Republic

    NASA Astrophysics Data System (ADS)

    Zámková, Martina; Blašková, Veronika

    2013-10-01

    This article is concerned with identifying economic factors primarily that affect birth rates in Czech Republic. To find the relationship between the magnitudes, we used the multivariate regression analysis and for modeling, we used a time series of annual values (1994-2011) both economic indicators and indicators related to demographics. Due to potential problems with apparent dependence we first cleansed all series obtained from the Czech Statistical Office using first differences. It is clear from the final model that meets all assumptions that there is a positive correlation between birth rates and the financial situation of households. We described the financial situation of households by GDP per capita, gross wages and consumer price index. As expected a positive correlation was proved for GDP per capita and gross wages and negative dependence was proved for the consumer price index. In addition to these economic variables in the model there were used also demographic characteristics of the workforce and the number of employed people. It can be stated that if the Czech Republic wants to support an increase in the birth rate, it is necessary to consider the financial support for households with small children.

  15. Growth Kinetics and Morphology of Barite Crystals Derived from Face-Specific Growth Rates

    SciTech Connect

    Godinho, Jose R. A.; Stack, Andrew G.

    2015-03-30

    Here we investigate the growth kinetics and morphology of barite (BaSO4) crystals by measuring the growth rates of the (001), (210), (010), and (100) surfaces using vertical scanning interferometry. Solutions with saturation indices 1.1, 2.1, and 3.0 without additional electrolyte, in 0.7 M NaCl, or in 1.3 mM SrCl2 are investigated. Face-specific growth rates are inhibited in the SrCl2 solution relative to a solution without electrolyte, except for (100). Contrarily, growth of all faces is promoted in the NaCl solution. The variation of face-specific rates is solution-specific, which leads to a. change of the crystal morphology and overall growth rate of crystals. The measured face-specific growth rates are used to model the growth of single crystals. Modeled crystals have a morphology and size similar to those grown from solution. Based on the model the time dependence of surface area and growth rates is analyzed. Growth rates change with time due to surface area normalization for small crystals and large growth intervals. By extrapolating rates to crystals with large surfaces areas, time-independent growth rates are 0.783, 2.96, and 0.513 mmol∙m-2∙h-1, for saturation index 2.1 solutions without additional electrolyte, NaCl, and SrCl2, respectively.

  16. Does the aerobic capacity of fish muscle change with growth rates?

    PubMed

    Pelletier, D; Guderley, H; Dutil, J D

    1993-08-01

    To ascertain whether growth rate modifies the oxidative capacity of fish white muscle, we examined the effects of individual growth rate on the activities of four mitochondrial enzymes in white muscle of the fast growing Atlantic cod,Gadus morhua. Growth rates were individually monitored in cod held at three acclimation temperatures during experiments repeated in four seasons. The size dependence of citrate synthase (CS), cytochrome C oxidase (CCO) and β-hydroxyacyl CoA dehydrogenase (HOAD) activities was established using wild cod ranging from 115 to 17,350 g. Given their negative allometry, CS and CCO activities in the experimental cod were corrected to those expected for a 1.2 kg animal. HOAD activities did not change with size. The specific activities of CCO and CS were positively correlated with growth rate. However, for both enzymes, season explained more of the variability than growth rate or temperature. Season was the only factor to significantly affect the activity of HOAD, while temperature and season interacted to determine glutamate dehydrogenase activity. CS activity was positively correlated with the initial condition of the cod, which differed among the seasons. The other enzymes did not show this relationship. The independent changes of these enzymes suggest that mitochondria undergo qualitative modifications with changes in growth rate, season and size. Although growth rate and the activities of CCO and CS are positively correlated, the activity of the mitochondrial enzymes is more affected by size, physical condition and season. PMID:24202687

  17. Modeling the Growth Rates of Tetragonal Lysozyme Crystal Faces

    NASA Technical Reports Server (NTRS)

    Li, Meirong; Nadarajah, Arunan; Pusey, Marc L.

    1998-01-01

    The measured macroscopic growth rates of the (110) and (101) faces of tetragonal lysozyme show an unexpectedly complex dependence on the supersaturation. The growth rates decay asymptotically to zero when the supersaturation is lowered to zero and increase rapidly when the supersaturation is increased. When supersaturations are increased still further the growth rates attain a maximum before starting to decrease. However, growth of these crystals is known to proceed by the classical dislocation and 2D nucleation growth mechanisms. This anomaly can be explained if growth is assumed to occur not by monomer units but by lysozyme aggregates. Analysis of the molecular packing of these crystals revealed that they were constructed of strongly bonded 4(sub 3) helices, while weaker bonds were responsible for binding the helices to each other. It follows that during crystal growth the stronger bonds are formed before the weaker ones. Thus, the growth of these crystals could be viewed as a two step process: aggregate growth units corresponding to the 4(sub 3) helix are first formed in the bulk solution by stronger intermolecular bonds and then attached to the crystal face by weaker bonds on dislocation hillocks or 2D islands. This will lead to a distribution of aggregates in the solution with monomers and lower order aggregates being predominant at low supersaturations and higher order aggregates being predominant at high supersaturations. If the crystal grows mostly by higher order aggregates, such as tetramers and octamers, it would explain the anomalous dependence of the growth rates on the supersaturation. Besides the analysis of molecular packing, a comprehensive analysis of the measured (110) and (101) growth rates was also undertaken in this study. The distribution of aggregates in lysozyme nutrient solutions at various solution conditions were determined from reversible aggregation reactions at equilibrium. The supersaturation was defined for each aggregate species

  18. Corn metabolites affect growth and virulence of Agrobacterium tumefaciens.

    PubMed Central

    Sahi, S V; Chilton, M D; Chilton, W S

    1990-01-01

    Homogenates of corn seedlings inhibit both growth of Agrobacterium tumefaciens and induction of its Ti plasmid virulence (vir) genes by acetosyringone (AS). The heat-labile inhibitor has been identified as 2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one (DIMBOA), present in 2-week-old seedlings (B73) at a concentration of 1.5 mM or greater. A concentration of 0.3 mM DIMBOA is sufficient to block growth of A. tumefaciens completely for 220 hr. DIMBOA at 0.1 mM concentration completely inhibited vir gene induction by 100 microM AS and reduced growth rate by 50%. Thus, DIMBOA can be expected to have a significant effect on attempts to transform corn by using A. tumefaciens as a vector. Images PMID:11607078

  19. Growth rate dispersion of single potassium alum crystals

    NASA Astrophysics Data System (ADS)

    Lacmann, Rolf; Tanneberger, Ulrike

    1995-01-01

    The dispersion of growth rates is a lively discussed matter. However, still no acceptable explanation exists for the reason of the phenomenon describing that crystals of the same size growing under the same constant environmental conditions (as supersaturation, temperature and hydrodynamics) might grow with different rates. The individual face-specific growth rates of potassium aluminium alum crystals (diameter 1-3 mm) have been directly determined at different supersaturations ( σ = 0.5-5%). It was found that the order of growth rates of the appearing faces of unhurt and hurt crystals is {111} < {100{ < {110{. Further experiments have shown that face-specific growth rates of unhurt crystals (out of evaporation crystallization) are lower than those of hurt crystals (out of batch crystallization experiments).

  20. Growth and development rates have different thermal responses.

    PubMed

    Forster, Jack; Hirst, Andrew G; Woodward, Guy

    2011-11-01

    Growth and development rates are fundamental to all living organisms. In a warming world, it is important to determine how these rates will respond to increasing temperatures. It is often assumed that the thermal responses of physiological rates are coupled to metabolic rate and thus have the same temperature dependence. However, the existence of the temperature-size rule suggests that intraspecific growth and development are decoupled. Decoupling of these rates would have important consequences for individual species and ecosystems, yet this has not been tested systematically across a range of species. We conducted an analysis on growth and development rate data compiled from the literature for a well-studied group, marine pelagic copepods, and use an information-theoretic approach to test which equations best describe these rates. Growth and development rates were best characterized by models with significantly different parameters: development has stronger temperature dependence than does growth across all life stages. As such, it is incorrect to assume that these rates have the same temperature dependence. We used the best-fit models for these rates to predict changes in organism mass in response to temperature. These predictions follow a concave relationship, which complicates attempts to model the impacts of increasing global temperatures on species body size.

  1. Growth Kinetics and Morphology of Barite Crystals Derived from Face-Specific Growth Rates

    DOE PAGES

    Godinho, Jose R. A.; Stack, Andrew G.

    2015-03-30

    Here we investigate the growth kinetics and morphology of barite (BaSO4) crystals by measuring the growth rates of the (001), (210), (010), and (100) surfaces using vertical scanning interferometry. Solutions with saturation indices 1.1, 2.1, and 3.0 without additional electrolyte, in 0.7 M NaCl, or in 1.3 mM SrCl2 are investigated. Face-specific growth rates are inhibited in the SrCl2 solution relative to a solution without electrolyte, except for (100). Contrarily, growth of all faces is promoted in the NaCl solution. The variation of face-specific rates is solution-specific, which leads to a. change of the crystal morphology and overall growth ratemore » of crystals. The measured face-specific growth rates are used to model the growth of single crystals. Modeled crystals have a morphology and size similar to those grown from solution. Based on the model the time dependence of surface area and growth rates is analyzed. Growth rates change with time due to surface area normalization for small crystals and large growth intervals. By extrapolating rates to crystals with large surfaces areas, time-independent growth rates are 0.783, 2.96, and 0.513 mmol∙m-2∙h-1, for saturation index 2.1 solutions without additional electrolyte, NaCl, and SrCl2, respectively.« less

  2. Seasonal growth rate of the sponge Haliclona oculata (Demospongiae: Haplosclerida).

    PubMed

    Koopmans, Marieke; Wijffels, René H

    2008-01-01

    The interest in sponges has increased rapidly since the discovery of potential new pharmaceutical compounds produced by many sponges. A good method to produce these compounds by using aquaculture of sponges is not yet available, because there is insufficient knowledge about the nutritional needs of sponges. To gain more insight in the nutritional needs for growth, we studied the growth rate of Haliclona oculata in its natural environment and monitored environmental parameters in parallel. A stereo photogrammetry approach was used for measuring growth rates. Stereo pictures were taken and used to measure volumetric changes monthly during 1 year. Volumetric growth rate of Haliclona oculata showed a seasonal trend with the highest average specific growth rate measured in May: 0.012 +/- 0.004 day(-1). In our study a strong positive correlation (p < 0.01) was found for growth rate with temperature, algal biomass (measured as chlorophyll a), and carbon and nitrogen content in suspended particulate matter. A negative correlation (p < 0.05) was found for growth rate with salinity, ammonium, nitrate, nitrite, and phosphate. No correlation was found with dissolved organic carbon, suggesting that Haliclona oculata is more dependent on particulate organic carbon.

  3. High Heating Rates Affect Greatly the Inactivation Rate of Escherichia coli.

    PubMed

    Huertas, Juan-Pablo; Aznar, Arantxa; Esnoz, Arturo; Fernández, Pablo S; Iguaz, Asunción; Periago, Paula M; Palop, Alfredo

    2016-01-01

    Heat resistance of microorganisms can be affected by different influencing factors. Although, the effect of heating rates has been scarcely explored by the scientific community, recent researches have unraveled its important effect on the thermal resistance of different species of vegetative bacteria. Typically heating rates described in the literature ranged from 1 to 20°C/min but the impact of much higher heating rates is unclear. The aim of this research was to explore the effect of different heating rates, such as those currently achieved in the heat exchangers used in the food industry, on the heat resistance of Escherichia coli. A pilot plant tubular heat exchanger and a thermoresistometer Mastia were used for this purpose. Results showed that fast heating rates had a deep impact on the thermal resistance of E. coli. Heating rates between 20 and 50°C/min were achieved in the heat exchanger, which were much slower than those around 20°C/s achieved in the thermoresistometer. In all cases, these high heating rates led to higher inactivation than expected: in the heat exchanger, for all the experiments performed, when the observed inactivation had reached about seven log cycles, the predictions estimated about 1 log cycle of inactivation; in the thermoresistometer these differences between observed and predicted values were even more than 10 times higher, from 4.07 log cycles observed to 0.34 predicted at a flow rate of 70 mL/min and a maximum heating rate of 14.7°C/s. A quantification of the impact of the heating rates on the level of inactivation achieved was established. These results point out the important effect that the heating rate has on the thermal resistance of E. coli, with high heating rates resulting in an additional sensitization to heat and therefore an effective food safety strategy in terms of food processing. PMID:27563300

  4. High Heating Rates Affect Greatly the Inactivation Rate of Escherichia coli.

    PubMed

    Huertas, Juan-Pablo; Aznar, Arantxa; Esnoz, Arturo; Fernández, Pablo S; Iguaz, Asunción; Periago, Paula M; Palop, Alfredo

    2016-01-01

    Heat resistance of microorganisms can be affected by different influencing factors. Although, the effect of heating rates has been scarcely explored by the scientific community, recent researches have unraveled its important effect on the thermal resistance of different species of vegetative bacteria. Typically heating rates described in the literature ranged from 1 to 20°C/min but the impact of much higher heating rates is unclear. The aim of this research was to explore the effect of different heating rates, such as those currently achieved in the heat exchangers used in the food industry, on the heat resistance of Escherichia coli. A pilot plant tubular heat exchanger and a thermoresistometer Mastia were used for this purpose. Results showed that fast heating rates had a deep impact on the thermal resistance of E. coli. Heating rates between 20 and 50°C/min were achieved in the heat exchanger, which were much slower than those around 20°C/s achieved in the thermoresistometer. In all cases, these high heating rates led to higher inactivation than expected: in the heat exchanger, for all the experiments performed, when the observed inactivation had reached about seven log cycles, the predictions estimated about 1 log cycle of inactivation; in the thermoresistometer these differences between observed and predicted values were even more than 10 times higher, from 4.07 log cycles observed to 0.34 predicted at a flow rate of 70 mL/min and a maximum heating rate of 14.7°C/s. A quantification of the impact of the heating rates on the level of inactivation achieved was established. These results point out the important effect that the heating rate has on the thermal resistance of E. coli, with high heating rates resulting in an additional sensitization to heat and therefore an effective food safety strategy in terms of food processing.

  5. High Heating Rates Affect Greatly the Inactivation Rate of Escherichia coli

    PubMed Central

    Huertas, Juan-Pablo; Aznar, Arantxa; Esnoz, Arturo; Fernández, Pablo S.; Iguaz, Asunción; Periago, Paula M.; Palop, Alfredo

    2016-01-01

    Heat resistance of microorganisms can be affected by different influencing factors. Although, the effect of heating rates has been scarcely explored by the scientific community, recent researches have unraveled its important effect on the thermal resistance of different species of vegetative bacteria. Typically heating rates described in the literature ranged from 1 to 20°C/min but the impact of much higher heating rates is unclear. The aim of this research was to explore the effect of different heating rates, such as those currently achieved in the heat exchangers used in the food industry, on the heat resistance of Escherichia coli. A pilot plant tubular heat exchanger and a thermoresistometer Mastia were used for this purpose. Results showed that fast heating rates had a deep impact on the thermal resistance of E. coli. Heating rates between 20 and 50°C/min were achieved in the heat exchanger, which were much slower than those around 20°C/s achieved in the thermoresistometer. In all cases, these high heating rates led to higher inactivation than expected: in the heat exchanger, for all the experiments performed, when the observed inactivation had reached about seven log cycles, the predictions estimated about 1 log cycle of inactivation; in the thermoresistometer these differences between observed and predicted values were even more than 10 times higher, from 4.07 log cycles observed to 0.34 predicted at a flow rate of 70 mL/min and a maximum heating rate of 14.7°C/s. A quantification of the impact of the heating rates on the level of inactivation achieved was established. These results point out the important effect that the heating rate has on the thermal resistance of E. coli, with high heating rates resulting in an additional sensitization to heat and therefore an effective food safety strategy in terms of food processing. PMID:27563300

  6. A Theory of Continuous Rates and Applications to the Theory of Growth and Obsolescence Rates.

    ERIC Educational Resources Information Center

    Egghe, L.

    1994-01-01

    Discusses the measurement of the growth and obsolescence of literature and shows that growth and obsolescence can be studied by the same mathematical techniques. A combined growth-obsolescence theory is presented that can be measured with continuous rates, and three earlier papers are reconsidered and results are reproven. (Contains 18…

  7. Analysis of Monomer Aggregation and Crystal Growth Rates of Lysozyme

    NASA Technical Reports Server (NTRS)

    Nadarajah, Arunan

    1996-01-01

    This project was originally conceived to analyze the extensive data of tetragonal lysozyme crystal growth rates collected at NASA/MSFC by Dr. Marc L. Pusey's research group. At that time the lack of analysis of the growth rates was hindering progress in understanding the growth mechanism of tetragonal lysozyme and other protein crystals. After the project was initiated our initial analysis revealed unexpected complexities in the growth rate behavior. This resulted in an expansion in the scope of the project to include a comprehensive investigation of the growth mechanisms of tetragonal lysozyme crystals. A discussion of this research is included as well a list of presentations and publications resulting from the research. This project contributed significantly toward the education of several students and fostered extensive collaborations between investigators.

  8. Growth rate controlled barium partitioning in calcite and aragonite

    NASA Astrophysics Data System (ADS)

    Goetschl, Katja Elisabeth; Mavromatis, Vasileios; Baldermann, Andre; Purgstaller, Bettina; Dietzel, Martin

    2016-04-01

    The barium (Ba) content and the Ba/Ca molar ratios in biogenic and abiotic carbonates have been widely used from the scientific community as a geochemical proxy especially in marine and early diagenetic settings. The Ba content of carbonate minerals has been earlier associated to changes in oceanic circulation that may have been caused by upwelling, changes in weathering regimes and river-runoff as well as melt water discharge. The physicochemical controls of Ba ion incorporation in the two most abundant CaCO3 polymorphs found in Earth's surface environments, i.e. calcite and aragonite, have adequately been studied only for calcite. These earlier studies (i.e. [1]) suggest that at increasing growth rate, Ba partitioning in calcite is increasing as well. In contrast, to date the effect of growth rate on the partitioning of Ba in aragonite remains questionable, despite the fact that this mineral phase is the predominant carbonate-forming polymorph in shallow marine environments. To shed light on the mechanisms controlling Ba ion uptake in carbonates in this study we performed steady-state Ba co-precipitation experiments with calcite and aragonite at 25°C. The obtained results for the partitioning of Ba in calcite are in good agreement with those reported earlier by [1], whereas those for aragonite indicate a reduction of Ba partitioning at elevated aragonite growth rates, with the partitioning coefficient value between solid and fluid to be approaching the unity. This finding is good agreement with the formation of a solid solution in the aragonite-witherite system, owing to the isostructural crystallography of the two mineral phases. Moreover, our data set provides new insights that are required for reconstructing the evolution of the Ba content of pristine marine versus diagenetically altered carbonate minerals commonly occurring in marine subfloor settings, as the thermodynamically less stable aragonite will transform to calcite enriched in Ba, whilst affecting

  9. A Simple Device to Measure Root Growth Rates

    ERIC Educational Resources Information Center

    Rauser, Wilfried E.; Horton, Roger F.

    1975-01-01

    Describes construction and use of a simple auxanometer which students can use to accurately measure root growth rates of intact seedlings. Typical time course data are presented for the effect of ethylene and indole acetic acid on pea root growth. (Author/BR)

  10. Improving estimates of tree mortality probability using potential growth rate

    USGS Publications Warehouse

    Das, Adrian J.; Stephenson, Nathan L.

    2015-01-01

    Tree growth rate is frequently used to estimate mortality probability. Yet, growth metrics can vary in form, and the justification for using one over another is rarely clear. We tested whether a growth index (GI) that scales the realized diameter growth rate against the potential diameter growth rate (PDGR) would give better estimates of mortality probability than other measures. We also tested whether PDGR, being a function of tree size, might better correlate with the baseline mortality probability than direct measurements of size such as diameter or basal area. Using a long-term dataset from the Sierra Nevada, California, U.S.A., as well as existing species-specific estimates of PDGR, we developed growth–mortality models for four common species. For three of the four species, models that included GI, PDGR, or a combination of GI and PDGR were substantially better than models without them. For the fourth species, the models including GI and PDGR performed roughly as well as a model that included only the diameter growth rate. Our results suggest that using PDGR can improve our ability to estimate tree survival probability. However, in the absence of PDGR estimates, the diameter growth rate was the best empirical predictor of mortality, in contrast to assumptions often made in the literature.

  11. The influence of impurities on the growth rate of calcite

    NASA Astrophysics Data System (ADS)

    Meyer, H. J.

    1984-05-01

    The effects of 34 different additives on the growth rate of calcite were investigated. An initial growth rate of about one crystal monolayer (3 × 10 -8 cm) per minute was adjusted at a constant supersaturation which was maintained by a control circuit. Then the impurity was added step by step and the reduction of the growth rate was measured. The impurity concentration necessary to reduce the initial growth rate by a certain percentage increased in the order Fe 2+, ATP, P 3O 5-10, P 2O 4-7, (PO 3) 6-6, Zn 2+, ADP, Ce 3+, Pb 2+, carbamyl phosphate, Fe 3+, PO 3-4, Co 2+, Mn 2+, Be 2+, β-glycerophosphate, Ni 2+, Cd 2+, "Tris", phenylphosphate, chondroitine sulphate, Ba 2+, citrate, AMP, Sr 2+, tricarballylate, taurine, SO 2-4, Mg 2+ by 4 orders of magnitude. The most effective additives halved the initial growth rate in concentrations of 2 × 10 -8 mol/1. For Fe 2+ the halving concentration was nearly proportional to the initial rate. The mechanism of inhibition by adsorption of the impurities at growth sites (kinks) is discussed.

  12. Protein Thermodynamics Can Be Predicted Directly from Biological Growth Rates

    PubMed Central

    Corkrey, Ross; McMeekin, Tom A.; Bowman, John P.; Ratkowsky, David A.; Olley, June; Ross, Tom

    2014-01-01

    Life on Earth is capable of growing from temperatures well below freezing to above the boiling point of water, with some organisms preferring cooler and others hotter conditions. The growth rate of each organism ultimately depends on its intracellular chemical reactions. Here we show that a thermodynamic model based on a single, rate-limiting, enzyme-catalysed reaction accurately describes population growth rates in 230 diverse strains of unicellular and multicellular organisms. Collectively these represent all three domains of life, ranging from psychrophilic to hyperthermophilic, and including the highest temperature so far observed for growth (122°C). The results provide credible estimates of thermodynamic properties of proteins and obtain, purely from organism intrinsic growth rate data, relationships between parameters previously identified experimentally, thus bridging a gap between biochemistry and whole organism biology. We find that growth rates of both unicellular and multicellular life forms can be described by the same temperature dependence model. The model results provide strong support for a single highly-conserved reaction present in the last universal common ancestor (LUCA). This is remarkable in that it means that the growth rate dependence on temperature of unicellular and multicellular life forms that evolved over geological time spans can be explained by the same model. PMID:24787650

  13. Growth of atmospheric clusters involving cluster-cluster collisions: comparison of different growth rate methods

    NASA Astrophysics Data System (ADS)

    Kontkanen, Jenni; Olenius, Tinja; Lehtipalo, Katrianne; Vehkamäki, Hanna; Kulmala, Markku; Lehtinen, Kari E. J.

    2016-05-01

    We simulated the time evolution of atmospheric cluster concentrations in a one-component system where not only do clusters grow by condensation of monomers, but cluster-cluster collisions also significantly contribute to the growth of the clusters. Our aim was to investigate the consistency of the growth rates of sub-3 nm clusters determined with different methods and the validity of the common approach to use them to estimate particle formation rates. We compared the growth rate corresponding to particle fluxes (FGR), the growth rate derived from the appearance times of clusters (AGR), and the growth rate calculated based on irreversible vapor condensation (CGR). We found that the relation between the different growth rates depends strongly on the external conditions and the properties of the model substance. The difference between the different growth rates was typically highest at the smallest, sub-2 nm sizes. FGR was generally lower than AGR and CGR; at the smallest sizes the difference was often very large, while at sizes larger than 2 nm the growth rates were closer to each other. AGR and CGR were in most cases close to each other at all sizes. The difference between the growth rates was generally lower in conditions where cluster concentrations were high, and evaporation and other losses were thus less significant. Furthermore, our results show that the conventional method used to determine particle formation rates from growth rates may give estimates far from the true values. Thus, care must be taken not only in how the growth rate is determined but also in how it is applied.

  14. Seasonal variations in ectotherm growth rates: Quantifying growth as an intermittent non steady state compensatory process

    USGS Publications Warehouse

    Guarini, J.-M.; Chauvaud, Laurent; Cloern, J.E.; Clavier, J.; Coston-Guarini, J.; Patry, Y.

    2011-01-01

    Generally, growth rates of living organisms are considered to be at steady state, varying only under environmental forcing factors. For example, these rates may be described as a function of light for plants or organic food resources for animals and these could be regulated (or not) by temperature or other conditions. But, what are the consequences for an individual's growth (and also for the population growth) if growth rate variations are themselves dynamic and not steady state? For organisms presenting phases of dormancy or long periods of stress, this is a crucial question. A dynamic perspective for quantifying short-term growth was explored using the daily growth record of the scallop Pecten maximus (L.). This species is a good biological model for ectotherm growth because the shell records growth striae daily. Independently, a generic mathematical function representing the dynamics of mean daily growth rate (MDGR) was implemented to simulate a diverse set of growth patterns. Once the function was calibrated with the striae patterns, the growth rate dynamics appeared as a forced damped oscillation during the growth period having a basic periodicity during two transitory phases (mean duration 43. days) and appearing at both growth start and growth end. This phase is most likely due to the internal dynamics of energy transfer within the organism rather than to external forcing factors. After growth restart, the transitory regime represents successive phases of over-growth and regulation. This pattern corresponds to a typical representation of compensatory growth, which from an evolutionary perspective can be interpreted as an adaptive strategy to coping with a fluctuating environment. ?? 2011 Elsevier B.V.

  15. Seasonal variations in ectotherm growth rates: Quantifying growth as an intermittent non steady state compensatory process

    NASA Astrophysics Data System (ADS)

    Guarini, Jean-Marc; Chauvaud, Laurent; Cloern, James E.; Clavier, Jacques; Coston-Guarini, Jennifer; Patry, Yann

    2011-04-01

    Generally, growth rates of living organisms are considered to be at steady state, varying only under environmental forcing factors. For example, these rates may be described as a function of light for plants or organic food resources for animals and these could be regulated (or not) by temperature or other conditions. But, what are the consequences for an individual's growth (and also for the population growth) if growth rate variations are themselves dynamic and not steady state? For organisms presenting phases of dormancy or long periods of stress, this is a crucial question. A dynamic perspective for quantifying short-term growth was explored using the daily growth record of the scallop Pecten maximus (L.). This species is a good biological model for ectotherm growth because the shell records growth striae daily. Independently, a generic mathematical function representing the dynamics of mean daily growth rate (MDGR) was implemented to simulate a diverse set of growth patterns. Once the function was calibrated with the striae patterns, the growth rate dynamics appeared as a forced damped oscillation during the growth period having a basic periodicity during two transitory phases (mean duration 43 days) and appearing at both growth start and growth end. This phase is most likely due to the internal dynamics of energy transfer within the organism rather than to external forcing factors. After growth restart, the transitory regime represents successive phases of over-growth and regulation. This pattern corresponds to a typical representation of compensatory growth, which from an evolutionary perspective can be interpreted as an adaptive strategy to coping with a fluctuating environment.

  16. Response of Escherichia coli growth rate to osmotic shock.

    PubMed

    Rojas, Enrique; Theriot, Julie A; Huang, Kerwyn Casey

    2014-05-27

    It has long been proposed that turgor pressure plays an essential role during bacterial growth by driving mechanical expansion of the cell wall. This hypothesis is based on analogy to plant cells, for which this mechanism has been established, and on experiments in which the growth rate of bacterial cultures was observed to decrease as the osmolarity of the growth medium was increased. To distinguish the effect of turgor pressure from pressure-independent effects that osmolarity might have on cell growth, we monitored the elongation of single Escherichia coli cells while rapidly changing the osmolarity of their media. By plasmolyzing cells, we found that cell-wall elastic strain did not scale with growth rate, suggesting that pressure does not drive cell-wall expansion. Furthermore, in response to hyper- and hypoosmotic shock, E. coli cells resumed their preshock growth rate and relaxed to their steady-state rate after several minutes, demonstrating that osmolarity modulates growth rate slowly, independently of pressure. Oscillatory hyperosmotic shock revealed that although plasmolysis slowed cell elongation, the cells nevertheless "stored" growth such that once turgor was reestablished the cells elongated to the length that they would have attained had they never been plasmolyzed. Finally, MreB dynamics were unaffected by osmotic shock. These results reveal the simple nature of E. coli cell-wall expansion: that the rate of expansion is determined by the rate of peptidoglycan insertion and insertion is not directly dependent on turgor pressure, but that pressure does play a basic role whereby it enables full extension of recently inserted peptidoglycan. PMID:24821776

  17. Response of Escherichia coli growth rate to osmotic shock.

    PubMed

    Rojas, Enrique; Theriot, Julie A; Huang, Kerwyn Casey

    2014-05-27

    It has long been proposed that turgor pressure plays an essential role during bacterial growth by driving mechanical expansion of the cell wall. This hypothesis is based on analogy to plant cells, for which this mechanism has been established, and on experiments in which the growth rate of bacterial cultures was observed to decrease as the osmolarity of the growth medium was increased. To distinguish the effect of turgor pressure from pressure-independent effects that osmolarity might have on cell growth, we monitored the elongation of single Escherichia coli cells while rapidly changing the osmolarity of their media. By plasmolyzing cells, we found that cell-wall elastic strain did not scale with growth rate, suggesting that pressure does not drive cell-wall expansion. Furthermore, in response to hyper- and hypoosmotic shock, E. coli cells resumed their preshock growth rate and relaxed to their steady-state rate after several minutes, demonstrating that osmolarity modulates growth rate slowly, independently of pressure. Oscillatory hyperosmotic shock revealed that although plasmolysis slowed cell elongation, the cells nevertheless "stored" growth such that once turgor was reestablished the cells elongated to the length that they would have attained had they never been plasmolyzed. Finally, MreB dynamics were unaffected by osmotic shock. These results reveal the simple nature of E. coli cell-wall expansion: that the rate of expansion is determined by the rate of peptidoglycan insertion and insertion is not directly dependent on turgor pressure, but that pressure does play a basic role whereby it enables full extension of recently inserted peptidoglycan.

  18. The growth rate of "clinically significant" renal cancer.

    PubMed

    Gofrit, Ofer N; Yutkin, Vladimir; Zorn, Kevin C; Duvdevani, Mordechai; Landau, Ezekiel H; Hidas, Guy; Pode, Dov

    2015-01-01

    Surveillance studies of enhancing renal masses report on a mean tumor growth rate of about 0.3 cm/year. In most of these studies however, only small tumors in elderly patients were followed. In the current report, we attempt to evaluate the growth rate of "clinically significant" renal carcinomas defined as tumors that were treated immediately upon diagnosis. 46 patients (mean age 64 years SD 11 years) were treated for renal carcinoma. All had a cross-sectional imaging studies performed 6-60 months prior to diagnosis of kidney cancer demonstrating no tumor. Tumor growth rate was calculated by dividing tumor's largest diameter by the time interval between the normal kidney imaging and diagnosis of renal cancer. Mean tumor diameter was 4.5 cm (SD 2.4 cm). Mean time period from the normal imaging to diagnosis of renal cancer was 33.6 months (SD 18 months). According to the proposed model, the average growth rate of "clinically significant" renal carcinomas was 2.13 cm/year (SD 1.45, range 0.2-6.5 cm/year). Tumor growth rate correlated inversely with patient's age (p = 0.007). Patient gender or Fuhrman's grade did not correlate however. The growth rate of "clinically significant" renal cancer appears to be higher than the rate reported in surveillance trials. Renal tumors tend to grow faster in young patients. As such, variable growth rate should be taken into account when considering active surveillance in young patients and when designing trials for evaluation of anti-cancer agents. PMID:26543715

  19. Noise-driven growth rate gain in clonal cellular populations

    PubMed Central

    Hashimoto, Mikihiro; Nozoe, Takashi; Nakaoka, Hidenori; Okura, Reiko; Akiyoshi, Sayo; Kaneko, Kunihiko; Kussell, Edo; Wakamoto, Yuichi

    2016-01-01

    Cellular populations in both nature and the laboratory are composed of phenotypically heterogeneous individuals that compete with each other resulting in complex population dynamics. Predicting population growth characteristics based on knowledge of heterogeneous single-cell dynamics remains challenging. By observing groups of cells for hundreds of generations at single-cell resolution, we reveal that growth noise causes clonal populations of Escherichia coli to double faster than the mean doubling time of their constituent single cells across a broad set of balanced-growth conditions. We show that the population-level growth rate gain as well as age structures of populations and of cell lineages in competition are predictable. Furthermore, we theoretically reveal that the growth rate gain can be linked with the relative entropy of lineage generation time distributions. Unexpectedly, we find an empirical linear relation between the means and the variances of generation times across conditions, which provides a general constraint on maximal growth rates. Together, these results demonstrate a fundamental benefit of noise for population growth, and identify a growth law that sets a “speed limit” for proliferation. PMID:26951676

  20. On the growth rate of gallstones in the human gallbladder

    NASA Astrophysics Data System (ADS)

    Nudelman, I.

    1993-05-01

    The growth rate of a single symmetrically oval shaped gallbladder stone weighing 10.8 g was recorded over a period of six years before surgery and removal. The length of the stone was measured by ultrasonography and the growth rate was found to be linear with time, with a value of 0.4 mm/year. A smaller stone growing in the wall of the gallbladder was detected only three years before removal and grew at a rate of ˜ 1.33 mm/year. The morphology and metallic ion chemical composition of the large stone and of a randomly selected small stone weighing about 1.1 g, extracted from another patient, were analyzed and compared. It was found that the large stone contained besides calcium also lead, whereas the small stone contained mainly calcium. It is possible that the lead causes a difference in mechanism between the growth of a single large and growth of multiple small gallstones.

  1. The Interrelationship between Promoter Strength, Gene Expression, and Growth Rate

    PubMed Central

    Klesmith, Justin R.; Detwiler, Emily E.; Tomek, Kyle J.; Whitehead, Timothy A.

    2014-01-01

    In exponentially growing bacteria, expression of heterologous protein impedes cellular growth rates. Quantitative understanding of the relationship between expression and growth rate will advance our ability to forward engineer bacteria, important for metabolic engineering and synthetic biology applications. Recently, a work described a scaling model based on optimal allocation of ribosomes for protein translation. This model quantitatively predicts a linear relationship between microbial growth rate and heterologous protein expression with no free parameters. With the aim of validating this model, we have rigorously quantified the fitness cost of gene expression by using a library of synthetic constitutive promoters to drive expression of two separate proteins (eGFP and amiE) in E. coli in different strains and growth media. In all cases, we demonstrate that the fitness cost is consistent with the previous findings. We expand upon the previous theory by introducing a simple promoter activity model to quantitatively predict how basal promoter strength relates to growth rate and protein expression. We then estimate the amount of protein expression needed to support high flux through a heterologous metabolic pathway and predict the sizable fitness cost associated with enzyme production. This work has broad implications across applied biological sciences because it allows for prediction of the interplay between promoter strength, protein expression, and the resulting cost to microbial growth rates. PMID:25286161

  2. Investigation of growth rate dispersion in lactose crystallisation by AFM

    NASA Astrophysics Data System (ADS)

    Dincer, T. D.; Ogden, M. I.; Parkinson, G. M.

    2014-09-01

    α-Lactose monohydrate crystals have been reported to exhibit growth rate dispersion (GRD). Variation in surface dislocations has been suggested as the cause of GRD, but this has not been further investigated to date. In this study, growth rate dispersion and the change in morphology were investigated in situ and via bottle roller experiments. The surfaces of the (0 1 0) faces of crystals were examined with Atomic Force Microscopy. Smaller, slow growing crystals tend to have smaller (0 1 0) faces with narrow bases and displayed a single double spiral in the centre of the crystal with 2 nm high steps. Additional double spirals in other crystals resulted in faster growth rates. Large, fast growing crystals were observed to have larger (0 1 0) faces with fast growth in both the a and b directions (giving a broader crystal base) with macro steps parallel to the (c direction). The number and location of spirals or existence of macro steps appears to influence the crystal morphology, growth rates and growth rate dispersion in lactose crystals.

  3. The interrelationship between promoter strength, gene expression, and growth rate.

    PubMed

    Bienick, Matthew S; Young, Katherine W; Klesmith, Justin R; Detwiler, Emily E; Tomek, Kyle J; Whitehead, Timothy A

    2014-01-01

    In exponentially growing bacteria, expression of heterologous protein impedes cellular growth rates. Quantitative understanding of the relationship between expression and growth rate will advance our ability to forward engineer bacteria, important for metabolic engineering and synthetic biology applications. Recently, a work described a scaling model based on optimal allocation of ribosomes for protein translation. This model quantitatively predicts a linear relationship between microbial growth rate and heterologous protein expression with no free parameters. With the aim of validating this model, we have rigorously quantified the fitness cost of gene expression by using a library of synthetic constitutive promoters to drive expression of two separate proteins (eGFP and amiE) in E. coli in different strains and growth media. In all cases, we demonstrate that the fitness cost is consistent with the previous findings. We expand upon the previous theory by introducing a simple promoter activity model to quantitatively predict how basal promoter strength relates to growth rate and protein expression. We then estimate the amount of protein expression needed to support high flux through a heterologous metabolic pathway and predict the sizable fitness cost associated with enzyme production. This work has broad implications across applied biological sciences because it allows for prediction of the interplay between promoter strength, protein expression, and the resulting cost to microbial growth rates.

  4. Growth-rate influences on coral climate proxies

    NASA Astrophysics Data System (ADS)

    Suzuki, A.; Hayashi, E.; Nakamura, T.; Iwase, A.; Ishimura, T.; Iguchi, A.; Sakai, K.; Okai, T.; Inoue, M.; Araoka, D.; Kawahata, H.

    2011-12-01

    Coral-based climate reconstruction has been increasingly reported from many tropical sites. Potential ambiguity of coral thermometers intrinsic in biomineralization process attracts much attention, including so-called 'vital effects', 'growth-rate-related kinetic effect', '[CO32-] effect' and so on. Here we study growth-rate influences on skeletal oxygen and carbon isotope ratios (δ18O and δ13C), as well as Sr/Ca ratio, based on a long-term culture experiment using Porites australiensis clone colonies. Variation in δ18O showed negligible influence against a large intercolony variation in growth rate based on the comparison of the seasonal minimum δ18O values during summer, while that was relatively sensitive to temporal growth-rate change due to health condition of each colony. Contrary, Sr/Ca ratio was robust against both the inter- and intra- colony variation in growth rate. Positive sift in δ13C for slower-growing corals was found, and it can be attributed to a kinetic behavior of calcification reaction. Seasonal fluctuation pattern in δ13C did not correspond to light intensity nor that in δ13C of dissolved inorganic carbon in seawater. These lines warrant the signal recording ability of coral skeletal Sr/Ca ratio and δ18O from a long-lived colony of clonal growth as paleo-climate archives, and propose practical guideline for the proper interplication of coral records.

  5. 7075-T6 and 2024-T351 Aluminum Alloy Fatigue Crack Growth Rate Data

    NASA Technical Reports Server (NTRS)

    Forth, Scott C.; Wright, Christopher W.; Johnston, William M., Jr.

    2005-01-01

    Experimental test procedures for the development of fatigue crack growth rate data has been standardized by the American Society for Testing and Materials. Over the past 30 years several gradual changes have been made to the standard without rigorous assessment of the affect these changes have on the precision or variability of the data generated. Therefore, the ASTM committee on fatigue crack growth has initiated an international round robin test program to assess the precision and variability of test results generated using the standard E647-00. Crack growth rate data presented in this report, in support of the ASTM roundrobin, shows excellent precision and repeatability.

  6. Evolution of thermal physiology and growth rate between populations of the western fence lizard (Sceloporus occidentalis).

    PubMed

    Sinervo, B

    1990-06-01

    Hatchling Sceloporus occidentalis from northern populations (central Oregon) grow more slowly than hatchlings from southern populations (southern California) in nature. In this study, I determine whether this difference in growth rate results from differences in thermal environment and/or in thermoregulatory behavior. To determine the degree to which the thermal environment affects growth rate among populations, I reared hatchings from the northern and southern populations in a cycling thermal regime in one of three experimental treatments differing in access to radiant heat (6, 9, or 12 h radiant heat; remainder of 24 h at 15°C). I also measured the body temperature that each individual voluntarily selected over the course of the daily activity cycle. Growth rate varied positively with duration of access to radiant heat. Within the three treatments, individual growth rate was positively correlated with body temperature. Moreover, the difference in growth rate between the northern and southern populations was due in part to differences in behavior - individuals from northern populations selected lower body temperatures. I found that significant variation in body temperature was associated with family membership, suggesting that thermal physiology has a genetic basis. Moreover, growth rate was correlated with body temperature among families in each population suggesting a genetic correlation underlies the phenotypic correlations. Thus, genetically based variation in thermal physiology contributes to differences in growth rate among individuals within a population as well as to differences among populations. PMID:22160116

  7. Faster is not always better: selection on growth rate fluctuates across life history and environments.

    PubMed

    Monro, Keyne; Marshall, Dustin J

    2014-06-01

    Growth rate is increasingly recognized as a key life-history trait that may affect fitness directly rather than evolve as a by-product of selection on size or age. An ongoing challenge is to explain the abundant levels of phenotypic and genetic variation in growth rates often seen in natural populations, despite what is expected to be consistently strong selection on this trait. Such a paradox suggests limits to how contemporary growth rates evolve. We explored limits arising from variation in selection, based on selection differentials for age-specific growth rates expressed under different ecological conditions. We present results from a field experiment that measured growth rates and reproductive output in wild individuals of a colonial marine invertebrate (Hippopodina iririkiensis), replicated within and across the natural range of succession in its local community. Colony growth rates varied phenotypically throughout this range, but not all such variation was available for selection, nor was it always targeted by selection as expected. While the maintenance of both phenotypic and genetic variation in growth rate is often attributed to costs of growing rapidly, our study highlights the potential for fluctuating selection pressures throughout the life history and across environments to play an important role in this process.

  8. Faster is not always better: selection on growth rate fluctuates across life history and environments.

    PubMed

    Monro, Keyne; Marshall, Dustin J

    2014-06-01

    Growth rate is increasingly recognized as a key life-history trait that may affect fitness directly rather than evolve as a by-product of selection on size or age. An ongoing challenge is to explain the abundant levels of phenotypic and genetic variation in growth rates often seen in natural populations, despite what is expected to be consistently strong selection on this trait. Such a paradox suggests limits to how contemporary growth rates evolve. We explored limits arising from variation in selection, based on selection differentials for age-specific growth rates expressed under different ecological conditions. We present results from a field experiment that measured growth rates and reproductive output in wild individuals of a colonial marine invertebrate (Hippopodina iririkiensis), replicated within and across the natural range of succession in its local community. Colony growth rates varied phenotypically throughout this range, but not all such variation was available for selection, nor was it always targeted by selection as expected. While the maintenance of both phenotypic and genetic variation in growth rate is often attributed to costs of growing rapidly, our study highlights the potential for fluctuating selection pressures throughout the life history and across environments to play an important role in this process. PMID:24823823

  9. Metabolic rate, latitude and thermal stability of roosts, but not phylogeny, affect rewarming rates of bats.

    PubMed

    Menzies, Allyson K; Webber, Quinn M R; Baloun, Dylan E; McGuire, Liam P; Muise, Kristina A; Coté, Damien; Tinkler, Samantha; Willis, Craig K R

    2016-10-01

    Torpor is an adaptation that allows many endotherms to save energy by abandoning the energetic cost of maintaining elevated body temperatures. Although torpor reduces energy consumption, the metabolic heat production required to arouse from torpor is energetically expensive and can impact the overall cost of torpor. The rate at which rewarming occurs can impact the cost of arousal, therefore, factors influencing rewarming rates of heterothermic endotherms could have influenced the evolution of rewarming rates and overall energetic costs of arousal from torpor. Bats are a useful taxon for studies of ecological and behavioral correlates of rewarming rate because of the widespread expression of heterothermy and ecological diversity across the >1200 known species. We used a comparative analysis of 45 bat species to test the hypothesis that ecological, behavioral, and physiological factors affect rewarming rates. We used basal metabolic rate (BMR) as an index of thermogenic capacity, and local climate (i.e., latitude of geographic range), roost stability and maximum colony size as ecological and behavioral predictors of rewarming rate. After controlling for phylogeny, high BMR was associated with rapid rewarming while species that live at higher absolute latitudes and in less thermally stable roosts also rewarmed most rapidly. These patterns suggests that some bat species rely on passive rewarming and social thermoregulation to reduce costs of rewarming, while others might rely on thermogenic capacity to maintain rapid rewarming rates in order to reduce energetic costs of arousal. Our results highlight species-specific traits associated with maintaining positive energy balance in a wide range of climates, while also providing insight into possible mechanisms underlying the evolution of heterothermy in endotherms.

  10. Metabolic rate, latitude and thermal stability of roosts, but not phylogeny, affect rewarming rates of bats.

    PubMed

    Menzies, Allyson K; Webber, Quinn M R; Baloun, Dylan E; McGuire, Liam P; Muise, Kristina A; Coté, Damien; Tinkler, Samantha; Willis, Craig K R

    2016-10-01

    Torpor is an adaptation that allows many endotherms to save energy by abandoning the energetic cost of maintaining elevated body temperatures. Although torpor reduces energy consumption, the metabolic heat production required to arouse from torpor is energetically expensive and can impact the overall cost of torpor. The rate at which rewarming occurs can impact the cost of arousal, therefore, factors influencing rewarming rates of heterothermic endotherms could have influenced the evolution of rewarming rates and overall energetic costs of arousal from torpor. Bats are a useful taxon for studies of ecological and behavioral correlates of rewarming rate because of the widespread expression of heterothermy and ecological diversity across the >1200 known species. We used a comparative analysis of 45 bat species to test the hypothesis that ecological, behavioral, and physiological factors affect rewarming rates. We used basal metabolic rate (BMR) as an index of thermogenic capacity, and local climate (i.e., latitude of geographic range), roost stability and maximum colony size as ecological and behavioral predictors of rewarming rate. After controlling for phylogeny, high BMR was associated with rapid rewarming while species that live at higher absolute latitudes and in less thermally stable roosts also rewarmed most rapidly. These patterns suggests that some bat species rely on passive rewarming and social thermoregulation to reduce costs of rewarming, while others might rely on thermogenic capacity to maintain rapid rewarming rates in order to reduce energetic costs of arousal. Our results highlight species-specific traits associated with maintaining positive energy balance in a wide range of climates, while also providing insight into possible mechanisms underlying the evolution of heterothermy in endotherms. PMID:27317837

  11. Does livestock grazing affect sediment deposition and accretion rates in salt marshes?

    NASA Astrophysics Data System (ADS)

    Nolte, Stefanie; Müller, Frauke; Schuerch, Mark; Wanner, Antonia; Esselink, Peter; Bakker, Jan P.; Jensen, Kai

    2013-12-01

    Accretion rates, defined as the vertical growth of salt marshes measured in mm per year, may be influenced by grazing livestock in two ways: directly, by increasing soil compaction through trampling, and indirectly, by reducing aboveground biomass and thus decreasing sediment deposition rates measured in g/m² per year. Although accretion rates and the resulting surface elevation change largely determine the resilience of salt marshes to sea-level rise (SLR), the effect of livestock grazing on accretion rates has been little studied. Therefore, this study aimed to investigate the effect of livestock grazing on salt-marsh accretion rates. We hypothesise that accretion will be lower in grazed compared to ungrazed salt marshes. In four study sites along the mainland coast of the Wadden Sea (in the south-eastern North Sea), accretion rates, sediment deposition rates, and soil compaction of grazed and ungrazed marshes were analysed using the 137Cs radionuclide dating method. Accretion rates were on average 11.6 mm yr-1 during recent decades and thus higher than current and projected rates of SLR. Neither accretion nor sediment deposition rates were significantly different between grazing treatments. Meanwhile, soil compaction was clearly affected by grazing with significantly higher dry bulk density on grazed compared to ungrazed parts. Based on these results, we conclude that other factors influence whether grazing has an effect on accretion and sediment deposition rates and that the effect of grazing on marsh growth does not follow a direct causal chain. It may have a great importance when interacting with other biotic and abiotic processes on the marsh.

  12. Medium-dependent control of the bacterial growth rate.

    PubMed

    Ehrenberg, Måns; Bremer, Hans; Dennis, Patrick P

    2013-04-01

    By combining results from previous studies of nutritional up-shifts we here re-investigate how bacteria adapt to different nutritional environments by adjusting their macromolecular composition for optimal growth. We demonstrate that, in contrast to a commonly held view the macromolecular composition of bacteria does not depend on the growth rate as an independent variable, but on three factors: (i) the genetic background (i.e. the strain used), (ii) the physiological history of the bacteria used for inoculation of a given growth medium, and (iii) the kind of nutrients in the growth medium. These factors determine the ribosome concentration and the average rate of protein synthesis per ribosome, and thus the growth rate. Immediately after a nutritional up-shift, the average number of ribosomes in the bacterial population increases exponentially with time at a rate which eventually is attained as the final post-shift growth rate of all cell components. After a nutritional up-shift from one minimal medium to another minimal medium of higher nutritional quality, ribosome and RNA polymerase syntheses are co-regulated and immediately increase by the same factor equal to the increase in the final growth rate. However, after an up-shift from a minimal medium to a medium containing all 20 amino acids, RNA polymerase and ribosome syntheses are no longer coregulated; a smaller rate of synthesis of RNA polymerase is compensated by a gradual increase in the fraction of free RNA polymerase, possibly due to a gradual saturation of mRNA promoters. We have also analyzed data from a recent publication, in which it was concluded that the macromolecular composition in terms of RNA/protein and RNA/DNA ratios is solely determined by the effector molecule ppGpp. Our analysis indicates that this is true only in special cases and that, in general, medium adaptation also depends on factors other than ppGpp.

  13. An assessment of bird habitat quality using population growth rates

    USGS Publications Warehouse

    Knutson, M.G.; Powell, L.A.; Hines, R.K.; Friberg, M.A.; Niemi, G.J.

    2006-01-01

    Survival and reproduction directly affect population growth rate (lambda) making lambda a fundamental parameter for assessing habitat quality. We used field data, literature review, and a computer simulation to predict annual productivity and lambda for several species of landbirds breeding in floodplain and upland forests in the Midwestern United States. We monitored 1735 nests of 27 species; 760 nests were in the uplands and 975 were in the floodplain. Each type of forest habitat (upland and floodplain) was a source habitat for some species. Despite a relatively low proportion of regional forest cover, the majority of species had stable or increasing populations in all or some habitats, including six species of conservation concern. In our search for a simple analog for lambda, we found that only adult apparent survival, juvenile survival, and annual productivity were correlated with lambda; daily nest survival and relative abundance estimated from point counts were not. Survival and annual productivity are among the most costly demographic parameters to measure and there does not seem to be a low-cost alternative. In addition, our literature search revealed that the demographic parameters needed to model annual productivity and lambda were unavailable for several species. More collective effort across North America is needed to fill the gaps in our knowledge of demographic parameters necessary to model both annual productivity and lambda. Managers can use habitat-specific predictions of annual productivity to compare habitat quality among species and habitats for purposes of evaluating management plans.

