Science.gov

Sample records for accelerated growth rates

  1. Transgenic tobacco plants overexpressing the Nicta; CycD3; 4 gene demonstrate accelerated growth rates.

    PubMed

    Guo, Jia; Wang, Myeong Hyeon

    2008-07-31

    D-type cyclins control the onset of cell division and the response to extracellular signals during the G1 phase. In this study, we transformed a D-type cyclin gene, Nicta;CycD3;4, from Nicotiana tabacum using an Agrobacterium-mediated method. A predicted 1.1 kb cyclin gene was present in all of the transgenic plants, but not in wild-type. Northern analyses showed that the expression level of the Nicta;CycD3;4 gene in all of the transgenic plants was strong when compared to the wild-type plants, suggesting that Nicta;CycD3;4 gene driven by the CaMV 35S promoter was being overexpressed. Our results revealed that transgenic plants overexpressing Nicta;CycD3;4 had an accelerated growth rate when compared to wild-type plants, and that the transgenic plants exhibited a smaller cell size and a decreased cell population in young leaves when compared to wild-type plants.

  2. Oscillations and accelerations of ice crystal growth rates in microgravity in presence of antifreeze glycoprotein impurity in supercooled water.

    PubMed

    Furukawa, Yoshinori; Nagashima, Ken; Nakatsubo, Shun-Ichi; Yoshizaki, Izumi; Tamaru, Haruka; Shimaoka, Taro; Sone, Takehiko; Yokoyama, Etsuro; Zepeda, Salvador; Terasawa, Takanori; Asakawa, Harutoshi; Murata, Ken-Ichiro; Sazaki, Gen

    2017-03-06

    The free growth of ice crystals in supercooled bulk water containing an impurity of glycoprotein, a bio-macromolecule that functions as 'antifreeze' in living organisms in a subzero environment, was observed under microgravity conditions on the International Space Station. We observed the acceleration and oscillation of the normal growth rates as a result of the interfacial adsorption of these protein molecules, which is a newly discovered impurity effect for crystal growth. As the convection caused by gravity may mitigate or modify this effect, secure observations of this effect were first made possible by continuous measurements of normal growth rates under long-term microgravity condition realized only in the spacecraft. Our findings will lead to a better understanding of a novel kinetic process for growth oscillation in relation to growth promotion due to the adsorption of protein molecules and will shed light on the role that crystal growth kinetics has in the onset of the mysterious antifreeze effect in living organisms, namely, how this protein may prevent fish freezing.

  3. Oscillations and accelerations of ice crystal growth rates in microgravity in presence of antifreeze glycoprotein impurity in supercooled water

    NASA Astrophysics Data System (ADS)

    Furukawa, Yoshinori; Nagashima, Ken; Nakatsubo, Shun-Ichi; Yoshizaki, Izumi; Tamaru, Haruka; Shimaoka, Taro; Sone, Takehiko; Yokoyama, Etsuro; Zepeda, Salvador; Terasawa, Takanori; Asakawa, Harutoshi; Murata, Ken-Ichiro; Sazaki, Gen

    2017-03-01

    The free growth of ice crystals in supercooled bulk water containing an impurity of glycoprotein, a bio-macromolecule that functions as ‘antifreeze’ in living organisms in a subzero environment, was observed under microgravity conditions on the International Space Station. We observed the acceleration and oscillation of the normal growth rates as a result of the interfacial adsorption of these protein molecules, which is a newly discovered impurity effect for crystal growth. As the convection caused by gravity may mitigate or modify this effect, secure observations of this effect were first made possible by continuous measurements of normal growth rates under long-term microgravity condition realized only in the spacecraft. Our findings will lead to a better understanding of a novel kinetic process for growth oscillation in relation to growth promotion due to the adsorption of protein molecules and will shed light on the role that crystal growth kinetics has in the onset of the mysterious antifreeze effect in living organisms, namely, how this protein may prevent fish freezing.

  4. Oscillations and accelerations of ice crystal growth rates in microgravity in presence of antifreeze glycoprotein impurity in supercooled water

    PubMed Central

    Furukawa, Yoshinori; Nagashima, Ken; Nakatsubo, Shun-ichi; Yoshizaki, Izumi; Tamaru, Haruka; Shimaoka, Taro; Sone, Takehiko; Yokoyama, Etsuro; Zepeda, Salvador; Terasawa, Takanori; Asakawa, Harutoshi; Murata, Ken-ichiro; Sazaki, Gen

    2017-01-01

    The free growth of ice crystals in supercooled bulk water containing an impurity of glycoprotein, a bio-macromolecule that functions as ‘antifreeze’ in living organisms in a subzero environment, was observed under microgravity conditions on the International Space Station. We observed the acceleration and oscillation of the normal growth rates as a result of the interfacial adsorption of these protein molecules, which is a newly discovered impurity effect for crystal growth. As the convection caused by gravity may mitigate or modify this effect, secure observations of this effect were first made possible by continuous measurements of normal growth rates under long-term microgravity condition realized only in the spacecraft. Our findings will lead to a better understanding of a novel kinetic process for growth oscillation in relation to growth promotion due to the adsorption of protein molecules and will shed light on the role that crystal growth kinetics has in the onset of the mysterious antifreeze effect in living organisms, namely, how this protein may prevent fish freezing. PMID:28262787

  5. Accelerated Growth Rate and Increased Drought Stress Resilience of the Model Grass Brachypodium distachyon Colonized by Bacillus subtilis B26.

    PubMed

    Gagné-Bourque, François; Mayer, Boris F; Charron, Jean-Benoit; Vali, Hojatollah; Bertrand, Annick; Jabaji, Suha

    2015-01-01

    Plant growth-promoting bacteria (PGB) induce positive effects in plants, for instance, increased growth and reduced abiotic stresses susceptibility. The mechanisms by which these bacteria impact the host plant are numerous, diverse and often specific. Here, we studied the agronomical, molecular and biochemical effects of the endophytic PGB Bacillus subtilis B26 on the full life cycle of Brachypodium distachyon Bd21, an established model species for functional genomics in cereal crops and temperate grasses. Inoculation of Brachypodium with B. subtilis strain B26 increased root and shoot weights, accelerated growth rate and seed yield as compared to control plants. B. subtilis strain B26 efficiently colonized the plant and was recovered from roots, stems and blades as well as seeds of Brachypodium, indicating that the bacterium is able to migrate, spread systemically inside the plant, establish itself in the aerial plant tissues and organs, and is vertically transmitted to seeds. The presence of B. subtilis strain B26 in the seed led to systemic colonization of the next generation of Brachypodium plants. Inoculated Brachypodium seedlings and mature plants exposed to acute and chronic drought stress minimized the phenotypic effect of drought compared to plants not harbouring the bacterium. Protection from the inhibitory effects of drought by the bacterium was linked to upregulation of the drought-response genes, DREB2B-like, DHN3-like and LEA-14-A-like and modulation of the DNA methylation genes, MET1B-like, CMT3-like and DRM2-like, that regulate the process. Additionally, total soluble sugars and starch contents increased in stressed inoculated plants, a biochemical indication of drought tolerance. In conclusion, we show a single inoculation of Brachypodium with a PGB affected the whole growth cycle of the plant, accelerating its growth rates, shortening its vegetative period, and alleviating drought stress effects. These effects are relevant to grasses and cereal

  6. Accelerated Stem Growth Rates and Improved Fiber Properties of Loblolly Pine: Functional Analysis Of CyclinD from Pinus taeda

    SciTech Connect

    Dr. John Cairney, School of Biology and Institute of Paper Science and Technology @ Georgia Tech, Georgia Institute of Technology; Dr. Gary Peter, University of Florida; Dr. Ulrika Egertsdotter, Dept. of Forestry, Virgina Tech; Dr. Armin Wagner, New Zealand Forest Research Institute Ltd.

    2005-11-30

    A sustained supply of low-cost, high quality raw materials is essential for the future success of the U.S. forest products industry. To maximize stem (trunk) growth, a fundamental understanding of the molecular mechanisms that regulate cell divisions within the cambial meristem is essential. We hypothesize that auxin levels within the cambial meristem regulate cyclin gene expression and this in turn controls cell cycle progression as occurs in all eukaryotic cells. Work with model plant species has shown that ectopic overexpression of cyclins promotes cell division thereby increasing root growth > five times. We intended to test whether ectopic overexpression of cambial cyclins in the cambial zone of loblolly pine also promotes cell division rates that enhance stem growth rates. Results generated in model annual angiosperm systems cannot be reliably extrapolated to perennial gymnosperms, thus while the generation and development of transgenic pine is time consuming, this is the necessary approach for meaningful data. We succeeded in isolating a cyclin D gene and Clustal analysis to the Arabidopsis cyclin D gene family indicates that it is more closely related to cyclin D2 than D1 or D3 Using this gene as a probe we observed a small stimulation of cyclin D expression in somatic embryo culture upon addition of auxin. We hypothesized that trees with more cells in the vascular cambial and expansion zones will have higher cyclin mRNA levels. We demonstrated that in trees under compressive stress where the rates of cambial divisions are increased on the underside of the stem relative to the top or opposite side, there was a 20 fold increase in the level of PtcyclinD1 mRNA on the compressed side of the stem relative to the opposite. This suggests that higher secondary growth rates correlate with PtcyclinD1 expression. We showed that larger diameter trees show more growth during each year and that the increased growth in loblolly pine trees correlates with more cell

  7. Late Pleistocene-Holocene acceleration of uplift rate in southwest Erromango Island, Southern Vanuatu, South Pacific: relation to the growth of the Vanuatuan Mid Sedimentary Basin

    SciTech Connect

    Neef, G.; Hendy, C.

    1988-07-01

    Late Quaternary and Holocene raised coral reefs are well developed in southwestern Erromango Island, which lies in the frontal arc area of the Vanuatuan Island Arc. Eight uranium series ages and one /sup 14/C age from samples from coral reefs at three localities range in age from 4800 B.P. to about 320,000 B.P. Six of the samples dated are from the Matiwo Point area. Here the youngest reef has given a /sup 230/Th//sup 234/U age of 4800 B.P. and a slightly older reef, 4.3 m higher in elevation, has a /sup 14/C age of 5270 B.P. Inland of a cliff the youngest three of four northeastward-tilted raised reefs have given /sup 230/Th//sup 234/U ages ranging from 104,000 B.P. to about 320,000 B.P. These data indicate accelerating uplift rates for southwest Erromango: during the periods 320,000-133,000 B.P., 133,000-6000 B.P., and 6000 - 0 B.P. average uplift rates were 0.33 mm/yr, 0.65 mm/yr, and about 1 mm/yr respectively. These data are interpreted to indicate the growth of the Mid Sedimentary Basin, which lies within the frontal and volcanic arc part of the island arc complex. This increase in uplift/eastward-tilting could represent a Quaternary-Late Pleistocene increase in the subduction rate of the Australian Plate beneath Erromango.

  8. Modeling Nonlinear Change via Latent Change and Latent Acceleration Frameworks: Examining Velocity and Acceleration of Growth Trajectories

    ERIC Educational Resources Information Center

    Grimm, Kevin; Zhang, Zhiyong; Hamagami, Fumiaki; Mazzocco, Michele

    2013-01-01

    We propose the use of the latent change and latent acceleration frameworks for modeling nonlinear growth in structural equation models. Moving to these frameworks allows for the direct identification of "rates of change" and "acceleration" in latent growth curves--information available indirectly through traditional growth…

  9. Dinosaurian growth patterns and rapid avian growth rates.

    PubMed

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

    2001-07-26

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

  10. Impact of accelerated plant growth on seed variety development

    NASA Astrophysics Data System (ADS)

    Christophersen, Eric

    1998-01-01

    The commercial lives of agricultural seed products have steadily declined in recent years. The introduction of genetically engineered crop seeds in 1966 has accentuated that trend. Widespread grower demand for genetically engineered seed requires competitive response by industry followers in order to avert market share losses to the industry leaders. Limitations on plant transformation technology, regulatory requirements and patent impediments require companies to rapidly convert transformed lines into elite commercial products. Massive multigenerational backcrossing efforts are required to distribute genetically engineered traits into a broad product mix. Significant incidents of expression failures, or ``gene silencing,'' have occurred unexpectedly, requiring product substitution strategies. First-to-market strategies, competitive response, broad germplasm conversion and rescue of product failures all share the element of urgency. Technologies which reliably accelerate product development rates can expect favorable reception by commercial seed developers. A growth chamber which dramatically accelerates the rate of plant growth is described.

  11. Impaired lymphatic function accelerates cancer growth

    PubMed Central

    Steinskog, Eli Sihn Samdal; Sagstad, Solfrid Johanne; Wagner, Marek; Karlsen, Tine Veronica; Yang, Ning; Markhus, Carl Erik; Yndestad, Synnøve; Wiig, Helge; Eikesdal, Hans Petter

    2016-01-01

    Increased lymphangiogenesis is a common feature of cancer development and progression, yet the influence of impaired lymphangiogenesis on tumor growth is elusive. C3HBA breast cancer and KHT-1 sarcoma cell lines were implanted orthotopically in Chy mice, harboring a heterozygous inactivating mutation of vascular endothelial growth factor receptor-3, resulting in impaired dermal lymphangiogenesis. Accelerated tumor growth was observed in both cancer models in Chy mice, coinciding with reduced peritumoral lymphangiogenesis. An impaired lymphatic washout was observed from the peritumoral area in Chy mice with C3HBA tumors, and the number of macrophages was significantly reduced. While fewer macrophages were detected, the fraction of CD163+ M2 macrophages remained constant, causing a shift towards a higher M2/M1 ratio in Chy mice. No difference in adaptive immune cells was observed between wt and Chy mice. Interestingly, levels of pro- and anti-inflammatory macrophage-associated cytokines were reduced in C3HBA tumors, pointing to an impaired innate immune response. However, IL-6 was profoundly elevated in the C3HBA tumor interstitial fluid, and treatment with the anti-IL-6 receptor antibody tocilizumab inhibited breast cancer growth. Collectively, our data indicate that impaired lymphangiogenesis weakens anti-tumor immunity and favors tumor growth at an early stage of cancer development. PMID:27329584

  12. The accelerating growth of online tagging systems

    NASA Astrophysics Data System (ADS)

    Wu, L. F.

    2011-09-01

    Research on the growth of online tagging systems not only is interesting in its own right, but also yields insights for website management and semantic web analysis. Traditional models that describing the growth of online systems can be divided between linear and nonlinear versions. Linear models, including the BA model [A.L. Barabasi, R. Albert, Science 286, 509 (1999)], assume that the average activity of users is a constant independent of population. Hence the total activity is a linear function of population. On the contrary, nonlinear models suggest that the average activity is affected by the size of the population and the total activity is a nonlinear function of population. In the current study, supporting evidences for the nonlinear growth assumption are obtained from data on Internet users' tagging behavior. A power law relationship between the number of new tags (F) and the population (P), which can be expressed as F~Pγ (γ > 1), is found. I call this pattern accelerating growth and find it relates the to time-invariant heterogeneity in individual activities. I also show how a greater heterogeneity leads to a faster growth.

  13. Accelerated Near-Threshold Fatigue Crack Growth Behavior of an Aluminum Powder Metallurgy Alloy

    NASA Technical Reports Server (NTRS)

    Piascik, Robert S.; Newman, John A.

    2002-01-01

    Fatigue crack growth (FCG) research conducted in the near threshold regime has identified a room temperature creep crack growth damage mechanism for a fine grain powder metallurgy (PM) aluminum alloy (8009). At very low DK, an abrupt acceleration in room temperature FCG rate occurs at high stress ratio (R = Kmin/Kmax). The near threshold accelerated FCG rates are exacerbated by increased levels of Kmax (Kmax less than 0.4 KIC). Detailed fractographic analysis correlates accelerated FCG with the formation of crack-tip process zone micro-void damage. Experimental results show that the near threshold and Kmax influenced accelerated crack growth is time and temperature dependent.

  14. Rotary plant growth accelerating apparatus. [weightlessness

    NASA Technical Reports Server (NTRS)

    Dedolph, R. D. (Inventor)

    1975-01-01

    Rotary plant growth accelerating apparatus for increasing plant yields by effectively removing the growing plants from the constraints of gravity and increasing the plant yield per unit of space is described. The apparatus is comprised of cylindrical plant beds supported radially removed from a primary axis of rotation, with each plant bed being driven about its own secondary axis of rotation and simultaneously moved in a planetary path about the primary axis of rotation. Each plant bed is formed by an apertured outer cylinder, a perforated inner cylinder positioned coaxially, and rooting media disposed in the space between. A rotatable manifold distributes liquid nutrients and water to the rooting media through the perforations in the inner cylinders as the plant beds are continuously rotated by suitable drive means.

  15. Growth rate for blackhole instabilities

    NASA Astrophysics Data System (ADS)

    Prabhu, Kartik; Wald, Robert

    2015-04-01

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

  16. Preloading To Accelerate Slow-Crack-Growth Testing

    NASA Technical Reports Server (NTRS)

    Gyekenyesi, John P.; Choi, Sung R.; Pawlik, Ralph J.

    2004-01-01

    An accelerated-testing methodology has been developed for measuring the slow-crack-growth (SCG) behavior of brittle materials. Like the prior methodology, the accelerated-testing methodology involves dynamic fatigue ( constant stress-rate) testing, in which a load or a displacement is applied to a specimen at a constant rate. SCG parameters or life prediction parameters needed for designing components made of the same material as that of the specimen are calculated from the relationship between (1) the strength of the material as measured in the test and (2) the applied stress rate used in the test. Despite its simplicity and convenience, dynamic fatigue testing as practiced heretofore has one major drawback: it is extremely time-consuming, especially at low stress rates. The present accelerated methodology reduces the time needed to test a specimen at a given rate of applied load, stress, or displacement. Instead of starting the test from zero applied load or displacement as in the prior methodology, one preloads the specimen and increases the applied load at the specified rate (see Figure 1). One might expect the preload to alter the results of the test and indeed it does, but fortunately, it is possible to account for the effect of the preload in interpreting the results. The accounting is done by calculating the normalized strength (defined as the strength in the presence of preload the strength in the absence of preload) as a function of (1) the preloading factor (defined as the preload stress the strength in the absence of preload) and (2) a SCG parameter, denoted n, that is used in a power-law crack-speed formulation. Figure 2 presents numerical results from this theoretical calculation.

  17. A Longitudinal Assessment of Early Acceleration of Students in Mathematics on Growth in Mathematics Achievement

    ERIC Educational Resources Information Center

    Ma, X.

    2005-01-01

    Early acceleration of students in mathematics (in the form of early access to formal abstract algebra) has been a controversial educational issue. The current study examined the rate of growth in mathematics achievement of accelerated gifted, honors, and regular students across the entire secondary years (Grades 7-12), in comparison to their…

  18. Stability of growth rate of sodium chlorate

    NASA Astrophysics Data System (ADS)

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

    2009-01-01

    The constancy of stabilized sodium chlorate crystal growth rate is investigated. After the growth rate stabilization, solution supersaturation was altered and then the initial one was restored, which resulted in fast restoring of the growth rate existing prior to the supersaturation change. It is thereby shown that stabilized growth rate is indeed very stable. The majority of crystals decrease the growth rates during the 3-4 growth hours, even if the process develops at the constant experimental conditions all the time. The new crystals introduced into the cell, continue to grow as the already growing crystals, with higher initial growth rates.

  19. Effects of acceleration rate on Rayleigh-Taylor instability in elastic-plastic materials

    NASA Astrophysics Data System (ADS)

    Banerjee, Arindam; Polavarapu, Rinosh

    2016-11-01

    The effect of acceleration rate in the elastic-plastic transition stage of Rayleigh-Taylor instability in an accelerated non-Newtonian material is investigated experimentally using a rotating wheel experiment. A non-Newtonian material (mayonnaise) was accelerated at different rates by varying the angular acceleration of a rotating wheel and growth patterns of single mode perturbations with different combinations of amplitude and wavelength were analyzed. Experiments were run at two different acceleration rates to compare with experiments presented in prior years at APS DFD meetings and the peak amplitude responses are captured using a high-speed camera. Similar to the instability acceleration, the elastic-plastic transition acceleration is found to be increasing with increase in acceleration rate for a given amplitude and wavelength. The experimental results will be compared to various analytical strength models and prior experimental studies using Newtonian fluids. Authors acknowledge funding support from Los Alamos National Lab subcontract(370333) and DOE-SSAA Grant (DE-NA0001975).

  20. Modeling Reliability Growth in Accelerated Stress Testing

    DTIC Science & Technology

    2013-12-01

    HASS and HASA Explained, Milwaukee, WI: Quality Press, 2009. [13] A. J. Porter, "Failure Mode Verification: Applying Highly Accelerated Life Testing...and Production Conference - Proceedings of the Technical Program, Des Plaines, IL, 1998. [16] M. Silverman, "Summary of HALT and HASS results at

  1. Accelerated Threshold Fatigue Crack Growth Effect-Powder Metallurgy Aluminum Alloy

    NASA Technical Reports Server (NTRS)

    Piascik, R. S.; Newman, J. A.

    2002-01-01

    Fatigue crack growth (FCG) research conducted in the near threshold regime has identified a room temperature creep crack growth damage mechanism for a fine grain powder metallurgy (PM) aluminum alloy (8009). At very low (Delta) K, an abrupt acceleration in room temperature FCG rate occurs at high stress ratio (R = K(sub min)/K(sub max)). The near threshold accelerated FCG rates are exacerbated by increased levels of K(sub max) (K(sub max) = 0.4 K(sub IC)). Detailed fractographic analysis correlates accelerated FCG with the formation of crack-tip process zone micro-void damage. Experimental results show that the near threshold and K(sub max) influenced accelerated crack growth is time and temperature dependent.

  2. Accelerated growth of calcium silicate hydrates: Experiments and simulations

    SciTech Connect

    Nicoleau, Luc

    2011-12-15

    Despite the usefulness of isothermal calorimetry in cement analytics, without any further computations this brings only little information on the nucleation and growth of hydrates. A model originally developed by Garrault et al. is used in this study in order to simulate hydration curves of cement obtained by calorimetry with different known hardening accelerators. The limited basis set of parameters used in this model, having a physical or chemical significance, is valuable for a better understanding of mechanisms underlying in the acceleration of C-S-H precipitation. Alite hydration in presence of four different types of hardening accelerators was investigated. It is evidenced that each accelerator type plays a specific role on one or several growth parameters and that the model may support the development of new accelerators. Those simulations supported by experimental observations enable us to follow the formation of the C-S-H layer around grains and to extract interesting information on its apparent permeability.

  3. Crack growth in Ti-8Al-1Mo-1V with real-time and accelerated flight by flight loading

    NASA Technical Reports Server (NTRS)

    Imig, L. A.

    1975-01-01

    Crack growth in Ti-8Al-lMo-lV was measured and calculated for real time and accelerated simulations of supersonic airplane loading and heating. Crack-growth rates calculated on the assumption that an entire flight could be represented by a single cycle predicted the experimental rates poorly. Calculated crack growth rates were slower than the experimental rates for all tests with flight-by-flight loading. For room temperature accelerated tests, the calculated rates agreed well with the experimental rates; but the calculations became progressively less accurate for progressively more complex test conditions (tests that included elevated temperature).

  4. A count rate based contamination control standard for electron accelerators

    SciTech Connect

    May, R.T.; Schwahn, S.O.

    1996-12-31

    Accelerators of sufficient energy and particle fluence can produce radioactivity as an unwanted byproduct. The radioactivity is typically imbedded in structural materials but may also be removable from surfaces. Many of these radionuclides decay by positron emission or electron capture; they often have long half lives and produce photons of low energy and yield making detection by standard devices difficult. The contamination control limit used throughout the US nuclear industry and the Department of Energy is 1,000 disintegrations per minute. This limit is based on the detection threshold of pancake type Geiger-Mueller probes for radionuclides of relatively high radiotoxicity, such as cobalt-60. Several radionuclides of concern at a high energy electron accelerator are compared in terms of radiotoxicity with radionuclides commonly found in the nuclear industry. Based on this comparison, a count-rate based contamination control limit and associated measurement strategy is proposed which provides adequate detection of contamination at accelerators without an increase in risk.

  5. Accelerating degradation rate of pure iron by zinc ion implantation

    PubMed Central

    Huang, Tao; Zheng, Yufeng; Han, Yong

    2016-01-01

    Pure iron has been considered as a promising candidate for biodegradable implant applications. However, a faster degradation rate of pure iron is needed to meet the clinical requirement. In this work, metal vapor vacuum arc technology was adopted to implant zinc ions into the surface of pure iron. Results showed that the implantation depth of zinc ions was about 60 nm. The degradation rate of pure iron was found to be accelerated after zinc ion implantation. The cytotoxicity tests revealed that the implanted zinc ions brought a slight increase on cytotoxicity of the tested cells. In terms of hemocompatibility, the hemolysis of zinc ion implanted pure iron was lower than 2%. However, zinc ions might induce more adhered and activated platelets on the surface of pure iron. Overall, zinc ion implantation can be a feasible way to accelerate the degradation rate of pure iron for biodegradable applications. PMID:27482462

  6. Accelerating degradation rate of pure iron by zinc ion implantation.

    PubMed

    Huang, Tao; Zheng, Yufeng; Han, Yong

    2016-12-01

    Pure iron has been considered as a promising candidate for biodegradable implant applications. However, a faster degradation rate of pure iron is needed to meet the clinical requirement. In this work, metal vapor vacuum arc technology was adopted to implant zinc ions into the surface of pure iron. Results showed that the implantation depth of zinc ions was about 60 nm. The degradation rate of pure iron was found to be accelerated after zinc ion implantation. The cytotoxicity tests revealed that the implanted zinc ions brought a slight increase on cytotoxicity of the tested cells. In terms of hemocompatibility, the hemolysis of zinc ion implanted pure iron was lower than 2%. However, zinc ions might induce more adhered and activated platelets on the surface of pure iron. Overall, zinc ion implantation can be a feasible way to accelerate the degradation rate of pure iron for biodegradable applications.

  7. Acceleration of hippocampal atrophy rates in asymptomatic amyloidosis.

    PubMed

    Andrews, K Abigail; Frost, Chris; Modat, Marc; Cardoso, M Jorge; Rowe, Chris C; Villemagne, Victor; Fox, Nick C; Ourselin, Sebastien; Schott, Jonathan M

    2016-03-01

    Increased rates of brain atrophy measured from serial magnetic resonance imaging precede symptom onset in Alzheimer's disease and may be useful outcome measures for prodromal clinical trials. Appropriate trial design requires a detailed understanding of the relationships between β-amyloid load and accumulation, and rate of brain change at this stage of the disease. Fifty-two healthy individuals (72.3 ± 6.9 years) from Australian Imaging, Biomarkers and Lifestyle Study of Aging had serial (0, 18 m, 36 m) magnetic resonance imaging, (0, 18 m) Pittsburgh compound B positron emission tomography, and clinical assessments. We calculated rates of whole brain and hippocampal atrophy, ventricular enlargement, amyloid accumulation, and cognitive decline. Over 3 years, rates of whole brain atrophy (p < 0.001), left and right hippocampal atrophy (p = 0.001, p = 0.023), and ventricular expansion (p < 0.001) were associated with baseline β-amyloid load. Whole brain atrophy rates were also independently associated with β-amyloid accumulation over the first 18 months (p = 0.003). Acceleration of left hippocampal atrophy rate was associated with baseline β-amyloid load across the cohort (p < 0.02). We provide evidence that rates of atrophy are associated with both baseline β-amyloid load and accumulation, and that there is presymptomatic, amyloid-mediated acceleration of hippocampal atrophy. Clinical trials using rate of hippocampal atrophy as an outcome measure should not assume linear decline in the presymptomatic phase.

  8. Crystal growth of energetic materials during high acceleration

    SciTech Connect

    Lanzerotti, M.Y.D.; Autera, J.; Borne, L.; Sharma, J.

    1996-07-01

    Studies of the growth of crystals of energetic materials under conditions of high acceleration in an ultracentrifuge are reported. When a saturated solution is accelerated in an ultracentrifuge, the solute molecules move individually through the solvent molecules to form a crystal at the outer edge of the tube if the solute is more dense than the solvent. Since there is no evaporation or temperature variation, convection currents caused by simultaneous movement of solvent and solute are minimized and crystal defects are potentially minimized. Crystal growth is controlled by the g-level of the acceleration. In addition, solution inclusions and bubbles migrate out of the saturated solution as a result of the pressure gradient induced by the g-force. The authors present results of TNT, RDX, and TNAZ grown at high g from various solutions.

  9. National health expenditure projections: modest annual growth until coverage expands and economic growth accelerates.

    PubMed

    Keehan, Sean P; Cuckler, Gigi A; Sisko, Andrea M; Madison, Andrew J; Smith, Sheila D; Lizonitz, Joseph M; Poisal, John A; Wolfe, Christian J

    2012-07-01

    For 2011-13, US health spending is projected to grow at 4.0 percent, on average--slightly above the historically low growth rate of 3.8 percent in 2009. Preliminary data suggest that growth in consumers' use of health services remained slow in 2011, and this pattern is expected to continue this year and next. In 2014, health spending growth is expected to accelerate to 7.4 percent as the major coverage expansions from the Affordable Care Act begin. For 2011 through 2021, national health spending is projected to grow at an average rate of 5.7 percent annually, which would be 0.9 percentage point faster than the expected annual increase in the gross domestic product during this period. By 2021, federal, state, and local government health care spending is projected to be nearly 50 percent of national health expenditures, up from 46 percent in 2011, with federal spending accounting for about two-thirds of the total government share. Rising government spending on health care is expected to be driven by faster growth in Medicare enrollment, expanded Medicaid coverage, and the introduction of premium and cost-sharing subsidies for health insurance exchange plans.

  10. Flux Rope Acceleration and Enhanced Magnetic Reconnection Rate

    SciTech Connect

    C.Z. Cheng; Y. Ren; G.S. Choe; Y.-J. Moon

    2003-03-25

    A physical mechanism of flares, in particular for the flare rise phase, has emerged from our 2-1/2-dimensional resistive MHD simulations. The dynamical evolution of current-sheet formation and magnetic reconnection and flux-rope acceleration subject to continuous, slow increase of magnetic shear in the arcade are studied by employing a non-uniform anomalous resistivity in the reconnecting current sheet under gravity. The simulation results directly relate the flux rope's accelerated rising motion with an enhanced magnetic reconnection rate and thus an enhanced reconnection electric field in the current sheet during the flare rise phase. The simulation results provide good quantitative agreements with observations of the acceleration of flux rope, which manifests in the form of SXR ejecta or erupting filament or CMEs, in the low corona. Moreover, for the X-class flare events studied in this paper the peak reconnection electric field is about O(10{sup 2} V/m) or larger, enough to accelerate p articles to over 100 keV in a field-aligned distance of 10 km. Nonthermal electrons thus generated can produce hard X-rays, consistent with impulsive HXR emission observed during the flare rise phase.

  11. Measurements of Protein Crystal Face Growth Rates

    NASA Technical Reports Server (NTRS)

    Gorti, S.

    2014-01-01

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

  12. Growth Rates of Microbes in the Oceans

    NASA Astrophysics Data System (ADS)

    Kirchman, David L.

    2016-01-01

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

  13. Growth Rates of Microbes in the Oceans.

    PubMed

    Kirchman, David L

    2016-01-01

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

  14. Temperature influence on phytoplankton community growth rates

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  15. Emittance growth mechanisms for laser-accelerated proton beams.

    PubMed

    Kemp, Andreas J; Fuchs, J; Sentoku, Y; Sotnikov, V; Bakeman, M; Antici, P; Cowan, T E

    2007-05-01

    In recent experiments the transverse normalized rms emittance of laser-accelerated MeV ion beams was found to be < 0.002 mm mrad, which is at least 100 times smaller than the emittance of thermal ion sources used in accelerators [T. E. Cowan, Phys. Rev. Lett. 92, 204801 (2004)]. We investigate the origin for the low emittance of laser-accelerated proton beams by studying several candidates for emittance-growth mechanisms. As our main tools, we use analytical models and one- and two-dimensional particle-in-cell simulations that have been modified to include binary collisions between particles. We find that the dominant source of emittance is filamentation of the laser-generated hot electron jets that drive the ion acceleration. Cold electron-ion collisions that occur before ions are accelerated contribute less than ten percent of the final emittance. Our results are in qualitative agreement with the experiment, for which we present a refined analysis relating emittance to temperature, a better representative of the fundamental beam physics.

  16. Population growth rates: issues and an application.

    PubMed Central

    Godfray, H Charles J; Rees, Mark

    2002-01-01

    Current issues in population dynamics are discussed in the context of The Royal Society Discussion Meeting 'Population growth rate: determining factors and role in population regulation'. In particular, different views on the centrality of population growth rates to the study of population dynamics and the role of experiments and theory are explored. Major themes emerging include the role of modern statistical techniques in bringing together experimental and theoretical studies, the importance of long-term experimentation and the need for ecology to have model systems, and the value of population growth rate as a means of understanding and predicting population change. The last point is illustrated by the application of a recently introduced technique, integral projection modelling, to study the population growth rate of a monocarpic perennial plant, its elasticities to different life-history components and the evolution of an evolutionarily stable strategy size at flowering. PMID:12396521

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

    PubMed

    Demetrius, L

    1989-04-01

    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 the notion of environmental intensity. The intensity function, expressed in terms of the entropy parameters, is applied to give a comparative study of the effect of environmental factors on the dynamics of Swedish and French populations.

  18. Drift mode growth rates and associated transport

    SciTech Connect

    Redd, A.J.; Kritz, A.H.; Bateman, G.; Rewoldt, G.; Tang, W.M.

    1999-04-01

    Drift mode linear growth rates and quasilinear transport are investigated using the FULL kinetic stability code [Rewoldt {ital et al.}, Phys. Plasmas {bold 5}, 1815 (1998)] and a version of the Weiland transport model [Strand {ital et al.}, Nucl. Fusion {bold 38}, 545 (1998)]. It is shown that the drift mode growth rates (as well as the marginal stability temperature gradient) obtained using the FULL code are dependent on the accuracy of the equilibrium employed. In particular, when an approximate equilibrium model is utilized by the FULL code, the results can differ significantly from those obtained using a more accurate numerical equilibrium. Also investigated are the effects of including full electron physics. It is shown, using both the FULL code and the Weiland model, that the nonadiabatic (e.g., trapped) electron response produces a significant increase in the linear growth rate of the ion-temperature-gradient (ITG) driven branch of the drift instability. Other consequences of the nonadiabatic electron response include a reduction in the marginal temperature gradient for the onset of the ITG mode and an additional contribution to transport due to the excitation of the Trapped Electron Mode (TEM). Physical explanations are given for the sensitivity of the mode growth rates to the equilibrium and the nonadiabatic electron response. Finally, linear growth rates for the ITG mode computed using the FULL code are compared with growth rates obtained using the Weiland model. {copyright} {ital 1999 American Institute of Physics.}

  19. On growth rate hysteresis and catastrophic crystal growth

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  20. Ultraslow growth rates of giant gypsum crystals

    PubMed Central

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

    2011-01-01

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

  1. Ultraslow growth rates of giant gypsum crystals.

    PubMed

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

    2011-09-20

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

  2. Two-tank suspended growth process for accelerating the detoxification kinetics of hydrocarbons requiring initial monooxygenation reactions.

    PubMed

    Dahlen, Elizabeth P; Rittmann, Bruce E

    2002-01-01

    An experimental evaluation demonstrated that suspended growth systems operated in a two-tank accelerator/aerator configuration significantly increased the overall removal rates for phenol and 2,4-dichlorophenol (2,4-DCP), aromatic hydrocarbons that require initial monooxygenations. The accelerator tank is a small volume that receives the influent and recycled biomass. It has a high ratio of electron donor (BOD) to electron acceptor (O2). Biomass in the accelerator should be enriched in reduced nicotinamide adenine dinucleotide (NADH + H+) and have a very high specific growth rate, conditions that should accelerate the kinetics of monooxygenation reactions. For the more slowly degraded 2,4-DCP, the average percentage removal increased from 74% to 93%, even though the volume of the two-tank system was smaller than that of the one-tank system in most experiments. The average volumetric and biomass-specific removal rates increased by 50% and 100%, respectively, in the two-tank system, compared to a one-tank system. The greatest enhancement in 2,4-DCP removal occurred when the accelerator tank comprised approximately 20% of the system volume. Biomass in the accelerator tank was significantly enriched in NADH + H+ when its dissolved oxygen (DO) concentration was below 0.25 mg/L, a situation having a high ratio of donor to acceptor. The accelerator biomass had its highest NADH + H+ content for the experiments that had the highest rate of 2,4-DCP removal. Biomass in the accelerator also had a much higher specific growth rate than in the aerator or the system overall, and the specific growth rate in the accelerator was inversely correlated to the accelerator volume.

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

    PubMed Central

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

    2016-01-01

    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. PMID:27941811

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Maximizing oyster-reef growth supports green infrastructure with accelerating sea-level rise

    PubMed Central

    Ridge, Justin T.; Rodriguez, Antonio B.; Joel Fodrie, F.; Lindquist, Niels L.; Brodeur, Michelle C.; Coleman, Sara E.; Grabowski, Jonathan H.; Theuerkauf, Ethan J.

    2015-01-01

    Within intertidal communities, aerial exposure (emergence during the tidal cycle) generates strong vertical zonation patterns with distinct growth boundaries regulated by physiological and external stressors. Forecasted accelerations in sea-level rise (SLR) will shift the position of these critical boundaries in ways we cannot yet fully predict, but landward migration will be impaired by coastal development, amplifying the importance of foundation species’ ability to maintain their position relative to rising sea levels via vertical growth. Here we show the effects of emergence on vertical oyster-reef growth by determining the conditions at which intertidal reefs thrive and the sharp boundaries where reefs fail, which shift with changes in sea level. We found that oyster reef growth is unimodal relative to emergence, with greatest growth rates occurring between 20–40% exposure, and zero-growth boundaries at 10% and 55% exposures. Notably, along the lower growth boundary (10%), increased rates of SLR would outpace reef accretion, thereby reducing the depth range of substrate suitable for reef maintenance and formation, and exacerbating habitat loss along developed shorelines. Our results identify where, within intertidal areas, constructed or natural oyster reefs will persist and function best as green infrastructure to enhance coastal resiliency under conditions of accelerating SLR. PMID:26442712

  6. Maximizing oyster-reef growth supports green infrastructure with accelerating sea-level rise.

    PubMed

    Ridge, Justin T; Rodriguez, Antonio B; Joel Fodrie, F; Lindquist, Niels L; Brodeur, Michelle C; Coleman, Sara E; Grabowski, Jonathan H; Theuerkauf, Ethan J

    2015-10-07

    Within intertidal communities, aerial exposure (emergence during the tidal cycle) generates strong vertical zonation patterns with distinct growth boundaries regulated by physiological and external stressors. Forecasted accelerations in sea-level rise (SLR) will shift the position of these critical boundaries in ways we cannot yet fully predict, but landward migration will be impaired by coastal development, amplifying the importance of foundation species' ability to maintain their position relative to rising sea levels via vertical growth. Here we show the effects of emergence on vertical oyster-reef growth by determining the conditions at which intertidal reefs thrive and the sharp boundaries where reefs fail, which shift with changes in sea level. We found that oyster reef growth is unimodal relative to emergence, with greatest growth rates occurring between 20-40% exposure, and zero-growth boundaries at 10% and 55% exposures. Notably, along the lower growth boundary (10%), increased rates of SLR would outpace reef accretion, thereby reducing the depth range of substrate suitable for reef maintenance and formation, and exacerbating habitat loss along developed shorelines. Our results identify where, within intertidal areas, constructed or natural oyster reefs will persist and function best as green infrastructure to enhance coastal resiliency under conditions of accelerating SLR.

  7. Hydrogen accelerated fatigue crack growth of friction stir welded X52 steel pipe

    DOE PAGES

    Ronevich, Joseph Allen; Somerday, Brian P.; Feng, Zhili

    2016-11-17

    Friction stir welded steel pipelines were tested in high pressure hydrogen gas to examine the effects of hydrogen accelerated fatigue crack growth. Fatigue crack growth rate (da/dN) vs. stress-intensity factor range (ΔK) relationships were measured for an X52 friction stir welded pipe tested in 21 MPa hydrogen gas at a frequency of 1 Hz and R = 0.5. Tests were performed on three regions: base metal (BM), center of friction stir weld (FSW), and 15 mm off-center of the weld. For all three material regions, tests in hydrogen exhibited accelerated fatigue crack growth rates that exceeded an order of magnitudemore » compared to companion tests in air. Among tests in hydrogen, fatigue crack growth rates were modestly higher in the FSW than the BM and 15 mm off-center tests. Select regions of the fracture surfaces associated with specified ΔK levels were examined which revealed intergranular fracture in the BM and 15 mm off-center specimens but an absence of intergranular features in the FSW specimens. In conclusion, the X52 friction stir weld and base metal tested in hydrogen exhibited fatigue crack growth rate relationships that are comparable to those for conventional arc welded steel pipeline of similar strength found in the literature.« less

  8. Hydrogen accelerated fatigue crack growth of friction stir welded X52 steel pipe

    SciTech Connect

    Ronevich, Joseph Allen; Somerday, Brian P.; Feng, Zhili

    2016-11-17

    Friction stir welded steel pipelines were tested in high pressure hydrogen gas to examine the effects of hydrogen accelerated fatigue crack growth. Fatigue crack growth rate (da/dN) vs. stress-intensity factor range (ΔK) relationships were measured for an X52 friction stir welded pipe tested in 21 MPa hydrogen gas at a frequency of 1 Hz and R = 0.5. Tests were performed on three regions: base metal (BM), center of friction stir weld (FSW), and 15 mm off-center of the weld. For all three material regions, tests in hydrogen exhibited accelerated fatigue crack growth rates that exceeded an order of magnitude compared to companion tests in air. Among tests in hydrogen, fatigue crack growth rates were modestly higher in the FSW than the BM and 15 mm off-center tests. Select regions of the fracture surfaces associated with specified ΔK levels were examined which revealed intergranular fracture in the BM and 15 mm off-center specimens but an absence of intergranular features in the FSW specimens. In conclusion, the X52 friction stir weld and base metal tested in hydrogen exhibited fatigue crack growth rate relationships that are comparable to those for conventional arc welded steel pipeline of similar strength found in the literature.

  9. SpS5: Accelerating the Rate of Astronomical Discovery

    NASA Astrophysics Data System (ADS)

    Norris, Ray P.

    2010-11-01

    Special Session 5 on Accelerating the Rate of Astronomical Discovery addressed a range of potential limits to progress: paradigmatic, technological, organizational, and political. It examined each issue both from modern and historical perspectives, and drew lessons to guide future progress. A number of issues were identified which may regulate the flow of discoveries, such as the balance between large strongly-focussed projects and instruments, designed to answer the most fundamental questions confronting us, and the need to maintain a creative environment with room for unorthodox thinkers and bold, high risk, projects. Also important is the need to maintain historical and cultural perspectives, and the need to engage the minds of the most brilliant young people on the planet, regardless of their background, ethnicity, gender, or geography.

  10. Learning improves growth rate in grasshoppers.

    PubMed

    Dukas, R; Bernays, E A

    2000-03-14

    To quantify the adaptive significance of insect learning, we documented the behavior and growth rate of grasshoppers (Schistocerca americana) in an environment containing two artificial food types, one providing a balanced diet of protein and carbohydrate, which maximizes growth, and the other being carbohydrate-deficient, which is unsuitable for growth. Grasshoppers in the Learning treatment experienced a predictable environment, where the spatial location, taste, and color of each food source remained constant throughout the experiment. In contrast, grasshoppers of the Random treatment developed in a temporally varying environment, where the spatial location, taste, and color of the balanced and deficient food types randomly alternated twice each day. Our results show that the grasshoppers that could employ associative learning for diet choice experienced higher growth rates than individuals of the Random treatment, demonstrating the adaptive significance of learning in a small short-lived insect.

  11. GPU accelerated processing of astronomical high frame-rate videosequences

    NASA Astrophysics Data System (ADS)

    Vítek, Stanislav; Švihlík, Jan; Krasula, Lukáš; Fliegel, Karel; Páta, Petr

    2015-09-01

    Astronomical instruments located around the world are producing an incredibly large amount of possibly interesting scientific data. Astronomical research is expanding into large and highly sensitive telescopes. Total volume of data rates per night of operations also increases with the quality and resolution of state-of-the-art CCD/CMOS detectors. Since many of the ground-based astronomical experiments are placed in remote locations with limited access to the Internet, it is necessary to solve the problem of the data storage. It mostly means that current data acquistion, processing and analyses algorithm require review. Decision about importance of the data has to be taken in very short time. This work deals with GPU accelerated processing of high frame-rate astronomical video-sequences, mostly originating from experiment MAIA (Meteor Automatic Imager and Analyser), an instrument primarily focused to observing of faint meteoric events with a high time resolution. The instrument with price bellow 2000 euro consists of image intensifier and gigabite ethernet camera running at 61 fps. With resolution better than VGA the system produces up to 2TB of scientifically valuable video data per night. Main goal of the paper is not to optimize any GPU algorithm, but to propose and evaluate parallel GPU algorithms able to process huge amount of video-sequences in order to delete all uninteresting data.

  12. Revisiting the Estimation of Dinosaur Growth Rates

    PubMed Central

    Myhrvold, Nathan P.

    2013-01-01

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

  13. Enteric bacterial growth rates in river water.

    PubMed

    Hendricks, C W

    1972-08-01

    Enteric bacteria, including stocked strains of pathogenic species and organisms naturally present in the stream, were capable of growth in a chemostat with autoclaved river water taken 750 m below a sewage outfall. Maximal specific growth rates for all organisms occurred at 30 C, whereas culture generation times ranged between 33.3 and 116 hr. Of the six laboratory strains of enteric species used, Escherichia coli and Enterobacter aerogenes grew at generation times of 34.5 and 33.3 hr, respectively, while the remaining Proteus, Arizona, Salmonella, and Shigella spp. reproduced at a rate two to three times slower than the coliforms. Little or no growth occurred in the water at incubation temperatures of 20 and 5 C, and death was observed for Salmonella senftenberg at 20 and 5 C and for E. aerogenes and Proteus rettgeri at 5 C. When enteric bacteria naturally present in the river water were employed in similar experiments, coliform bacteria demonstrated a generation time of approximately 116 hr, whereas fecal coliforms failed to grow. Growth of the bacteria from the river demonstrated a periodicity of approximately 100 hr, which suggests that much of the growth of these organisms in the chemostat may be on the glass surfaces. This phenomenon, however, was not observed with any of the stocked enteric species. Neither the stock cultures nor the aquatic strains were capable of growth in autoclaved river water taken above the sewage outfall at the three temperatures tested.

