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Sample records for growth rate dependent

  1. Connection between the growth rate distribution and the size dependent crystal growth

    Science.gov (United States)

    Mitrović, M. M.; Žekić, A. A.; IIić, Z. Z.

    2002-07-01

    The results of investigations of the connection between the growth rate dispersions and the size dependent crystal growth of potassium dihydrogen phosphate (KDP), Rochelle salt (RS) and sodium chlorate (SC) are presented. A possible way out of the existing confusion in the size dependent crystal growth investigations is suggested. It is shown that the size independent growth exists if the crystals belonging to one growth rate distribution maximum are considered separately. The investigations suggest possible reason for the observed distribution maxima widths, and the high data scattering on the growth rate versus the crystal size dependence.

  2. Growth-rate-dependent dynamics of a bacterial genetic oscillator

    Science.gov (United States)

    Osella, Matteo; Lagomarsino, Marco Cosentino

    2013-01-01

    Gene networks exhibiting oscillatory dynamics are widespread in biology. The minimal regulatory designs giving rise to oscillations have been implemented synthetically and studied by mathematical modeling. However, most of the available analyses generally neglect the coupling of regulatory circuits with the cellular “chassis” in which the circuits are embedded. For example, the intracellular macromolecular composition of fast-growing bacteria changes with growth rate. As a consequence, important parameters of gene expression, such as ribosome concentration or cell volume, are growth-rate dependent, ultimately coupling the dynamics of genetic circuits with cell physiology. This work addresses the effects of growth rate on the dynamics of a paradigmatic example of genetic oscillator, the repressilator. Making use of empirical growth-rate dependencies of parameters in bacteria, we show that the repressilator dynamics can switch between oscillations and convergence to a fixed point depending on the cellular state of growth, and thus on the nutrients it is fed. The physical support of the circuit (type of plasmid or gene positions on the chromosome) also plays an important role in determining the oscillation stability and the growth-rate dependence of period and amplitude. This analysis has potential application in the field of synthetic biology, and suggests that the coupling between endogenous genetic oscillators and cell physiology can have substantial consequences for their functionality.

  3. Resolving nanoparticle growth mechanisms from size- and time-dependent growth rate analysis

    Science.gov (United States)

    Pichelstorfer, Lukas; Stolzenburg, Dominik; Ortega, John; Karl, Thomas; Kokkola, Harri; Laakso, Anton; Lehtinen, Kari E. J.; Smith, James N.; McMurry, Peter H.; Winkler, Paul M.

    2018-01-01

    Atmospheric new particle formation occurs frequently in the global atmosphere and may play a crucial role in climate by affecting cloud properties. The relevance of newly formed nanoparticles depends largely on the dynamics governing their initial formation and growth to sizes where they become important for cloud microphysics. One key to the proper understanding of nanoparticle effects on climate is therefore hidden in the growth mechanisms. In this study we have developed and successfully tested two independent methods based on the aerosol general dynamics equation, allowing detailed retrieval of time- and size-dependent nanoparticle growth rates. Both methods were used to analyze particle formation from two different biogenic precursor vapors in controlled chamber experiments. Our results suggest that growth rates below 10 nm show much more variation than is currently thought and pin down the decisive size range of growth at around 5 nm where in-depth studies of physical and chemical particle properties are needed.

  4. Size-dependent standard deviation for growth rates: empirical results and theoretical modeling.

    Science.gov (United States)

    Podobnik, Boris; Horvatic, Davor; Pammolli, Fabio; Wang, Fengzhong; Stanley, H Eugene; Grosse, I

    2008-05-01

    We study annual logarithmic growth rates R of various economic variables such as exports, imports, and foreign debt. For each of these variables we find that the distributions of R can be approximated by double exponential (Laplace) distributions in the central parts and power-law distributions in the tails. For each of these variables we further find a power-law dependence of the standard deviation sigma(R) on the average size of the economic variable with a scaling exponent surprisingly close to that found for the gross domestic product (GDP) [Phys. Rev. Lett. 81, 3275 (1998)]. By analyzing annual logarithmic growth rates R of wages of 161 different occupations, we find a power-law dependence of the standard deviation sigma(R) on the average value of the wages with a scaling exponent beta approximately 0.14 close to those found for the growth of exports, imports, debt, and the growth of the GDP. In contrast to these findings, we observe for payroll data collected from 50 states of the USA that the standard deviation sigma(R) of the annual logarithmic growth rate R increases monotonically with the average value of payroll. However, also in this case we observe a power-law dependence of sigma(R) on the average payroll with a scaling exponent beta approximately -0.08 . Based on these observations we propose a stochastic process for multiple cross-correlated variables where for each variable (i) the distribution of logarithmic growth rates decays exponentially in the central part, (ii) the distribution of the logarithmic growth rate decays algebraically in the far tails, and (iii) the standard deviation of the logarithmic growth rate depends algebraically on the average size of the stochastic variable.

  5. Size-dependent standard deviation for growth rates: Empirical results and theoretical modeling

    Science.gov (United States)

    Podobnik, Boris; Horvatic, Davor; Pammolli, Fabio; Wang, Fengzhong; Stanley, H. Eugene; Grosse, I.

    2008-05-01

    We study annual logarithmic growth rates R of various economic variables such as exports, imports, and foreign debt. For each of these variables we find that the distributions of R can be approximated by double exponential (Laplace) distributions in the central parts and power-law distributions in the tails. For each of these variables we further find a power-law dependence of the standard deviation σ(R) on the average size of the economic variable with a scaling exponent surprisingly close to that found for the gross domestic product (GDP) [Phys. Rev. Lett. 81, 3275 (1998)]. By analyzing annual logarithmic growth rates R of wages of 161 different occupations, we find a power-law dependence of the standard deviation σ(R) on the average value of the wages with a scaling exponent β≈0.14 close to those found for the growth of exports, imports, debt, and the growth of the GDP. In contrast to these findings, we observe for payroll data collected from 50 states of the USA that the standard deviation σ(R) of the annual logarithmic growth rate R increases monotonically with the average value of payroll. However, also in this case we observe a power-law dependence of σ(R) on the average payroll with a scaling exponent β≈-0.08 . Based on these observations we propose a stochastic process for multiple cross-correlated variables where for each variable (i) the distribution of logarithmic growth rates decays exponentially in the central part, (ii) the distribution of the logarithmic growth rate decays algebraically in the far tails, and (iii) the standard deviation of the logarithmic growth rate depends algebraically on the average size of the stochastic variable.

  6. Wavelength dependence of the linear growth rate of the Es layer instability

    Directory of Open Access Journals (Sweden)

    R. B. Cosgrove

    2007-06-01

    Full Text Available It has recently been shown, by computation of the linear growth rate, that midlatitude sporadic-E (Es layers are subject to a large scale electrodynamic instability. This instability is a logical candidate to explain certain frontal structuring events, and polarization electric fields, which have been observed in Es layers by ionosondes, by coherent scatter radars, and by rockets. However, the original growth rate derivation assumed an infinitely thin Es layer, and therefore did not address the short wavelength cutoff. Also, the same derivation ignored the effects of F region loading, which is a significant wavelength dependent effect. Herein is given a generalized derivation that remedies both these short comings, and thereby allows a computation of the wavelength dependence of the linear growth rate, as well as computations of various threshold conditions. The wavelength dependence of the linear growth rate is compared with observed periodicities, and the role of the zeroth order meridional wind is explored. A three-dimensional paper model is used to explain the instability geometry, which has been defined formally in previous works.

  7. Cell Size and Growth Rate Are Modulated by TORC2-Dependent Signals.

    Science.gov (United States)

    Lucena, Rafael; Alcaide-Gavilán, Maria; Schubert, Katherine; He, Maybo; Domnauer, Matthew G; Marquer, Catherine; Klose, Christian; Surma, Michal A; Kellogg, Douglas R

    2018-01-22

    The size of all cells, from bacteria to vertebrates, is proportional to the growth rate set by nutrient availability, but the underlying mechanisms are unknown. Here, we show that nutrients modulate cell size and growth rate via the TORC2 signaling network in budding yeast. An important function of the TORC2 network is to modulate synthesis of ceramide lipids, which play roles in signaling. TORC2-dependent control of ceramide signaling strongly influences both cell size and growth rate. Thus, cells that cannot make ceramides fail to modulate their growth rate or size in response to changes in nutrients. PP2A associated with the Rts1 regulatory subunit (PP2A Rts1 ) is embedded in a feedback loop that controls TORC2 signaling and helps set the level of TORC2 signaling to match nutrient availability. Together, the data suggest a model in which growth rate and cell size are mechanistically linked by ceramide-dependent signals arising from the TORC2 network. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Translation elicits a growth rate-dependent, genome-wide, differential protein production in Bacillus subtilis.

    Science.gov (United States)

    Borkowski, Olivier; Goelzer, Anne; Schaffer, Marc; Calabre, Magali; Mäder, Ulrike; Aymerich, Stéphane; Jules, Matthieu; Fromion, Vincent

    2016-05-17

    Complex regulatory programs control cell adaptation to environmental changes by setting condition-specific proteomes. In balanced growth, bacterial protein abundances depend on the dilution rate, transcript abundances and transcript-specific translation efficiencies. We revisited the current theory claiming the invariance of bacterial translation efficiency. By integrating genome-wide transcriptome datasets and datasets from a library of synthetic gfp-reporter fusions, we demonstrated that translation efficiencies in Bacillus subtilis decreased up to fourfold from slow to fast growth. The translation initiation regions elicited a growth rate-dependent, differential production of proteins without regulators, hence revealing a unique, hard-coded, growth rate-dependent mode of regulation. We combined model-based data analyses of transcript and protein abundances genome-wide and revealed that this global regulation is extensively used in B. subtilis We eventually developed a knowledge-based, three-step translation initiation model, experimentally challenged the model predictions and proposed that a growth rate-dependent drop in free ribosome abundance accounted for the differential protein production. © 2016 The Authors. Published under the terms of the CC BY 4.0 license.

  9. Rate-Independent Processes with Linear Growth Energies and Time-Dependent Boundary Conditions

    Czech Academy of Sciences Publication Activity Database

    Kružík, Martin; Zimmer, J.

    2012-01-01

    Roč. 5, č. 3 (2012), s. 591-604 ISSN 1937-1632 R&D Projects: GA AV ČR IAA100750802 Grant - others:GA ČR(CZ) GAP201/10/0357 Institutional research plan: CEZ:AV0Z10750506 Keywords : concentrations * oscillations * time - dependent boundary conditions * rate-independent evolution Subject RIV: BA - General Mathematics http://library.utia.cas.cz/separaty/2011/MTR/kruzik-rate-independent processes with linear growth energies and time - dependent boundary conditions.pdf

  10. Growth rates of rhizosphere microorganisms depend on competitive abilities of plants for nitrogen

    Science.gov (United States)

    Blagodatskaya, Evgenia; Littschwager, Johanna; Lauerer, Marianna; Kuzyakov, Yakov

    2010-05-01

    Rhizosphere - one of the most important ‘hot spots' in soil - is characterized not only by accelerated turnover of microbial biomass and nutrients but also by strong intra- and inter-specific competition. Intra-specific competition occurs between individual plants of the same species, while inter-specific competition can occur both at population level (plant species-specific, microbial species-specific interactions) and at community level (plant - microbial interactions). Such plant - microbial interactions are mainly governed by competition for available N sources, since N is one of the main growth limiting nutrients in natural ecosystems. Functional structure and activity of microbial community in rhizosphere is not uniform and is dependent on quantity and quality of root exudates which are plant specific. It is still unclear how microbial growth and turnover in the rhizosphere are dependent on the features and competitive abilities of plants for N. Depending on C and N availability, acceleration and even retardation of microbial activity and carbon mineralization can be expected in the rhizosphere of plants with high competitive abilities for N. We hypothesized slower microbial growth rates in the rhizosphere of plants with smaller roots, as they usually produce less exudates compared to plants with small shoot-to-root ratio. As the first hypothesis is based solely on C availability, we also expected the greater effect of N availability on microbial growth in rhizosphere of plants with smaller root mass. These hypothesis were tested for two plant species of strawberry: Fragaria vesca L. (native species), and Duchesnea indica (Andrews) Focke (an invasive plant in central Europe) growing in intraspecific and interspecific competition. Microbial biomass and the kinetic parameters of microbial growth in the rhizosphere were estimated by dynamics of CO2 emission from the soil amended with glucose and nutrients. Specific growth rate (µ) of soil microorganisms was

  11. Transcription factor control of growth rate dependent genes in Saccharomyces cerevisiae: A three factor design

    DEFF Research Database (Denmark)

    Fazio, Alessandro; Jewett, Michael Christopher; Daran-Lapujade, Pascale

    2008-01-01

    , such as Ace2 and Swi6, and stress response regulators, such as Yap1, were also shown to have significantly enriched target sets. Conclusion: Our work, which is the first genome-wide gene expression study to investigate specific growth rate and consider the impact of oxygen availability, provides a more......Background: Characterization of cellular growth is central to understanding living systems. Here, we applied a three-factor design to study the relationship between specific growth rate and genome-wide gene expression in 36 steady-state chemostat cultures of Saccharomyces cerevisiae. The three...... factors we considered were specific growth rate, nutrient limitation, and oxygen availability. Results: We identified 268 growth rate dependent genes, independent of nutrient limitation and oxygen availability. The transcriptional response was used to identify key areas in metabolism around which m...

  12. Density Dependence and Growth Rate: Evolutionary Effects on Resistance Development to Bt (Bacillus thuringiensis).

    Science.gov (United States)

    Martinez, Jeannette C; Caprio, Michael A; Friedenberg, Nicholas A

    2018-02-09

    It has long been recognized that pest population dynamics can affect the durability of a pesticide, but dose remains the primary component of insect resistance management (IRM). For transgenic pesticidal traits such as Bt (Bacillus thuringiensis Berliner (Bacillales: Bacillaceae)), dose (measured as the mortality of susceptibles caused by a toxin) is a relatively fixed characteristic and often falls below the standard definition of high dose. Hence, it is important to understand how pest population dynamics modify durability and what targets they present for IRM. We used a deterministic model of a generic arthropod pest to examine how timing and strength of density dependence interacted with population growth rate and Bt mortality to affect time to resistance. As in previous studies, durability typically reached a minimum at intermediate doses. However, high population growth rates could eliminate benefits of high dose. The timing of density dependence had a more subtle effect. If density dependence operated simultaneously with Bt mortality, durability was insensitive to its strengths. However, if density dependence was driven by postselection densities, decreasing its strength could increase durability. The strength of density dependence could affect durability of both single traits and pyramids, but its influence depended on the timing of density dependence and size of the refuge. Our findings suggest the utility of a broader definition of high dose, one that incorporates population-dynamic context. That maximum growth rates and timing and strength of interactions causing density dependent mortality can all affect durability, also highlights the need for ecologically integrated approaches to IRM research. © The Author(s) 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  13. Rate-dependent mode I interlaminar crack growth mechanisms in graphite/epoxy and graphite/PEEK

    Science.gov (United States)

    Gillespie, J. W., Jr.; Carlsson, L. A.; Smiley, A. J.

    1987-01-01

    In this paper the mode I fracture behavior of graphite/epoxy and graphite/PEEK composites is examined over four decades of crosshead rates (0.25-250 mm/min). Straight-sided double-cantilever-beam specimens consisting of unidirectional laminates were tested at room temperature. For graphite/epoxy the load-deflection response was linear to fracture, and stable slow crack growth initiating at the highest load level was observed for all rates tested. In contrast, mode I crack growth in the graphite/PEEK material was often unstable and showed stick-slip behavior. Subcritical crack growth occurring prior to the onset of fracture was observed at intermediate displacement rates. A mechanism for the fracture behavior of the graphite/PEEK material (based on viscoelastic, plastic, and microcrack coalescence in the process zone) is proposed and related to the observed rate-dependent phenomena.

  14. Growth-Rate Dependent Regulation of tRNA Level and Charging in Bacillus licheniformis.

    Science.gov (United States)

    Ferro, Iolanda; Liebeton, Klaus; Ignatova, Zoya

    2017-10-13

    Cellular growth crucially depends on protein synthesis and the abundance of translational components. Among them, aminoacyl-tRNAs play a central role in biosynthesis and shape the kinetics of mRNA translation, thus influencing protein production. Here, we used microarray-based approaches to determine the charging levels and tRNA abundance of Bacillus licheniformis. We observed an interesting cross-talk among tRNA expression, charging pattern, and growth rate. For a large subset of tRNAs, we found a co-regulated and augmented expression at high growth rate. Their tRNA aminoacylation level is kept relatively constant through riboswitch-regulated expression of the cognate aminoacyl-tRNA-synthetase (AARS). We show that AARSs with putative riboswitch-controlled expression are those charging tRNAs with amino acids which disfavor cell growth when individually added to the nutrient medium. Our results suggest that the riboswitch-regulated AARS expression in B. licheniformis is a powerful mechanism not only to maintain a constant ratio of aminoacyl-tRNA independent of the growth rate but concomitantly to control the intracellular level of free amino acids. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Testing linear growth rate formulas of non-scale endogenous growth models

    NARCIS (Netherlands)

    Ziesemer, Thomas

    2017-01-01

    Endogenous growth theory has produced formulas for steady-state growth rates of income per capita which are linear in the growth rate of the population. Depending on the details of the models, slopes and intercepts are positive, zero or negative. Empirical tests have taken over the assumption of

  16. Laboratory observations of temperature and humidity dependencies of nucleation and growth rates of sub-3 nm particles

    Science.gov (United States)

    Yu, Huan; Dai, Liang; Zhao, Yi; Kanawade, Vijay P.; Tripathi, Sachchida N.; Ge, Xinlei; Chen, Mindong; Lee, Shan-Hu

    2017-02-01

    Temperature and relative humidity (RH) are the most important thermodynamic parameters in aerosol formation, yet laboratory studies of nucleation and growth dependencies on temperature and RH are lacking. Here we report the experimentally observed temperature and RH dependences of sulfuric acid aerosol nucleation and growth. Experiments were performed in a flow tube in the temperature range from 248 to 313 K, RH from 0.8% to 79%, and relative acidity (RA) of sulfuric acid from 6 × 10-5 to 0.38 (2 × 107-109 cm-3). The impurity levels of base compounds were determined to be NH3 nucleation at fixed sulfuric acid concentration but impede nucleation when RA is fixed. It is also shown that binary nucleation of sulfuric acid and water is negligible in planetary boundary layer temperature and sulfuric acid ranges. An empirical algorithm was derived to correlate the nucleation rate with RA, RH, and temperature together. Collision-limited condensation of free-sulfuric acid molecules fails to predict the observed growth rate in the sub-3 nm size range, as well as its dependence on temperature and RH. This suggests that evaporation, sulfuric acid hydration, and possible involvement of other ternary molecules should be considered for the sub-3 nm particle growth.

  17. Growth and development rates have different thermal responses.

    Science.gov (United States)

    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.

  18. Density-dependent growth in invasive Lionfish (Pterois volitans).

    Science.gov (United States)

    Benkwitt, Cassandra E

    2013-01-01

    Direct demographic density dependence is necessary for population regulation and is a central concept in ecology, yet has not been studied in many invasive species, including any invasive marine fish. The red lionfish (Pterois volitans) is an invasive predatory marine fish that is undergoing exponential population growth throughout the tropical western Atlantic. Invasive lionfish threaten coral-reef ecosystems, but there is currently no evidence of any natural population control. Therefore, a manipulative field experiment was conducted to test for density dependence in lionfish. Juvenile lionfish densities were adjusted on small reefs and several demographic rates (growth, recruitment, immigration, and loss) were measured throughout an 8-week period. Invasive lionfish exhibited direct density dependence in individual growth rates, as lionfish grew slower at higher densities throughout the study. Individual growth in length declined linearly with increasing lionfish density, while growth in mass declined exponentially with increasing density. There was no evidence, however, for density dependence in recruitment, immigration, or loss (mortality plus emigration) of invasive lionfish. The observed density-dependent growth rates may have implications for which native species are susceptible to lionfish predation, as the size and type of prey that lionfish consume is directly related to their body size. The absence of density-dependent loss, however, contrasts with many native coral-reef fish species and suggests that for the foreseeable future manual removals may be the only effective local control of this invasion.

  19. Density-dependent growth in invasive Lionfish (Pterois volitans.

    Directory of Open Access Journals (Sweden)

    Cassandra E Benkwitt

    Full Text Available Direct demographic density dependence is necessary for population regulation and is a central concept in ecology, yet has not been studied in many invasive species, including any invasive marine fish. The red lionfish (Pterois volitans is an invasive predatory marine fish that is undergoing exponential population growth throughout the tropical western Atlantic. Invasive lionfish threaten coral-reef ecosystems, but there is currently no evidence of any natural population control. Therefore, a manipulative field experiment was conducted to test for density dependence in lionfish. Juvenile lionfish densities were adjusted on small reefs and several demographic rates (growth, recruitment, immigration, and loss were measured throughout an 8-week period. Invasive lionfish exhibited direct density dependence in individual growth rates, as lionfish grew slower at higher densities throughout the study. Individual growth in length declined linearly with increasing lionfish density, while growth in mass declined exponentially with increasing density. There was no evidence, however, for density dependence in recruitment, immigration, or loss (mortality plus emigration of invasive lionfish. The observed density-dependent growth rates may have implications for which native species are susceptible to lionfish predation, as the size and type of prey that lionfish consume is directly related to their body size. The absence of density-dependent loss, however, contrasts with many native coral-reef fish species and suggests that for the foreseeable future manual removals may be the only effective local control of this invasion.

  20. Dependence of electron beam instability growth rates on the beam-plasma system parameters

    International Nuclear Information System (INIS)

    Strangeway, R.J.

    1982-01-01

    Electron beam instabilites are studied by using a simple model for an electron beam streaming through a cold plasma, the beam being of finite width perpendicular to the ambient magnetic field. Through considerations of finite geometry and the coldness of the beam and background plasma, an instability similar to the two stream instability is assumed to be the means for wave growth in the system. Having found the maximum growth rate for one set of beam-plasma system parameters, this maximum growth rate is traced as these parameters are varied. The parameters that describe the system are the beam velocity (v/sub b/), electron gyrofrequency to ambient electron plasma frequency ratio (Ω/sub e//ω/sub p/e), the beam to background number density ratio (n/sub b//n/sub a/), and the beam width (a). When Ω/sub e//ω/sub p/e>1, a mode with Ω/sub e/<ω<ω/sub u/hr is found to be unstable, where Ω is the wave frequency and ω/sub u/hr is the upper hybrid resonance frequency. For low values of n/sub b//n/sub a/ and Ω/sub e/<ω/sub p/e, this mode is still present with ω/sub p/e<ω<ω/sub u/hr. If the beam density is large, n/sub b//n/sub a/approx. =1, the instability occures for frequencies just above the electron gyrofrequency. This mode may well be that observed in laboratory plasma before the system undergoes the beam-plasma discharge. There is another instability present, which occurs for ωapprox. =ω/sub p/e. The growth rates for this mode, which are generally larger than those found for the ωapprox. =ωuhr mode, are only weakly dependent on Ω/sub d//ω/sub p/e. That this mode is not always observed in the laboratory implies that some factors not considered in the present theory suppress this mode, specifically, finite beam length

  1. Host factor I, Hfq, binds to Escherichia coli ompA mRNA in a growth rate-dependent fashion and regulates its stability

    DEFF Research Database (Denmark)

    Vytvytska, O; Jakobsen, J S; Balcunaite, G

    1998-01-01

    RNA. In hfq mutant cells with a deficient Hfq gene product, the RNA-binding activity is missing, and analysis of the ompA mRNA showed that the growth-rate dependence of degradation is lost. Furthermore, the half-life of the ompA mRNA is prolonged in the mutant cells, irrespective of growth rate. Hfq has...

  2. Protein thermodynamics can be predicted directly from biological growth rates.

    Directory of Open Access Journals (Sweden)

    Ross Corkrey

    Full Text Available 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.

  3. Division-Based, Growth Rate Diversity in Bacteria

    Directory of Open Access Journals (Sweden)

    Ghislain Y. Gangwe Nana

    2018-05-01

    Full Text Available To investigate the nature and origins of growth rate diversity in bacteria, we grew Escherichia coli and Bacillus subtilis in liquid minimal media and, after different periods of 15N-labeling, analyzed and imaged isotope distributions in individual cells with Secondary Ion Mass Spectrometry. We find a striking inter- and intra-cellular diversity, even in steady state growth. This is consistent with the strand-dependent, hyperstructure-based hypothesis that a major function of the cell cycle is to generate coherent, growth rate diversity via the semi-conservative pattern of inheritance of strands of DNA and associated macromolecular assemblies. We also propose quantitative, general, measures of growth rate diversity for studies of cell physiology that include antibiotic resistance.

  4. Dinosaur Metabolism and the Allometry of Maximum Growth Rate.

    Science.gov (United States)

    Myhrvold, Nathan P

    2016-01-01

    The allometry of maximum somatic growth rate has been used in prior studies to classify the metabolic state of both extant vertebrates and dinosaurs. The most recent such studies are reviewed, and their data is reanalyzed. The results of allometric regressions on growth rate are shown to depend on the choice of independent variable; the typical choice used in prior studies introduces a geometric shear transformation that exaggerates the statistical power of the regressions. The maximum growth rates of extant groups are found to have a great deal of overlap, including between groups with endothermic and ectothermic metabolism. Dinosaur growth rates show similar overlap, matching the rates found for mammals, reptiles and fish. The allometric scaling of growth rate with mass is found to have curvature (on a log-log scale) for many groups, contradicting the prevailing view that growth rate allometry follows a simple power law. Reanalysis shows that no correlation between growth rate and basal metabolic rate (BMR) has been demonstrated. These findings drive a conclusion that growth rate allometry studies to date cannot be used to determine dinosaur metabolism as has been previously argued.

  5. Dinosaur Metabolism and the Allometry of Maximum Growth Rate

    Science.gov (United States)

    Myhrvold, Nathan P.

    2016-01-01

    The allometry of maximum somatic growth rate has been used in prior studies to classify the metabolic state of both extant vertebrates and dinosaurs. The most recent such studies are reviewed, and their data is reanalyzed. The results of allometric regressions on growth rate are shown to depend on the choice of independent variable; the typical choice used in prior studies introduces a geometric shear transformation that exaggerates the statistical power of the regressions. The maximum growth rates of extant groups are found to have a great deal of overlap, including between groups with endothermic and ectothermic metabolism. Dinosaur growth rates show similar overlap, matching the rates found for mammals, reptiles and fish. The allometric scaling of growth rate with mass is found to have curvature (on a log-log scale) for many groups, contradicting the prevailing view that growth rate allometry follows a simple power law. Reanalysis shows that no correlation between growth rate and basal metabolic rate (BMR) has been demonstrated. These findings drive a conclusion that growth rate allometry studies to date cannot be used to determine dinosaur metabolism as has been previously argued. PMID:27828977

  6. Emittance growth rates for displaced beams

    International Nuclear Information System (INIS)

    Anderson, O.A.

    1993-05-01

    Emittance growth rates have been previously analyzed for nonuniform beams in linear channels and for initially uniform mismatched beams in nonlinear channels. These studies were for centered beams. Additional emittance growth can arise in cases where the beam is initially displaced. The purpose of this study is to obtain growth rates for displaced beams. This work differs from studies involving random displacement of electrodes. Our analysis assumes instead that the focusing system is perfectly aligned but that the beam is initially displaced with respect to the equilibrium axis. If the focusing force is slightly nonlinear, we find a gradual transfer of the potential energy of beam displacement into kinetic energy associated with emittance growth. We present explicit results for the emittance growth distance as a function of the nonlinearity of the channel. These results will have practical importance for designers of accelerators and transport systems when setting realistic tolerances for initial beam alignment. These tolerances will depend on the nonlinearity and the length of the system

  7. Comments on the Dutton-Puls model: Temperature and yield stress dependences of crack growth rate in zirconium alloys

    International Nuclear Information System (INIS)

    Kim, Young S.

    2010-01-01

    Research highlights: → This study shows first that temperature and yield stress dependences of crack growth rate in zirconium alloys can analytically be understood not by the Dutton-Puls model but by Kim's new DHC model. → It is demonstrated that the driving force for DHC is ΔC, not the stress gradient, which is the core of Kim's DHC model. → The Dutton-Puls model reveals the invalidity of Puls' claim that the crack tip solubility would increase to the cooling solvus. - Abstract: This work was prompted by the publication of Puls's recent papers claiming that the Dutton-Puls model is valid enough to explain the stress and temperature dependences of the crack growth rate (CGR) in zirconium alloys. The first version of the Dutton-Puls model shows that the CGR has positive dependences on the concentration difference ΔC, hydrogen diffusivity D H , and the yield strength, and a negative dependence on the applied stress intensity factor K I , which is one of its critical defects. Thus, the Dutton-Puls model claiming that the temperature dependence of CGR is determined by D H C H turns out to be incorrect. Given that ΔC is independent of the stress, it is evident that the driving force for DHC is ΔC, not the stress gradient, corroborating the validity of Kim's model. Furthermore, the predicted activation energy for CGR in a cold-worked Zr-2.5Nb tube disagrees with the measured one for the Zr-2.5Nb tube, showing that the Dutton-Puls model is too defective to explain the temperature dependence of CGR. It is demonstrated that the revised Dutton-Puls model also cannot explain the yield stress dependence of CGR.

  8. Effect of Time-Dependent Pinning Pressure on Abnormal Grain Growth: Phase Field Simulation

    Science.gov (United States)

    Kim, Jeong Min; Min, Guensik; Shim, Jae-Hyeok; Lee, Kyung Jong

    2018-05-01

    The effect of the time-dependent pinning pressure of precipitates on abnormal grain growth has been investigated by multiphase field simulation with a simple precipitation model. The application of constant pinning pressure is problematic because it always induces abnormal grain growth or no grain growth, which is not reasonable considering the real situation. To produce time-dependent pinning pressure, both precipitation kinetics and precipitate coarsening kinetics have been considered with two rates: slow and fast. The results show that abnormal grain growth is suppressed at the slow precipitation rate. At the slow precipitation rate, the overall grain growth caused by the low pinning pressure in the early stage indeed plays a role in preventing abnormal grain growth by reducing the mobility advantage of abnormal grains. In addition, the fast precipitate coarsening rate tends to more quickly transform abnormal grain growth into normal grain growth by inducing the active growth of grains adjacent to the abnormal grains in the early stage. Therefore, the present study demonstrates that the time dependence of the pinning pressure of precipitates is a critical factor that determines the grain growth mode.

  9. Dinosaur Metabolism and the Allometry of Maximum Growth Rate

    OpenAIRE

    Myhrvold, Nathan P.

    2016-01-01

    The allometry of maximum somatic growth rate has been used in prior studies to classify the metabolic state of both extant vertebrates and dinosaurs. The most recent such studies are reviewed, and their data is reanalyzed. The results of allometric regressions on growth rate are shown to depend on the choice of independent variable; the typical choice used in prior studies introduces a geometric shear transformation that exaggerates the statistical power of the regressions. The maximum growth...

  10. Composition–dependent growth dynamics of selectively grown InGaAs nanowires

    International Nuclear Information System (INIS)

    Kohashi, Y; Hara, S; Motohisa, J

    2014-01-01

    We grew gallium-rich (x > 0.50) and indium-rich (x < 0.50) In 1 − x Ga x As nanowires by catalyst–free selective-area metal–organic vapor-phase epitaxy (SA-MOVPE), and compared their growth dynamics dependence on V/III ratio. It was found that the growth dynamics of In 1 − x Ga x As nanowires is clearly dependent on the alloy composition x. Specifically, for gallium–rich nanowire growth, the axial growth rate of nanowires initially increased with decreasing V/III ratio, and then started to decrease when the V/III ratio continued to decrease below a critical value. On the other hand, axial growth rate of indium-rich nanowires monotonically decreased with decreasing V/III ratio. In addition, the alloy composition was strongly dependent on the V/III ratio for gallium-rich nanowire growth, while it was relatively independent of the V/III ratio for indium-rich nanowire growth. We discuss the origin of dissimilarity in the growth dynamics dependence on V/III ratio between gallium-rich and indium-rich InGaAs nanowire growth, and conclude that it is due to the inherent dissimilarity between GaAs and InAs. Our finding provides important guidelines for achieving precise control of the diameter, height, and alloy composition of nanowires suitable for future nanowire-based electronics. (papers)

  11. Characterization of dependencies between growth and division in budding yeast.

    Science.gov (United States)

    Mayhew, Michael B; Iversen, Edwin S; Hartemink, Alexander J

    2017-02-01

    Cell growth and division are processes vital to the proliferation and development of life. Coordination between these two processes has been recognized for decades in a variety of organisms. In the budding yeast Saccharomyces cerevisiae , this coordination or 'size control' appears as an inverse correlation between cell size and the rate of cell-cycle progression, routinely observed in G 1 prior to cell division commitment. Beyond this point, cells are presumed to complete S/G 2 /M at similar rates and in a size-independent manner. As such, studies of dependence between growth and division have focused on G 1 Moreover, in unicellular organisms, coordination between growth and division has commonly been analysed within the cycle of a single cell without accounting for correlations in growth and division characteristics between cycles of related cells. In a comprehensive analysis of three published time-lapse microscopy datasets, we analyse both intra- and inter-cycle dependencies between growth and division, revisiting assumptions about the coordination between these two processes. Interestingly, we find evidence (i) that S/G 2 /M durations are systematically longer in daughters than in mothers, (ii) of dependencies between S/G 2 /M and size at budding that echo the classical G 1 dependencies, and (iii) in contrast with recent bacterial studies, of negative dependencies between size at birth and size accumulated during the cell cycle. In addition, we develop a novel hierarchical model to uncover inter-cycle dependencies, and we find evidence for such dependencies in cells growing in sugar-poor environments. Our analysis highlights the need for experimentalists and modellers to account for new sources of cell-to-cell variation in growth and division, and our model provides a formal statistical framework for the continued study of dependencies between biological processes. © 2017 The Author(s).

  12. The dependence of the growth rate and meat content of young boars on semen parameters and conception rate.

    Science.gov (United States)

    Knecht, D; Jankowska-Mąkosa, A; Duziński, K

    2017-05-01

    Boars have a decisive impact on the progress in pig production, however, there is no recent information about the optimal growth parameters during the rearing period for modern breed later used in artificial insemination (AI) stations. Therefore, the objective of the research was to conduct semen parameter and conception rate analyses on the basis of growth rate and meat content assessments made during the rearing of AI boars of different genotypes. The study was carried out between 2010 and 2014 and included 184 boars in five breed combinations: 46 Polish Large White, 50 Polish Landrace, 27 Pietrain, 36 Duroc×Pietrain and 25 Hampshire×Pietrain. Boars were qualified by daily gains and meat content assessment (between 170 and 210 days of life). A total number of 38 272 ejaculates were examined (semen volume (ml), spermatozoa concentration (×106 ml-1), total number of spermatozoa (×109) and number of insemination doses from one ejaculate (n)). The fertility was determined by the conception rate (%). Semen volume, spermatozoa concentration and conception rate (PMeat content affected semen volume, number of insemination doses and conception rate (Pmeat content helps AI stations to increase the efficiency and economic profitability, and the number of insemination doses to increase by up to 300 doses/boar within a year. The analyses of growth parameters may help increase the efficiency and economic viability of AI stations.

  13. Population and prehistory I: Food-dependent population growth in constant environments.

    Science.gov (United States)

    Lee, Charlotte T; Tuljapurkar, Shripad

    2008-06-01

    We present a demographic model that describes the feedbacks between food supply, human mortality and fertility rates, and labor availability in expanding populations, where arable land area is not limiting. This model provides a quantitative framework to describe how environment, technology, and culture interact to influence the fates of preindustrial agricultural populations. We present equilibrium conditions and derive approximations for the equilibrium population growth rate, food availability, and other food-dependent measures of population well-being. We examine how the approximations respond to environmental changes and to human choices, and find that the impact of environmental quality depends upon whether it manifests through agricultural yield or maximum (food-independent) survival rates. Human choices can complement or offset environmental effects: greater labor investments increase both population growth and well-being, and therefore can counteract lower agricultural yield, while fertility control decreases the growth rate but can increase or decrease well-being. Finally we establish equilibrium stability criteria, and argue that the potential for loss of local stability at low population growth rates could have important consequences for populations that suffer significant environmental or demographic shocks.

  14. Metabolic enzyme cost explains variable trade-offs between microbial growth rate and yield.

    Directory of Open Access Journals (Sweden)

    Meike T Wortel

    2018-02-01

    Full Text Available Microbes may maximize the number of daughter cells per time or per amount of nutrients consumed. These two strategies correspond, respectively, to the use of enzyme-efficient or substrate-efficient metabolic pathways. In reality, fast growth is often associated with wasteful, yield-inefficient metabolism, and a general thermodynamic trade-off between growth rate and biomass yield has been proposed to explain this. We studied growth rate/yield trade-offs by using a novel modeling framework, Enzyme-Flux Cost Minimization (EFCM and by assuming that the growth rate depends directly on the enzyme investment per rate of biomass production. In a comprehensive mathematical model of core metabolism in E. coli, we screened all elementary flux modes leading to cell synthesis, characterized them by the growth rates and yields they provide, and studied the shape of the resulting rate/yield Pareto front. By varying the model parameters, we found that the rate/yield trade-off is not universal, but depends on metabolic kinetics and environmental conditions. A prominent trade-off emerges under oxygen-limited growth, where yield-inefficient pathways support a 2-to-3 times higher growth rate than yield-efficient pathways. EFCM can be widely used to predict optimal metabolic states and growth rates under varying nutrient levels, perturbations of enzyme parameters, and single or multiple gene knockouts.

  15. Time-dependent crack growth in Alloy 718: An interim assessment

    International Nuclear Information System (INIS)

    James, L.A.

    1982-08-01

    Previous results on the time-dependent nature of fatigue-crack propagation (FCP) in Alloy 718 at elevated temperatures were reviewed. Additional experiments were conducted to further define certain aspects of the time-dependent crack growth behavior. it was found that loading waveform influenced FCP behavior, with tensile hold-times producing higher growth rates than continuous cycling at the same frequency. Crack growth rates under hold-time conditions tended to increase with decreasing grain size. Finally, experiments were conducted which tended to cast some doubt upon the ability of linear-elastic fracture mechanics (LEFM) techniques to characterize cracking behavior in this alloy under hold-time conditions. However, since a superior correlating parameter has not yet been proven, it is suggested that LEFM methods be used in the interim with appropriate safety factors to account for the potential errors. 34 refs., 10 figs., 4 tabs

  16. Time-dependent crack growth and fracture in concrete

    International Nuclear Information System (INIS)

    Zhou Fan Ping.

    1992-02-01

    The objectives of this thesis are to study time-dependent fracture behaviour in concrete. The thesis consists of an experimental study, costitutive modelling and numerical analysis. The experimental study was undertaken to investigate the influences of time on material properties for the fracture process zone and on crack growth and fracture in plain concrete structures. The experiments include tensile relaxation tests, bending tests on notched beams to determine fracture energy at varying deflection rates, and sustained bending and compact tensile tests. From the tensile relaxation tests, the envelope of the σ-w relation does not seem to be influenced by holding periods, though some local detrimental effect does occur. Fracture energy seems to decrease as rates become slower. In the sustained loading tests, deformation (deflection or CMOD) growth curves display three stages, as usually observed in a creep rupture test. The secondary stage dominates the whole failure lifetime, and the secondary deformation rate appears to have good correlation with the failure lifetime. A crack model for time-dependent fracture is proposed, by applying the idea of the Fictitious Crack Model. In this model, a modified Maxwell model is introduced for the fracture process zone incorporated with the static σ-w curve as a failure criterion, based on the observation of the tensile relaxation tests. The time-dependent σ-w curve is expressed in an incremental law. The proposed model has been implemented in a finite element program and applied to simulating sustained flexural and compact tensile tests. Numerical analysis includes simulations of crack growth, load-CMOD curves, stress-failure lifetime curves, size effects on failure life etc. The numerical results indicate that the model seems to be able to properly predict the main features of time-dependent fracture behaviour in concrete, as compared with the experimental results. 97 refs

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

    Science.gov (United States)

    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.

  18. [Specific growth rate and the rate of energy metabolism in the ontogenesis of axolotl, Ambystoma mexicanum (Amphibia: Ambystomatidae)].

    Science.gov (United States)

    Vladimirova, I G; Kleĭmenov, S Iu; Alekseeva, T A; Radzinskaia, L I

    2003-01-01

    Concordant changes in the rate of energy metabolism and specific growth rate of axolotls have been revealed. Several periods of ontogeny are distinguished, which differ in the ratio of energy metabolism to body weight and, therefore, are described by different allometric equations. It is suggested that the specific growth rate of an animal determines the type of dependence of energy metabolism on body weight.

  19. Adaptive Significance of Quorum Sensing-Dependent Regulation of Rhamnolipids by Integration of Growth Rate in Burkholderia glumae: A Trade-Off between Survival and Efficiency.

    Science.gov (United States)

    Nickzad, Arvin; Déziel, Eric

    2016-01-01

    Quorum sensing (QS) is a cell density-dependent mechanism which enables a population of bacteria to coordinate cooperative behaviors in response to the accumulation of self-produced autoinducer signals in their local environment. An emerging framework is that the adaptive significance of QS in the regulation of production of costly extracellular metabolites ("public goods") is to maintain the homeostasis of cooperation. We investigated this model using the phytopathogenic bacterium Burkholderia glumae, which we have previously demonstrated uses QS to regulate the production of rhamnolipids, extracellular surface-active glycolipids promoting the social behavior called "swarming motility." Using mass spectrometric quantification and chromosomal lux-based gene expression, we made the unexpected finding that when unrestricted nutrient resources are provided, production of rhamnolipids is carried out completely independently of QS regulation. This is a unique observation among known QS-controlled factors in bacteria. On the other hand, under nutrient-limited conditions, QS then becomes the main regulating mechanism, significantly enhancing the specific rhamnolipids yield. Accordingly, decreasing nutrient concentrations amplifies rhamnolipid biosynthesis gene expression, revealing a system where QS-dependent regulation is specifically triggered by the growth rate of the population, rather than by its cell density. Furthermore, a gradual increase in QS signal specific concentration upon decrease of specific growth rate suggests a reduction in quorum threshold, which reflects an increase in cellular demand for production of QS-dependent target gene product at low density populations. Integration of growth rate with QS as a decision-making mechanism for biosynthesis of costly metabolites, such as rhamnolipids, could serve to assess the demand and timing for expanding the carrying capacity of a population through spatial expansion mechanisms, such as swarming motility, thus

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

    Science.gov (United States)

    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.

  1. Growth dependence of conjugation explains limited plasmid invasion in biofilms: an individual‐based modelling study

    DEFF Research Database (Denmark)

    Merkey, Brian; Lardon, Laurent; Seoane, Jose Miguel

    2011-01-01

    Plasmid invasion in biofilms is often surprisingly limited in spite of the close contact of cells in a biofilm. We hypothesized that this poor plasmid spread into deeper biofilm layers is caused by a dependence of conjugation on the growth rate (relative to the maximum growth rate) of the donor......, we find that invasion of a resident biofilm is indeed limited when plasmid transfer depends on growth, but not so in the absence of growth dependence. Using sensitivity analysis we also find that parameters related to timing (i.e. a lag before the transconjugant can transfer, transfer proficiency...... and scan speed) and spatial reach (EPS yield, conjugal pilus length) are more important for successful plasmid invasion than the recipients' growth rate or the probability of segregational loss. While this study identifies one factor that can limit plasmid invasion in biofilms, the new individual...

  2. A simple equation for describing the temperature dependent growth of free-floating macrophytes

    NARCIS (Netherlands)

    Heide, van Tj.; Roijackers, R.M.M.; Nes, van E.H.; Peeters, E.T.H.M.

    2006-01-01

    Temperature is one of the most important factors determining growth rates of free-floating macrophytes in the field. To analyse and predict temperature dependent growth rates of these pleustophytes, modelling may play an important role. Several equations have been published for describing

  3. Influence of Crucible Support Rod on the Growth Rate and Temperature Gradient in a Bridgman Growth of Tin Crystal

    OpenAIRE

    IMASHIMIZU, Yuji; MIURA, Koji; KAMATA, Masaki; WATANABE, Jiro

    2003-01-01

    Bridgman growth of tincrystal was carried out in a graphite crucible that was fixed on a quartz support rod or a copper one. The growth rate and axial temperature distribution were examined by recording the temperature variation with time at each of four prescribed positions in the solid-liquidsystem during solidification, l) Actual growth rate of crystal increased with progress of solidification while the furnace elevated at a constant rate, but the tendency was different depending on the ty...

  4. Orbit width scaling of TAE instability growth rate

    International Nuclear Information System (INIS)

    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

  5. Orbit width scaling of TAE instability growth rate

    International Nuclear Information System (INIS)

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

    1995-01-01

    The growth rate of toroidal Alfven eigenmodes (TAEs) 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 that 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. (author). 16 refs, 8 figs

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

    International Nuclear Information System (INIS)

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

    2010-01-01

    Research highlights: → CK2 subunits are nuclear both in glucose and in ethanol growing yeast cells. → CK2 activity is modulated in S. cerevisiae. → CK2 activity is higher in conditions supporting higher growth rates. → V max is higher in faster growing cells, while K 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 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.

  7. Temperature-dependent evolution of chemisorbed digermane in Ge thin film growth

    International Nuclear Information System (INIS)

    Eres, D.; Sharp, J.W.

    1992-01-01

    The formation and evolution of chemisorbed digermane layers in context with germanium thin film growth was investigated by time- resolved surface reflectometry. Modulation of the source gas supply made possible the separation and independent study of the temperature dependence of the adsorption and desorption processes. The regeneration of active sites by molecular hydrogen desorption was identified as the rate-limiting step at low substrate temperatures. A dynamic method of thin film growth was demonstrated by repetitively replenishing the active film growth sites regenerated between two successive source gas pulses. The film growth rate was shown to be related to the substrate temperature and the delay time between successive source gas pulses

  8. Investment in secreted enzymes during nutrient-limited growth is utility dependent.

    Science.gov (United States)

    Cezairliyan, Brent; Ausubel, Frederick M

    2017-09-12

    Pathogenic bacteria secrete toxins and degradative enzymes that facilitate their growth by liberating nutrients from the environment. To understand bacterial growth under nutrient-limited conditions, we studied resource allocation between cellular and secreted components by the pathogenic bacterium Pseudomonas aeruginosa during growth on a protein substrate that requires extracellular digestion by secreted proteases. We identified a quantitative relationship between the rate of increase of cellular biomass under nutrient-limiting growth conditions and the rate of increase in investment in secreted proteases. Production of secreted proteases is stimulated by secreted signals that convey information about the utility of secreted proteins during nutrient-limited growth. Growth modeling using this relationship recapitulated the observed kinetics of bacterial growth on a protein substrate. The proposed regulatory strategy suggests a rationale for quorum-sensing-dependent stimulation of the production of secreted enzymes whereby investment in secreted enzymes occurs in proportion to the utility they confer. Our model provides a framework that can be applied toward understanding bacterial growth in many environments where growth rate is limited by the availability of nutrients.

  9. New developments on size-dependent growth applied to the crystallization of sucrose

    Science.gov (United States)

    Martins, P. M.; Rocha, F.

    2007-12-01

    The effect of crystal size on the growth rate of sucrose (C 12H 22O 11) at 40 °C is investigated from a theoretical and an experimental point of view. Based on new perspectives resulting from the recently introduced spiral nucleation model [P.M. Martins, F. Rocha, Surf. Sci. 601 (2007) 3400], crystal growth rates are expressed in terms of mass deposition per time and crystal volume units. This alternative definition is demonstrated to be size-independent over the considered supersaturation range. The conventional overall growth rate expressed per surface area units is found to be linearly dependent on crystal size. The advantages of the "volumetric" growth rate concept are discussed. Sucrose dissolution rates were measured under reciprocal conditions of the growth experiments in order to investigate the two-way effect of crystal size on mass transfer rates and on the integration kinetics. Both effects are adequately described by combining a well-established diffusion-integration model and the spiral nucleation mechanism.

  10. Scan-rate and vacuum pressure dependence of the nucleation and growth dynamics in a spin-crossover single crystal: the role of latent heat.

    Science.gov (United States)

    Ridier, Karl; Rat, Sylvain; Salmon, Lionel; Nicolazzi, William; Molnár, Gábor; Bousseksou, Azzedine

    2018-04-04

    Using optical microscopy we studied the vacuum pressure dependence (0.1-1000 mbar) of the nucleation and growth dynamics of the thermally induced first-order spin transition in a single crystal of the spin-crossover compound [Fe(HB(tz)3)2] (tz = 1,2,4-triazol-1-yl). A crossover between a quasi-static hysteresis regime and a temperature-scan-rate-dependent kinetic regime is evidenced around 5 mbar due to the change of the heat exchange coupling between the crystal and its external environment. Remarkably, the absorption/dissipation rate of latent heat was identified as the key factor limiting the switching speed of the crystal.

  11. Growth pattern and growth dependent mortality of larval and pelagic juvenile North Sea cod Gadus morhua

    DEFF Research Database (Denmark)

    Nielsen, Rune; Munk, Peter

    2004-01-01

    and May 2001), and larval/juvenile growth history from each of the sampling sequences was outlined. Growth rate was estimated by fitting a Laird-Gompertz equation to lengths-at-age, and we found the mean specific growth rate in length at age 20 d was 3.2% d(-1), declining to 1.9% d(-1) at an age of 90 d....... Otolith radius and larval standard length were highly correlated, and otolith growth was used as a measure of larval somatic growth. The larvae were divided into 3 groups dependent on their hatch-date, and for each hatch group, the same period of past growth was compared between fish sampled in April...... and May. A 2-way repeated-measurement ANOVA revealed a significant higher past growth of fish sampled in May in 2 of the 3 hatch-groups, implying a higher mortality of the slow growing larvae. Additionally, otolith size at age differed significantly between the April and May sampling of the oldest larvae...

  12. A quantitative theory of solid tumor growth, metabolic rate and vascularization.

    Directory of Open Access Journals (Sweden)

    Alexander B Herman

    Full Text Available The relationships between cellular, structural and dynamical properties of tumors have traditionally been studied separately. Here, we construct a quantitative, predictive theory of solid tumor growth, metabolic rate, vascularization and necrosis that integrates the relationships between these properties. To accomplish this, we develop a comprehensive theory that describes the interface and integration of the tumor vascular network and resource supply with the cardiovascular system of the host. Our theory enables a quantitative understanding of how cells, tissues, and vascular networks act together across multiple scales by building on recent theoretical advances in modeling both healthy vasculature and the detailed processes of angiogenesis and tumor growth. The theory explicitly relates tumor vascularization and growth to metabolic rate, and yields extensive predictions for tumor properties, including growth rates, metabolic rates, degree of necrosis, blood flow rates and vessel sizes. Besides these quantitative predictions, we explain how growth rates depend on capillary density and metabolic rate, and why similar tumors grow slower and occur less frequently in larger animals, shedding light on Peto's paradox. Various implications for potential therapeutic strategies and further research are discussed.

  13. Growth rate of late passage sarcoma cells is independent of epigenetic events but dependent on the amount of chromosomal aberrations

    International Nuclear Information System (INIS)

    Becerikli, Mustafa; Jacobsen, Frank; Rittig, Andrea; Köhne, Wiebke; Nambiar, Sandeep; Mirmohammadsadegh, Alireza; Stricker, Ingo; Tannapfel, Andrea; Wieczorek, Stefan; Epplen, Joerg Thomas; Tilkorn, Daniel; Steinstraesser, Lars

    2013-01-01

    Soft tissue sarcomas (STS) are characterized by co-participation of several epigenetic and genetic events during tumorigenesis. Having bypassed cellular senescence barriers during oncogenic transformation, the factors further affecting growth rate of STS cells remain poorly understood. Therefore, we investigated the role of gene silencing (DNA promoter methylation of LINE-1, PTEN), genetic aberrations (karyotype, KRAS and BRAF mutations) as well as their contribution to the proliferation rate and migratory potential that underlies “initial” and “final” passage sarcoma cells. Three different cell lines were used, SW982 (synovial sarcoma), U2197 (malignant fibrous histiocytoma (MFH)) and HT1080 (fibrosarcoma). Increased proliferative potential of final passage STS cells was not associated with significant differences in methylation (LINE-1, PTEN) and mutation status (KRAS, BRAF), but it was dependent on the amount of chromosomal aberrations. Collectively, our data demonstrate that these fairly differentiated/advanced cancer cell lines have still the potential to gain an additional spontaneous growth benefit without external influences and that maintenance of increased proliferative potential towards longevity of STS cells (having crossed senescence barriers) may be independent of overt epigenetic alterations. -- Highlights: Increased proliferative potential of late passage STS cells was: • Not associated with epigenetic changes (methylation changes at LINE-1, PTEN). • Not associated with mutation status of KRAS, BRAF. • Dependent on presence/absence of chromosomal aberrations

  14. Temperature-dependent respiration-growth relations in ancestral maize cultivars

    Science.gov (United States)

    Bruce N. Smith; Jillian L. Walker; Rebekka L. Stone; Angela R. Jones; Lee D. Hansen

    2001-01-01

    Shoots from 4- to 6-day old seedlings of seven ancestral or old cultivars of Zea mays L. were placed in a calorimeter. Dark metabolic heat rate (q) and CO2 production rate (RCO2) were measured at nine temperatures (5, 10, 15, 20, 25, 30, 35, 40, and 45 °C). Temperature dependencies of q and RCO2 were used to model response of both growth and substrate carbon conversion...

  15. Anomalous dependence of population growth on the birth rate in the plant-herbivore system

    International Nuclear Information System (INIS)

    Cui, Xue M.; Han, Seung K.; Chung, Jean S.

    2010-01-01

    We performed a simulation of the two-species plant-herbivore system by using the agent-based NetLogo program and constructed a dynamic model of populations consistent with the simulation results. The dynamic model is a three-dimensional system including the mean energy of the herbivore in addition to two variables denoting the populations of plants and herbivores. A steady-state analysis of the dynamic model shows that the dependence of the herbivore population on the birth and the death rates observed from the agent model is consistent with the prediction of the dynamic model. Especially, the anomalous dependence of the herbivore population on the birth rate, where the population decreases with the birth rate for small death rate, is consistently explained by a phase plane analysis of the dynamic model.

  16. Temperature dependences of growth rates and carrying capacities of marine bacteria depart from metabolic theoretical predictions

    KAUST Repository

    Huete-Stauffer, Tamara Megan

    2015-09-11

    Using the metabolic theory of ecology (MTE) framework, we evaluated over a whole annual cycle the monthly responses to temperature of the growth rates (μ) and carrying capacities (K) of heterotrophic bacterioplankton at a temperate coastal site. We used experimental incubations spanning 6oC with bacterial physiological groups identified by flow cytometry according to membrane integrity (live), nucleic acid content (HNA and LNA) and respiratory activity (CTC+). The temperature dependence of μat the exponential phase of growth was summarized by the activation energy (E), which was variable (-0.52 to 0.72 eV) but followed a seasonal pattern, only reaching the hypothesized value for aerobic heterotrophs of 0.65 eV during the spring bloom for the most active bacterial groups (live, HNA, CTC+). K (i.e. maximum experimental abundance) peaked at 4 × 106 cells mL-1 and generally covaried with μbut, contrary to MTE predictions, it did not decrease consistently with temperature. In the case of live cells, the responses of μand K to temperature were positively correlated and related to seasonal changes in substrate availability, indicating that the responses of bacteria to warming are far from homogeneous and poorly explained by MTE at our site. © FEMS 2015.

  17. Population Growth Rate, Life Expectancy and Pension Program Improvement in China

    OpenAIRE

    Yang, Zaigui

    2008-01-01

    Applying an overlapping-generations model with lifetime uncertainty, we examine in this paper China’s partially funded public pension system. The findings show that the individual contribution rate does not affect the capital-labor ratio but the firm contribution rate does. The optimal firm contribution rate depends on the capital share of income, social discount factor, survival probability, and population growth rate. The simulation results indicate that the optimal firm contribution rate r...

  18. 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

    Science.gov (United States)

    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

  19. 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.

    Science.gov (United States)

    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

  20. 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.

    Directory of Open Access Journals (Sweden)

    Jan Werner

    Full Text Available 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

  1. Thresholds of time dependent intergranular crack growth in a nickel disc alloy Alloy 720Li

    Directory of Open Access Journals (Sweden)

    Li Hangyue

    2014-01-01

    Full Text Available At high temperatures in air, introducing a dwell period at the peak stress of fatigue cycles promotes time dependent intergranular crack growth which can increase crack growth rates by upto a few orders of magnitude from the rates of transgranular fatigue crack growth in superalloys. It is expected that time dependent intergranular crack growth in nickel-based superalloys may not occur below a critical mechanical driving force, ΔKth−IG, analogous to a fatigue threshold (ΔKth and a critical temperature, Tth. In this study, dwell fatigue crack growth tests have been carefully designed and conducted on Alloy 720Li to examine such thresholds. Unlike a fatigue threshold, the threshold stress intensity factor range for intergranular crack growth is observed to be highly sensitive to microstructure, dwell time and test procedure. The near threshold crack growth behaviour is made complex by the interactions between grain boundary oxidation embrittlement and crack tip stress relaxation. In general, lower ΔKth−IG values are associated with finer grain size and/or shorter dwell times. Often a load increasing procedure promotes stress relaxation and tends to lead to higher ΔKth−IG. When there is limited stress relaxation at the crack tip, similar ΔKth−IG values are measured with load increasing and load shedding procedures. They are generally higher than the fatigue threshold (ΔKth despite faster crack growth rates (da/dN in the stable crack growth regime. Time dependent intergranular crack growth cannot be activated below a temperature of 500 ∘C.

  2. Major Changes in Growth Rate and Growth Variability of Beech (Fagus sylvatica L. Related to Soil Alteration and Climate Change in Belgium

    Directory of Open Access Journals (Sweden)

    Nicolas Latte

    2016-08-01

    Full Text Available Global change—particularly climate change, forest management, and atmospheric deposition—has significantly altered forest growing conditions in Europe. The influences of these changes on beech growth (Fagus sylvatica L. were investigated for the past 80 years in Belgium, using non-linear mixed effects models on ring-width chronologies of 149 mature and dominant beech trees (87–186 years old. The effects of the developmental stage (i.e., increasing tree size were filtered out in order to focus on time-dependent growth changes. Beech radial growth was divided into a low-frequency signal (=growth rate, mainly influenced by forest management and atmospheric deposition, and into a high-frequency variability (≈mean sensitivity, mainly influenced by climate change. Between 1930 and 2008, major long-term and time-dependent changes were highlighted. The beech growth rate has decreased by about 38% since the 1950–1960s, and growth variability has increased by about 45% since the 1970–1980s. Our results indicate that (1 before the 1980s, beech growth rate was not predominantly impacted by climate change but rather by soil alteration (i.e., soil compaction and/or nitrogen deposition; and (2 since the 1980s, climate change induced more frequent and intense yearly growth reductions that amplified the growth rate decrease. The highlighted changes were similar in the two ecoregions of Belgium, although more pronounced in the lowlands than in the uplands.

  3. Measurement of fatigue crack growth rate of reactor structural material in air based on DCPD method

    International Nuclear Information System (INIS)

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

    2014-01-01

    The principles and details of direct current potential drop (DCPD) in monitoring the crack growth of reactor structural materials was introduced in this paper. Based on this method, the fatigue crack growth rate (CGR) of typical structural materials in nuclear power systems was measured. The effects of applied load, load ratio and loading frequency on the fatigue crack growth rate of reactor structural materials were discussed. The result shows that the fatigue crack growth rate of reactor structural materials depends on the hardness of materials, and the harder the material is, the higher the rate of crack growth is. (authors)

  4. Effect of diffusion from a lateral surface on the rate of GaN nanowire growth

    International Nuclear Information System (INIS)

    Sibirev, N. V.; Tchernycheva, M.; Cirlin, G. E.; Patriarche, G.; Harmand, J. C.; Dubrovskii, V. G.

    2012-01-01

    The kinetics of the growth of GaN crystalline nanowires on a Si (111) surface with no catalyst is studied experimentally and theoretically. Noncatalytic GaN nanowires were grown by molecular-beam epitaxy with AlN inserts, which makes it possible to determine the rate of the vertical growth of nanowires. A model for the formation of GaN nanowires is developed, and an expression for their rate of growth is derived. It is shown that, in the general case, the dependence of the rate of growth on the nanowire diameter has a minimum. The diameter corresponding to the experimentally observed minimum of the rate of growth steadily increases with increasing diffusion flux from the lateral surface.

  5. Radiosensitivity of the swiss-rap mouse as a function of its growth rate

    International Nuclear Information System (INIS)

    Legeay, G.; Glas, J.F.

    1969-01-01

    The results of an exhaustive study of the age dependence of the radiosensitivity of female Swiss-Rap mice are given. A close relationship of radiosensitivity versus age could not be brought out, whereas the weekly growth rate could be accurately related to radiosensitivity. Thus, the latter should be studied when a strain is to be used for biological experiments, as the rates of growth are different with the strains. (author) [fr

  6. How to determine control of growth rate in a chemostat. Using metabolic control analysis to resolve the paradox

    DEFF Research Database (Denmark)

    Snoep, Jacky L.; Jensen, Peter Ruhdal; Groeneveld, Philip

    1994-01-01

    how, paradoxically, one can determine control of growth rate, of growth yield and of other fluxes in a chemostat. We develop metabolic control analysis for the chemostat. this analysis does not depend on the particular way in which specific growth rate varies with the concentration of the growth...