  14. Increase in Growth Cone Size Correlates with Decrease in Neurite Growth Rate

    PubMed Central

    Ren, Yuan

    2016-01-01

    Several important discoveries in growth cone cell biology were made possible by the use of growth cones derived from cultured Aplysia bag cell neurons, including the characterization of the organization and dynamics of the cytoskeleton. The majority of these Aplysia studies focused on large growth cones induced by poly-L-lysine substrates at early stages in cell culture. Under these conditions, the growth cones are in a steady state with very little net advancement. Here, we offer a comprehensive cellular analysis of the motile behavior of Aplysia growth cones in culture beyond this pausing state. We found that average growth cone size decreased with cell culture time whereas average growth rate increased. This inverse correlation of growth rate and growth cone size was due to the occurrence of large growth cones with a peripheral domain larger than 100 μm2. The large pausing growth cones had central domains that were less consistently aligned with the direction of growth and could be converted into smaller, faster-growing growth cones by addition of a three-dimensional collagen gel. We conclude that the significant lateral expansion of lamellipodia and filopodia as observed during these culture conditions has a negative effect on neurite growth. PMID:27274874

  15. Effect of low dose rate radiation on cell growth kinetics.

    PubMed Central

    Gregg, E C; Yau, T M; Kim, S C

    1979-01-01

    Experimental determinations were made of cell number as a function of time for two strains of L5178Y mammalian cells maintained continuously in various environments of radiation. One strain possessed a shoulder in its dose response curve whereas the other did not. Neither strain showed any significant difference in growth rate for interdivision doses on the order of the median lethal dose or less delivered continuously at a low dose rate or pulsed every 4 h at a high instantaneous dose rate. It was also shown that large numbers of dead cells have little effect on growth rate and that these dead cells last as discrete entities for many days. A simple theory of growth rate in the presence of radiation is presented, and the agreement with the observations implies that there is no effect of any sublethal low dose rate radiation received in one generation on the growth rate or radiation sensitivity of the succeeding generation. Further analysis of the data also showed that for the no-shoulder cells at 37 degrees C, tritiated water had a relative biological effect close to unity for cell sterilization. PMID:262446

  16. Noise in gene expression is coupled to growth rate.

    PubMed

    Keren, Leeat; van Dijk, David; Weingarten-Gabbay, Shira; Davidi, Dan; Jona, Ghil; Weinberger, Adina; Milo, Ron; Segal, Eran

    2015-12-01

    Genetically identical cells exposed to the same environment display variability in gene expression (noise), with important consequences for the fidelity of cellular regulation and biological function. Although population average gene expression is tightly coupled to growth rate, the effects of changes in environmental conditions on expression variability are not known. Here, we measure the single-cell expression distributions of approximately 900 Saccharomyces cerevisiae promoters across four environmental conditions using flow cytometry, and find that gene expression noise is tightly coupled to the environment and is generally higher at lower growth rates. Nutrient-poor conditions, which support lower growth rates, display elevated levels of noise for most promoters, regardless of their specific expression values. We present a simple model of noise in expression that results from having an asynchronous population, with cells at different cell-cycle stages, and with different partitioning of the cells between the stages at different growth rates. This model predicts non-monotonic global changes in noise at different growth rates as well as overall higher variability in expression for cell-cycle-regulated genes in all conditions. The consistency between this model and our data, as well as with noise measurements of cells growing in a chemostat at well-defined growth rates, suggests that cell-cycle heterogeneity is a major contributor to gene expression noise. Finally, we identify gene and promoter features that play a role in gene expression noise across conditions. Our results show the existence of growth-related global changes in gene expression noise and suggest their potential phenotypic implications. PMID:26355006

  17. Noise in gene expression is coupled to growth rate

    PubMed Central

    Keren, Leeat; van Dijk, David; Weingarten-Gabbay, Shira; Davidi, Dan; Jona, Ghil; Weinberger, Adina; Milo, Ron; Segal, Eran

    2015-01-01

    Genetically identical cells exposed to the same environment display variability in gene expression (noise), with important consequences for the fidelity of cellular regulation and biological function. Although population average gene expression is tightly coupled to growth rate, the effects of changes in environmental conditions on expression variability are not known. Here, we measure the single-cell expression distributions of approximately 900 Saccharomyces cerevisiae promoters across four environmental conditions using flow cytometry, and find that gene expression noise is tightly coupled to the environment and is generally higher at lower growth rates. Nutrient-poor conditions, which support lower growth rates, display elevated levels of noise for most promoters, regardless of their specific expression values. We present a simple model of noise in expression that results from having an asynchronous population, with cells at different cell-cycle stages, and with different partitioning of the cells between the stages at different growth rates. This model predicts non-monotonic global changes in noise at different growth rates as well as overall higher variability in expression for cell-cycle–regulated genes in all conditions. The consistency between this model and our data, as well as with noise measurements of cells growing in a chemostat at well-defined growth rates, suggests that cell-cycle heterogeneity is a major contributor to gene expression noise. Finally, we identify gene and promoter features that play a role in gene expression noise across conditions. Our results show the existence of growth-related global changes in gene expression noise and suggest their potential phenotypic implications. PMID:26355006

  18. Correlation of thrombosis growth rate to pathological wall shear rate during platelet accumulation.

    PubMed

    Bark, David L; Para, Andrea N; Ku, David N

    2012-10-01

    Local hemodynamics may strongly influence atherothrombosis, which can lead to acute myocardial infarction and stroke. The relationship between hemodynamics and thrombosis during platelet accumulation was studied through an in vitro flow system consisting of a stenosis. Specifically, wall shear rates (WSR) ranging from 0 to 100,000 s(-1) were ascertained through computations and compared with thrombus growth rates found by image analysis for over 5,000 individual observation points per experiment. A positive correlation (P < 0.0001) was found between thrombus accumulation rates and WSR up to 6,000 s(-1), with a decrease in growth rates at WSR >6,000 s(-1) (P < 0.0001). Furthermore, growth rates at pathological shear rates were found to be two to four times greater than for physiological arterial shear rates below 400 s(-1). Platelets did not accumulate for the first minute of perfusion. The initial lag time, before discernible thrombus growth could be found, diminished with shear (P < 0.0001). These studies show the quantitative increase in thrombus growth rates with very high shear rates in stenoses onto a collagen substrate. PMID:22539078

  19. Shoot Turgor Does Not Limit Shoot Growth of NaCl-Affected Wheat and Barley 1

    PubMed Central

    Termaat, Annie; Passioura, John B.; Munns, Rana

    1985-01-01

    The aim of this work was to test the hypothesis that the reduced growth rate of wheat and barley that results when the roots are exposed to NaCl is due to inadequate turgor in the expanding cells of the leaves. The hypothesis was tested by exposing plants to 100 millimolar NaCl (which reduced their growth rates by about 20%), growing them for 7 to 10 days with their roots in pressure chambers, and applying sufficient pneumatic pressure in the chambers to offset the osmotic pressure of the NaCl, namely, 0.48 megapascals. The results showed that applying the pressure had no sustained effect (relative to unpressurized controls) on growth rates, transpiration rates, or osmotic pressures of the cell sap, in either the fully expanded or currently expanding leaf tissue, of both wheat and barley. The results indicate that the applied pressure correspondingly increased turgor in the shoot although this was not directly measured. We conclude that shoot turgor alone was not regulating the growth of these NaCl-affected plants, and, after discussing other possible influences, argue that a message arising in the roots may be regulating the growth of the shoot. PMID:16664152

  20. PEPA-1* genotype affects return rate for hatchery steelhead

    USGS Publications Warehouse

    Reisenbichler, R.R.; Hayes, M.C.; Rubin, S.P.; Wetzel, L.A.; Baker, B.M.

    2006-01-01

    Allozymes continue to be useful as genetic markers in a variety of studies; however, their utility often hinges on the selective neutrality of the allelic variation. Our study tested for neutrality between the two most common alleles (*100 and *110) at the cytosol nonspecific dipeptidase locus (PEPA-1*) in steelhead Oncorhynchus mykiss from Dworshak National Fish Hatchery in Idaho. We tested for differential growth and survival among fish with the * 100/100, *100/ 110, and *110/110 genotypes rearing in a hatchery or a natural stream. We repeated the study for two year-classes, using heterozygous (*100/110) adults to make the experimental crosses. This design avoided differences in family contribution among genotypes because each cross produced all three genotypes. We divided the progeny from each family into two groups. One group was reared in a hatchery for 1 year and then released for migration to the sea and subsequent return to the hatchery as adults. The other group was released into a natural stream and monitored for 3 years. We found no significant differences in size or survival among PEPA-1* genotypes for either the naturally reared fish or the hatchery-reared fish immediately prior to release as smolts. For females, survival to returning adult also was similar among genotypes; however, hatchery-reared males with the *110/110 genotype returned at a higher rate than did males with the *100/ 100 genotype; heterozygous males were intermediate. These results indicate that selection occurs at the PEPA-1* locus or at one or more loci tightly linked to it. The finding of nearly equal frequencies for these two alleles in the source population suggests that selection differentials among genotypes reverse or vary from year to year; otherwise, steady directional selection would drive the *100 allele to low frequencies or extinction. Locus PEPA-1* seems inappropriate for genetic marks in studies of steelhead that span the full life cycle and probably should be avoided

  1. Protein restriction during pregnancy affects postnatal growth in swine progeny.

    PubMed

    Schoknecht, P A; Pond, W G; Mersmann, H J; Maurer, R R

    1993-11-01

    Protein deficiency during pregnancy affects fetal development. The critical period, when the fetus is most susceptible to maternal protein deficiency and its effect on neonatal growth, is unknown. Therefore, we studied the effect of a protein-restricted diet during early and late pregnancy and throughout pregnancy on growth of pigs from birth to market weight. Sows were fed a control (13% protein) or protein-restricted (0.5% protein) diet throughout pregnancy or protein-restricted diet from d 1 to 44, then control diet to term or control diet from d 1 to 81, then the protein-restricted diet to term. In Experiment 1, birth weights were measured, and 12 pigs/diet group were weaned at 4 wk and raised to market weight. Feeding the protein-restricted diet throughout pregnancy reduced birth and slaughter weights, whereas the control followed by protein-restricted and protein-restricted followed by control diets reduced only birth weight relative to controls. Indices of carcass lean were reduced in the protein-restricted piglets, with carcass fat not affected. In Experiment 2, control and control-protein-restricted litters were reduced to six piglets and 3/litter cross-fostered to a sow of the other treatment group. After weaning at 4 wk, 4 piglets/group were individually fed to 8 wk. The control and control followed by protein-restricted diet fed piglets had similar weights at birth, but piglets raised by a control-protein-restricted sow tended to weight less at weaning than their littermates raised by a control sow. After weaning, these piglets had greater feed intakes relative to other groups and there were no weight differences by 8 wk.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. The effect of light direction and suspended cell concentrations on algal biofilm growth rates.

    PubMed

    Schnurr, Peter J; Espie, George S; Allen, D Grant

    2014-10-01

    Algae biofilms were grown in a semicontinuous flat plate biofilm photobioreactor to study the effects of light direction and suspended algal cell populations on algal biofilm growth. It was determined that, under the growth conditions and biofilm thicknesses studied, light direction had no effect on long-term algal biofilm growth (26 days); however, light direction did affect the concentration of suspended algal cells by influencing the photon flux density in the growth medium in the photobioreactors. This suspended algal cell population affected short-term (7 days) algae cell recruitment and algal biofilm growth, but additional studies showed that enhanced suspended algal cell populations did not affect biofilm growth rates over the long term (26 days). Studying profiles of light transmittance through biofilms as they grew showed that most of the light became attenuated by the biomass after just a few days of growth (88 % after 3 days). The estimated biofilm thicknesses after these few days of growth were approximately 150 μm. The light attenuation data suggests that, although the biofilms grew to 700-900 μm, under these light intensities, only the first few hundred micrometers of the biofilm is receiving enough light to be photosynthetically active. We postulate that this photosynthetically active layer of the biofilm grows adjacent to the light source, while the rest of the biofilm is in a stationary growth phase. The results of this study have implications for algal biofilm photobioreactor design and operation.

  3. The effect of light direction and suspended cell concentrations on algal biofilm growth rates.

    PubMed

    Schnurr, Peter J; Espie, George S; Allen, D Grant

    2014-10-01

    Algae biofilms were grown in a semicontinuous flat plate biofilm photobioreactor to study the effects of light direction and suspended algal cell populations on algal biofilm growth. It was determined that, under the growth conditions and biofilm thicknesses studied, light direction had no effect on long-term algal biofilm growth (26 days); however, light direction did affect the concentration of suspended algal cells by influencing the photon flux density in the growth medium in the photobioreactors. This suspended algal cell population affected short-term (7 days) algae cell recruitment and algal biofilm growth, but additional studies showed that enhanced suspended algal cell populations did not affect biofilm growth rates over the long term (26 days). Studying profiles of light transmittance through biofilms as they grew showed that most of the light became attenuated by the biomass after just a few days of growth (88 % after 3 days). The estimated biofilm thicknesses after these few days of growth were approximately 150 μm. The light attenuation data suggests that, although the biofilms grew to 700-900 μm, under these light intensities, only the first few hundred micrometers of the biofilm is receiving enough light to be photosynthetically active. We postulate that this photosynthetically active layer of the biofilm grows adjacent to the light source, while the rest of the biofilm is in a stationary growth phase. The results of this study have implications for algal biofilm photobioreactor design and operation. PMID:25149444

  4. Do plastic particles affect microalgal photosynthesis and growth?

    PubMed

    Sjollema, Sascha B; Redondo-Hasselerharm, Paula; Leslie, Heather A; Kraak, Michiel H S; Vethaak, A Dick

    2016-01-01

    The unbridled increase in plastic pollution of the world's oceans raises concerns about potential effects these materials may have on microalgae, which are primary producers at the basis of the food chain and a major global source of oxygen. Our current understanding about the potential modes and mechanisms of toxic action that plastic particles exert on microalgae is extremely limited. How effects might vary with particle size and the physico-chemical properties of the specific plastic material in question are equally unelucidated, but may hold clues to how toxicity, if observed, is exerted. In this study we selected polystyrene particles, both negatively charged and uncharged, and three different sizes (0.05, 0.5 and 6μm) for testing the effects of size and material properties. Microalgae were exposed to different polystyrene particle sizes and surface charges for 72h. Effects on microalgal photosynthesis and growth were determined by pulse amplitude modulation fluorometry and flow cytometry, respectively. None of the treatments tested in these experiments had an effect on microalgal photosynthesis. Microalgal growth was negatively affected (up to 45%) by uncharged polystyrene particles, but only at high concentrations (250mg/L). Additionally, these adverse effects were demonstrated to increase with decreasing particle size.

  5. Do plastic particles affect microalgal photosynthesis and growth?

    PubMed

    Sjollema, Sascha B; Redondo-Hasselerharm, Paula; Leslie, Heather A; Kraak, Michiel H S; Vethaak, A Dick

    2016-01-01

    The unbridled increase in plastic pollution of the world's oceans raises concerns about potential effects these materials may have on microalgae, which are primary producers at the basis of the food chain and a major global source of oxygen. Our current understanding about the potential modes and mechanisms of toxic action that plastic particles exert on microalgae is extremely limited. How effects might vary with particle size and the physico-chemical properties of the specific plastic material in question are equally unelucidated, but may hold clues to how toxicity, if observed, is exerted. In this study we selected polystyrene particles, both negatively charged and uncharged, and three different sizes (0.05, 0.5 and 6μm) for testing the effects of size and material properties. Microalgae were exposed to different polystyrene particle sizes and surface charges for 72h. Effects on microalgal photosynthesis and growth were determined by pulse amplitude modulation fluorometry and flow cytometry, respectively. None of the treatments tested in these experiments had an effect on microalgal photosynthesis. Microalgal growth was negatively affected (up to 45%) by uncharged polystyrene particles, but only at high concentrations (250mg/L). Additionally, these adverse effects were demonstrated to increase with decreasing particle size. PMID:26675372

  6. Artificial Polychromatic Light Affects Growth and Physiology in Chicks

    PubMed Central

    Yang, Bo; Yu, Yonghua

    2014-01-01

    Despite the overwhelming use of artificial light on captive animals, its effect on those animals has rarely been studied experimentally. Housing animals in controlled light conditions is useful for assessing the effects of light. The chicken is one of the best-studied animals in artificial light experiments, and here, we evaluate the effect of polychromatic light with various green and blue components on the growth and physiology in chicks. The results indicate that green-blue dual light has two side-effects on chick body mass, depending on the various green to blue ratios. Green-blue dual light with depleted and medium blue component decreased body mass, whereas enriched blue component promoted body mass in chicks compared with monochromatic green- or blue spectra-treated chicks. Moreover, progressive changes in the green to blue ratios of green-blue dual light could give rise to consistent progressive changes in body mass, as suggested by polychromatic light with higher blue component resulting in higher body mass. Correlation analysis confirmed that food intake was positively correlated with final body mass in chicks (R2 = 0.7664, P = 0.0001), suggesting that increased food intake contributed to the increased body mass in chicks exposed to higher blue component. We also found that chicks exposed to higher blue component exhibited higher blood glucose levels. Furthermore, the glucose level was positively related to the final body mass (R2 = 0.6406, P = 0.0001) and food intake (R2 = 0.784, P = 0.0001). These results demonstrate that spectral composition plays a crucial role in affecting growth and physiology in chicks. Moreover, consistent changes in spectral components might cause the synchronous response of growth and physiology. PMID:25469877

  7. Energetics and growth rate of northern Shrike (Lanius excubitor) nestlings

    SciTech Connect

    Degen, A.A.; Kam, M. ); Pinshow, B.; Yosef, R. ); Nagy, K.A. )

    1992-12-01

    Northern Shrikes (Lanius excubitor) breed in a variety of habitats, including deserts. Deserts are characterized by unpredictable food supplies, which can lead to a slow growth rate of nestlings. However, given that Northern Shrike males use prey from their caches to augment freshly caught prey in providing food for their mates and nestlings, we hypothesized that their nestlings do not have a slow growth rate, but one that is equivalent to that in other passerine nestlings from temperate areas. To test this hypothesis, we measured growth rates and energy use in Northern Shrike nestlings and fledglings. We also measured energy expenditure in two adult males that were attending nests. Growth rate of Northern Shrike nestlings was similar to that predicted for passerines in temperate areas and therefore our hypothesis was supported. However, metabolizable energy available in the cache amounted to only [approx] 7.2% of the total energy requirements of the nestlings or 4.2% of the total energy requirements of parents and nestlings during the nestling period. This suggested that other factors in addition to the cache were important in determining growth rate. These included (1) an extremely low maintenance energy requirement of the nestling; 30% of that predicted for a bird of its body mass when it weighed 10 g, which gradually increased to 70% at 50 g. This allowed for more of the energy intake to be used for growth and also reduced foraging costs of males; (2) the relatively low amount of body energy retained as a fraction of metabolizable energy intake, 0.15 to 0.16, indicating that more water per unit growth was incorporated than in other passerines. 47 refs., 5 figs., 2 tabs.

  8. Growth rate paradox of Salmonella typhimurium within host macrophages.

    PubMed Central

    Abshire, K Z; Neidhardt, F C

    1993-01-01

    The growth rate of Salmonella typhimurium U937 within host macrophages was estimated by two independent methods. The extent to which ribosomal protein L12 is acetylated to produce ribosomal protein L7 changes markedly with the growth rate. By this measure, the intracellular bacteria appeared to be growing rapidly. Measurements of viable bacteria, however, indicated that the bacteria were growing slowly. A solution of this apparent growth rate paradox was sought by treating U937 cells infected with S. typhimurium X3306 with ampicillin or chloramphenicol to help determine the number of bacteria that were actively growing and dividing in the intracellular condition. Use of these antibiotics showed that by 2 h after invasion, the intracellular bacteria consisted of at least two populations, one static and the other rapidly dividing. This finding implies that previously described changes in the gene expression of S. typhimurium are important for the survival and/or multiplication of the bacteria within the macrophage. Images PMID:8509329

  9. Influence of corruption on economic growth rate and foreign investment

    NASA Astrophysics Data System (ADS)

    Podobnik, Boris; Shao, Jia; Njavro, Djuro; Ivanov, Plamen Ch.; Stanley, H. E.

    2008-06-01

    We analyze the dependence of the Gross Domestic Product ( GDP) per capita growth rates on changes in the Corruption Perceptions Index ( CPI). For the period 1999 2004 for all countries in the world, we find on average that an increase of CPI by one unit leads to an increase of the annual GDP per capita growth rate by 1.7%. By regressing only the European countries with transition economies, we find that an increase of CPI by one unit generates an increase of the annual GDP per capita growth rate by 2.4%. We also analyze the relation between foreign direct investments received by different countries and CPI, and we find a statistically significant power-law functional dependence between foreign direct investment per capita and the country corruption level measured by the CPI. We introduce a new measure to quantify the relative corruption between countries based on their respective wealth as measured by GDP per capita.

  10. Growth rates in a captive population of Tonkean macaques.

    PubMed

    Sanna, Andrea; De Marco, Arianna; Thierry, Bernard; Cozzolino, Roberto

    2015-07-01

    Measuring variations in body mass is necessary to gain a deeper understanding of the evolution of life-history patterns, and it provides information on the timing of sexual maturity and the development of sexual dimorphism. In this study, we collected longitudinal data on body mass from infancy to adulthood in a captive population of Tonkean macaques (Macaca tonkeana). Tests to evaluate whether social group, maternal age, and dominance rank influenced growth rates showed that they had no significant effect. We investigated the timing and magnitude of breaking points in the growth paths of males and females, and checked whether these breaking points could correspond to specific reproductive and morphological developmental events. We found that male and female Tonkean macaques have roughly equivalent body masses until around the age of four, when males go through an adolescent growth spurt and females continue to grow at a constant rate. Males not only grow faster than females, but they also continue to grow for nearly one and a half years after females have attained their full body mass. Growth rate differences account for approximately two-thirds of the body mass sexual dimorphism; only the remaining third results from continued male growth beyond the age where full body mass is reached in females. We also discovered remarkable correspondences between the timing of testicular enlargement and the adolescent growth spurt in males, and between dental development and slowdown breaking points in both sexes.

  11. Leptin expression affects metabolic rate in zebrafish embryos (D. rerio).

    PubMed

    Dalman, Mark R; Liu, Qin; King, Mason D; Bagatto, Brian; Londraville, Richard L

    2013-01-01

    We used antisense morpholino oligonucleotide technology to knockdown leptin-(A) gene expression in developing zebrafish embryos and measured its effects on metabolic rate and cardiovascular function. Using two indicators of metabolic rate, oxygen consumption was significantly lower in leptin morphants early in development [<48 hours post-fertilization (hpf)], while acid production was significantly lower in morphants later in development (>48 hpf). Oxygen utilization rates in <48 hpf embryos and acid production in 72 hpf embryos could be rescued to that of wildtype embryos by recombinant leptin coinjected with antisense morpholino. Leptin is established to influence metabolic rate in mammals, and these data suggest leptin signaling also influences metabolic rate in fishes.

  12. Factors affecting credit rating downgrades of hospital revenue bonds.

    PubMed

    McCue, M J; Renn, S C; Pillari, G D

    1990-01-01

    This paper identifies the key institutional, operational, financial, and market-area factors associated with downgrades in the credit ratings of hospitals' outstanding, tax-exempt revenue bonds between 1985 and 1988. We examined data from 41 hospitals whose ratings had been downgraded from A to BBB by Standard and Poor's Corp., as well as data from 17 hospitals whose ratings had been downgraded from BBB to BB and lower, compared with hospitals having unchanged A and BBB ratings, respectively. The analysis found only two variables--the hospital's occupancy rate and its ratio of cash and cash equivalents to debt service payments--that were significantly associated with both types of downgrades.

  13. Carbon nanotubes are able to penetrate plant seed coat and dramatically affect seed germination and plant growth.

    PubMed

    Khodakovskaya, Mariya; Dervishi, Enkeleda; Mahmood, Meena; Xu, Yang; Li, Zhongrui; Watanabe, Fumiya; Biris, Alexandru S

    2009-10-27

    Carbon nanotubes (CNTs) were found to penetrate tomato seeds and affect their germination and growth rates. The germination was found to be dramatically higher for seeds that germinated on medium containing CNTs (10-40 mug/mL) compared to control. Analytical methods indicated that the CNTs are able to penetrate the thick seed coat and support water uptake inside seeds, a process which can affect seed germination and growth of tomato seedlings. PMID:19772305

  14. Radiocarbon Based Ages and Growth Rates: Hawaiian Deep Sea Corals

    SciTech Connect

    Roark, E B; Guilderson, T P; Dunbar, R B; Ingram, B L

    2006-01-13

    The radial growth rates and ages of three different groups of Hawaiian deep-sea 'corals' were determined using radiocarbon measurements. Specimens of Corallium secundum, Gerardia sp., and Leiopathes glaberrima, were collected from 450 {+-} 40 m at the Makapuu deep-sea coral bed using a submersible (PISCES V). Specimens of Antipathes dichotoma were collected at 50 m off Lahaina, Maui. The primary source of carbon to the calcitic C. secundum skeleton is in situ dissolved inorganic carbon (DIC). Using bomb {sup 14}C time markers we calculate radial growth rates of {approx} 170 {micro}m y{sup -1} and ages of 68-75 years on specimens as tall as 28 cm of C. secundum. Gerardia sp., A. dichotoma, and L. glaberrima have proteinaceous skeletons and labile particulate organic carbon (POC) is their primary source of architectural carbon. Using {sup 14}C we calculate a radial growth rate of 15 {micro}m y{sup -1} and an age of 807 {+-} 30 years for a live collected Gerardia sp., showing that these organisms are extremely long lived. Inner and outer {sup 14}C measurements on four sub-fossil Gerardia spp. samples produce similar growth rate estimates (range 14-45 {micro}m y{sup -1}) and ages (range 450-2742 years) as observed for the live collected sample. Similarly, with a growth rate of < 10 {micro}m y{sup -1} and an age of {approx}2377 years, L. glaberrima at the Makapuu coral bed, is also extremely long lived. In contrast, the shallow-collected A. dichotoma samples yield growth rates ranging from 130 to 1,140 {micro}m y{sup -1}. These results show that Hawaiian deep-sea corals grow more slowly and are older than previously thought.

  15. Crystallographic anisotropy of growth and etch rates of CVD diamond

    SciTech Connect

    Wolfer, M; Biener, J; El-dasher, B S; Biener, M M; Hamza, A V; Kriele, A; Wild, C

    2008-08-05

    The investigation of orientation dependent crystal growth and etch processes can provide deep insights into the underlying mechanisms and thus helps to validate theoretical models. Here, we report on homoepitaxial diamond growth and oxygen etch experiments on polished, polycrystalline CVD diamond wafers by use of electron backscatter diffraction (EBSD) and white-light interferometry (WLI). Atomic force microscopy (AFM) was applied to provide additional atomic scale surface morphology information. The main advantage of using polycrystalline diamond substrates with almost random grain orientation is that it allows determining the orientation dependent growth (etch) rate for different orientations within one experiment. Specifically, we studied the effect of methane concentration on the diamond growth rate, using a microwave plasma CVD process. At 1 % methane concentration a maximum of the growth rate near <100> and a minimum near <111> is detected. Increasing the methane concentration up to 5 % shifts the maximum towards <110> while the minimum stays at <111>. Etch rate measurements in a microwave powered oxygen plasma reveal a pronounced maximum at <111>. We also made a first attempt to interpret our experimental data in terms of local micro-faceting of high-indexed planes.

  16. Small Variance in Growth Rate in Annual Plants has Large Effects on Genetic Drift

    Technology Transfer Automated Retrieval System (TEKTRAN)

    When plant size is strongly correlated with plant reproduction, variance in growth rates results in a lognormal distribution of seed production within a population. Fecundity variance affects effective population size (Ne), which reflects the ability of a population to maintain beneficial mutations ...

  17. Analysing the lag-growth rate relationship of Yersinia enterocolitica.

    PubMed

    Pin, Carmen; García, de Fernando Gonzalo D; Ordóñez, Juan A; Baranyi, József

    2002-03-01

    A generalised z-value concept has been applied to analyse the relationship between the lag and the growth rate of Yersinia enterocolitica at a range of temperature, atmospheric carbon dioxide and oxygen percentages. The product of the specific growth rate and the lag (the "work to be done" during the lag phase) is found to be independent of temperature. However, it does depend on the CO2 and O2 concentrations, though the effect of oxygen was less noticeable than the effect of carbon dioxide.

  18. Orbit width scaling of TAE instability growth rate

    SciTech Connect

    Wong, H.V.; Berk, H.L.; Breizman, B.N.

    1995-07-01

    The growth rate of Toroidal Alfven Eigenmodes (TAE) driven unstable by resonant coupling of energetic charged particles is evaluated in the ballooning limit over a wide range of parameters. All damping effects are ignored. Variations in orbit width, aspect ratio, and the ratio of alfven velocity to energetic particle birth velocity, are explored. The relative contribution of passing and trapped particles, and finite Larmor radius effects, are also examined. The phase space location of resonant particles with interact strongly with the modes is described. The accuracy of the analytic results with respect to growth rate magnitude and parametric dependence is investigated by comparison with numerical results.

  19. The growth rate of gas hydrate from refrigerant R12

    SciTech Connect

    Kendoush, Abdullah Abbas; Jassim, Najim Abid; Joudi, Khalid A.

    2006-07-15

    Experimental and theoretical investigations were presented dealing with three phase direct-contact heat transfer by evaporation of refrigerant drops in an immiscible liquid. Refrigerant R12 was used as the dispersed phase, while water and brine were the immiscible continuous phase. A numerical solution is presented to predict the formation rate of gas hydrates in test column. The solution provided an acceptable agreement when compared with experimental results. The gas hydrate growth rate increased with time. It increased with increasing dispersed phase flow rate. The presence of surface-active sodium chloride in water had a strong inhibiting effect on the gas hydrate formation rate. (author)

  20. Calcium pectate chemistry controls growth rate of Chara corallina.

    PubMed

    Proseus, Timothy E; Boyer, John S

    2006-01-01

    Pectin, a normal constituent of cell walls, caused growth rates to accelerate to the rates in living cells when supplied externally to isolated cell walls of Chara corallina. Because this activity was not reported previously, the activity was investigated. Turgor pressure (P) was maintained in isolated walls or living cells using a pressure probe in culture medium. Pectin from various sources was supplied to the medium. Ca and Mg were the dominant inorganic elements in the wall. EGTA or pectin in the culture medium extracted moderate amounts of wall Ca and essentially all the wall Mg, and wall growth accelerated. Removing the external EGTA or pectin and replacing with fresh medium returned growth to the original rate. A high concentration of Ca2+ quenched the accelerating activity of EGTA or pectin and caused gelling of the pectin, physically inhibiting wall growth. Low pH had little effect. After the Mg had been removed, Ca-pectate in the wall bore the longitudinal load imposed by P. Removal of this Ca caused the wall to burst. Live cells and isolated walls reacted similarly. It was concluded that Ca cross-links between neighbouring pectin molecules were strong wall bonds that controlled wall growth rates. The central role of Ca-pectate chemistry was illustrated by removing Ca cross-links with new pectin (wall "loosening"), replacing vacated cross-links with new Ca2+ ("Ca2+-tightening"), or adding new cross-links with new Ca-pectate that gelled ("gel tightening"). These findings establish a molecular model for growth that includes wall deposition and assembly for sustained growth activity.

  1. 3D fold growth rates in transpressional tectonic settings

    NASA Astrophysics Data System (ADS)

    Frehner, Marcel

    2015-04-01

    Geological folds are inherently three-dimensional (3D) structures; hence, they also grow in 3D. In this study, fold growth in all three dimensions is quantified numerically using a finite-element algorithm for simulating deformation of Newtonian media in 3D. The presented study is an extension and generalization of the work presented in Frehner (2014), which only considered unidirectional layer-parallel compression. In contrast, the full range from strike slip settings (i.e., simple shear) to unidirectional layer-parallel compression is considered here by varying the convergence angle of the boundary conditions; hence the results are applicable to general transpressional tectonic settings. Only upright symmetrical single-layer fold structures are considered. The horizontal higher-viscous layer exhibits an initial point-like perturbation. Due to the mixed pure- and simple shear boundary conditions a mechanical buckling instability grows from this perturbation in all three dimensions, described by: Fold amplification (vertical growth): Fold amplification describes the growth from a fold shape with low limb-dip angle to a shape with higher limb-dip angle. Fold elongation (growth parallel to fold axis): Fold elongation describes the growth from a dome-shaped (3D) structure to a more cylindrical fold (2D). Sequential fold growth (growth perpendicular to fold axial plane): Sequential fold growth describes the growth of secondary (and further) folds adjacent to the initial isolated fold. The term 'lateral fold growth' is used as an umbrella term for both fold elongation and sequential fold growth. In addition, the orientation of the fold axis is tracked as a function of the convergence angle. Even though the absolute values of all three growth rates are markedly reduced with increasing simple-shear component at the boundaries, the general pattern of the quantified fold growth under the studied general-shear boundary conditions is surprisingly similar to the end

  2. SCC crack growth rate of cold worked 316L stainless steel in PWR environment

    NASA Astrophysics Data System (ADS)

    Du, Donghai; Chen, Kai; Yu, Lun; lu, Hui; Zhang, Lefu; Shi, Xiuqiang; Xu, Xuelian

    2015-01-01

    Many component failures in nuclear power plants were found to be caused by stress corrosion cracking (SCC) of cold worked austenitic steels. Some of the pressure boundary component materials are even cold worked up to 35% plastic deformation, leaving high residual stress and inducing high growth rate of corrosion crack. Controlling water chemistry is one of the best counter measure to mitigate this problem. In this work, the effects of temperature (200 up to 325 °C) and dissolved oxygen (0 up to 2000 μg/L) on SCC crack growth rates of cold worked austenitic stainless steel type 316L have been tested by using direct current potential drop (DCPD) method. The results showed that temperature affected SCC crack growth rates more significantly in oxygenated water than in deaerated water. In argon deaerated water, the crack growth rate exhibited a peak at about 250 °C, which needs further verification. At 325 °C, the SCC crack growth rate increased rapidly with the increase of dissolved oxygen concentration within the range from 0 up to 200 μg/L, while when dissolved oxygen was above 200 μg/L, the crack growth rate followed a shallower dependence on dissolved oxygen concentration.

  3. Islamic Republic of Iran population growth rate declines.

    PubMed

    1996-01-01

    In April 1996, at the 52nd Session of the UN Economic and Social Commission for Asia and the Pacific (ESCAP), the delegate from the Islamic Republic of Iran announced that social indicators indicate acceptable improvement. The average population growth rate fell from 3.9% (1981-1991) to less than 2% (1995). High birth rates and an influx of refugees during 1981-1991 accounted for the high population growth rate. The marked decline in the birth rate, brought about mainly by effective family planning and health programs, has contributed greatly to the reduced population growth rate. The government has focused on rural areas. 86% of rural households now have access to piped water. More than 60% have electricity. The overall literacy rate in Iran has reached 79%. The entire population has access to free or subsidized primary health care services. The Second Development Plan of Iran centers on the significance of the role that mothers have in shaping society and individuals by their child raising abilities, particularly in the early years. The Iranian delegate endorsed the secretariat's plan for helping members and associate members to reach their development goals and objectives.

  4. Root pressurization affects growth-induced water potentials and growth in dehydrated maize leaves.

    PubMed

    Tang, An-Ching; Boyer, John S

    2003-11-01

    Profiles of water potential (Psi w) were measured from the soil to the tips of growing leaves of maize (Zea mays L.) when pressure (P) was applied to the soil/root system. At moderately low soil Psi w, leaf elongation was somewhat inhibited, large tensions existed in the xylem, and Psi w were slightly lower in the elongating leaf tissues than in the xylem, i.e. a growth-induced Psi w was present but small. With P, the tension was relieved, enlarging the difference in Psi w between the xylem and the elongating tissues, i.e. enlarging the growth-induced Psi w, which is critical for growth. Guttation occurred, confirming the high Psi w of the xylem, and the mature leaf tissue rehydrated. Water uptake increased and met the requirements of transpiration. Leaf elongation recovered to control rates. Under more severe conditions at lower soil Psi w, P induced only a brief elongation and the growth-induced Psi w responded only slightly. Guttation did not occur, water flow did not meet the requirements of transpiration, and the mature leaf tissues did not rehydrate. A rewatering experiment indicated that a low conductance existed in the severely dehydrated soil, which limited water delivery to the root and shoot. Therefore, the initial growth inhibition appeared to be hydraulic because the enlargement of the growth-induced Psi w by P together with rehydration of the mature leaf tissue were essential for growth recovery. In more severe conditions, P was ineffective because the soil could not supply water at the required rate, and metabolic factors began to contribute to the inhibition. PMID:14512379

  5. Does growth rate determine the rate of metabolism in shorebird chicks living in the Arctic?

    PubMed

    Williams, Joseph B; Tieleman, B Irene; Visser, G Henk; Ricklefs, Robert E

    2007-01-01

    We measured resting and peak metabolic rates (RMR and PMR, respectively) during development of chicks of seven species of shorebirds: least sandpiper (Calidris minutilla; adult mass 20-22 g), dunlin (Calidris alpina; 56-62 g), lesser yellowlegs (Tringa flavipes; 88-92 g), short-billed dowitcher (Limnodromus griseus; 85-112 g), lesser golden plover (Pluvialis dominicana; 150-156 g), Hudsonian godwit (Limosa haemastica; 205-274 g), and whimbrel (Numenius phaeopus; 380 g). We tested two opposing hypotheses: the growth rate-maturity hypothesis, which posits that growth rate in chicks is inversely related to functional maturity of tissues, and the fast growth rate-high metabolism hypothesis, which suggests that rapid growth is possible only with a concomitant increase in either RMR or PMR. We have found no evidence that chicks of shorebirds with fast growth rates have lower RMRs or lower PMRs, as would be predicted by the growth rate-maturity hypothesis, but our data suggested that faster-growing chest muscles resulted in increased thermogenic capacity, consistent with the fast growth-high metabolism hypothesis. The development of homeothermy in smaller species is a consequence primarily of greater metabolic intensities of heat-generating tissues. The maximum temperature gradient between a chick's body and environment that can be maintained in the absence of a net radiative load increased rapidly with body mass during development and was highest in least sandpipers and lowest among godwits. Chicks of smaller species could maintain a greater temperature gradient at a particular body mass because of their higher mass-specific maximum metabolic rates.

  6. Delays and Growth Rates of Multiple TEOAE Components

    NASA Astrophysics Data System (ADS)

    Goodman, Shawn S.; Mertes, Ian B.; Scheperle, Rachel A.

    2011-11-01

    Bandpass-filtered transient-evoked otoacoustic emissions (TEOAEs) show multiple energy peaks with time delays that are invariant with level and growth rates that vary with delay and stimulus level, suggesting that multiple generation mechanisms may be involved at moderate and high stimulus levels. We measured delays and magnitude growths of multiple TEOAE energy peaks and compared the results obtained from linear and nonlinear extraction methods. To test the hypothesis that early components are generated at the basal portion of the cochlea, delays and growth rates were also measured in the presence of highpass masking noise for a subset of subjects. No effect of the highpass masking was seen. The results are discussed in terms of potential generation mechanisms of the multiple energy peaks.

  7. Linear Stability of Binary Alloy Solidification for Unsteady Growth Rates

    NASA Technical Reports Server (NTRS)

    Mazuruk, K.; Volz, M. P.

    2010-01-01

    An extension of the Mullins and Sekerka (MS) linear stability analysis to the unsteady growth rate case is considered for dilute binary alloys. In particular, the stability of the planar interface during the initial solidification transient is studied in detail numerically. The rapid solidification case, when the system is traversing through the unstable region defined by the MS criterion, has also been treated. It has been observed that the onset of instability is quite accurately defined by the "quasi-stationary MS criterion", when the growth rate and other process parameters are taken as constants at a particular time of the growth process. A singular behavior of the governing equations for the perturbed quantities at the constitutional supercooling demarcation line has been observed. However, when the solidification process, during its transient, crosses this demarcation line, a planar interface is stable according to the linear analysis performed.

  8. Slow growth rates of Amazonian trees: consequences for carbon cycling.

    PubMed

    Vieira, Simone; Trumbore, Susan; Camargo, Plinio B; Selhorst, Diogo; Chambers, Jeffrey Q; Higuchi, Niro; Martinelli, Luiz Antonio

    2005-12-20

    Quantifying age structure and tree growth rate of Amazonian forests is essential for understanding their role in the carbon cycle. Here, we use radiocarbon dating and direct measurement of diameter increment to document unexpectedly slow growth rates for trees from three locations spanning the Brazilian Amazon basin. Central Amazon trees, averaging only approximately 1 mm/year diameter increment, grow half as fast as those from areas with more seasonal rainfall to the east and west. Slow growth rates mean that trees can attain great ages; across our sites we estimate 17-50% of trees with diameter >10 cm have ages exceeding 300 years. Whereas a few emergent trees that make up a large portion of the biomass grow faster, small trees that are more abundant grow slowly and attain ages of hundreds of years. The mean age of carbon in living trees (60-110 years) is within the range of or slightly longer than the mean residence time calculated from C inventory divided by annual C allocation to wood growth (40-100 years). Faster C turnover is observed in stands with overall higher rates of diameter increment and a larger fraction of the biomass in large, fast-growing trees. As a consequence, forests can recover biomass relatively quickly after disturbance, whereas recovering species composition may take many centuries. Carbon cycle models that apply a single turnover time for carbon in forest biomass do not account for variations in life strategy and therefore may overestimate the carbon sequestration potential of Amazon forests.

  9. Measuring the growth rate of structure around cosmic voids

    NASA Astrophysics Data System (ADS)

    Hawken, A. J.; Michelett, D.; Granett, B.; Iovino, A.; Guzzo, L.

    2016-10-01

    Using an algorithm based on searching for empty spheres we identified 245 voids in the VIMOS Public Extragalactic Redshift Survey (VIPERS). We show how by modelling the anisotropic void-galaxy cross correlation function we can probe the growth rate of structure.

  10. Inhibition of rate of tumor growth by creatine and cyclocreatine.

    PubMed Central

    Miller, E E; Evans, A E; Cohn, M

    1993-01-01

    Growth rate inhibition of subcutaneously implanted tumors results from feeding rats and athymic nude mice diets containing 1% cyclocreatine or 1%, 2%, 5%, or 10% creatine. The tumors studied included rat mammary tumors (Ac33tc in Lewis female rats and 13762A in Fischer 344 female rats), rat sarcoma MCI in Lewis male rats, and tumors resulting from the injection of two human neuroblastoma cell lines, IMR-5 and CHP-134, in athymic nude mice. Inhibition was observed regardless of the time experimental diets were administered, either at the time of tumor implantation or after the appearance of palpable tumors. For mammary tumor Ac33tc, the growth inhibition during 24 days after the implantation was approximately 50% for both 1% cyclocreatine and 1% creatine, and inhibition increased as creatine was increased from 2% to 10% of the diet. For the other rat mammary tumor (13762A), there was approximately 35% inhibition by both 1% cyclocreatine and 2% creatine. In the case of the MCI sarcoma, the inhibitory effect appeared more pronounced at earlier periods of growth, ranging from 26% to 41% for 1% cyclocreatine and from 30% to 53% for 1% creatine; there was no significant difference in growth rate between the tumors in the rats fed 1% and 5% creatine. The growth rate of tumors in athymic nude mice, produced by implantation of the human neuroblastoma IMR-5 cell line, appeared somewhat more effectively inhibited by 1% cyclocreatine than by 1% creatine, and 5% creatine feeding was most effective. For the CHP-134 cell line, 33% inhibition was observed for the 1% cyclocreatine diet and 71% for the 5% creatine diet. In several experiments, a delay in appearance of tumors was observed in animals on the experimental diets. In occasional experiments, neither additive inhibited tumor growth rate for the rat tumors or the athymic mouse tumors. Images Fig. 3 PMID:8475072

  11. Prediction of Growth Rate at Different Light Levels from Measured Photosynthesis and Respiration Rates

    PubMed Central

    McCree, K. J.; Troughton, J. H.

    1966-01-01

    Light integrators with a linear response are not suitable for measuring the light climates of plants because plants are not linear integrators. It should be possible to make a quantitative allowance for this nonlinearity by using the CO2 uptake curve of the plant. To test this, we have subjected white clover plants to different levels of constant light, comparing the rate of increase of total dry matter with the net rate of uptake of CO2 per day. Temperature, humidity, daylength and nutrient supply were kept constant. The growth rate calculated from CO2 uptake agreed well with the observed rate over the light levels tested (3.7-88 w·m−2, 0.4-0.7 micron: 1 w·m−2 = 103 erg · sec−1 cm−2). All plants put on weight over the few days of the experiment, even those placed at light levels below their compensation point. The plants adapted their respiration rates to be a constant proportion of their growth rates. Most of the adaptation occurred within 24 hours of the light change. The adaptation of respiration has implications for models of light/growth relations in plant communities, almost all of which assume that respiration is proportional to leaf area and independent of growth rate or light level. The only model which does not is that of de Wit, and this gave good agreement with our results. PMID:16656288

  12. Determination of kinetic parameters of crystal growth rate of borax in aqueous solution by using the rotating disc technique

    NASA Astrophysics Data System (ADS)

    Sahin, Omer; Aslan, Fevzi; Ozdemir, Mustafa; Durgun, Mustafa

    2004-10-01

    Growth rate of polycrystalline disc of borax compressed at different pressure and rotated at various speed has been measured in a rotating disc crystallizer under well-defined conditions of supersaturation. It was found that the mass transfer coefficient, K, increased while overall growth rate constant, Kg, and surface reaction constant, kr, decreased with increasing smoothness of the disc. It was also determined that kinetic parameters (kr , r , K , g) of crystal growth rate of borax decreased with increasing rotating speed of the polycrystalline disc. The effectiveness factor was calculated from the growth rate data to evaluate the relative magnitude of the steps in series bulk diffusion through the mass transfer boundary layer and the surface integration. At low rotating speed of disc, the crystal growth rate of borax is mainly controlled by integration. However, both diffusion and integration steps affect the growth rate of borax at higher rotating speed of polycrystalline disc.

  13. Relating Productivity Events to Holocene Bivalve Shell Growth Rates

    NASA Astrophysics Data System (ADS)

    Huntley, J. W.; Krause, R. A.; Kowalewski, M.; Romanek, C. S.; Kaufman, D. S.; Simoes, M. G.

    2007-12-01

    The growth rate of a bivalve can be influenced by many environmental factors that can change during the life of the organism. In this contribution we present initial data from a millennium scale chronology to assess the relationship between ontogenetic growth in the bivalve Semele casali and paleoenvironmental conditions preserved in the shell using growth increment analysis, radiocarbon-calibrated amino acid racemization dating techniques, stable isotopes (C and O) and high spatial resolution (125-150 samples per cm of shell profile) trace element (Ba, Mn) analysis (LA-ICPMS). Time-averaged specimens of S. casali were dredged from two sites at 10 meters and 30 meters depth along the inner continental shelf at Ubatuba Bay in the Southeast Brazilian Bight, an area influenced by productivity pulses triggered by coastal runoff events and coastal upwelling. Seventy-five individual valves were dated using amino acid racemization (aspartic acid). Dates were calculated using an expanded version of a previously published relationship (Barbour Wood et al., 2006 Quaternary Research 323- 331) between aspartic acid ratios and AMS radiocarbon dates of twelve S. casali individuals from the same sampling locations. The resulting time series has complete coverage for the past three thousand years at centennial resolution. From this time series, a sub-sample of dated valves was selected for more detailed growth increment, stable isotope and high-resolution trace element (Ba/Ca and Mn/Ca) analyses. Oceanic productivity is expressed differentially in the trace element profiles of S. casali with elevated Ba/Ca and Mn/Ca ratios capturing nutrient input through coastal runoff events while elevated Ba/Ca and depressed Mn/Ca ratios represent input through coastal upwelling. Fluctuations in Ba/Ca and Mn/Ca are not correlated to fluctuations in relative growth throughout the ontogeny of an individual bivalve, nor are they expected to be as periods of increased productivity are transient

  14. Scaling laws in the dynamics of crime growth rate

    NASA Astrophysics Data System (ADS)

    Alves, Luiz G. A.; Ribeiro, Haroldo V.; Mendes, Renio S.

    2013-06-01

    The increasing number of crimes in areas with large concentrations of people have made cities one of the main sources of violence. Understanding characteristics of how crime rate expands and its relations with the cities size goes beyond an academic question, being a central issue for contemporary society. Here, we characterize and analyze quantitative aspects of murders in the period from 1980 to 2009 in Brazilian cities. We find that the distribution of the annual, biannual and triannual logarithmic homicide growth rates exhibit the same functional form for distinct scales, that is, a scale invariant behavior. We also identify asymptotic power-law decay relations between the standard deviations of these three growth rates and the initial size. Further, we discuss similarities with complex organizations.

  15. Ant Larval Demand Reduces Aphid Colony Growth Rates in an Ant-Aphid Interactio

    PubMed Central

    Oliver, Tom H.; Leather, Simon R.; Cook, James M.

    2012-01-01

    Ants often form mutualistic interactions with aphids, soliciting honeydew in return for protective services. Under certain circumstances, however, ants will prey upon aphids. In addition, in the presence of ants aphids may increase the quantity or quality of honeydew produced, which is costly. Through these mechanisms, ant attendance can reduce aphid colony growth rates. However, it is unknown whether demand from within the ant colony can affect the ant-aphid interaction. In a factorial experiment, we tested whether the presence of larvae in Lasius niger ant colonies affected the growth rate of Aphis fabae colonies. Other explanatory variables tested were the origin of ant colonies (two separate colonies were used) and previous diet (sugar only or sugar and protein). We found that the presence of larvae in the ant colony significantly reduced the growth rate of aphid colonies. Previous diet and colony origin did not affect aphid colony growth rates. Our results suggest that ant colonies balance the flow of two separate resources from aphid colonies- renewable sugars or a protein-rich meal, depending on demand from ant larvae within the nest. Aphid payoffs from the ant-aphid interaction may change on a seasonal basis, as the demand from larvae within the ant colony waxes and wanes. PMID:26467951

  16. Proximate causes of adaptive growth rates: growth efficiency variation among latitudinal populations of Rana temporaria.

    PubMed

    Lindgren, B; Laurila, A

    2005-07-01

    In ectothermic organisms, declining season length and lower temperature towards higher latitudes often select for latitudinal variation in growth and development. However, the energetic mechanisms underlying this adaptive variation are largely unknown. We investigated growth, food intake and growth efficiency of Rana temporaria tadpoles from eight populations along a 1500 km latitudinal gradient across Sweden. To gain an insight into the mechanisms of adaptation at organ level, we also examined variation in tadpole gut length. The tadpoles were raised at two temperatures (16 and 20 degrees C) in a laboratory common garden experiment. We found increased growth rate towards higher latitudes, regardless of temperature treatment. This increase in growth was not because of a higher food intake rate, but populations from higher latitudes had higher growth efficiency, i.e. they were more efficient at converting ingested food into body mass. Low temperature reduced growth efficiency most strongly in southern populations. Relative gut length increased with latitude, and tadpoles at low temperature tended to have longer guts. However, variation in gut length was not the sole adaptive explanation for increased growth efficiency as latitude and body length still explained significant amounts of variation in growth efficiency. Hence, additional energetic adaptations are probably involved in growth efficiency variation along the latitudinal gradient.

  17. Pedalling rate affects endurance performance during high-intensity cycling.

    PubMed

    Nielsen, Jens Steen; Hansen, Ernst Albin; Sjøgaard, Gisela

    2004-06-01

    The purpose of this study into high-intensity cycling was to: (1) test the hypothesis that endurance time is longest at a freely chosen pedalling rate (FCPR), compared to pedalling rates 25% lower (FCPR-25) and higher (FCPR+25) than FCPR, and (2) investigate how physiological variables, such as muscle fibre type composition and power reserve, relate to endurance time. Twenty males underwent testing to determine their maximal oxygen uptake (VO(2max)), power output corresponding to 90% of VO(2max) at 80 rpm (W90), FCPR at W90, percentage of slow twitch muscle fibres (% MHC I), maximal leg power, and endurance time at W90 with FCPR-25, FCPR, and FCPR+25. Power reserve was calculated as the difference between applied power output at a given pedalling rate and peak crank power at this same pedalling rate. W90 was 325 (47) W. FCPR at W90 was 78 (11) rpm, resulting in FCPR-25 being 59 (8) rpm and FCPR+25 being 98 (13) rpm. Endurance time at W90(FCPR+25) [441 (188) s] was significantly shorter than at W90(FCPR) [589 (232) s] and W90(FCPR-25) [547 (170) s]. Metabolic responses such as VO(2) and blood lactate concentration were generally higher at W90(FCPR+25) than at W90(FCPR-25) and W90(FCPR). Endurance time was negatively related to VO(2max), W90 and % MHC I, while positively related to power reserve. In conclusion, at group level, endurance time was longer at FCPR and at a pedalling rate 25% lower compared to a pedalling rate 25% higher than FCPR. Further, inter-individual physiological variables were of significance for endurance time, % MHC I showing a negative and power reserve a positive relationship.

  18. Does Vessel Noise Affect Oyster Toadfish Calling Rates?

    PubMed

    Luczkovich, Joseph J; Krahforst, Cecilia S; Hoppe, Harry; Sprague, Mark W

    2016-01-01

    The question we addressed in this study is whether oyster toadfish respond to vessel disturbances by calling less when vessels with lower frequency spectra are present in a sound recording and afterward. Long-term data recorders were deployed at the Neuse (high vessel-noise site) and Pamlico (low vessel-noise site) Rivers. There were many fewer toadfish detections at the high vessel-noise site than the low-noise station. Calling rates were lower in the high-boat traffic area, suggesting that toadfish cannot call over loud vessel noise, reducing the overall calling rate, and may have to call more often when vessels are not present. PMID:26611015

  19. Density, ages, and growth rates in old-growth and young-growth forests in coastal Oregon

    USGS Publications Warehouse

    Tappeiner, J. C.; Huffman, D.; Spies, T.; Bailey, John D.

    1997-01-01

    We studied the ages and diameter growth rates of trees in former Douglas-fir (Pseudotsuga menziesii (Mirb.)Franco) old-growth stands on 10 sites and compared them with young-growth stands (50-70 years old, regenerated after timber harvest) in the Coast Range of western Oregon. The diameters and diameter growth rates for the first 100 years of trees in the old-growth stands were significantly greater than those in the young-growth stands. Growth rates in the old stands were comparable with those from long-term studies of young stands in which density is about 100-120 trees/ha; often young-growth stand density is well over 500 trees/ha. Ages of large trees in the old stands ranged from 100 to 420 years; ages in young stands varied by only about 5 to 10 years. Apparently, regeneration of old-growth stands on these sites occurred over a prolonged period, and trees grew at low density with little self-thinning; in contrast, after timber harvest, young stands may develop with high density of trees with similar ages and considerable self-thinning. The results suggest that thinning may be needed in dense young stands where the management objective is to speed development of old-growth characteristics.

  20. Do Graduate Student Teacher Training Courses Affect Placement Rates?

    ERIC Educational Resources Information Center

    Ishiyama, John; Balarezo, Christine; Miles, Tom

    2014-01-01

    We investigate whether the existence of a required graduate course on "Teaching in Political Science" is related to overall job placement rates reported by graduate political science programs. We examine this in light of evidence from 73 public PhD-granting political science departments across the country. We find that the existence of…

  1. Factors affecting heart rate variability in preterm infants.

    PubMed

    Cabal, L A; Siassi, B; Zanini, B; Hodgman, J E; Hon, E E

    1980-01-01

    Neonatal heart rate variability (NHRV) was studied in 92 preterm infants (birth weight, 750 to 2,500 gm; gestational age, 28 to 36 weeks). Each infant was monitored continuously during the first 6 hours and for one hour at 24, 48, and 168 hours of life. During each hour NHRV was quantified and related to the following parameters: sex, gestational age, postnatal age, heart rate, and the presence and severity of respiratory distress syndrome (RDS). NHRV in healthy preterm infants was inversely related to heart rate level and directly related to the infant's postnatal age. In healthy babies with gestations of 30 to 36 weeks there was no significant correlation between NHRV and gestation. Decrease in NHRV was significantly related to the severity of RDS, and the reappearance of NHRV in infants with RDS was associated with a good prognosis. Decreased NHRV significantly differentiated the infants with RDS who survived after the fifth hour of life. The data reveal that NHRV (1) should be corrected for heart rate level and postnatal age; (2) is decreased in RDS; and (3) can be used as an indicator of morbidity and mortality in preterm infants with RDS.

  2. Rhizobacterial volatiles affect the growth of fungi and Arabidopsis thaliana.

    PubMed

    Vespermann, Anja; Kai, Marco; Piechulla, Birgit

    2007-09-01

    Volatiles of Stenotrophomonas, Serratia, and Bacillus species inhibited mycelial growth of many fungi and Arabidopsis thaliana (40 to 98%), and volatiles of Pseudomonas species and Burkholderia cepacia retarded the growth to lesser extents. Aspergillus niger and Fusarium species were resistant, and B. cepacia and Staphylococcus epidermidis promoted the growth of Rhizoctonia solani and A. thaliana. Bacterial volatiles provide a new source of compounds with antibiotic and growth-promoting features.

  3. Direct Observation of Aggregative Nanoparticle Growth: Kinetic Modeling of the Size Distribution and Growth Rate

    SciTech Connect

    Woehl, Taylor J.; Park, Chiwoo; Evans, James E.; Arslan, Ilke; Ristenpart, William D.; Browning, Nigel D.

    2014-01-08

    Direct observations of solution-phase nanoparticle growth using in situ liquid transmission electron microscopy (TEM) have demonstrated the importance of “non-classical” growth mechanisms, such as aggregation and coalescence, on the growth and final morphology of nanocrystals at the atomic and single nanoparticle scales. To date, groups have quantitatively interpreted the mean growth rate of nanoparticles in terms of the Lifshitz-Slyozov-Wagner (LSW) model for Ostwald ripening, but less attention has been paid to modeling the corresponding particle size distribution. Here we use in situ fluid stage scanning TEM to demonstrate that silver nanoparticles grow by a length-scale dependent mechanism, where individual nanoparticles grow by monomer attachment but ensemble-scale growth is dominated by aggregation. Although our observed mean nanoparticle growth rate is consistent with the LSW model, we show that the corresponding particle size distribution is broader and more symmetric than predicted by LSW. Following direct observations of aggregation, we interpret the ensemble-scale growth using Smoluchowski kinetics and demonstrate that the Smoluchowski model quantitatively captures the mean growth rate and particle size distribution.

  4. The effect of growth rate, diameter and impurity concentration on structure in Czochralski silicon crystal growth

    NASA Technical Reports Server (NTRS)

    Digges, T. G., Jr.; Shima, R.