  14. Safety Evaluation of Transgenic Tilapia with Accelerated Growth.

    PubMed

    Guillén; Berlanga; Valenzuela; Morales; Toledo; Estrada; Puentes; Hayes; de la Fuente J

    1999-01-01

    Recent advances in modern marine biotechnology have permitted the generation of new strains of economically important fish species through the transfer of growth hormone genes. These transgenic fish strains show improved growth performance and therefore constitute a better alternative for aquaculture programs. Recently, we have obtained a transgenic tilapia line with accelerated growth. However, before introducing this line into Cuban aquaculture, environmental and food safety assessment was required by national authorities. Experiments were performed to evaluate the behavior of transgenic tilapia in comparison to wild tilapia as a way to assess the environmental impact of introducing transgenic tilapia into Cuban aquaculture. Studies were also conducted to evaluate, according to the principle of substantial equivalence, the safety of consuming transgenic tilapia as food. Behavior studies showed that transgenic tilapia had a lower feeding motivation and dominance status than controls. Food safety assessment indicated that tilapia growth hormone has no biological activity when administered to nonhuman primates. Furthermore, no effects were detected in human healthy volunteers after the consumption of transgenic tilapia. These results showed, at least under the conditions found in Cuba, no environmental implications for the introduction of this transgenic tilapia line and the safety in the consumption of tiGH-transgenic tilapia as an alternative feeding source for humans. These results support the culture and consumption of these transgenic tilapia.

  15. Antisomatostatin-induced growth acceleration in chinook salmon (Oncorhynchus tshawytscha).

    PubMed

    Mayer, I; McLean, E; Kieffer, T J; Souza, L M; Donaldson, E M

    1994-10-01

    Since somatostatin (SRIF) inhibits the release of growth hormone (GH), its immunoneutralization may provide an alternative to GH therapy as a means of enhancing somatic growth in fish. The present study examined the feasibility of accelerating growth in juvenile chinook salmon by means of antiSRIF administration. Yearling salmon of Nicola River stock (BC, Canada) were injected intraperitoneally every 5 days, for a total of 40 days, with either SRIF (1 μg g-1 body wt.), antiSRIF (SOMA-10, 1 μg g(-1)), recombinant bovine GH (rbGH, 2.5 μg g(-1)), recombinant porcine GH (rpGH, 2.5 μg g(-1)) or saline (controls). No significant differences were observed in length, weight or final condition factor (k) between the SRIF-treated and control fish over the experimental period. However, the fish treated with the antiSRIF were significantly (p ≤ 0.05) longer and heavier than the control salmon after 25 and 30 days respectively. Furthermore, antiSRIF treatment caused a lowering in k when compared to the control salmon. Fish injected with rbGH or rpGH were significantly longer and heavier than all other groups (p ≤ 0.05), after only 5 days. GH treated groups also returned higher k when compared against all other treatments (p ≤ 0.05). No differences were observed in growth between the two rGH treatments over the experimental period.

  16. DnaK-Dependent Accelerated Evolutionary Rate in Prokaryotes

    PubMed Central

    Kadibalban, A. Samer; Bogumil, David; Landan, Giddy; Dagan, Tal

    2016-01-01

    Many proteins depend on an interaction with molecular chaperones in order to fold into a functional tertiary structure. Previous studies showed that protein interaction with the GroEL/GroES chaperonine and Hsp90 chaperone can buffer the impact of slightly deleterious mutations in the protein sequence. This capacity of GroEL/GroES to prevent protein misfolding has been shown to accelerate the evolution of its client proteins. Whether other bacterial chaperones have a similar effect on their client proteins is currently unknown. Here, we study the impact of DnaK (Hsp70) chaperone on the evolution of its client proteins. Evolutionary parameters were derived from comparison of the Escherichia coli proteome to 1,808,565 orthologous proteins in 1,149 proteobacterial genomes. Our analysis reveals a significant positive correlation between protein binding frequency with DnaK and evolutionary rate. Proteins with high binding affinity to DnaK evolve on average 4.3-fold faster than proteins in the lowest binding affinity class at the genus resolution. Differences in evolutionary rates of DnaK interactor classes are still significant after adjusting for possible effects caused by protein expression level. Furthermore, we observe an additive effect of DnaK and GroEL chaperones on the evolutionary rates of their common interactors. Finally, we found pronounced similarities in the physicochemical profiles that characterize proteins belonging to DnaK and GroEL interactomes. Our results thus implicate DnaK-mediated folding as a major component in shaping protein evolutionary dynamics in bacteria and supply further evidence for the long-term manifestation of chaperone-mediated folding on genome evolution. PMID:27189986

  17. Voltage stress effects on microcircuit accelerated life test failure rates

    NASA Technical Reports Server (NTRS)

    Johnson, G. M.

    1976-01-01

    The applicability of Arrhenius and Eyring reaction rate models for describing microcircuit aging characteristics as a function of junction temperature and applied voltage was evaluated. The results of a matrix of accelerated life tests with a single metal oxide semiconductor microcircuit operated at six different combinations of temperature and voltage were used to evaluate the models. A total of 450 devices from two different lots were tested at ambient temperatures between 200 C and 250 C and applied voltages between 5 Vdc and 15 Vdc. A statistical analysis of the surface related failure data resulted in bimodal failure distributions comprising two lognormal distributions; a 'freak' distribution observed early in time, and a 'main' distribution observed later in time. The Arrhenius model was shown to provide a good description of device aging as a function of temperature at a fixed voltage. The Eyring model also appeared to provide a reasonable description of main distribution device aging as a function of temperature and voltage. Circuit diagrams are shown.

  18. DCC functions as an accelerator of thalamocortical axonal growth downstream of spontaneous thalamic activity

    PubMed Central

    Castillo-Paterna, Mar; Moreno-Juan, Verónica; Filipchuk, Anton; Rodríguez-Malmierca, Luis; Susín, Rafael; López-Bendito, Guillermina

    2015-01-01

    Controlling the axon growth rate is fundamental when establishing brain connections. Using the thalamocortical system as a model, we previously showed that spontaneous calcium activity influences the growth rate of thalamocortical axons by regulating the transcription of Robo1 through an NF-κB-binding site in its promoter. Robo1 acts as a brake on the growth of thalamocortical axons in vivo. Here, we have identified the Netrin-1 receptor DCC as an accelerator for thalamic axon growth. Dcc transcription is regulated by spontaneous calcium activity in thalamocortical neurons and activating DCC signaling restores normal axon growth in electrically silenced neurons. Moreover, we identified an AP-1-binding site in the Dcc promoter that is crucial for the activity-dependent regulation of this gene. In summary, we have identified the Dcc gene as a novel downstream target of spontaneous calcium activity involved in axon growth. Together with our previous data, we demonstrate a mechanism to control axon growth that relies on the activity-dependent regulation of two functionally opposed receptors, Robo1 and DCC. These two proteins establish a tight and efficient means to regulate activity-guided axon growth in order to correctly establish neuronal connections during development. PMID:25947198

  19. Acceleration and localization of subcritical crack growth in a natural composite material

    NASA Astrophysics Data System (ADS)

    Lennartz-Sassinek, S.; Main, I. G.; Zaiser, M.; Graham, C. C.

    2014-11-01

    Catastrophic failure of natural and engineered materials is often preceded by an acceleration and localization of damage that can be observed indirectly from acoustic emissions (AE) generated by the nucleation and growth of microcracks. In this paper we present a detailed investigation of the statistical properties and spatiotemporal characteristics of AE signals generated during triaxial compression of a sandstone sample. We demonstrate that the AE event amplitudes and interevent times are characterized by scaling distributions with shapes that remain invariant during most of the loading sequence. Localization of the AE activity on an incipient fault plane is associated with growth in AE rate in the form of a time-reversed Omori law with an exponent near 1. The experimental findings are interpreted using a model that assumes scale-invariant growth of the dominating crack or fault zone, consistent with the Dugdale-Barenblatt "process zone" model. We determine formal relationships between fault size, fault growth rate, and AE event rate, which are found to be consistent with the experimental observations. From these relations, we conclude that relatively slow growth of a subcritical fault may be associated with a significantly more rapid increase of the AE rate and that monitoring AE rate may therefore provide more reliable predictors of incipient failure than direct monitoring of the growing fault.

  20. Growth rates of Chinese and American alligators.

    PubMed

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

    2002-04-01

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

  1. Polymorphic growth rates in myrmecophilous insects.

    PubMed

    Schönrogge, K; Wardlaw, J C; Thomas, J A; Elmes, G W

    2000-04-22

    A polymorphism in growth rates was recently described affecting the larval development of the myrmecophilous butterfly Maculinea rebeli, spanning different years in a single insect population. The close integration of M. rebeli into the host ant colonies, facilitated by adaptations in behaviour and chemical mimicry, make extended larval development a successful strategy. Here we present additional data for M. rebeli and new data for Maculinea alcon (another cuckoo-feeding lycaenid) and the two myrmecophilous predators Maculinea arion and Microdon mutabilis (Diptera: Syrphidae). As predicted, M. alcon shows the same growth pattern as M. rebeli with a proportion of caterpillars developing in one year and the remainder over two years. This pattern holds in both northern and southern European populations, where M. alcon exploits different species of host. Against expectation, the same bimodal distribution of pre-pupation body weights, indicating one and two year developers, was found for the larvae of M. arion and M. mutabilis. As predators, both species are less closely integrated in their host ant colonies, suggesting that the polymorphism in growth rates is a more general adaptation to a myrmecophilous life style, arrived at by convergent evolution between the Maculinea and Microdon species. For predatory species we suggest that biennialism is an adaptation to the migratory behaviour of the host made possible by the predators' ability to fast over extended periods. We also hypothesize that M. arion represents an ancestral strategy in Maculinea butterflies and that the growth polymorphism might have become genetically fixed in the cuckoo-feeding species.

  2. Controlling Growth Rates of Protein Samples

    NASA Technical Reports Server (NTRS)

    Herrmann, Frederick T.; Herren, Blair J.

    1987-01-01

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

  3. Growth axis maturation is linked to nutrition, growth and developmental rate.

    PubMed

    Hetz, Jennifer A; Menzies, Brandon R; Shaw, Geoffrey; Rao, Alexandra; Clarke, Iain J; Renfree, Marilyn B

    2015-08-15

    Maturation of the mammalian growth axis is thought to be linked to the transition from fetal to post-natal life at birth. However, in an altricial marsupial, the tammar wallaby (Macropus eugenii), this process occurs many months after birth but at a time when the young is at a similar developmental stage to that of neonatal eutherian mammals. Here we manipulate growth rates and demonstrate in slow, normal and fast growing tammar young that nutrition and growth rate affect the time of maturation of the growth axis. Maturation of GH/IGF-I axis components occurred earlier in fast growing young, which had significantly increased hepatic GHR, IGF1 and IGFALS expression, plasma IGF-I concentrations, and significantly decreased plasma GH concentrations compared to age-matched normal young. These data support the hypothesis that the time of maturation of the growth axis depends on the growth rate and maturity of the young, which can be accelerated by changing their nutritional status.

  4. Laboratory selection for an accelerated mosquito sexual development rate

    PubMed Central

    2011-01-01

    Background Separating males and females at the early adult stage did not ensure the virginity of females of Anopheles arabiensis (Dongola laboratory strain), whereas two years earlier this method had been successful. In most mosquito species, newly emerged males and females are not able to mate successfully. For anopheline species, a period of 24 h post-emergence is generally required for the completion of sexual maturation, which in males includes a 180° rotation of the genitalia. In this study, the possibility of an unusually shortened sexual maturity period in the laboratory-reared colony was investigated. Methods The effect of two different sex-separation methods on the virginity of females was tested: females separated as pupae or less than 16 h post-emergence were mated with males subjected to various doses of radiation. T-tests were performed to compare the two sex-separation methods. The rate of genitalia rotation was compared for laboratory-reared and wild males collected as pupae in Dongola, Sudan, and analysed by Z-tests. Spermatheca dissections were performed on females mated with laboratory-reared males to determine their insemination status. Results When the sex-separation was performed when adults were less than 16 h post-emergence, expected sterility was never reached for females mated with radio-sterilized males. Expected sterility was accomplished only when sexes were separated at the pupal stage. Observation of genitalia rotation showed that some males from the laboratory strain Dongola were able to successfully mate only 11 h after emergence and 42% of the males had already completed rotation. A small proportion of the same age females were inseminated. Wild males showed a much slower genitalia rotation rate. At 17 h post-emergence, 96% of the laboratory-reared males had completed genitalia rotation whereas none of the wild males had. Conclusion This colony has been cultured in the laboratory for over one hundred generations, and now has

  5. Gradient of Growth, Spontaneous Changes in Growth Rate and Response to Auxin of Excised Hypocotyl Segments of Phaseolus aureus 1

    PubMed Central

    Prat, Roger

    1978-01-01

    Spontaneous growth was studied in excised mung bean (Phaseolus aureus Roxb.) hypocotyl segments. Measurements were made with a growth-recording apparatus using displacement transducers on single 5- to 6-millimeter samples excised from the growth zone immediately below the hook. Even for a given zone and under controlled experimental conditions, there are differences in the spontaneous growth of individual explants. Nevertheless, in every case, two phases of endogenous acceleration are found at 15 to 20 minutes, and 120 to 150 minutes after excision. Accelerations were separated by steady growth phases. Knowledge of the spontaneous growth curve appears important for the choice of the time of application of experimental stimuli. Auxin was added at various times after excision (0 to 6 hours). The classical biphasic response to auxin was obtained when the hormone was added during a steady phase of growth. However, the response was difficult to interpret when the hormone was added during an acceleration phase. Spontaneous and indoleacetic acid-induced growth were studied along the hypocotyl. Spontaneous growth rate and growth potential revealed by indoleacetic acid changed markedly along the growth gradient. The nature of spontaneous changes according to experimental time and state of differentiation of the cells is discussed. PMID:16660473

  6. The accelerated growth of the worldwide air transportation network

    NASA Astrophysics Data System (ADS)

    Azzam, Mark; Klingauf, Uwe; Zock, Alexander

    2013-01-01

    Mobility by means of air transportation has a critical impact on the global economy. Especially against the backdrop of further growth and an aggravation of the energy crisis, it is crucial to design a sustainable air transportation system. Current approaches focus on air traffic management. Nevertheless, also the historically evolved network offers great potential for an optimized redesign. But the understanding of its complex structure and development is limited, although modern network science supplies a great set of new methods and tools. So far studies analyzing air transportation as a complex network are based on divers and poor data, which are either merely regional or strongly bounded time-wise. As a result, the current state of research is rather inconsistent regarding topological coefficients and incomplete regarding network evolution. Therefore, we use the historical, worldwide OAG flight schedules data between 1979 and 2007 for our study. Through analyzing by far the most comprehensive data base so far, a better understanding of the network, its evolution and further implications is being provided. To our knowledge we present the first study to determine that the degree distribution of the worldwide air transportation network is non-stationary and is subject to densification and accelerated growth, respectively.

  7. Bioelectrochemical system accelerates microbial growth and degradation of filter paper.

    PubMed

    Sasaki, Kengo; Hirano, Shin-Ichi; Morita, Masahiko; Sasaki, Daisuke; Matsumoto, Norio; Ohmura, Naoya; Igarashi, Yasuo

    2011-01-01

    Bioelectrochemical reactors (BERs) with a cathodic working potential of -0.6 or -0.8 V more efficiently degraded cellulosic material, i.e., filter paper (57.4-74.1% in 3 days and 95.9-96.3% in 7 days) than did control reactors without giving exogenous potential (15.4% in 3 days and 64.2% in 7 days). At the same time, resultant conversions to methane and carbon dioxide in cathodic working chamber of BERs by application of electrochemical reduction in 3 days of operation were larger than control reactors. However, cumulative methane production in cathodic BERs was similar to those in control reactors after 7 days of operation. Microscopic observation and 16S rRNA gene analysis showed that microbial growth in the entire consortium was higher after 2 days of operation of cathodic BERs as compared with the control reactors. In addition, the number of methanogenic 16S rRNA gene copies in cathodic BERs was higher than in control reactors. Moreover, archaeal community structures constructed in cathodic BERs consisted of hydrogenotrophic methanogen-related organisms and differed from those in control reactors after 2 days of operation. Specifically, the amount of Methanothermobacter species in cathodic BERs was higher within archaeal communities than in those control reactors after 2 days of operation. Electrochemical reduction may be effective for accelerating microbial growth in the start-up period and thereby increasing microbial treatment of cellulosic waste and methane production.

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

    PubMed

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

    2016-03-01

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

  9. Arabidopsis thaliana root growth kinetics and lunisolar tidal acceleration.

    PubMed

    Fisahn, Joachim; Yazdanbakhsh, Nima; Klingele, Emile; Barlow, Peter

    2012-07-01

    • All living organisms on Earth are continually exposed to diurnal variations in the gravitational tidal force due to the Sun and Moon. • Elongation of primary roots of Arabidopsis thaliana seedlings maintained at a constant temperature was monitored for periods of up to 14 d using high temporal- and spatial-resolution video imaging. The time-course of the half-hourly elongation rates exhibited an oscillation which was maintained when the roots were placed in the free-running condition of continuous illumination. • Correlation between the root growth kinetics collected from seedlings initially raised under several light protocols but whose roots were subsequently in the free-running condition and the lunisolar tidal profiles enabled us to identify that the latter is the probable exogenous determinant of the rhythmic variation in root elongation rate. Similar observations and correlations using roots of Arabidopsis starch mutants suggest a central function of starch metabolism in the response to the lunisolar tide. The periodicity of the lunisolar tidal signal and the concomitant adjustments in root growth rate indicate that an exogenous timer exists for the modulation of root growth and development. • We propose that, in addition to the sensitivity to Earthly 1G gravity, which is inherent to all animals and plants, there is another type of responsiveness which is attuned to the natural diurnal variations of the lunisolar tidal force.

  10. Nd isotopes and crustal growth rate

    NASA Technical Reports Server (NTRS)

    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.

  11. Diffusive shock acceleration - Acceleration rate, magnetic-field direction and the diffusion limit

    NASA Technical Reports Server (NTRS)

    Jokipii, J. R.

    1992-01-01

    This paper reviews the concept of diffusive shock acceleration, showing that the acceleration of charged particles at a collisionless shock is a straightforward consequence of the standard cosmic-ray transport equation, provided that one treats the discontinuity at the shock correctly. This is true for arbitrary direction of the upstream magnetic field. Within this framework, it is shown that acceleration at perpendicular or quasi-perpendicular shocks is generally much faster than for parallel shocks. Paradoxically, it follows also that, for a simple scattering law, the acceleration is faster for less scattering or larger mean free path. Obviously, the mean free path can not become too large or the diffusion limit becomes inapplicable. Gradient and curvature drifts caused by the magnetic-field change at the shock play a major role in the acceleration process in most cases. Recent observations of the charge state of the anomalous component are shown to require the faster acceleration at the quasi-perpendicular solar-wind termination shock.

  12. Magnetospheric chorus - Amplitude and growth rate

    NASA Technical Reports Server (NTRS)

    Burtis, W. J.; Helliwell, R. A.

    1975-01-01

    A new study of the amplitude of magnetospheric chorus with 1966-1967 data from the Stanford University/Stanford Research Institute VLF receivers on Ogo 1 and Ogo 3 has confirmed the band-limited character of magnetospheric chorus in general and the double-banding of near-equatorial chorus. Chorus amplitude tended to be inversely correlated with frequency, implying lower intensities at lower L values. Individual chorus emissions often showed a characteristic amplitude variation, with rise times of 10 to 300 ms, a short duration at peak amplitude, and decay times of 100 to 3000 msec. Growth was often approximately exponential, with rates from 200 to nearly 2000 dB/sec. Rate of change of frequency was found in many cases to be independent of emission amplitude, in agreement with the cyclotron feedback theory of chorus (Helliwell, 1967, 1970).

  13. Growth rate modeling for selective tungsten LPCVD

    NASA Astrophysics Data System (ADS)

    Wolf, H.; Streiter, R.; Schulz, S. E.; Gessner, T.

    1995-10-01

    Selective chemical vapor deposition of tungsten plugs on sputtered tungsten was performed in a single-wafer cold-wall reactor using silane (SiH 4) and tungsten hexafluoride (WF 6). Extensive SEM measurements of film thickness were carried out to study the dependence of growth rates on various process conditions, wafer loading, and via dimensions. The results have been interpreted by numerical calculations based on a simulation model which is also presented. Both continuum fluid dynamics and the ballistic line-of-sight approach are used for transport modeling. The reaction rate is described by an empirical rate expression using coefficients fitted from experimental data. In the range 0.2 < p( SiH 4) /p( WF 6) < 0.75 , the reaction order was determined as 1.55 and -0.55 with respect to SiH 4 and WF 6, respectively. For higher partial pressure ratios the second-order rate dependence on p(SiH 4) and the minus first-order dependence on p(WF 6) were confirmed.

  14. Instability growth rates of crossing sea states.

    PubMed

    Laine-Pearson, F E

    2010-03-01

    Crossing sea states can occur during adverse weather conditions. The instability of such wave trains has been suggested as a possible mechanism for the formation of rogue (freak or extreme) waves. One model for crossing sea states is weakly nonlinear and finite-amplitude short-crested waves (SCWs) on deep water. SCWs are the resonant interaction of two wave systems each with a different direction of propagation. Recently, it has been shown that the stability of these wave interactions is closely associated with the stability of the oblique nonresonant interaction between two waves. The long-wave instability of such waves is considered here; SCWs are used as a benchmark. By using a mismatch of amplitudes, it is demonstrated that instability growth rates of two crossing waves can be larger than those given by SCWs. This indicates that only considering true resonant interactions can underestimate the contribution from unstable crossing sea states to the possible formation of rogue waves.

  15. Near-Term Acceleration In The Rate of Temperature Change

    SciTech Connect

    Smith, Steven J.; Edmonds, James A.; Hartin, Corinne A.; Mundra, Anupriya; Calvin, Katherine V.

    2015-03-09

    Anthropogenically-driven climate changes, which are expected to impact human and natural systems, are often expressed in terms of global-mean temperature . The rate of climate change over multi-decadal scales is also important, with faster rates of change resulting in less time for human and natural systems to adapt . We find that current trends in greenhouse gas and aerosol emissions are now moving the Earth system into a regime in terms of multi-decadal rates of change that are unprecedented for at least the last 1000 years. The rate of global-mean temperature increase in the CMIP5 archive over 40-year periods increases to 0.25±0.05 (1σ) °C per decade by 2020, an average greater than peak rates of change during the previous 1-2 millennia. Regional rates of change in Europe, North America and the Arctic are higher than the global average. Research on the impacts of such near-term rates of change is urgently needed.

  16. Effects of propellant composition variables on acceleration-induced burning-rate augmentation of solid propellants

    NASA Technical Reports Server (NTRS)

    Northam, G. B.

    1972-01-01

    This work was conducted to define further the effects of propellant composition variables on the acceleration-induced burning rate augmentation of solid propellants. The rate augmentation at a given acceleration was found to be a nonlinear inverse function of the reference burning rate and not controlled by binder or catalyst type at a given reference rate. A nonaluminized propellant and a low rate double-base propellant exhibited strong transient rate augmentation due to surface pitting resulting from the retention of hot particles on the propellant surface.

  17. Early rapid growth, early birth: Accelerated fetal growth and spontaneous late preterm birth

    PubMed Central

    Kusanovic, Juan Pedro; Erez, Offer; Espinoza, Jimmy; Gotsch, Francesca; Goncalves, Luis; Hassan, Sonia; Gomez, Ricardo; Nien, Jyh Kae; Frongillo, Edward A.; Romero, Roberto

    2011-01-01

    The past two decades in the United States have seen a 24 % rise in spontaneous late preterm delivery (34 to 36 weeks) of unknown etiology. This study tested the hypothesis that fetal growth was identical prior to spontaneous preterm (n=221, median gestational age at birth 35.6 weeks) and term (n=3706) birth among pregnancies followed longitudinally in Santiago, Chile. The hypothesis was not supported: Preterm-delivered fetuses were significantly larger than their term-delivered peers by mid-second trimester in estimated fetal weight, head, limb and abdominal dimensions, and they followed different growth trajectories. Piecewise regression assessed time-specific differences in growth rates at 4-week intervals from 16 weeks. Estimated fetal weight and abdominal circumference growth rates faltered at 20 weeks among the preterm-delivered, only to match and/or exceed their term-delivered peers at 24–28 weeks. After an abrupt decline at 28 weeks attenuating growth rates in all dimensions, fetuses delivered preterm did so at greater population-specific sex and age-adjusted weight than their peers from uncomplicated pregnancies (p<0.01). Growth rates predicted birth timing: one standard score of estimated fetal weight increased the odds ratio for preterm birth from 2.8 prior to 23 weeks, to 3.6 (95% confidence interval, 1.82–7.11, p<0.05) between 23 and 27 weeks. After 27 weeks, increasing size was protective (OR: 0.56, 95% confidence interval, 0.38–0.82, p=0.003). These data document, for the first time, a distinctive fetal growth pattern across gestation preceding spontaneous late preterm birth, identify the importance of mid-gestation for alterations in fetal growth, and add perspective on human fetal biological variability. PMID:18988282

  18. Intrinsic normalized emittance growth in laser-driven electron accelerators

    NASA Astrophysics Data System (ADS)

    Migliorati, M.; Bacci, A.; Benedetti, C.; Chiadroni, E.; Ferrario, M.; Mostacci, A.; Palumbo, L.; Rossi, A. R.; Serafini, L.; Antici, P.

    2013-01-01

    Laser-based electron sources are attracting strong interest from the conventional accelerator community due to their unique characteristics in terms of high initial energy, low emittance, and significant beam current. Extremely strong electric fields (up to hundreds of GV/m) generated in the plasma allow accelerating gradients much higher than in conventional accelerators and set the basis for achieving very high final energies in a compact space. Generating laser-driven high-energy electron beam lines therefore represents an attractive challenge for novel particle accelerators. In this paper we show that laser-driven electrons generated by the nowadays consolidated TW laser systems, when leaving the interaction region, are subject to a very strong, normalized emittance worsening which makes them quickly unusable for any beam transport. Furthermore, due to their intrinsic beam characteristics, controlling and capturing the full beam current can only be achieved improving the source parameters.

  19. Limestone weathering rates accelerated by micron-scale grain detachment

    NASA Astrophysics Data System (ADS)

    Emmanuel, S.; Levenson, Y.

    2014-12-01

    The weathering rates of carbonate rocks is often thought to be controlled by chemical dissolution, although some studies have suggested that mechanical erosion could also play an important role. Quantifying the rates of the different processes has proved challenging due to the high degree of variability encountered in both field and lab settings. To determine the rates and mechanisms controlling long-term limestone weathering, we analyse a lidar scan of the Western Wall, a Roman period edifice located in Jerusalem. Weathering rates in fine-grained micritic limestone blocks are up to 2 orders of magnitude higher than the average rates estimated for coarse-grained limestone blocks at the same site. In addition, in experiments that use atomic force microscopy to image dissolving micritic limestone, we show that these higher reaction rates could be due to rapid dissolution along micron-scale grain boundaries, followed by mechanical detachment of tiny particles from the surface. Our analysis indicates that micron-scale grain detachment, rather than pure chemical dissolution, could be the dominant erosional mode for fine-grained rocks in many carbonate terrains.

  20. Growth Habits and Growth Rates of Snow Crystals

    NASA Astrophysics Data System (ADS)

    Mason, B. J.

    1993-04-01

    Equations are derived for the growth rates of snow crystals as they fall through the atmosphere in terms of the air temperature, supersaturation and their terminal velocities. The predicted maximum attainable diameters of regular hexagonal plates (0.84 mm), sector plates (ca. 2 mm) and stellar dendrites (3.5 mm) are in good agreement with observations based on Nakaya's large collection of snow crystal photographs. Mason et al. (Phil. Mag. 8, 505 (1963)) determined experimentally the average migration distance xB for water molecules diffusing across the basal surface of ice crystals as a function of temperature. These measurements of xB have now been supplemented by calculations of the corresponding quantity xp for the prism faces from measurements of the limiting c/a ratios of small growing crystals whose shape is largely determined by the values of both xp and xB.A theoretical treatment for the onset of dendritic growth leads to the result that a stationary thin regular hexagonal plate starts to sprout at the corners when its diameter dc exceeds 1.6 × 105 xp2/Dv, where Dv is the diffusion coefficient of water vapour in air. Plates grow in the temperature range -8 degrees C to -23 degrees C, for which dc ranges from 50 μ m at -15 degrees C to 670 μ m at -8 degrees C. For falling ventilated plates the corresponding values of dc are rather larger at 50 μ m and 940 μ m respectively, because the vapour concentration gradients around the crystal are enhanced. These latter values agree respectively with the observed minimum sizes of thin plates found at the centres of stellar dendritic crystals, and with the observed maximum size of regular plates. The observed maximum diameter (1.2 mm) of sector plates at the centre of dendritic crystals agrees well with calculations based on the assumption that these originate at about the -20 degrees C level and develop into dendrites only after falling below the -16 degrees C level. A mechanism, based on the interplay between

  1. Growth rate of Rayleigh-Taylor turbulent mixing layers with the foliation approach.

    PubMed

    Poujade, Olivier; Peybernes, Mathieu

    2010-01-01

    For years, astrophysicists, plasma fusion, and fluid physicists have puzzled over Rayleigh-Taylor turbulent mixing layers. In particular, strong discrepancies in the growth rates have been observed between experiments and numerical simulations. Although two phenomenological mechanisms (mode-coupling and mode-competition) have brought some insight on these differences, convincing theoretical arguments are missing to explain the observed values. In this paper, we provide an analytical expression of the growth rate compatible with both mechanisms and is valid for a self-similar, low Atwood Rayleigh-Taylor turbulent mixing subjected to a constant or time-varying acceleration. The key step in this work is the presentation of foliated averages and foliated turbulent spectra highlighted in our three-dimensional numerical simulations. We show that the exact value of the Rayleigh-Taylor growth rate not only depends upon the acceleration history but is also bound to the power-law exponent of the foliated spectra at large scales.

  2. Growth rate of Rayleigh-Taylor turbulent mixing layers with the foliation approach

    SciTech Connect

    Poujade, Olivier; Peybernes, Mathieu

    2010-01-15

    For years, astrophysicists, plasma fusion, and fluid physicists have puzzled over Rayleigh-Taylor turbulent mixing layers. In particular, strong discrepancies in the growth rates have been observed between experiments and numerical simulations. Although two phenomenological mechanisms (mode-coupling and mode-competition) have brought some insight on these differences, convincing theoretical arguments are missing to explain the observed values. In this paper, we provide an analytical expression of the growth rate compatible with both mechanisms and is valid for a self-similar, low Atwood Rayleigh-Taylor turbulent mixing subjected to a constant or time-varying acceleration. The key step in this work is the presentation of foliated averages and foliated turbulent spectra highlighted in our three-dimensional numerical simulations. We show that the exact value of the Rayleigh-Taylor growth rate not only depends upon the acceleration history but is also bound to the power-law exponent of the foliated spectra at large scales.

  3. Anthropogenic and biophysical contributions to increasing atmospheric CO2 growth rate and airborne fraction

    NASA Astrophysics Data System (ADS)

    Raupach, M. R.; Canadell, J. G.; Le Quéré, C.

    2008-11-01

    We quantify the relative roles of natural and anthropogenic influences on the growth rate of atmospheric CO2 and the CO2 airborne fraction, considering both interdecadal trends and interannual variability. A combined ENSO-Volcanic Index (EVI) relates most (~75%) of the interannual variability in CO2 growth rate to the El-Niño-Southern-Oscillation (ENSO) climate mode and volcanic activity. Analysis of several CO2 data sets with removal of the EVI-correlated component confirms a previous finding of a detectable increasing trend in CO2 airborne fraction (defined using total anthropogenic emissions including fossil fuels and land use change) over the period 1959 2006, at a proportional growth rate 0.24% y-1 with probability ~0.9 of a positive trend. This implies that the atmospheric CO2 growth rate increased slightly faster than total anthropogenic CO2 emissions. To assess the combined roles of the biophysical and anthropogenic drivers of atmospheric CO2 growth, the increase in the CO2 growth rate (1.9% y-1 over 1959 2006) is expressed as the sum of the growth rates of four global driving factors: population (contributing +1.7% y-1); per capita income (+1.8% y-1); the total carbon intensity of the global economy (-1.7% y-1); and airborne fraction (averaging +0.2% y-1 with strong interannual variability). The first three of these factors, the anthropogenic drivers, have therefore dominated the last, biophysical driver as contributors to accelerating CO2 growth. Together, the recent (post-2000) increase in growth of per capita income and decline in the negative growth (improvement) in the carbon intensity of the economy will drive a significant further acceleration in the CO2 growth rate over coming decades, unless these recent trends reverse.

  4. Accelerating failure rate of the ASR total hip replacement.

    PubMed

    Langton, D J; Jameson, S S; Joyce, T J; Gandhi, J N; Sidaginamale, R; Mereddy, P; Lord, J; Nargol, A V F

    2011-08-01

    There is widespread concern regarding the incidence of adverse soft-tissue reactions after metal-on-metal (MoM) hip replacement. Recent National Joint Registry data have shown clear differences in the rates of failure of different designs of hip resurfacing. Our aim was to update the failure rates related to metal debris for the Articular Surface Replacement (ASR). A total of 505 of these were implanted. Kaplan-Meier analysis showed a failure rate of 25% at six years for the ASR resurfacing and of 48.8% for the ASR total hip replacement (THR). Of 257 patients with a minimum follow-up of two years, 67 (26.1%) had a serum cobalt concentration which was greater than 7 μg/l. Co-ordinate measuring machine analysis of revised components showed that all patients suffering adverse tissue reactions in the resurfacing group had abnormal wear of the bearing surfaces. Six THR patients had relatively low rates of articular wear, but were found to have considerable damage at the trunion-taper interface. Our results suggest that wear at the modular junction is an important factor in the development of adverse tissue reactions after implantation of a large-diameter MoM THR.

  5. The trade-off between maturation and growth during accelerated development in frogs.

    PubMed

    Mueller, Casey A; Augustine, Starrlight; Kooijman, Sebastiaan A L M; Kearney, Michael R; Seymour, Roger S

    2012-09-01

    Developmental energetics are crucial to a species' life history and ecology but are poorly understood from a mechanistic perspective. Traditional energy and mass budgeting does not distinguish between costs of growth and maturation, making it difficult to account for accelerated development. We apply a metabolic theory that uniquely considers maturation costs (Dynamic Energy Budget theory, DEB) to interpret empirical data on the energetics of accelerated development in amphibians. We measured energy use until metamorphosis in two related frogs, Crinia georgiana and Pseudophryne bibronii. Mass and energy content of fresh ova were comparable between the species. However, development to metamorphosis was 1.7 times faster in C. georgiana while P. bibronii produced nine times the dry biomass at metamorphosis and had lower mass-specific oxygen requirements. DEB theory explained these patterns through differences in ontogenetic energy allocation to maturation. P. bibronii partitioned energy in the same (constant) way throughout development whereas C. georgiana increased the fraction of energy allocated to maturation over growth between hatching and the onset of feeding. DEB parameter estimation for additional, direct-developing taxa suggests that a change in energy allocation during development may result from a selective pressure to increase development rate, and not as a result of development mode.

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

    ERIC Educational Resources Information Center

    Rowland, Stephen M.

    1983-01-01

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

  7. Tree growth acceleration and expansion of alpine forests: The synergistic effect of atmospheric and edaphic change

    PubMed Central

    Silva, Lucas C. R.; Sun, Geng; Zhu-Barker, Xia; Liang, Qianlong; Wu, Ning; Horwath, William R.

    2016-01-01

    Many forest ecosystems have experienced recent declines in productivity; however, in some alpine regions, tree growth and forest expansion are increasing at marked rates. Dendrochronological analyses at the upper limit of alpine forests in the Tibetan Plateau show a steady increase in tree growth since the early 1900s, which intensified during the 1930s and 1960s, and have reached unprecedented levels since 1760. This recent growth acceleration was observed in small/young and large/old trees and coincided with the establishment of trees outside the forest range, reflecting a connection between the physiological performance of dominant species and shifts in forest distribution. Measurements of stable isotopes (carbon, oxygen, and nitrogen) in tree rings indicate that tree growth has been stimulated by the synergistic effect of rising atmospheric CO2 and a warming-induced increase in water and nutrient availability from thawing permafrost. These findings illustrate the importance of considering soil-plant-atmosphere interactions to understand current and anticipate future changes in productivity and distribution of forest ecosystems. PMID:27652334

  8. Tree growth acceleration and expansion of alpine forests: The synergistic effect of atmospheric and edaphic change.

    PubMed

    Silva, Lucas C R; Sun, Geng; Zhu-Barker, Xia; Liang, Qianlong; Wu, Ning; Horwath, William R

    2016-08-01

    Many forest ecosystems have experienced recent declines in productivity; however, in some alpine regions, tree growth and forest expansion are increasing at marked rates. Dendrochronological analyses at the upper limit of alpine forests in the Tibetan Plateau show a steady increase in tree growth since the early 1900s, which intensified during the 1930s and 1960s, and have reached unprecedented levels since 1760. This recent growth acceleration was observed in small/young and large/old trees and coincided with the establishment of trees outside the forest range, reflecting a connection between the physiological performance of dominant species and shifts in forest distribution. Measurements of stable isotopes (carbon, oxygen, and nitrogen) in tree rings indicate that tree growth has been stimulated by the synergistic effect of rising atmospheric CO2 and a warming-induced increase in water and nutrient availability from thawing permafrost. These findings illustrate the importance of considering soil-plant-atmosphere interactions to understand current and anticipate future changes in productivity and distribution of forest ecosystems.

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

    NASA Technical Reports Server (NTRS)

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

    2012-01-01

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

  10. Calcite crystal growth rate inhibition by polycarboxylic acids

    USGS Publications Warehouse

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

    2001-01-01

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

  11. Stillbirths: rates, risk factors, and acceleration towards 2030.

    PubMed

    Lawn, Joy E; Blencowe, Hannah; Waiswa, Peter; Amouzou, Agbessi; Mathers, Colin; Hogan, Dan; Flenady, Vicki; Frøen, J Frederik; Qureshi, Zeshan U; Calderwood, Claire; Shiekh, Suhail; Jassir, Fiorella Bianchi; You, Danzhen; McClure, Elizabeth M; Mathai, Matthews; Cousens, Simon

    2016-02-06

    An estimated 2.6 million third trimester stillbirths occurred in 2015 (uncertainty range 2.4-3.0 million). The number of stillbirths has reduced more slowly than has maternal mortality or mortality in children younger than 5 years, which were explicitly targeted in the Millennium Development Goals. The Every Newborn Action Plan has the target of 12 or fewer stillbirths per 1000 births in every country by 2030. 94 mainly high-income countries and upper middle-income countries have already met this target, although with noticeable disparities. At least 56 countries, particularly in Africa and in areas affected by conflict, will have to more than double present progress to reach this target. Most (98%) stillbirths are in low-income and middle-income countries. Improved care at birth is essential to prevent 1.3 million (uncertainty range 1.2-1.6 million) intrapartum stillbirths, end preventable maternal and neonatal deaths, and improve child development. Estimates for stillbirth causation are impeded by various classification systems, but for 18 countries with reliable data, congenital abnormalities account for a median of only 7.4% of stillbirths. Many disorders associated with stillbirths are potentially modifiable and often coexist, such as maternal infections (population attributable fraction: malaria 8.0% and syphilis 7.7%), non-communicable diseases, nutrition and lifestyle factors (each about 10%), and maternal age older than 35 years (6.7%). Prolonged pregnancies contribute to 14.0% of stillbirths. Causal pathways for stillbirth frequently involve impaired placental function, either with fetal growth restriction or preterm labour, or both. Two-thirds of newborns have their births registered. However, less than 5% of neonatal deaths and even fewer stillbirths have death registration. Records and registrations of all births, stillbirths, neonatal, and maternal deaths in a health facility would substantially increase data availability. Improved data alone will not

  12. Economic growth rate management by soft computing approach

    NASA Astrophysics Data System (ADS)

    Maksimović, Goran; Jović, Srđan; Jovanović, Radomir

    2017-01-01

    Economic growth rate management is very important process in order to improve the economic stability of any country. The main goal of the study was to manage the impact of agriculture, manufacturing, industry and services on the economic growth rate prediction. Soft computing methodology was used in order to select the inputs influence on the economic growth rate prediction. It is known that the economic growth may be developed on the basis of combination of different factors. Gross domestic product (GDP) was used as economic growth indicator. It was found services have the highest impact on the GDP growth rate. On the contrary, the manufacturing has the smallest impact on the GDP growth rate.

  13. The application of exogenous cellulase to improve soil fertility and plant growth due to acceleration of straw decomposition.

    PubMed

    Han, Wei; He, Ming

    2010-05-01

    The effects of exogenous cellulase application on straw decomposition, soil fertility, and plant growth were investigated with nylon bag and pot experiments. Cellulase application promoted straw decomposition, and the decomposition rates of rice and wheat straw increased by 6.3-26.0% and 6.8-28.0%, respectively, in the nylon bag experiments. In pot experiments soil-available N and P contents, soil cellulase activity, and growth of rice seedlings increased. Soil respiration rate and microbial population were unaffected. Seventy Ug(-1) was the optimal cellulase concentration for plant growth. The exogenous cellulase persisted in soil for more than 100days. Although the data show that exogenous cellulase application can enhance soil fertility and plant growth in the short-term due to the acceleration of straw decomposition and has the potential to be an environment-friendly approach to manage straw, cellulase application to soil seems currently not economical.

  14. The rate of change of acceleration: implications to head kinematics during rear-end impacts.

    PubMed

    Hynes, Loriann M; Dickey, James P

    2008-05-01

    Whiplash is a mechanism of injury commonly associated with rear-impact vehicle collisions. To date, research has focused primarily on changes in velocity and acceleration as key factors for determining injuries due to whiplash mechanisms, but other characteristics of the acceleration pulse may be important. This study assessed whether the head acceleration response to whiplash-like perturbation profiles were affected by a change in the rate of the applied acceleration, or jerk. Twenty-one subjects were exposed to different low-velocity rear-impact whiplash-like perturbations using a precisely controlled robotic platform. The perturbations were divided into two groupings of peak acceleration (approximately 10 (high) and 5.7 (low) m/s2) and three groupings of jerk (approximately 260, 310, and 360 m/s3). These six profiles were repeated twice. Results demonstrated that the jerk magnitude significantly affected forehead acceleration in the vertical and horizontal directions. Increasing the magnitude of the platform acceleration also differentially affected the horizontal and vertical forehead accelerations. This indicates that the level of jerk influences the resulting head kinematics and should be considered when designing or interpreting experiments that are attempting to predict injury from whiplash-like perturbations.

  15. Measurement of seedling growth rate by machine vision

    NASA Astrophysics Data System (ADS)

    Howarth, M. Scott; Stanwood, Phillip C.

    1993-05-01

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

  16. Baldwin effect under multipeaked fitness landscapes: Phenotypic fluctuation accelerates evolutionary rate

    NASA Astrophysics Data System (ADS)

    Saito, Nen; Ishihara, Shuji; Kaneko, Kunihiko

    2013-05-01

    Phenotypic fluctuations and plasticity can generally affect the course of evolution, a process known as the Baldwin effect. Several studies have recast this effect and claimed that phenotypic plasticity accelerates evolutionary rate (the Baldwin expediting effect); however, the validity of this claim is still controversial. In this study, we investigate the evolutionary population dynamics of a quantitative genetic model under a multipeaked fitness landscape, in order to evaluate the validity of the effect. We provide analytical expressions for the evolutionary rate and average population fitness. Our results indicate that under a multipeaked fitness landscape, phenotypic fluctuation always accelerates evolutionary rate, but it decreases the average fitness. As an extreme case of the trade-off between the rate of evolution and average fitness, phenotypic fluctuation is shown to accelerate the error catastrophe, in which a population fails to sustain a high-fitness peak. In the context of our findings, we discuss the role of phenotypic plasticity in adaptive evolution.

  17. Acceleration of the rate of ethanol fermentation by addition of nitrogen in high tannin grain sorghum

    SciTech Connect

    Mullins, J.T.; NeSmith, C.C.

    1987-01-01

    In this communication, the authors show that accelerated rates of ethanol production, comparable to sorghum varieties containing low levels of tannins and to corn, can occur without the removal of the tannins. The basis of the inhibition appears to be a lack of sufficient nitrogen in the mash for protein synthesis required to support an accelerated fermentative metabolism in Saccharomyces. No inhibition of the enzymes used for starch hydrolysis was found.

  18. Resistive Wall Growth Rate Measurements in the Fermilab Recycler

    SciTech Connect

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

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  20. Effect of Residual Accelerations on the Crystal Growth of II-VI Semiconductors in Low Earth Orbit

    NASA Technical Reports Server (NTRS)

    Gillies, D. C.; Su, C.-H.; Szofran, F. R.; Scripa, R. N.; Cobb, S. D.; Lehoczky, S. L.; Curreri, Peter A. (Technical Monitor)

    2002-01-01

    The paper compares and summarizes the effects of residual acceleration during crystal growth on the compositional variation of two II-VI solid solution binary alloys (Hg(0.8)Cd(0.2)Te and Hg(0.84)Zn(0.16)Te). The crystals were grown by directional solidification on the second United States Microgravity Payload (USMP-2) and the first United States Microgravity Laboratory (USML-1) missions, respectively. For both alloys, changes in the direction and magnitude of the quasisteady acceleration vector (approximately 0.4- 1 mu g) caused large changes in the radial compositional distribution that demonstrates the importance of residual accelerations, even in the submicrogravity range, for large density gradients in the melt and slow solidification rates. The observed compositional variations will be correlated to changes in the radial flow velocities ahead of the solidification interface.

  1. Dinosaur Metabolism and the Allometry of Maximum Growth Rate

    PubMed Central

    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

  2. Recombinant Human Epidermal Growth Factor Accelerates Recovery of Mouse Small Intestinal Mucosa After Radiation Damage

    SciTech Connect

    Lee, Kang Kyoo; Jo, Hyang Jeong; Hong, Joon Pio; Lee, Sang-wook Sohn, Jung Sook; Moon, Soo Young; Yang, Sei Hoon; Shim, Hyeok; Lee, Sang Ho; Ryu, Seung-Hee; Moon, Sun Rock

    2008-07-15

    Purpose: To determine whether systemically administered recombinant human epidermal growth factor (rhEGF) accelerates the recovery of mouse small intestinal mucosa after irradiation. Methods and Materials: A mouse mucosal damage model was established by administering radiation to male BALB/c mice with a single dose of 15 Gy applied to the abdomen. After irradiation, rhEGF was administered subcutaneously at various doses (0.04, 0.2, 1.0, and 5.0 mg/kg/day) eight times at 2- to 3-day intervals. The evaluation methods included histologic changes of small intestinal mucosa, change in body weight, frequency of diarrhea, and survival rate. Results: The recovery of small intestinal mucosa after irradiation was significantly improved in the mice treated with a high dose of rhEGF. In the mice that underwent irradiation without rhEGF treatment, intestinal mucosal ulceration, mucosal layer damage, and severe inflammation occurred. The regeneration of villi was noticeable in mice treated with more than 0.2 mg/kg rhEGF, and the villi recovered fully in mice given more than 1 mg/kg rhEGF. The frequency of diarrhea persisting for more than 3 days was significantly greater in the radiation control group than in the rhEGF-treated groups. Conclusions: Systemic administration of rhEGF accelerates recovery from mucosal damage induced by irradiation. We suggest that rhEGF treatment shows promise for the reduction of small intestinal damage after irradiation.