  7. The effect of rumen content transfer on rate of bacteria and protozoa growth

    International Nuclear Information System (INIS)

    Suharyono; M Winugroho; Y Widiati; S Marijati

    1998-01-01

    The aims the experiment wants to know the benefit of rate of microbial protein in rumen content and to complete the information that isolates is useful for ruminant animals feed. The result indicated that buffaloes from East Nusa Tenggara is the best when they are used as donor rumen transfer making isolate. When rumen of ongole cattle generation was mixed in rumen content of buffaloes from East Nusa Tenggara and incubated 48 h, the rate of bacteria cell growth is better than rate of protozoa cell growth comparing to the other animals. The values are 30.99 mg/h/100 ml and 24.92 mg.h/100 ml respectively. The results of isolate selection in 48 h incubation indicated that treatment F is the best. The results rates of bacteria cell growth and rate of protozoa's cell growth are 26.96 mg/h/100 ml and 2.53 mg/h/100 respectively. The result of in vitro study indicated that pH and ammonia concentration support the rate of bacteria cell growth and do not cause the toxicity of microbes and animal . The rate of bacteria cell growth on D treatment is significant to A,B, and C treatments. The values are 21.44 mg/h/100 ml. 7.99; 13.13; and 13.38 mg/h/100 ml respectively. The result rates of protozoa's cell growth tends lower than rates of bacteria cell. The overall conclusion is a lower or a higher rate of microorganism cell growth depends on the environment condition. (author)

  8. Trophic Relationships between the Parasitic Plant Species Phelipanche ramosa (L.) and Different Hosts Depending on Host Phenological Stage and Host Growth Rate

    Science.gov (United States)

    Moreau, Delphine; Gibot-Leclerc, Stéphanie; Girardin, Annette; Pointurier, Olivia; Reibel, Carole; Strbik, Florence; Fernández-Aparicio, Mónica; Colbach, Nathalie

    2016-01-01

    Phelipanche ramosa (L.) Pomel (branched broomrape) is a holoparasitic plant that reproduces on crops and also on weeds, which contributes to increase the parasite seed bank in fields. This parasite extracts all its nutrients at the host’s expense so that host–parasite trophic relationships are crucial to determine host and parasite growth. This study quantified the intensity with which P. ramosa draws assimilates from its host and analyzed whether it varied with host species, host phenological stage and host growth rate. A greenhouse experiment was conducted on three host species: the crop species Brassica napus (L.) (oilseed rape) and two weed species, Capsella bursa-pastoris (L.) Medik. and Geranium dissectum (L.). Plants were grown with or without P. ramosa and under three light levels to modulate host growth rate. The proportion of host biomass loss due to parasitism by P. ramosa differed between host species (at host fructification, biomass loss ranged from 34 to 84%). B. napus and C. bursa-pastoris displayed a similar response to P. ramosa, probably because they belong to the same botanical family. The sensitivity to P. ramosa in each host species could be related to the precocity of P. ramosa development on them. Host compartments could be ranked as a function of their sensitivity to parasitism, with the reproductive compartment being the most severely affected, followed by stems and roots. The proportion of biomass allocated to leaves was not reduced by parasitism. The proportion of pathosystem biomass allocated to the parasite depended on host species. It generally increased with host stage progression but was constant across light induced-host growth rate, showing that P. ramosa adapts its growth to host biomass production. The rank order of host species in terms of sink strength differed from that in terms of host sensitivity. Finally, for B. napus, the biomass of individual parasite shoots decreased with increasing their number per host plant

  9. Trophic relationships between the parasitic plant species Phelipanche ramosa (L. and different hosts depending on host phenological stage and host growth rate

    Directory of Open Access Journals (Sweden)

    Delphine Moreau

    2016-07-01

    Full Text Available Phelipanche ramosa (L. Pomel (branched broomrape is a holoparasitic plant that reproduces on crops and also on weeds, which contributes to increase the parasite seed bank in fields. This parasite extracts all its nutrients at the host's expense so that host-parasite trophic relationships are crucial to determine host and parasite growth. This study quantified the intensity with which P. ramosa draws assimilates from its host and analyzed whether it varied with host species, host phenological stage and host growth rate. A greenhouse experiment was conducted on three host species: the crop species Brassica napus (L. (oilseed rape and two weed species, Capsella bursa-pastoris (L. Medik. and Geranium dissectum (L.. Plants were grown with or without P. ramosa and under three light levels to modulate host growth rate. The proportion of host biomass loss due to parasitism by P. ramosa differed between host species (at host fructification, biomass loss ranged from 34% to 84%. Brassica napus and C. bursa-pastoris displayed a similar response to P. ramosa, probably because they belong to the same botanical family. The sensitivity to P. ramosa in each host species could be related to the precocity of P. ramosa development on them. Host compartments could be ranked as a function of their sensitivity to parasitism, with the reproductive compartment being the most severely affected, followed by stems and roots. The proportion of biomass allocated to leaves was not reduced by parasitism. The proportion of pathosystem biomass allocated to the parasite depended on host species. It generally increased with host stage progression but was constant across light induced-host growth rate, showing that P. ramosa adapts its growth to host biomass production. The rank order of host species in terms of sink strength differed from that in terms of host sensitivity. Finally, for B. napus, the biomass of individual parasite shoots decreased with increasing their number per

  10. Selective area growth of GaN rod structures by MOVPE: Dependence on growth conditions

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shunfeng; Fuendling, Soenke; Wang, Xue; Erenburg, Milena; Al-Suleiman, Mohamed Aid Mansur; Wei, Jiandong; Wehmann, Hergo-Heinrich; Waag, Andreas [Institut fuer Halbleitertechnik, TU Braunschweig, Hans-Sommer-Strasse 66, 38106 Braunschweig (Germany); Bergbauer, Werner [Institut fuer Halbleitertechnik, TU Braunschweig, Hans-Sommer-Strasse 66, 38106 Braunschweig (Germany); Osram Opto Semiconductors GmbH, Leibnizstr. 4, 93055 Regensburg (Germany); Strassburg, Martin [Osram Opto Semiconductors GmbH, Leibnizstr. 4, 93055 Regensburg (Germany)

    2011-07-15

    Selective area growth of GaN nanorods by metalorganic vapor phase epitaxy is highly demanding for novel applications in nano-optoelectronic and nanophotonics. Recently, we report the successful selective area growth of GaN nanorods in a continuous-flow mode. In this work, as examples, we show the morphology dependence of GaN rods with {mu}m or sub-{mu}m in diameters on growth conditions. Firstly, we found that the nitridation time is critical for the growth, with an optimum from 90 to 180 seconds. This leads to more homogeneous N-polar GaN rods growth. A higher temperature during GaN rod growth tends to increase the aspect ratio of the GaN rods. This is due to the enhanced surface diffusion of growth species. The V/III ratio is also an important parameter for the GaN rod growth. Its increase causes reduction of the aspect ratio of GaN rods, which could be explained by the relatively lower growth rate on (000-1) N-polar top surface than it on {l_brace}1-100{r_brace} m-planes by supplying more NH{sub 3} (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Methods of forecasting crack growth rate under creep conditions

    International Nuclear Information System (INIS)

    Ol'kin, S.I.

    1979-01-01

    Using construction aluminium alloy application possibility of linear mechanics of the destruction for quantitative description of crack development process under creepage conditions is investigated. It is shown, that the grade dependence between the stress intensity coefficient and the crack growth rate takes place only at certain combination of the sample geometry and creepage parameters, and consequently, its applicability in every given case must necessarily be tested experimentally

  12. Calcite growth-rate inhibition by fulvic acid and magnesium ion—Possible influence on biogenic calcite formation

    Science.gov (United States)

    Reddy, Michael M.

    2012-01-01

    Increases in ocean surface water dissolved carbon dioxide (CO2) concentrations retard biocalcification by reducing calcite supersaturation (Ωc). Reduced calcification rates may influence growth-rate dependent magnesium ion (Mg) incorporation into biogenic calcite modifying the use of calcifying organisms as paleoclimate proxies. Fulvic acid (FA) at biocalcification sites may further reduce calcification rates. Calcite growth-rate inhibition by FA and Mg, two common constituents of seawater and soil water involved in the formation of biogenic calcite, was measured separately and in combination under identical, highly reproducible experimental conditions. Calcite growth rates (pH=8.5 and Ωc=4.5) are reduced by FA (0.5 mg/L) to 47% and by Mg (10−4 M) to 38%, compared to control experiments containing no added growth-rate inhibitor. Humic acid (HA) is twice as effective a calcite growth-rate inhibitor as FA. Calcite growth rate in the presence of both FA (0.5 mg/L) and Mg (10−4 M) is reduced to 5% of the control rate. Mg inhibits calcite growth rates by substitution for calcium ion at the growth site. In contrast, FA inhibits calcite growth rates by binding multiple carboxylate groups on the calcite surface. FA and Mg together have an increased affinity for the calcite growth sites reducing calcite growth rates.

  13. Population growth, interest rate, and housing tax in the transitional China

    Science.gov (United States)

    He, Ling-Yun; Wen, Xing-Chun

    2017-03-01

    This paper combines and develops the models in Lastrapes (2002) and Mankiw and Weil (1989), which enables us to analyze the effects of interest rate and population growth shocks on housing price in one integrated framework. Based on this model, we carry out policy simulations to examine whether the housing (stock or flow) tax reduces the housing price fluctuations caused by interest rate or population growth shocks. Simulation results imply that the choice of housing tax tools depends on the kind of shock that housing market faces. In the situation where the housing price volatility is caused by the population growth shock, the flow tax can reduce the volatility of housing price while the stock tax makes no difference to it. If the shock is resulting from the interest rate, the policy maker should not impose any kind of the housing taxes. Furthermore, the effect of one kind of the housing tax can be strengthened by that of the other type of housing tax.

  14. Growth performance and carcass traits in pigs selected for indirect genetic effects on growth rate in two environments

    NARCIS (Netherlands)

    Camerlink, I.; Bolhuis, J.E.; Duijvesteijn, N.; Arendonk, van J.A.M.; Bijma, P.

    2014-01-01

    Production traits such as growth rate may depend on the social interactions between group members. These social interactions might be partly heritable and are referred to as indirect genetic effects (IGE), social-, associative-, or competitive genetic effects. IGE may contribute to heritable

  15. Evolution of space dependent growth in the teleost Astyanax mexicanus.

    Directory of Open Access Journals (Sweden)

    Natalya D Gallo

    Full Text Available The relationship between growth rate and environmental space is an unresolved issue in teleosts. While it is known from aquaculture studies that stocking density has a negative relationship to growth, the underlying mechanisms have not been elucidated, primarily because the growth rate of populations rather than individual fish were the subject of all previous studies. Here we investigate this problem in the teleost Astyanax mexicanus, which consists of a sighted surface-dwelling form (surface fish and several blind cave-dwelling (cavefish forms. Surface fish and cavefish are distinguished by living in spatially contrasting environments and therefore are excellent models to study the effects of environmental size on growth. Multiple controlled growth experiments with individual fish raised in confined or unconfined spaces showed that environmental size has a major impact on growth rate in surface fish, a trait we have termed space dependent growth (SDG. In contrast, SDG has regressed to different degrees in the Pachón and Tinaja populations of cavefish. Mating experiments between surface and Pachón cavefish show that SDG is inherited as a dominant trait and is controlled by multiple genetic factors. Despite its regression in blind cavefish, SDG is not affected when sighted surface fish are raised in darkness, indicating that vision is not required to perceive and react to environmental space. Analysis of plasma cortisol levels showed that an elevation above basal levels occurred soon after surface fish were exposed to confined space. This initial cortisol peak was absent in Pachón cavefish, suggesting that the effects of confined space on growth may be mediated partly through a stress response. We conclude that Astyanax reacts to confined spaces by exhibiting SDG, which has a genetic component and shows evolutionary regression during adaptation of cavefish to confined environments.

  16. Larval developmental rate, metabolic rate and future growth performance in Atlantic salmon

    DEFF Research Database (Denmark)

    Serrano, Jonathan Vaz; Åberg, Madelene; Gjoen, Hans Magnus

    2009-01-01

    , quantified as time to first feeding, and growth in later stages was demonstrated in Atlantic salmon (Salmo salar L.). The observed relationship between future growth and larval developmental rate suggests that sorting larvae by time to first feeding can be a potential tool to optimize feeding strategies...... and growth in commercial rearing of Atlantic salmon. Furthermore, the link between larval standard metabolic rate and developmental rate and future growth is discussed in the present study....

  17. Using time-dependent models to investigate body condition and growth rate of the giant gartersnake

    Science.gov (United States)

    Coates, P.S.; Wylie, G.D.; Halstead, B.J.; Casazza, Michael L.

    2009-01-01

    Identifying links between phenotypic attributes and fitness is a primary goal of reproductive ecology. Differences in within-year patterns of body condition between sexes of gartersnakes in relation to reproduction and growth are not fully understood. We conducted an 11-year field study of body condition and growth rate of the giant gartersnake Thamnophis gigas across 13 study areas in the Central Valley of California, USA. We developed a priori mixed effects models of body condition index (BCI), which included covariates of time, sex and snout-vent length and reported the best-approximating models using an information theoretic approach. Also, we developed models of growth rate index (GRI) using covariates of sex and periods based on reproductive behavior. The largest difference in BCI between sexes, as predicted by a non-linear (cubic) time model, occurred during the mating period when female body condition (0.014??0.001 se) was substantially greater than males (-0.027??0.002 se). Males likely allocated energy to search for mates, while females likely stored energy for embryonic development. We also provided evidence that males use more body energy reserves than females during hibernation, perhaps because of different body temperatures between sexes. We found GRI of male snakes was substantially lower during the mating period than during a non-mating period, which indicated that a trade-off existed between searching for mates and growth. These findings contribute to our understanding of snake ecology in a Mediterranean climate. ?? 2009 The Zoological Society of London.

  18. Coordinated Changes in Mutation and Growth Rates Induced by Genome Reduction

    Directory of Open Access Journals (Sweden)

    Issei Nishimura

    2017-07-01

    Full Text Available Genome size is determined during evolution, but it can also be altered by genetic engineering in laboratories. The systematic characterization of reduced genomes provides valuable insights into the cellular properties that are quantitatively described by the global parameters related to the dynamics of growth and mutation. In the present study, we analyzed a small collection of W3110 Escherichia coli derivatives containing either the wild-type genome or reduced genomes of various lengths to examine whether the mutation rate, a global parameter representing genomic plasticity, was affected by genome reduction. We found that the mutation rates of these cells increased with genome reduction. The correlation between genome length and mutation rate, which has been reported for the evolution of bacteria, was also identified, intriguingly, for genome reduction. Gene function enrichment analysis indicated that the deletion of many of the genes encoding membrane and transport proteins play a role in the mutation rate changes mediated by genome reduction. Furthermore, the increase in the mutation rate with genome reduction was highly associated with a decrease in the growth rate in a nutrition-dependent manner; thus, poorer media showed a larger change that was of higher significance. This negative correlation was strongly supported by experimental evidence that the serial transfer of the reduced genome improved the growth rate and reduced the mutation rate to a large extent. Taken together, the global parameters corresponding to the genome, growth, and mutation showed a coordinated relationship, which might be an essential working principle for balancing the cellular dynamics appropriate to the environment.

  19. Flow-dependent directional growth of carbon nanotube forests by chemical vapor deposition

    International Nuclear Information System (INIS)

    Kim, Hyeongkeun; Park, Young Chul; Chun, Kyoung-Yong; Kim, Young-Jin; Choi, Jae-Boong; Kim, Keun Soo; Kang, Junmo; Hong, Byung Hee; Boo, Jin-Hyo

    2011-01-01

    We demonstrated that the structural formation of vertically aligned carbon nanotube (CNT) forests is primarily affected by the geometry-related gas flow, leading to the change of growth directions during the chemical vapor deposition (CVD) process. By varying the growing time, flow rate, and direction of the carrier gas, the structures and the formation mechanisms of the vertically aligned CNT forests were carefully investigated. The growth directions of CNTs are found to be highly dependent on the nonlinear local gas flows induced by microchannels. The angle of growth significantly changes with increasing gas flows perpendicular to the microchannel, while the parallel gas flow shows almost no effect. A computational fluid dynamics (CFD) model was employed to explain the flow-dependent growth of CNT forests, revealing that the variation of the local pressure induced by microchannels is an important parameter determining the directionality of the CNT growth. We expect that the present method and analyses would provide useful information to control the micro- and macrostructures of vertically aligned CNTs for various structural/electrical applications.

  20. Flow-dependent directional growth of carbon nanotube forests by chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyeongkeun; Park, Young Chul; Chun, Kyoung-Yong; Kim, Young-Jin; Choi, Jae-Boong [School of Mechanical Engineering, Sungkyunkwan University, Suwon, 440-746 (Korea, Republic of); Kim, Keun Soo; Kang, Junmo; Hong, Byung Hee [SKKU Advanced Institute of Nanotechnology (SAINT) and Center for Human Interface Nano Technology (HINT), Sungkyunkwan University, Suwon, 440-746 (Korea, Republic of); Boo, Jin-Hyo, E-mail: byunghee@skku.edu, E-mail: boong33@skku.edu [Department of Chemistry, RIAN and Institute of Basic Science, Sungkyunkwan University, Suwon, 440-746 (Korea, Republic of)

    2011-03-04

    We demonstrated that the structural formation of vertically aligned carbon nanotube (CNT) forests is primarily affected by the geometry-related gas flow, leading to the change of growth directions during the chemical vapor deposition (CVD) process. By varying the growing time, flow rate, and direction of the carrier gas, the structures and the formation mechanisms of the vertically aligned CNT forests were carefully investigated. The growth directions of CNTs are found to be highly dependent on the nonlinear local gas flows induced by microchannels. The angle of growth significantly changes with increasing gas flows perpendicular to the microchannel, while the parallel gas flow shows almost no effect. A computational fluid dynamics (CFD) model was employed to explain the flow-dependent growth of CNT forests, revealing that the variation of the local pressure induced by microchannels is an important parameter determining the directionality of the CNT growth. We expect that the present method and analyses would provide useful information to control the micro- and macrostructures of vertically aligned CNTs for various structural/electrical applications.

  1. Growth Rates of Microbes in the Oceans.

    Science.gov (United States)

    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.

  2. Radiation effects on time-dependent deformation: Creep and growth

    International Nuclear Information System (INIS)

    Simonen, E.P.

    1989-03-01

    Observations of irradiation creep strain as well as irradiation growth strain and related microstructures are reviewed and compared to mechanisms for radiation effects on time-dependent deformation. Composition, microstructure, stress and temperature affect irradiation creep less than thermal creep. Irradiation creep rates can often dominate thermal creep rates, particularly at low temperatures and low stresses. Irradiation creep mechanisms are classified in two general categories: (1) stress-induced preferential absorption and (2) climb-glide. In the former, creep results from dislocation climb, whereas in the latter, creep results from dislocation glide. The effects of irradiation creep on failure modes in nuclear environments are discussed. 53 refs., 18 figs., 1 tab

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

    Science.gov (United States)

    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.

  4. Effect of massing on larval growth rate.

    Science.gov (United States)

    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. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  5. Temperature dependences of growth rates and carrying capacities of marine bacteria depart from metabolic theoretical predictions

    KAUST Repository

    Huete-Stauffer, Tamara Megan; Arandia-Gorostidi, Nestor; Dí az-Pé rez, Laura; Moran, Xose Anxelu G.

    2015-01-01

    Using the metabolic theory of ecology (MTE) framework, we evaluated over a whole annual cycle the monthly responses to temperature of the growth rates (μ) and carrying capacities (K) of heterotrophic bacterioplankton at a temperate coastal site. We

  6. Understanding Biological Rates and their Temperature Dependence, from Enzymes to Ecosystems

    Science.gov (United States)

    Prentice, E.; Arcus, V. L.

    2017-12-01

    Temperature responses over various scales in biological systems follow a similar pattern; negative curvature results in an optimum temperature (Topt) for activity/growth/turnover, with decreases in rates on either side of Topt. Previously this downturn in rates at high temperatures has been attributed to enzyme denaturation, where a failing of the basic driving units of metabolism was used to describe curvature at the enzyme and organism level. However, recent developments in our understanding of the factors governing enzyme rates at different temperatures have guided a new understanding of the responses of biological systems. Enzymes catalyse reactions by driving the substrate through a high energy species, which is tightly bound to the enzyme. Macromolecular rate theory (MMRT) has recently been developed to account for the changes in the system brought about by this tight binding, specifically the change in the physical parameter heat capacity (ΔCǂp), and the effect this has on the temperature dependence of enzyme reactions. A negative ΔCǂp imparts the signature negative curvature to rates in the absence of denaturation, and finds that Topt, ΔCǂp and curvature are all correlated, placing constraints on biological systems. The simplest of cells comprise thousands of enzymatically catalysed reactions, functioning in series and in parallel in metabolic pathways to determine the overall growth rate of an organism. Intuitively, the temperature effects of enzymes play a role in determining the overall temperature dependence of an organism, in tandem with cellular level regulatory responses. However, the effect of individual Topt values and curvature on overall pathway behaviour is less apparent. Here, this is investigated in the context of MMRT through the in vitro characterisation of a six-step metabolic pathway to understand the steps in isolation and functioning in series. Pathway behaviour is found to be approximately an average of the properties of the

  7. A Minimalistic Resource Allocation Model to Explain Ubiquitous Increase in Protein Expression with Growth Rate.

    Directory of Open Access Journals (Sweden)

    Uri Barenholz

    Full Text Available 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.

  8. GROWTH RATE DISTRIBUTION OF BORAX SINGLE CRYSTALS ON THE (001 FACE UNDER VARIOUS FLOW RATES

    Directory of Open Access Journals (Sweden)

    Suharso Suharso

    2010-06-01

    Full Text Available The growth rates of borax single crystals from aqueous solutions at various flow rates in the (001 direction were measured using in situ cell method. From the growth rate data obtained, the growth rate distribution of borax crystals was investigated using Minitab Software and SPSS Software at relative supersaturation of 0807 and temperature of 25 °C. The result shows that normal, gamma, and log-normal distribution give a reasonably good fit to GRD. However, there is no correlation between growth rate distribution and flow rate of solution.   Keywords: growth rate dispersion (GRD, borax, flow rate

  9. Facet-Dependent Oxidative Goethite Growth As a Function of Aqueous Solution Conditions.

    Science.gov (United States)

    Strehlau, Jennifer H; Stemig, Melissa S; Penn, R Lee; Arnold, William A

    2016-10-04

    Nitroaromatic compounds are groundwater pollutants that can be degraded through reactions with Fe(II) adsorbed on iron oxide nanoparticles, although little is known about the evolving reactivity of the minerals with continuous pollutant exposure. In this work, Fe(II)/goethite reactivity toward 4-chloronitrobenzene (4-ClNB) as a function of pH, organic matter presence, and reactant concentrations was explored using sequential-spike batch reactors. Reaction rate constants were smaller with lower pH, introduction of organic matter, and diluted reactant concentrations as compared to a reference condition. Reaction rate constants did not change with the number of 4-ClNB spikes for all reaction conditions. Under all conditions, oxidative goethite growth was demonstrated through X-ray diffraction, magnetic characterization, and transmission electron microscopy. Nonparametric statistics were applied to compare histograms of lengths and widths of goethite nanoparticles as a function of varied solution conditions. The conditions that slowed the reaction also resulted in statistically shorter and wider particles than for the faster reactions. Additionally, added organic matter interfered with particle growth on the favorable {021} faces to a greater extent, with statistically reduced rate of growth on the tip facets and increased rate of growth on the side facets. These data demonstrate that oxidative growth of goethite in aqueous systems is dependent on major groundwater variables, such as pH and the presence of organic matter, which could lead to the evolving reactivity of goethite particles in natural environments.

  10. Constitutive modeling of rate dependence and microinertia effects in porous-plastic materials with multi-sized voids (MSVs)

    KAUST Repository

    Liu, Jinxing

    2012-11-27

    Micro-voids of varying sizes exist in most metals and alloys. Both experiments and numerical studies have demonstrated the critical influence of initial void sizes on void growth. The classical Gurson-Tvergaard-Needleman model summarizes the influence of voids with a single parameter, namely the void-volume fraction, excluding any possible effects of the void-size distribution. We extend our newly proposed model including the multi-sized void (MSV) effect and the void-interaction effect for the capability of working for both moderate and high loading rate cases, where either rate dependence or microinertia becomes considerable or even dominant. Parametric studies show that the MSV-related competitive mechanism among void growth leads to the dependence of the void growth rate on void size, which directly influences the void\\'s contribution to the total energy composition. We finally show that the stress-strain constitutive behavior is also affected by this MSV-related competitive mechanism. The stabilizing effect due to rate sensitivity and microinertia is emphasized. © 2013 IOP Publishing Ltd.

  11. Microtubules Growth Rate Alteration in Human Endothelial Cells

    Directory of Open Access Journals (Sweden)

    Irina B. Alieva

    2010-01-01

    Full Text Available To understand how microtubules contribute to the dynamic reorganization of the endothelial cell (EC cytoskeleton, we established an EC model expressing EB3-GFP, a protein that marks microtubule plus-ends. Using this model, we were able to measure microtubule growth rate at the centrosome region and near the cell periphery of a single human EC and in the EC monolayer. We demonstrate that the majority of microtubules in EC are dynamic, the growth rate of their plus-ends is highest in the internal cytoplasm, in the region of the centrosome. Growth rate of microtubule plus-ends decreases from the cell center toward the periphery. Our data suggest the existing mechanism(s of local regulation of microtubule plus-ends growth in EC. Microtubule growth rate in the internal cytoplasm of EC in the monolayer is lower than that of single EC suggesting the regulatory effect of cell-cell contacts. Centrosomal microtubule growth rate distribution in single EC indicated the presence of two subpopulations of microtubules with “normal” (similar to those in monolayer EC and “fast” (three times as much growth rates. Our results indicate functional interactions between cell-cell contacts and microtubules.

  12. Exchange-rate regimes and economic growth: An empirical evaluation

    OpenAIRE

    Simón Sosvilla-Rivero; María del Carmen Ramos-Herrera

    2014-01-01

    Based on a dataset of 123 economies, this paper empirically investigates the relation between exchange-rate regimes and economic growth. We find that growth performance is best under intermediate exchange rate regimes, while the smallest growth rates are associated with flexible exchange rates. Nevertheless, this conclusion is tempered when we analyze the countries by income level: even though countries that adopt intermediate exchange-rate regimes are characterized by higher economic growth,...

  13. Temperature-dependent growth of Geomyces destructans, the fungus that causes bat white-nose syndrome.

    Directory of Open Access Journals (Sweden)

    Michelle L Verant

    Full Text Available White-nose syndrome (WNS is an emergent disease estimated to have killed over five million North American bats. Caused by the psychrophilic fungus Geomyces destructans, WNS specifically affects bats during hibernation. We describe temperature-dependent growth performance and morphology for six independent isolates of G. destructans from North America and Europe. Thermal performance curves for all isolates displayed an intermediate peak with rapid decline in performance above the peak. Optimal temperatures for growth were between 12.5 and 15.8°C, and the upper critical temperature for growth was between 19.0 and 19.8°C. Growth rates varied across isolates, irrespective of geographic origin, and above 12°C all isolates displayed atypical morphology that may have implications for proliferation of the fungus. This study demonstrates that small variations in temperature, consistent with those inherent of bat hibernacula, affect growth performance and physiology of G. destructans, which may influence temperature-dependent progression and severity of WNS in wild bats.

  14. Temperature-dependent growth of Geomyces destructans, the fungus that causes bat white-nose syndrome.

    Science.gov (United States)

    Verant, Michelle L; Boyles, Justin G; Waldrep, William; Wibbelt, Gudrun; Blehert, David S

    2012-01-01

    White-nose syndrome (WNS) is an emergent disease estimated to have killed over five million North American bats. Caused by the psychrophilic fungus Geomyces destructans, WNS specifically affects bats during hibernation. We describe temperature-dependent growth performance and morphology for six independent isolates of G. destructans from North America and Europe. Thermal performance curves for all isolates displayed an intermediate peak with rapid decline in performance above the peak. Optimal temperatures for growth were between 12.5 and 15.8°C, and the upper critical temperature for growth was between 19.0 and 19.8°C. Growth rates varied across isolates, irrespective of geographic origin, and above 12°C all isolates displayed atypical morphology that may have implications for proliferation of the fungus. This study demonstrates that small variations in temperature, consistent with those inherent of bat hibernacula, affect growth performance and physiology of G. destructans, which may influence temperature-dependent progression and severity of WNS in wild bats.

  15. Investigation of the growth rate for joint fast breeder reactor and light water reactor operation

    International Nuclear Information System (INIS)

    Hanan, N.A.; Borg, C.R.; Ott, K.O.

    1977-07-01

    An investigation of fuel consumption and breeding characteristics of FBR-LWR joint operation is presented. The FBR operates in a closed cycle with joint-reprocessing of core and blanket material. The LWR-portion that runs on FBR plutonium operates in an open cycle. The growth rate of the system is defined based upon the fact that the discharge from the system will make up a fraction of an identical system; the system growth rate is found to have an almost linear dependence on the fraction of the LWR fed by plutonium from the FBR. The LWR growth rate, which is negative, is a constant and represents the fraction of the fuel burnt in the LWR-fraction that runs on FBR plutonium per year

  16. Measurements of Protein Crystal Face Growth Rates

    Science.gov (United States)

    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.

  17. Rising CO2 interacts with growth light and growth rate to alter photosystem II photoinactivation of the coastal diatom Thalassiosira pseudonana.

    Directory of Open Access Journals (Sweden)

    Gang Li

    Full Text Available We studied the interactive effects of pCO(2 and growth light on the coastal marine diatom Thalassiosira pseudonana CCMP 1335 growing under ambient and expected end-of-the-century pCO(2 (750 ppmv, and a range of growth light from 30 to 380 µmol photons·m(-2·s(-1. Elevated pCO(2 significantly stimulated the growth of T. pseudonana under sub-saturating growth light, but not under saturating to super-saturating growth light. Under ambient pCO(2 susceptibility to photoinactivation of photosystem II (σ(i increased with increasing growth rate, but cells growing under elevated pCO(2 showed no dependence between growth rate and σ(i, so under high growth light cells under elevated pCO(2 were less susceptible to photoinactivation of photosystem II, and thus incurred a lower running cost to maintain photosystem II function. Growth light altered the contents of RbcL (RUBISCO and PsaC (PSI protein subunits, and the ratios among the subunits, but there were only limited effects on these and other protein pools between cells grown under ambient and elevated pCO(2.

  18. Influence of Cell-Cell Interactions on the Population Growth Rate in a Tumor

    Science.gov (United States)

    Chen, Yong

    2017-12-01

    The understanding of the macroscopic phenomenological models of the population growth at a microscopic level is important to predict the population behaviors emerged from the interactions between the individuals. In this work, we consider the influence of the population growth rate R on the cell-cell interaction in a tumor system and show that, in most cases especially small proliferative probabilities, the regulative role of the interaction will be strengthened with the decline of the intrinsic proliferative probabilities. For the high replication rates of an individual and the cooperative interactions, the proliferative probability almost has no effect. We compute the dependences of R on the interactions between the cells under the approximation of the nearest neighbor in the rim of an avascular tumor. Our results are helpful to qualitatively understand the influence of the interactions between the individuals on the growth rate in population systems. Supported by the National Natural Science Foundation of China under Grant Nos. 11675008 and 21434001

  19. Using a laboratory-based growth model to estimate mass- and temperature-dependent growth parameters across populations of juvenile Chinook Salmon

    Science.gov (United States)

    Perry, Russell W.; Plumb, John M.; Huntington, Charles

    2015-01-01

    To estimate the parameters that govern mass- and temperature-dependent growth, we conducted a meta-analysis of existing growth data from juvenile Chinook Salmon Oncorhynchus tshawytscha that were fed an ad libitum ration of a pelleted diet. Although the growth of juvenile Chinook Salmon has been well studied, research has focused on a single population, a narrow range of fish sizes, or a narrow range of temperatures. Therefore, we incorporated the Ratkowsky model for temperature-dependent growth into an allometric growth model; this model was then fitted to growth data from 11 data sources representing nine populations of juvenile Chinook Salmon. The model fit the growth data well, explaining 98% of the variation in final mass. The estimated allometric mass exponent (b) was 0.338 (SE = 0.025), similar to estimates reported for other salmonids. This estimate of b will be particularly useful for estimating mass-standardized growth rates of juvenile Chinook Salmon. In addition, the lower thermal limit, optimal temperature, and upper thermal limit for growth were estimated to be 1.8°C (SE = 0.63°C), 19.0°C (SE = 0.27°C), and 24.9°C (SE = 0.02°C), respectively. By taking a meta-analytical approach, we were able to provide a growth model that is applicable across populations of juvenile Chinook Salmon receiving an ad libitum ration of a pelleted diet.

  20. Growth rate of YBCO-Ag superconducting single grains

    Science.gov (United States)

    Congreve, J. V. J.; Shi, Y. H.; Dennis, A. R.; Durrell, J. H.; Cardwell, D. A.

    2017-12-01

    The large scale use of (RE)Ba2Cu3O7 bulk superconductors, where RE=Y, Gd, Sm, is, in part, limited by the relatively poor mechanical properties of these inherently brittle ceramic materials. It is reported that alloying of (RE)Ba2Cu3O7 with silver enables a significant improvement in the mechanical strength of bulk, single grain samples without any detrimental effect on their superconducting properties. However, due to the complexity and number of inter-related variables involved in the top seeded melt growth (TSMG) process, the growth of large single grains is difficult and the addition of silver makes it even more difficult to achieve successful growth reliably. The key processing variables in the TSMG process include the times and temperatures of the stages within the heating profile, which can be derived from the growth rate during the growth process. To date, the growth rate of the YBa2Cu3O7-Ag system has not been reported in detail and it is this lacuna that we have sought to address. In this work we measure the growth rate of the YBCO-Ag system using a method based on continuous cooling and isothermal holding (CCIH). We have determined the growth rate by measuring the side length of the crystallised region for a number of samples for specified isothermal hold temperatures and periods. This has enabled the growth rate to be modelled and from this an optimized heating profile for the successful growth of YBCO-Ag single grains to be derived.

  1. Ant Larval Demand Reduces Aphid Colony Growth Rates in an Ant-Aphid Interaction

    Directory of Open Access Journals (Sweden)

    James M. Cook

    2012-02-01

    Full Text Available 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.

  2. Experimental determination of growth rate effect on U 6+ and Mg 2+ partitioning between aragonite and fluid at elevated U 6+ concentration

    Science.gov (United States)

    Gabitov, R. I.; Gaetani, G. A.; Watson, E. B.; Cohen, A. L.; Ehrlich, H. L.

    2008-08-01

    Results are reported from an experimental study in which the partitioning of U and Mg between aragonite and an aqueous solution were determined as a function of crystal growth rate. Crystals, identified as aragonite by X-ray diffractometry and micro-Raman spectroscopy, were grown by diffusion of CO 2 from an ammonium carbonate source into a calcium-bearing solution at temperatures of 22 and 53 °C. Hemispherical bundles (spherulites) of aragonite crystals were produced, the growth rates of which decreased monotonically from the spherulite interiors to the edges and thus provide the opportunity to examine the influence of growth rate on crystal composition. Element concentration ratios were measured using electron microprobe (EMP) and fluid composition was determined by inductively coupled plasma-mass spectrometry (ICP-MS) and atomic absorption (AA). Growth rates were determined directly by addition of a Dy spike to the fluid during the experiment that was subsequently located in an experimentally precipitated spherulite using secondary ion mass spectrometry (SIMS). At 22 °C both U/Ca and Mg/Ca partition coefficients exhibited a strong growth rate dependence when crystal growth rates were low, and became independent of growth rate when crystal growth rates were high. The U/Ca ratios in aragonite increase between 22 and 53 °C; in contrast Mg/Ca ratios show inverse dependence on temperature.

  3. Growth rate of matter perturbations as a probe of large-scale magnetism

    CERN Document Server

    Giovannini, Massimo

    2011-01-01

    The growth rate of matter perturbations is computed in a magnetized environment for the LambdaCDM and wCDM paradigms. It is argued that the baryons do not necessarily follow into the dark matter potential wells after they are released from the drag of the photons. The baryonic evolution equations inherit a forcing term whose explicit form depends on the plasma description and can be deduced, for instance, in the resistive magnetohydrodynamical approximation. After deriving an analytical expression for the growth rate applicable when dark energy does not cluster, the effects of relativistic corrections and of the inhomogeneities associated with the other species of the plasma are taken into account numerically. The spectral amplitudes and slopes of the stochastic magnetic background are selected to avoid appreciable distortions in the measured temperature and polarization anisotropies of the Cosmic Microwave Background. The growth of structures in the current paradigms of structure formation represents a compl...

  4. Growth rate, population entropy, and perturbation theory.

    OpenAIRE

    Demetrius, L.

    1989-01-01

    This paper is concerned with the connection between two classes of population variables: measures of population growth rate—the Malthusian parameter, the net reproduction rate, the gross reproduction rate, and the mean life expectancy; and measures of demographic heterogeneity—population entropy. It is shown that the entropy functions predict the response of the growth rate parameters to perturbations in the age-specific fecundity and mortality schedule. These results are invoked to introduce...

  5. Localized Technological Change and Path-Dependent Growth

    OpenAIRE

    Bassanini, A.

    1997-01-01

    In recent years the theory of macroeconomic growth has seen an expanding literature building upon the idea that technological change is localized (technology-specific) to investigate various phenomena such as leapfrogging, take-off, and social mobility. In this paper I explore the relationship between localized technological change and dependence on history of long-run aggregate output growth. The growth model I set forth show that, subject to mild assumptions on the stochastic process repres...

  6. EVIDENCE ON EMPLOYMENT RATE AND ECONOMIC GROWTH

    Directory of Open Access Journals (Sweden)

    Cornelia VĂCEANU

    2014-11-01

    Full Text Available This paper explores a causal relationship between employment rate and economic growth for European Union countries, in general, and produces a structural assessment of employment on the background of labour market dynamics. Economic growth is the key in economic theory and the main source of well-being and quality of life. Since the 2008 financial crisis, most European countries have experienced job shortage and unemployment problem, but today's European economic outlook is strengthening on the bases of a GDP growing momentum. Empirical data shows, regardless the GDP's moderate positive trend, the employment rate did not increase enough. Given this, the present analysis address the question: to what extent the employment rate is affected by economic growth?

  7. Rate of fatigue crack growth in residual stress fields of welded titanium joints with different contents of embrittling impurities

    International Nuclear Information System (INIS)

    Troshchenko, V.T.; Pokrovskij, V.V.; Yarusevich, V.L.; Mikhajlov, V.I.; Sher, V.A.

    1990-01-01

    Resistance to fatigue crack growth (FCG) has been studied in welded joints of structural titanium alloys contaminated by embrittling impurities. Besides, effect of crack closing has been taken into account what makes it possible to determine the effective coefficient of the stress intensity. The rate of fatigue crack growth is proved to considerably depend on the value and direction of residual stresses. The rate dependence of FCG in welded joints of structural titanium alloys on the swing of effective coefficient of stress intensity is invariant to the value and direction of weld residual stresses

  8. Hatching rate and growth rate of Nothobranchius guentheri fertilized eggs after space flight

    International Nuclear Information System (INIS)

    Guo Mingzhong; Zheng Leyun; Lin Guangji; Zhong Jianxing; Yang Huosheng; Zheng Yangfu

    2012-01-01

    Hatching, abnormal, growth and survival rate of the fertilized eggs of Nothobranchius guentheri were carried by Shenzhou 7 spacecraft were studied. The results indicated that the hatching and abnormal rate were no significant difference between the spaceflight group (99.3% and 16.8%) and ground group (97.2% and 10.4%); but the growth rate of male fish from spaceflight group was significant higher (0.094 g/d) than that of ground group (0.059 g/d), leading to the significant bigger of the male fish from spaceflight group. The survival rate of spaceflight group (66.7%) was higher than the ground group (47.9%). It was concluded that there was a higher growth and survival rate of Nothobranchius guentheri fertilized eggs after space flight. (authors)

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

    Science.gov (United States)

    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.

  10. Volume growth rate of acoustic neurinomas

    International Nuclear Information System (INIS)

    Laasonen, E.M.; Troupp, H.

    1986-01-01

    Of 79 acoustic neurinomas seen between June 1980 and June 1984, at least two CT scans were available for each of 23 tumours (21 patients); the scans were performed at intervals of at least 6 months. The volume growth rate of the tumours was either moderate, with a volume doubling time ranging from 205 to 545 days, or slow, with a doubling time ranging from 1090 days to no observable growth. No single clinical, radiological or histological feature correlated with any type of growth rate. However, some conclusions were drawn. If a primary CT scan is negative, at least 1 year should elapse before it is worthwhile taking another scan, even though audiological findings suggest growth; after an apparently radical removal, at least 3 years should elapse before a check CT scan is worthwhile; and if a small acoustic neurinoma is diagnosed, but for some reason not operated upon, a second CT scan should be carried out 1 year later in order to reassess the case. (orig.)

  11. Money Supply, Interest Rate, and Economic Growth in Cameroon: A ...

    African Journals Online (AJOL)

    Money Supply, Interest Rate, and Economic Growth in Cameroon: A Time Series ... the impacts of money and interest rate on economic growth and development. ... Money Supply, Interest Rates, Economic growth, Co-integration and Inflation.

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

    Directory of Open Access Journals (Sweden)

    Susannah S French

    Full Text Available 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.

  13. Standard test method for measurement of fatigue crack growth rates

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2015-01-01

    1.1 This test method covers the determination of fatigue crack growth rates from near-threshold to Kmax controlled instability. Results are expressed in terms of the crack-tip stress-intensity factor range (ΔK), defined by the theory of linear elasticity. 1.2 Several different test procedures are provided, the optimum test procedure being primarily dependent on the magnitude of the fatigue crack growth rate to be measured. 1.3 Materials that can be tested by this test method are not limited by thickness or by strength so long as specimens are of sufficient thickness to preclude buckling and of sufficient planar size to remain predominantly elastic during testing. 1.4 A range of specimen sizes with proportional planar dimensions is provided, but size is variable to be adjusted for yield strength and applied force. Specimen thickness may be varied independent of planar size. 1.5 The details of the various specimens and test configurations are shown in Annex A1-Annex A3. Specimen configurations other than t...

  14. Effect of Ni and Cr on IGSCC growth rate of Ni-Cr-Fe alloys in PWR primary water

    International Nuclear Information System (INIS)

    Arioka, K.; Yamada, T.; Aoki, M.; Miyamoto, T.

    2015-01-01

    The purpose of this research is to examine the dependence of SCC (Stress Corrosion Crack) growth on nickel and chromium in PWR primary water; the objective is to obtain the basic knowledge to understand SCC behavior of steam generator tubing materials. The second objective is to understand whether accelerated testing at higher temperatures is appropriate for predicting SCC initiation and growth at lower temperatures. For these objectives, SCC growth was measured in PWR primary water at 290, 320, 330, 340, and 360 C. degrees under static load conditions. Tests were performed using 0.5 T compact tension type specimen using 20%CW X%Ni-16%Cr-Fe alloys in the range of nickel concentration between 16 to 60% and laboratory melted nuclear grade 20% cold worked Alloy 800 (USN N08800, CW800NG). Four important patterns were observed. First, significant effect of nickel on IGSCC resistance was observed at 340 and 360 C. degrees. The rate of IGSCC growth decreases with increasing nickel concentration in the range of nickel concentration between 10% to 25% nickel; and then, the rate of IGSCC increases with increasing nickel concentration in the range of Ni content between 50% and 76%. This trend is quite similar to the results reported by Coriou and Staehle tested in deaerated pure water at 350 C. degrees. However, no significant dependence of Ni content on IGSCC in PWR water at 320 and 290 C. degrees was observed. The change in SCC growth dependence on nickel concentration suggested that the main rate limiting processes on IGSCC growth seems to change between 320 and 340 C. degrees. Secondly, significant beneficial effects of chromium in alloys were observed at 320 C. degrees. However, no beneficial effect of chromium addition in alloys was observed at 360 C. degrees. Thirdly, peak temperatures in growth rate of IGSCC were observed in almost all test materials except for 20%CW Alloy 600. Finally, intergranular attack was observed in some alloys at lower temperature, and the

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  16. Resistive Wall Growth Rate Measurements in the Fermilab Recycler

    Energy Technology Data Exchange (ETDEWEB)

    Ainsworth, R. [Fermilab; Adamson, P. [Fermilab; Burov, A. [Fermilab; Kourbanis, I. [Fermilab

    2016-10-05

    Impedance could represent a limitation of running high intensity beams in the Fermilab recycler. With high intensity upgrades foreseen, it is important to quantify the impedance. To do this,studies have been performed measuring the growth rate of presumably the resistive wall instability. The growth rates at varying intensities and chromaticities are shown. The measured growth rates are compared to ones calculated with the resistive wall impedance.

  17. Effective Exchange Rate Classifications and Growth

    OpenAIRE

    Justin M. Dubas; Byung-Joo Lee; Nelson C. Mark

    2005-01-01

    We propose an econometric procedure for obtaining de facto exchange rate regime classifications which we apply to study the relationship between exchange rate regimes and economic growth. Our classification method models the de jure regimes as outcomes of a multinomial logit choice problem conditional on the volatility of a country's effective exchange rate, a bilateral exchange rate and international reserves. An `effective' de facto exchange rate regime classification is then obtained by as...

  18. Attaining the rate-independent limit of a rate-dependent strain gradient plasticity theory

    DEFF Research Database (Denmark)

    El-Naaman, Salim Abdallah; Nielsen, Kim Lau; Niordson, Christian Frithiof

    2016-01-01

    The existence of characteristic strain rates in rate-dependent material models, corresponding to rate-independent model behavior, is studied within a back stress based rate-dependent higher order strain gradient crystal plasticity model. Such characteristic rates have recently been observed...... for steady-state processes, and the present study aims to demonstrate that the observations in fact unearth a more widespread phenomenon. In this work, two newly proposed back stress formulations are adopted to account for the strain gradient effects in the single slip simple shear case, and characteristic...... rates for a selected quantity are identified through numerical analysis. Evidently, the concept of a characteristic rate, within the rate-dependent material models, may help unlock an otherwise inaccessible parameter space....

  19. Effects of Phlomis umbrosa Root on Longitudinal Bone Growth Rate in Adolescent Female Rats

    Directory of Open Access Journals (Sweden)

    Donghun Lee

    2016-04-01

    Full Text Available 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.

  20. Linear growth rates of resistive tearing modes with sub-Alfvénic streaming flow

    International Nuclear Information System (INIS)

    Wu, L. N.; Ma, Z. W.

    2014-01-01

    The tearing instability with sub-Alfvénic streaming flow along the external magnetic field is investigated using resistive MHD simulation. It is found that the growth rate of the tearing mode instability is larger than that without the streaming flow. With the streaming flow, there exist two Alfvén resonance layers near the central current sheet. The larger perturbation of the magnetic field in two closer Alfvén resonance layers could lead to formation of the observed cone structure and can largely enhance the development of the tearing mode for a narrower streaming flow. For a broader streaming flow, a larger separation of Alfvén resonance layers reduces the magnetic reconnection. The linear growth rate decreases with increase of the streaming flow thickness. The growth rate of the tearing instability also depends on the plasma beta (β). When the streaming flow is embedded in the current sheet, the growth rate increases with β if β  s , but decreases if β > β s . The existence of the specific value β s can be attributed to competition between the suppressing effect of β and the enhancing effect of the streaming flow on the magnetic reconnection. The critical value β s increases with increase of the streaming flow strength

  1. Vector population growth and condition-dependent movement drive the spread of plant pathogens.

    Science.gov (United States)

    Shaw, Allison K; Peace, Angela; Power, Alison G; Bosque-Pérez, Nilsa A

    2017-08-01

    Plant viruses, often spread by arthropod vectors, impact natural and agricultural ecosystems worldwide. Intuitively, the movement behavior and life history of vectors influence pathogen spread, but the relative contribution of each factor has not been examined. Recent research has highlighted the influence of host infection status on vector behavior and life history. Here, we developed a model to explore how vector traits influence the spread of vector-borne plant viruses. We allowed vector life history (growth rate, carrying capacity) and movement behavior (departure and settlement rates) parameters to be conditional on whether the plant host is infected or healthy and whether the vector is viruliferous (carrying the virus) or not. We ran simulations under a wide range of parameter combinations and quantified the fraction of hosts infected over time. We also ran case studies of the model for Barley yellow dwarf virus, a persistently transmitted virus, and for Potato virus Y, a non-persistently transmitted virus. We quantified the relative importance of each parameter on pathogen spread using Latin hypercube sampling with the statistical partial rank correlation coefficient technique. We found two general types of mechanisms in our model that increased the rate of pathogen spread. First, increasing factors such as vector intrinsic growth rate, carrying capacity, and departure rate from hosts (independent of whether these factors were condition-dependent) led to more vectors moving between hosts, which increased pathogen spread. Second, changing condition-dependent factors such as a vector's preference for settling on a host with a different infection status than itself, and vector tendency to leave a host of the same infection status, led to increased contact between hosts and vectors with different infection statuses, which also increased pathogen spread. Overall, our findings suggest that vector population growth rates had the greatest influence on rates of virus

  2. Impact of AlN seeding layer growth rate in MOVPE growth of semi-polar gallium nitride structures on high index silicon

    Energy Technology Data Exchange (ETDEWEB)

    Ravash, Roghaiyeh; Blaesing, Juergen; Hempel, Thomas; Noltemeyer, Martin; Dadgar, Armin; Christen, Juergen; Krost, Alois [Otto-von-Guericke-University Magdeburg, FNW/IEP/AHE, Postfach 4120, 39016 Magdeburg (Germany)

    2011-03-15

    We present metal organic vapor phase epitaxy growth of semi-polar GaN structures on high index silicon surfaces. The crystallographic structure of GaN grown on Si(112), (115), and (117) substrates is investigated by X-ray analysis and scanning electron microscopy. X-ray diffraction was performed in Bragg Brentano geometry as well as pole figure measurements. The results demonstrate that the orientation of GaN crystallites on Si is significantly dependent on thickness of the AlN seeding layer and TMAl-flow rate. We observe that the crystallographic structures of GaN by applying thin AlN seeding layers grown with high TMAl-flow rate depend on Si surface direction while they are independent for thicker layers. By applying such seeding layer we obtain single crystalline semi-polar GaN on Si(112), while GaN structures grown with the same growth parameters on Si(117) show four components of GaN(0002). (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  3. Re-assessing copepod growth using the Moult Rate method

    DEFF Research Database (Denmark)

    Hirst, Andrew G.; Keister, J. E.; Richardson, A. J.

    2014-01-01

    Estimating growth and production rates of mesozooplankton, and copepods in particular, is important in describing flows of material and energy though pelagic systems. Over the past 30 years, the Moult Rate (MR) method has been used to estimate juvenile copepod growth rates in ∼40 papers. Yet the MR......-moulting stage, e.g. copepodite stage 5 to adult. We performed experiments with Calanus pacificus to estimate growth of stage C5 using an alternative method. We found that the error size and sign varied between mass type (i.e. DW, C and N). Recommendations for practical future assessments of growth in copepods...

  4. Bootstrapping as a Resource Dependence Management Strategy and its Association with Startup Growth

    OpenAIRE

    T. VANACKER; S. MANIGART; M. MEULEMAN; L. SELS

    2011-01-01

    This paper studies the association between bootstrapping and startup growth. Bootstrapping reduces a startup’s dependence on financial investors, but may create new dependencies. Drawing upon resource dependence theory, we hypothesize that when bootstrapping does not create new strong dependencies it will benefit startup growth, especially when dependence from financial investors is high. However, when bootstrapping creates new strong dependencies it will constrain growth, especially when dep...

  5. Light-Dependency of Growth and Secondary Metabolite Production in the Captive Zooxanthellate Soft Coral Sinularia flexibilis

    NARCIS (Netherlands)

    Khalesi, M.K.; Beeftink, H.H.; Wijffels, R.H.

    2009-01-01

    The branching zooxanthellate soft coral Sinularia flexibillis releases antimicrobial and toxic compounds with potential pharmaceutical importance. As photosynthesis by the symbiotic algae is vital to the host, the light-dependency of the coral, including its specific growth rate (µ day-1) and the

  6. Divergent biparietal diameter growth rates in twin pregnancies.

    Science.gov (United States)

    Houlton, M C

    1977-05-01

    Twenty-eight twin pregnancies were monitored by serial ultrasonic cephalometry from 30 or 31 weeks' gestation. The rates of growth of the individual twins as determined by biparietal diameters were similar in 11 cases (39%) and divergent in 17 (61%). When the rates of growth were divergent, the lesser rate was always below the mean for singleton pregnancies, and the incidence of small-for-gestational-age babies was 18 of 34 (53%). It was apparent that the greater the difference in biparietal diameters within the 2 weeks preceding delivery, the higher the risk of a small-for-gestation-age baby being delivered. No comment could be made on the growth rate prior to 28 weeks except that at diagnosis there was little or no difference in biparietal diameters.

  7. Preliminary observation of genital secretions, growth rate and ...

    African Journals Online (AJOL)

    Cane rats are large terrestial rodents which have the potential to increase animal protein intake. There is paucity of information on the genital secretions and growth rate of caged cane rats. This study observed the genital secretions, growth rate, feeds, feeding and the behaviour of caged cane rats. When animals adjusted to ...

  8. Astragalus Extract Mixture HT042 Increases Longitudinal Bone Growth Rate by Upregulating Circulatory IGF-1 in Rats

    Directory of Open Access Journals (Sweden)

    Donghun Lee

    2017-01-01

    Full Text Available Astragalus extract mixture HT042 is a standardized ingredient of health functional food approved by Korean FDA with a claim of “height growth of children.” HT042 stimulates bone growth rate and increases local IGF-1 expression in growth plate of rats which can be considered as direct stimulation of GH and its paracrine/autocrine actions. However, it remains unclear whether HT042 stimulates circulatory IGF-1 which also plays a major role to stimulate bone growth. To determine the effects on circulatory IGF-1, IGF-1 and IGFBP-3 expressions and phosphorylation of JAK2/STAT5 were evaluated in the liver after 10 days of HT042 administration. HT042 upregulated liver IGF-1 and IGFBP-3 mRNA expression, IGF-1 protein expression, and phosphorylation of JAK2/STAT5. HT042 also increased bone growth rate and proliferative zonal height in growth plate. In conclusion, HT042 stimulates bone growth rate via increment of proliferative rate by upregulation of liver IGF-1 and IGFBP-3 mRNA followed by IGF-1 protein expression through phosphorylation of JAK2/STAT5, which can be regarded as normal functioning of GH-dependent endocrine pathway.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Stephanie P Cartwright

    Full Text Available 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.

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

    Science.gov (United States)

    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.

  12. Convexity, gauge-dependence and tunneling rates

    Energy Technology Data Exchange (ETDEWEB)

    Plascencia, Alexis D.; Tamarit, Carlos [Institute for Particle Physics Phenomenology, Durham University,South Road, DH1 3LE (United Kingdom)

    2016-10-19

    We clarify issues of convexity, gauge-dependence and radiative corrections in relation to tunneling rates. Despite the gauge dependence of the effective action at zero and finite temperature, it is shown that tunneling and nucleation rates remain independent of the choice of gauge-fixing. Taking as a starting point the functional that defines the transition amplitude from a false vacuum onto itself, it is shown that decay rates are exactly determined by a non-convex, false vacuum effective action evaluated at an extremum. The latter can be viewed as a generalized bounce configuration, and gauge-independence follows from the appropriate Nielsen identities. This holds for any election of gauge-fixing that leads to an invertible Faddeev-Popov matrix.

  13. Convexity, gauge-dependence and tunneling rates

    International Nuclear Information System (INIS)

    Plascencia, Alexis D.; Tamarit, Carlos

    2016-01-01

    We clarify issues of convexity, gauge-dependence and radiative corrections in relation to tunneling rates. Despite the gauge dependence of the effective action at zero and finite temperature, it is shown that tunneling and nucleation rates remain independent of the choice of gauge-fixing. Taking as a starting point the functional that defines the transition amplitude from a false vacuum onto itself, it is shown that decay rates are exactly determined by a non-convex, false vacuum effective action evaluated at an extremum. The latter can be viewed as a generalized bounce configuration, and gauge-independence follows from the appropriate Nielsen identities. This holds for any election of gauge-fixing that leads to an invertible Faddeev-Popov matrix.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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.

  16. Exchange Rate Fluctuation and the Nigeria Economic Growth

    Directory of Open Access Journals (Sweden)

    Lawal Adedoyin Isola

    2016-11-01

    Full Text Available The aim of this study is to investigate the impact of exchange rate fluctuation on economic growth in Nigeria within the context of four profound theories: purchasing power parity; monetary model of exchange rates; the portfolio balance approach; and the optimal currency area theory. Data was collected from the CBN statistical bulletin in Nigeria from 2003– 2013and the Autoregressive Distributed Lag (ARDL model was employed to estimate the model. In the model, real GDP (RGDP was used as the proxy for economic growth while Inflation rate (IF, Exchange rate (EXC, Interest rate (INT and Money Supply(M2 as proxies for other macroeconomic variables. The empirical results show that exchange rate fluctuation has no effect on economic growth in the long run though a short run relationship exist between the two. Based on these findings, this paper recommends that the Central bank for policy purposes should ensure that stern foreign exchange control policies are put in place in order to help in appropriate determination of the value of the exchange rate. This will in the long run help to strengthen the value of the Naira.

  17. Effect of selection for relative growth rate and bodyweight of mice on rate, composition and efficiency of growth

    NARCIS (Netherlands)

    Bakker, H.

    1974-01-01

    To evaluate the effect of selection for parameters of a growth curve, four selection lines and a control line were started from one base population. In the selection lines is selected for a large and a small relative growth rate between 21 and 29 days (RGH and RGL) and for a large and

  18. Quorum sensing influences Vibrio harveyi growth rates in a manner not fully accounted for by the marker effect of bioluminescence.

    Science.gov (United States)

    Nackerdien, Zeena E; Keynan, Alexander; Bassler, Bonnie L; Lederberg, Joshua; Thaler, David S

    2008-02-27

    The light-emitting Vibrios provide excellent material for studying the interaction of cellular communication with growth rate because bioluminescence is a convenient marker for quorum sensing. However, the use of bioluminescence as a marker is complicated because bioluminescence itself may affect growth rate, e.g. by diverting energy. The marker effect was explored via growth rate studies in isogenic Vibrio harveyi (Vh) strains altered in quorum sensing on the one hand, and bioluminescence on the other. By hypothesis, growth rate is energy limited: mutants deficient in quorum sensing grow faster because wild type quorum sensing unleashes bioluminescence and bioluminescence diverts energy. Findings reported here confirm a role for bioluminescence in limiting Vh growth rate, at least under the conditions tested. However, the results argue that the bioluminescence is insufficient to explain the relationship of growth rate and quorum sensing in Vh. A Vh mutant null for all genes encoding the bioluminescence pathway grew faster than wild type but not as fast as null mutants in quorum sensing. Vh quorum sensing mutants showed altered growth rates that do not always rank with their relative increase or decrease in bioluminescence. In addition, the cell-free culture fluids of a rapidly growing Vibrio parahaemolyticus (Vp) strain increased the growth rate of wild type Vh without significantly altering Vh's bioluminescence. The same cell-free culture fluid increased the bioluminescence of Vh quorum mutants. The effect of quorum sensing on Vh growth rate can be either positive or negative and includes both bioluminescence-dependent and independent components. Bioluminescence tends to slow growth rate but not enough to account for the effects of quorum sensing on growth rate.

  19. Quorum sensing influences Vibrio harveyi growth rates in a manner not fully accounted for by the marker effect of bioluminescence.

    Directory of Open Access Journals (Sweden)

    Zeena E Nackerdien

    2008-02-01

    Full Text Available The light-emitting Vibrios provide excellent material for studying the interaction of cellular communication with growth rate because bioluminescence is a convenient marker for quorum sensing. However, the use of bioluminescence as a marker is complicated because bioluminescence itself may affect growth rate, e.g. by diverting energy.The marker effect was explored via growth rate studies in isogenic Vibrio harveyi (Vh strains altered in quorum sensing on the one hand, and bioluminescence on the other. By hypothesis, growth rate is energy limited: mutants deficient in quorum sensing grow faster because wild type quorum sensing unleashes bioluminescence and bioluminescence diverts energy. Findings reported here confirm a role for bioluminescence in limiting Vh growth rate, at least under the conditions tested. However, the results argue that the bioluminescence is insufficient to explain the relationship of growth rate and quorum sensing in Vh. A Vh mutant null for all genes encoding the bioluminescence pathway grew faster than wild type but not as fast as null mutants in quorum sensing. Vh quorum sensing mutants showed altered growth rates that do not always rank with their relative increase or decrease in bioluminescence. In addition, the cell-free culture fluids of a rapidly growing Vibrio parahaemolyticus (Vp strain increased the growth rate of wild type Vh without significantly altering Vh's bioluminescence. The same cell-free culture fluid increased the bioluminescence of Vh quorum mutants.The effect of quorum sensing on Vh growth rate can be either positive or negative and includes both bioluminescence-dependent and independent components. Bioluminescence tends to slow growth rate but not enough to account for the effects of quorum sensing on growth rate.

  20. Microbial uptake of radiolabeled substrates: estimates of growth rates from time course measurements

    International Nuclear Information System (INIS)

    Li, W.K.W.

    1984-01-01

    The uptake of [ 3 H]glucose and a mixture of 3 H-labeled amino acids was measured, in time course fashion, in planktonic microbial assemblages of the eastern tropical Pacific Ocean. The average generation times of those portions of the assemblages able to utilize these substrates were estimated from a simple exponential growth model. Other workers have independently used this model in its integrated or differential form. A mathematical verification and an experimental demonstration of the equivalence of the two approaches are presented. A study was made of the size distribution of heterotrophic activity, using time course measurements. It was found that the size distribution and the effect of sample filtration before radiolabeling were dependent on time of incubation. In principle, it was possible to ascribe these time dependences to differences in th specific growth rate and initial standing stock of the microbial assemblages. 33 references

  1. Variation in coral growth rates with depth at Discovery Bay, Jamaica

    Energy Technology Data Exchange (ETDEWEB)

    Huston, M

    1985-01-01

    Growth rates, determined by X-radiographic measurement of skeletal extension, decreased with depth for four of six species of coral examined at Discovery Bay, Jamaica. Growth of Porites astreoides, Montastrea annularis, Colpophyllia natans, and Siderastrea siderea decreased significantly with depth over a 1- to 30-m depth range. In Montastrea cavernosa, the highest growth rate occurred in the middle of the sampled depth range. Agaricia agaricites had no measurable change in growth rate with depth. A compilation of available growth data for Atlantic and Pacific corals shows a strong pattern of highest growth rates a short distance below the surface and a decrease with depth.