    1980-01-01

    It is demonstrated that maximum growth rates of up to 80% of the theoretical limit can be attained in Czochralski-grown silicon crystals while maintaining single crystal structure. Attaining the other 20% increase is dependent on design changes in the grower, to reduce the temperature gradient in the liquid while increasing the gradient in the solid. The conclusions of Hopkins et al. (1977) on the effect of diameter on the breakdown of structure at fast growth rates are substantiated. Copper was utilized as the test impurity. At large diameters (greater than 7.5 cm), concentrations of greater than 1 ppm copper were attained in the solid (45,000 ppm in the liquid) without breakdown at maximum growth speeds. For smaller diameter crystals, the sensitivity of impurities is much more apparent. For solar cell applications, impurities will limit cell performance before they cause crystal breakdown for fast growth rates of large diameter crystals.

  5. A study of the growth rates and growth habits of ice crystals in a solution of antifreeze (glyco) proteins

    NASA Astrophysics Data System (ADS)

    Li, Qianzhong; Luo, Liaofu

    1996-12-01

    The mechanism of the antifreeze glycoprotein/antifreeze protein interaction on the surface of ice is analyzed. The theory of ice crystal growth in an AF(G)P solution is presented. A quantitative calculation of the growth rates for gain growth has been obtained. The anisotropic growth habits and growth rates of ice crystals in an AF(G)P solution are explained.

  6. Improvements in plant growth rate using underwater discharge

    NASA Astrophysics Data System (ADS)

    Takaki, K.; Takahata, J.; Watanabe, S.; Satta, N.; Yamada, O.; Fujio, T.; Sasaki, Y.

    2013-03-01

    The drainage water from plant pots was irradiated by plasma and then recycled to irrigate plants for improving the growth rate by supplying nutrients to plants and inactivating the bacteria in the bed-soil. Brassica rapa var. perviridis (Chinese cabbage; Brassica campestris) plants were cultivated in pots filled with artificial soil, which included the use of chicken droppings as a fertiliser. The water was recycled once per day from a drainage water pool and added to the bed-soil in the pots. A magnetic compression type pulsed power generator was used to produce underwater discharge with repetition rate of 250 pps. The plasma irradiation times were set as 10 and 20 minutes per day over 28 days of cultivation. The experimental results showed that the growth rate increased significantly with plasma irradiation into the drainage water. The growth rate increased with the plasma irradiation time. The nitrogen concentration of the leaves increased as a result of plasma irradiation based on chlorophyll content analysis. The bacteria in the drainage water were inactivated by the plasma irradiation.

  7. Spherulitic nucleation and growth rates in a sheared polypropylene melt

    NASA Astrophysics Data System (ADS)

    De Santis, F.; Scermino, R.; Pantani, R.; Titomanlio, G.

    2014-05-01

    In common polymer processing operations such as injection molding, film blowing, and fiber spinning, the molten polymer is subjected to intense shear and/or elongational flow fields and crystallizes during or after the application of flow. The semicrystalline morphology that develops in the final product is typically very different from what is observed during quiescent crystallization of the same polymer, and the properties change accordingly. The possibility of controlling the final morphology and the resulting mechanical and functional properties of semicrystalline polymers based on the study of polymer melt crystallization stimulated by flow is highly intriguing. This work starts from the experimental evidence that there exists qualitatively three regimes of crystallization under shear: (a) very low shear rates, in which there is no effect on kinetics; (b) higher shear rates, in which orientational effects enhance just the nucleation and growth rates, and spherulitic crystallization is observed; and (c) high shear rates, in which molecular stretching occurs giving rise to a fibrillar morphology development under very fast kinetics. The first two regimes are explored and analyzed by means of experimental protocols developed on purpose. In particular: - spherulitic nucleation and growth rates under continuous shear rates were carefully measured and related to molecular strain - the condition below which crystallization turns out to be essentially quiescent was evidenced.

  8. Alteration of proteoglycan sulfation affects bone growth and remodeling

    PubMed Central

    Gualeni, Benedetta; de Vernejoul, Marie-Christine; Marty-Morieux, Caroline; De Leonardis, Fabio; Franchi, Marco; Monti, Luca; Forlino, Antonella; Houillier, Pascal; Rossi, Antonio; Geoffroy, Valerie

    2013-01-01

    Diastrophic dysplasia (DTD) is a chondrodysplasia caused by mutations in the SLC26A2 gene, leading to reduced intracellular sulfate pool in chondrocytes, osteoblasts and fibroblasts. Hence, proteoglycans are undersulfated in the cartilage and bone of DTD patients. To characterize the bone phenotype of this skeletal dysplasia we used the Slc26a2 knock-in mouse (dtd mouse), that was previously validated as an animal model of DTD in humans. X-rays, bone densitometry, static and dynamic histomorphometry, and in vitro studies revealed a primary bone defect in the dtd mouse model. We showed in vivo that this primary bone defect in dtd mice is due to decreased bone accrual associated with a decreased trabecular and periosteal appositional rate at the cell level in one month-old mice. Although the osteoclast number evaluated by histomorphometry was not different in dtd compared to wild-type mice, urine analysis of deoxypyridinoline cross-links and serum levels of type I collagen C-terminal telopeptides showed a higher resorption rate in dtd mice compared to wild-type littermates. Electron microscopy studies showed that collagen fibrils in bone were thinner and less organized in dtd compared to wild-type mice. These data suggest that the low bone mass observed in mutant mice could possibly be linked to the different bone matrix compositions/organizations in dtd mice triggering changes in osteoblast and osteoclast activities. Overall, these results suggest that proteoglycan undersulfation not only affects the properties of hyaline cartilage, but can also lead to unbalanced bone modeling and remodeling activities, demonstrating the importance of proteoglycan sulfation in bone homeostasis. PMID:23369989

  9. Growth Rate Analysis of an Untreated Glomus Vagale on MRI

    PubMed Central

    Wang, Jeffrey Tzu-Yu; Wang, Allen Yu-Yu; Cheng, Sheila; Gomes, Lavier; Da Cruz, Melville

    2016-01-01

    Paragangliomas are slow growing, hypervascular neuroendocrine tumors that develop in the extra-adrenal paraganglion tissues. Paraganglioma involving the vagus nerve ganglia is termed glomus vagale. The slow growth of head and neck paragangliomas especially in the absence of symptom may obviate the necessity for any active intervention, in which case, a “wait and scan” policy is implemented involving long-term clinical and radiologic follow-ups. We present a case of a 71-year-old female with an untreated left glomus vagale who underwent a conservative “wait and rescan” plan of management and the tumor was observed with 8 serial MRI scans over a period of 7.4 years. A growth rate analysis was conducted which demonstrated a slow growth. A literature review of radiologic studies examining the natural history of head and neck paragangliomas was also performed. PMID:27073708

  10. Context-specific influence of water temperature on brook trout growth rates in the field

    USGS Publications Warehouse

    Xu, C.; Letcher, B.H.; Nislow, K.H.

    2010-01-01

    1. Modelling the effects of climate change on freshwater fishes requires robust field-based estimates accounting for interactions among multiple factors.2. We used data from an 8-year individual-based study of a wild brook trout (Salvelinus fontinalis) population to test the influence of water temperature on season-specific growth in the context of variation in other environmental (i.e. season, stream flow) or biotic factors (local brook trout biomass density and fish age and size) in West Brook, a third-order stream in western Massachusetts, U.S.A.3. Changes in ambient temperature influenced individual growth rates. In general, higher temperatures were associated with higher growth rates in winter and spring and lower growth rates in summer and autumn. However, the effect of temperature on growth was strongly context-dependent, differing in both magnitude and direction as a function of season, stream flow and fish biomass density.4. We found that stream flow and temperature had strong and complex interactive effects on trout growth. At the coldest temperatures (in winter), high stream flows were associated with reduced trout growth rates. During spring and autumn and in typical summers (when water temperatures were close to growth optima), higher flows were associated with increased growth rates. In addition, the effect of flow at a given temperature (the flow-temperature interaction) differed among seasons.5. Trout density negatively affected growth rate and had strong interactions with temperature in two of four seasons (i.e. spring and summer) with greater negative effects at high temperatures.6. Our study provided robust, integrative field-based estimates of the effects of temperature on growth rates for a species which serves as a model organism for cold-water adapted ectotherms facing the consequences of environmental change. Results of the study strongly suggest that failure to derive season-specific estimates, or to explicitly consider interactions with

  11. Rate of outward growth of the Mediterranean ridge accretionary complex

    NASA Astrophysics Data System (ADS)

    Kastens, Kim A.

    1991-12-01

    The position as a function time of the deformation front on the southwest flank of the Mediterranean Ridge accretionary complex is constrained as follows: (a) the deformation front is now active; (b) the site of core BAN84-05GC was still near the abyssal plain when displaced shallow water benthic foraminifera of inferred African provenance were redeposited within an upper Pliocene age unit; (c) the site of core BAN84-05GC on the outer flank of the Mediterranean Ridge was already within the topographically rugged accretionary complex when a Pliocene debris flow was emplaced; (d) DSDP Site 125 had already been uplifted into a topographically elevated position when lower Pliocene pelagic ooze was deposited; (e) a gypsum-bearing breccia in DSDP Site 125 requires that the site was either on the abyssal plain or within the tectonically active outer perimeter of the accretionary complex during the Messinian salinity crisis; (f) DSDP Site 377 had already been uplifted into a topographically elevated position when middle Miocene age pelagic marl was deposited; (g) DSDP Site 377 was still on or near the abyssal plain when early to lower-middle Miocene age, smectite-bearing turbidites of inferred African provenance were deposited; and (h) the Mediterranean Ridge began to grow by offscraping against a backstop formed by the Alpine nappes of the Hellenic Arc at the time that subduction began (> 33 Ma). Together, these constraints define a range of potential growth curves for the Mediterranean Ridge, with a rate of outward growth of approximately 0.5 to 2 cm/yr. This growth rate is faster than that inferred for most other modern accretionary prisms, both as an absolute value, and as a fraction of the subduction velocity. An unusually thick incoming section and/or an unusually weak (evaporitic) décollement may contribute to the rapid growth rate. The inferred age of accretion does not increase linearly with distance from the deformation front; rather, there is an apparent

  12. Flute growth rate of plasma jet in mirror machine

    NASA Astrophysics Data System (ADS)

    Be'ery, I.; Seemann, O.; Goldstein, G.; Fisher, A.; Ron, A.

    2014-02-01

    The evolution of flute instability in a cold, high-density hydrogen plasma jet, injected into a mirror machine, is studied. The experiment was designed to minimize the interaction of the plasma with the walls, thus bringing it close to the ideal magnetic Rayleigh-Taylor instability conditions. The modal growth rate was measured in various settings to demonstrate the effects of the finite Larmor radius, Bohm diffusion, conductive limiter, biased limiter and neutral background gas. In this paper we will demonstrate that lowering the magnetic field increases stability, as does the insertion of a conducting ring. However, if the ring is biased, the stability is reduced due to inhomogeneous coupling between the plasma and the limiter. It was also found that heavy background gas dramatically reduces the flute instability growth rate.

  13. Human Disturbance Influences Reproductive Success and Growth Rate in California Sea Lions (Zalophus californianus)

    PubMed Central

    French, Susannah S.; González-Suárez, Manuela; Young, Julie K.; Durham, Susan; Gerber, Leah R.

    2011-01-01

    The environment is currently undergoing changes at both global (e.g., climate change) and local (e.g., tourism, pollution, habitat modification) scales that have the capacity to affect the viability of animal and plant populations. Many of these changes, such as human disturbance, have an anthropogenic origin and therefore may be mitigated by management action. To do so requires an understanding of the impact of human activities and changing environmental conditions on population dynamics. We investigated the influence of human activity on important life history parameters (reproductive rate, and body condition, and growth rate of neonate pups) for California sea lions (Zalophus californianus) in the Gulf of California, Mexico. Increased human presence was associated with lower reproductive rates, which translated into reduced long-term population growth rates and suggested that human activities are a disturbance that could lead to population declines. We also observed higher body growth rates in pups with increased exposure to humans. Increased growth rates in pups may reflect a density dependent response to declining reproductive rates (e.g., decreased competition for resources). Our results highlight the potentially complex changes in life history parameters that may result from human disturbance, and their implication for population dynamics. We recommend careful monitoring of human activities in the Gulf of California and emphasize the importance of management strategies that explicitly consider the potential impact of human activities such as ecotourism on vertebrate populations. PMID:21436887

  14. Human disturbance influences reproductive success and growth rate in California sea lions (Zalophus californianus).

    PubMed

    French, Susannah S; González-Suárez, Manuela; Young, Julie K; Durham, Susan; Gerber, Leah R

    2011-03-16

    The environment is currently undergoing changes at both global (e.g., climate change) and local (e.g., tourism, pollution, habitat modification) scales that have the capacity to affect the viability of animal and plant populations. Many of these changes, such as human disturbance, have an anthropogenic origin and therefore may be mitigated by management action. To do so requires an understanding of the impact of human activities and changing environmental conditions on population dynamics. We investigated the influence of human activity on important life history parameters (reproductive rate, and body condition, and growth rate of neonate pups) for California sea lions (Zalophus californianus) in the Gulf of California, Mexico. Increased human presence was associated with lower reproductive rates, which translated into reduced long-term population growth rates and suggested that human activities are a disturbance that could lead to population declines. We also observed higher body growth rates in pups with increased exposure to humans. Increased growth rates in pups may reflect a density dependent response to declining reproductive rates (e.g., decreased competition for resources). Our results highlight the potentially complex changes in life history parameters that may result from human disturbance, and their implication for population dynamics. We recommend careful monitoring of human activities in the Gulf of California and emphasize the importance of management strategies that explicitly consider the potential impact of human activities such as ecotourism on vertebrate populations.

  15. Human disturbance influences reproductive success and growth rate in California sea lions (Zalophus californianus).

    PubMed

    French, Susannah S; González-Suárez, Manuela; Young, Julie K; Durham, Susan; Gerber, Leah R

    2011-01-01

    The environment is currently undergoing changes at both global (e.g., climate change) and local (e.g., tourism, pollution, habitat modification) scales that have the capacity to affect the viability of animal and plant populations. Many of these changes, such as human disturbance, have an anthropogenic origin and therefore may be mitigated by management action. To do so requires an understanding of the impact of human activities and changing environmental conditions on population dynamics. We investigated the influence of human activity on important life history parameters (reproductive rate, and body condition, and growth rate of neonate pups) for California sea lions (Zalophus californianus) in the Gulf of California, Mexico. Increased human presence was associated with lower reproductive rates, which translated into reduced long-term population growth rates and suggested that human activities are a disturbance that could lead to population declines. We also observed higher body growth rates in pups with increased exposure to humans. Increased growth rates in pups may reflect a density dependent response to declining reproductive rates (e.g., decreased competition for resources). Our results highlight the potentially complex changes in life history parameters that may result from human disturbance, and their implication for population dynamics. We recommend careful monitoring of human activities in the Gulf of California and emphasize the importance of management strategies that explicitly consider the potential impact of human activities such as ecotourism on vertebrate populations. PMID:21436887

  16. Computing the crystal growth rate by the interface pinning method

    NASA Astrophysics Data System (ADS)

    Pedersen, Ulf R.; Hummel, Felix; Dellago, Christoph

    2015-01-01

    An essential parameter for crystal growth is the kinetic coefficient given by the proportionality between supercooling and average growth velocity. Here, we show that this coefficient can be computed in a single equilibrium simulation using the interface pinning method where two-phase configurations are stabilized by adding a spring-like bias field coupling to an order-parameter that discriminates between the two phases. Crystal growth is a Smoluchowski process and the crystal growth rate can, therefore, be computed from the terminal exponential relaxation of the order parameter. The approach is investigated in detail for the Lennard-Jones model. We find that the kinetic coefficient scales as the inverse square-root of temperature along the high temperature part of the melting line. The practical usability of the method is demonstrated by computing the kinetic coefficient of the elements Na and Si from first principles. A generalized version of the method may be used for computing the rates of crystal nucleation or other rare events.

  17. Slow growth rates of Amazonian trees: Consequences for carbon cycling

    PubMed Central

    Vieira, Simone; Trumbore, Susan; Camargo, Plinio B.; Selhorst, Diogo; Chambers, Jeffrey Q.; Higuchi, Niro; Martinelli, Luiz Antonio

    2005-01-01

    Quantifying age structure and tree growth rate of Amazonian forests is essential for understanding their role in the carbon cycle. Here, we use radiocarbon dating and direct measurement of diameter increment to document unexpectedly slow growth rates for trees from three locations spanning the Brazilian Amazon basin. Central Amazon trees, averaging only ≈1mm/year diameter increment, grow half as fast as those from areas with more seasonal rainfall to the east and west. Slow growth rates mean that trees can attain great ages; across our sites we estimate 17-50% of trees with diameter >10 cm have ages exceeding 300 years. Whereas a few emergent trees that make up a large portion of the biomass grow faster, small trees that are more abundant grow slowly and attain ages of hundreds of years. The mean age of carbon in living trees (60-110 years) is within the range of or slightly longer than the mean residence time calculated from C inventory divided by annual C allocation to wood growth (40-100 years). Faster C turnover is observed in stands with overall higher rates of diameter increment and a larger fraction of the biomass in large, fast-growing trees. As a consequence, forests can recover biomass relatively quickly after disturbance, whereas recovering species composition may take many centuries. Carbon cycle models that apply a single turnover time for carbon in forest biomass do not account for variations in life strategy and therefore may overestimate the carbon sequestration potential of Amazon forests. PMID:16339903

  18. The effect of lean growth rate on puberty attainment in gilts.

    PubMed

    Patterson, J L; Ball, R O; Willis, H J; Aherne, F X; Foxcroft, G R

    2002-05-01

    Two hundred sixteen prepubertal Genex Manor hybrid F1 gilts were used to determine the impact of lean growth rate on sexual development of gilts. This study was composed of two experiments (Exp. 1 and Exp. 2). In Exp. 1, at approximately 96 d of age and 54 kg weight, gilts were allocated with respect to growth rate and litter origin to one of two dietary treatments: 1) a diet formulated to maximize lean growth potential (LP; n = 84) or 2) a diet formulated to produce a lower lean growth rate (LL; n = 84). In Exp. 2, at approximately 88 d of age and 50 kg weight, gilts were allocated with respect to growth rate and litter origin to one of two dietary treatments: 1) a diet formulated to maximize lean growth potential (LP; n = 24) or 2) a diet formulated to restrict lean growth further than was achieved in LL in Exp. 1 (RL; n = 24). All gilts were fed treatment diets for ad libitum consumption and housed in groups of six. Weight, backfat depth and loin depth, and feed intake were measured weekly. Starting at 135 d of age, gilts received 20 min of direct daily exposure to a boar as a pen group for pubertal stimulation. Puberty attainment was determined as the day gilts first exhibited the standing reflex in response to contact with a boar. At pubertal estrus, body weight, backfat depth, and loin depths were recorded. Diet affected (P < or = 0.05) estimated fat-free lean gain (LP, 424 vs LL, 347 g/d, Exp. 1; LP, 397 vs RL, 376 g/d, Exp. 2) during the growth period (start to stimulation). However, age at puberty was not affected by diet (LP, 157.3 vs LL, 157.6, Exp. 1; LP, 166.7 vs RL, 167.3, Exp. 2) or overall lean growth at stimulation (P > or = 0.05 in both experiments), confirming that innate variability in sexual development of commercial genotypes, rather than growth performance, determines onset of sexual maturity. A negative correlation between age at puberty and growth rate from 50 kg until puberty (P < or = 0.05) (LP, r = -0.40, LL, r = -0.36, Exp. 1; LP, r

  19. Interspecific synchrony of seabird population growth rate and breeding success

    PubMed Central

    Robinson, James P W; Dornelas, Maria; Ojanguren, Alfredo F

    2013-01-01

    Environmental variability can destabilize communities by causing correlated interspecific fluctuations that weaken the portfolio effect, yet evidence of such a mechanism is rare in natural systems. Here, we ask whether the population dynamics of similar sympatric species of a seabird breeding community are synchronized, and if these species have similar exceptional responses to environmental variation. We used a 24-year time series of the breeding success and population growth rate of a marine top predator species group to assess the degree of synchrony between species demography. We then developed a novel method to examine the species group – all species combined – response to environmental variability, in particular, whether multiple species experience similar, pronounced fluctuations in their demography. Multiple species were positively correlated in breeding success and growth rate. Evidence of “exceptional” years was found, where the species group experienced pronounced fluctuations in their demography. The synchronous response of the species group was negatively correlated with winter sea surface temperature of the preceding year for both growth rate and breeding success. We present evidence for synchronous, exceptional responses of a species group that are driven by environmental variation. Such species covariation destabilizes communities by reducing the portfolio effect, and such exceptional responses may increase the risk of a state change in this community. Our understanding of the future responses to environmental change requires an increased focus on the short-term fluctuations in demography that are driven by extreme environmental variability. PMID:23919147

  20. On Growth Rates of Subadditive Functions for Semiflows

    NASA Astrophysics Data System (ADS)

    Schreiber, Sebastian J.

    1998-09-01

    Letφ: X×T+→Xbe a semiflow on a compact metric spaceX. A functionF: X×T+→Xis subadditive with respect toφifF(x, t+s)⩽F(x, t)+F(φ(x, t),nbsp;s). We define the maximal growth rate ofFto be supx∈X lim supt→∞(1/t) F(x, t). This growth rate is shown to equal the maximal growth rate of the subadditive function restricted to the minimal center of attraction of the semiflow. Applications to Birkhoff sums, characteristic exponents of linear skew-product semiflows on Banach bundles, and average Lyapunov functions are developed. In particular, a relationship between the dynamical spectrum and the measurable spectrum of a linear skew-product flow established by R. A. Johnson, K. J. Palmer, and G. R. Sell (SIAM J. Math. Anal.18, 1987, 1-33) is extended to semiflows in an infinite dimensional setting.

  1. Factors affecting Staphylococcus epidermidis growth in peritoneal dialysis solutions.

    PubMed Central

    McDonald, W A; Watts, J; Bowmer, M I

    1986-01-01

    Staphylococcus epidermidis is the most frequent cause of peritonitis complicating continuous ambulatory peritoneal dialysis. We studied factors that might influence the growth of S. epidermidis in commercially available peritoneal dialysis solution (PDS). Test strains were inoculated into PDS and incubated overnight at 37 degrees C. Samples were removed at appropriate intervals, bacterial counts were performed, and growth curves were constructed. We studied the effects of various osmolarities, the neutralization and acidification of fresh and spent PDS, and the effect of intraperitoneal dwell time on the ability PDS to support growth of S. epidermidis. In fresh PDS, numbers of bacteria remained constant after 24 h. No significant differences in growth were observed among PDS with 0.5, 1.5, 2.5, and 4.25% glucose. Neutralizing acidic fresh PDS had no effect on bacterial growth. However, growth did occur in spent PDS. PDS which was recovered after only 2 h in the peritoneal cavity supported growth to the same extent as did PDS recovered after 4 to 6 h. Mean log10 changes after 24 h of incubation were as follows: for fresh PDS, -1.3; after 2 h dwell time, 2.9; after 4 h dwell time, 1.9; and after 6 h dwell time, 1.3. Acidification of spent PDS to less than pH 6.35 produced less rapid growth; mean log10 increases after 24 h of incubation were 1.9 for pH 7.75, 1.6 for pH 6.35, 0.6 for pH 5.75, and 0.7 for pH 4.95. Fresh PDS of all available osmolarities neither supported the growth of S. epidermidis nor was bactericidal. Spent PDS supported bacterial growth, and this growth was partly independent of the neutralization which occurred during the dialysis. PMID:3722356

  2. CK2 activity is modulated by growth rate in Saccharomyces cerevisiae

    SciTech Connect

    Tripodi, Farida; Cirulli, Claudia; Reghellin, Veronica; Marin, Oriano; Brambilla, Luca; Schiappelli, Maria Patrizia; Porro, Danilo; Vanoni, Marco; Alberghina, Lilia; Coccetti, Paola

    2010-07-16

    Research highlights: {yields} CK2 subunits are nuclear both in glucose and in ethanol growing yeast cells. {yields} CK2 activity is modulated in S. cerevisiae. {yields} CK2 activity is higher in conditions supporting higher growth rates. {yields} V{sub max} is higher in faster growing cells, while K{sub m} is not affected. -- Abstract: CK2 is a highly conserved protein kinase controlling different cellular processes. It shows a higher activity in proliferating mammalian cells, in various types of cancer cell lines and tumors. The findings presented herein provide the first evidence of an in vivo modulation of CK2 activity, dependent on growth rate, in Saccharomyces cerevisiae. In fact, CK2 activity, assayed on nuclear extracts, is shown to increase in exponential growing batch cultures at faster growth rate, while localization of catalytic and regulatory subunits is not nutritionally modulated. Differences in intracellular CK2 activity of glucose- and ethanol-grown cells appear to depend on both increase in molecule number and k{sub cat}. Also in chemostat cultures nuclear CK2 activity is higher in faster growing cells providing the first unequivocal demonstration that growth rate itself can affect CK2 activity in a eukaryotic organism.

  3. Organizational Career Growth, Affective Occupational Commitment and Turnover Intentions

    ERIC Educational Resources Information Center

    Weng, Qingxiong; McElroy, James C.

    2012-01-01

    Survey data, collected from the People's Republic of China, were used to test Weng's (2010) four facet model of career growth and to examine its effect on occupational commitment and turnover intentions. Weng conceptualized career growth as consisting of four factors: career goal progress, professional ability development, promotion speed, and…

  4. Dimensions of Escherichia coli at various growth rates: model for envelope growth.

    PubMed Central

    Pierucci, O

    1978-01-01

    The duplication of Escherichia coli B/r is described based on two independent sequences, the replication of the genome and the growth of the envelope. It is proposed that (i) new envelope growth zones are activated coincident with the initiation of new rounds of chromosome replication; (ii) each zone is active in envelope synthesis from the time of its inauguration to the division which follows the completion of the round of chromosome replication (that is, for C + D min); and (iii) the rate of envelope synthesis at each site is constant, independent of the growth rate. Measurements of the surface areas of two E. coli B/r substrains growing at a variety of rates and during nutritional transitions are consistent with the predictions of the model. PMID:355233

  5. Differential Effect of Culture Temperature and Specific Growth Rate on CHO Cell Behavior in Chemostat Culture

    PubMed Central

    Vergara, Mauricio; Becerra, Silvana; Berrios, Julio; Osses, Nelson; Reyes, Juan; Rodríguez-Moyá, María; Gonzalez, Ramon; Altamirano, Claudia

    2014-01-01

    Mild hypothermia condition in mammalian cell culture technology has been one of the main focuses of research for the development of breeding strategies to maximize productivity of these production systems. Despite the large number of studies that show positive effects of mild hypothermia on specific productivity of r-proteins, no experimental approach has addressed the indirect effect of lower temperatures on specific cell growth rate, nor how this condition possibly affects less specific productivity of r-proteins. To separately analyze the effects of mild hypothermia and specific growth rate on CHO cell metabolism and recombinant human tissue plasminogen activator productivity as a model system, high dilution rate (0.017 h−1) and low dilution rate (0.012 h−1) at two cultivation temperatures (37 and 33°C) were evaluated using chemostat culture. The results showed a positive effect on the specific productivity of r-protein with decreasing specific growth rate at 33°C. Differential effect was achieved by mild hypothermia on the specific productivity of r-protein, contrary to the evidence reported in batch culture. Interestingly, reduction of metabolism could not be associated with a decrease in culture temperature, but rather with a decrease in specific growth rate. PMID:24699760

  6. Fishery-induced selection on an Alpine whitefish: quantifying genetic and environmental effects on individual growth rate

    PubMed Central

    Nusslé, Sébastien; Bornand, Christophe N; Wedekind, Claus

    2009-01-01

    Size-selective fishing, environmental changes and reproductive strategies are expected to affect life-history traits such as the individual growth rate. The relative contribution of these factors is not clear, particularly whether size-selective fishing can have a substantial impact on the genetics and hence on the evolution of individual growth rates in wild populations. We analysed a 25-year monitoring survey of an isolated population of the Alpine whitefish Coregonus palaea. We determined the selection differentials on growth rate, the actual change of growth rate over time and indicators of reproductive strategies that may potentially change over time. The selection differential can be reliably estimated in our study population because almost all the fish are harvested within their first years of life, i.e. few fish escape fishing mortality. We found a marked decline in average adult growth rate over the 25 years and a significant selection differential for adult growth, but no evidence for any linear change in reproductive strategies over time. Assuming that the heritability of growth in this whitefish corresponds to what was found in other salmonids, about a third of the observed decline in growth rate would be linked to fishery-induced evolution. Size-selective fishing seems to affect substantially the genetics of individual growth in our study population. PMID:25567861

  7. Sodic soil properties and sunflower growth as affected by byproducts of flue gas desulfurization.

    PubMed

    Wang, Jinman; Bai, Zhongke; Yang, Peiling

    2012-01-01

    The main component of the byproducts of flue gas desulfurization (BFGD) is CaSO(4), which can be used to improve sodic soils. The effects of BFGD on sodic soil properties and sunflower growth were studied in a pot experiment. The experiment consisted of eight treatments, at four BFGD rates (0, 7.5, 15 and 22.5 t ha(-1)) and two leaching levels (750 and 1200 m(3) ha(-1)). The germination rate and yield of the sunflower increased, and the exchangeable sodium percentage (ESP), pH and total dissolved salts (TDS) in the soils decreased after the byproducts were applied. Excessive BFGD also affected sunflower germination and growth, and leaching improved reclamation efficiency. The physical and chemical properties of the reclaimed soils were best when the byproducts were applied at 7.5 t ha(-1) and water was supplied at 1200 m(3)·ha(-1). Under these conditions, the soil pH, ESP, and TDS decreased from 9.2, 63.5 and 0.65% to 7.8, 2.8 and 0.06%, and the germination rate and yield per sunflower reached 90% and 36.4 g, respectively. Salinity should be controlled by leaching when sodic soils are reclaimed with BFGD as sunflower growth is very sensitive to salinity during its seedling stage. PMID:23285042

  8. Sodic Soil Properties and Sunflower Growth as Affected by Byproducts of Flue Gas Desulfurization

    PubMed Central

    Wang, Jinman; Bai, Zhongke; Yang, Peiling

    2012-01-01

    The main component of the byproducts of flue gas desulfurization (BFGD) is CaSO4, which can be used to improve sodic soils. The effects of BFGD on sodic soil properties and sunflower growth were studied in a pot experiment. The experiment consisted of eight treatments, at four BFGD rates (0, 7.5, 15 and 22.5 t ha−1) and two leaching levels (750 and 1200 m3 ha−1). The germination rate and yield of the sunflower increased, and the exchangeable sodium percentage (ESP), pH and total dissolved salts (TDS) in the soils decreased after the byproducts were applied. Excessive BFGD also affected sunflower germination and growth, and leaching improved reclamation efficiency. The physical and chemical properties of the reclaimed soils were best when the byproducts were applied at 7.5 t ha−1 and water was supplied at 1200 m3·ha−1. Under these conditions, the soil pH, ESP, and TDS decreased from 9.2, 63.5 and 0.65% to 7.8, 2.8 and 0.06%, and the germination rate and yield per sunflower reached 90% and 36.4 g, respectively. Salinity should be controlled by leaching when sodic soils are reclaimed with BFGD as sunflower growth is very sensitive to salinity during its seedling stage. PMID:23285042

  9. Individual variation affects departure rate from the natal pond in an ephemeral pond-breeding anuran

    USGS Publications Warehouse

    Chelgren, N.D.; Rosenberg, D.K.; Heppell, S.S.; Gitelman, A.I.

    2008-01-01

    Frogs exhibit extreme plasticity and individual variation in growth and behavior during metamorphosis, driven by interactions of intrinsic state factors and extrinsic environmental factors. In northern red-legged frogs (Rana aurora Baird and Girard, 1852), we studied the timing of departure from the natal pond as it relates to date and size of individuals at metamorphosis in the context of environmental uncertainty. To affect body size at metamorphosis, we manipulated food availability during the larval stage for a sample (317) of 1045 uniquely marked individuals and released them at their natal ponds as newly metamorphosed frogs. We recaptured 34% of marked frogs in pitfall traps as they departed and related the timing of their initial terrestrial movements to individual properties using a time-to-event model. Median age at first capture was 4 and 9 days postmetamorphosis at two sites. The rate of departure was positively related to body size and to date of metamorphosis. Departure rate was strongly negatively related to time elapsed since rainfall, and this effect was diminished for smaller and later metamorphosing frogs. Individual variation in metamorphic traits thus affects individuals' responses to environmental variability, supporting a behavioral link with variation in survival associated with these same metamorphic traits. ?? 2008 NRC.

  10. Imaging System For Measuring Macromolecule Crystal Growth Rates in Microgravity

    NASA Technical Reports Server (NTRS)

    Corder, Eric L.; Briscoe, Jeri

    2004-01-01

    In order to determine how macromolecule crystal quality improvement in microgravity is related to crystal growth characteristics, a team of scientists and engineers at NASA's Marshal Space Flight Center (MSFC) developed flight hardware capable of measuring the crystal growth rates of a population of crystals growing under the same conditions. As crystal growth rate is defined as the change or delta in a defined dimension or length (L) of crystal over time, the hardware was named Delta-L. Delta-L consists of three sub assemblies: a fluid unit including a temperature-controlled growth cell, an imaging unit, and a control unit (consisting of a Data Acquisition and Control Unit (DACU), and a thermal control unit). Delta-L will be used in connection with the Glovebox Integrated Microgravity Isolation Technology (g-LIMIT) inside the Microgravity Science Glovebox (MSG), onboard the International Space Station. This paper will describe the Delta-L imaging system. The Delta-L imaging system was designed to locate, resolve, and capture images of up to 10 individual crystals ranging in size from 10 to 500 microns with a point-to-point accuracy of +/- 2.0 microns within a quartz growth cell observation area of 20 mm x 10 mm x 1 mm. The optical imaging system is comprised of a video microscope camera mounted on computer controlled translation stages. The 3-axis translation stages and control units provide crewmembers the ability to search throughout the growth cell observation area for crystals forming in size of approximately 10 microns. Once the crewmember has selected ten crystals of interest, the growth of these crystals is tracked until the size reaches approximately 500 microns. In order to resolve these crystals an optical system with a magnification of 10X was designed. A black and white NTSC camera was utilized with a 20X microscope objective and a 0.5X custom designed relay lens with an inline light to meet the magnification requirement. The design allows a 500 pm

  11. Perspectives on massive coral growth rates in a changing ocean.

    PubMed

    Lough, Janice M; Cantin, Neal E

    2014-06-01

    The tropical ocean environment is changing at an unprecedented rate, with warming and severe tropical cyclones creating obvious impacts to coral reefs within the last few decades and projections of acidification raising concerns for the future of these iconic and economically important ecosystems. Documenting variability and detecting change in global and regional climate relies upon high-quality observational records of climate variables supplemented, prior to the mid-19th century, with reconstructions from various sources of proxy climate information. Here we review how annual density banding patterns that are recorded in the skeletons of massive reef-building corals have been used to document environmental change and impacts within coral reefs. Massive corals provide a historical perspective of continuous calcification processes that pre-date most ecological observations of coral reefs. High-density stress bands, abrupt declines in annual linear extension, and evidence of partial mortality within the skeletal growth record reveal signatures of catastrophic stress events that have recently been attributed to mass bleaching events caused by unprecedented thermal stress. Comparison of recent trends in annual calcification with century-scale baseline calcification rates reveals that the frequency of growth anomalies has increased since the late 1990s throughout most of the world's coral reef ecosystems. Continuous coral growth histories provide valuable retrospective information on the coral response to environmental change and the consequences of anthropogenic climate change. Co-ordinated efforts to synthesize and combine global calcification histories will greatly enhance our understanding of current calcification responses to a changing ocean.

  12. Diffusion-controlled growth rate of stepped interfaces.

    PubMed

    Saidi, P; Hoyt, J J

    2015-07-01

    For many materials, the structure of crystalline surfaces or solid-solid interphase boundaries is characterized by an array of mobile steps separated by immobile terraces. Despite the prevalence of step-terraced interfaces a theoretical description of the growth rate has not been completely solved. In this work the boundary element method (BEM) has been utilized to numerically compute the concentration profile in a fluid phase in contact with an infinite array of equally spaced surface steps and, under the assumption that step motion is controlled by diffusion through the fluid phase, the growth rate is computed. It is also assumed that a boundary layer exists between the growing surface and a point in the liquid where complete convective mixing occurs. The BEM results are presented for varying step spacing, supersaturation, and boundary layer width. BEM calculations were also used to study the phenomenon of step bunching during crystal growth, and it is found that, in the absence of elastic strain energy, a sufficiently large perturbation in the position of a step from its regular spacing will lead to a step bunching instability. Finally, an approximate analytic solution using a matched asymptotic expansion technique is presented for the case of a stagnant liquid or equivalently a solid-solid stepped interface.

  13. Bacterial growth rates are influenced by cellular characteristics of individual species when immersed in electromagnetic fields.

    PubMed

    Tessaro, Lucas W E; Murugan, Nirosha J; Persinger, Michael A

    2015-03-01

    Previous studies have shown that exposure to extremely low-frequency electromagnetic fields (ELF-EMFs) have negative effects on the rate of growth of bacteria. In the present study, two Gram-positive and two Gram-negative species were exposed to six magnetic field conditions in broth cultures. Three variations of the 'Thomas' pulsed frequency-modulated pattern; a strong-static "puck" magnet upwards of 5000G in intensity; a pair of these magnets rotating opposite one another at ∼30rpm; and finally a strong dynamic magnetic field generator termed the 'Resonator' with an average intensity of 250μT were used. Growth rate was discerned by optical density (OD) measurements every hour at 600nm. ELF-EMF conditions significantly affected the rates of growth of the bacterial cultures, while the two static magnetic field conditions were not statistically significant. Most interestingly, the 'Resonator' dynamic magnetic field increased the rates of growth of three species (Staphylococcus epidermidis, Staphylococcus aureus, and Escherichia coli), while slowing the growth of one (Serratia marcescens). We suggest that these effects are due to individual biophysical characteristics of the bacterial species.

  14. Modeling circadian clock-cell cycle interaction effects on cell population growth rates.

    PubMed

    El Cheikh, R; Bernard, S; El Khatib, N

    2014-12-21

    The circadian clock and the cell cycle are two tightly coupled oscillators. Recent analytical studies have shown counter-intuitive effects of circadian gating of the cell cycle on growth rates of proliferating cells which cannot be explained by a molecular model or a population model alone. In this work, we present a combined molecular-population model that studies how coupling the circadian clock to the cell cycle, through the protein WEE1, affects a proliferating cell population. We show that the cell cycle can entrain to the circadian clock with different rational period ratios and characterize multiple domains of entrainment. We show that coupling increases the growth rate for autonomous periods of the cell cycle around 24 h and above 48 h. We study the effect of mutation of circadian genes on the growth rate of cells and show that disruption of the circadian clock can lead to abnormal proliferation. Particularly, we show that Cry 1, Cry 2 mutations decrease the growth rate of cells, Per 2 mutation enhances it and Bmal 1 knockout increases it for autonomous periods of the cell cycle less than 21 h and decreases it elsewhere. Combining a molecular model to a population model offers new insight on the influence of the circadian clock on the growth of a cell population. This can help chronotherapy which takes benefits of physiological rhythms to improve anti-cancer efficacy and tolerance to drugs by administering treatments at a specific time of the day.

  15. Rate of Conditioned Reinforcement Affects Observing Rate but Not Resistance to Change

    ERIC Educational Resources Information Center

    Shahan, Timothy A.; Podlesnik, Christopher A.

    2005-01-01

    The effects of rate of conditioned reinforcement on the resistance to change of operant behavior have not been examined. In addition, the effects of rate of conditioned reinforcement on the rate of observing have not been adequately examined. In two experiments, a multiple schedule of observing-response procedures was used to examine the effects…

  16. Postnatal growth rates covary weakly with embryonic development rates and do not explain adult mortality probability among songbirds on four continents

    USGS Publications Warehouse

    Martin, Thomas E.; Oteyza, Juan C.; Mitchell, Adam E.; Potticary, Ahva L.; Lloyd, P.

    2016-01-01

    Growth and development rates may result from genetic programming of intrinsic processes that yield correlated rates between life stages. These intrinsic rates are thought to affect adult mortality probability and longevity. However, if proximate extrinsic factors (e.g., temperature, food) influence development rates differently between stages and yield low covariance between stages, then development rates may not explain adult mortality probability. We examined these issues based on study of 90 songbird species on four continents to capture the diverse life-history strategies observed across geographic space. The length of the embryonic period explained little variation (ca. 13%) in nestling periods and growth rates among species. This low covariance suggests that the relative importance of intrinsic and extrinsic influences on growth and development rates differs between stages. Consequently, nestling period durations and nestling growth rates were not related to annual adult mortality probability among diverse songbird species within or among sites. The absence of a clear effect of faster growth on adult mortality when examined in an evolutionary framework across species may indicate that species that evolve faster growth also evolve physiological mechanisms for ameliorating costs on adult mortality. Instead, adult mortality rates of species in the wild may be determined more strongly by extrinsic environmental causes.

  17. Postnatal growth rates covary weakly with embryonic development rates and do not explain adult mortality probability among songbirds on four continents.

    PubMed

    Martin, Thomas E; Oteyza, Juan C; Mitchell, Adam E; Potticary, Ahva L; Lloyd, Penn

    2015-03-01

    Growth and development rates may result from genetic programming of intrinsic processes that yield correlated rates between life stages. These intrinsic rates are thought to affect adult mortality probability and longevity. However, if proximate extrinsic factors (e.g., temperature, food) influence development rates differently between stages and yield low covariance between stages, then development rates may not explain adult mortality probability. We examined these issues based on study of 90 songbird species on four continents to capture the diverse life-history strategies observed across geographic space. The length of the embryonic period explained little variation (ca. 13%) in nestling periods and growth rates among species. This low covariance suggests that the relative importance of intrinsic and extrinsic influences on growth and development rates differs between stages. Consequently, nestling period durations and nestling growth rates were not related to annual adult mortality probability among diverse songbird species within or among sites. The absence of a clear effect of faster growth on adult mortality when examined in an evolutionary framework across species may indicate that species that evolve faster growth also evolve physiological mechanisms for ameliorating costs on adult mortality. Instead, adult mortality rates of species in the wild may be determined more strongly by extrinsic environmental causes.

  18. Postnatal nutritional restriction affects growth and immune function of piglets with intra-uterine growth restriction.

    PubMed

    Hu, Liang; Liu, Yan; Yan, Chuan; Peng, Xie; Xu, Qin; Xuan, Yue; Han, Fei; Tian, Gang; Fang, Zhengfeng; Lin, Yan; Xu, Shengyu; Zhang, Keying; Chen, Daiwen; Wu, De; Che, Lianqiang

    2015-07-14

    Postnatal rapid growth by excess intake of nutrients has been associated with an increased susceptibility to diseases in neonates with intra-uterine growth restricted (IUGR). The aim of the present study was to determine whether postnatal nutritional restriction could improve intestinal development and immune function of neonates with IUGR using piglets as model. A total of twelve pairs of normal-birth weight (NBW) and IUGR piglets (7 d old) were randomly assigned to receive adequate nutrient intake or restricted nutrient intake (RNI) by artificially liquid feeding for a period of 21 d. Blood samples and intestinal tissues were collected at necropsy and were analysed for morphology, digestive enzyme activities, immune cells and expression of innate immunity-related genes. The results indicated that both IUGR and postnatal nutritional restriction delayed the growth rate during the sucking period. Irrespective of nutrient intake, piglets with IUGR had a significantly lower villous height and crypt depth in the ileum than the NBW piglets. Moreover, IUGR decreased alkaline phosphatase activity while enhanced lactase activity in the jejunum and mRNA expressions of Toll-like receptor 9 (TLR-9) and DNA methyltransferase 1 (DNMT1) in the ileum of piglets. Irrespective of body weight, RNI significantly decreased the number and/or percentage of peripheral leucocytes, lymphocytes and monocytes of piglets, whereas the percentage of neutrophils and the ratio of CD4+ to CD8+ were increased. Furthermore, RNI markedly enhanced the mRNA expression of TLR-9 and DNMT1, but decreased the expression of NOD2 and TRAF-6 in the ileum of piglets. In summary, postnatal nutritional restriction led to abnormal cellular and innate immune response, as well as delayed the growth and intestinal development of IUGR piglets. PMID:26059215

  19. Sodium sulfate impacts feeding, specific dynamic action, and growth rate in the freshwater bivalve Corbicula fluminea.

    PubMed

    Soucek, David John

    2007-08-01

    Sodium sulfate is a ubiquitous salt that reaches toxic concentrations due to mining and other industrial activities, yet is currently unregulated at the Federal level in the United States. Previous studies have documented reduced growth of clams downstream of sulfate-dominated effluents, altered bioenergetics in filter-feeding invertebrates, and interactions between sulfate and other toxicants. Therefore, the purpose of this study was to determine if sodium sulfate affects the bioenergetics of the filter-feeding, freshwater bivalve, Corbicula fluminea, and the mechanism by which the effects are elicited. In addition to measuring effects on feeding, respiration and growth rates, I evaluated the relative sensitivity of a green algae consumed by clams to determine if top-down or bottom-up effects might be exhibited under field conditions. This study demonstrated that sodium sulfate had no effect on basal metabolic rates, but significantly reduced the feeding, post-feeding metabolic, and growth rates of C. fluminea. The proposed mechanism for these impacts is that filtering rates are reduced upon exposure, resulting in reduced food consumption and therefore, preventing increased metabolic rates normally associated with post-feeding specific dynamic action (SDA). In the field, these effects may cause changes in whole stream respiration rates and organic matter dynamics, as well as alter uptake rates of other food-associated contaminants like selenium, the toxicity of which is known to be antagonized by sulfate, in filter-feeding bivalves.

  20. Respiration, growth and grazing rates of three ciliate species in hypoxic conditions.

    PubMed

    Rocke, Emma; Liu, Hongbin

    2014-08-30

    Marine hypoxic episodes are affecting both marine and freshwater bodies all over the world. Yet, limited data exists with regard to the effects of decreasing oxygen on protist metabolism. Three ciliate species were therefore isolated from Hong Kong coastal waters. Controlled hypoxic conditions were simulated in the lab environment, during which time growth, respiration and grazing rates were measured. Euplotes sp. and a Oxytrichidae-like ciliate showed decreased growth and respiration below 2.5 mg O2 L(-1), however Uronema marinum kept steady growth and respiration until below 1.5 mg O2 L(-1). Euplotes sp. and the Oxytrichidae-like ciliate had the highest ingestion rate, which dropped significantly below 3.0 mg O2 L(-1). U.marinum grazing rates were affected at and below 1.5 mg O2 L(-1), correlating with their drop in growth and respiration at this lower concentration. This study illustrates the slowing metabolism of key grazing protists, as well as species-specific tolerance in response to hypoxia.

  1. A model of northern pintail productivity and population growth rate

    USGS Publications Warehouse

    Flint, P.L.; Grand, J.B.; Rockwell, R.F.

    1998-01-01

    Our objective was to synthesize individual components of reproductive ecology into a single estimate of productivity and to assess the relative effects of survival and productivity on population dynamics. We used information on nesting ecology, renesting potential, and duckling survival of northern pintails (Anas acuta) collected on the Yukon-Kuskokvim Delta (Y-K Delta), Alaska, 1991-95, to model the number of ducklings produced under a range of nest success and duckling survival probabilities. Using average values of 25% nest success, 11% duckling survival, and 56% renesting probability from our study population, we calculated that all young in our population were produced by 13% of the breeding females, and that early-nesting females produced more young than later-nesting females. Further, we calculated, on average, that each female produced only 0.16 young females/nesting season. We combined these results with estimates of first-year and adult survival to examine the growth rate (??) of the population and the relative contributions of these demographic parameters to that growth rate. Contrary to aerial survey data, the population projection model suggests our study population is declining rapidly (?? = 0.6969). The relative effects on population growth rate were 0.1175 for reproductive success, 0.1175 for first-year survival, and 0.8825 for adult survival. Adult survival had the greatest influence on ?? for our population, and this conclusion was robust over a range of survival and productivity estimates. Given published estimates of annual survival for adult females (61%), our model suggested nest success and duckling survival need to increase to approximately 40% to achieve population stability. We discuss reasons for the apparent discrepancy in population trends between our model and aerial surveys in terms of bias in productivity and survival estimates.

  2. Cottonwood growth rate and fine root condensed tannin concentration.

    PubMed

    Kosola, Kevin R; Dickmann, Donald I; Hall, Richard B; Workmaster, Beth Ann A

    2004-09-01

    We examined the relationship between trunk diameter and diameter relative growth rate (RGR) and fine root condensed tannin concentration in 12 genotypes of eastern cottonwood (Populus deltoides Bartr. ex Marsh.) planted in three locations across the north central United States. Across genotypes, trunk diameter, diameter RGR and root condensed tannin concentration were negatively correlated at one location (Wisconsin), but showed no significant correlation at the other locations (Iowa and Michigan). The factors responsible for this difference among sites remain unidentified, but may be related to soil fertility.

  3. Growth rate effects on Mg/Ca and Sr/Ca ratios constrained by belemnite calcite

    NASA Astrophysics Data System (ADS)

    Vinzenz Ullmann, Clemens

    2016-04-01

    Multiple temperature proxies from single species are important to achieve robust palaeotemperature estimates. Besides the commonly employed oxygen isotope thermometer, also Mg/Ca and Sr/Ca ratios perform well as proxies for calcification temperature in the shells of some species. While salinity changes affect the ratios of earth alkaline elements much less than the δ18O thermometer, metabolic effects may exert a strong control on the expression of element ratios. Such effects are hard to study because biomineralization experiments have to overcome large intraspecific variability and can hardly ever isolate the controls of a single parameter on shell geochemistry. The unique geometry of the belemnite rostrum constitutes an exception to this rule. Its shape, large size, and the visibility of growth increments as bands enable the analysis of multiple, correlatable, high resolution geochemical profiles in a single fossil. The effects of the growth rate variability amongst these profiles on Mg/Ca and Sr/Ca ratios has been tested here. Within a specimen of Passaloteuthis bisulcata (Early Toarcian, Cleveland Basin, UK), Mg/Ca and Sr/Ca data were obtained from four profiles. With respect to growth rate in the first profile, which was taken as a reference, the relative growth rates in the remaining three profiles varied by a factor of 0.9 to 2.7. Results suggest that relative growth rate is linearly correlated with Mg/Ca and Sr/Ca, with a decrease of Mg/Ca by 8 % and increase of Sr/Ca by 6 % per 100 % increase in relative growth rate. The observed trends are consistent with abiogenic precipitation experiments and suggest that crystal precipitation rate exerts a significant, predictable control on the element distribution in biogenic calcite.

  4. Factors affecting plant growth in membrane nutrient delivery

    NASA Technical Reports Server (NTRS)

    Dreschel, T. W.; Wheeler, R. M.; Sager, J. C.; Knott, W. M.

    1990-01-01

    The development of the tubular membrane plant growth unit for the delivery of water and nutrients to roots in microgravity has recently focused on measuring the effects of changes in physical variables controlling solution availability to the plants. Significant effects of membrane pore size and the negative pressure used to contain the solution were demonstrated. Generally, wheat grew better in units with a larger pore size but equal negative pressure and in units with the same pore size but less negative pressure. Lettuce also exhibited better plant growth at less negative pressure.

  5. Estimation of Eruption Source Parameters from Plume Growth Rate

    NASA Astrophysics Data System (ADS)

    Pouget, Solene; Bursik, Marcus; Webley, Peter; Dehn, Jon; Pavalonis, Michael; Singh, Tarunraj; Singla, Puneet; Patra, Abani; Pitman, Bruce; Stefanescu, Ramona; Madankan, Reza; Morton, Donald; Jones, Matthew

    2013-04-01

    The eruption of Eyjafjallajokull, Iceland in April and May, 2010, brought to light the hazards of airborne volcanic ash and the importance of Volcanic Ash Transport and Dispersion models (VATD) to estimate the concentration of ash with time. These models require Eruption Source Parameters (ESP) as input, which typically include information about the plume height, the mass eruption rate, the duration of the eruption and the particle size distribution. However much of the time these ESP are unknown or poorly known a priori. We show that the mass eruption rate can be estimated from the downwind plume or umbrella cloud growth rate. A simple version of the continuity equation can be applied to the growth of either an umbrella cloud or the downwind plume. The continuity equation coupled with the momentum equation using only inertial and gravitational terms provides another model. Numerical modeling or scaling relationships can be used, as necessary, to provide values for unknown or unavailable parameters. Use of these models applied to data on plume geometry provided by satellite imagery allows for direct estimation of plume volumetric and mass growth with time. To test our methodology, we compared our results with five well-studied and well-characterized historical eruptions: Mount St. Helens, 1980; Pinatubo, 1991, Redoubt, 1990; Hekla, 2000 and Eyjafjallajokull, 2010. These tests show that the methodologies yield results comparable to or better than currently accepted methodologies of ESP estimation. We then applied the methodology to umbrella clouds produced by the eruptions of Okmok, 12 July 2008, and Sarychev Peak, 12 June 2009, and to the downwind plume produced by the eruptions of Hekla, 2000; Kliuchevsko'i, 1 October 1994; Kasatochi 7-8 August 2008 and Bezymianny, 1 September 2012. The new methods allow a fast, remote assessment of the mass eruption rate, even for remote volcanoes. They thus provide an additional path to estimation of the ESP and the forecasting

  6. Climate forcing growth rates: doubling down on our Faustian bargain

    NASA Astrophysics Data System (ADS)

    Hansen, James; Kharecha, Pushker; Sato, Makiko

    2013-03-01

    Rahmstorf et al 's (2012) conclusion that observed climate change is comparable to projections, and in some cases exceeds projections, allows further inferences if we can quantify changing climate forcings and compare those with projections. The largest climate forcing is caused by well-mixed long-lived greenhouse gases. Here we illustrate trends of these gases and their climate forcings, and we discuss implications. We focus on quantities that are accurately measured, and we include comparison with fixed scenarios, which helps reduce common misimpressions about how climate forcings are changing. Annual fossil fuel CO2 emissions have shot up in the past decade at about 3% yr-1, double the rate of the prior three decades (figure 1). The growth rate falls above the range of the IPCC (2001) 'Marker' scenarios, although emissions are still within the entire range considered by the IPCC SRES (2000). The surge in emissions is due to increased coal use (blue curve in figure 1), which now accounts for more than 40% of fossil fuel CO2 emissions. Figure 1. Figure 1. CO2 annual emissions from fossil fuel use and cement manufacture, an update of figure 16 of Hansen (2003) using data of British Petroleum (BP 2012) concatenated with data of Boden et al (2012). The resulting annual increase of atmospheric CO2 (12-month running mean) has grown from less than 1 ppm yr-1 in the early 1960s to an average ~2 ppm yr-1 in the past decade (figure 2). Although CO2 measurements were not made at sufficient locations prior to the early 1980s to calculate the global mean change, the close match of global and Mauna Loa data for later years suggests that Mauna Loa data provide a good approximation of global change (figure 2), thus allowing a useful estimate of annual global change beginning with the initiation of Mauna Loa measurements in 1958 by Keeling et al (1973). Figure 2. Figure 2. Annual increase of CO2 based on data from the NOAA Earth System Research Laboratory (ESRL 2012). CO2 change

  7. Gain-Loss versus Reinforcement-Affect Ordering of Student Rating of Teaching: Effect of Rating Instructions.

    ERIC Educational Resources Information Center

    Turcotte, Shelly J. C.; Leventhal, Les

    1984-01-01

    This study investigated the effect of student rating instructions on primacy and recency effects when rank ordering four lecture quality sequences. Effects were measured on final instructor ratings, liking for the instructor, student affect, and student self-esteem. (Author/BS)

  8. Shade periodicity affects growth of container grown dogwoods

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Container-grown dogwoods rank third in the US in nursery sales of ornamental trees. However, Dogwoods are a challenging crop to produce in container culture, especially when bare root liners are used as the initial transplant into containers due unacceptable levels of mortality and poor growth. This...