  3. Computed lateral rate and acceleration power spectral response of conventional and STOL airplanes to atmospheric turbulence

    NASA Technical Reports Server (NTRS)

    Lichtenstein, J. H.

    1975-01-01

    Power-spectral-density calculations were made of the lateral responses to atmospheric turbulence for several conventional and short take-off and landing (STOL) airplanes. The turbulence was modeled as three orthogonal velocity components, which were uncorrelated, and each was represented with a one-dimensional power spectrum. Power spectral densities were computed for displacements, rates, and accelerations in roll, yaw, and sideslip. In addition, the power spectral density of the transverse acceleration was computed. Evaluation of ride quality based on a specific ride quality criterion was also made. The results show that the STOL airplanes generally had larger values for the rate and acceleration power spectra (and, consequently, larger corresponding root-mean-square values) than the conventional airplanes. The ride quality criterion gave poorer ratings to the STOL airplanes than to the conventional airplanes.

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

    NASA Astrophysics Data System (ADS)

    Şahin, Ö.; Özdemir, M.; Genli, N.

    2004-01-01

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

  5. Growth rate changes of sodium chlorate crystals independent of growth conditions

    NASA Astrophysics Data System (ADS)

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

    2008-10-01

    Results of investigations of the growth rate changes inherent to the crystal are presented. It is shown that, in initial growth stage, there exist crystal growth rate changes independent of experimental conditions, with tendency to level during the time. Time evolution of sodium chlorate crystals growth rate dispersion is also presented. The results obtained show that these changes must be included in the interpretations of the growth rate changes affected by various parameters (supersaturation, temperature, fields, stress, impurities, etc.), which have not previously been taken into account. These results may improve the current crystal growth theories.

  6. Bunch self-focusing regime of laser wakefield acceleration with reduced emittance growth.

    PubMed

    Reitsma, A J W; Goloviznin, V V; Kamp, L P J; Schep, T J

    2002-01-07

    A new regime of laser wakefield acceleration of an injected electron bunch is described. In this regime, the bunch charge is so high that the bunch wakefields play an important role in the bunch dynamics. In particular, the transverse bunch wakefield induces a strong self-focusing that suppresses the transverse emittance growth arising from misalignment errors. The decelerating longitudinal bunch wakefield, however, is not so strong that it completely cancels the accelerating laser wakefield. In fact, the induced energy spread can be compensated by exploiting phase slippage effects. These features make the new regime interesting for high beam quality laser wakefield acceleration.

  7. Increased diffuse radiation fraction does not significantly accelerate plant growth

    NASA Astrophysics Data System (ADS)

    Angert, Alon; Krakauer, Nir

    2010-05-01

    A recent modelling study (Mercado et al., 2009) claims that increased numbers of scattering aerosols are responsible for a substantial fraction of the terrestrial carbon sink in recent decades because higher diffuse light fraction enhances plant net primary production (NPP). Here we show that observations of atmospheric CO2 seasonal cycle and tree ring data indicate that the relation between diffuse light and NPP is actually quite weak on annual timescales. The inconsistency of these data with the modelling results may arise because the relationships used to quantify the enhancement of NPP were calibrated with eddy covariance measurements of hourly carbon uptake. The effect of diffuse-light fraction on carbon uptake could depend on timescale, since this effect varies rapidly as sun angle and cloudiness change, and since plants can respond dynamically over various timescales to change in incoming radiation. Volcanic eruptions, such as the eruption of Mount Pinatubo in 1991, provide the best available tests for the effect of an annual-scale increase in the diffuse light fraction. Following the Pinatubo Eruption, in 1992 and 1993, a sharp decrease in the atmospheric CO2 growth rate was observed. This could have resulted from enhanced plant carbon uptake. Mercado et al. (2009) argue that largely as a result of the (volcanic aerosol driven) increase in diffuse light fraction, NPP was elevated in 1992, particularly between 25° N-45° N where annual NPP was modelled to be ~0.8 PgC (~10%) above average. In a previous study (Angert et al., 2004) a biogeochemical model (CASA) linked to an atmospheric tracer model (MATCH), was used to show that a diffuse-radiation driven increase in NPP in the extratropics will enhance carbon uptake mostly in summer, leading to a lower CO2 seasonal minimum. Here we use a 'toy model' to show that this conclusion is general and model-independent. The model shows that an enhanced sink of 0.8 PgC, similar to that modelled by Mercado et al. (2009

  8. Comparative analysis of animal growth: a primate continuum revealed by a new dimensionless growth rate coefficient.

    PubMed

    Vinicius, Lucio; Mumby, Hannah S

    2013-05-01

    The comparative analysis of animal growth still awaits full integration into life-history studies, partially due to the difficulty of defining a comparable measure of growth rate across species. Using growth data from 50 primate species, we introduce a modified "general growth model" and a dimensionless growth rate coefficient β that controls for size scaling and phylogenetic effects in the distribution of growth rates. Our results contradict the prevailing idea that slow growth characterizes primates as a group: the observed range of β values shows that not all primates grow slowly, with galago species exhibiting growth rates similar or above the mammalian average, while other strepsirrhines and most New World monkeys show limited reduction in growth rates. Low growth rate characterizes apes and some papionines. Phylogenetic regressions reveal associations between β and life-history variables, providing tests for theories of primate growth evolution. We also show that primate slow growth is an exclusively postnatal phenomenon. Our study exemplifies how the dimensionless approach promotes the integration of growth rate data into comparative life-history analysis, and demonstrates its potential applicability to other cases of adaptive diversification of animal growth patterns.

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

    PubMed Central

    Sibly, Richard M; Hone, Jim

    2002-01-01

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

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

    PubMed

    Werner, Jan; Griebeler, Eva Maria

    2014-01-01

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

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

    PubMed Central

    Werner, Jan; Griebeler, Eva Maria

    2014-01-01

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

  12. Coenzyme Q10 prevents accelerated cardiac aging in a rat model of poor maternal nutrition and accelerated postnatal growth.

    PubMed

    Tarry-Adkins, Jane L; Blackmore, Heather L; Martin-Gronert, Malgorzata S; Fernandez-Twinn, Denise S; McConnell, Josie M; Hargreaves, Iain P; Giussani, Dino A; Ozanne, Susan E

    2013-01-01

    Studies in human and animals have demonstrated that nutritionally induced low birth-weight followed by rapid postnatal growth increases the risk of metabolic syndrome and cardiovascular disease. Although the mechanisms underlying such nutritional programming are not clearly defined, increased oxidative-stress leading to accelerated cellular aging has been proposed to play an important role. Using an established rodent model of low birth-weight and catch-up growth, we show here that post-weaning dietary supplementation with coenzyme Q10, a key component of the electron transport chain and a potent antioxidant rescued many of the detrimental effects of nutritional programming on cardiac aging. This included a reduction in nitrosative and oxidative-stress, telomere shortening, DNA damage, cellular senescence and apoptosis. These findings demonstrate the potential for postnatal antioxidant intervention to reverse deleterious phenotypes of developmental programming and therefore provide insight into a potential translatable therapy to prevent cardiovascular disease in at risk humans.

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

    SciTech Connect

    Kemp, P.F.

    1995-12-31

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

  14. Deceleration and acceleration capacities of heart rate associated with heart failure with high discriminating performance.

    PubMed

    Hu, Wei; Jin, Xian; Zhang, Peng; Yu, Qiang; Yin, Guizhi; Lu, Yi; Xiao, Hongbing; Chen, Yueguang; Zhang, Dadong

    2016-03-23

    Accurate measurements of autonomic nerve regulation in heart failure (HF) were unresolved. The discriminating performance of deceleration and acceleration capacities of heart rate in HF was evaluated in 130 HF patients and 212 controls. Acceleration capacity and deceleration capacity were independent risk factors for HF in males, evaluated by multiple logistic regression analysis, with odds ratios (ORs) of 5.94 and 0.13, respectively. Acceleration capacity was also an independent risk factor for HF in females, with an OR of 8.58. Deceleration capacity was the best cardiac electrophysiological index to classify HF in males, with an area under the receiver operating characteristic curve (AUC) of 0.88. Deceleration capacity was the best classification factor of HF in females with an AUC of 0.97, significantly higher than even left ventricular ejection fraction (LVEF). Acceleration capacity also showed high performance in classifying HF in males (0.84) and females (0.92). The cut-off values of deceleration capacity for HF classification in males and females were 4.55 ms and 4.85 ms, respectively. The cut-off values of acceleration capacity for HF classification in males and females were -6.15 ms and -5.75 ms, respectively. Our study illustrates the role of acceleration and deceleration capacity measurements in the neuro-pathophysiology of HF.

  15. Deceleration and acceleration capacities of heart rate associated with heart failure with high discriminating performance

    PubMed Central

    Hu, Wei; Jin, Xian; Zhang, Peng; Yu, Qiang; Yin, Guizhi; Lu, Yi; Xiao, Hongbing; Chen, Yueguang; Zhang, Dadong

    2016-01-01

    Accurate measurements of autonomic nerve regulation in heart failure (HF) were unresolved. The discriminating performance of deceleration and acceleration capacities of heart rate in HF was evaluated in 130 HF patients and 212 controls. Acceleration capacity and deceleration capacity were independent risk factors for HF in males, evaluated by multiple logistic regression analysis, with odds ratios (ORs) of 5.94 and 0.13, respectively. Acceleration capacity was also an independent risk factor for HF in females, with an OR of 8.58. Deceleration capacity was the best cardiac electrophysiological index to classify HF in males, with an area under the receiver operating characteristic curve (AUC) of 0.88. Deceleration capacity was the best classification factor of HF in females with an AUC of 0.97, significantly higher than even left ventricular ejection fraction (LVEF). Acceleration capacity also showed high performance in classifying HF in males (0.84) and females (0.92). The cut-off values of deceleration capacity for HF classification in males and females were 4.55 ms and 4.85 ms, respectively. The cut-off values of acceleration capacity for HF classification in males and females were −6.15 ms and −5.75 ms, respectively. Our study illustrates the role of acceleration and deceleration capacity measurements in the neuro-pathophysiology of HF. PMID:27005970

  16. Accelerated tests for bounding the low dose rate radiation response of lateral PNP bipolar junction transistors

    SciTech Connect

    Witczak, S.C.; Schrimpf, R.D.; Galloway, K.F.; Schmidt, D.M.; Fleetwood, D.M.; Pease, R.L.; Coombs, W.E.; Suehle, J.S.

    1996-03-01

    Low dose rate gain degradation of lateral pnp bipolar transistors can be simulated by accelerated irradiations performed at approximately 135 degrees C. Degradation enhancement is explained by temperature- dependent radiation-induced interface trap formation above the transistor`s base.

  17. Accelerating rate calorimetry: A new technique for safety studies in lithium systems

    NASA Technical Reports Server (NTRS)

    Ebner, W. B.

    1982-01-01

    The role of exothermic reactions in battery test modes is discussed. The exothermic reactions are characterized with respect to their time-temperature and time-pressure behavior. Reactions occuring for any major exotherm were examined. The accelerating rate calorimetry methods was developed to study lithium cells susceptibility to thermal runaway reactions following certain abuse modes such as forced discharge into reversal and charging.

  18. ULTRASOUND INCREASES THE RATE OF BACTERIAL CELL GROWTH

    PubMed Central

    Pitt, William G.; Ross, S. Aaron

    2006-01-01

    Ultrasound was employed to increase the growth rate of bacterial cells attached to surfaces. Staphylococcus epidermidis, Pseudomonas aeruginosa and Escherichia coli cells adhered to and grew on a polyethylene surface in the presence of ultrasound. It was found that low frequency ultrasound (70 kHz) of low acoustic intensity (<2 W/cm2) increased the growth rate of the cells compared to growth without ultrasound. However, at high intensity levels, cells were partially removed from the surface. Ultrasound also enhanced planktonic growth of S. epidermidis and other planktonic bacteria. It is hypothesized that ultrasound increases the rate of transport of oxygen and nutrients to the cells and increases the rate of transport of waste products away from the cells, thus enhancing their growth. PMID:12790676

  19. Evolution of high-repetition-rate induction accelerators through advancements in switching

    NASA Astrophysics Data System (ADS)

    Kirbie, H. C.; Caporaso, G. J.; Newton, M. A.; Yu, S. S.

    1992-08-01

    Future applications of linear and recirculating induction accelerators include microwave sources for plasma heating and linear colliders, industrial manufacturing processes, and heavy ion fusion. These applications require pulsed sources capable of sustained operation at high pulse-repetition rates. Powering these new accelerators places severe switching demands on the source, demands that often can not be met withcommercially-available technology. Consequently, several new accelerator switching schemes have been developed at Lawrence Livermore National Laboratory (LLNL). Our transition from spark-gap technology to magnetic switching has merged the formerly independent roles of source and cell into a single system and reshaped our design methods to emphasize high efficiency. Treatment of the accelerator as a system has also enabled us to optimize new accelerator designs based on cost considerations. Presently, we are developing a technology for driving a heavy-ion induction recirculator at pulse rates exceeding 100 kHz. In this case, the switching method is all solid state and the source and cell have evolved into a unified device.

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

    SciTech Connect

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

    2015-03-30

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

  1. Modeling the Growth Rates of Tetragonal Lysozyme Crystal Faces

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

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

  2. Growth and development rates have different thermal responses.

    PubMed

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

    2011-11-01

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

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

    DOE PAGES

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

    2015-03-30

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

  4. Microtubules Growth Rate Alteration in Human Endothelial Cells

    PubMed Central

    Alieva, Irina B.; Zemskov, Evgeny A.; Kireev, Igor I.; Gorshkov, Boris A.; Wiseman, Dean A.; Black, Stephen M.; Verin, Alexander D.

    2010-01-01

    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. PMID:20445745

  5. Microtubules growth rate alteration in human endothelial cells.

    PubMed

    Alieva, Irina B; Zemskov, Evgeny A; Kireev, Igor I; Gorshkov, Boris A; Wiseman, Dean A; Black, Stephen M; Verin, Alexander D

    2010-01-01

    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.

  6. Minimization of three-dimensional beam emittance growth in rare-isotope accelerator

    NASA Astrophysics Data System (ADS)

    Oh, B. H.; Yoon, M.

    2016-12-01

    In this paper, we describe a research to minimize the three-dimensional (3D) emittance growth (EG) in the RAON accelerator, a heavy ion accelerator currently being developed in Korea to produce various rare isotopes. The emittance minimization is performed using the multi-objective genetic algorithm and the simplex method. We use them to analyze the driver linac for the in-flight fragmentation separator of the RAON facility and show that redesign of the 90-degree bending section of the RAON accelerator together with adjustment of optics in the upstream and downstream superconducting linacs can limit the 3D EG to 20 % in the entire region of the driver linac. Effects of various magnet and rf accelerating cavity errors on the beam-EG are also discussed.

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

    NASA Technical Reports Server (NTRS)

    Nadarajah, Arunan

    1996-01-01

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

  8. Overexpression of insulin-like growth factor-II induces accelerated myoblast differentiation.

    PubMed

    Stewart, C E; James, P L; Fant, M E; Rotwein, P

    1996-10-01

    Previous studies have shown that exogenous insulin-like growth factors (IGFs) can stimulate the terminal differentiation of skeletal myoblasts in culture and have established a correlation between the rate and the extent of IGF-II secretion by muscle cell lines and the rate of biochemical and morphological differentiation. To investigate the hypothesis that autocrine secretion of IGF-II plays a critical role in stimulating spontaneous myogenic differentiation in vitro, we have established C2 muscle cell lines that stably express a mouse IGF-II cDNA under control of the strong, constitutively active Moloney sarcoma virus promoter, enabling us to study directly the effects of IGF-II overproduction. Similar to observations with other muscle cell lines, IGF-II overexpressing myoblasts proliferated normally in growth medium containing 20% fetal serum, but they underwent enhanced differentiation compared with controls when incubated in low-serum differentiation medium. Accelerated differentiation of IGF-II overexpressing C2 cells was preceded by the rapid induction of myogenin mRNA and protein expression (within 1 h, compared with 24-48 h in controls) and was accompanied by an enhanced proportion of the retinoblastoma protein in an underphosphrylated and potentially active form, by a marked increase in activity of the muscle-specific enzyme, creatine phosphokinase, by extensive myotube formation by 48 h, and by elevated secretion of IGF binding protein-5 when compared with controls. These results confirm a role for IGF-II as an autocrine/paracrine differentiation factor for skeletal myoblasts, and they define a model cell system that will be useful in determining the biochemical mechanisms of IGF action in cellular differentiation.

  9. Integrating Frameworks from Early Childhood Intervention and School Psychology to Accelerate Growth for All Young Children

    ERIC Educational Resources Information Center

    VanDerHeyden, Amanda M.; Snyder, Patricia

    2006-01-01

    Knowing what behaviors adults can engage in to accelerate child growth toward desired outcomes is fundamental to achieving the promise of early education and intervention. Once adequate progress-monitoring measures are developed, patterns of child performance over time and in response to certain interventions can be quantified. The ability to…

  10. Global evidence on the distribution of GDP growth rates

    NASA Astrophysics Data System (ADS)

    Williams, Michael A.; Baek, Grace; Li, Yiyang; Park, Leslie Y.; Zhao, Wei

    2017-02-01

    We study the size distribution of changes in the gross domestic product (GDP) of 167 countries for the period 1950-2011. A consensus has developed in the literature that the distribution of GDP growth rates can be approximated by the Laplace distribution in the central part and power-law distributions in the tails. Using a richer database than prior studies and testing for more theoretical distributions, we find that the distribution of GDP growth rates can be fitted using the heavy-tailed Cauchy distribution for almost all countries. Significantly, this same finding recently has been demonstrated for (1) the distribution of firm growth rates and (2) the distribution of firm economic profit rates. Together, these three findings suggest the possibility that there exist universal mechanisms that give rise to general laws governing the growth dynamics of firms and economies.

  11. Debris growth sensitivity to launch and cascade rates

    SciTech Connect

    Canavan, G.H.

    1996-10-24

    Two-component models provide a good description of debris growth from the outset of launch to the present, predictions of future trends, and assessments of their sensitivity. Launch rate reductions produce less than proportional reductions in debris, for reasons that are discussed. The shift of debris to higher altitudes is assessed quantitatively, although the details of the growth are discussed elsewhere.

  12. A Simple Device to Measure Root Growth Rates

    ERIC Educational Resources Information Center

    Rauser, Wilfried E.; Horton, Roger F.

    1975-01-01

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

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

    USGS Publications Warehouse

    Das, Adrian J.; Stephenson, Nathan L.

    2015-01-01

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

  14. Growth rates in pediatric dialysis patients and renal transplant recipients.

    PubMed

    Turenne, M N; Port, F K; Strawderman, R L; Ettenger, R B; Alexander, S R; Lewy, J E; Jones, C A; Agodoa, L Y; Held, P J

    1997-08-01

    We compared growth rates by modality over a 6- to 14-month period in 1,302 US pediatric end-stage renal disese (ESRD) patients treated during 1990. Modality comparisons were adjusted for age, sex, race, ethnicity, and ESRD duration using linear regression models by age group (0.5 to 4 years, 5 to 9 years, 10 to 14 years, and 15 to 18 years). Growth rates were higher in young children receiving a transplant compared with those receiving dialysis (ages 0.5 to 4 years, delta = 3.1 cm/yr v continuous cycling peritoneal dialysis [CCPD], P < 0.01; ages 5 to 9 years, delta = 2.0 to 2.6 cm/yr v CCPD, chronic ambulatory peritoneal dialysis (CAPD), and hemodialysis, P < 0.01). In contrast, growth rates in older children were not statistically different when comparing transplantation with each dialysis modality. For most age groups of transplant recipients, we observed faster growth with alternate-day versus daily steroids that was not fully explained by differences in allograft function. Younger patients (<15 years) grew at comparable rates with each dialysis modality, while older CAPD patients grew faster compared with hemodialysis or CCPD patients (P < 0.02). There was no substantial pubertal growth spurt in transplant or dialysis patients. This national US study of pediatric growth rates with dialysis and transplantation shows differences in growth by modality that vary by age group.

  15. A model to calculate the induced dose rate around an 18 MV ELEKTA linear accelerator.

    PubMed

    Perrin, Bruce; Walker, Anne; Mackay, Ranald

    2003-03-07

    The dose rate due to activity induced by (gamma, n) reactions around an ELEKTA Precise accelerator running at 18 MV is reported. A model to calculate the induced dose rate for a variety of working practices has been derived and compared to the measured values. From this model, the dose received by the staff using the machine can be estimated. From measured dose rates at the face of the linear accelerator for a 10 x 10 cm2 jaw setting at 18 MV an activation coefficient per MU was derived for each of the major activation products. The relative dose rates at points around the linac head, for different energy and jaw settings, were measured. Dose rates adjacent to the patient support system and portal imager were also measured. A model to calculate the dose rate at these points was derived, and compared to those measured over a typical working week. The model was then used to estimate the maximum dose to therapists for the current working schedule on this machine. Calculated dose rates at the linac face agreed to within +/- 12% of those measured over a week, with a typical dose rate of 4.5 microSv h(-1) 2 min after the beam has stopped. The estimated maximum annual whole body dose for a treatment therapist, with the machine treating at only 18 MV, for 60000 MUs per week was 2.5 mSv. This compares well with value of 2.9 mSv published for a Clinac 21EX. A model has been derived to calculate the dose from the four dominant activation products of an ELEKTA Precise 18 MV linear accelerator. This model is a useful tool to calculate the induced dose rate around the treatment head. The model can be used to estimate the dose to the staff for typical working patterns.

  16. Global evidence on the distribution of firm growth rates

    NASA Astrophysics Data System (ADS)

    Williams, Michael A.; Pinto, Brijesh P.; Park, David

    2015-08-01

    The consensus finding in the literature is that the distribution of firm growth rates is best approximated by the Laplace distribution, a particular case of the Subbotin, or exponential power, family of probability distributions. Using a richer database than prior studies and testing for more theoretical distributions, we find that the distribution of firm growth rates is best approximated by the heavier-tailed Cauchy distribution.

  17. Growth rate of Enterobacteriaceae at elevated temperatures: limitation by methionine.

    PubMed

    Ron, E Z

    1975-10-01

    The effect of elevated temperatures on growth rate was studied in five strains of Enterobacteriaceae. In all the strains tested a shift to the elevated temperature resulted in an immediate decrease in growth rate which was due to limitation in the availability of endogenous methionine. The first biosynthetic enzyme of the methionine pathway-homoserine transsuccinylase-was studied in extracts of Aerobacter aerogenes, Salmonella typhimurium, and Escherichia coli and was shown to be temperature sensitive in all of them.

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

    PubMed Central

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

    2014-01-01

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

  19. Deformation of Platonic foam cells: effect on growth rate.

    PubMed

    Evans, Myfanwy E; Zirkelbach, Johannes; Schröder-Turk, Gerd E; Kraynik, Andrew M; Mecke, Klaus

    2012-06-01

    The diffusive growth rate of a polyhedral cell in dry three-dimensional foams depends on details of shape beyond cell topology, in contrast to the situation in two dimensions, where, by von Neumann's law, the growth rate depends only on the number of cell edges. We analyze the dependence of the instantaneous growth rate on the shape of single foam cells surrounded by uniform pressure; this is accomplished by supporting the cell with films connected to a wire frame and inducing cell distortions by deforming the wire frame. We consider three foam cells with a very simple topology; these are the Platonic foam cells, which satisfy Plateau's laws and are based on the trivalent Platonic solids (tetrahedron, cube, and dodecahedron). The Surface Evolver is used to model cell deformations induced through extension, compression, shear, and torsion of the wire frames. The growth rate depends on the deformation mode and frame size and can increase or decrease with increasing cell distortion. The cells have negative growth rates, in general, but dodecahedral cells subjected to torsion in small wire frames can have positive growth rates. The deformation of cubic cells is demonstrated experimentally.

  20. Deformation of Platonic foam cells: Effect on growth rate

    NASA Astrophysics Data System (ADS)

    Evans, Myfanwy E.; Zirkelbach, Johannes; Schröder-Turk, Gerd E.; Kraynik, Andrew M.; Mecke, Klaus

    2012-06-01

    The diffusive growth rate of a polyhedral cell in dry three-dimensional foams depends on details of shape beyond cell topology, in contrast to the situation in two dimensions, where, by von Neumann's law, the growth rate depends only on the number of cell edges. We analyze the dependence of the instantaneous growth rate on the shape of single foam cells surrounded by uniform pressure; this is accomplished by supporting the cell with films connected to a wire frame and inducing cell distortions by deforming the wire frame. We consider three foam cells with a very simple topology; these are the Platonic foam cells, which satisfy Plateau's laws and are based on the trivalent Platonic solids (tetrahedron, cube, and dodecahedron). The Surface Evolver is used to model cell deformations induced through extension, compression, shear, and torsion of the wire frames. The growth rate depends on the deformation mode and frame size and can increase or decrease with increasing cell distortion. The cells have negative growth rates, in general, but dodecahedral cells subjected to torsion in small wire frames can have positive growth rates. The deformation of cubic cells is demonstrated experimentally.

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

    PubMed

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Meyer, H. J.

    1984-05-01

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

  3. Accelerated high-frame-rate mouse heart cine-MRI using compressed sensing reconstruction.

    PubMed

    Motaal, Abdallah G; Coolen, Bram F; Abdurrachim, Desiree; Castro, Rui M; Prompers, Jeanine J; Florack, Luc M J; Nicolay, Klaas; Strijkers, Gustav J

    2013-04-01

    We introduce a new protocol to obtain very high-frame-rate cinematographic (Cine) MRI movies of the beating mouse heart within a reasonable measurement time. The method is based on a self-gated accelerated fast low-angle shot (FLASH) acquisition and compressed sensing reconstruction. Key to our approach is that we exploit the stochastic nature of the retrospective triggering acquisition scheme to produce an undersampled and random k-t space filling that allows for compressed sensing reconstruction and acceleration. As a standard, a self-gated FLASH sequence with a total acquisition time of 10 min was used to produce single-slice Cine movies of seven mouse hearts with 90 frames per cardiac cycle. Two times (2×) and three times (3×) k-t space undersampled Cine movies were produced from 2.5- and 1.5-min data acquisitions, respectively. The accelerated 90-frame Cine movies of mouse hearts were successfully reconstructed with a compressed sensing algorithm. The movies had high image quality and the undersampling artifacts were effectively removed. Left ventricular functional parameters, i.e. end-systolic and end-diastolic lumen surface areas and early-to-late filling rate ratio as a parameter to evaluate diastolic function, derived from the standard and accelerated Cine movies, were nearly identical.

  4. Sensory Constraints on Birdsong Syntax: Neural Responses to Swamp Sparrow Songs with Accelerated Trill Rates.

    PubMed

    Prather, Jf; Peters, S; Mooney, R; Nowicki, S

    2012-06-01

    Both sensory and motor mechanisms can constrain behavioral performance. Sensory mechanisms may be especially important for constraining behaviors that depend on experience, such as learned birdsongs. Swamp sparrows learn to sing by imitating the song of a tutor, but sparrows fail to accurately imitate artificial tutor songs with abnormally accelerated trills, instead singing brief and rapid trills interrupted by silent gaps. This "broken syntax" has been proposed to arise from vocal-motor limitations. Here we consider whether sensory limitations exist that could also contribute to broken syntax. We tested this idea by recording auditory-evoked activity of sensorimotor neurons in the swamp sparrow's brain that are known to be important for the learning, performance and perception of song. In freely behaving adult sparrows that sang songs with normal syntax, neurons were detected that exhibited precisely time-locked activity to each repetition of the syllable in a trill when presented at a natural rate. Those cells failed to faithfully follow syllables presented at an accelerated rate, however, and their failure to respond to consecutive syllables increased as a function of trill rate. This "flickering" auditory representation in animals performing normal syntax reveals a central constraint on the sensory processing of rapid trills. Furthermore, because these neurons are implicated in both song learning and perception, and because auditory flickering began to occur at accelerated trill rates previously associated with the emergence of broken song syntax, these sensory constraints may contribute to the emergence of broken syntax.

  5. Sensory Constraints on Birdsong Syntax: Neural Responses to Swamp Sparrow Songs with Accelerated Trill Rates

    PubMed Central

    Prather, JF; Peters, S; Mooney, R; Nowicki, S

    2013-01-01

    Both sensory and motor mechanisms can constrain behavioral performance. Sensory mechanisms may be especially important for constraining behaviors that depend on experience, such as learned birdsongs. Swamp sparrows learn to sing by imitating the song of a tutor, but sparrows fail to accurately imitate artificial tutor songs with abnormally accelerated trills, instead singing brief and rapid trills interrupted by silent gaps. This “broken syntax” has been proposed to arise from vocal-motor limitations. Here we consider whether sensory limitations exist that could also contribute to broken syntax. We tested this idea by recording auditory-evoked activity of sensorimotor neurons in the swamp sparrow’s brain that are known to be important for the learning, performance and perception of song. In freely behaving adult sparrows that sang songs with normal syntax, neurons were detected that exhibited precisely time-locked activity to each repetition of the syllable in a trill when presented at a natural rate. Those cells failed to faithfully follow syllables presented at an accelerated rate, however, and their failure to respond to consecutive syllables increased as a function of trill rate. This “flickering” auditory representation in animals performing normal syntax reveals a central constraint on the sensory processing of rapid trills. Furthermore, because these neurons are implicated in both song learning and perception, and because auditory flickering began to occur at accelerated trill rates previously associated with the emergence of broken song syntax, these sensory constraints may contribute to the emergence of broken syntax. PMID:23976787

  6. Recent acceleration in coastal cliff retreat rates on the south coast of Great Britain.

    PubMed

    Hurst, Martin D; Rood, Dylan H; Ellis, Michael A; Anderson, Robert S; Dornbusch, Uwe

    2016-11-22

    Rising sea levels and increased storminess are expected to accelerate the erosion of soft-cliff coastlines, threatening coastal infrastructure and livelihoods. To develop predictive models of future coastal change we need fundamentally to know how rapidly coasts have been eroding in the past, and to understand the driving mechanisms of coastal change. Direct observations of cliff retreat rarely extend beyond 150 y, during which humans have significantly modified the coastal system. Cliff retreat rates are unknown in prior centuries and millennia. In this study, we derived retreat rates of chalk cliffs on the south coast of Great Britain over millennial time scales by coupling high-precision cosmogenic radionuclide geochronology and rigorous numerical modeling. Measured (10)Be concentrations on rocky coastal platforms were compared with simulations of coastal evolution using a Monte Carlo approach to determine the most likely history of cliff retreat. The (10)Be concentrations are consistent with retreat rates of chalk cliffs that were relatively slow (2-6 cm⋅y(-1)) until a few hundred years ago. Historical observations reveal that retreat rates have subsequently accelerated by an order of magnitude (22-32 cm⋅y(-1)). We suggest that acceleration is the result of thinning of cliff-front beaches, exacerbated by regional storminess and anthropogenic modification of the coast.

  7. Recent acceleration in coastal cliff retreat rates on the south coast of Great Britain

    NASA Astrophysics Data System (ADS)

    Hurst, Martin D.; Rood, Dylan H.; Ellis, Michael A.; Anderson, Robert S.; Dornbusch, Uwe

    2016-11-01

    Rising sea levels and increased storminess are expected to accelerate the erosion of soft-cliff coastlines, threatening coastal infrastructure and livelihoods. To develop predictive models of future coastal change we need fundamentally to know how rapidly coasts have been eroding in the past, and to understand the driving mechanisms of coastal change. Direct observations of cliff retreat rarely extend beyond 150 y, during which humans have significantly modified the coastal system. Cliff retreat rates are unknown in prior centuries and millennia. In this study, we derived retreat rates of chalk cliffs on the south coast of Great Britain over millennial time scales by coupling high-precision cosmogenic radionuclide geochronology and rigorous numerical modeling. Measured 10Be concentrations on rocky coastal platforms were compared with simulations of coastal evolution using a Monte Carlo approach to determine the most likely history of cliff retreat. The 10Be concentrations are consistent with retreat rates of chalk cliffs that were relatively slow (2-6 cmṡy-1) until a few hundred years ago. Historical observations reveal that retreat rates have subsequently accelerated by an order of magnitude (22-32 cmṡy-1). We suggest that acceleration is the result of thinning of cliff-front beaches, exacerbated by regional storminess and anthropogenic modification of the coast.

  8. A comparison of constant acceleration swimming speeds when acceleration rates are different with critical swimming speeds in Chinese bream under two oxygen tensions.

    PubMed

    Wang, Jian-Wei; Cao, Zhen-Dong; Fu, Shi-Jian

    2016-10-01

    To investigate the effect of acceleration rates on the constant acceleration test speed (U cat) and to compare U cat with the critical swimming speed (U crit) in Chinese bream (Parabramis pekinensis), the U cat test at acceleration rates of 0.05, 0.1, 0.2, 0.4 and 0.8 cm s(-2) and the U crit test in juvenile fish at 20 °C in either normoxia (>90 % saturation oxygen tension) or hypoxia (30 % saturation) were compared. The lactate concentration ([lactate]) of white muscle, liver and plasma and the glycogen concentration ([glycogen]) of white muscle and liver were also measured to identify whether tissue substrate depletion or tissue lactate accumulation correlated with exhaustion. The U cat decreased with the acceleration rate, and there was no significant difference between U crit and U cat at lower acceleration rates. Hypoxia resulted in lower U cat and U crit, and the difference increased with decreased acceleration rates of the U cat test, possibly due to the increased contribution of aerobic components in U crit or U cat at low acceleration rates. Hypoxia elicited a significant decrease in muscle [glycogen] and an increase in muscle and liver [lactate] in resting fish. All post-exercise fish had similar muscle [lactate], suggesting that tissue lactate accumulation may correlate with exercise exhaustion. Unlike hypoxia, exercise induced an increase in muscle [lactate] and a significant increase in plasma [lactate], which were worthy of further investigation. The similar swimming speed and biochemical indicators after exercise in the U crit and U cat groups at low acceleration rates suggested that U cat can be an alternative for the more frequently adopted protocols in U crit in Chinese bream and possibly in other cyprinid fish species.

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

    USGS Publications Warehouse

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

    2011-01-01

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

  10. Anthropogenic and biophysical contributions to increasing atmospheric CO2 growth rate and airborne fraction

    NASA Astrophysics Data System (ADS)

    Raupach, M. R.; Canadell, J. G.; Le Quéré, C.

    2008-07-01

    We quantify the relative roles of natural and anthropogenic influences on the growth rate of atmospheric CO2 and the CO2 airborne fraction, considering both interdecadal trends and interannual variability. A combined ENSO-Volcanic Index (EVI) relates most (~75%) of the interannual variability in CO2 growth rate to the El-Niño-Southern-Oscillation (ENSO) climate mode and volcanic activity. Analysis of several CO2 data sets with removal of the EVI-correlated component confirms a previous finding of a detectable increasing trend in CO2 airborne fraction (defined using total anthropogenic emissions including fossil fuels and land use change) over the period 1959 2006, at a proportional growth rate 0.24% y-1 with probability ~0.9 of a positive trend. This implies that the atmospheric CO2 growth rate increased slightly faster than total anthropogenic CO2 emissions. An extended form of the Kaya identity relates the increase in the CO2 growth rate (1.9% y-1 over 1959 2006) to the growth rates of four global driving factors: population (contributing +1.7% y-1); per capita income (+1.8% y-1); the total carbon intensity of the global economy (-1.7% y-1); and airborne fraction (averaging +0.2% y-1 with strong interannual variability). Together, the recent (post-2000) increase in growth of per capita income and decline in the negative growth (improvement) in the carbon intensity of the economy will drive a significant acceleration in the CO2 growth rate over coming decades, unless these recent trends reverse. To achieve an annual reduction rate in total emissions of -2% y-1 (which would halve emissions in 35 years) in the presence of a per-capita income growth rate of 2% y-1 and a population growth rate of 1% y-1, it is necessary to achieve a decline in total carbon intensity of the economy at a rate of around -5% y-1, three times the 1959 2006 average.

  11. Low energy emulsion-based fermentation enabling accelerated methane mass transfer and growth of poly(3-hydroxybutyrate)-accumulating methanotrophs.

    PubMed

    Myung, Jaewook; Kim, Minkyu; Pan, Ming; Criddle, Craig S; Tang, Sindy K Y

    2016-05-01

    Methane is a low-cost feedstock for the production of polyhydroxyalkanoate biopolymers, but methanotroph fermentations are limited by the low solubility of methane in water. To enhance mass transfer of methane to water, vigorous mixing or agitation is typically used, which inevitably increases power demand and operational costs. This work presents a method for accelerating methane mass transfer without agitation by growing methanotrophs in water-in-oil emulsions, where the oil has a higher solubility for methane than water does. In systems without agitation, the growth rate of methanotrophs in emulsions is five to six times that of methanotrophs in the medium-alone incubations. Within seven days, cells within the emulsions accumulate up to 67 times more P3HB than cells in the medium-alone incubations. This is achieved due to the increased interfacial area of the aqueous phase, and accelerated methane diffusion through the oil phase.

  12. The Role of Cracks in Accelerating the Rate of Landslide Movement

    NASA Astrophysics Data System (ADS)

    Weirich, F. H.; Blesius, L.

    2013-12-01

    The mechanisms responsible for deep seated landslides often involve the complex interplay of a number of factors that contribute to the initiation, accelerated rates of movement, and often catastrophic failures associated with these types of mass movement processes. One of the challenges associated with the study of such events is the determination of the trigger mechanism that tips the scale in favor of movement, accelerated movement, or catastrophic failure. Much research has been directed at the role of a number of factors such as: basic geology, failure zones, preferential slide planes,vegetative root strength, rainfall amounts, rates and basic infiltration dynamics that may contribute to movement or failure, or at times even serve as the primary forcing mechanism leading to failure or accelerated movement. However, the role of surface cracks in impacting the hydrologic balance of a hillslope and ultimately the stability of a hillside has received relatively little attention. In an effort to better understand the potential role of surface cracks in altering the hydrologic balance and ultimately the stability and rate of movement of deep seated slope failures, an evaluation of a relatively large scale landslide in Los Flores Canyon, Malibu, CA was undertaken. The Los Flores Canyon slide area encompasses an area in excess of 50 acres (+ 200,000 m2), with an overall slide volume in excess of 25 M cubic meters. Over the years, it has undergone wide and often relatively rapid variation in movement rates with toe movement rates ranging from under 0.3 m/yr up to rates exceeding 2.5 m/yr. Local rates on major portions of the slide surface have exceeded 25 m/yr at times. Combining basic geologic, rainfall, urban runoff, fire, and landslide movement data with a careful GIS based evaluation of the initiation and development of crack systems on the slide mass it was determined that in some instances, once the initial movement of the slide had begun, some of the subsequent

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

    NASA Astrophysics Data System (ADS)

    Nudelman, I.

    1993-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

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

    PubMed Central

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

    2014-01-01

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

  16. Growth-rate influences on coral climate proxies

    NASA Astrophysics Data System (ADS)

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

    2011-12-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

  18. Acceleration of ventricular rate by fibrillation associated with the Wolff-Parkinson-White syndrome.

    PubMed

    Sheinman, B D; Evans, T

    1982-10-09

    Amiodarone has proved to be a valuable drug in atrial fibrillation associated with the Wolff-Parkinson-White syndrome. When it was administered to a patient with this syndrome in atrial fibrillation, who had previously suffered an inferior myocardial infarction, the ventricular rate accelerated from 170 to 230 beats/minute.This unusual case emphasises the need for full electrophysiological assessment of patients with the Wolff-Parkinson-White syndrome for whom amiodarone treatment is being considered.

  19. Application of Rate Theory to Accelerated Durability Testing of Structural Adhesives

    DTIC Science & Technology

    1980-03-01

    comes too late to impact on material selection or design considerations. The analytical approach, coupled with an accelerated 10 testing program, is...estimated range and then evaluating the impact of each parameter on the failure rate and expected service life. The life-limiting components and the...interest of processing economy can be identified. This information can then be fed back into the system design process and the analyses repeated to

  20. Modeling Neisseria meningitidis B metabolism at different specific growth rates.

    PubMed

    Baart, Gino J E; Willemsen, Marieke; Khatami, Elnaz; de Haan, Alex; Zomer, Bert; Beuvery, E Coen; Tramper, Johannes; Martens, Dirk E

    2008-12-01

    Neisseria meningitidis is a human pathogen that can infect diverse sites within the human host. The major diseases caused by N. meningitidis are responsible for death and disability, especially in young infants. At the Netherlands Vaccine Institute (NVI) a vaccine against serogroup B organisms is currently being developed. This study describes the influence of the growth rate of N. meningitidis on its macro-molecular composition and its metabolic activity and was determined in chemostat cultures. In the applied range of growth rates, no significant changes in RNA content and protein content with growth rate were observed in N. meningitidis. The DNA content in N. meningitidis was somewhat higher at the highest applied growth rate. The phospholipid and lipopolysaccharide content in N. meningitidis changed with growth rate but no specific trends were observed. The cellular fatty acid composition and the amino acid composition did not change significantly with growth rate. Additionally, it was found that the PorA content in outer membrane vesicles was significantly lower at the highest growth rate. The metabolic fluxes at various growth rates were calculated using flux balance analysis. Errors in fluxes were calculated using Monte Carlo Simulation and the reliability of the calculated flux distribution could be indicated, which has not been reported for this type of analysis. The yield of biomass on substrate (Y(x/s)) and the maintenance coefficient (m(s)) were determined as 0.44 (+/-0.04) g g(-1) and 0.04 (+/-0.02) g g(-1) h(-1), respectively. The growth associated energy requirement (Y(x/ATP)) and the non-growth associated ATP requirement for maintenance (m(ATP)) were estimated as 0.13 (+/-0.04) mol mol(-1) and 0.43 (+/-0.14) mol mol(-1) h(-1), respectively. It was found that the split ratio between the Entner-Doudoroff and the pentose phosphate pathway, the sole glucose utilizing pathways in N. meningitidis, had a minor effect on ATP formation rate but a major

  1. Ambient dose and dose rate measurements in the vicinity of Elekta Precise accelerators for radiation therapy.

    PubMed

    Zutz, H; Hupe, O

    2014-12-01

    In radiation therapy, commercially available medical linear accelerators (LINACs) are used. At high primary beam energies in the 10-MeV range, the leakage dose of the accelerator head and the backscatter from the room walls, the air and the patient become more important. Therefore, radiation protection measurements of photon dose rates in the treatment room and in the maze are performed to quantify the radiation field. Since the radiation of the LINACs is usually pulsed with short radiation pulse durations in the microsecond range, there are problems with electronic dose (rate) meters commonly used in radiation protection. In this paper measurements with ionisation chambers are presented and electronic dosemeters are used for testing at selected positions. The measured time-averaged dose rate ranges from a few microsieverts per hour in the maze to some millisieverts per hour in the vicinity of the accelerator head and up to some sieverts per hour in the blanked primary beam and several hundred sieverts per hour in the direct primary beam.

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

    PubMed

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

    2013-04-01

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

  3. Growth of (101) faces of tetragonal lysozyme crystals: measured growth-rate trends

    NASA Technical Reports Server (NTRS)

    Forsythe, E. L.; Nadarajah, A.; Pusey, M. L.

    1999-01-01

    Previous extensive measurements of the growth rates of the (110) face of tetragonal lysozyme crystals have shown unexpected dependencies on the supersaturation. In this study, similar growth-rate measurements were performed for the (101) faces of the crystals. The data show a similar dependence on the supersaturation, becoming appreciable only at high supersaturations, reaching a maximum value and then decreasing. The (101) growth rates are larger at low supersaturations than the (110) growth rates under the same conditions and are smaller at high supersaturations. These trends suggest that the growth mechanism of the (101) face is similar to that of the (110) face: both processes involve the addition of multimeric growth units formed in solution, but the average size of the units for the (101) face is likely to be smaller than for the (110) face.

  4. Growth of (101) Faces of Tetragonal Lysozyme Crystals: Measured Growth Rate Trends

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

    Earlier extensive measurements of the growth rates of the (110) face of tetragonal lysozyme crystals had shown unexpected dependencies on the supersaturation. In this study similar growth rate measurements were done for the (101) faces of the crystals. The data show a similar dependence on the supersaturation, becoming appreciable only at high supersaturations, reaching a maximum value and then decreasing. As reported in earlier studies, the (101) growth rates are larger at low supersaturations than the (110) growth rates at the same conditions, and smaller at high supersaturations. These trends suggest that the growth mechanism of the (101) is similar to that of the (110) face, involving the addition of lysozyme aggregates formed in solution, but with a growth unit smaller than that of the (110) face.

  5. Application of a statistical bootstrapping technique to calculate growth rate variance for modelling psychrotrophic pathogen growth.

    PubMed

    Schaffner, D W

    1994-12-01

    The inherent variability or 'variance' of growth rate measurements is critical to the development of accurate predictive models in food microbiology. A large number of measurements are typically needed to estimate variance. To make these measurements requires a significant investment of time and effort. If a single growth rate determination is based on a series of independent measurements, then a statistical bootstrapping technique can be used to simulate multiple growth rate measurements from a single set of experiments. Growth rate variances were calculated for three large datasets (Listeria monocytogenes, Listeria innocua, and Yersinia enterocolitica) from our laboratory using this technique. This analysis revealed that the population of growth rate measurements at any given condition are not normally distributed, but instead follow a distribution that is between normal and Poisson. The relationship between growth rate and temperature was modeled by response surface models using generalized linear regression. It was found that the assumed distribution (i.e. normal, Poisson, gamma or inverse normal) of the growth rates influenced the prediction of each of the models used. This research demonstrates the importance of variance and assumptions about the statistical distribution of growth rates on the results of predictive microbiological models.

  6. A synthesis of growth rates in marine epipelagic invertebrate zooplankton.

    PubMed

    Hirst, A G; Roff, J C; Lampitt, R S

    2003-01-01

    We present the most extensive study to date of globally compiled and analysed weight-specific growth rates in marine epi-pelagic invertebrate metazoan zooplankton. Using specified selection criteria, we analyse growth rates from a variety of zooplanktonic taxa, including both holo- and mero-planktonic forms, from over 110 published studies. Nine principal taxonomic groups are considered, the copepods (number of individual data points (n) = 2,528); crustaceans other than copepods (n = 253); cnidarians (n = 77); ctenophores (n = 27); chaetognaths (n = 87); pteropods (n = 8); polychaetes (n = 12); thaliaceans (n = 88); and larvaceans (n = 91). The copepods are further examined by subdividing them into broadcasters or sac-spawning species, and as nauplii (N1-N6), copepodites (C1-C5) and adults (C6). For each taxonomic group relationships between growth, temperature and body weight are examined using a variety of methods. Weight-specific growth tends to increase with increasing temperature and with decreasing body weight in the crustacean group. Growth does not relate to body weight in the case of chaetognaths and larvaceans, but does increase with temperature. In the cnidarian and ctenophore groups growth does not relate to temperature, but is negatively related to body size. For the thaliceans growth increases with both increasing body weight and temperature. In the entire broadcasting copepod data set, weight-specific growth increases with increasing temperature and decreasing body weight. In sac-spawners, growth increases with increasing temperature, and increases with decreasing body weight at temperatures below 20 degrees C, but decreases with body weight at temperatures above this. Comparison between the different taxa shows important differences and similarities. Our extensive synthesis of data generally confirms that larvaceans, pteropods, cnidarians and ctenophores have rates of weight-specific growth that are typically greater than the copepods, chaetognaths

  7. Stringent restriction from the growth of large-scale structure on apparent acceleration in inhomogeneous cosmological models.