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

    Science.gov (United States)

    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. Growth, development and productivity of Jerusalem artichoke depending on plant stand in the conditions of the Republic of Karakalpakstan

    Directory of Open Access Journals (Sweden)

    Zhangabaeva A.S.

    2017-08-01

    Full Text Available the article presents the results of studying the influence of various schemes of planting seed tubers of Jerusalem artichoke on the rate of plant growth and development in the soil and climatic conditions of the Republic of Karakalpakstan. Differences in the rate of growth and development of plants are revealed, depending on the varietal features of Jerusalem artichoke and the density of their standing. The most optimal scheme for planting tubers of Jerusalem artichoke is 70x40 cm.

  4. Evaluation of Mycelium Growth Rate and Yield of White Button Mushroom Isolates (Agaricus bisporus in Iran

    Directory of Open Access Journals (Sweden)

    Mohammad Javad Ahmadi Lahijani

    2017-10-01

    Full Text Available Introduction: Among edible mushrooms, white button mushroom is the most cultivated one around the world. Mono-spores diversity in terms of growth rate, colony type, yield and etc. is used for intra strain genetic improvement. High yielding isolates with filamentous mycelium type are screened and used for spawn production (Farsi and Gordan, 2002. Success in mushroom production largely depends on the quality of spawn produced in sterile conditions (Sanchez, 2010. Farsi and Gordan, (2004 reported that colony shape and mycelium growth type are very important factors in screening isolates in terms of mycelium growth rate and yield. To screen isolates based on their mycelium growth, solid media are among the most suitable ones (Griffin, 1994. In a study conducted to evaluate mycelium growth rate of six Morchella species on different media, PDA and MEA were known as the best ones (Kalmis and Kalyoncu, 2008. The present study was conducted in order to evaluate mycelium growth rate and yield of white button mushroom isolates in solid medium, spawn and compost media. Materials and methods: Eighteen isolates of white button mushroom were compared on PDA (Potato Dextrose Agar, CYM (Complete Yeast Medium, spawn and compost media based on mycelium growth rate, type and class growth and yield at the mushroom research center of Faculty of Agriculture, Ferdowsi University of Mashhad, in 2014. A piece of mycelium of each isolate was placed in the center of each petri dish and was kept in 23±1°C, and the radial growth rate of mycelium was measured as two perpendicular diameters in three consecutive weeks. Mycelium growth rate on spawn and compost media was measured based on the percentage of surface coverage during the 15 consecutive days. Yield of each isolate was measured by daily harvesting of mushrooms during 35 days of experiment. Analysis of variance and means comparison of the variables were carried out using SAS software. Means analysis was performed

  5. PENGARUH PROFIT MARGIN, ASSETS TURNOVER DAN LEVERAGE TERHADAP SUSTAINABLE GROWTH RATE PADA PERUSAHAAN SEKTOR JASA YANG TERDAFTAR DI BURSA EFEK INDONESIA PERIODE 2010-2012

    Directory of Open Access Journals (Sweden)

    Arim Nasim

    2015-04-01

    Full Text Available This study aims to determine the effect of Profit Margin, Assets Turnover and Leverage on Sustainable Growth Rate. The variables used are profit margin, asset turnover and leverage as independent variable and sustainable growth rate as dependent variable. This study also aims to describe the state of profit margin projected by Net Profit Margin (NPM, asset turnover proxied by Total Assets Turnover (TATO, leverage which is proxied by Debt to Equity Ratio (DER and Sustainable Growth Rate (SGR Service sector. This research was conducted on service sector companies listed in Indonesia Stock Exchange 2010-2012.Data obtained from website Bursa Efek Indonesia.Teknik data analysis used is multiple linear regression and use t-statistics to test the influence of each independent variable to variable Dependent partially.Previously done classical assumption test that includes data normality test, multicolinierity test, heteroskedastisitas test and autocorrelation test.Based on data normality test, multicolinierity test, heteroscedasticity test and autocorrelation test did not found any variables that deviate from the classical assumption.From the results of research Shows that profit margin positively affect sustainable growth rate, asset turnover have positive effect to sustainable growth rate, and leverage have positive effect to sustainable growth rate.

  6. GROWTH-RATES OF SHRUBS ON DIFFERENT SOILS IN TANZANIA

    NARCIS (Netherlands)

    PRINS, HHT; VANDERJEUGD, HP

    1992-01-01

    Because little is known of growth rates of shrubs in East Africa, the growth rates of Acalypha fructicosa, Gardenia jovis-tonantis, Justicia cordata, Maerua triphylla, and Ocimum suave were measured in Lake Manyara National Park, northern Tanzania. Branch diameter increments and branch length

  7. Growth rates of shrubs on different soils in Tanzania.

    NARCIS (Netherlands)

    Prins, H.H.T.; Jeugd, van der H.P.

    1992-01-01

    Because little is known of growth rates of shrubs in East Africa, the growth rates of Acalypha fructicosa, Gardenia jovis-tonantis, Justicia cordata, Maerua triphylla, and Ocimum suave were measured in Lake Manyara National Park, northern Tanzania. Branch diameter increments and branch length

  8. Estimation and Forecasting the Gross Domestic Product´s Growth Rate in Ecuador: a Short-term Vision

    Directory of Open Access Journals (Sweden)

    Yadier Alberto Torres−Sánchez

    2016-12-01

    Full Text Available Ecuador is the seventh largest economy in Latin America. From 2000 to 2012, the country has been expanding at an average rate of 1,15 % on a quarter over quarter basis, mostly due to a rise in exports. Ecuador´s economy is highly dependent on oil exports. In order to reach its full growth potential, the country needs to reduce its dependence on oil revenue; increase the tax base; achieve political stability and reduce the levels of poverty and inequality. The main objective of this research is specifically marked in estimate and forecast the Gross Domestic Product´s Growth Rate in Ecuador, applying for this Box – Jenkins´ Methodology for ARIMA models. It was obtained a forecast of 3,96 % approximately, that represents a logical result according with the time series.

  9. Estimation and Forecasting the Gross Domestic Product´s Growth Rate in Ecuador: a Short-term Vision

    Directory of Open Access Journals (Sweden)

    Yadier Alberto Torres−Sánchez

    2017-01-01

    Full Text Available Ecuador is the seventh largest economy in Latin America. From 2000 to 2012, the country has been expanding at an average rate of 1,15 % on a quarter over quarter basis, mostly due to a rise in exports. Ecuador´s economy is highly dependent on oil exports. In order to reach its full growth potential, the country needs to reduce its dependence on oil revenue; increase the tax base; achieve political stability and reduce the levels of poverty and inequality. The main objective of this research is specifically marked in estimate and forecast the Gross Domestic Product´s Growth Rate in Ecuador, applying for this Box – Jenkins´ Methodology for ARIMA models. It was obtained a forecast of 3,96 % approximately, that represents a logical result according with the time series.

  10. Postnatal Growth Rates of Hummingbirds : Review and New Records

    NARCIS (Netherlands)

    Freymann, Bernd P.; Schuchmann, Karl-Ludwig

    2008-01-01

    We review the published information on postnatal growth rates of hummingbirds (13 species), and report previously unpublished records for nine additional trochilid species. The allometric relationship based on the log(10)-transformed data of K (logistic growth rate constant) and body mass has a

  11. The Variance Composition of Firm Growth Rates

    Directory of Open Access Journals (Sweden)

    Luiz Artur Ledur Brito

    2009-04-01

    Full Text Available Firms exhibit a wide variability in growth rates. This can be seen as another manifestation of the fact that firms are different from one another in several respects. This study investigated this variability using the variance components technique previously used to decompose the variance of financial performance. The main source of variation in growth rates, responsible for more than 40% of total variance, corresponds to individual, idiosyncratic firm aspects and not to industry, country, or macroeconomic conditions prevailing in specific years. Firm growth, similar to financial performance, is mostly unique to specific firms and not an industry or country related phenomenon. This finding also justifies using growth as an alternative outcome of superior firm resources and as a complementary dimension of competitive advantage. This also links this research with the resource-based view of strategy. Country was the second source of variation with around 10% of total variance. The analysis was done using the Compustat Global database with 80,320 observations, comprising 13,221 companies in 47 countries, covering the years of 1994 to 2002. It also compared the variance structure of growth to the variance structure of financial performance in the same sample.

  12. Estimating blue whale skin isotopic incorporation rates and baleen growth rates: Implications for assessing diet and movement patterns in mysticetes

    Science.gov (United States)

    Busquets-Vass, Geraldine; Newsome, Seth D.; Calambokidis, John; Serra-Valente, Gabriela; Jacobsen, Jeff K.; Aguíñiga-García, Sergio; Gendron, Diane

    2017-01-01

    Stable isotope analysis in mysticete skin and baleen plates has been repeatedly used to assess diet and movement patterns. Accurate interpretation of isotope data depends on understanding isotopic incorporation rates for metabolically active tissues and growth rates for metabolically inert tissues. The aim of this research was to estimate isotopic incorporation rates in blue whale skin and baleen growth rates by using natural gradients in baseline isotope values between oceanic regions. Nitrogen (δ15N) and carbon (δ13C) isotope values of blue whale skin and potential prey were analyzed from three foraging zones (Gulf of California, California Current System, and Costa Rica Dome) in the northeast Pacific from 1996–2015. We also measured δ15N and δ13C values along the lengths of baleen plates collected from six blue whales stranded in the 1980s and 2000s. Skin was separated into three strata: basale, externum, and sloughed skin. A mean (±SD) skin isotopic incorporation rate of 163±91 days was estimated by fitting a generalized additive model of the seasonal trend in δ15N values of skin strata collected in the Gulf of California and the California Current System. A mean (±SD) baleen growth rate of 15.5±2.2 cm y-1 was estimated by using seasonal oscillations in δ15N values from three whales. These oscillations also showed that individual whales have a high fidelity to distinct foraging zones in the northeast Pacific across years. The absence of oscillations in δ15N values of baleen sub-samples from three male whales suggests these individuals remained within a specific zone for several years prior to death. δ13C values of both whale tissues (skin and baleen) and potential prey were not distinct among foraging zones. Our results highlight the importance of considering tissue isotopic incorporation and growth rates when studying migratory mysticetes and provide new insights into the individual movement strategies of blue whales. PMID:28562625

  13. Vertical instability in TCV: comparison of experimental and theoretical growth rates

    International Nuclear Information System (INIS)

    Hofmann, F.; Dutch, M.J.; Ward, D.J.; Anton, M.; Furno, I.; Lister, J.B.; Moret, J.M.

    1996-12-01

    Growth rates of the axisymmetric mode in vertically elongated plasmas in the TCV tokamak are measured and compared with numerically calculated growth rates for the reconstructed equilibria. This comparison is made over a range of discharge parameters including elongation, triangularity, and vertical position within the vacuum vessel. Growth rates increase with respect to increasing elongation, decreasing triangularity and increasing vertical distance from the top of the vacuum vessel, as expected. The agreement between the measured growth rates in the experiment and the numerically determined growth rates is excellent, in particular for the full linear MHD model which accounts for the non-rigid motion of strongly shaped plasma cross-sections. (author) 7 figs., 22 refs

  14. Nd isotopes and crustal growth rate

    International Nuclear Information System (INIS)

    Albarede, F.

    1988-01-01

    Sm/Nd isotopic constraints on crustal growth is discussed. In order to constrain Sm/Nd fractionation between continental crust and depleted mantle, an extensive data base of isotopic measurements (assumed to be adequately representative of continental crust) was compiled. The results imply that the evolution of depleted mantles was roughly linear, with no major discontinuities over the course of geologic time. This is different from other determinations of depleting mantle evolution, which show nonlinear behavior. The Sm/Nd evolution lines for continental crust and depleted mantle intersect between 3.8 to 4.0 Ga, which may indicate that the onset of continental growth was later than 4.5 Ga. A mathematical model is described, the results of which imply that time integrated crustal additions from the mantle are about 1.8 to 2.5 cu km/a, whereas crustal subtractions by sediment recycling are about 0.6 to 1.5 cu km/a. This results in a net time integrated crustal growth rate of about 1 cu km/a, which is similar to present day rates determined, for example, by Reymer and Schubert

  15. Dependent interest and transition rates in life insurance

    DEFF Research Database (Denmark)

    Buchardt, Kristian

    2014-01-01

    For market consistent life insurance liabilities modelled with a multi-state Markov chain, it is of importance to consider the interest and transition rates as stochastic processes, for example in order to consider hedging possibilities of the risks, and for risk measurement. In the literature......, this is usually done with an assumption of independence between the interest and transition rates. In this paper, it is shown how to valuate life insurance liabilities using affine processes for modelling dependent interest and transition rates. This approach leads to the introduction of so-called dependent...... forward rates. We propose a specific model for surrender modelling, and within this model the dependent forward rates are calculated, and the market value and the Solvency II capital requirement are examined for a simple savings contract....

  16. Comparing Basal Area Growth Rates in Repeated Inventories: Simpson's Paradox in Forestry

    Science.gov (United States)

    Charles E. Thomas; Bernard R. Parresol

    1989-01-01

    Recent analyses of radial growth rates in southern commercial forests have shown that current rates are lower than past rates when compared diameter class by diameter class. These results have been interpreted as an indication that the growth rate of the forest is declining. In this paper, growth rates of forest populations in Alabama are studied. Basal area growth (a...

  17. Warming, soil moisture, and loss of snow increase Bromus tectorum’s population growth rate

    Directory of Open Access Journals (Sweden)

    Aldo Compagnoni

    2014-01-01

    Full Text Available Abstract Climate change threatens to exacerbate the impacts of invasive species. In temperate ecosystems, direct effects of warming may be compounded by dramatic reductions in winter snow cover. Cheatgrass (Bromus tectorum is arguably the most destructive biological invader in basins of the North American Intermountain West, and warming could increase its performance through direct effects on demographic rates or through indirect effects mediated by loss of snow. We conducted a two-year experimental manipulation of temperature and snow pack to test whether 1 warming increases cheatgrass population growth rate and 2 reduced snow cover contributes to cheatgrass’ positive response to warming. We used infrared heaters operating continuously to create the warming treatment, but turned heaters on only during snowfalls for the snowmelt treatment. We monitored cheatgrass population growth rate and the vital rates that determine it: emergence, survival and fecundity. Growth rate increased in both warming and snowmelt treatments. The largest increases occurred in warming plots during the wettest year, indicating that the magnitude of response to warming depends on moisture availability. Warming increased both fecundity and survival, especially in the wet year, while snowmelt contributed to the positive effects of warming by increasing survival. Our results indicate that increasing temperature will exacerbate cheatgrass impacts, especially where warming causes large reductions in the depth and duration of snow cover.

  18. Multi-omics approach to study the growth efficiency and amino acid metabolism in Lactococcus lactis at various specific growth rates

    Directory of Open Access Journals (Sweden)

    Arike Liisa

    2011-02-01

    Full Text Available Abstract Background Lactococcus lactis is recognised as a safe (GRAS microorganism and has hence gained interest in numerous biotechnological approaches. As it is fastidious for several amino acids, optimization of processes which involve this organism requires a thorough understanding of its metabolic regulations during multisubstrate growth. Results Using glucose limited continuous cultivations, specific growth rate dependent metabolism of L. lactis including utilization of amino acids was studied based on extracellular metabolome, global transcriptome and proteome analysis. A new growth medium was designed with reduced amino acid concentrations to increase precision of measurements of consumption of amino acids. Consumption patterns were calculated for all 20 amino acids and measured carbon balance showed good fit of the data at all growth rates studied. It was observed that metabolism of L. lactis became more efficient with rising specific growth rate in the range 0.10 - 0.60 h-1, indicated by 30% increase in biomass yield based on glucose consumption, 50% increase in efficiency of nitrogen use for biomass synthesis, and 40% reduction in energy spilling. The latter was realized by decrease in the overall product formation and higher efficiency of incorporation of amino acids into biomass. L. lactis global transcriptome and proteome profiles showed good correlation supporting the general idea of transcription level control of bacterial metabolism, but the data indicated that substrate transport systems together with lower part of glycolysis in L. lactis were presumably under allosteric control. Conclusions The current study demonstrates advantages of the usage of strictly controlled continuous cultivation methods combined with multi-omics approach for quantitative understanding of amino acid and energy metabolism of L. lactis which is a valuable new knowledge for development of balanced growth media, gene manipulations for desired product

  19. Time-Dependent Behaviors of Granite: Loading-Rate Dependence, Creep, and Relaxation

    Science.gov (United States)

    Hashiba, K.; Fukui, K.

    2016-07-01

    To assess the long-term stability of underground structures, it is important to understand the time-dependent behaviors of rocks, such as their loading-rate dependence, creep, and relaxation. However, there have been fewer studies on crystalline rocks than on tuff, mudstone, and rock salt, because the high strength of crystalline rocks makes the detection of their time-dependent behaviors much more difficult. Moreover, studies on the relaxation, temporal change of stress and strain (TCSS) conditions, and relations between various time-dependent behaviors are scarce for not only granites, but also other rocks. In this study, previous reports on the time-dependent behaviors of granites were reviewed and various laboratory tests were conducted using Toki granite. These tests included an alternating-loading-rate test, creep test, relaxation test, and TCSS test. The results showed that the degree of time dependence of Toki granite is similar to other granites, and that the TCSS resembles the stress-relaxation curve and creep-strain curve. A viscoelastic constitutive model, proposed in a previous study, was modified to investigate the relations between the time-dependent behaviors in the pre- and post-peak regions. The modified model reproduced the stress-strain curve, creep, relaxation, and the results of the TCSS test. Based on a comparison of the results of the laboratory tests and numerical simulations, close relations between the time-dependent behaviors were revealed quantitatively.

  20. Using random walk in models specified by stochastic differential equations to determine the best expression for the bacterial growth rate

    DEFF Research Database (Denmark)

    method allows us to develop a new expression for the growth rate. The method is based on the stochastic continuous-discrete time state-space model, with a continuous-time state equation (a stochastic differential equation, SDE) combined with a discrete-time measurement equation. In our study the SDE...... described by Kristensen et. al [2]. The resulting time series allows us graphically to inspect the functional dependence of the growth rate on the substrate content. From the method described above we find three new plausible expressions for μ(S). Therefore we apply the likelihood-ratio test to compare...... for the Monod expression. Thus, the method was applied to successfully determine a significant better expression for the substrate dependent growth expression, and we find the method generally applicable for model development. References [1] Kristensen NR, Madsen H, Jørgensen, SB (2004) A method for systematic...

  1. Individual Growth Rates of Nikolsky’s Viper, Vipera berus nikolskii (Squamata, Viperidae

    Directory of Open Access Journals (Sweden)

    Bondarenko Z. S.

    2016-02-01

    Full Text Available Capture-mark-recapture data was used to infer growth rates of the Nikolsky’s viper, Vipera berus nikolskii (Vedmederja, Grubant et Rudaeva, 1986, in the Eastern Ukraine. We have found that growth rate is negatively correlated with age. The difference in growth rates before maturation is not significant between different sexes. Growth rates decrease rapidly after maturation in males and females, however adult males retain significantly higher average growth rates. There is large dispersion of growth rates in the group of adult females, which is caused, probably, by alteration of complete arrest of growth in the years with reproduction and more intensive growth in the years without it. Asymptotic snout-ventral length estimated after Von Bertalanffy model was 680 mm in females and 630 mm in males. Females mature after fifth and males mature after fourth hibernation. The larger females in vipers can not be the result of higher growth rates in females, but are the outcome of a combination of other factors including different maturation time and size (older and being larger, and, perhaps, longer life span due to lower mortality. Growth rates of the Nikolsky’s viper in the nature are higher than in other species in the group of small Eurasian vipers.

  2. BMP signaling regulates satellite cell-dependent postnatal muscle growth.

    Science.gov (United States)

    Stantzou, Amalia; Schirwis, Elija; Swist, Sandra; Alonso-Martin, Sonia; Polydorou, Ioanna; Zarrouki, Faouzi; Mouisel, Etienne; Beley, Cyriaque; Julien, Anaïs; Le Grand, Fabien; Garcia, Luis; Colnot, Céline; Birchmeier, Carmen; Braun, Thomas; Schuelke, Markus; Relaix, Frédéric; Amthor, Helge

    2017-08-01

    Postnatal growth of skeletal muscle largely depends on the expansion and differentiation of resident stem cells, the so-called satellite cells. Here, we demonstrate that postnatal satellite cells express components of the bone morphogenetic protein (BMP) signaling machinery. Overexpression of noggin in postnatal mice (to antagonize BMP ligands), satellite cell-specific knockout of Alk3 (the gene encoding the BMP transmembrane receptor) or overexpression of inhibitory SMAD6 decreased satellite cell proliferation and accretion during myofiber growth, and ultimately retarded muscle growth. Moreover, reduced BMP signaling diminished the adult satellite cell pool. Abrogation of BMP signaling in satellite cell-derived primary myoblasts strongly diminished cell proliferation and upregulated the expression of cell cycle inhibitors p21 and p57 In conclusion, these results show that BMP signaling defines postnatal muscle development by regulating satellite cell-dependent myofiber growth and the generation of the adult muscle stem cell pool. © 2017. Published by The Company of Biologists Ltd.

  3. Differences in proleptic and epicormic shoot structures in relation to water deficit and growth rate in almond trees (Prunus dulcis).

    Science.gov (United States)

    Negrón, Claudia; Contador, Loreto; Lampinen, Bruce D; Metcalf, Samuel G; Guédon, Yann; Costes, Evelyne; DeJong, Theodore M

    2014-02-01

    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. 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. 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. 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 a more rapid progression through ontogenetic states.

  4. DRG axon elongation and growth cone collapse rate induced by Sema3A are differently dependent on NGF concentration.

    Science.gov (United States)

    Kaselis, Andrius; Treinys, Rimantas; Vosyliūtė, Rūta; Šatkauskas, Saulius

    2014-03-01

    Regeneration of embryonic and adult dorsal root ganglion (DRG) sensory axons is highly impeded when they encounter neuronal growth cone-collapsing factor semaphorin3A (Sema3A). On the other hand, increasing evidence shows that DRG axon's regeneration can be stimulated by nerve growth factor (NGF). In this study, we aimed to evaluate whether increased NGF concentrations can counterweight Sema3A-induced inhibitory responses in 15-day-old mouse embryo (E15) DRG axons. The DRG explants were grown in Neurobasal-based medium with different NGF concentrations ranging from 0 to 100 ng/mL and then treated with Sema3A at constant 10 ng/mL concentration. To evaluate interplay between NGF and Sema3A number of DRG axons, axon outgrowth distance and collapse rate were measured. We found that the increased NGF concentrations abolish Sema3A-induced inhibitory effect on axon outgrowth, while they have no effect on Sema3A-induced collapse rate.

  5. Growth and carbon fixation rate of calcareous algae cricosphaera carterae. Sekkaiso cricosphaera carterae no zoshoku to tanso kotei sokudo

    Energy Technology Data Exchange (ETDEWEB)

    Seki, M; Furusaki, S [The University of Tokyo, Tokyo (Japan). Faculty of Engineering; Shigematsu, K [Sumitomo Chemical Co. Ltd., Osaka (Japan); Shigeta, K [Kanagawa Prefectural Office, Yokohama (Japan)

    1993-09-10

    Notice has been given on a calcareous alga among micro marine algae that play an important role in carbon circulation, and the representative alga, Cricosphaera carterae was cultured to discuss growth and carbon fixation rate experimentally. It was found that nutrient salt is taken in more actively in the bright period during which no fission occurs, and less actively during the growth stage in the dark period. Dependence of nitrate concentration on specific growth rate was measured with semi-continuous culture and two formulas were formulated. The specific growth rate was 0.53/d at an average nitrogen concentration on the ocean surface of 15 mg/m[sup 3]. The maximum specific growth rate was 0.9/d, and the fixing ratio of inorganic carbon to organic carbon was roughly 0.1. Further, the alga was cultured with CO2 concentration doubled (to 715 ppm), where no large difference was discovered in the growth and the inorganic carbon fixation. From these findings, the carbon fixation amount due to algae on the entire earth was calculated to roughly 4 billion tons per year. 23 refs., 10 figs., 4 tabs.

  6. Effect of feeding frequency and feeding rate on growth of ...

    African Journals Online (AJOL)

    Effect of feeding frequency and feeding rate on growth of Oreochromis mossambicus (Teleostei: Cichlidae) fry. ... Weight gain, specific growth rate and gross food conversion ratio were significantly affected by ... AJOL African Journals Online.

  7. Metal-to-Insulator Transition in Anatase TiO2 Thin Films Induced by Growth Rate Modulation

    Energy Technology Data Exchange (ETDEWEB)

    Tachikawa, T; Minohara, M.; Nakanishi, Y.; Hikita, Y.; Yoshita, M.; Akiyama, H.; Bell, C.; Hwang, H.Y.

    2012-06-21

    We demonstrate control of the carrier density of single phase anatase TiO{sub 2} thin films by nearly two orders of magnitude by modulating the growth kinetics during pulsed laser deposition, under fixed thermodynamic conditions. The resistivity and the intensity of the photoluminescence spectra of these TiO{sub 2} samples, both of which correlate with the number of oxygen vacancies, are shown to depend strongly on the growth rate. A quantitative model is used to explain the carrier density changes.

  8. Metal-to-Insulator Transition in Anatase TiO2 Thin Films Induced by Growth Rate Modulation

    International Nuclear Information System (INIS)

    Tachikawa, Takashi

    2012-01-01

    We demonstrate control of the carrier density of single phase anatase TiO 2 thin films by nearly two orders of magnitude by modulating the growth kinetics during pulsed laser deposition, under fixed thermodynamic conditions. The resistivity and the intensity of the photoluminescence spectra of these TiO 2 samples, both of which correlate with the number of oxygen vacancies, are shown to depend strongly on the growth rate. A quantitative model is used to explain the carrier density changes.

  9. Growth changes in plaice, cod, haddock and saithe in the North Sea: a comparison of (post-)medieval and present-day growth rates based on otolith measurements

    Science.gov (United States)

    Bolle, Loes J.; Rijnsdorp, Adriaan D.; van Neer, Wim; Millner, Richard S.; van Leeuwen, Piet I.; Ervynck, Anton; Ayers, Richard; Ongenae, Ellen

    2004-05-01

    Fishing effort has strongly increased in the North Sea since the mid-19th century, causing a substantial reduction in the population size of exploited fish stocks. As fisheries research has developed simultaneously with the industrialisation of the fisheries, our knowledge of population dynamics at low levels of exploitations is limited. Otoliths retrieved from archaeological excavations offer a unique opportunity to study growth rates in the past. This study compares historical and present-day growth rates for four commercially important demersal fish species. A total of 2532 modern otoliths (AD 1984-1999) and 1286 historical otoliths (AD 1200-1925) obtained from archaeological excavations in Belgium and Scotland were analysed. Comparison of the growth patterns between eras revealed a major increase in growth rate of haddock, whereas growth changes were not observed in saithe and only in the smaller size classes of plaice and cod. Comparison of our results with literature data indicates that the observed growth rate changes in plaice and cod occurred within the 20th century. Apparently the onset of industrialised fisheries has not greatly affected the growth of plaice, cod and saithe populations in the North Sea. This result contradicts the expectation of density-dependent limitation of growth during the era of pre-industrialised fishing, but is in agreement with the concentration hypothesis of Beverton (Neth. J. Sea Res. 34 (1995) 1) stating that species which concentrate spatially into nursery grounds during their early life-history may 'saturate' the carrying capacity of the juvenile habitat even though the adult part of the population is not limited by the adult habitat.

  10. Growth rates of breeder reactor fuel. Final report

    International Nuclear Information System (INIS)

    Ott, K.O.

    1979-01-01

    During the contract period, a consistent formalism for the definition of the growth rates (and thus the doubling time) of breeder reactor fuel has been developed. This formalism was then extended to symbiotic operation of breeder and converter reactors. Further, an estimation prescription for the growth rate has been developed which is based upon the breeding worth factors. The characteristics of this definition have been investigated, which led to an additional integral concept, the breeding bonus

  11. Effects of lowered pH on marine phytoplankton growth rates

    DEFF Research Database (Denmark)

    Berge, Terje; Daugbjerg, Niels; Andersen, Betinna Balling

    2010-01-01

    concentration of seawater. Ocean acidification may potentially both stimulate and reduce primary production by marine phytoplankton. Data are scarce on the response of marine phytoplankton growth rates to lowered pH/increased CO2. Using the acid addition method to lower the seawater pH and manipulate...... the carbonate system, we determined in detail the lower pH limit for growth rates of 2 model species of common marine phytoplankton. We also tested whether growth and production rates of 6 other common species of phytoplankton were affected by ocean acidification (lowered to pH 7.0). The lower pH limits...... statistically similar in the pH range of ~7.0 to 8.5. Our results and literature reports on growth at lowered pH indicate that marine phytoplankton in general are resistant to climate change in terms of ocean acidification, and do not increase or decrease their growth rates according to ecological relevant...

  12. Neutrino masses, scale-dependent growth, and redshift-space distortions

    Energy Technology Data Exchange (ETDEWEB)

    Hernández, Oscar F., E-mail: oscarh@physics.mcgill.ca [Marianopolis College, 4873 Westmount Ave., Westmount, QC H3Y 1X9 (Canada)

    2017-06-01

    Massive neutrinos leave a unique signature in the large scale clustering of matter. We investigate the wavenumber dependence of the growth factor arising from neutrino masses and use a Fisher analysis to determine the aspects of a galaxy survey needed to measure this scale dependence.

  13. Modification of cell growth rate by irradiation

    International Nuclear Information System (INIS)

    Itoh, Hisao; Takemasa, Kazuhiko; Nishiguchi, Iku; Ka, Wei-Jei; Kutsuki, Shoji; Hashimoto, Shozo

    1993-01-01

    The effect of irradiation on the proliferation kinetics of the monolayer cells has been studied. Two human cell lines with different doubling times (HeLa-P and RMUG) and two clones that have the same radiosensitivity but different doubling times (HeLa-R and HeLa-S) were irradiated with a daily dose of 2 Gy for 6 days. The number of the clonogenic cells/dish was calculated by multiplying the number of total cell/dish by the survival fraction. In the rapidly growing cells (HeLa-P, HeLa-R), the number of the clonogenic cells was not decreased by the first two fractionated irradiations, but decreased thereafter at a similar rate as by single-dose fractionation, whereas the clonogenic cell number decreased from the first fractionated irradiation in the slowly growing cells (RMUG, HeLa-S). When the proliferation of clonogenic cell number increased along with a similar growth rates that was seen in all other types of cells. Further, no correlation was seen between the growth rates of cells without irradiation and cells that received irradiation. This latter result suggests that the slow growth rate of non-irradiated cells may not be the predictive factor of the tumor cure and the interruption of radiotherapy may reduce the beneficial effect of this treatment even in slow growing tumors. (author)

  14. Time-dependent crack growth in steam generator tube leakage

    International Nuclear Information System (INIS)

    Chung, H.D.; Lee, J.H.; Park, Y.W.; Choi, Y.H.

    2006-01-01

    In general, cracks found in steam generator tubes have semi-elliptical shapes and it is assumed to be rectangular shape for conservatism after crack penetration. Hence, the leak and crack growth behavior has not been clearly understood after the elliptical crack penetrates the tube wall. Several experimental results performed by Argonne Nation Laboratory exhibited time-dependent crack growth behavior of rectangular flaws as well as trapezoidal flaws under constant pressure. The crack growth faster than expected was observed in both cases, which is likely attributed to time-dependent crack growth accompanied by fatigue sources such as the interaction between active jet and crack. The stress intensity factor, K 1 , is necessary for the prediction of the observed fatigue crack growth behavior. However, no K 1 solution is available for a trapezoidal flaw. The objective of this study is to develop the stress intensity factor which can be used for the fatigue analysis of a trapezoidal crack. To simplify the analysis, the crack is assumed to be a symmetric trapezoidal shape. A new K 1 formula for axial trapezoidal through-wall cracks was proposed based on the FEM results. (author)

  15. Influence of deposition parameters on the refractive index and growth rate of diamond-like carbon films

    International Nuclear Information System (INIS)

    Zhang, G.F.; Zheng, X.; Guo, L.J.; Liu, Z.T.; Xiu, N.K.

    1994-01-01

    In order to use diamond-like carbon (DLC) films as protective and antireflection coatings for IR optical materials exposed to hostile environments, an investigation has been systematically conducted on the influence of the deposition parameters on the refractive index and growth rate of DLC films, which are two of the most important parameters in evaluating optical characteristics of antireflection coatings. The experimental results show that both the refractive index and growth rate of DLC films depend strongly on the negative d.c. bias voltage. The refractive index increases with increasing bias voltage and decreases with increasing partial pressure of the hydrocarbon gas and total flow rate of the mixture. The growth rate increases greatly when the bias voltage is larger than a threshold value. The various parameters which influence the structure and properties of DLC films are interrelated. Fourier transform IR spectroscopy results show that the strength of the C-H stretching absorption band in the range 3300-2850 cm -1 is gradually weakened with increasing negative bias voltage and argon concentration. High energy bombardment of the growing film plays an important role in the structure and hence the properties of DLC films. (orig.)

  16. Analytic solutions for Rayleigh-Taylor growth rates in smooth density gradients

    International Nuclear Information System (INIS)

    Munro, D.H.

    1988-01-01

    The growth rate of perturbations on the shell of a laser fusion target can be estimated as √gk , where g is the shell acceleration and k is the transverse wave number of the perturbation. This formula overestimates the growth rate, and should be modified for the effects of density gradients and/or ablation of the unstable interface. The density-gradient effect is explored here analytically. With the use of variational calculus to explore all possible density profiles, the growth rate is shown to exceed √gk/(1+kL) , where L is a typical density-gradient scale length. Density profiles actually exhibiting this minimum growth rate are found

  17. Modeling of scale-dependent bacterial growth by chemical kinetics approach.

    Science.gov (United States)

    Martínez, Haydee; Sánchez, Joaquín; Cruz, José-Manuel; Ayala, Guadalupe; Rivera, Marco; Buhse, Thomas

    2014-01-01

    We applied the so-called chemical kinetics approach to complex bacterial growth patterns that were dependent on the liquid-surface-area-to-volume ratio (SA/V) of the bacterial cultures. The kinetic modeling was based on current experimental knowledge in terms of autocatalytic bacterial growth, its inhibition by the metabolite CO2, and the relief of inhibition through the physical escape of the inhibitor. The model quantitatively reproduces kinetic data of SA/V-dependent bacterial growth and can discriminate between differences in the growth dynamics of enteropathogenic E. coli, E. coli JM83, and Salmonella typhimurium on one hand and Vibrio cholerae on the other hand. Furthermore, the data fitting procedures allowed predictions about the velocities of the involved key processes and the potential behavior in an open-flow bacterial chemostat, revealing an oscillatory approach to the stationary states.

  18. Modeling of Scale-Dependent Bacterial Growth by Chemical Kinetics Approach

    Directory of Open Access Journals (Sweden)

    Haydee Martínez

    2014-01-01

    Full Text Available We applied the so-called chemical kinetics approach to complex bacterial growth patterns that were dependent on the liquid-surface-area-to-volume ratio (SA/V of the bacterial cultures. The kinetic modeling was based on current experimental knowledge in terms of autocatalytic bacterial growth, its inhibition by the metabolite CO2, and the relief of inhibition through the physical escape of the inhibitor. The model quantitatively reproduces kinetic data of SA/V-dependent bacterial growth and can discriminate between differences in the growth dynamics of enteropathogenic E. coli, E. coli  JM83, and Salmonella typhimurium on one hand and Vibrio cholerae on the other hand. Furthermore, the data fitting procedures allowed predictions about the velocities of the involved key processes and the potential behavior in an open-flow bacterial chemostat, revealing an oscillatory approach to the stationary states.

  19. The temperature dependence and environmental enhancement mechanism of fatigue crack growth rates of A 351-CF8A cast stainless steel in LWR environment

    International Nuclear Information System (INIS)

    Cullen, W.H.; Haenninen, H.; Toerroenen, K.; Kemppainen, M.

    1984-01-01

    The fatigue crack growth rates for A 351-CF8A cast stainless steel were determined over a range of temperatures from 93 degC to 338 degC (200 degF to 640 degF). The waveform was 17 mHz sinusoidal and the load ratio was 0.2. The environment was borated and lithiated water with a dissolved oxygen content of approximately 1 ppb. The results show an easily measurable (factors of 2 to 8) increase in crack growth rates due to the environment. However, these rates are well within the known band of results for low-alloy pressure vessel and low-carbon piping steels in LWR environments. An extensive fractographic investigation shows fatigue fracture surfaces consisting of brittle morphology. This fracture morphology is similar to that of stress corrosion cracking of stainless steels, suggesting that there is a distinctive environmental assistance mechanism resulting in the increased crack growth rates. (author)

  20. Dependence of N-polar GaN rod morphology on growth parameters during selective area growth by MOVPE

    Science.gov (United States)

    Li, Shunfeng; Wang, Xue; Mohajerani, Matin Sadat; Fündling, Sönke; Erenburg, Milena; Wei, Jiandong; Wehmann, Hergo-Heinrich; Waag, Andreas; Mandl, Martin; Bergbauer, Werner; Strassburg, Martin

    2013-02-01

    Selective area growth of GaN rods by metalorganic vapor phase epitaxy has attracted great interest due to its novel applications in optoelectronic and photonics. In this work, we will present the dependence of GaN rod morphology on various growth parameters i.e. growth temperature, H2/N2 carrier gas concentration, V/III ratio, total carrier gas flow and reactor pressure. It is found that higher growth temperature helps to increase the aspect ratio of the rods, but reduces the height homogeneity. Furthermore, H2/N2 carrier gas concentration is found to be a critical factor to obtain vertical rod growth. Pure nitrogen carrier gas leads to irregular growth of GaN structure, while an increase of hydrogen carrier gas results in vertical GaN rod growth. Higher hydrogen carrier gas concentration also reduces the diameter and enhances the aspect of the GaN rods. Besides, increase of V/III ratio causes reduction of the aspect ratio of N-polar GaN rods, which could be explained by the relatively lower growth rate on (000-1) N-polar top surface when supplying more ammonia. In addition, an increase of the total carrier gas flow leads to a decrease in the diameter and the average volume of GaN rods. These phenomena are tentatively explained by the change of partial pressure of the source materials and boundary layer thickness in the reactor. Finally, it is shown that the average volume of the N-polar GaN rods keeps a similar value for a reactor pressure PR of 66 and 125 mbar, while an incomplete filling of the pattern opening is observed with PR of 250 mbar. Room temperature photoluminescence spectrum of the rods is also briefly discussed.

  1. Modelling of tomato stem diameter growth rate based on physiological responses

    International Nuclear Information System (INIS)

    Li, L.; Tan, J.; Lv, T.

    2017-01-01

    The stem diameter is an important parameter describing the growth of tomato plant during vegetative growth stage. A stem diameter growth model was developed to predict the response of plant growth under different conditions. By analyzing the diurnal variations of stem diameter in tomato (Solanum lycopersicum L.), it was found that the stem diameter measured at 3:00 am was the representative value as the daily basis of tomato stem diameter. Based on the responses of growth rate in stem diameter to light and temperature, a linear regression relationship was applied to establish the stem diameter growth rate prediction model for the vegetative growth stage in tomato and which was further validated by experiment. The root mean square error (RMSE) and relative error (RE) were used to test the correlation between measured and modeled stem diameter variations. Results showed that the model can be used in prediction for stem diameter growth rate at vegetative growth stage in tomato. (author)

  2. Linear growth of the entanglement entropy and the Kolmogorov-Sinai rate

    Science.gov (United States)

    Bianchi, Eugenio; Hackl, Lucas; Yokomizo, Nelson

    2018-03-01

    The rate of entropy production in a classical dynamical system is characterized by the Kolmogorov-Sinai entropy rate h KS given by the sum of all positive Lyapunov exponents of the system. We prove a quantum version of this result valid for bosonic systems with unstable quadratic Hamiltonian. The derivation takes into account the case of time-dependent Hamiltonians with Floquet instabilities. We show that the entanglement entropy S A of a Gaussian state grows linearly for large times in unstable systems, with a rate Λ A ≤ h KS determined by the Lyapunov exponents and the choice of the subsystem A. We apply our results to the analysis of entanglement production in unstable quadratic potentials and due to periodic quantum quenches in many-body quantum systems. Our results are relevant for quantum field theory, for which we present three applications: a scalar field in a symmetry-breaking potential, parametric resonance during post-inflationary reheating and cosmological perturbations during inflation. Finally, we conjecture that the same rate Λ A appears in the entanglement growth of chaotic quantum systems prepared in a semiclassical state.

  3. Growth rates of Porites astreoides and Orbicella franksi in mesophotic habitats surrounding St. Thomas, US Virgin Islands

    Science.gov (United States)

    Groves, Sarah H.; Holstein, Daniel M.; Enochs, Ian C.; Kolodzeij, Graham; Manzello, Derek P.; Brandt, Marilyn E.; Smith, Tyler B.

    2018-06-01

    Mesophotic coral ecosystems (MCEs) are deep (> 30 m), light-dependent communities that are abundant in many parts of the global ocean. MCEs are potentially connected to shallow reefs via larval exchange and may act as refuges for reef organisms. However, MCE community level recovery after disturbance, and thus, community resilience, are poorly understood components of their capacity as refuges. To assess the potential for disturbance and growth to drive community structure on MCEs with differential biophysical conditions and coral communities, we collected colonies of Orbicella franksi and Porites astreoides and used computerized tomography to quantify calcification. The divergence of coral growth rates in MCEs with different environmental conditions may be species specific; habitat-forming O. franksi have slow and consistent growth rates of 0.2 cm yr-1 below 30 m, regardless of mesophotic habitat, compared to 1.0 cm yr-1 in shallow-water habitats. Slow skeletal growth rates in MCEs suggest that rates of recovery from disturbance will likely also be slow. Localized buffering of MCEs from the stressors affecting shallow reefs is therefore crucial to the long-term capacity of these sites to serve as refugia, given that skeletal extension and recovery from disturbance in MCEs will be significantly slower than on shallow reefs.

  4. Growth rate correlates negatively with protein turnover in Arabidopsis accessions.

    Science.gov (United States)

    Ishihara, Hirofumi; Moraes, Thiago Alexandre; Pyl, Eva-Theresa; Schulze, Waltraud X; Obata, Toshihiro; Scheffel, André; Fernie, Alisdair R; Sulpice, Ronan; Stitt, Mark

    2017-08-01

    Previous studies with Arabidopsis accessions revealed that biomass correlates negatively to dusk starch content and total protein, and positively to the maximum activities of enzymes in photosynthesis. We hypothesized that large accessions have lower ribosome abundance and lower rates of protein synthesis, and that this is compensated by lower rates of protein degradation. This would increase growth efficiency and allow more investment in photosynthetic machinery. We analysed ribosome abundance and polysome loading in 19 accessions, modelled the rates of protein synthesis and compared them with the observed rate of growth. Large accessions contained less ribosomes than small accessions, due mainly to cytosolic ribosome abundance falling at night in large accessions. The modelled rates of protein synthesis resembled those required for growth in large accessions, but were up to 30% in excess in small accessions. We then employed 13 CO 2 pulse-chase labelling to measure the rates of protein synthesis and degradation in 13 accessions. Small accessions had a slightly higher rate of protein synthesis and much higher rates of protein degradation than large accessions. Protein turnover was negligible in large accessions but equivalent to up to 30% of synthesised protein day -1 in small accessions. We discuss to what extent the decrease in growth in small accessions can be quantitatively explained by known costs of protein turnover and what factors may lead to the altered diurnal dynamics and increase of ribosome abundance in small accessions, and propose that there is a trade-off between protein turnover and maximisation of growth rate. © 2017 The Authors The Plant Journal © 2017 John Wiley & Sons Ltd.

  5. Effect of Microstructure on Time Dependent Fatigue Crack Growth Behavior In a P/M Turbine Disk Alloy

    Science.gov (United States)

    Telesman, Ignacy J.; Gabb, T. P.; Bonacuse, P.; Gayda, J.

    2008-01-01

    A study was conducted to determine the processes which govern hold time crack growth behavior in the LSHR disk P/M superalloy. Nineteen different heat treatments of this alloy were evaluated by systematically controlling the cooling rate from the supersolvus solutioning step and applying various single and double step aging treatments. The resulting hold time crack growth rates varied by more than two orders of magnitude. It was shown that the associated stress relaxation behavior for these heat treatments was closely correlated with the crack growth behavior. As stress relaxation increased, the hold time crack growth resistance was also increased. The size of the tertiary gamma' in the general microstructure was found to be the key microstructural variable controlling both the hold time crack growth behavior and stress relaxation. No relationship between the presence of grain boundary M23C6 carbides and hold time crack growth was identified which further brings into question the importance of the grain boundary phases in determining hold time crack growth behavior. The linear elastic fracture mechanics parameter, Kmax, is unable to account for visco-plastic redistribution of the crack tip stress field during hold times and thus is inadequate for correlating time dependent crack growth data. A novel methodology was developed which captures the intrinsic crack driving force and was able to collapse hold time crack growth data onto a single curve.

  6. Strain-rate dependent plasticity in thermo-mechanical transient analysis

    International Nuclear Information System (INIS)

    Rashid, Y.R.; Sharabi, M.N.

    1980-01-01

    The thermo-mechanical transient behavior of fuel element cladding and other reactor components is generally governed by the strain-rate properties of the material. Relevant constitutive modeling requires extensive material data in the form of strain-rate response as function of true-stress, temperature, time and environmental conditions, which can then be fitted within a theoretical framework of an inelastic constitutive model. In this paper, we present a constitutive formulation that deals continuously with the entire strain-rate range and has the desirable advantage of utilizing existing material data. The derivation makes use of strain-rate sensitive stress-strain curve and strain-rate dependent yield surface. By postulating a strain-rate dependent on Mises yield function and a strain-rate dependent kinematic hardening rule, we are able to derive incremental stress-strain relations that describe the strain-rate behavior in the entire deformation range spanning high strain-rate plasticity and creep. The model is sufficiently general as to apply to any materials and loading histories for which data is available. (orig.)

  7. Investigating calcite growth rates using a quartz crystal microbalance with dissipation (QCM-D)

    Science.gov (United States)

    Cao, Bo; Stack, Andrew G.; Steefel, Carl I.; DePaolo, Donald J.; Lammers, Laura N.; Hu, Yandi

    2018-02-01

    Calcite precipitation plays a significant role in processes such as geological carbon sequestration and toxic metal sequestration and, yet, the rates and mechanisms of calcite growth under close to equilibrium conditions are far from well understood. In this study, a quartz crystal microbalance with dissipation (QCM-D) was used for the first time to measure macroscopic calcite growth rates. Calcite seed crystals were first nucleated and grown on sensors, then growth rates of calcite seed crystals were measured in real-time under close to equilibrium conditions (saturation index, SI = log ({Ca2+}/{CO32-}/Ksp) = 0.01-0.7, where {i} represent ion activities and Ksp = 10-8.48 is the calcite thermodynamic solubility constant). At the end of the experiments, total masses of calcite crystals on sensors measured by QCM-D and inductively coupled plasma mass spectrometry (ICP-MS) were consistent, validating the QCM-D measurements. Calcite growth rates measured by QCM-D were compared with reported macroscopic growth rates measured with auto-titration, ICP-MS, and microbalance. Calcite growth rates measured by QCM-D were also compared with microscopic growth rates measured by atomic force microscopy (AFM) and with rates predicted by two process-based crystal growth models. The discrepancies in growth rates among AFM measurements and model predictions appear to mainly arise from differences in step densities, and the step velocities were consistent among the AFM measurements as well as with both model predictions. Using the predicted steady-state step velocity and the measured step densities, both models predict well the growth rates measured using QCM-D and AFM. This study provides valuable insights into the effects of reactive site densities on calcite growth rate, which may help design future growth models to predict transient-state step densities.

  8. Growth rates of alien Oreochromis niloticus and indigenous ...

    African Journals Online (AJOL)

    Growth rates of indigenous Oreochromis mortimeri and alien Oreochromis niloticus from Lake Kariba were estimated from samples collected in 1997–2000, 2003–2005 and 2010–2011. Growth zones on scales and otoliths of O. niloticus and on the otoliths and opercula of O. mortimeri were deposited annually.

  9. Microzooplankton growth rates examined across a temperature gradient in the Barents Sea.

    Science.gov (United States)

    Franzè, Gayantonia; Lavrentyev, Peter J

    2014-01-01

    Growth rates (µ) of abundant microzooplankton species were examined in field experiments conducted at ambient sea temperatures (-1.8-9.0°C) in the Barents Sea and adjacent waters (70-78.5°N). The maximum species-specific µ of ciliates and athecate dinoflagellates (0.33-1.67 d(-1) and 0.52-1.14 d(-1), respectively) occurred at temperatures below 5°C and exceeded the µmax predicted by previously published, laboratory culture-derived equations. The opposite trend was found for thecate dinoflagellates, which grew faster in the warmer Atlantic Ocean water. Mixotrophic ciliates and dinoflagellates grew faster than their heterotrophic counterparts. At sub-zero temperatures, microzooplankton µmax matched those predicted for phytoplankton by temperature-dependent growth equations. These results indicate that microzooplankton protists may be as adapted to extreme Arctic conditions as their algal prey.

  10. Fatigue Crack Growth Rate and Stress-Intensity Factor Corrections for Out-of-Plane Crack Growth

    Science.gov (United States)

    Forth, Scott C.; Herman, Dave J.; James, Mark A.

    2003-01-01

    Fatigue crack growth rate testing is performed by automated data collection systems that assume straight crack growth in the plane of symmetry and use standard polynomial solutions to compute crack length and stress-intensity factors from compliance or potential drop measurements. Visual measurements used to correct the collected data typically include only the horizontal crack length, which for cracks that propagate out-of-plane, under-estimates the crack growth rates and over-estimates the stress-intensity factors. The authors have devised an approach for correcting both the crack growth rates and stress-intensity factors based on two-dimensional mixed mode-I/II finite element analysis (FEA). The approach is used to correct out-of-plane data for 7050-T7451 and 2025-T6 aluminum alloys. Results indicate the correction process works well for high DeltaK levels but fails to capture the mixed-mode effects at DeltaK levels approaching threshold (da/dN approximately 10(exp -10) meter/cycle).

  11. Dependency of Shear Strength on Test Rate in SiC/BSAS Ceramic Matrix Composite at Elevated Temperature

    Science.gov (United States)

    Choi, Sung R.; Bansal, Narottam P.; Gyekenyesi, John P.

    2003-01-01

    Both interlaminar and in-plane shear strengths of a unidirectional Hi-Nicalon(TM) fiber-reinforced barium strontium aluminosilicate (SiC/BSAS) composite were determined at 1100 C in air as a function of test rate using double notch shear test specimens. The composite exhibited a significant effect of test rate on shear strength, regardless of orientation which was either in interlaminar or in in-plane direction, resulting in an appreciable shear-strength degradation of about 50 percent as test rate decreased from 3.3 10(exp -1) mm/s to 3.3 10(exp -5) mm/s. The rate dependency of composite's shear strength was very similar to that of ultimate tensile strength at 1100 C observed in a similar composite (2-D SiC/BSAS) in which tensile strength decreased by about 60 percent when test rate varied from the highest (5 MPa/s) to the lowest (0.005 MPa/s). A phenomenological, power-law slow crack growth formulation was proposed and formulated to account for the rate dependency of shear strength of the composite.

  12. Growth rates, grazing, sinking, and iron limitation of equatorial Pacific phytoplankton

    International Nuclear Information System (INIS)

    Chavez, F.P.; Buck, K.R.; Coale, K.H.; Martin, J.H.; DiTullio, G.R.; Welschmeyer, N.A.; Barber, R.T.; Jacobson, A.C.

    1991-01-01

    Concentrations of phytoplankton and NO 3 are consistently low and high in surface waters of the oceanic eastern and central equatorial Pacific, and phytoplankton populations are dominated by small solitary phytoplankton. Growth rates of natural phytoplankton populations, needed to assess the relative importance of many of the processes considered in the equatorial Pacific, were estimated by several methods. The growth rates of natural phytoplankton populations were found to be ∼0.7 d -1 or 1 biomass doubling d -1 and were similar for all methods. To keep this system in its observed balance requires that loss rates approximate observed growth rates. Grazing rates, measured with a dilution grazing experiment, were high, accounting for a large fraction of the daily production. Additions of various forms of Fe to 5-7-d incubations utilizing ultraclean techniques resulted in significant shifts in autotrophic and heterotrophic assemblages between initial samples, controls, and Fe enrichments, which were presumably due to Fe, grazing by both protistan and metazoan components, and incubation artifacts. Estimated growth rates of small pennate diatoms showed increases in Fe enrichments with respect to controls. The growth rates of the pennate diatoms were similar to those estimated for the larger size fraction of the natural populations

  13. Sales Growth Rate Forecasting Using Improved PSO and SVM

    Directory of Open Access Journals (Sweden)

    Xibin Wang

    2014-01-01

    Full Text Available Accurate forecast of the sales growth rate plays a decisive role in determining the amount of advertising investment. In this study, we present a preclassification and later regression based method optimized by improved particle swarm optimization (IPSO for sales growth rate forecasting. We use support vector machine (SVM as a classification model. The nonlinear relationship in sales growth rate forecasting is efficiently represented by SVM, while IPSO is optimizing the training parameters of SVM. IPSO addresses issues of traditional PSO, such as relapsing into local optimum, slow convergence speed, and low convergence precision in the later evolution. We performed two experiments; firstly, three classic benchmark functions are used to verify the validity of the IPSO algorithm against PSO. Having shown IPSO outperform PSO in convergence speed, precision, and escaping local optima, in our second experiment, we apply IPSO to the proposed model. The sales growth rate forecasting cases are used to testify the forecasting performance of proposed model. According to the requirements and industry knowledge, the sample data was first classified to obtain types of the test samples. Next, the values of the test samples were forecast using the SVM regression algorithm. The experimental results demonstrate that the proposed model has good forecasting performance.

  14. Do fish growth rates correlate with PCB body burdens?

    Science.gov (United States)

    Andrew L. Rypel; David R.. Bayne

    2010-01-01

    We evaluated whether growth rates of six fish species correlated with PCB concentrations in a moderately-to-heavily polluted freshwater ecosystem. Using a large dataset (n ¼ 984 individuals), and after accounting for growth effects related to fish age, habitat, sex, and lipids, growth correlated significantly, but positively with lipid-corrected PCB concentrations for...

  15. On the growth rate of the foliicolous lichen Strigula elegans

    NARCIS (Netherlands)

    Wilde-Duyfjes, de B.E.E.

    1967-01-01

    The diametral growth rate of the foliicolous lichen Strigula elegans (Fée) Müll. Arg., measured under natural conditions in the African tropical rainforest, has been established to amount to (0.7-)3-3-6(-8) mm annually. As compared to the diametral growth rate of lichens from temperate regions,

  16. Pretreatment Growth Rate Predicts Radiation Response in Vestibular Schwannomas

    International Nuclear Information System (INIS)

    Niu, Nina N.; Niemierko, Andrzej; Larvie, Mykol; Curtin, Hugh; Loeffler, Jay S.; McKenna, Michael J.; Shih, Helen A.

    2014-01-01

    Purpose: Vestibular schwannomas (VS) are often followed without initial therapeutic intervention because many tumors do not grow and radiation therapy is associated with potential adverse effects. In an effort to determine whether maximizing initial surveillance predicts for later treatment response, the predictive value of preirradiation growth rate of VS on response to radiation therapy was assessed. Methods and Materials: Sixty-four patients with 65 VS were treated with single-fraction stereotactic radiation surgery or fractionated stereotactic radiation therapy. Pre- and postirradiation linear expansion rates were estimated using volumetric measurements on sequential magnetic resonance images (MRIs). In addition, postirradiation tumor volume change was classified as demonstrating shrinkage (ratio of volume on last follow-up MRI to MRI immediately preceding irradiation <80%), stability (ratio 80%-120%), or expansion (ratio >120%). The median pre- and postirradiation follow-up was 20.0 and 27.5 months, respectively. Seven tumors from neurofibromatosis type 2 (NF2) patients were excluded from statistical analyses. Results: In the 58 non-NF2 patients, there was a trend of correlation between pre- and postirradiation volume change rates (slope on linear regression, 0.29; P=.06). Tumors demonstrating postirradiation expansion had a median preirradiation growth rate of 89%/year, and those without postirradiation expansion had a median preirradiation growth rate of 41%/year (P=.02). As the preirradiation growth rate increased, the probability of postirradiation expansion also increased. Overall, 24.1% of tumors were stable, 53.4% experienced shrinkage, and 22.5% experienced expansion. Predictors of no postirradiation tumor expansion included no prior surgery (P=.01) and slower tumor growth rate (P=.02). The control of tumors in NF2 patients was only 43%. Conclusions: Radiation therapy is an effective treatment for VS, but tumors that grow quickly preirradiation may be

  17. Pretreatment Growth Rate Predicts Radiation Response in Vestibular Schwannomas

    Energy Technology Data Exchange (ETDEWEB)

    Niu, Nina N. [Department of Radiation Oncology, Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts (United States); Harvard Medical School, Department of Medicine, Brigham and Women' s Hospital, Boston, Massachusetts (United States); Niemierko, Andrzej [Department of Radiation Oncology, Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts (United States); Larvie, Mykol [Harvard Medical School, Department of Radiology, Massachusetts General Hospital, Boston, Massachusetts (United States); Curtin, Hugh [Harvard Medical School, Department of Radiology, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts (United States); Loeffler, Jay S. [Department of Radiation Oncology, Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts (United States); McKenna, Michael J. [Harvard Medical School, Department of Otolaryngology, Massachusetts Eye and Ear Infirmary, Boston, Massachusetts (United States); Shih, Helen A., E-mail: hshih@partners.org [Department of Radiation Oncology, Harvard Medical School, Massachusetts General Hospital, Boston, Massachusetts (United States)

    2014-05-01

    Purpose: Vestibular schwannomas (VS) are often followed without initial therapeutic intervention because many tumors do not grow and radiation therapy is associated with potential adverse effects. In an effort to determine whether maximizing initial surveillance predicts for later treatment response, the predictive value of preirradiation growth rate of VS on response to radiation therapy was assessed. Methods and Materials: Sixty-four patients with 65 VS were treated with single-fraction stereotactic radiation surgery or fractionated stereotactic radiation therapy. Pre- and postirradiation linear expansion rates were estimated using volumetric measurements on sequential magnetic resonance images (MRIs). In addition, postirradiation tumor volume change was classified as demonstrating shrinkage (ratio of volume on last follow-up MRI to MRI immediately preceding irradiation <80%), stability (ratio 80%-120%), or expansion (ratio >120%). The median pre- and postirradiation follow-up was 20.0 and 27.5 months, respectively. Seven tumors from neurofibromatosis type 2 (NF2) patients were excluded from statistical analyses. Results: In the 58 non-NF2 patients, there was a trend of correlation between pre- and postirradiation volume change rates (slope on linear regression, 0.29; P=.06). Tumors demonstrating postirradiation expansion had a median preirradiation growth rate of 89%/year, and those without postirradiation expansion had a median preirradiation growth rate of 41%/year (P=.02). As the preirradiation growth rate increased, the probability of postirradiation expansion also increased. Overall, 24.1% of tumors were stable, 53.4% experienced shrinkage, and 22.5% experienced expansion. Predictors of no postirradiation tumor expansion included no prior surgery (P=.01) and slower tumor growth rate (P=.02). The control of tumors in NF2 patients was only 43%. Conclusions: Radiation therapy is an effective treatment for VS, but tumors that grow quickly preirradiation may be

  18. Reinforcer magnitude and rate dependency: evaluation of resistance-to-change mechanisms.

    Science.gov (United States)

    Pinkston, Jonathan W; Ginsburg, Brett C; Lamb, Richard J

    2014-10-01

    Under many circumstances, reinforcer magnitude appears to modulate the rate-dependent effects of drugs such that when schedules arrange for relatively larger reinforcer magnitudes rate dependency is attenuated compared with behavior maintained by smaller magnitudes. The current literature on resistance to change suggests that increased reinforcer density strengthens operant behavior, and such strengthening effects appear to extend to the temporal control of behavior. As rate dependency may be understood as a loss of temporal control, the effects of reinforcer magnitude on rate dependency may be due to increased resistance to disruption of temporally controlled behavior. In the present experiments, pigeons earned different magnitudes of grain during signaled components of a multiple FI schedule. Three drugs, clonidine, haloperidol, and morphine, were examined. All three decreased overall rates of key pecking; however, only the effects of clonidine were attenuated as reinforcer magnitude increased. An analysis of within-interval performance found rate-dependent effects for clonidine and morphine; however, these effects were not modulated by reinforcer magnitude. In addition, we included prefeeding and extinction conditions, standard tests used to measure resistance to change. In general, rate-decreasing effects of prefeeding and extinction were attenuated by increasing reinforcer magnitudes. Rate-dependent analyses of prefeeding showed rate-dependency following those tests, but in no case were these effects modulated by reinforcer magnitude. The results suggest that a resistance-to-change interpretation of the effects of reinforcer magnitude on rate dependency is not viable.