  9. Dissolved oxygen concentration affects hybrid striped bass growth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Management of dissolved oxygen (DO) concentration in ponds at night during the growing season is important because fish growth and yield are greater in ponds with higher nightly DO concentrations. Three studies were conducted to quantify performance traits and metabolic responses of hybrid striped b...

  10. Long-term cleaner fish presence affects growth of a coral reef fish.

    PubMed

    Clague, Gillian E; Cheney, Karen L; Goldizen, Anne W; McCormick, Mark I; Waldie, Peter A; Grutter, Alexandra S

    2011-12-23

    Cleaning behaviour is considered to be a classical example of mutualism. However, no studies, to our knowledge, have measured the benefits to clients in terms of growth. In the longest experimental study of its kind, over an 8 year period, cleaner fish Labroides dimidiatus were consistently removed from seven patch reefs (61-285 m(2)) and left undisturbed on nine control reefs, and the growth and parasite load of the damselfish Pomacentrus moluccensis determined. After 8 years, growth was reduced and parasitic copepod abundance was higher on fish from removal reefs compared with controls, but only in larger individuals. Behavioural observations revealed that P. moluccensis cleaned by L. dimidiatus were 27 per cent larger than nearby conspecifics. The selective cleaning by L. dimidiatus probably explains why only larger P. moluccensis individuals benefited from cleaning. This is the first demonstration, to our knowledge, that cleaners affect the growth rate of client individuals; a greater size for a given age should result in increased fecundity at a given time. The effect of the removal of so few small fish on the size of another fish species is unprecedented on coral reefs. PMID:21733872

  11. Damage segregation at fissioning may increase growth rates

    PubMed Central

    Evans, Steven N.; Steinsaltz, David

    2007-01-01

    A fissioning organism may purge unrepairable damage by bequeathing it preferentially to one of its daughters. Using the mathematical formalism of superprocesses, we propose a flexible class of analytically tractable models that allow quite general effects of damage on death rates and splitting rates and similarly general damage segregation mechanisms. We show that, in a suitable regime, the effects of randomness in damage segregation at fissioning are indistinguishable from those of randomness in the mechanism of damage accumulation during the organism’s lifetime. Moreover, the optimal population growth is achieved for a particular finite, non-zero level of combined randomness from these two sources. In particular, when damage accumulates deterministically, optimal population growth is achieved by a moderately unequal division of damage between the daughters, while too little or too much division is sub-optimal. Connections are drawn both to recent experimental results on inheritance of damage in protozoans, and to theories of aging and resource division between siblings. PMID:17442356

  12. A Comparison of Terrestrial and Kronian CMI growth rates

    NASA Astrophysics Data System (ADS)

    Mutel, R. L.; Menietti, J. D.; Gurnett, D. A.; Kurth, W. S.; Pickett, J. S.; Fazakerley, A. N.; Coates, A. J.; Arridge, C. S.; Lamy, L.; Cecconi, B.; Zarka, P. M.

    2009-12-01

    The Earth's auroral kilometric radiation (AKR) and Saturn's SKR are both thought to be driven by the electron cyclotron maser instability (CMI) mechanism. Recent in situ measurements of AKR intensities and electron distributions using Cluster WBD and PEACE instruments in the auroral acceleration region are compared with CMI growth rates to determine whether the distribution can account for the observed intensities. We compare these results to a similar coeval measurement of SKR intensities and electron distribution functions in the Kronian acceleration region using the RPWS and CAPS/EWS instruments. The terrestrial AKR appears to be driven by perpendicular velocity gradients, while the Kronian SKR is driven by parallel gradients resulting from a very intense, slightly spread parallel beam with a sharp low-energy edge. The measured k-vector orientations are also consistent with the dominance of the differing terms in the growth rate integral (significant parallel k-component in Kronian case). Kronian electron velocity distribution function showing strong parallel beam. This beam appears to drive the CMI instability.

  13. The Effect of Growth Rate on Interface Morphology

    NASA Technical Reports Server (NTRS)

    Trivedi, R.; Somboonsuk, K.

    1984-01-01

    Since significantly different solidification structures of a given alloy can be obtained by varying experimental growth rates, it is desirable to understand the basic factors which control the formation and stability of these microstructures when conditions are altered. Directional solidification experiments are described and the results obtained in metallic and transparent organic systems are presented. Emphasis is on the characteristics of dendritic structures obtained under different solidification conditions. Specifically, the effect of the growth rate on the primary dendritic spacing, the secondary dendrite spacing, and the dendrite tip radius is discussed. It is shown that significant changes in the primary spacing are observed when a dendrite to cellular transition takes place at lower velocities. It is found that the primary cellular spacing is much smaller than the primary dendrite spacing so that a maximum in the primary spacing occurs as a function of velocity at the dendrite-cellular transition. A theoretical model is also described which quantitatively explains various microstructural features of dendritic and cellular structures.

  14. Perspectives on massive coral growth rates in a changing ocean.

    PubMed

    Lough, Janice M; Cantin, Neal E

    2014-06-01

    The tropical ocean environment is changing at an unprecedented rate, with warming and severe tropical cyclones creating obvious impacts to coral reefs within the last few decades and projections of acidification raising concerns for the future of these iconic and economically important ecosystems. Documenting variability and detecting change in global and regional climate relies upon high-quality observational records of climate variables supplemented, prior to the mid-19th century, with reconstructions from various sources of proxy climate information. Here we review how annual density banding patterns that are recorded in the skeletons of massive reef-building corals have been used to document environmental change and impacts within coral reefs. Massive corals provide a historical perspective of continuous calcification processes that pre-date most ecological observations of coral reefs. High-density stress bands, abrupt declines in annual linear extension, and evidence of partial mortality within the skeletal growth record reveal signatures of catastrophic stress events that have recently been attributed to mass bleaching events caused by unprecedented thermal stress. Comparison of recent trends in annual calcification with century-scale baseline calcification rates reveals that the frequency of growth anomalies has increased since the late 1990s throughout most of the world's coral reef ecosystems. Continuous coral growth histories provide valuable retrospective information on the coral response to environmental change and the consequences of anthropogenic climate change. Co-ordinated efforts to synthesize and combine global calcification histories will greatly enhance our understanding of current calcification responses to a changing ocean. PMID:25070864

  15. Non-linear stochastic growth rates and redshift space distortions

    SciTech Connect

    Jennings, Elise; Jennings, David

    2015-04-09

    The linear growth rate is commonly defined through a simple deterministic relation between the velocity divergence and the matter overdensity in the linear regime. We introduce a formalism that extends this to a non-linear, stochastic relation between θ = ∇ ∙ v(x,t)/aH and δ. This provides a new phenomenological approach that examines the conditional mean <θ|δ>, together with the fluctuations of θ around this mean. We also measure these stochastic components using N-body simulations and find they are non-negative and increase with decreasing scale from ~10 per cent at k < 0.2 h Mpc-1 to 25 per cent at k ~ 0.45 h Mpc-1 at z = 0. Both the stochastic relation and non-linearity are more pronounced for haloes, M ≤ 5 × 1012 M h-1, compared to the dark matter at z = 0 and 1. Non-linear growth effects manifest themselves as a rotation of the mean <θ|δ> away from the linear theory prediction -fLTδ, where fLT is the linear growth rate. This rotation increases with wavenumber, k, and we show that it can be well-described by second-order Lagrangian perturbation theory (2LPT) fork < 0.1 h Mpc-1. Furthermore, the stochasticity in the θ – δ relation is not so simply described by 2LPT, and we discuss its impact on measurements of fLT from two-point statistics in redshift space. Furthermore, given that the relationship between δ and θ is stochastic and non-linear, this will have implications for the interpretation and precision of fLT extracted using models which assume a linear, deterministic expression.

  16. Non-linear stochastic growth rates and redshift space distortions

    DOE PAGES

    Jennings, Elise; Jennings, David

    2015-04-09

    The linear growth rate is commonly defined through a simple deterministic relation between the velocity divergence and the matter overdensity in the linear regime. We introduce a formalism that extends this to a non-linear, stochastic relation between θ = ∇ ∙ v(x,t)/aH and δ. This provides a new phenomenological approach that examines the conditional mean <θ|δ>, together with the fluctuations of θ around this mean. We also measure these stochastic components using N-body simulations and find they are non-negative and increase with decreasing scale from ~10 per cent at k < 0.2 h Mpc-1 to 25 per cent at kmore » ~ 0.45 h Mpc-1 at z = 0. Both the stochastic relation and non-linearity are more pronounced for haloes, M ≤ 5 × 1012 M⊙ h-1, compared to the dark matter at z = 0 and 1. Non-linear growth effects manifest themselves as a rotation of the mean <θ|δ> away from the linear theory prediction -fLTδ, where fLT is the linear growth rate. This rotation increases with wavenumber, k, and we show that it can be well-described by second-order Lagrangian perturbation theory (2LPT) fork < 0.1 h Mpc-1. Furthermore, the stochasticity in the θ – δ relation is not so simply described by 2LPT, and we discuss its impact on measurements of fLT from two-point statistics in redshift space. Furthermore, given that the relationship between δ and θ is stochastic and non-linear, this will have implications for the interpretation and precision of fLT extracted using models which assume a linear, deterministic expression.« less

  17. Words That Fascinate the Listener: Predicting Affective Ratings of On-Line Lectures

    ERIC Educational Resources Information Center

    Weninger, Felix; Staudt, Pascal; Schuller, Björn

    2013-01-01

    In a large scale study on 843 transcripts of Technology, Entertainment and Design (TED) talks, the authors address the relation between word usage and categorical affective ratings of lectures by a large group of internet users. Users rated the lectures by assigning one or more predefined tags which relate to the affective state evoked in the…

  18. Effects of Affective Stimuli Mode on Eye Blink Rate and Anxiety

    ERIC Educational Resources Information Center

    Weiner, Elliot A.; Concepcion, Paul

    1975-01-01

    This study investigated the physiological responses to affective visual and auditory stimuli with eye-blink rate (EBR) as the physiological indicator and examined the relationship between this response and subjective anxiety-level ratings by means of Zuckerman and Lubin's Multiple Affect Adjective Check-list (MACCL). (Author)

  19. Phasic temperature change patterns affect growth and tuberization in potatoes

    SciTech Connect

    Cao, W.; Tibbitts, T.W. . Dept. of Horticulture)

    1994-07-01

    This study determined the response of potato (Solanum tuberosum L., cv. Norland) plants to various patterns of air temperature changes over different growth periods. In each of two experiments under controlled environments, eight treatments of temperature changes were carried out in two growth rooms maintained at 17 and 22 C and a constant vapor pressure deficit of 0.60 kPa and 14-hour photoperiod. Plants were grown for 63 days after transplanting of tissue culture plantlets in 20-liter pots containing peat-vermiculite mix. Temperature changes were imposed on days 21 and 42, which were essentially at the beginning of tuber initiation and tuber enlargement, respectively, for this cultivar. Plants were moved between two temperature rooms to obtain eight temperature change patterns: 17-17-17, 17-17-22, 17-22-17, 22-17-17, 17-22-22, 22-17-22, 22-22-17, and 22-22-22C over three 21-day growth periods. At harvest on day 63, total plant dry weight was higher for the treatments beginning with 22 C than for those beginning with 17C, with highest biomass obtained at 22-22-17 and 22-17-17C. Shoot dry weight increased with temperature increased from 17-17-17 to 22-22-22C during the three growth periods. Tuber dry weight was highest with 22-17-17C, and lowest with 17-17-22 and 17-22-22C. With 22-17-17C, both dry weights of stolons and roots were lowest. Total tuber number and number of small tubers were highest with 17-17-17 and 17-17-22C, and lowest with 17-22-22 and 22-22-22C, whereas number of medium tubers was highest with 22-17-22C, and number of large tubers was highest with 22-17-17C. This study indicates that tuber development of potatoes is optimized with a phasic pattern of high temperature during early growth and low temperature during later growth.

  20. Growth rate predicts mortality of Abies concolor in both burned and unburned stands

    USGS Publications Warehouse

    van Mantgem, Phillip J.; Stephenson, Nathan L.; Mutch, Linda S.; Johnson, Veronica G.; Esperanza, Annie M.; Parsons, David J.

    2003-01-01

    Tree mortality is often the result of both long-term and short-term stress. Growth rate, an indicator of long-term stress, is often used to estimate probability of death in unburned stands. In contrast, probability of death in burned stands is modeled as a function of short-term disturbance severity. We sought to narrow this conceptual gap by determining (i) whether growth rate, in addition to crown scorch, is a predictor of mortality in burned stands and (ii) whether a single, simple model could predict tree death in both burned and unburned stands. Observations of 2622 unburned and 688 burned Abies concolor (Gord. & Glend.) Lindl. (white fir) in the Sierra Nevada of California, U.S.A., indicated that growth rate was a significant predictor of mortality in the unburned stands, while both crown scorch and radial growth were significant predictors of mortality in the burned stands. Applying the burned stand model to unburned stands resulted in an overestimation of the unburned stand mortality rate. While failing to create a general model of tree death for A. concolor, our findings underscore the idea that similar processes may affect mortality in disturbed and undisturbed stands.

  1. Analysis of the dynamic and steady-state responses of growth rate and turgor pressure to changes in cell parameters.

    PubMed

    Cosgrove, D J

    1981-12-01

    The physical analysis of plant cell enlargment is extended to show the dependence of turgor pressure and growth rate under steady-state conditions on the parameters which govern cell wall extension and water transport in growing cells and tissues, and to show the dynamic responses of turgor and growth rate to instantaneous changes in one of these parameters. The analysis is based on the fact that growth requires simultaneous water uptake and irreversible wall expansion. It shows that when a growing cell is perturbed from its steady-state growth rate, it will approach the steady-state rate with exponential kinetics. The half-time of the transient adjustment depends on the biophysical parameters governing both water transport and irreversible wall expansion. When wall extensibility is small compared to hydraulic conductance, the growth rate is controlled by the yielding properties of the cell wall, while the half-time for changes in growth rate is controlled by the water transport parameters. The reverse situation occurs when hydraulic conductance is lower than wall extensibility. The analysis also shows explicitly that turgor pressure is tightly coupled with growth rate when growth is controlled by both water transport and wall yielding parameters.In growing tissue where the resistance to water flow is distributed throughout the tissue, the physical analysis is more complicated because gradients in water potential (and hence turgor pressure) are required to sustain high growth rates. However, the analysis of growth in such tissues shows that the turgor and time-course relations are similar to that in single cells. These turgor and time-course relations provide experimentally useful ways for determining (a) whether growth is limited by water uptake, and (b) whether an agent which alters the growth rate does so by affecting the water transport or wall yielding properties or both.

  2. Climate forcing growth rates: doubling down on our Faustian bargain

    NASA Astrophysics Data System (ADS)

    Hansen, James; Kharecha, Pushker; Sato, Makiko

    2013-03-01

    Rahmstorf et al 's (2012) conclusion that observed climate change is comparable to projections, and in some cases exceeds projections, allows further inferences if we can quantify changing climate forcings and compare those with projections. The largest climate forcing is caused by well-mixed long-lived greenhouse gases. Here we illustrate trends of these gases and their climate forcings, and we discuss implications. We focus on quantities that are accurately measured, and we include comparison with fixed scenarios, which helps reduce common misimpressions about how climate forcings are changing. Annual fossil fuel CO2 emissions have shot up in the past decade at about 3% yr-1, double the rate of the prior three decades (figure 1). The growth rate falls above the range of the IPCC (2001) 'Marker' scenarios, although emissions are still within the entire range considered by the IPCC SRES (2000). The surge in emissions is due to increased coal use (blue curve in figure 1), which now accounts for more than 40% of fossil fuel CO2 emissions. Figure 1. Figure 1. CO2 annual emissions from fossil fuel use and cement manufacture, an update of figure 16 of Hansen (2003) using data of British Petroleum (BP 2012) concatenated with data of Boden et al (2012). The resulting annual increase of atmospheric CO2 (12-month running mean) has grown from less than 1 ppm yr-1 in the early 1960s to an average ~2 ppm yr-1 in the past decade (figure 2). Although CO2 measurements were not made at sufficient locations prior to the early 1980s to calculate the global mean change, the close match of global and Mauna Loa data for later years suggests that Mauna Loa data provide a good approximation of global change (figure 2), thus allowing a useful estimate of annual global change beginning with the initiation of Mauna Loa measurements in 1958 by Keeling et al (1973). Figure 2. Figure 2. Annual increase of CO2 based on data from the NOAA Earth System Research Laboratory (ESRL 2012). CO2 change

  3. Growth and aggressiveness factors affecting Monilinia spp. survival peaches.

    PubMed

    Villarino, M; Melgarejo, P; De Cal, A

    2016-05-01

    Brown rot of stone fruit is caused by three species of Monilinia, Monilinia laxa, M. fructigena, and M. fructicola. Eleven components of 20 different isolates of each of the three Monilinia species were analysed to determine distinct aggressiveness and growth characteristics among the three fungi. M. fructicola showed the greatest lesion diameter, and the lowest incubation and latency period on fruit postharvest, however isolates of M. fructigena exhibited less aggressiveness components. Five growth characteristics of M. fructicola could be used to distinguish M. fructicola from the other two species. The dendrogram generated from only the presence of sclerotia and lesion length on infected fruit separated the 60 isolates into two clusters (r=0.93). One cluster was composed of the M. laxa and M. fructigena isolates and the other cluster comprised the M. fructicola isolates. However, the dendrogram generated based on the presence of stromata and sclerotia in the same colony of the three species when they were grown on potato dextrose agar, and the lesion diameter on fruit infected with each species separated the 60 isolates into three clusters (r=0.81). Each cluster comprised the isolates of each of three Monilinia spp. We discussed the effect of M. fructicola growth and aggressiveness differences on the displacement of M. laxa and M. fructigena by M. fructicola recorded in Spanish peach orchards and their effect on brown rot at postharvest.

  4. Organic Matter Loading Affects Lodgepole Pine Seedling Growth

    NASA Astrophysics Data System (ADS)

    Wei, Xiaohua; Li, Qinglin; Waterhouse, M. J.; Armleder, H. M.

    2012-06-01

    Organic matter plays important roles in returning nutrients to the soil, maintaining forest productivity and creating habitats in forest ecosystems. Forest biomass is in increasing demand for energy production, and organic matter has been considered as a potential supply. Thus, an important management question is how much organic matter should be retained after forest harvesting to maintain forest productivity. To address this question, an experimental trial was established in 1996 to evaluate the responses of lodgepole pine seedling growth to organic matter loading treatments. Four organic matter loading treatments were randomly assigned to each of four homogeneous pine sites: removal of all organic matter on the forest floor, organic matter loading quantity similar to whole-tree-harvesting residuals left on site, organic matter loading quantity similar to stem-only-harvesting residuals, and organic matter loading quantity more similar to what would be found in disease- or insect-killed stands. Our 10-year data showed that height and diameter had 29 and 35 % increase, respectively, comparing the treatment with the most organic matter loading to the treatment with the least organic matter loading. The positive response of seedling growth to organic matter loading may be associated with nutrients and/or microclimate change caused by organic matter, and requires further study. The dynamic response of seedling growth to organic matter loading treatments highlights the importance of long-term studies. Implications of those results on organic matter management are discussed in the context of forest productivity sustainability.

  5. Growth and aggressiveness factors affecting Monilinia spp. survival peaches.

    PubMed

    Villarino, M; Melgarejo, P; De Cal, A

    2016-06-16

    Brown rot of stone fruit is caused by three species of Monilinia, Monilinia laxa, M. fructigena, and M. fructicola. Eleven components of 20 different isolates of each of the three Monilinia species were analyzed to determine distinct aggressiveness and growth characteristics among the three fungi. M. fructicola showed the greatest lesion diameter, and the lowest incubation and latency period on fruit postharvest, however isolates of M. fructigena exhibited less aggressiveness components. Five growth characteristics of M. fructicola could be used to distinguish M. fructicola from the other two species. The dendrogram generated from only the presence of sclerotia and lesion length on infected fruit separated the 60 isolates into two clusters (r=0.93). One cluster was composed of the M. laxa and M. fructigena isolates and the other cluster comprised the M. fructicola isolates. However, the dendrogram generated based on the presence of stromata and sclerotia in the same colony of the three species when they were grown on potato dextrose agar, and the lesion diameter on fruit infected with each species separated the 60 isolates into three clusters (r=0.81). Each cluster comprised the isolates of each of three Monilinia spp. We discussed the effect of M. fructicola growth and aggressiveness differences on the displacement of M. laxa and M. fructigena by M. fructicola recorded in Spanish peach orchards and their effect on brown rot at postharvest. PMID:27043383

  6. Growth in body size affects rotational performance in women's gymnastics.

    PubMed

    Ackland, Timothy; Elliott, Bruce; Richards, Joanne

    2003-07-01

    National and state representative female gymnasts (n = 37), aged initially between 10 and 12 years, completed a mixed longitudinal study over 3.3 years, to investigate the effect of body size on gymnastic performance. Subjects were tested at four-monthly intervals on a battery of measures including structural growth, strength and gymnastic performance. The group were divided into 'high growers' and 'low growers' based on height (> 18 cm or < 14 cm/37 months, respectively) and body mass (> 15 kg or < 12 kg/37 months, respectively) for comparative purposes. Development of gymnastic performance was assessed through generic skills (front and back rotations, a twisting jump and a V-sit action) and a vertical jump for maximum height. The results show that the smaller gymnast, with a high strength to mass ratio, has greater potential for performing skills involving whole-body rotations. Larger gymnasts, while able to produce more power and greater angular momentum, could not match the performance of the smaller ones. The magnitude of growth experienced by the gymnast over this period has a varying effect on performance. While some activities were greatly influenced by rapid increases in whole-body moment of inertia (e.g. back rotation), performance on others like the front rotation and vertical jump, appeared partly immune to the physical and mechanical changes associated with growth. PMID:14737925

  7. Growth and aggressiveness factors affecting Monilinia spp. survival peaches.

    PubMed

    Villarino, M; Melgarejo, P; De Cal, A

    2016-05-01

    Brown rot of stone fruit is caused by three species of Monilinia, Monilinia laxa, M. fructigena, and M. fructicola. Eleven components of 20 different isolates of each of the three Monilinia species were analysed to determine distinct aggressiveness and growth characteristics among the three fungi. M. fructicola showed the greatest lesion diameter, and the lowest incubation and latency period on fruit postharvest, however isolates of M. fructigena exhibited less aggressiveness components. Five growth characteristics of M. fructicola could be used to distinguish M. fructicola from the other two species. The dendrogram generated from only the presence of sclerotia and lesion length on infected fruit separated the 60 isolates into two clusters (r=0.93). One cluster was composed of the M. laxa and M. fructigena isolates and the other cluster comprised the M. fructicola isolates. However, the dendrogram generated based on the presence of stromata and sclerotia in the same colony of the three species when they were grown on potato dextrose agar, and the lesion diameter on fruit infected with each species separated the 60 isolates into three clusters (r=0.81). Each cluster comprised the isolates of each of three Monilinia spp. We discussed the effect of M. fructicola growth and aggressiveness differences on the displacement of M. laxa and M. fructigena by M. fructicola recorded in Spanish peach orchards and their effect on brown rot at postharvest. PMID:26918325

  8. Protein crystal growth rates are face-specifically modified by structurally related contaminants

    NASA Astrophysics Data System (ADS)

    Hirschler, Joachim; Fontecilla-Camps, Juan Carlos

    1997-02-01

    Growth rates of turkey egg-white lysozyme (TEWL) crystal faces have been measured in uncontaminated solutions as well as in solutions contaminated by the homologous hen egg-white lysozyme (HEWL). Comparison of growth rates from uncontaminated and contaminated solutions shows that the growth rate of the {112} faces drops significantly in the presence of the contaminant, whereas the growth rate of the {110} faces does not change. This demonstrates that HEWL acts specifically on the growth process of the {112} faces.

  9. Growth trajectory influences temperature preference in fish through an effect on metabolic rate

    PubMed Central

    Killen, Shaun S

    2014-01-01

    Most animals experience temperature variations as they move through the environment. For ectotherms, in particular, temperature has a strong influence on habitat choice. While well studied at the species level, less is known about factors affecting the preferred temperature of individuals; especially lacking is information on how physiological traits are linked to thermal preference and whether such relationships are affected by factors such feeding history and growth trajectory. This study examined these issues in the common minnow Phoxinus phoxinus, to determine the extent to which feeding history, standard metabolic rate (SMR) and aerobic scope (AS), interact to affect temperature preference. Individuals were either: 1) food deprived (FD) for 21 days, then fed ad libitum for the next 74 days; or 2) fed ad libitum throughout the entire period. All animals were then allowed to select preferred temperatures using a shuttle-box, and then measured for SMR and AS at 10 °C, estimated by rates of oxygen uptake. Activity within the shuttle-box under a constant temperature regime was also measured. In both FD and control fish, SMR was negatively correlated with preferred temperature. The SMR of the FD fish was increased compared with the controls, probably due to the effects of compensatory growth, and so these growth-compensated fish preferred temperatures that were on average 2·85 °C cooler than controls fed a maintenance ration throughout the study. Fish experiencing compensatory growth also displayed a large reduction in activity. In growth-compensated fish and controls, activity measured at 10 °C was positively correlated with preferred temperature. Individual fish prefer temperatures that vary predictably with SMR and activity level, which are both plastic in response to feeding history and growth trajectories. Cooler temperatures probably allow individuals to reduce maintenance costs and divert more energy towards growth. A reduction in SMR at cooler

  10. Growth trajectory influences temperature preference in fish through an effect on metabolic rate.

    PubMed

    Killen, Shaun S

    2014-11-01

    Most animals experience temperature variations as they move through the environment. For ectotherms, in particular, temperature has a strong influence on habitat choice. While well studied at the species level, less is known about factors affecting the preferred temperature of individuals; especially lacking is information on how physiological traits are linked to thermal preference and whether such relationships are affected by factors such feeding history and growth trajectory. This study examined these issues in the common minnow Phoxinus phoxinus, to determine the extent to which feeding history, standard metabolic rate (SMR) and aerobic scope (AS), interact to affect temperature preference. Individuals were either: 1) food deprived (FD) for 21 days, then fed ad libitum for the next 74 days; or 2) fed ad libitum throughout the entire period. All animals were then allowed to select preferred temperatures using a shuttle-box, and then measured for SMR and AS at 10 °C, estimated by rates of oxygen uptake. Activity within the shuttle-box under a constant temperature regime was also measured. In both FD and control fish, SMR was negatively correlated with preferred temperature. The SMR of the FD fish was increased compared with the controls, probably due to the effects of compensatory growth, and so these growth-compensated fish preferred temperatures that were on average 2.85 °C cooler than controls fed a maintenance ration throughout the study. Fish experiencing compensatory growth also displayed a large reduction in activity. In growth-compensated fish and controls, activity measured at 10 °C was positively correlated with preferred temperature. Individual fish prefer temperatures that vary predictably with SMR and activity level, which are both plastic in response to feeding history and growth trajectories. Cooler temperatures probably allow individuals to reduce maintenance costs and divert more energy towards growth. A reduction in SMR at cooler

  11. Extended Simulations of Graphene Growth with Updated Rate Coefficients

    SciTech Connect

    Whitesides, R; You, X; Frenklach, M

    2010-03-18

    New simulations of graphene growth in flame environments are presented. The simulations employ a kinetic Monte Carlo (KMC) algorithm coupled to molecular mechanics (MM) geometry optimization to track individual graphenic species as they evolve. Focus is given to incorporation of five-member rings and resulting curvature and edge defects. The model code has been re-written to be more computationally efficient enabling a larger set of simulations to be run, decreasing stochastic fluctuations in the averaged results. The model also includes updated rate coefficients for graphene edge reactions recently published in the literature. The new simulations are compared to results from the previous model as well as to hydrogen to carbon ratios recorded in experiment and calculated with alternate models.

  12. Growth rate inhibition of phytopathogenic fungi by characterized chitosans

    PubMed Central

    Oliveira Junior, Enio N.; Gueddari, Nour E. El; Moerschbacher, Bruno. M.; Franco, Telma T.

    2012-01-01

    The inhibitory effects of fifteen chitosans with different degrees of polymerization (DP) and different degrees of acetylation (FA) on the growth rates (GR) of four phytopathogenic fungi (Alternaria alternata, Botrytis cinerea, Penicillium expansum, and Rhizopus stolonifer) were examined using a 96-well microtiter plate and a microplate reader. The minimum inhibitory concentrations (MICs) of the chitosans ranged from 100 μg ×mL-1 to 1,000 μg ×mL-1 depending on the fungus tested and the DP and FA of the chitosan. The antifungal activity of the chitosans increased with decreasing FA. Chitosans with low FA and high DP showed the highest inhibitory activity against all four fungi. P. expansum and B. cinerea were relatively less susceptible while A. alternata and R. stolonifer were relatively more sensitive to the chitosan polymers. Scanning electron microscopy of fungi grown on culture media amended with chitosan revealed morphological changes. PMID:24031893

  13. Growth rate inhibition of phytopathogenic fungi by characterized chitosans.

    PubMed

    Oliveira Junior, Enio N; Gueddari, Nour E El; Moerschbacher, Bruno M; Franco, Telma T

    2012-04-01

    The inhibitory effects of fifteen chitosans with different degrees of polymerization (DP) and different degrees of acetylation (FA) on the growth rates (GR) of four phytopathogenic fungi (Alternaria alternata, Botrytis cinerea, Penicillium expansum, and Rhizopus stolonifer) were examined using a 96-well microtiter plate and a microplate reader. The minimum inhibitory concentrations (MICs) of the chitosans ranged from 100 μg ×mL(-1) to 1,000 μg ×mL(-1) depending on the fungus tested and the DP and FA of the chitosan. The antifungal activity of the chitosans increased with decreasing FA. Chitosans with low FA and high DP showed the highest inhibitory activity against all four fungi. P. expansum and B. cinerea were relatively less susceptible while A. alternata and R. stolonifer were relatively more sensitive to the chitosan polymers. Scanning electron microscopy of fungi grown on culture media amended with chitosan revealed morphological changes.

  14. Intrauterine growth restriction affects the preterm infant's hippocampus.

    PubMed

    Lodygensky, Gregory A; Seghier, Mohammed L; Warfield, Simon K; Tolsa, Cristina Borradori; Sizonenko, Stephane; Lazeyras, François; Hüppi, Petra S

    2008-04-01

    The hippocampus is known to be vulnerable to hypoxia, stress, and undernutrition, all likely to be present in fetal intrauterine growth restriction (IUGR). The effect of IUGR in preterm infants on the hippocampus was studied using 3D magnetic resonance imaging at term-equivalent age Thirteen preterm infants born with IUGR after placental insufficiency were compared with 13 infants with normal intrauterine growth age matched for gestational age. The hippocampal structural differences were defined using voxel-based morphometry and manual segmentation. The specific neurobehavioral function was evaluated by the Assessment of Preterm Infants' Behavior at term and at 24 mo of corrected age by a Bayley Scales of Infant and Toddler Development. Voxel-based morphometry detected significant gray matter volume differences in the hippocampus between the two groups. This finding was confirmed by manual segmentation of the hippocampus with a reduction of hippocampal volume after IUGR. The hippocampal volume reduction was further associated with functional behavioral differences at term-equivalent age in all six subdomains of the Assessment of Preterm Infants' Behavior but not at 24 mo of corrected age. We conclude that hippocampal development in IUGR is altered and might result from a combination of maternal corticosteroid hormone exposure, hypoxemia, and micronutrient deficiency. PMID:18356754

  15. Age, growth rates, and paleoclimate studies of deep sea corals

    USGS Publications Warehouse

    Prouty, Nancy G; Roark, E. Brendan; Andrews, Allen; Robinson, Laura; Hill, Tessa; Sherwood, Owen; Williams, Branwen; Guilderson, Thomas P.; Fallon, Stewart

    2015-01-01

    Deep-water corals are some of the slowest growing, longest-lived skeletal accreting marine organisms. These habitat-forming species support diverse faunal assemblages that include commercially and ecologically important organisms. Therefore, effective management and conservation strategies for deep-sea corals can be informed by precise and accurate age, growth rate, and lifespan characteristics for proper assessment of vulnerability and recovery from perturbations. This is especially true for the small number of commercially valuable, and potentially endangered, species that are part of the black and precious coral fisheries (Tsounis et al. 2010). In addition to evaluating time scales of recovery from disturbance or exploitation, accurate age and growth estimates are essential for understanding the life history and ecology of these habitat-forming corals. Given that longevity is a key factor for population maintenance and fishery sustainability, partly due to limited and complex genetic flow among coral populations separated by great distances, accurate age structure for these deep-sea coral communities is essential for proper, long-term resource management.

  16. The effect of differential growth rates across plants on spectral predictions of physiological parameters.

    PubMed

    Rapaport, Tal; Hochberg, Uri; Rachmilevitch, Shimon; Karnieli, Arnon

    2014-01-01

    Leaves of various ages and positions in a plant's canopy can present distinct physiological, morphological and anatomical characteristics, leading to complexities in selecting a single leaf for spectral representation of an entire plant. A fortiori, as growth rates between canopies differ, spectral-based comparisons across multiple plants--often based on leaves' position but not age--becomes an even more challenging mission. This study explores the effect of differential growth rates on the reflectance variability between leaves of different canopies, and its implication on physiological predictions made by widely-used spectral indices. Two distinct irrigation treatments were applied for one month, in order to trigger the formation of different growth rates between two groups of grapevines. Throughout the experiment, the plants were physiologically and morphologically monitored, while leaves from every part of their canopies were spectrally and histologically sampled. As the control vines were constantly developing new leaves, the water deficit plants were experiencing growth inhibition, resulting in leaves of different age at similar nodal position across the treatments. This modification of the age-position correlation was characterized by a near infrared reflectance difference between younger and older leaves, which was found to be exponentially correlated (R(2) = 0.98) to the age-dependent area of intercellular air spaces within the spongy parenchyma. Overall, the foliage of the control plant became more spectrally variable, creating complications for intra- and inter-treatment leaf-based comparisons. Of the derived indices, the Structure-Insensitive Pigment Index (SIPI) was found indifferent to the age-position effect, allowing the treatments to be compared at any nodal position, while a Normalized Difference Vegetation Index (NDVI)-based stomatal conductance prediction was substantially affected by differential growth rates. As various biotic and abiotic

  17. The Effect of Differential Growth Rates across Plants on Spectral Predictions of Physiological Parameters

    PubMed Central

    Rapaport, Tal; Hochberg, Uri; Rachmilevitch, Shimon; Karnieli, Arnon

    2014-01-01

    Leaves of various ages and positions in a plant's canopy can present distinct physiological, morphological and anatomical characteristics, leading to complexities in selecting a single leaf for spectral representation of an entire plant. A fortiori, as growth rates between canopies differ, spectral-based comparisons across multiple plants – often based on leaves' position but not age – becomes an even more challenging mission. This study explores the effect of differential growth rates on the reflectance variability between leaves of different canopies, and its implication on physiological predictions made by widely-used spectral indices. Two distinct irrigation treatments were applied for one month, in order to trigger the formation of different growth rates between two groups of grapevines. Throughout the experiment, the plants were physiologically and morphologically monitored, while leaves from every part of their canopies were spectrally and histologically sampled. As the control vines were constantly developing new leaves, the water deficit plants were experiencing growth inhibition, resulting in leaves of different age at similar nodal position across the treatments. This modification of the age-position correlation was characterized by a near infrared reflectance difference between younger and older leaves, which was found to be exponentially correlated (R2 = 0.98) to the age-dependent area of intercellular air spaces within the spongy parenchyma. Overall, the foliage of the control plant became more spectrally variable, creating complications for intra- and inter-treatment leaf-based comparisons. Of the derived indices, the Structure-Insensitive Pigment Index (SIPI) was found indifferent to the age-position effect, allowing the treatments to be compared at any nodal position, while a Normalized Difference Vegetation Index (NDVI)-based stomatal conductance prediction was substantially affected by differential growth rates. As various biotic and

  18. Let's not be indifferent about neutrality: Neutral ratings in the International Affective Picture System (IAPS) mask mixed affective responses.

    PubMed

    Schneider, Iris K; Veenstra, Lotte; van Harreveld, Frenk; Schwarz, Norbert; Koole, Sander L

    2016-06-01

    The International Affective Picture System (IAPS) is a picture set used by researchers to select pictures that have been prerated on valence. Researchers rely on the ratings in the IAPS to accurately reflect the degree to which the pictures elicit affective responses. Here we show that this may not always be a safe assumption. More specifically, the scale used to measure valence in the IAPS ranges from positive to negative, implying that positive and negative feelings are end-points of the same construct. This makes interpretation of midpoint, or neutral ratings, especially problematic because it is impossible to tell whether these ratings are the result of neutral, or of mixed feelings. In other words, neutral ratings may not be as neutral as researchers assume them to be. Investigating this, in this work we show that pictures that seem neutral according to the valence ratings in the IAPS indeed vary in levels of ambivalence they elicit. Furthermore, the experience of ambivalence in response to these pictures is predictive of the arousal that people report feeling when viewing these pictures. These findings are of particular importance because neutrality differs from ambivalence in its specific psychological consequences, and by relying on seemingly neutral valance ratings, researchers may unwillingly introduce these consequences into their research design, undermining their level of experimental control. (PsycINFO Database Record

  19. Selective consequences of catastrophes for growth rates in a stream-dwelling salmonid.

    PubMed

    Vincenzi, Simone; Crivelli, Alain J; Giske, Jarl; Satterthwaite, William H; Mangel, Marc

    2012-02-01

    Optimal life histories in a fluctuating environment are likely to differ from those that are optimal in a constant environment, but we have little understanding of the consequences of bounded fluctuations versus episodic massive mortality events. Catastrophic disturbances, such as floods, droughts, landslides and fires, substantially alter the population dynamics of affected populations, but little has been done to investigate how catastrophes may act as a selective agent for life-history traits. We use an individual-based model of population dynamics of the stream-dwelling salmonid marble trout (Salmo marmoratus) to investigate how trade-offs between the growth and mortality of individuals and density-dependent body growth can lead to the maintenance of a wide or narrow range of individual variation in body growth rates in environments that are constant (i.e., only demographic stochasticity), variable (i.e., environmental stochasticity), or variable with catastrophic events that cause massive mortalities (e.g., flash floods). We find that occasional episodes of massive mortality can substantially reduce persistent variability in individual growth rates. Lowering the population density reduces density dependence and allows for higher fitness of more opportunistic strategies (rapid growth and early maturation) during the recovery period.

  20. In situ evidence for chirality-dependent growth rates of individual carbon nanotubes

    NASA Astrophysics Data System (ADS)

    Rao, Rahul; Liptak, David; Cherukuri, Tonya; Yakobson, Boris I.; Maruyama, Benji

    2012-03-01

    Chiral-selective growth of single-walled carbon nanotubes (SWNTs) remains a great challenge that hinders their use in applications such as electronics and medicine. Recent experimental and theoretical reports have begun to address this problem by suggesting that selectivity may be achieved during nucleation by changing the catalyst composition or structure. Nevertheless, to establish a rational basis for chiral-selective synthesis, the underlying mechanisms governing nucleation, growth, and termination of SWNTs must be better understood. To this end, we report the first measurements of growth rates of individual SWNTs through in situ Raman spectroscopy and correlate them with their chiral angles. Our results show that the growth rates are directly proportional to the chiral angles, in agreement with recent theoretical predictions. Importantly, the evidence singles out the growth stage as responsible for the chiral distribution—distinct from nucleation and termination which might also affect the final product distribution. Our results suggest a route to chiral-selective synthesis of SWNTs through rational synthetic design strategies based on kinetic control.

  1. Specific ion effects on the growth rates of Staphylococcus aureus and Pseudomonas aeruginosa

    NASA Astrophysics Data System (ADS)

    Lo Nostro, Pierandrea; Ninham, Barry W.; Lo Nostro, Antonella; Pesavento, Giovanna; Fratoni, Laura; Baglioni, Piero

    2005-03-01

    Motivated by recent advances in the physical and chemical basis of the Hofmeister effect, we measured the rate cell growth of S. aureus—a halophilic pathogenic bacterium—and of P. aeruginosa, an opportunistic pathogen, in the presence of different aqueous salt solutions at different concentrations (0.2, 0.6 and 0.9 M). Microorganism growth rates depend strongly on the kind of anion in the growth medium. In the case of S. aureus, chloride provides a favorable growth medium, while both kosmotropes (water structure makers) and chaotropes (water structure breakers) reduce the microorganism growth. In the case of P. aeruginosa, all ions affect adversely the bacterial survival. In both cases, the trends parallel the specific ion, or Hofmeister, sequences observed in a wide range of physico-chemical systems. The correspondence with specific ion effect obtained in other studies, on the activities of a DNA restriction enzyme, of horseradish peroxidase, and of Lipase A (Aspergillus niger) is particularly striking. This work provides compelling evidence for Hofmeister effects, physical chemistry in action, in these organisms.

  2. Rates of Root and Organism Growth, Soil Conditions, and Temporal and Spatial Development of the Rhizosphere

    PubMed Central

    WATT, MICHELLE; SILK, WENDY K.; PASSIOURA, JOHN B.

    2006-01-01

    • Background Roots growing in soil encounter physical, chemical and biological environments that influence their rhizospheres and affect plant growth. Exudates from roots can stimulate or inhibit soil organisms that may release nutrients, infect the root, or modify plant growth via signals. These rhizosphere processes are poorly understood in field conditions. • Scope and Aims We characterize roots and their rhizospheres and rates of growth in units of distance and time so that interactions with soil organisms can be better understood in field conditions. We review: (1) distances between components of the soil, including dead roots remnant from previous plants, and the distances between new roots, their rhizospheres and soil components; (2) characteristic times (distance2/diffusivity) for solutes to travel distances between roots and responsive soil organisms; (3) rates of movement and growth of soil organisms; (4) rates of extension of roots, and how these relate to the rates of anatomical and biochemical ageing of root tissues and the development of the rhizosphere within the soil profile; and (5) numbers of micro-organisms in the rhizosphere and the dependence on the site of attachment to the growing tip. We consider temporal and spatial variation within the rhizosphere to understand the distribution of bacteria and fungi on roots in hard, unploughed soil, and the activities of organisms in the overlapping rhizospheres of living and dead roots clustered in gaps in most field soils. • Conclusions Rhizosphere distances, characteristic times for solute diffusion, and rates of root and organism growth must be considered to understand rhizosphere development. Many values used in our analysis were estimates. The paucity of reliable data underlines the rudimentary state of our knowledge of root–organism interactions in the field. PMID:16551700

  3. Formaldehyde exposure affects growth and metabolism of common bean

    SciTech Connect

    Mutters, R.G.; Madore, M. ); Bytnerowicz, A. )

    1993-01-01

    Recent state and federal directives have slated a substantial increase in the use of methanol as an alternative to gasoline in both fleet and private vehicles in the coming decade. The incomplete combustion of methanol produces formaldehyde vapor, and catalytic converter technology that completely oxidizes formaldehyde has yet to be developed. The approach of this study was to use a range of methanol concentrations encompassing levels currently found or that may occur in the future in the ambient air of some heavily polluted areas to test the potential phytotoxicity of formaldehyde. The study had the following objectives: (1) design and build a formaldehyde vapor generator with sufficient capacity for long-term plant fumigations; (2) determine growth response of common bean to formaldehyde; (3) evaluate physiological and biochemical changes of bean plants associated with formaldehyde exposures. 20 refs., 2 figs., 2 tabs.

  4. Nitrogen deficiency inhibits leaf blade growth in Lolium perenne by increasing cell cycle duration and decreasing mitotic and post-mitotic growth rates.

    PubMed

    Kavanová, Monika; Lattanzi, Fernando Alfredo; Schnyder, Hans

    2008-06-01

    Nitrogen deficiency severely inhibits leaf growth. This response was analysed at the cellular level by growing Lolium perenne L. under 7.5 mM (high) or 1 mM (low) nitrate supply, and performing a kinematic analysis to assess the effect of nitrogen status on cell proliferation and cell growth in the leaf blade epidermis. Low nitrogen supply reduced leaf elongation rate (LER) by 43% through a similar decrease in the cell production rate and final cell length. The former was entirely because of a decreased average cell division rate (0.023 versus 0.032 h(-1)) and thus longer cell cycle duration (30 versus 22 h). Nitrogen status did not affect the number of division cycles of the initial cell's progeny (5.7), and accordingly the meristematic cell number (53). Meristematic cell length was unaffected by nitrogen deficiency, implying that the division and mitotic growth rates were equally impaired. The shorter mature cell length arose from a considerably reduced post-mitotic growth rate (0.033 versus 0.049 h(-1)). But, nitrogen stress did not affect the position where elongation stopped, and increased cell elongation duration. In conclusion, nitrogen deficiency limited leaf growth by increasing the cell cycle duration and decreasing mitotic and post-mitotic elongation rates, delaying cell maturation.

  5. L-Carnosine Affects the Growth of Saccharomyces cerevisiae in a Metabolism-Dependent Manner

    PubMed Central

    Cartwright, Stephanie P.; Bill, Roslyn M.; Hipkiss, Alan R.

    2012-01-01

    The dipeptide L-carnosine (β-alanyl-L-histidine) has been described as enigmatic: it inhibits growth of cancer cells but delays senescence in cultured human fibroblasts and extends the lifespan of male fruit flies. In an attempt to understand these observations, the effects of L-carnosine on the model eukaryote, Saccharomyces cerevisiae, were examined on account of its unique metabolic properties; S. cerevisiae can respire aerobically, but like some tumor cells, it can also exhibit a metabolism in which aerobic respiration is down regulated. L-Carnosine exhibited both inhibitory and stimulatory effects on yeast cells, dependent upon the carbon source in the growth medium. When yeast cells were not reliant on oxidative phosphorylation for energy generation (e.g. when grown on a fermentable carbon source such as 2% glucose), 10–30 mM L-carnosine slowed growth rates in a dose-dependent manner and increased cell death by up to 17%. In contrast, in media containing a non-fermentable carbon source in which yeast are dependent on aerobic respiration (e.g. 2% glycerol), L-carnosine did not provoke cell death. This latter observation was confirmed in the respiratory yeast, Pichia pastoris. Moreover, when deletion strains in the yeast nutrient-sensing pathway were treated with L-carnosine, the cells showed resistance to its inhibitory effects. These findings suggest that L-carnosine affects cells in a metabolism-dependent manner and provide a rationale for its effects on different cell types. PMID:22984600

  6. A growth QTL on chicken chromosome 1 affects emotionality and sociality.

    PubMed

    Wirén, Anna; Jensen, Per

    2011-03-01

    Domestication of animals, regardless of species, is often accompanied by simultaneous changes in several physiological and behavioral traits (e.g. growth rate and fearfulness). In this study we compared the social behavior and emotional reactivity, as measured in a battery of behavioral tests, of two groups of chickens selected from a common genetic background, an advanced intercross line between the ancestral red junglefowl ("RJF") and the domesticated White Leghorn layer ("WL"). The birds were selected for homozygosity for alternative alleles at one locus (a microsatellite marker), centrally positioned in a previously identified pleiotropic growth QTL on chromosome 1, closely linked to one major candidate gene (AVPR1a) for certain aspects of social behavior. Birds homozygous for the WL allele ("WL genotype") had a modified pattern of social and emotional reactions than birds homozygous for the RJF allele ("RJF genotype"), shown by different scores in a principal components analysis. These results suggest that the growth QTL affects a number of domestication related behavioral traits, and may have been a primary target of selection during domestication. The QTL contains a multitude of genes, several of which have been linked to social behavior (for example the vasotocin receptor AVPR1a targeted in this experiment). Future studies aimed at making a higher resolution genotypic characterization of the QTL should give more information about which of these genes may be considered the strongest candidates for bringing about the behavioral changes associated with animal domestication. PMID:20596888

  7. L-carnosine affects the growth of Saccharomyces cerevisiae in a metabolism-dependent manner.

    PubMed

    Cartwright, Stephanie P; Bill, Roslyn M; Hipkiss, Alan R

    2012-01-01

    The dipeptide L-carnosine (β-alanyl-L-histidine) has been described as enigmatic: it inhibits growth of cancer cells but delays senescence in cultured human fibroblasts and extends the lifespan of male fruit flies. In an attempt to understand these observations, the effects of L-carnosine on the model eukaryote, Saccharomyces cerevisiae, were examined on account of its unique metabolic properties; S. cerevisiae can respire aerobically, but like some tumor cells, it can also exhibit a metabolism in which aerobic respiration is down regulated. L-Carnosine exhibited both inhibitory and stimulatory effects on yeast cells, dependent upon the carbon source in the growth medium. When yeast cells were not reliant on oxidative phosphorylation for energy generation (e.g. when grown on a fermentable carbon source such as 2% glucose), 10-30 mM L-carnosine slowed growth rates in a dose-dependent manner and increased cell death by up to 17%. In contrast, in media containing a non-fermentable carbon source in which yeast are dependent on aerobic respiration (e.g. 2% glycerol), L-carnosine did not provoke cell death. This latter observation was confirmed in the respiratory yeast, Pichia pastoris. Moreover, when deletion strains in the yeast nutrient-sensing pathway were treated with L-carnosine, the cells showed resistance to its inhibitory effects. These findings suggest that L-carnosine affects cells in a metabolism-dependent manner and provide a rationale for its effects on different cell types.

  8. Streptomycin affects the growth and photochemical activity of the alga Chlorella vulgaris.

    PubMed

    Perales-Vela, Hugo Virgilio; García, Roberto Velasco; Gómez-Juárez, Evelyn Alicia; Salcedo-Álvarez, Martha Ofelia; Cañizares-Villanueva, Rosa Olivia

    2016-10-01

    Antibiotics are increasingly being used in human and veterinary medicine, as well as pest control in agriculture. Recently, their emergence in the aquatic environment has become a global concern. The aim of this study was to evaluate the effect of streptomycin on growth and photosynthetic activity of Chlorella vulgaris after 72h exposure. We found that growth, photosynthetic activity and the content of the D1 protein of photosystem II decreased. Analysis of chlorophyll a fluorescence emission shows a reduction in the energy transfer between the antenna complex and reaction center. Also the activity of the oxygen evolution complex and electron flow between QA and QB were significantly reduced; in contrast, we found an increase in the reduction rate of the acceptor side of photosystem I. The foregoing can be attributed to the inhibition of the synthesis of the D1 protein and perhaps other coded chloroplast proteins that are part of the electron transport chain which are essential for the transformation of solar energy in the photosystems. We conclude that micromolar concentrations of streptomycin can affect growth and photosynthetic activity of Chlorella vulgaris. The accumulation of antibiotics in the environment can become an ecological problem for primary producers in the aquatic environment. PMID:27344399

  9. Streptomycin affects the growth and photochemical activity of the alga Chlorella vulgaris.

    PubMed

    Perales-Vela, Hugo Virgilio; García, Roberto Velasco; Gómez-Juárez, Evelyn Alicia; Salcedo-Álvarez, Martha Ofelia; Cañizares-Villanueva, Rosa Olivia

    2016-10-01

    Antibiotics are increasingly being used in human and veterinary medicine, as well as pest control in agriculture. Recently, their emergence in the aquatic environment has become a global concern. The aim of this study was to evaluate the effect of streptomycin on growth and photosynthetic activity of Chlorella vulgaris after 72h exposure. We found that growth, photosynthetic activity and the content of the D1 protein of photosystem II decreased. Analysis of chlorophyll a fluorescence emission shows a reduction in the energy transfer between the antenna complex and reaction center. Also the activity of the oxygen evolution complex and electron flow between QA and QB were significantly reduced; in contrast, we found an increase in the reduction rate of the acceptor side of photosystem I. The foregoing can be attributed to the inhibition of the synthesis of the D1 protein and perhaps other coded chloroplast proteins that are part of the electron transport chain which are essential for the transformation of solar energy in the photosystems. We conclude that micromolar concentrations of streptomycin can affect growth and photosynthetic activity of Chlorella vulgaris. The accumulation of antibiotics in the environment can become an ecological problem for primary producers in the aquatic environment.

  10. Climate Forcing Growth Rates: Doubling Down on Our Faustian Bargain

    NASA Technical Reports Server (NTRS)

    Hansen, James; Kharecha, Pushker; Sato, Makiko

    2013-01-01

    Rahmstorf et al 's (2012) conclusion that observed climate change is comparable to projections, and in some cases exceeds projections, allows further inferences if we can quantify changing climate forcings and compare those with projections. The largest climate forcing is caused by well-mixed long-lived greenhouse gases. Here we illustrate trends of these gases and their climate forcings, and we discuss implications. We focus on quantities that are accurately measured, and we include comparison with fixed scenarios, which helps reduce common misimpressions about how climate forcings are changing. Annual fossil fuel CO2 emissions have shot up in the past decade at about 3/yr, double the rate of the prior three decades (figure 1). The growth rate falls above the range of the IPCC (2001) 'Marker' scenarios, although emissions are still within the entire range considered by the IPCC SRES (2000). The surge in emissions is due to increased coal use (blue curve in figure 1), which now accounts for more than 40 of fossil fuel CO2 emissions.

  11. Metabolic clearance and production rates of human growth hormone.

    PubMed

    Taylor, A L; Finster, J L; Mintz, D H

    1969-12-01

    The metabolic clearance rate (MCR) of human growth hormone (HGH) was determined by the constant infusion to equilibrium technique utilizing HGH-(125)I. 22 control subjects had a MCR of 229 +/-52 ml/min (mean +/-SD). No difference was evident between sexes, or between various age groups. Patients with acromegaly demonstrated normal MCR's. Moreover, acute elevations of plasma growth hormone concentrations in normal subjects did not alter the MCR of HGH. The MCR was relatively constant from day to day and within the day when subjects were evaluated in the supine position. In contrast, the assumption of the upright position was associated with a mean 24% decrease in the MCR. These results were contrasted with the MCR of HGH observed in a small number of patients with altered thyroid function or diabetes mellitus. In six patients with hypothyroidism the MCR (131 +/-36 ml/min) was significantly decreased (P < 0.001); whereas the MCR in eight patients with hyperthyroidism (240 +/-57 ml/min) did not differ from control subjects. The MCR in eight patients with insulin-independent diabetes mellitus (IID) (185 +/-41 ml/min) and in eight patients with insulin-dependent diabetes mellitus (IDD) (136 +/-31 ml/min) were significantly different from control subjects (P = < 0.05 and P = < 0.001, respectively). These data were interpreted to indicate that the plasma HGH-removing mechanism(s) is not saturated at physiologic plasma HGH levels, that plasma HGH levels alone may not permit distinction between variations in pituitary release of the hormone and its rate of clearance from the plasma, and that the estimation of the MCR of HGH may help clarify the mechanism of abnormal plasma HGH responses to various stimuli. Production rates of HGH (PR) in control subjects (347 +/-173 mmug/min) were contrasted with hyperthyroid patients (529 +/-242 mmug/min, P < 0.05), hypothyroid patients (160 +/-69 mmug/min, P < 0.02), IID (245 +/-100 mmug/min, NS), and IDD (363 +/-153 mmug/min, NS

  12. An experimental investigation of the effect of hydrophobicity on the rate of frost growth in laminar channel flows

    SciTech Connect

    Dyer, J.M.; Storey, B.D.; Hoke, J.L.; Jacobi, A.M.; Georgiadis, J.G.