    PubMed

    Ishak, Mustapha; Peel, Austin; Troxel, M A

    2013-12-20

    Probes of cosmic expansion constitute the main basis for arguments to support or refute a possible apparent acceleration due to different expansion rates in the Universe as described by inhomogeneous cosmological models. We present in this Letter a separate argument based on results from an analysis of the growth rate of large-scale structure in the Universe as modeled by the inhomogeneous cosmological models of Szekeres. We use the models with no assumptions of spherical or axial symmetries. We find that while the Szekeres models can fit very well the observed expansion history without a Λ, they fail to produce the observed late-time suppression in the growth unless Λ is added to the dynamics. A simultaneous fit to the supernova and growth factor data shows that the cold dark matter model with a cosmological constant (ΛCDM) provides consistency with the data at a confidence level of 99.65%, while the Szekeres model without Λ achieves only a 60.46% level. When the data sets are considered separately, the Szekeres with no Λ fits the supernova data as well as the ΛCDM does, but provides a very poor fit to the growth data with only 31.31% consistency level compared to 99.99% for the ΛCDM. This absence of late-time growth suppression in inhomogeneous models without a Λ is consolidated by a physical explanation.

  8. The Formalism for Energy Changing Rate of an Accelerated Atom Coupled with Electromagnetic Vacuum Fluctuations

    NASA Astrophysics Data System (ADS)

    Zhang, Anwei

    2016-09-01

    The structure of the rate of variation of the atomic energy for an arbitrary stationary motion of the atom in interaction with a quantum electromagnetic field is investigated. Our main purpose is to rewrite the formalism in Zhu et al. (Phys Rev D 73:107501, 2006) and to deduce the general expressions of the Einstein A coefficients of an atom on an arbitrary stationary trajectory. The total rate of change of the energy and Einstein coefficients of the atom near a plate with finite temperature or acceleration are also investigated.

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

    USGS Publications Warehouse

    Das, Adrian

    2012-01-01

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

  10. MENTAL RETARDATION AND ACCELERATED GROWTH: INAPPROPRIATE SECRETION OF HUMAN GROWTH HORMONE,

    DTIC Science & Technology

    he had periodic elevations of the fasting plasma growth hormone levels and regularly had a paradoxical fall in the hormone level associated with...insulin-induced hypoglycemia. The human growth hormone response to arginine infusion was perfectly normal. It is suggested that the occasional elevations...in human growth hormone under fasting conditions and the paradoxical response to insulin are compatible with the hypothesis that this patient

  11. Early Acceleration of Mathematics Students and its Effect on Growth in Self-esteem: A Longitudinal Study

    NASA Astrophysics Data System (ADS)

    Ma, Xin

    2002-11-01

    The Longitudinal Study of American Youth (LSAY) database was employed to examine the educational practice of early acceleration of students of mathematics on the development of their self-esteem across the entire secondary grade levels. Students were classified into three different academic categories (gifted, honors, and regular). Results indicated that, in terms of the development of their self-esteem, gifted students benefited from early acceleration, honors students neither benefited nor were harmed by early acceleration, and regular students were harmed by early acceleration. Early acceleration in mathematics promoted significant growth in self-esteem among gifted male students and among gifted, honors, and regular minority students. When students were accelerated, schools showed similar average growth in self-esteem among gifted students and regular students and a large effect of general support for mathematics on the average growth in self-esteem among honors students.

  12. Arabidopsis thaliana root elongation growth is sensitive to lunisolar tidal acceleration and may also be weakly correlated with geomagnetic variations

    PubMed Central

    Barlow, Peter W.; Fisahn, Joachim; Yazdanbakhsh, Nima; Moraes, Thiago A.; Khabarova, Olga V.; Gallep, Cristiano M.

    2013-01-01

    Background Correlative evidence suggests a relationship between the lunisolar tidal acceleration and the elongation rate of arabidopsis roots grown under free-running conditions of constant low light. Methods Seedlings of Arabidopsis thaliana were grown in a controlled-climate chamber maintained at a constant temperature and subjected to continuous low-level illumination from fluorescent tubes, conditions that approximate to a ‘free-running’ state in which most of the abiotic factors that entrain root growth rates are excluded. Elongation of evenly spaced, vertical primary roots was recorded continuously over periods of up to 14 d using high temporal- and spatial-resolution video imaging and were analysed in conjunction with geophysical variables. Key Results and Conclusions The results confirm the lunisolar tidal/root elongation relationship. Also presented are relationships between the hourly elongation rates and the contemporaneous variations in geomagnetic activity, as evaluated from the disturbance storm time and ap indices. On the basis of time series of root elongation rates that extend over ≥4 d and recorded at different seasons of the year, a provisional conclusion is that root elongation responds to variation in the lunisolar force and also appears to adjust in accordance with variations in the geomagnetic field. Thus, both lunisolar tidal acceleration and the geomagnetic field should be considered as modulators of root growth rate, alongside other, stronger and more well-known abiotic environmental regulators, and perhaps unexplored factors such as air ions. Major changes in atmospheric pressure are not considered to be a factor contributing to oscillations of root elongation rate. PMID:23532042

  13. Growth rate in the dynamical dark energy models.

    PubMed

    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.

  14. Microbial Growth at Ultraslow Rates: Regulation and Genetic Stability.

    DTIC Science & Technology

    1983-03-01

    this taxonomic range of eubacteria , and the understanding we have gained of underlying biochemical and genetic machineries, it is clear that any...to eubacteria and whose effects on mu and Y, in fact, made the Monod-type equations invalid as soon as they were eluci- dated to the level reached by...growth parameters. Thus, we sought specifically: 1) to find if there was a pattern of growth behavior at slow rates common among eubacteria ; 2) to

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

    NASA Astrophysics Data System (ADS)

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

    2008-06-01

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

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

    PubMed

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

    2015-07-01

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

  17. Error-Rate Estimation Based on Multi-Signal Flow Graph Model and Accelerated Radiation Tests

    PubMed Central

    Wang, Yueke; Xing, Kefei; Deng, Wei; Zhang, Zelong

    2016-01-01

    A method of evaluating the single-event effect soft-error vulnerability of space instruments before launched has been an active research topic in recent years. In this paper, a multi-signal flow graph model is introduced to analyze the fault diagnosis and meantime to failure (MTTF) for space instruments. A model for the system functional error rate (SFER) is proposed. In addition, an experimental method and accelerated radiation testing system for a signal processing platform based on the field programmable gate array (FPGA) is presented. Based on experimental results of different ions (O, Si, Cl, Ti) under the HI-13 Tandem Accelerator, the SFER of the signal processing platform is approximately 10−3(error/particle/cm2), while the MTTF is approximately 110.7 h. PMID:27583533

  18. The origin of modern frogs (Neobatrachia) was accompanied by acceleration in mitochondrial and nuclear substitution rates

    PubMed Central

    2012-01-01

    Background Understanding the causes underlying heterogeneity of molecular evolutionary rates among lineages is a long-standing and central question in evolutionary biology. Although several earlier studies showed that modern frogs (Neobatrachia) experienced an acceleration of mitochondrial gene substitution rates compared to non-neobatrachian relatives, no further characterization of this phenomenon was attempted. To gain new insights on this topic, we sequenced the complete mitochondrial genomes and nine nuclear loci of one pelobatoid (Pelodytes punctatus) and five neobatrachians, Heleophryne regis (Heleophrynidae), Lechriodus melanopyga (Limnodynastidae), Calyptocephalella gayi (Calyptocephalellidae), Telmatobius bolivianus (Ceratophryidae), and Sooglossus thomasseti (Sooglossidae). These represent major clades not included in previous mitogenomic analyses, and most of them are remarkably species-poor compared to other neobatrachians. Results We reconstructed a fully resolved and robust phylogeny of extant frogs based on the new mitochondrial and nuclear sequence data, and dated major cladogenetic events. The reconstructed tree recovered Heleophryne as sister group to all other neobatrachians, the Australasian Lechriodus and the South American Calyptocephalella formed a clade that was the sister group to Nobleobatrachia, and the Seychellois Sooglossus was recovered as the sister group of Ranoides. We used relative-rate tests and direct comparison of branch lengths from mitochondrial and nuclear-based trees to demonstrate that both mitochondrial and nuclear evolutionary rates are significantly higher in all neobatrachians compared to their non-neobatrachian relatives, and that such rate acceleration started at the origin of Neobatrachia. Conclusions Through the analysis of the selection coefficient (ω) in different branches of the tree, we found compelling evidence of relaxation of purifying selection in neobatrachians, which could (at least in part) explain the

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

    SciTech Connect

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

    2006-01-13

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

  20. Brain growth rate abnormalities visualized in adolescents with autism.

    PubMed

    Hua, Xue; Thompson, Paul M; Leow, Alex D; Madsen, Sarah K; Caplan, Rochelle; Alger, Jeffry R; O'Neill, Joseph; Joshi, Kishori; Smalley, Susan L; Toga, Arthur W; Levitt, Jennifer G

    2013-02-01

    Autism spectrum disorder is a heterogeneous disorder of brain development with wide ranging cognitive deficits. Typically diagnosed before age 3, autism spectrum disorder is behaviorally defined but patients are thought to have protracted alterations in brain maturation. With longitudinal magnetic resonance imaging (MRI), we mapped an anomalous developmental trajectory of the brains of autistic compared with those of typically developing children and adolescents. Using tensor-based morphometry, we created 3D maps visualizing regional tissue growth rates based on longitudinal brain MRI scans of 13 autistic and seven typically developing boys (mean age/interscan interval: autism 12.0 ± 2.3 years/2.9 ± 0.9 years; control 12.3 ± 2.4/2.8 ± 0.8). The typically developing boys demonstrated strong whole brain white matter growth during this period, but the autistic boys showed abnormally slowed white matter development (P = 0.03, corrected), especially in the parietal (P = 0.008), temporal (P = 0.03), and occipital lobes (P = 0.02). We also visualized abnormal overgrowth in autism in gray matter structures such as the putamen and anterior cingulate cortex. Our findings reveal aberrant growth rates in brain regions implicated in social impairment, communication deficits and repetitive behaviors in autism, suggesting that growth rate abnormalities persist into adolescence. Tensor-based morphometry revealed persisting growth rate anomalies long after diagnosis, which has implications for evaluation of therapeutic effects.

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

    SciTech Connect

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

    2008-08-05

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

  2. Numerical analysis of the sensitivity of crystal growth experiments to spacecraft residual acceleration

    NASA Technical Reports Server (NTRS)

    Alexander, J. I. D.; Amiroudine, Sakir; Ouazzani, Jalil; Rosenberger, Franz

    1992-01-01

    An analysis is conducted of the sensitivity of the Bridgman-Stockbarger crystal growth method, using an idealized model for a range of operating and boundary conditions over a variety of accelerations. Attention is given to the dopant nonuniformity at the melt-crystal interface. The largest compositional nonuniformities are found to occur for disturbances whose amplitudes are greater than 10 exp 6 g, and frequencies below 0.1 Hz.

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

    PubMed

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

    2002-03-01

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

  4. Consequences of bounds on longitudinal emittance growth for the design of recirculating linear accelerators

    SciTech Connect

    Berg, J. S.

    2015-05-03

    Recirculating linear accelerators (RLAs) are a cost-effective method for the acceleration of muons for a muon collider in energy ranges from a couple GeV to a few 10s of GeV. Muon beams generally have longitudinal emittances that are large for the RF frequency that is used, and it is important to limit the growth of that longitudinal emittance. This has particular consequences for the arc design of the RLAs. I estimate the longitudinal emittance growth in an RLA arising from the RF nonlinearity. Given an emittance growth limitation and other design parameters, one can then compute the maximum momentum compaction in the arcs. I describe how to obtain an approximate arc design satisfying these requirements based on the deisgn in [1]. Longitudinal dynamics also determine the energy spread in the beam, and this has consequences on the transverse phase advance in the linac. This in turn has consequences for the arc design due to the need to match beta functions. I combine these considerations to discuss design parameters for the acceleration of muons for a collider in an RLA from 5 to 63 GeV.

  5. Universality of Thermodynamic Constants Governing Biological Growth Rates

    PubMed Central

    Corkrey, Ross; Olley, June; Ratkowsky, David; McMeekin, Tom; Ross, Tom

    2012-01-01

    Background Mathematical models exist that quantify the effect of temperature on poikilotherm growth rate. One family of such models assumes a single rate-limiting ‘master reaction’ using terms describing the temperature-dependent denaturation of the reaction's enzyme. We consider whether such a model can describe growth in each domain of life. Methodology/Principal Findings A new model based on this assumption and using a hierarchical Bayesian approach fits simultaneously 95 data sets for temperature-related growth rates of diverse microorganisms from all three domains of life, Bacteria, Archaea and Eukarya. Remarkably, the model produces credible estimates of fundamental thermodynamic parameters describing protein thermal stability predicted over 20 years ago. Conclusions/Significance The analysis lends support to the concept of universal thermodynamic limits to microbial growth rate dictated by protein thermal stability that in turn govern biological rates. This suggests that the thermal stability of proteins is a unifying property in the evolution and adaptation of life on earth. The fundamental nature of this conclusion has importance for many fields of study including microbiology, protein chemistry, thermal biology, and ecological theory including, for example, the influence of the vast microbial biomass and activity in the biosphere that is poorly described in current climate models. PMID:22348140

  6. Recombinant growth factor mixtures induce cell cycle progression and the upregulation of type I collagen in human skin fibroblasts, resulting in the acceleration of wound healing processes.

    PubMed

    Lee, Do Hyun; Choi, Kyung-Ha; Cho, Jae-We; Kim, So Young; Kwon, Tae Rin; Choi, Sun Young; Choi, Yoo Mi; Lee, Jay; Yoon, Ho Sang; Kim, Beom Joon

    2014-05-01

    Application of growth factor mixtures has been used for wound healing and anti-wrinkles agents. The aim of this study was to evaluate the effect of recombinant growth factor mixtures (RGFM) on the expression of cell cycle regulatory proteins, type I collagen, and wound healing processes of acute animal wound models. The results showed that RGFM induced increased rates of cell proliferation and cell migration of human skin fibroblasts (HSF). In addition, expression of cyclin D1, cyclin E, cyclin-dependent kinase (Cdk)4, and Cdk2 proteins was markedly increased with a growth factor mixtures treatment in fibroblasts. Expression of type I collagen was also increased in growth factor mixtures-treated HSF. Moreover, growth factor mixtures-induced the upregulation of type I collagen was associated with the activation of Smad2/3. In the animal model, RGFM-treated mice showed accelerated wound closure, with the closure rate increasing as early as on day 7, as well as re-epithelization and reduced inflammatory cell infiltration than phosphate-buffered saline (PBS)-treated mice. In conclusion, the results indicated that RGFM has the potential to accelerate wound healing through the upregulation of type I collagen, which is partly mediated by activation of Smad2/3-dependent signaling pathway as well as cell cycle progression in HSF. The topical application of growth factor mixtures to acute and chronic skin wound may accelerate the epithelization process through these molecular mechanisms.

  7. 3D fold growth rates in transpressional tectonic settings

    NASA Astrophysics Data System (ADS)

    Frehner, Marcel

    2015-04-01

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

  8. Evidence of accelerated beak growth associated with avian keratin disorder in black-capped chickadees (Poecile atricapillus)

    USGS Publications Warehouse

    Van Hemert, Caroline R.; Handel, Colleen M.; O'Hara, Todd M.

    2012-01-01

    We recently documented an epizootic of beak deformities in more than 2,000 Blackcapped Chickadees (Poecile atricapillus) and other wild bird species in North America. This emerging avian disease, which has been termed avian keratin disorder, results in gross overgrowth of the rhamphotheca, the outer, keratinized layer of the beak. To test the hypothesis that the beak deformities characteristic of this disorder are associated with accelerated keratin production, we measured rates of beak growth and wear in affected Black-capped Chickadees (n=16) and a control sample of unaffected chickadees (n=14) collected from south-central (61°09'-61°38'N, 149°11' -149°48'W) and interior Alaska (64°51' -64°53'N, 147°49' -147°59'W). Rates of absolute growth were 50-100% higher in affected birds than they were in control birds and exceeded records from other passerine species. These results suggest that abnormally rapid epidermal growth is the primary physical mechanism by which beak deformities develop and are maintained in affected chickadees. Although beak overgrowth typically worsened over time, differential patterns of wear influenced the severity and morphology of deformities. In some cases, the effects of accelerated keratin growth were partially mitigated by frequent breakage of rhamphothecal tips. However, mortalities occurred in 9 of 16 birds (56%) with beak deformities during the study, suggesting that avian keratin disorder results in severe health consequences for affected birds. Additional study of factors that control beak keratin production is needed to understand the pathogenesis of this debilitating disease in wild birds.

  9. Evidence of accelerated beak growth associated with avian keratin disorder in Black-capped Chickadees (Poecile atricapillus)

    USGS Publications Warehouse

    Van Hemert, Caroline; Handel, Colleen M.; O'Hara, Todd M.

    2012-01-01

    We recently documented an epizootic of beak deformities in more than 2,000 Blackcapped Chickadees (Poecile atricapillus) and other wild bird species in North America. This emerging avian disease, which has been termed avian keratin disorder, results in gross overgrowth of the rhamphotheca, the outer, keratinized layer of the beak. To test the hypothesis that the beak deformities characteristic of this disorder are associated with accelerated keratin production, we measured rates of beak growth and wear in affected Black-capped Chickadees (n=16) and a control sample of unaffected chickadees (n=14) collected from south-central (61°09′−61°38′N, 149°11′ −149°48′W) and interior Alaska (64°51′ −64°53′N, 147°49′ −147°59′W). Rates of absolute growth were 50–100% higher in affected birds than they were in control birds and exceeded records from other passerine species. These results suggest that abnormally rapid epidermal growth is the primary physical mechanism by which beak deformities develop and are maintained in affected chickadees. Although beak overgrowth typically worsened over time, differential patterns of wear influenced the severity and morphology of deformities. In some cases, the effects of accelerated keratin growth were partially mitigated by frequent breakage of rhamphothecal tips. However, mortalities occurred in 9 of 16 birds (56%) with beak deformities during the study, suggesting that avian keratin disorder results in severe health consequences for affected birds. Additional study of factors that control beak keratin production is needed to understand the pathogenesis of this debilitating disease in wild birds.

  10. In situ growth rate measurement of selective LPCVD of tungsten

    SciTech Connect

    Holleman, J.; Hasper, A.; Middelhoek, J. )

    1991-04-01

    This paper reports on the reflectance measurement during the selective deposition of W on Si covered with an insulator rating proven to be a convenient method to monitor the W deposition. The reflectance change during deposition allows the in situ measurement of the deposition rate. The influence of surface roughening due to either the W growth or an etching pretreatment of the wafer is modeled, as well as the effect of selectivity loss and lateral overgrowth.

  11. Accelerated Testing Methodology in Constant Stress-Rate Testing for Advanced Structural Ceramics: A Preloading Technique

    NASA Technical Reports Server (NTRS)

    Choi, Sung R.; Gyekenyesi, John P.; Huebert, Dean; Bartlett, Allen; Choi, Han-Ho

    2001-01-01

    Preloading technique was used as a means of an accelerated testing methodology in constant stress-rate ('dynamic fatigue') testing for two different brittle materials. The theory developed previously for fatigue strength as a function of preload was further verified through extensive constant stress-rate testing for glass-ceramic and CRT glass in room temperature distilled water. The preloading technique was also used in this study to identify the prevailing failure mechanisms at elevated temperatures, particularly at lower test rate in which a series of mechanisms would be associated simultaneously with material failure, resulting in significant strength increase or decrease. Two different advanced ceramics including SiC whisker-reinforced composite silicon nitride and 96 wt% alumina were used at elevated temperatures. It was found that the preloading technique can be used as an additional tool to pinpoint the dominant failure mechanism that is associated with such a phenomenon of considerable strength increase or decrease.

  12. Accelerated Testing Methodology in Constant Stress-Rate Testing for Advanced Structural Ceramics: A Preloading Technique

    NASA Technical Reports Server (NTRS)

    Choi, Sung R.; Gyekenyesi, John P.; Huebert, Dean; Bartlett, Allen; Choi, Han-Ho

    2001-01-01

    Preloading technique was used as a means of an accelerated testing methodology in constant stress-rate (dynamic fatigue) testing for two different brittle materials. The theory developed previously for fatigue strength as a function of preload was further verified through extensive constant stress-rate testing for glass-ceramic and CRT glass in room temperature distilled water. The preloading technique was also used in this study to identify the prevailing failure mechanisms at elevated temperatures, particularly at lower test rates in which a series of mechanisms would be associated simultaneously with material failure, resulting in significant strength increase or decrease. Two different advanced ceramics including SiC whisker-reinforced composite silicon nitride and 96 wt% alumina were used at elevated temperatures. It was found that the preloading technique can be used as an additional tool to pinpoint the dominant failure mechanism that is associated with such a phenomenon of considerable strength increase or decrease.

  13. Clinical evaluation of peak endocardial acceleration as a sensor for rate responsive pacing.

    PubMed

    Greco, Enrico Maria; Ferrario, Marco; Romano, Salvatore

    2003-04-01

    An innovative control parameter for rate responsive (RR) pacing that uses a sensor to measure mechanical vibrations generated by the myocardium during the isovolumetric contraction phase (peak endocardial acceleration [PEA]), has been devised by SORIN Biomedica (BEST Living System). To assess the physiological sensitivity of the pacemaker sensor along with reliability of the algorithm to supply appropriate pacing rates three different relationships were examined (linear regression analysis): (1) recorded deltaPEA exercise steps against the calculated energy cost of exercise (MET), (2) exercise pacing rates against predicted values, and (3) deltaPEA against exercise pacing rates. Fifteen patients (mean age 68 +/- 12 years) in NYHA Class I-II, implanted with the BEST Living System (Living 1 DDDR pacemaker) for advanced AVB and/or SSS, underwent one of the following maximal exercise stress protocols: bicycle (25 W, 2-minute steps) or Bruce or Chronotropic Assessment Exercise Protocol (CAEP). Pacing rates for each step were matched against those predicted by a reliable and tested custom software called Pacing Rate Profile Software (PRPS). The PRPS is based on the oxygen pulse reserve (OPR) method (OPR = VO2 reserve divided by heart rate reserve), American College of Sports Medicine (ACSM) formulas for calculating workload/metabolic requirements, and data derived from the Weber functional classes. On the basis of certain patient, data the PRPS then supplies appropriate metabolic pacing rate profiles. In all 15 patients linear regression analysis of deltaPEA against MET, as evaluated during the exercise protocol steps, showed a high correlation (r = 0.97). Likewise, a high correlation was also obtained between PRPS predicted heart rates and exercise pacing rates (r = 0.96) and PEA against exercise pacing rates (r = 0.96). The results of this study show that, through PEA dynamic monitoring, the SORIN Best Living System produces physiological pacing rates that are

  14. Rapid growth rates of aerobic anoxygenic phototrophs in the ocean.

    PubMed

    Koblízek, Michal; Masín, Michal; Ras, Josephine; Poulton, Alex J; Prásil, Ondrej

    2007-10-01

    We analysed bacteriochlorophyll diel changes to assess growth rates of aerobic anoxygenic phototrophs in the euphotic zone across the Atlantic Ocean. The survey performed during Atlantic Meridional Transect cruise 16 has shown that bacteriochlorophyll in the North Atlantic Gyre cycles at rates of 0.91-1.08 day(-1) and in the South Atlantic at rates of 0.72-0.89 day(-1). In contrast, in the more productive equatorial region and North Atlantic it cycled at rates of up to 2.13 day(-1). These results suggest that bacteriochlorophyll-containing bacteria in the euphotic zone of the oligotrophic gyres grow at rates of about one division per day and in the more productive regions up to three divisions per day. This is in striking contrast with the relatively slow growth rates of the total bacterial community. Thus, aerobic anoxygenic phototrophs appear to be a very dynamic part of the marine microbial community and due to their rapid growth, they are likely to be larger sinks for dissolved organic matter than their abundance alone would predict.

  15. Upscaling Calcite Growth Rates from the Mesoscale to the Macroscale

    SciTech Connect

    Bracco, Jacquelyn N.; Stack, Andrew G.; Steefel, Carl I.

    2013-07-02

    Quantitative prediction of mineral reaction rates in the subsurface remains a daunting task partly because a key parameter for macroscopic models, the reactive site density, is poorly constrained. Here we report atomic force microscopy (AFM) measurements on the calcite surface of monomolecular step densities, treated as equivalent to the reactive site density, as a function of aqueous calcium-to-carbonate ratio and saturation index. Data for the obtuse step orientation are combined with existing step velocity measurements to generate a model that predicts overall macroscopic calcite growth rates. The model is quantitatively consistent with several published macroscopic rates under a range of alkaline solution conditions, particularly for two of the most comprehensive data sets without the need for additional fit parameters. The model reproduces peak growth rates and its functional form is simple enough to be incorporated into reactive transport or other macroscopic models designed for predictions in porous media. However, it currently cannot model equilibrium, pH effects, and may overestimate rates at high aqueous calcium-to-carbonate ratios. The discrepancies in rates at high calcium-to-carbonate ratios may be due to differences in pre-treatment, such as exposing the seed material to SI 1.0 to generate/develop growth hillocks, or other factors.

  16. Determination of relative growth rates of natural quartz crystals

    PubMed

    Ihinger; Zink

    2000-04-20

    Although the theory describing crystal growth in the geological environment is well established, there are few quantitative studies that delimit the absolute time involved in the growth of natural crystals. The actual mechanisms responsible for the variation in size and shape of individual crystal faces are, in fact, not well understood. Here we describe a micro-infrared spectroscopic study of a single, gem-quality quartz crystal that allows us to measure the size, shape and relative growth rate of each of the crystal faces that are active throughout its growth history. We demonstrate that the abundances of hydrogen-bearing impurities can serve as 'speedometers' to monitor the growth rate of advancing crystal faces. Our technique can be applied to crystals from a variety of geological environments to determine their growth histories. Within the electronics industry, the technique might facilitate the production of defect-free synthetic crystals required for high-quality resonators and, ultimately, might allow determination of the absolute time involved in geological processes such as the crystallization of magmas, fluid flow in metamorphism and the sealing of open cracks in earthquake rupture zones.

  17. Age at first reproduction and growth rate are independent of basal metabolic rate in mammals.

    PubMed

    Lovegrove, Barry G

    2009-05-01

    This study tested an emergent prediction from the Metabolic Theory of Ecology (MTE) that the age at first reproduction (alpha) of a mammal is proportional to the inverse of its mass-corrected basal metabolic rate: alpha proportional (B / M)-1 The hypothesis was tested with multiple regression models of conventional species data and phylogenetically independent contrasts of 121 mammal species. Since age at first reproduction is directly influenced by an individual's growth rate, the hypothesis that growth rate is proportional to BMR was also tested. Although the overall multiple regression model was significant, age at first reproduction was not partially correlated with either body mass, growth rate or BMR. Similarly, growth rate was not correlated with BMR. Thus at least for mammals in general, there is no evidence to support the fundamental premise of the MTE that individual metabolism governs the rate at which energy is converted to growth and reproduction at the species level. The exponents of the BMR allometry calculated using phylogenetic generalized least squares regression models were significantly lower than the three-quarter value predicted by the MTE.

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

    PubMed

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

    2016-01-01

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

  19. Growth rate and cell size: a re-examination of the growth law.

    PubMed

    Vadia, Stephen; Levin, Petra Anne

    2015-04-01

    Research into the mechanisms regulating bacterial cell size has its origins in a single paper published over 50 years ago. In it Schaechter and colleagues made the observation that the chemical composition and size of a bacterial cell is a function of growth rate, independent of the medium used to achieve that growth rate, a finding that is colloquially referred to as 'the growth law'. Recent findings hint at unforeseen complexity in the growth law, and suggest that nutrients rather than growth rate are the primary arbiter of size. The emerging picture suggests that size is a complex, multifactorial phenomenon mediated through the varied impacts of central carbon metabolism on cell cycle progression and biosynthetic capacity.

  20. On the effect of accelerated winds on the wave growth through detailed laboratory measurements.

    NASA Astrophysics Data System (ADS)

    Ocampo-Torres, Francisco J.; Branger, Hubert; Osuna, Pedro; Hernández, Aldo

    2013-04-01

    The possible influence of accelerated winds on air-water momentum fluxes is being studied through detailed laboratory measurements in a large wind-wave flume. Wind stress over the water surface, waves and surface drift are measured in the 40m long wind-wave tank at IRPHE, Marseille. While momentum fluxes are estimated directly through the eddy correlation method in a station about the middle of the tank, they provide information corresponding to rather short non-dimensional fetch not previously reported. Wave evolution along the tank is determined through a series of wave gauges, and the wind-induced surface drift is obtained at one of the first measuring stations at the beginning of the tank. At each experimental run very low wind was on (about 1m/s) for a certain period and suddenly it was constantly accelerated to reach about 13 m/s (as well as 8 and 5 m/s during different runs) in about 15 sec to as long as 600 sec. The wind was kept constant at that high speed for 2 to 10 min, and then suddenly and constantly decelerate to 0. Data from the constant high winds provided us with reference equilibrium conditions for at least 3 different wind speed. We, nevertheless, focus in the recordings while wind was being constantly accelerated expecting some contribution to the understanding of gustiness, the implied wind wave growth and the onset of surface drift. Wind-wave growth is observed to lag behind the wind stress signal, and furthermore, a two regime wind stress is noticed, apparently well correlated with a) the incipient growth and appearance of the first waves and b) the arrival of waves from the up-wind section of the tank. Results of non-dimensional wave energy as a function of non-dimensional fetch represent an extension of at least 2 decades shorter non-dimensional fetch to the wave growth curves typically found in the literature. The linear tendency of wave growth compares very well only when wind is reaching its maximum, while during the accelerated wind

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

    NASA Technical Reports Server (NTRS)

    Mazuruk, K.; Volz, M. P.

    2010-01-01

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

  2. The effects of acceleration rate on vehicle exhaust emissions and fuel economy. Technical report

    SciTech Connect

    Landman, L.C.

    1982-08-01

    This report summarizes a test program which was designed to explore the impact on exhaust emissions and fuel economy of coupling the dynamometer rollers (front and rear) and of using acceleration rates higher than those used on the Federal Test Procedure (FTP). A total of six vehicles were tested in this program. All five gasoline-fueled exhibited increases in hydrocarbons (HC) and carbon monoxide (CO) emissions on the Federal Test Procedure (FTP) driving cycle when the dynamometer rollers were coupled. The other results are strongly vehicle dependent.

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

    PubMed

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

    2005-12-20

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

  4. Measuring the growth rate of structure around cosmic voids

    NASA Astrophysics Data System (ADS)

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

    2016-10-01

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

  5. Winter temperatures limit population growth rate of a migratory songbird

    PubMed Central

    Woodworth, Bradley K.; Wheelwright, Nathaniel T.; Newman, Amy E.; Schaub, Michael; Norris, D. Ryan

    2017-01-01

    Understanding the factors that limit and regulate wildlife populations requires insight into demographic and environmental processes acting throughout the annual cycle. Here, we combine multi-year tracking data of individual birds with a 26-year demographic study of a migratory songbird to evaluate the relative effects of density and weather at the breeding and wintering grounds on population growth rate. Our results reveal clear support for opposing forces of winter temperature and breeding density driving population dynamics. Above-average temperatures at the wintering grounds lead to higher population growth, primarily through their strong positive effects on survival. However, population growth is regulated over the long term by strong negative effects of breeding density on both fecundity and adult male survival. Such knowledge of how year-round factors influence population growth, and the demographic mechanisms through which they act, will vastly improve our ability to predict species responses to environmental change and develop effective conservation strategies for migratory animals. PMID:28317843

  6. Tuning calcite morphology and growth acceleration by a rational design of highly stable protein-mimetics

    SciTech Connect

    Chen, Chunlong; Qi, Jiahui; Tao, Jinhui; Zuckermann, Ronald; De Yoreo, James J.

    2014-09-05

    In nature, proteins play a significant role in biomineral formation. One of the ultimate goals of bioinspired materials science is to develop highly stable synthetic molecules that mimic the function of these natural proteins by controlling crystal formation. Here, we demonstrate that both the morphology and the degree of acceleration or inhibition observed during growth of calcite in the presence of peptoids can be rationally tuned by balancing the electrostatic interactions (EI) and hydrophobic interactions (HI), with HI playing the dominant role. While either strong EI or HI inhibit growth and suppress (104) face expression, correlations between peptoid-crystal binding energies and observed changes in calcite growth indicate moderate EI allow peptoids to weakly adsorb while moderate HI cause disruption of surface-adsorbed water layers, leading to growth acceleration with retained expression of (104) faces. This study provides fundamental principles for designing peptoids as crystallization promoters, and offers a straightforward screening method based on macroscopic crystal morphology. Because peptoids are sequence-specific, highly stable, and easily synthesized, peptoid-enhanced crystallization offers a broad range of potential applications.

  7. Scaling laws in the dynamics of crime growth rate

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

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

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

    PubMed

    Lindgren, B; Laurila, A

    2005-07-01

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

  9. Protein Degradation Rate in Arabidopsis thaliana Leaf Growth and Development.

    PubMed

    Li, Lei; Nelson, Clark J; Trösch, Josua; Castleden, Ian; Huang, Shaobai; Millar, A Harvey

    2017-02-01

    We applied (15)N labeling approaches to leaves of the Arabidopsis thaliana rosette to characterize their protein degradation rate and understand its determinants. The progressive labeling of new peptides with (15)N and measuring the decrease in the abundance of >60,000 existing peptides over time allowed us to define the degradation rate of 1228 proteins in vivo. We show that Arabidopsis protein half-lives vary from several hours to several months based on the exponential constant of the decay rate for each protein. This rate was calculated from the relative isotope abundance of each peptide and the fold change in protein abundance during growth. Protein complex membership and specific protein domains were found to be strong predictors of degradation rate, while N-end amino acid, hydrophobicity, or aggregation propensity of proteins were not. We discovered rapidly degrading subunits in a variety of protein complexes in plastids and identified the set of plant proteins whose degradation rate changed in different leaves of the rosette and correlated with leaf growth rate. From this information, we have calculated the protein turnover energy costs in different leaves and their key determinants within the proteome.

  10. Reaction Rate Acceleration and Tg Depression of Polycyanurate Under Nanopore Confinement

    NASA Astrophysics Data System (ADS)

    Lopez, Evelyn; Simon, Sindee L.

    2015-03-01

    Material properties such as Tg and the reaction kinetics are known to deviate from the bulk when subjected to nano-sized confinement. Previous work from our laboratory on the trimerization of cyanate esters found that the reaction kinetics were faster for a monofunctional reactant compared to a difunctional monomer, whereas the Tg depression was greater for the crosslinked product of the latter compared to the low molecular weight trimer of the former. The origin of the changes in nanoconfined reaction rates differs from those that govern changes in the Tg. The research objective is to further explore the effect that confinement has on reaction kinetics and Tg using a mixture consisting of mono- and di- cyanate ester monomers. The product is an uncrosslinked polycyanurate with Mn = 5240 g/mol and PDI = 1.78. The confinement mediums are controlled pore glasses with diameters ranging from 8.1 to 111.1 nm. The nanopore-confined material was synthesized in-situ and the reaction kinetics are followed by DSC; after the reaction, the Tg values of the nanoconfined polymer where also measured by DSC. An acceleration factor of 13 and a Tg depression of 38 °C are observed for the material confined in the smallest 8.1 nm-diameter pores. The Tg depression is between those of the trimer and network previously studied, while the acceleration of the reaction rate is lower. Our results are consistent with the reaction acceleration arising from packing effects at the pore wall and the Tg depression arising from intrinsic size effects.

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

    USGS Publications Warehouse

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

    1997-01-01

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

  12. Controlling growth rate anisotropy for formation of continuous ZnO thin films from seeded substrates

    NASA Astrophysics Data System (ADS)

    Zhang, R. H.; Slamovich, E. B.; Handwerker, C. A.

    2013-05-01

    Solution-processed zinc oxide (ZnO) thin films are promising candidates for low-temperature-processable active layers in transparent thin film electronics. In this study, control of growth rate anisotropy using ZnO nanoparticle seeds, capping ions, and pH adjustment leads to a low-temperature (90 ° C) hydrothermal process for transparent and high-density ZnO thin films. The common 1D ZnO nanorod array was grown into a 2D continuous polycrystalline film using a short-time pure solution method. Growth rate anisotropy of ZnO crystals and the film morphology were tuned by varying the chloride (Cl-) ion concentration and the initial pH of solutions of zinc nitrate and hexamethylenetetramine (HMTA), and the competitive adsorption effects of Cl- ions and HMTA ligands on the anisotropic growth behavior of ZnO crystals were proposed. The lateral growth of nanorods constituting the film was promoted by lowering the solution pH to accelerate the hydrolysis of HMTA, thereby allowing the adsorption effects from Cl- to dominate. By optimizing the growth conditions, a dense ˜100 nm thickness film was fabricated in 15 min from a solution of [Cl-]/[Zn2+] = 1.5 and pH= 4.8 ± 0.1. This film shows >80% optical transmittance and a field-effect mobility of 2.730 cm2 V-1 s-1 at zero back-gate bias.

  13. Education and Skills for Development in South Africa: Reflections on the Accelerated and Shared Growth Initiative for South Africa

    ERIC Educational Resources Information Center

    McGrath, S.; Akoojee, Salim

    2007-01-01

    In July 2005, President Mbeki announced the launch of the Accelerated and Shared Growth Initiative for South Africa (AsgiSA), a new development strategy designed to help the South African state meet the ANC's 2004 election pledges, namely: (1) halve unemployment; (2) halve poverty; (3) accelerate employment equity; and (4) improve broad-based…

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

    SciTech Connect

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

    2014-01-08

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

  15. In situ growth rate measurements by normal-incidence reflectance during MOVPE growth

    SciTech Connect

    Hou, H.Q.; Breiland, W.G.; Hammons, B.E.; Chui, H.C.

    1996-05-01

    We present an in situ technique for monitoring metal-organic vapor phase epitaxy growth by normal-incidence reflectance. This technique is used to calibrate the growth rate periodically and to monitor the growth process routinely. It is not only a precise tool to measure the growth rate, but also very useful in identifying unusal problems during a growth run, such as depletion of source material, deterioration of surface morphology, and problems associated with an improper growht procedure. We will also present an excellent reproducibility ({+-}0.3% over a course of more than 100 runs) of the cavity wavelength of vertical-cavity surface emitting laser structures with periodic calibration by this in situ technique.

  16. Improvements in plant growth rate using underwater discharge

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

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

  18. Enterococcus faecium LKE12 Cell-Free Extract Accelerates Host Plant Growth via Gibberellin and Indole-3-Acetic Acid Secretion.

    PubMed

    Lee, Ko-Eun; Radhakrishnan, Ramalingam; Kang, Sang-Mo; You, Young-Hyun; Joo, Gil-Jae; Lee, In-Jung; Ko, Jae-Hwan; Kim, Jin-Ho

    2015-09-01

    The use of microbial extracts containing plant hormones is a promising technique to improve crop growth. Little is known about the effect of bacterial cell-free extracts on plant growth promotion. This study, based on phytohormonal analyses, aimed at exploring the potential mechanisms by which Enterococcus faecium LKE12 enhances plant growth in oriental melon. A bacterial strain, LKE12, was isolated from soil, and further identified as E. faecium by 16S rDNA sequencing and phylogenetic analysis. The plant growth-promoting ability of an LKE12 bacterial culture was tested in a gibberellin (GA)-deficient rice dwarf mutant (waito-C) and a normal GA biosynthesis rice cultivar (Hwayongbyeo). E. faecium LKE12 significantly improved the length and biomass of rice shoots in both normal and dwarf cultivars through the secretion of an array of gibberellins (GA1, GA3, GA7, GA8, GA9, GA12, GA19, GA20, GA24, and GA53), as well as indole-3-acetic acid (IAA). To the best of our knowledge, this is the first study indicating that E. faecium can produce GAs. Increases in shoot and root lengths, plant fresh weight, and chlorophyll content promoted by E. faecium LKE12 and its cell-free extract inoculated in oriental melon plants revealed a favorable interaction of E. faecium LKE12 with plants. Higher plant growth rates and nutrient contents of magnesium, calcium, sodium, iron, manganese, silicon, zinc, and nitrogen were found in cell-free extract-treated plants than in control plants. The results of the current study suggest that E. faecium LKE12 promotes plant growth by producing GAs and IAA; interestingly, the exogenous application of its cell-free culture extract can be a potential strategy to accelerate plant growth.

  19. In vivo acceleration of skin growth using a servo-controlled stretching device.

    PubMed

    Chin, Michael S; Ogawa, Rei; Lancerotto, Luca; Pietramaggiori, Giorgio; Schomacker, Kevin T; Mathews, Jasmine C; Scherer, Saja S; Van Duyn, Paul; Prsa, Michael J; Ottensmeyer, Mark P; Veves, Aristidis; Orgill, Dennis P

    2010-06-01

    Tension is a principal force experienced by skin and serves a critical role in growth and development. Optimal tension application regimens may be an important component for skin tissue engineering and dermatogenesis. In this study, we designed and tested a novel servo-controlled skin-stretching device to apply predetermined tension and waveforms in mice. The effects of static and cyclical stretching forces were compared in 48 mice by measuring epidermal proliferation, angiogenesis, cutaneous perfusion, and principal growth factors using immunohistochemistry, real-time reverse transcriptase-polymerase chain reaction, and hyperspectral imaging. All stretched samples had upregulated epidermal proliferation and angiogenesis. Real-time reverse transcriptase-polymerase chain reaction of epidermal growth factor, transforming growth factor beta1, and nerve growth factor demonstrated greater expression in cyclically stretched skin when compared to static stretch. Hypoxia-induced factor 1alpha was significantly upregulated in cyclically stretched skin, but poststretch analysis demonstrated well-oxygenated tissue, collectively suggesting the presence of transient hypoxia. Waveform-specific mechanical loads may accelerate tissue growth by mechanotransduction and as a result of repeated cycles of temporary hypoxia. Further analysis of mechanotransduction signaling pathways may provide additional insight to improve skin tissue engineering methods and optimize our device.

  20. Plant growth promoting rhizobacteria and endophytes accelerate phytoremediation of metalliferous soils.

    PubMed

    Ma, Y; Prasad, M N V; Rajkumar, M; Freitas, H

    2011-01-01

    Technogenic activities (industrial-plastic, textiles, microelectronics, wood preservatives; mining-mine refuse, tailings, smelting; agrochemicals-chemical fertilizers, farm yard manure, pesticides; aerosols-pyrometallurgical and automobile exhausts; biosolids-sewage sludge, domestic waste; fly ash-coal combustion products) are the primary sources of heavy metal contamination and pollution in the environment in addition to geogenic sources. During the last two decades, bioremediation has emerged as a potential tool to clean up the metal-contaminated/polluted environment. Exclusively derived processes by plants alone (phytoremediation) are time-consuming. Further, high levels of pollutants pose toxicity to the remediating plants. This situation could be ameliorated and accelerated by exploring the partnership of plant-microbe, which would improve the plant growth by facilitating the sequestration of toxic heavy metals. Plants can bioconcentrate (phytoextraction) as well as bioimmobilize or inactivate (phytostabilization) toxic heavy metals through in situ rhizospheric processes. The mobility and bioavailability of heavy metal in the soil, particularly at the rhizosphere where root uptake or exclusion takes place, are critical factors that affect phytoextraction and phytostabilization. Developing new methods for either enhancing (phytoextraction) or reducing the bioavailability of metal contaminants in the rhizosphere (phytostabilization) as well as improving plant establishment, growth, and health could significantly speed up the process of bioremediation techniques. In this review, we have highlighted the role of plant growth promoting rhizo- and/or endophytic bacteria in accelerating phytoremediation derived benefits in extensive tables and elaborate schematic sketches.

  1. A rare large right atrial myxoma with rapid growth rate.

    PubMed

    Kelly, Shawn C; Steffen, Kelly; Stys, Adam T

    2014-10-01

    Atrial myxomas are the most common benign intracavitary cardiac neoplasms. They most frequently occur in the left atrium. Right atrial tumors are rare, comprising 20 percent of myxomas achieving an incidence of 0.02 percent. Due to their rarity, right atrial tumor development and associated clinical symptoms has not been well described. The classical clinical triad for the presentation of left atrial myxomas--heart failure, embolic events, and constitutional symptoms--may not be applicable to right sided tumors. Also, natural development of myxoma is not well described, as surgical resection is the common practice. Previously ascribed growth rates of myxomas refer mostly to left atrial ones, as right atrial tumors are rare. We present a case of right atrial myxoma with growth rates exceeding those previously described.

  2. On Growth Rates of Subadditive Functions for Semiflows

    NASA Astrophysics Data System (ADS)

    Schreiber, Sebastian J.

    1998-09-01

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

  3. Mortality rate acceleration and post-reproductive lifespan in matrilineal whale species.

    PubMed

    Foote, Andrew D

    2008-04-23

    The strength of selection to increase the span of a life stage is dependent upon individuals at that stage being able to contribute towards individual fitness and the probability of their surviving to that stage. Complete reproductive cessation and a long post-reproductive female lifespan as found in humans are also found in killer whale (Orcinus orca) and short-finned pilot whale (Globicephala macrorhynchus), but not in the long-finned pilot whale (Globicephala melaena). Each species forms kin-based, stable matrilineal groups and exhibits kin-directed behaviours that could increase inclusive fitness. Here, the initial mortality rate and mortality rate-doubling time of females of these three closely related whale species are compared. The initial mortality rate shows little variation among pilot whale species; however mortality rate accelerates almost twice as fast in the long-finned pilot whale as it does in killer whale and short-finned pilot whale. Selection for a long post-reproductive female lifespan in matrilineal whales may therefore be determined by the proportion of females surviving past the point of reproductive cessation.

  4. Canine fetal heart rate: do accelerations or decelerations predict the parturition day in bitches?

    PubMed

    Gil, E M U; Garcia, D A A; Giannico, A T; Froes, T R

    2014-10-15

    Ultrasonography is a safe and efficient technique for monitoring fetal development and viability. One of the most important and widely used parameters to verify fetal viability is the fetal heart rate (HR). In human medicine, the fetal HR normally oscillates during labor in transient accelerations and decelerations associated with uterine contractions. The present study investigated whether these variations also occur in canine fetuses and its relationship to parturition. A cohort study was conducted in 15 pregnant bitches undergoing two-dimensional high-resolution ultrasonographic examination during the 8th and 9th week of gestation. Fetal HR was assessed in M-mode for 5 minutes in each fetus in all bitches. In addition, the bitches were monitored for clinical signs of imminent parturition. Associations between the HR, antepartum time, and delivery characteristics were evaluated with a Poisson regression model. Fetal HR acceleration and deceleration occurred in canine fetuses and predicted the optimal time of parturition. These findings can help veterinarians and sonographers better understand this phenomenon in canine fetuses.