  19. Growth-Phase Sterigmatocystin Formation on Lactose Is Mediated via Low Specific Growth Rates in Aspergillus nidulans

    Directory of Open Access Journals (Sweden)

    Zoltán Németh

    2016-11-01

    Full Text Available Seed contamination with polyketide mycotoxins such as sterigmatocystin (ST produced by Aspergilli is a worldwide issue. The ST biosynthetic pathway is well-characterized in A. nidulans, but regulatory aspects related to the carbon source are still enigmatic. This is particularly true for lactose, inasmuch as some ST production mutant strains still synthesize ST on lactose but not on other carbon substrates. Here, kinetic data revealed that on d-glucose, ST forms only after the sugar is depleted from the medium, while on lactose, ST appears when most of the carbon source is still available. Biomass-specified ST production on lactose was significantly higher than on d-glucose, suggesting that ST formation may either be mediated by a carbon catabolite regulatory mechanism, or induced by low specific growth rates attainable on lactose. These hypotheses were tested by d-glucose limited chemostat-type continuous fermentations. No ST formed at a high growth rate, while a low growth rate led to the formation of 0.4 mg·L−1 ST. Similar results were obtained with a CreA mutant strain. We concluded that low specific growth rates may be the primary cause of mid-growth ST formation on lactose in A. nidulans, and that carbon utilization rates likely play a general regulatory role during biosynthesis.

  20. The influence of specimen size on creep crack growth rate in cross-weld CT specimens cut out from a welded component

    International Nuclear Information System (INIS)

    Andersson, Peder; Segle, Peter; Samuelson, Lars Aa.

    1999-04-01

    A 3D finite element study of creep crack growth in cross-weld CT specimens with material properties of 2.25Cr1Mo at 550 deg C is carried out, where large strain and displacement theory is used. The creep crack growth rate is calculated using a creep ductility based damage model, in which the creep strain rate perpendicular to the crack plane ahead of the crack tip is integrated, considering the multiaxial stress state. The influence of specimen size on creep crack growth rate under constant load is given special attention, but the possibility to transfer results from cross-weld CT specimens to welded high temperature components is also investigated. The creep crack growth rate of a crack in a circumferentially welded pipe is compared with the creep crack growth rate of cross-weld CT specimens of three different sizes, cut out from the pipe. Although the constraint ahead of the crack tip is higher for a larger CT specimen, the creep crack growth rate is higher for a smaller specimen than for a larger one if they are loaded to attain the same stress intensity factor. If the specimens are loaded to the same C* value, however, a more complicated pattern occurs; depending on the material properties of the weldment constituents, the CT specimen with the intermediate size will either yield the highest or the lowest creep crack growth rate

  1. Bistable Bacterial Growth Rate in Response to Antibiotics with Low Membrane Permeability

    Science.gov (United States)

    Elf, Johan; Nilsson, Karin; Tenson, Tanel; Ehrenberg, Måns

    2006-12-01

    We demonstrate that growth rate bistability for bacterial cells growing exponentially at a fixed external antibiotic concentration can emerge when the cell wall permeability for the drug is low and the growth rate sensitivity to the intracellular drug concentration is high. Under such conditions, an initially high growth rate can remain high, due to dilution of the intracellular drug concentration by rapid cell volume increase, while an initially low growth rate can remain low, due to slow cell volume increase and insignificant drug dilution. Our findings have implications for the testing of novel antibiotics on growing bacterial strains.

  2. Circadian cycles in growth and feeding rates of heterotrophic protist plankton

    DEFF Research Database (Denmark)

    Jakobsen, Hans Henrik; Strom, S.L.

    2004-01-01

    Growth and feeding rates of four species of planktonic marine heterotrophic protists showed pronounced diel cycles. In most cases, rates were higher during the day and lower at night. However, for the ciliate Strobilidium sp., growth was highest at night. In another ciliate species, Balanion...... comatum, no day-night difference in growth and feeding rates was found. Maintenance of day-night rate differences during 24-h exposures to continuous darkness demonstrated that most of these protists had circadian cycles. The heterotrophic dinoflagellate Oxyrrhis marina exhibited a clear irradiance...... to culturing in a day: night light cycle in O. marina and found that resetting the circadian cycle in this dinoflagellate temporarily arrested growth and feeding. We suggest that protists use a time-integrated light threshold rather than an instantaneous irradiance to maintain the circadian cell cycle...

  3. Geographic distribution of habitat, development, and population growth rates of the Asian citrus psyllid, Diaphorina citri, in Mexico.

    Science.gov (United States)

    López-Collado, José; Isabel López-Arroyo, J; Robles-García, Pedro L; Márquez-Santos, Magdalena

    2013-01-01

    The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Psyllidae), is an introduced pest in Mexico and a vector of huanglongbing, a lethal citrus disease. Estimations of the habitat distribution and population growth rates of D. citri are required to establish regional and areawide management strategies and can be used as a pest risk analysis tools. In this study, the habitat distribution of D. citri in Mexico was computed with MaxEnt, an inductive, machine-learning program that uses bioclimatic layers and point location data. Geographic distributions of development and population growth rates were determined by fitting a temperature-dependent, nonlinear model and projecting the rates over the target area, using the annual mean temperature as the predictor variable. The results showed that the most suitable regions for habitat of D. citri comprise the Gulf of Mexico states, Yucatán Peninsula, and areas scattered throughout the Pacific coastal states. Less suitable areas occurred in northern and central states. The most important predictor variables were related to temperature. Development and growth rates had a distribution wider than habitat, reaching some of the northern states of México. Habitat, development, and population growth rates were correlated to each other and with the citrus producing area. These relationships indicated that citrus producing states are within the most suitable regions for the occurrence, development, and population growth of D. citri, therefore increasing the risk of huanglongbing dispersion.

  4. Evidence of A Bimodal US GDP Growth Rate Distribution: A Wavelet Approach

    Directory of Open Access Journals (Sweden)

    Sandro Claudio Lera

    2017-04-01

    Full Text Available We present a quantitative characterisation of the fluctuations of the annualized growth rate of the real US GDP per capita at many scales, using a wavelet transform analysis of two data sets, quarterly data from 1947 to 2015 and annual data from 1800 to 2010. The chosen mother wavelet (first derivative of the Gaussian function applied to the logarithm of the real US GDP per capita provides a robust estimation of the instantaneous growth rate at different scales. Our main finding is that business cycles appear at all scales and the distribution of GDP growth rates can be well approximated by a bimodal function associated to a series of switches between regimes of strong growth rate $\\rho_\\text{high}$ and regimes of low growth rate $\\rho_\\text{low}$. The succession of such two regimes compounds to produce a remarkably stable long term average real annualized growth rate of 1.6% from 1800 to 2010 and $\\approx 2.0\\%$ since 1950, which is the result of a subtle compensation between the high and low growth regimes that alternate continuously. Thus, the overall growth dynamics of the US economy is punctuated, with phases of strong growth that are intrinsically unsustainable, followed by corrections or consolidation until the next boom starts. We interpret these findings within the theory of "social bubbles" and argue as a consequence that estimations of the cost of the 2008 crisis may be misleading. We also interpret the absence of strong recovery since 2008 as a protracted low growth regime $\\rho_\\text{low}$ associated with the exceptional nature of the preceding large growth regime.

  5. Numerical Analysis of Inlet Gas-Mixture Flow Rate Effects on Carbon Nanotube Growth Rate

    Directory of Open Access Journals (Sweden)

    B. Zahed

    2013-01-01

    Full Text Available The growth rate and uniformity of Carbon Nano Tubes (CNTs based on Chemical Vapor Deposition (CVD technique is investigated by using a numerical model. In this reactor, inlet gas mixture, including xylene as carbon source and mixture of argon and hydrogen as  carrier gas enters into a horizontal CVD reactor at atmospheric pressure. Based on the gas phase and surface reactions, released carbon atoms are grown as CNTs on the iron catalysts at the reactor hot walls. The effect of inlet gas-mixture flow rate, on CNTs growth rate and its uniformity is discussed. In addition the velocity and temperature profile and also species concentrations throughout the reactor are presented.

  6. Disilane chemisorption on Si(x)Ge(1-x)(100)-(2 x 1): molecular mechanisms and implications for film growth rates.

    Science.gov (United States)

    Ng, Rachel Qiao-Ming; Tok, E S; Kang, H Chuan

    2009-07-28

    At low temperatures, hydrogen desorption is known to be the rate-limiting process in silicon germanium film growth via chemical vapor deposition. Since surface germanium lowers the hydrogen desorption barrier, Si(x)Ge((1-x)) film growth rate increases with the surface germanium fraction. At high temperatures, however, the molecular mechanisms determining the epitaxial growth rate are not well established despite much experimental work. We investigate these mechanisms in the context of disilane adsorption because disilane is an important precursor used in film growth. In particular, we want to understand the molecular steps that lead, in the high temperature regime, to a decrease in growth rate as the surface germanium increases. In addition, there is a need to consider the issue of whether disilane adsorbs via silicon-silicon bond dissociation or via silicon-hydrogen bond dissociation. It is usually assumed that disilane adsorption occurs via silicon-silicon bond dissociation, but in recent work we provided theoretical evidence that silicon-hydrogen bond dissociation is more important. In order to address these issues, we calculate the chemisorption barriers for disilane on silicon germanium using first-principles density functional theory methods. We use the calculated barriers to estimate film growth rates that are then critically compared to the experimental data. This enables us to establish a connection between the dependence of the film growth rate on the surface germanium content and the kinetics of the initial adsorption step. We show that the generally accepted mechanism where disilane chemisorbs via silicon-silicon bond dissociation is not consistent with the data for film growth kinetics. Silicon-hydrogen bond dissociation paths have to be included in order to give good agreement with the experimental data for high temperature film growth rate.

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

    Energy Technology Data Exchange (ETDEWEB)

    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.

  8. Strain rate dependency of laser sintered polyamide 12

    Directory of Open Access Journals (Sweden)

    Cook J.E.T.

    2015-01-01

    Full Text Available Parts processed by Additive Manufacturing can now be found across a wide range of applications, such as those in the aerospace and automotive industry in which the mechanical response must be optimised. Many of these applications are subjected to high rate or impact loading, yet it is believed that there is no prior research on the strain rate dependence in these materials. This research investigates the effect of strain rate and laser energy density on laser sintered polyamide 12. In the study presented here, parts produced using four different laser sintered energy densities were exposed to uniaxial compression tests at strain rates ranging from 10−3 to 10+3 s−1 at room temperature, and the dependence on these parameters is presented.

  9. GROWTH RATE DISPERSION (GRD OF THE (010 FACE OF BORAX CRYSTALS IN FLOWING SOLUTION

    Directory of Open Access Journals (Sweden)

    Suharso Suharso

    2010-06-01

    Full Text Available The growth rates of borax crystals from aqueous solutions in the (010 direction at various flow rates were measured. The observed variations of the growth rate can be represented by a normal distribution.  It was found that there is no correlation between growth rate distribution and solution flow under these experimental conditions.   Keywords: Growth rate dispersion (GRD, borax, flow rate

  10. Bacterial growth on surfaces: Automated image analysis for quantification of growth rate-related parameters

    DEFF Research Database (Denmark)

    Møller, S.; Sternberg, Claus; Poulsen, L. K.

    1995-01-01

    species-specific hybridizations with fluorescence-labelled ribosomal probes to estimate the single-cell concentration of RNA. By automated analysis of digitized images of stained cells, we determined four independent growth rate-related parameters: cellular RNA and DNA contents, cell volume......, and the frequency of dividing cells in a cell population. These parameters were used to compare physiological states of liquid-suspended and surfacegrowing Pseudomonas putida KT2442 in chemostat cultures. The major finding is that the correlation between substrate availability and cellular growth rate found...

  11. Lanthanide-Dependent Regulation of Methanol Oxidation Systems in Methylobacterium extorquens AM1 and Their Contribution to Methanol Growth.

    Science.gov (United States)

    Vu, Huong N; Subuyuj, Gabriel A; Vijayakumar, Srividhya; Good, Nathan M; Martinez-Gomez, N Cecilia; Skovran, Elizabeth

    2016-04-01

    Methylobacterium extorquens AM1 has two distinct types of methanol dehydrogenase (MeDH) enzymes that catalyze the oxidation of methanol to formaldehyde. MxaFI-MeDH requires pyrroloquinoline quinone (PQQ) and Ca in its active site, while XoxF-MeDH requires PQQ and lanthanides, such as Ce and La. Using MeDH mutant strains to conduct growth analysis and MeDH activity assays, we demonstrate that M. extorquens AM1 has at least one additional lanthanide-dependent methanol oxidation system contributing to methanol growth. Additionally, the abilities of different lanthanides to support growth were tested and strongly suggest that both XoxF and the unknown methanol oxidation system are able to use La, Ce, Pr, Nd, and, to some extent, Sm. Further, growth analysis using increasing La concentrations showed that maximum growth rate and yield were achieved at and above 1 μM La, while concentrations as low as 2.5 nM allowed growth at a reduced rate. Contrary to published data, we show that addition of exogenous lanthanides results in differential expression from the xox1 and mxa promoters, upregulating genes in the xox1 operon and repressing genes in the mxa operon. Using transcriptional reporter fusions, intermediate expression from both the mxa and xox1 promoters was detected when 50 to 100 nM La was added to the growth medium, suggesting that a condition may exist under which M. extorquens AM1 is able to utilize both enzymes simultaneously. Together, these results suggest that M. extorquens AM1 actively senses and responds to lanthanide availability, preferentially utilizing the lanthanide-dependent MeDHs when possible. The biological role of lanthanides is a nascent field of study with tremendous potential to impact many areas in biology. Our studies demonstrate that there is at least one additional lanthanide-dependent methanol oxidation system, distinct from the MxaFI and XoxF MeDHs, that may aid in classifying additional environmental organisms as methylotrophs. Further

  12. Nationwide Macroeconomic Variables and the Growth Rate of Bariatric Surgeries in Brazil.

    Science.gov (United States)

    Cazzo, Everton; Ramos, Almino Cardoso; Pareja, José Carlos; Chaim, Elinton Adami

    2018-06-06

    The effect of nationwide economic issues on the necessary expansion in the number of bariatric procedures remains unclear. This study aims to determine whether there are correlations between the growth rate in the number of bariatric surgeries and the major macroeconomic variables over time in Brazil. It is a nationwide analysis regarding the number of bariatric surgeries in Brazil and the main national macroeconomic variables from 2003 through 2016: gross domestic product (GDP), inflation rate, and the unemployment rate, as well as the evolution in the number of registered bariatric surgeons. There were significant positive correlations of the growth rate of surgeries with the early variations of the GDP (R = 0.5558; p = 0.04863) and of the overall health expenditure per capita (R = 0.78322; p = 0.00259). The growth rate of the number of bariatric surgeries was not correlated with the unemployment and inflation rates, as well as with the growth rate of available bariatric surgeons. There were direct relationships between the growth rate of bariatric surgeries and the evolutions of the GDP and health care expenditure per capita. These variables appear to influence the nationwide offer of bariatric surgery.

  13. Modality dependency of familiarity ratings of Japanese words.

    Science.gov (United States)

    Amano, S; Kondo, T; Kakehi, K

    1995-07-01

    Familiarity ratings for a large number of aurally and visually presented Japanese words wer measured for 11 subjects, in order to investigate the modality dependency of familiarity. The correlation coefficient between auditory and visual ratings was .808, which is lower than that observed for English words, suggesting that a substantial portion of the mental lexicon is modality dependent. It was shown that the modality dependency is greater for low-familiarity words than it is for medium- or high-familiarity words. This difference between the low- and the medium- or high-familiarity words has a relationship to orthography. That is, the dependency is larger in words consisting only of kanji, which may have multiple pronunciations and usually represent meaning, than it is in words consisting only of hiragana or katakana, which have a single pronunciation and usually do not represent meaning. These results indicate that the idiosyncratic characteristics of Japanese orthography contribute to the modality dependency.

  14. Constraints and trade-offs in climate-dependent adaptation: energy budgets and growth in a latitudinal cline

    Directory of Open Access Journals (Sweden)

    Hans O. Pörtner

    2005-12-01

    Full Text Available Characteristics of temperature-dependent metabolic adaptation as well as their implications for associated changes in energy budgets are analysed based on comparisons of fish and invertebrates from various latitudinal clines in northern and southern hemispheres and on integrated ecological and physiological approaches. To identify putative “bottlenecks” of adaptation and for a general cause and effect understanding, the temperature sensitivity of growth as a key energy budget component is investigated, considering underlying processes at population, whole animal and cellular levels. Available data support the hypothesis that natural selection favours individuals for energy efficiency and maximised growth, but is subject to constraints of limited energy availability and temperature. According to emerging relationships between energy turnover, temperature variability and thermal tolerance, the notion that selection should favour a certain metabolic rate according to mean temperature is too simplistic. Within the energy budget, savings in maintenance costs set free energy for growth, visible as growth increments at a low standard metabolic rate. Such energy savings are maximised at the permanently low temperature of the Antarctic. However, some variability persists as pelagic lifestyles in the Antarctic are fuelled by higher metabolic rates at the expense of reduced growth. Temperature variability in the cold, as in the Subarctic, causes a rise in maintenance costs at the expense of growth, but in favour of exercise and thus foraging capacity. Such transitions in energy cost between sub-polar and polar areas are not visible in the southern hemisphere, where there is less temperature variability. However, these patterns—as well as many of the underlying mechanisms—still remain incompletely investigated, especially with respect to the suggested hierarchy in energy allocation to energy budget components.

  15. Age class, longevity and growth rate relationships: protracted growth increases in old trees in the eastern United States.

    Science.gov (United States)

    Johnson, Sarah E; Abrams, Marc D

    2009-11-01

    This study uses data from the International Tree-Ring Data Bank website and tree cores collected in the field to explore growth rate (basal area increment, BAI) relationships across age classes (from young to old) for eight tree species in the eastern US. These species represent a variety of ecological traits and include those in the genera Populus, Quercus, Pinus, Tsuga and Nyssa. We found that most trees in all age classes and species exhibit an increasing BAI throughout their lives. This is particularly unusual for trees in the older age classes that we expected to have declining growth in the later years, as predicted by physiological growth models. There exists an inverse relationship between growth rate and increasing age class. The oldest trees within each species have consistently slow growth throughout their lives, implying an inverse relationship between growth rate and longevity. Younger trees (trees when they are of the same age resulting from a higher proportion of fast-growing trees in these young age classes. Slow, but increasing, BAI in the oldest trees in recent decades is a continuation of their growth pattern established in previous centuries. The fact that they have not shown a decreasing growth rate in their old age contradicts physiological growth models and may be related to the stimulatory effects of global change phenomenon (climate and land-use history).

  16. Oxygen-sensitive regulation and neuroprotective effects of growth hormone-dependent growth factors during early postnatal development.

    Science.gov (United States)

    Jung, Susan; Boie, Gudrun; Doerr, Helmuth-Guenther; Trollmann, Regina

    2017-04-01

    Perinatal hypoxia severely disrupts metabolic and somatotrophic development, as well as cerebral maturational programs. Hypoxia-inducible transcription factors (HIFs) represent the most important endogenous adaptive mechanisms to hypoxia, activating a broad spectrum of growth factors that contribute to cell survival and energy homeostasis. To analyze effects of systemic hypoxia and growth hormone (GH) therapy (rhGH) on HIF-dependent growth factors during early postnatal development, we compared protein (using ELISA) and mRNA (using quantitative RT PCR) levels of growth factors in plasma and brain between normoxic and hypoxic mice (8% O 2 , 6 h; postnatal day 7 , P7) at P14. Exposure to hypoxia led to reduced body weight ( P controls and was associated with significantly reduced plasma levels of mouse GH ( P controls. In addition, rhGH treatment increased cerebral IGF-1, IGF-2, IGFBP-2, and erythropoietin mRNA levels, resulting in significantly reduced apoptotic cell death in the hypoxic, developing mouse brain. These data indicate that rhGH may functionally restore hypoxia-induced systemic dysregulation of the GH/IGF-1 axis and induce upregulation of neuroprotective, HIF-dependent growth factors in the hypoxic developing brain. Copyright © 2017 the American Physiological Society.

  17. Growth rate regulated genes and their wide involvement in the Lactococcus lactis stress responses

    Directory of Open Access Journals (Sweden)

    Redon Emma

    2008-07-01

    Full Text Available Abstract Background The development of transcriptomic tools has allowed exhaustive description of stress responses. These responses always superimpose a general response associated to growth rate decrease and a specific one corresponding to the stress. The exclusive growth rate response can be achieved through chemostat cultivation, enabling all parameters to remain constant except the growth rate. Results We analysed metabolic and transcriptomic responses of Lactococcus lactis in continuous cultures at different growth rates ranging from 0.09 to 0.47 h-1. Growth rate was conditioned by isoleucine supply. Although carbon metabolism was constant and homolactic, a widespread transcriptomic response involving 30% of the genome was observed. The expression of genes encoding physiological functions associated with biogenesis increased with growth rate (transcription, translation, fatty acid and phospholipids metabolism. Many phages, prophages and transposon related genes were down regulated as growth rate increased. The growth rate response was compared to carbon and amino-acid starvation transcriptomic responses, revealing constant and significant involvement of growth rate regulations in these two stressful conditions (overlap 27%. Two regulators potentially involved in the growth rate regulations, llrE and yabB, have been identified. Moreover it was established that genes positively regulated by growth rate are preferentially located in the vicinity of replication origin while those negatively regulated are mainly encountered at the opposite, thus indicating the relationship between genes expression and their location on chromosome. Although stringent response mechanism is considered as the one governing growth deceleration in bacteria, the rigorous comparison of the two transcriptomic responses clearly indicated the mechanisms are distinct. Conclusion This work of integrative biology was performed at the global level using transcriptomic analysis

  18. Unusual growth rate during cystic echinococcosis.

    Science.gov (United States)

    Valour, Florent; Khenifer, Safia; Della-Schiava, Nellie; Cotte, Eddy; Guibert, Benoit; Wallon, Martine; Durupt, Stéphane; Durieu, Isabelle

    2014-04-01

    Cystic echinococcosis is a world wild zoonosis caused by Echinococcus granulosus, leading to hepatic and lung cysts with a usually slight growth rate. We report the case of an 82year-old Algerian woman with hepatic and lung cystic echinococcosis with a 10-fold size increase in 6months. Copyright © 2013. Published by Elsevier Ireland Ltd.

  19. Extreme-value dependence: An application to exchange rate markets

    Science.gov (United States)

    Fernandez, Viviana

    2007-04-01

    Extreme value theory (EVT) focuses on modeling the tail behavior of a loss distribution using only extreme values rather than the whole data set. For a sample of 10 countries with dirty/free float regimes, we investigate whether paired currencies exhibit a pattern of asymptotic dependence. That is, whether an extremely large appreciation or depreciation in the nominal exchange rate of one country might transmit to another. In general, after controlling for volatility clustering and inertia in returns, we do not find evidence of extreme-value dependence between paired exchange rates. However, for asymptotic-independent paired returns, we find that tail dependency of exchange rates is stronger under large appreciations than under large depreciations.

  20. A panel data investigation of real exchange rate misalignment and growth

    Directory of Open Access Journals (Sweden)

    Flávio Vilela Vieira

    2012-09-01

    Full Text Available The paper investigates the role of real exchange rate misalignment on long-run growth for a set of ninety countries using time series data from 1980 to 2004. We first estimate a panel data model (fixed and random effects for the real exchange rate in order to produce estimates of the equilibrium real exchange rate and this is then used to construct measures of real exchange rate misalignment. We provide an alternative set of estimates of RER misalignment using panel cointegration methods. The results for the two-step System GMM panel growth models indicate that the coefficients for real exchange rate misalignment are positive for different model specification and samples, which means that a more depreciated (appreciated real exchange rate helps (harms long-run growth. The estimated coefficients are higher for developing and emerging countries.

  1. Supersaturation Control using Analytical Crystal Size Distribution Estimator for Temperature Dependent in Nucleation and Crystal Growth Phenomena

    Science.gov (United States)

    Zahari, Zakirah Mohd; Zubaidah Adnan, Siti; Kanthasamy, Ramesh; Saleh, Suriyati; Samad, Noor Asma Fazli Abdul

    2018-03-01

    The specification of the crystal product is usually given in terms of crystal size distribution (CSD). To this end, optimal cooling strategy is necessary to achieve the CSD. The direct design control involving analytical CSD estimator is one of the approaches that can be used to generate the set-point. However, the effects of temperature on the crystal growth rate are neglected in the estimator. Thus, the temperature dependence on the crystal growth rate needs to be considered in order to provide an accurate set-point. The objective of this work is to extend the analytical CSD estimator where Arrhenius expression is employed to cover the effects of temperature on the growth rate. The application of this work is demonstrated through a potassium sulphate crystallisation process. Based on specified target CSD, the extended estimator is capable of generating the required set-point where a proposed controller successfully maintained the operation at the set-point to achieve the target CSD. Comparison with other cooling strategies shows a reduction up to 18.2% of the total number of undesirable crystals generated from secondary nucleation using linear cooling strategy is achieved.

  2. The frequency effect on the fatigue crack growth rate of 304 stainless steel

    International Nuclear Information System (INIS)

    Shih, Y.-S.; Chen, J.-J.

    1999-01-01

    Under cyclic loading condition, the fatigue crack growth (FCG) rate governed by stress intensity factor and stress ratio is well known; Walker's equation, Forman's equation and Elber's equation are typical formulae to describe the fatigue crack growth rate. However, the loading frequency effect on the fatigue crack growth rate has yet to be explored. Recently, studies have focused on the loading frequency effect on some visco-elastic materials, and have provided a clearer understanding of the frequency effect on the fatigue crack growth rate. In a physical sense, knowledge about the loading frequency effect on the fatigue crack growth rate for 304 stainless steel is still lacking. James conducted a lot of experiments, and through data analysis, he concluded an evaluation equation which is based upon the experimental illustration. In this study, the physical properties of the material are used to illustrate the modification of fatigue crack growth rate, and a new formula which is based upon the modified Forman's equation, is provided. (orig.)

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

    Science.gov (United States)

    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.

  4. Size- and food-dependent growth drives patterns of competitive dominance along productivity gradients.

    Science.gov (United States)

    Huss, Magnus; Gårdmark, Anna; Van Leeuwen, Anieke; de Roos, André M

    2012-04-01

    Patterns of coexistence among competing species exhibiting size- and food-dependent growth remain largely unexplored. Here we studied mechanisms behind coexistence and shifts in competitive dominance in a size-structured fish guild, representing sprat and herring stocks in the Baltic Sea, using a physiologically structured model of competing populations. The influence of degree of resource overlap and the possibility of undergoing ontogenetic diet shifts were studied as functions of zooplankton and zoobenthos productivity. By imposing different size-dependent mortalities, we could study the outcome of competition under contrasting environmental regimes representing poor and favorable growth conditions. We found that the identity of the dominant species shifted between low and high productivity. Adding a herring-exclusive benthos resource only provided a competitive advantage over sprat when size-dependent mortality was high enough to allow for rapid growth in the zooplankton niche. Hence, the importance of a bottom-up effect of varying productivity was dependent on a strong top-down effect. Although herring could depress shared resources to lower levels than could sprat and also could access an exclusive resource, the smaller size at maturation of sprat allowed it to coexist with herring and, in some cases, exclude it. Our model system, characterized by interactions among size cohorts, allowed for consumer coexistence even at full resource overlap at intermediate productivities when size-dependent mortality was low. Observed shifts in community patterns were crucially dependent on the explicit consideration of size- and food-dependent growth. Accordingly, we argue that accounting for food-dependent growth and size-dependent interactions is necessary to better predict changes in community structure and dynamics following changes in major ecosystem drivers such as resource productivity and mortality, which are fundamental for our ability to manage exploitation of

  5. Growth and time dependent alignment of KCl crystals in Hemoglobin LB monolayer

    International Nuclear Information System (INIS)

    Mahato, Mrityunjoy; Pal, Prabir; Tah, Bidisha; Kamilya, Tapanendu; Talapatra, G.B.

    2012-01-01

    Nature and organism often use the biomineralization technique to build up various highly regular structures such as bone, teeth, kidney stone etc., and recently this becomes the strategy to design and synthesis of novel biocomposite materials. We report here the controlled crystallization of KCl in Langmuir and Langmuir Blodgett (LB) monolayer of Hemoglobin (Hb) at ambient condition. The nucleation and growth of KCl crystals in Hb monolayer has temporal and KCl concentration dependency. The growth of KCl crystals in LB film of Hb has distinct behavior in the alignment of crystals from linear to fractal like structures depending on growth time. The crystallographic identity of the biomineralized KCl crystal is confirmed from HR-TEM, XRD, and from powder diffraction simulation. Our results substantiated that the template of Langmuir monolayer of proteins plays a crucial role in biomineralization as well as in designing and synthesizing of novel biocomposite materials. Highlights: ► Biomineralization of KCl crystal has been studied in Hemoglobin LB film. ► KCl crystal growth is time and concentration of KCl dependent. ► The alignment of KCl crystal growth is fractal nature with time. ► The unfolding of Hb and evaporation factor has some role in crystallization and fractal growth.

  6. DKDP crystal growth controlled by cooling rate

    Science.gov (United States)

    Xie, Xiaoyi; Qi, Hongji; Shao, Jianda

    2017-08-01

    The performance of deuterated potassium dihydrogen phosphate (DKDP) crystal directly affects beam quality, energy and conversion efficiency in the Inertial Confinement Fusion(ICF)facility, which is related with the initial saturation temperature of solution and the real-time supersaturation during the crystal growth. However, traditional method to measure the saturation temperature is neither efficient nor accurate enough. Besides, the supersaturation is often controlled by experience, which yields the higher error and leads to the instability during the crystal growth. In this paper, DKDP solution with 78% deuteration concentration is crystallized in different temperatures. We study the relation between solubility and temperature of DKDP and fit a theoretical curve with a parabola model. With the model, the measurement of saturation temperature is simplified and the control precision of the cooling rate is improved during the crystal growth, which is beneficial for optimizing the crystal growth process.

  7. Comprehensive analyses of ventricular myocyte models identify targets exhibiting favorable rate dependence.

    Directory of Open Access Journals (Sweden)

    Megan A Cummins

    2014-03-01

    Full Text Available Reverse rate dependence is a problematic property of antiarrhythmic drugs that prolong the cardiac action potential (AP. The prolongation caused by reverse rate dependent agents is greater at slow heart rates, resulting in both reduced arrhythmia suppression at fast rates and increased arrhythmia risk at slow rates. The opposite property, forward rate dependence, would theoretically overcome these parallel problems, yet forward rate dependent (FRD antiarrhythmics remain elusive. Moreover, there is evidence that reverse rate dependence is an intrinsic property of perturbations to the AP. We have addressed the possibility of forward rate dependence by performing a comprehensive analysis of 13 ventricular myocyte models. By simulating populations of myocytes with varying properties and analyzing population results statistically, we simultaneously predicted the rate-dependent effects of changes in multiple model parameters. An average of 40 parameters were tested in each model, and effects on AP duration were assessed at slow (0.2 Hz and fast (2 Hz rates. The analysis identified a variety of FRD ionic current perturbations and generated specific predictions regarding their mechanisms. For instance, an increase in L-type calcium current is FRD when this is accompanied by indirect, rate-dependent changes in slow delayed rectifier potassium current. A comparison of predictions across models identified inward rectifier potassium current and the sodium-potassium pump as the two targets most likely to produce FRD AP prolongation. Finally, a statistical analysis of results from the 13 models demonstrated that models displaying minimal rate-dependent changes in AP shape have little capacity for FRD perturbations, whereas models with large shape changes have considerable FRD potential. This can explain differences between species and between ventricular cell types. Overall, this study provides new insights, both specific and general, into the determinants of

  8. Elevated atmospheric CO2 increases microbial growth rates and enzymes activity in soil

    Science.gov (United States)

    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 aestivumyeast 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 1.2-1.9-fold higher than under ambient CO2. This indicates the increased activity of microorganisms, which leads to accelerated C turnover in soil under elevated CO2. Our results clearly showed that the functional characteristics of the soil microbial community (i.e. specific growth rates and enzymes activity) rather than total microbial biomass

  9. Skeletal muscle protein accretion rates and hindlimb growth are reduced in late gestation intrauterine growth-restricted fetal sheep.

    Science.gov (United States)

    Rozance, Paul J; Zastoupil, Laura; Wesolowski, Stephanie R; Goldstrohm, David A; Strahan, Brittany; Cree-Green, Melanie; Sheffield-Moore, Melinda; Meschia, Giacomo; Hay, William W; Wilkening, Randall B; Brown, Laura D

    2018-01-01

    Adults who were affected by intrauterine growth restriction (IUGR) suffer from reductions in muscle mass, which may contribute to insulin resistance and the development of diabetes. We demonstrate slower hindlimb linear growth and muscle protein synthesis rates that match the reduced hindlimb blood flow and oxygen consumption rates in IUGR fetal sheep. These adaptations resulted in hindlimb blood flow rates in IUGR that were similar to control fetuses on a weight-specific basis. Net hindlimb glucose uptake and lactate output rates were similar between groups, whereas amino acid uptake was significantly lower in IUGR fetal sheep. Among all fetuses, blood O 2 saturation and plasma glucose, insulin and insulin-like growth factor-1 were positively associated and norepinephrine was negatively associated with hindlimb weight. These results further our understanding of the metabolic and hormonal adaptations to reduced oxygen and nutrient supply with placental insufficiency that develop to slow hindlimb growth and muscle protein accretion. Reduced skeletal muscle mass in the fetus with intrauterine growth restriction (IUGR) persists into adulthood and may contribute to increased metabolic disease risk. To determine how placental insufficiency with reduced oxygen and nutrient supply to the fetus affects hindlimb blood flow, substrate uptake and protein accretion rates in skeletal muscle, late gestation control (CON) (n = 8) and IUGR (n = 13) fetal sheep were catheterized with aortic and femoral catheters and a flow transducer around the external iliac artery. Muscle protein kinetic rates were measured using isotopic tracers. Hindlimb weight, linear growth rate, muscle protein accretion rate and fractional synthetic rate were lower in IUGR compared to CON (P fetal norepinephrine and reduced IGF-1 and insulin. © 2017 The Authors. The Journal of Physiology © 2017 The Physiological Society.

  10. Reinforcement magnitude modulation of rate dependent effects in pigeons and rats.

    Science.gov (United States)

    Ginsburg, Brett C; Pinkston, Jonathan W; Lamb, R J

    2011-08-01

    Response rate can influence the behavioral effects of many drugs. Reinforcement magnitude may also influence drug effects. Further, reinforcement magnitude can influence rate-dependent effects. For example, in an earlier report, we showed that rate-dependent effects of two antidepressants depended on reinforcement magnitude. The ability of reinforcement magnitude to interact with rate-dependency has not been well characterized. It is not known whether our previous results are specific to antidepressants or generalize to other drug classes. Here, we further examine rate-magnitude interactions by studying effects of two stimulants (d-amphetamine [0.32-5.6 mg/kg] and cocaine [0.32-10 mg/kg]) and two sedatives (chlordiazepoxide [1.78-32 mg/kg] and pentobarbital [1.0-17.8 mg/kg]) in pigeons responding under a 3-component multiple fixed-interval (FI) 300-s schedule maintained by 2-, 4-, or 8-s of food access. We also examine the effects of d-amphetamine [0.32-3.2 mg/kg] and pentobarbital [1.8-10 mg/kg] in rats responding under a similar multiple FI300-s schedule maintained by 2- or 10- food pellet (45 mg) delivery. In pigeons, cocaine and, to a lesser extent, chlordiazepoxide exerted rate-dependent effects that were diminished by increasing durations of food access. The relationship was less apparent for pentobarbital, and not present for d-amphetamine. In rats, rate-dependent effects of pentobarbital and d-amphetamine were not modulated by reinforcement magnitude. In conclusion, some drugs appear to exert rate-dependent effect which are diminished when reinforcement magnitude is relatively high. Subsequent analysis of the rate-dependency data suggest the effects of reinforcement magnitude may be due to a diminution of drug-induced increases in low-rate behavior that occurs early in the fixed-interval. (c) 2011 APA, all rights reserved.

  11. Fibroblast growth factor receptor mediates fibroblast-dependent growth in EMMPRIN-depleted head and neck cancer tumor cells.

    Science.gov (United States)

    Liu, Zhiyong; Hartman, Yolanda E; Warram, Jason M; Knowles, Joseph A; Sweeny, Larissa; Zhou, Tong; Rosenthal, Eben L

    2011-08-01

    Head and neck squamous cell carcinoma tumors (HNSCC) contain a dense fibrous stroma which is known to promote tumor growth, although the mechanism of stroma-mediated growth remains unclear. As dysplastic mucosal epithelium progresses to cancer, there is incremental overexpression of extracellular matrix metalloprotease inducer (EMMPRIN) which is associated with tumor growth and metastasis. Here, we present evidence that gain of EMMPRIN expression allows tumor growth to be less dependent on fibroblasts by modulating fibroblast growth factor receptor-2 (FGFR2) signaling. We show that silencing EMMPRIN in FaDu and SCC-5 HNSCC cell lines inhibits cell growth, but when EMMPRIN-silenced tumor cells were cocultured with fibroblasts or inoculated with fibroblasts into severe combined immunodeficient mice, the growth inhibition by silencing EMMPRIN was blunted by the presence of fibroblasts. Coculture experiments showed fibroblast-dependent tumor cell growth occurred via a paracrine signaling. Analysis of tumor gene expression revealed expression of FGFR2 was inversely related to EMMPRIN expression. To determine the role of FGFR2 signaling in EMMPRIN-silenced tumor cells, ligands and inhibitors of FGFR2 were assessed. Both FGF1 and FGF2 enhanced tumor growth in EMMPRIN-silenced cells compared with control vector-transfected cells, whereas inhibition of FGFR2 with blocking antibody or with a synthetic inhibitor (PD173074) inhibited tumor cell growth in fibroblast coculture, suggesting the importance of FGFR2 signaling in fibroblast-mediated tumor growth. Analysis of xenografted tumors revealed that EMMPRIN-silenced tumors had a larger stromal compartment compared with control. Taken together, these results suggest that EMMPRIN acquired during tumor progression promotes fibroblast-independent tumor growth.

  12. Fibroblast growth factor receptor mediates fibroblast-dependent growth in EMMPRIN depleted head and neck cancer tumor cells

    Science.gov (United States)

    Liu, Zhiyong; Hartman, Yolanda E.; Warram, Jason M.; Knowles, Joseph A.; Sweeny, Larrisa; Zhou, Tong; Rosenthal, Eben L.

    2011-01-01

    Head and neck squamous cell carcinoma tumors (HNSCC) contain a dense fibrous stroma which is known to promote tumor growth, although the mechanism of stroma mediated growth remains unclear. As dysplastic mucosal epithelium progresses to cancer there is incremental overexpression of extracellular matrix metalloprotease inducer (EMMPRIN) which is associated with tumor growth and metastasis. Here we present evidence that gain of EMMPRIN expression allows tumor growth to be less dependent on fibroblasts by modulating fibroblast growth factor receptor-2 (FGFR2) signaling. We show that silencing EMMPRIN in FaDu and SCC-5 HNSCC cell lines inhibits cell growth, but when EMMPRIN-silenced tumor cells were co-cultured with fibroblasts or inoculated with fibroblasts into SCID mice, the growth inhibition by silencing EMMPRIN was blunted by the presence of fibroblasts. Co-culture experiments demonstrated fibroblast-dependent tumor cell growth occurred via a paracrine signaling. Analysis of tumor gene expression revealed expression of FGFR2 was inversely related to EMMPRIN expression. To determine the role of FGFR2 signaling in EMMPRIN silenced tumor cells, ligands and inhibitors of FGFR2 were assessed. Both FGF1 and FGF2 enhanced tumor growth in EMMPRIN silenced cells compared to control vector transfected cells, while inhibition of FGFR2 with blocking antibody or with a synthetic inhibitor (PD173074) inhibited tumor cell growth in fibroblast co-culture, suggesting the importance of FGFR2 signaling in fibroblast mediated tumor growth. Analysis of xenografted tumors revealed EMMPRIN silenced tumors had a larger stromal compartment compared to control. Taken together, these results suggest that EMMPRIN acquired during tumor progression promotes fibroblast independent tumor growth. PMID:21665938

  13. Time dependent fracture growth in intact crystalline rock: new laboratory procedures

    International Nuclear Information System (INIS)

    Backers, T.; Stephansson, O.

    2008-01-01

    Short term laboratory tests to determine the strength of rock material are commonly used to assess stability of rock excavations. However, loading the rock below its short term strength may lead to delayed failure due to slow stable fracture growth. This time-dependent phenomenon is called subcritical fracture growth. A fracture mechanics based approach is applied in this study to determine the parameters describing subcritical fracture growth under Mode Ⅰ (tensile) and Mode Ⅱ (in-plane shear) loading in terms of the stress intensity factors of saturated granodiorite from the) Aespoe HRL. A statistical method is applied to data from three-point bending (tension) and Punch-Through Shear with Confining Pressure, PTS/CP, (shear) experiments. One population of each set-up was subjected to rapid loading tests yielding a strength probability distribution. A second population was loaded up to a certain fraction of the statistical percentage for failure and the time-to-failure was determined. From these two populations the subcritical fracture growth parameters were determined successfully. Earlier studies demonstrated subcritical fracture growth under Mode I loading conditions, but this study shows that under a Mode Ⅱ load time-dependent fracture growth exists as well. (authors)

  14. Metabolic efficiency in yeast Saccharomyces cerevisiae in relation to temperature dependent growth and biomass yield.

    Science.gov (United States)

    Zakhartsev, Maksim; Yang, Xuelian; Reuss, Matthias; Pörtner, Hans Otto

    2015-08-01

    Canonized view on temperature effects on growth rate of microorganisms is based on assumption of protein denaturation, which is not confirmed experimentally so far. We develop an alternative concept, which is based on view that limits of thermal tolerance are based on imbalance of cellular energy allocation. Therefore, we investigated growth suppression of yeast Saccharomyces cerevisiae in the supraoptimal temperature range (30-40°C), i.e. above optimal temperature (Topt). The maximal specific growth rate (μmax) of biomass, its concentration and yield on glucose (Yx/glc) were measured across the whole thermal window (5-40°C) of the yeast in batch anaerobic growth on glucose. Specific rate of glucose consumption, specific rate of glucose consumption for maintenance (mglc), true biomass yield on glucose (Yx/glc(true)), fractional conservation of substrate carbon in product and ATP yield on glucose (Yatp/glc) were estimated from the experimental data. There was a negative linear relationship between ATP, ADP and AMP concentrations and specific growth rate at any growth conditions, whilst the energy charge was always high (~0.83). There were two temperature regions where mglc differed 12-fold, which points to the existence of a 'low' (within 5-31°C) and a 'high' (within 33-40°C) metabolic mode regarding maintenance requirements. The rise from the low to high mode occurred at 31-32°C in step-wise manner and it was accompanied with onset of suppression of μmax. High mglc at supraoptimal temperatures indicates a significant reduction of scope for growth, due to high maintenance cost. Analysis of temperature dependencies of product formation efficiency and Yatp/glc revealed that the efficiency of energy metabolism approaches its lower limit at 26-31°C. This limit is reflected in the predetermined combination of Yx/glc(true), elemental biomass composition and degree of reduction of the growth substrate. Approaching the limit implies a reduction of the safety margin

  15. Study on the PWSCC Crack Growth Rate for Steam Generator Tubing

    International Nuclear Information System (INIS)

    Kang, Shin Hoo; Hwang, Il Soon; Lim, Jun; Lee, Seung Gi; Ryu, Kyung Ha

    2008-03-01

    Using in-situ Raman spectroscopy and crack growth rate lest system in simulated PWR primary water environment, the relationship between the oxide film chemistry and the PWSCC growth rate has been studied. We used I/2T compact tension specimen and disk specimen made of Alloy 182 and Alloy 600 for crack growth rate test and in-situ Raman spectroscopy measurement. Test was made in a refreshed autoclave with 30 cc STP / kg of dissolved hydrogen concentration. Conductivity, pH, dissolved hydrogen and oxygen concentration were continuously monitored at the outlet. The crack growth rate was measured by using switching DCPD technique under cyclinc triangular loading and at the same time oxide phase was determined by using in-situ Raman spectra at the elevation of the temperature. Additionally Raman spectroscopy was achieved for oxide phase transition of Alloy 600 according to the temperature and dissolved hydrogen concentration, 2 and 30cc STP / kg

  16. Breast meat quality of chickens with divergent growth rates and its relation to growth curve parameters

    Directory of Open Access Journals (Sweden)

    P. C. Muth

    2017-11-01

    Full Text Available The effects of the increase of body weight of contemporary broilers during growth on functional meat quality and color characteristics of the chicken breast muscle are controversially debated. Therefore, male chickens (n = 264 of a fast-growing commercial broiler (Ross 308 and two slow-growing experimental meat-type chicken lines were compared at equal age and at similar body weight in order to investigate the effect of growth rate on selected functional breast meat traits and meat color. Additionally, the breast meat characteristics of birds with different growth profiles were compared within lines. When the body weight of commercial broilers reached about 40 to 60 % of their growth potential, they exhibited particularly high ultimate pH values compared with slow-growing lines. The ability of the meat of fast-growing broilers to retain water during cooking was impaired (5 to 16 percentage points increased cooking loss compared to slow-growing lines, which, in contrast to pH, was only marginally affected by body weight and/or age at slaughter. No unfavorable correlations of breast meat quality traits with the growth profile, represented by growth curve parameters derived from the Gompertz–Laird equation, were detected within any of the investigated chicken lines. It is noteworthy that the associations of ultimate pH and cooking loss with maximum growth speed indicate a non-linear relationship. Thus, some of the functional characteristics of breast meat of the fast-growing broiler resembled the white-striping defect described for poultry meat, but the hypothesis that selection on increased growth rates is detrimental for meat quality per se could not be confirmed. In fact, an elevated growth potential in particular, i.e., body weight at maturity, could have some beneficial effects for the water-holding capacity of breast meat, regardless of the genotypic growth rate.

  17. The Optimal Replenishment Policy under Trade Credit Financing with Ramp Type Demand and Demand Dependent Production Rate

    Directory of Open Access Journals (Sweden)

    Juanjuan Qin

    2014-01-01

    Full Text Available This paper investigates the optimal replenishment policy for the retailer with the ramp type demand and demand dependent production rate involving the trade credit financing, which is not reported in the literatures. First, the two inventory models are developed under the above situation. Second, the algorithms are given to optimize the replenishment cycle time and the order quantity for the retailer. Finally, the numerical examples are carried out to illustrate the optimal solutions and the sensitivity analysis is performed. The results show that if the value of production rate is small, the retailer will lower the frequency of putting the orders to cut down the order cost; if the production rate is high, the demand dependent production rate has no effect on the optimal decisions. When the trade credit is less than the growth stage time, the retailer will shorten the replenishment cycle; when it is larger than the breakpoint of the demand, within the maturity stage of the products, the trade credit has no effect on the optimal order cycle and the optimal order quantity.

  18. Long-term growth rates and effects of bleaching in Acropora hyacinthus

    Science.gov (United States)

    Gold, Zachary; Palumbi, Stephen R.

    2018-03-01

    Understanding the response of coral growth to natural variation in the environment, as well as to acute temperature stress under current and future climate change conditions, is critical to predicting the future health of coral reef ecosystems. As such, ecological surveys are beginning to focus on corals that live in high thermal stress environments to understand how future coral populations may adapt to climate change. We investigated the relationship between coral growth, thermal microhabitat, symbionts type, and thermal acclimatization of four species of the Acropora hyacinthus complex in back-reef lagoons in American Samoa. Coral growth was measured from August 2010 to April 2016 using horizontal planar area of coral colonies derived from photographs and in situ maximum width measurements. Despite marked intraspecific variation, we found that planar colony growth rates were significantly different among cryptic species. The highly heat tolerant A. hyacinthus variant "HE" increased in area an average of 2.9% month-1 (0.03 cm average mean radial extension month-1). By contrast, the three less tolerant species averaged 6.1% (0.07 cm average mean radial extension month-1). Planar growth rates were 40% higher on average in corals harboring Clade C versus Clade D symbiont types, although marked inter-colony variation in growth rendered this difference nonsignificant. Planar growth rates for all four species dropped to near zero following a 2015 bleaching event, independent of the visually estimated percent area of bleaching. Within 1 yr, growth rates recovered to previous levels, confirming previous studies that found sublethal effects of thermal stress on coral growth. Long-term studies of individual coral colonies provide an important tool to measure impacts of environmental change and allow integration of coral physiology, genetics, symbionts, and microclimate on reef growth patterns.

  19. Vitamin B12–dependent taurine synthesis regulates growth and bone mass

    Science.gov (United States)

    Roman-Garcia, Pablo; Quiros-Gonzalez, Isabel; Mottram, Lynda; Lieben, Liesbet; Sharan, Kunal; Wangwiwatsin, Arporn; Tubio, Jose; Lewis, Kirsty; Wilkinson, Debbie; Santhanam, Balaji; Sarper, Nazan; Clare, Simon; Vassiliou, George S.; Velagapudi, Vidya R.; Dougan, Gordon; Yadav, Vijay K.

    2014-01-01

    Both maternal and offspring-derived factors contribute to lifelong growth and bone mass accrual, although the specific role of maternal deficiencies in the growth and bone mass of offspring is poorly understood. In the present study, we have shown that vitamin B12 (B12) deficiency in a murine genetic model results in severe postweaning growth retardation and osteoporosis, and the severity and time of onset of this phenotype in the offspring depends on the maternal genotype. Using integrated physiological and metabolomic analysis, we determined that B12 deficiency in the offspring decreases liver taurine production and associates with abrogation of a growth hormone/insulin-like growth factor 1 (GH/IGF1) axis. Taurine increased GH-dependent IGF1 synthesis in the liver, which subsequently enhanced osteoblast function, and in B12-deficient offspring, oral administration of taurine rescued their growth retardation and osteoporosis phenotypes. These results identify B12 as an essential vitamin that positively regulates postweaning growth and bone formation through taurine synthesis and suggests potential therapies to increase bone mass. PMID:24911144

  20. Growth rate change driven by external perturbation in the azuki bean weevil

    CERN Document Server

    Fukano, T

    2003-01-01

    In laboratory experiments we obtain that the apparent growth rate of the population becomes larger than one under the normal condition, triggered by the external perturbation as the removal of individuals. The changed growth rate is stable for a while. We also propose a simple model of population dynamics allowing both matching and mis-matching the trend of the external perturbation, and show that the growth rate of the model population is changeable and stable to some extent.

  1. Growth rate change driven by external perturbation in the azuki bean weevil

    International Nuclear Information System (INIS)

    Fukano, Takao; Gunji, Yukio-Pegio

    2003-01-01

    In laboratory experiments we obtain that the apparent growth rate of the population becomes larger than one under the normal condition, triggered by the external perturbation as the removal of individuals. The changed growth rate is stable for a while. We also propose a simple model of population dynamics allowing both matching and mis-matching the trend of the external perturbation, and show that the growth rate of the model population is changeable and stable to some extent

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

    Science.gov (United States)

    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.

  3. Ergodicity, hidden bias and the growth rate gain

    Science.gov (United States)

    Rochman, Nash D.; Popescu, Dan M.; Sun, Sean X.

    2018-05-01

    Many single-cell observables are highly heterogeneous. A part of this heterogeneity stems from age-related phenomena: the fact that there is a nonuniform distribution of cells with different ages. This has led to a renewed interest in analytic methodologies including use of the ‘von Foerster equation’ for predicting population growth and cell age distributions. Here we discuss how some of the most popular implementations of this machinery assume a strong condition on the ergodicity of the cell cycle duration ensemble. We show that one common definition for the term ergodicity, ‘a single individual observed over many generations recapitulates the behavior of the entire ensemble’ is implied by the other, ‘the probability of observing any state is conserved across time and over all individuals’ in an ensemble with a fixed number of individuals but that this is not true when the ensemble is growing. We further explore the impact of generational correlations between cell cycle durations on the population growth rate. Finally, we explore the ‘growth rate gain’—the phenomenon that variations in the cell cycle duration leads to an improved population-level growth rate—in this context. We highlight that, fundamentally, this effect is due to asymmetric division.

  4. Effect of neutron irradiation on hatching rate of eggs and growth rate of chicken

    International Nuclear Information System (INIS)

    Liu Yubin; Zhao Jide; Liu Shengdian; Xy Xiuwei

    1995-01-01

    It was proved through 3 years of experiments and productions that after the eggs of AA meat chickens being irradiated by 14 MeV fast neutron, the hatching rate and the survival rate as well the weight of commercial chickens increased greatly. In addition it is found that the optimum neutron fluence for hatching and growth rate is 6.2 x 10 5 n·cm -2

  5. CHRONIC UNSTABILITY AND POTENTIAL GROWTH RATE: TURKISH EXPERIENCE, 1960-2006

    Directory of Open Access Journals (Sweden)

    MUSTAFA İSMİHAN

    2013-06-01

    Full Text Available This study investigates the role of macroeconomic instability on potential growth rate of output in Turkey over the period 1960-2006. In doing so, it also attempts to estimate the potential growth rate of Turkish economy over the sample period by using Hodrick-Prescott filter and model based on production function approach. Descriptive and empirical results suggest that Turkish economy suffered from a significant output loss during the chronic instability episodes, between the mid-1970s and 2001. A significant fall in macroeconomic instability has provided the main contribution to the achievement of the recent high growth episode (2002-2006 of Turkish economy. However, in order to continue the desired high growth performance in near future it is necessary to accelerate both human and physical capital formation while preserving stability.

  6. Size- and time-dependent growth properties of human induced pluripotent stem cells in the culture of single aggregate.

    Science.gov (United States)

    Nath, Suman C; Horie, Masanobu; Nagamori, Eiji; Kino-Oka, Masahiro

    2017-10-01

    Aggregate culture of human induced pluripotent stem cells (hiPSCs) is a promising method to obtain high number of cells for cell therapy applications. This study quantitatively evaluated the effects of initial cell number and culture time on the growth of hiPSCs in the culture of single aggregate. Small size aggregates ((1.1 ± 0.4) × 10 1 -(2.8 ± 0.5) × 10 1 cells/aggregate) showed a lower growth rate in comparison to medium size aggregates ((8.8 ± 0.8) × 10 1 -(6.8 ± 1.1) × 10 2 cells/aggregate) during early-stage of culture (24-72 h). However, when small size aggregates were cultured in conditioned medium, their growth rate increased significantly. On the other hand, large size aggregates ((1.1 ± 0.2) × 10 3 -(3.5 ± 1.1) × 10 3 cells/aggregate) showed a lower growth rate and lower expression level of proliferation marker (ki-67) in the center region of aggregate in comparison to medium size aggregate during early-stage of culture. Medium size aggregates showed the highest growth rate during early-stage of culture. Furthermore, hiPSCs proliferation was dependent on culture time because the growth rate decreased significantly during late-stage of culture (72-120 h) at which point collagen type I accumulated on the periphery of aggregate, suggesting blockage of diffusive transport of nutrients, oxygen and metabolites into and out of the aggregates. Consideration of initial cell number and culture time are important to maintain balance between autocrine factors secretion and extracellular matrix accumulation on the aggregate periphery to achieve optimal growth of hiPSCs in the culture of single aggregate. Copyright © 2017 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

  7. Growth, Mortality and Exploitation Rates of Sarotherodon ...

    African Journals Online (AJOL)

    Evans

    ABSTRACT. Sarotherodon melanotheron population of Dominli Lagoon in the Western Region of Ghana was studied for its growth and mortality parameters as well as exploitation rate. The study generally aimed at providing basic information necessary for the assessment and management of the fish stock in the lagoon.

  8. A review on pipeline corrosion, in-line inspection (ILI), and corrosion growth rate models

    International Nuclear Information System (INIS)

    Vanaei, H.R.; Eslami, A.; Egbewande, A.

    2017-01-01

    Pipelines are the very important energy transmission systems. Over time, pipelines can corrode. While corrosion could be detected by in-line inspection (ILI) tools, corrosion growth rate prediction in pipelines is usually done through corrosion rate models. For pipeline integrity management and planning selecting the proper corrosion ILI tool and also corrosion growth rate model is important and can lead to significant savings and safer pipe operation. In this paper common forms of pipeline corrosion, state of the art ILI tools, and also corrosion growth rate models are reviewed. The common forms of pipeline corrosion introduced in this paper are Uniform/General Corrosion, Pitting Corrosion, Cavitation and Erosion Corrosion, Stray Current Corrosion, Micro-Bacterial Influenced Corrosion (MIC). The ILI corrosion detection tools assessed in this study are Magnetic Flux Leakage (MFL), Circumferential MFL, Tri-axial MFL, and Ultrasonic Wall Measurement (UT). The corrosion growth rate models considered in this study are single-value corrosion rate model, linear corrosion growth rate model, non-linear corrosion growth rate model, Monte-Carlo method, Markov model, TD-GEVD, TI-GEVD model, Gamma Process, and BMWD model. Strengths and limitations of ILI detection tools, and also corrosion predictive models with some practical examples are discussed. This paper could be useful for those whom are supporting pipeline integrity management and planning. - Highlights: • Different forms of pipeline corrosion are explained. • Common In-Line Inspection (ILI) tools and corrosion growth rate models are introduced. • Strength and limitations of corrosion growth rate models/ILI tools are discussed. • For pipeline integrity management programs using more than one corrosion growth rate model/ILI tool is suggested.

  9. Physical growth in children with transfusion-dependent thalassemia

    Directory of Open Access Journals (Sweden)

    Harish K Pemde

    2011-02-01

    Full Text Available Harish K Pemde, Jagdish Chandra, Divya Gupta, Varinder Singh, Rajni Sharma, AK DuttaDepartment of Pediatrics, Lady Hardinge Medical College, Kalawati Saran Children's Hospital, New Delhi, IndiaObjective: To describe physical growth and related factors in transfusion-dependent thalassemia patients.Methods: This is a cross-sectional analysis of the records of the patients registered at and being followed up by the Thalassemia Day Care Center (TDCC at Kalawati Saran Children's Hospital, New Delhi, India. Clinical and laboratory parameters were recorded on a spreadsheet for analysis. Clinical parameters included weight, height, sexual maturity ratings, and general and systemic physical examination. Laboratory parameters included pretransfusion hemoglobin (Hb, periodic serum ferritin, and tests for viral markers of human immunodeficiency virus (HIV and hepatitis B and C. Z-scores for weight, height, and body mass index (BMI were calculated using World Health Organization reference data. Statistical analysis was carried out using Microsoft Excel® and Stata® software.Results: Out of 214 patients registered at the TDCC since 2001, 154 were included in this study. The mean age of patients was 9.19 years (range 0.5–20 years. Pretransfusion Hb was well maintained (mean 9.21 g/dL; 95% confidence interval [CI]: 9.06–9.36, but the mean serum ferritin levels were approximately three times (3112 ng/mL the desired value despite the patients being on deferiprone (72% or deferasirox (25%. One-third (33.11% of the patients had short stature, 13% were thin, and 10.82% were very thin (BMI z-score <-3. No patient was overweight or obese. Linear regression coefficient showed that for every 1-year increase in age, the mean ferritin value increased by 186.21 pg/mL (95% CI: 143.31–228.27. Height z-scores had significant correlation with mean ferritin levels, whereas correlation with mean pretransfusion Hb was not significant statistically. Mean ferritin levels

  10. Stainless steels: general considerations and rates of crack growth

    International Nuclear Information System (INIS)

    Chator, T.

    1992-05-01

    This report describes the different types of stainless steels, and presents the laws governing the rates of crack growth for several stainless steels extensively used for the manufacture of structures in nuclear power plants. The laws are not discussed in detail in the report. After a brief review of the development of stainless steels, the main categories of stainless steels, their mechanical characteristics and corrosion resistance, are presented. Finally, the rates of crack growth are presented for various stainless steels, mainly austenitic. The study overall aim is an investigation of the cracking in the 900 MWe primary pump thermal barriers and shafts

  11. DETERMINATION OF THE SPECIFIC GROWTH RATE ON ...

    African Journals Online (AJOL)

    Sewage generation is one of the dense problems Nigerians encounter on daily bases, mostly at the urbanized area where factories and industries are located. This paper is aimed at determining the specific growth rate “K” of biological activities on cassava wastewater during degradation using Michaelis-Menten Equation.

  12. Mathematical model for predicting molecular-beam epitaxy growth rates for wafer production

    International Nuclear Information System (INIS)

    Shi, B.Q.

    2003-01-01

    An analytical mathematical model for predicting molecular-beam epitaxy (MBE) growth rates is reported. The mathematical model solves the mass-conservation equation for liquid sources in conical crucibles and predicts the growth rate by taking into account the effect of growth source depletion on the growth rate. Assumptions made for deducing the analytical model are discussed. The model derived contains only one unknown parameter, the value of which can be determined by using data readily available to MBE growers. Procedures are outlined for implementing the model in MBE production of III-V compound semiconductor device wafers. Results from use of the model to obtain targeted layer compositions and thickness of InP-based heterojunction bipolar transistor wafers are presented

  13. Correlation between TCA cycle flux and glucose uptake rate during respiro-fermentative growth of Saccharomyces cerevisiae.

    Science.gov (United States)

    Heyland, Jan; Fu, Jianan; Blank, Lars M

    2009-12-01

    Glucose repression of the tricarboxylic acid (TCA) cycle in Saccharomyces cerevisiae was investigated under different environmental conditions using (13)C-tracer experiments. Real-time quantification of the volatile metabolites ethanol and CO(2) allowed accurate carbon balancing. In all experiments with the wild-type, a strong correlation between the rates of growth and glucose uptake was observed, indicating a constant yield of biomass. In contrast, glycerol and acetate production rates were less dependent on the rate of glucose uptake, but were affected by environmental conditions. The glycerol production rate was highest during growth in high-osmolarity medium (2.9 mmol g(-1) h(-1)), while the highest acetate production rate of 2.1 mmol g(-1) h(-1) was observed in alkaline medium of pH 6.9. Under standard growth conditions (25 g glucose l(-1) , pH 5.0, 30 degrees C) S. cerevisiae had low fluxes through the pentose phosphate pathway and the TCA cycle. A significant increase in TCA cycle activity from 0.03 mmol g(-1) h(-1) to about 1.7 mmol g(-1) h(-1) was observed when S. cerevisiae grew more slowly as a result of environmental perturbations, including unfavourable pH values and sodium chloride stress. Compared to experiments with high glucose uptake rates, the ratio of CO(2) to ethanol increased more than 50 %, indicating an increase in flux through the TCA cycle. Although glycolysis and the ethanol production pathway still exhibited the highest fluxes, the net flux through the TCA cycle increased significantly with decreasing glucose uptake rates. Results from experiments with single gene deletion mutants partially impaired in glucose repression (hxk2, grr1) indicated that the rate of glucose uptake correlates with this increase in TCA cycle flux. These findings are discussed in the context of regulation of glucose repression.