    2000-07-01

    An experimental investigation of the effect of the substrate on frost growth rate is presented. Measurements of frost height as a function of time are presented for a flat, bare, horizontally oriented aluminum substrate and four coated substrates, two hydrophilic and two hydrophobic. The average frost growth rate on the hydrophilic coated aluminum substrate is 13% higher than the control substrate, while the frost growth rate on the hydrophilic kapton substrate is 4% higher. Frost grows on the hydrophobic substrates at a rate 19% and 3% lower than the reference substrate for the polytetrafluoroethylene (PTFE) coated steel and PTFE tape, respectively. Differences in the receding and advancing contact angles for these substrates do not fully explain the difference in growth rates. Differences in initial water deposition, freezing, and frost growth on hydrophilic and hydrophobic substrates are examined using confocal microscopy. On the basis of the microscopic observations, the authors hypothesize that the water coverage on the substrate before and after freezing can affect the thermal resistance of the mature frost layer. Differences in thermal resistance, in turn, affect the growth rate.

  13. Relationship between obesity, negative affect and basal heart rate in predicting heart rate reactivity to psychological stress among adolescents

    PubMed Central

    Park, Andres E.; Huynh, Pauline; Schell, Anne M.; Baker, Laura A.

    2015-01-01

    Reduced cardiovascular responses to psychological stressors have been found to be associated with both obesity and negative affect in adults, but have been less well studied in children and adolescent populations. These findings have most often been interpreted as reflecting reduced sympathetic nervous system response, perhaps associated with heightened baseline sympathetic activation among the obese and those manifesting negative affect. However, obesity and negative affect may themselves be correlated, raising the question of whether they both independently affect cardiovascular reactivity. The present study thus examined the separate effects of obesity and negative affect on both cardiovascular and skin conductance responses to stress (e.g., during a serial subtraction math task) in adolescents, while controlling for baseline levels of autonomic activity during rest. Both obesity and negative affect had independent and negative associations with cardiovascular reactivity, such that reduced stress responses were apparent for obese adolescents and those with high levels of negative affect. In contrast, neither obesity nor negative affect was related to skin conductance responses to stress, implicating specifically noradrenergic mechanisms rather than sympathetic mechanisms generally as being deficient. Moreover, baseline heart rate was unrelated to obesity in this sample, which suggests that heightened baseline of sympathetic activity is not necessary for the reduced cardiovascular reactivity to stress. PMID:26049136

  14. Relationship between obesity, negative affect and basal heart rate in predicting heart rate reactivity to psychological stress among adolescents.

    PubMed

    Park, Andres E; Huynh, Pauline; Schell, Anne M; Baker, Laura A

    2015-08-01

    Reduced cardiovascular responses to psychological stressors have been found to be associated with both obesity and negative affect in adults, but have been less well studied in children and adolescent populations. These findings have most often been interpreted as reflecting reduced sympathetic nervous system response, perhaps associated with heightened baseline sympathetic activation among the obese and those manifesting negative affect. However, obesity and negative affect may themselves be correlated, raising the question of whether they both independently affect cardiovascular reactivity. The present study thus examined the separate effects of obesity and negative affect on both cardiovascular and skin conductance responses to stress (e.g., during a serial subtraction math task) in adolescents, while controlling for baseline levels of autonomic activity during rest. Both obesity and negative affect had independent and negative associations with cardiovascular reactivity, such that reduced stress responses were apparent for obese adolescents and those with high levels of negative affect. In contrast, neither obesity nor negative affect was related to skin conductance responses to stress, implicating specifically noradrenergic mechanisms rather than sympathetic mechanisms generally as being deficient. Moreover, baseline heart rate was unrelated to obesity in this sample, which suggests that heightened baseline of sympathetic activity is not necessary for the reduced cardiovascular reactivity to stress.

  15. Jensen's Inequality and the Impact of Short-Term Environmental Variability on Long-Term Population Growth Rates.

    PubMed

    Pickett, Evan J; Thomson, David L; Li, Teng A; Xing, Shuang

    2015-01-01

    It is well established in theory that short-term environmental fluctuations could affect the long-term growth rates of wildlife populations, but this theory has rarely been tested and there remains little empirical evidence that the effect is actually important in practice. Here we develop models to quantify the effects of daily, seasonal, and yearly temperature fluctuations on the average population growth rates, and we apply them to long-term data on the endangered Black-faced Spoonbill (Platalea minor); an endothermic species whose population growth rates follow a concave relationship with temperature. We demonstrate for the first time that the current levels of temperature variability, particularly seasonal variability, are already large enough to substantially reduce long-term population growth rates. As the climate changes, our results highlight the importance of considering the ecological effects of climate variability and not just average conditions. PMID:26352857

  16. Growth of ponderosa pine seedlings as affected by air pollution

    NASA Astrophysics Data System (ADS)

    Momen, B.; Anderson, P. D.; Houpis, J. L. J.; Helms, J. A.

    The effect of air pollution on seedling survival and competitive ability is important to natural and artificial regeneration of forest trees. Although biochemical and physiological processes are sensitive indicators of pollution stress, the cumulative effects of air pollutants on seedling vigor and competitive ability may be assessed directly from whole-plant growth characteristics such as diameter, height, and photosynthetic area. A few studies that have examined intraspecific variation in seedling response to air pollution indicate that genotypic differences are important in assessing potential effects of air pollution on forest regeneration. Here, we studied the effects of acid rain (no-rain, pH 5.1 rain, pH 3.0 rain) and ozone (filtered, ambient, twice-ambient) in the field on height, diameter, volume, the height:diameter ratio, maximum needle length, and time to reach maximum needle length in seedlings of three families of ponderosa pine ( Pinus ponderosa Dougl. ex Laws). Seedling diameter, height, volume, and height:diameter ratio related significantly to their pre-treatment values. Twice-ambient ozone decreased seedling diameter compared with ozone-filtered air. A significant family-by-ozone interaction was detected for seedling height, as the height of only one of the three families was decreased by twice-ambient ozone compared with the ambient level. Seedling diameter was larger and the height:diameter ratio was smaller under pH 3.0 rain compared to either the no-rain or the pH 5.1-rain treatment. This suggests greater seedling vigor, perhaps due to a foliar fertilization effect of the pH 3.0 rain.

  17. Percolation model for growth rates of aggregates and its application for business firm growth

    NASA Astrophysics Data System (ADS)

    Fu, Dongfeng; Buldyrev, Sergey V.; Salinger, Michael A.; Stanley, H. Eugene

    2006-09-01

    Motivated by recent empirical studies of business firm growth, we develop a dynamic percolation model which captures some of the features of the economical system—i.e., merging and splitting of business firms—represented as aggregates on a d -dimensional lattice. We find the steady-state distribution of the aggregate size and explore how this distribution depends on the model parameters. We find that at the critical threshold, the standard deviation of the aggregate growth rates, σ , increases with aggregate size S as σ˜Sβ , where β can be explained in terms of the connectedness length exponent ν and the fractal dimension df , with β=1/(2νdf)≈0.20 for d=2 and 0.125 for d→∞ . The distributions of aggregate growth rates have a sharp peak at the center and pronounced wings extending over many standard deviations, giving the distribution a tent-shape form—the Laplace distribution. The distributions for different aggregate sizes scaled by their standard deviations collapse onto the same curve.

  18. Measuring aging rates of mice subjected to caloric restriction and genetic disruption of growth hormone signaling.

    PubMed

    Koopman, Jacob J E; van Heemst, Diana; van Bodegom, David; Bonkowski, Michael S; Sun, Liou Y; Bartke, Andrzej

    2016-03-01

    Caloric restriction and genetic disruption of growth hormone signaling have been shown to counteract aging in mice. The effects of these interventions on aging are examined through age-dependent survival or through the increase in age-dependent mortality rates on a logarithmic scale fitted to the Gompertz model. However, these methods have limitations that impede a fully comprehensive disclosure of these effects. Here we examine the effects of these interventions on murine aging through the increase in age-dependent mortality rates on a linear scale without fitting them to a model like the Gompertz model. Whereas these interventions negligibly and non-consistently affected the aging rates when examined through the age-dependent mortality rates on a logarithmic scale, they caused the aging rates to increase at higher ages and to higher levels when examined through the age-dependent mortality rates on a linear scale. These results add to the debate whether these interventions postpone or slow aging and to the understanding of the mechanisms by which they affect aging. Since different methods yield different results, it is worthwhile to compare their results in future research to obtain further insights into the effects of dietary, genetic, and other interventions on the aging of mice and other species.

  19. Measuring aging rates of mice subjected to caloric restriction and genetic disruption of growth hormone signaling

    PubMed Central

    Koopman, Jacob J.E.; van Heemst, Diana; van Bodegom, David; Bonkowski, Michael S.; Sun, Liou Y.; Bartke, Andrzej

    2016-01-01

    Caloric restriction and genetic disruption of growth hormone signaling have been shown to counteract aging in mice. The effects of these interventions on aging are examined through age-dependent survival or through the increase in age-dependent mortality rates on a logarithmic scale fitted to the Gompertz model. However, these methods have limitations that impede a fully comprehensive disclosure of these effects. Here we examine the effects of these interventions on murine aging through the increase in age-dependent mortality rates on a linear scale without fitting them to a model like the Gompertz model. Whereas these interventions negligibly and non-consistently affected the aging rates when examined through the age-dependent mortality rates on a logarithmic scale, they caused the aging rates to increase at higher ages and to higher levels when examined through the age-dependent mortality rates on a linear scale. These results add to the debate whether these interventions postpone or slow aging and to the understanding of the mechanisms by which they affect aging. Since different methods yield different results, it is worthwhile to compare their results in future research to obtain further insights into the effects of dietary, genetic, and other interventions on the aging of mice and other species. PMID:26959761

  20. Allometric growth and development of organs in ballan wrasse (Labrus bergylta Ascanius, 1767) larvae in relation to different live prey diets and growth rates.

    PubMed

    Gagnat, Maren Ranheim; Wold, Per-Arvid; Bardal, Tora; Øie, Gunvor; Kjørsvik, Elin

    2016-01-01

    Small fish larvae grow allometrically, but little is known about how this growth pattern may be affected by different growth rates and early diet quality. The present study investigates how different growth rates, caused by start-feeding with copepods or rotifers the first 30 days post-hatch (dph), affect allometric growth and development of nine major organs in ballan wrasse (Labrus bergylta) larvae up to experimental end at 60 dph. Feeding with cultivated copepod nauplii led to both increased larval somatic growth and faster development and growth of organ systems than feeding with rotifers. Of the organs studied, the digestive and respiratory organs increased the most in size between 4 and 8 dph, having a daily specific growth rate (SGR) between 30 and 40% in larvae fed copepods compared with 20% or less for rotifer-fed larvae. Muscle growth was prioritised from flexion stage and onwards, with a daily SGR close to 30% between 21 and 33 dph regardless of treatment. All larvae demonstrated a positive linear correlation between larval standard length (SL) and increase in total tissue volume, and no difference in allometric growth pattern was found between the larval treatments. A change from positive allometric to isometric growth was observed at a SL close to 6.0 mm, a sign associated with the start of metamorphosis. This was also where the larvae reached postflexion stage, and was accompanied by a change in growth pattern for most of the major organ systems. The first sign of a developing hepatopancreas was, however, first observed in the largest larva (17.4 mm SL, 55 dph), indicating that the metamorphosis in ballan wrasse is a gradual process lasting from 6.0 to at least 15-17 mm SL. PMID:27422903

  1. Allometric growth and development of organs in ballan wrasse (Labrus bergylta Ascanius, 1767) larvae in relation to different live prey diets and growth rates

    PubMed Central

    Wold, Per-Arvid; Bardal, Tora; Øie, Gunvor; Kjørsvik, Elin

    2016-01-01

    ABSTRACT Small fish larvae grow allometrically, but little is known about how this growth pattern may be affected by different growth rates and early diet quality. The present study investigates how different growth rates, caused by start-feeding with copepods or rotifers the first 30 days post-hatch (dph), affect allometric growth and development of nine major organs in ballan wrasse (Labrus bergylta) larvae up to experimental end at 60 dph. Feeding with cultivated copepod nauplii led to both increased larval somatic growth and faster development and growth of organ systems than feeding with rotifers. Of the organs studied, the digestive and respiratory organs increased the most in size between 4 and 8 dph, having a daily specific growth rate (SGR) between 30 and 40% in larvae fed copepods compared with 20% or less for rotifer-fed larvae. Muscle growth was prioritised from flexion stage and onwards, with a daily SGR close to 30% between 21 and 33 dph regardless of treatment. All larvae demonstrated a positive linear correlation between larval standard length (SL) and increase in total tissue volume, and no difference in allometric growth pattern was found between the larval treatments. A change from positive allometric to isometric growth was observed at a SL close to 6.0 mm, a sign associated with the start of metamorphosis. This was also where the larvae reached postflexion stage, and was accompanied by a change in growth pattern for most of the major organ systems. The first sign of a developing hepatopancreas was, however, first observed in the largest larva (17.4 mm SL, 55 dph), indicating that the metamorphosis in ballan wrasse is a gradual process lasting from 6.0 to at least 15-17 mm SL. PMID:27422903

  2. Allometric growth and development of organs in ballan wrasse (Labrus bergylta Ascanius, 1767) larvae in relation to different live prey diets and growth rates.

    PubMed

    Gagnat, Maren Ranheim; Wold, Per-Arvid; Bardal, Tora; Øie, Gunvor; Kjørsvik, Elin

    2016-09-15

    Small fish larvae grow allometrically, but little is known about how this growth pattern may be affected by different growth rates and early diet quality. The present study investigates how different growth rates, caused by start-feeding with copepods or rotifers the first 30 days post-hatch (dph), affect allometric growth and development of nine major organs in ballan wrasse (Labrus bergylta) larvae up to experimental end at 60 dph. Feeding with cultivated copepod nauplii led to both increased larval somatic growth and faster development and growth of organ systems than feeding with rotifers. Of the organs studied, the digestive and respiratory organs increased the most in size between 4 and 8 dph, having a daily specific growth rate (SGR) between 30 and 40% in larvae fed copepods compared with 20% or less for rotifer-fed larvae. Muscle growth was prioritised from flexion stage and onwards, with a daily SGR close to 30% between 21 and 33 dph regardless of treatment. All larvae demonstrated a positive linear correlation between larval standard length (SL) and increase in total tissue volume, and no difference in allometric growth pattern was found between the larval treatments. A change from positive allometric to isometric growth was observed at a SL close to 6.0 mm, a sign associated with the start of metamorphosis. This was also where the larvae reached postflexion stage, and was accompanied by a change in growth pattern for most of the major organ systems. The first sign of a developing hepatopancreas was, however, first observed in the largest larva (17.4 mm SL, 55 dph), indicating that the metamorphosis in ballan wrasse is a gradual process lasting from 6.0 to at least 15-17 mm SL.

  3. Adaptation of Lactococcus lactis to high growth temperature leads to a dramatic increase in acidification rate.

    PubMed

    Chen, Jun; Shen, Jing; Ingvar Hellgren, Lars; Ruhdal Jensen, Peter; Solem, Christian

    2015-09-21

    Lactococcus lactis is essential for most cheese making, and this mesophilic bacterium has its growth optimum around 30 °C. We have, through adaptive evolution, isolated a mutant TM29 that grows well up to 39 °C, and continuous growth at 40 °C is possible if pre-incubated at a slightly lower temperature. At the maximal permissive temperature for the wild-type, 38 °C, TM29 grows 33% faster and has a 12% higher specific lactate production rate than its parent MG1363, which results in fast lactate accumulation. Genome sequencing was used to reveal the mutations accumulated, most of which were shown to affect thermal tolerance. Of the mutations with more pronounced effects, two affected expression of single proteins (chaperone; riboflavin transporter), two had pleiotropic effects (RNA polymerase) which changed the gene expression profile, and one resulted in a change in the coding sequence of CDP-diglyceride synthase. A large deletion containing 10 genes was also found to affect thermal tolerance significantly. With this study we demonstrate a simple approach to obtain non-GMO derivatives of the important L. lactis that possess properties desirable by the industry, e.g. thermal robustness and increased rate of acidification. The mutations we have identified provide a genetic basis for further investigation of thermal tolerance.

  4. Adaptation of Lactococcus lactis to high growth temperature leads to a dramatic increase in acidification rate.

    PubMed

    Chen, Jun; Shen, Jing; Ingvar Hellgren, Lars; Ruhdal Jensen, Peter; Solem, Christian

    2015-01-01

    Lactococcus lactis is essential for most cheese making, and this mesophilic bacterium has its growth optimum around 30 °C. We have, through adaptive evolution, isolated a mutant TM29 that grows well up to 39 °C, and continuous growth at 40 °C is possible if pre-incubated at a slightly lower temperature. At the maximal permissive temperature for the wild-type, 38 °C, TM29 grows 33% faster and has a 12% higher specific lactate production rate than its parent MG1363, which results in fast lactate accumulation. Genome sequencing was used to reveal the mutations accumulated, most of which were shown to affect thermal tolerance. Of the mutations with more pronounced effects, two affected expression of single proteins (chaperone; riboflavin transporter), two had pleiotropic effects (RNA polymerase) which changed the gene expression profile, and one resulted in a change in the coding sequence of CDP-diglyceride synthase. A large deletion containing 10 genes was also found to affect thermal tolerance significantly. With this study we demonstrate a simple approach to obtain non-GMO derivatives of the important L. lactis that possess properties desirable by the industry, e.g. thermal robustness and increased rate of acidification. The mutations we have identified provide a genetic basis for further investigation of thermal tolerance. PMID:26388459

  5. Adaptation of Lactococcus lactis to high growth temperature leads to a dramatic increase in acidification rate

    PubMed Central

    Chen, Jun; Shen, Jing; Ingvar Hellgren, Lars; Ruhdal Jensen, Peter; Solem, Christian

    2015-01-01

    Lactococcus lactis is essential for most cheese making, and this mesophilic bacterium has its growth optimum around 30 °C. We have, through adaptive evolution, isolated a mutant TM29 that grows well up to 39 °C, and continuous growth at 40 °C is possible if pre-incubated at a slightly lower temperature. At the maximal permissive temperature for the wild-type, 38 °C, TM29 grows 33% faster and has a 12% higher specific lactate production rate than its parent MG1363, which results in fast lactate accumulation. Genome sequencing was used to reveal the mutations accumulated, most of which were shown to affect thermal tolerance. Of the mutations with more pronounced effects, two affected expression of single proteins (chaperone; riboflavin transporter), two had pleiotropic effects (RNA polymerase) which changed the gene expression profile, and one resulted in a change in the coding sequence of CDP-diglyceride synthase. A large deletion containing 10 genes was also found to affect thermal tolerance significantly. With this study we demonstrate a simple approach to obtain non-GMO derivatives of the important L. lactis that possess properties desirable by the industry, e.g. thermal robustness and increased rate of acidification. The mutations we have identified provide a genetic basis for further investigation of thermal tolerance. PMID:26388459

  6. Effect of temperature on microbial growth rate-mathematical analysis: the Arrhenius and Eyring-Polanyi connections.

    PubMed

    Huang, Lihan; Hwang, Andy; Phillips, John

    2011-10-01

    The objective of this work is to develop a mathematical model for evaluating the effect of temperature on the rate of microbial growth. The new mathematical model is derived by combination and modification of the Arrhenius equation and the Eyring-Polanyi transition theory. The new model, suitable for both suboptimal and the entire growth temperature ranges, was validated using a collection of 23 selected temperature-growth rate curves belonging to 5 groups of microorganisms, including Pseudomonas spp., Listeria monocytogenes, Salmonella spp., Clostridium perfringens, and Escherichia coli, from the published literature. The curve fitting is accomplished by nonlinear regression using the Levenberg-Marquardt algorithm. The resulting estimated growth rate (μ) values are highly correlated to the data collected from the literature (R(2) = 0.985, slope = 1.0, intercept = 0.0). The bias factor (B(f) ) of the new model is very close to 1.0, while the accuracy factor (A(f) ) ranges from 1.0 to 1.22 for most data sets. The new model is compared favorably with the Ratkowsky square root model and the Eyring equation. Even with more parameters, the Akaike information criterion, Bayesian information criterion, and mean square errors of the new model are not statistically different from the square root model and the Eyring equation, suggesting that the model can be used to describe the inherent relationship between temperature and microbial growth rates. The results of this work show that the new growth rate model is suitable for describing the effect of temperature on microbial growth rate. Practical Application:  Temperature is one of the most significant factors affecting the growth of microorganisms in foods. This study attempts to develop and validate a mathematical model to describe the temperature dependence of microbial growth rate. The findings show that the new model is accurate and can be used to describe the effect of temperature on microbial growth rate in foods.

  7. Basic principles of muscle development and growth in meat-producing mammals as affected by the insulin-like growth factor (IGF) system.

    PubMed

    Oksbjerg, Niels; Gondret, Florence; Vestergaard, Mogens

    2004-10-01

    This presentation aims to describe how the basic events in prenatal muscle development and postnatal muscle growth are controlled by the insulin-like growth factor system (IGF). The prenatal events (myogenesis) cover the rate of proliferation, the rate and extent of fusion, and the differentiation of three myoblast populations, giving rise to primary fibers, secondary fibers, and a satellite cell population, respectively. The number of muscle fibers, a key determinant of the postnatal growth rate, is fixed late in gestation. The postnatal events contributing to myofiber hypertrophy comprise satellite cell proliferation and differentiation, and protein turnover. Muscle cell cultures produce IGFs and IGF binding proteins (IGFBPs) in various degrees depending on the origin (species, muscle type) and state of development of these cells, suggesting an autocrine/paracrine mode of action of IGF-related factors. In vivo studies and results based on cell lines or primary cell cultures show that IGF-I and IGF-II stimulate both proliferation and differentiation of myoblasts and satellite cells in a time and concentration-dependent way, via interaction with type I IGF receptors. However, IGF binding proteins (IGFBP) may either inhibit or potentiate the stimulating effects of IGFs on proliferation or differentiation. During postnatal growth in vivo or in fully differentiated muscle cells in culture, IGF-I stimulates the rate of protein synthesis and inhibits the rate of protein degradation, thereby enhancing myofiber hypertrophy. The possible roles and actions of the IGF system in regulating and determining muscle growth as affected by developmental stage and age, muscle type, feeding levels, treatment with growth hormone and selection for growth performance are discussed.

  8. Estimation of uncertainty for fatigue growth rate at cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Nyilas, Arman; Weiss, Klaus P.; Urbach, Elisabeth; Marcinek, Dawid J.

    2014-01-01

    Fatigue crack growth rate (FCGR) measurement data for high strength austenitic alloys at cryogenic environment suffer in general from a high degree of data scatter in particular at ΔK regime below 25 MPa√m. Using standard mathematical smoothing techniques forces ultimately a linear relationship at stage II regime (crack propagation rate versus ΔK) in a double log field called Paris law. However, the bandwidth of uncertainty relies somewhat arbitrary upon the researcher's interpretation. The present paper deals with the use of the uncertainty concept on FCGR data as given by GUM (Guidance of Uncertainty in Measurements), which since 1993 is a recommended procedure to avoid subjective estimation of error bands. Within this context, the lack of a true value addresses to evaluate the best estimate by a statistical method using the crack propagation law as a mathematical measurement model equation and identifying all input parameters. Each parameter necessary for the measurement technique was processed using the Gaussian distribution law by partial differentiation of the terms to estimate the sensitivity coefficients. The combined standard uncertainty determined for each term with its computed sensitivity coefficients finally resulted in measurement uncertainty of the FCGR test result. The described procedure of uncertainty has been applied within the framework of ITER on a recent FCGR measurement for high strength and high toughness Type 316LN material tested at 7 K using a standard ASTM proportional compact tension specimen. The determined values of Paris law constants such as C0 and the exponent m as best estimate along with the their uncertainty value may serve a realistic basis for the life expectancy of cyclic loaded members.

  9. Body composition of piglets exhibiting different growth rates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The growth and composition of the neonatal pig is of interest because of potential impact on subsequent growth and finally, composition at market weight. The purpose of this study was to compare at weaning the growth and body composition of the largest and smallest pigs (excluding runts) from each o...

  10. In vivo embryo recovery rate by laparoscopic technique from rabbit does selected for growth rate.

    PubMed

    Mehaisen, G M K; Vicente, J S; Lavara, R

    2004-10-01

    Rabbit does from R line selected for growth rate present a low reproductive performance and this study aimed to evaluate both the recovery efficacy and viability of recovered embryos after vitrification and the reproductive performance of donor does subjected to in vivo recovery. Does were divided into three groups: 28 does without in vivo recovery (control), 25 does in which in vivo recovery was started in the nulliparous state (group 1) and 30 does with at least one litter before in vivo recovery (group 2). Does were superovulated with a single subcutaneous injection of 50 IU of equine chorionic gonadotropin (eCG) per female, and were then artificially inseminated 60 h later and immediately administered an intravenous dose of 75 IU of human chorionic gonadotropin (hCG) per female. Does from group 1 and 2 were recovered in vivo 76-80 h post-insemination by repeated laparoscopies at one to four times and permitted one or two parturitions between recoveries [in vivo (IV) recovery]. At the end of the experiment, about 16 does of all groups were recovered post-mortem (PM recovery). All normal embryos were vitrified, devitrified and then cultivated in vitro to evaluate the viability after thawing. A significant increase in the ovulation rate was found in does recovered PM than in those recovered IV in the nulliparous state. However, no significant differences were observed in the recovery rate, the donor rate, the number of normal embryos recovered with at least one normal embryo per doe and the viability after thawing between the PM and IV groups. A significant decrease in the fertility rate, total born, live born and weaned kids was found for does from group 1 in comparison with does from group 2. Results support the use of repeated laparoscopy to increase the number of recovered embryos per donor doe especially in such R line does, if they are permitted to produce at least one litter before the beginning of in vivo recovery. PMID:15367268

  11. Growth rate of early-stage hepatocellular carcinoma in patients with chronic liver disease

    PubMed Central

    An, Chansik; Choi, Youn Ah; Choi, Dongil; Paik, Yong Han; Ahn, Sang Hoon; Kim, Myeong-Jin; Paik, Seung Woon; Han, Kwang-Hyub

    2015-01-01

    Background/Aims The goal of this study was to estimate the growth rate of hepatocellular carcinoma (HCC) and identify the host factors that significantly affect this rate. Methods Patients with early-stage HCC (n=175) who underwent two or more serial dynamic imaging studies without any anticancer treatment at two tertiary care hospitals in Korea were identified. For each patient, the tumor volume doubling time (TVDT) of HCC was calculated by comparing tumor volumes between serial imaging studies. Clinical and laboratory data were obtained from the medical records of the patients. Results The median TVDT was 85.7 days, with a range of 11 to 851.2 days. Multiple linear regression revealed that the initial tumor diameter (a tumor factor) and the etiology of chronic liver disease (a host factor) were significantly associated with the TVDT. The TVDT was shorter when the initial tumor diameter was smaller, and was shorter in HCC related to hepatitis B virus (HBV) infection than in HCC related to hepatitis C virus (HCV) infection (median, 76.8 days vs. 137.2 days; P=0.0234). Conclusions The etiology of chronic liver disease is a host factor that may significantly affect the growth rate of early-stage HCC, since HBV-associated HCC grows faster than HCV-associated HCC. PMID:26523271

  12. Long-run growth rate in a random multiplicative model

    SciTech Connect

    Pirjol, Dan

    2014-08-01

    We consider the long-run growth rate of the average value of a random multiplicative process x{sub i+1} = a{sub i}x{sub i} where the multipliers a{sub i}=1+ρexp(σW{sub i}₋1/2 σ²t{sub i}) have Markovian dependence given by the exponential of a standard Brownian motion W{sub i}. The average value (x{sub n}) is given by the grand partition function of a one-dimensional lattice gas with two-body linear attractive interactions placed in a uniform field. We study the Lyapunov exponent λ=lim{sub n→∞}1/n log(x{sub n}), at fixed β=1/2 σ²t{sub n}n, and show that it is given by the equation of state of the lattice gas in thermodynamical equilibrium. The Lyapunov exponent has discontinuous partial derivatives along a curve in the (ρ, β) plane ending at a critical point (ρ{sub C}, β{sub C}) which is related to a phase transition in the equivalent lattice gas. Using the equivalence of the lattice gas with a bosonic system, we obtain the exact solution for the equation of state in the thermodynamical limit n → ∞.

  13. Sustainable growth rate 2013: time for definitive intervention.

    PubMed

    Hirsch, Joshua A; Rosman, David A; Liu, Raymond W; Ding, Alexander; Manchikanti, Laxmaiah

    2013-07-01

    Federal healthcare spending has been a subject of intense concern as the US Congress continues to search for ways to reduce the budget deficit. The Congressional Budget Office (CBO) estimated that, even though it is growing more slowly than previously projected, federal spending on Medicare, Medicaid and the State Children's Health Insurance Program (SCHIP) will reach nearly $900 billion in 2013. In 2011 the Medicare program paid $68 billion for physicians and other health professional services, 12% of total Medicare spending. Since 2002 the sustainable growth rate (SGR) correction has called for reductions to physician reimbursements; however, Congress has typically staved off these reductions, although the situation remains precarious for physicians who accept Medicare. The fiscal cliff agreement that came into focus at the end of 2012 averted a 26.5% reduction to physician reimbursements related to the SGR correction. Nonetheless, the threat of these devastating cuts continues to loom. The Administration, Congress and others have devised many options to fix this unsustainable situation. This review explores the historical development of the SGR, touches on elements of the formula itself and outlines current proposals for fixing the SGR problem. A recent CBO estimate reduces the potential cost of a 10-year fix of SGR system to $138 billion. This has provided new hope for resolution of this long-standing issue. PMID:23645571

  14. Sustainable growth rate 2013: time for definitive intervention.

    PubMed

    Hirsch, Joshua A; Rosman, David A; Liu, Raymond W; Ding, Alexander; Manchikanti, Laxmaiah

    2013-07-01

    Federal healthcare spending has been a subject of intense concern as the US Congress continues to search for ways to reduce the budget deficit. The Congressional Budget Office (CBO) estimated that, even though it is growing more slowly than previously projected, federal spending on Medicare, Medicaid and the State Children's Health Insurance Program (SCHIP) will reach nearly $900 billion in 2013. In 2011 the Medicare program paid $68 billion for physicians and other health professional services, 12% of total Medicare spending. Since 2002 the sustainable growth rate (SGR) correction has called for reductions to physician reimbursements; however, Congress has typically staved off these reductions, although the situation remains precarious for physicians who accept Medicare. The fiscal cliff agreement that came into focus at the end of 2012 averted a 26.5% reduction to physician reimbursements related to the SGR correction. Nonetheless, the threat of these devastating cuts continues to loom. The Administration, Congress and others have devised many options to fix this unsustainable situation. This review explores the historical development of the SGR, touches on elements of the formula itself and outlines current proposals for fixing the SGR problem. A recent CBO estimate reduces the potential cost of a 10-year fix of SGR system to $138 billion. This has provided new hope for resolution of this long-standing issue.

  15. Effect of acidified sorbate solutions on the lag phase durations and growth rates of Listeria monocytogenes on meat surfaces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The surfaces of ready-to-eat meats are susceptible to post-processing contamination by Listeria monocytogenes. This study quantified the lag phase durations (LPD) and growth rates (GR) of L. monocytogenes on the surfaces of cooked ham as affected by sorbate solutions of different concentrations and...

  16. Estimation of the growth kinetic parameters of Bacillus cereus spores as affected by pulsed light treatment.

    PubMed

    Aguirre, Juan S; de Fernando, Gonzalo García; Hierro, Eva; Hospital, Xavier F; Ordóñez, Juan A; Fernández, Manuela

    2015-06-01

    Quantitative microbial risk assessment requires the knowledge of the effect of food preservation technologies on the growth parameters of the survivors of the treatment. This is of special interest in the case of the new non-thermal technologies that are being investigated for minimal processing of foods. This is a study on the effect of pulsed light technology (PL) on the lag phase of Bacillus cereus spores surviving the treatment and the maximum growth rate (μmax) of the survivors after germination. The D value was estimated as 0.35 J/cm(2) and our findings showed that PL affected the kinetic parameters of the microorganism. A log linear relationship was observed between the lag phase and the intensity of the treatment. Increasing the lethality lengthened the mean lag phase and proportionally increased its variability. A polynomial regression was fitted between the μmax of the survivors and the inactivation achieved. The μmax decreased as intensity increased. From these data, and their comparison to published results on the effect of heat and e-beam irradiation on B. cereus spores, it was observed that the shelf-life of PL treated foods would be longer than those treated with heat and similar to irradiated ones. These findings offer information of interest for the implementation of PL for microbial decontamination in the food industry. PMID:25755081

  17. Estimation of the growth kinetic parameters of Bacillus cereus spores as affected by pulsed light treatment.

    PubMed

    Aguirre, Juan S; de Fernando, Gonzalo García; Hierro, Eva; Hospital, Xavier F; Ordóñez, Juan A; Fernández, Manuela

    2015-06-01

    Quantitative microbial risk assessment requires the knowledge of the effect of food preservation technologies on the growth parameters of the survivors of the treatment. This is of special interest in the case of the new non-thermal technologies that are being investigated for minimal processing of foods. This is a study on the effect of pulsed light technology (PL) on the lag phase of Bacillus cereus spores surviving the treatment and the maximum growth rate (μmax) of the survivors after germination. The D value was estimated as 0.35 J/cm(2) and our findings showed that PL affected the kinetic parameters of the microorganism. A log linear relationship was observed between the lag phase and the intensity of the treatment. Increasing the lethality lengthened the mean lag phase and proportionally increased its variability. A polynomial regression was fitted between the μmax of the survivors and the inactivation achieved. The μmax decreased as intensity increased. From these data, and their comparison to published results on the effect of heat and e-beam irradiation on B. cereus spores, it was observed that the shelf-life of PL treated foods would be longer than those treated with heat and similar to irradiated ones. These findings offer information of interest for the implementation of PL for microbial decontamination in the food industry.

  18. Lidar observations of mixed layer dynamics - Tests of parameterized entrainment models of mixed layer growth rate

    NASA Technical Reports Server (NTRS)

    Boers, R.; Eloranta, E. W.; Coulter, R. L.

    1984-01-01

    Ground based lidar measurements of the atmospheric mixed layer depth, the entrainment zone depth and the wind speed and wind direction were used to test various parameterized entrainment models of mixed layer growth rate. Six case studies under clear air convective conditions over flat terrain in central Illinois are presented. It is shown that surface heating alone accounts for a major portion of the rise of the mixed layer on all days. A new set of entrainment model constants was determined which optimized height predictions for the dataset. Under convective conditions, the shape of the mixed layer height prediction curves closely resembled the observed shapes. Under conditions when significant wind shear was present, the shape of the height prediction curve departed from the data suggesting deficiencies in the parameterization of shear production. Development of small cumulus clouds on top of the layer is shown to affect mixed layer depths in the afternoon growth phase.

  19. The Averaged Face Growth Rates of lysozyme Crystals: The Effect of Temperature

    NASA Technical Reports Server (NTRS)

    Nadarajah, Arunan; Forsythe, Elizabeth L.; Pusey, Marc L.

    1995-01-01

    Measurements of the averaged or macroscopic face growth rates of lysozyme crystals are reported here for the (110) face of tetragonal lysozyme, at three sets of pH and salt concentrations, with temperatures over a 4-22 C range for several protein concentrations. The growth rate trends with supersaturation were similar to previous microscopic growth rate measurements. However, it was found that at high super-saturations the growth rates attain a maximum and then start decreasing. No 'dead zone' was observed but the growth rates were found to approach zero asymptotically at very low super-saturations. The growth rate data also displayed a dependence on pH and salt concentration which could not be characterized solely by the super-saturation. A complete mechanism for lysozyme crystal growth, involving the formation of an aggregate growth unit, mass transport of the growth unit to the crystal interface and faceted crystal growth by growth unit addition, is suggested. Such a mechanism may provide a more consistent explanation for the observed growth rate trends than those suggested by other investigators. The nutrient solution interactions leading to the formation of the aggregate growth unit may, thus, be as important as those occurring at the crystal interface and may account for the differences between small molecule and protein crystal growth.

  20. Microbial maximal specific growth rate as a square-root function of biomass yield and two kinetic parameters.

    PubMed

    Wong, Wilson W; Liao, James C

    2009-11-01

    Understanding how growth rates changes under different perturbations is fundamental to many aspect of microbial physiology. In this work, we experimentally showed that maximal specific growth rate is a square-root function of the biomass yield, the substrate turnover number, and the maximum synthesis rate of the substrate transporter under that condition. We used Escherichia coli cultures in lactose minimal medium as a model system by introducing genetic modifications, in vitro evolution, and ethanol stress to the cell. Deletion of crr affected all three parameters in different directions while deletion of ptsG decreased only the biomass yield. Ethanol stress negatively impacted all three parameters, while anaerobicity decreased biomass yield and transporter synthesis rate. In addition, laboratory evolution increased the growth rate in lactose mostly through enhancing the expression rate of the lac operon. Despite all these changes, the growth rate of the perturbed strain was successfully related to the three parameters by the square-root equation. Thus, this square-root relationship provides insight into how growth rate is altered by different physiological parameters. PMID:19712746

  1. Growth rate regulation of rRNA content of a marine Synechococcus (cyanobacterium) strain

    SciTech Connect

    Binder, B.J.; Liu, Y.C.

    1998-09-01

    The relationship between growth rate and rRNA content in a marine Synechococcus strain was examined. A combination of flow cytometry and whole-cell hybridization with fluorescently labeled 16S rRNA-targeted oligonucleotide probes was used to measure the rRNA content of Synechococcus strain WH8101 cells grown at a range of light-limited growth rates. The sensitivity of this approach was sufficient for the analysis of rRNA even in very slowly growing Synechococcus cells. The relationship between growth rate and cellular rRNA content comprised three phases: (1) at low growth rates, rRNA cell{sup {minus}1} remained approximately constant; (2) at intermediate rates, rRNA cell{sup {minus}1} increased proportionally with growth rate; and (3) at the highest, light-saturated rates, rRNA cell{sup {minus}1} dropped abruptly. Total cellular RNA was well correlated with the probe-based measure of rRNA and varied in a similar manner with growth rate. Mean cell volume and rRNA concentration were related to growth rate in a manner similar to rRNA cell{sup {minus}1}, although the overall magnitude linear increase in ribosome efficiency with increasing growth rate, which is consistent with the prevailing prokaryotic model at low growth rates. Taken together, these results support the notion that measurements of cellular rRNA content might be useful for estimating in situ growth rates in natural Synechococcus populations.

  2. Does nitrogen fertilizer application rate to corn affect nitrous oxide emissions from the rotated soybean crop?

    PubMed

    Iqbal, Javed; Mitchell, David C; Barker, Daniel W; Miguez, Fernando; Sawyer, John E; Pantoja, Jose; Castellano, Michael J

    2015-05-01

    Little information exists on the potential for N fertilizer application to corn ( L.) to affect NO emissions during subsequent unfertilized crops in a rotation. To determine if N fertilizer application to corn affects NO emissions during subsequent crops in rotation, we measured NO emissions for 3 yr (2011-2013) in an Iowa, corn-soybean [ (L.) Merr.] rotation with three N fertilizer rates applied to corn (0 kg N ha, the recommended rate of 135 kg N ha, and a high rate of 225 kg N ha); soybean received no N fertilizer. We further investigated the potential for a winter cereal rye ( L.) cover crop to interact with N fertilizer rate to affect NO emissions from both crops. The cover crop did not consistently affect NO emissions. Across all years and irrespective of cover crop, N fertilizer application above the recommended rate resulted in a 16% increase in mean NO flux rate during the corn phase of the rotation. In 2 of the 3 yr, N fertilizer application to corn (0-225 kg N ha) did not affect mean NO flux rates from the subsequent unfertilized soybean crop. However, in 1 yr after a drought, mean NO flux rates from the soybean crops that received 135 and 225 kg N ha N application in the corn year were 35 and 70% higher than those from the soybean crop that received no N application in the corn year. Our results are consistent with previous studies demonstrating that cover crop effects on NO emissions are not easily generalizable. When N fertilizer affects NO emissions during a subsequent unfertilized crop, it will be important to determine if total fertilizer-induced NO emissions are altered or only spread across a greater period of time.

  3. Salivary enzymes and exhaled air affect Streptococcus salivarius growth and physiological state in complemented artificial saliva.

    PubMed

    Roger, P; Harn-Arsa, S; Delettre, J; Béal, C

    2011-12-01

    To better understand the phenomena governing the establishment of the oral bacterium Streptococcus salivarius in the mouth, the effect of some environmental factors has been studied in complemented artificial saliva, under oral pH and temperature conditions. Three salivary enzymes at physiological concentrations were tested: peroxidase, lysozyme and amylase, as well as injection of exhaled air. Injection of air containing 5% CO2 and 16% O2 induced a deleterious effect on S. salivarius K12, mainly by increasing redox potential. Addition of lysozyme slightly affected the physiological state of S. salivarius by altering membrane integrity. In contrast, peroxidase was not detrimental as it made it possible to decrease the redox potential. The addition of amylase reduced the specific growth rate of S. salivarius by formation of a complex with amylase and mucins, but led to high final biomass, as a result of enzymatic degradation of some nutrients. Finally, this work demonstrated that salivary enzymes had a slight impact on S. salivarius behaviour. It can thus be concluded that this bacterium was well adapted to in-mouth conditions, as it was able to resist certain salivary enzymes, even if tolerance to expired air was affected, as a result of an increased redox potential. PMID:21892611

  4. Transcriptional modulator ZBED6 affects cell cycle and growth of human colorectal cancer cells.

    PubMed

    Akhtar Ali, Muhammad; Younis, Shady; Wallerman, Ola; Gupta, Rajesh; Andersson, Leif; Sjöblom, Tobias

    2015-06-23

    The transcription factor ZBED6 (zinc finger, BED-type containing 6) is a repressor of IGF2 whose action impacts development, cell proliferation, and growth in placental mammals. In human colorectal cancers, IGF2 overexpression is mutually exclusive with somatic mutations in PI3K signaling components, providing genetic evidence for a role in the PI3K pathway. To understand the role of ZBED6 in tumorigenesis, we engineered and validated somatic cell ZBED6 knock-outs in the human colorectal cancer cell lines RKO and HCT116. Ablation of ZBED6 affected the cell cycle and led to increased growth rate in RKO cells but reduced growth in HCT116 cells. This striking difference was reflected in the transcriptome analyses, which revealed enrichment of cell-cycle-related processes among differentially expressed genes in both cell lines, but the direction of change often differed between the cell lines. ChIP sequencing analyses displayed enrichment of ZBED6 binding at genes up-regulated in ZBED6-knockout clones, consistent with the view that ZBED6 modulates gene expression primarily by repressing transcription. Ten differentially expressed genes were identified as putative direct gene targets, and their down-regulation by ZBED6 was validated experimentally. Eight of these genes were linked to the Wnt, Hippo, TGF-β, EGF receptor, or PI3K pathways, all involved in colorectal cancer development. The results of this study show that the effect of ZBED6 on tumor development depends on the genetic background and the transcriptional state of its target genes.

  5. Incubation temperature affects growth and energy metabolism in blue tit nestlings.

    PubMed

    Nord, Andreas; Nilsson, Jan-Åke

    2011-11-01

    Because the maintenance of proper developmental temperatures during avian incubation is costly to parents, embryos of many species experience pronounced variation in incubation temperature. However, the effects of such temperature variation on nestling development remain relatively unexplored. To investigate this, we artificially incubated wild blue tit (Cyanistes caeruleus L.) clutches at 35.0°, 36.5°, or 38.0°C for two-thirds of the incubation period. We returned clutches to their original nests before hatching and subsequently recorded nestling growth and resting metabolic rate. The length of the incubation period decreased with temperature, whereas hatching success increased. Nestlings from the lowest incubation temperature group had shorter tarsus lengths at 2 weeks of age, but body mass and wing length were not affected by temperature. In addition, nestlings from the lowest temperature group had a significantly higher resting metabolic rate compared with mid- and high-temperature nestlings, which may partly explain observed size differences between the groups. These findings suggest that nest microclimate can influence nestling phenotype, but whether observed differences carry over to later life-history stages remains unknown.

  6. Plant N capture from pulses: effects of pulse size, growth rate, and other soil resources.

    PubMed

    James, J J; Richards, J H

    2005-08-01

    In arid ecosystems, the ability to rapidly capture nitrogen (N) from brief pulses is expected to influence plant growth, survival, and competitive ability. Theory and data suggest that N capture from pulses should depend on plant growth rate and availability of other limiting resources. Theory also predicts trade-offs in plant stress tolerance and ability to capture N from different size pulses. We injected K15NO3, to simulate small and large N pulses at three different times during the growing season into soil around the co-dominant Great Basin species Sarcobatus vermiculatus, Chrysothamnus nauseosus ssp. consimilis, and Distichlis spicata. Soils were amended with water and P in a partial factorial design. As predicted, all study species showed a comparable decline in N capture from large pulses through the season as growth rates slowed. Surprisingly, however, water and P availability differentially influenced the ability of these species to capture N from pulses. Distichlis N capture increased up to tenfold with water addition while Chrysothamnus N capture increased up to threefold with P addition. Sarcobatus N capture was not affected by water or P availability. Opposite to our prediction, Sarcobatus, the most stress tolerant species, captured less N from small pulses but more N from large pulses relative to the other species. These observations suggest that variation in N pulse timing and size can interact with variable soil water and P supply to determine how N is partitioned among co-existing Great Basin species.

  7. A model to predict the thermal reaction norm for the embryo growth rate from field data.

    PubMed

    Girondot, Marc; Kaska, Yakup

    2014-10-01

    The incubation of eggs is strongly influenced by temperature as observed in all species studied to date. For example, incubation duration, sexual phenotype, growth, and performances in many vertebrate hatchlings are affected by incubation temperature. Yet it is very difficult to predict temperature effect based on the temperature within a field nest, as temperature varies throughout incubation. Previous works used egg incubation at constant temperatures in the laboratory to evaluate the dependency of growtProd. Type: FTPh rate on temperature. However, generating such data is time consuming and not always feasible due to logistical and legislative constraints. This paper therefore presents a methodology to extract the thermal reaction norm for the embryo growth rate directly from a time series of incubation temperatures recorded within natural nests. This methodology was successfully applied to the nests of the marine turtle Caretta caretta incubated on Dalyan Beach in Turkey, although it can also be used for any egg-laying species, with some of its limitations being discussed in the paper. Knowledge about embryo growth patterns is also important when determining the thermosensitive period for species with temperature-dependent sex determination. Indeed, in this case, sexual phenotype is sensitive to temperature only during this window of embryonic development.

  8. Food composition influences metabolism, heart rate and organ growth during digestion in Python regius.

    PubMed

    Henriksen, Poul Secher; Enok, Sanne; Overgaard, Johannes; Wang, Tobias

    2015-05-01

    Digestion in pythons is associated with a large increase in oxygen consumption (SDA), increased cardiac output and growth in visceral organs assisting in digestion. The processes leading to the large postprandial rise in metabolism in snakes is subject to opposing views. Gastric work, protein synthesis and organ growth have each been speculated to be major contributors to the SDA. To investigate the role of food composition on SDA, heart rate (HR) and organ growth, 48 ball pythons (Python regius) were fed meals of either fat, glucose, protein or protein combined with carbonate. Our study shows that protein, in the absence or presence of carbonate causes a large SDA response, while glucose caused a significantly smaller SDA response and digestion of fat failed to affect metabolism. Addition of carbonate to the diet to stimulate gastric acid secretion did not increase the SDA response. These results support protein synthesis as a major contributor to the SDA response and show that increased gastric acid secretion occurs at a low metabolic cost. The increase in metabolism was supported by tachycardia caused by altered autonomic regulation as well as an increased non-adrenergic, non-cholinergic (NANC) tone in response to all diets, except for the lipid meal. Organ growth only occurred in the small intestine and liver in snakes fed on a high protein diet.

  9. Insights into Embryo Defenses of the Invasive Apple Snail Pomacea canaliculata: Egg Mass Ingestion Affects Rat Intestine Morphology and Growth

    PubMed Central

    Gimeno, Eduardo J.; Heras, Horacio

    2014-01-01

    Background The spread of the invasive snail Pomacea canaliculata is expanding the rat lungworm disease beyond its native range. Their toxic eggs have virtually no predators and unusual defenses including a neurotoxic lectin and a proteinase inhibitor, presumably advertised by a warning coloration. We explored the effect of egg perivitellin fluid (PVF) ingestion on the rat small intestine morphology and physiology. Methodology/Principal Findings Through a combination of biochemical, histochemical, histopathological, scanning electron microscopy, cell culture and feeding experiments, we analyzed intestinal morphology, growth rate, hemaglutinating activity, cytotoxicity and cell proliferation after oral administration of PVF to rats. PVF adversely affects small intestine metabolism and morphology and consequently the standard growth rate, presumably by lectin-like proteins, as suggested by PVF hemaglutinating activity and its cytotoxic effect on Caco-2 cell culture. Short-term effects of ingested PVF were studied in growing rats. PVF-supplemented diet induced the appearance of shorter and wider villi as well as fused villi. This was associated with changes in glycoconjugate expression, increased cell proliferation at crypt base, and hypertrophic mucosal growth. This resulted in a decreased absorptive surface after 3 days of treatment and a diminished rat growth rate that reverted to normal after the fourth day of treatment. Longer exposure to PVF induced a time-dependent lengthening of the small intestine while switching to a control diet restored intestine length and morphology after 4 days. Conclusions/Significance Ingestion of PVF rapidly limits the ability of potential predators to absorb nutrients by inducing large, reversible changes in intestinal morphology and growth rate. The occurrence of toxins that affect intestinal morphology and absorption is a strategy against predation not recognized among animals before. Remarkably, this defense is rather similar to

  10. Ice Particle Growth Rates Under Upper Troposphere Conditions

    NASA Technical Reports Server (NTRS)

    Peterson, Harold; Bailey, Matthew; Hallett, John

    2010-01-01

    Atmospheric conditions for growth of ice crystals (temperature and ice supersaturation) are often not well constrained and it is necessary to simulate such conditions in the laboratory to investigate such growth under well controlled conditions over many hours. The growth of ice crystals from the vapour in both prism and basal planes was observed at temperatures of -60 C and -70 C under ice supersaturation up to 100% (200% relative humidity) at pressures derived from the standard atmosphere in a static diffusion chamber. Crystals grew outward from a vertical glass filament, thickening in the basal plane by addition of macroscopic layers greater than 2 m, leading to growth in the prism plane by passing of successive layers conveniently viewed by time lapse video.

  11. Ice Crystal Growth Rates Under Upper Troposphere Conditions

    NASA Technical Reports Server (NTRS)

    Peterson, Harold S.; Bailey, Matthew; Hallett, John

    2010-01-01

    Atmospheric conditions for growth of ice crystals (temperature and ice supersaturation) are often not well constrained and it is necessary to simulate such conditions in the laboratory to investigate such growth under well controlled conditions over many hours. The growth of ice crystals from the vapour in both prism and basal planes was observed at temperatures of -60 C and -70 C under ice supersaturation up to 100% (200% relative humidity) at pressures derived from the standard atmosphere in a static diffusion chamber. Crystals grew outward from a vertical glass filament, thickening in the basal plane by addition of macroscopic layers greater than 2 m, leading to growth in the prism plane by passing of successive layers conveniently viewed by time lapse video.

  12. Estimation of the growth curve and heritability of the growth rate for giant panda (Ailuropoda melanoleuca) cubs.

    PubMed

    Che, T D; Wang, C D; Jin, L; Wei, M; Wu, K; Zhang, Y H; Zhang, H M; Li, D S

    2015-03-27

    Giant panda cubs have a low survival rate during the newborn and early growth stages. However, the growth and developmental parameters of giant panda cubs during the early lactation stage (from birth to 6 months) are not well known. We examined the growth and development of giant panda cubs by the Chapman growth curve model and estimated the heritability of the maximum growth rate at the early lactation stage. We found that 83 giant panda cubs reached their maximum growth rate at approximately 75-120 days after birth. The body weight of cubs at 75 days was 4285.99 g. Furthermore, we estimated that the heritability of the maximum growth rate was moderate (h(2) = 0.38). Our study describes the growth and development of giant panda cubs at the early lactation stage and provides valuable growth benchmarks. We anticipate that our results will be a starting point for more detailed research on increasing the survival rate of giant panda cubs. Feeding programs for giant panda cubs need further improvement.

  13. Estimation of the growth curve and heritability of the growth rate for giant panda (Ailuropoda melanoleuca) cubs.

    PubMed

    Che, T D; Wang, C D; Jin, L; Wei, M; Wu, K; Zhang, Y H; Zhang, H M; Li, D S

    2015-01-01

    Giant panda cubs have a low survival rate during the newborn and early growth stages. However, the growth and developmental parameters of giant panda cubs during the early lactation stage (from birth to 6 months) are not well known. We examined the growth and development of giant panda cubs by the Chapman growth curve model and estimated the heritability of the maximum growth rate at the early lactation stage. We found that 83 giant panda cubs reached their maximum growth rate at approximately 75-120 days after birth. The body weight of cubs at 75 days was 4285.99 g. Furthermore, we estimated that the heritability of the maximum growth rate was moderate (h(2) = 0.38). Our study describes the growth and development of giant panda cubs at the early lactation stage and provides valuable growth benchmarks. We anticipate that our results will be a starting point for more detailed research on increasing the survival rate of giant panda cubs. Feeding programs for giant panda cubs need further improvement. PMID:25867378

  14. Antarctic and Arctic land-fast sea ice growth rates: an intercomparison based on stable isotope fractionation measurements

    NASA Astrophysics Data System (ADS)

    Smith, I.; Langhorne, P. J.; Gough, A. J.; Leonard, G. H.; Mahoney, A. R.; Eicken, H.; Van Hale, R.; Trodahl, H. J.; Haskell, T.