  5. Volume Changes After Stereotactic LINAC Radiotherapy in Vestibular Schwannoma: Control Rate and Growth Patterns

    SciTech Connect

    Langenberg, Rick van de; Dohmen, Amy J.C.; Bondt, Bert J. de; Nelemans, Patty J.; Baumert, Brigitta G.; Stokroos, Robert J.

    2012-10-01

    Purpose: The purpose of this study was to evaluate the control rate of vestibular schwannomas (VS) after treatment with linear accelerator (LINAC)-based stereotactic radiosurgery (SRS) or radiotherapy (SRT) by using a validated volumetric measuring tool. Volume-based studies on prognosis after LINAC-based SRS or SRT for VS are reported scarcely. In addition, growth patterns and risk factors predicting treatment failure were analyzed. Materials and Methods: Retrospectively, 37 VS patients treated with LINAC based SRS or SRT were analyzed. Baseline and follow-up magnetic resonance imaging scans were analyzed with volume measurements on contrast enhanced T1-weighted magnetic resonance imaging. Absence of intervention after radiotherapy was defined as 'no additional intervention group, ' absence of radiological growth was defined as 'radiological control group. ' Significant growth was defined as a volume change of 19.7% or more, as calculated in a previous study. Results: The cumulative 4-year probability of no additional intervention was 96.4% {+-} 0.03; the 4-year radiological control probability was 85.4% {+-} 0.1). The median follow-up was 40 months. Overall, shrinkage was seen in 65%, stable VS in 22%, and growth in 13%. In 54% of all patients, transient swelling was observed. No prognostic factors were found regarding VS growth. Previous treatment and SRS were associated with transient swelling significantly. Conclusions: Good control rates are reported for LINAC based SRS or SRT in VS, in which the lower rate of radiological growth control is attributed to the use of the more sensitive volume measurements. Transient swelling after radiosurgery is a common phenomenon and should not be mistaken for treatment failure. Previous treatment and SRS were significantly associated with transient swelling.

  6. Computational method to estimate Single Event Upset rates in an accelerator environment

    NASA Astrophysics Data System (ADS)

    Huhtinen, M.; Faccio, F.

    2000-08-01

    We present a new method to estimate Single Event Upsets (SEU) in a hadron accelerator environment, which is characterized by a complicated radiation spectrum. Our method is based on first principles, i.e. an explicit generation and transport of nuclear fragments and detailed accounting for energy loss by ionization. However, instead of simulating also the behaviour of the circuit, we use a Weibull fit to experimental heavy-ion SEU data in order to quantify the SEU sensitivity of the circuit. Thus, in principle, we do not need to know details about the circuit and our method is almost free of adjustable parameters - we only need a reasonable guess for the Sensitive Volume (SV) size. We show by a comparison with experimental data that our method predicts the SEU cross sections for protons rather accurately. We then indicate with an example how our method could be applied to predict SEU rates at the forthcoming LHC experiments.

  7. Rate of energy gain and maximum energy in diffusive shock acceleration. [astrophysical implications

    NASA Technical Reports Server (NTRS)

    Jokipii, J. R.

    1987-01-01

    The problem of diffusive shock acceleration of fast charged particles is reexamined with emphasis on the rate of energy gain, and the maximum energy which can be attained in a given circumstance. The direction of the average magnetic field at the shock is shown to have a large effect. If the perpendicular diffusion coefficient is much smaller than the parallel coefficient, particles can gain much more energy if the shock is quasi-perpendicular than if it is quasi-parallel. The maximum energy attainable can be substantially higher (by a factor of 100 or more) than previous discussions would predict, in cases where the shock is quasi-perpendicular. The energy gain increases as kappa-perpendicular decreases. The principal limitation comes from the requirement that diffusion be a valid approximation to the particle motion, and that the particle be able to diffuse fast enough to encounter the shock many times.

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

    PubMed

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

    2015-11-01

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

  9. World growth rate slows, but numbers build up.

    PubMed

    Haub, C

    1994-11-01

    In 1992, the UN estimated annual world population growth at 1.68% for 1990-95. Official UN world population estimates and projections were, however, revised in 1994 to reflect the beginning of an apparent fertility transition in a number of sub-Saharan African, Asian, and Middle Eastern countries. This new series of UN estimates and projections reflects the resumption of a trend of declining world population growth rates which began in the mid-1960s, but stalled soon thereafter. UN demographers now calculate that over the period 1990-94, world population grew at 1.57% per year, lower than the 1.68% used in 1992, and significantly below the 1.73% per year growth rate over the period 1975-90 and the peak of 2.0% in the late 1960s. The current rate of population growth is the lowest recorded since World War II. The number of people added to world population will, however, increase annually until at least the year 2000. In mid-1994, there were 5.63 billion people in the world, 4.47 billion in developing countries and 1.16 billion in more developed countries. World population is projected to be 9.8 billion in the year 2050 in the medium series projection, 7.9 billion in the low series, and 11.9 billion in the high series. China, India, the United States, Indonesia, Brazil, Russia, Pakistan, Japan, Bangladesh, and Nigeria are currently the only countries each with more than 100 million people. UN medium projections, however, indicate that by the year 2050 Ethiopia, Zaire, Iran, Mexico, Vietnam, the Philippines, Egypt, and Turkey should enter the 100-million-plus league.

  10. Time dependent sphere-to-rod growth of the pluronic micelles: investigating the role of core and corona solvation in determining the micellar growth rate.

    PubMed

    Kadam, Y; Ganguly, R; Kumbhakar, M; Aswal, V K; Hassan, P A; Bahadur, P

    2009-12-24

    The salt induced sphere-to-rod growth in the micelles of the PEO-PPO triblock copolymers, Pluronic P123 (EO(20)PO(70)PEO(20)) and Pluronic P103 (EO(16)PO(61)PEO(16)), has been studied by dynamic light scattering (DLS), viscometry, and small angle neutron scattering (SANS) techniques. The observed micellar growths are found to be time dependent and have a strong variation in their growth rate with changing anion type and copolymer composition. The rate of growth increases rather significantly with an increase in the water structure making abilities of the anions along the Hofmeister series in the order Cl(-) < F(-)< (PO(4))(3-). This has been attributed to an increasing ability of these ions to dehydrate the micellar corona, a factor that plays an important role in inducing sphere-to-rod shape transition of the micelles. The copolymer composition also has a significant influence on the micellar growth rate, as the P103 with a smaller molecular weight than P123 shows a significantly faster growth of its micelles under similar conditions. The observed time dependence in micellar growth in these systems has been attributed to a slow micellar restructuring process necessary to attain the equilibrium structure of the micelles. A remarkable improvement in the growth rate of the micelles, however, could be achieved in the presence of ethanol, a solvent that has affinity toward both the PPO and PEO blocks. Our spectroscopic studies suggest that the observed improvement in the micellar growth rate by ethanol is due to an accelerated restructuring process of the micelles in the presence of the solvated micellar core. These studies thus highlight the role of changing core and corona solvation characteristics of the pluronic micelles in determining their rearrangement and the growth rate, which is first of its kind in the aqueous pluronic system.

  11. TP508 accelerates fracture repair by promoting cell growth over cell death

    SciTech Connect

    Li Xinmin; Wang Hali; Touma, Edward; Qi Yuchen; Rousseau, Emma; Quigg, Richard J.; Ryaby, James T.

    2007-12-07

    TP508 is a synthetic 23-amino acid peptide representing a receptor-binding domain of human thrombin. We have previously shown that a single injection of TP508 accelerates fracture healing in a rat femoral fracture model. To understand how TP508 acts at the protein level during fracture healing, we compared the translational profiles between saline-control and fractured femur at six time points after TP508 treatment using the second generation of BD Clontech{sup TM} Antibody Microarray. Here, we demonstrate that TP508 accelerates fracture healing by modulating expression levels of proteins primarily involved in the functional categories of cell cycle, cellular growth and proliferation, and cell death. The majority of those proteins are physically interrelated and functionally overlapped. The action of those proteins is highlighted by a central theme of promoting cell growth via balance of cell survival over cell death signals. This appears to occur through the stimulation of several bone healing pathways including cell cycle-G1/S checkpoint regulation, apoptosis, JAK/STAT, NF-{kappa}B, PDGF, PI3K/AKT, PTEN, and ERK/MAPK.

  12. Acceleration of puberty during growth hormone therapy in a child with septo-optic dysplasia.

    PubMed

    Catlı, Gönül; Altıncık, Ayça; Anık, Ahmet; Demir, Korcan; Güleryüz, Handan; Abacı, Ayhan; Böber, Ece

    2014-01-01

    Septo-optic dysplasia (SOD) is a heterogeneous disorder of the central nervous system characterized by various endocrinological and neurological findings. It is a complex disease caused by a combination of genetic and environmental factors. Herein, we report the case of a 5.5-year-old girl who presented with short stature and strabismus. Ophthalmological examination revealed bilateral optic nerve hypoplasia. Ectopic posterior pituitary and bilateral optic hypoplasia were detected on brain magnetic resonance imaging. The presence of bilateral optic nerve hypoplasia and hypopituitarism led to the diagnosis of SOD. An abated growth hormone (GH) response was found in the GH stimulation test and GH replacement therapy was initiated. At the end of the first year of clinical follow-up, secondary hypothyroidism was detected and L-thyroxine was added to the treatment. At the age of 8.25 years, thelarche was noted and 6 months later, the patient presented with menarche. At this time, the bone age was 12 years and the basal luteinizing hormone level was 7 mIU/mL. These findings indicated acceleration in the process of pubertal development. We report this case (i) to emphasize the need to investigate hypopituitarism in cases with bilateral optic nerve hypoplasia and (ii) to draw attention to the fact that during the follow-up of SOD cases receiving GH therapy, inappropriate acceleration of growth velocity and rapid improvement in bone age may be predictive of central precocious puberty development.

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

    NASA Technical Reports Server (NTRS)

    Corder, Eric L.; Briscoe, Jeri

    2004-01-01

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

  14. Updating Medicare's physician fees: the sustainable growth rate methodology.

    PubMed

    Dummit, Laura A

    2006-11-10

    Medicare's method to annually update the fees it pays physicians has been under fire for some time--specifically, since the method determined that physician fees should be reduced rather than increased. The update method, called the sustainable growth rate (SGR), was implemented to control the growth in Medicare physician spending. Yet Congress, in response to physician concerns about beneficiary access to care, has acted to avert physician fee cuts since 2003. Although this signals dissatisfaction with the SGR methodology, there is yet to be a widely accepted physician fee update proposal that balances federal budgetary realities with the need to ensure beneficiary access. And the cost of changing the update method continues to mount, adding to the difficulties of developing a solution that meets the needs of all stakeholders. This issue brief describes the SGR methodology, the reasons why projected physician fee updates are negative, and some options that have been proposed to remedy the current situation. This issue brief is the second of two related papers on physician spending and Medicare's sustainable growth rate methodology. The companion paper was published on October 9, 2006 (see Issue Brief 815, available at www.nhpf.org/pdfs_ib/IB815_PhysicianSpending_10-09-06.pdf).

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

    PubMed

    Lough, Janice M; Cantin, Neal E

    2014-06-01

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

  16. Diffusion-controlled growth rate of stepped interfaces

    NASA Astrophysics Data System (ADS)

    Saidi, P.; Hoyt, J. J.

    2015-07-01

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

  17. Diffusion-controlled growth rate of stepped interfaces.

    PubMed

    Saidi, P; Hoyt, J J

    2015-07-01

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

  18. Rapid growth rates of syndepositional marine aragonite cements in steep marginal slope deposits, Bahamas and Belize

    SciTech Connect

    Grammer, G.M.; Ginsburg, R.N.; Swart, P.K.; McNeill, D.F. . Div. of Marine Geology); Jull, A.J.T. . NSF Accelerator Facility); Prezbindowski, D.R. )

    1993-09-01

    Growth rates of marine botryoidal aragonite cements from steep (35-45[degree]) marginal slope deposits in the Bahamas and Belize have been determined by accelerator mass spectrometer radiocarbon dating of samples taken at the base and top of individual botryoids. The pore-filling cements, which range from approximately 11,000-13,000 years old, grew at average rates of 8-10mm/100 yr with maximum rates > 25mm/100 yr. Radiocarbon dating of coexisting skeletal components indicates that cementation was syndepositional. Microsampling transects across individual botryoids for stable-isotope analyses show little variation in [delta][sup 31]C and [delta][sup 18]O, supporting the conclusion that cementation was extremely rapid. Although the cements show a progressive depletion in isotopic composition of approximately 1[per thousand]([delta][sup 13]C) and 2[per thousand]([delta][sup 18]O) from 13 ka to 11 ka, the average variation ([delta][sub 1]) within individual pore-filling cements, ranging in size 2 mm to 32 mm (bottom to top), was 0.11[per thousand]([delta][sup 13]C) and 0.14[per thousand]([delta][sup 18]O). Results of this study provide the first quantitative data on growth rates of marine carbonate cements in a marginal slope environment. The data indicate that marginal slope deposits may lithify within several tens of years and suggest that geologically instantaneous cementation may be critical in stabilizing steep carbonate slope deposits at or above angles of repose.

  19. Growth of monosodium urate monohydrate crystals: effect of cartilage and synovial fluid components on in vitro growth rates.

    PubMed Central

    Burt, H M; Dutt, Y C

    1986-01-01

    The effects of cartilage and synovial fluid components such as proteoglycans, chondroitin sulphate, hyaluronic acid, phospholipids, and albumin on the growth kinetics of monosodium urate monohydrate (MSUM) crystals were investigated. MSUM seed crystals were added to supersaturated sodium urate solutions, and the rate of decrease in the concentration of growth medium was used as a measure of the growth rate. A second order dependence of growth rate on supersaturation was found, and growth rate constants were determined with an integrated form of the growth equation. The additives, hyaluronic acid, proteoglycan monomer and aggregate, and phosphatidylserine, had no significant effect on the growth rate constant. Chondroitin sulphate and phosphatidylcholine increased the growth rate constant, possibly by promoting further nucleation in the growth medium. Albumin significantly inhibited MSUM crystallisation. The possible implications of these findings on in vivo MSUM crystallisation are discussed. PMID:3098195

  20. Co-option of pre-existing vascular beds in adipose tissue controls tumor growth rates and angiogenesis

    PubMed Central

    Lim, Sharon; Hosaka, Kayoko; Nakamura, Masaki; Cao, Yihai

    2016-01-01

    Many types of cancer develop in close association with highly vascularized adipose tissues. However, the role of adipose pre-existing vascular beds on tumor growth and angiogenesis is unknown. Here we report that pre-existing microvascular density in tissues where tumors originate is a crucial determinant for tumor growth and neovascularization. In three independent tumor types including breast cancer, melanoma, and fibrosarcoma, inoculation of tumor cells in the subcutaneous tissue, white adipose tissue (WAT), and brown adipose tissue (BAT) resulted in markedly differential tumor growth rates and angiogenesis, which were in concordance with the degree of pre-existing vascularization in these tissues. Relative to subcutaneous tumors, WAT and BAT tumors grew at accelerated rates along with improved neovascularization, blood perfusion, and decreased hypoxia. Tumor cells implanted in adipose tissues contained leaky microvessel with poor perivascular cell coverage. Thus, adipose vasculature predetermines the tumor microenvironment that eventually supports tumor growth. PMID:27203675

  1. Single-mode, Rayleigh-Taylor growth-rate measurements on the OMEGA laser system

    NASA Astrophysics Data System (ADS)

    Knauer, J. P.; Betti, R.; Bradley, D. K.; Boehly, T. R.; Collins, T. J. B.; Goncharov, V. N.; McKenty, P. W.; Meyerhofer, D. D.; Smalyuk, V. A.; Verdon, C. P.; Glendinning, S. G.; Kalantar, D. H.; Watt, R. G.

    2000-01-01

    The results from a series of single-mode, Rayleigh-Taylor (RT) instability growth experiments performed on the OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] using planar targets are reported. Planar targets with imposed mass perturbations were accelerated using five or six 351 nm laser beams overlapped with total intensities up to 2.5×1014 W/cm2. Experiments were performed with both 3 ns ramp and 3 ns flat-topped temporal pulse shapes. The use of distributed phase plates and smoothing by spectral dispersion resulted in a laser-irradiation nonuniformity of 4%-7% over a 600 μm diam region defined by the 90% intensity contour. The temporal growth of the modulation in optical depth was measured using throughfoil radiography and was detected with an x-ray framing camera for CH targets. Two-dimensional (2-D) hydrodynamic simulations (ORCHID) [R. L. McCrory and C. P. Verdon, in Inertial Confinement Fusion (Editrice Compositori, Bologna, 1989), pp. 83-124] of the growth of 20, 31, and 60 μm wavelength perturbations were in good agreement with the experimental data when the experimental details, including noise, were included. The amplitude of the simulation optical depth is in good agreement with the experimental optical depth; therefore, great care must be taken when the growth rates are compared to dispersion formulas. Since the foil's initial condition just before it is accelerated is not that of a uniformly compressed foil, the optical density measurement does not accurately reflect the amplitude of the ablation surface but is affected by the initial nonuniform density profile.

  2. Single-mode, Rayleigh-Taylor growth-rate measurements on the OMEGA laser system

    SciTech Connect

    Knauer, J. P.; Betti, R.; Bradley, D. K.; Boehly, T. R.; Collins, T. J. B.; Goncharov, V. N.; McKenty, P. W.; Meyerhofer, D. D.; Smalyuk, V. A.; Verdon, C. P.

    2000-01-01

    The results from a series of single-mode, Rayleigh-Taylor (RT) instability growth experiments performed on the OMEGA laser system [T. R. Boehly et al., Opt. Commun. 133, 495 (1997)] using planar targets are reported. Planar targets with imposed mass perturbations were accelerated using five or six 351 nm laser beams overlapped with total intensities up to 2.5x10{sup 14} W/cm{sup 2}. Experiments were performed with both 3 ns ramp and 3 ns flat-topped temporal pulse shapes. The use of distributed phase plates and smoothing by spectral dispersion resulted in a laser-irradiation nonuniformity of 4%-7% over a 600 {mu}m diam region defined by the 90% intensity contour. The temporal growth of the modulation in optical depth was measured using throughfoil radiography and was detected with an x-ray framing camera for CH targets. Two-dimensional (2-D) hydrodynamic simulations (ORCHID) [R. L. McCrory and C. P. Verdon, in Inertial Confinement Fusion (Editrice Compositori, Bologna, 1989), pp. 83-124] of the growth of 20, 31, and 60 {mu}m wavelength perturbations were in good agreement with the experimental data when the experimental details, including noise, were included. The amplitude of the simulation optical depth is in good agreement with the experimental optical depth; therefore, great care must be taken when the growth rates are compared to dispersion formulas. Since the foil's initial condition just before it is accelerated is not that of a uniformly compressed foil, the optical density measurement does not accurately reflect the amplitude of the ablation surface but is affected by the initial nonuniform density profile. (c) 2000 American Institute of Physics.

  3. Growth rate, transmission mode and virulence in human pathogens

    PubMed Central

    Cornwallis, Charlie K.; Buckling, Angus; West, Stuart A.

    2017-01-01

    The harm that pathogens cause to hosts during infection, termed virulence, varies across species from negligible to a high likelihood of rapid death. Classic theory for the evolution of virulence is based on a trade-off between pathogen growth, transmission and host survival, which predicts that higher within-host growth causes increased transmission and higher virulence. However, using data from 61 human pathogens, we found the opposite correlation to the expected positive correlation between pathogen growth rate and virulence. We found that (i) slower growing pathogens are significantly more virulent than faster growing pathogens, (ii) inhaled pathogens and pathogens that infect via skin wounds are significantly more virulent than pathogens that are ingested, but (iii) there is no correlation between symptoms of infection that aid transmission (such as diarrhoea and coughing) and virulence. Overall, our results emphasize how virulence can be influenced by mechanistic life-history details, especially transmission mode, that determine how parasites infect and exploit their hosts. This article is part of the themed issue ‘Opening the black box: re-examining the ecology and evolution of parasite transmission’. PMID:28289261

  4. Female promiscuity and maternally dependent offspring growth rates in mammals.

    PubMed

    Garratt, Michael; Brooks, Robert C; Lemaître, Jean-François; Gaillard, Jean-Michel

    2014-04-01

    Conflicts between family members are expected to influence the duration and intensity of parental care. In mammals, the majority of this care occurs as resource transfer from mothers to offspring during gestation and lactation. Mating systems can have a strong influence on the severity of familial conflict--where female promiscuity is prevalent, conflict is expected to be higher between family members, causing offspring to demand more resources. If offspring are capable of manipulating their mothers and receive resources in proportion to their demands, resource transfer should increase with elevated promiscuity. We tested this prediction, unexplored across mammals, using a comparative approach. The total durations of gestation and lactation were not related to testes mass, a reliable proxy of female promiscuity across taxa. Offspring growth during gestation, however, and weaning mass, were positively correlated with testes mass, suggesting that offspring gain resources from their mothers at faster rates when familial conflict is greater. During gestation, the relationship between offspring growth and testes mass was also related to placenta morphology, with a stronger relationship between testes mass and growth observed in species with a less invasive placenta. Familial conflict could have a pervasive influence on patterns of parental care in mammals.

  5. Crystallization of Solids in the Presence of Anisotropic Growth Rates and Gaussian Nucleation Rates

    NASA Astrophysics Data System (ADS)

    Lokovic, Kimberly; Bill, Andreas; Bergmann, Ralf

    2010-10-01

    The grain size distribution allows characterizing quantitatively the microstructure of an amorphous solid at different stages of crystallization. We review the theory developed recently for the grain size distribution (GSD) [1] and present two extensions of the model. In the first generalization, we replace the isotropic growth rate by an anisotropic rate that leads to the formation of ellipsoidal grains. Different anisotropic growth mechanisms are considered. We obtain an analytical expression for the GSD when the growth rate leads to a change of volume leaving the shape of grains invariant [2]. In the second generalization, we study how the GSD is affected by replacing the Dirac-type source term of nuclei by a more physical Gaussian-type source. We use that model to analyze the GSD at early stages of crystallization.[4pt] [1] A.V.Teran, R.B.Bergmann and A.Bill, Phys. Rev. B 81, 075319 (2010).[0pt] [2] K.S.Lokovic, R.B.Bergmann and A.Bill, Mater. Res. Soc. Symp. Proc. 1245, A16-07 (2010).

  6. Time growth rate and field profiles of hybrid modes excited by a relativistic elliptical electron beam in an elliptical metallic waveguide with dielectric rod

    SciTech Connect

    Jazi, B.; Rahmani, Z.; Abdoli-Arani, A.; Heidari-Semiromi, E.

    2012-10-15

    The dispersion relation of guided electromagnetic waves propagating in an elliptical metallic waveguide with a dielectric rod driven by relativistic elliptical electron beam (REEB) is investigated. The electric field profiles and the growth rates of the waves are numerically calculated by using Mathieu functions. The effects of relative permittivity constant of dielectric rod, accelerating voltage, and current density of REEB on the growth rate are presented.

  7. The Effect of Growth Rate on Interface Morphology

    NASA Technical Reports Server (NTRS)

    Trivedi, R.; Somboonsuk, K.

    1984-01-01

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

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

    DOE PAGES

    Jennings, Elise; Jennings, David

    2015-04-09

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

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

    SciTech Connect

    Jennings, Elise; Jennings, David

    2015-04-09

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

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

    NASA Astrophysics Data System (ADS)

    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. Effect of initial acceleration on the development of the flow field of an airfoil pitching at constant rate

    NASA Technical Reports Server (NTRS)

    Koochesfahani, M. M.; Smiljanovski, V.; Brown, T. A.

    1992-01-01

    We present results from a series of experiments where an airfoil is pitched at constant rate from 0 to 60 degrees angle of attack. It is well documented that the dynamic stall behavior of such an airfoil strongly depends on the nondimensional pitch rate K = dot-alpha C/(2U(sub infinity)), where C is the chord, dot-alpha the constant pitch rate, and U(sub infinity) the free stream speed. In reality, the actual motion of the airfoil deviates from the ideal ramp due to the finite acceleration and deceleration periods imposed by the damping of drive system and response characteristics of the airfoil. It is possible that the pitch rate alone may not suffice in describing the flow and that the details of the motion trajectory before achieving a desired constant pitch rate may also affect the processes involved in the dynamic stall phenomenon. The effects of acceleration and deceleration periods are investigated by systematically varing the acceleration magnitude and its duration through the initial acceleration phase to constant pitch rate. The magnitude and duration of deceleration needed to bring the airfoil motion to rest is similarly controlled.

  12. Growth rate of a shocked mixing layer with known initial perturbations [Mixing at shocked interfaces with known perturbations

    SciTech Connect

    Weber, Christopher R.; Cook, Andrew W.; Bonazza, Riccardo

    2013-05-14

    Here we derive a growth-rate model for the Richtmyer–Meshkov mixing layer, given arbitrary but known initial conditions. The initial growth rate is determined by the net mass flux through the centre plane of the perturbed interface immediately after shock passage. The net mass flux is determined by the correlation between the post-shock density and streamwise velocity. The post-shock density field is computed from the known initial perturbations and the shock jump conditions. The streamwise velocity is computed via Biot–Savart integration of the vorticity field. The vorticity deposited by the shock is obtained from the baroclinic torque with an impulsive acceleration. Using the initial growth rate and characteristic perturbation wavelength as scaling factors, the model collapses the growth-rate curves and, in most cases, predicts the peak growth rate over a range of Mach numbers (1.1 ≤Mi≤1.9), Atwood numbers (₋0.73 ≤ A ≤ ₋0.35 and 0.22 ≤ A ≤ 0.73), adiabatic indices (1.40/1.67≤γ12≤1.67/1.09) and narrow-band perturbation spectra. Lastly, the mixing layer at late times exhibits a power-law growth with an average exponent of θ=0.24.

  13. Effects of growth rate and compensatory growth on body composition in lambs.

    PubMed

    Turgeon, O A; Brink, D R; Bartle, S J; Klopfenstein, T J; Ferrell, C L

    1986-09-01

    Fifty lambs were used in a comparative slaughter experiment to determine the effects of growth rates and compensatory growth on body composition. The study consisted of a growing and a finishing phase. During the growing phase, lambs (20 to 30 kg) were fed three different concentrate levels (30, 50 or 70%) to gain at three different rates (slow, medium and rapid). The finishing phase was evaluated in two periods (early, 30 to 38 kg; late, 38 to 45 kg). All lambs received 70% concentrate diets during the finishing phase. Groups of five lambs were sacrificed at 20, 30, 38 and 45 kg fleece-free weights for whole-body chemical analysis. At 30 kg live weight, lambs on a rapid growth diet were the fattest (P less than .01) and contained the least protein (P less than .05) in their empty bodies. The slower the lambs gained during the growing phase, the greater (P less than .05) was the response in rate of gain and feed efficiency during both periods of the finishing phase. Compensatory growth occurred in two stages; a greater proportion of protein gain was made early while a greater proportion of the fat gain was made during the late period of the finishing phase.

  14. Carcinogenic Parasite Secretes Growth Factor That Accelerates Wound Healing and Potentially Promotes Neoplasia

    PubMed Central

    Smout, Michael J.; Sotillo, Javier; Laha, Thewarach; Papatpremsiri, Atiroch; Rinaldi, Gabriel; Pimenta, Rafael N.; Chan, Lai Yue; Johnson, Michael S.; Turnbull, Lynne; Whitchurch, Cynthia B.; Giacomin, Paul R.; Moran, Corey S.; Golledge, Jonathan; Daly, Norelle; Sripa, Banchob; Mulvenna, Jason P.

    2015-01-01

    Abstract Infection with the human liver fluke Opisthorchis viverrini induces cancer of the bile ducts, cholangiocarcinoma (CCA). Injury from feeding activities of this parasite within the human biliary tree causes extensive lesions, wounds that undergo protracted cycles of healing, and re-injury over years of chronic infection. We show that O. viverrini secreted proteins accelerated wound resolution in human cholangiocytes, an outcome that was compromised following silencing of expression of the fluke-derived gene encoding the granulin-like growth factor, Ov-GRN-1. Recombinant Ov-GRN-1 induced angiogenesis and accelerated mouse wound healing. Ov-GRN-1 was internalized by human cholangiocytes and induced gene and protein expression changes associated with wound healing and cancer pathways. Given the notable but seemingly paradoxical properties of liver fluke granulin in promoting not only wound healing but also a carcinogenic microenvironment, Ov-GRN-1 likely holds marked potential as a therapeutic wound-healing agent and as a vaccine against an infection-induced cancer of major public health significance in the developing world. PMID:26485648

  15. TUSC3 Loss Alters the ER Stress Response and Accelerates Prostate Cancer Growth in vivo

    NASA Astrophysics Data System (ADS)

    Horak, Peter; Tomasich, Erwin; Vaňhara, Petr; Kratochvílová, Kateřina; Anees, Mariam; Marhold, Maximilian; Lemberger, Christof E.; Gerschpacher, Marion; Horvat, Reinhard; Sibilia, Maria; Pils, Dietmar; Krainer, Michael

    2014-01-01

    Prostate cancer is the most prevalent cancer in males in developed countries. Tumor suppressor candidate 3 (TUSC3) has been identified as a putative tumor suppressor gene in prostate cancer, though its function has not been characterized. TUSC3 shares homologies with the yeast oligosaccharyltransferase (OST) complex subunit Ost3p, suggesting a role in protein glycosylation. We provide evidence that TUSC3 is part of the OST complex and affects N-linked glycosylation in mammalian cells. Loss of TUSC3 expression in DU145 and PC3 prostate cancer cell lines leads to increased proliferation, migration and invasion as well as accelerated xenograft growth in a PTEN negative background. TUSC3 downregulation also affects endoplasmic reticulum (ER) structure and stress response, which results in increased Akt signaling. Together, our findings provide first mechanistic insight in TUSC3 function in prostate carcinogenesis in general and N-glycosylation in particular.

  16. TUSC3 Loss Alters the ER Stress Response and Accelerates Prostate Cancer Growth in vivo

    PubMed Central

    Horak, Peter; Tomasich, Erwin; Vaňhara, Petr; Kratochvílová, Kateřina; Anees, Mariam; Marhold, Maximilian; Lemberger, Christof E.; Gerschpacher, Marion; Horvat, Reinhard; Sibilia, Maria; Pils, Dietmar; Krainer, Michael

    2014-01-01

    Prostate cancer is the most prevalent cancer in males in developed countries. Tumor suppressor candidate 3 (TUSC3) has been identified as a putative tumor suppressor gene in prostate cancer, though its function has not been characterized. TUSC3 shares homologies with the yeast oligosaccharyltransferase (OST) complex subunit Ost3p, suggesting a role in protein glycosylation. We provide evidence that TUSC3 is part of the OST complex and affects N-linked glycosylation in mammalian cells. Loss of TUSC3 expression in DU145 and PC3 prostate cancer cell lines leads to increased proliferation, migration and invasion as well as accelerated xenograft growth in a PTEN negative background. TUSC3 downregulation also affects endoplasmic reticulum (ER) structure and stress response, which results in increased Akt signaling. Together, our findings provide first mechanistic insight in TUSC3 function in prostate carcinogenesis in general and N-glycosylation in particular. PMID:24435307

  17. Acceleration of wound healing by growth hormone-releasing hormone and its agonists.

    PubMed

    Dioufa, Nikolina; Schally, Andrew V; Chatzistamou, Ioulia; Moustou, Evi; Block, Norman L; Owens, Gary K; Papavassiliou, Athanasios G; Kiaris, Hippokratis

    2010-10-26

    Despite the well-documented action of growth hormone-releasing hormone (GHRH) on the stimulation of production and release of growth hormone (GH), the effects of GHRH in peripheral tissues are incompletely explored. In this study, we show that GHRH plays a role in wound healing and tissue repair by acting primarily on wound-associated fibroblasts. Mouse embryonic fibroblasts (MEFs) in culture and wound-associated fibroblasts in mice expressed a splice variant of the receptors for GHRH (SV1). Exposure of MEFs to 100 nM and 500 nM GHRH or the GHRH agonist JI-38 stimulated the expression of α-smooth muscle actin (αSMA) based on immunoblot analyses as well as the expression of an αSMA-β-galactosidase reporter transgene in primary cultures of fibroblasts isolated from transgenic mice. Consistent with this induction of αSMA expression, results of transwell-based migration assays and in vitro wound healing (scratch) assays showed that both GHRH and GHRH agonist JI-38 stimulated the migration of MEFs in vitro. In vivo, local application of GHRH or JI-38 accelerated healing in skin wounds of mice. Histological evaluation of skin biopsies showed that wounds treated with GHRH and JI-38 were both characterized by increased abundance of fibroblasts during the early stages of wound healing and accelerated reformation of the covering epithelium at later stages. These results identify another function of GHRH in promoting skin tissue wound healing and repair. Our findings suggest that GHRH may have clinical utility for augmenting healing of skin wounds resulting from trauma, surgery, or disease.

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

    PubMed

    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. Rotational IMRT delivery using a digital linear accelerator in very high dose rate 'burst mode'

    NASA Astrophysics Data System (ADS)

    Salter, Bill J.; Sarkar, Vikren; Wang, Brian; Shukla, Himanshu; Szegedi, Martin; Rassiah-Szegedi, Prema

    2011-04-01

    Recently, there has been a resurgence of interest in arc-based IMRT, through the use of 'conventional' multileaf collimator (MLC) systems that can treat large tumor volumes in a single, or very few pass(es) of the gantry. Here we present a novel 'burst mode' modulated arc delivery approach, wherein 2000 monitor units per minute (MU min-1) high dose rate bursts of dose are facilitated by a flattening-filter-free treatment beam on a Siemens Artiste (Oncology Care Systems, Siemens Medical Solutions, Concord, CA, USA) digital linear accelerator in a non-clinical configuration. Burst mode delivery differs from continuous mode delivery, used by Elekta's VMAT (Elekta Ltd, Crawley, UK) and Varian's RapidArc (Varian Medical Systems, Palo Alto, CA, USA) implementations, in that dose is not delivered while MLC leaves are moving. Instead, dose is delivered in bursts over very short arc angles and only after an MLC segment shape has been completely formed and verified by the controller. The new system was confirmed to be capable of delivering a wide array of clinically relevant treatment plans, without machine fault or other delivery anomalies. Dosimetric accuracy of the modulated arc platform, as well as the Prowess (Prowess Inc., Concord, CA, USA) prototype treatment planning version utilized here, was quantified and confirmed, and delivery times were measured as significantly brief, even with large hypofractionated doses. The burst mode modulated arc approach evaluated here appears to represent a capable, accurate and efficient delivery approach.

  20. Rotational IMRT delivery using a digital linear accelerator in very high dose rate 'burst mode'.

    PubMed

    Salter, Bill J; Sarkar, Vikren; Wang, Brian; Shukla, Himanshu; Szegedi, Martin; Rassiah-Szegedi, Prema

    2011-04-07

    Recently, there has been a resurgence of interest in arc-based IMRT, through the use of 'conventional' multileaf collimator (MLC) systems that can treat large tumor volumes in a single, or very few pass(es) of the gantry. Here we present a novel 'burst mode' modulated arc delivery approach, wherein 2000 monitor units per minute (MU min(-1)) high dose rate bursts of dose are facilitated by a flattening-filter-free treatment beam on a Siemens Artiste (Oncology Care Systems, Siemens Medical Solutions, Concord, CA, USA) digital linear accelerator in a non-clinical configuration. Burst mode delivery differs from continuous mode delivery, used by Elekta's VMAT (Elekta Ltd, Crawley, UK) and Varian's RapidArc (Varian Medical Systems, Palo Alto, CA, USA) implementations, in that dose is not delivered while MLC leaves are moving. Instead, dose is delivered in bursts over very short arc angles and only after an MLC segment shape has been completely formed and verified by the controller. The new system was confirmed to be capable of delivering a wide array of clinically relevant treatment plans, without machine fault or other delivery anomalies. Dosimetric accuracy of the modulated arc platform, as well as the Prowess (Prowess Inc., Concord, CA, USA) prototype treatment planning version utilized here, was quantified and confirmed, and delivery times were measured as significantly brief, even with large hypofractionated doses. The burst mode modulated arc approach evaluated here appears to represent a capable, accurate and efficient delivery approach.

  1. Evolution on neutral networks accelerates the ticking rate of the molecular clock

    PubMed Central

    Manrubia, Susanna; Cuesta, José A.

    2015-01-01

    Large sets of genotypes give rise to the same phenotype, because phenotypic expression is highly redundant. Accordingly, a population can accept mutations without altering its phenotype, as long as the genotype mutates into another one on the same set. By linking every pair of genotypes that are mutually accessible through mutation, genotypes organize themselves into neutral networks (NNs). These networks are known to be heterogeneous and assortative, and these properties affect the evolutionary dynamics of the population. By studying the dynamics of populations on NNs with arbitrary topology, we analyse the effect of assortativity, of NN (phenotype) fitness and of network size. We find that the probability that the population leaves the network is smaller the longer the time spent on it. This progressive ‘phenotypic entrapment’ entails a systematic increase in the overdispersion of the process with time and an acceleration in the fixation rate of neutral mutations. We also quantify the variation of these effects with the size of the phenotype and with its fitness relative to that of neighbouring alternatives. PMID:25392402

  2. Atrial and ventricular rate response and patterns of heart rate acceleration during maternal-fetal terbutaline treatment of fetal complete heart block.

    PubMed

    Cuneo, Bettina F; Zhao, Hui; Strasburger, Janette F; Ovadia, Marc; Huhta, James C; Wakai, Ronald T

    2007-08-15

    Terbutaline is used to treat fetal bradycardia in the setting of complete heart block (CHB); however, little is known of its effects on atrial and ventricular beat rates or patterns of heart rate (HR) acceleration. Fetal atrial and ventricular beat rates were compared before and after transplacental terbutaline treatment (10 to 30 mg/day) by fetal echocardiography in 17 fetuses with CHB caused by immune-mediated damage to a normal conduction system (isoimmune, n = 8) or a congenitally malformed conduction system associated with left atrial isomerism (LAI, n = 9). While receiving terbutaline, 9 of the 17 fetuses underwent fetal magnetocardiography (fMCG) to assess maternal HR and rhythm, patterns of fetal HR acceleration, and correlation between fetal atrial and ventricular accelerations (i.e., AV correlation). Maternal HR and fetal atrial and ventricular beat rates increased with terbutaline. However, terbutaline's effects were greater on the atrial pacemaker(s) in fetuses with isoimmune CHB and greater on the ventricular pacemaker(s) in those with LAI-associated CHB. Patterns of fetal HR acceleration also differed between isoimmune and LAI CHB. Finally, despite increasing HR, terbutaline did not restore the normal coordinated response between atrial and ventricular accelerations in isoimmune or LAI CHB. In conclusion, the pathophysiologic heterogeneity of CHB is reflected in the differing effect of terbutaline on the atrial and ventricular pacemaker(s) and varying patterns of HR acceleration. However, regardless of the cause of CHB, terbutaline augments HR but not AV correlation, suggesting that its effects are determined by the conduction system defect rather than the autonomic control of the developing heart.

  3. Atrial and Ventricular Rate Response and Patterns of Heart Rate Acceleration during Maternal–Fetal Terbutaline Treatment of Fetal Complete Heart Block

    PubMed Central

    Cuneo, Bettina F.; Zhao, Hui; Strasburger, Janette F.; Ovadia, Marc; Huhta, James C.; Wakai, Ronald T.

    2012-01-01

    Terbutaline is used to treat fetal bradycardia in the setting of complete heart block (CHB); however, little is known of its effects on atrial and ventricular beat rates or patterns of heart rate (HR) acceleration. Fetal atrial and ventricular beat rates were compared before and after transplacental terbutaline treatment (10 to 30 mg/day) by fetal echocardiography in 17 fetuses with CHB caused by immune-mediated damage to a normal conduction system (isoimmune, n = 8) or a congenitally malformed conduction system associated with left atrial isomerism (LAI, n = 9). While receiving terbutaline, 9 of the 17 fetuses underwent fetal magnetocardiography (fMCG) to assess maternal HR and rhythm, patterns of fetal HR acceleration, and correlation between fetal atrial and ventricular accelerations (i.e., AV correlation). Maternal HR and fetal atrial and ventricular beat rates increased with terbutaline. However, terbutaline's effects were greater on the atrial pacemaker(s) in fetuses with isoimmune CHB and greater on the ventricular pacemaker(s) in those with LAI-associated CHB. Patterns of fetal HR acceleration also differed between isoimmune and LAI CHB. Finally, despite increasing HR, terbutaline did not restore the normal coordinated response between atrial and ventricular accelerations in isoimmune or LAI CHB. In conclusion, the pathophysiologic heterogeneity of CHB is reflected in the differing effect of terbutaline on the atrial and ventricular pacemaker(s) and varying patterns of HR acceleration. However, regardless of the cause of CHB, terbutaline augments HR but not AV correlation, suggesting that its effects are determined by the conduction system defect rather than the autonomic control of the developing heart. PMID:17697825

  4. [Calculating the intrinsic growth rate: comparison of definition and model].

    PubMed

    Voronov, D A

    2005-01-01

    It was shown that well known equation r = ln[N(t2)/N(t1)]/(t2 - t1) is the definition of the average value of intrinsic growth rate of population r within any given interval of time t2-t1 and changing arbitrarity its numbers N(t). The common opinion considering the equation as suitable only for exponentially growing population was found to be incorrect. The fundamentally different approach is based on the calculation of r within the framework of demographic model, realized as Euler - Lotka equation or population projection matrices. However this model requires simultaneous realization of several assumptions improbable for natural populations: exponential change in population size, stable age structure and maintaining constant age-dependent birth and death rates. The calculation of r by definition requires the data on the dynamics of population numbers, whereas calculation on the basis of the model requires the demographic tables of birth and death rate, but not the population numbers. With the example of American ginseng it was shown that evalution of r by definition and model approaches could produce opposite results.

  5. Growth rate controlled barium partitioning in calcite and aragonite

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  6. Thermoneutral immersion exercise accelerates heart rate recovery: A potential novel training modality.

    PubMed

    Garzon, Mauricio; Dupuy, Olivier; Bosquet, Laurent; Nigam, Anil; Comtois, Alain Steve; Juneau, Martin; Gayda, Mathieu

    2017-04-01

    This study compared heart rate recovery (HRR) after incremental maximal exercise performed at the same external power output (Pext) on dry land ergocycle (DE) vs. immersible ergocycle (IE). Fifteen young healthy participants (30 ± 7 years, 13 men and 2 women) performed incremental maximal exercise tests on DE and on IE. The initial Pext on DE was 25 W and was increased by 25 W/min at a pedalling cadence between 60 and 80 rpm, while during IE immersion at chest level in thermoneutral water (30°C), the initial Pext deployment was at a cadence of 40 rpm which was increased by 10 rpm until 70 rpm and thereafter by 5 rpm until exhaustion. Gas exchange and heart rate (HR) were measured continuously during exercise and recovery for 5 min. Maximal HR (DE: 176 ± 15 vs. IE 169 ± 12 bpm) reached by the subjects in the two conditions did not differ (P > .05). Parasympathetic reactivation parameters (ΔHR from 10 to 300 s) were compared during the DE and IE HR recovery recordings. During the IE recovery, parasympathetic reactivation in the early phase was more predominant (HRR at Δ10-Δ60 s, P < .05), but similar in the late phase (HRR at Δ120-Δ300 s, P > .05) when compared to the DE condition. In conclusion, incremental maximal IE exercise at chest level immersion in thermoneutral water accelerates the early phase parasympathetic reactivation compared to DE in healthy young participants.

  7. Toward intelligent synthetic neural circuits: directing and accelerating neuron cell growth by self-rolled-up silicon nitride microtube array.

    PubMed

    Froeter, Paul; Huang, Yu; Cangellaris, Olivia V; Huang, Wen; Dent, Erik W; Gillette, Martha U; Williams, Justin C; Li, Xiuling

    2014-11-25

    In neural interface platforms, cultures are often carried out on a flat, open, rigid, and opaque substrate, posing challenges to reflecting the native microenvironment of the brain and precise engagement with neurons. Here we present a neuron cell culturing platform that consists of arrays of ordered microtubes (2.7-4.4 μm in diameter), formed by strain-induced self-rolled-up nanomembrane (s-RUM) technology using ultrathin (<40 nm) silicon nitride (SiNx) film on transparent substrates. These microtubes demonstrated robust physical confinement and unprecedented guidance effect toward outgrowth of primary cortical neurons, with a coaxially confined configuration resembling that of myelin sheaths. The dynamic neural growth inside the microtube, evaluated with continuous live-cell imaging, showed a marked increase (20×) of the growth rate inside the microtube compared to regions outside the microtubes. We attribute the dramatic accelerating effect and precise guiding of the microtube array to three-dimensional (3D) adhesion and electrostatic interaction with the SiNx microtubes, respectively. This work has clear implications toward building intelligent synthetic neural circuits by arranging the size, site, and patterns of the microtube array, for potential treatment of neurological disorders.

  8. Toward Intelligent Synthetic Neural Circuits: Directing and Accelerating Neuron Cell Growth by Self-Rolled-Up Silicon Nitride Microtube Array

    PubMed Central

    2015-01-01

    In neural interface platforms, cultures are often carried out on a flat, open, rigid, and opaque substrate, posing challenges to reflecting the native microenvironment of the brain and precise engagement with neurons. Here we present a neuron cell culturing platform that consists of arrays of ordered microtubes (2.7–4.4 μm in diameter), formed by strain-induced self-rolled-up nanomembrane (s-RUM) technology using ultrathin (<40 nm) silicon nitride (SiNx) film on transparent substrates. These microtubes demonstrated robust physical confinement and unprecedented guidance effect toward outgrowth of primary cortical neurons, with a coaxially confined configuration resembling that of myelin sheaths. The dynamic neural growth inside the microtube, evaluated with continuous live-cell imaging, showed a marked increase (20×) of the growth rate inside the microtube compared to regions outside the microtubes. We attribute the dramatic accelerating effect and precise guiding of the microtube array to three-dimensional (3D) adhesion and electrostatic interaction with the SiNx microtubes, respectively. This work has clear implications toward building intelligent synthetic neural circuits by arranging the size, site, and patterns of the microtube array, for potential treatment of neurological disorders. PMID:25329686

  9. Exposure to omega-3 fatty acids at early age accelerate bone growth and improve bone quality.

    PubMed

    Koren, Netta; Simsa-Maziel, Stav; Shahar, Ron; Schwartz, Betty; Monsonego-Ornan, Efrat

    2014-06-01

    Omega-3 fatty acids (FAs) are essential nutritional components that must be obtained from foods. Increasing evidence validate that omega-3 FAs are beneficial for bone health, and several mechanisms have been suggested to mediate their effects on bone, including alterations in calcium absorption and urinary calcium loss, prostaglandin synthesis, lipid oxidation, osteoblast formation and inhibition of osteoclastogenesis. However, to date, there is scant information regarding the effect of omega-3 FAs on the developing skeleton during the rapid growth phase. In this study we aim to evaluate the effect of exposure to high levels of omega-3 FAs on bone development and quality during prenatal and early postnatal period. For this purpose, we used the fat-1 transgenic mice that have the ability to convert omega-6 to omega-3 fatty acids and the ATDC5 chondrogenic cell line as models. We show that exposure to high concentrations of omega-3 FAs at a young age accelerates bone growth through alterations of the growth plate, associated with increased chondrocyte proliferation and differentiation. We further propose that those effects are mediated by the receptors G-protein coupled receptor 120 (GPR120) and hepatic nuclear factor 4α, which are expressed by chondrocytes in culture. Additionally, using a combined study on the structural and mechanical bone parameters, we show that high omega-3 levels contribute to superior trabecular and cortical structure, as well as to stiffer bones and improved bone quality. Most interestingly, the fat-1 model allowed us to demonstrate the role of maternal high omega-3 concentration on bone growth during the gestation and postnatal period.