  14. Growth rate in the dynamical dark energy models

    International Nuclear Information System (INIS)

    Avsajanishvili, Olga; Arkhipova, Natalia A.; Samushia, Lado; Kahniashvili, Tina

    2014-01-01

    Dark energy models with a slowly rolling cosmological scalar field provide a popular alternative to the standard, time-independent cosmological constant model. We study the simultaneous evolution of background expansion and growth in the scalar field model with the Ratra-Peebles self-interaction potential. We use recent measurements of the linear growth rate and the baryon acoustic oscillation peak positions to constrain the model parameter α that describes the steepness of the scalar field potential. (orig.)

  15. Growth rate in the dynamical dark energy models.

    Science.gov (United States)

    Avsajanishvili, Olga; Arkhipova, Natalia A; Samushia, Lado; Kahniashvili, Tina

    Dark energy models with a slowly rolling cosmological scalar field provide a popular alternative to the standard, time-independent cosmological constant model. We study the simultaneous evolution of background expansion and growth in the scalar field model with the Ratra-Peebles self-interaction potential. We use recent measurements of the linear growth rate and the baryon acoustic oscillation peak positions to constrain the model parameter [Formula: see text] that describes the steepness of the scalar field potential.

  16. Are elderly dependency ratios associated with general population suicide rates?

    Science.gov (United States)

    Shah, Ajit

    2011-05-01

    The elderly population size is increasing worldwide due to falling birth rates and increasing life expectancy. It has been hypothesized that as the elderly dependency ratio (the ratio of those over the age of 65 years to those under 65) increases, there will be fewer younger people available to care for older people and this, in turn, will increase the burden on younger carers with increased levels of psychiatric morbidity leading to an increase in general population suicide rates. A cross-national study examining the relationship between elderly dependency ratios and general population suicide rates was conducted using data from the World Health Organization and the United Nations websites. The main findings were of a significant and independent positive correlation between elderly dependency ratios and general population suicide rates in both genders. The contribution of cross-national differences in psychiatric morbidity in younger carers on general population suicide rates requires further study. The prevalence of psychiatric morbidity in younger carers of older people should be examined by: (i) cross-national studies using standardized measures of psychiatric morbidity that are education-free, culture-fair and language-fair; and (ii) within-country longitudinal studies with changing elderly dependency ratios over time.

  17. Dose rate and SDD dependence of commercially available diode detectors

    International Nuclear Information System (INIS)

    Saini, Amarjit S.; Zhu, Timothy C.

    2004-01-01

    The dose-rate dependence of commercially available diode detectors was measured under both high instantaneous dose-rate (pulsed) and low dose rate (continuous, Co-60) radiation. The dose-rate dependence was measured in an acrylic miniphantom at a 5-cm depth in a 10x10 cm 2 collimator setting, by varying source-to-detector distance (SDD) between at least 80 and 200 cm. The ratio of a normalized diode reading to a normalized ion chamber reading (both at SDD=100 cm) was used to determine diode sensitivity ratio for pulsed and continuous radiation at different SDD. The inverse of the diode sensitivity ratio is defined as the SDD correction factor (SDD CF). The diode sensitivity ratio increased with increasing instantaneous dose rate (or decreasing SDD). The ratio of diode sensitivity, normalized to 4000 cGy/s, varied between 0.988 (1490 cGy/s)-1.023 (38 900 cGy/s) for unirradiated n-type Isorad Gold, 0.981 (1460 cGy/s)-1.026 (39 060 cGy/s) for unirradiated QED Red (n type), 0.972 (1490 cGy/s)-1.068 (38 900 cGy/s) for preirradiated Isorad Red (n type), 0.985 (1490 cGy/s)-1.012 (38 990 cGy/s) for n-type Pt-doped Isorad-3 Gold, 0.995 (1450 cGy/s)-1.020 (21 870 cGy/s) for n-type Veridose Green, 0.978 (1450 cGy/s)-1.066 (21 870 cGy/s) for preirradiated Isorad-p Red, 0.994 (1540 cGy/s)-1.028 (17 870 cGy/s) for p-type preirradiated QED, 0.998 (1450 cGy/s)-1.003 (21 870 cGy/s) for the p-type preirradiated Scanditronix EDP20 3G , and 0.998 (1490 cGy/s)-1.015 (38 880 cGy/s) for Scanditronix EDP10 3G diodes. The p-type diodes do not always show less dose-rate dependence than the n-type diodes. Preirradiation does not always reduce diode dose-rate dependence. A comparison between the SDD dependence measured at the surface of a full scatter phantom and that in a miniphantom was made. Using a direct adjustment of radiation pulse height, we concluded that the SDD dependence of diode sensitivity can be explained by the instantaneous dose-rate dependence if sufficient buildup is

  18. Flow-dependent growth in the zooxanthellate soft coral Sinularia flexibilis

    NARCIS (Netherlands)

    Khalesi, M.K.; Beeftink, H.H.; Wijffels, R.H.

    2007-01-01

    Growth characteristics of colonies of the branching zooxanthellate octocoral Sinularia flexibilis, with potential pharmaceutical importance, were measured over a range of water velocities. The highest mean specific growth rate (¿ d¿ 1) was found at a flow velocity of 11 cm s¿ 1. An optimal range of

  19. Diagnostic Accuracy of Growth Rate in Differentiating Etiologies of Short Stature in Children

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Alaei

    2016-08-01

    Full Text Available Background  Short stature is a manifestation of a wide variety of conditions that some of which may be amenable to timely treatment and a suboptimal growth rate may be an early marker pointing to the cause of growth retardation. This study was conducted to evaluate the diagnostic utility of growth rate in differential diagnosis of children with short stature. Materials and Methods All children between the ages of 2 and 18 years who visited in pediatric endocrinology clinic in a five years period were recruited in a prospective cohort study. Children with standing height Results One hundred forty three patients fulfilled the inclusion criteria. Mean follow up period was 14.4±10.9 months. Etiologies of short stature were: constitutional growth delay (CGD 46.9%, familial short stature (FSS 28.7%, hypothyroidism 4.2%, growth hormone deficiency (GHD 4.2% and miscellaneous causes in 16% of patients.  Mean Z- score for children with constitutional growth delay was -2.3±0.69, in familial short stature was -2.3±0.65 and for other condition was -2.7±1.49. There was a meaningful statistical correlation between growth rate and etiology of short stature (P0.05. Conclusion There was significant difference in growth rate between children with constitutional growth delay and familial short stature in comparing to short stature due to endocrine problem and other etiologies. Assessment of growth rate has some utility in diagnosing the etiology of short stature.

  20. Daily changes in temperature, not the circadian clock, regulate growth rate in Brachypodium distachyon.

    Directory of Open Access Journals (Sweden)

    Dominick A Matos

    Full Text Available 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.

  1. Dispersion relation and growth rate in a Cherenkov free electron laser: Finite axial magnetic field

    International Nuclear Information System (INIS)

    Kheiri, Golshad; Esmaeilzadeh, Mahdi

    2013-01-01

    A theoretical analysis is presented for dispersion relation and growth rate in a Cherenkov free electron laser with finite axial magnetic field. It is shown that the growth rate and the resonance frequency of Cherenkov free electron laser increase with increasing axial magnetic field for low axial magnetic fields, while for high axial magnetic fields, they go to a saturation value. The growth rate and resonance frequency saturation values are exactly the same as those for infinite axial magnetic field approximation. The effects of electron beam self-fields on growth rate are investigated, and it is shown that the growth rate decreases in the presence of self-fields. It is found that there is an optimum value for electron beam density and Lorentz relativistic factor at which the maximum growth rate can take place. Also, the effects of velocity spread of electron beam are studied and it is found that the growth rate decreases due to the electron velocity spread

  2. Long-term dependence in exchange rates

    Directory of Open Access Journals (Sweden)

    A. Karytinos

    2000-01-01

    Full Text Available The extent to which exchange rates of four major currencies against the Greek Drachma exhibit long-term dependence is investigated using a R/S analysis testing framework. We show that both classic R/S analysis and the modified R/S statistic if enhanced by bootstrapping techniques can be proven very reliable tools to this end. Our findings support persistence and long-term dependence with non-periodic cycles for the Deutsche Mark and the French Franc series. In addition a noisy chaos explanation is favored over fractional Brownian motion. On the contrary, the US Dollar and British Pound were found to exhibit a much more random behavior and lack of any long-term structure.

  3. Spatial distribution of soda straws growth rates of the Coufin Cave (Vercors, France

    Directory of Open Access Journals (Sweden)

    Perrette Yves

    2010-07-01

    Full Text Available The Choranche Cave system (Vercors, France is an excellent locality for measuring the growth rates of large numbers soda straws. This is especially the case for the Coufin Cave, as enlargement of the cave entrance in 1875 led to a change in stalactite color from brown to white, thus providing a reliable chronomarker. The date of this brown-to-white calcite transition has been confirmed by lamina counting. We measured and georeferenced the growth-lengths of 306 soda straws in a 1m2 area of the roof of the Coufin Cave entrance chamber. Because of the very slow and sometimes inexistent water feeding of those stalactites, hydrochemistry analysis were not achieved and drop rate effect on growth were neglected; this study is based on a geomorphological and geostatistical work. By measuring a large number of soda straws in a very small area for which most of the parameters affecting stalactite growth could be considered uniform, and because flow rates are very slow (frequencies are always superior to 1 drop per half hour, we could ascribe differences in growth rates to variations in the global increase of water flow through the unsaturated matrix. Statistical and geostatistical analyses of the measurements showed that this set of similarly shaped stalactites actually consisted of three Gaussian populations with different mean growth rates: fast growth rate (FGR- mean of 0.92 mm.y-1, medium growth rate (MGR- mean of 0.47 mm.y-1 and low growth rate (LGR- 0.09 mm.y-1. Plotting the lengths and spatial distribution of the 20 longest FGR soda straws revealed that there is a rough pattern to the water flow through the cave roof. Even if no direction is statisticaly different from others, the observed directional pattern is consistent with local and regional tectonic observations. Plots of the spatial distribution of the soda straws show that FGR soda straws follow lines of regional geological stress, whereas MGR and LGR soda straws are more dispersed.

  4. Tumor cell proliferation kinetics and tumor growth rate

    Energy Technology Data Exchange (ETDEWEB)

    Tubiana, M

    1989-01-01

    The present knowledge on the growth rate and the proliferation kinetics of human tumor is based on the measurement of the tumor doubling times (DT) in several hundred patients and on the determination of the proportion of proliferating cells with radioactive thymidine or by flow cytometry in large numbers of patients. The results show that the DT of human tumor varies widely, from less than one week to over one year with a median value of approximately 2 months. The DTs are significantly correlated with the histological type. They depend upon (1) the duration of the cell cycle whose mean duration is 2 days with small variations from tumor to tumor, (2) the proportion of proliferating cells and consequently the cell birth rate which varies widely among tumors and which is significantly correlated to the DT, (3) the cell loss factors which also vary widely and which are the greatest when proliferation is most intensive. These studies have several clinical implications: (a) they have further increased our understanding of the natural history of human tumor, (b) they have therapeutic implications since tumor responsiveness and curability by radiation and drugs are strongly influenced by the cell kinetic parameters of the tumor, (c) the proportion of proliferating cells is of great prognostic value in several types of human cancers. The investigation of the molecular defects, which are correlated with the perturbation of control of cell proliferation, should lead to significant fundamental and therapeutic advances. (orig.).

  5. Variability in growth rates of larval haddock in the northern North Sea

    DEFF Research Database (Denmark)

    Gallego, A.; Heath, M.R.; Basford, D.J.

    1999-01-01

    of the spring plankton production bloom, and a likely explanation for the absence of environmental effects on larval growth was high food availability and larval feeding rates. Nevertheless, differences in growth were observed between cohorts, with larvae hatched later in the spring displaying higher growth...... at age than those hatched earlier. Particle-tracking modelling suggested that differences in temperature history between cohorts, on their own or compounded by a potential interaction between temperature and the development of plankton production, may explain the higher growth rate of the larvae hatched...

  6. Gross domestic product growth rates as confined Lévy flights: Towards a unifying theory of economic growth rate fluctuations

    Science.gov (United States)

    Lera, Sandro Claudio; Sornette, Didier

    2018-01-01

    A model that combines economic growth rate fluctuations at the microscopic and macroscopic levels is presented. At the microscopic level, firms are growing at different rates while also being exposed to idiosyncratic shocks at the firm and sector levels. We describe such fluctuations as independent Lévy-stable fluctuations, varying over multiple orders of magnitude. These fluctuations are aggregated and measured at the macroscopic level in averaged economic output quantities such as GDP. A fundamental question is thereby to what extent individual firm size fluctuations can have a noticeable impact on the overall economy. We argue that this question can be answered by considering the Lévy fluctuations as embedded in a steep confining potential well, ensuring nonlinear mean-reversal behavior, without having to rely on microscopic details of the system. The steepness of the potential well directly controls the extent to which idiosyncratic shocks to firms and sectors are damped at the level of the economy. Additionally, the theory naturally accounts for business cycles, represented in terms of a bimodal economic output distribution and thus connects two so far unrelated fields in economics. By analyzing 200 years of U.S. gross domestic product growth rates, we find that the model is in good agreement with the data.

  7. Plasmin-driven fibrinolysis facilitates skin tumor growth in a gender-dependent manner

    DEFF Research Database (Denmark)

    Hald, Andreas; Eickhardt, Hanne; Maerkedahl, Rasmus Baadsgaard

    2012-01-01

    deficiency was due to thrombosis and lost patency of the tumor vasculature, resulting in tumor necrosis. The connection between plasmin-dependent fibrinolysis, vascular patency, and tumor growth was further substantiated as the effect of plasminogen deficiency on tumor growth could be reverted...

  8. Tax Rates, Tax Evasion, and Growth in a Multi-period Economy

    OpenAIRE

    Jordi Caballé; Judith Panadés

    2007-01-01

    We extend the basic tax evasion model to a multi-period economy exhibiting sustained growth. When individuals conceal part of their true income from the tax authority, they face the risk of being audited and hence of paying the corresponding fine. Both taxes and fines determine individual saving and the rate of capital accumulation. We show that, if the penalty imposed on tax evaders is proportional to the amount of evaded taxes, then the growth rate is decreasing in the tax rate. However, th...

  9. Discrete dislocation plasticity analysis of loading rate-dependent static friction.

    Science.gov (United States)

    Song, H; Deshpande, V S; Van der Giessen, E

    2016-08-01

    From a microscopic point of view, the frictional force associated with the relative sliding of rough surfaces originates from deformation of the material in contact, by adhesion in the contact interface or both. We know that plastic deformation at the size scale of micrometres is not only dependent on the size of the contact, but also on the rate of deformation. Moreover, depending on its physical origin, adhesion can also be size and rate dependent, albeit different from plasticity. We present a two-dimensional model that incorporates both discrete dislocation plasticity inside a face-centred cubic crystal and adhesion in the interface to understand the rate dependence of friction caused by micrometre-size asperities. The friction strength is the outcome of the competition between adhesion and discrete dislocation plasticity. As a function of contact size, the friction strength contains two plateaus: at small contact length [Formula: see text], the onset of sliding is fully controlled by adhesion while for large contact length [Formula: see text], the friction strength approaches the size-independent plastic shear yield strength. The transition regime at intermediate contact size is a result of partial de-cohesion and size-dependent dislocation plasticity, and is determined by dislocation properties, interfacial properties as well as by the loading rate.

  10. [Growth rate and bone maturation in celiac disease (author's transl)].

    Science.gov (United States)

    Martínez Sopena, M J; Calvo Romero, M C; Bedate Calderón, P; Alonso Franch, M; Sánchez Villares, E

    1978-05-01

    The growth and bone maturation of 43 celiac patients were analyzed. A significant correlation between gluten intake and growth rate was found. The authors suggest this is a good parameter to advise the best moment to make the control biopsie and the provocation test.

  11. Modeling tumor growth in the presence of a therapy with an effect on rate growth and variability by means of a modified Gompertz diffusion process.

    Science.gov (United States)

    Román-Román, Patricia; Román-Román, Sergio; Serrano-Pérez, Juan José; Torres-Ruiz, Francisco

    2016-10-21

    In experimental studies on tumor growth, whenever the time evolution of the relative volume of a tumor in an untreated (control) group can be fitted by a Gompertz diffusion process there is a possibility that an antiproliferative therapy, which modifies the growth rate of the process that fits the treated group, may also affect its variability. The present paper proposes several procedures for the estimation of the time function included in the infinitesimal variance of the new process, as well as the time function affecting the growth rate (which is included in the infinitesimal mean). Also, a hypothesis testing is designed to confirm or refute the need for including such a time-dependent function in the infinitesimal variance. In order to validate and compare the proposed procedures a simulation study has been carried out. In addition, a proposal is made for a strategy aimed at finding the optimal combination of procedures for each case. A real data application concerning the effects of cisplatin on a patient-derived xenograft (PDX) tumor model showcases the advantages of this model over others that have been used in the past. Copyright © 2016 Elsevier Ltd. All rights reserved.

  12. Trade-offs between microbial growth phases lead to frequency-dependent and non-transitive selection.

    Science.gov (United States)

    Manhart, Michael; Adkar, Bharat V; Shakhnovich, Eugene I

    2018-02-14

    Mutations in a microbial population can increase the frequency of a genotype not only by increasing its exponential growth rate, but also by decreasing its lag time or adjusting the yield (resource efficiency). The contribution of multiple life-history traits to selection is a critical question for evolutionary biology as we seek to predict the evolutionary fates of mutations. Here we use a model of microbial growth to show that there are two distinct components of selection corresponding to the growth and lag phases, while the yield modulates their relative importance. The model predicts rich population dynamics when there are trade-offs between phases: multiple strains can coexist or exhibit bistability due to frequency-dependent selection, and strains can engage in rock-paper-scissors interactions due to non-transitive selection. We characterize the environmental conditions and patterns of traits necessary to realize these phenomena, which we show to be readily accessible to experiments. Our results provide a theoretical framework for analysing high-throughput measurements of microbial growth traits, especially interpreting the pleiotropy and correlations between traits across mutants. This work also highlights the need for more comprehensive measurements of selection in simple microbial systems, where the concept of an ordinary fitness landscape breaks down. © 2018 The Author(s).

  13. Growth, exchange rates and trade in Brazil: a structuralist post-Keynesian approach

    Directory of Open Access Journals (Sweden)

    Nelson H. Barbosa Filho

    2004-01-01

    Full Text Available This paper presents a structuralist post-Keynesian analysis of trade adjustment in Brazil. Based on the concept of the balance-of-payments (BoP constraint on growth, the paper investigates the relationship between income growth and real-exchange-rate devaluation necessary to adjust trade to a foreign-exchange constraint. The main result is that, with price-inelastic and income-elastic imports and based on its trade structure in 2002, Brazil may have to compensate an additional 1% of income growth with approximately 7% of real-exchange-rate devaluation in order to keep its trade balance stable in relation to GDP in the near future. Moreover, the trade parameters of Brazil seem to be unfavorable to growth with stable trade, that is, even moderate rates of GDP expansion lead to a substantial increase of imports and, therefore, require an also substantial devaluation of the real exchange rate to avoid a deterioration of the trade balance.

  14. Growth, exchange rates and trade in Brazil: a structuralist post Keynesian approach

    Directory of Open Access Journals (Sweden)

    Nelson H. Barbosa Filho

    2009-06-01

    Full Text Available This paper presents a structuralist post-Keynesian analysis of trade adjustment in Brazil. Based on the concept of the balance-of-payments (BoP constraint on growth, the paper investigates the relationship between income growth and real-exchange-rate devaluation necessary to adjust trade to a foreign-exchange constraint. The main result is that, with price-inelastic and income-elastic imports and based on its trade structure in 2002, Brazil may have to compensate an additional 1% of income growth with approximately 7% of real-exchange-rate devaluation in order to keep its trade balance stable in relation to GDP in the near future. Moreover, the trade parameters of Brazil seem to be unfavorable to growth with stable trade, that is, even moderate rates of GDP expansion lead to a substantial increase of imports and, therefore, require an also substantial devaluation of the real exchange rate to avoid a deterioration of the trade balance.

  15. Effect of specimen geometry on the variability in fatigue crack growth rate

    International Nuclear Information System (INIS)

    Tsuji, Hirokazu; Nakajima, Hajime; Kondo, Tatsuo

    1982-02-01

    Fatigue crack growth tests on SA 533 grade B class 1 steel were conducted in air with both contoured double cantilever beam (CDCB) specimens and compact-tension (CT) specimens for comparison, which corresponded to the ΔK constant and ΔK increasing fatigue tests respectively. The variability of the measured values was examined statistically, and possible sources of the determined variability were discussed. The variability in the ΔK increasing fatigue tests with the CT specimens was found to be substantially greater than that in the ΔK constant fatigue tests with the CDCB specimens employed in the present study. In addition, the width of the scatter as well as in the degree of deviation from the expected linearity in da/dN versus ΔK plots were found to be varied depending on the level of ΔK in the CT specimen. Based on the results, a conclusion was drawn that constant ΔK type tests should be preferred in the tests where accuracy and reproducibility of crack growth rate measurement was of particular importance. (author)

  16. The neurite growth inhibitory effects of soluble TNFα on developing sympathetic neurons are dependent on developmental age.

    Science.gov (United States)

    Nolan, Aoife M; Collins, Louise M; Wyatt, Sean L; Gutierrez, Humberto; O'Keeffe, Gerard W

    2014-01-01

    During development, the growth of neural processes is regulated by an array of cellular and molecular mechanisms which influence growth rate, direction and branching. Recently, many members of the TNF superfamily have been shown to be key regulators of neurite growth during development. The founder member of this family, TNFα can both promote and inhibit neurite growth depending on the cellular context. Specifically, transmembrane TNFα promotes neurite growth, while soluble TNFα inhibits it. While the growth promoting effects of TNFα are restricted to a defined developmental window of early postnatal development, whether the growth inhibitory effects of soluble TNFα occur throughout development is unknown. In this study we used the extensively studied, well characterised neurons of the superior cervical ganglion to show that the growth inhibitory effects of soluble TNFα are restricted to a specific period of late embryonic and early postnatal development. Furthermore, we show that this growth inhibitory effect of soluble TNFα requires NF-κB signalling at all developmental stages at which soluble TNFα inhibits neurite growth. These findings raise the possibility that increases in the amount of soluble TNFα in vivo, for example as a result of maternal inflammation, could negatively affect neurite growth in developing neurons at specific stages of development. Copyright © 2015 International Society of Differentiation. Published by Elsevier B.V. All rights reserved.

  17. Identification of Toxoplasma gondii cAMP dependent protein kinase and its role in the tachyzoite growth.

    Directory of Open Access Journals (Sweden)

    Hitomi Kurokawa

    Full Text Available cAMP-dependent protein kinase (PKA has been implicated in the asexual stage of the Toxoplasma gondii life cycle through assaying the effect of a PKA-specific inhibitor on its growth rate. Since inhibition of the host cell PKA cannot be ruled out, a more precise evaluation of the role of PKA, as well as characterization of the kinase itself, is necessary.The inhibitory effects of two PKA inhibitors, H89, an ATP-competitive chemical inhibitor, and PKI, a substrate-competitive mammalian natural peptide inhibitor, were estimated. In the in vitro kinase assay, the inhibitory effect of PKI on a recombinant T. gondii PKA catalytic subunit (TgPKA-C was weaker compared to that on mammalian PKA-C. In a tachyzoite growth assay, PKI had little effect on the growth of tachyzoites, whereas H89 strongly inhibited it. Moreover, T. gondii PKA regulatory subunit (TgPKA-R-overexpressing tachyzoites showed a significant growth defect.Our data suggest that PKA plays an important role in the growth of tachyzoites, and the inhibitory effect of substrate-competitive inhibitor PKI on T. gondii PKA was low compared to that of the ATP competitive inhibitor H89.

  18. Influence of water chemistry on IGSCC growth rate of SUS316 under high temperature water

    International Nuclear Information System (INIS)

    Fukumura, Takuya; Terachi, Takumi; Arioka, Koji

    2005-01-01

    The influence of the environment on intergranular stress corrosion crack behavior was examined by performing tensile tests in high-temperature water using cold-water non-sensitized 316 stainless steel. In the constant elongation test, the crack growth rate showed a clear environmental dependence on the concentration of dissolved hydrogen, boric acid and lithium, but no such environmental dependence was observed in the compact tension test. Regarding the influence of the environment on the intergranular stress corrosion crack behavior of non-sensitized 316 stainless steel, it is considered that the environmental factors of dissolved hydrogen (3-45 cc/kgH 2 O), boric acid (500-3500 ppm) and lithium (0.05-10 ppm) greatly affect the initiation process but do not significantly affect the propagation process. (author)

  19. A Conceptual Model for Projecting Coccolithophorid Growth, Calcification and Photosynthetic Carbon Fixation Rates in Response to Global Ocean Change

    Directory of Open Access Journals (Sweden)

    Natasha A. Gafar

    2018-01-01

    Full Text Available Temperature, light and carbonate chemistry all influence the growth, calcification and photosynthetic rates of coccolithophores to a similar degree. There have been multiple attempts to project the responses of coccolithophores to changes in carbonate chemistry, but the interaction with light and temperature remains elusive. Here we devise a simple conceptual model to derive a fit equation for coccolithophorid growth, photosynthetic and calcification rates in response to simultaneous changes in carbonate chemistry, temperature and light conditions. The fit equation is able to account for up to 88% of the variability in measured metabolic rates. Equation projections indicate that temperature, light and carbonate chemistry all have different modulating effects on both optimal growth conditions and the sensitivity of responses to extreme environmental conditions. Calculations suggest that a single extreme environmental condition (CO2, temperature, light will reduce maximum rates regardless of how optimal the other environmental conditions may be. Thus, while the response of coccolithophores to ocean change depends on multiple variables, the one which is least optimal will have the most impact on overall rates. Finally, responses to ocean change are usually reported in terms of cellular rates. However, changes in cellular rates can be a poor predictor for assessing changes in production at the community level. We therefore introduce a new metric, the calcium carbonate production potential (CCPP, which combines the independent effects of changes in growth rate and cellular calcium carbonate content to assess how environmental changes will impact coccolith production. Direct comparison of CO2 impacts on cellular CaCO3 production rates and CCPP shows that while the former is still at 45% of its pre-industrial capacity at 1,000 μatm, the latter is reduced to 10%.

  20. The time dependence of rate constants of esub(aq)sup(-) reactions

    International Nuclear Information System (INIS)

    Burcl, R.; Byakov, V.M.; Grafutin, V.I.

    1982-01-01

    Published data about the time dependence of rate constants k(esub(aq)sup(-)+Ac) of esub(aq)sup(-) reactions with the acceptor Ac are analyzed, using the results of rate constant k(Ps+Ac) measurements for positronium reactions. It is shown that neither esub(aq)sup(-) nor Ps reaction rate constants depend on time in the observable range. Experimentally found concentration dependence of k(esub(aq)sup(-)+Ac) is due to other factors, connected with the existence of electric charge of esub(aq)sup(-), e.g. ionic strength, tunnelling effect etc. (author)

  1. Time-dependent integral transport equation kernels, leakage rates and collision rates for plane and spherical geometry

    International Nuclear Information System (INIS)

    Henderson, D.L.

    1987-01-01

    Time-dependent integral transport equation flux and current kernels for plane and spherical geometry are derived for homogeneous media. Using the multiple collision formalism, isotropic sources that are delta distributions in time are considered for four different problems. The plane geometry flux kernel is applied to a uniformly distributed source within an infinite medium and to a surface source in a semi-infinite medium. The spherical flux kernel is applied to a point source in an infinite medium and to a point source at the origin of a finite sphere. The time-dependent first-flight leakage rates corresponding to the existing steady state first-flight escape probabilities are computed by the Laplace transform technique assuming a delta distribution source in time. The case of a constant source emitting neutrons over a time interval, Δt, for a spatially uniform source is obtained for a slab and a sphere. Time-dependent first-flight leakage rates are also determined for the general two region spherical medium problem for isotropic sources with a delta distribution in time uniformly distributed throughout both the inner and outer regions. The time-dependent collision rates due to the uncollided neutrons are computed for a slab and a sphere using the time-dependent first-flight leakage rates and the time-dependent continuity equation. The case of a constant source emitting neutrons over a time interval, Δt, is also considered

  2. Last Five Years Pakistan Economic Growth Rate GDP And Its Comparison With China India And Bangladesh

    Directory of Open Access Journals (Sweden)

    Abdul Rehman

    2015-01-01

    Full Text Available Abstract This paper formulates and reviews Pakistans last five years economic growth rate and its comparison with the growth rate of China India and Bangladesh. As growth rate the amount of increment of a specific variable has gained within a specific period of time and context. In fact economic growth rate provides general direction and magnitude of growth for overall economy.

  3. Capital accumulation, structural change and real exchange rate in a Keynesian-Structuralist growth model

    Directory of Open Access Journals (Sweden)

    Oreiro José Luis

    2015-01-01

    Full Text Available The aim of this paper is to show at theoretical level that maintaining a competitive real exchange rate positively affects the economic growth of developing countries by means of a Keynesian-Structuralist model that combines elements of Kaleckian growth models with the balance of payments constrained growth models pioneered developed by Thirlwall. In this setting, the level of real exchange rate is capable, due to its effect over capital accumulation, to induce a structural change in the economy, making endogenous income elasticities of exports and imports. For reasonable parameter values it is shown that in steady-state growth there is two long-run equilibrium values for real exchange rate, one that corresponds to an under-valued currency and another that corresponds to an over-valued currency. If monetary authorities run exchange rate policy in order to target a competitive level for real exchange rate, than under-valued equilibrium is stable and the economy will show a high growth rate in the long-run.

  4. Variation in relative growth rate and growth traits in wild and cultivated Capsicum accessions grown under different temperatures

    NARCIS (Netherlands)

    Swart, de E.A.M.; Marcelis, L.F.M.; Voorrips, R.E.

    2006-01-01

    Differences in environmental conditions are known to influence plant growth and growth-related traits. The aim of this study was to identify the variation in relative growth rate (RGR), and its underlying physiological and morphological traits, in a group of ten wild and cultivated Capsicum

  5. The radiation swelling effect on fracture properties and fracture mechanisms of irradiated austenitic steels. Part II. Fatigue crack growth rate

    Energy Technology Data Exchange (ETDEWEB)

    Margolin, B., E-mail: margolinbz@yandex.ru; Minkin, A.; Smirnov, V.; Sorokin, A.; Shvetsova, V.; Potapova, V.

    2016-11-15

    The experimental data on the fatigue crack growth rate (FCGR) have been obtained for austenitic steel of 18Cr-10Ni-Ti grade (Russian analog of AISI 321 steel) irradiated up to neutron dose of 150 dpa with various radiation swelling. The performed study of the fracture mechanisms for cracked specimens under cyclic loading has explained why radiation swelling affects weakly FCGR unlike its effect on fracture toughness. Mechanical modeling of fatigue crack growth has been carried out and the dependencies for prediction of FCGR in irradiated austenitic steel with and with no swelling are proposed and verified with the obtained experimental results. As input data for these dependencies, FCGR for unirradiated steel and the tensile mechanical properties for unirradiated and irradiated steels are used.

  6. Coral growth rates revisited after 31 years: what is causing lower extension rates in Acropora palmata?

    NARCIS (Netherlands)

    Bak, R.P.M.; Nieuwland, G.; Meesters, H.W.G.

    2009-01-01

    Linear extension of branches in the same Acropora palmata (Lamarck, 1816) population in Curaçao was measured, employing exactly the same methods, in 1971-1973 and in 2002-2004, and the resulting coral growth rates are compared. Linear growth shows the same pattern over seasons in both periods with

  7. The kinetics of ice-lens growth in porous media

    KAUST Repository

    Style, Robert W.; Peppin, Stephen S. L.

    2012-01-01

    -growth (heave) rates. This explains why many previous models predict ice-growth rates that are much larger than those seen in experiments. We derive an explicit formula for the ice-growth rate in a given porous medium, and show that this only depends

  8. Latent Growth Modeling of nursing care dependency of acute neurological inpatients.

    Science.gov (United States)

    Piredda, M; Ghezzi, V; De Marinis, M G; Palese, A

    2015-01-01

    Longitudinal three-time point study, addressing how neurological adult patient care dependency varies from the admission time to the 3rd day of acute hospitalization. Nursing care dependency was measured with the Care Dependency Scale (CDS) and a Latent Growth Modeling approach was used to analyse the CDS trend in 124 neurosurgical and stroke inpatients. Care dependence followed a decreasing linear trend. Results can help nurse-managers planning an appropriate amount of nursing care for acute neurological patients during their initial stage of hospitalization. Further studies are needed aimed at investigating the determinants of nursing care dependence during the entire in-hospital stay.

  9. Density regulation in Northeast Atlantic fish populations: Density dependence is stronger in recruitment than in somatic growth.

    Science.gov (United States)

    Zimmermann, Fabian; Ricard, Daniel; Heino, Mikko

    2018-05-01

    Population regulation is a central concept in ecology, yet in many cases its presence and the underlying mechanisms are difficult to demonstrate. The current paradigm maintains that marine fish populations are predominantly regulated by density-dependent recruitment. While it is known that density-dependent somatic growth can be present too, its general importance remains unknown and most practical applications neglect it. This study aimed to close this gap by for the first time quantifying and comparing density dependence in growth and recruitment over a large set of fish populations. We fitted density-dependent models to time-series data on population size, recruitment and age-specific weight from commercially exploited fish populations in the Northeast Atlantic Ocean and the Baltic Sea. Data were standardized to enable a direct comparison within and among populations, and estimated parameters were used to quantify the impact of density regulation on population biomass. Statistically significant density dependence in recruitment was detected in a large proportion of populations (70%), whereas for density dependence in somatic growth the prevalence of density dependence depended heavily on the method (26% and 69%). Despite age-dependent variability, the density dependence in recruitment was consistently stronger among age groups and between alternative approaches that use weight-at-age or weight increments to assess growth. Estimates of density-dependent reduction in biomass underlined these results: 97% of populations with statistically significant parameters for growth and recruitment showed a larger impact of density-dependent recruitment on population biomass. The results reaffirm the importance of density-dependent recruitment in marine fishes, yet they also show that density dependence in somatic growth is not uncommon. Furthermore, the results are important from an applied perspective because density dependence in somatic growth affects productivity and

  10. Optimal tax rate and economic growth. Evidence from Nigeria and South Africa

    Directory of Open Access Journals (Sweden)

    Olufemi Muibi SAIBU

    2015-05-01

    Full Text Available The recent economic crisis had made developing countries to look inward for financial resources to finance development. The readily alternative is the tax revenues however, the possible adverse direct and indirect effects of tax on productivity and work efforts as well as on aggregate consumption had make some African countries (especially Nigeria and South Africa reluctant in implementing far reaching tax policy reform. This paper examines optimal tax burden and real output growth Nigeria and South Africa, two of the top four economies in Africa. The paper empirically determined what should be the optimal tax rate for Nigeria and South Africa-the two leading economies in Africa. The paper found that nonlinearity hypothesis in the effects of tax in the case of South Africa is rejected while a significant nonlinear relationship is found in the case of Nigeria. The results suggest that the growth-maximizing tax rate is about 15% of per capita GDP for South Africa and 30% for Nigeria. At that tax rate, the economic growth rate would be around 6% and 8% instead of the actual mean growth rate of 2.84% and 4.51% for South Africa and Nigeria respectively. The paper concluded the current tax burden in the two countries may be sub-optimal and may hurt long term sustainable growth process in the two countries

  11. Orientation aspects of growth during recrystallization

    International Nuclear Information System (INIS)

    Juul Jensen, D.

    1997-04-01

    Recrystallization of heavily cold rolled aluminium and copper is studied with the aim of achieving information about effects of crystallography orientation on the growth process. The potentials of several experimental techniques are analysed, and a method well suited for characterizing growth rates of grains with different orientations is developed. This method, which is referred to as the extended Cahn-Hagel method, is used for growth rate determinations in aluminium and copper deformed and annealed under five different conditions. In all the investigated cases, preferential growth of cube oriented grains is observed. Recrystallization models, which simulates the orientational as well as microstructural development, are described. selected models are applied for studies of recrystallization in aluminium and copper under specific deformation and annealing conditions as well as for more general studies of the effects of orientation dependent growth rates on the recrystallization microstructure and texture. Finally, reasons for the observed orientation dependent growth rates are discussed. A new mechanism, orientation pinning, is suggested and it is shown that this mechanism is necessary for the understanding of experimental results. (au) 4 tabs., 41 ills., 153 refs

  12. Orientation aspects of growth during recrystallization

    Energy Technology Data Exchange (ETDEWEB)

    Juul Jensen, D.

    1997-04-01

    Recrystallization of heavily cold rolled aluminium and copper is studied with the aim of achieving information about effects of crystallography orientation on the growth process. The potentials of several experimental techniques are analysed, and a method well suited for characterizing growth rates of grains with different orientations is developed. This method, which is referred to as the extended Cahn-Hagel method, is used for growth rate determinations in aluminium and copper deformed and annealed under five different conditions. In all the investigated cases, preferential growth of cube oriented grains is observed. Recrystallization models, which simulates the orientational as well as microstructural development, are described. selected models are applied for studies of recrystallization in aluminium and copper under specific deformation and annealing conditions as well as for more general studies of the effects of orientation dependent growth rates on the recrystallization microstructure and texture. Finally, reasons for the observed orientation dependent growth rates are discussed. A new mechanism, orientation pinning, is suggested and it is shown that this mechanism is necessary for the understanding of experimental results. (au) 4 tabs., 41 ills., 153 refs.

  13. Effects of hepatocyte growth factor on glutathione synthesis, growth, and apoptosis is cell density-dependent

    International Nuclear Information System (INIS)

    Yang Heping; Magilnick, Nathaniel; Xia Meng; Lu, Shelly C.

    2008-01-01

    Hepatocyte growth factor (HGF) is a potent hepatocyte mitogen that exerts opposing effects depending on cell density. Glutathione (GSH) is the main non-protein thiol in mammalian cells that modulates growth and apoptosis. We previously showed that GSH level is inversely related to cell density of hepatocytes and is positively related to growth. Our current work examined whether HGF can modulate GSH synthesis in a cell density-dependent manner and how GSH in turn influence HGF's effects. We found HGF treatment of H4IIE cells increased cell GSH levels only under subconfluent density. The increase in cell GSH under low density was due to increased transcription of GSH synthetic enzymes. This correlated with increased protein levels and nuclear binding activities of c-Jun, c-Fos, p65, p50, Nrf1 and Nrf2 to the promoter region of these genes. HGF acts as a mitogen in H4IIE cells under low cell density and protects against tumor necrosis factor α (TNFα)-induced apoptosis by limiting JNK activation. However, HGF is pro-apoptotic under high cell density and exacerbates TNFα-induced apoptosis by potentiating JNK activation. The increase in cell GSH under low cell density allows HGF to exert its full mitogenic effect but is not necessary for its anti-apoptotic effect

  14. Space-Time Dependent Transport, Activation, and Dose Rates for Radioactivated Fluids.

    Science.gov (United States)

    Gavazza, Sergio

    Two methods are developed to calculate the space - and time-dependent mass transport of radionuclides, their production and decay, and the associated dose rates generated from the radioactivated fluids flowing through pipes. The work couples space- and time-dependent phenomena, treated as only space- or time-dependent in the open literature. The transport and activation methodology (TAM) is used to numerically calculate space- and time-dependent transport and activation of radionuclides in fluids flowing through pipes exposed to radiation fields, and volumetric radioactive sources created by radionuclide motions. The computer program Radionuclide Activation and Transport in Pipe (RNATPA1) performs the numerical calculations required in TAM. The gamma ray dose methodology (GAM) is used to numerically calculate space- and time-dependent gamma ray dose equivalent rates from the volumetric radioactive sources determined by TAM. The computer program Gamma Ray Dose Equivalent Rate (GRDOSER) performs the numerical calculations required in GAM. The scope of conditions considered by TAM and GAM herein include (a) laminar flow in straight pipe, (b)recirculating flow schemes, (c) time-independent fluid velocity distributions, (d) space-dependent monoenergetic neutron flux distribution, (e) space- and time-dependent activation process of a single parent nuclide and transport and decay of a single daughter radionuclide, and (f) assessment of space- and time-dependent gamma ray dose rates, outside the pipe, generated by the space- and time-dependent source term distributions inside of it. The methodologies, however, can be easily extended to include all the situations of interest for solving the phenomena addressed in this dissertation. A comparison is made from results obtained by the described calculational procedures with analytical expressions. The physics of the problems addressed by the new technique and the increased accuracy versus non -space and time-dependent methods

  15. The evaluation system of city's smart growth success rates

    Science.gov (United States)

    Huang, Yifan

    2018-04-01

    "Smart growth" is to pursue the best integrated perform+-ance of the Economically prosperous, socially Equitable, and Environmentally Sustainable(3E). Firstly, we establish the smart growth evaluation system(SGI) and the sustainable development evaluation system(SDI). Based on the ten principles and the definition of three E's of sustainability. B y using the Z-score method and the principal component analysis method, we evaluate and quantify indexes synthetically. Then we define the success of smart growth as the ratio of the SDI to the SGI composite score growth rate (SSG). After that we select two cities — Canberra and Durres as the objects of our model in view of the model. Based on the development plans and key data of these two cities, we can figure out the success of smart growth. And according to our model, we adjust some of the growth indicators for both cities. Then observe the results before and after adjustment, and finally verify the accuracy of the model.

  16. Growth-rate regulated genes have profound impact on interpretation of transcriptome profiling in Saccharomyces cerevisiae

    DEFF Research Database (Denmark)

    Regenberg, Birgitte; Grotkjær, Thomas; Winther, Ole

    2006-01-01

    Growth rate is central to the development of cells in all organisms. However, little is known about the impact of changing growth rates. We used continuous cultures to control growth rate and studied the transcriptional program of the model eukaryote Saccharomyces cerevisiae, with generation time...

  17. Growth Rates and Mechanisms of Magmatic Orbicule Formation: Insights from Calcium Isotopes

    Science.gov (United States)

    Antonelli, M. A.; Watkins, J. M.; DePaolo, D. J.

    2017-12-01

    Orbicular diorites and granites are rare plutonic rock textures that remain enigmatic despite a century of study. Orbicules consist of a rounded core (xenolith, xenocryst, or autolith) surrounded by a variable number of concentric rings defined by different modal mineralogies and textures. Recent work suggests that the alternating layers of mineral growth are a consequence of either changes in external conditions of the magma (e.g. temperature, magma composition due to mixing, changes in volatile abundances), or rapid growth of one mineral phase (e.g plagioclase) creating a depleted boundary layer that then promotes precipitation of an alternative mineral phase (e.g. pyroxene). This process can be repeated to produce multiple layers. The rates at which orbicules grow is also of interest and relates to the mechanisms. Studies of orbicular diorites from the northern Sierra Nevada suggest exceptionally high growth rates (McCarthy et al., 2016). Ca isotopes can offer a unique perspective on orbicule formation, as diffusive isotope fractionation should be substantial when growth rates are high, and they are also sensitive to the nature of the growth medium (silicate liquid or supercritical fluid phase). We present δ44Ca measurements and chemistry for a transect of a dioritic orbicule collected from Emerald Lake, California (Sierra Nevada), where the growth layers are defined by variations in plagioclase/pyroxene ratio, grain size, and texture. Ca concentration varies from 5-13 wt%, and d44Ca values oscillate between -0.5 to 0.0‰ relative to BSE, correlating with changes in mineralogy and texture. Zones of plagioclase comb texture are associated with negative δ44Ca excursions of -0.2 to -0.4‰, consistent with diffusive isotope fractionation during rapid mineral growth. Assuming a 10‰ difference in diffusivity for 44Ca vs. 40Ca in dioritic liquids (Watson et al., 2016), and using the models of Watson and Muller (2009) as a guide, these small fractionations

  18. On the Temperature Dependence of Enzyme-Catalyzed Rates.

    Science.gov (United States)

    Arcus, Vickery L; Prentice, Erica J; Hobbs, Joanne K; Mulholland, Adrian J; Van der Kamp, Marc W; Pudney, Christopher R; Parker, Emily J; Schipper, Louis A

    2016-03-29

    One of the critical variables that determine the rate of any reaction is temperature. For biological systems, the effects of temperature are convoluted with myriad (and often opposing) contributions from enzyme catalysis, protein stability, and temperature-dependent regulation, for example. We have coined the phrase "macromolecular rate theory (MMRT)" to describe the temperature dependence of enzyme-catalyzed rates independent of stability or regulatory processes. Central to MMRT is the observation that enzyme-catalyzed reactions occur with significant values of ΔCp(‡) that are in general negative. That is, the heat capacity (Cp) for the enzyme-substrate complex is generally larger than the Cp for the enzyme-transition state complex. Consistent with a classical description of enzyme catalysis, a negative value for ΔCp(‡) is the result of the enzyme binding relatively weakly to the substrate and very tightly to the transition state. This observation of negative ΔCp(‡) has important implications for the temperature dependence of enzyme-catalyzed rates. Here, we lay out the fundamentals of MMRT. We present a number of hypotheses that arise directly from MMRT including a theoretical justification for the large size of enzymes and the basis for their optimum temperatures. We rationalize the behavior of psychrophilic enzymes and describe a "psychrophilic trap" which places limits on the evolution of enzymes in low temperature environments. One of the defining characteristics of biology is catalysis of chemical reactions by enzymes, and enzymes drive much of metabolism. Therefore, we also expect to see characteristics of MMRT at the level of cells, whole organisms, and even ecosystems.

  19. Growth rate distribution in the forming lateral root of arabidopsis.

    Science.gov (United States)

    Szymanowska-Pułka, Joanna; Lipowczan, Marcin

    2014-10-01

    Microscopic observations of lateral roots (LRs) in Arabidopsis thaliana reveal that the cross-sectional shape of the organ changes from its basal to its apical region. The founder cells for LRs are elongated along the parent root axis, and thus from the site of initiation the base of LRs resemble an ellipse. The circumference of the apical part of LRs is usually a circle. The objective of this study was to analyse the characteristics of changes in the growth field of LRs possessing various shapes in their basal regions. The LRs of the wild type (Col-0) and two transgenic arabidopsis lines were analysed. On the basis of measurements of the long and short diameters (DL and DS, respectively) of the ellipse-like figure representing the bases of particular LRs, their asymmetry ratios (DL/DS) were determined. Possible differences between accessions were analysed by applying statistical methods. No significant differences between accessions were detected. Comparisons were therefore made of the maximal, minimal and mean value of the ratio of all the LRs analysed. Taking into consideration the lack of circular symmetry of the basal part, rates of growth were determined at selected points on the surface of LRs by the application of the growth tensor method, a mathematical tool previously applied only to describe organs with rotational symmetry. Maps showing the distribution of growth rates were developed for surfaces of LRs of various asymmetry ratios. The maps of growth rates on the surfaces of LRs having various shapes of the basal part show differences in both the geometry and the manner of growth, thus indicating that the manner of growth of the LR primordium is correlated to its shape. This is the first report of a description of growth of an asymmetric plant organ using the growth tensor method. The mathematical modelling adopted in the study provides new insights into plant organ formation and shape. © The Author 2014. Published by Oxford University Press on

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

    Science.gov (United States)

    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

  1. Transcriptional dynamics with time-dependent reaction rates

    Science.gov (United States)

    Nandi, Shubhendu; Ghosh, Anandamohan

    2015-02-01

    Transcription is the first step in the process of gene regulation that controls cell response to varying environmental conditions. Transcription is a stochastic process, involving synthesis and degradation of mRNAs, that can be modeled as a birth-death process. We consider a generic stochastic model, where the fluctuating environment is encoded in the time-dependent reaction rates. We obtain an exact analytical expression for the mRNA probability distribution and are able to analyze the response for arbitrary time-dependent protocols. Our analytical results and stochastic simulations confirm that the transcriptional machinery primarily act as a low-pass filter. We also show that depending on the system parameters, the mRNA levels in a cell population can show synchronous/asynchronous fluctuations and can deviate from Poisson statistics.

  2. Transcriptional dynamics with time-dependent reaction rates

    International Nuclear Information System (INIS)

    Nandi, Shubhendu; Ghosh, Anandamohan

    2015-01-01

    Transcription is the first step in the process of gene regulation that controls cell response to varying environmental conditions. Transcription is a stochastic process, involving synthesis and degradation of mRNAs, that can be modeled as a birth–death process. We consider a generic stochastic model, where the fluctuating environment is encoded in the time-dependent reaction rates. We obtain an exact analytical expression for the mRNA probability distribution and are able to analyze the response for arbitrary time-dependent protocols. Our analytical results and stochastic simulations confirm that the transcriptional machinery primarily act as a low-pass filter. We also show that depending on the system parameters, the mRNA levels in a cell population can show synchronous/asynchronous fluctuations and can deviate from Poisson statistics. (paper)

  3. Stress corrosion crack growth rate in dissimilar metal welds

    International Nuclear Information System (INIS)

    Fernandez, M. P.; Lapena, J.; Lancha, A. M.; Perosanz, F. J.; Navas, M.

    2000-01-01

    Dissimilar welds, used to join different sections in light water reactors, are potentially susceptible to stress corrosion cracking (SCC) in aqueous mediums characteristic of nuclear plants. However, the study of these The ma has been limited to evaluating the weld material susceptibility in these mediums. Little scarce data are available on crack growth rates due, fundamentally, to inadequate testing techniques. In order to address this lack of information the crack growth rate at the interface of ferritic SA 533 B-1 alloy and alloy I-82, in a dissimilar weld (SA533B-1/I-82/316L), was studied. Experiments were conducted in water at 288 degree centigrade, 8 ppm of O 2 and 1 μS/cm conductivity. (Author) 33 refs

  4. Developmental plasticity of growth and digestive efficiency in dependence of early-life food availability

    Science.gov (United States)

    Kotrschal, Alexander; Szidat, Sönke; Taborsky, Barbara

    2014-01-01

    Nutrition is a potent mediator of developmental plasticity. If food is scarce, developing organisms may invest into growth to outgrow size-dependent mortality (short-term benefit) and/or into an efficient digestion system (long-term benefit). We investigated this potential trade-off, by determining the influence of food availability on juvenile body and organ growth, and on adult digestive efficiency in the cichlid fish Simochromis pleurospilus. We reared two groups of fish at constant high or low food rations, and we switched four other groups between these two rations at an early and late juvenile period. We measured juvenile growth and organ sizes at different developmental stages and determined adult digestive efficiency. Fish kept at constant, high rations grew considerably faster than low-food fish. Nevertheless, S. pleurospilus partly buffered the negative effects of low food availability by developing heavier digestive organs, and they were therefore more efficient in digesting their food as adults. Results of fish exposed to a ration switch during either the early or late juvenile period suggest (i) that the ability to show compensatory growth after early exposure to low food availability persists during the juvenile period, (ii) that digestive efficiency is influenced by varying juvenile food availability during the late juvenile phase and (iii) that the efficiency of the adult digestive system is correlated with the growth rate during a narrow time window of juvenile period. PMID:25866430

  5. Growth rate effects on the formation of dislocation loops around deep helium bubbles in Tungsten

    International Nuclear Information System (INIS)

    Sandoval, Luis; Perez, Danny; Uberuaga, Blas P.; Voter, Arthur Ford

    2016-01-01

    Here, the growth process of spherical helium bubbles located 6 nm below a (100) surface is studied using molecular dynamics and parallel replica dynamics simulations, over growth rates from 10"6 to 10"1"2 helium atoms per second. Slower growth rates lead to a release of pressure and lower helium content as compared with fast growth cases. In addition, at slower growth rates, helium bubbles are not decorated by multiple dislocation loops, as these tend to merge or emit given sufficient time. At faster rates, dislocation loops nucleate faster than they can emit, leading to a more complicated dislocation structure around the bubble.

  6. Shear-Rate-Dependent Behavior of Clayey Bimaterial Interfaces at Landslide Stress Levels

    Science.gov (United States)

    Scaringi, Gianvito; Hu, Wei; Xu, Qiang; Huang, Runqiu

    2018-01-01

    The behavior of reactivated and first-failure landslides after large displacements is controlled by the available shear resistance in a shear zone and/or along slip surfaces, such as a soil-bedrock interface. Among the factors influencing the resistance parameter, the dependence on the shear rate can trigger catastrophic evolution (rate-weakening) or exert a slow-down feedback (rate-strengthening) upon stress perturbation. We present ring-shear test results, performed under various normal stresses and shear rates, on clayey soils from a landslide shear zone, on its parent lithology and other lithologies, and on clay-rock interface samples. We find that depending on the materials in contact, the normal stress, and the stress history, the shear-rate-dependent behaviors differ. We discuss possible models and underlying mechanisms for the time-dependent behavior of landslides in clay soils.

  7. Growth rates of important East African montane forest trees, with ...

    African Journals Online (AJOL)

    These trees showed growth rates at least twice as high as those of the primary species. Juniperus procera was found to be the fastest growing species in the cedar forest, underlining its success in forming dense stands after a fire. Only young Podocarpus latifolius showed a similar fast growth. Olea europaea ssp. cuspidata, ...

  8. Standard metabolic rate predicts growth trajectory of juvenile Chinese crucian carp (Carassius auratus under changing food availability

    Directory of Open Access Journals (Sweden)

    Ling-Qing Zeng

    2017-09-01

    Full Text Available Phenotypic traits vary greatly within populations and can have a significant influence on aspects of performance. The present study aimed to investigate the effects of individual variation in standard metabolic rate (SMR on growth rate and tolerance to food deprivation in juvenile Chinese crucian carp (Carassius auratus under varying levels of food availability. To address this issue, 19 high and 16 low SMR individuals were randomly assigned to a satiation diet for 3 weeks, whereas another 20 high and 16 low SMR individuals were assigned to a restricted diet (approximately 50% of satiation for the same period. Then, all fish were completely food-deprived for another 3 weeks. High SMR individuals showed a higher growth rate when fed to satiation, but this advantage of SMR did not exist in food-restricted fish. This result was related to improved feeding efficiency with decreased food intake in low SMR individuals, due to their low food processing capacity and maintenance costs. High SMR individuals experienced more mass loss during food deprivation as compared to low SMR individuals. Our results here illustrate context-dependent costs and benefits of intraspecific variation in SMR whereby high SMR individuals show increased growth performance under high food availability but had a cost under stressful environments (i.e. food shortage.

  9. Enhancement of glomerular filtration rate and renal plasma flow by oral glucose load in well controlled insulin-dependent diabetics

    DEFF Research Database (Denmark)

    Sandahl Christiansen, J; Christensen, C K; Hermansen, K

    1986-01-01

    Glomerular filtration rate (GFR) and renal plasma flow (RPF) were measured in 27 patients with uncomplicated insulin-dependent diabetes (IDDM) before and after an oral glucose load of 1.1 g glucose/kg body wt. In the 18 patients showing near-normoglycaemia (blood glucose less than or equal to 8....... No changes in blood pressure or urinary albumin excretion rates took place in either group. The reduction in plasma protein and in plasma growth hormone concentration were similar in the two groups. No change was seen in plasma arginine vasopressin concentration. There was no difference in the qualitative...

  10. Sex-based differences in Adelie penguin (Pygoscelis adeliae) chick growth rates.

    Science.gov (United States)

    Jennings, Scott; Varsani, Arvind; Dugger, Catherine; Ballard, Grant; Ainley, David G.

    2016-01-01

    Sexually size-dimorphic species must show some difference between the sexes in growth rate and/or length of growing period. Such differences in growth parameters can cause the sexes to be impacted by environmental variability in different ways, and understanding these differences allows a better understanding of patterns in productivity between individuals and populations. We investigated differences in growth rate and diet between male and female Adélie Penguin (Pygoscelis adeliae) chicks during two breeding seasons at Cape Crozier, Ross Island, Antarctica. Adélie Penguins are a slightly dimorphic species, with adult males averaging larger than adult females in mass (~11%) as well as bill (~8%) and flipper length (~3%). We measured mass and length of flipper, bill, tibiotarsus, and foot at 5-day intervals for 45 male and 40 female individually-marked chicks. Chick sex was molecularly determined from feathers. We used linear mixed effects models to estimate daily growth rate as a function of chick sex, while controlling for hatching order, brood size, year, and potential variation in breeding quality between pairs of parents. Accounting for season and hatching order, male chicks gained mass an average of 15.6 g d-1 faster than females. Similarly, growth in bill length was faster for males, and the calculated bill size difference at fledging was similar to that observed in adults. There was no evidence for sex-based differences in growth of other morphological features. Adélie diet at Ross Island is composed almost entirely of two species—one krill (Euphausia crystallorophias) and one fish (Pleuragramma antarctica), with fish having a higher caloric value. Using isotopic analyses of feather samples, we also determined that male chicks were fed a higher proportion of fish than female chicks. The related differences in provisioning and growth rates of male and female offspring provides a greater understanding of the ways in which ecological factors may impact

  11. Age, growth rate, and otolith growth of polar cod (Boreogadus saida in two fjords of Svalbard, Kongsfjorden and Rijpfjorden

    Directory of Open Access Journals (Sweden)

    Dariusz P. Fey

    2017-10-01

    Full Text Available This work presents biological information for polar cod (Boreogadus saida collected with a Campelen 1800 shrimp bottom trawl in Kongsfjorden (two stations located in the inner part of the fjord adjacent to the glacier and Rijpfjorden (one station at the entrance to the fjord in September and October 2013. The otolith-based ages of polar cod collected in Kongsfjorden (6.1–24 cm total length TL; n = 813 ranged from 0 to 4 years. The growth rate was relatively constant at approximately 4.7 cm year−1 between years 1 and 4, which indicates that growth was fast in the glacier area. The ages of polar cod collected in Rijpfjorden (8.6–15.9 cm TL; n = 64 ranged from 2 to 3 years. The fish from Rijpfjorden were smaller at age than those from Kongsfjorden, and their growth rate between years 2 and 3 (no other age classes were available was approximately 3.3 cm year−1. In both fjords, males and females were of the same size-at-age and the same weight-at-TL. The small sampling area means that the results on growth rate are not representative of the entire fjords. Instead, the results can be discussed as presenting the possible growth rates of some populations. A strong relationship was identified between otolith size (length and weight and fish size (TL and TW, with no differences between males and females or the fjords. A significant, strong relationship was also noted between fish and otolith growth rates.

  12. Controlling the crystal polymorph by exploiting the time dependence of nucleation rates.

    Science.gov (United States)

    Little, Laurie J; King, Alice A K; Sear, Richard P; Keddie, Joseph L

    2017-10-14

    Most substances can crystallise into two or more different crystal lattices called polymorphs. Despite this, there are no systems in which we can quantitatively predict the probability of one competing polymorph forming instead of the other. We address this problem using large scale (hundreds of events) studies of the competing nucleation of the alpha and gamma polymorphs of glycine. In situ Raman spectroscopy is used to identify the polymorph of each crystal. We find that the nucleation kinetics of the two polymorphs is very different. Nucleation of the alpha polymorph starts off slowly but accelerates, while nucleation of the gamma polymorph starts off fast but then slows. We exploit this difference to increase the purity with which we obtain the gamma polymorph by a factor of ten. The statistics of the nucleation of crystals is analogous to that of human mortality, and using a result from medical statistics, we show that conventional nucleation data can say nothing about what, if any, are the correlations between competing nucleation processes. Thus we can show that with data of our form it is impossible to disentangle the competing nucleation processes. We also find that the growth rate and the shape of a crystal depend on it when nucleated. This is new evidence that nucleation and growth are linked.

  13. Mechanisms promoting higher growth rate in arctic than in temperate shorebirds

    NARCIS (Netherlands)

    Schekkerman, H.; Tulp, I.Y.M.; Piersma, T.; Visser, G.H.

    2003-01-01

    We compared prefledging growth, energy expenditure, and time budgets in the arctic-breeding red knot (Calidris canutus) to those in temperate shorebirds, to investigate how arctic chicks achieve a high growth rate despite energetic difficulties associated with precocial development in a cold

  14. Mechanisms promoting higher growth rate in arctic than in temperate shorebirds

    NARCIS (Netherlands)

    Schekkerman, H; Tulp, Ingrid; Piersma, T.; Visser, G.H.

    We compared prefledging growth, energy expenditure, and time budgets in the arctic-breeding red knot (Calidris canutus) to those in temperate shorebirds, to investigate how arctic chicks achieve a high growth rate despite energetic difficulties associated with precocial development in a cold

  15. Response of insect relative growth rate to temperature and host-plant phenology: estimation and validation from field data.

    Directory of Open Access Journals (Sweden)

    Mamadou Ciss

    Full Text Available Between 1975 to 2011, aphid Relative Growth Rates (RGR were modelled as a function of mean outdoor temperature and host plant phenology. The model was applied to the grain aphid Sitobion avenae using data on aphid counts in winter wheat at two different climate regions in France (oceanic climate, Rennes (western France; continental climate, Paris. Mean observed aphid RGR was higher in Paris compared to the Rennes region. RGR increased with mean temperature, which is explained by aphid reproduction, growth and development being dependent on ambient temperature. From the stem extension to the heading stage in wheat, there was either a plateau in RGR values (Rennes or an increase with a maximum at heading (Paris due to high intrinsic rates of increase in aphids and also to aphid immigration. From the wheat flowering to the ripening stage, RGR decreased in both regions due to the low intrinsic rate of increase in aphids and high emigration rate linked to reduced nutrient quality in maturing wheat. The model validation process showed that the fitted models have more predictive power in the Paris region than in the Rennes region.