    2012-12-01

    The growth rate of sea ice (i.e., the change in sea ice thickness with time) is a critical factor affecting the thermohaline circulation because it determines the amount and timing of salt fluxes to the ocean. Studies of the colonisation of sea ice by microorganisms and the timing of ice-algal blooms, evident at depth horizons in sea ice, also require knowledge of growth rates. However, sea ice thickness and in particular growth rates of level ice are poorly known, mostly due to restrictions in remote sensing of these quantities. Direct measurements through repeated drilling, or the use of temperature probes or ultrasonic pingers (such as on ice mass balance buoys) are resource intensive, and are therefore limited to a few sites. An ideal methodology would allow retrospective reconstruction of sea ice growth rates from the analysis of ice cores taken at the end of the growth season. Previously developed methods have included salinity-based growth rate models, growth history deductions from thick section structural analysis and growth rate models based on the measurement of oxygen isotope fractionation in sea ice. In this presentation, we focus on the latter and compare measured growth rates with those derived from an existing isotope fractionation based model (Eicken, Ant. Res. Ser., 1998). In addition, comparisons are made with measured seasonal changes in δ18O values in Antarctic surface waters. The data presented have been collected for land-fast sea ice from McMurdo Sound, Antarctica and the Chukchi Sea near Barrow, Alaska. These two locations are ideally suited for this intercomparison study because both locations have a long history of sea ice and ocean observations. The Antarctic sea ice data are influenced by the appearance of waters from beneath an ice shelf. The Arctic sea ice growth rate and isotope data are from two sites, and are supported by oceanographic data, including under-ice current speeds, from a nearby mooring. Previous measurements of Arctic

  15. Effects of growth medium and fertilizer rate on the yield response of soybeans exposed to chronic doses of ozone

    SciTech Connect

    Heagle, A.S.; Letchworth, M.B.; Mitchell, C.A.

    1983-01-01

    The objectives were to determine whether wide variation in fertilizer rates or type of growth medium would affect the response of soybeans, Glycine max 'Davis' exposed to chronic doses of ozone (O/sub 3/) in open-top field chambers. Responses to O/sub 3/ were compared for plants grown in the ground or in pots containing an artificial growth medium. In 1977, the yield of plants grown in pots containing soil, sand, and a mixture of perlite, peat moss, and vermiculite was greater than that of plants grown in the ground; in 1978, the reverse was true. However, the percentage yeild loss caused by O/sub 3/ was not affected by the growth medium either year. Separate tests were made for potted plants that received different levels of fertilizer. At moderate fertilizer rates, the yield response to different doses of O/sub 3/ was not significantly affected by fertilizer rate for either year. In 1978, plants with no fertilizer added were severely stunted and even relatively high doses of O/sub 3/ did not further decrease yield. The results suggest that plant response to O/sub 3/ will be fairly uniform over a range of substrate types and fertilizer rates when edaphic conditions are adequate to insure normal plant growth. 17 references, 5 figures, 2 tables.

  16. [Population growth rate of the rotifer Brachionus rotundiformis (Rotifera: Brachionidae) in a two-stage chemostat].

    PubMed

    Cabrera, María I

    2008-09-01

    The population growth rate of the rotifer Brachionus rotundiformis (Rotifera: Brachionidae) in two-stage chemostat. The population growth rates of Brachionus rotundiformis were estimated in two-stage chemostat cultures. Chlorella sorokiniana was supplied continuously from a steady state culture growing with constant illumination on limiting nitrate. Rotifer growth in the second stage was limited by the rate of algal supply. The algal supply rate and rotifer population growth rate were determined by the second-stage dilution rate. The maximum population growth rate in the transient state of B. rotundiformis (1.96 day(-1)) was observed at 2.5 x 10(6) cel/ml of the algae whereas in the steady state the maximum population growth rate (1.09 day(-1)) was similar to the point Hopf's bifurcation predicted by Fussmann and was observed at 1 x 10(6) cel/ml of the algae. In the transient state, the rotifer's growth rate increased and the duplication time decreased at higher algal concentrations, until reaching a peak where the population growth rate begins to decrease. In the steady state, the opposite was true. The growth rates observed in this work are among the highest recorded for this rotifer in continuous cultures.

  17. Factors affecting the corrosion rates of ceramics in coal combustion systems

    SciTech Connect

    Hurley, J.P.

    1995-08-01

    The concentrations of approximately a dozen elements in the products of coal combustion affect the corrosion rates of ceramics used to construct the combustion system. The elements, including H, O, Na, Mg, Al, Si, P, S, Cl, K, Ca, and Fe, affect corrosion rates in three ways: as primary corrodants of the materials, as secondary corrodants that affect the activities of the primary corrodants, and by affecting the mass transport rate of the primary corrodants. A full factorial study of corrosion rates performed by varying the concentrations of these elements would involve X{sup n} tests, where X is the number of variations of each element and n is the number of different elements. For three variations (low, medium, and high concentrations) of each of 12 elements, the number of tests is 531,441 for a single temperature and pressure condition. The numbers can be reduced with the use of a fractional factorial test matrix, but the most effective way to perform corrosion tests is to base them on realistic system conditions. In this paper, the effects of the composition and physical state of the products of coal combustion on ceramic corrosion rates are given along with suggestions of appropriate test conditions for specific system components.

  18. Appropriate Fe (II) Addition Significantly Enhances Anaerobic Ammonium Oxidation (Anammox) Activity through Improving the Bacterial Growth Rate

    PubMed Central

    Liu, Yiwen; Ni, Bing-Jie

    2015-01-01

    The application of anaerobic ammonium oxidation (Anammox) process is often limited by the slow growth rate of Anammox bacteria. As the essential substrate element that required for culturing Anammox sludge, Fe (II) is expected to affect Anammox bacterial growth. This work systematically studied the effects of Fe (II) addition on Anammox activity based on the kinetic analysis of specific growth rate using data from batch tests with an enriched Anammox sludge at different dosing levels. Results clearly demonstrated that appropriate Fe (II) dosing (i.e., 0.09 mM) significantly enhanced the specific Anammox growth rate up to 0.172 d−1 compared to 0.118 d−1 at regular Fe (II) level (0.03 mM). The relationship between Fe (II) concentration and specific Anammox growth rate was found to be well described by typical substrate inhibition kinetics, which was integrated into currently well-established Anammox model to describe the enhanced Anammox growth with Fe (II) addition. The validity of the integrated Anammox model was verified using long-term experimental data from three independent Anammox reactors with different Fe (II) dosing levels. This Fe (II)-based approach could be potentially implemented to enhance the process rate for possible mainstream application of Anammox technology, in order for an energy autarchic wastewater treatment. PMID:25644239

  19. Appropriate Fe (II) Addition Significantly Enhances Anaerobic Ammonium Oxidation (Anammox) Activity through Improving the Bacterial Growth Rate

    NASA Astrophysics Data System (ADS)

    Liu, Yiwen; Ni, Bing-Jie

    2015-02-01

    The application of anaerobic ammonium oxidation (Anammox) process is often limited by the slow growth rate of Anammox bacteria. As the essential substrate element that required for culturing Anammox sludge, Fe (II) is expected to affect Anammox bacterial growth. This work systematically studied the effects of Fe (II) addition on Anammox activity based on the kinetic analysis of specific growth rate using data from batch tests with an enriched Anammox sludge at different dosing levels. Results clearly demonstrated that appropriate Fe (II) dosing (i.e., 0.09 mM) significantly enhanced the specific Anammox growth rate up to 0.172 d-1 compared to 0.118 d-1 at regular Fe (II) level (0.03 mM). The relationship between Fe (II) concentration and specific Anammox growth rate was found to be well described by typical substrate inhibition kinetics, which was integrated into currently well-established Anammox model to describe the enhanced Anammox growth with Fe (II) addition. The validity of the integrated Anammox model was verified using long-term experimental data from three independent Anammox reactors with different Fe (II) dosing levels. This Fe (II)-based approach could be potentially implemented to enhance the process rate for possible mainstream application of Anammox technology, in order for an energy autarchic wastewater treatment.

  20. Appropriate Fe (II) addition significantly enhances anaerobic ammonium oxidation (Anammox) activity through improving the bacterial growth rate.

    PubMed

    Liu, Yiwen; Ni, Bing-Jie

    2015-01-01

    The application of anaerobic ammonium oxidation (Anammox) process is often limited by the slow growth rate of Anammox bacteria. As the essential substrate element that required for culturing Anammox sludge, Fe (II) is expected to affect Anammox bacterial growth. This work systematically studied the effects of Fe (II) addition on Anammox activity based on the kinetic analysis of specific growth rate using data from batch tests with an enriched Anammox sludge at different dosing levels. Results clearly demonstrated that appropriate Fe (II) dosing (i.e., 0.09 mM) significantly enhanced the specific Anammox growth rate up to 0.172 d(-1) compared to 0.118 d(-1) at regular Fe (II) level (0.03 mM). The relationship between Fe (II) concentration and specific Anammox growth rate was found to be well described by typical substrate inhibition kinetics, which was integrated into currently well-established Anammox model to describe the enhanced Anammox growth with Fe (II) addition. The validity of the integrated Anammox model was verified using long-term experimental data from three independent Anammox reactors with different Fe (II) dosing levels. This Fe (II)-based approach could be potentially implemented to enhance the process rate for possible mainstream application of Anammox technology, in order for an energy autarchic wastewater treatment. PMID:25644239

  1. How meristem plasticity in response to soil nutrients and light affects plant growth in four Festuca grass species.

    PubMed

    Sugiyama, Shu-ichi; Gotoh, Minako

    2010-02-01

    Investigation of responses of meristems to environmental conditions is important for understanding the mechanisms and consequences of plant phenotypic plasticity. Here, we examined how meristem plasticity to light and soil nutrients affected leaf growth and relative growth rate (RGR) in fast- and slow-growing Festuca grass species. Activity in shoot apical meristems was measured by leaf appearance rate, and that in leaf meristems by the duration and rate of cell production, which was further divided into single cell cycle time and the number of dividing cells. Light and soil nutrients affected activity in shoot apical meristems similarly. The high nutrient supply increased the number of dividing cells, which was responsible for enhancement of cell production rate; shaded conditions extended the duration of cell production. As a result, leaf length increased under high nutrient and shaded conditions. The RGR was correlated positively with the total meristem size of the shoot under a low nutrient supply, implying inhibition of RGR by cell production under nutrient-limited conditions. Fast-growing species were more plastic for cell production rate and specific leaf area (SLA) but less plastic for RGR than slow-growing species. This study demonstrates that meristem plasticity plays key roles in characterizing environmental responses of plant species.

  2. Prediction of PWSCC in nickel base alloys using crack growth rate models

    SciTech Connect

    Thompson, C.D.; Krasodomski, H.T.; Lewis, N.; Makar, G.L.

    1995-12-31

    The Ford/Andresen slip-dissolution SCC model, originally developed for stainless steel components in BWR environments, has been applied to Alloy 600 and Alloy X-750 tested in deaerated pure water chemistry. A method is described whereby the crack growth rates measured in compact tension specimens can be used to estimate crack growth in a component. Good agreement was found between model prediction and measured SCC in X-750 threaded fasteners over a wide range of temperatures, stresses, and material conditions. Most data support the basic assumption of this model that cracks initiate early in life. The evidence supporting a particular SCC mechanism is mixed. Electrochemical repassivation data and estimates of oxide fracture strain indicate that the slip-dissolution model can account for the observed crack growth rates, provided primary rather than secondary creep rates are used. However, approximately 100 cross-sectional TEM foils of SCC cracks including crack tips reveal no evidence of enhanced plasticity or unique dislocation patterns at the crack tip or along the crack to support a classic slip-dissolution mechanism. No voids, hydrides, or microcracks are found in the vicinity of the crack tips creating doubt about classic hydrogen related mechanisms. The bulk oxide films exhibit a surface oxide which is often different than the oxides found within a crack. Although bulk chromium concentration affects the rate of SCC, analytical data indicates the mechanism does not result from chromium depletion at the grain boundaries. The overall findings support a corrosion/dissolution mechanism but not one necessarily related to slip at the crack tip.

  3. Metabolism correlates with variation in post-natal growth rate among songbirds at three latitudes

    USGS Publications Warehouse

    Ton, Riccardo; Martin, Thomas E.

    2015-01-01

    4. Our results suggest that variation in metabolic rates has an important influence on broad patterns of avian growth rates at a global scale. We suggest further studies that address the ecological and physiological costs and consequences of variation in metabolism and growth rates.

  4. Contributions of vital rates to growth of a protected population of American black bears

    USGS Publications Warehouse

    Mitchell, M.S.; Pacifici, L.B.; Grand, J.B.; Powell, R.A.

    2009-01-01

    Analyses of large, long-lived animals suggest that adult survival generally has the potential to contribute more than reproduction to population growth rate (??), but because survival varies little, high variability in reproduction can have a greater influence. This pattern has been documented for several species of large mammals, but few studies have evaluated such contributions of vital rates to ?? for American black bears (Ursus americanus). We used variance-based perturbation analyses (life table response experiments, LTRE) and analytical sensitivity and elasticity analyses to examine the actual and potential contributions of variation of vital rates to variation in growth rate (??) of a population of black bears inhabiting the Pisgah Bear Sanctuary in the southern Appalachian Mountains of North Carolina, using a 22-year dataset. We found that recruitment varied more than other vital rates; LTRE analyses conducted over several time intervals thus indicated that recruitment generally contributed at least as much as juvenile and adult survival to observed variation in ??, even though the latter 2 vital rates had the greater potential to affect ??. Our findings are consistent with predictions from studies on polar bears (U. maritimus) and grizzly bears (U. arctos), but contrast with the few existing studies on black bears in ways that suggest levels of protection from human-caused mortality might explain whether adult survival or recruitment contribute most to variation in ?? for this species. We hypothesize that ?? is most strongly influenced by recruitment in protected populations where adult survival is relatively high and constant, whereas adult survival will most influence ?? for unprotected populations. ?? 2009 International Association for Bear Research and Management.

  5. Effect of storage temperature on crystal formation rate and growth rate of calcium lactate crystals on smoked Cheddar cheeses.

    PubMed

    Rajbhandari, P; Patel, J; Valentine, E; Kindstedt, P S

    2013-06-01

    Previous studies have shown that storage temperature influences the formation of calcium lactate crystals on vacuum-packaged Cheddar cheese surfaces. However, the mechanisms by which crystallization is modulated by storage temperature are not completely understood. The objectives of this study were to evaluate the effect of storage temperature on smoked Cheddar cheese surfaces for (1) the number of discrete visible crystals formed per unit of cheese surface area; (2) growth rate and shape of discrete crystals (as measured by area and circularity); (3) percentage of total cheese surface area occupied by crystals. Three vacuum-packaged, random weight (∼300 g) retail samples of naturally smoked Cheddar cheese, produced from the same vat of cheese, were obtained from a retail source. The samples were cut parallel to the longitudinal axis at a depth of 10mm from the 2 surfaces to give six 10-mm-thick slabs, 4 of which were randomly assigned to 4 different storage temperature treatments: 1, 5, 10°C, and weekly cycling between 1 and 10°C. Samples were stored for 30 wk. Following the onset of visible surface crystals, digital photographs of surfaces were taken every other week and evaluated by image analysis for number of discrete crystal regions and total surface area occupied by crystals. Specific discrete crystals were chosen and evaluated biweekly for radius, area, and circularity. The entire experiment was conducted in triplicate. The effects of cheese surface, storage temperature, and storage time on crystal number and total crystal area were evaluated by ANOVA, according to a repeated-measures design. The number of discrete crystal regions increased significantly during storage but at different rates for different temperature treatments. Total crystal area also increased significantly during storage, at rates that varied with temperature treatment. Storage temperature did not appear to have a major effect on the growth rates and shapes of the individual crystals

  6. Effects of elevated pressure on rate of photosynthesis during plant growth.

    PubMed

    Takeishi, Hiroyuki; Hayashi, Jun; Okazawa, Atsushi; Harada, Kazuo; Hirata, Kazumasa; Kobayashi, Akio; Akamatsu, Fumiteru

    2013-10-20

    The aim of this study is to investigate the effects of an artificially controlled environment, particularly elevated total pressure, on net photosynthesis and respiration during plant growth. Pressure directly affects not only cells and organelles in leaves but also the diffusion coefficients and degrees of solubility of CO2 and O2. In this study, the effects of elevated total pressure on the rates of net photosynthesis and respiration of a model plant, Arabidopsis thaliana, were investigated in a chamber that newly developed in this study to control the total pressure. The results clearly showed that the rate of respiration decreased linearly with increasing total pressure at a high humidity. The rate of respiration decreased linearly with increasing total pressure up to 0.2 MPa, and increased with increasing total pressure from 0.3 to 0.5 MPa at a low humidity. The rate of net photosynthesis decreased linearly with increasing total pressure under a constant partial pressure of CO2 at 40 Pa. On the other hand, the rate of net photosynthesis was clearly increased by up to 1.6-fold with increasing total pressure and partial pressure of CO2.

  7. The many growth rates and elasticities of populations in random environments.

    PubMed

    Tuljapurkar, Shripad; Horvitz, Carol C; Pascarella, John B

    2003-10-01

    Despite considerable interest in the dynamics of populations subject to temporally varying environments, alternate population growth rates and their sensitivities remain incompletely understood. For a Markovian environment, we compare and contrast the meanings of the stochastic growth rate (lambdaS), the growth rate of average population (lambdaM), the growth rate for average transition rates (lambdaA), and the growth rate of an aggregate represented by a megamatrix (shown here to equal lambdaM). We distinguish these growth rates by the averages that define them. We illustrate our results using data on an understory shrub in a hurricane-disturbed landscape, employing a range of hurricane frequencies. We demonstrate important differences among growth rates: lambdaS lambdaM. We show that stochastic elasticity, ESij, and megamatrix elasticity, EMij, describe a complex perturbation of both means and variances of rates by the same proportion. Megamatrix elasticities respond slightly and stochastic elasticities respond strongly to changing the frequency of disturbance in the habitat (in our example, the frequency of hurricanes). The elasticity EAij of lambdaA does not predict changes in the other elasticities. Because ES, although commonly utilized, is difficult to interpret, we introduce elasticities with a more direct interpretation: ESmu for perturbations of means and ESsigma for variances. We argue that a fundamental tool for studying selection pressures in varying environments is the response of growth rate to vital rates in all habitat states.

  8. Measurements of growth rates of an ice crystal from supercooled heavy water under microgravity conditions: basal face growth rate and tip velocity of a dendrite.

    PubMed

    Yokoyama, Etsuro; Yoshizaki, Izumi; Shimaoka, Taro; Sone, Takehiko; Kiyota, Tatsuo; Furukawa, Yoshinori

    2011-07-14

    The growth of single ice crystals from supercooled heavy water was studied under microgravity conditions in the Japanese Experiment Module ''KIBO'' of the International Space Station (ISS). The velocities of dendrite tips parallel to the a axis and the growth rates of basal faces parallel to the c axis were both analyzed under supercooling ranging from 0.03 to 2.0 K. The velocities of dendrite tips agree with the theory for larger amounts of supercooling when the growth on the basal faces are not zero. At very low supercooling there is no growth on the basal faces. With increasing supercooling the basal faces start to grow, the growth rate changing as a function of supercooling with a power law with an exponent of about 2, with the exponent approaching 1 as supercooling increases further. We interpret the growth on the basal faces as being controlled by two-dimensional nucleation under low supercooling, with a change in the growth kinetics to spiral growth with the aid of screw dislocations with increasing supercooling then to a linear growth law. We discuss the combined effect of tip velocity and basal face kinetics on pattern formation during the growth of ice.

  9. Does a Rater's Familiarity with a Candidate's Pronunciation Affect the Rating in Oral Proficiency Interviews?

    ERIC Educational Resources Information Center

    Carey, Michael D.; Mannell, Robert H.; Dunn, Peter K.

    2011-01-01

    This study investigated factors that could affect inter-examiner reliability in the pronunciation assessment component of speaking tests. We hypothesized that the rating of pronunciation is susceptible to variation in assessment due to the amount of exposure examiners have to nonnative English accents. An inter-rater variability analysis was…

  10. Heart Rate Variability – a Tool to Differentiate Positive and Negative Affective States in Pigs?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The causal neurophysiological processes, such as autonomic nervous system activity, that mediate behavioral and physiological reactivity to an environment have largely been ignored. Heart rate variability (HRV) analysis is a clinical diagnostic tool used to assess affective states (stressful and ple...

  11. Peer Rated Therapeutic Talent and Affective Sensitivity: A Multiple Regression Approach.

    ERIC Educational Resources Information Center

    Jackson, Eugene

    1985-01-01

    Used peer rated measures of Warmth, Understanding and Openness to predict scores on the Kagan Affective Sensitivity Scale-E80 among 66 undergraduates who had participated in interpersonal skills training groups. Results indicated that, as an additively composite index of Therapeutic Talent, they were positively correlated with affective…

  12. Self-Reported ADHD Symptoms among College Students: Item Positioning Affects Symptom Endorsement Rates

    ERIC Educational Resources Information Center

    Mitchell, John T.; Knouse, Laura E.; Nelson-Gray, Rosemery O.; Kwapil, Thomas R.

    2009-01-01

    Objective: The effect of manipulating item positioning on self-reported ADHD symptoms was examined. We assessed whether listing DSM-IV ADHD symptoms serially or interspersed affected (a) the correlation between ADHD symptoms and (b) the rate of symptom endorsement. Method: In Study 1, an undergraduate sample (n = 102) completed a measure that…

  13. Generalised Central Limit Theorems for Growth Rate Distribution of Complex Systems

    NASA Astrophysics Data System (ADS)

    Takayasu, Misako; Watanabe, Hayafumi; Takayasu, Hideki

    2014-04-01

    We introduce a solvable model of randomly growing systems consisting of many independent subunits. Scaling relations and growth rate distributions in the limit of infinite subunits are analysed theoretically. Various types of scaling properties and distributions reported for growth rates of complex systems in a variety of fields can be derived from this basic physical model. Statistical data of growth rates for about 1 million business firms are analysed as a real-world example of randomly growing systems. Not only are the scaling relations consistent with the theoretical solution, but the entire functional form of the growth rate distribution is fitted with a theoretical distribution that has a power-law tail.

  14. Effect of mono- and dichromatic light quality on growth rates and photosynthetic performance of Synechococcus sp. PCC 7002

    SciTech Connect

    Bernstein, Hans C.; Konopka, Allan; Melnicki, Matthew R.; Hill, Eric A.; Kucek, Leo A.; Zhang, Shuyi; Shen, Gaozhong; Bryant, Donald A.; Beliaev, Alex S.

    2014-09-19

    Synechococcus sp. PCC 7002 was grown to steady state in optically thin turbidostat cultures under conditions for which light quantity and quality was systematically varied by modulating the output of narrow-band LEDs. Cells were provided photons absorbed primarily by chlorophyll (680 nm) or phycocyanin (630 nm) as the organism was subjected to four distinct mono- and dichromatic regimes. During cultivation with dichromatic light, growth rates displayed by Synechococcus sp. PCC 7002 were generally proportional to the total incident irradiance at values < 275 µmol photons m-2 s-1 and were not affected by the ratio of 630:680 nm wavelengths. Notably, under monochromatic light conditions, cultures exhibited similar growth rates only when they were irradiated with 630 nm light; cultures irradiated with only 680 nm light grew at rates that were 60 – 70% of those under other light quality regimes at equivalent irradiances. The functionality of photosystem II and associated processes such as maximum rate of photosynthetic electron transport, rate of cyclic electron flow, and rate of dark respiration generally increased as a function of growth rate. Nonetheless, some of the photophysiological parameters measured here displayed distinct patterns with respect to growth rate of cultures adapted to a single wavelength including phycobiliprotein content, which increased under severely light-limited growth conditions. Additionally, the ratio of photosystem II to photosystem I increased approximately 40% over the range of growth rates, although cells grown with 680 nm light only had the highest ratios. These results suggest the presence of effective mechanisms which allow acclimation of Synechococcus sp. PCC 7002 acclimation to different irradiance conditions.

  15. Effect of mono- and dichromatic light quality on growth rates and photosynthetic performance of Synechococcus sp. PCC 7002

    PubMed Central

    Bernstein, Hans C.; Konopka, Allan; Melnicki, Matthew R.; Hill, Eric A.; Kucek, Leo A.; Zhang, Shuyi; Shen, Gaozhong; Bryant, Donald A.; Beliaev, Alexander S.

    2014-01-01

    Synechococcus sp. PCC 7002 was grown to steady state in optically thin turbidostat cultures under conditions for which light quantity and quality was systematically varied by modulating the output of narrow-band LEDs. Cells were provided photons absorbed primarily by chlorophyll (680 nm) or phycocyanin (630 nm) as the organism was subjected to four distinct mono- and dichromatic regimes. During cultivation with dichromatic light, growth rates were generally proportional to the total incident irradiance at values <275 μmol photons m−2 · s−1 and were not affected by the ratio of 630:680 nm wavelengths. Notably, under monochromatic light conditions, cultures exhibited similar growth rates only when they were irradiated with 630 nm light; cultures irradiated with only 680 nm light grew at rates that were 60–70% of those under other light quality regimes at equivalent irradiances. The functionality of photosystem II and associated processes such as maximum rate of photosynthetic electron transport, rate of cyclic electron flow, and rate of dark respiration generally increased as a function of growth rate. Nonetheless, some of the photophysiological parameters measured here displayed distinct patterns with respect to growth rate of cultures adapted to a single wavelength including phycobiliprotein content, which increased under severely light-limited growth conditions. Additionally, the ratio of photosystem II to photosystem I increased ~40% over the range of growth rates, although cells grown with 680 nm light only had the highest ratios. These results suggest the presence of effective mechanisms which allow acclimation of Synechococcus sp. PCC 7002 acclimation to different irradiance conditions. PMID:25285095

  16. Hot spring siliceous stromatolites from Yellowstone National Park: assessing growth rate and laminae formation.

    PubMed

    Berelson, W M; Corsetti, F A; Pepe-Ranney, C; Hammond, D E; Beaumont, W; Spear, J R

    2011-09-01

    Stromatolites are commonly interpreted as evidence of ancient microbial life, yet stromatolite morphogenesis is poorly understood. We apply radiometric tracer and dating techniques, molecular analyses and growth experiments to investigate siliceous stromatolite morphogenesis in Obsidian Pool Prime (OPP), a hot spring in Yellowstone National Park. We examine rates of stromatolite growth and the environmental and/or biologic conditions that affect lamination formation and preservation, both difficult features to constrain in ancient examples. The "main body" of the stromatolite is composed of finely laminated, porous, light-dark couplets of erect (surface normal) and reclining (surface parallel) silicified filamentous bacteria, interrupted by a less-distinct, well-cemented "drape" lamination. Results from dating studies indicate a growth rate of 1-5 cm year(-1) ; however, growth is punctuated. (14)C as a tracer demonstrates that stromatolite cyanobacterial communities fix CO(2) derived from two sources, vent water (radiocarbon dead) and the atmosphere (modern (14)C). The drape facies contained a greater proportion of atmospheric CO(2) and more robust silica cementation (vs. the main body facies), which we interpret as formation when spring level was lower. Systematic changes in lamination style are likely related to environmental forcing and larger scale features (tectonic, climatic). Although the OPP stromatolites are composed of silica and most ancient forms are carbonate, their fine lamination texture requires early lithification. Without early lithification, whether silica or carbonate, it is unlikely that a finely laminated structure representing an ancient microbial mat would be preserved. In OPP, lithification on the nearly diurnal time scale is likely related to temperature control on silica solubility. PMID:21777367

  17. Hot spring siliceous stromatolites from Yellowstone National Park: assessing growth rate and laminae formation.

    PubMed

    Berelson, W M; Corsetti, F A; Pepe-Ranney, C; Hammond, D E; Beaumont, W; Spear, J R

    2011-09-01

    Stromatolites are commonly interpreted as evidence of ancient microbial life, yet stromatolite morphogenesis is poorly understood. We apply radiometric tracer and dating techniques, molecular analyses and growth experiments to investigate siliceous stromatolite morphogenesis in Obsidian Pool Prime (OPP), a hot spring in Yellowstone National Park. We examine rates of stromatolite growth and the environmental and/or biologic conditions that affect lamination formation and preservation, both difficult features to constrain in ancient examples. The "main body" of the stromatolite is composed of finely laminated, porous, light-dark couplets of erect (surface normal) and reclining (surface parallel) silicified filamentous bacteria, interrupted by a less-distinct, well-cemented "drape" lamination. Results from dating studies indicate a growth rate of 1-5 cm year(-1) ; however, growth is punctuated. (14)C as a tracer demonstrates that stromatolite cyanobacterial communities fix CO(2) derived from two sources, vent water (radiocarbon dead) and the atmosphere (modern (14)C). The drape facies contained a greater proportion of atmospheric CO(2) and more robust silica cementation (vs. the main body facies), which we interpret as formation when spring level was lower. Systematic changes in lamination style are likely related to environmental forcing and larger scale features (tectonic, climatic). Although the OPP stromatolites are composed of silica and most ancient forms are carbonate, their fine lamination texture requires early lithification. Without early lithification, whether silica or carbonate, it is unlikely that a finely laminated structure representing an ancient microbial mat would be preserved. In OPP, lithification on the nearly diurnal time scale is likely related to temperature control on silica solubility.

  18. Proliferation rate but not mismatch repair affects the long-term response of colon carcinoma cells to 5FU treatment.

    PubMed

    Choudhary, B; Hanski, M L; Zeitz, M; Hanski, C

    2012-07-01

    The role of mismatch repair (MMR) in the response of colon carcinoma cells to 5-fluorouracil (5FU) is not well understood. In most of the in vitro studies only short-term response was investigated. We focussed here on the influence of MMR status on the mechanism of the short- and long-term response to clinically relevant 5FU concentrations by using isogenic or semiisogenic cell line pairs expressing/nonexpressing the hMLH1 protein, an important component of the MMR system. We show that the lower survival of MMR-proficient than of MMR-deficient cells in the clonogenic survival assay is due to a more frequent early cell arrest and to subsequent senescence. By contrast, the long-term cell growth after treatment, which is also affected by long-term arrest and senescence, is independent from the MMR status. The overall effect on the long-term cell growth is a cumulative result of cell proliferation rate-dependent growth inhibition, apoptosis and necrotic cell death. The main long-term cytotoxic effect of 5FU is the inhibition of growth while apoptosis and the necrotic cell death are minor contributions.

  19. Measuring the stiffness of bacterial cells from growth rates in hydrogels of tunable elasticity

    PubMed Central

    Tuson, Hannah H.; Auer, George K.; Renner, Lars D.; Hasebe, Mariko; Tropini, Carolina; Salick, Max; Crone, Wendy C.; Gopinathan, Ajay; Huang, Kerwyn Casey; Weibel, Douglas B.

    2012-01-01

    Summary Although bacterial cells are known to experience large forces from osmotic pressure differences and their local microenvironment, quantitative measurements of the mechanical properties of growing bacterial cells have been limited. We provide an experimental approach and theoretical framework for measuring the mechanical properties of live bacteria. We encapsulated bacteria in agarose with a user-defined stiffness, measured the growth rate of individual cells, and fit data to a thin-shell mechanical model to extract the effective longitudinal Young's modulus of the cell envelope of Escherichia coli (50–150 MPa), Bacillus subtilis (100–200 MPa), and Pseudomonas aeruginosa (100–200 MPa). Our data provide estimates of cell wall stiffness similar to values obtained via the more labor-intensive technique of atomic force microscopy. To address physiological perturbations that produce changes in cellular mechanical properties, we tested the effect of A22-induced MreB depolymerization on the stiffness of E. coli. The effective longitudinal Young's modulus was not significantly affected by A22 treatment at short time scales, supporting a model in which the interactions between MreB and the cell wall persist on the same time scale as growth. Our technique therefore enables the rapid determination of how changes in genotype and biochemistry affect the mechanical properties of the bacterial envelope. PMID:22548341

  20. The Effect of Load-Line Displacement Rate on the SCC Growth Rate of Nickel Alloys and Mechanistic Implications

    SciTech Connect

    D Morton

    2005-10-19

    A key set of SCC growth experiments was designed to test the hypothesis that deformation/creep is the rate controlling step in LPSCC. These tests were performed on Alloy X-750 AH compact tension specimens at a various constant displacement rates. The deformation/creep rate within the crack tip zone is proportional to the test displacement rate. If crack growth rates were observed to increase with the load-line displacement rate, then this would indicate that deformation/creep is a critical SCC mechanism process. However, results obtained from the load-line displacement tests did not find X-750 AH SCC growth rate to be dependent on the position rate and therefore do not support the assumption that deformation/creep is the rate controlling process in LPSCC. The similarities between the SCC response of X-750, Alloy 600 and EN82H suggests that it is likely that the same SCC process is occurring for all these alloys (i.e., the same rate controlling step) and that deformation based models are also inappropriate for Alloy 600 and EN82H. The strong temperature and coolant hydrogen dependencies exhibited by these alloys make it more likely that nickel alloy LPSCC is controlled by an environmental or corrosion driven process.

  1. Test method for the determination of crack-growth rates and crack growth resistance under cyclic loading

    SciTech Connect

    Yarema, S.Ya.

    1995-05-01

    This article describes the test method for the determination of crack growth rates and crack growth resistance under cyclic loading conditions. The text of the article is limited to two appendices with the following subjects: (1) general requirements for specimens for testing with a constant cycle of the stress intensity factor, and (2) descriptions of the loading fixtures.

  2. Disruption of the lower food web in Lake Ontario: Did it affect alewife growth or condition?

    USGS Publications Warehouse

    O'Gorman, R.; Prindle, S.E.; Lantry, J.R.; Lantry, B.F.

    2008-01-01

    From the early 1980s to the late 1990s, a succession of non-native invertebrates colonized Lake Ontario and the suite of consequences caused by their colonization became known as "food web disruption". For example, the native burrowing amphipod Diporeia spp., a key link in the profundal food web, declined to near absence, exotic predaceous cladocerans with long spines proliferated, altering the zooplankton community, and depth distributions of fishes shifted. These changes had the potential to affect growth and condition of planktivorous alewife Alosa pseudoharengus, the most abundant fish in the lake. To determine if food web disruption affected alewife, we used change-point analysis to examine alewife growth and adult alewife condition during 1976-2006 and analysis-of-variance to determine if values between change points differed significantly. There were no change points in growth during the first year of life. Of three change points in growth during the second year of life, one coincided with the shift in springtime distribution of alewife to deeper water but it was not associated with a significant change in growth. After the second year of life, no change points in growth were evident, although growth in the third year of life spiked in those years when Bythotrephes, the largest of the exotic cladocerans, was abundant suggesting that it was a profitable prey item for age-2 fish. We detected two change points in condition of adult alewife in fall, but the first occurred in 1981, well before disruption began. A second change point occurred in 2003, well after disruption began. After the springtime distribution of alewife shifted deeper during 1992-1994, growth in the first two years of life became more variable, and growth in years of life two and older became correlated (P < 0.05). In conclusion, food web disruption had no negative affect on growth and condition of alewife in Lake Ontario although it appears to have resulted in growth in the first two years of

  3. Environmental versus genetic influences on growth rates of the corals Pocillopora eydouxi and Porites lobata (Anthozoa: Scleractinia)

    USGS Publications Warehouse

    Smith, L.W.; Wirshing, H.H.; Baker, A.C.; Birkeland, C.

    2008-01-01

    Reciprocal transplant experiments of the corals Pocillopora eydouxi Milne Edwards & Haime and Porites lobata Dana were carried out for an 18-month period from September 2004 to March 2006 between two back reef pools on Ofu Island, American Samoa, to test environmental versus genetic effects on skeletal growth rates. Skeletal growth of P. eydouxi showed environmental but not genetic effects, resulting in doubling of growth in Pool 300 compared with Pool 400. There were no environmental or genetic effects on skeletal growth of P. lobata. Pool 300 had more frequent and longer durations of elevated seawater temperatures than Pool 400, characteristics likely to decrease rather than increase skeletal growth. Pool 300 also had higher nutrient levels and flow velocities than Pool 400, characteristics that may increase skeletal growth. However, higher nutrient levels would be expected to increase skeletal growth in both species, but there was no difference between the pools in P. lobata growth. P. eydouxi is much more common in high-energy environments than P. lobata; thus the higher flow velocities in Pool 300 than in Pool 400 may have positively affected skeletal growth of P. eydouxi while not having a detectable effect on P. lobata. The greater skeletal growth of P. eydouxi in Pool 300 occurred despite the presence of clade D zooxanthellae in several source colonies in Pool 300, a genotype known to result in greater heat resistance but slower skeletal growth. Increased skeletal growth rates in higher water motion may provide P. eydouxi a competitive advantage in shallow, high-energy enviromnents where competition for space is intense. ?? 2008 by University of Hawai'i Press. All rights reserved.

  4. Effect of growth rate and substrate limitation on the composition and structure of the cell wall of Saccharomyces cerevisiae

    PubMed Central

    McMurrough, I.; Rose, A. H.

    1967-01-01

    1. A study was made of the composition and structure of walls isolated from yeast grown in continuous culture at different rates, under three conditions of glucose limitation in which the concentrations of glucose and ammonium sulphate in the medium and the oxygen-transfer rate in the culture were varied, and one condition of NH4+ limitation. 2. The contents of total glucan and total mannan in the walls were relatively little affected by the growth rate under any of the four sets of conditions. The phosphorus and protein contents of walls from yeast grown under each of the four conditions increased as the growth rate was decreased. Walls from yeast grown under NH4+ limitation contained only half as much protein as walls from cells grown under glucose limitation. The proportion of lipid was greatest in walls from yeast grown under NH4+ limitation. 3. A procedure was devised for fractionating isolated walls, based on the ease with which the glucan and mannan were extracted with water and with hot and cold 6% (w/v) potassium hydroxide solution. The percentage of glucan, mannan, protein and phosphorus in each of the fractions was affected by the rate of growth and by the nature of the substrate limitation. 4. The β-fructofuranosidase activities of yeast grown under glucose limitation increased as the growth rate was lowered, but decreased at very low growth rates. The effects at low growth rates were probably due to repression of enzyme synthesis by residual glucose in the culture filtrate. The β-fructofuranosidase activities of yeast grown under NH4+ limitation were much lower than those from yeast grown under any of the conditions of glucose limitation. 5. Yeast cells grown at any of the rates under NH4+ limitation were longer and thinner than those grown at the same rate under any of the conditions of glucose limitation. Mean cell volumes were dependent on growth rate but not on the nature of the substrate limitation. 6. Electron micrographs of thin sections of

  5. Geometric analysis and estimation of the growth rate gradient on gastropod shells.

    PubMed

    Noshita, Koji; Shimizu, Keisuke; Sasaki, Takenori

    2016-01-21

    The morphology of gastropod shells provides a record of the growth rate at the aperture of the shell, and molecular biological studies have shown that the growth rate gradient along the aperture of a gastropod shell can be closely related to gene expression at the aperture. Here, we develop a novel method for deriving microscopic growth rates from the macroscopic shapes of gastropod shells. The growth vector map of a shell provides information on the growth rate gradient as a vector field along the aperture, over the growth history. However, it is difficult to estimate the growth vector map directly from the macroscopic shape of a specimen, because the degree of freedom of the growth vector map is very high. In order to overcome this difficulty, we develop a method of estimating the growth vector map based on a growing tube model, where the latter includes fewer parameters to be estimated. In addition, we calculate an aperture map specifying the magnitude of the growth vector at each location, which can be compared with the expression levels of several genes or proteins that are important in morphogenesis. Finally, we show a concrete example of how macroscopic shell shapes evolve in a morphospace when microscopic growth rate gradient changes.

  6. A review of modifying factors affecting usage of diagnostic rating scales in concussion management.

    PubMed

    Dessy, Alexa; Rasouli, Jonathan; Gometz, Alex; Choudhri, Tanvir

    2014-07-01

    Sport-related concussion has gained increasing recognition as a result of recent legislation, public health initiatives and media coverage. Moreover, there have been substantial paradigm shifts in the management of concussion. This article will discuss the variables that affect the use of diagnostic rating scales such as ImPACT and SCAT in the current management of concussed individuals. Specifically, patient-specific modifying factors affecting test interpretation, including age, gender, fitness level, psychiatric conditions, learning disorders and other components of medical history will be addressed, as well as methodological concerns with baseline testing. PMID:24908218

  7. A Minimalistic Resource Allocation Model to Explain Ubiquitous Increase in Protein Expression with Growth Rate

    PubMed Central

    Keren, Leeat; Segal, Eran; Milo, Ron

    2016-01-01

    Most proteins show changes in level across growth conditions. Many of these changes seem to be coordinated with the specific growth rate rather than the growth environment or the protein function. Although cellular growth rates, gene expression levels and gene regulation have been at the center of biological research for decades, there are only a few models giving a base line prediction of the dependence of the proteome fraction occupied by a gene with the specific growth rate. We present a simple model that predicts a widely coordinated increase in the fraction of many proteins out of the proteome, proportionally with the growth rate. The model reveals how passive redistribution of resources, due to active regulation of only a few proteins, can have proteome wide effects that are quantitatively predictable. Our model provides a potential explanation for why and how such a coordinated response of a large fraction of the proteome to the specific growth rate arises under different environmental conditions. The simplicity of our model can also be useful by serving as a baseline null hypothesis in the search for active regulation. We exemplify the usage of the model by analyzing the relationship between growth rate and proteome composition for the model microorganism E.coli as reflected in recent proteomics data sets spanning various growth conditions. We find that the fraction out of the proteome of a large number of proteins, and from different cellular processes, increases proportionally with the growth rate. Notably, ribosomal proteins, which have been previously reported to increase in fraction with growth rate, are only a small part of this group of proteins. We suggest that, although the fractions of many proteins change with the growth rate, such changes may be partially driven by a global effect, not necessarily requiring specific cellular control mechanisms. PMID:27073913

  8. Effect of high sedimentation rates on surface sediment dynamics and mangrove growth in the Porong River, Indonesia.

    PubMed

    Sidik, Frida; Neil, David; Lovelock, Catherine E

    2016-06-15

    Large quantities of mud from the LUSI (Lumpur Sidoarjo) volcano in northeastern Java have been channeled to the sea causing high rates of sediment delivery to the mouth of the Porong River, which has a cover of natural and planted mangroves. This study investigated how the high rates of sediment delivery affected vertical accretion, surface elevation change and the growth of Avicennia sp., the dominant mangrove species in the region. During our observations in 2010-2011 (4-5years after the initial volcanic eruption), very high rates of sedimentation in the forests at the mouth of the river gave rise to high vertical accretion of over 10cmy(-1). The high sedimentation rates not only resulted in reduced growth of Avicennia sp. mangrove trees at the two study sites at the Porong River mouth, but also gave rise to high soil surface elevation gains. PMID:27048688

  9. Effect of high sedimentation rates on surface sediment dynamics and mangrove growth in the Porong River, Indonesia.

    PubMed

    Sidik, Frida; Neil, David; Lovelock, Catherine E

    2016-06-15

    Large quantities of mud from the LUSI (Lumpur Sidoarjo) volcano in northeastern Java have been channeled to the sea causing high rates of sediment delivery to the mouth of the Porong River, which has a cover of natural and planted mangroves. This study investigated how the high rates of sediment delivery affected vertical accretion, surface elevation change and the growth of Avicennia sp., the dominant mangrove species in the region. During our observations in 2010-2011 (4-5years after the initial volcanic eruption), very high rates of sedimentation in the forests at the mouth of the river gave rise to high vertical accretion of over 10cmy(-1). The high sedimentation rates not only resulted in reduced growth of Avicennia sp. mangrove trees at the two study sites at the Porong River mouth, but also gave rise to high soil surface elevation gains.

  10. Exploring Latent Class Based on Growth Rates in Number Sense Ability

    ERIC Educational Resources Information Center

    Kim, Dongil; Shin, Jaehyun; Lee, Kijyung

    2013-01-01

    The purpose of this study was to explore latent class based on growth rates in number sense ability by using latent growth class modeling (LGCM). LGCM is one of the noteworthy methods for identifying growth patterns of the progress monitoring within the response to intervention framework in that it enables us to analyze latent sub-groups based not…

  11. Mir-373 affects human lung cancer cells' growth and its E-cadherin expression.

    PubMed

    Wu, Weihua; He, Xiaoyan; Kong, Jing; Ye, Bin

    2012-01-01

    The aims of this study was to elucidate whether the expression of E-cadherin can be affected by the recombinant has-mir-373 eukaryotic expression plasmid vector through tests in vitro, and to analyze the relationship between the expression of E-cadherin and tumor growth. According to the has-mir-373 sequence in miRBase database, two template DNA sequences were designed. The has-mir-373 sequence and a control sequence were synthesized and cloned into pGenesil-1 eukaryotic expression plasmid vector. The recombinant plasmids were transfected into human lung cancer A549 cells by liposome-mediated method. The mir-373 expression in A549 cells was detected by using real-time quantitative polymerase chain reaction (real-time PCR). MTT (methyl thiazolyl tetrazolium) was used to analyze the growth of cancer cell cycle. RT-PCR and Western blotting were used to evaluate the levels of E-cadherin mRNA and protein expression, respectively. The expression of E-cadherin in cells was determined by immunocytochemistry. The mobility capability of transfected cells were evaluated by using wound healing assay in vitro. The fluorescent light was observed under fluorescent microscope. RT-PCR indicated that the mRNA of E-cadherin increased, and the Western blotting results also displayed that mir-373 promoted the expression of the E-cadherin protein. Compared with the control groups, MTT method and wound healing assay demonstrated that both the growth rate and migration of A549 cells transfected with the recombinant has-mir-373 eukaryotic expression plasmid was also decreased significantly (p < 0.001). The differences between the other two control groups were not significant (p > 0.05). The immunocytochemistry demonstrated a significant increase of E-cadherin protein levels in the cells transfected with mir-373, but not in the cells of the control group. Mir-373 could increase the expression levels of the E-cadherin and decrease the migration ability of human lung cancer A549 cells in

  12. Functional traits explain light and size response of growth rates in tropical tree species.

    PubMed

    Rüger, Nadja; Wirth, Christian; Wright, S Joseph; Condit, Richard

    2012-12-01

    Relationships between functional traits and average or potential demographic rates have provided insight into the functional constraints and trade-offs underlying life-history strategies of tropical tree species. We have extended this framework by decomposing growth rates of -130 000 trees of 171 Neotropical tree species into intrinsic growth and the response of growth to light and size. We related these growth characteristics to multiple functional traits (wood density, adult stature, seed mass, leaf traits) in a hierarchical Bayesian model that accounted for measurement error and intraspecific variability of functional traits. Wood density was the most important trait determining all three growth characteristics. Intrinsic growth rates were additionally strongly related to adult stature, while all traits contributed to light response. Our analysis yielded a predictive model that allows estimation of growth characteristics for rare species on the basis of a few easily measurable morphological traits.

  13. Keeping Pace with Your Eating: Visual Feedback Affects Eating Rate in Humans

    PubMed Central

    Bosworth, Matthew L.; Godinot, Nicolas; Martin, Nathalie; Rogers, Peter J.; Brunstrom, Jeffrey M.

    2016-01-01

    Deliberately eating at a slower pace promotes satiation and eating quickly has been associated with a higher body mass index. Therefore, understanding factors that affect eating rate should be given high priority. Eating rate is affected by the physical/textural properties of a food, by motivational state, and by portion size and palatability. This study explored the prospect that eating rate is also influenced by a hitherto unexplored cognitive process that uses ongoing perceptual estimates of the volume of food remaining in a container to adjust intake during a meal. A 2 (amount seen; 300ml or 500ml) x 2 (amount eaten; 300ml or 500ml) between-subjects design was employed (10 participants in each condition). In two ‘congruent’ conditions, the same amount was seen at the outset and then subsequently consumed (300ml or 500ml). To dissociate visual feedback of portion size and actual amount consumed, food was covertly added or removed from a bowl using a peristaltic pump. This created two additional ‘incongruent’ conditions, in which 300ml was seen but 500ml was eaten or vice versa. We repeated these conditions using a savoury soup and a sweet dessert. Eating rate (ml per second) was assessed during lunch. After lunch we assessed fullness over a 60-minute period. In the congruent conditions, eating rate was unaffected by the actual volume of food that was consumed (300ml or 500ml). By contrast, we observed a marked difference across the incongruent conditions. Specifically, participants who saw 300ml but actually consumed 500ml ate at a faster rate than participants who saw 500ml but actually consumed 300ml. Participants were unaware that their portion size had been manipulated. Nevertheless, when it disappeared faster or slower than anticipated they adjusted their rate of eating accordingly. This suggests that the control of eating rate involves visual feedback and is not a simple reflexive response to orosensory stimulation. PMID:26828922

  14. Salinity fluctuation of the brine discharge affects growth and survival of the seagrass Cymodocea nodosa.

    PubMed

    Garrote-Moreno, A; Fernández-Torquemada, Y; Sánchez-Lizaso, J L

    2014-04-15

    The increase of seawater desalination plants may affect seagrasses as a result of its hypersaline effluents. There are some studies on the salinity tolerance of seagrasses under controlled laboratory conditions, but few have been done in situ. To this end, Cymodocea nodosa shoots were placed during one month at four localities: two close to a brine discharge; and the other two not affected by the discharge, and this experiment was repeated four times. The results obtained showed a decrease in growth and an increased mortality at the localities affected by the brine discharge. An increase was detected in the percentage of horizontal shoots in respect to vertical shoots at the impacted localities. It is probably that not only the average salinity, but also the constant salinity fluctuations and slightly higher temperatures associated with the brine that may have caused physiological stress thus reducing C. nodosa growth and survival.

  15. Growth Rate Lags Again in Graduate Schools' International Admissions

    ERIC Educational Resources Information Center

    McCormack, Eugene

    2008-01-01

    The number of foreign students admitted to graduate schools at American colleges and universities grew in 2008 for the fourth straight year, but the rate of increase over the previous year declined for the third consecutive year, according to survey results released by the Council of Graduate Schools. Based on previous years' data, this year's…

  16. Gradient of Growth, Spontaneous Changes in Growth Rate and Response to Auxin of Excised Hypocotyl Segments of Phaseolus aureus 1

    PubMed Central

    Prat, Roger

    1978-01-01

    Spontaneous growth was studied in excised mung bean (Phaseolus aureus Roxb.) hypocotyl segments. Measurements were made with a growth-recording apparatus using displacement transducers on single 5- to 6-millimeter samples excised from the growth zone immediately below the hook. Even for a given zone and under controlled experimental conditions, there are differences in the spontaneous growth of individual explants. Nevertheless, in every case, two phases of endogenous acceleration are found at 15 to 20 minutes, and 120 to 150 minutes after excision. Accelerations were separated by steady growth phases. Knowledge of the spontaneous growth curve appears important for the choice of the time of application of experimental stimuli. Auxin was added at various times after excision (0 to 6 hours). The classical biphasic response to auxin was obtained when the hormone was added during a steady phase of growth. However, the response was difficult to interpret when the hormone was added during an acceleration phase. Spontaneous and indoleacetic acid-induced growth were studied along the hypocotyl. Spontaneous growth rate and growth potential revealed by indoleacetic acid changed markedly along the growth gradient. The nature of spontaneous changes according to experimental time and state of differentiation of the cells is discussed. PMID:16660473

  17. Influence of Polymers on the Crystal Growth Rate of Felodipine: Correlating Adsorbed Polymer Surface Coverage to Solution Crystal Growth Inhibition.

    PubMed

    Schram, Caitlin J; Taylor, Lynne S; Beaudoin, Stephen P

    2015-10-20

    The bioavailability of orally administered drugs that exhibit poor aqueous solubility can be enhanced with the use of supersaturating dosage forms. Stabilization of these forms by preventing or inhibiting crystallization in solution is an important area of study. Polymers can be used to stabilize supersaturated systems; however, the properties that impact their effectiveness as crystal growth rate inhibitors are not yet fully understood. In this study, the impact of various polymers on the crystal growth rate of felodipine and the conformation of these polymers adsorbed to crystalline felodipine was investigated in order to gain a mechanistic understanding of crystal growth inhibition. It was determined that polymer hydrophobicity impacted polymer adsorption as well as adsorbed polymer conformation. Polymer conformation impacts its surface coverage, which was shown to directly correlate to the polymer's effectiveness as a growth rate inhibitor. By modeling this correlation, it is possible to predict polymer effectiveness given the surface coverage of the polymer.

  18. Temperature effect on proliferation and differentiation of satellite cells from turkeys with different growth rates.

    PubMed

    Clark, D L; Coy, C S; Strasburg, G M; Reed, K M; Velleman, S G

    2016-04-01

    Poultry selected for growth have an inefficient thermoregulatory system and are more sensitive to temperature extremes. Satellite cells are precursors to skeletal muscle and mediate all posthatch muscle growth. Their physiological functions are affected by temperature. The objective of the current study was to determine how temperature affects satellite cells isolated from the pectoralis major (p. major) muscle (breast muscle) of turkeys selected for increased 16 wk body weight (F line) in comparison to a randombred control line (RBC2) from which the F line originated. Pectoralis major muscle satellite cells were thermally challenged by culturing between 33°C and 43°C to analyze the effects of cold and heat on proliferation and differentiation as compared to control temperature of 38°C. Expression levels of myogenic regulatory factors: myogenic differentiation factor 1 (MYOD1) and myogenin (MYOG) were quantified by quantitative polymerase chain reaction (qPCR). At all sampling times, proliferation increased at a linear rate across temperature in both the RBC2 and F lines. Differentiation also increased at a linear rate across temperature from 33 to 41°C at all sampling times in both the F and RBC2 lines. Satellite cells isolated from F line turkeys were more sensitive to both hot and cold temperatures as proliferation and differentiation increased to a greater extent across temperature (33 to 43°C) when compared with the RBC2 line. Expression of MYOD1 and MYOG increased as temperatures increased from 33 to 41°C at all sampling times in both the F and RBC2 lines. These results demonstrate that satellite cell function is sensitive to both cold and hot temperatures and p. major muscle satellite cells from F line turkeys are more sensitive to temperature extremes than RBC2 satellite cells.