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

    USGS Publications Warehouse

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

    2015-01-01

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

  11. Does seed mass drive the differences in relative growth rate between growth forms?

    PubMed

    Houghton, Jennie; Thompson, Ken; Rees, Mark

    2013-07-07

    The idea that herbaceous plants have higher relative growth rates (RGRs) compared with woody plants is fundamental to many of the most influential theories in plant ecology. This difference in growth rate is thought to reflect systematic variation in physiology, allocation and leaf construction. Previous studies documenting this effect have, however, ignored differences in seed mass. As woody species often have larger seeds and RGR is negatively correlated with seed mass, it is entirely possible the lower RGRs observed in woody species is a consequence of having larger seeds rather than different growth strategies. Using a synthesis of the published literature, we explored the relationship between RGR and growth form, accounting for the effects of seed mass and study-specific effects (e.g. duration of study and pot volume), using a mixed-effects model. The model showed that herbaceous species do indeed have higher RGRs than woody species, and that the difference was independent of seed mass, thus at all seed masses, herbaceous species on average grow faster than woody ones.

  12. Reduced expression of the SHORT-ROOT gene increases the rates of growth and development in hybrid poplar and Arabidopsis.

    PubMed

    Wang, Jiehua; Andersson-Gunnerås, Sara; Gaboreanu, Ioana; Hertzberg, Magnus; Tucker, Matthew R; Zheng, Bo; Leśniewska, Joanna; Mellerowicz, Ewa J; Laux, Thomas; Sandberg, Göran; Jones, Brian

    2011-01-01

    SHORT-ROOT (SHR) is a well characterized regulator of cell division and cell fate determination in the Arabidopsis primary root. However, much less is known about the functions of SHR in the aerial parts of the plant. In this work, we cloned SHR gene from Populus trichocarpa (PtSHR1) as an AtSHR ortholog and down-regulated its expression in hybrid poplar (Populus tremula×P. tremuloides Michx-clone T89) in order to determine its physiological functions in shoot development. Sharing a 90% similarity to AtSHR at amino acid level, PtSHR1 was able to complement the Arabidopsis shr mutant. Down regulation of PtSHR1 led to a strong enhancement of primary (height) and secondary (girth) growth rates in the transgenic poplars. A similar approach in Arabidopsis showed a comparable accelerated growth and development phenotype. Our results suggest that the response to SHR could be dose-dependent and that a partial down-regulation of SHR could lead to enhanced meristem activity and a coordinated acceleration of plant growth in woody species. Therefore, SHR functions in plant growth and development as a regulator of cell division and meristem activity not only in the roots but also in the shoots. Reducing SHR expression in transgenic poplar was shown to lead to significant increases in primary and secondary growth rates. Given the current interest in bioenergy crops, SHR has a broader role as a key regulator of whole plant growth and development and SHR suppression has considerable potential for accelerating biomass accumulation in a variety of species.

  13. Reduced Expression of the SHORT-ROOT Gene Increases the Rates of Growth and Development in Hybrid Poplar and Arabidopsis

    PubMed Central

    Wang, Jiehua; Andersson-Gunnerås, Sara; Gaboreanu, Ioana; Hertzberg, Magnus; Tucker, Matthew R.; Zheng, Bo; Leśniewska, Joanna; Mellerowicz, Ewa J.; Laux, Thomas; Sandberg, Göran; Jones, Brian

    2011-01-01

    SHORT-ROOT (SHR) is a well characterized regulator of cell division and cell fate determination in the Arabidopsis primary root. However, much less is known about the functions of SHR in the aerial parts of the plant. In this work, we cloned SHR gene from Populus trichocarpa (PtSHR1) as an AtSHR ortholog and down-regulated its expression in hybrid poplar (Populus tremula×P. tremuloides Michx-clone T89) in order to determine its physiological functions in shoot development. Sharing a 90% similarity to AtSHR at amino acid level, PtSHR1 was able to complement the Arabidopsis shr mutant. Down regulation of PtSHR1 led to a strong enhancement of primary (height) and secondary (girth) growth rates in the transgenic poplars. A similar approach in Arabidopsis showed a comparable accelerated growth and development phenotype. Our results suggest that the response to SHR could be dose-dependent and that a partial down-regulation of SHR could lead to enhanced meristem activity and a coordinated acceleration of plant growth in woody species. Therefore, SHR functions in plant growth and development as a regulator of cell division and meristem activity not only in the roots but also in the shoots. Reducing SHR expression in transgenic poplar was shown to lead to significant increases in primary and secondary growth rates. Given the current interest in bioenergy crops, SHR has a broader role as a key regulator of whole plant growth and development and SHR suppression has considerable potential for accelerating biomass accumulation in a variety of species. PMID:22194939

  14. A critical point of male gonad development: neuroendocrine correlates of accelerated testicular growth in rats during early life.

    PubMed

    Dygalo, Nikolay N; Shemenkova, Tatjana V; Kalinina, Tatjana S; Shishkina, Galina T

    2014-01-01

    Testis growth during early life is important for future male fertility and shows acceleration during the first months of life in humans. This acceleration coincides with the peak in gonadotropic hormones in the blood, while the role of hypothalamic factors remains vague. Using neonatal rats to assess this issue, we found that day 9 of life is likely critical for testis development in rats. Before this day, testicular growth was proportional to body weight gain, but after that the testes showed accelerated growth. Hypothalamic kisspeptin and its receptor mRNA levels begin to elevate 2 days later, at day 11. A significant increase in the mRNA levels for gonadotropin-releasing hormone (GnRH) receptors in the hypothalamus between days 5 and 7 was followed by a 3-fold decrease in GnRH mRNA levels in this brain region during the next 2 days. Starting from day 9, hypothalamic GnRH mRNA levels increased significantly and positively correlated with accelerated testicular growth. Triptorelin, an agonist of GnRH, at a dose that had no effect on testicular growth during "proportional" period, increased testis weights during the period of accelerated growth. The insensitivity of testicular growth to GnRH during "proportional" period was supported by inability of a 2.5-fold siRNA knockdown of GnRH expression in the hypothalamus of the 7-day-old animals to produce any effect on their testis weights. GnRH receptor blockade with cetrorelix was also without effect on testis weights during "proportional" period but the same doses of this GnRH antagonist significantly inhibited "accelerated" testicular growth. GnRH receptor mRNA levels in the pituitary as well as plasma LH concentrations were higher during "accelerated" period of testicular growth than during "proportional" period. In general, our data defined two distinct periods in rat testicular development that are primarily characterized by different responses to GnRH signaling.

  15. The structural alteration of gut microbiota in low-birth-weight mice undergoing accelerated postnatal growth

    PubMed Central

    Wang, Jingjing; Tang, Huang; Wang, Xiaoxin; Zhang, Xu; Zhang, Chenhong; Zhang, Menghui; Zhao, Yufeng; Zhao, Liping; Shen, Jian

    2016-01-01

    The transient disruption of gut microbiota in infancy by antibiotics causes adult adiposity in mice. Accelerated postnatal growth (A) leads to a higher risk of adult metabolic syndrome in low birth-weight (LB) humans than in normal birth-weight (NB) individuals, but the underlying mechanism remains unclear. Here, we set up an experiment using LB + A mice, NB + A mice, and control mice with NB and normal postnatal growth. At 24 weeks of age (adulthood), while NB + A animals had a normal body fat content and glucose tolerance compared with controls, LB + A mice exhibited excessive adiposity and glucose intolerance. In infancy, more fecal bacteria implicated in obesity were increased in LB + A pups than in NB + A pups, including Desulfovibrionaceae, Enterorhabdus, and Barnesiella. One bacterium from the Lactobacillus genus, which has been implicated in prevention of adult adiposity, was enhanced only in NB + A pups. Besides, LB + A pups, but not NB + A pups, showed disrupted gut microbiota fermentation activity. After weaning, the fecal microbiota composition of LB + A mice, but not that of NB + A animals, became similar to that of controls by 24 weeks. In infancy, LB + A mice have a more dysbiotic gut microbiome compared to NB + A mice, which might increase their risk of adult metabolic syndrome. PMID:27277748

  16. National health spending in 2011: overall growth remains low, but some payers and services show signs of acceleration.

    PubMed

    Hartman, Micah; Martin, Anne B; Benson, Joseph; Catlin, Aaron

    2013-01-01

    In 2011 US health care spending grew 3.9 percent to reach $2.7 trillion, marking the third consecutive year of relatively slow growth. Growth in national health spending closely tracked growth in nominal gross domestic product (GDP) in 2010 and 2011, and health spending as a share of GDP remained stable from 2009 through 2011, at 17.9 percent. Even as growth in spending at the national level has remained stable, personal health care spending growth accelerated in 2011 (from 3.7 percent to 4.1 percent), in part because of faster growth in spending for prescription drugs and physician and clinical services. There were also divergent trends in spending growth in 2011 depending on the payment source: Medicaid spending growth slowed, while growth in Medicare, private health insurance, and out-of-pocket spending accelerated. Overall, there was relatively slow growth in incomes, jobs, and GDP in 2011, which raises questions about whether US health care spending will rebound over the next few years as it typically has after past economic downturns.

  17. A Bayesian analysis of the effect of selection for growth rate on growth curves in rabbits

    PubMed Central

    Blasco, Agustín; Piles, Miriam; Varona, Luis

    2003-01-01

    Gompertz growth curves were fitted to the data of 137 rabbits from control (C) and selected (S) lines. The animals came from a synthetic rabbit line selected for an increased growth rate. The embryos from generations 3 and 4 were frozen and thawed to be contemporary of rabbits born in generation 10. Group C was the offspring of generations 3 and 4, and group S was the contemporary offspring of generation 10. The animals were weighed individually twice a week during the first four weeks of life, and once a week thereafter, until 20 weeks of age. Subsequently, the males were weighed weekly until 40 weeks of age. The random samples of the posterior distributions of the growth curve parameters were drawn by using Markov Chain Monte Carlo (MCMC) methods. As a consequence of selection, the selected animals were heavier than the C animals throughout the entire growth curve. Adult body weight, estimated as a parameter of the Gompertz curve, was 7% higher in the selected line. The other parameters of the Gompertz curve were scarcely affected by selection. When selected and control growth curves are represented in a metabolic scale, all differences disappear. PMID:12605849

  18. Examining the limits of time reweighting and Kramers' rate theory to obtain correct kinetics from accelerated molecular dynamics.

    PubMed

    Xin, Yao; Doshi, Urmi; Hamelberg, Donald

    2010-06-14

    Accelerated molecular dynamics simulations are routinely being used to recover the correct canonical probability distributions corresponding to the original potential energy landscape of biomolecular systems. However, the limits of time reweighting, based on transition state theory, in obtaining true kinetic rates from accelerated molecular dynamics for biomolecular systems are less obvious. Here, we investigate this issue by studying the kinetics of cis-trans isomerization of peptidic omega bond by accelerated molecular dynamics. We find that time reweighting is valid for obtaining true kinetics when the original potential is not altered at the transition state regions, as expected. When the original potential landscape is modified such that the applied boost potential alters the transition state regions, time reweighting fails to reproduce correct kinetics and the reweighted rate is much slower than the true rate. By adopting the overdamped limit of Kramers' rate theory, we are successful in recovering correct kinetics irrespective of whether or not the transition state regions are modified. Furthermore, we tested the validity of the acceleration weight factor from the path integral formalism for obtaining the correct kinetics of cis-trans isomerization. It was found that this formulation of the weight factor is not suitable for long time scale processes such as cis-trans isomerization with high energy barriers.

  19. Language-Dependent Pitch Encoding Advantage in the Brainstem Is Not Limited to Acceleration Rates that Occur in Natural Speech

    ERIC Educational Resources Information Center

    Krishnan, Ananthanarayan; Gandour, Jackson T.; Smalt, Christopher J.; Bidelman, Gavin M.

    2010-01-01

    Experience-dependent enhancement of neural encoding of pitch in the auditory brainstem has been observed for only specific portions of native pitch contours exhibiting high rates of pitch acceleration, irrespective of speech or nonspeech contexts. This experiment allows us to determine whether this language-dependent advantage transfers to…

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

    NASA Technical Reports Server (NTRS)

    Hansen, James; Kharecha, Pushker; Sato, Makiko

    2013-01-01

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

  1. Generalized Temporal Acceleration Scheme for Kinetic Monte Carlo Simulations of Surface Catalytic Processes by Scaling the Rates of Fast Reactions.

    PubMed

    Dybeck, Eric Christopher; Plaisance, Craig Patrick; Neurock, Matthew

    2017-02-14

    A novel algorithm has been developed to achieve temporal acceleration during kinetic Monte Carlo (KMC) simulations of surface catalytic processes. This algorithm allows for the direct simulation of reaction networks containing kinetic processes occurring on vastly disparate timescales which computationally overburden standard KMC methods. Previously developed methods for temporal acceleration in KMC have been designed for specific systems and often require a priori information from the user such as identifying the fast and slow processes. In the approach presented herein, quasi-equilibrated processes are identified automatically based on previous executions of the forward and reverse reactions. Temporal acceleration is achieved by automatically scaling the intrinsic rate constants of the quasi-equilibrated processes, bringing their rates closer to the timescales of the slow kinetically relevant non-equilibrated processes. All reactions are still simulated directly, although with modified rate constants. Abrupt changes in the underlying dynamics of the reaction network are identified during the simulation and the reaction rate constants are rescaled accordingly. The algorithm has been utilized here to model the Fischer-Tropsch synthesis reaction over ruthenium nanoparticles. This reaction network has multiple timescale-disparate processes which would be intractable to simulate without the aid of temporal acceleration. The accelerated simulations are found to give reaction rates and selectivities indistinguishable from those calculated by an equivalent mean-field kinetic model. The computational savings of the algorithm can span many orders of magnitude in realistic systems and the computational cost is not limited by the magnitude of the timescale disparity in the system processes. Furthermore, the algorithm has been designed in a generic fashion and can easily be applied to other surface catalytic processes of interest.

  2. Ocean Acidification Accelerates the Growth of Two Bloom-Forming Macroalgae

    PubMed Central

    Young, Craig S.; Gobler, Christopher J.

    2016-01-01

    While there is growing interest in understanding how marine life will respond to future ocean acidification, many coastal ecosystems currently experience intense acidification in response to upwelling, eutrophication, or riverine discharge. Such acidification can be inhibitory to calcifying animals, but less is known regarding how non-calcifying macroalgae may respond to elevated CO2. Here, we report on experiments performed during summer through fall with North Atlantic populations of Gracilaria and Ulva that were grown in situ within a mesotrophic estuary (Shinnecock Bay, NY, USA) or exposed to normal and elevated, but environmentally realistic, levels of pCO2 and/or nutrients (nitrogen and phosphorus). In nearly all experiments, the growth rates of Gracilaria were significantly increased by an average of 70% beyond in situ and control conditions when exposed to elevated levels of pCO2 (p<0.05), but were unaffected by nutrient enrichment. In contrast, the growth response of Ulva was more complex as this alga experienced significantly (p<0.05) increased growth rates in response to both elevated pCO2 and elevated nutrients and, in two cases, pCO2 and nutrients interacted to provide a synergistically enhanced growth rate for Ulva. Across all experiments, elevated pCO2 significantly increased Ulva growth rates by 30% (p<0.05), while the response to nutrients was smaller (p>0.05). The δ13C content of both Gracilaria and Ulva decreased two-to-three fold when grown under elevated pCO2 (p<0.001) and mixing models demonstrated these macroalgae experienced a physiological shift from near exclusive use of HCO3- to primarily CO2 use when exposed to elevated pCO2. This shift in carbon use coupled with significantly increased growth in response to elevated pCO2 suggests that photosynthesis of these algae was limited by their inorganic carbon supply. Given that eutrophication can yield elevated levels of pCO2, this study suggests that the overgrowth of macroalgae in eutrophic

  3. Effect of compost temperature on oxygen uptake rate, specific growth rate and enzymatic activity of microorganisms in dairy cattle manure.

    PubMed

    Miyatake, Fumihito; Iwabuchi, Kazunori

    2006-05-01

    Investigations were carried out to find out the relationship between temperature and microbial activity in dairy cattle manure composting using oxygen uptake rate, specific growth rate and enzymatic activities during autothermal and isothermal composting experiments. In autothermal composting, oxygen uptake rate and specific growth rate were found to be most intensive in order of 43 degrees C, 60 degrees C and 54 degrees C. Isothermal composting at 54 degrees C resulted highest levels of enzymatic activity and promoted the volatile solids reduction. Based on the maximum enzymatic activity, specific growth rate appeared to be more closely linked with microbial activity in compost than with oxygen uptake rate. The enhancement of specific growth rate, enzymatic activity and volatile solids reduction were induced at 54 degrees C in cattle manure composting.

  4. Growth rate regulation of lac operon expression in Escherichia coli is cyclic AMP dependent.

    PubMed

    Kuo, Jong-Tar; Chang, Yu-Jen; Tseng, Ching-Ping

    2003-10-23

    In contrast to the ribosomal RNA gene expression increasing with growth rate, transcription of the lac operon is downregulated by cell growth rate. In continuous culture, growth rate regulation of lac promoter was independent of carbon substrate used and its location on the chromosome. Since the lac operon is activated by cyclic adenosine monophosphate (cAMP), which decreases with increasing cell growth rate, expression of plac-lacZ reporter fusion was analyzed in cya mutant under various growth conditions. The results demonstrated that expression of plac-lacZ in cya mutant was both lower and growth rate independent. In addition, ppGpp (guanosine tetraphosphate) was not involved in the mechanism of growth rate regulation of the lac promoter. Thus, the results of this study indicate that cAMP mediates the growth rate-dependent regulation of lac operon expression in Escherichia coli.

  5. Dual-mass vibratory rate gyroscope with suppressed translational acceleration response and quadrature-error correction capability

    NASA Technical Reports Server (NTRS)

    Clark, William A. (Inventor); Juneau, Thor N. (Inventor); Lemkin, Mark A. (Inventor); Roessig, Allen W. (Inventor)

    2001-01-01

    A microfabricated vibratory rate gyroscope to measure rotation includes two proof-masses mounted in a suspension system anchored to a substrate. The suspension has two principal modes of compliance, one of which is driven into oscillation. The driven oscillation combined with rotation of the substrate about an axis perpendicular to the substrate results in Coriolis acceleration along the other mode of compliance, the sense-mode. The sense-mode is designed to respond to Coriolis accelerationwhile suppressing the response to translational acceleration. This is accomplished using one or more rigid levers connecting the two proof-masses. The lever allows the proof-masses to move in opposite directions in response to Coriolis acceleration. The invention includes a means for canceling errors, termed quadrature error, due to imperfections in implementation of the sensor. Quadrature-error cancellation utilizes electrostatic forces to cancel out undesired sense-axis motion in phase with drive-mode position.

  6. Accelerated forgetting? An evaluation on the use of long-term forgetting rates in patients with memory problems.

    PubMed

    Geurts, Sofie; van der Werf, Sieberen P; Kessels, Roy P C

    2015-01-01

    The main focus of this review was to evaluate whether long-term forgetting rates (delayed tests, days, to weeks, after initial learning) are more sensitive measures than standard delayed recall measures to detect memory problems in various patient groups. It has been suggested that accelerated forgetting might be characteristic for epilepsy patients, but little research has been performed in other populations. Here, we identified eleven studies in a wide range of brain injured patient groups, whose long-term forgetting patterns were compared to those of healthy controls. Signs of accelerated forgetting were found in three studies. The results of eight studies showed normal forgetting over time for the patient groups. However, most of the studies used only a recognition procedure, after optimizing initial learning. Based on these results, we recommend the use of a combined recall and recognition procedure to examine accelerated forgetting and we discuss the relevance of standard and optimized learning procedures in clinical practice.

  7. Accelerated forgetting? An evaluation on the use of long-term forgetting rates in patients with memory problems

    PubMed Central

    Geurts, Sofie; van der Werf, Sieberen P.; Kessels, Roy P. C.

    2015-01-01

    The main focus of this review was to evaluate whether long-term forgetting rates (delayed tests, days, to weeks, after initial learning) are more sensitive measures than standard delayed recall measures to detect memory problems in various patient groups. It has been suggested that accelerated forgetting might be characteristic for epilepsy patients, but little research has been performed in other populations. Here, we identified eleven studies in a wide range of brain injured patient groups, whose long-term forgetting patterns were compared to those of healthy controls. Signs of accelerated forgetting were found in three studies. The results of eight studies showed normal forgetting over time for the patient groups. However, most of the studies used only a recognition procedure, after optimizing initial learning. Based on these results, we recommend the use of a combined recall and recognition procedure to examine accelerated forgetting and we discuss the relevance of standard and optimized learning procedures in clinical practice. PMID:26106343

  8. Determination of the cosmological rate of change of G and the tidal accelerations of earth and moon from ancient and modern astronomical data

    NASA Technical Reports Server (NTRS)

    Muller, P. M.

    1976-01-01

    The theory and numerical analysis of ancient astronomical observations (1374 to 1715) are combined with modern data in a simultaneous solution for: the tidal acceleration of the lunar longitude; the observed apparent acceleration of the earth's rotation; the true nontidal geophysical part of this acceleration; and the rate of change in the gravitational constant. Provided are three independent determinations of a rate of change of G consistent with the Hubble Constant and a near zero nontidal rotational acceleration of the earth. The tidal accelerations are shown to have remained constant during the historical period within uncertainties. Ancient and modern solar system data, and extragalactic observations provided a completely consistent astronomical and cosmological scheme.

  9. Accelerated crack growth, residual stress, and a cracked zinc coated pressure shell

    NASA Technical Reports Server (NTRS)

    Dittman, Daniel L.; Hampton, Roy W.; Nelson, Howard G.

    1987-01-01

    During a partial inspection of a 42 year old, operating, pressurized wind tunnel at NASA-Ames Research Center, a surface connected defect 114 in. long having an indicated depth of a 0.7 in. was detected. The pressure shell, constructed of a medium carbon steel, contains approximately 10 miles of welds and is cooled by flowing water over its zinc coated external surface. Metallurgical and fractographic analysis showed that the actual detect was 1.7 in. deep, and originated from an area of lack of weld penetration. Crack growth studies were performed on the shell material in the laboratory under various loading rates, hold times, and R-ratios with a simulated shell environment. The combination of zinc, water with electrolyte, and steel formed an electrolytic cell which resulted in an increase in cyclic crack growth rate by as much as 500 times over that observed in air. It was concluded that slow crack growth occurred in the pressure shell by a combination of stress corrosion cracking due to the welding residual stress and corrosion fatigue due to the cyclic operating stress.

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

  11. Body composition of piglets exhibiting different growth rates

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  12. Thin liquid sheet target capabilities for ultra-intense laser acceleration of ions at a kHz repetition rate

    NASA Astrophysics Data System (ADS)

    Klim, Adam; Morrison, J. T.; Orban, C.; Feister, S.; Ngirmang, G. K.; Smith, J.; Frische, K.; Peterson, A. C.; Chowdhury, E. A.; Freeman, R. R.; Roquemore, W. M.

    2016-10-01

    The success of laser-accelerated ion experiments depends crucially on a number of factors including how thin the targets can be created. We present experimental results demonstrating extremely thin (under 200 nm) water sheet targets that can be used for ultra-intense laser-accelerated ion experiments conducted at the Air Force Research Laboratory at Wright-Patterson Air Force Base. Importantly, these experiments operate at a kHz repetition rate and the recovery time of the liquid targets is fast enough to allow the laser to interact with a refreshed, thin target on every shot. We present results from liquid water targets which are useful for proton acceleration experiments via the mechanism of Target Normal Sheath Acceleration (TNSA). In future work, we will create thin sheets from deuterated water in order to perform laser-accelerated deuteron experiments. This research was sponsored by the Quantum and Non-Equilibrium Processes Division of the AFOSR, under the management of Dr. Enrique Parra, and support from the DOD HPCMP Internship Program.

  13. Simultaneous identification of growth law and estimation of its rate parameter for biological growth data: a new approach.

    PubMed

    Bhowmick, Amiya Ranjan; Chattopadhyay, Gaurangadeb; Bhattacharya, Sabyasachi

    2014-01-01

    Scientific formalizations of the notion of growth and measurement of the rate of growth in living organisms are age-old problems. The most frequently used metric, "Average Relative Growth Rate" is invariant under the choice of the underlying growth model. Theoretically, the estimated rate parameter and relative growth rate remain constant for all mutually exclusive and exhaustive time intervals if the underlying law is exponential but not for other common growth laws (e.g., logistic, Gompertz, power, general logistic). We propose a new growth metric specific to a particular growth law and show that it is capable of identifying the underlying growth model. The metric remains constant over different time intervals if the underlying law is true, while the extent of its variation reflects the departure of the assumed model from the true one. We propose a new estimator of the relative growth rate, which is more sensitive to the true underlying model than the existing one. The advantage of using this is that it can detect crucial intervals where the growth process is erratic and unusual. It may help experimental scientists to study more closely the effect of the parameters responsible for the growth of the organism/population under study.

  14. Zonal Flow Growth Rates: Modulational Instability vs Statistical Steady States.

    NASA Astrophysics Data System (ADS)

    Krommes, J. A.; Kolesnikov, R. A.

    2002-11-01

    The nonlinear growth rate of zonal flows has been the subject of various investigations. The calculations can be grouped into two major classes: those based on modulational instability of a fixed pump wave;(L. Chen et al., Phys. Plasmas 7), 3129 (2000); P. N. Guzdar et al., Phys. Rev. Lett. 87, 015001 (2001); C. N. Lashmore-Davies et al., Phys. Plasmas 8, 5121 (2001). and those employing statistical formalism to describe a self-consistent, energy-conserving steady state.(J. A. Krommes and C.--B. Kim, Phys. Rev. E 62), 8508 (2000), and references therein. The results from these two approaches do not necessarily agree either in their dependence on parameters like the plasma pressure β, on the threshold for instability, or even, in some cases, on the sign. The reasons for such disagreements are isolated, and it is shown to what extent the steady-state statistical approach can be reconciled with a generic modulational instability calculation. Generalizations of the statistical formalism to the multifield systems appropriate for finite β are described. Specific calculations based on model systems are used to illustrate the general arguments.

  15. Dysfunctional Transforming Growth Factor-β Receptor II Accelerates Prostate Tumorigenesis in the TRAMP Mouse Model

    PubMed Central

    Pu, Hong; Collazo, Joanne; Jones, Elisabeth; Gayheart, Dustin; Sakamoto, Shinichi; Vogt, Adam; Mitchell, Bonnie; Kyprianou, Natasha

    2009-01-01

    The contribution of a dysfunctional TGF-β type II receptor (TGFβRII) to prostate cancer initiation and progression was investigated in an in vivo mouse model. Transgenic mice harboring the dominant-negative mutant TGF-β type II receptor (DNTGFβRII) in mouse epithelial cell were crossed with the TRAMP prostate cancer transgenic mouse to characterize the in vivo consequences of inactivated TGF-β signaling on prostate tumor initiation and progression. Histopathological diagnosis of prostate specimens from the TRAMP+/DNTGFβRII double transgenic mice, revealed the appearance of early malignant changes and subsequently highly aggressive prostate tumors at a younger age, compared to littermates TRAMP+/Wt TGFβRII mice. Immunohistochemical and western blotting analysis revealed significantly increased proliferative and apoptotic activities, as well as vascularity and macrophage infiltration that correlated with an elevated VEGF and MCP-1 protein levels in prostates from TRAMP+/DNTGFβRII+ mice. An epithelial-mesenchymal transition (EMT)-effect was also detected in prostates of TRAMP+/DNTGFβRII mice, as documented by the loss of epithelial markers (E-cadherin and β-catenin) and upregulation of mesenchymal markers (N-cadherin) and EMT-transcription factor Snail. A significant increase in the androgen receptor (AR) mRNA and protein levels was associated with the early onset of prostate tumorigenesis in TRAMP+/DNTGFβRII mice. Our results indicate that in vivo disruption of TGF-β signaling accelerates the pathological malignant changes in the prostate by altering the kinetics of prostate growth and inducing EMT. The study also suggests that a dysfunctional TGFβRII augments AR expression and promotes inflammation in early stage tumor growth thus conferring a significant contribution by TGF-β to prostate cancer progression. PMID:19738062

  16. Technology evaluation of man-rated acceleration test equipment for vestibular research

    NASA Technical Reports Server (NTRS)

    Taback, I.; Kenimer, R. L.; Butterfield, A. J.

    1983-01-01

    The considerations for eliminating acceleration noise cues in horizontal, linear, cyclic-motion sleds intended for both ground and shuttle-flight applications are addressed. the principal concerns are the acceleration transients associated with change in direction-of-motion for the carriage. The study presents a design limit for acceleration cues or transients based upon published measurements for thresholds of human perception to linear cyclic motion. The sources and levels for motion transients are presented based upon measurements obtained from existing sled systems. The approaches to a noise-free system recommends the use of air bearings for the carriage support and moving-coil linear induction motors operating at low frequency as the drive system. Metal belts running on air bearing pulleys provide an alternate approach to the driving system. The appendix presents a discussion of alternate testing techniques intended to provide preliminary type data by means of pendulums, linear motion devices and commercial air bearing tables.

  17. Acceleration and Deceleration Capacity of Fetal Heart Rate in an In-Vivo Sheep Model

    PubMed Central

    Rivolta, Massimo W.; Stampalija, Tamara; Casati, Daniela; Richardson, Bryan S.; Ross, Michael G.; Frasch, Martin G.; Bauer, Axel; Ferrazzi, Enrico; Sassi, Roberto

    2014-01-01

    Background Fetal heart rate (FHR) variability is an indirect index of fetal autonomic nervous system (ANS) integrity. FHR variability analysis in labor fails to detect early hypoxia and acidemia. Phase-rectified signal averaging (PRSA) is a new method of complex biological signals analysis that is more resistant to non-stationarities, signal loss and artifacts. It quantifies the average cardiac acceleration and deceleration (AC/DC) capacity. Objective The aims of the study were: (1) to investigate AC/DC in ovine fetuses exposed to acute hypoxic-acidemic insult; (2) to explore the relation between AC/DC and acid-base balance; and (3) to evaluate the influence of FHR decelerations and specific PRSA parameters on AC/DC computation. Methods Repetitive umbilical cord occlusions (UCOs) were applied in 9 pregnant near-term sheep to obtain three phases of MILD, MODERATE, and SEVERE hypoxic-acidemic insult. Acid-base balance was sampled and fetal ECGs continuously recorded. AC/DC were calculated: (1) for a spectrum of T values (T = 1÷50 beats; the parameter limits the range of oscillations detected by PRSA); (2) on entire series of fetal RR intervals or on “stable” series that excluded FHR decelerations caused by UCOs. Results AC and DC progressively increased with UCOs phases (MILD vs. MODERATE and MODERATE vs. SEVERE, p<0.05 for DC  = 2–5, and AC  = 1–3). The time evolution of AC/DC correlated to acid-base balance (0.4<<0.9, p<0.05) with the highest for . PRSA was not independent from FHR decelerations caused by UCOs. Conclusions This is the first in-vivo evaluation of PRSA on FHR analysis. In the presence of acute hypoxic-acidemia we found increasing values of AC/DC suggesting an activation of ANS. This correlation was strongest on time scale dominated by parasympathetic modulations. We identified the best performing parameters (), and found that AC/DC computation is not independent from FHR decelerations. These findings establish the basis for

  18. Hypercholesterolemia induces angiogenesis and accelerates growth of breast tumors in vivo.

    PubMed

    Pelton, Kristine; Coticchia, Christine M; Curatolo, Adam S; Schaffner, Carl P; Zurakowski, David; Solomon, Keith R; Moses, Marsha A

    2014-07-01

    Obesity and metabolic syndrome are linked to an increased prevalence of breast cancer among postmenopausal women. A common feature of obesity, metabolic syndrome, and a Western diet rich in saturated fat is a high level of circulating cholesterol. Epidemiological reports investigating the relationship between high circulating cholesterol levels, cholesterol-lowering drugs, and breast cancer are conflicting. Here, we modeled this complex condition in a well-controlled, preclinical animal model using innovative isocaloric diets. Female severe combined immunodeficient mice were fed a low-fat/no-cholesterol diet and then randomized to four isocaloric diet groups: low-fat/no-cholesterol diet, with or without ezetimibe (cholesterol-lowering drug), and high-fat/high-cholesterol diet, with or without ezetimibe. Mice were implanted orthotopically with MDA-MB-231 cells. Breast tumors from animals fed the high-fat/high-cholesterol diet exhibited the fastest progression. Significant differences in serum cholesterol level between groups were achieved and maintained throughout the study; however, no differences were observed in intratumoral cholesterol levels. To determine the mechanism of cholesterol-induced tumor progression, we analyzed tumor proliferation, apoptosis, and angiogenesis and found a significantly greater percentage of proliferating cells from mice fed the high-fat/high-cholesterol diet. Tumors from hypercholesterolemic animals displayed significantly less apoptosis compared with the other groups. Tumors from high-fat/high-cholesterol mice had significantly higher microvessel density compared with tumors from the other groups. These results demonstrate that hypercholesterolemia induces angiogenesis and accelerates breast tumor growth in vivo.

  19. High expression of connective tissue growth factor accelerates dissemination of leukaemia.

    PubMed

    Wells, J E; Howlett, M; Halse, H M; Heng, J; Ford, J; Cheung, L C; Samuels, A L; Crook, M; Charles, A K; Cole, C H; Kees, U R

    2016-09-01

    To improve treatment of acute lymphoblastic leukaemia (ALL), a better understanding of disease development is needed to tailor new therapies. Connective tissue growth factor (CTGF/CCN2) is highly expressed in leukaemia cells from the majority of paediatric patients with B-lineage ALL (pre-B ALL). CTGF is a matricellular protein and plays a role in aggressive cancers. Here we have genetically engineered leukaemia cells to modulate CTGF expression levels. Elevated CTGF levels accelerated disease dissemination and reduced survival in NOD/SCID mice. In vitro studies showed that CTGF protein induces stromal cell proliferation, promotes adhesion of leukaemia cells to stromal cells and leads to overexpression of genes associated with cell cycle and synthesis of extracellular matrix (ECM). Corresponding data from our leukaemia xenograft models demonstrated that CTGF leads to increased proliferation of non-leukaemia cells and deposition of ECM in the bone marrow. We document for the first time a functional role of CTGF in altering disease progression in a lymphoid malignancy. The findings provide support for targeting the bone marrow microenvironment in aggressive forms of leukaemia.

  20. Accelerated Aging Experiments for Prognostics of Damage Growth in Composite Materials

    NASA Technical Reports Server (NTRS)

    Saxena, Abhinav; Goebel, Kai Frank; Larrosa, Cecilia C.; Janapati, Vishnuvardhan; Roy, Surajit; Chang, Fu-Kuo

    2011-01-01

    Composite structures are gaining importance for use in the aerospace industry. Compared to metallic structures their behavior is less well understood. This lack of understanding may pose constraints on their use. One possible way to deal with some of the risks associated with potential failure is to perform in-situ monitoring to detect precursors of failures. Prognostic algorithms can be used to predict impending failures. They require large amounts of training data to build and tune damage model for making useful predictions. One of the key aspects is to get confirmatory feedback from data as damage progresses. These kinds of data are rarely available from actual systems. The next possible resource to collect such data is an accelerated aging platform. To that end this paper describes a fatigue cycling experiment with the goal to stress carbon-carbon composite coupons with various layups. Piezoelectric disc sensors were used to periodically interrogate the system. Analysis showed distinct differences in the signatures of growing failures between data collected at conditions. Periodic X-radiographs were taken to assess the damage ground truth. Results after signal processing showed clear trends of damage growth that were correlated to damage assessed from the X-ray images.

  1. Results With Accelerated Partial Breast Irradiation in Terms of Estrogen Receptor, Progesterone Receptor, and Human Growth Factor Receptor 2 Status

    SciTech Connect

    Wilder, Richard B.; Curcio, Lisa D.; Khanijou, Rajesh K.; Eisner, Martin E.; Kakkis, Jane L.; Chittenden, Lucy; Agustin, Jeffrey; Lizarde, Jessica; Mesa, Albert V.; Macedo, Jorge C.; Ravera, John; Tokita, Kenneth M.

    2010-11-01

    Purpose: To report our results with accelerated partial breast irradiation (APBI) in terms of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER-2/neu) status. Methods and Materials: Between February 2003 and June 2009, 209 women with early-stage breast carcinomas were treated with APBI using multicatheter, MammoSite, or Contura brachytherapy to 34 Gy in 10 fractions twice daily over 5-7 days. Three patient groups were defined by receptor status: Group 1: ER or PR (+) and HER-2/neu (-) (n = 180), Group 2: ER and PR (-) and HER-2/neu (+) (n = 10), and Group 3: ER, PR, and HER-2/neu (-) (triple negative breast cancer, n = 19). Median follow-up was 22 months. Results: Group 3 patients had significantly higher Scarff-Bloom-Richardson scores (p < 0.001). The 3-year ipsilateral breast tumor control rates for Groups 1, 2, and 3 were 99%, 100%, and 100%, respectively (p = 0.15). Group 3 patients tended to experience relapse in distant sites earlier than did non-Group 3 patients. The 3-year relapse-free survival rates for Groups 1, 2, and 3 were 100%, 100%, and 81%, respectively (p = 0.046). The 3-year cause-specific and overall survival rates for Groups 1, 2, and 3 were 100%, 100%, and 89%, respectively (p = 0.002). Conclusions: Triple negative breast cancer patients typically have high-grade tumors with significantly worse relapse-free, cause-specific, and overall survival. Longer follow-up will help to determine whether these patients also have a higher risk of ipsilateral breast tumor relapse.

  2. Correlations of metabolic rate and body acceleration in three species of coastal sharks under contrasting temperature regimes.

    PubMed

    Lear, Karissa O; Whitney, Nicholas M; Brewster, Lauran R; Morris, Jack J; Hueter, Robert E; Gleiss, Adrian C

    2017-02-01

    The ability to produce estimates of the metabolic rate of free-ranging animals is fundamental to the study of their ecology. However, measuring the energy expenditure of animals in the field has proved difficult, especially for aquatic taxa. Accelerometry presents a means of translating metabolic rates measured in the laboratory to individuals studied in the field, pending appropriate laboratory calibrations. Such calibrations have only been performed on a few fish species to date, and only one where the effects of temperature were accounted for. Here, we present calibrations between activity, measured as overall dynamic body acceleration (ODBA), and metabolic rate, measured through respirometry, for nurse sharks (Ginglymostoma cirratum), lemon sharks (Negaprion brevirostris) and blacktip sharks (Carcharhinus limbatus). Calibrations were made at a range of volitional swimming speeds and experimental temperatures. Linear mixed models were used to determine a predictive equation for metabolic rate based on measured ODBA values, with the optimal model using ODBA in combination with activity state and temperature to predict metabolic rate in lemon and nurse sharks, and ODBA and temperature to predict metabolic rate in blacktip sharks. This study lays the groundwork for calculating the metabolic rate of these species in the wild using acceleration data.

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

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  4. Evolution of intrinsic growth rate: metabolic costs drive trade-offs between growth and swimming performance in Menidia menidia.

    PubMed

    Arnott, Stephen A; Chiba, Susumu; Conover, David O

    2006-06-01

    There is strong evidence that genetic capacity for growth evolves toward an optimum rather than an absolute maximum. This implies that fast growth has a cost and that trade-offs occur between growth and other life-history traits, but the fundamental mechanisms are poorly understood. Previous work on the Atlantic silverside fish Menidia menidia has demonstrated a trade-off between growth and swimming performance. We hypothesize that the trade-off derives from the competing metabolic demands associated with growth and swimming activity. We tested this by measuring standard metabolic rate (M(STD)), maximum sustainable metabolic rate (M(ACT)) and metabolic scope of laboratory-reared silversides originating from two geographically distinct populations with well-documented differences in genetic capacity for growth. The fast-growth genotype had a significantly greater M(STD) than the slow-growth genotype, but a similar MACT when swum to near exhaustion. The scope for activity of the fast-growth genotype was lower than that of the slow-growth genotype. Furthermore, the fast-growth genotype eats larger meals, thereby incurring a greater postprandial oxygen demand. We conclude that a metabolic trade-off occurs between growth and other metabolic demands and that this trade-off provides a general mechanism underlying the evolution of growth rate.

  5. Anabolic therapy with growth hormone accelerates protein gain in surgical patients requiring nutritional rehabilitation.

    PubMed Central

    Byrne, T A; Morrissey, T B; Gatzen, C; Benfell, K; Nattakom, T V; Scheltinga, M R; LeBoff, M S; Ziegler, T R; Wilmore, D W

    1993-01-01

    OBJECTIVE: The authors investigated the effects of exogenous growth hormone (GH) on protein accretion and the composition of weight gain in a group of stable, nutritionally compromised postoperative patients receiving standard hypercaloric nutritional therapy. SUMMARY BACKGROUND DATA: A significant loss of body protein impairs normal physiologic functions and is associated with increased postoperative complications and prolonged hospitalization. Previous studies have demonstrated that standard methods of nutritional support enhance the deposition of fat and extracellular water but are ineffective in repleting body protein. METHODS: Fourteen patients requiring long-term nutritional support for severe gastrointestinal dysfunction received standard nutritional therapy (STD) providing approximately 50 kcal/kg/day and 2 g of protein/kg/day during an initial 7-day equilibrium period. The patients then continued on STD (n = 4) or, in addition, received GH 0.14 mg/kg/day (n = 10). On day 7 of the equilibrium period and again after 3 weeks of treatment, the components of body weight were determined; these included body fat, mineral content, lean (nonfat and nonmineral-containing tissue) mass, total body water, extracellular water (ECW), and body protein. Daily and cumulative nutrient balance and substrate oxidation studies determined the distribution, efficiency, and utilization of calories for protein, fat, and carbohydrate deposition. RESULTS: The GH-treated patients gained minimal body fat but had significantly more lean mass (4.311 +/- 0.6 kg vs. 1.988 +/- 0.2 kg, p < or = 0.03) and more protein (1.417 +/- 0.3 kg vs. 0.086 +/- 0.1 kg, p < or = 0.03) than did the STD-treated patients. The increase in lean mass was not associated with an inappropriate expansion of ECW. In contrast, patients receiving STD therapy tended to deposit a greater proportion of body weight as ECW and significantly more fat than did GH-treated patients (1.004 +/- 0.3 kg vs. 0.129 +/- 0.2 kg, p < 0

  6. Developmental transcription of genes putatively associated with growth in two sturgeon species of different growth rate.

    PubMed

    Miandare, Hamed Kolangi; Farahmand, Hamid; Akbarzadeh, Arash; Ramezanpour, Sanaz; Kaiya, Hiroyuki; Miyazato, Mikiya; Rytkönen, Kalle T; Nikinmaa, Mikko

    2013-02-01

    In the present study, we surveyed developmental changes in the transcription of growth hormone (gh), insulin-like growth factor-I (igf-I), ghrelin (ghrl) and vascular endothelial growth factor (vegf) genes in the largest freshwater fish, European sturgeon (Beluga, Huso huso) and compared the same parameters to that of its phylogenically close moderate-sized species, Persian sturgeon (Acipenser persicus). The transcripts of gh, igf-I, ghrl and vegf were detected at all developmental time-points of Persian sturgeon and Beluga from embryos to juvenile fish. Changes in normalized gh, igf-I, ghrl and vegf transcription by using the geometric average of genes encoding ribosomal protein L6 (RPL6) and elongation factor (EF1A) over the time of development of Persian sturgeon and Beluga were statistically significant (P<0.05). Our results showed that the mRNA expression levels of both igf-I and ghrl were low during early larval development and then increased significantly to the late larval time-points when larvae started exogenous feeding. In both Beluga and Persian sturgeon, after a low mRNA expression during the embryonic stage, the transcript levels of vegf displayed an increasing trend during yolk-sac fry, consistent with organogenesis. The vegf level remained constantly high in the time of exogenous feeding. The highest detection of gh transcripts coincided with the end of the embryonic stage (hatching time) in Persian sturgeon and 3 days-post-hatching (dph) in Beluga. In Persian sturgeon, the gh transcript started to decrease to the rest of the developmental time-points, whereas in Beluga gh transcript had a marked second increase from the time of exogenous feeding (20-dph). This Beluga specific increase in gh transcription may be associated with the marked growth rate and extraordinary size of this fish species.

  7. In vivo human left-to-right ventricular differences in rate adaptation transiently increase pro-arrhythmic risk following rate acceleration.

    PubMed

    Bueno-Orovio, Alfonso; Hanson, Ben M; Gill, Jaswinder S; Taggart, Peter; Rodriguez, Blanca

    2012-01-01

    Left-to-right ventricular (LV/RV) differences in repolarization have been implicated in lethal arrhythmias in animal models. Our goal is to quantify LV/RV differences in action potential duration (APD) and APD rate adaptation and their contribution to arrhythmogenic substrates in the in vivo human heart using combined in vivo and in silico studies. Electrograms were acquired from 10 LV and 10 RV endocardial sites in 15 patients with normal ventricles. APD and APD adaptation were measured during an increase in heart rate. Analysis of in vivo electrograms revealed longer APD in LV than RV (207.8 ± 21.5 vs 196.7 ± 20.1 ms; P<0.05), and slower APD adaptation in LV than RV (time constant τ(s) =47.0 ± 14.3 vs 35.6 ± 6.5 s; P<0.05). Following rate acceleration, LV/RV APD dispersion experienced an increase of up to 91% in 12 patients, showing a strong correlation (r(2) =0.90) with both initial dispersion and LV/RV difference in slow adaptation. Pro-arrhythmic implications of measured LV/RV functional differences were studied using in silico simulations. Results show that LV/RV APD and APD adaptation heterogeneities promote unidirectional block following rate acceleration, albeit being insufficient for establishment of reentry in normal hearts. However, in the presence of an ischemic region at the LV/RV junction, LV/RV heterogeneity in APD and APD rate adaptation promotes reentrant activity and its degeneration into fibrillatory activity. Our results suggest that LV/RV heterogeneities in APD adaptation cause a transient increase in APD dispersion in the human ventricles following rate acceleration, which promotes unidirectional block and wave-break at the LV/RV junction, and may potentiate the arrhythmogenic substrate, particularly in patients with ischemic heart disease.