  16. How the growth rate of host cells affects cancer risk in a deterministic way

    Science.gov (United States)

    Draghi, Clément; Viger, Louise; Denis, Fabrice; Letellier, Christophe

    2017-09-01

    It is well known that cancers are significantly more often encountered in some tissues than in other ones. In this paper, by using a deterministic model describing the interactions between host, effector immune and tumor cells at the tissue level, we show that this can be explained by the dependency of tumor growth on parameter values characterizing the type as well as the state of the tissue considered due to the "way of life" (environmental factors, food consumption, drinking or smoking habits, etc.). Our approach is purely deterministic and, consequently, the strong correlation (r = 0.99) between the number of detectable growing tumors and the growth rate of cells from the nesting tissue can be explained without evoking random mutation arising during DNA replications in nonmalignant cells or "bad luck". Strategies to limit the mortality induced by cancer could therefore be well based on improving the way of life, that is, by better preserving the tissue where mutant cells randomly arise.

  17. Ecological regime shift drives declining growth rates of sea turtles throughout the West Atlantic

    Science.gov (United States)

    Bjorndal, Karen A.; Bolten, Alan B.; Chaloupka, Milani; Saba, Vincent S.; Bellini, Cláudio; Marcovaldi, Maria A.G.; Santos, Armando J.B.; Bortolon, Luis Felipe Wurdig; Meylan, Anne B.; Meylan, Peter A.; Gray, Jennifer; Hardy, Robert; Brost, Beth; Bresette, Michael; Gorham, Jonathan C.; Connett, Stephen; Crouchley, Barbara Van Sciver; Dawson, Mike; Hayes, Deborah; Diez, Carlos E.; van Dam, Robert P.; Willis, Sue; Nava, Mabel; Hart, Kristen M.; Cherkiss, Michael S.; Crowder, Andrew; Pollock, Clayton; Hillis-Starr, Zandy; Muñoz Tenería, Fernando A.; Herrera-Pavón, Roberto; Labrada-Martagón, Vanessa; Lorences, Armando; Negrete-Philippe, Ana; Lamont, Margaret M.; Foley, Allen M.; Bailey, Rhonda; Carthy, Raymond R.; Scarpino, Russell; McMichael, Erin; Provancha, Jane A.; Brooks, Annabelle; Jardim, Adriana; López-Mendilaharsu, Milagros; González-Paredes, Daniel; Estrades, Andrés; Fallabrino, Alejandro; Martínez-Souza, Gustavo; Vélez-Rubio, Gabriela M.; Boulon, Ralf H.; Collazo, Jaime; Wershoven, Robert; Hernández, Vicente Guzmán; Stringell, Thomas B.; Sanghera, Amdeep; Richardson, Peter B.; Broderick, Annette C.; Phillips, Quinton; Calosso, Marta C.; Claydon, John A.B.; Metz, Tasha L.; Gordon, Amanda L.; Landry, Andre M.; Shaver, Donna J.; Blumenthal, Janice; Collyer, Lucy; Godley, Brendan J.; McGowan, Andrew; Witt, Matthew J.; Campbell, Cathi L.; Lagueux, Cynthia J.; Bethel, Thomas L.; Kenyon, Lory

    2017-01-01

    Somatic growth is an integrated, individual-based response to environmental conditions, especially in ectotherms. Growth dynamics of large, mobile animals are particularly useful as bio-indicators of environmental change at regional scales. We assembled growth rate data from throughout the West Atlantic for green turtles, Chelonia mydas, which are long-lived, highly migratory, primarily herbivorous mega-consumers that may migrate over hundreds to thousands of kilometers. Our dataset, the largest ever compiled for sea turtles, has 9690 growth increments from 30 sites from Bermuda to Uruguay from 1973 to 2015. Using generalized additive mixed models, we evaluated covariates that could affect growth rates; body size, diet, and year have significant effects on growth. Growth increases in early years until 1999, then declines by 26% to 2015. The temporal (year) effect is of particular interest because two carnivorous species of sea turtles – hawksbills, Eretmochelys imbricata, and loggerheads, Caretta caretta – exhibited similar significant declines in growth rates starting in 1997 in the West Atlantic, based on previous studies. These synchronous declines in productivity among three sea turtle species across a trophic spectrum provide strong evidence that an ecological regime shift (ERS) in the Atlantic is driving growth dynamics. The ERS resulted from a synergy of the 1997/1998 El Niño Southern Oscillation (ENSO) – the strongest on record – combined with an unprecedented warming rate over the last two to three decades. Further support is provided by the strong correlations between annualized mean growth rates of green turtles and both sea surface temperatures (SST) in the West Atlantic for years of declining growth rates (r = -0.94) and the Multivariate ENSO Index (MEI) for all years (r = 0.74). Granger-causality analysis also supports the latter finding. We discuss multiple stressors that could reinforce and prolong the effect of the ERS. This study

  18. Ecological regime shift drives declining growth rates of sea turtles throughout the West Atlantic.

    Science.gov (United States)

    Bjorndal, Karen A; Bolten, Alan B; Chaloupka, Milani; Saba, Vincent S; Bellini, Cláudio; Marcovaldi, Maria A G; Santos, Armando J B; Bortolon, Luis Felipe Wurdig; Meylan, Anne B; Meylan, Peter A; Gray, Jennifer; Hardy, Robert; Brost, Beth; Bresette, Michael; Gorham, Jonathan C; Connett, Stephen; Crouchley, Barbara Van Sciver; Dawson, Mike; Hayes, Deborah; Diez, Carlos E; van Dam, Robert P; Willis, Sue; Nava, Mabel; Hart, Kristen M; Cherkiss, Michael S; Crowder, Andrew G; Pollock, Clayton; Hillis-Starr, Zandy; Muñoz Tenería, Fernando A; Herrera-Pavón, Roberto; Labrada-Martagón, Vanessa; Lorences, Armando; Negrete-Philippe, Ana; Lamont, Margaret M; Foley, Allen M; Bailey, Rhonda; Carthy, Raymond R; Scarpino, Russell; McMichael, Erin; Provancha, Jane A; Brooks, Annabelle; Jardim, Adriana; López-Mendilaharsu, Milagros; González-Paredes, Daniel; Estrades, Andrés; Fallabrino, Alejandro; Martínez-Souza, Gustavo; Vélez-Rubio, Gabriela M; Boulon, Ralf H; Collazo, Jaime A; Wershoven, Robert; Guzmán Hernández, Vicente; Stringell, Thomas B; Sanghera, Amdeep; Richardson, Peter B; Broderick, Annette C; Phillips, Quinton; Calosso, Marta; Claydon, John A B; Metz, Tasha L; Gordon, Amanda L; Landry, Andre M; Shaver, Donna J; Blumenthal, Janice; Collyer, Lucy; Godley, Brendan J; McGowan, Andrew; Witt, Matthew J; Campbell, Cathi L; Lagueux, Cynthia J; Bethel, Thomas L; Kenyon, Lory

    2017-11-01

    Somatic growth is an integrated, individual-based response to environmental conditions, especially in ectotherms. Growth dynamics of large, mobile animals are particularly useful as bio-indicators of environmental change at regional scales. We assembled growth rate data from throughout the West Atlantic for green turtles, Chelonia mydas, which are long-lived, highly migratory, primarily herbivorous mega-consumers that may migrate over hundreds to thousands of kilometers. Our dataset, the largest ever compiled for sea turtles, has 9690 growth increments from 30 sites from Bermuda to Uruguay from 1973 to 2015. Using generalized additive mixed models, we evaluated covariates that could affect growth rates; body size, diet, and year have significant effects on growth. Growth increases in early years until 1999, then declines by 26% to 2015. The temporal (year) effect is of particular interest because two carnivorous species of sea turtles-hawksbills, Eretmochelys imbricata, and loggerheads, Caretta caretta-exhibited similar significant declines in growth rates starting in 1997 in the West Atlantic, based on previous studies. These synchronous declines in productivity among three sea turtle species across a trophic spectrum provide strong evidence that an ecological regime shift (ERS) in the Atlantic is driving growth dynamics. The ERS resulted from a synergy of the 1997/1998 El Niño Southern Oscillation (ENSO)-the strongest on record-combined with an unprecedented warming rate over the last two to three decades. Further support is provided by the strong correlations between annualized mean growth rates of green turtles and both sea surface temperatures (SST) in the West Atlantic for years of declining growth rates (r = -.94) and the Multivariate ENSO Index (MEI) for all years (r = .74). Granger-causality analysis also supports the latter finding. We discuss multiple stressors that could reinforce and prolong the effect of the ERS. This study demonstrates the

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

    Science.gov (United States)

    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.

  20. Nanowire growth from the viewpoint of the thin film polylayer growth theory

    Science.gov (United States)

    Kashchiev, Dimo

    2018-03-01

    The theory of polylayer growth of thin solid films is employed for description of the growth kinetics of single-crystal nanowires. Expressions are derived for the dependences of the height h and radius r of a given nanowire on time t, as well as for the h(r) dependence. These dependences are applicable immediately after the nanowire nucleation on the substrate and thus include the period during which the nucleated nanowire changes its shape from that of cap to that of column. The analysis shows that the nanowire cap-to-column shape transition is continuous and makes it possible to kinetically define the nanowire shape-transition radius by means of the nanowire radial and axial growth rates. The obtained h(t), r(t) and h(r) dependences are found to provide a good description of available experimental data for growth of self-nucleated GaN nanowires by the vapor-solid mechanism.

  1. Extending the durability of cultivar resistance by limiting epidemic growth rates.

    Science.gov (United States)

    Carolan, Kevin; Helps, Joe; van den Berg, Femke; Bain, Ruairidh; Paveley, Neil; van den Bosch, Frank

    2017-09-27

    Cultivar resistance is an essential part of disease control programmes in many agricultural systems. The use of resistant cultivars applies a selection pressure on pathogen populations for the evolution of virulence, resulting in loss of disease control. Various techniques for the deployment of host resistance genes have been proposed to reduce the selection for virulence, but these are often difficult to apply in practice. We present a general technique to maintain the effectiveness of cultivar resistance. Derived from classical population genetics theory; any factor that reduces the population growth rates of both the virulent and avirulent strains will reduce selection. We model the specific example of fungicide application to reduce the growth rates of virulent and avirulent strains of a pathogen, demonstrating that appropriate use of fungicides reduces selection for virulence, prolonging cultivar resistance. This specific example of chemical control illustrates a general principle for the development of techniques to manage the evolution of virulence by slowing epidemic growth rates. © 2017 The Author(s).

  2. Causality Relationship Between Import, Export and Growth Rate in Developing Countries

    Directory of Open Access Journals (Sweden)

    Serhat YUKSEL

    2017-06-01

    Full Text Available In this paper, we tried to determine the relationship between imports, exports and growth rate in developing countries. Within this scope, 6 developing countries (Argentina, Brazil, China, Malaysia, Mexico and Turkey were analyzed in this study. In order to achieve this purpose, annual data for the periods between 1961 and 2014 was tested by using Engle Granger co-integration analysis, Vector Error Correction Model and Toda Yamamoto causality analysis. According to the result of the analysis, it was determined that there is not any relationship among three variables in Brazil and Mexico. On the other hand, we defined that increase in export causes higher growth rate in Argentina. Moreover, it was concluded that there is a causal relationship from import to export in China and Turkey. Furthermore, it was determined that export causes higher import in Malaysia. Therefore, it can be concluded that the relationship between import, export and growth rate is not same for all developing countries..

  3. Testing for long-range dependence in the Brazilian term structure of interest rates

    International Nuclear Information System (INIS)

    Cajueiro, Daniel O.; Tabak, Benjamin M.

    2009-01-01

    This paper presents empirical evidence of fractional dynamics in interest rates for different maturities for Brazil. A variation of a newly developed test for long-range dependence, the V/S statistic, with a post-blackening bootstrap is employed. Results suggest that Brazilian interest rates possess strong long-range dependence in volatility, even when considering the structural break in 1999. These findings imply that the development of policy models that give rise to long-range dependence in interest rates' volatility could be very useful. The long-short-term interest rates spread has strong long-range dependence, which suggests that traditional tests of expectation hypothesis of the term structure of interest rates may be misspecified.

  4. Regeneration and growth rates of allofragments in four common stream plants

    DEFF Research Database (Denmark)

    Riis, Tenna; Madsen, Tom Vindbæk; Sennels, R. S. H.

    2009-01-01

    perfoliatus L. and Ranunculus baudotii x pseudofluitans. The objectives of this study were to determine (1) if shoots with an apical tip have higher regeneration (growth of new shoots and rhizomes from allofragments) and colonisation (root attachment in sediment) abilities and higher relative growth rates...

  5. Influence of temperature on growth rate and lag phase of fungi isolated from Argentine corn.

    Science.gov (United States)

    González, H H; Resnik, S L; Vaamonde, G

    1988-03-01

    The influence of temperature on the growth of nine strains of fungi belonging to the genera Eurotium, Aspergillus, Penicillium and Fusarium has been investigated for the temperature range 15-35 degrees C. The lag phase and the growth rate were evaluated by using a laboratory medium. The maximum growth rate for E. repens, A. wentii and P. chrysogenum was observed at about 25 degrees C, for P. citrinum near 30 degrees C and for F. semitectum and F. moniliforme between 20 and 25 degrees C. The growth rate of A. niger, A. flavus and A. parasiticus increased with increasing temperatures in the range studied. For all strains studied it appeared that the higher the growth rate the lower the lag phase was.

  6. Rate dependent inelastic behavior of polycrystalline solids using a dislocation model

    International Nuclear Information System (INIS)

    Werne, R.W.; Kelly, J.M.

    1980-01-01

    A rate dependent theory of polycrystalline plasticity is presented in which the solid is modeled as an isotropic continuum with internal variables. The rate of plastic deformation is shown to be a function of the deviatoric portion of the Cauchy stress tensor as well as two scalar internal variables. The scalar internal variables, which are the dislocation density and mobile fraction, are governed by rate equations which reflect the evolution of microstructural processes. The model has been incorporated into a two dimensional finite element code and several example multidimensional problems are presented which exhibit the rate dependence of the material model

  7. Growth Rate and Relocation Movements of Common Nighthawk (Chordeiles minor) Nestlings in Relation to Age

    Science.gov (United States)

    Kramer, Gunnar R.; Chalfoun, Anna D.

    2012-01-01

    Relocation by dependent young is a survival strategy that occurs among a wide range of taxa. The Common Nighthawk (Chordeiles minor) lays its eggs on bare substrate and, once hatched, nestlings may relocate to new sites daily. We located and monitored eight Common Nighthawk nests in Grand Teton National Park, Wyoming, quantified inter-use-site distances in relation to nestling age, and calculated a nestling growth rate curve. Common Nighthawk nestlings grow in a nearly linear fashion. Nestlings moved up to 48 m in a single day and larger, older nestlings tended to move greater distances between daily use-sites.

  8. The effect of salinity on growth rate and osmolyte concentration of ...

    African Journals Online (AJOL)

    Although at a slower rate, growth is maintained in seawater cultures supplemented with nutrients. Differences were found in carbohydrate content between cultures in different growth media. The highest carbohydrate content was observed in cultures growing in Zarrouk medium supplemented with 4 NaCl and in seawater ...

  9. Comparison of cyanobacterial and green algal growth rates at different temperatures

    NARCIS (Netherlands)

    Lurling, M.; Faassen, E.J.; Kosten, S.; Eshetu, Z.; Huszar, V.M.

    2013-01-01

    1.The hypothesis that cyanobacteria have higher optimum growth temperatures and higher growth rates at the optimum as compared to chlorophytes was tested by running a controlled experiment with eight cyanobacteria species and eight chlorophyte species at six different temperatures (20-35°C) and by

  10. Volume doubling time and growth rate of renal cell carcinoma determined by helical CT: a single-institution experience

    International Nuclear Information System (INIS)

    Lee, Ji Young; Kim, Chan Kyo; Choi, Dongil; Park, Byung Kwan

    2008-01-01

    The purpose of this study was to retrospectively evaluate the volume doubling time (VDT) and growth rate of renal cell carcinomas (RCC) on a serial computed tomography (CT) scan. Thirty pathologically proven RCCs were reviewed with helical CT. Each tumor underwent at least two CT scans. Tumor volume was determined using an area measuring tool and the summation-of-areas technique. Growth rate was evaluated in terms of diameter and volume changes. VDT and volume growth rate were compared in relation to several factors (initial diameter, initial volume, diameter growth rate, volume growth rate, tumor grade, tumor subtype, sex or age). Mean VDT of RCCs was 505 days. Mean diameter and volume growth rate were 0.59 cm/year and 19.1 cm 3 /year, respectively. For volume and diameter growth rate, tumors ≤4 cm showed lower rates than those >4 cm (P 0.05). Volume growth rate was moderately to strongly positively correlated with initial diameter, initial volume and diameter growth rate (P < 0.05). In conclusion, small RCCs grew at a slow rate both diametrically and volumetrically. More accurate assessment of tumor growth rate and VDT may be helpful to understand the natural history of RCC. (orig.)

  11. Growth and xanthan production of Xanthomonas campestris depending on the N-source concentration

    Energy Technology Data Exchange (ETDEWEB)

    Prell, A [Academy of Sciences of the Czech Republic, Prague (Czech Republic). Inst. of Microbiology; Lasik, J [Academy of Sciences of the Czech Republic, Prague (Czech Republic). Inst. of Microbiology; Konicek, J [Academy of Sciences of the Czech Republic, Prague (Czech Republic). Inst. of Microbiology; Sobotka, M [Academy of Sciences of the Czech Republic, Prague (Czech Republic). Inst. of Microbiology; Sys, J [Academy of Sciences of the Czech Republic, Prague (Czech Republic). Inst. of Microbiology

    1995-11-01

    Growth of X. campestris and production of xanthan were studied in several batch fermentations with different starting concentrations of N-source. The dependencies of growth, productivity and yields on initial N-source concentration were observed. The maximum yields in the course of cultivations were identified. (orig.)

  12. Metabolic clearance and production rates of human growth hormone

    Science.gov (United States)

    Taylor, Andrew L.; Finster, Joseph L.; Mintz, Daniel H.

    1969-01-01

    The metabolic clearance rate (MCR) of human growth hormone (HGH) was determined by the constant infusion to equilibrium technique utilizing HGH-125I. 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 mμg/min) were contrasted with hyperthyroid patients (529 ±242 mμg/min, P < 0.05), hypothyroid patients (160 ±69 mμg/min, P < 0.02), IID (245 ±100 mμg/min, NS), and IDD (363 ±153 mμg/min, NS). Considerable

  13. Structure of the Mr 140,000 growth hormone-dependent insulin-like growth factor binding protein complex: Determination by reconstitution and affinity-labeling

    International Nuclear Information System (INIS)

    Baxter, R.C.; Martin, J.L.

    1989-01-01

    To determine the structure of the high molecular weight, growth hormone-dependent complex between the insulin-like growth factors (IGF-I and IGF-II) and their binding proteins in human serum, we have reconstituted the complex from its purified component proteins and analyzed it by gel electrophoresis and autoradiography after covalent cross-linking. The proteins tested in reconstitution mixtures were an acid-labile Mr 84,000-86,000 glycoprotein doublet (alpha subunit), an acid-stable Mr 47,000-53,000 glycoprotein doublet with IGF-binding activity (BP-53 or beta subunit), and IGF-I or IGF-II (gamma subunit). In incubations containing any one of the three subunits 125I-labeled and the other two unlabeled, identical 125I-labeled alpha-beta-gamma complexes of Mr 140,000 were formed. Minor bands of Mr 120,000 and 90,000 were also seen, thought to represent a partially deglycosylated form of the alpha-beta-gamma complex, and an alpha-gamma complex arising as a cross-linking artifact. When serum samples from subjects of various growth hormone status were affinity-labeled with IGF-II tracer, a growth hormone-dependent Mr 140,000 band was seen, corresponding to the reconstituted alpha-beta-gamma complex. Other growth hormone-dependent labeled bands, of Mr 90,000 (corresponding to alpha-gamma), Mr 55,000-60,000 (corresponding to labeled beta-subunit doublet), and smaller bands of Mr 38,000, 28,000, and 23,000-25,000 (corresponding to labeled beta-subunit degradation products), were also seen in the affinity-labeled serum samples and in the complex reconstituted from pure proteins. All were immunoprecipitable with an anti-BP-53 antiserum. We conclude that the growth hormone-dependent Mr 140,000 IGF-binding protein complex in human serum has three components: the alpha (acid-labile) subunit, the beta (binding) subunit, and the gamma (growth factor) subunit

  14. Exchange-Driven Growth with Birth Rate Less Than Death

    International Nuclear Information System (INIS)

    Lin Zhenquan; Ye Gaoxiang; Ke Jianhong

    2005-01-01

    We further study the kinetic behavior of the exchange-driven growth with birth and death for the case of birth rate kernel being less than that of death based on the mean-field theory. The symmetric exchange rate kernel is K(k,j) = K'(k,j) = Ikj υ , and the birth and death rates are proportional to the aggregate's size. The long time asymptotic behavior of the aggregate size distribution a k (t) is found to obey a much unusual scaling law with an exponentially growing scaling function Φ(x) = exp (x).

  15. The Effect of Growth Temperature and V/III Flux Ratio of MOCVD Antimony Based Semiconductors on Growth Rate and Surface Morphology

    Directory of Open Access Journals (Sweden)

    Ramelan Ari Handono

    2017-01-01

    Full Text Available Epitaxial Alx Ga1-x Sb layers on GaSb and GaAs substrates have been grown by atmospheric pressure metalorganic chemical vapor deposition using TMAl, TMGa and TMSb. Nomarski microscope and a profiler were employed to examine the surface morphology and growth rate of the samples. We report the effect of growth temperature and V/III flux ratio on growth rate and surface morphology. Growth temperatures in the range of 520°C and 680°C and V/III ratios from 1 to 5 have been investigated. A growth rate activation energy of 0.73 eV was found. At low growth temperatures between 520 and 540°C, the surface morphology is poor due to antimonide precipitates associated with incomplete decomposition of the TMSb. For layers grown on GaAs at 580°C and 600°C with a V/III ratio of 3 a high quality surface morphology is typical, with a mirror-like surface and good composition control. It was found that a suitable growth temperature and V/III flux ratio was beneficial for producing good AlGaSb layers. Undoped AlGaSb grown at 580°C with a V/III flux ratio of 3 at the rate of 3.5 μm/hour shows p-type conductivity with smooth surface morphology

  16. Inhibition of fibroblast growth by Notch1 signaling is mediated by induction of Wnt11-dependent WISP-1.

    Directory of Open Access Journals (Sweden)

    Zhao-Jun Liu

    Full Text Available Fibroblasts are an integral component of stroma and important source of growth factors and extracellular matrix (ECM. They play a prominent role in maintaining tissue homeostasis and in wound healing and tumor growth. Notch signaling regulates biological function in a variety of cells. To elucidate the physiological function of Notch signaling in fibroblasts, we ablated Notch1 in mouse (Notch1(Flox/Flox embryonic fibroblasts (MEFs. Notch1-deficient (Notch1(-/- MEFs displayed faster growth and motility rate compared to Notch1(Flox/Flox MEFs. Such phenotypic changes, however, were reversible by reconstitution of Notch1 activation via overexpression of the intracellular domain of Notch1 (NICD1 in Notch1-deficient MEFs. In contrast, constitutive activation of Notch1 signaling by introducing NICD1 into primary human dermal fibroblasts (FF2441, which caused pan-Notch activation, inhibited cell growth and motility, whereas cellular inhibition was relievable when the Notch activation was countered with dominant-negative mutant of Master-mind like 1 (DN-MAML-1. Functionally, "Notch-activated" stromal fibroblasts could inhibit tumor cell growth/invasion. Moreover, Notch activation induced expression of Wnt-induced secreted proteins-1 (WISP-1/CCN4 in FF2441 cells while deletion of Notch1 in MEFs resulted in an opposite effect. Notably, WISP-1 suppressed fibroblast proliferation, and was responsible for mediating Notch1's inhibitory effect since siRNA-mediated blockade of WISP-1 expression could relieve cell growth inhibition. Notch1-induced WISP-1 expression appeared to be Wnt11-dependent, but Wnt1-independent. Blockade of Wnt11 expression resulted in decreased WISP-1 expression and liberated Notch-induced cell growth inhibition. These findings indicated that inhibition of fibroblast proliferation by Notch pathway activation is mediated, at least in part, through regulating Wnt1-independent, but Wnt11-dependent WISP-1 expression.

  17. New parametrization for the scale dependent growth function in general relativity

    International Nuclear Information System (INIS)

    Dent, James B.; Dutta, Sourish; Perivolaropoulos, Leandros

    2009-01-01

    We study the scale-dependent evolution of the growth function δ(a,k) of cosmological perturbations in dark energy models based on general relativity. This scale dependence is more prominent on cosmological scales of 100h -1 Mpc or larger. We derive a new scale-dependent parametrization which generalizes the well-known Newtonian approximation result f 0 (a)≡(dlnδ 0 /dlna)=Ω(a) γ (γ=(6/11) for ΛCDM) which is a good approximation on scales less than 50h -1 Mpc. Our generalized parametrization is of the form f(a)=(f 0 (a)/1+ξ(a,k)), where ξ(a,k)=(3H 0 2 Ω 0m )/(ak 2 ). We demonstrate that this parametrization fits the exact result of a full general relativistic evaluation of the growth function up to horizon scales for both ΛCDM and dynamical dark energy. In contrast, the scale independent parametrization does not provide a good fit on scales beyond 5% of the horizon scale (k≅0.01h -1 Mpc).

  18. Influence of water relations and growth rate on plant element uptake and distribution

    International Nuclear Information System (INIS)

    Greger, Maria

    2006-02-01

    Plant uptake of Ni, Sr, Mo, Cs, La, Th, Se, Cl and I was examined to determine how plant water relations and growth rate influence the uptake and distribution of these elements in the studied plants. The specific questions were how water uptake and growth rate influenced the uptake of various nuclides and how transpiration influenced translocation to the shoot. The knowledge gained will be used in future modelling of radionuclide leakage from nuclear waste deposits entering the ecosystem via plants. The plant studied was willow, Salix viminalis, a common plant in the areas suggested for waste disposal; since there can be clone variation, two different clones having different uptake properties for several other heavy metals were used. The plants were grown in nutrient solution and the experiments on 3-month-old plants were run for 3 days. Polyethylene glycol was added to the medium to decrease the water uptake rate, a fan was used to increase the transpiration rate, and different light intensities were used to produce different growth rates. Element concentration was analysed in roots and shoots. The results show that both the uptake and distribution of various elements are influenced in different ways and to various extents by water flow and plant growth rate, and that it is not possible from the chemical properties of these elements to know how they will react. However, in most cases increased growth rate diluted the concentration of the element in the tissue, reduced water uptake reduced the element uptake, while transpiration had no effect on the translocation of elements to the shoot. The clones did not differ in terms of either the uptake or translocation of the elements, except that I was not taken up and translocated to the shoot in one of the clones when the plant water flow or growth rate was too low. Not all of the elements were found in the plant in the same proportions as they had been added to the nutrient solution

  19. Influence of water relations and growth rate on plant element uptake and distribution

    Energy Technology Data Exchange (ETDEWEB)

    Greger, Maria [Stockholm Univ. (Sweden). Dept. of Botany

    2006-02-15

    Plant uptake of Ni, Sr, Mo, Cs, La, Th, Se, Cl and I was examined to determine how plant water relations and growth rate influence the uptake and distribution of these elements in the studied plants. The specific questions were how water uptake and growth rate influenced the uptake of various nuclides and how transpiration influenced translocation to the shoot. The knowledge gained will be used in future modelling of radionuclide leakage from nuclear waste deposits entering the ecosystem via plants. The plant studied was willow, Salix viminalis, a common plant in the areas suggested for waste disposal; since there can be clone variation, two different clones having different uptake properties for several other heavy metals were used. The plants were grown in nutrient solution and the experiments on 3-month-old plants were run for 3 days. Polyethylene glycol was added to the medium to decrease the water uptake rate, a fan was used to increase the transpiration rate, and different light intensities were used to produce different growth rates. Element concentration was analysed in roots and shoots. The results show that both the uptake and distribution of various elements are influenced in different ways and to various extents by water flow and plant growth rate, and that it is not possible from the chemical properties of these elements to know how they will react. However, in most cases increased growth rate diluted the concentration of the element in the tissue, reduced water uptake reduced the element uptake, while transpiration had no effect on the translocation of elements to the shoot. The clones did not differ in terms of either the uptake or translocation of the elements, except that I was not taken up and translocated to the shoot in one of the clones when the plant water flow or growth rate was too low. Not all of the elements were found in the plant in the same proportions as they had been added to the nutrient solution.

  20. The use of Ampelisca abdita growth rate as an indicator of sediment quality

    International Nuclear Information System (INIS)

    Weston, D.P.; Thompson, B.

    1995-01-01

    Acute lethal bioassays with amphipod crustaceans are routinely used to assess toxicity of bulk sediments. A study within the San Francisco Bay Regional Monitoring Program (RMP) is in progress to develop a chronic bioassay with the amphipod Ampelisca abdita, measuring both survivorship and growth rates. This approach is attractive because depression of growth rate is likely to be a more sensitive indicator of toxic effects than acute lethality, and natural populations of A. abdita exist throughout the Bay. Spiked sediment bioassays, using cadmium and crude oil, were used to demonstrate the relative sensitivity of the standard 10-day lethal test vs. the 30-day growth test. Sediments were also collected from 9 sites throughout the Bay, ranging from areas adjacent to municipal wastewater discharges to areas distant from known point source inputs. These samples were then split, and used for side-by-side comparison of acute (lethal) and chronic (growth) toxicity tests. Survivorship exceeded 90% in all tests, including those sediments collected nearest the wastewater outfalls. Growth rates were contrasted among the various treatments to examine the utility of this end point in discriminating the outfall sites. Data on the spatial distribution, abundance, and size-frequency distribution of native populations was examined within the context of using growth rate as an indicator of toxic effects in natural populations as well

  1. Micromechanical modeling of rate-dependent behavior of Connective tissues.

    Science.gov (United States)

    Fallah, A; Ahmadian, M T; Firozbakhsh, K; Aghdam, M M

    2017-03-07

    In this paper, a constitutive and micromechanical model for prediction of rate-dependent behavior of connective tissues (CTs) is presented. Connective tissues are considered as nonlinear viscoelastic material. The rate-dependent behavior of CTs is incorporated into model using the well-known quasi-linear viscoelasticity (QLV) theory. A planar wavy representative volume element (RVE) is considered based on the tissue microstructure histological evidences. The presented model parameters are identified based on the available experiments in the literature. The presented constitutive model introduced to ABAQUS by means of UMAT subroutine. Results show that, monotonic uniaxial test predictions of the presented model at different strain rates for rat tail tendon (RTT) and human patellar tendon (HPT) are in good agreement with experimental data. Results of incremental stress-relaxation test are also presented to investigate both instantaneous and viscoelastic behavior of connective tissues. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Density-dependence as a size-independent regulatory mechanism.

    Science.gov (United States)

    de Vladar, Harold P

    2006-01-21

    The growth function of populations is central in biomathematics. The main dogma is the existence of density-dependence mechanisms, which can be modelled with distinct functional forms that depend on the size of the population. One important class of regulatory functions is the theta-logistic, which generalizes the logistic equation. Using this model as a motivation, this paper introduces a simple dynamical reformulation that generalizes many growth functions. The reformulation consists of two equations, one for population size, and one for the growth rate. Furthermore, the model shows that although population is density-dependent, the dynamics of the growth rate does not depend either on population size, nor on the carrying capacity. Actually, the growth equation is uncoupled from the population size equation, and the model has only two parameters, a Malthusian parameter rho and a competition coefficient theta. Distinct sign combinations of these parameters reproduce not only the family of theta-logistics, but also the van Bertalanffy, Gompertz and Potential Growth equations, among other possibilities. It is also shown that, except for two critical points, there is a general size-scaling relation that includes those appearing in the most important allometric theories, including the recently proposed Metabolic Theory of Ecology. With this model, several issues of general interest are discussed such as the growth of animal population, extinctions, cell growth and allometry, and the effect of environment over a population.

  3. Airborne measurements of nucleation mode particles I: coastal nucleation and growth rates

    Directory of Open Access Journals (Sweden)

    C. D. O'Dowd

    2007-01-01

    Full Text Available A light aircraft was equipped with a bank of Condensation Particle Counters (CPCs (50% cut from 3–5.4–9.6 nm and a nano-Scanning Mobility Particle Sizer (nSMPS and deployed along the west coast of Ireland, in the vicinity of Mace Head. The objective of the exercise was to provide high resolution micro-physical measurements of the coastal nucleation mode in order to map the spatial extent of new particle production regions and to evaluate the evolution, and associated growth rates of the coastal nucleation-mode aerosol plume. Results indicate that coastal new particle production is occurring over most areas along the land-sea interface with peak concentrations at the coastal plume-head in excess of 106 cm−3. Pseudo-Lagrangian studies of the coastal plume evolution illustrated significant growth of new particles to sizes in excess of 8 nm approximately 10 km downwind of the source region. Close to the plume head (<1 km growth rates can be as high as 123–171 nm h−1, decreasing gradually to 53–72 nm h−1 at 3 km. Further along the plume, at distances up to 10 km, the growth rates are calculated to be 17–32 nm h−1. Growth rates of this magnitude suggest that after a couple of hours, coastal nucleation mode particles can reach significant sizes where they can contribution to the regional aerosol loading.

  4. Species Diversity Enhances Predator Growth Rates

    International Nuclear Information System (INIS)

    Olson, M.H.; Jacobs, R.P.; O'Donnell, E.B.

    2007-01-01

    Predators can be important top-down regulators of community structure and are known to have both positive and negative effects on species diversity. However, little is known about the reciprocal effects of species diversity on predators. Across a set of 80 lakes in Connecticut, USA, we found a strong positive correlation between prey species diversity (using the Shannon-Weiner Diversity Index) and growth rates of largemouth bass (Micropterus salmoides). This correlation was strongest for small predators and decreased with body size. Although the underlying mechanisms are not known, the correlation is not driven by total fish abundance, predator abundance, or productivity.

  5. Sleep-Dependent Modulation of Metabolic Rate in Drosophila.

    Science.gov (United States)

    Stahl, Bethany A; Slocumb, Melissa E; Chaitin, Hersh; DiAngelo, Justin R; Keene, Alex C

    2017-08-01

    Dysregulation of sleep is associated with metabolic diseases, and metabolic rate (MR) is acutely regulated by sleep-wake behavior. In humans and rodent models, sleep loss is associated with obesity, reduced metabolic rate, and negative energy balance, yet little is known about the neural mechanisms governing interactions between sleep and metabolism. We have developed a system to simultaneously measure sleep and MR in individual Drosophila, allowing for interrogation of neural systems governing interactions between sleep and metabolic rate. Like mammals, MR in flies is reduced during sleep and increased during sleep deprivation suggesting sleep-dependent regulation of MR is conserved across phyla. The reduction of MR during sleep is not simply a consequence of inactivity because MR is reduced ~30 minutes following the onset of sleep, raising the possibility that CO2 production provides a metric to distinguish different sleep states in the fruit fly. To examine the relationship between sleep and metabolism, we determined basal and sleep-dependent changes in MR is reduced in starved flies, suggesting that starvation inhibits normal sleep-associated effects on metabolic rate. Further, translin mutant flies that fail to suppress sleep during starvation demonstrate a lower basal metabolic rate, but this rate was further reduced in response to starvation, revealing that regulation of starvation-induced changes in MR and sleep duration are genetically distinct. Therefore, this system provides the unique ability to simultaneously measure sleep and oxidative metabolism, providing novel insight into the physiological changes associated with sleep and wakefulness in the fruit fly. © Sleep Research Society 2017. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.

  6. A Longitudinal Study and Color Rating System of Acquisition Cost Growth

    Science.gov (United States)

    2017-03-23

    cost growth analysis. Ways in which this research can be carried forward include: • Collect more SAR data to further populate our research database... Growth Cory N. D’Amico Follow this and additional works at: https://scholar.afit.edu/etd Part of the Finance and Financial Management Commons This...and Color Rating System of Acquisition Cost Growth " (2017). Theses and Dissertations. 781. https://scholar.afit.edu/etd/781 A Longitudinal

  7. Effect of extremely low frequency electromagnetic fields on growth rate and morphology of bacteria.

    Science.gov (United States)

    Inhan-Garip, Ayse; Aksu, Burak; Akan, Zafer; Akakin, Dilek; Ozaydin, A Nilufer; San, Tangul

    2011-12-01

    To determine the effect of extremely low frequency (bacteria and to determine any morphological changes that might have been caused by ELF-EMF. Six bacterial strains, three Gram-negative and three Gram-positive were subjected to 50 Hz, 0.5 mT ELF-EMF for 6 h. To determine growth rate after ELF-EMF application, bacteria exposed to ELF-EMF for 3 h were collected, transferred to fresh medium and cultured without field application for another 4 h. Growth-rate was determined by optical density (OD) measurements made every hour. Morphological changes were determined with Transmission electron microscopy (TEM) for two gram-negative and two gram-positive strains collected after 3 h of field application. A decrease in growth rate with respect to control samples was observed for all strains during ELF-EMF application. The decrease in growth-rate continued when exposed bacteria were cultured without field application. Significant ultrastructural changes were observed in all bacterial strains, which were seen to resemble the alterations caused by cationic peptides. This study shows that ELF-EMF induces a decrease in growth rate and morphological changes for both Gram-negative and Gram-positive bacteria.

  8. Inferring time derivatives including cell growth rates using Gaussian processes

    Science.gov (United States)

    Swain, Peter S.; Stevenson, Keiran; Leary, Allen; Montano-Gutierrez, Luis F.; Clark, Ivan B. N.; Vogel, Jackie; Pilizota, Teuta

    2016-12-01

    Often the time derivative of a measured variable is of as much interest as the variable itself. For a growing population of biological cells, for example, the population's growth rate is typically more important than its size. Here we introduce a non-parametric method to infer first and second time derivatives as a function of time from time-series data. Our approach is based on Gaussian processes and applies to a wide range of data. In tests, the method is at least as accurate as others, but has several advantages: it estimates errors both in the inference and in any summary statistics, such as lag times, and allows interpolation with the corresponding error estimation. As illustrations, we infer growth rates of microbial cells, the rate of assembly of an amyloid fibril and both the speed and acceleration of two separating spindle pole bodies. Our algorithm should thus be broadly applicable.

  9. Impact of Macroeconomic Policies on Poverty and Unemployment Rates in Nigeria, Implications for Attaining Inclusive Growth

    Directory of Open Access Journals (Sweden)

    Philip Nwosa

    2016-04-01

    Full Text Available This paper examined the effect of macroeconomic policies on unemployment and poverty rates in Nigeria from 1980 to 2013 with implication to achieving inclusive growth. The inability of macroeconomic policies in addressing the rising issues unemployment and poverty rates in Nigeria despite the impressive economic growth experience over the last decades has increasingly called for the need for the pursuance of inclusive growth to address the social issues of unemployment and poverty rate. Previous studies have not considered the extent to which macroeconomic policies affects unemployment and poverty rate in Nigeria, and the implication of this relationship to the attainment of inclusive growth in Nigeria. The study adopts the Ordinary Least Square (OLS technique. The study observed that among macroeconomic policy variables only exchange rate significantly influenced unemployment rate while only fiscal policy significantly influenced and poverty rate. This implies that present macroeconomic policies in Nigeria do not guarantee the attainment of inclusive growth in Nigeria. The contribution of the paper is that to achieve inclusive growth that guarantees high employment and reduced poverty rate, there is the need for a re-examination of macroeconomic policy management in Nigeria.

  10. Exchange Rate Volatility and Employment Growth in Developing Countries: Evidence from Turkey

    OpenAIRE

    Demir, Firat

    2010-01-01

    Employing a unique panel of 691 private firms that accounted for 26% of total value-added in manufacturing in Turkey, the paper explores the impacts of exchange rate volatility on employment growth during the period of 1983 - 2005. The empirical analysis using a variety of specifications, estimation techniques, and robustness tests suggests that exchange rate volatility has a statistically and economically significant employment growth reducing effect on manufacturing firms. Using point estim...

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

    Science.gov (United States)

    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.

  12. Temperature dependence of dose rate laser simulation adequacy

    International Nuclear Information System (INIS)

    Skorobogatov, P.K.; Nikiforov, A.Y.; Demidov, A.A.

    1999-01-01

    2-D numerical modeling was carried out to analyze the temperature dependence of dose rate laser simulation adequacy in application to p-n junction ionising current. Experimental validation was performed using test structure in the temperature range of 0 to 100 deg.C. (authors)

  13. Colorimetry provides a rapid objective measurement of de novo hair growth rate in mice.

    Science.gov (United States)

    Tzung, Tien-Yi; Yang, Chia-Yi; Huang, Yung-Chang; Kao, Fu-Jen

    2009-11-01

    Depilated mice have been used as a test platform for hair growth-regulating agents. However, currently available assessment tools for hair growth in mice are less than ideal. Tristimulus colorimetry of the fur color of depilated agouti, albino, and black mice with L*, a*, and b* values were performed daily until the full growth of pelage. Using light-emitting diode (LED) irradiation (650 and 890 nm) with a daily dose of 3.5 J/cm(2) as hair growth regulators, the hair growth rates observed by the global assessment were compared with those derived from colorimetry. In contrast to a* and b* values, L* values changed more drastically over time in the anagen phase regardless of fur color. Unlike the inhibitory effect of 650 nm irradiation, LED of 890 nm promoted de novo hair regrowth in mice. The difference in hair growth rates detected by colorimetry paralleled the observation made by the global assessment. The L* value of fur color obtained by tristimulus colorimetry was a sensitive yet quantitative indicator of de novo hair growth, and could be used to project the hair growth rate in mice.

  14. 4EBP-Dependent Signaling Supports West Nile Virus Growth and Protein Expression.

    Science.gov (United States)

    Shives, Katherine D; Massey, Aaron R; May, Nicholas A; Morrison, Thomas E; Beckham, J David

    2016-10-18

    West Nile virus (WNV) is a (+) sense, single-stranded RNA virus in the Flavivirus genus. WNV RNA possesses an m7 GpppN m 5' cap with 2'- O -methylation that mimics host mRNAs preventing innate immune detection and allowing the virus to translate its RNA genome through the utilization of cap-dependent translation initiation effectors in a wide variety of host species. Our prior work established the requirement of the host mammalian target of rapamycin complex 1 (mTORC1) for optimal WNV growth and protein expression; yet, the roles of the downstream effectors of mTORC1 in WNV translation are unknown. In this study, we utilize gene deletion mutants in the ribosomal protein kinase called S6 kinase (S6K) and eukaryotic translation initiation factor 4E-binding protein (4EBP) pathways downstream of mTORC1 to define the role of mTOR-dependent translation initiation signals in WNV gene expression and growth. We now show that WNV growth and protein expression are dependent on mTORC1 mediated-regulation of the eukaryotic translation initiation factor 4E-binding protein/eukaryotic translation initiation factor 4E-binding protein (4EBP/eIF4E) interaction and eukaryotic initiation factor 4F (eIF4F) complex formation to support viral growth and viral protein expression. We also show that the canonical signals of mTORC1 activation including ribosomal protein s6 (rpS6) and S6K phosphorylation are not required for WNV growth in these same conditions. Our data suggest that the mTORC1/4EBP/eIF4E signaling axis is activated to support the translation of the WNV genome.

  15. 4EBP-Dependent Signaling Supports West Nile Virus Growth and Protein Expression

    Directory of Open Access Journals (Sweden)

    Katherine D. Shives

    2016-10-01

    Full Text Available West Nile virus (WNV is a (+ sense, single-stranded RNA virus in the Flavivirus genus. WNV RNA possesses an m7GpppNm 5′ cap with 2′-O-methylation that mimics host mRNAs preventing innate immune detection and allowing the virus to translate its RNA genome through the utilization of cap-dependent translation initiation effectors in a wide variety of host species. Our prior work established the requirement of the host mammalian target of rapamycin complex 1 (mTORC1 for optimal WNV growth and protein expression; yet, the roles of the downstream effectors of mTORC1 in WNV translation are unknown. In this study, we utilize gene deletion mutants in the ribosomal protein kinase called S6 kinase (S6K and eukaryotic translation initiation factor 4E-binding protein (4EBP pathways downstream of mTORC1 to define the role of mTOR-dependent translation initiation signals in WNV gene expression and growth. We now show that WNV growth and protein expression are dependent on mTORC1 mediated-regulation of the eukaryotic translation initiation factor 4E-binding protein/eukaryotic translation initiation factor 4E-binding protein (4EBP/eIF4E interaction and eukaryotic initiation factor 4F (eIF4F complex formation to support viral growth and viral protein expression. We also show that the canonical signals of mTORC1 activation including ribosomal protein s6 (rpS6 and S6K phosphorylation are not required for WNV growth in these same conditions. Our data suggest that the mTORC1/4EBP/eIF4E signaling axis is activated to support the translation of the WNV genome.

  16. Growth dynamics of the energy dependent economy. Die Wachstumsdynamik der energieabhaengigen Wirtschaft

    Energy Technology Data Exchange (ETDEWEB)

    Kuemmel, R

    1980-01-01

    In Part I the industrial process is analysed and a functional, quantitative definition of capital, by which (instrumental) capital is related to automation is proposed. In this way capital can be defined and measured precisely in terms of physical work done and information processes by machines. Pollution, defined as entropy increase in the economic system, is considered in its various manifestations and taken into account by a product of specific pollution functions. In Part II the role of creativity as a generator of growth intervals and system-characteristics is discussed. The conditions of integrability of the equation of growth are pointed out, thus elucidating the requirements for the existence of a production function which unequivocally depends upon capital, labor and energy. This results in a set of differential equations for the elasticities of production. The states of total automation and full capital employment are analyzed and the extremum principles which govern the quantitative input of the production factors are given. In Part III the dependence of the elasticities of production on the factors of production are examined with the help of the integrability conditions. The path of balanced economic growth is analyzed along which the growth of production within a growth-interval is described by a Cobb-Douglas production function. Scenarios of energy crises are calculated, and simple estimates are given.

  17. Effect of different saccharides on growth, sporulation rate and d ...

    African Journals Online (AJOL)

    MFCS

    2012-05-17

    May 17, 2012 ... general, high sporulation rate was related with high growth rate and high viable cell count (>1.5 x 1012 cfu/ml). .... The sterile culture medium (180 ml) in a 1000 ml Erlenmeyer flask was ... The column temperature was set at 85°C. A series of ..... inactivation of certain sugar-metabolizing operons, such as lac ...

  18. Growth rates and energy intake of hand-reared cheetah cubs (Acinonyx jubatus) in South Africa.

    Science.gov (United States)

    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. © 2011 Blackwell Verlag GmbH.

  19. Neutron Scattering in Hydrogenous Moderators, Studied by Time Dependent Reaction Rate Method

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, L G; Moeller, E; Purohit, S N

    1966-03-15

    The moderation and absorption of a neutron burst in water, poisoned with the non-1/v absorbers cadmium and gadolinium, has been followed on the time scale by multigroup calculations, using scattering kernels for the proton gas and the Nelkin model. The time dependent reaction rate curves for each absorber display clear differences for the two models, and the separation between the curves does not depend much on the absorber concentration. An experimental method for the measurement of infinite medium reaction rate curves in a limited geometry has been investigated. This method makes the measurement of the time dependent reaction rate generally useful for thermalization studies in a small geometry of a liquid hydrogenous moderator, provided that the experiment is coupled to programs for the calculation of scattering kernels and time dependent neutron spectra. Good agreement has been found between the reaction rate curve, measured with cadmium in water, and a calculated curve, where the Haywood kernel has been used.

  20. Temperature dependence of muonium reaction rates in the gas phase

    International Nuclear Information System (INIS)

    Fleming, D.G.; Garner, D.M.; Mikula, R.J.; British Columbia Univ., Vancouver

    1981-01-01

    A study of the temperature dependence of reaction rates has long been an important tool in establishing reaction pathways in chemical reactions. This is particularly true for the reactions of muonium (in comparison with those of hydrogen) since a measurement of the activation energy for chemical reaction is sensitive to both the height and the position of the potential barrier in the reaction plane. For collision controlled reactions, on the other hand, the reaction rate is expected to exhibit a weak T 1 sup(/) 2 dependence characteristic of the mean collision velocity. These concepts are discussed and their effects illustrated in a comparison of the chemical and spin exchange reaction rates of muonium and hydrogen in the temperature range approx.300-approx.500 K. (orig.)

  1. Arabidopsis cryptochrome 1 is a soluble protein mediating blue light-dependent regulation of plant growth and development

    International Nuclear Information System (INIS)

    Lin ChenTao; Ahmad, M.; Cashmore, A.R.

    1996-01-01

    Cryptochrome 1 (CRY1) is a flavin-type blue type receptor of Arabidopsis thaliana which mediates inhibition of hypocotyl elongation. In the work described in this report it is demonstrated that CRY1 is a soluble protein expressed in both young seedlings grown either in the dark or under light, and in different organs of adult plants. The functional role of CRY1 was further investigated using transgenic Arabidopsis plants overexpressing CRY1. It is demonstrated that overexpression of CRY1 resulted in hypersensitivity to blue, UV-A, and green light for the inhibition of hypocotyl elongation response. Transgenic plants overexpressing CRY1 also exhibited a dwarf phenotype with reduced size in almost every organ. This was in keeping with the previous observation of reciprocal alterations found in hy4 mutant plants and is consistent with a hypothesis that CRY1 mediates a light-dependent process resulting in a general inhibitory effect on plant growth. In addition, transgenic plants overexpressing CRY1 showed increased anthocyanin accumulation in response to blue, UV-A, and green light in a fluence rate-dependent manner. This increase in anthocyanin accumulation in transgenic plants was shown to be concomitant with increased blue light-induction of CHS gene expression. It is concluded that CRY1 is a photoreceptor mediating blue light-dependent regulation of gene expression in addition to its affect on plant growth. (author)

  2. A model for rate-dependent but time-independent material behavior in cyclic plasticity

    International Nuclear Information System (INIS)

    Dafalias, Y.F.; Ramey, M.R.; Sheikh, I.

    1977-01-01

    It is the purpose of this paper to present a model for rate-dependent but time independent material behavior under cyclic loading in the plastic range. What is referred to as time independent behavior here, is the absence of creep and relaxation phenomena from the behavior of the model. The notion of plastic internal variables (piv) is introduced, as properly invariant scalars or second order tensors, whose constitutive relations are rate-type equations not necessarily homogeneous of oder one in the rates, as it would be required for independent plasticity. The concept of a yield surface in the strain space and a loading function in terms of the total strain rate is introduced, where the sign of the loading function defines zero or non-zero value of the rate of piv. Thus rate dependence is achieved without time dependent behavior (no creep or relaxation). In addition, discrete memory parameters associated with the most recent event of unloading-reloading in different directions enter the constitutive relations for the piv. A particular form of the constitutive relations is assumed, where the rate of piv is a linear combination of the strain rate components, with coefficients depending on the second invariant of the strain rate tensor, which can be viewed as a scalar measure of the rate of deformation in the multiaxial case and a direct generalization of the uniaxial strain rate. This leads to a particularly simple form of the constitutive relations resembling the ones for rate independent plasticity. The uniaxial counterpart would be a relation between the plastic strain rate (as one of the piv) and the total strain rate through a plastic modulus which depends on the strain rate, the piv, and the discrete memory parameters

  3. Periodic matrix population models: growth rate, basic reproduction number, and entropy.

    Science.gov (United States)

    Bacaër, Nicolas

    2009-10-01

    This article considers three different aspects of periodic matrix population models. First, a formula for the sensitivity analysis of the growth rate lambda is obtained that is simpler than the one obtained by Caswell and Trevisan. Secondly, the formula for the basic reproduction number R0 in a constant environment is generalized to the case of a periodic environment. Some inequalities between lambda and R0 proved by Cushing and Zhou are also generalized to the periodic case. Finally, we add some remarks on Demetrius' notion of evolutionary entropy H and its relationship to the growth rate lambda in the periodic case.

  4. Physiological levels of nitrate support anoxic growth by denitrification of Pseudomonas aeruginosa at growth rates reported in cystic fibrosis lungs and sputum

    DEFF Research Database (Denmark)

    Line, Laura; Alhede, Morten; Kolpen, Mette

    2014-01-01

    denitrification. The growth rate of P. aeruginosa achieved by denitrification at physiological levels (~400 μM) of nitrate (NO(-) 3) is however, not known. Therefore, we have measured growth rates of anoxic cultures of PAO1 and clinical isolates (n = 12) in LB media supplemented with NO(-) 3 and found...... a significant increase of growth when supplementing PAO1 and clinical isolates with ≥150 μM NO(-) 3 and 100 μM NO(-) 3, respectively. An essential contribution to growth by denitrification was demonstrated by the inability to establish a significantly increased growth rate by a denitrification deficient Δnir...... of the four N-oxide reductases in PAO1 (Nar, Nir, Nor, Nos) further verified the engagement of denitrification, showing a transient increase in activation and expression and rapid consumption of NO(-) 3 followed by a transient increase of NO(-) 2. Growth rates obtained by denitrification in this study were...

  5. Evidence for density-dependent changes in growth, downstream movement, and size of Chinook salmon subyearlings in a large-river landscape

    Science.gov (United States)

    Connor, William P.; Tiffan, Kenneth F.; Plumb, John M.; Moffit, Christine M.

    2013-01-01

    We studied the growth rate, downstream movement, and size of naturally produced fall Chinook Salmon Oncorhynchus tshawytscha subyearlings (age 0) for 20 years in an 8th-order river landscape with regulated riverine upstream rearing areas and an impounded downstream migration corridor. The population transitioned from low to high abundance in association with U.S. Endangered Species Act and other federally mandated recovery efforts. The mean growth rate of parr in the river did not decline with increasing abundance, but during the period of higher abundance the timing of dispersal from riverine habitat into the reservoir averaged 17 d earlier and the average size at the time of downstream dispersal was smaller by 10 mm and 1.8 g. Changes in apparent abundance, measured by catch per unit effort, largely explained the time of dispersal, measured by median day of capture, in riverine habitat. The growth rate of smolts in the reservoir declined from an average of 0.6 to 0.2 g/d between the abundance periods because the reduction in size at reservoir entry was accompanied by a tendency to migrate rather than linger and by increasing concentrations of smolts in the reservoir. The median date of passage through the reservoir was 14 d earlier on average, and average smolt size was smaller by 38 mm and 22.0 g, in accordance with density-dependent behavioral changes reflected by decreased smolt growth. Unexpectedly, smolts during the high-abundance period had begun to reexpress the migration timing and size phenotypes observed before the river was impounded, when abundance was relatively high. Our findings provide evidence for density-dependent phenotypic change in a large river that was influenced by the expansion of a recovery program. Thus, this study shows that efforts to recover native fishes can have detectable effects in large-river landscapes. The outcome of such phenotypic change, which will be an important area of future research, can only be fully judged by

  6. Microscopic Rate Constants of Crystal Growth from Molecular Dynamic Simulations Combined with Metadynamics

    Directory of Open Access Journals (Sweden)

    Dániel Kozma

    2012-01-01

    Full Text Available Atomistic simulation of crystal growth can be decomposed into two steps: the determination of the microscopic rate constants and a mesoscopic kinetic Monte Carlo simulation. We proposed a method to determine kinetic rate constants of crystal growth. We performed classical molecular dynamics on the equilibrium liquid/crystal interface of argon. Metadynamics was used to explore the free energy surface of crystal growth. A crystalline atom was selected at the interface, and it was displaced to the liquid phase by adding repulsive Gaussian potentials. The activation free energy of this process was calculated as the maximal potential energy density of the Gaussian potentials. We calculated the rate constants at different interfacial structures using the transition state theory. In order to mimic real crystallization, we applied a temperature difference in the calculations of the two opposite rate constants, and they were applied in kinetic Monte Carlo simulation. The novelty of our technique is that it can be used for slow crystallization processes, while the simple following of trajectories can be applied only for fast reactions. Our method is a possibility for determination of elementary rate constants of crystal growth that seems to be necessary for the long-time goal of computer-aided crystal design.

  7. Concurrent growth rate and transcript analyses reveal essential gene stringency in Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Shan Goh

    Full Text Available BACKGROUND: Genes essential for bacterial growth are of particular scientific interest. Many putative essential genes have been identified or predicted in several species, however, little is known about gene expression requirement stringency, which may be an important aspect of bacterial physiology and likely a determining factor in drug target development. METHODOLOGY/PRINCIPAL FINDINGS: Working from the premise that essential genes differ in absolute requirement for growth, we describe silencing of putative essential genes in E. coli to obtain a titration of declining growth rates and transcript levels by using antisense peptide nucleic acids (PNA and expressed antisense RNA. The relationship between mRNA decline and growth rate decline reflects the degree of essentiality, or stringency, of an essential gene, which is here defined by the minimum transcript level for a 50% reduction in growth rate (MTL(50. When applied to four growth essential genes, both RNA silencing methods resulted in MTL(50 values that reveal acpP as the most stringently required of the four genes examined, with ftsZ the next most stringently required. The established antibacterial targets murA and fabI were less stringently required. CONCLUSIONS: RNA silencing can reveal stringent requirements for gene expression with respect to growth. This method may be used to validate existing essential genes and to quantify drug target requirement.

  8. Facilitating control of fed-batch fermentation processes by monitoring the growth rates of saccharomyces cerevisiae

    NARCIS (Netherlands)

    Keulers, M.L.B.; Ariaans, L.J.J.M.; Soeterboek, R.; Giuseppin, M.

    1994-01-01

    In this paper we present a growth rate controller for a fed-batch bioprocess. An observer estimates the growth rate. The observer is based on knowledge about the stoichiometric relations of the process. Furthermore, the observer needs online measurements of the oxygen uptake rate and the

  9. EFFECT OF SODIUM DODECYLBENZENESULFONIC ACID (SDBS ON THE GROWTH RATE AND MORPHOLOGY OF BORAX CRYSTAL

    Directory of Open Access Journals (Sweden)

    Suharso Suharso

    2010-06-01

    Full Text Available An investigation of the effect of sodium dodecylbenzenesulfonic acid (SDBS on both growth rate and morphology of borax crystal has been carried out.  This experiment was carried out at temperature of 25 °C and relative supersaturation of 0.21 and 0.74 under in situ cell optical microscopy method.  The result shows that SDBS inhibits the growth rate and changes the morphology of borax crystal.   Keywords: Borax; growth rate; crystallization, SDBS

  10. Using measurements of the aerosol charging state in determination of the particle growth rate and the proportion of ion-induced nucleation

    Directory of Open Access Journals (Sweden)

    J. Leppä

    2013-01-01

    Full Text Available The fraction of charged nucleation mode particles as a function of particle diameter depends on the particle growth rate and the proportion of particles formed via ion-induced nucleation. In this study we have tested the applicability of recent data analysis methods to determine the growth rate and the proportion of ion-induced nucleation from the measured charged fractions. For this purpose we have conducted a series of aerosol dynamic simulations covering a wide range of atmospheric conditions. The growth rate and initial fraction of charged particles were estimated from simulated data using these methods and compared with the values obtained directly from the simulations. We found that the data analysis methods used in this study should not be used when the nuclei growth rate is less than ~3 nm h−1, or when charged particles grow much more rapidly than neutral ones. Furthermore, we found that the difference in removal rates of neutral and charged particles should be taken into account when estimating the proportion of ion-induced nucleation. Neglecting the higher removal rate of charged particles compared with that of neutral ones could result in an underestimation of the proportion of ion-induced nucleation by up to a factor of 2. This underestimation is further increased if charged particles grow more rapidly than neutral ones. We also provided a simple way of assessing whether these methods are suitable for analyzing data measured under specific conditions. The assessment procedure was illustrated using a few examples of actual measurement sites with a more detailed examination of the typical conditions observed at the SMEAR II station in Hyytiälä, Finland.

  11. Micromechanisms of fatigue crack growth in polycarbonate polyurethane: Time dependent and hydration effects.

    Science.gov (United States)

    Ford, Audrey C; Gramling, Hannah; Li, Samuel C; Sov, Jessica V; Srinivasan, Amrita; Pruitt, Lisa A

    2018-03-01

    Polycarbonate polyurethane has cartilage-like, hygroscopic, and elastomeric properties that make it an attractive material for orthopedic joint replacement application. However, little data exists on the cyclic loading and fracture behavior of polycarbonate polyurethane. This study investigates the mechanisms of fatigue crack growth in polycarbonate polyurethane with respect to time dependent effects and conditioning. We studied two commercially available polycarbonate polyurethanes, Bionate® 75D and 80A. Tension testing was performed on specimens at variable time points after being removed from hydration and variable strain rates. Fatigue crack propagation characterized three aspects of loading. Study 1 investigated the impact of continuous loading (24h/day) versus intermittent loading (8-10h/day) allowing for relaxation overnight. Study 2 evaluated the effect of frequency and study 3 examined the impact of hydration on the fatigue crack propagation in polycarbonate polyurethane. Samples loaded intermittently failed instantaneously and prematurely upon reloading while samples loaded continuously sustained longer stable cracks. Crack growth for samples tested at 2 and 5Hz was largely planar with little crack deflection. However, samples tested at 10Hz showed high degrees of crack tip deflection and multiple crack fronts. Crack growth in hydrated samples proceeded with much greater ductile crack mouth opening displacement than dry samples. An understanding of the failure mechanisms of this polymer is important to assess the long-term structural integrity of this material for use in load-bearing orthopedic implant applications. Copyright © 2018 Elsevier Ltd. All rights reserved.