  19. Temperature effect on proliferation and differentiation of satellite cells from turkeys with different growth rates.

    PubMed

    Clark, D L; Coy, C S; Strasburg, G M; Reed, K M; Velleman, S G

    2016-04-01

    Poultry selected for growth have an inefficient thermoregulatory system and are more sensitive to temperature extremes. Satellite cells are precursors to skeletal muscle and mediate all posthatch muscle growth. Their physiological functions are affected by temperature. The objective of the current study was to determine how temperature affects satellite cells isolated from the pectoralis major (p. major) muscle (breast muscle) of turkeys selected for increased 16 wk body weight (F line) in comparison to a randombred control line (RBC2) from which the F line originated. Pectoralis major muscle satellite cells were thermally challenged by culturing between 33°C and 43°C to analyze the effects of cold and heat on proliferation and differentiation as compared to control temperature of 38°C. Expression levels of myogenic regulatory factors: myogenic differentiation factor 1 (MYOD1) and myogenin (MYOG) were quantified by quantitative polymerase chain reaction (qPCR). At all sampling times, proliferation increased at a linear rate across temperature in both the RBC2 and F lines. Differentiation also increased at a linear rate across temperature from 33 to 41°C at all sampling times in both the F and RBC2 lines. Satellite cells isolated from F line turkeys were more sensitive to both hot and cold temperatures as proliferation and differentiation increased to a greater extent across temperature (33 to 43°C) when compared with the RBC2 line. Expression of MYOD1 and MYOG increased as temperatures increased from 33 to 41°C at all sampling times in both the F and RBC2 lines. These results demonstrate that satellite cell function is sensitive to both cold and hot temperatures and p. major muscle satellite cells from F line turkeys are more sensitive to temperature extremes than RBC2 satellite cells. PMID:26769270

  20. Multilevel factor analysis of smokers' real-time negative affect ratings while quitting.

    PubMed

    Bold, Krysten W; Witkiewitz, Katie; McCarthy, Danielle E

    2016-09-01

    Smoking is a serious public health problem, and accurate real-time assessment of risk factors associated with smoking is critical to understanding smoking relapse. Negative affect is often described as a critical risk factor related to smoking relapse, and ecological momentary assessment (EMA) methods have been widely used to study real-time relations between negative affect and smoking. However, the factor structure of momentary negative affect ratings is unknown. The current investigation examined the multilevel factor structure and internal consistency of an EMA measure of negative affect. Daily assessments were collected for 1 week prequit and 3 weeks postquit from 113 adult daily smokers receiving nicotine replacement therapy and counseling to quit smoking. Results supported a 2-factor model with correlated but distinct agitation and distress factors, rather than a single-factor model of negative affect. The agitation factor was indicated by these items: impatient, tense/anxious, restless. The distress factor was indicated by these items: sad/depressed, upset, distressed. The 2-factor model had acceptable model fit and consistent factor loadings across 3 separate cessation phases: prequit, postquit with recent smoking, and postquit without recent smoking. The 2 factors were highly correlated, showed good internal consistency, and showed strong associations with theoretically relevant smoking and affect variables. Agitation was more strongly related to urge to smoke, and distress was more strongly related to recent stress. This study provides support for a 2-factor model of an EMA measure of negative affect and highlights distinct facets that may be useful for future investigations of affect and smoking. (PsycINFO Database Record PMID:27536999

  1. The effect of density gradient on the growth rate of relativistic Weibel instability

    NASA Astrophysics Data System (ADS)

    Mahdavi, M.; Khodadadi Azadboni, F.

    2014-02-01

    In this paper, the effect of density gradient on the Weibel instability growth rate is investigated. The density perturbations in the near corona fuel, where temperature anisotropy, η, is larger than the critical temperature anisotropy, ηc, (η > ηc), enhances the growth rate of Weibel instability due to the sidebands coupled with the electron oscillatory velocity. But for η < ηc, the thermal spread of the energetic electrons reduces the growth rate. Also, the growth rate can be reduced if the relativistic parameter (Lorentz factor) is sufficiently large, γ > 2. The analysis shows that relativistic effects and density gradient tend to stabilize the Weibel instability. The growth rate can be reduced by 88% by reducing η by a factor of 100 and increasing relativistic parameter by a factor of 3.

  2. Two-Way Selection for Growth Rate in the Common Carp (CYPRINUS CARPIO L.)

    PubMed Central

    Moav, R.; Wohlfarth, G.

    1976-01-01

    The domesticated European carp was subjected to a two-way selection for growth rate. Five generations of mass selection for faster growth rate did not yield any response, but subsequent selection between groups (families) resulted in considerable progress while maintaining a large genetic variance. Selection for slow growth rate yielded relatively strong response for the first three generations. Random-bred control lines suffered from strong inbreeding depression and when two lines were crossed, the F1 showed a high degree of heterosis. Selection was performed on pond-raised fish, but growth rate was also tested in cages. A strong pond-cage genetic interaction was found. A theoretical explanation was suggested involving overdominance for fast growth rate and amplification through competition of intra-group but not inter-group variation. PMID:1248737

  3. The effect of density gradient on the growth rate of relativistic Weibel instability

    SciTech Connect

    Mahdavi, M.; Khodadadi Azadboni, F.

    2014-02-15

    In this paper, the effect of density gradient on the Weibel instability growth rate is investigated. The density perturbations in the near corona fuel, where temperature anisotropy, η, is larger than the critical temperature anisotropy, η{sub c}, (η > η{sub c}), enhances the growth rate of Weibel instability due to the sidebands coupled with the electron oscillatory velocity. But for η < η{sub c}, the thermal spread of the energetic electrons reduces the growth rate. Also, the growth rate can be reduced if the relativistic parameter (Lorentz factor) is sufficiently large, γ > 2. The analysis shows that relativistic effects and density gradient tend to stabilize the Weibel instability. The growth rate can be reduced by 88% by reducing η by a factor of 100 and increasing relativistic parameter by a factor of 3.

  4. The relationship between the growth rate and the lifetime in carbon nanotube synthesis

    NASA Astrophysics Data System (ADS)

    Chen, Guohai; Davis, Robert C.; Kimura, Hiroe; Sakurai, Shunsuke; Yumura, Motoo; Futaba, Don N.; Hata, Kenji

    2015-05-01

    We report an inverse relationship between the carbon nanotube (CNT) growth rate and the catalyst lifetime by investigating the dependence of growth kinetics for ~330 CNT forests on the carbon feedstock, carbon concentration, and growth temperature. We found that the increased growth temperature led to increased CNT growth rate and shortened catalyst lifetime for all carbon feedstocks, following an inverse relationship of a fairly constant maximum height. For the increased carbon concentration, the carbon feedstocks fell into two groups where ethylene/butane showed an increased/decreased growth rate and a decreased/increased lifetime indicating different rate-limiting growth processes. In addition, this inverse relationship held true for different types of CNTs synthesized by various chemical vapor deposition techniques and continuously spanned a 1000-times range in both the growth rate and catalyst lifetime, indicating the generality and fundamental nature of this behavior originating from the growth mechanism of CNTs itself. These results suggest that it would be fundamentally difficult to achieve a fast growth with a long lifetime.

  5. The relationship between the growth rate and the lifetime in carbon nanotube synthesis.

    PubMed

    Chen, Guohai; Davis, Robert C; Kimura, Hiroe; Sakurai, Shunsuke; Yumura, Motoo; Futaba, Don N; Hata, Kenji

    2015-05-21

    We report an inverse relationship between the carbon nanotube (CNT) growth rate and the catalyst lifetime by investigating the dependence of growth kinetics for ∼330 CNT forests on the carbon feedstock, carbon concentration, and growth temperature. We found that the increased growth temperature led to increased CNT growth rate and shortened catalyst lifetime for all carbon feedstocks, following an inverse relationship of a fairly constant maximum height. For the increased carbon concentration, the carbon feedstocks fell into two groups where ethylene/butane showed an increased/decreased growth rate and a decreased/increased lifetime indicating different rate-limiting growth processes. In addition, this inverse relationship held true for different types of CNTs synthesized by various chemical vapor deposition techniques and continuously spanned a 1000-times range in both the growth rate and catalyst lifetime, indicating the generality and fundamental nature of this behavior originating from the growth mechanism of CNTs itself. These results suggest that it would be fundamentally difficult to achieve a fast growth with a long lifetime. PMID:25913386

  6. Dietary fish oil affects food intake, growth and hematologic values of weanling rats.

    PubMed

    Domínguez, Z; Bosch, V

    1994-06-01

    The object of this study was to evaluate the effect of increasing amounts of dietary fish oil on growth and hematological variables of the weanling male Sprague-Dawley rat. Animals were fed diets containing either fish oil (FO) or sesame oil (SO) at 5, 10 or 15% (w/w) for 31 d. Growth retardation and reduced food intake was noted in groups fed FO. Hemoglobin (Hb) concentration diminished when the dietary FO was above 5% (w/w). FO is a poor source of (n-6) fatty acids. We postulate that a partial deficiency in (n-6) polyenic family, is a consequence of the increasing amounts of FO in the diets, that may affect growth and erytropoiesis. In this report we show evidence supporting the hypothesis that diets enriched with fish oil can alter normal growth and induced hematological changes in the male weanling rat.

  7. The ability of Salmonella to enter mammalian cells is affected by bacterial growth state.

    PubMed Central

    Lee, C A; Falkow, S

    1990-01-01

    We have examined the effect of different growth conditions on the ability of Salmonella to interact with Madin-Darby canine kidney cells. Two growth conditions that affect the expression of Salmonella adherence and invasiveness have been identified. First, bacteria lose their invasiveness in the stationary phase of growth. Second, bacteria growing in oxygen-limited growth conditions are induced for adherence and invasiveness, whereas those growing aerobically are relatively nonadherent and noninvasive. Salmonella from cultures aerated with gas mixtures containing 0% or 1% oxygen were 6- to 70-fold more adherent and invasive than those from cultures aerated with a gas mixture containing 20% oxygen. The Salmonella typhimurium oxrA gene that is required for the anaerobic induction of many proteins is not involved in the regulation of Salmonella invasiveness. We speculate that oxygen limitation might be an environmental cue that triggers the expression of Salmonella invasiveness within the intestinal lumen and other tissues. Images PMID:2349239

  8. Dietary zinc affects concentrations of insulin, insulin-like growth factor-I and growth hormone in lambs

    SciTech Connect

    Droke, E.A.; Spears, J.W.; Armstrong, J.D. )

    1991-03-15

    Glucose tolerance and concentrations of insulin, growth hormone (GH) and insulin-like growth factor-I (IGF-I) were evaluated in lambs deficient, marginal or adequate in zinc (Zn). Lambs were fed a semipurified diet that contained either 3.7, 8.7, or 43.7 mg Zn/kg. Zinc deficiency resulted in lower serum insulin levels 1 h after feeding while levels in marginal lambs were not different from that of adequate lambs. Dietary Zn did not affect plasma glucose post feeding. One h after IV glucose administration plasma glucose concentrations were lower in deficient lambs compared to adequate lambs; marginal lambs had intermediate glucose levels. Concentration of GH before and after feeding or glucose challenge were not affected by Zn status; however, serum IGF-I was lower in deficient than in marginal or adequate lambs. A GH releasing factor (GRF) analog was given to evaluate the release of GH. Serum GH in response to GRF challenge was higher in deficient lambs and tended to be higher in marginal lambs when compared to adequate lambs. Impaired growth observed with Zn deficiency may be mediated in part by its effect on insulin, GH and IGF-I concentrations.

  9. Growth rate and transition to turbulence of a gas curtain

    SciTech Connect

    Vorobieff, P.; Rightley, P.; Benjamin, R.

    1997-09-01

    The authors conduct shock-tube experiments to investigate Richtmyer-Meshkov (RM) instability of a narrow curtain of heavy gas (SF{sub 6}) embedded in lighter gas (air). Initial perturbations of the curtain can be varied, producing different flow patterns in the subsequent evolution of the curtain. Multiple-exposure video flow visualization provides images of the growth of the instability and its transition to turbulence, making it possible to extract quantitative information such as the width of the perturbed curtain. They demonstrate that the width of the curtain with initial perturbation on the downstream side is non-monotonic. As the initial perturbation undergoes phase inversion, the width of the curtain actually decreases before beginning to grow as the RM instability evolves.

  10. Nocturnal Light Pulses Lower Carbon Dioxide Production Rate without Affecting Feed Intake in Geese.

    PubMed

    Huang, De-Jia; Yang, Shyi-Kuen

    2016-03-01

    This study was conducted to investigate the effect of nocturnal light pulses (NLPs) on the feed intake and metabolic rate in geese. Fourteen adult Chinese geese were penned individually, and randomly assigned to either the C (control) or NLP group. The C group was exposed to a 12L:12D photoperiod (12 h light and 12 h darkness per day), whereas the NLP group was exposed to a 12L:12D photoperiod inserted by 15-min lighting at 2-h intervals in the scotophase. The weight of the feed was automatically recorded at 1-min intervals for 1 wk. The fasting carbon dioxide production rate (CO2 PR) was recorded at 1-min intervals for 1 d. The results revealed that neither the daily feed intake nor the feed intakes during both the daytime and nighttime were affected by photoperiodic regimen, and the feed intake during the daytime did not differ from that during the nighttime. The photoperiodic treatment did not affect the time distribution of feed intake. However, NLPs lowered (p<0.05) the mean and minimal CO2 PR during both the daytime and nighttime. Both the mean and minimal CO2 PR during the daytime were significantly higher (p<0.05) than those during the nighttime. We concluded that NLPs lowered metabolic rate of the geese, but did not affect the feed intake; both the mean and minimal CO2 PR were higher during the daytime than during the nighttime. PMID:26950871

  11. Seasonal and geographical variations in the growth rate of infants in China receiving increasing dosages of vitamin D supplements.

    PubMed

    Feliciano, E S; Ho, M L; Specker, B L; Falciglia, G; Shui, Q M; Yin, T A; Chen, X C

    1994-06-01

    In theory, sunshine exposure is sufficient to maintain normal vitamin D concentrations for the optimal growth of newborn infants. To determine whether season of birth, latitude (north v. south) and increasing dosages of vitamin D supplements would influence the growth rate for the first 6 months of life, 255 healthy fall-and spring-born infants from two northern and two southern cities in China were randomly assigned to receive either 100, 200, or 400 IU of vitamin D a day. The study showed that season of birth and dose of vitamin D did not affect the growth rate of infants born in the same latitude, but a significant difference was found in the gain in length over the 6-month period between infants from the north and infants from the south (P = 0.0001). Regional differences among the Chinese people, other than sunshine exposure, may have influenced the difference in length gain.

  12. Endogenous Abscisic Acid Promotes Hypocotyl Growth and Affects Endoreduplication during Dark-Induced Growth in Tomato (Solanum lycopersicum L.)

    PubMed Central

    Humplík, Jan F.; Bergougnoux, Véronique; Jandová, Michaela; Šimura, Jan; Pěnčík, Aleš; Tomanec, Ondřej; Rolčík, Jakub; Novák, Ondřej; Fellner, Martin

    2015-01-01

    Dark-induced growth (skotomorphogenesis) is primarily characterized by rapid elongation of the hypocotyl. We have studied the role of abscisic acid (ABA) during the development of young tomato (Solanum lycopersicum L.) seedlings. We observed that ABA deficiency caused a reduction in hypocotyl growth at the level of cell elongation and that the growth in ABA-deficient plants could be improved by treatment with exogenous ABA, through which the plants show a concentration dependent response. In addition, ABA accumulated in dark-grown tomato seedlings that grew rapidly, whereas seedlings grown under blue light exhibited low growth rates and accumulated less ABA. We demonstrated that ABA promotes DNA endoreduplication by enhancing the expression of the genes encoding inhibitors of cyclin-dependent kinases SlKRP1 and SlKRP3 and by reducing cytokinin levels. These data were supported by the expression analysis of the genes which encode enzymes involved in ABA and CK metabolism. Our results show that ABA is essential for the process of hypocotyl elongation and that appropriate control of the endogenous level of ABA is required in order to drive the growth of etiolated seedlings. PMID:25695830

  13. Single-mode, Rayleigh-Taylor growth-rate measurements on the OMEGA laser system

    SciTech Connect

    Knauer, J. P.; Betti, R.; Bradley, D. K.; Boehly, T. R.; Collins, T. J. B.; Goncharov, V. N.; McKenty, P. W.; Meyerhofer, D. D.; Smalyuk, V. A.; Verdon, C. P.

    2000-01-01

    The results from a series of single-mode, Rayleigh-Taylor (RT) instability growth experiments performed on the OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] using planar targets are reported. Planar targets with imposed mass perturbations were accelerated using five or six 351 nm laser beams overlapped with total intensities up to 2.5x10{sup 14} W/cm{sup 2}. Experiments were performed with both 3 ns ramp and 3 ns flat-topped temporal pulse shapes. The use of distributed phase plates and smoothing by spectral dispersion resulted in a laser-irradiation nonuniformity of 4%-7% over a 600 {mu}m diam region defined by the 90% intensity contour. The temporal growth of the modulation in optical depth was measured using throughfoil radiography and was detected with an x-ray framing camera for CH targets. Two-dimensional (2-D) hydrodynamic simulations (ORCHID) [R. L. McCrory and C. P. Verdon, in Inertial Confinement Fusion (Editrice Compositori, Bologna, 1989), pp. 83-124] of the growth of 20, 31, and 60 {mu}m wavelength perturbations were in good agreement with the experimental data when the experimental details, including noise, were included. The amplitude of the simulation optical depth is in good agreement with the experimental optical depth; therefore, great care must be taken when the growth rates are compared to dispersion formulas. Since the foil's initial condition just before it is accelerated is not that of a uniformly compressed foil, the optical density measurement does not accurately reflect the amplitude of the ablation surface but is affected by the initial nonuniform density profile. (c) 2000 American Institute of Physics.

  14. Single-mode, Rayleigh-Taylor growth-rate measurements on the OMEGA laser system

    NASA Astrophysics Data System (ADS)

    Knauer, J. P.; Betti, R.; Bradley, D. K.; Boehly, T. R.; Collins, T. J. B.; Goncharov, V. N.; McKenty, P. W.; Meyerhofer, D. D.; Smalyuk, V. A.; Verdon, C. P.; Glendinning, S. G.; Kalantar, D. H.; Watt, R. G.

    2000-01-01

    The results from a series of single-mode, Rayleigh-Taylor (RT) instability growth experiments performed on the OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] using planar targets are reported. Planar targets with imposed mass perturbations were accelerated using five or six 351 nm laser beams overlapped with total intensities up to 2.5×1014 W/cm2. Experiments were performed with both 3 ns ramp and 3 ns flat-topped temporal pulse shapes. The use of distributed phase plates and smoothing by spectral dispersion resulted in a laser-irradiation nonuniformity of 4%-7% over a 600 μm diam region defined by the 90% intensity contour. The temporal growth of the modulation in optical depth was measured using throughfoil radiography and was detected with an x-ray framing camera for CH targets. Two-dimensional (2-D) hydrodynamic simulations (ORCHID) [R. L. McCrory and C. P. Verdon, in Inertial Confinement Fusion (Editrice Compositori, Bologna, 1989), pp. 83-124] of the growth of 20, 31, and 60 μm wavelength perturbations were in good agreement with the experimental data when the experimental details, including noise, were included. The amplitude of the simulation optical depth is in good agreement with the experimental optical depth; therefore, great care must be taken when the growth rates are compared to dispersion formulas. Since the foil's initial condition just before it is accelerated is not that of a uniformly compressed foil, the optical density measurement does not accurately reflect the amplitude of the ablation surface but is affected by the initial nonuniform density profile.

  15. Mammoth tooth enamel growth rates inferred from stable isotope analysis and histology

    NASA Astrophysics Data System (ADS)

    Metcalfe, Jessica Z.; Longstaffe, Fred J.

    2012-05-01

    Mammoth (Mammuthus sp.) teeth are relatively abundant in Quaternary deposits from Eurasia and North America, and their isotopic compositions can be used to reconstruct past seasonal patterns in precipitation, diet, and migration. Strategies for collecting and interpreting such data, however, are strongly dependent on growth rates, which can vary among species, individuals, and within teeth. In this study, we use histological and isotopic measurements to determine enamel growth rates for a Columbian mammoth (Mammuthus columbi) tooth in two directions. Using histology, the growth rate through the enamel thickness (ET; perpendicular to the height of the tooth) is estimated at 0.8 to 1.5 mm/yr. Isotopic sampling through the innermost 0.36 mm of the ET recovered less than half a period of variation (i.e., half an inferred year of growth), which is consistent with the histological estimate for ET growth rate. A combination of histological and isotopic measurements suggests that the enamel extension rate (growth in the height of the tooth) is 13-14 mm/yr. Knowledge of enamel growth rates should improve the design and interpretation of future isotopic studies of mammoth teeth. The combination of histological and isotopic measurements may also prove useful in determining growth rates for other extinct taxa.

  16. Rate limits in silicon sheet growth - The connections between vertical and horizontal methods

    NASA Technical Reports Server (NTRS)

    Thomas, Paul D.; Brown, Robert A.

    1987-01-01

    Meniscus-defined techniques for the growth of thin silicon sheets fall into two categories: vertical and horizontal growth. The interactions of the temperature field and the crystal shape are analyzed for both methods using two-dimensional finite-element models which include heat transfer and capillarity. Heat transfer in vertical growth systems is dominated by conduction in the melt and the crystal, with almost flat melt/crystal interfaces that are perpendicular to the direction of growth. The high axial temperature gradients characteristic of vertical growth lead to high thermal stresses. The maximum growth rate is also limited by capillarity which can restrict the conduction of heat from the melt into the crystal. In horizontal growth the melt/crystal interface stretches across the surface of the melt pool many times the crystal thickness, and low growth rates are achievable with careful temperature control. With a moderate axial temperature gradient in the sheet a substantial portion of the latent heat conducts along the sheet and the surface of the melt pool becomes supercooled, leading to dendritic growth. The thermal supercooling is surpressed by lowering the axial gradient in the crystal; this configuration is the most desirable for the growth of high quality crystals. An expression derived from scaling analysis relating the growth rate and the crucible temperature is shown to be reliable for horizontal growth.

  17. Fusarium Oxysporum Volatiles Enhance Plant Growth Via Affecting Auxin Transport and Signaling.

    PubMed

    Bitas, Vasileios; McCartney, Nathaniel; Li, Ningxiao; Demers, Jill; Kim, Jung-Eun; Kim, Hye-Seon; Brown, Kathleen M; Kang, Seogchan

    2015-01-01

    Volatile organic compounds (VOCs) have well-documented roles in plant-plant communication and directing animal behavior. In this study, we examine the less understood roles of VOCs in plant-fungal relationships. Phylogenetically and ecologically diverse strains of Fusarium oxysporum, a fungal species complex that often resides in the rhizosphere of assorted plants, produce volatile compounds that augment shoot and root growth of Arabidopsis thaliana and tobacco. Growth responses of A. thaliana hormone signaling mutants and expression patterns of a GUS reporter gene under the auxin-responsive DR5 promoter supported the involvement of auxin signaling in F. oxysporum volatile-mediated growth enhancement. In addition, 1-naphthylthalamic acid, an inhibitor of auxin efflux, negated F. oxysporum volatile-mediated growth enhancement in both plants. Comparison of the profiles of volatile compounds produced by F. oxysporum strains that differentially affected plant growth suggests that the relative compositions of both growth inhibitory and stimulatory compounds may determine the degree of plant growth enhancement. Volatile-mediated signaling between fungi and plants may represent a potentially conserved, yet mostly overlooked, mechanism underpinning plant-fungus interactions and fungal niche adaption. PMID:26617587

  18. Fusarium Oxysporum Volatiles Enhance Plant Growth Via Affecting Auxin Transport and Signaling

    PubMed Central

    Bitas, Vasileios; McCartney, Nathaniel; Li, Ningxiao; Demers, Jill; Kim, Jung-Eun; Kim, Hye-Seon; Brown, Kathleen M.; Kang, Seogchan

    2015-01-01

    Volatile organic compounds (VOCs) have well-documented roles in plant-plant communication and directing animal behavior. In this study, we examine the less understood roles of VOCs in plant-fungal relationships. Phylogenetically and ecologically diverse strains of Fusarium oxysporum, a fungal species complex that often resides in the rhizosphere of assorted plants, produce volatile compounds that augment shoot and root growth of Arabidopsis thaliana and tobacco. Growth responses of A. thaliana hormone signaling mutants and expression patterns of a GUS reporter gene under the auxin-responsive DR5 promoter supported the involvement of auxin signaling in F. oxysporum volatile-mediated growth enhancement. In addition, 1-naphthylthalamic acid, an inhibitor of auxin efflux, negated F. oxysporum volatile-mediated growth enhancement in both plants. Comparison of the profiles of volatile compounds produced by F. oxysporum strains that differentially affected plant growth suggests that the relative compositions of both growth inhibitory and stimulatory compounds may determine the degree of plant growth enhancement. Volatile-mediated signaling between fungi and plants may represent a potentially conserved, yet mostly overlooked, mechanism underpinning plant-fungus interactions and fungal niche adaption. PMID:26617587

  19. The effect of salinity on the growth rate of the macroalgae Enteromorpha intestinalis (Chlorophyta) in the Mondego estuary (west Portugal)

    NASA Astrophysics Data System (ADS)

    Martins, Irene; Oliveira, José Miguel; Flindt, Morgens R.; Marques, João Carlos

    1999-07-01

    The excessive growth of opportunistic macroalgae in estuaries and other coastal areas, characterised by enormous values of vegetal biomass in the form of dense mats, is a common and widespread picture nowadays. In such conditions, macroalgae completely dominate the nutrient dynamics in the ecosystem and function as high quality food for the microbial, meio- and macrofaunal communities. Due to their important role in the nutrient pathways of the ecosystems, it becomes essential to obtain new information on variables and processes that regulate the bloom formation of these primary producers. The Mondego estuary (west Portugal) is a eutrophic estuary, where usually macroalgae of the genera Enteromorpha seasonally bloom. Nevertheless, in years with high precipitation characterised by a significant increase of the freshwater runoff to the system, no Enteromorpha blooms are observed. Possible explanations for this are related to the reduction of light in the water column, high water speed, high sediment turbulence and low salinity values. Thus, because the decrease in salinity seemed an important feature during such periods, a set of experiments were conducted, to evaluate to what extent the growth of Enteromorpha intestinalis (the most abundant species in the Mondego estuary) is affected by fluctuations in salinity and, particularly, by low salinity values. In the laboratory, the growth rate of E. intestinalis was tested against a range of salinity, from 0 to 32 psu. E. intestinalis showed the lowest growth rates at extreme low salinity values (≤ 3 psu) and for salinity ≤ 1 psu, the algae died. Growth rates at salinity lower than 5 psu and higher than 25 psu were also low, when compared with growth between salinity of 15 and 20 psu, where E. intestinalis showed the highest growth rates. These results agree with the field observations and suggest that, in the Mondego estuary, salinity is an important external parameter to control the growth of E. intestinalis, which

  20. Growth rates of atmospheric molecular clusters determined from cluster appearance times and collision-evaporation fluxes

    NASA Astrophysics Data System (ADS)

    Kontkanen, Jenni; Olenius, Tinja; Lehtipalo, Katrianne; Vehkamäki, Hanna; Kulmala, Markku

    2015-04-01

    The probability of freshly formed particles to survive to climatically relevant sizes is determined by the competition between the coagulation loss rate and the particle growth rate. Therefore, various methods have been developed to deduce the growth rates from measured particle size distributions. Recently, the growth rates of sub-3nm clusters have been determined based on the appearance times of different cluster sizes. However, it is not clear to what extent these growth rates are consistent with the growth rates corresponding to molecular fluxes between clusters. In this work, we simulated the time evolution of a population of sub-3 nm molecular clusters and compared the growth rates determined (1) from the cluster appearance times and (2) from the collision-evaporation fluxes between different cluster sizes. We performed a number of simulations by varying the ambient conditions and the properties of the model substance. In the first simulation set, the Gibbs free energy of the formation of the clusters was assumed to have a single maximum and no minima, corresponding to a monotonically increasing stability as a function of cluster size. The saturation vapor pressure was selected so that the growth proceeded solely via monomer additions. The growth rates were determined separately for each cluster. However, to see the effect of finite size resolution, we also performed simulations where the clusters were grouped into size bins, for which we determined the growth rates. In the second simulation set, the saturation vapor pressure was lowered so that the collisions of small clusters significantly contributed to the growth. As the growth rate of a single cluster is ambiguous in this case, the growth rates were determined only for different size bins. We performed simulations using a similar free energy profile as in other simulations but we also used a free energy profile containing a local minimum, corresponding to small stable clusters. Our simulations show that

  1. Milk and Protein Intake by Pregnant Women Affects Growth of Foetus

    PubMed Central

    Borazjani, Fatemeh; Kulkarni, Shanuak S.

    2013-01-01

    The study assessed the effects of the daily intake of milk and protein by pregnant women on foetal growth and determined the growth pattern and velocity of growth. A total of 504 ultrasound observations from 156 respondents were collected following a cross-sectional design in the last trimester of pregnancy; majority of them were in the last month of pregnancy. De facto and purposive sampling was done, and direct interviews of affluent pregnant women were conducted. Kruskal-Wallis test shows that majority of the respondents had tendency to consume 155.65 to 465.17 mL of milk per day, resulting in better and higher foetal growth. Most respondents consumed about 50-70 g of protein per day, and the foetal growth measurements, such as abdomen-circumference, femur length, biparietal diameter, and head-circumference, on an average, were higher in the same group. Quadratic regression model exhibited that all the traits of growth pattern in Model 1 (low milk and protein intake) appeared to have more mode of decline, in contrast to Model 2 (more milk and protein intake), which shows better growth. In addition, velocity of growth pattern was obtained through the first derivative of quadratic regression of growth pattern. Moreover, 95% confidence interval calculated for regression line slope of Model 1 and Model 2 showed that the estimation point (2 B2) of Model 1 does not lay into 95% CI of Model 2; so, statistical significance assorted and also the same trend conversely hold for Model 2. The rate of growth was highly influenced by maternal milk and protein intake. These findings suggest that contribution of common nutrients or other nutritional factors present in milk and protein promote the growth of foetus. PMID:24592584

  2. Controlled Cu nanoparticle growth on wrinkle affecting deposition of large scale graphene

    NASA Astrophysics Data System (ADS)

    Ahmed, Mohsin; Uddin, Md Jasim; Rahman, Muhammad Anisur; Kishi, Naoki; Soga, Tetsuo

    2016-09-01

    For Chemical Vapor Deposition (CVD) grown graphene on Cu substrate, deviation from atomic orientation in crystals may be resulted from diffusion of abnormalities in the form of Cu nanoparticle (NP) formation or defects and affects graphene quality and properties drastically. However, for the uniform graphene deposition, mechanism of nanoparticle formation and its suppression procedure need to be better understood. We report growth of graphene, affected by Cu nanoparticles (NPs) emergence on Cu substrates. In the current study, growth of these nanoparticles has been suppressed by fine tuning of carrier gas by two-fold gas insertion mechanism and hence, quality and uniformity of graphene is significantly improved. It has been also observed that during the deposition by CVD, Cu nanoparticles cluster preferentially on wrinkles or terrace of the Cu surface. Composition of NP is extensively studied and found to be the oxide nanoparticle of Cu. Our result, controlled NP growth affecting deposition of graphene layer would provide useful insight on the growth of uniform and high quality Single layer or bilayer graphene for numerous electronics applications.

  3. Larval growth rate and sex determine resource allocation and stress responsiveness across life stages in juvenile frogs.

    PubMed

    Warne, Robin W; Crespi, Erica J

    2015-03-01

    The extent to which interactions between environmental stressors and phenotypic variation during larval life stages impose carry-over effects on adult phenotypes in wildlife are not clear. Using semi-natural mesocosms, we examined how chronically low food availability and size-specific phenotypes in larval amphibians interact and carry over to influence frog growth, resource allocation, endocrine activity and survival. We tagged three cohorts of larvae that differed in body size and developmental stage at 3 weeks after hatching, and tracked them through 10 weeks after metamorphosis in high and low food conditions. We found that growth and development rates during the early tadpole stage not only affected metamorphic rates, but also shaped resource allocation and stress responsiveness in frogs: the slowest growing larvae from low-food mesocosms exhibited a suppressed glucocorticoid response to a handling stressor; reduced growth rate and fat storage as frogs. We also show for the first time that larval developmental trajectories varied with sex, where females developed faster than males especially in food-restricted conditions. Last, while larval food restriction profoundly affected body size in larvae and frogs, time to metamorphosis was highly constrained, which suggests that the physiology and development of this ephemeral pond-breeding amphibian is adapted for rapid metamorphosis despite large potential variation in nutrient availability. Taken together, these results suggest that larval phenotypic variation significantly influences multiple dimensions of post-metamorphic physiology and resource allocation, which likely affect overall performance.

  4. Growth rates are related to production efficiencies in juveniles of the sea urchin Lytechinus variegatus

    PubMed Central

    Heflin, L.E.; Gibbs, V.K.; Jones, W.T.; Makowsky, R.; Lawrence, A.L.; Watts, S.A.

    2014-01-01

    Growth rates of newly-metamorphosed urchins from a single spawning event (three males and three females) were highly variable, despite being held en masse under identical environmental and nutritional conditions. As individuals reached ~5 mm diameter (0.07–0.10 g wet weight), they were placed in growth trials (23 dietary treatments containing various nutrient profiles). Elapsed time from the first individual entering the growth trials to the last individual entering was 121 days (N = 170 individuals). During the five-week growth trials, urchins were held individually and proffered a limiting ration to evaluate growth rate and production efficiency. Growth rates among individuals within each dietary treatment remained highly variable. Across all dietary treatments, individuals with an initially high growth rate (entering the study first) continued to grow at a faster rate than those with an initially low growth rate (entering the study at a later date), regardless of feed intake. Wet weight gain (ranging from 0.13 −3.19 g, P < 0.0001, R2 = 0.5801) and dry matter production efficiency (ranging from 25.2–180.5%, P = 0.0003, R2 = 0.6162) were negatively correlated with stocking date, regardless of dietary treatment. Although canalization of growth rate during en masse early post-metamorphic growth is possible, we hypothesize that intrinsic differences in growth rates are, in part, the result of differences (possibly genetic) in production efficiencies of individual Lytechinus variegatus. That is, some sea urchins are more efficient in converting feed to biomass. We further hypothesize that this variation may have evolved as an adaptive response to selective pressure related to food availability. PMID:25435593

  5. Beyond Thermal Performance Curves: Modeling Time-Dependent Effects of Thermal Stress on Ectotherm Growth Rates.

    PubMed

    Kingsolver, Joel G; Woods, H Arthur

    2016-03-01

    Thermal performance curves have been widely used to model the ecological responses of ectotherms to variable thermal environments and climate change. Such models ignore the effects of time dependence-the temporal pattern and duration of temperature exposure-on performance. We developed and solved a simple mathematical model for growth rate of ectotherms, combining thermal performance curves for ingestion rate with the temporal dynamics of gene expression and protein production in response to high temperatures to predict temporal patterns of growth rate in constant and diurnally fluctuating temperatures. We used the model to explore the effects of heat shock proteins on larval growth rates of Manduca sexta. The model correctly captures two empirical patterns for larval growth rate: first, maximal growth rate and optimal temperature decline with increasing duration of temperature exposure; second, mean growth rates decline with time in diurnally fluctuating temperatures at higher mean temperatures. These qualitative results apply broadly to cases where proteins or other molecules produced in response to high temperatures reduce growth rates. We discuss some of the critical assumptions and predictions of the model and suggest potential extensions and alternatives. Incorporating time-dependent effects will be essential for making more realistic predictions about the physiological and ecological consequences of temperature fluctuations and climate change. PMID:26913942

  6. Towards an organic palaeosalinity proxy: the effect of salinity, growth rate and growth phase on the hydrogen isotopic composition of alkenones produced by haptophyte algae

    NASA Astrophysics Data System (ADS)

    Chivall, David; M'Boule, Daniela; Schouten, Stefan; Sinninghe Damsté, Jaap S.; van der Meer, Marcel T. J.

    2013-04-01

    Palaeosalinity is one of the most important oceanographic parameters which currently cannot be quantified with reasonable accuracy from sedimentary records. Schouten et al.1 established that the fractionation of hydrogen isotopes between growth water and alkenones produced by the haptophyte algae Emiliania huxleyi and Gephyrocapsa oceanica is salinity dependent. As such, the δD values of alkenones recovered from sediment cores can be used to reconstruct variations in palaeo- sea surface salinity.2 However, to accurately determine absolute palaeosalinity requires a better constraining of the relationship between this hydrogen fractionation, salinity and other parameters such as growth rate and growth phase. Here, we present results from our ongoing work to constrain the relationship between the fractionation factor αalkenone-water, salinity, growth rate and growth phase for the major alkenone-producing haptophytes. In batch cultures of different strains of the open-ocean haptophyte E. huxleyi sampled during the exponential growth phase, αC37alkenone-growthwater increases by between 0.0022 and 0.0033 per unit increase in salinity. A similar relationship is observed in batch cultures of the coastal haptophyte Isochrysis galbana, where α increases with each unit of salinity by 0.0019 - slightly less than for E. huxleyi. However, absolute αC37alkenone-growthwater values vary strongly between species suggesting that species composition has a strong impact on the δD value of alkenones. The fractionation factor for alkenones produced by batch cultures of I. galbana is affected by growth phase: the rate of change of αC37alkenone-growthwater with each unit of salinity decreases from 0.0019 in the exponential phase to 0.0010 during the stationary phase. We also show the effect of varying growth rate over the range 0.2-0.8 day-1 on the fractionation factor for alkenones produced by E. huxleyi grown in continuous culture. These data show that alkenone δD can be used to

  7. Parental age affects somatic mutation rates in the progeny of flowering plants.

    PubMed

    Singh, Amit Kumar; Bashir, Tufail; Sailer, Christian; Gurumoorthy, Viswanathan; Ramakrishnan, Anantha Maharasi; Dhanapal, Shanmuhapreya; Grossniklaus, Ueli; Baskar, Ramamurthy

    2015-05-01

    In humans, it is well known that the parental reproductive age has a strong influence on mutations transmitted to their progeny. Meiotic nondisjunction is known to increase in older mothers, and base substitutions tend to go up with paternal reproductive age. Hence, it is clear that the germinal mutation rates are a function of both maternal and paternal ages in humans. In contrast, it is unknown whether the parental reproductive age has an effect on somatic mutation rates in the progeny, because these are rare and difficult to detect. To address this question, we took advantage of the plant model system Arabidopsis (Arabidopsis thaliana), where mutation detector lines allow for an easy quantitation of somatic mutations, to test the effect of parental age on somatic mutation rates in the progeny. Although we found no significant effect of parental age on base substitutions, we found that frameshift mutations and transposition events increased in the progeny of older parents, an effect that is stronger through the maternal line. In contrast, intrachromosomal recombination events in the progeny decrease with the age of the parents in a parent-of-origin-dependent manner. Our results clearly show that parental reproductive age affects somatic mutation rates in the progeny and, thus, that some form of age-dependent information, which affects the frequency of double-strand breaks and possibly other processes involved in maintaining genome integrity, is transmitted through the gametes. PMID:25810093

  8. Timing of cotyledon damage affects growth and flowering in mature plants.

    PubMed

    Hanley, M E; Fegan, E L

    2007-07-01

    Although the effects of herbivory on plant fitness are strongly linked to age, we understand little about how the timing of herbivory at the seedling stage affects growth and reproduction for plants that survive attack. In this study, we subjected six north-western European, dicotyledonous grassland species (Leontodon autumnalis, Leontodon hispidus, Plantago lanceolata, Plantago major, Trifolium pratense and Trifolium repens) to cotyledon removal at 7, 14 and 21 d old. We monitored subsequent growth and flowering (number of inflorescences recorded, and time taken for first flowers to open) over a 107 d period. Cotyledon removal reduced growth during establishment (35 d) for all species, and a further three exhibited reduced growth at maturity. Four species developed fewer inflorescences, or had delayed flowering after cotyledon removal. Although early damage (7 d old) had the greatest long-term effect on plant performance, responses varied according to the age at which the damage occurred and the species involved. Our results illustrate how growth and flowering into the mature phase is affected by cotyledon damage during different stages of seedling ontogeny, and we highlight the ways in which ontogenetic variation in seedling tolerance of tissue loss might impact upon plant fitness in mature plant communities. PMID:17547653

  9. Impacts of Bokashi on survival and growth rates of Pinus pseudostrobus in community reforestation projects.

    PubMed

    Jaramillo-López, P F; Ramírez, M I; Pérez-Salicrup, D R

    2015-03-01

    Community-based small-scale reforestation practices have been proposed as an alternative to low-efficiency massive reforestations conducted by external agents. These latter conventional reforestations are often carried out in soils that have been seriously degraded and this has indirectly contributed to the introduction of non-native species and/or acceptance of very low seedling survival rates. Bokashi is a fermented soil organic amendment that can be made from almost any available agricultural byproduct, and its beneficial effects in agriculture have been reported in various contexts. Here, we report the results of a community-based small-scale experimental reforestation where the provenance of pine seedlings (local and commercial) and the use of Bokashi as a soil amendment were evaluated. Bokashi was prepared locally by members of a small rural community in central Mexico. Almost two years after the establishment of the trial, survival rates for the unamended and amended local trees were 97-100% while survival of the commercial trees from unamended and amended treatments were 87-93%. Consistently through time, local and commercial seedlings planted in Bokashi-amended soils were significantly taller (x̅ = 152 cm) than those planted in unamended soils (̅x = 86 cm). An unplanned infection by Cronartium quercuum in the first year of the experiment was considered as a covariable. Infected seedlings showed malformations but this did not affect survival and growth rates. Bokashi amendment seems as an inexpensive, locally viable technology to increase seedling survival and growth and to help recover deforested areas where soils have been degraded. This allows local stakeholders to see more rapid results while helping them to maintain their interest in conservation activities. PMID:25460423

  10. Elevated atmospheric CO2 increases microbial growth rates and enzymes activity in soil

    NASA Astrophysics Data System (ADS)

    Blagodatskaya, Evgenia; Blagodatsky, Sergey; Dorodnikov, Maxim; Kuzyakov, Yakov

    2010-05-01

    Increasing the belowground translocation of assimilated carbon by plants grown under elevated CO2 can cause a shift in the structure and activity of the microbial community responsible for the turnover of organic matter in soil. We investigated the long-term effect of elevated CO2 in the atmosphere on microbial biomass and specific growth rates in root-free and rhizosphere soil. The experiments were conducted under two free air carbon dioxide enrichment (FACE) systems: in Hohenheim and Braunschweig, as well as in the intensively managed forest mesocosm of the Biosphere 2 Laboratory (B2L) in Oracle, AZ. Specific microbial growth rates (μ) were determined using the substrate-induced respiration response after glucose and/or yeast extract addition to the soil. We evaluated the effect of elevated CO2 on b-glucosidase, chitinase, phosphatase, and sulfatase to estimate the potential enzyme activity after soil amendment with glucose and nutrients. For B2L and both FACE systems, up to 58% higher μ were observed under elevated vs. ambient CO2, depending on site, plant species and N fertilization. The μ-values increased linearly with atmospheric CO2 concentration at all three sites. The effect of elevated CO2 on rhizosphere microorganisms was plant dependent and increased for: Brassica napus=Triticum aestivumaffected microbial growth rates directly (N limitation) and indirectly (changing the quantity of fine roots). So, 50% decrease in N fertilization caused the overall increase or decrease of microbial growth rates depending on plant species. The μ-value increase was lower for microorganisms growing on yeast extract then for those growing on glucose, i.e. the effect of elevated CO2 was smoothed on rich vs. simple substrate. So, the r/K strategies ratio can be better revealed by studying growth on simple (glucose) than on rich substrate mixtures (yeast extract). After adding glucose, enzyme activities under elevated CO2 were

  11. Differences in proleptic and epicormic shoot structures in relation to water deficit and growth rate in almond trees (Prunus dulcis)

    PubMed Central

    Negrón, Claudia; Contador, Loreto; Lampinen, Bruce D.; Metcalf, Samuel G.; Guédon, Yann; Costes, Evelyne; DeJong, Theodore M.

    2014-01-01

    Background and Aims Shoot characteristics differ depending on the meristem tissue that they originate from and environmental conditions during their development. This study focused on the effects of plant water status on axillary meristem fate and flowering patterns along proleptic and epicormic shoots, as well as on shoot growth rates on ‘Nonpareil’ almond trees (Prunus dulcis). The aims were (1) to characterize the structural differences between proleptic and epicormic shoots, (2) to determine whether water deficits modify shoot structures differently depending on shoot type, and (3) to determine whether shoot structures are related to shoot growth rates. Methods A hidden semi-Markov model of the axillary meristem fate and number of flower buds per node was built for two shoot types growing on trees exposed to three plant water status treatments. The models segmented observed shoots into successive homogeneous zones, which were compared between treatments. Shoot growth rates were calculated from shoot extension measurements made during the growing season. Key Results Proleptic shoots had seven successive homogeneous zones while epicormic shoots had five zones. Shoot structures were associated with changes in growth rate over the season. Water deficit (1) affected the occurrence and lengths of the first zones of proleptic shoots, but only the occurrence of the third zone was reduced in epicormic shoots; (2) had a minor effect on zone flowering patterns and did not modify shoot or zone composition of axillary meristem fates; and (3) reduced growth rates, although patterns over the season were similar among treatments. Conclusions Two meristem types, with different latency durations, produced shoots with different growth rates and distinct structures. Differences between shoot type structure responses to water deficit appeared to reflect their ontogenetic characteristics and/or resource availability for their development. Tree water deficit appeared to stimulate

  12. The effects of temperature and NaCl concentration on tetragonal lysozyme face growth rates

    NASA Technical Reports Server (NTRS)

    Forsythe, Elizabeth; Pusey, Marc Lee

    1994-01-01

    Measurements were made of the (110) and (101) face growth rates of the tetragonal form of hen egg white lysozyme at 0.1M sodium acetate buffer, pH 4.0, from 4 to 22 C and with 3.0%, 5.0%, and 7.0% NaCl used as the precipitating salt. The data were collected at supersaturation ratios ranging from approximately 4 to approximately 63. Both decreasing temperature and increasing salt concentrations shifted plots of the growth rate versus C/C(sat) to the right, i.e. higher supersaturations were required for comparable growth rates. The observed trends in the growth data are counter to those expected from the solubility data. If tetragonal lysozyme crystal growth is by addition of ordered aggregates from the solution, then the observed growth data could be explained as a result of the effects of lowered temperature and increased salt concentration on the kinetics and equilibrium processes governing protein-protein interactions in solution. The data indicate that temperature would be a more tractable means of controlling the growth rate for tetragonal lysozyme crystals contrary to the usual practice in, e.g., vapor diffusion protein crystal growth, where both the precipitant and protein concentrations are simultaneously increased. However, the available range for control is dependent upon the protein concentration, with the greatest growth rate control being at the lower concentration.

  13. Growth rates and energy intake of hand-reared cheetah cubs (Acinonyx jubatus) in South Africa.

    PubMed

    Bell, K M; Rutherfurd, S M; Morton, R H

    2012-04-01

    Growth rate is an important factor in neonatal survival. The aim of this study was to determine growth rates in hand-reared cheetah cubs in South Africa fed a prescribed energy intake, calculated for growth in the domestic cat. Growth was then compared with previously published data from hand-reared cubs in North America and the relationship between growth and energy intake explored. Daily body weight (BW) gain, feed and energy intake data was collected from 18 hand-reared cheetah cubs up to 120 days of age. The average pre-weaning growth rate was 32 g/day, which is lower than reported in mother-reared cubs and hand-reared cubs in North American facilities. However, post-weaning growth increased to an average of 55 g/day. Growth was approximately linear prior to weaning, but over the entire age range it exhibited a sigmoidal shape with an asymptotic plateau averaging 57 kg. Energy intake associated with pre-weaning growth was 481 kJ ME/kg BW(0.75). Regression analysis described the relationship between metabolic BW, metabolisable energy (ME) intake, and hence daily weight gain. This relationship may be useful in predicting energy intake required to achieve growth rates in hand-reared cheetah cubs similar to those observed for their mother-reared counterparts.

  14. Observations on the luminosity lifetimes, emittance growth rates and intra-beam scattering at the Tevatron

    SciTech Connect

    Paul L.G. Lebrun et al.

    2003-05-22

    A record luminosity of 4.2 10{sup 31}has been reached at the Fermilab p-{bar p} collider. The lifetime of this luminosity at the beginning of the store is about 10 hours. This lifetime can be explained by the measured loss of anti-protons and protons due to collisions and emittance growths. We report on transverse emittance growth rates based on our Synchrotron Light Monitor. Longitudinal emittance growth rate measurements are based on the TeV Sampled Bunch Display data. It is shown that Intra Beam Scattering is a significant source of emittance growth rates. We comment on other possible factors for these observed emittance growth rates. Finally, we comment on future luminosity lifetimes, as we hope to further increase our peak luminosity.

  15. Temperature responses of substrate carbon conversion efficiencies and growth rates of plant tissues.

    PubMed

    Hansen, Lee D; Thomas, Nathan R; Arnholdt-Schmitt, Birgit

    2009-12-01

    Growth rates of plant tissues depend on both the respiration rate and the efficiency with which carbon is incorporated into new structural biomass. Calorespirometric measurement of respiratory heat and CO2 rates, from which both efficiency and growth rate can be calculated, is a well established method for determining the effects of rapid temperature changes on the respiratory and growth properties of plant tissues. The effect of the alternative oxidase/cytochrome oxidase activity ratio on efficiency is calculated from first principles. Data on the temperature dependence of the substrate carbon conversion efficiency are tabulated. These data show that epsilon is maximum and approximately constant through the optimum growth temperature range and decreases rapidly as temperatures approach temperature limits to growth. The width of the maximum and the slopes of decreasing epsilon at high and low temperatures vary greatly with species, cultivars and accessions.

  16. Crystal growth rates and secondary nucleation threshold for γ-DL-methionine in aqueous solution

    NASA Astrophysics Data System (ADS)

    Wantha, Lek; Flood, Adrian E.

    2011-03-01

    The Secondary Nucleation Threshold (SNT) of γ-DL-methionine (DL-met) in aqueous solution was measured for the temperature range 10-61 °C. The width of the SNT is weakly temperature dependent with slightly smaller induction times at higher temperatures. Seeded batch crystallizations of γ-DL-met were performed isothermally at 10, 25, and 40 °C in an agitated batch crystallizer, and within the SNT region to avoid nucleation. The effect of the initial supersaturation and seed mass on crystal growth were also studied at 25 °C. The initial growth rate (during the first 20 min of the batch) is significantly higher than subsequent crystal growth, a phenomenon previously seen with other species. The measured growth rates are independent of seed mass, as expected, for the usable portion of the growth rate data. The growth rates were found to linearly depend on the relative supersaturation of the total DL-met in the system. The growth rate constants increase with increasing temperature and follow an Arrhenius relationship. The growth kinetics of the γ-DL-met will be used to study in order to begin characterization of the polymorphic transformations and the overall crystallization rate of DL-met.

  17. ppGpp is the major source of growth rate control in E. coli.

    PubMed

    Potrykus, Katarzyna; Murphy, Helen; Philippe, Nadège; Cashel, Michael

    2011-03-01

    It is widely accepted that the DNA, RNA and protein content of Enterobacteriaceae is regulated as a function of exponential growth rates; macromolecular content increases with faster growth regardless of specific composition of the growth medium. This phenomenon, called growth rate control, primarily involves regulation of ribosomal RNA and ribosomal protein synthesis. However, it was uncertain whether the global regulator ppGpp is the major determinant for growth rate control. Therefore, here we re-evaluate the effect of ppGpp on macromolecular content for different balanced growth rates in defined media. We find that when ppGpp is absent, RNA/protein and RNA/DNA ratios are equivalent in fast and slow growing cells. Moreover, slow growing ppGpp-deficient cells with increased RNA content, display a normal ribosomal subunit composition although polysome content is reduced when compared with fast growing wild-type cells. From this we conclude that growth rate control does not occur in the absence of ppGpp. Also, artificial elevation of ppGpp or introduction of stringent RNA polymerase mutants in ppGpp-deficient cells restores this control. We believe these findings strongly argue in favour of ppGpp and against redundant regulation of growth rate control by other factors in Escherichia coli and other enteric bacteria.

  18. Propagule size and predispersal damage by insects affect establishment and early growth of mangrove seedlings.

    PubMed

    Sousa, Wayne P; Kennedy, Peter G; Mitchell, Betsy J

    2003-05-01

    Variation in rates of seedling recruitment, growth, and survival can strongly influence the rate and course of forest regeneration following disturbance. Using a combination of field sampling and shadehouse experiments, we investigated the influence of propagule size and predispersal insect damage on the establishment and early growth of the three common mangrove species on the Caribbean coast of Panama: Avicennia germinans, Laguncularia racemosa, and Rhizophora mangle. In our field samples, all three species exhibited considerable intraspecific variation in mature propagule size, and suffered moderate to high levels of predispersal attack by larval insects. Rates of insect attack were largely independent of propagule size both within and among trees. Our experimental studies using undamaged mature propagules showed that, for all three species, seedlings established at high rates regardless of propagule size. However, propagule size did have a marked effect on early seedling growth: seedlings that developed from larger propagules grew more rapidly. Predispersal insect infestations that had destroyed or removed a substantial amount of tissue, particularly if that tissue was meristematic or conductive, reduced the establishment of propagules of all three species. The effect of sublethal tissue damage or loss on the subsequent growth of established seedlings varied among the three mangrove species. For Avicennia, the growth response was graded: for a propagule of a given size, the more tissue lost, the slower the growth of the seedling. For Laguncularia, the response to insect attack appeared to be all-or-none. If the boring insect penetrated the outer spongy seed coat and reached the developing embryo, it usually caused sufficient damage to prevent a seedling from developing. On the other hand, if the insect damaged but did not penetrate the seed coat, a completely healthy seedling developed and its growth rate was indistinguishable from a seedling developing from an

  19. Stocker growth on rye and ryegrass pastures affects subsequent feedlot gains and carcass traits

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Stocker calves were stocked on annual rye (Secale cereale L.) and ryegrass (Lolium multiflorum Lam.) pastures using stocking strategies (STK) to create graded levels of gain to assess subsequent growth rates, feedlot performance, and carcass traits. During two consecutive years, yearling Angus, Here...

  20. The Ecology of Technological Progress: How Symbiosis and Competition Affect the Growth of Technology Domains

    ERIC Educational Resources Information Center

    Carnabuci, Gianluca

    2010-01-01

    We show that the progress of technological knowledge is an inherently ecological process, wherein the growth rate of each technology domain depends on dynamics occurring in "other" technology domains. We identify two sources of ecological interdependence among technology domains. First, there are symbiotic interdependencies, implying that the rate…

  1. Root Respiration and Growth in Plantago major as Affected by Vesicular-Arbuscular Mycorrhizal Infection.

    PubMed

    Baas, R; van der Werf, A; Lambers, H

    1989-09-01

    Effects of vesicular-arbuscular mycorrhizal (VAM) infection and P on root respiration and dry matter allocation were studied in Plantago major L. ssp. pleiosperma (Pilger). By applying P, the relative growth rate of non-VAM controls and plants colonized by Glomus fasciculatum (Thaxt. sensu Gerdemann) Gerdemann and Trappe was increased to a similar extent (55-67%). However, leaf area ratio was increased more and net assimilation rate per unit leaf area was increased less by VAM infection than by P addition. The lower net assimilation rate could be related to a 20 to 30% higher root respiration rate per unit leaf area of VAM plants. Root respiration per unit dry matter and specific net uptake rates of N and P were increased more by VAM infection than by P addition. Neither the contribution of the alternative respiratory path nor the relative growth rate could account for the differences in root respiration rate between VAM and non-VAM plants. It was estimated that increased fungal respiration (87%) and ion uptake rate (13%) contributed to the higher respiratory activity of VAM roots of P. major. PMID:16667001

  2. Root Respiration and Growth in Plantago major as Affected by Vesicular-Arbuscular Mycorrhizal Infection 1

    PubMed Central

    Baas, Rob; van der Werf, Adrie; Lambers, Hans

    1989-01-01

    Effects of vesicular-arbuscular mycorrhizal (VAM) infection and P on root respiration and dry matter allocation were studied in Plantago major L. ssp. pleiosperma (Pilger). By applying P, the relative growth rate of non-VAM controls and plants colonized by Glomus fasciculatum (Thaxt. sensu Gerdemann) Gerdemann and Trappe was increased to a similar extent (55-67%). However, leaf area ratio was increased more and net assimilation rate per unit leaf area was increased less by VAM infection than by P addition. The lower net assimilation rate could be related to a 20 to 30% higher root respiration rate per unit leaf area of VAM plants. Root respiration per unit dry matter and specific net uptake rates of N and P were increased more by VAM infection than by P addition. Neither the contribution of the alternative respiratory path nor the relative growth rate could account for the differences in root respiration rate between VAM and non-VAM plants. It was estimated that increased fungal respiration (87%) and ion uptake rate (13%) contributed to the higher respiratory activity of VAM roots of P. major. PMID:16667001

  3. Root Respiration and Growth in Plantago major as Affected by Vesicular-Arbuscular Mycorrhizal Infection.

    PubMed

    Baas, R; van der Werf, A; Lambers, H

    1989-09-01

    Effects of vesicular-arbuscular mycorrhizal (VAM) infection and P on root respiration and dry matter allocation were studied in Plantago major L. ssp. pleiosperma (Pilger). By applying P, the relative growth rate of non-VAM controls and plants colonized by Glomus fasciculatum (Thaxt. sensu Gerdemann) Gerdemann and Trappe was increased to a similar extent (55-67%). However, leaf area ratio was increased more and net assimilation rate per unit leaf area was increased less by VAM infection than by P addition. The lower net assimilation rate could be related to a 20 to 30% higher root respiration rate per unit leaf area of VAM plants. Root respiration per unit dry matter and specific net uptake rates of N and P were increased more by VAM infection than by P addition. Neither the contribution of the alternative respiratory path nor the relative growth rate could account for the differences in root respiration rate between VAM and non-VAM plants. It was estimated that increased fungal respiration (87%) and ion uptake rate (13%) contributed to the higher respiratory activity of VAM roots of P. major.