  8. Acceleration of ventricular rate by amiodarone in atrial fibrillation associated with the Wolff-Parkinson-White syndrome

    PubMed Central

    Sheinman, Bryan D; Evans, Tom

    1982-01-01

    Amiodarone has proved to be a valuable drug in atrial fibrillation associated with the Wolff-Parkinson-White syndrome. When it was administered to a patient with this syndrome in atrial fibrillation, who had previously suffered an inferior myocardial infarction, the ventricular rate accelerated from 170 to 230 beats/minute. This unusual case emphasises the need for full electrophysiological assessment of patients with the Wolff-Parkinson-White syndrome for whom amiodarone treatment is being considered. Imagesp1000-a PMID:6812745

  9. Physiological growth hormone replacement and rate of recurrence of craniopharyngioma: the Genentech National Cooperative Growth Study.

    PubMed

    Smith, Timothy R; Cote, David J; Jane, John A; Laws, Edward R

    2016-10-01

    OBJECTIVE The object of this study was to establish recurrence rates in patients with craniopharyngioma postoperatively treated with recombinant human growth hormone (rhGH) as a basis for determining the risk of rhGH therapy in the development of recurrent tumor. METHODS The study included 739 pediatric patients with craniopharyngioma who were naïve to GH upon entering the Genentech National Cooperative Growth Study (NCGS) for treatment. Reoperation for tumor recurrence was documented as an adverse event. Cox proportional-hazards regression models were developed for time to recurrence, using age as the outcome and enrollment date as the predictor. Patients without recurrence were treated as censored. Multivariate logistic regression was used to examine the incidence of recurrence with adjustment for the amount of time at risk. RESULTS Fifty recurrences in these 739 surgically treated patients were recorded. The overall craniopharyngioma recurrence rate in the NCGS was 6.8%, with a median follow-up time of 4.3 years (range 0.7-6.4 years.). Age at the time of study enrollment was statistically significant according to both Cox (p = 0.0032) and logistic (p < 0.001) models, with patients under 9 years of age more likely to suffer recurrence (30 patients [11.8%], 0.025 recurrences/yr of observation, p = 0.0097) than those ages 9-13 years (17 patients [6.0%], 0.17 recurrences/yr of observation) and children older than 13 years (3 patients [1.5%], 0.005 recurrences/yr of observation). CONCLUSIONS Physiological doses of GH do not appear to increase the recurrence rate of craniopharyngioma after surgery in children, but long-term follow-up of GH-treated patients is required to establish a true natural history in the GH treatment era.

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

    DOE PAGES

    Sandoval, Luis; Perez, Danny; Uberuaga, Blas P.; ...

    2016-11-15

    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 106 to 1012 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 themore » bubble.« less

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

    SciTech Connect

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

    2016-11-15

    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 106 to 1012 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.

  12. Multiple Metazoan Life-span Interventions Exhibit a Sex-specific Strehler-Mildvan Inverse Relationship Between Initial Mortality Rate and Age-dependent Mortality Rate Acceleration.

    PubMed

    Shen, Jie; Landis, Gary N; Tower, John

    2017-01-01

    The Gompertz equation describes survival in terms of initial mortality rate (parameter a), indicative of health, and age-dependent acceleration in mortality rate (parameter b), indicative of aging. Gompertz parameters were analyzed for several published studies. In Drosophila females, mating increases egg production and decreases median life span, consistent with a trade-off between reproduction and longevity. Mating increased parameter a, causing decreased median life span, whereas time parameter b was decreased. The inverse correlation between parameters indicates the Strehler-Mildvan (S-M) relationship, where loss of low-vitality individuals yields a cohort with slower age-dependent mortality acceleration. The steroid hormone antagonist mifepristone/RU486 reversed these effects. Mating and mifepristone showed robust S-M relationships across genotypes, and dietary restriction showed robust S-M relationship across diets. Because nutrient optima differed between females and males, the same manipulation caused opposite effects on mortality rates in females versus males across a range of nutrient concentrations. Similarly, p53 mutation in Drosophila and mTOR mutation in mice caused increased median life span associated with opposite direction changes in mortality rate parameters in females versus males. The data demonstrate that dietary and genetic interventions have sex-specific and sometimes sexually opposite effects on mortality rates consistent with sexual antagonistic pleiotropy.

  13. Growth rate control of flagellar assembly in Escherichia coli strain RP437

    PubMed Central

    Sim, Martin; Koirala, Santosh; Picton, David; Strahl, Henrik; Hoskisson, Paul A.; Rao, Christopher V.; Gillespie, Colin S.; Aldridge, Phillip D.

    2017-01-01

    The flagellum is a rotary motor that enables bacteria to swim in liquids and swarm over surfaces. Numerous global regulators control flagellar assembly in response to cellular and environmental factors. Previous studies have also shown that flagellar assembly is affected by the growth-rate of the cell. However, a systematic study has not yet been described under controlled growth conditions. Here, we investigated the effect of growth rate on flagellar assembly in Escherichia coli using steady-state chemostat cultures where we could precisely control the cell growth-rate. Our results demonstrate that flagellar abundance correlates with growth rate, where faster growing cells produce more flagella. They also demonstrate that this growth-rate dependent control occurs through the expression of the flagellar master regulator, FlhD4C2. Collectively, our results demonstrate that motility is intimately coupled to the growth-rate of the cell. PMID:28117390

  14. Growth under elevated atmospheric CO(2) concentration accelerates leaf senescence in sunflower (Helianthus annuus L.) plants.

    PubMed

    de la Mata, Lourdes; Cabello, Purificación; de la Haba, Purificación; Agüera, Eloísa

    2012-09-15

    Some morphogenetic and metabolic processes were sensitive to a high atmospheric CO(2) concentration during sunflower primary leaf ontogeny. Young leaves of sunflower plants growing under elevated CO(2) concentration exhibited increased growth, as reflected by the high specific leaf mass referred to as dry weight in young leaves (16 days). The content of photosynthetic pigments decreased with leaf development, especially in plants grown under elevated CO(2) concentrations, suggesting that high CO(2) accelerates chlorophyll degradation, and also possibly leaf senescence. Elevated CO(2) concentration increased the oxidative stress in sunflower plants by increasing H(2)O(2) levels and decreasing activity of antioxidant enzymes such as catalase and ascorbate peroxidase. The loss of plant defenses probably increases the concentration of reactive oxygen species in the chloroplast, decreasing the photosynthetic pigment content as a result. Elevated CO(2) concentration was found to boost photosynthetic CO(2) fixation, especially in young leaves. High CO(2) also increased the starch and soluble sugar contents (glucose and fructose) and the C/N ratio during sunflower primary leaf development. At the beginning of senescence, we observed a strong increase in the hexoses to sucrose ratio that was especially marked at high CO(2) concentration. These results indicate that elevated CO(2) concentration could promote leaf senescence in sunflower plants by affecting the soluble sugar levels, the C/N ratio and the oxidative status during leaf ontogeny. It is likely that systemic signals produced in plants grown with elevated CO(2), lead to early senescence and a higher oxidation state of the cells of these plant leaves.

  15. Hypercholesterolemia Induces Angiogenesis and Accelerates Growth of Breast Tumors in Vivo

    PubMed Central

    Pelton, Kristine; Coticchia, Christine M.; Curatolo, Adam S.; Schaffner, Carl P.; Zurakowski, David; Solomon, Keith R.; Moses, Marsha A.

    2015-01-01

    Obesity and metabolic syndrome are linked to an increased prevalence of breast cancer among postmenopausal women. A common feature of obesity, metabolic syndrome, and a Western diet rich in saturated fat is a high level of circulating cholesterol. Epidemiological reports investigating the relationship between high circulating cholesterol levels, cholesterol-lowering drugs, and breast cancer are conflicting. Here, we modeled this complex condition in a well-controlled, preclinical animal model using innovative isocaloric diets. Female severe combined immunodeficient mice were fed a low-fat/no-cholesterol diet and then randomized to four isocaloric diet groups: low-fat/no-cholesterol diet, with or without ezetimibe (cholesterol-lowering drug), and high-fat/high-cholesterol diet, with or without ezetimibe. Mice were implanted orthotopically with MDA-MB-231 cells. Breast tumors from animals fed the high-fat/high-cholesterol diet exhibited the fastest progression. Significant differences in serum cholesterol level between groups were achieved and maintained throughout the study; however, no differences were observed in intratumoral cholesterol levels. To determine the mechanism of cholesterol-induced tumor progression, we analyzed tumor proliferation, apoptosis, and angiogenesis and found a significantly greater percentage of proliferating cells from mice fed the high-fat/high-cholesterol diet. Tumors from hypercholesterolemic animals displayed significantly less apoptosis compared with the other groups. Tumors from high-fat/high-cholesterol mice had significantly higher microvessel density compared with tumors from the other groups. These results demonstrate that hypercholesterolemia induces angiogenesis and accelerates breast tumor growth in vivo. PMID:24952430

  16. Estimating Reading Growth Attributable to Accelerated Reader at One American School in the Caribbean

    ERIC Educational Resources Information Center

    Foster, David K.; Foster, Dean P.

    2014-01-01

    This article provides a statistical analysis of the reading gains observed at one American school in the Caribbean that was using Accelerated Reader. It provides an estimate of the number of hours students needed to read to advance their reading performance an additional year. The authors estimate how much Accelerated Reader contributed to the…

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

    NASA Astrophysics Data System (ADS)

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

    2015-12-01

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

  18. Ice Particle Growth Rates Under Upper Troposphere Conditions

    NASA Technical Reports Server (NTRS)

    Peterson, Harold; Bailey, Matthew; Hallett, John

    2010-01-01

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

  19. Ice Crystal Growth Rates Under Upper Troposphere Conditions

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

  20. Stool consistency is strongly associated with gut microbiota richness and composition, enterotypes and bacterial growth rates

    PubMed Central

    Vandeputte, Doris; Falony, Gwen; Vieira-Silva, Sara; Tito, Raul Y; Joossens, Marie; Raes, Jeroen

    2016-01-01

    Objective The assessment of potentially confounding factors affecting colon microbiota composition is essential to the identification of robust microbiome based disease markers. Here, we investigate the link between gut microbiota variation and stool consistency using Bristol Stool Scale classification, which reflects faecal water content and activity, and is considered a proxy for intestinal colon transit time. Design Through 16S rDNA Illumina profiling of faecal samples of 53 healthy women, we evaluated associations between microbiome richness, Bacteroidetes:Firmicutes ratio, enterotypes, and genus abundance with self-reported, Bristol Stool Scale-based stool consistency. Each sample’s microbiota growth potential was calculated to test whether transit time acts as a selective force on gut bacterial growth rates. Results Stool consistency strongly correlates with all known major microbiome markers. It is negatively correlated with species richness, positively associated to the Bacteroidetes:Firmicutes ratio, and linked to Akkermansia and Methanobrevibacter abundance. Enterotypes are distinctly distributed over the BSS-scores. Based on the correlations between microbiota growth potential and stool consistency scores within both enterotypes, we hypothesise that accelerated transit contributes to colon ecosystem differentiation. While shorter transit times can be linked to increased abundance of fast growing species in Ruminococcaceae-Bacteroides samples, hinting to a washout avoidance strategy of faster replication, this trend is absent in Prevotella-enterotyped individuals. Within this enterotype adherence to host tissue therefore appears to be a more likely bacterial strategy to cope with washout. Conclusions The strength of the associations between stool consistency and species richness, enterotypes and community composition emphasises the crucial importance of stool consistency assessment in gut metagenome-wide association studies. PMID:26069274

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

    PubMed

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

    2015-03-27

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

  2. Growth rate and resource imbalance interactively control biomass stoichiometry and elemental quotas of aquatic bacteria.

    PubMed

    Godwin, Casey M; Whitaker, Emily A; Cotner, James B

    2017-03-01

    The effects of resource stoichiometry and growth rate on the elemental composition of biomass have been examined in a wide variety of organisms, but the interaction among these effects is often overlooked. To determine how growth rate and resource imbalance affect bacterial carbon (C): nitrogen (N): phosphorus (P) stoichiometry and elemental content, we cultured two strains of aquatic heterotrophic bacteria in chemostats at a range of dilution rates and P supply levels (C:P of 100:1 to 10,000:1). When growing below 50% of their maximum growth rate, P availability and dilution rate had strong interactive effects on biomass C:N:P, elemental quotas, cell size, respiration rate, and growth efficiency. In contrast, at faster growth rates, biomass stoichiometry was strongly homeostatic in both strains (C:N:P of 70:13:1 and 73:14:1) and elemental quotas of C, N, and P were tightly coupled (but not constant). Respiration and cell size increased with both growth rate and P limitation, and P limitation induced C accumulation and excess respiration. These results show that bacterial biomass stoichiometry is relatively constrained when all resources are abundant and growth rates are high, but at low growth rates resource imbalance is relatively more important than growth rate in controlling bacterial biomass composition.

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

    NASA Astrophysics Data System (ADS)

    Blagodatskaya, Evgenia; Blagodatsky, Sergey; Dorodnikov, Maxim; Kuzyakov, Yakov

    2010-05-01

    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 amount are sensitive to increased atmospheric CO2. We conclude that the more abundant available organics released by roots at elevated CO2 altered the ecological strategy of the soil microbial community specifically a shift to a higher contribution of fast-growing r-selected species was observed. These changes in functional structure of the soil microbial community may counterbalance higher C input into the soil under elevated atmospheric CO2 concentration.

  4. Plasma metabolite levels predict bird growth rates: A field test of model predictive ability.

    PubMed

    Albano, Noelia; Masero, José A; Villegas, Auxiliadora; Abad-Gómez, José María; Sánchez-Guzmán, Juan M

    2011-09-01

    Bird growth rates are usually derived from nonlinear relationships between age and some morphological structure, but this procedure may be limited by several factors. To date, nothing is known about the capacity of plasma metabolite profiling to predict chick growth rates. Based on laboratory-trials, we here develop predictive logistic models of body mass, and tarsus and wing length growth rates in Gull-billed Tern Gelochelidon nilotica chicks from measurements of plasma metabolite levels at different developmental stages. The predictive model obtained during the fastest growth period (at the age of 12 days) explained 65-68% of the chicks' growth rates, with fasting triglyceride level explaining most of the variation in growth rate. At the end of pre-fledging period, β-hydroxybutyrate level was also a good predictor of growth rates. Finally, we carried out a field test to check the predictive capacity of the models in two colonies of wild Gull-billed Tern, comparing field-measured and model-predicted growth rates between groups. Both, measured and predicted growth rates, matched statistically. Plasma metabolite levels can thus be applied in comparative studies of chick growth rates when semi-precocial birds can be captured only once.

  5. Metabolism correlates with variation in post-natal growth rate among songbirds at three latitudes

    USGS Publications Warehouse

    Ton, Riccardo; Martin, Thomas E.

    2016-01-01

    4. Our results suggest that variation in metabolic rates has an important influence on broad patterns of avian growth rates at a global scale. We suggest further studies that address the ecological and physiological costs and consequences of variation in metabolism and growth rates.

  6. Accelerating 21st Century Economic Growth by Implementation of the Lunar Solar Power System

    NASA Astrophysics Data System (ADS)

    Criswell, D. R.

    2002-01-01

    The World Energy Council (1) makes this declaration. "Given this dramatically uneven distribution and the limited evidence of improvement in economic growth in many developing countries, WEC at the 17th World Congress in Houston in September 1998 concluded that the number one priority in sustainable energy development today for all decision-makers in all countries is to extend access to commercial energy services to the people who do not now have it and to those who will come into the world in the next two decades, largely in developing countries, without such access." By ~2050 the global systems should supply 10 billion people approximately 6.7 kilowatts of thermal power per person or 61,360 kWt-h/y-person of energy. The economic equivalent is ~2 - 3 kWe of electric power per person. The energy must be environmentally clean. The energy must be sufficiently low in cost that the 2 billion poorest people, who now make 1,000 /y-person, can be provided with the new power. A survey of twenty-five options for providing adequate commercial electric power, including solar power satellites in orbit about Earth, concludes that only the Lunar Solar Power System can meet the WEC challenge (2, 3, 4, 5). Maurice Strong is the former CEO of Ontario Hydro and organizer of the 1992 Rio Environmental Summit. Quoting Strong - "I have checked it (LSP System) out with a number of experts, all of whom confirmed that the idea, which has been mooted for some time, may now be ripe to carry forward. --- The project would deliver net new energy to the Earth that is independent of the biosphere, would produce no CO2 or other polluting emissions and have minimal environmental impact compared with other energy sources." (6). Electric energy provided by the LSP System can accelerate terrestrial economic growth in several ways. A cost of less than 1 cent per kilowatt electric hour seems achievable. This allows poor nations to buy adequate energy. Increasing per capita use of electric power is

  7. The Impact of Back-Sputtered Carbon on the Accelerator Grid Wear Rates of the NEXT and NSTAR Ion Thrusters

    NASA Technical Reports Server (NTRS)

    Soulas, George C.

    2013-01-01

    A study was conducted to quantify the impact of back-sputtered carbon on the downstream accelerator grid erosion rates of the NASA's Evolutionary Xenon Thruster (NEXT) Long Duration Test (LDT1). A similar analysis that was conducted for the NASA's Solar Electric Propulsion Technology Applications Readiness Program (NSTAR) Life Demonstration Test (LDT2) was used as a foundation for the analysis developed herein. A new carbon surface coverage model was developed that accounted for multiple carbon adlayers before complete surface coverage is achieved. The resulting model requires knowledge of more model inputs, so they were conservatively estimated using the results of past thin film sputtering studies and particle reflection predictions. In addition, accelerator current densities across the grid were rigorously determined using an ion optics code to determine accelerator current distributions and an algorithm to determine beam current densities along a grid using downstream measurements. The improved analysis was applied to the NSTAR test results for evaluation. The improved analysis demonstrated that the impact of back-sputtered carbon on pit and groove wear rate for the NSTAR LDT2 was negligible throughout most of eroded grid radius. The improved analysis also predicted the accelerator current density for transition from net erosion to net deposition considerably more accurately than the original analysis. The improved analysis was used to estimate the impact of back-sputtered carbon on the accelerator grid pit and groove wear rate of the NEXT Long Duration Test (LDT1). Unlike the NSTAR analysis, the NEXT analysis was more challenging because the thruster was operated for extended durations at various operating conditions and was unavailable for measurements because the test is ongoing. As a result, the NEXT LDT1 estimates presented herein are considered preliminary until the results of future post-test analyses are incorporated. The worst-case impact of carbon

  8. The Impact of Back-Sputtered Carbon on the Accelerator Grid Wear Rates of the NEXT and NSTAR Ion Thrusters

    NASA Technical Reports Server (NTRS)

    Soulas, George C.

    2013-01-01

    A study was conducted to quantify the impact of back-sputtered carbon on the downstream accelerator grid erosion rates of the NEXT (NASA's Evolutionary Xenon Thruster) Long Duration Test (LDT1). A similar analysis that was conducted for the NSTAR (NASA's Solar Electric Propulsion Technology Applications Readiness Program) Life Demonstration Test (LDT2) was used as a foundation for the analysis developed herein. A new carbon surface coverage model was developed that accounted for multiple carbon adlayers before complete surface coverage is achieved. The resulting model requires knowledge of more model inputs, so they were conservatively estimated using the results of past thin film sputtering studies and particle reflection predictions. In addition, accelerator current densities across the grid were rigorously determined using an ion optics code to determine accelerator current distributions and an algorithm to determine beam current densities along a grid using downstream measurements. The improved analysis was applied to the NSTAR test results for evaluation. The improved analysis demonstrated that the impact of back-sputtered carbon on pit and groove wear rate for the NSTAR LDT2 was negligible throughout most of eroded grid radius. The improved analysis also predicted the accelerator current density for transition from net erosion to net deposition considerably more accurately than the original analysis. The improved analysis was used to estimate the impact of back-sputtered carbon on the accelerator grid pit and groove wear rate of the NEXT Long Duration Test (LDT1). Unlike the NSTAR analysis, the NEXT analysis was more challenging because the thruster was operated for extended durations at various operating conditions and was unavailable for measurements because the test is ongoing. As a result, the NEXT LDT1 estimates presented herein are considered preliminary until the results of future posttest analyses are incorporated. The worst-case impact of carbon back

  9. Tumor growth accelerated by chemotherapy-induced senescent cells is suppressed by treatment with IL-12 producing cellular vaccines

    PubMed Central

    Simova, Jana; Sapega, Olena; Imrichova, Terezie; Stepanek, Ivan; Kyjacova, Lenka; Mikyskova, Romana; Indrova, Marie; Bieblova, Jana; Bubenik, Jan; Bartek, Jiri; Hodny, Zdenek; Reinis, Milan

    2016-01-01

    Standard-of-care chemo- or radio-therapy can induce, besides tumor cell death, also tumor cell senescence. While senescence is considered to be a principal barrier against tumorigenesis, senescent cells can survive in the organism for protracted periods of time and they can promote tumor development. Based on this emerging concept, we hypothesized that elimination of such potentially cancer-promoting senescent cells could offer a therapeutic benefit. To assess this possibility, here we first show that tumor growth of proliferating mouse TC-1 HPV-16-associated cancer cells in syngeneic mice becomes accelerated by co-administration of TC-1 or TRAMP-C2 prostate cancer cells made senescent by pre-treatment with the anti-cancer drug docetaxel, or lethally irradiated. Phenotypic analyses of tumor-explanted cells indicated that the observed acceleration of tumor growth was attributable to a protumorigenic environment created by the co-injected senescent and proliferating cancer cells rather than to escape of the docetaxel-treated cells from senescence. Notably, accelerated tumor growth was effectively inhibited by cell immunotherapy using irradiated TC-1 cells engineered to produce interleukin IL-12. Collectively, our data document that immunotherapy, such as the IL-12 treatment, can provide an effective strategy for elimination of the detrimental effects caused by bystander senescent tumor cells in vivo. PMID:27448982

  10. Silicide layer growth rates in Mo/Si multilayers

    SciTech Connect

    Rosen, R.S.; Stearns, D.G. ); Viliardos, M.A.; Kassner, M.E. ); Vernon, S.P. ); Cheng, Y. )

    1993-12-01

    The thermal stability of sputter-deposited Mo/Si multilayers was investigated by annealing studies at relatively low temperatures ([similar to]250--350 [degree]C) for various times (0.5--3000 h). Two distinct stages of thermally activated Mo/Si interlayer growth were found: a primary surge, followed by a (slower) secondary steady-state growth in which the interdiffusion coefficient is constant. The interdiffusion coefficients for the interlayer formed by deposition of Mo-on-Si are higher than those of the interlayer formed by deposition of Si-on-Mo. Assuming that the activation energy is constant, an extrapolation of our results to ambient temperature finds that interlayer growth is negligible, suggesting long-term thermal stability in soft-x-ray projection lithography applications.

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

    PubMed

    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 (< 60 years of age) within each species are consistently growing faster than the older 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).

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

    NASA Astrophysics Data System (ADS)

    Hansen, James; Kharecha, Pushker; Sato, Makiko

    2013-03-01

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

  13. Catch-up growth in Japanese quail (Coturnix Japonica): relationships with food intake, metabolic rate and sex.

    PubMed

    Chin, Eunice H; Storm-Suke, Andrea L; Kelly, Ryan J; Burness, Gary

    2013-08-01

    The effects of early environmental conditions can profoundly affect individual development and adult phenotype. In birds, limiting resources can affect growth as nestlings, but also fitness and survival as adults. Following periods of food restriction, individuals may accelerate development, undergoing a period of rapid "catch-up" growth, in an attempt to reach the appropriate size at adulthood. Previous studies of altricial birds have shown that catch-up growth can have negative consequences in adulthood, although this has not been explored in species with different developmental strategies. Here, we investigated the effects of resource limitation and the subsequent period of catch-up growth, on the morphological and metabolic phenotype of adult Japanese quail (Coturnix japonica), a species with a precocial developmental strategy. Because males and females differ in adult body size, we also test whether food restriction had sex-specific effects. Birds that underwent food restriction early in development had muscles of similar size and functional maturity, but lower adult body mass than controls. There was no evidence of sex-specific sensitivity of food restriction on adult body mass; however, there was evidence for body size. Females fed ad lib were larger than males fed ad lib, while females subjected to food restriction were of similar size to males. Adults that had previously experienced food restriction did not have an elevated metabolic rate, suggesting that in contrast to altricial nestlings, there was no metabolic carry-over effect of catch-up growth into adulthood. While Japanese quail can undergo accelerated growth after re-feeding, timing of food restriction may be important to adult size, particularly in females. However, greater developmental flexibility compared to altricial birds may contribute to the lack of metabolic carryover effects at adulthood.

  14. Generalised Central Limit Theorems for Growth Rate Distribution of Complex Systems

    NASA Astrophysics Data System (ADS)

    Takayasu, Misako; Watanabe, Hayafumi; Takayasu, Hideki

    2014-04-01

    We introduce a solvable model of randomly growing systems consisting of many independent subunits. Scaling relations and growth rate distributions in the limit of infinite subunits are analysed theoretically. Various types of scaling properties and distributions reported for growth rates of complex systems in a variety of fields can be derived from this basic physical model. Statistical data of growth rates for about 1 million business firms are analysed as a real-world example of randomly growing systems. Not only are the scaling relations consistent with the theoretical solution, but the entire functional form of the growth rate distribution is fitted with a theoretical distribution that has a power-law tail.

  15. Effect of puberty on rates of bone growth and mineralisation: with observations in male delayed puberty.

    PubMed Central

    Krabbe, S; Christiansen, C; Rødbro, P; Transbøl, I

    1979-01-01

    The bone mineral content (BMC) and body height were measured in 301 normal children and adolescents aged 7--20 years, and in 8 boys with constitutional delayed puberty aged 14--17 years. Serum testosterone was measured in the last group as well as in a subpopulation of the normal children and adolescents. The growth spurt, which coincided with a steep increase of serum testosterone in boys, indicated a great change in skeletal growth and mineralisation in both sexes. After the growth spurt, linear growth slowed down considerably while bone mineralisation rose steeply. When low levels of serum testosterone were maintained, as in delayed puberty, these combined changes of skeletal growth and mineralisation did not occur. It is suggested that gonadal hormones are the true initiators of the short-lived growth spurt as well as of prolonged acceleration of bone mineralisation. PMID:533299

  16. Stimulant-Related Reductions of Growth Rates in the PATS

    ERIC Educational Resources Information Center

    Swanson, James; Greenhill, Laurence; Wigal, Tim; Kollins, Scott; Stehli, Annamarie; Davies, Mark; Chuang, Shirley; Vitiello, Benedetto; Skrobala, Anne; Posner, Kelly; Abikoff, Howard; Oatis, Melvin; McCracken, James; McGough, James; Riddle, Mark; Ghuman, Jaswinder; Cunningham, Charles; Wigal, Sharon

    2006-01-01

    Objective: To investigate growth of children with attention-deficit/hyperactivity disorder (ADHD) in the Preschool ADHD Treatment Study (PATS) before and after initiation of treatment with methylphenidate at titrated doses (average, 14.2 mg/day) administered three times daily, 7 days/week for approximately equal to 1 year. Method: The heights and…

  17. Growth of Knowledge of Rate in Four Precalculus Students.

    ERIC Educational Resources Information Center

    Hauger, Garnet Smith

    Several studies have shown the difficulties students encounter in making sense of situations involving rate of change. This study concerns how students discover errors and refine their knowledge when working with rate of change. The part of the study reported here concerns the responses of four precalculus students to a task which asked them to…

  18. Low-concentration polymers inhibit and accelerate crystal growth in organic glasses in correlation with segmental mobility.

    PubMed

    Powell, C Travis; Cai, Ting; Hasebe, Mariko; Gunn, Erica M; Gao, Ping; Zhang, Geoff; Gong, Yuchuan; Yu, Lian

    2013-09-05

    Crystal growth in organic glasses has been studied in the presence of low-concentration polymers. Doping the organic glass nifedipine (NIF) with 1 wt % polymer has no measurable effect on the glass transition temperature Tg of host molecules, but substantially alters the rate of crystal growth, from a 10-fold reduction to a 30% increase at 12 °C below the host Tg. Among the polymers tested, all but polyethylene oxide (PEO) inhibit growth. The inhibitory effects greatly diminish in the liquid state (at Tg + 38 °C), but PEO persists to speed crystal growth. The crystal growth rate varies exponentially with polymer concentration, in analogy with the polymer effect on solvent mobility, though the effect on crystal growth can be much stronger. The ability to inhibit crystal growth is not well ordered by the strength of host-polymer hydrogen bonds, but correlates remarkably well with the neat polymer's Tg, suggesting that the mobility of polymer chains is an important factor in inhibiting crystal growth in organic glasses. The polymer dopants also affect crystal growth at the free surface of NIF glasses, but the effect is attenuated according to the power law us ∝ ub(0.35), where us and ub are the surface and bulk growth rates.

  19. The Effect of Load-Line Displacement Rate on the SCC Growth Rate of Nickel Alloys and Mechanistic Implications

    SciTech Connect

    D Morton

    2005-10-19

    A key set of SCC growth experiments was designed to test the hypothesis that deformation/creep is the rate controlling step in LPSCC. These tests were performed on Alloy X-750 AH compact tension specimens at a various constant displacement rates. The deformation/creep rate within the crack tip zone is proportional to the test displacement rate. If crack growth rates were observed to increase with the load-line displacement rate, then this would indicate that deformation/creep is a critical SCC mechanism process. However, results obtained from the load-line displacement tests did not find X-750 AH SCC growth rate to be dependent on the position rate and therefore do not support the assumption that deformation/creep is the rate controlling process in LPSCC. The similarities between the SCC response of X-750, Alloy 600 and EN82H suggests that it is likely that the same SCC process is occurring for all these alloys (i.e., the same rate controlling step) and that deformation based models are also inappropriate for Alloy 600 and EN82H. The strong temperature and coolant hydrogen dependencies exhibited by these alloys make it more likely that nickel alloy LPSCC is controlled by an environmental or corrosion driven process.

  20. Accelerating Rates of Discontinuous Permafrost Thaw Associated with Ground Surface Morphology and Changing Vegetation Structures Determined from Multi-Temporal LIDAR Data

    NASA Astrophysics Data System (ADS)

    Chasmer, L.; Hopkinson, C.

    2015-12-01

    Rates of permafrost thaw within the discontinuous permafrost zone are expected to accelerate with permafrost fragmentation. However quantification of drivers of permafrost change remain elusive due to the non-linearity of feedbacks in space and time. Given the extent of permafrost in Canada, there is significant interest in the mechanisms associated with land cover change as climate change and disturbance intensifies.We quantify the variability of rates of thaw associated with structural characteristics of the land surface within a discontinuous permafrost watershed in the NWT, Canada. Results are compared to an isolated permafrost watershed in Alberta, which may exemplify the northern discontinuous landscape in ~350 years. Three airborne Light Detection And Ranging (LiDAR) datasets have been collected in 2008, 2011 and 2015, coincident with digital photogrammetry (2008), thermal infrared (2011) and bathymetry (2015) within both watersheds. Rates of change of land elevation associated with permafrost thaw within plateaus and peatlands are quantified using non-linear spatial regression, and compared with topographic and vegetation derivatives. Results indicate that increasing fragmentation of discontinuous permafrost plateaus results in exponential thaw. Rates of thaw become linear with decreasing complexity. Accelerating thaw is related to substantial Picea mariana mortality (up to 45%), increased gap fraction within 1-2 m of plateau edges, and shrub succession (average growth ~0.2 m yr—1) at the 0-2m boundary within the 7-year period. Thaw rate in parts is also complicated by understory succession within the area of local convexity between the plateau and slope edge and linear thaw pathways. Greatest rates of thaw and vegetation mortality (~30-50%) are found on plateaus with populous tremuloides. In the central boreal watershed, vegetation succession at peatland margins is associated with increased drying and changes to runoff trends over the last 40 years

  1. Accelerated rate of molecular evolution for vittarioid ferns is strong and not driven by selection.

    PubMed

    Rothfels, Carl J; Schuettpelz, Eric

    2014-01-01

    Molecular evolutionary rate heterogeneity-the violation of a molecular clock-is a prominent feature of many phylogenetic data sets. It has particular importance to systematists not only because of its biological implications, but also for its practical effects on our ability to infer and date evolutionary events. Here we show, using both maximum likelihood and Bayesian approaches, that a remarkably strong increase in substitution rate in the vittarioid ferns is consistent across the nuclear and plastid genomes. Contrary to some expectations, this rate increase is not due to selective forces acting at the protein level on our focal loci. The vittarioids bear no signature of the change in the relative strengths of selection and drift that one would expect if the rate increase was caused by altered post-mutation fixation rates. Instead, the substitution rate increase appears to stem from an elevated supply of mutations, perhaps limited to the vittarioid ancestral branch. This generalized rate increase is accompanied by extensive fine-scale heterogeneity in rates across loci, genomes, and taxa. Our analyses demonstrate the effectiveness and flexibility of trait-free investigations of rate heterogeneity within a model-selection framework, emphasize the importance of explicit tests for signatures of selection prior to invoking selection-related or demography-based explanations for patterns of rate variation, and illustrate some unexpected nuances in the behavior of relaxed clock methods for modeling rate heterogeneity, with implications for our ability to confidently date divergence events. In addition, our data provide strong support for the monophyly of Adiantum, and for the position of Calciphilopteris in the cheilanthoid ferns, two relationships for which convincing support was previously lacking.

  2. Phenomenological approach to precise creep life prediction by means of quantitative evaluation of strain rate acceleration in secondary creep

    NASA Astrophysics Data System (ADS)

    Sato, Hiroyuki; Miyano, Takaya

    2010-07-01

    A method of creep life prediction by means of Strain-Acceleration-Parameter (SAP), α, is presented. The authors show that the shape of creep curve can be characterized by SAP that reflects magnitude of strain-rate change in secondary creep. The SAP-values, α are evaluated on magnesium-aluminium solution hardened alloys. Reconstruction of creep curves by combinations of SAP and minimum-creep rates are successfully performed, and the curves reasonably agree with experiments. The advantage of the proposed method is that the required parameters evaluated from individual creep curves are directly connected with the minimum creep rate. The predicted times-to-failure agree well with that obtained by experiments, and possibility of precise life time prediction by SAP is pronounced.

  3. Cortical porosity exhibits accelerated rate of change in peri- compared with post-menopausal women.

    PubMed

    Burt, L A; Bhatla, J L; Hanley, D A; Boyd, S K

    2017-01-10

    The rate of change in bone density was not different between peri- and post-menopausal women. Differences in rate of change were observed in bone microarchitecture, specifically cortical porosity (Ct.Po), where peri-menopausal women increased +9% per year compared with the +6% per year for post-menopausal women.

  4. Growth rates of new parametric instabilities occurring in a plasma with streaming He(2+)

    NASA Technical Reports Server (NTRS)

    Jayanti, V.; Hollweg, Joseph V.

    1994-01-01

    We consider parametic instabilities of a circularly polarized pump Alfven wave, which propagates parallel to the ambient magnetic field; the daughter waves are also parallel-propagating. We follow Hollweg et al. (1993) and consider several new instabilites that owe their existence to the presence of streaming alpha particles. One of the new instabilites is similar to the famililar decay instability, but the daughter waves are a forward going alpha sound wave and a backward going Alfven wave. The growth rate of this instability is usually small if the alpha abundance is small. The other three new instabilities occur at high frequencies and small wavelengths. We find that the new instability which involves the proton cyclotron wave and alpha sound (i.e., the +f, - alpha) instability, which involves both the proton and alpha cycltron resonances, but if the pump wave must have low frequency and large amplitude. These instabilities may be a means of heating and accelerating alpha particles in the solar wind, but this claim is unproven until a fully kinetic study is carried out.

  5. SU-E-T-495: Neutron Induced Electronics Failure Rate Analysis for a Single Room Proton Accelerator

    SciTech Connect

    Knutson, N; DeWees, T; Klein, E

    2014-06-01

    Purpose: To determine the failure rate as a function of neutron dose of the range modulator's servo motor controller system (SMCS) while shielded with Borated Polyethylene (BPE) and unshielded in a single room proton accelerator. Methods: Two experimental setups were constructed using two servo motor controllers and two motors. Each SMCS was then placed 30 cm from the end of the plugged proton accelerator applicator. The motor was then turned on and observed from outside of the vault while being irradiated to known neutron doses determined from bubble detector measurements. Anytime the motor deviated from the programmed motion a failure was recorded along with the delivered dose. The experiment was repeated using 9 cm of BPE shielding surrounding the SMCS. Results: Ten SMCS failures were recorded in each experiment. The dose per monitor unit for the unshielded SMCS was 0.0211 mSv/MU and 0.0144 mSv/MU for the shielded SMCS. The mean dose to produce a failure for the unshielded SMCS was 63.5 ± 58.3 mSv versus 17.0 ±12.2 mSv for the shielded. The mean number of MUs between failures were 2297 ± 1891 MU for the unshielded SMCS and 2122 ± 1523 MU for the shielded. A Wilcoxon Signed Ranked test showed the dose between failures were significantly different (P value = 0.044) while the number of MUs between failures were not (P value = 1.000). Statistical analysis determined a SMCS neutron dose of 5.3 mSv produces a 5% chance of failure. Depending on the workload and location of the SMCS, this failure rate could impede clinical workflow. Conclusion: BPE shielding was shown to not reduce the average failure of the SMCS and relocation of the system outside of the accelerator vault was required to lower the failure rate enough to avoid impeding clinical work flow.

  6. Sorafenib suppresses growth and survival of hepatoma cells by accelerating degradation of enhancer of zeste homolog 2.

    PubMed

    Wang, Shanshan; Zhu, Yu; He, Hongyong; Liu, Jing; Xu, Le; Zhang, Heng; Liu, Haiou; Liu, Weisi; Liu, Yidong; Pan, Deng; Chen, Lin; Wu, Qian; Xu, Jiejie; Gu, Jianxin

    2013-06-01

    Enhancer of zeste homolog 2 (EZH2) is a mammalian histone methyltransferase that contributes to the epigenetic silencing of target genes that regulate cancer cell growth and survival. It is overexpressed in hepatocellular carcinoma (HCC) with a clinical significance that remains obscure. Sorafenib, a multikinase inhibitor, has been used as a first-line therapeutic drug and shown clinical efficiency for advanced-stage HCC patients. In the present study, we found that sorafenib lowered the protein level of EZH2 through accelerating proteasome-mediated EZH2 degradation in hepatoma cells. Overexpression of EZH2 reversed sorafenib-induced cell growth arrest, cell cycle arrest, and cell apoptosis dependent on histone methyltransferase activity in hepatoma cells. More importantly, shRNA-mediated EZH2 knockdown or EZH2 inhibition with 3-deazaneplanocin A treatment promoted sorafenib-induced hepatoma cell growth arrest and apoptosis. Sorafenib altered the hepatoma epigenome by reducing EZH2 and H3K27 trimethylation. These results revealed a novel therapeutic mechanism underlying sorafenib treatment in suppressing hepatoma growth and survival by accelerating EZH2 degradation. Genetic deletion or pharmacological ablation of EZH2 made hepatoma cells more sensitive to sorafenib, which helps provide a strong framework for exploring innovative combined therapies for advanced-stage HCC patients.

  7. Electron diffraction using ultrafast electron bunches from a laser-wakefield accelerator at kHz repetition rate

    NASA Astrophysics Data System (ADS)

    He, Z.-H.; Thomas, A. G. R.; Beaurepaire, B.; Nees, J. A.; Hou, B.; Malka, V.; Krushelnick, K.; Faure, J.

    2013-02-01

    We show that electron bunches in the 50-100 keV range can be produced from a laser wakefield accelerator using 10 mJ, 35 fs laser pulses operating at 0.5 kHz. It is shown that using a solenoid magnetic lens, the electron bunch distribution can be shaped. The resulting transverse and longitudinal coherence is suitable for producing diffraction images from a polycrystalline 10 nm aluminum foil. The high repetition rate, the stability of the electron source, and the fact that its uncorrelated bunch duration is below 100 fs make this approach promising for the development of sub-100 fs ultrafast electron diffraction experiments.

  8. Solar effect on the Rayleigh-Taylor instability growth rate as simulated by the NCAR TIEGCM

    NASA Astrophysics Data System (ADS)

    Wu, Qian

    2017-04-01

    The TIEGCM (Thermosphere Ionosphere Electrodynamics General Circulation Model) is used to investigate the solar effect on the equatorial ionospheric Rayleigh-Taylor (R-T) instability growth rate, which is responsible for the occurrence of the plasma bubbles. The R-T growth rate is calculated for the solar maximum year 2003 and minimum 2009. The growth rate is strongly dependent on the solar activity. During solar maximum, the pre-reversal enhancement is much stronger leading to higher R-T growth rate. The R-T growth rates from the TIEGCM follow the same solar dependence as the observed occurrence of equatorial plasma bubbles by DMSP satellites. The R-T growth rate also enhances when the day/night terminator is parallel to the magnetic field line near the equator. The R-T growth rate does not correlate well with the solar F10.7 index on a short time scale ( 10 days) because the field-line integrated electron content gradient cancels out the positive correlation between the vertical ion drift with the F10.7 index. The TIEGCM result shows the importance of the electron content gradient to the R-T growth rate and the plasma bubble occurrence. The bubble occurrence rates were estimated based on the vertical ion drift simulation results.

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

    PubMed

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

    2009-05-01

    Recent palaeoatmospheric models suggest large-scale fluctuations in ambient oxygen level over the past 550 million years. To better understand how global hypoxia and hyperoxia might have affected the growth and physiology of contemporary vertebrates, we incubated eggs and raised hatchlings of the American alligator. Crocodilians are one of few vertebrate taxa that survived these global changes with distinctly conservative morphology. We maintained animals at 30 degrees C under chronic hypoxia (12% O(2)), normoxia (21% O(2)) or hyperoxia (30% O(2)). At hatching, hypoxic animals were significantly smaller than their normoxic and hyperoxic siblings. Over the course of 3 months, post-hatching growth was fastest under hyperoxia and slowest under hypoxia. Hypoxia, but not hyperoxia, caused distinct scaling of major visceral organs-reduction of liver mass, enlargement of the heart and accelerated growth of lungs. When absorptive and post-absorptive metabolic rates were measured in juvenile alligators, the increase in oxygen consumption rate due to digestion/absorption of food was greatest in hyperoxic alligators and smallest in hypoxic ones. Hyperoxic alligators exhibited the lowest breathing rate and highest oxygen consumption per breath. We suggest that, despite compensatory cardiopulmonary remodelling, growth of hypoxic alligators is constrained by low atmospheric oxygen supply, which may limit their food utilisation capacity. Conversely, the combination of elevated metabolism and low cost of breathing in hyperoxic alligators allows for a greater proportion of metabolised energy to be available for growth. This suggests that growth and metabolic patterns of extinct vertebrates would have been significantly affected by changes in the atmospheric oxygen level.

  10. Geometric analysis and estimation of the growth rate gradient on gastropod shells.

    PubMed

    Noshita, Koji; Shimizu, Keisuke; Sasaki, Takenori

    2016-01-21

    The morphology of gastropod shells provides a record of the growth rate at the aperture of the shell, and molecular biological studies have shown that the growth rate gradient along the aperture of a gastropod shell can be closely related to gene expression at the aperture. Here, we develop a novel method for deriving microscopic growth rates from the macroscopic shapes of gastropod shells. The growth vector map of a shell provides information on the growth rate gradient as a vector field along the aperture, over the growth history. However, it is difficult to estimate the growth vector map directly from the macroscopic shape of a specimen, because the degree of freedom of the growth vector map is very high. In order to overcome this difficulty, we develop a method of estimating the growth vector map based on a growing tube model, where the latter includes fewer parameters to be estimated. In addition, we calculate an aperture map specifying the magnitude of the growth vector at each location, which can be compared with the expression levels of several genes or proteins that are important in morphogenesis. Finally, we show a concrete example of how macroscopic shell shapes evolve in a morphospace when microscopic growth rate gradient changes.

  11. Spatial and directional variation of growth rates in Arabidopsis root apex: a modelling study.

    PubMed

    Nakielski, Jerzy; Lipowczan, Marcin

    2013-01-01

    Growth and cellular organization of the Arabidopsis root apex are investigated in various aspects, but still little is known about spatial and directional variation of growth rates in very apical part of the apex, especially in 3D. The present paper aims to fill this gap with the aid of a computer modelling based on the growth tensor method. The root apex with a typical shape and cellular pattern is considered. Previously, on the basis of two types of empirical data: the published velocity profile along the root axis and dimensions of cell packets formed in the lateral part of the root cap, the displacement velocity field for the root apex was determined. Here this field is adopted to calculate the linear growth rate in different points and directions. The results are interpreted taking principal growth directions into account. The root apex manifests a significant anisotropy of the linear growth rate. The directional preferences depend on a position within the root apex. In the root proper the rate in the periclinal direction predominates everywhere, while in the root cap the predominating direction varies with distance from the quiescent centre. The rhizodermis is distinguished from the neighbouring tissues (cortex, root cap) by relatively high contribution of the growth rate in the anticlinal direction. The degree of growth anisotropy calculated for planes defined by principal growth directions and exemplary cell walls may be as high as 25. The changes in the growth rate variation are modelled.

  12. Insulin accelerates global and mitochondrial protein synthesis rates in neonatal muscle during sepsis

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In neonatal pigs, sepsis decreases protein synthesis in skeletal muscle by decreasing translation initiation. However, insulin stimulates muscle protein synthesis despite persistent repression of translation initiation signaling. To determine whether the insulin-induced increase in global rates of m...