  12. ENVIRONMENTAL DEPENDENCE OF THE GALAXY MERGER RATE IN A ΛCDM UNIVERSE

    International Nuclear Information System (INIS)

    Jian, Hung-Yu; Chiueh, Tzihong; Lin Lihwai

    2012-01-01

    We make use of four galaxy catalogs based on four different semi-analytical models (SAMs) implemented in the Millennium Simulation to study the environmental effects and the model dependence of the galaxy merger rate. We begin the analyses by finding that the galaxy merger rate in SAMs has a mild redshift evolution with luminosity-selected samples in the evolution-corrected B-band magnitude range,–21 ≤ M e B ≤ –19, consistent with the results of previous works. To study the environmental dependence of the galaxy merger rate, we adopt two estimators, the local overdensity (1 + δ n ), defined as the surface density from the nth nearest neighbor (n = 6 is chosen in this study), and the host halo mass M h . We find that the galaxy merger rate F mg shows a strong dependence on the local overdensity (1 + δ n ) and the dependence is similar at all redshifts. For the overdensity estimator, the merger rate F mg is found to be about twenty times larger in the densest regions than in underdense ones in two of the four SAMs, while it is roughly four times higher in the other two. In other words, the discrepancies of the merger rate difference between the two extremes can differ by a factor of ∼5 depending on the SAMs adopted. On the other hand, for the halo mass estimator, F mg does not monotonically increase with the host halo mass M h but peaks in the M h range between 10 12 and 10 13 h –1 M ☉ , which corresponds to group environments. The high merger rate in high local density regions corresponds primarily to the high merger rate in group environments. In addition, we also study the merger probability of 'close pairs' identified using the projected separation and the line-of-sight velocity difference C mg and the merger timescale T mg ; these are two important quantities for observations to convert the pair fraction N c into the galaxy merger rate. We discover that T mg has a weak dependence on environment and different SAMs, and is about 2 Gyr old at z

  13. Generation and growth rates of nonlinear distortions in a traveling wave tube

    International Nuclear Information System (INIS)

    Woehlbier, John G.; Dobson, Ian; Booske, John H.

    2002-01-01

    The structure of a steady state multifrequency model of a traveling wave tube amplifier is exploited to describe the generation of intermodulation frequencies and calculate their growth rates. The model describes the evolution of Fourier coefficients of circuit and electron beam quantities and has the form of differential equations with quadratic nonlinearities. Intermodulation frequencies are sequentially generated by the quadratic nonlinearities in a series solution of the differential equations. A formula for maximum intermodulation growth rates is derived and compared to simulation results

  14. On Decidable Growth-Rate Properties of Imperative Programs

    Directory of Open Access Journals (Sweden)

    Amir M. Ben-Amram

    2010-05-01

    Full Text Available In 2008, Ben-Amram, Jones and Kristiansen showed that for a simple "core" programming language - an imperative language with bounded loops, and arithmetics limited to addition and multiplication - it was possible to decide precisely whether a program had certain growth-rate properties, namely polynomial (or linear bounds on computed values, or on the running time. This work emphasized the role of the core language in mitigating the notorious undecidability of program properties, so that one deals with decidable problems. A natural and intriguing problem was whether more elements can be added to the core language, improving its utility, while keeping the growth-rate properties decidable. In particular, the method presented could not handle a command that resets a variable to zero. This paper shows how to handle resets. The analysis is given in a logical style (proof rules, and its complexity is shown to be PSPACE-complete (in contrast, without resets, the problem was PTIME. The analysis algorithm evolved from the previous solution in an interesting way: focus was shifted from proving a bound to disproving it, and the algorithm works top-down rather than bottom-up.

  15. Energy and rate dependence of diagnostic x-ray exposure meters

    International Nuclear Information System (INIS)

    Wagner, L.K.; Cerra, F.; Conway, B.; Fewell, T.R.; Ohlhaber, T.R.

    1988-01-01

    Variations in x-ray exposure measurements among a variety of contemporary diagnostic exposure meters are investigated. Variations may result from systematic errors due to calibration, beam-quality dependence and exposure-rate dependence. It is concluded that the majority of general purpose diagnostic meters will agree to within 10% of each other if exposure rates are below 1.3 mC kg-1S-1 of air (5 R s-1) and beam qualities are typical for general purpose radiology, excluding mammography. For exposure rates comparable to those in barium enema radiography the variations can range up to 25% or more. Variations up to 40% were observed among general purpose exposure meters at mammographic beam qualities. In the mammographic range, mammographic (thin window) exposure meters varied by no more than 2%

  16. Stiff mutant genes of Phycomyces target turgor pressure and wall mechanical properties to regulate elongation growth rate

    Directory of Open Access Journals (Sweden)

    Joseph K. E. Ortega

    2012-05-01

    Full Text Available 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 four genes; madD, madE, madF and madG. 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. 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 deformation rates of the wall within the growth zone and growth zone length are smaller for stiff mutant sporangiophores compared to wild type. These findings explain the diminished tropic responses of the stiff mutant sporangiophores and suggest that the defective genes affect the amount of wall-building material delivered to the inner

  17. Hoof Growth Rates of the European Roe Deer (Capreolus capreolus for Dating the Hoof’s Isotopic Archive

    Directory of Open Access Journals (Sweden)

    Benjamin D. Hafner

    2017-11-01

    Full Text Available Hooves preserve the isotopic information laid down during their growth and may be used for reconstruction of animal feeding history. To assign certain positions along hooves to corresponding times, growth rates are required. Hoof growth rates are known for domestic animals; however, they cannot be obtained easily in wild animals. We estimated the hoof growth rate of the European roe deer (Capreolus capreolus L. by using the immediate drop in δ13C along the hoof as a tag that is assigned to the date of maize (Zea mays L. harvest. Keratin samples were taken each mm along 17 hooves and analyzed for their δ13C. A linear regression between (1 time differences of expected maize harvest to animal death and (2 distances between the points of the δ13C drop to the periople yielded the growth rate. Mean hoof growth rate was 0.122 mm/day (95% CI 0.014 mm/day and 0.365%/day (±0.026%/day of the hoof length and within the range of domestic animals. The method may be applied to determine growth rates of other incrementally growing tissues. Our estimated growth rate fosters dating isotopic information in hooves, facilitating research on feed resources and space use of roe deer.

  18. [Dose rate-dependent cellular and molecular effects of ionizing radiation].

    Science.gov (United States)

    Przybyszewski, Waldemar M; Wideł, Maria; Szurko, Agnieszka; Maniakowski, Zbigniew

    2008-09-11

    The aim of radiation therapy is to kill tumor cells while minimizing damage to normal cells. The ultimate effect of radiation can be apoptotic or necrotic cell death as well as cytogenetic damage resulting in genetic instability and/or cell death. The destructive effects of radiation arise from direct and indirect ionization events leading to peroxidation of macromolecules, especially those present in lipid-rich membrane structures as well as chromatin lipids. Lipid peroxidative end-products may damage DNA and proteins. A characteristic feature of radiation-induced peroxidation is an inverse dose-rate effect (IDRE), defined as an increase in the degree of oxidation(at constant absorbed dose) accompanying a lower dose rate. On the other hand, a low dose rate can lead to the accumulation of cells in G2, the radiosensitive phase of the cell cycle since cell cycle control points are not sensitive to low dose rates. Radiation dose rate may potentially be the main factor improving radiotherapy efficacy as well as affecting the intensity of normal tissue and whole-body side effects. A better understanding of dose rate-dependent biological effects may lead to improved therapeutic intervention and limit normal tissue reaction. The study reviews basic biological effects that depend on the dose rate of ionizing radiation.

  19. Data compilation of respiration, feeding, and growth rates of marine pelagic organisms

    DEFF Research Database (Denmark)

    2013-01-01

    's adaptation to the environment, with consequently less universal mass scaling properties. Data on body mass, maximum ingestion and clearance rates, respiration rates and maximum growth rates of animals living in the ocean epipelagic were compiled from the literature, mainly from original papers but also from...

  20. Growth but not photosynthesis response of a host plant to infection by a holoparasitic plant depends on nitrogen supply.

    Directory of Open Access Journals (Sweden)

    Hao Shen

    Full Text Available Parasitic plants can adversely influence the growth of their hosts by removing resources and by affecting photosynthesis. Such negative effects depend on resource availability. However, at varied resource levels, to what extent the negative effects on growth are attributed to the effects on photosynthesis has not been well elucidated. Here, we examined the influence of nitrogen supply on the growth and photosynthesis responses of the host plant Mikania micrantha to infection by the holoparasite Cuscuta campestris by focusing on the interaction of nitrogen and infection. Mikania micrantha plants fertilized at 0.2, 1 and 5 mM nitrate were grown with and without C. campestris infection. We observed that the infection significantly reduced M. micrantha growth at each nitrate fertilization and more severely at low than at high nitrate. Such alleviation at high nitrate was largely attributed to a stronger influence of infection on root biomass at low than at high nitrate fertilization. However, although C. campestris altered allometry and inhibited host photosynthesis, the magnitude of the effects was independent of nitrate fertilizations. The infection reduced light saturation point, net photosynthesis at saturating irradiances, apparent quantum yield, CO2 saturated rate of photosynthesis, carboxylation efficiency, the maximum carboxylation rate of Rubisco, and maximum light-saturated rate of electron transport, and increased light compensation point in host leaves similarly across nitrate levels, corresponding to a similar magnitude of negative effects of the parasite on host leaf soluble protein and Rubisco concentrations, photosynthetic nitrogen use efficiency and stomatal conductance across nitrate concentrations. Thus, the more severe inhibition in host growth at low than at high nitrate supplies cannot be attributed to a greater parasite-induced reduction in host photosynthesis, but the result of a higher proportion of host resources

  1. Growth but Not Photosynthesis Response of a Host Plant to Infection by a Holoparasitic Plant Depends on Nitrogen Supply

    Science.gov (United States)

    Shen, Hao; Xu, Shu-Jun; Hong, Lan; Wang, Zhang-Ming; Ye, Wan-Hui

    2013-01-01

    Parasitic plants can adversely influence the growth of their hosts by removing resources and by affecting photosynthesis. Such negative effects depend on resource availability. However, at varied resource levels, to what extent the negative effects on growth are attributed to the effects on photosynthesis has not been well elucidated. Here, we examined the influence of nitrogen supply on the growth and photosynthesis responses of the host plant Mikania micrantha to infection by the holoparasite Cuscuta campestris by focusing on the interaction of nitrogen and infection. Mikania micrantha plants fertilized at 0.2, 1 and 5 mM nitrate were grown with and without C. campestris infection. We observed that the infection significantly reduced M. micrantha growth at each nitrate fertilization and more severely at low than at high nitrate. Such alleviation at high nitrate was largely attributed to a stronger influence of infection on root biomass at low than at high nitrate fertilization. However, although C. campestris altered allometry and inhibited host photosynthesis, the magnitude of the effects was independent of nitrate fertilizations. The infection reduced light saturation point, net photosynthesis at saturating irradiances, apparent quantum yield, CO2 saturated rate of photosynthesis, carboxylation efficiency, the maximum carboxylation rate of Rubisco, and maximum light-saturated rate of electron transport, and increased light compensation point in host leaves similarly across nitrate levels, corresponding to a similar magnitude of negative effects of the parasite on host leaf soluble protein and Rubisco concentrations, photosynthetic nitrogen use efficiency and stomatal conductance across nitrate concentrations. Thus, the more severe inhibition in host growth at low than at high nitrate supplies cannot be attributed to a greater parasite-induced reduction in host photosynthesis, but the result of a higher proportion of host resources transferred to the parasite at

  2. Growth kinetics and initial stage growth during plasma-enhanced Ti atomic layer deposition

    CERN Document Server

    Kim, H

    2002-01-01

    We have investigated the growth kinetics of plasma-enhanced Ti atomic layer deposition (ALD) using a quartz crystal microbalance. Ti ALD films were grown at temperatures from 20 to 200 deg. C using TiCl sub 4 as a source gas and rf plasma-produced atomic H as the reducing agent. Postdeposition ex situ chemical analyses of thin films showed that the main impurity is oxygen, mostly incorporated during the air exposure prior to analysis. The thickness per cycle, corresponding to the growth rate, was measured by quartz crystal microbalance as a function of various key growth parameters, including TiCl sub 4 and H exposure time, rf plasma power, and sample temperature. The growth rates were independent of TiCl sub 4 exposure above 1x10 sup 3 L, indicating typical ALD mode growth. The key kinetic parameters for Cl extraction reaction and TiCl sub 4 adsorption kinetics were obtained and the growth kinetics were modeled to predict the growth rates based upon these results. Also, the dependency of growth kinetics on d...

  3. HEALTH CARE SPENDING GROWTH AND THE FUTURE OF U.S. TAX RATES

    Science.gov (United States)

    Baicker, Katherine; Skinner, Jonathan S.

    2011-01-01

    The fraction of GDP devoted to health care in the United States is the highest in the world and rising rapidly. Recent economic studies have highlighted the growing value of health improvements, but less attention has been paid to the efficiency costs of tax-financed spending to pay for such improvements. This paper uses a life cycle model of labor supply, saving, and longevity improvement to measure the balanced-budget impact of continued growth in the Medicare and Medicaid programs. The model predicts that top marginal tax rates could rise to 70 percent by 2060, depending on the progressivity of future tax changes. The deadweight loss of the tax system is greater when the financing is more progressive. If the share of taxes paid by high-income taxpayers remains the same, the efficiency cost of raising the revenue needed to finance the additional health spending is $1.48 per dollar of revenue collected, and GDP declines (relative to trend) by 11 percent. A proportional payroll tax has a lower efficiency cost (41 cents per dollar of revenue averaged over all tax hikes, a 5 percent drop in GDP) but more than doubles the share of the tax burden borne by lower income taxpayers. Empirical support for the model comes from analysis of OECD country data showing that countries facing higher tax burdens in 1979 experienced slower health care spending growth in subsequent decades. The rising burden imposed by the public financing of health care expenditures may therefore serve as a brake on health care spending growth. PMID:21608156

  4. The Growth-Inequality Association:

    DEFF Research Database (Denmark)

    Bjørnskov, Christian

    2008-01-01

    This note suggests that the association between income inequality and economic growth rates might arguably depend on the political ideology of incumbent governments. Estimates indicate that under leftwing governments, inequality is negatively associated with growth while the association is positive...... under rightwing governments. This may provide a qualification to recent studies of inequality....

  5. Thermal effects on growth and respiration rates of the mayfly, Dolania americana (ephemeroptera)

    International Nuclear Information System (INIS)

    Harvey, R.S.

    1975-01-01

    The mayfly Dolania Americana, common in the sand of Upper Three Runs Creek, Savannah River Plant, was studied to determine the effects of seasonal changes in temperature on population growth rates and to determine the effects of slight elevations in water temperature on respiration rates of this benthic species. Growth of the population increased with stream temperature until peak emergence of adults in June and July. There was a strong inverse correlation between body weight and respiration rates of immature nymphs. Respiration rates at 2.5, 5, and 10 0 C above ambient creekwater temperatures were not significantly higher than those measured at ambient creekwater temperatures. (auth)

  6. Exploration of mechanisms underlying the strain-rate-dependent mechanical property of single chondrocytes

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Trung Dung; Gu, YuanTong, E-mail: yuantong.gu@qut.edu.au [School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane, Queensland (Australia)

    2014-05-05

    Based on the characterization by Atomic Force Microscopy, we report that the mechanical property of single chondrocytes has dependency on the strain-rates. By comparing the mechanical deformation responses and the Young's moduli of living and fixed chondrocytes at four different strain-rates, we explore the deformation mechanisms underlying this dependency property. We found that the strain-rate-dependent mechanical property of living cells is governed by both of the cellular cytoskeleton and the intracellular fluid when the fixed chondrocytes are mainly governed by their intracellular fluid, which is called the consolidation-dependent deformation behavior. Finally, we report that the porohyperelastic constitutive material model which can capture the consolidation-dependent behavior of both living and fixed chondrocytes is a potential candidature to study living cell biomechanics.

  7. H2-dependent attachment kinetics and shape evolution in chemical vapor deposition graphene growth

    Science.gov (United States)

    Meca, Esteban; Shenoy, Vivek B.; Lowengrub, John

    2017-09-01

    Experiments on graphene growth through chemical vapor deposition (CVD) involving methane (CH4) and hydrogen (H2) gases reveal a complex shape evolution and a non-monotonic dependence on the partial pressure of H2 ({{p}{{\\text{H}2}}} ). To explain these intriguing observations, we develop a microkinetic model for the stepwise decomposition of CH4 into mobile radicals and consider two possible mechanisms of attachment to graphene crystals: CH radicals to hydrogen-decorated edges of the crystals and C radicals to bare crystal edges. We derive an effective mass flux and an effective kinetic coefficient, both of which depend on {{p}{{\\text{H}2}}} , and incorporate these into a phase field model. The model reproduces both the non-monotonic dependence on {{p}{{\\text{H}2}}} and the characteristic shapes of graphene crystals observed in experiments. At small {{p}{{\\text{H}2}}} , growth is limited by the kinetics of attachment while at large {{p}{{\\text{H}2}}} growth is limited because the effective mass flux is small. We also derive a simple analytical model that captures the non-monotone behavior, enables the two mechanisms of attachment to be distinguished and provides guidelines for CVD growth of defect-free 2D crystals.

  8. Size-dependent mortality rate profiles.

    Science.gov (United States)

    Roa-Ureta, Ruben H

    2016-08-07

    Knowledge of mortality rates is crucial to the understanding of population dynamics in populations of free-living fish and invertebrates in marine and freshwater environments, and consequently to sustainable resource management. There is a well developed theory of population dynamics based on age distributions that allow direct estimation of mortality rates. However, for most cases the aging of individuals is difficult or age distributions are not available for other reasons. The body size distribution is a widely available alternative although the theory underlying the formation of its shape is more complicated than in the case of age distributions. A solid theory of the time evolution of a population structured by any physiological variable has been developed in 1960s and 1970s by adapting the Hamilton-Jacobi formulation of classical mechanics, and equations to estimate the body size-distributed mortality profile have been derived for simple cases. Here I extend those results with regards to the size-distributed mortality profile to complex cases of non-stationary populations, individuals growing according to a generalised growth model and seasonally patterned recruitment pulses. I apply resulting methods to two cases in the marine environment, a benthic crustacean population that was growing during the period of observation and whose individuals grow with negative acceleration, and a sea urchin coastal population that is undergoing a stable cycle of two equilibrium points in population size whose individuals grow with varying acceleration that switches sign along the size range. The extension is very general and substantially widens the applicability of the theory. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Focal adhesion kinase regulates neuronal growth, synaptic plasticity and hippocampus-dependent spatial learning and memory.

    Science.gov (United States)

    Monje, Francisco J; Kim, Eun-Jung; Pollak, Daniela D; Cabatic, Maureen; Li, Lin; Baston, Arthur; Lubec, Gert

    2012-01-01

    The focal adhesion kinase (FAK) is a non-receptor tyrosine kinase abundantly expressed in the mammalian brain and highly enriched in neuronal growth cones. Inhibitory and facilitatory activities of FAK on neuronal growth have been reported and its role in neuritic outgrowth remains controversial. Unlike other tyrosine kinases, such as the neurotrophin receptors regulating neuronal growth and plasticity, the relevance of FAK for learning and memory in vivo has not been clearly defined yet. A comprehensive study aimed at determining the role of FAK in neuronal growth, neurotransmitter release and synaptic plasticity in hippocampal neurons and in hippocampus-dependent learning and memory was therefore undertaken using the mouse model. Gain- and loss-of-function experiments indicated that FAK is a critical regulator of hippocampal cell morphology. FAK mediated neurotrophin-induced neuritic outgrowth and FAK inhibition affected both miniature excitatory postsynaptic potentials and activity-dependent hippocampal long-term potentiation prompting us to explore the possible role of FAK in spatial learning and memory in vivo. Our data indicate that FAK has a growth-promoting effect, is importantly involved in the regulation of the synaptic function and mediates in vivo hippocampus-dependent spatial learning and memory. Copyright © 2011 S. Karger AG, Basel.

  10. Investigating the asymmetric relationship between inflation-output growth exchange rate changes

    Science.gov (United States)

    Chu, Jenq Fei; Sek, Siok Kun

    2017-08-01

    The relationship between inflation-output growth or output variation has long been studied. In this study, we extend the investigation under two exchange rate flexibility/regime in four Asian countries (Indonesia, Korea, Philippines and Thailand) that have experienced drastic exchange rate regime changes aftermath the financial crisis of 1997. These countries have switched from fixed/rigid exchange rate regime to flexible exchange rate and inflation targeting (IT) regime after the crisis. Our main objective is to compare the inflation-output trade-off relationship in the pre-IT and post-IT periods as a tool to evaluate the efficiency of monetary policy. A nonlinear autoregressive distributed lags (NARDL) model is applied to capture the asymmetric effects of exchange rate changes (increases and decreases). The data ranging from 1981M1 onwards till 2016M3. Our results show that exchange rate has asymmetric effect on inflation both short-run and long-run with larger impact in the post-IT period under flexible regime. Depreciation of exchange rate has leads to higher inflation. Furthermore, we find evidences on the relationship between inflation and growth in both short-run and long-run, but the trade-off only detected in the short run both in the pre- and post-IT periods.

  11. Using wavelength-normalized optical spectroscopy to improve the accuracy of bacteria growth rate quantification

    Science.gov (United States)

    McBirney, Samantha E.; Trinh, Kristy; Wong-Beringer, Annie; Armani, Andrea M.

    2017-02-01

    One of the fundamental analytical measurements performed in microbiology is monitoring and characterizing cell concentration in culture media. Measurement error will give rise to reproducibility problems in a wide range of applications, from biomanufacturing to basic research. Therefore, it is critical that the generated results are consistent. Single wavelength optical density (OD) measurements have become the preferred approach. Here, we compare the conventional OD600 technique with a multi-wavelength normalized scattering optical spectroscopy method to measure the growth rates of Pseudomonas aeruginosa and Staphylococcus aureus, two of the leading nosocomial pathogens with proven abilities to develop resistance. The multi-wavelength normalization process minimizes the impact of bacteria byproducts and environmental noise on the signal, thereby accurately quantifying growth rates with high fidelity at low concentrations. In contrast, due to poor absorbance and scattering at 600 nm, the classic OD600 measurement method is able to detect bacteria but cannot quantify the growth rate reliably. Our wavelength-normalization protocol to detect bacteria growth rates can be readily and easily adopted by research labs, given that it only requires the use of a standard spectrophotometer and implementation of straightforward data analysis. Measuring and monitoring bacteria growth rates play a critical role in a wide range of settings, spanning from therapeutic design and development to diagnostics and disease prevention. Having a full understanding of the growth cycles of bacteria known to cause severe infections and diseases will lead to a better understanding of the pathogenesis of these illnesses, leading to better treatment and, ultimately, the development of a cure.

  12. Fibroblast growth factor-mediated proliferation of central nervous system precursors depends on endogenous production of insulin-like growth factor I

    International Nuclear Information System (INIS)

    Drago, J.; Murphy, M.; Carroll, S.M.; Harvey, R.P.; Bartlett, P.F.

    1991-01-01

    Fibroblast growth factor stimulates proliferation and subsequent differentiation of precursor cells isolated from the neuroepithelium of embryonic day 10 mice in vitro. Here we show that fibroblast growth factor-induced proliferation is dependent on the presence of insulin-like growth factors (IGFs) and that IGF-I is endogenously produced by the neuroepithelial cells. Blocking of endogenous IGF-I activity with anti-IGF-I antibodies results in complete inhibition of fibroblast growth factor-mediated proliferation and in cell death. IGF-I alone acts as a survival agent. These observations correlate with the detection of transcripts for IGF-I and basic fibroblast growth factor in freshly isolated neuroepithelium and are consistent with an autocrine action of these factors in early brain development in vivo

  13. Insect outbreak shifts the direction of selection from fast to slow growth rates in the long-lived conifer Pinus ponderosa.

    Science.gov (United States)

    de la Mata, Raul; Hood, Sharon; Sala, Anna

    2017-07-11

    Long generation times limit species' rapid evolution to changing environments. Trees provide critical global ecosystem services, but are under increasing risk of mortality because of climate change-mediated disturbances, such as insect outbreaks. The extent to which disturbance changes the dynamics and strength of selection is unknown, but has important implications on the evolutionary potential of tree populations. Using a 40-y-old Pinus ponderosa genetic experiment, we provide rare evidence of context-dependent fluctuating selection on growth rates over time in a long-lived species. Fast growth was selected at juvenile stages, whereas slow growth was selected at mature stages under strong herbivory caused by a mountain pine beetle ( Dendroctonus ponderosae ) outbreak. Such opposing forces led to no net evolutionary response over time, thus providing a mechanism for the maintenance of genetic diversity on growth rates. Greater survival to mountain pine beetle attack in slow-growing families reflected, in part, a host-based life-history trade-off. Contrary to expectations, genetic effects on tree survival were greatest at the peak of the outbreak and pointed to complex defense responses. Our results suggest that selection forces in tree populations may be more relevant than previously thought, and have implications for tree population responses to future environments and for tree breeding programs.

  14. Conifers in cold environments synchronize maximum growth rate of tree-ring formation with day length.

    Science.gov (United States)

    Rossi, Sergio; Deslauriers, Annie; Anfodillo, Tommaso; Morin, Hubert; Saracino, Antonio; Motta, Renzo; Borghetti, Marco

    2006-01-01

    Intra-annual radial growth rates and durations in trees are reported to differ greatly in relation to species, site and environmental conditions. However, very similar dynamics of cambial activity and wood formation are observed in temperate and boreal zones. Here, we compared weekly xylem cell production and variation in stem circumference in the main northern hemisphere conifer species (genera Picea, Pinus, Abies and Larix) from 1996 to 2003. Dynamics of radial growth were modeled with a Gompertz function, defining the upper asymptote (A), x-axis placement (beta) and rate of change (kappa). A strong linear relationship was found between the constants beta and kappa for both types of analysis. The slope of the linear regression, which corresponds to the time at which maximum growth rate occurred, appeared to converge towards the summer solstice. The maximum growth rate occurred around the time of maximum day length, and not during the warmest period of the year as previously suggested. The achievements of photoperiod could act as a growth constraint or a limit after which the rate of tree-ring formation tends to decrease, thus allowing plants to safely complete secondary cell wall lignification before winter.

  15. Effect of temperature on sulphate reduction, growth rate and growth yield in five psychrophilic sulphate-reducing bacteria from Arctic sediments

    DEFF Research Database (Denmark)

    Knoblauch, C.; Jørgensen, BB

    1999-01-01

    and T(opt). For strains LSv21 and LSv514, however, growth yields were highest at the lowest temperatures, around 0 degrees C. The results indicate that psychrophilic sulphate-reducing bacteria are specially adapted to permanently low temperatures by high relative growth rates and high growth yields......Five psychrophilic sulphate-reducing bacteria (strains ASv26, LSv21, PSv29, LSv54 and LSv514) isolated from Arctic sediments were examined for their adaptation to permanently low temperatures, All strains grew at -1.8 degrees C, the freezing point of sea water, but their optimum temperature...... for growth (T(opt)) were 7 degrees C (PSv29), 10 degrees C (ASv26, LSv54) and 18 degrees C (LSv21, LSv514), Although T(opt) was considerably above the in situ temperatures of their habitats (-1.7 degrees C and 2.6 degrees C), relative growth rates were still high at 0 degrees C, accounting for 25...

  16. The ramp rate dependence of the sextupole field in superconducting dipoles

    International Nuclear Information System (INIS)

    Ghosh, A.K.; Robins, K.E.; Sampson, W.B.

    1993-01-01

    Sextupole components are induced in the magnetic field of superconducting dipoles when the current is changed. The magnitude of this effect depends on the rate of change of field, the strand-to-strand resistance in the superconducting cable, and the twist pitch of the wire. Ramp rate measurements have been made on a number of SSC dipoles wound from conductors with different interstrand resistances. The technique employed uses an array of Hall probes sensitive to the sextupole field and can measure the difference for field increasing or decreasing as a function of axial position. Magnets with very low interstrand resistance exhibit a large axial oscillation in the sextupole field between up and down ramps which is rate dependent When the strand resistance is high the amplitude of this oscillation is almost independent of ramp rate

  17. Individualism in plant populations: using stochastic differential equations to model individual neighbourhood-dependent plant growth.

    Science.gov (United States)

    Lv, Qiming; Schneider, Manuel K; Pitchford, Jonathan W

    2008-08-01

    We study individual plant growth and size hierarchy formation in an experimental population of Arabidopsis thaliana, within an integrated analysis that explicitly accounts for size-dependent growth, size- and space-dependent competition, and environmental stochasticity. It is shown that a Gompertz-type stochastic differential equation (SDE) model, involving asymmetric competition kernels and a stochastic term which decreases with the logarithm of plant weight, efficiently describes individual plant growth, competition, and variability in the studied population. The model is evaluated within a Bayesian framework and compared to its deterministic counterpart, and to several simplified stochastic models, using distributional validation. We show that stochasticity is an important determinant of size hierarchy and that SDE models outperform the deterministic model if and only if structural components of competition (asymmetry; size- and space-dependence) are accounted for. Implications of these results are discussed in the context of plant ecology and in more general modelling situations.

  18. Growth activity in human septal cartilage: age-dependent incorporation of labeled sulfate in different anatomic locations

    International Nuclear Information System (INIS)

    Vetter, U.; Pirsig, W.; Heinze, E.

    1983-01-01

    Growth activity in different areas of human septal cartilage was measured by the in vitro incorporation of 35 S-labeled NaSO 4 into chondroitin sulfate. Septal cartilage without perichondrium was obtained during rhinoplasty from 36 patients aged 6 to 35 years. It could be shown that the anterior free end of the septum displays high growth activity in all age groups. The supra-premaxillary area displayed its highest growth activity during prepuberty, showing thereafter a continuous decline during puberty and adulthood. A similar age-dependent pattern in growth activity was found in the caudal prolongation of the septal cartilage. No age-dependent variations could be detected in the posterior area of the septal cartilage

  19. Temperature Effects on the Growth Rates and Photosynthetic Activities of Symbiodinium Cells

    Directory of Open Access Journals (Sweden)

    Widiastuti Karim

    2015-06-01

    Full Text Available Coral bleaching is caused by environmental stress and susceptibility to bleaching stress varies among types of coral. The physiological properties of the algal symbionts (Symbiodinium spp., especially extent of damage to PSII and its repair capacity, contribute importantly to this variability in stress susceptibility. The objective of the present study was to investigate the relationship between the growth rates and photosynthetic activities of six cultured strains of Symbiodinium spp. (clades A, B, C, D, and F at elevated temperature (33 °C. We also observed the recovery of photodamaged-PSII in the presence or absence of a chloroplast protein synthesis inhibitor (lincomycin. The growth rates and photochemical efficiencies of PSII (Fv/Fm decreased in parallel at high temperature in thermally sensitive strains, B-K100 (clade B followed by culture name and A-Y106, but not in thermally tolerant strains, F-K102 and D-K111. In strains A-KB8 and C-Y103, growth declined markedly at high temperature, but Fv/Fm decreased only slightly. These strains may reallocate energy from growth to the repair of damaged photosynthetic machineries or protection pathways. Alternatively, since recoveries of photo-damaged PSII at 33 °C were modest in strains A-KB8 and C-Y103, thermal stressing of other metabolic pathways may have reduced growth rates in these two strains. This possibility should be explored in future research efforts.

  20. Rate Dependence of the Compressive Response of Ti Foams

    Directory of Open Access Journals (Sweden)

    Nik Petrinic

    2012-06-01

    Full Text Available Titanium foams of relative density ranging from 0.3 to 0.9 were produced by titanium powder sintering procedures and tested in uniaxial compression at strain rates ranging from 0.01 to 2,000 s−1. The material microstructure was examined by X-ray tomography and Scanning Electron Microscopy (SEM observations. The foams investigated are strain rate sensitive, with both the yield stress and the strain hardening increasing with applied strain rate, and the strain rate sensitivity is more pronounced in foams of lower relative density. Finite element simulations were conducted modelling explicitly the material’s microstructure at the micron level, via a 3D Voronoi tessellation. Low and high strain rate simulations were conducted in order to predict the material’s compressive response, employing both rate-dependant and rate-independent constitutive models. Results from numerical analyses suggest that the primary source of rate sensitivity is represented by the intrinsic sensitivity of the foam’s parent material.

  1. Climatic Constraints on Growth Rate and Geochemistry (Sr/Ca and U/Ca) of the Coral Siderastrea stellata in the Southwest Equatorial Atlantic (Rocas Atoll, Brazil)

    Science.gov (United States)

    Evangelista, H.; Sifeddine, A.; Corrège, T.; Servain, J.; Dassié, E. P.; Logato, R.; Cordeiro, R. C.; Shen, C.-C.; Le Cornec, F.; Nogueira, J.; Segal, B.; Castagna, A.; Turcq, B.

    2018-03-01

    Although relatively rare compared to similar latitudes in the Pacific or Indian Oceans, massive coral colonies are present in the Tropical/Equatorial Southwestern Atlantic Ocean. However, detailed geochemical compositions of these corals are still largely unknown. In this work, we present growth rates, Sr/Ca, and U/Ca ratios of the coral colony (Siderastrea stellata) sampled at Rocas Atoll, off the Brazilian coast. These variables are primarily affected by sea surface temperature (SST) at seasonal scale, and by wind stress at interannual scale, these results represent a broad new finding. A lower significance at the interannual time scale between Sr/Ca and U/Ca with respect to SST is attributed to the low SST amplitude closed to Equator. An investigation on the dependence of coral growth rates with respect to the "cloud shading effect" promoted by the Intertropical Convergence Zone (ITCZ) does not show significant influence. Additionally, rain seems to act on local geochemistry of Sr/Ca ratios and growth rate at the decadal scale.

  2. Constant savings rates and quasi-arithmetic population growth under exhaustible resource constraints

    NARCIS (Netherlands)

    Asheim, G.B.; Buchholz, W.; Hartwick, J.M.; Mitra, T.; Withagen, C.A.A.M.

    2007-01-01

    In the Dasgupta–Heal–Solow–Stiglitz (DHSS) model of capital accumulation and resource depletion we show the following equivalence: if an efficient path has constant (gross and net of population growth) savings rates, then population growth must be quasi-arithmetic and the path is a maximin or a

  3. Dampening effects of long-term experimental drought on growth and mortality rates of a Holm oak forest.

    Science.gov (United States)

    Barbeta, Adrià; Ogaya, Romà; Peñuelas, Josep

    2013-10-01

    Forests respond to increasing intensities and frequencies of drought by reducing growth and with higher tree mortality rates. Little is known, however, about the long-term consequences of generally drier conditions and more frequent extreme droughts. A Holm oak forest was exposed to experimental rainfall manipulation for 13 years to study the effect of increasing drought on growth and mortality of the dominant species Quercus ilex, Phillyrea latifolia, and Arbutus unedo. The drought treatment reduced stem growth of A. unedo (-66.5%) and Q. ilex (-17.5%), whereas P. latifolia remained unaffected. Higher stem mortality rates were noticeable in Q. ilex (+42.3%), but not in the other two species. Stem growth was a function of the drought index of early spring in the three species. Stem mortality rates depended on the drought index of winter and spring for Q. ilex and in spring and summer for P. latifolia, but showed no relation to climate in A. unedo. Following a long and intense drought (2005-2006), stem growth of Q. ilex and P. latifolia increased, whereas it decreased in A. unedo. Q. ilex also enhanced its survival after this period. Furthermore, the effect of drought treatment on stem growth in Q. ilex and A. unedo was attenuated as the study progressed. These results highlight the different vulnerabilities of Mediterranean species to more frequent and intense droughts, which may lead to partial species substitution and changes in forest structure and thus in carbon uptake. The response to drought, however, changed over time. Decreased intra- and interspecific competition after extreme events with high mortality, together with probable morphological and physiological acclimation to drought during the study period, may, at least in the short term, buffer forests against drier conditions. The long-term effects of drought consequently deserve more attention, because the ecosystemic responses are unlikely to be stable over time.Nontechnical summaryIn this study, we

  4. "Heart rate-dependent" electrocardiographic diagnosis of left ventricular hypertrophy.

    Science.gov (United States)

    Madias, John E

    2013-05-01

    A case is presented revealing the common phenomenon of heart rate-dependent diagnosis of electrocardiographic (ECG) diagnosis of left ventricular hypertrophy (LVH), which consists of satisfaction of LVH criteria only at faster rates whereas ECGs with a slow heart rate do not satisfy such criteria. The mechanism of the phenomenon has been attributed to the tachycardia-mediated underfilling of the left ventricle bringing the electrical "centroid" of the heart closer to the recording electrodes, which results in augmentation of the amplitude of QRS complexes, particularly in leads V2-V4. ©2012, The Author. Journal compilation ©2012 Wiley Periodicals, Inc.

  5. Re-alimentation in harbor seal pups: effects on the somatotropic axis and growth rate.

    Science.gov (United States)

    Richmond, Julie P; Norris, Tenaya; Zinn, Steven A

    2010-01-15

    The metabolic hormones, growth hormone (GH) and insulin-like growth factor (IGF)-I, together with IGF binding proteins (IGFBP), have been well studied in domestic species and are the primary components of the somatotropic axis. This hormone axis is responsive to nutrient intake, associated with growth rate, and accretion of protein and adipose. However, this relationship has not been evaluated in species that rely heavily on adipose stores for survival, such as pinnipeds. The primary objectives of this research were to investigate the response of the somatotropic axis to reduced nutrient intake and re-alimentation in rehabilitated harbor seal pups, and to assess if these hormones are related to nutritional status and growth rate in harbor seals. Stranded harbor seal pups (n=24) arrived at the rehabilitation facility very thin after fasting for several days (nutritional nadir). Throughout rehabilitation nutrient intake increased and pups gained mass and body condition. Concentrations of GH and IGFBP-2 decreased with re-alimentation, while IGF-I and IGFBP-3 concentrations increased. Overall, GH and IGFBP-2 were negatively associated and IGF-I and IGFBP-3 were positively associated with growth rate and increased body condition of harbor sea pups. Further, the magnitude of the growth response was related to the magnitude in response of the somatotropic axis to varied levels of intake. These data suggest that multiple components of the somatotropic axis may be used to assess the energy status of individuals and may also provide information on the level of feed intake that is predictive of growth rate.

  6. Plant allometry, leaf nitrogen and phosphorus stoichiometry, and interspecific trends in annual growth rates.

    Science.gov (United States)

    Niklas, Karl J

    2006-02-01

    Life forms as diverse as unicellular algae, zooplankton, vascular plants, and mammals appear to obey quarter-power scaling rules. Among the most famous of these rules is Kleiber's (i.e. basal metabolic rates scale as the three-quarters power of body mass), which has a botanical analogue (i.e. annual plant growth rates scale as the three-quarters power of total body mass). Numerous theories have tried to explain why these rules exist, but each has been heavily criticized either on conceptual or empirical grounds. N,P-STOICHIOMETRY: Recent models predicting growth rates on the basis of how total cell, tissue, or organism nitrogen and phosphorus are allocated, respectively, to protein and rRNA contents may provide the answer, particularly in light of the observation that annual plant growth rates scale linearly with respect to standing leaf mass and that total leaf mass scales isometrically with respect to nitrogen but as the three-quarters power of leaf phosphorus. For example, when these relationships are juxtaposed with other allometric trends, a simple N,P-stoichiometric model successfully predicts the relative growth rates of 131 diverse C3 and C4 species. The melding of allometric and N,P-stoichiometric theoretical insights provides a robust modelling approach that conceptually links the subcellular 'machinery' of protein/ribosomal metabolism to observed growth rates of uni- and multicellular organisms. Because the operation of this 'machinery' is basic to the biology of all life forms, its allometry may provide a mechanistic explanation for the apparent ubiquity of quarter-power scaling rules.

  7. The daily weight gain, growth rate and length-weight relationships of ...

    African Journals Online (AJOL)

    The daily weight gain, growth rate and length-weight relationships of Clarias gariepinus, Heterobranchus longifilis and their reciprocal hybrids (Pisces: Clariidae) reared under ambient environmental conditions.

  8. Modeling and Control for Giant Magnetostrictive Actuators with Rate-Dependent Hysteresis

    Directory of Open Access Journals (Sweden)

    Ping Liu

    2013-01-01

    Full Text Available The rate-dependent hysteresis in giant magnetostrictive materials is a major impediment to the application of such material in actuators. In this paper, a relevance vector machine (RVM model is proposed for describing the hysteresis nonlinearity under varying input current. It is possible to construct a unique dynamic model in a given rate range for a rate-dependent hysteresis system using the sinusoidal scanning signals as the training set input signal. Subsequently, a proportional integral derivative (PID control scheme combined with a feedforward compensation is implemented on a giant magnetostrictive actuator (GMA for real-time precise trajectory tracking. Simulations and experiments both verify the effectiveness and the practicality of the proposed modeling and control methods.

  9. Deprivation index and dependency ratio are key determinants of emergency medical admission rates.

    Science.gov (United States)

    Conway, Richard; Byrne, Declan; O'Riordan, Deirdre; Cournane, Seán; Coveney, Seamus; Silke, Bernard

    2015-11-01

    Patients from deprived backgrounds have a higher in-patient mortality following an emergency medical admission; there has been debate as to the extent to which deprivation and population structure influences hospital admission rate. All emergency medical admissions to an Irish hospital over a 12-year period (2002-2013) categorized by quintile of Deprivation Index and Dependency Ratio (proportion of population Dependency Ratio was an independent predictor of the admission rate with adjusted predicted rates of Q1 20.8 (95%CI 20.5 to 21.1), Q2 19.2 (95%CI 19.0 to 19.4), Q3 27.6 (95%CI 27.3 to 27.9), Q4 43.9 (95%CI 43.5 to 44.4) and Q5 34.4 (95%CI 34.1 to 34.7). A high concurrent Deprivation Index and Dependency Ratio were associated with very high admission rates. Deprivation Index and population Dependency Ratio are key determinants of the rate of emergency medical admissions. Copyright © 2015 European Federation of Internal Medicine. Published by Elsevier B.V. All rights reserved.

  10. Atomistic Origin of Rate-Dependent Serrated Plastic Flow in Metallic Glasses

    Directory of Open Access Journals (Sweden)

    Yao YG

    2008-01-01

    Full Text Available Abstract Nanoindentation simulations on a binary metallic glass were performed under various strain rates by using molecular dynamics. The rate-dependent serrated plastic flow was clearly observed, and the spatiotemporal behavior of its underlying irreversible atomic rearrangement was probed. Our findings clearly validate that the serration is a temporally inhomogeneous characteristic of such rearrangements and not directly dependent on the resultant shear-banding spatiality. The unique spatiotemporal distribution of shear banding during nanoindentation is highlighted in terms of the potential energy landscape (PEL theory.

  11. Biomolecular Origin of The Rate-Dependent Deformation of Prismatic Enamel

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, J; Hsiung, L

    2006-07-05

    Penetration deformation of columnar prismatic enamel was investigated using instrumented nanoindentation testing, carried out at three constant strain rates (0.05 s{sup -1}, 0.005 s{sup -1}, and 0.0005 s{sup -1}). Enamel demonstrated better resistance to penetration deformation and greater elastic modulus values were measured at higher strain rates. The origin of the rate-dependent deformation was rationalized to be the shear deformation of nanoscale protein matrix surrounding each hydroxyapatite crystal rods. And the shear modulus of protein matrix was shown to depend on strain rate in a format: G{sub p} = 0.213 + 0.021 ln {dot {var_epsilon}}. Most biological composites compromise reinforcement mineral components and an organic matrix. They are generally partitioned into multi-level to form hierarchical structures that have supreme resistance to crack growth [1]. The molecular mechanistic origin of toughness is associated with the 'sacrificial chains' between the individual sub-domains in a protein molecule [2]. As the protein molecule is stretched, these 'sacrificial chains' break to protect its backbone and dissipate energy [3]. Such fresh insights are providing new momentum toward updating our understanding of biological materials [4]. Prismatic enamel in teeth is one such material. Prismatic microstructure is frequently observed in the surface layers of many biological materials, as exemplified in mollusk shells [5] and teeth [6]. It is a naturally optimized microstructure to bear impact loading and penetration deformation. In teeth, the columnar prismatic enamel provides mechanical and chemical protection for the relatively soft dentin layer. Its mechanical behavior and reliability are extremely important to ensure normal tooth function and human health. Since enamel generally contains up to 95% hydroxyapatite (HAP) crystals and less than 5% protein matrix, it is commonly believed to be a weak and brittle material with little resistance to

  12. Contrasting growth properties of Nocardioides JS614 on threedifferent vinyl halides.

    Science.gov (United States)

    Taylor, Anne E; Bottomley, Peter J; Semprini, Lewis

    2018-02-01

    Ethene (ETH)-grown inocula of Nocardioides JS614 grow on vinyl chloride (VC), vinyl fluoride (VF), or vinyl bromide (VB) as the sole carbon and energy source, with faster growth rates and higher cell yields on VC and VF than on VB. However, whereas acetate-grown inocula of JS614 grow on VC and VF after a lag period, growth on VB did not occur unless supplemental ethene oxide (EtO) was present in the medium. Despite inferior growth on VB, the maximum rate of VB consumption by ETH-grown cells was ~ 50% greater than the rates of VC and VF consumption, but Br - release during VB consumption was non-stoichiometric with VB consumption (~ 66%) compared to 100% release of Cl - and F - during VC and VF consumption. Evidence was obtained for VB turnover-dependent toxicity of cell metabolism in JS614 with both acetate-dependent respiration and growth being significantly reduced by VB turnover, but no VC or VF turnover-dependent toxicity of growth was detected. Reduced growth rate and cell yield of JS614 on VB probably resulted from a combination of inefficient metabolic processing of the highly unstable VB epoxide (t 0.5  = 45 s), accompanied by growth inhibitory effects of VB metabolites on acetate-dependent metabolism. The exact role(s) of EtO in promoting growth of alkene repressed JS614 on VB remains unresolved, with evidence of EtO inducing epoxide consuming activity prior to an increase in alkene oxidizing activity and supplementing reductant supply when VB is the growth substrate.

  13. On the relationship between tumour growth rate and survival in non-small cell lung cancer

    Directory of Open Access Journals (Sweden)

    Hitesh B. Mistry

    2017-11-01

    Full Text Available A recurrent question within oncology drug development is predicting phase III outcome for a new treatment using early clinical data. One approach to tackle this problem has been to derive metrics from mathematical models that describe tumour size dynamics termed re-growth rate and time to tumour re-growth. They have shown to be strong predictors of overall survival in numerous studies but there is debate about how these metrics are derived and if they are more predictive than empirical end-points. This work explores the issues raised in using model-derived metric as predictors for survival analyses. Re-growth rate and time to tumour re-growth were calculated for three large clinical studies by forward and reverse alignment. The latter involves re-aligning patients to their time of progression. Hence, it accounts for the time taken to estimate re-growth rate and time to tumour re-growth but also assesses if these predictors correlate to survival from the time of progression. I found that neither re-growth rate nor time to tumour re-growth correlated to survival using reverse alignment. This suggests that the dynamics of tumours up until disease progression has no relationship to survival post progression. For prediction of a phase III trial I found the metrics performed no better than empirical end-points. These results highlight that care must be taken when relating dynamics of tumour imaging to survival and that bench-marking new approaches to existing ones is essential.

  14. Deposition and growth of domains in one dimension

    Science.gov (United States)

    Rodgers, G. J.; Tavassoli, Z.

    1998-09-01

    A model of deposition and growth in one dimension is studied in which finite sized domains are deposited by the random sequential adsorption process. The domains then grow with a time dependent growth rate. When the initial deposited domains are monomers and dimers the coverage is found exactly for a number of different growth rates. A continuum version of this model is also considered.

  15. The trade-off of availability and growth inhibition through copper for the production of copper-dependent enzymes by Pichia pastoris.

    Science.gov (United States)

    Balakumaran, Palanisamy Athiyaman; Förster, Jan; Zimmermann, Martin; Charumathi, Jayachandran; Schmitz, Andreas; Czarnotta, Eik; Lehnen, Mathias; Sudarsan, Suresh; Ebert, Birgitta E; Blank, Lars Mathias; Meenakshisundaram, Sankaranarayanan

    2016-02-20

    Copper is an essential chemical element for life as it is a part of prosthetic groups of enzymes including super oxide dismutase and cytochrome c oxidase; however, it is also toxic at high concentrations. Here, we present the trade-off of copper availability and growth inhibition of a common host used for copper-dependent protein production, Pichia pastoris. At copper concentrations ranging from 0.1 mM (6.35 mg/L) to 2 mM (127 mg/L), growth rates of 0.25 h(-1) to 0.16 h(-1) were observed with copper uptake of as high as 20 mgcopper/gCDW. The intracellular copper content was estimated by subtracting the copper adsorbed on the cell wall from the total copper concentration in the biomass. Higher copper concentrations led to stronger cell growth retardation and, at 10 mM (635 mg/L) and above, to growth inhibition. To test the determined copper concentration range for optimal recombinant protein production, a laccase gene from Aspergillus clavatus [EMBL: EAW07265.1] was cloned under the control of the constitutive glyceraldehyde-3-phosphate (GAP) dehydrogenase promoter for expression in P. pastoris. Notably, in the presence of copper, laccase expression improved the specific growth rate of P. pastoris. Although copper concentrations of 0.1 mM and 0.2 mM augmented laccase expression 4 times up to 3 U/mL compared to the control (0.75 U/mL), while higher copper concentrations resulted in reduced laccase production. An intracellular copper content between 1 and 2 mgcopper/gCDW was sufficient for increased laccase activity. The physiology of the yeast could be excluded as a reason for the stop of laccase production at moderate copper concentrations as no flux redistribution could be observed by (13)C-metabolic flux analysis. Copper and its pivotal role to sustain cellular functions is noteworthy. However, knowledge on its cellular accumulation, availability and distribution for recombinant protein production is limited. This study attempts to address one such challenge

  16. Time-series analysis of foreign exchange rates using time-dependent pattern entropy

    Science.gov (United States)

    Ishizaki, Ryuji; Inoue, Masayoshi

    2013-08-01

    Time-dependent pattern entropy is a method that reduces variations to binary symbolic dynamics and considers the pattern of symbols in a sliding temporal window. We use this method to analyze the instability of daily variations in foreign exchange rates, in particular, the dollar-yen rate. The time-dependent pattern entropy of the dollar-yen rate was found to be high in the following periods: before and after the turning points of the yen from strong to weak or from weak to strong, and the period after the Lehman shock.

  17. Interacting growth and loss rates: The balance of top-down and bottom-up controls in plankton communities

    International Nuclear Information System (INIS)

    Lehman, J.T.

    1991-01-01

    Application of resource-based competition theory to high-nutrient, low-chlorophyll regions of the ocean suggests that single-factor controls on vertical export rates of carbon from euphotic zones are unlikely. High specific rates of grazing or sinking losses interact with growth physiology to produce nutrient requirements in situ that are much higher than those required for the growth of populations held in bottle bioassays. The efficiency of vertical export of carbon by sinking particulates can vary with species composition of the plankton, which in turn can be altered by nutrient manipulation. A simulation model explores possible changes to species composition and vertical carbon flux which might result from addition of Fe to Southern Ocean plankton communities. Nutrient manipulation permits invasion of plankton communities by taxa not originally present and does not necessarily increase the biomass or metabolism of resident species. This makes a priori prediction of fluxes associated with an enriched and altered community fundamentally uncertain if predictions are based on stoichiometries and physiologies of the original resident taxa. Vertical carbon flux could either increase or decrease in response to single-element addition, depending on the attributes of the invading species

  18. Effects of void anisotropy on the ignition and growth rates of energetic materials

    Science.gov (United States)

    Rai, Nirmal Kumar; Sen, Oishik; Udaykumar, H. S.

    2017-06-01

    Initiation of heterogeneous energetic materials is thought to occur at hot spots; reaction fronts propagate from sites of such hot spots into the surrounding material resulting in complete consumption of the material. Heterogeneous materials, such as plastic bonded explosives (PBXs) and pressed materials contain numerous voids, defects and interfaces at which hot spots can occur. Amongst the various mechanisms of hot spot formation, void collapse is considered to be the predominant one in the high strain rate loading conditions. It is established in the past the shape of the voids has a significant effect on the initiation behavior of energetic materials. In particular, void aspect ratio and orientations play an important role in this regard. This work aims to quantify the effects of void aspect ratio and orientation on the ignition and growth rates of chemical reaction from the hot spot. A wide range of aspect ratio and orientations is considered to establish a correlation between the ignition and growth rates and the void morphology. The ignition and growth rates are obtained from high fidelity reactive meso-scale simulations. The energetic material considered in this work is HMX and Tarver McGuire HMX decomposition model is considered to capture the reaction mechanism of HMX. The meso-scale simulations are performed using a Cartesian grid based Eulerian solver SCIMITAR3D. The void morphology is shown to have a significant effect on the ignition and growth rates of HMX.

  19. Constant Growth Rate Can Be Supported by Decreasing Energy Flux and Increasing Aerobic Glycolysis

    Directory of Open Access Journals (Sweden)

    Nikolai Slavov

    2014-05-01

    Full Text Available Fermenting glucose in the presence of enough oxygen to support respiration, known as aerobic glycolysis, is believed to maximize growth rate. We observed increasing aerobic glycolysis during exponential growth, suggesting additional physiological roles for aerobic glycolysis. We investigated such roles in yeast batch cultures by quantifying O2 consumption, CO2 production, amino acids, mRNAs, proteins, posttranslational modifications, and stress sensitivity in the course of nine doublings at constant rate. During this course, the cells support a constant biomass-production rate with decreasing rates of respiration and ATP production but also decrease their stress resistance. As the respiration rate decreases, so do the levels of enzymes catalyzing rate-determining reactions of the tricarboxylic-acid cycle (providing NADH for respiration and of mitochondrial folate-mediated NADPH production (required for oxidative defense. The findings demonstrate that exponential growth can represent not a single metabolic/physiological state but a continuum of changing states and that aerobic glycolysis can reduce the energy demands associated with respiratory metabolism and stress survival.

  20. IN VITRO GROWTH RATE OF Kappaphycus alvarezii MICROPROPAGULE AND EMBRYO BY ENRICHMENT MEDIUM WITH SEAWEED EXTRACT

    Directory of Open Access Journals (Sweden)

    Emma Suryati

    2015-06-01

    Full Text Available The development of micropropagule and embryo of seaweed depend on nutrient and fertilizer used. Seaweed has been reported contain hormone regulators such as auxine, cytokinine, gibbereline, and various minerals applied in stimulating the growth ocra plant and wheat culture. The objectives of this study were to determine the potential of Kappaphycus alvarezii extract and its optimal concentration in accelerating of Kappaphycus alvarezii micropropagule and embryo growth. Micropropagule and embryo produced through callus induction were planted into PES 1/20 liquid medium supplemented with seaweed extract at the concentrations of 0 (control, 25, 50, 75, and 100 μL in 10 mL of medium. The results showed that medium enrichment with 50 μL of seaweed extract had the highest survival rate and growth of thallus. In addition, this concentration was also resulted in a good performance of K. alvarezii thallus with the lighter color. The advantage of this study for seaweed cultivation in Indonesia, among others, seaweed can be used as fertilizer, especially in the maintenance of seaweed seed, so that cultivation can be better develop.

  1. A model for rate-dependent but time-independent material behavior in cyclic plasticity

    International Nuclear Information System (INIS)

    Dafalias, Y.F.; Ramey, M.R.; Sheikh, I.

    1977-01-01

    This paper presents a model for rate-dependent but time independent material behavior under cyclic loading in the plastic range. What is referred to as time independent behavior here, is the absence of creep and relaxation phenomena from the behavior of the model. The notion of plastic internal variables (piv) is introduced, as properly invariant scalars or second order tensors, whose constitutive relations are rate-type equations not necessarily homogeneous of order one in the rates, as it would be required for independent plasticity. The concept of a yield surface in the strain space and a loading function in terms of the total strain rate is introduced, where the sign of the loading function defines zero or non-zero value of the rate of piv. Thus rate dependence is achieved without time dependent behaviour (no creep or relaxation). In addition, discrete memory parameters associated with the most recent event of unloading-reloading in different directions enter the constitutive relations for the piv. (Auth.)

  2. Higher Growth Rate of Branch Duct Intraductal Papillary Mucinous Neoplasms Associates With Worrisome Features.

    Science.gov (United States)

    Kolb, Jennifer M; Argiriadi, Pamela; Lee, Karen; Liu, Xiaoyu; Bagiella, Emilia; Lucas, Aimee L; Kim, Michelle Kang; Kumta, Nikhil A; Nagula, Satish; Sarpel, Umut; DiMaio, Christopher J

    2018-03-11

    For patients with branch duct intraductal papillary mucinous neoplasms (BD-IPMNs, cysts), it is a challenge to identify those at high risk for malignant lesions. We sought to identify factors associated with development of pancreatic cancer, focusing on neoplasm growth rate. We performed a retrospective study of 189 patients with BD-IPMNs who underwent at least 2 contrast-enhanced cross-sectional imaging studies, 1 year or more apart, at a tertiary referral center from January 2003 through 2013. Patients with cysts that had Fukuoka worrisome or high-risk features were excluded. Two radiologists reviewed all images. Cyst size was recorded at the initial and final imaging studies and growth rate was calculated. We collected patient demographic data, cyst characteristics, and clinical outcomes; univariate logistic regression models were used to determine the odds of developing worrisome features. The primary outcomes were to determine growth rate of low-risk BD-IPMNs and to assess whether cyst growth rate correlates high-risk features of IPMNs. Based on image analyses, cysts were initially a median 11 mm (range, 3-31 mm) and their final size was 12.5 mm (range, 3-42 mm). After a median follow-up time of 56 months (range, 12-163 months), the median cyst growth rate was 0.29 mm/year. Twelve patients developed worrisome features, no patients developed high-risk features, 4 patients had surgical resection, and no cancers developed. The rate of BD-IPMN growth was greater in patients who developed worrisome features than those who did not (2.84 mm/year vs 0.23 mm/year; P < .001). The odds of developing worrisome features increased for each unit (mm) increase in cyst size (odds ratio, 1.149; 95% CI, 1.035-1.276, P = .009). In a retrospective analysis of images from patients with BD-IPMN, we found low-risk BD-IPMNs to grow at an extremely low rate (less than 0.3 mm/year). BD-IPMNs in only about 6% of patients developed worrisome features, and none developed high-risk features

  3. Oxygen dependency of epidermal growth factor receptor binding and DNA synthesis of rat hepatocytes

    International Nuclear Information System (INIS)

    Hirose, Tetsuro; Terajima, Hiroaki; Yamauchi, Akira

    1997-01-01

    Background/Aims: Changes in oxygen availability modulate replicative responses in several cell types, but the effects on hepatocyte replication remain unclear. We have studied the effects of transient nonlethal hypoxia on epidermal growth factor receptor binding and epidermal growth factor-induced DNA synthesis of rat hepatocytes. Methods: Lactate dehydrogenase activity in culture supernatant, intracellular adenosine triphosphate content, 125 I-epidermal growth factor specific binding, epidermal growth factor receptor protein expression, and 3 H-thymidine incorporation were compared between hepatocytes cultured in hypoxia and normoxia. Results: Hypoxia up to 3 h caused no significant increase in lactate dehydrogenase activity in the culture supernatant, while intracellular adenosine triphosphate content decreased time-dependently and was restored to normoxic levels by reoxygenation (nonlethal hypoxia). Concomitantly, 125 I-epidermal growth factor specific binding to hepatocytes decreased time-dependently (to 54.1% of normoxia) and was restored to control levels by reoxygenation, although 125 I-insulin specific binding was not affected. The decrease in 125 I-epidermal growth factor specific binding was explained by the decrease in the number or available epidermal growth factor receptors (21.37±3.08 to 12.16±1.42 fmol/10 5 cells), while the dissociation constant of the receptor was not affected. The change in the number of available receptors was not considered to be due to receptor degradation-resynthesis, since immuno-detection of the epidermal growth factor receptor revealed that the receptor protein expression did not change during hypoxia and reoxygenation, and since neither actinomycin D nor cycloheximide affected the recovery of 125 I-epidermal growth factor binding by reoxygenation. Inhibition of epidermal growth factor-induced DNA synthesis after hypoxia (to 75.4% of normoxia by 3 h hypoxia) paralleled the decrease in 125 I-epidermal growth factor binding

  4. Maximum Likelihood based comparison of the specific growth rates for P. aeruginosa and four mutator strains

    DEFF Research Database (Denmark)

    Philipsen, Kirsten Riber; Christiansen, Lasse Engbo; Mandsberg, Lotte Frigaard

    2008-01-01

    with an exponentially decaying function of the time between observations is suggested. A model with a full covariance structure containing OD-dependent variance and an autocorrelation structure is compared to a model with variance only and with no variance or correlation implemented. It is shown that the model...... are used for parameter estimation. The data is log-transformed such that a linear model can be applied. The transformation changes the variance structure, and hence an OD-dependent variance is implemented in the model. The autocorrelation in the data is demonstrated, and a correlation model...... that best describes data is a model taking into account the full covariance structure. An inference study is made in order to determine whether the growth rate of the five bacteria strains is the same. After applying a likelihood-ratio test to models with a full covariance structure, it is concluded...

  5. A grain-boundary diffusion model of dynamic grain growth during superplastic deformation

    International Nuclear Information System (INIS)

    Kim, Byung-Nam; Hiraga, Keijiro; Sakka, Yoshio; Ahn, Byung-Wook

    1999-01-01

    Dynamic grain growth during superplastic deformation is modelled on the basis of a grain-boundary diffusion mechanism. On the grain boundary where a static and a dynamic potential difference coexist, matter transport along the boundary is assumed to contribute to dynamic grain growth through depositing the matter on the grain surface located opposite to the direction of grain-boundary migration. The amount of the diffusive matter during deformation is calculated for an aggregate of spherical grains and is converted to the increment of mean boundary migration velocity. The obtained relationship between the strain rate and the dynamic grain growth rate is shown to be independent of deformation mechanisms, provided that the grain growth is controlled by grain-boundary diffusion. The strain dependence, strain-rate dependence and temperature dependence of grain growth predicted from this model are consistent with those observed in superplastic ZrO 2 -dispersed Al 2 O 3

  6. Growth rates in modern speleothems from Santana Cave, Brazil, by the 210Pb-method

    International Nuclear Information System (INIS)

    Bonotto, D.M.; Karmann, I.; Baskaran, M.M.