  4. Do variations in leaf phenology affect radial growth variations in Fagus sylvatica?

    NASA Astrophysics Data System (ADS)

    Čufar, Katarina; De Luis, Martin; Prislan, Peter; Gričar, Jožica; Črepinšek, Zalika; Merela, Maks; Kajfež-Bogataj, Lučka

    2015-08-01

    We used a dendrochronological and leaf phenology network of European beech ( Fagus sylvatica) in Slovenia, a transitional area between Mediterranean, Alpine and continental climatic regimes, for the period 1955-2007 to test whether year to year variations in leaf unfolding and canopy duration (i.e. time between leaf unfolding and colouring) influence radial growth (annual xylem production and tree ring widths) and if such influences are more pronounced at higher altitudes. We showed that variability in leaf phenology has no significant effect on variations in radial growth. The results are consistent in the entire region, irrespective of the climatic regime or altitude, although previous studies have shown that leaf phenology and tree ring variation depend on altitude. The lack of relationship between year to year variability in leaf phenology and radial growth may suggest that earlier leaf unfolding—as observed in a previous study—probably does not cause increased tree growth rates in beech in Slovenia.

  5. Differentiation of affective and denotative meaning systems and their influence in personality ratings.

    PubMed

    Tzeng, O C

    1975-12-01

    The present study presents an empirical example of the dichotomy of affective and denotative meaning systems and their influence on individual differences in personality ratings. The three-mode factor analytic technique with a newly developed transformation methodology for the scale mode was applied to data collected by Hogenraad from 50 French-speaking Belgians, rating 40 personality concepts against 40 semantic differential scales. Results indicated that three affective dimensions (evaluation, potency, and activity) proved to be dominant in the indigenous factor structure of personality impressions and that three dimensions in the "other" space, orthogonal to affect, are clearly interpretable denotative semantic features of personalities. Three idealized individual differences on interactions of these two meaning systems with four concept factors were highlighted by the final rotated inner core matrix. The present methodology along with the semantic differential technique and three-mode factor analysis can be applied to various types of subjects and/or concept domains for better understanding of intra- and intercultural differences. PMID:1214218

  6. Do Case Rates Affect Physicians' Clinical Practice in Radiation Oncology?: An Observational Study

    PubMed Central

    Loy, Bryan A.; Shkedy, Clive I.; Powell, Adam C.; Happe, Laura E.; Royalty, Julie A.; Miao, Michael T.; Smith, Gary L.; Long, James W.; Gupta, Amit K.

    2016-01-01

    Case rate payments combined with utilization monitoring may have the potential to improve the quality of care by reducing over and under-treatment. Thus, a national managed care organization introduced case rate payments at one multi-site radiation oncology provider while maintaining only fee-for-service payments at others. This study examined whether the introduction of the payment method had an effect on radiation fractions administered when compared to clinical guidelines. The number of fractions of radiation therapy delivered to patients with bone metastases, breast, lung, prostate, and skin cancer was assessed for concordance with clinical guidelines. The proportion of guideline-based care ascertained from the payer's claims database was compared before (2011) and after (2013) the payment method introduction using relative risks (RR). After the introduction of case rates, there were no significant changes in guideline-based care in breast, lung, and skin cancer; however, patients with bone metastases and prostate cancer were significantly more likely to have received guideline-based care (RR = 2.0 and 1.1, respectively, p<0.05). For the aggregate of all cancers, the under-treatment rate significantly declined (p = 0.008) from 4% to 0% after the introduction of case rate payments, while the over-treatment rate remained steady at 9%, with no significant change (p = 0.20). These findings suggest that the introduction of case rate payments did not adversely affect the rate of guideline-based care at the provider examined. Additional research is needed to isolate the effect of the payment model and assess implications in other populations. PMID:26870963

  7. Do Case Rates Affect Physicians' Clinical Practice in Radiation Oncology?: An Observational Study.

    PubMed

    Loy, Bryan A; Shkedy, Clive I; Powell, Adam C; Happe, Laura E; Royalty, Julie A; Miao, Michael T; Smith, Gary L; Long, James W; Gupta, Amit K

    2016-01-01

    Case rate payments combined with utilization monitoring may have the potential to improve the quality of care by reducing over and under-treatment. Thus, a national managed care organization introduced case rate payments at one multi-site radiation oncology provider while maintaining only fee-for-service payments at others. This study examined whether the introduction of the payment method had an effect on radiation fractions administered when compared to clinical guidelines. The number of fractions of radiation therapy delivered to patients with bone metastases, breast, lung, prostate, and skin cancer was assessed for concordance with clinical guidelines. The proportion of guideline-based care ascertained from the payer's claims database was compared before (2011) and after (2013) the payment method introduction using relative risks (RR). After the introduction of case rates, there were no significant changes in guideline-based care in breast, lung, and skin cancer; however, patients with bone metastases and prostate cancer were significantly more likely to have received guideline-based care (RR = 2.0 and 1.1, respectively, p<0.05). For the aggregate of all cancers, the under-treatment rate significantly declined (p = 0.008) from 4% to 0% after the introduction of case rate payments, while the over-treatment rate remained steady at 9%, with no significant change (p = 0.20). These findings suggest that the introduction of case rate payments did not adversely affect the rate of guideline-based care at the provider examined. Additional research is needed to isolate the effect of the payment model and assess implications in other populations.

  8. Does childhood cancer affect parental divorce rates? A population-based study.

    PubMed

    Syse, Astri; Loge, Jon H; Lyngstad, Torkild H

    2010-02-10

    PURPOSE Cancer in children may profoundly affect parents' personal relationships in terms of psychological stress and an increased care burden. This could hypothetically elevate divorce rates. Few studies on divorce occurrence exist, so the effect of childhood cancers on parental divorce rates was explored. PATIENTS AND METHODS Data on the entire Norwegian married population, age 17 to 69 years, with children age 0 to 20 years in 1974 to 2001 (N = 977,928 couples) were retrieved from the Cancer Registry, the Central Population Register, the Directorate of Taxes, and population censuses. Divorce rates for 4,590 couples who were parenting a child with cancer were compared with those of otherwise similar couples by discrete-time hazard regression models. Results Cancer in a child was not associated with an increased risk of parental divorce overall. An increased divorce rate was observed with Wilms tumor (odds ratio [OR], 1.52) but not with any of the other common childhood cancers. The child's age at diagnosis, time elapsed from diagnosis, and death from cancer did not influence divorce rates significantly. Increased divorce rates were observed for couples in whom the mothers had an education greater than high school level (OR, 1.16); the risk was particularly high shortly after diagnosis, for CNS cancers and Wilms tumors, for couples with children 0 to 9 years of age at diagnosis, and after a child's death. CONCLUSION This large, registry-based study shows that cancer in children is not associated with an increased parental divorce rate, except with Wilms tumors. Couples in whom the wife is highly educated appear to face increased divorce rates after a child's cancer, and this may warrant additional study.

  9. Pleiotropic Genes Affecting Carcass Traits in Bos indicus (Nellore) Cattle Are Modulators of Growth.

    PubMed

    G T Pereira, Anirene; Utsunomiya, Yuri T; Milanesi, Marco; Torrecilha, Rafaela B P; Carmo, Adriana S; Neves, Haroldo H R; Carvalheiro, Roberto; Ajmone-Marsan, Paolo; Sonstegard, Tad S; Sölkner, Johann; Contreras-Castillo, Carmen J; Garcia, José F

    2016-01-01

    Two complementary methods, namely Multi-Trait Meta-Analysis and Versatile Gene-Based Test for Genome-wide Association Studies (VEGAS), were used to identify putative pleiotropic genes affecting carcass traits in Bos indicus (Nellore) cattle. The genotypic data comprised over 777,000 single-nucleotide polymorphism markers scored in 995 bulls, and the phenotypic data included deregressed breeding values (dEBV) for weight measurements at birth, weaning and yearling, as well visual scores taken at weaning and yearling for carcass finishing precocity, conformation and muscling. Both analyses pointed to the pleomorphic adenoma gene 1 (PLAG1) as a major pleiotropic gene. VEGAS analysis revealed 224 additional candidates. From these, 57 participated, together with PLAG1, in a network involved in the modulation of the function and expression of IGF1 (insulin like growth factor 1), IGF2 (insulin like growth factor 2), GH1 (growth hormone 1), IGF1R (insulin like growth factor 1 receptor) and GHR (growth hormone receptor), suggesting that those pleiotropic genes operate as satellite regulators of the growth pathway. PMID:27410030

  10. Pleiotropic Genes Affecting Carcass Traits in Bos indicus (Nellore) Cattle Are Modulators of Growth

    PubMed Central

    Milanesi, Marco; Torrecilha, Rafaela B. P.; Carmo, Adriana S.; Neves, Haroldo H. R.; Carvalheiro, Roberto; Ajmone-Marsan, Paolo; Sonstegard, Tad S.; Sölkner, Johann; Contreras-Castillo, Carmen J.; Garcia, José F.

    2016-01-01

    Two complementary methods, namely Multi-Trait Meta-Analysis and Versatile Gene-Based Test for Genome-wide Association Studies (VEGAS), were used to identify putative pleiotropic genes affecting carcass traits in Bos indicus (Nellore) cattle. The genotypic data comprised over 777,000 single-nucleotide polymorphism markers scored in 995 bulls, and the phenotypic data included deregressed breeding values (dEBV) for weight measurements at birth, weaning and yearling, as well visual scores taken at weaning and yearling for carcass finishing precocity, conformation and muscling. Both analyses pointed to the pleomorphic adenoma gene 1 (PLAG1) as a major pleiotropic gene. VEGAS analysis revealed 224 additional candidates. From these, 57 participated, together with PLAG1, in a network involved in the modulation of the function and expression of IGF1 (insulin like growth factor 1), IGF2 (insulin like growth factor 2), GH1 (growth hormone 1), IGF1R (insulin like growth factor 1 receptor) and GHR (growth hormone receptor), suggesting that those pleiotropic genes operate as satellite regulators of the growth pathway. PMID:27410030

  11. Growth pattern and carcase development in male ducks selected for growth rate.

    PubMed

    Maruyama, K; Akbar, M K; Turk, C M

    1999-05-01

    1. Growth patterns of the whole body, eviscerated carcases, breast muscle, leg and thigh muscles and abdominal fat pads were compared in 4 lines (Lines A, B, C, and D) of male ducks selected for market weight (n = 1305) using growth curve analysis, allometric growth analysis and repeated measure analysis. At 49 d of age, Line A was heaviest, followed by Line B, Line C and Line D. 2. Ducks were fed ad libitum under 24-h lighting and 12 or 24 ducks were killed to determine body, carcase, breast-muscle, leg and thigh-muscle, and abdominal fat weights at time points from hatching until 53 d of age. 3. The Weibull function was chosen for growth curve analysis. The asymptote and inflection point from the Weibull growth curves identified 3 lines (Lines B, C, and D) with discrete body and carcase growth patterns but did not distinguish Line A from Line B. In all 4 lines the asymptote ranged from 4437 g to 3008 g for body weight and from 3334 g to 2098 g for carcase weight; the inflection point ranged from 22.5 d to 25.3 d for body weight and from 25.4 d to 29.6 d for carcase weight. 4. The allometric growth coefficient, relative to whole-body growth, was higher than 1.00 for breast muscle and lower than 1.00 for leg and thigh muscles during from 4 d to 53 d of age. 5. Body fat accumulation was estimated by abdominal fat. Line D accumulated more abdominal fat than other lines. The pattern of fat accumulation in Line D was different from Lines A, B and C and there were no differences between Lines A, B and C. PMID:10465391

  12. Dietary nucleotides affect hepatic growth and composition in the weanling mouse.

    PubMed

    Novak, D A; Carver, J D; Barness, L A

    1994-01-01

    The effect of dietary nucleotides upon hepatic growth and composition was examined in weanling mice. For 5 weeks, mice were fed either Purina Rat Chow, a nucleotide-free diet (NT-), a nucleotide-free diet supplemented with a mixture of five nucleotides (0.21% w/w), (NT+) or a nucleotide-free diet supplemented with adenosine 5'-monophosphate (0.0425% w/w) (NTA). Hepatic cholesterol and lipid phosphorous were significantly higher, whereas liver weight (expressed as a percentage of body weight), and glycogen were lower in animals fed NT- vs all other groups. NTA-fed animals presented a greater contrast to the NT- group than did animals fed the mixture of nucleotides. Liver fatty acid composition and distribution of phospholipid subclasses were not affected by dietary nucleotide supplementation. Dietary nucleotide supplementation in weanling mice affects hepatic growth and composition; adenosine 5'-monophosphate may play a unique role in these effects.

  13. Color of illumination during growth affects LHCII chiral macroaggregates in pea plant leaves.

    PubMed

    Gussakovsky, Eugene E; Shahak, Yosepha; Schroeder, Dana F

    2007-02-01

    To determine whether the color of illumination under which plants are grown, affects the structure of photosynthetic antennae, pea plants were grown under either blue-enriched, red-enriched, or white light. Carotenoid content of isolated chloroplasts was found to be insensitive to the color of illumination during growth, while chlorophyll a/b ratio in chloroplasts isolated from young illuminated leaves showed susceptibility to color. Color of illumination affects the LHCII chiral macroaggregates in intact leaves and isolated chloroplasts, providing light-induced alteration of the handedness of the LHCII chiral macroaggregate, as measured with circular dichroism and circularly polarized luminescence. The susceptibility of handedness to current illumination (red light excitation of chlorophyll fluorescence) is dependent on the color under which the plants were grown, and was maximal for the red-enriched illumination. We propose the existence of a long-term (growth period) color memory, which influences the susceptibility of the handedness of LHCII chiral macroaggregates to current light.

  14. Effects of temperature, light and heterotrophy on the growth rate and budding of the temperate coral Cladocora caespitosa

    NASA Astrophysics Data System (ADS)

    Rodolfo-Metalpa, R.; Peirano, A.; Houlbrèque, F.; Abbate, M.; Ferrier-Pagès, C.

    2008-03-01

    Recent investigations have shown the temperate scleractinian coral Cladocora caespitosa to be a new potential climate archive for the Mediterranean Sea. Whilst earlier studies have demonstrated a seasonal variation in growth rates, they were unable to distinguish which environmental parameter (light, temperature, or food) was influencing growth. In this study, the effect of these three factors on the coral physiology and calcification rate was characterized to aid the correct interpretation of skeletal trace element variations. Two temperatures (13 and 23°C), irradiances (50 and 120 μmol m-2 s-1), and feeding regimes (unfed and fed with nauplii of Artemia salina) were tested under controlled laboratory conditions on the growth, zooxanthellae density, chlorophyll (chl) content, and asexual reproduction (budding) of C. caespitosa during a 7-week factorial experiment. Unlike irradiance, which had no effect, high temperature and food supply increased the growth rates of C. caespitosa. The effect of feeding was however higher for corals maintained at low temperature, suggesting that heterotrophy is especially important during the cold season, and that temperature is the predominant factor affecting the coral’s growth. At low temperature, fed samples had higher zooxanthellae density and chl content, possibly for maximizing photosynthetic efficiency. Sexual reproduction investment of C. caespitosa was higher during favourable conditions characterised by high temperatures and zooplankton availability.

  15. High growth rate 4H-SiC epitaxial growth using dichlorosilane in a hot-wall CVD reactor

    NASA Astrophysics Data System (ADS)

    Chowdhury, Iftekhar; Chandrasekhar, M. V. S.; Klein, Paul B.; Caldwell, Joshua D.; Sudarshan, Tangali

    2011-02-01

    Thick, high quality 4H-SiC epilayers have been grown in a vertical hot-wall chemical vapor deposition system at a high growth rate on (0 0 0 1) 8° off-axis substrates. We discuss the use of dichlorosilane as the Si-precursor for 4H-SiC epitaxial growth as it provides the most direct decomposition route into SiCl 2, which is the predominant growth species in chlorinated chemistries. A specular surface morphology was attained by limiting the hydrogen etch rate until the system was equilibrated at the desired growth temperature. The RMS roughness of the grown films ranged from 0.5-2.0 nm with very few morphological defects (carrots, triangular defects, etc.) being introduced, while enabling growth rates of 30-100 μm/h, 5-15 times higher than most conventional growths. Site-competition epitaxy was observed over a wide range of C/Si ratios, with doping concentrations <1×10 14 cm -3 being recorded. X-ray rocking curves indicated that the epilayers were of high crystallinity, with linewidths as narrow as 7.8 arcsec being observed, while microwave photoconductive decay (μPCD) measurements indicated that these films had high injection (ambipolar) carrier lifetimes in the range of 2 μs.

  16. Nitrogen Plant Growth Regulator Rates on Cotton Yield and Fiber Quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The objective of this experiment was to determine the effect of two plant growth regulator (PGR) strategies with and without a high application PGR rate, prior to harvest, on cotton yield and fiber quality across two N rates for a cotton conservation tillage system. Nitrogen rates and PGR strategie...

  17. Demography of forest birds in Panama: How do transients affect estimates of survival rates?

    USGS Publications Warehouse

    Brawn, J.D.; Karr, J.R.; Nichols, J.D.; Robinson, W.D.; Adams, N.J.; Slotow, R.H.

    1998-01-01

    Estimates of annual survival rates for a multispecies sample of neotropical birds from Panama have proven controversial. Traditionally, tropical birds were thought to have high survival rates for their size, but analyses by Kart et al. (1990. Am. Nat. 136:277-91) contradicted that view, suggesting tropical birds may not have systematically high survival rates. A persistent criticism of that study has been that the estimates were biased by transient birds captured only once as they passed through the area being sampled. New models that formally adjust for transient individuals have been developed since 1990. Preliminary analyses using these models indicate that, despite some variation among species, overall estimates of survival rates for understory birds in Panama are not strongly affected by adjustments for transients. We also compare estimates of survival rates based on mark-recapture models with observations of colour-marked birds. The demographic traits of birds in the tropics (and elsewhere) vary within and among species according to combinations of historical and ongoing ecological factors. Understanding sources of this variation is the challenge for future work.

  18. User fee exemption does not affect lower rates of hospital admission of girls in Vietnam.

    PubMed

    Schmidt, Wolf-Peter; Suzuki, Motoi; Thiem, Vu Dinh; Yoshida, Lay-Myint; Matsubayashi, Toru; Yanai, Hideki; Tho, Le Huu; Anh, Dang Duc; Ariyoshi, Koya

    2012-10-01

    In many countries, girls have been reported to be less often admitted to hospital than boys. We studied the influence of socio-economic factors, education and access to health care on girls' and boys' admission rates for pneumonia, diarrhoea and dengue fever in south-central Vietnam. We explored whether the user fee exemption for children under 6 years introduced in 2005 had an impact on girls' admission rates. In a cohort analysis, we used data from a large census in Khanh Hoa Province conducted in 2006, linked to hospital admission records at individual level. We further analysed a cross-sectional health care utilization survey in a sample of children reported ill at the census. There were 38 731 children under 6 years among a total census population of 353 891. Overall, girls under the age of 6 years were 29% less likely to be admitted to hospital than boys. The gender differences in admission rates in children under 6 years were similar for diarrhoea, pneumonia and dengue. None of the socio-economic and educational factors appeared to affect the gender difference. The user fee exemption starting from October 2005 had no impact on the girls/boys rate ratio of admission. In conclusion, the higher hospital admission rates of boys compared with girls in Vietnam are independent of socio-economic factors and user fees. Higher susceptibility of boys to severe disease could explain part of the gender gap, but profound cultural norms and beliefs may also have contributed to the findings.

  19. Technologies that affect the weaning rate in beef cattle production systems.

    PubMed

    Dill, Matheus Dhein; Pereira, Gabriel Ribas; Costa, João Batista Gonçalves; Canellas, Leonardo Canali; Peripolli, Vanessa; Neto, José Braccini; Sant'Anna, Danilo Menezes; McManus, Concepta; Barcellos, Júlio Otávio Jardim

    2015-10-01

    We investigated the differences between weaning rates and technologies adopted by farmers in cow-calf production systems in Rio Grande do Sul State, Brazil. Interviews were carried out with 73 farmers about 48 technologies that could affect reproductive performance. Data were analyzed by multivariate analysis using a non-hierarchical cluster method. The level of significance was set at P < 0.05. Three distinct clusters of farmers were created (R (2) = 0.90), named as low (LWR), intermediate (IWR), and high (HWR) weaning rate, with 100, 91, and 96 % of the farmers identified within their respective groups and average weaning rates of 59, 72, and 83 %, respectively. IWR and HWR farmers used more improved natural pasture, fixed-time artificial insemination, selection for birth weight, and proteinated salt compared to LWR. HWR farmers used more stocking rate control, and IWR farmers used more ultrasound to evaluate reproductive performance compared to the LWR group. IWR and HWR adopted more technologies related to nutrition and reproductive aspects of the herd in comparison to LWR. We concluded that farmers with higher technology use on farm had higher weaning rates which could be used to benefit less efficient farmers.

  20. Geographic after-tax real income differentials and population growth rates.

    PubMed

    Alexander, G; Cebula, R J; Koch, J V

    1990-03-01

    "The purpose of this [one-page] note is to empirically investigate the impact of geographic after-tax real income differentials on geographic population growth rate differentials. The focus is on population growth rates in Florida's 67 counties over the period 1980-88." The authors conclude that "even after allowing for a variety of other location-influencing factors, including coastal access, after-tax real income differentials exercise a positive and significant impact on population growth rate differentials among Florida's counties."

  1. Macronutrient content of plant-based food affects growth of a carnivorous arthropod.

    PubMed

    Wilder, Shawn M; Holway, David A; Suarez, Andrew V; Eubanks, Micky D

    2011-02-01

    Many arthropods engage in mutualisms in which they consume plant-based foods including nectar, extrafloral nectar, and honeydew. However, relatively little is known about the manner in which the specific macronutrients in these plant-based resources affect growth, especially for carnivorous arthropods. Using a combination of laboratory and field experiments, we tested (1) how plant-based foods, together with ad libitum insect prey, affect the growth of a carnivorous ant, Solenopsis invicta, and (2) which macronutrients in these resources (i.e., carbohydrates, amino acids, or both) contribute to higher colony growth. Access to honeydew increased the production of workers and brood in experimental colonies. This growth effect appeared to be due to carbohydrates alone as colonies provided with the carbohydrate component of artificial extrafloral nectar had greater worker and brood production compared to colonies deprived of carbohydrates. Surprisingly, amino acids only had a slight interactive effect on the proportion of a colony composed of brood and negatively affected worker survival. Diet choice in the laboratory and field matched performance in the laboratory with high recruitment to carbohydrate baits and only slight recruitment to amino acids. The strong, positive effects of carbohydrates on colony growth and the low cost of producing this macronutrient for plants and hemipterans may have aided the evolution of food-for-protection mutualisms and help explain why these interactions are so common in ants. In addition, greater access to plant-based resources in the introduced range of S. invicta may help to explain the high densities achieved by this species throughout the southeastern United States.

  2. Macronutrient content of plant-based food affects growth of a carnivorous arthropod.

    PubMed

    Wilder, Shawn M; Holway, David A; Suarez, Andrew V; Eubanks, Micky D

    2011-02-01

    Many arthropods engage in mutualisms in which they consume plant-based foods including nectar, extrafloral nectar, and honeydew. However, relatively little is known about the manner in which the specific macronutrients in these plant-based resources affect growth, especially for carnivorous arthropods. Using a combination of laboratory and field experiments, we tested (1) how plant-based foods, together with ad libitum insect prey, affect the growth of a carnivorous ant, Solenopsis invicta, and (2) which macronutrients in these resources (i.e., carbohydrates, amino acids, or both) contribute to higher colony growth. Access to honeydew increased the production of workers and brood in experimental colonies. This growth effect appeared to be due to carbohydrates alone as colonies provided with the carbohydrate component of artificial extrafloral nectar had greater worker and brood production compared to colonies deprived of carbohydrates. Surprisingly, amino acids only had a slight interactive effect on the proportion of a colony composed of brood and negatively affected worker survival. Diet choice in the laboratory and field matched performance in the laboratory with high recruitment to carbohydrate baits and only slight recruitment to amino acids. The strong, positive effects of carbohydrates on colony growth and the low cost of producing this macronutrient for plants and hemipterans may have aided the evolution of food-for-protection mutualisms and help explain why these interactions are so common in ants. In addition, greater access to plant-based resources in the introduced range of S. invicta may help to explain the high densities achieved by this species throughout the southeastern United States. PMID:21618912

  3. Identifying critical road geometry parameters affecting crash rate and crash type.

    PubMed

    Othman, Sarbaz; Thomson, Robert; Lannér, Gunnar

    2009-10-01

    The objective of this traffic safety investigation was to find critical road parameters affecting crash rate (CR). The study was based on crash and road maintenance data from Western Sweden. More than 3000 crashes, reported from 2000 to 2005 on median-separated roads, were collected and combined with road geometric and surface data. The statistical analysis showed variations in CR when road elements changed confirming that road characteristics affect CR. The findings indicated that large radii right-turn curves were more dangerous than left curves, in particular, during lane changing manoeuvres. However sharper curves are more dangerous in both left and right curves. Moreover, motorway carriageways with no or limited shoulders have the highest CR when compared to other carriageway widths, while one lane carriageway sections on 2+1 roads were the safest. Road surface results showed that both wheel rut depth and road roughness have negative impacts on traffic safety.

  4. Patient-derived xenograft (PDX) tumors increase growth rate with time

    PubMed Central

    Pearson, Alexander T.; Finkel, Kelsey A.; Warner, Kristy A.; Nör, Felipe; Tice, David; Martins, Manoela D.; Jackson, Trachette L.; Nör, Jacques E.

    2016-01-01

    Patient-derived xenograft (PDX) models are frequently used for translational cancer research, and are assumed to behave consistently as the tumor ages. However, growth rate constancy as a function of time is unclear. Notably, variable PDX growth rates over time might have implications for the interpretation of translational studies. We characterized four PDX models through several in vivo passages from primary human head and neck squamous cell carcinoma and salivary gland adenoid cystic carcinoma. We developed a mathematical approach to merge growth data from different passages into a single measure of relative tumor volume normalized to study initiation size. We analyzed log-relative tumor volume increase with linear mixed effect models. Two oral pathologists analyzed the PDX tissues to determine if histopathological feature changes occurred over in vivo passages. Tumor growth rate increased over time. This was determined by repeated measures linear regression statistical analysis in four different PDX models. A quadratic statistical model for the temporal effect predicted the log-relative tumor volume significantly better than a linear time effect model. We found a significant correlation between passage number and histopathological features of higher tumor grade. Our mathematical treatment of PDX data allows statistical analysis of tumor growth data over long periods of time, including over multiple passages. Non-linear tumor growth in our regression models revealed the exponential growth rate increased over time. The dynamic tumor growth rates correlated with quantifiable histopathological changes that related to passage number in multiple types of cancer. PMID:26783960

  5. Effects of loading on the growth rates of deep stress-corrosion cracks

    SciTech Connect

    Beavers, J.A.; Christman, T.K.

    1990-08-01

    The goal of this research program was to determine the effects of loading on growth of stress-corrosion cracks (SCC) in line pipe steel and whether special loading procedures could actually inhibit crack growth. Of particular interest was the effect of hydrostatic retesting on the subsequent growth of existing cracks. The growth rate experiments showed that the slow-strain rate loading could successfully nucleate a group of fine cracks with depths up to 0.025 inches (0.64 mm). However, the subsequent cyclic loading at typical operating stress levels (lower than experienced during the slow- strain rate loading) produced minimal crack growth and stopped soon after the test was started. The limited growth is believed to be a real phenomenon which means this is not a suitable procedure for the measurement of average crack growth rates. These experiments indicate that cracks grown at high stress (as in the slow-strain rate phase) do not readily propagate at lower stress levels. This may be because of crack closure (compressive crack tip residual stress) induced by the initial higher stress level. If that is true, then hydrostatic retests could inhibit the growth of existing stress-corrosion cracks, especially if the hydrostatic tests are conducted at high stress levels. 15 figures, 3 tabs.

  6. Patient-derived xenograft (PDX) tumors increase growth rate with time.

    PubMed

    Pearson, Alexander T; Finkel, Kelsey A; Warner, Kristy A; Nör, Felipe; Tice, David; Martins, Manoela D; Jackson, Trachette L; Nör, Jacques E

    2016-02-16

    Patient-derived xenograft (PDX) models are frequently used for translational cancer research, and are assumed to behave consistently as the tumor ages. However, growth rate constancy as a function of time is unclear. Notably, variable PDX growth rates over time might have implications for the interpretation of translational studies. We characterized four PDX models through several in vivo passages from primary human head and neck squamous cell carcinoma and salivary gland adenoid cystic carcinoma. We developed a mathematical approach to merge growth data from different passages into a single measure of relative tumor volume normalized to study initiation size. We analyzed log-relative tumor volume increase with linear mixed effect models. Two oral pathologists analyzed the PDX tissues to determine if histopathological feature changes occurred over in vivo passages. Tumor growth rate increased over time. This was determined by repeated measures linear regression statistical analysis in four different PDX models. A quadratic statistical model for the temporal effect predicted the log-relative tumor volume significantly better than a linear time effect model. We found a significant correlation between passage number and histopathological features of higher tumor grade. Our mathematical treatment of PDX data allows statistical analysis of tumor growth data over long periods of time, including over multiple passages. Non-linear tumor growth in our regression models revealed the exponential growth rate increased over time. The dynamic tumor growth rates correlated with quantifiable histopathological changes that related to passage number in multiple types of cancer.

  7. Daily changes in temperature, not the circadian clock, regulate growth rate in Brachypodium distachyon.

    PubMed

    Matos, Dominick A; Cole, Benjamin J; Whitney, Ian P; MacKinnon, Kirk J-M; Kay, Steve A; Hazen, Samuel P

    2014-01-01

    Plant growth is commonly regulated by external cues such as light, temperature, water availability, and internal cues generated by the circadian clock. Changes in the rate of growth within the course of a day have been observed in the leaves, stems, and roots of numerous species. However, the relative impact of the circadian clock on the growth of grasses has not been thoroughly characterized. We examined the influence of diurnal temperature and light changes, and that of the circadian clock on leaf length growth patterns in Brachypodium distachyon using high-resolution time-lapse imaging. Pronounced changes in growth rate were observed under combined photocyles and thermocycles or with thermocycles alone. A considerably more rapid growth rate was observed at 28°C than 12°C, irrespective of the presence or absence of light. In spite of clear circadian clock regulated gene expression, plants exhibited no change in growth rate under conditions of constant light and temperature, and little or no effect under photocycles alone. Therefore, temperature appears to be the primary cue influencing observed oscillations in growth rate and not the circadian clock or photoreceptor activity. Furthermore, the size of the leaf meristem and final cell length did not change in response to changes in temperature. Therefore, the nearly five-fold difference in growth rate observed across thermocycles can be attributed to proportionate changes in the rate of cell division and expansion. A better understanding of the growth cues in B. distachyon will further our ability to model metabolism and biomass accumulation in grasses.

  8. Soil Particle Heterogeneity Affects the Growth of a Rhizomatous Wetland Plant

    PubMed Central

    Xue, Wei; Peng, Yi-Ke; Zhang, Ming-Xiang; Yu, Fei-Hai

    2013-01-01

    Soil is commonly composed of particles of different sizes, and soil particle size may greatly affect the growth of plants because it affects soil physical and chemical properties. However, no study has tested the effects of soil particle heterogeneity on the growth of clonal plants. We conducted a greenhouse experiment in which individual ramets of the wetland plant Bolboschoenus planiculmis were grown in three homogeneous soil treatments with uniformly sized quartz particles (small: 0.75 mm, medium: 1.5 mm, or large: 3 mm), one homogeneous treatment with an even mixture of large and medium particles, and two heterogeneous treatments consisting of 16 or 4 patches of large and medium particles. Biomass, ramet number, rhizome length and spacer length were significantly greater in the treatment with only medium particles than in the one with only large particles. Biomass, ramet number, rhizome length and tuber number in the patchy treatments were greater in patches of medium than of large particles; this difference was more pronounced when patches were small than when they were large. Soil particle size and soil particle heterogeneity can greatly affect the growth of clonal plants. Thus, studies to test the effects of soil heterogeneity on clonal plants should distinguish the effects of nutrient heterogeneity from those of particle heterogeneity. PMID:23936110

  9. Nitrogen stress affects the turnover and size of nitrogen pools supplying leaf growth in a grass.

    PubMed

    Lehmeier, Christoph Andreas; Wild, Melanie; Schnyder, Hans

    2013-08-01

    The effect of nitrogen (N) stress on the pool system supplying currently assimilated and (re)mobilized N for leaf growth of a grass was explored by dynamic ¹⁵N labeling, assessment of total and labeled N import into leaf growth zones, and compartmental analysis of the label import data. Perennial ryegrass (Lolium perenne) plants, grown with low or high levels of N fertilization, were labeled with ¹⁵NO₃⁻/¹⁴NO₃⁻ from 2 h to more than 20 d. In both treatments, the tracer time course in N imported into the growth zones fitted a two-pool model (r² > 0.99). This consisted of a "substrate pool," which received N from current uptake and supplied the growth zone, and a recycling/mobilizing "store," which exchanged with the substrate pool. N deficiency halved the leaf elongation rate, decreased N import into the growth zone, lengthened the delay between tracer uptake and its arrival in the growth zone (2.2 h versus 0.9 h), slowed the turnover of the substrate pool (half-life of 3.2 h versus 0.6 h), and increased its size (12.4 μg versus 5.9 μg). The store contained the equivalent of approximately 10 times (low N) and approximately five times (high N) the total daily N import into the growth zone. Its turnover agreed with that of protein turnover. Remarkably, the relative contribution of mobilization to leaf growth was large and similar (approximately 45%) in both treatments. We conclude that turnover and size of the substrate pool are related to the sink strength of the growth zone, whereas the contribution of the store is influenced by partitioning between sinks.

  10. The effect of pulse duration on the growth rate of laser-induced damage sites at 351 nm on fused silica surfaces

    SciTech Connect

    Negres, R A; Norton, M A; Liao, Z M; Cross, D A; Bude, J D; Carr, C W

    2009-10-29

    Past work in the area of laser-induced damage growth has shown growth rates to be primarily dependent on the laser fluence and wavelength. More recent studies suggest that growth rate, similar to the damage initiation process, is affected by a number of additional parameters including pulse duration, pulse shape, site size, and internal structure. In this study, we focus on the effect of pulse duration on the growth rate of laser damage sites located on the exit surface of fused silica optics. Our results demonstrate, for the first time, a significant dependence of growth rate at 351 nm on pulse duration from 1 ns to 15 ns as {tau}{sup 0.3} for sites in the 50-100 {micro}m size range.

  11. Interrelationship between single- and multi-wall carbon nanotube growth rates for CVD process

    SciTech Connect

    Wood, Richard F; Pannala, Sreekanth; Wells, Jack C; Puretzky, Alexander A; Geohegan, David B

    2007-01-01

    Recent time-resolved measurements of carbon nanotube (CNT) growth on Fe and Fe/Mo catalysts have identified a maximum growth rate and temperature corresponding to the onset of small-diameter, single-wall CNT (SWNT) formation. A simple model described here emphasizes the essential role of the SWNTs in the growth process of CNTs. Remarkably, it shows that the growth rate (i.e. the time derivative of the length) of a multi-walled CNT (MWNT) is the same as that of a SWNT at the carbon flux and diffusion coefficient corresponding to a given temperature. Moreover, below ~700C, the temperature above which SWNT growth is observed for a 6 sccm C2H2 flow rate, the number of walls as a function of temperature is uniquely determined by the interplay of the incident flux of atomic C and diffusion rates consistent with bulk diffusion. Even partial melting of the catalytic particle is unnecessary to explain the experimental results on growth rate and number of walls. Above 700C, where severe catalyst poisoning ordinarily begins, the growth rate without poisoning is consistent with recent results of Hata and co-workers for "supergrowth".

  12. Gonadotropin ratio affects the in vitro growth of rhesus ovarian preantral follicles.

    PubMed

    Kim, Yoon Young; Yun, Jun-Won; Kim, Jong Min; Park, Chung Gyu; Rosenwaks, Zev; Liu, Hung Ching; Kang, Byeong-Cheol; Ku, Seung-Yup

    2016-04-01

    In vitro follicle growth (IVFG) strategy is critical in the fertility preservation of cancer survivors; however, its optimal protocol needs to be developed using primate models since the availability of human samples is limited. Only a few previous studies have reported the successful IVFG of rhesus monkey ovaries using low-dose follicle-stimulating hormone (FSH) (0.3 or 3 ng/mL) and long-term culture (up to 5 weeks) and it is still uncertain in regard to the optimal culture duration and effective dose of treated gonadotropins applicable to the IVFG of rhesus preantral follicles. Recently, we have reported that the FSH to luteinizing hormone (LH) ratio affects the in vitro growth of murine ovarian follicles. We aimed to investigate whether gonadotropin ratios affect the efficiency of rhesus follicular growth in vitro Ovaries were collected from six necropsied rhesus macaques (4-9 years) and preantral follicles were retrieved and cultured for 14 days using 200 mIU/mL FSH. The characteristics of follicular growth were compared between the FSH:LH=1:1 (n=24) and FSH:LH=2:1 (n=24) groups. High concentration gonadotropin treatment shortened the duration required for in vitro maturation of rhesus preantral follicles. The FSH:LH=2:1 group showed a faster follicular growth and enabled the acquisition of mature oocytes, although the expression of growth differentiation factor (GDF)-9 and anti-Müllerian hormone (AMH) did not differ significantly between the two groups. Taken together, high dose gonadotropin treatment can shorten the duration of IVFG and the gonadotropin ratio is important in the IVFG of rhesus monkey ovaries.

  13. Gonadotropin ratio affects the in vitro growth of rhesus ovarian preantral follicles

    PubMed Central

    Kim, Yoon Young; Yun, Jun-Won; Kim, Jong Min; Park, Chung Gyu; Rosenwaks, Zev; Liu, Hung Ching; Kang, Byeong-Cheol; Ku, Seung-Yup

    2016-01-01

    In vitro follicle growth (IVFG) strategy is critical in the fertility preservation of cancer survivors; however, its optimal protocol needs to be developed using primate models since the availability of human samples is limited. Only a few previous studies have reported the successful IVFG of rhesus monkey ovaries using low-dose follicle-stimulating hormone (FSH) (0.3 or 3 ng/mL) and long-term culture (up to 5 weeks) and it is still uncertain in regard to the optimal culture duration and effective dose of treated gonadotropins applicable to the IVFG of rhesus preantral follicles. Recently, we have reported that the FSH to luteinizing hormone (LH) ratio affects the in vitro growth of murine ovarian follicles. We aimed to investigate whether gonadotropin ratios affect the efficiency of rhesus follicular growth in vitro. Ovaries were collected from six necropsied rhesus macaques (4–9 years) and preantral follicles were retrieved and cultured for 14 days using 200 mIU/mL FSH. The characteristics of follicular growth were compared between the FSH:LH=1:1 (n=24) and FSH:LH=2:1 (n=24) groups. High concentration gonadotropin treatment shortened the duration required for in vitro maturation of rhesus preantral follicles. The FSH:LH=2:1 group showed a faster follicular growth and enabled the acquisition of mature oocytes, although the expression of growth differentiation factor (GDF)-9 and anti-Müllerian hormone (AMH) did not differ significantly between the two groups. Taken together, high dose gonadotropin treatment can shorten the duration of IVFG and the gonadotropin ratio is important in the IVFG of rhesus monkey ovaries. PMID:26980777

  14. Elevational variation in adult body size and growth rate but not in metabolic rate in the tree weta Hemideina crassidens.

    PubMed

    Bulgarella, Mariana; Trewick, Steven A; Godfrey, A Jonathan R; Sinclair, Brent J; Morgan-Richards, Mary

    2015-04-01

    Populations of the same species inhabiting distinct localities experience different ecological and climatic pressures that might result in differentiation in traits, particularly those related to temperature. We compared metabolic rate (and its thermal sensitivity), growth rate, and body size among nine high- and low-elevation populations of the Wellington tree weta, Hemideina crassidens, distributed from 9 to 1171 m a.s.l across New Zealand. Our results did not indicate elevational compensation in metabolic rates (metabolic cold adaptation). Cold acclimation decreased metabolic rate compared to warm-acclimated individuals from both high- and low-elevation populations. However, we did find countergradient variation in growth rates, with individuals from high-elevation populations growing faster and to a larger final size than individuals from low-elevation populations. Females grew faster to a larger size than males, although as adults their metabolic rates did not differ significantly. The combined physiological and morphological data suggest that high-elevation individuals grow quickly and achieve larger size while maintaining metabolic rates at levels not significantly different from low-elevation individuals. Thus, morphological differentiation among tree weta populations, in concert with genetic variation, might provide the material required for adaptation to changing conditions.

  15. Stool consistency is strongly associated with gut microbiota richness and composition, enterotypes and bacterial growth rates

    PubMed Central

    Vandeputte, Doris; Falony, Gwen; Vieira-Silva, Sara; Tito, Raul Y; Joossens, Marie; Raes, Jeroen

    2016-01-01

    Objective The assessment of potentially confounding factors affecting colon microbiota composition is essential to the identification of robust microbiome based disease markers. Here, we investigate the link between gut microbiota variation and stool consistency using Bristol Stool Scale classification, which reflects faecal water content and activity, and is considered a proxy for intestinal colon transit time. Design Through 16S rDNA Illumina profiling of faecal samples of 53 healthy women, we evaluated associations between microbiome richness, Bacteroidetes:Firmicutes ratio, enterotypes, and genus abundance with self-reported, Bristol Stool Scale-based stool consistency. Each sample’s microbiota growth potential was calculated to test whether transit time acts as a selective force on gut bacterial growth rates. Results Stool consistency strongly correlates with all known major microbiome markers. It is negatively correlated with species richness, positively associated to the Bacteroidetes:Firmicutes ratio, and linked to Akkermansia and Methanobrevibacter abundance. Enterotypes are distinctly distributed over the BSS-scores. Based on the correlations between microbiota growth potential and stool consistency scores within both enterotypes, we hypothesise that accelerated transit contributes to colon ecosystem differentiation. While shorter transit times can be linked to increased abundance of fast growing species in Ruminococcaceae-Bacteroides samples, hinting to a washout avoidance strategy of faster replication, this trend is absent in Prevotella-enterotyped individuals. Within this enterotype adherence to host tissue therefore appears to be a more likely bacterial strategy to cope with washout. Conclusions The strength of the associations between stool consistency and species richness, enterotypes and community composition emphasises the crucial importance of stool consistency assessment in gut metagenome-wide association studies. PMID:26069274

  16. Growth against entropy in bacterial metabolism: the phenotypic trade-off behind empirical growth rate distributions in E. coli

    NASA Astrophysics Data System (ADS)

    De Martino, Daniele; Capuani, Fabrizio; De Martino, Andrea

    2016-06-01

    The solution space of genome-scale models of cellular metabolism provides a map between physically viable flux configurations and cellular metabolic phenotypes described, at the most basic level, by the corresponding growth rates. By sampling the solution space of E. coli's metabolic network, we show that empirical growth rate distributions recently obtained in experiments at single-cell resolution can be explained in terms of a trade-off between the higher fitness of fast-growing phenotypes and the higher entropy of slow-growing ones. Based on this, we propose a minimal model for the evolution of a large bacterial population that captures this trade-off. The scaling relationships observed in experiments encode, in such frameworks, for the same distance from the maximum achievable growth rate, the same degree of growth rate maximization, and/or the same rate of phenotypic change. Being grounded on genome-scale metabolic network reconstructions, these results allow for multiple implications and extensions in spite of the underlying conceptual simplicity.

  17. Ab initio determination of the instability growth rate of warm dense beryllium-deuterium interface

    SciTech Connect

    Wang, Cong; Zhang, Ping; Li, Zi; Li, DaFang

    2015-10-15

    Accurate knowledge about the interfacial unstable growth is of great importance in inertial confinement fusion. During implosions, the deuterium-tritium capsule is driven by laser beams or X-rays to access the strongly coupled and partially degenerated warm dense matter regime. At this stage, the effects of dissipative processes, such as diffusion and viscosity, have significant impact on the instability growth rates. Here, we present ab initio molecular dynamics simulations to determine the equations of state and the transport coefficients. Several models are used to estimate the reduction in the growth rate dispersion curves of Rayleigh-Taylor and Richtmyer-Meshkov instabilities with considering the presence of these dissipative effects. We show that these instability growth rates are effectively reduced when considering diffusion. The findings provide significant insights into the microscopic mechanism of the instability growth at the ablator-fuel interface and will refine the models used in the laser-driven hydrodynamic instability experiments.

  18. Delta L: An Apparatus for Measuring Macromolecular Crystal Growth Rates in Microgravity

    NASA Technical Reports Server (NTRS)

    Judge, Russell A.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    In order to determine how macromolecule crystal quality improvement in microgravity is related to crystal growth characteristics, is was necessary to develop new hardware that could measure the crystal growth rates of a population of crystals growing under the same solution conditions. As crystal growth rate is defined as the change or delta in a defined dimension or length (L) of a crystal over time, the hardware was named Delta L. Delta L consists of fluids, optics, and data acquisition, sub-assemblies. Temperature control is provided for the crystal growth chamber. Delta L will be used in connection with the Glovebox Integrated Microgravity Isolation Technology (g-LIMIT) inside the Microgravity Science Glovebox (MSG), onboard the International Space Station (ISS). Delta L prototype hardware has been assembled. This paper will describe an overview of the design of Delta L and present preliminary crystal growth rate data.

  19. Strain-energy release rate analysis of cyclic delamination growth in compressively loaded laminates

    NASA Technical Reports Server (NTRS)

    Whitcomb, J. D.

    1984-01-01

    Delamination growth in compressively loaded composite laminates was studied analytically and experimentally. The configuration used was a laminate with an across-the-width delamination. An approximate super-position stress analysis was developed to quantify the effects of various geometric, material, and load parameters on mode 1 and mode 2 strain energy release rates G sub 1 and G sub 2, respectively. Calculated values of G sub 1 and G sub 2 were then compared with measured cyclic delamination growth rates to determine the relative importance of G sub 1 and G sub 2. High growth rates were observed only when G sub 1 was large. However, slow growth was observed even when G sub 1 was negligibly small. This growth was apparently due to a large value of G sub 2.

  20. Strain energy release rate analysis of cyclic delamination growth in compressively loaded laminates

    NASA Technical Reports Server (NTRS)

    Whitcomb, J. D.

    1983-01-01

    Delamination growth in compressively loaded composite laminates was studied analytically and experimentally. The configuration used was a laminate with an across-the-width delamination. An approximate super-position stress analysis was developed to quantify the effects of various geometric, material, and load parameters on mode 2 and mode 2 strain energy release rates G sub/1 and G sub 2, respectively. Calculated values of G sub 1 and G sub 2 were then compared with measured cyclic delamination growth rates to determine the relative importance of G sub 1 and G sub 2. High growth rates were observed only when G sub 1 was large. However, slow growth was observed even when G sub 1 was negligibly small. This growth apparently was due to a large value of G sub 2.

  1. Endogenous and exogenous estrogens during embryonic development affect timing of hatch and growth in the American alligator (Alligator mississippiensis).

    PubMed

    Cruze, Lori; Roark, Alison M; Rolland, Gabrielle; Younas, Mona; Stacy, Nicole; Guillette, Louis J

    2015-06-01

    Prenatal exposure to estrogenic endocrine disrupting chemicals (EDCs) can affect length of gestation and body mass and size of offspring. However, the dose, timing, and duration of exposure as well as sex and strain of the experimental animals determine the direction and magnitude of these effects. In this study, we examined the effects of a one-time embryonic exposure to either 17 β-estradiol (E2) or bisphenol A (BPA) on rate of development and growth in American alligators (Alligator mississippiensis). Our results indicate that BPA and E2-treated alligators hatched approximately 1.4 days earlier than vehicle-treated (control) alligators, suggesting that estrogenic chemicals hasten hatching in these animals. We assessed growth rates, growth allometry, and body condition for 21 weeks after hatching and found that BPA-treated alligators grew more quickly shortly after hatching but more slowly thereafter compared to control alligators. Conversely, E2-treated alligators grew more slowly shortly after hatching but more quickly thereafter compared to control alligators. As a result of differences in growth rate, BPA-treated alligators were heavier, longer, and fatter than control alligators at age 5 weeks but were similar in size and leaner than control alligators at age 21 weeks. Biochemical analytes were examined at the end of the 21-week study to assess overall metabolic condition. We found that E2-treated alligators had significantly higher circulating plasma concentrations of cholesterol and triglycerides than control alligators while BPA-treated alligators had blood profiles comparable to control alligators. Our results provide important insights into the effects of exogenous estrogens on morphology and metabolism in an oviparous, semi-aquatic reptile.

  2. CO2 and fertility affect growth and reproduction but not susceptibility to aphids in field grown Solanum ptycanthum

    SciTech Connect

    Long, T.M.

    1995-09-01

    In general, C3 annual plants respond positively in terms of growth, reproduction and biomass accrued when grown under elevated levels of atmospheric carbon dioxide. However, most studies documenting this response have been conducted in growth chambers where plants can be reared under conditions free form environmental stressors such as nutrient and water constraints, UV exposure and damage from pests. During the 1993 fieldseason, I grew 200 individuals of Solanum ptycanthum in an array of 10 outdoor, open-topped CO2 enclosures (5 @ 700 ppm CO2) at the University of Michigan Biological Station in Pellston, MI. Half of the plants were grown in a 50;50 mix of native C-horizon soil and topsoil (low fertility); the other half were grown in 100% topsoil (high-fertility). Plants were censused throughout the growing season for flower and fruit production, growth rate and degree of infestation of aphids. Fertility and CO2 both significantly affected production of flowers and fruits, but only fertility was significantly related to vegetative growth. Aphid infestation varied significantly among enclosures, but was not related to CO2 or fertility.

  3. Effects of Phlomis umbrosa Root on Longitudinal Bone Growth Rate in Adolescent Female Rats.

    PubMed

    Lee, Donghun; Kim, Young-Sik; Song, Jungbin; Kim, Hyun Soo; Lee, Hyun Jung; Guo, Hailing; Kim, Hocheol

    2016-01-01

    This study aimed to investigate the effects of Phlomis umbrosa root on bone growth and growth mediators in rats. Female adolescent rats were administered P. umbrosa extract, recombinant human growth hormone or vehicle for 10 days. Tetracycline was injected intraperitoneally to produce a glowing fluorescence band on the newly formed bone on day 8, and 5-bromo-2'-deoxyuridine was injected to label proliferating chondrocytes on days 8-10. To assess possible endocrine or autocrine/paracrine mechanisms, we evaluated insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein-3 (IGFBP-3) or bone morphogenetic protein-2 (BMP-2) in response to P. umbrosa administration in either growth plate or serum. Oral administration of P. umbrosa significantly increased longitudinal bone growth rate, height of hypertrophic zone and chondrocyte proliferation of the proximal tibial growth plate. P. umbrosa also increased serum IGFBP-3 levels and upregulated the expressions of IGF-1 and BMP-2 in growth plate. In conclusion, P. umbrosa increases longitudinal bone growth rate by stimulating proliferation and hypertrophy of chondrocyte with the increment of circulating IGFBP-3. Regarding the immunohistochemical study, the effect of P. umbrosa may also be attributable to upregulation of local IGF-1 and BMP-2 expressions in the growth plate, which can be considered as a GH dependent autocrine/paracrine pathway. PMID:27070559

  4. Effect of Oxygen-Supply Rates on Growth of Escherichia coli

    PubMed Central

    McDaniel, L. E.; Bailey, E. G.; Zimmerli, A.

    1965-01-01

    The effect of oxygen-supply rates on bacterial growth was studied in commercially available unbaffled and baffled flasks with the use of Escherichia coli in a synthetic medium as a test system. The amount of growth obtained depended on the oxygen-supply rate. Based on oxygen-absorption rates (OAR) measured by the rate of sulfite oxidation, equal OAR values in different types of flasks did not give equal amounts of growth. However, growth was essentially equal at the equal sulfite-oxidation rates when these were determined in the presence of killed whole cultures. Specific growth rates were reduced only at oxygen-supply rates much lower than those at which the total amount of growth was reduced. For the physical set-up used in this work and with the biological system employed, Bellco 598 flasks and flasks fitted with Biotech stainless-steel baffles gave satisfactory results at workable broth volumes; unbaffled and Bellco 600 flasks did not. PMID:14264837

  5. Bushmeat poaching reduces the seed dispersal and population growth rate of a mammal-dispersed tree.

    PubMed

    Brodie, Jedediah F; Helmy, Olga E; Brockelman, Warren Y; Maron, John L

    2009-06-01

    Myriad tropical vertebrates are threatened by overharvest. Whether this harvest has indirect effects on nonhunted organisms that interact with the game species is a critical question. Many tropical birds and mammals disperse seeds. Their overhunting in forests can cause zoochorous trees to suffer from reduced seed dispersal. Yet how these reductions in seed dispersal influence tree abundance and population dynamics remains unclear. Reproductive parameters in long-lived organisms often have very low elasticities; indeed the demographic importance of seed dispersal is an open question. We asked how variation in hunting pressure across four national parks with seasonal forest in northern Thailand influenced the relative abundance of gibbons, muntjac deer, and sambar deer, the sole dispersers of seeds of the canopy tree Choerospondias axillaris. We quantified how variation in disperser numbers affected C. axillaris seed dispersal and seedling abundance across the four parks. We then used these data in a structured population model based on vital rates measured in Khao Yai National Park (where poaching pressure is minimal) to explore how variation in illegal hunting pressure might influence C. axillaris population growth and persistence. Densities of the mammals varied strongly