    2012-01-01

    The Santana Cave is located at the Upper Ribeira Touristic State Park (PETAR-Parque Estadual Turístico do Alto Ribeira) in southern São Paulo State, Brazil. This paper describes 210 Pb activity concentration data in soda straw stalactites samples collected at Salão das Flores in Santana Cave that is a fossil tributary of the cave river. Non-expensive alpha counting following some analytical steps for extracting and depositing 210 Po were used for providing the 210 Pb data. In the analyzed samples, 210 Pb values of increasingly older samples fitted an exponential curve, thus suggesting that the production of 210 Pb has been constant with time. Also, the near-ideal fit indicated that the growth was uniform and there was no break in the continuous growth. The soda straw growth rates were determined from the best fit to the exponential curve through the 210 Pb activity concentration. The results of the measurements allowed estimate a longitudinal rate corresponding to 1.3 mm/yr and a lateral rate of 0.01 mm/yr, which permitted calculate times of 70 years and 317–498 years for their formation, respectively. The lateral growth rate is compatible with values from studies of chemical weathering rates held under laboratory and natural conditions.

  7. An inverse modeling procedure to determine particle growth and nucleation rates from measured aerosol size distributions

    Directory of Open Access Journals (Sweden)

    B. Verheggen

    2006-01-01

    Full Text Available Classical nucleation theory is unable to explain the ubiquity of nucleation events observed in the atmosphere. This shows a need for an empirical determination of the nucleation rate. Here we present a novel inverse modeling procedure to determine particle nucleation and growth rates based on consecutive measurements of the aerosol size distribution. The particle growth rate is determined by regression analysis of the measured change in the aerosol size distribution over time, taking into account the effects of processes such as coagulation, deposition and/or dilution. This allows the growth rate to be determined with a higher time-resolution than can be deduced from inspecting contour plots ('banana-plots''. Knowing the growth rate as a function of time enables the evaluation of the time of nucleation of measured particles of a certain size. The nucleation rate is then obtained by integrating the particle losses from time of measurement to time of nucleation. The regression analysis can also be used to determine or verify the optimum value of other parameters of interest, such as the wall loss or coagulation rate constants. As an example, the method is applied to smog chamber measurements. This program offers a powerful interpretive tool to study empirical aerosol population dynamics in general, and nucleation and growth in particular.

  8. Effect of Compressive Mode I on the Mixed Mode I/II Fatigue Crack Growth Rate of 42CrMo4

    Science.gov (United States)

    Heirani, Hasan; Farhangdoost, Khalil

    2018-01-01

    Subsurface cracks in mechanical contact loading components are subjected to mixed mode I/II, so it is necessary to evaluate the fatigue behavior of materials under mixed mode loading. For this purpose, fatigue crack propagation tests are performed with compact tension shear specimens for several stress intensity factor (SIF) ratios of mode I and mode II. The effect of compressive mode I loading on mixed mode I/II crack growth rate and fracture surface is investigated. Tests are carried out for the pure mode I, pure mode II, and two different mixed mode loading angles. On the basis of the experimental results, mixed mode crack growth rate parameters are proposed according to Tanaka and Richard with Paris' law. Results show neither Richard's nor Tanaka's equivalent SIFs are very useful because these SIFs depend strongly on the loading angle, but Richard's equivalent SIF formula is more suitable than Tanaka's formula. The compressive mode I causes the crack closure, and the friction force between the crack surfaces resists against the crack growth. In compressive loading with 45° angle, d a/d N increases as K eq decreases.

  9. Effect of repeated oral therapeutic doses of methylphenidate on food intake and growth rate in rats.

    Science.gov (United States)

    Alam, Nausheen; Najam, Rahila

    2015-01-01

    Central nervous system stimulants are known to produce anorexia. Previous data suggest that methylphenidate can have variable effects on caloric intake and growth rate. A dose-response study was performed to monitor caloric intake, liquid intake and growth rate in rats following repeated administration of human oral therapeutic doses 2 mg/kg/day, 5mg/kg/day and 8mg/kg/day of methylphenidate. We found that food intake and water intake, increased in all weeks and at all doses used in the study. Growth rate increased more at higher dose (8mg/kg/day) and at low dose (2mg/kg/day) of methylphenidate in 1(st) and 2(nd) week whereas more decreased by the above doses in 3(rd) week, suggesting that food stimulation leads to initial increase in growth rate but long term administration of methylphenidate attenuate growth rate that is not due to modulation of appetite but may be due to anxiety and increased activity produce by stimulants. A possible role of DA, 5HT receptors in modulation of appetite and anxiety is discussed.

  10. Growth rate variation of the stalked barnacle Pollicipes pollicipes (Crustacea: Cirripedia using calcein as a chemical marker

    Directory of Open Access Journals (Sweden)

    David Jacinto

    2015-03-01

    Full Text Available This study describes the use of calcein as a chemical tagging methodology to estimate growth rate variation of the stalked barnacle Pollicipes pollicipes, an ecologically important intertidal species and economic resource, in SW Portugal. Calcein tagging had a high success rate (94% in marking both juvenile and adult barnacles for a period of 2.5 months, providing a valuable method for obtaining reliable data in growth studies of P. pollicipes. Growth rate decreased with barnacle size and was highly variable amongst individuals, particularly in smaller barnacles. No effect of shore level on barnacle growth was detected. Growth rates were higher in smaller juvenile barnacles, peaking at a 1.1-mm monthly increment in rostro-carinal length (RC for individuals with RC=5 mm, and decreased with barnacle size (monthly growth rates of 0.5 mm for adult barnacles with RC~12.5 mm. Growth rates observed in adults with commercial interest (RC ≥ 18 mm was < 0.25 mm per month. The advantages of tagging P. pollicipes with calcein were the possibility of mass marking individual barnacles of different size cohorts within a short period (less than 1 day of manipulation; and reduced time of fieldwork, which is very important because this species inhabits very exposed rocky shores.

  11. Determining the nucleation rate from the dimer growth probability

    NARCIS (Netherlands)

    Ter Horst, J.H.; Kashchiev, D.

    2005-01-01

    A new method is proposed for the determination of the stationary one-component nucleation rate J with the help of data for the growth probability P2 of a dimer which is the smallest cluster of the nucleating phase. The method is based on an exact formula relating J and P2, and is readily applicable

  12. Power-law temperature dependence of the inelastic-scattering rate in disordered superconductors

    International Nuclear Information System (INIS)

    Devereaux, T.P.; Belitz, D.

    1991-01-01

    We present a theory of the quasiparticle inelastic lifetime τ in in disordered superconducting films. We find that both the Coulomb and the electron-phonon contribution to τ in -1 are enhanced by disorder, and that for reasonably strong electron-phonon coupling the latter is dominant. In contrast to clean superconductors, the scattering rate is larger than the recombination rate at all temperatures. This leads to a power-law temperature dependence of τ in -1 , in agreement with experimental observations. The theory quantitatively accounts for the magnitude, disorder dependence, and temperature dependence of τ in measured in recent experiments

  13. Morphology and mycelial growth rate of Pleurotus spp. strains from the Mexican mixtec region

    Science.gov (United States)

    Guadarrama-Mendoza, P.C.; del Toro, G. Valencia; Ramírez-Carrillo, R.; Robles-Martínez, F.; Yáñez-Fernández, J.; Garín-Aguilar, M.E.; Hernández, C.G.; Bravo-Villa, G.

    2014-01-01

    Two native Pleurotus spp. strains (white LB-050 and pale pink LB-051) were isolated from rotten tree trunks of cazahuate (Ipomoea murucoides) from the Mexican Mixtec Region. Both strains were chemically dedikaryotized to obtain their symmetrical monokaryotic components (neohaplonts). This was achieved employing homogenization time periods from 60 to 65 s, and 3 day incubation at 28 °C in a peptone-glucose solution (PGS). Pairing of compatible neohaplonts resulted in 56 hybrid strains which were classified into the four following hybrid types: (R1-nxB1-n, R1-nxB2-1, R2-nxB1-n and R2-nxB2-1). The mycelial growth of Pleurotus spp. monokaryotic and dikaryotic strains showed differences in texture (cottony or floccose), growth (scarce, regular or abundant), density (high, regular or low), and pigmentation (off-white, white or pale pink). To determine the rate and the amount of mycelium growth in malt extract agar at 28 °C, the diameter of the colony was measured every 24 h until the Petri dish was completely colonized. A linear model had the best fit to the mycelial growth kinetics. A direct relationship between mycelial morphology and growth rate was observed. Cottony mycelium presented significantly higher growth rates (p < 0.01) in comparison with floccose mycelium. Thus, mycelial morphology can be used as criterion to select which pairs must be used for optimizing compatible-mating studies. Hybrids resulting from cottony neohaplonts maintained the characteristically high growth rates of their parental strains with the hybrid R1-nxB1-n being faster than the latter. PMID:25477920

  14. Exercise training improves heart rate variability after methamphetamine dependency.

    Science.gov (United States)

    Dolezal, Brett Andrew; Chudzynski, Joy; Dickerson, Daniel; Mooney, Larissa; Rawson, Richard A; Garfinkel, Alan; Cooper, Christopher B

    2014-06-01

    Heart rate variability (HRV) reflects a healthy autonomic nervous system and is increased with physical training. Methamphetamine dependence (MD) causes autonomic dysfunction and diminished HRV. We compared recently abstinent methamphetamine-dependent participants with age-matched, drug-free controls (DF) and also investigated whether HRV can be improved with exercise training in the methamphetamine-dependent participants. In 50 participants (MD = 28; DF = 22), resting heart rate (HR; R-R intervals) was recorded over 5 min while seated using a monitor affixed to a chest strap. Previously reported time domain (SDNN, RMSSD, pNN50) and frequency domain (LFnu, HFnu, LF/HF) parameters of HRV were calculated with customized software. MD were randomized to thrice-weekly exercise training (ME = 14) or equal attention without training (MC = 14) over 8 wk. Groups were compared using paired and unpaired t-tests. Statistical significance was set at P ≤ 0.05. Participant characteristics were matched between groups (mean ± SD): age = 33 ± 6 yr; body mass = 82.7 ± 12 kg, body mass index = 26.8 ± 4.1 kg·min. Compared with DF, the MD group had significantly higher resting HR (P HRV indices were similar between ME and MC groups. However, after training, the ME group significantly (all P HRV, based on several conventional indices, was diminished in recently abstinent, methamphetamine-dependent individuals. Moreover, physical training yielded a marked increase in HRV, representing increased vagal modulation or improved autonomic balance.

  15. Growth rate enhancement of free-electron laser by two consecutive ...

    Indian Academy of Sciences (India)

    2014-06-03

    Jun 3, 2014 ... been the subject of many papers published by different groups all around the world. The radiation is generated by relativistic electron beam passing through a wiggler. ..... Shown in figure 2 are plots of growth rate, Im ¯k, vs.

  16. D2O clusters isolated in rare-gas solids: Dependence of infrared spectrum on concentration, deposition rate, heating temperature, and matrix material

    Science.gov (United States)

    Shimazaki, Yoichi; Arakawa, Ichiro; Yamakawa, Koichiro

    2018-04-01

    The infrared absorption spectra of D2O monomers and clusters isolated in rare-gas matrices were systematically reinvestigated under the control of the following factors: the D2O concentration, deposition rate, heating temperature, and rare-gas species. We clearly show that the cluster-size distribution is dependent on not only the D2O concentration but also the deposition rate of a sample; as the rate got higher, smaller clusters were preferentially formed. Under the heating procedures at different temperatures, the cluster-size growth was successfully observed. Since the monomer diffusion was not enough to balance the changes in the column densities of the clusters, the dimer diffusion was likely to contribute the cluster growth. The frequencies of the bonded-OD stretches of (D2O)k with k = 2-6 were almost linearly correlated with the square root of the critical temperature of the matrix material. Additional absorption peaks of (D2O)2 and (D2O)3 in a Xe matrix were assigned to the species trapped in tight accommodation sites.

  17. Sex-Based Differences in Adelie Penguin (Pygoscelis adeliae Chick Growth Rates and Diet.

    Directory of Open Access Journals (Sweden)

    Scott Jennings

    Full Text Available Sexually size-dimorphic species must show some difference between the sexes in growth rate and/or length of growing period. Such differences in growth parameters can cause the sexes to be impacted by environmental variability in different ways, and understanding these differences allows a better understanding of patterns in productivity between individuals and populations. We investigated differences in growth rate and diet between male and female Adélie Penguin (Pygoscelis adeliae chicks during two breeding seasons at Cape Crozier, Ross Island, Antarctica. Adélie Penguins are a slightly dimorphic species, with adult males averaging larger than adult females in mass (~11% as well as bill (~8% and flipper length (~3%. We measured mass and length of flipper, bill, tibiotarsus, and foot at 5-day intervals for 45 male and 40 female individually-marked chicks. Chick sex was molecularly determined from feathers. We used linear mixed effects models to estimate daily growth rate as a function of chick sex, while controlling for hatching order, brood size, year, and potential variation in breeding quality between pairs of parents. Accounting for season and hatching order, male chicks gained mass an average of 15.6 g d(-1 faster than females. Similarly, growth in bill length was faster for males, and the calculated bill size difference at fledging was similar to that observed in adults. There was no evidence for sex-based differences in growth of other morphological features. Adélie diet at Ross Island is composed almost entirely of two species--one krill (Euphausia crystallorophias and one fish (Pleuragramma antarctica, with fish having a higher caloric value. Using isotopic analyses of feather samples, we also determined that male chicks were fed a higher proportion of fish than female chicks. The related differences in provisioning and growth rates of male and female offspring provides a greater understanding of the ways in which ecological factors

  18. Time-series analysis of multiple foreign exchange rates using time-dependent pattern entropy

    Science.gov (United States)

    Ishizaki, Ryuji; Inoue, Masayoshi

    2018-01-01

    Time-dependent pattern entropy is a method that reduces variations to binary symbolic dynamics and considers the pattern of symbols in a sliding temporal window. We use this method to analyze the instability of daily variations in multiple foreign exchange rates. The time-dependent pattern entropy of 7 foreign exchange rates (AUD/USD, CAD/USD, CHF/USD, EUR/USD, GBP/USD, JPY/USD, and NZD/USD) was found to be high in the long period after the Lehman shock, and be low in the long period after Mar 2012. We compared the correlation matrix between exchange rates in periods of high and low of the time-dependent pattern entropy.

  19. MEAT AND FAT CONTENT AND MEAT QUALITY OF PIGS OF POLISH LARGE WHITE BREED OF DIFFERENT GROWTH RATE

    Directory of Open Access Journals (Sweden)

    Jerzy NOWACHOWICZ

    2009-08-01

    Full Text Available The subject of research were 40 gilts of Polish Large White breed, which were separatively kept and fed under control. They were slaughtered on 185th day of life. Particular dissection of primary cuts and evaluation of some traits of meat quality such as pH1, meat colour and soluble protein content were conducted according to methodology applied in Polish Pig Testing Station. Depending on growth rate during fattening period gilts were divided into two groups (20 individuals each, i.e. lower daily gains of body weight (up to 680 g and higher daily gains of body weight (above 680 g. The limit value regarding daily gain of body weight amounted 680 g and resulted from distribution of this trait in tested population of animals. Significance of differences between tested groups of different growth rate was estimated by using t-Student test and computer program Statistica PL. Tested gilts characterized by higher growth rate had statistically high significant meat weight in primary cuts such as proper ham, loin, belly and ribs by 0.52; 0.38, 0.26 and 0.07 kg, respectively. Differences in total meat weight in primary cuts between group of pigs of higher and lower daily gains were 1.58 kg (P≤0.01. However, percentage meat content re-calculated on 1 kg of half-carcass shaped on similar level in tested groups of gilts. Fat weight in particular primary cuts and percentage fat content re-calculated on 1 kg of half-carcass and relations between percentage meat content and percentage fat content in 1 kg of half-carcass in gilts of tested groups were statistically not diversed. In range of traits characterizing meat quality statistically significant differences between group of pigs of higher and lower daily gains of body weight also were not stated. Therefore, the impact of growth rate on percentage meat and fat content re-calculated on 1 kg of half-carcass and meat quality of pigs of Polish Large White breed was not proved.

  20. Compression-rate-dependent nonlinear mechanics of normal and impaired porcine knee joints.

    Science.gov (United States)

    Rodriguez, Marcel Leonardo; Li, LePing

    2017-11-14

    The knee joint performs mechanical functions with various loading and unloading processes. Past studies have focused on the kinematics and elastic response of the joint with less understanding of the rate-dependent load response associated with viscoelastic and poromechanical behaviors. Forty-five fresh porcine knee joints were used in the present study to determine the loading-rate-dependent force-compression relationship, creep and relaxation of normal, dehydrated and meniscectomized joints. The mechanical tests of all normal intact joints showed similar strong compression-rate-dependent behavior: for a given compression-magnitude up to 1.2 mm, the reaction force varied 6 times over compression rates. While the static response was essentially linear, the nonlinear behavior was boosted with the increased compression rate to approach the asymptote or limit at approximately 2 mm/s. On the other hand, the joint stiffness varied approximately 3 times over different joints, when accounting for the maturity and breed of the animals. Both a loss of joint hydration and a total meniscectomy greatly compromised the load support in the joint, resulting in a reduction of load support as much as 60% from the corresponding intact joint. However, the former only weakened the transient load support, but the latter also greatly weakened the equilibrium load support. A total meniscectomy did not diminish the compression-rate-dependence of the joint though. These findings are consistent with the fluid-pressurization loading mechanism, which may have a significant implication in the joint mechanical function and cartilage mechanobiology.

  1. Investigation of the dose rate dependency of the PAGAT gel dosimeter at low dose rates

    International Nuclear Information System (INIS)

    Zehtabian, M.; Faghihi, R.; Zahmatkesh, M.H.; Meigooni, A.S.; Mosleh-Shirazi, M.A.; Mehdizadeh, S.; Sina, S.; Bagheri, S.

    2012-01-01

    Medical physicists need dosimeters such as gel dosimeters capable of determining three-dimensional dose distributions with high spatial resolution. To date, in combination with magnetic resonance imaging (MRI), polyacrylamide gel (PAG) polymers are the most promising gel dosimetry systems. The purpose of this work was to investigate the dose rate dependency of the PAGAT gel dosimeter at low dose rates. The gel dosimeter was used for measurement of the dose distribution around a Cs-137 source from a brachytherapy LDR source to have a range of dose rates from 0.97 Gy h −1 to 0.06 Gy h −1 . After irradiation of the PAGAT gel, it was observed that the dose measured by gel dosimetry was almost the same at different distances (different dose rates) from the source, although the points nearer the source had been expected to receive greater doses. Therefore, it was suspected that the PAGAT gel is dose rate dependent at low dose rates. To test this further, three other sets of measurements were performed by placing vials containing gel at different distances from a Cs-137 source. In the first two measurements, several plastic vials were exposed to equal doses at different dose rates. An ionization chamber was used to measure the dose rate at each distance. In addition, three TLD chips were simultaneously irradiated in order to verify the dose to each vial. In the third measurement, to test the oxygen diffusion through plastic vials, the experiment was repeated again using plastic vials in a nitrogen box and glass vials. The study indicates that oxygen diffusion through plastic vials for dose rates lower than 2 Gy h −1 would affect the gel dosimeter response and it is suggested that the plastic vials or (phantoms) in an oxygen free environment or glass vials should be used for the dosimetry of low dose rate sources using PAGAT gel to avoid oxygen diffusion through the vials.

  2. Maternal body size and condition determine calf growth rates in southern right whales

    DEFF Research Database (Denmark)

    Christiansen, Fredrik; Vivier, Fabien; Charlton, Claire

    2018-01-01

    The cost of reproduction is a key parameter determining a species' life history strategy. Despite exhibiting some of the fastest offspring growth rates among mammals, the cost of reproduction in baleen whales is largely unknown since standard field metabolic techniques cannot be applied. We...... quantified the cost of reproduction for southern right whales Eubalaena australis over a 3 mo breeding season. We did this by determining the relationship between calf growth rate and maternal rate of loss in energy reserves, using repeated measurements of body volume obtained from unmanned aerial vehicle...... period, and highlights the importance of sufficient maternal energy reserves for reproduction in this capital breeding species....

  3. Angle-dependent strong-field molecular ionization rates with tuned range-separated time-dependent density functional theory

    Energy Technology Data Exchange (ETDEWEB)

    Sissay, Adonay [Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803 (United States); Abanador, Paul; Mauger, François; Gaarde, Mette; Schafer, Kenneth J. [Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803 (United States); Lopata, Kenneth, E-mail: klopata@lsu.edu [Department of Chemistry, Louisiana State University, Baton Rouge, Louisiana 70803 (United States); Center for Computation and Technology, Louisiana State University, Baton Rouge, Louisiana 70803 (United States)

    2016-09-07

    Strong-field ionization and the resulting electronic dynamics are important for a range of processes such as high harmonic generation, photodamage, charge resonance enhanced ionization, and ionization-triggered charge migration. Modeling ionization dynamics in molecular systems from first-principles can be challenging due to the large spatial extent of the wavefunction which stresses the accuracy of basis sets, and the intense fields which require non-perturbative time-dependent electronic structure methods. In this paper, we develop a time-dependent density functional theory approach which uses a Gaussian-type orbital (GTO) basis set to capture strong-field ionization rates and dynamics in atoms and small molecules. This involves propagating the electronic density matrix in time with a time-dependent laser potential and a spatial non-Hermitian complex absorbing potential which is projected onto an atom-centered basis set to remove ionized charge from the simulation. For the density functional theory (DFT) functional we use a tuned range-separated functional LC-PBE*, which has the correct asymptotic 1/r form of the potential and a reduced delocalization error compared to traditional DFT functionals. Ionization rates are computed for hydrogen, molecular nitrogen, and iodoacetylene under various field frequencies, intensities, and polarizations (angle-dependent ionization), and the results are shown to quantitatively agree with time-dependent Schrödinger equation and strong-field approximation calculations. This tuned DFT with GTO method opens the door to predictive all-electron time-dependent density functional theory simulations of ionization and ionization-triggered dynamics in molecular systems using tuned range-separated hybrid functionals.

  4. Angle-dependent strong-field molecular ionization rates with tuned range-separated time-dependent density functional theory

    International Nuclear Information System (INIS)

    Sissay, Adonay; Abanador, Paul; Mauger, François; Gaarde, Mette; Schafer, Kenneth J.; Lopata, Kenneth

    2016-01-01

    Strong-field ionization and the resulting electronic dynamics are important for a range of processes such as high harmonic generation, photodamage, charge resonance enhanced ionization, and ionization-triggered charge migration. Modeling ionization dynamics in molecular systems from first-principles can be challenging due to the large spatial extent of the wavefunction which stresses the accuracy of basis sets, and the intense fields which require non-perturbative time-dependent electronic structure methods. In this paper, we develop a time-dependent density functional theory approach which uses a Gaussian-type orbital (GTO) basis set to capture strong-field ionization rates and dynamics in atoms and small molecules. This involves propagating the electronic density matrix in time with a time-dependent laser potential and a spatial non-Hermitian complex absorbing potential which is projected onto an atom-centered basis set to remove ionized charge from the simulation. For the density functional theory (DFT) functional we use a tuned range-separated functional LC-PBE*, which has the correct asymptotic 1/r form of the potential and a reduced delocalization error compared to traditional DFT functionals. Ionization rates are computed for hydrogen, molecular nitrogen, and iodoacetylene under various field frequencies, intensities, and polarizations (angle-dependent ionization), and the results are shown to quantitatively agree with time-dependent Schrödinger equation and strong-field approximation calculations. This tuned DFT with GTO method opens the door to predictive all-electron time-dependent density functional theory simulations of ionization and ionization-triggered dynamics in molecular systems using tuned range-separated hybrid functionals.

  5. Population Growth Rate: Teaching Guide. Measures of Progress Poster Kit Number 2.

    Science.gov (United States)

    World Bank, Washington, DC.

    This teaching guide accompanies the Population Growth Rate poster kit which is designed to teach students about population growth differences between rich and poor nations and about what people in developing countries are doing to help improve their quality of life. The guide is designed for use with: (1) a poster map of the world providing social…

  6. Role of temperature on growth and metabolic rate in the tenebrionid beetles Alphitobius diaperinus and Tenebrio molitor.

    Science.gov (United States)

    Bjørge, Julie Dahl; Overgaard, Johannes; Malte, Hans; Gianotten, Natasja; Heckmann, Lars-Henrik

    2018-03-10

    Insects are increasingly used as a dietary source for food and feed and it is therefore important to understand how rearing conditions affect growth and development of these agricultural animals. Temperature is arguably the most important factor affecting metabolism and growth rate in insects. Here, we investigated how rearing temperature affected growth rate, growth efficiency and macronutrient composition in two species of edible beetle larvae: Alphitobius diaperinus and Tenebrio molitor. Growth rates of both species were quantified at temperatures ranging from 15.2 to 38.0 °C after which we measured protein and lipid content of the different treatment groups. Metabolic rate was measured in a similar temperature range by measuring the rate of O 2 consumption (V·O 2 ) and CO 2 production (V·CO 2 ) using repeated measures closed respirometry. Using these measurements, we calculated the growth efficiency of mealworms by relating the energy assimilation rate to the metabolic rate. Maximum daily growth rates were 18.3% and 16.6% at 31 °C, for A. diaperinus and T. molitor respectively, and we found that A. diaperinus was better at maintaining growth at high temperatures while T. molitor had superior growth at lower temperatures. Both species had highest efficiencies of energy assimilation in the temperature range of 23.3-31.0 °C, with values close to 2 J assimilated/J metabolised in A. diaperinus and around 4 J assimilated/J metabolised in T. molitor. Compared to "conventional" terrestrial livestock, both species of insects were characterised by high growth rates and very high energy conversion efficiency at most experimental temperatures. For A. diaperinus, lipid content was approximately 30% of dry mass and protein content approximately 50% of dry mass across most temperatures. Temperature had a greater influence on the body composition of T. molitor. At 31.0 °C the lipid and protein content was measured to 47.4% and 37.9%, respectively but lipid

  7. Rate of egg maturation in marine turtles exhibits 'universal temperature dependence'.

    Science.gov (United States)

    Weber, Sam B; Blount, Jonathan D; Godley, Brendan J; Witt, Matthew J; Broderick, Annette C

    2011-09-01

    1. The metabolic theory of ecology (MTE) predicts that, after correcting for body mass variation among organisms, the rates of most biological processes will vary as a universal function of temperature. However, empirical support for 'universal temperature dependence' (UTD) is currently equivocal and based on studies of a limited number of traits. 2. In many ectothermic animals, the rate at which females produce mature eggs is temperature dependent and may be an important factor in determining the costs of reproduction. 3. We tested whether the rate of egg maturation in marine turtles varies with environmental temperature as predicted by MTE, using the time separating successive clutches of individual females to estimate the rate at which eggs are formed. We also assessed the phenotypic contribution to this rate, by using radio telemetry to make repeated measurements of interclutch intervals for individual green turtles (Chelonia mydas). 4. Rates of egg maturation increased with seasonally increasing water temperatures in radio-tracked green turtles, but were not repeatable for individual females, and did not vary according to maternal body size or reproductive investment (number and size of eggs produced). 5. Using a collated data set from several different populations and species of marine turtles, we then show that a single relationship with water temperature explains most of the variation in egg maturation rates, with a slope that is statistically indistinguishable from the UTD predicted by MTE. However, several alternative statistical models also described the relationship between temperature and egg maturation rates equally parsimoniously. 6. Our results offer novel support for the MTE's predicted UTD of biological rates, although the underlying mechanisms require further study. The strong temperature dependence of egg maturation combined with the apparently weak phenotypic contribution to this rate has interesting behavioural implications in ectothermic

  8. Comparison of human dermal fibroblasts (HDFs) growth rate in culture media supplemented with or without basic fibroblast growth factor (bFGF).

    Science.gov (United States)

    Abdian, Narges; Ghasemi-Dehkordi, Payam; Hashemzadeh-Chaleshtori, Morteza; Ganji-Arjenaki, Mahbobe; Doosti, Abbas; Amiri, Beheshteh

    2015-12-01

    Basic fibroblast growth factor (bFGF or FGF-2) is a member of the FGF family secreted by different kinds of cells like HDFs and it is an important nutritional factor for cell growth and differentiation. The HDFs release bFGF in culture media at very low. The present study aims to investigate the HDFs growth rate in culture media supplemented either with or without bFGF. In brief, HDFs were isolated from human foreskin sample and were cultured in vitro in media containing bFGF and lack of this factor. The cells growth rate was calculated by trypan blue. The karyotyping was performed using G-banding to investigate the chromosomal abnormality of HDFs in both groups. Total RNA of each groups were extracted and cDNA samples were synthesized then, real-time Q-PCR was used to measure the expression level of p27kip1 and cyclin D1 genes normalized to internal control gene (GAPDH). The karyotype analysis showed that HDFs cultured in media or without bFGF had normal karyotype (46 chromosomes, XY) and chromosomal abnormalities were not observed. The cell growth rates in both groups were normal with proliferated exponentially but the slope of growth curve in HDFs cultured in media containing bFGF was increased. Karyotyp test showed that bFGF does not affect on cytogenetic stability of cells. The survey of p27kip1 and cyclin D1 genes by real-time Q-PCR showed that the expression level of these genes were up-regulated when adding bFGF in culture media (p culture media with growth factor like bFGF could enhance the proliferation and differentiation capacity of cells and improve cells growth rate. Similarly, fibroblast growth factors did not induce any chromosomal abnormality in cells. Furthermore, in HDFs cultured in bFGF supplemented media, the p27kip1 and cyclin D1 genes were up-regulated and suggesting an important role for bFGF in cell-cycle regulation and progression and fibroblast division stimulation. It also suggests that the effects of bFGF on different cell types with

  9. A replication of the relationship between elderly suicides rates and elderly dependency ratios: cross-national study

    Science.gov (United States)

    Shah, Ajit

    2010-01-01

    Abstract: Background: A positive correlation between elderly dependency ratios and elderly suicide rates has been observed using one-year cross-sectional data on elderly suicide rates. Methods: A cross-national study designed to replicate this positive correlation between elderly dependency ratios and elderly suicide rates was undertaken by: (i) using one-year average of five years data on suicide rates; and (ii) using more recent data on both elderly suicide rates and elderly dependency ratios. Data on elderly suicide rates, and the total number of elderly and young people was ascertained from the World Health Organization website. Results: The main findings were of significant positive correlations between elderly dependency ratios and suicide rates in both sexes in both the elderly age-bands (65-74 years and 75+ years). Conclusions: The replication of the positive correlations between elderly dependency ratios and elderly suicide rates by using one-year average of five years data on suicide rates suggests that this relationship is robust and accurate. PMID:21483194

  10. Parameter estimations in predictive microbiology: Statistically sound modelling of the microbial growth rate.

    Science.gov (United States)

    Akkermans, Simen; Logist, Filip; Van Impe, Jan F

    2018-04-01

    When building models to describe the effect of environmental conditions on the microbial growth rate, parameter estimations can be performed either with a one-step method, i.e., directly on the cell density measurements, or in a two-step method, i.e., via the estimated growth rates. The two-step method is often preferred due to its simplicity. The current research demonstrates that the two-step method is, however, only valid if the correct data transformation is applied and a strict experimental protocol is followed for all experiments. Based on a simulation study and a mathematical derivation, it was demonstrated that the logarithm of the growth rate should be used as a variance stabilizing transformation. Moreover, the one-step method leads to a more accurate estimation of the model parameters and a better approximation of the confidence intervals on the estimated parameters. Therefore, the one-step method is preferred and the two-step method should be avoided. Copyright © 2017. Published by Elsevier Ltd.

  11. Climate is a stronger driver of tree and forest growth rates than soil and disturbance

    NARCIS (Netherlands)

    Toledo, M.; Poorter, L.; Peña-Claros, M.; Alarcón, A.; Balcázar, J.; Leaño, C.; Licona, J.C.; Llanque, O.; Vroomans, V.; Zuidema, P.; Bongers, F.

    2011-01-01

    1. Essential resources such as water, nutrients and light vary over space and time and plant growth rates are expected to vary accordingly. We examined the effects of climate, soil and logging disturbances on diameter growth rates at the tree and stand level, using 165 1-ha permanent sample plots

  12. Insights into crystal growth rates from a study of orbicular granitoids from western Australia

    Science.gov (United States)

    Zhang, J.; Lee, C. T.

    2017-12-01

    The purpose of this study is to develop new tools for constraining crystal growth rate in geologic systems. Of interest is the growth of crystals in magmatic systems because crystallization changes the rheology of a magma as well as provides surfaces on which bubbles can nucleate. To explore crystal growth in more detail, we conducted a case study of orbicular granitoids from western Australia. The orbicules occur as spheroids dispersed in a granitic matrix. Most orbicules have at least two to three concentric bands, composed of elongate and radially oriented hornblende surrounded by interstitial plagioclase. We show that mineral modes and hence bulk composition at the scale of the band is homogeneous from rim to core. Crystal number density decreases and crystal size increases from rim to core. These observations suggest that the orbicules crystallized rapidly from rim to core. We hypothesize that the orbicules are blobs of hot dioritic liquid injected into a cold granitic magma and subsequently cooled and solidified. Crystals stop growing when the mass transport rate tends to zero due to the low temperature. We estimated cooling timescales based on conductive cooling models, constraining crystal growth rates to be 10-6 to 10-5 m/s. We also show that the oscillatory banding is controlled by disequilibrium crystallization, wherein hornblende preferentially crystallizes, resulting in the diffusive growth of a chemical boundary layer enriched in plagioclase component, which in turns results in crystallization of plagioclase. We show that the correlation between the width of each crystallization couplet (band) with distance from orbicule rim is linear, with the slope corresponding to the square root of the ratio between chemical diffusivity in the growth medium and thermal diffusivity. We estimate chemical diffusivity of 2*10-7 m2/s, which is remarkably fast for silicate liquids but reasonable for diffusion in hot aqueous fluids, suggesting that crystallization

  13. Systems Level Regulation of Rhythmic Growth Rate and Biomass Accumulation in Grasses

    Energy Technology Data Exchange (ETDEWEB)

    Kay, Steve A. [Univ. of Southern California, Los Angeles, CA (United States)

    2017-10-20

    Objectives: Several breakthroughs have been recently made in our understanding of plant growth and biomass accumulation. It was found that plant growth is rhythmically controlled throughout the day by the circadian clock through a complex interplay of light and phytohormone signaling pathways. While plants such as the C4 energy crop sorghum (Sorghum bicolor (L.) Moench) and possibly the C3 grass Brachypodium distachyon also exhibit daily rhythms in growth rate, the molecular details of its regulation remain to be explored. A better understanding of diurnally regulated growth behavior in grasses may lead to species-specific mechanisms highly relevant to future strategies to optimize energy crop biomass yield. Here we propose to devise a systems approach to identify, in parallel, regulatory hubs associated with rhythmic growth in C3 and C4 plants. We propose to use rhythmicity in daily growth patterns to drive the discovery of regulatory network modules controlling biomass accumulation. Description: The project is divided in three main parts: 1) Performing time-lapse imaging and growth measurement in B. distachyon and S. bicolor to determine growth rate dynamic during the day/night cycle. Identifying growth-associated genes whose expression patterns follow the observed growth dynamics using deep sequencing technology, 2) identifying regulators of these genes by screening for DNA-binding proteins interacting with the growth-associated gene promoters identified in Aim 1. Screens will be performed using a validated yeast-one hybrid strategy paired with a specifically designed B. distachyon and S. bicolor transcription factor libraries (1000 clones each), and 3) Selecting 50 potential growth regulators from the screen for downstream characterization. The selection will be made by using a sytems biology approach by calculating the connectivity between growth rate, rhythmic gene expression profiles and TF expression profile and determine which TF is likely part of a hub

  14. Value of volume measurements in evaluating abdominal aortic aneurysms growth rate and need for surgical treatment

    Energy Technology Data Exchange (ETDEWEB)

    Kontopodis, Nikolaos, E-mail: kontopodisn@yahoo.gr [Department of Vascular Surgery, University of Crete Medical School, Heraklion (Greece); Metaxa, Eleni, E-mail: emmetaxa@gmail.com [Institute of Applied and Computational Mathematics, Foundation for Research and Technology-Hellas, Heraklion, Crete (Greece); Papaharilaou, Yannis, E-mail: yannisp@iacm.forth.gr [Institute of Applied and Computational Mathematics, Foundation for Research and Technology-Hellas, Heraklion, Crete (Greece); Georgakarakos, Efstratios, E-mail: efstratiosgeorg@gmail.com [Vascular Surgery Department, “Demokritus” University of Thrace Medical School, Alexandroupolis (Greece); Tsetis, Dimitris, E-mail: tsetis@med.uoc.gr [Interventional Radiology Unit, Department of Radiology, University of Crete Medical School, Heraklion, Crete (Greece); Ioannou, Christos V., E-mail: ioannou@med.uoc.gr [Department of Vascular Surgery, University of Crete Medical School, Heraklion (Greece)

    2014-07-15

    Purpose: To examine whether indices other than the traditionally used abdominal aortic aneurysm (AAA) maximum diameter, such as AAA volume, intraluminal thrombus (ILT) thickness and ILT volume, may be superior to evaluate aneurismal enlargement. Materials and methods: Thirty-four small AAAs (initially presenting a maximum diameter <5.5 cm which is the threshold for surgical repair) with an initial and a follow-up CT were examined. Median increase and percentile annual change of these variables was calculated. Correlation between growth rates as determined by the new indices under evaluation and those of maximum diameter were assessed. AAAs were divided according to outcome (surveillance vs. elective repair after follow-up which is based on the maximum diameter criterion) and according to growth rate (high vs. low) based on four indices. Contingency between groups of high/low growth rate regarding each of the four indices on one hand and those regarding need for surgical repair on the other was assessed. Results: A strong correlation between growth rates of maximum diameter and those of AAA and ILT volumes could be established. Evaluation of contingency between groups of outcome and those of growth rate revealed significant associations only for AAA and ILT volumes. Subsequently AAAs with a rapid volumetric increase over time had a likelihood ratio of 10 to be operated compared to those with a slower enlargement. Regarding increase of maximum diameter, likelihood ratio between AAAs with rapid and those with slow expansion was only 3. Conclusion: Growth rate of aneurysms regarding 3Dimensional indices of AAA and ILT volumes is significantly associated with the need for surgical intervention while the same does not hold for growth rates determined by 2Dimensional indices of maximum diameter and ILT thickness.

  15. Value of volume measurements in evaluating abdominal aortic aneurysms growth rate and need for surgical treatment

    International Nuclear Information System (INIS)

    Kontopodis, Nikolaos; Metaxa, Eleni; Papaharilaou, Yannis; Georgakarakos, Efstratios; Tsetis, Dimitris; Ioannou, Christos V.

    2014-01-01

    Purpose: To examine whether indices other than the traditionally used abdominal aortic aneurysm (AAA) maximum diameter, such as AAA volume, intraluminal thrombus (ILT) thickness and ILT volume, may be superior to evaluate aneurismal enlargement. Materials and methods: Thirty-four small AAAs (initially presenting a maximum diameter <5.5 cm which is the threshold for surgical repair) with an initial and a follow-up CT were examined. Median increase and percentile annual change of these variables was calculated. Correlation between growth rates as determined by the new indices under evaluation and those of maximum diameter were assessed. AAAs were divided according to outcome (surveillance vs. elective repair after follow-up which is based on the maximum diameter criterion) and according to growth rate (high vs. low) based on four indices. Contingency between groups of high/low growth rate regarding each of the four indices on one hand and those regarding need for surgical repair on the other was assessed. Results: A strong correlation between growth rates of maximum diameter and those of AAA and ILT volumes could be established. Evaluation of contingency between groups of outcome and those of growth rate revealed significant associations only for AAA and ILT volumes. Subsequently AAAs with a rapid volumetric increase over time had a likelihood ratio of 10 to be operated compared to those with a slower enlargement. Regarding increase of maximum diameter, likelihood ratio between AAAs with rapid and those with slow expansion was only 3. Conclusion: Growth rate of aneurysms regarding 3Dimensional indices of AAA and ILT volumes is significantly associated with the need for surgical intervention while the same does not hold for growth rates determined by 2Dimensional indices of maximum diameter and ILT thickness

  16. Rate Constants of PSII Photoinhibition and its Repair, and PSII Fluorescence Parameters in Field Plants in Relation to their Growth Light Environments.

    Science.gov (United States)

    Miyata, Kazunori; Ikeda, Hiroshi; Nakaji, Masayoshi; Kanel, Dhana Raj; Terashima, Ichiro

    2015-09-01

    The extent of photoinhibition of PSII is determined by a balance between the rate of photodamage to PSII and that of repair of the damaged PSII. It has already been indicated that the rate constants of photodamage (kpi) and repair (krec) of the leaves differ depending on their growth light environment. However, there are no studies using plants in the field. We examined these rate constants and fluorescence parameters of several field-grown plants to determine inter-relationships between these values and the growth environment. The kpi values were strongly related to the excess energy, EY, of the puddle model and non-regulated energy dissipation, Y(NO), of the lake model, both multiplied by the photosynthetically active photon flux density (PPFD) level during the photoinhibitory treatment. In contrast, the krec values corrected against in situ air temperature were very strongly related to the daily PPFD level. The plants from the fields showed higher NPQ than the chamber-grown plants, probably because these field plants acclimated to stronger lightflecks than the averaged growth PPFD. Comparing chamber-grown plants and the field plants, we showed that kpi is determined by the incident light level and the photosynthetic capacities such as in situ rate of PSII electron transport and non-photochemical quenching (NPQ) [e.g. Y(NO)×PPFD] and that krec is mostly determined by the growth light and temperature levels. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  17. The Effect of CO2 Injection on Macroalgae Gelidium latifolium Biomass Growth Rate and Carbohydrate Content

    Directory of Open Access Journals (Sweden)

    Mujizat Kawaroe

    2016-06-01

    Full Text Available There are many species of macroalga grow in marine ecosystem and potentially as raw material for bioethanol resource. Bioethanol is a conversion result of carbohydrate, one of macroalgae biomass content. The exploration of macroalgae require information about  growth rate ability to determine availability in the nature. This research analyze growth rate and carbohydrate content of marine macroalga Gelidium latifolium on cultivation using varied injection of carbon dioxide and aeration. The treatments were control (K, 2000 cc CO2 injection and aeration (P1, 3000 cc CO2 injection and aeration (P2, 2000 cc CO2 injection without aeration (P3, and 3000 cc CO2 injection without aeration (P4. Samples weight were 3 gram in early cultivation on laboratorium scale for 42 days observation. The results showed that the daily growth rate Gelidium latifolium during the study ranged from 0.02-1.06%. The highest daily growth rate was 1.06±0.14% (P2. Carbohydrate yield was 18.23% in early cultivation then 19.40% (K and P2, 20.40% (P1, 16.87% (K3, and 16.40% (P4 after cultivation. The high of carbohydrates value may not guarantee the sustainable Gelidium latifolium biomass utilization as raw material for bioethanol production because of the low growth rate, thus it is necessary to modified and encourage cultivation method effectively. Keywords: CO2 injection, growth rate, carbohydrate, macroalgae, Gelidium latifolium

  18. Cucumber seedling dependence on cotyledonary leaves for early growth Dependência das folhas cotiledonares para o crescimento inicial de pepino

    Directory of Open Access Journals (Sweden)

    Dilson Antônio Bisognin

    2005-06-01

    Full Text Available The objective of this work was to evaluate the dependence of cucumber (Cucumis sativus L. seedlings on cotyledonary leaves for early growth and establishment. Sets of two uniform emerging seedlings were used to quantify the initial growth and dry matter accumulation, as well as the intensity and stage of cotyledon damage in seedling establishment and to determine cotyledon protein, amino acid and carbohydrate contributions to the growing seedling. Cucumber seedling establishment was found to be highly dependent on cotyledonary leaves. Root system establishment was highly dependent on the health of the aerial part. One cotyledon was enough to maintain aerial growth of seedlings after unfolding the first true leaf. Cucumber seedlings depended on both cotyledons to keep root system growth at least until leaf area was equivalent to cotyledon area. Covering one or both cotyledons of seedlings with one unfolded leaf increased carbohydrate content of uncovered cotyledon and leaves compared with control seedlings. Cucumber seedlings are highly dependent on cotyledonary leaves and aerial parts are less dependent than root system. Cotyledon damage at early stages of plant establishment would adversely impact crop yield by reducing plant density, an important yield component, or slowing down seedling growth and establishment.O objetivo deste trabalho foi estudar o desempenho das folhas cotiledonares no crescimento inicial e estabelecimento de plântulas de pepino (Cucumis sativus L.. Grupos de duas plântulas uniformemente emergidas foram utilizados para quantificar o crescimento inicial e acúmulo de matéria seca, o efeito da intensidade e época de remoção dos cotilédones sobre o estabelecimento da plântula, e a contribuição de proteínas, aminoácidos e carboidratos dos cotilédones para o crescimento inicial. O estabelecimento das plântulas de pepino foi altamente dependente das folhas cotiledonares. As folhas cotiledonares foram fundamentais

  19. Interstate Differences on Economic Growth Rates in Australia, 1953-54 to 1990-91

    OpenAIRE

    Harris, P; Harris, D

    1992-01-01

    This paper examines interstate differences in economic growth rates in Australia over the period 1953-54 to 1990-91 using a six State classification (with ACT included in New South Wales and the Northern Territory in South Australia). The economic growth rate is measured by the increase in constant price gross state product at factor cost (GSP) per head of population over time, using three year moving averages of GSP and population to remove some of the annual fluctuations in the data. The an...

  20. Relationships between vital rates and ecological traits in an avian community.

    Science.gov (United States)

    Bellier, Edwige; Kéry, Marc; Schaub, Michael

    2018-03-30

    Comparative studies about the relationships between vital rates and ecological traits at the community level are conspicuously lacking for most taxa because estimating vital rates requires detailed demographic data. Identifying relationships between vital rates and ecological traits could help to better understand ecological and evolutionary demographic mechanisms that lead to interspecific differences in vital rates. We use novel dynamic N-mixture models for counts to achieve this for a whole avian community comprising 53 passerine species, while simultaneously accounting for density dependence and environmental stochasticity in recruitment and survival and, importantly, correcting our inferences for imperfect detection. Demographic stochasticity is taken into account in the form of the binomial and Poisson distributions describing survival events and number of recruits. We then explore relationships between estimated demographic parameters (i.e., vital rates) and ecological traits related to migration patterns, diet, habitat and nesting location of each species. The relative importance of recruitment and adult survival as contributors to population growth varied greatly among species, and interspecific differences in vital rates partly reflected differences in ecological traits. Migratory mode was associated with interspecific differences in population growth and density dependence. Resident species had higher population growth rates than long- and short-distance migrants. We found no relationships between diet and population growth rate. Habitat differences were associated with different growth rates: alpine, wetland and farmland species had lower population growth rates than forest species. Differences in population growth rates among nesting locations showed that breeding habitat is essential for population dynamics. Our study reveals relationships between ecological traits and contributions of vital rates to population growth and suggests ways in which

  1. In situ growth rates and biofilm development of Pseudomonas aeruginosa populations in chronic lung infections

    DEFF Research Database (Denmark)

    Yang, L.; Haagensen, J.A.; Jelsbak, L.

    2008-01-01

    matrix, whereas nonmucoid variants were present mainly as dispersed cells. To obtain estimates of the growth rates of P. aeruginosa in CF lungs, we used quantitative FISH to indirectly measure growth rates of bacteria in sputum samples (reflecting the in vivo lung conditions). The concentration of r......The growth dynamics of bacterial pathogens within infected hosts are a fundamental but poorly understood feature of most infections. We have focused on the in situ distribution and growth characteristics of two prevailing and transmissible Pseudomonas aeruginosa clones that have caused chronic lung......RNA in bacteria isolated from sputa was measured and correlated with the rRNA contents of the same bacteria growing in vitro at defined rates. The results showed that most cells were actively growing with doubling times of between 100 and 200 min, with some growing even faster. Only a small stationary...

  2. Flexibility in metabolic rate confers a growth advantage under changing food availability.

    Science.gov (United States)

    Auer, Sonya K; Salin, Karine; Rudolf, Agata M; Anderson, Graeme J; Metcalfe, Neil B

    2015-09-01

    1. Phenotypic flexibility in physiological, morphological and behavioural traits can allow organisms to cope with environmental challenges. Given recent climate change and the degree of habitat modification currently experienced by many organisms, it is therefore critical to quantify the degree of phenotypic variation present within populations, individual capacities to change and what their consequences are for fitness. 2. Flexibility in standard metabolic rate (SMR) may be particularly important since SMR reflects the minimal energetic cost of living and is one of the primary traits underlying organismal performance. SMR can increase or decrease in response to food availability, but the consequences of these changes for growth rates and other fitness components are not well known. 3. We examined individual variation in metabolic flexibility in response to changing food levels and its consequences for somatic growth in juvenile brown trout (Salmo trutta). 4. SMR increased when individuals were switched to a high food ration and decreased when they were switched to a low food regime. These shifts in SMR, in turn, were linked with individual differences in somatic growth; those individuals that increased their SMR more in response to elevated food levels grew fastest, while growth at the low food level was fastest in those individuals that depressed their SMR most. 5. Flexibility in energy metabolism is therefore a key mechanism to maximize growth rates under the challenges imposed by variability in food availability and is likely to be an important determinant of species' resilience in the face of global change. © 2015 The Authors. Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.

  3. Effect of Alfvén waves on the growth rate of the electron-cyclotron maser emission

    Energy Technology Data Exchange (ETDEWEB)

    Wu, D. J., E-mail: djwu@pmo.ac.cn [Purple Mountain Observatory, CAS, Nanjing 210008 (China)

    2014-06-15

    By using the non-relativistic approximation for the calculation of growth rates, but taking account of the weakly relativistic modification for the electron-cyclotron resonance condition, it is shown that the effect of Alfvén waves (AWs) on the electron-cyclotron maser emission leads to the significant increase of the O-mode growth rate, but has little effect on the X-mode growth rate. We propose that this is because the O-mode wave has the field-aligned polarization sense in the same as the field-aligned oscillatory current, which is created by the field-aligned oscillatory motion of the energetic electrons caused via the presence of AWs. It is this field-aligned oscillatory current that contributes a novel growth rate to the O-mode wave but has little effect on the X-mode wave.

  4. Density dependence, whitebark pine, and vital rates of grizzly bears

    Science.gov (United States)

    van Manen, Frank T.; Haroldson, Mark A.; Bjornlie, Daniel D.; Ebinger, Michael R.; Thompson, Daniel J.; Costello, Cecily M.; White, Gary C.

    2016-01-01

    Understanding factors influencing changes in population trajectory is important for effective wildlife management, particularly for populations of conservation concern. Annual population growth of the grizzly bear (Ursus arctos) population in the Greater Yellowstone Ecosystem, USA has slowed from 4.2–7.6% during 1983–2001 to 0.3–2.2% during 2002–2011. Substantial changes in availability of a key food source and bear population density have occurred. Whitebark pine (Pinus albicaulis), the seeds of which are a valuable but variable fall food for grizzly bears, has experienced substantial mortality primarily due to a mountain pine beetle (Dendroctonus ponderosae) outbreak that started in the early 2000s. Positive growth rates of grizzly bears have resulted in populations reaching high densities in some areas and have contributed to continued range expansion. We tested research hypotheses to examine if changes in vital rates detected during the past decade were more associated with whitebark pine decline or, alternatively, increasing grizzly bear density. We focused our assessment on known-fate data to estimate survival of cubs-of-the-year (cubs), yearlings, and independent bears (≥2 yrs), and reproductive transition of females from having no offspring to having cubs. We used spatially and temporally explicit indices for grizzly bear density and whitebark pine mortality as individual covariates. Models indicated moderate support for an increase in survival of independent male bears over 1983–2012, whereas independent female survival did not change. Cub survival, yearling survival, and reproductive transition from no offspring to cubs all changed during the 30-year study period, with lower rates evident during the last 10–15 years. Cub survival and reproductive transition were negatively associated with an index of grizzly bear density, indicating greater declines where bear densities were higher. Our analyses did not support a similar relationship for the

  5. Theory of electromagnetic cyclotron wave growth in a time-varying magnetoplasma

    International Nuclear Information System (INIS)

    Gail, W.B.

    1990-01-01

    The time-dependent growth rate for parallel propagating electromagnetic cyclotron waves is derived for a magnetoplasma which is characterized by a time dependent compressional perturbation superimposed on an equilibrium configuration. Such perturbations are commonly observed in the Earth's magnetosphere as a consequence of resonant field line oscillations, solar-wind disturbances, and other phenomena. The time dependencies of the magnetic field, thermal plasma density, energetic particle distribution function, and resonance condition are first related through a single dimensionless time parameter b(t) using the ideal MHD assumption. For cases in which the particle distribution can be described by F(α, E) = f(E)sin a(E) α, the time dependent wave growth rate is then given by γ≅ γ 0 (1 + Λ) where γ 0 is the equilibrium growth rate and Λ(b) is a function of the equilibrium parameters and the time parameter b. The term |Λ| is generally small compared to 1, and the effect is a small modulation of the equilibrium growth rate by Λ. If the particle distribution is locally near marginal stability, however, |Λ| is large compared to 1, and the growth rate modulation can be much larger than for a distribution which is not near marginal stability. The results suggest that particle populations which are near marginal stability may be strongly influenced by perturbations in the magnetic field and plasma. Marginally stable distributions may thus play an important role in magnetospheric dynamics as well as determination of radiation belt characteristics

  6. Growth orientation dependence of Si doping in GaAsN

    Energy Technology Data Exchange (ETDEWEB)

    Han, Xiuxun, E-mail: xxhan@semi.ac.cn [Laboratory of Clean Energy Chemistry and Materials, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China); State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China); Dong, Chen [Laboratory of Clean Energy Chemistry and Materials, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, 730000 (China); Feng, Qiang [Optoelectronic Department, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun, 130033 (China); Ohshita, Yoshio; Yamaguchi, Masafumi [Toyota Technological Institute, 2-12-1 Hisakata, Tempaku, Nagoya, 468-8511 (Japan)

    2015-02-07

    The incorporation of Si in GaAsN alloys grown simultaneously on (100), (311)A, (311)B, and (211)B GaAs substrates by the chemical beam epitaxy has been investigated. The decrease in electron concentration with the increasing N composition suggests the occurrence of N and Si interaction, whereas the interaction exhibits evidently different extent depending on the growth orientation. Combined with the secondary ion mass spectrometry and photoluminescence measurements, it is revealed that (311)B and (211)B are the promising substrate orientations to reduce the N-Si passivation and improve n-type Si doping in GaAsN over a wider N composition range. A surface bonding model is utilized to explain the plane polarity dependent incorporation behaviors of Si and N.

  7. Growth rates and geochemical proxies in Late Campanian bivalves - New insights from micro-X-ray Fluorescence mapping and numerical growth modelling

    Science.gov (United States)

    de Winter, Niels; Goderis, Steven; van Malderen, Stijn; Vanhaecke, Frank; Claeys, Philippe

    2017-04-01

    surfaces is combined with high-precision point measurements and linescans to characterize different carbonate facies within the shell and to model changes in proxy data in three dimensions. Comparison of sub-annual variations in growth rate and shell geometry with proxy data sheds light on the degree to which observed seasonal variations in geochemical proxies are dependent on internal mechanisms of shell growth as opposed to external mechanisms such as climatic and environmental change. The use of three different species of bivalve from the same paleoenvironment allows the examination of species-specific responses to environmental change. This study attempts to determine which proxies in which species of bivalve are suitable for paleoenvironmental reconstruction and will aid future paleoseasonality studies in interpreting seasonally resolved multi-proxy records. References 1 DeConto R.M., et al. Cambridge University Press; 2000. 2 Elliot M, et al., PPP 2009. 3 Steuber T. Geology. 1996. 4 R core team, 2004, www.R-project.org

  8. TEST OF THE CATCH-UP HYPOTHESIS IN AFRICAN AGRICULTURAL GROWTH RATES

    Directory of Open Access Journals (Sweden)

    Kalu Ukpai IFEGWU

    2015-11-01

    Full Text Available The paper tested the catch-up hypothesis in agricultural growth rates of twenty-six African countries. Panel data used was drawn from the Food and Agricultural Organization Statistics (FAOSTAT of the United Nations. The Data Envelopment Analysis Method for measuring productivity was used to estimate productivity growth rates. The cross-section framework consisting of sigma-convergence and beta-convergence was employed to test the catching up process. Catching up is said to exist if the value of beta is negative and significant. Since catching up does not necessarily imply narrowing of national productivity inequalities, sigma-convergence which measures inequality, was estimated for the same variables. The results showed evidence of the catch-up process, but failed to find a narrowing of productivity inequalities among countries.

  9. Inhibition of fibroblast growth factor receptor 3-dependent lung adenocarcinoma with a human monoclonal antibody

    Directory of Open Access Journals (Sweden)

    Yongjun Yin

    2016-05-01

    Full Text Available Activating mutations in fibroblast growth factor receptor 3 (FGFR3 have been identified in multiple types of human cancer and in congenital birth defects. In human lung cancer, fibroblast growth factor 9 (FGF9, a high-affinity ligand for FGFR3, is overexpressed in 10% of primary resected non-small cell lung cancer (NSCLC specimens. Furthermore, in a mouse model where FGF9 can be induced in lung epithelial cells, epithelial proliferation and ensuing tumorigenesis is dependent on FGFR3. To develop new customized therapies for cancers that are dependent on FGFR3 activation, we have used this mouse model to evaluate a human monoclonal antibody (D11 with specificity for the extracellular ligand-binding domain of FGFR3, that recognizes both human and mouse forms of the receptor. Here, we show that D11 effectively inhibits signaling through FGFR3 in vitro, inhibits the growth of FGFR3-dependent FGF9-induced lung adenocarcinoma in mice, and reduces tumor-associated morbidity. Given the potency of FGF9 in this mouse model and the absolute requirement for signaling through FGFR3, this study validates the D11 antibody as a potentially useful and effective reagent for treating human cancers or other pathologies that are dependent on activation of FGFR3.

  10. Endothelial MMP14 is required for endothelial-dependent growth support of human airway basal cells

    Science.gov (United States)

    Ding, Bi-Sen; Gomi, Kazunori; Rafii, Shahin; Crystal, Ronald G.; Walters, Matthew S.

    2015-01-01

    ABSTRACT Human airway basal cells are the stem (or progenitor) population of the airway epithelium, and play a central role in anchoring the epithelium to the basement membrane. The anatomic position of basal cells allows for potential paracrine signaling between them and the underlying non-epithelial stromal cells. In support of this, we have previously demonstrated that endothelial cells support growth of basal cells during co-culture through vascular endothelial growth factor A (VEGFA)-mediated signaling. Building on these findings, we found, by RNA sequencing analysis, that basal cells expressed multiple fibroblast growth factor (FGF) ligands (FGF2, FGF5, FGF11 and FGF13) and that only FGF2 and FGF5 were capable of functioning in a paracrine manner to activate classical FGF receptor (FGFR) signaling. Antibody-mediated blocking of FGFR1 during basal-cell–endothelial-cell co-culture significantly reduced the endothelial-cell-dependent basal cell growth. Stimulation of endothelial cells with basal-cell-derived growth factors induced endothelial cell expression of matrix metallopeptidase 14 (MMP14), and short hairpin RNA (shRNA)-mediated knockdown of endothelial cell MMP14 significantly reduced the endothelial-cell-dependent growth of basal cells. Overall, these data characterize a new growth-factor-mediated reciprocal ‘crosstalk’ between human airway basal cells and endothelial cells that regulates proliferation of basal cells. PMID:26116571

  11. Efficient rate control scheme using modified inter-layer dependency ...

    Indian Academy of Sciences (India)

    The IRC from the prior art is modified to achieve better rate control per layer by recursive updates for mean absolute difference values of eachbasic unit. Proposed modified inter-layer dependency shows improvement in the PSNR for enhancement layers while the updated IRC enforces better IRC for all the layers.

  12. Widespread Dependence of Backup NHEJ on Growth State: Ramifications for the Use of DNA-PK Inhibitors

    International Nuclear Information System (INIS)

    Singh, Satyendra K.; Wu Wenqi; Zhang Lihua; Klammer, Holger; Wang Minli; Iliakis, George

    2011-01-01

    Purpose: The backup pathway of nonhomologous end joining (B-NHEJ) enables cells to process DNA double-strand breaks (DSBs) when the DNA-PK-dependent pathway of NHEJ (D-NHEJ) is compromised. Our previous results show marked reduction in the activity of B-NHEJ when LIG4 -/- mouse embryo fibroblasts (MEFs) cease to grow and enter a plateau phase. The dependence of B-NHEJ on growth state is substantially stronger than that of D-NHEJ and points to regulatory mechanisms or processing determinants that require elucidation. Because the different D-NHEJ mutants show phenotypes distinct in their details, it is necessary to characterize the dependence of their DSB repair capacity on growth state and to explore species-specific responses. Methods and Materials: DSB repair was measured in cells of different genetic background from various species using pulsed-field gel electrophoresis, or the formation of γ-H2AX foci, at different stages of growth. Results: Using pulsed-field gel electrophoresis, we report a marked reduction of B-NHEJ during the plateau phase of growth in KU and XRCC4, mouse or Chinese hamster, mutants. Notably, this reduction is only marginal in DNA-PKcs-deficient cells. However, reduced B-NHEJ is also observed in repair proficient, plateau-phase cells after treatment with DNA-PK inhibitors. The reduction of B-NHEJ activity in the plateau phase of growth does not derive from the reduced expression of participating proteins, is detectable by γ-H2AX foci analysis, and leads to enhanced cell killing. Conclusions: These results further document the marked dependence on growth state of an essential DSB repair pathway and show the general nature of the effect. Molecular characterization of the mechanism underlying this response will help to optimize the administration of DNA repair inhibitors as adjuvants in radiation therapy.

  13. Effect of feeding frequency and feeding rate on growth performance ...

    African Journals Online (AJOL)

    Fish fed at higher feeding rates accumulated significantly more lipid within the body and had associated decreases in moisture, protein, and ash content, but carcass composition was unaffected by feeding frequency. Juvenile pompano show better growth performance when fed 10% BW/day 3 and 6 times a day.

  14. Growth condition depend