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

    PubMed Central

    Keren, Leeat; Segal, Eran; Milo, Ron

    2016-01-01

    Most proteins show changes in level across growth conditions. Many of these changes seem to be coordinated with the specific growth rate rather than the growth environment or the protein function. Although cellular growth rates, gene expression levels and gene regulation have been at the center of biological research for decades, there are only a few models giving a base line prediction of the dependence of the proteome fraction occupied by a gene with the specific growth rate. We present a simple model that predicts a widely coordinated increase in the fraction of many proteins out of the proteome, proportionally with the growth rate. The model reveals how passive redistribution of resources, due to active regulation of only a few proteins, can have proteome wide effects that are quantitatively predictable. Our model provides a potential explanation for why and how such a coordinated response of a large fraction of the proteome to the specific growth rate arises under different environmental conditions. The simplicity of our model can also be useful by serving as a baseline null hypothesis in the search for active regulation. We exemplify the usage of the model by analyzing the relationship between growth rate and proteome composition for the model microorganism E.coli as reflected in recent proteomics data sets spanning various growth conditions. We find that the fraction out of the proteome of a large number of proteins, and from different cellular processes, increases proportionally with the growth rate. Notably, ribosomal proteins, which have been previously reported to increase in fraction with growth rate, are only a small part of this group of proteins. We suggest that, although the fractions of many proteins change with the growth rate, such changes may be partially driven by a global effect, not necessarily requiring specific cellular control mechanisms. PMID:27073913

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

    PubMed

    Barenholz, Uri; Keren, Leeat; Segal, Eran; Milo, Ron

    2016-01-01

    Most proteins show changes in level across growth conditions. Many of these changes seem to be coordinated with the specific growth rate rather than the growth environment or the protein function. Although cellular growth rates, gene expression levels and gene regulation have been at the center of biological research for decades, there are only a few models giving a base line prediction of the dependence of the proteome fraction occupied by a gene with the specific growth rate. We present a simple model that predicts a widely coordinated increase in the fraction of many proteins out of the proteome, proportionally with the growth rate. The model reveals how passive redistribution of resources, due to active regulation of only a few proteins, can have proteome wide effects that are quantitatively predictable. Our model provides a potential explanation for why and how such a coordinated response of a large fraction of the proteome to the specific growth rate arises under different environmental conditions. The simplicity of our model can also be useful by serving as a baseline null hypothesis in the search for active regulation. We exemplify the usage of the model by analyzing the relationship between growth rate and proteome composition for the model microorganism E.coli as reflected in recent proteomics data sets spanning various growth conditions. We find that the fraction out of the proteome of a large number of proteins, and from different cellular processes, increases proportionally with the growth rate. Notably, ribosomal proteins, which have been previously reported to increase in fraction with growth rate, are only a small part of this group of proteins. We suggest that, although the fractions of many proteins change with the growth rate, such changes may be partially driven by a global effect, not necessarily requiring specific cellular control mechanisms.

  15. Exploring Latent Class Based on Growth Rates in Number Sense Ability

    ERIC Educational Resources Information Center

    Kim, Dongil; Shin, Jaehyun; Lee, Kijyung

    2013-01-01

    The purpose of this study was to explore latent class based on growth rates in number sense ability by using latent growth class modeling (LGCM). LGCM is one of the noteworthy methods for identifying growth patterns of the progress monitoring within the response to intervention framework in that it enables us to analyze latent sub-groups based not…

  16. How vein sealing boosts fracture widening rates - The buckling-enhanced aperture growth mechanism for syn-tectonic veins

    NASA Astrophysics Data System (ADS)

    Nüchter, Jens-Alexander

    2017-01-01

    The paper introduces the mechanism of buckling-enhanced aperture growth for syn-tectonic veins that formed in simple-shear dominated kinematic frameworks in the middle or lower crust. Apart from the well understood concepts of fracture widening driven by effective tensile stresses, buckling-enhanced fracture aperture growth relates widening to active outward buckling of more viscous incipient cement layers precipitated as hydrothermal minerals for the pore fluid on the walls of juvenile syn-tectonic veins, driven by fracture-parallel compressive creep strain in the host rocks. Thus, the mechanism proposed here follows similar principles as tectonic folding, although important differences exist. Inspired by the structural record of low-aspect ratio veins exposed in HP/LT metamorphic rocks cropping out on south Evia island, Greece, generic numerical models are calculated to study development of buckling instabilities in such incompletely cemented veins and their impact on aperture growth rates. The models indicate (1) that aperture growth rates increase with increasing viscosity contrast between the host rocks and the cement layers, (2) an increase in the thickness of the cement layers cause acceleration of aperture growth, (3) that support of restraining forces at the vein tips offered by the host rocks against buckling of the cement layers cause fully compressive states of stress ahead the fracture tips, and (4) that fracture aperture growth is possible against fully compressive fracture-normal stresses. The buckling-enhanced vein aperture growth mechanism yields important implications for the maintenance and decay of fracture-bound permeability and for the mechanical state of the middle and lower crust in seismically active regions.

  17. Rate accelerations in nuclear 18S rDNA of mycoheterotrophic and parasitic angiosperms.

    PubMed

    Lemaire, Benny; Huysmans, Suzy; Smets, Erik; Merckx, Vincent

    2011-09-01

    Rate variation in genes from all three genomes has been observed frequently in plant lineages with a parasitic and mycoheterotrophic mode of life. While the loss of photosynthetic ability leads to a relaxation of evolutionary constraints in genes involved in the photosynthetic apparatus, it remains to be determined how prevalent increased substitution rates are in nuclear DNA of non-photosynthetic angiosperms. In this study we infer rates of molecular evolution of 18S rDNA of all parasitic and mycoheterotorphic plant families (except Lauraceae and Polygalaceae) using relative rate tests. In several holoparasitic and mycoheterotrophic plant lineages extremely high substitution rates are observed compared to other photosynthetic angiosperms. The position and frequency of these substitutions have been identified to understand the mutation dynamics of 18S rRNA in achlorophyllous plants. Despite the presence of significantly elevated substitution rates, very few mutations occur in major functional and structural regions of the small ribosomal molecule, providing evidence that the efficiency of the translational apparatus in non-photosynthetic plants has not been affected.

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

    PubMed

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

    2013-01-01

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

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

    PubMed Central

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

    2013-01-01

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

  20. Growth rates and life histories in twenty-two small-scale societies.

    PubMed

    Walker, Robert; Gurven, Michael; Hill, Kim; Migliano, Andrea; Chagnon, Napoleon; De Souza, Roberta; Djurovic, Gradimir; Hames, Raymond; Hurtado, A Magdalena; Kaplan, Hillard; Kramer, Karen; Oliver, William J; Valeggia, Claudia; Yamauchi, Taro

    2006-01-01

    This study investigates variation in body growth (cross-sectional height and weight velocity) among a sample of 22 small-scale societies. Considerable variation in growth exists among hunter-gatherers that overlaps heavily with growth trajectories present in groups focusing more on horticulture. Intergroup variation tends to track environmental conditions, with societies under more favorable conditions displaying faster growth and earlier puberty. In addition, faster/earlier development in females is correlated with higher mortality. For example, African "Pygmies," Philippine "Negritos," and the Hiwi of Venezuela are characterized by relatively fast child-juvenile growth for their adult body size (used as a proxy for energetic availability). In these societies, subadult survival is low, and puberty, menarche, and first reproduction are relatively early (given their adult body size), suggesting selective pressure for accelerated development in the face of higher mortality. In sum, the origin and maintenance of different human ontogenies may require explanations invoking both environmental constraints and selective pressures.

  1. Surface composition and barium evaporation rate of ``pedigreed'' impregnated tungsten dispenser cathodes during accelerated life testing

    NASA Astrophysics Data System (ADS)

    Tomich, D. H.; Mescher, J. A.; Grant, J. T.

    1987-03-01

    A study has been made of the surface composition and barium evaporation rate of "pedigreed" impregnated tungsten dispenser cathodes. The effect of air exposure on coated cathodes was examined and was found to have no significant effect on barium evaporation rate although in some cases longer reactivation times were required. No changes in surface topography were apparent following air exposure and reactivation. Life testing was done at 100°C above the typical operating temperature for the cathode, where the typical operating temperature was taken to be 950°C for coated cathodes and 1050°C for uncoated cathodes. The cathodes were examined at different stages of life testing, up to 1200 h. Significant decreases in barium evaporation rates were found after as few as 500 h of life testing. After 1000 h the evaporation rate had decreased more than an order of magnitude. Changes in surface composition were also found. The effects of tungsten particle size, used in manufacture of the billet, on barium evaporation rate were also studied but no correlation was found.

  2. Growth Rate Lags Again in Graduate Schools' International Admissions

    ERIC Educational Resources Information Center

    McCormack, Eugene

    2008-01-01

    The number of foreign students admitted to graduate schools at American colleges and universities grew in 2008 for the fourth straight year, but the rate of increase over the previous year declined for the third consecutive year, according to survey results released by the Council of Graduate Schools. Based on previous years' data, this year's…

  3. Influence of Polymers on the Crystal Growth Rate of Felodipine: Correlating Adsorbed Polymer Surface Coverage to Solution Crystal Growth Inhibition.

    PubMed

    Schram, Caitlin J; Taylor, Lynne S; Beaudoin, Stephen P

    2015-10-20

    The bioavailability of orally administered drugs that exhibit poor aqueous solubility can be enhanced with the use of supersaturating dosage forms. Stabilization of these forms by preventing or inhibiting crystallization in solution is an important area of study. Polymers can be used to stabilize supersaturated systems; however, the properties that impact their effectiveness as crystal growth rate inhibitors are not yet fully understood. In this study, the impact of various polymers on the crystal growth rate of felodipine and the conformation of these polymers adsorbed to crystalline felodipine was investigated in order to gain a mechanistic understanding of crystal growth inhibition. It was determined that polymer hydrophobicity impacted polymer adsorption as well as adsorbed polymer conformation. Polymer conformation impacts its surface coverage, which was shown to directly correlate to the polymer's effectiveness as a growth rate inhibitor. By modeling this correlation, it is possible to predict polymer effectiveness given the surface coverage of the polymer.

  4. Nucleation kinetics and crystal growth with fluctuating rates at the intermediate stage of phase transitions

    NASA Astrophysics Data System (ADS)

    Alexandrov, D. V.; Malygin, A. P.

    2014-01-01

    Crystal growth kinetics accompanied by particle growth with fluctuating rates at the intermediate stage of phase transitions is analyzed theoretically. The integro-differential model of governing equations is solved analytically for size-independent growth rates and arbitrary dependences of the nucleation frequency on supercooling/supersaturation. Two important cases of Weber-Volmer-Frenkel-Zel'dovich and Mier nucleation kinetics are detailed. A Fokker-Plank type equation for the crystal-size density distribution function is solved explicitly.

  5. The effect of density gradient on the growth rate of relativistic Weibel instability

    SciTech Connect

    Mahdavi, M.; Khodadadi Azadboni, F.

    2014-02-15

    In this paper, the effect of density gradient on the Weibel instability growth rate is investigated. The density perturbations in the near corona fuel, where temperature anisotropy, η, is larger than the critical temperature anisotropy, η{sub c}, (η > η{sub c}), enhances the growth rate of Weibel instability due to the sidebands coupled with the electron oscillatory velocity. But for η < η{sub c}, the thermal spread of the energetic electrons reduces the growth rate. Also, the growth rate can be reduced if the relativistic parameter (Lorentz factor) is sufficiently large, γ > 2. The analysis shows that relativistic effects and density gradient tend to stabilize the Weibel instability. The growth rate can be reduced by 88% by reducing η by a factor of 100 and increasing relativistic parameter by a factor of 3.

  6. Amplified Rate Acceleration by Simultaneous Up-Regulation of Multiple Active Sites in an Endo-Functionalized Porous Capsule.

    PubMed

    Kopilevich, Sivil; Müller, Achim; Weinstock, Ira A

    2015-10-14

    Using the hydrolysis of epoxides in water as a model reaction, the effect of multiple active sites on Michaelis-Menten compliant rate accelerations in a porous capsule is demonstrated. The capsule is a water-soluble Ih-symmetry Keplerate-type complex of the form, [{Mo(VI)6O21(H2O)6}12{Mo(V)2O4(L)}30](42-), in which 12 pentagonal "ligands," {(Mo(VI))Mo(VI)5O21(H2O)6}(6-), are coordinated to 30 dimolybdenum sites, {Mo(V)2O4L}(1+) (L = an endohedrally coordinated η(2)-bound carboxylate anion), resulting in 20 Mo9O9 pores. When "up-regulated" by removal of ca. one-third of the blocking ligands, L, an equal number of dimolybdenum sites are activated, and the newly freed-up space allows for encapsulation of nearly twice as many substrate guests, leading to a larger effective molarity (amplification), and an increase in the rate acceleration (k(cat)/k(uncat)) from 16,000 to an enzyme-like value of 182,800.

  7. Lewis Acid Accelerated Aryl Ether Bond Cleavage with Nickel: Orders of Magnitude Rate Enhancement Using AlMe3.

    PubMed

    Kelley, Paul; Edouard, Guy A; Lin, Sibo; Agapie, Theodor

    2016-11-21

    Study of the kinetics of intramolecular aryl ether C-O bond cleavage by Ni was facilitated by access to a family of metal complexes supported by diphosphines with pendant aryl-methyl ethers. The nature of the aryl substituents was found to have little effect on the rate of cleavage. In contrast, soluble Lewis acidic additives accelerate the aryl ether cleavage dramatically. The effect of AlMe3 was studied in detail, and showed an increase in rate by several orders of magnitude. Low temperature NMR spectroscopy studies demonstrate quantitative coordination of ether to Al. From the Lewis acid-bound precursor, the activation parameters for ether cleavage are significantly lower. These findings provide a mechanistic basis for milder catalyst design for the activation of strong bonds.

  8. Accelerating the initial rate of hydrolysis of methyl parathion with laser excitation using monolayer protected 10 nm Au nanoparticles capped with a Cu(bpy) catalyst.

    PubMed

    Trammell, Scott A; Nita, Rafaela; Moore, Martin; Zabetakis, Dan; Chang, Eddie; Knight, D Andrew

    2012-04-28

    Using a low power green laser, we have demonstrated a rate acceleration of ~2-fold for the hydrolysis of methyl parathion by irradiating the plasmon absorption band of Au nanoparticles capped with a Cu(bpy) catalyst.

  9. Effects of Eucommia ulmoides extract on longitudinal bone growth rate in adolescent female rats.

    PubMed

    Kim, Ji Young; Lee, Jeong-Il; Song, MiKyung; Lee, Donghun; Song, Jungbin; Kim, Soo Young; Park, Juyeon; Choi, Ho-Young; Kim, Hocheol

    2015-01-01

    Eucommia ulmoides is one of the popular tonic herbs for the treatment of low back pain and bone fracture and is used in Korean medicine to reinforce muscles and bones. This study was performed to investigate the effects of E. ulmoides extract on longitudinal bone growth rate, growth plate height, and the expressions of bone morphogenetic protein 2 (BMP-2) and insulin-like growth factor 1 (IGF-1) in adolescent female rats. In two groups, we administered a twice-daily dosage of E. ulmoides extract (at 30 and 100 mg/kg, respectively) per os over 4 days, and in a control group, we administered vehicle only under the same conditions. Longitudinal bone growth rate in newly synthesized bone was observed using tetracycline labeling. Chondrocyte proliferation in the growth plate was observed using cresyl violet dye. In addition, we analyzed the expressions of BMP-2 and IGF-1 using immunohistochemistry. Eucommia ulmoides extract significantly increased longitudinal bone growth rate and growth plate height in adolescent female rats. In the immunohistochemical study, E. ulmoides markedly increased BMP-2 and IGF-1 expressions in the proliferative and hypertrophic zones. In conclusion, E. ulmoides increased longitudinal bone growth rate by promoting chondrogenesis in the growth plate and the levels of BMP-2 and IGF-1. Eucommia ulmoides could be helpful for increasing bone growth in children who have growth retardation.

  10. Selective sinoatrial node optical mapping to investigate the mechanism of sinus rate acceleration

    NASA Astrophysics Data System (ADS)

    Lin, Shien-Fong; Shinohara, Tetsuji; Joung, Boyoung; Chen, Peng-Sheng

    2011-03-01

    Studies using isolated sinoatrial node (SAN) cells indicate that rhythmic spontaneous sarcoplasmic reticulum Ca release (Ca clock) plays an important role in SAN automaticity. However, it is difficult to translate these findings into intact SAN because the SAN is embedded in the right atrium (RA). Cross contamination of the optical signals between SAN and RA prevented the definitive testing of Ca clock hypothesis in intact SAN. We use a novel approach to selectively map intact SAN to examine the Ca clock function in intact RA. We simultaneously mapped intracellular Ca (Cai) and membrane potential (Vm) in 7 isolated, Langendorff perfused normal canine RA. Electrical conduction from the SAN to RA was inhibited with high potassium (10 mmol/L) Tyrode's solution, allowing selective optical mapping of Vm and Cai of the SAN. Isoproterenol (ISO, 0.03 μmol/L) decreased cycle length of the sinus beats from 586+/-17 ms at baseline to 366+/-32 ms, and shifted the leading pacemaker site from the middle or inferior SAN to the superior SAN in all RAs. The Cai upstroke preceded the Vm in the leading pacemaker site by up to 18+/-2 ms. ISO-induced changes to SAN were inhibited by ryanodine (3 μmol/L), but not ZD7288 (3 μmol/L), a selective If blocker. We conclude that a high extracellular potassium concentration results in intermittent SAN-RA conduction block, allowing selective optical mapping of the intact SAN. Acceleration of Ca cycling in the superior SAN underlies the mechanism of sinus tachycardia during sympathetic stimulation.

  11. Growth rate and transition to turbulence of a gas curtain

    SciTech Connect

    Vorobieff, P.; Rightley, P.; Benjamin, R.

    1997-09-01

    The authors conduct shock-tube experiments to investigate Richtmyer-Meshkov (RM) instability of a narrow curtain of heavy gas (SF{sub 6}) embedded in lighter gas (air). Initial perturbations of the curtain can be varied, producing different flow patterns in the subsequent evolution of the curtain. Multiple-exposure video flow visualization provides images of the growth of the instability and its transition to turbulence, making it possible to extract quantitative information such as the width of the perturbed curtain. They demonstrate that the width of the curtain with initial perturbation on the downstream side is non-monotonic. As the initial perturbation undergoes phase inversion, the width of the curtain actually decreases before beginning to grow as the RM instability evolves.

  12. Simulation of Rayleigh-Taylor instability growth rate of laser accelerated plant target. Final report

    SciTech Connect

    Bel`kov, S.A.; Bondarenko, S.V.; Vinokurov, O.A.; Kochemasov, G.G.; Mkhitarian, L.S.

    1996-09-01

    This report presents the research results for the time point when the Rayleigh-Taylor instability converts to the nonlinear stage as well as the computational results for the interaction of two modes of Rayleigh-Taylor instability when initial perturbations are concentrated at the ablation front (problem (a)) and on the rear side (problem (b)) of the plane target. As was shown in the report for the first phase, for a target of 3 {mu}m thick the existence time of the nonlinear stage is extremely low and does not allow to track the evolution pattern. In it was shown that the plane target with {Delta}{sub 0}=5 {mu}m is more preferable for this goal. Therefore all the computations presented here relate to the target with the indicated thickness. The laser pulse parameters are remained unchanged J{sub L}=10{sup 15} W/cm{sup 2}, {lambda}=0.35 {mu}m.

  13. Ancient dates or accelerated rates? Morphological clocks and the antiquity of placental mammals.

    PubMed

    Beck, Robin M D; Lee, Michael S Y

    2014-10-22

    Analyses of a comprehensive morphological character matrix of mammals using 'relaxed' clock models (which simultaneously estimate topology, divergence dates and evolutionary rates), either alone or in combination with an 8.5 kb nuclear sequence dataset, retrieve implausibly ancient, Late Jurassic-Early Cretaceous estimates for the initial diversification of Placentalia (crown-group Eutheria). These dates are much older than all recent molecular and palaeontological estimates. They are recovered using two very different clock models, and regardless of whether the tree topology is freely estimated or constrained using scaffolds to match the current consensus placental phylogeny. This raises the possibility that divergence dates have been overestimated in previous analyses that have applied such clock models to morphological and total evidence datasets. Enforcing additional age constraints on selected internal divergences results in only a slight reduction of the age of Placentalia. Constraining Placentalia to less than 93.8 Ma, congruent with recent molecular estimates, does not require major changes in morphological or molecular evolutionary rates. Even constraining Placentalia to less than 66 Ma to match the 'explosive' palaeontological model results in only a 10- to 20-fold increase in maximum evolutionary rate for morphology, and fivefold for molecules. The large discrepancies between clock- and fossil-based estimates for divergence dates might therefore be attributable to relatively small changes in evolutionary rates through time, although other explanations (such as overly simplistic models of morphological evolution) need to be investigated. Conversely, dates inferred using relaxed clock models (especially with discrete morphological data and MrBayes) should be treated cautiously, as relatively minor deviations in rate patterns can generate large effects on estimated divergence dates.

  14. Ancient dates or accelerated rates? Morphological clocks and the antiquity of placental mammals

    PubMed Central

    Beck, Robin M. D.; Lee, Michael S. Y.

    2014-01-01

    Analyses of a comprehensive morphological character matrix of mammals using ‘relaxed’ clock models (which simultaneously estimate topology, divergence dates and evolutionary rates), either alone or in combination with an 8.5 kb nuclear sequence dataset, retrieve implausibly ancient, Late Jurassic–Early Cretaceous estimates for the initial diversification of Placentalia (crown-group Eutheria). These dates are much older than all recent molecular and palaeontological estimates. They are recovered using two very different clock models, and regardless of whether the tree topology is freely estimated or constrained using scaffolds to match the current consensus placental phylogeny. This raises the possibility that divergence dates have been overestimated in previous analyses that have applied such clock models to morphological and total evidence datasets. Enforcing additional age constraints on selected internal divergences results in only a slight reduction of the age of Placentalia. Constraining Placentalia to less than 93.8 Ma, congruent with recent molecular estimates, does not require major changes in morphological or molecular evolutionary rates. Even constraining Placentalia to less than 66 Ma to match the ‘explosive’ palaeontological model results in only a 10- to 20-fold increase in maximum evolutionary rate for morphology, and fivefold for molecules. The large discrepancies between clock- and fossil-based estimates for divergence dates might therefore be attributable to relatively small changes in evolutionary rates through time, although other explanations (such as overly simplistic models of morphological evolution) need to be investigated. Conversely, dates inferred using relaxed clock models (especially with discrete morphological data and MrBayes) should be treated cautiously, as relatively minor deviations in rate patterns can generate large effects on estimated divergence dates. PMID:25165770

  15. Mammoth tooth enamel growth rates inferred from stable isotope analysis and histology

    NASA Astrophysics Data System (ADS)

    Metcalfe, Jessica Z.; Longstaffe, Fred J.

    2012-05-01

    Mammoth (Mammuthus sp.) teeth are relatively abundant in Quaternary deposits from Eurasia and North America, and their isotopic compositions can be used to reconstruct past seasonal patterns in precipitation, diet, and migration. Strategies for collecting and interpreting such data, however, are strongly dependent on growth rates, which can vary among species, individuals, and within teeth. In this study, we use histological and isotopic measurements to determine enamel growth rates for a Columbian mammoth (Mammuthus columbi) tooth in two directions. Using histology, the growth rate through the enamel thickness (ET; perpendicular to the height of the tooth) is estimated at 0.8 to 1.5 mm/yr. Isotopic sampling through the innermost 0.36 mm of the ET recovered less than half a period of variation (i.e., half an inferred year of growth), which is consistent with the histological estimate for ET growth rate. A combination of histological and isotopic measurements suggests that the enamel extension rate (growth in the height of the tooth) is 13-14 mm/yr. Knowledge of enamel growth rates should improve the design and interpretation of future isotopic studies of mammoth teeth. The combination of histological and isotopic measurements may also prove useful in determining growth rates for other extinct taxa.

  16. Rate limits in silicon sheet growth - The connections between vertical and horizontal methods

    NASA Technical Reports Server (NTRS)

    Thomas, Paul D.; Brown, Robert A.

    1987-01-01

    Meniscus-defined techniques for the growth of thin silicon sheets fall into two categories: vertical and horizontal growth. The interactions of the temperature field and the crystal shape are analyzed for both methods using two-dimensional finite-element models which include heat transfer and capillarity. Heat transfer in vertical growth systems is dominated by conduction in the melt and the crystal, with almost flat melt/crystal interfaces that are perpendicular to the direction of growth. The high axial temperature gradients characteristic of vertical growth lead to high thermal stresses. The maximum growth rate is also limited by capillarity which can restrict the conduction of heat from the melt into the crystal. In horizontal growth the melt/crystal interface stretches across the surface of the melt pool many times the crystal thickness, and low growth rates are achievable with careful temperature control. With a moderate axial temperature gradient in the sheet a substantial portion of the latent heat conducts along the sheet and the surface of the melt pool becomes supercooled, leading to dendritic growth. The thermal supercooling is surpressed by lowering the axial gradient in the crystal; this configuration is the most desirable for the growth of high quality crystals. An expression derived from scaling analysis relating the growth rate and the crucible temperature is shown to be reliable for horizontal growth.

  17. Progress on plasma accelerators

    SciTech Connect

    Chen, P.

    1986-05-01

    Several plasma accelerator concepts are reviewed, with emphasis on the Plasma Beat Wave Accelerator (PBWA) and the Plasma Wake Field Accelerator (PWFA). Various accelerator physics issues regarding these schemes are discussed, and numerical examples on laboratory scale experiments are given. The efficiency of plasma accelerators is then revealed with suggestions on improvements. Sources that cause emittance growth are discussed briefly.

  18. Growth rate, organic carbon and nutrient removal rates of Chlorella sorokiniana in autotrophic, heterotrophic and mixotrophic conditions.

    PubMed

    Kim, Sunjin; Park, Jeong-eun; Cho, Yong-Beom; Hwang, Sun-Jin

    2013-09-01

    This study sought to investigate the growth rate and organic carbon and nutrient removal efficiency of Chlorella sorokiniana under autotrophic, heterotrophic and mixotrophic conditions. Growth rates of the microalgae were 0.24 d(-1), 0.53 d(-1) and 0.44 d(-1) in autotrophic, heterotrophic and mixotrophic conditions, respectively. The growth rate of C. sorokiniana was significantly higher for that grown under heterotrophic conditions. The nitrogen removal rates were 13.1 mg-N/L/day, 23.9 mg-N/L/day and 19.4 mg-N/L/day, respectively. The phosphorus removal rates reached to 3.4 mg-P/L/day, 5.6 mg-P/L/day and 5.1 mg-P/L/day, respectively. Heterotrophic conditions were superior in terms of the microalgae growth and removal of nitrogen and phosphorus compared to autotrophic and mixotrophic conditions, suggesting that microalgae cultured under this condition would be most useful for application in wastewater treatment systems.

  19. UVB Exposure Does Not Accelerate Rates of Litter Decomposition in a Semiarid Riparian Ecosystem

    NASA Astrophysics Data System (ADS)

    Uselman, S. M.; Snyder, K. A.; Blank, R. R.; Jones, T. J.

    2010-12-01

    Aboveground litter decomposition is controlled mainly by substrate quality and climate factors across terrestrial ecosystems, but photodegradation from exposure to high-intensity ultraviolet-B (UVB) radiation may also be important in arid and semi-arid environments. We investigated the interactive effects of UVB exposure and litter quality on decomposition in a Tamarix-invaded riparian ecosystem during the establishment of an insect biological control agent in northern Nevada. Feeding by the northern tamarisk beetle (Diorhabda carinulata) on Tamarix spp. trees leads to altered leaf litter quality and increased exposure to solar UVB radiation from canopy opening. In addition, we examined the dynamics of litter decomposition of the invasive exotic Lepidium latifolium, because it is well-situated to invade beetle-infested Tamarix sites. Three leaf litter types (natural Tamarix, beetle-affected Tamarix, and L. latifolium) differing in substrate quality were decomposed in litterbags for one year in the field. Litterbags were subjected to one of three treatments: (1) Ambient UVB or (2) Reduced UVB (where UVB was manipulated by using clear plastic films that transmit or block UVB), and (3) No Cover (a control used to test for the effect of using the plastic films, i.e. a cover effect). Results showed a large cover effect on rates of decomposition and nutrient release, and our findings suggested that frequent cycles of freeze-thaw, and possibly rainfall intensity, influenced decomposition at this site. Contrary to our expectations, greater UVB exposure did not result in faster rates of decomposition. Greater UVB exposure resulted in decreased rates of decomposition and P release for the lower quality litter and no change in rates of decomposition and nutrient release for the two higher quality litter types, possibly due to a negative effect of UVB on soil microbes. Among litter types, rates of decomposition and net release of N and P followed this ranking: L. latifolium

  20. Growth rates are related to production efficiencies in juveniles of the sea urchin Lytechinus variegatus.

    PubMed

    Heflin, L E; Gibbs, V K; Jones, W T; Makowsky, R; Lawrence, A L; Watts, S A

    2013-09-01

    Growth rates of newly-metamorphosed urchins from a single spawning event (three males and three females) were highly variable, despite being held en masse under identical environmental and nutritional conditions. As individuals reached ~5 mm diameter (0.07-0.10 g wet weight), they were placed in growth trials (23 dietary treatments containing various nutrient profiles). Elapsed time from the first individual entering the growth trials to the last individual entering was 121 days (N = 170 individuals). During the five-week growth trials, urchins were held individually and proffered a limiting ration to evaluate growth rate and production efficiency. Growth rates among individuals within each dietary treatment remained highly variable. Across all dietary treatments, individuals with an initially high growth rate (entering the study first) continued to grow at a faster rate than those with an initially low growth rate (entering the study at a later date), regardless of feed intake. Wet weight gain (ranging from 0.13 -3.19 g, P < 0.0001, R(2) = 0.5801) and dry matter production efficiency (ranging from 25.2-180.5%, P = 0.0003, R(2) = 0.6162) were negatively correlated with stocking date, regardless of dietary treatment. Although canalization of growth rate during en masse early post-metamorphic growth is possible, we hypothesize that intrinsic differences in growth rates are, in part, the result of differences (possibly genetic) in production efficiencies of individual Lytechinus variegatus. That is, some sea urchins are more efficient in converting feed to biomass. We further hypothesize that this variation may have evolved as an adaptive response to selective pressure related to food availability.

  1. Growth rates are related to production efficiencies in juveniles of the sea urchin Lytechinus variegatus

    PubMed Central

    Heflin, L.E.; Gibbs, V.K.; Jones, W.T.; Makowsky, R.; Lawrence, A.L.; Watts, S.A.

    2014-01-01

    Growth rates of newly-metamorphosed urchins from a single spawning event (three males and three females) were highly variable, despite being held en masse under identical environmental and nutritional conditions. As individuals reached ~5 mm diameter (0.07–0.10 g wet weight), they were placed in growth trials (23 dietary treatments containing various nutrient profiles). Elapsed time from the first individual entering the growth trials to the last individual entering was 121 days (N = 170 individuals). During the five-week growth trials, urchins were held individually and proffered a limiting ration to evaluate growth rate and production efficiency. Growth rates among individuals within each dietary treatment remained highly variable. Across all dietary treatments, individuals with an initially high growth rate (entering the study first) continued to grow at a faster rate than those with an initially low growth rate (entering the study at a later date), regardless of feed intake. Wet weight gain (ranging from 0.13 −3.19 g, P < 0.0001, R2 = 0.5801) and dry matter production efficiency (ranging from 25.2–180.5%, P = 0.0003, R2 = 0.6162) were negatively correlated with stocking date, regardless of dietary treatment. Although canalization of growth rate during en masse early post-metamorphic growth is possible, we hypothesize that intrinsic differences in growth rates are, in part, the result of differences (possibly genetic) in production efficiencies of individual Lytechinus variegatus. That is, some sea urchins are more efficient in converting feed to biomass. We further hypothesize that this variation may have evolved as an adaptive response to selective pressure related to food availability. PMID:25435593

  2. Isolation of Hox Cluster Genes from Insects Reveals an Accelerated Sequence Evolution Rate

    PubMed Central

    Hadrys, Heike; Simon, Sabrina; Kaune, Barbara; Schmitt, Oliver; Schöner, Anja; Jakob, Wolfgang; Schierwater, Bernd

    2012-01-01

    Among gene families it is the Hox genes and among metazoan animals it is the insects (Hexapoda) that have attracted particular attention for studying the evolution of development. Surprisingly though, no Hox genes have been isolated from 26 out of 35 insect orders yet, and the existing sequences derive mainly from only two orders (61% from Hymenoptera and 22% from Diptera). We have designed insect specific primers and isolated 37 new partial homeobox sequences of Hox cluster genes (lab, pb, Hox3, ftz, Antp, Scr, abd-a, Abd-B, Dfd, and Ubx) from six insect orders, which are crucial to insect phylogenetics. These new gene sequences provide a first step towards comparative Hox gene studies in insects. Furthermore, comparative distance analyses of homeobox sequences reveal a correlation between gene divergence rate and species radiation success with insects showing the highest rate of homeobox sequence evolution. PMID:22685537

  3. Particle Rate and Host Accelerator Beam Loss on the MICE Experiment

    SciTech Connect

    Dobbs, Adam James

    2011-10-01

    A study is presented of particle rates in the MICE Muon Beamline and their relationship to beam loss produced in ISIS. A brief overview of neutrino physics is presented, together with a discussion on the Neutrino Factory as a motivation for MICE. An overview of MICE itself is then presented, highlighting the need for a systematic understanding of the relationship between the MICE target parameters, ISIS beam loss, and MICE particle rate. The variation of beam loss with target depth is examined and observed to be non-linear. The variation of beam loss with respect to the target dip time in the ISIS cycle is examined and observed to be approximately linear for dip times between 11.1 ms and 12.6 ms after ISIS injection, before tailing at earlier dip times. The variation of beam loss with particle rate is also observed to follow an approximately linear relationship from 0.05 V.ms to 4.7 V.ms beam loss, with a further strong indication that this continues up to 7.1 V.ms. Particle identification using time-of-flight data is used to give an insight into the relative abundances of each particle species present in the MICE beam. Estimates of muon rate are then produced as a function of beam loss. At a level of 2 V.ms beam loss ~10.9 muons per spill for a 3.2 ms spill with negative π → μ optics, and ~31.1 muons per 1 ms spill with positive π → μ optics are observed. Simulations using the ORBIT particle tracking code of the beam loss distributions around the ISIS ring, caused by the MICE target, are also presented and the implications for MICE running discussed.

  4. Exposure of human megakaryocytes to high shear rates accelerates platelet production.

    PubMed

    Dunois-Lardé, Claire; Capron, Claude; Fichelson, Serge; Bauer, Thomas; Cramer-Bordé, Elisabeth; Baruch, Dominique

    2009-08-27

    Platelets originate from megakaryocytes (MKs) by cytoplasmic elongation into proplatelets. Direct platelet release is not seen in bone marrow hematopoietic islands. It was suggested that proplatelet fragmentation into platelets can occur intravascularly, yet evidence of its dependence on hydrodynamic forces is missing. Therefore, we investigated whether platelet production from MKs could be up-regulated by circulatory forces. Human mature MKs were perfused at a high shear rate on von Willebrand factor. Cells were observed in real time by videomicroscopy, and by confocal and electron microscopy after fixation. Dramatic cellular modifications followed exposure to high shear rates: 30% to 45% adherent MKs were converted into proplatelets and released platelets within 20 minutes, contrary to static conditions that required several hours, often without platelet release. Tubulin was present in elongated proplatelets and platelets, thus ruling out membrane tethers. By using inhibitors, we demonstrated the fundamental roles of microtubule assembly and MK receptor GPIb. Secretory granules were present along the proplatelet shafts and in shed platelets, as shown by P-selectin labeling. Platelets generated in vitro were functional since they responded to thrombin by P-selectin expression and cytoskeletal reorganization. In conclusion, MK exposure to high shear rates promotes platelet production via GPIb, depending on microtubule assembly and elongation.

  5. Hillslope-channel coupling in a steep Hawaiian catchment accelerates erosion rates over 100-fold

    NASA Astrophysics Data System (ADS)

    Stock, J. D.; Hanshaw, M. N.; Rosener, M.; Schmidt, K. M.; Brooks, B. A.; Tribble, G.; Jacobi, J.

    2009-12-01

    In tropical watersheds, hillslope changes are producing increasing amounts of fine sediment that can be quickly carried to reefs by channels. Suspended sediment concentrations off the reefs of Molokai, Hawaii, chronically exceed a toxic level of 10 mg/L, threatening reef ecosystems. We hypothesize that historic conversion of watersheds from soil creep to overland flow erosion increased both magnitude and frequency of sediment flooding adjacent reefs. We combined surficial and ecological mapping, hillslope and stream gages, and novel sensors to locate, quantify and model the generation of fine sediments polluting the Molokai reef. Ecological and geomorphic mapping from LiDAR and multi-spectral imagery located a subset of overland flow areas with vegetation cover below a threshold value preventing erosion. Here, feral goat grazing exposed cohesive volcanic soils whose low matrix hydraulic conductivities (1-20 mm/hour) promote Horton overland flow erosion. We instrumented steep, barren hillslopes with soil moisture sensors, overland flow meters, Parshall flumes, ISCO sediment samplers, and a rain gage and conducted repeat Tripod LiDAR and infiltration tests. To characterize soil resistance here and elsewhere to overland flow erosion, we deployed a Cohesive Strength Meter (CSM) to simulate the stresses of flowing water. At the 13.5 km 2 watershed mouth we used a USGS stream gage and ISCO sediment sampler to estimate total load. Over 2 years, storms triggered overland flow during rainfall intensities above 10-15 mm/hr. Overland flow meters indicate such flows can be up to 3 cm deep, with a tendency to deepen downslope. CSM tests indicate that these depths are insufficient to erode soils where vegetation is dense, but far above threshold values of 2-3 mm depth for bare soil erosion. Sediment ratings curves for both hillslope and downstream catchment gages show strong clock-wise hysteresis during the first intense storms in the Fall, becoming linear later in the rainy

  6. The effects of temperature and NaCl concentration on tetragonal lysozyme face growth rates

    NASA Technical Reports Server (NTRS)

    Forsythe, Elizabeth; Pusey, Marc Lee

    1994-01-01

    Measurements were made of the (110) and (101) face growth rates of the tetragonal form of hen egg white lysozyme at 0.1M sodium acetate buffer, pH 4.0, from 4 to 22 C and with 3.0%, 5.0%, and 7.0% NaCl used as the precipitating salt. The data were collected at supersaturation ratios ranging from approximately 4 to approximately 63. Both decreasing temperature and increasing salt concentrations shifted plots of the growth rate versus C/C(sat) to the right, i.e. higher supersaturations were required for comparable growth rates. The observed trends in the growth data are counter to those expected from the solubility data. If tetragonal lysozyme crystal growth is by addition of ordered aggregates from the solution, then the observed growth data could be explained as a result of the effects of lowered temperature and increased salt concentration on the kinetics and equilibrium processes governing protein-protein interactions in solution. The data indicate that temperature would be a more tractable means of controlling the growth rate for tetragonal lysozyme crystals contrary to the usual practice in, e.g., vapor diffusion protein crystal growth, where both the precipitant and protein concentrations are simultaneously increased. However, the available range for control is dependent upon the protein concentration, with the greatest growth rate control being at the lower concentration.

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

    PubMed

    Bell, K M; Rutherfurd, S M; Morton, R H

    2012-04-01

    Growth rate is an important factor in neonatal survival. The aim of this study was to determine growth rates in hand-reared cheetah cubs in South Africa fed a prescribed energy intake, calculated for growth in the domestic cat. Growth was then compared with previously published data from hand-reared cubs in North America and the relationship between growth and energy intake explored. Daily body weight (BW) gain, feed and energy intake data was collected from 18 hand-reared cheetah cubs up to 120 days of age. The average pre-weaning growth rate was 32 g/day, which is lower than reported in mother-reared cubs and hand-reared cubs in North American facilities. However, post-weaning growth increased to an average of 55 g/day. Growth was approximately linear prior to weaning, but over the entire age range it exhibited a sigmoidal shape with an asymptotic plateau averaging 57 kg. Energy intake associated with pre-weaning growth was 481 kJ ME/kg BW(0.75). Regression analysis described the relationship between metabolic BW, metabolisable energy (ME) intake, and hence daily weight gain. This relationship may be useful in predicting energy intake required to achieve growth rates in hand-reared cheetah cubs similar to those observed for their mother-reared counterparts.

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

    PubMed Central

    Németh, Zoltán; Molnár, Ákos P.; Fejes, Balázs; Novák, Levente; Karaffa, Levente; Keller, Nancy P.; Fekete, Erzsébet

    2016-01-01

    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. PMID:27916804

  9. Growth rate hypothesis and efficiency of protein synthesis under different sulphate concentrations in two green algae.

    PubMed

    Giordano, Mario; Palmucci, Matteo; Raven, John A

    2015-11-01

    The growth rate hypothesis (GRH) predicts a positive correlation between growth rate and RNA content because growth depends upon the protein synthesis machinery. The application of this hypothesis to photoautotrophic organisms has been questioned. We tested the GRH on one prasinophycean, Tetraselmis suecica, and one chlorophycean, Dunaliella salina, grown at three sulphate concentrations. Sulphate was chosen because its concentration in the oceans increased through geological time and apparently had a role in the evolutionary trajectories of phytoplankton. Cell protein content and P quota were positively related to the RNA content (r = 0.62 and r = 0.74, respectively). The correlation of the RNA content with growth rates (r = 0.95) indicates that the GRH was valid for these species when growth rates were below 0.82 d(-1) .

  10. Phytoplankton production and taxon-specific growth rates in the Costa Rica Dome

    PubMed Central

    Selph, Karen E.; Landry, Michael R.; Taylor, Andrew G.; Gutiérrez-Rodríguez, Andrés; Stukel, Michael R.; Wokuluk, John; Pasulka, Alexis

    2016-01-01

    During summer 2010, we investigated phytoplankton production and growth rates at 19 stations in the eastern tropical Pacific, where winds and strong opposing currents generate the Costa Rica Dome (CRD), an open-ocean upwelling feature. Primary production (14C-incorporation) and group-specific growth and net growth rates (two-treatment seawater dilution method) were estimated from samples incubated in situ at eight depths. Our cruise coincided with a mild El Niño event, and only weak upwelling was observed in the CRD. Nevertheless, the highest phytoplankton abundances were found near the dome center. However, mixed-layer growth rates were lowest in the dome center (∼0.5–0.9 day−1), but higher on the edge of the dome (∼0.9–1.0 day−1) and in adjacent coastal waters (0.9–1.3 day−1). We found good agreement between independent methods to estimate growth rates. Mixed-layer growth rates of Prochlorococcus and Synechococcus were largely balanced by mortality, whereas eukaryotic phytoplankton showed positive net growth (∼0.5–0.6 day−1), that is, growth available to support larger (mesozooplankton) consumer biomass. These are the first group-specific phytoplankton rate estimates in this region, and they demonstrate that integrated primary production is high, exceeding 1 g C m−2 day−1 on average, even during a period of reduced upwelling. PMID:27275025

  11. Growth rate of the lithospheric mantle: variations in time and space

    NASA Astrophysics Data System (ADS)

    Artemieva, I. M.

    2007-05-01

    Two global databases for the continents, (a) for tectono-thermal ages and (b) for lithospheric thermal thickness (Artemieva, Tectonophysics, 2006 and available for download at the web-site), are used to calculate (i) the volume of the preserved continental lithosphere of different ages within the individual cratons, (ii) the lithospheric growth rate for different continents over the past 3.6 Ga, (iii) a global model of lithosphere growth rate since the Archean. The submerged areas with continental crust are excluded from the analysis. On the scale of a craton, significant differences in the rates of lithosphere growth are observed between the individual cratons. These data are compared with independent estimates of growth rate of juvenile crust on different continents as constrained by sedimentary record, geological and isotope data. On the global scale, the results show a general agreement between the global cumulative growth rate of the continental lithosphere and juvenile crust (Condie, 1998). The most pronounced peak in lithosphere growth occurred at 2.1-1.7 Ga, when the volume of lithospheric mantle was increasing with the rate of ca. 10-20 (km3 per year). Contrary to growth models of juvenile crust, the peaks in growth rate of the lithospheric mantle at ca. 2.7- 2.6 Ga and 1.3-1.1 Ga are weak, ca. 5-8 (km3 per year). The differences between the growth rates of the lithosphere and juvenile crust are interpreted as indicator of the preservation rate of the cratonic lithosphere since the Archean.

  12. Different growth rates for catalyst-induced and self-induced GaN nanowires

    NASA Astrophysics Data System (ADS)

    Chèze, C.; Geelhaar, L.; Jenichen, B.; Riechert, H.

    2010-10-01

    The catalyst- and self-induced pathways of GaN nanowire growth by molecular beam epitaxy are compared. The catalyst-induced nanowires elongate faster than the self-induced ones and their growth rate is fully determined by the impinging N rate. The self-induced nanowire growth rate is identical on both Si(111) and Si(001) and approaches the impinging N rate only for the few longest nanowires. This difference is attributed to the presence of the Ni-catalyst which enhances the incorporation of Ga at the nanowire tip while for the self-induced nanowires, growth is limited by the different incorporation rates on the nanowire tip and sidewall facets.

  13. MRI-based brain atrophy rates in ADNI phase 2: acceleration and enrichment considerations for clinical trials.

    PubMed

    Hua, Xue; Ching, Christopher R K; Mezher, Adam; Gutman, Boris A; Hibar, Derrek P; Bhatt, Priya; Leow, Alex D; Jack, Clifford R; Bernstein, Matt A; Weiner, Michael W; Thompson, Paul M

    2016-01-01

    The goal of this work was to assess statistical power to detect treatment effects in Alzheimer's disease (AD) clinical trials using magnetic resonance imaging (MRI)-derived brain biomarkers. We used unbiased tensor-based morphometry (TBM) to analyze n = 5,738 scans, from Alzheimer's Disease Neuroimaging Initiative 2 participants scanned with both accelerated and nonaccelerated T1-weighted MRI at 3T. The study cohort included 198 healthy controls, 111 participants with significant memory complaint, 182 with early mild cognitive impairment (EMCI) and 177 late mild cognitive impairment (LMCI), and 155 AD patients, scanned at screening and 3, 6, 12, and 24 months. The statistical power to track brain change in TBM-based imaging biomarkers depends on the interscan interval, disease stage, and methods used to extract numerical summaries. To achieve reasonable sample size estimates for potential clinical trials, the minimal scan interval was 6 months for LMCI and AD and 12 months for EMCI. TBM-based imaging biomarkers were not sensitive to MRI scan acceleration, which gave results comparable with nonaccelerated sequences. ApoE status and baseline amyloid-beta positron emission tomography data improved statistical power. Among healthy, EMCI, and LMCI participants, sample size requirements were significantly lower in the amyloid+/ApoE4+ group than for the amyloid-/ApoE4- group. ApoE4 strongly predicted atrophy rates across brain regions most affected by AD, but the remaining 9 of the top 10 AD risk genes offered no added predictive value in this cohort.

  14. Linking oceanic food webs to coastal production and growth rates of Pacific salmon ( Oncorhynchus spp.), using models on three scales

    NASA Astrophysics Data System (ADS)

    Aydin, Kerim Y.; McFarlane, Gordon A.; King, Jacquelynne R.; Megrey, Bernard A.; Myers, Katherine W.

    2005-03-01

    Three independent modeling methods—a nutrient-phytoplankton-zooplankton (NPZ) model (NEMURO), a food web model (Ecopath/Ecosim), and a bioenergetics model for pink salmon ( Oncorhynchus gorbuscha)—were linked to examine the relationship between seasonal zooplankton dynamics and annual food web productive potential for Pacific salmon feeding and growing in the Alaskan subarctic gyre ecosystem. The linked approach shows the importance of seasonal and ontogenetic prey switching for zooplanktivorous pink salmon, and illustrates the critical role played by lipid-rich forage species, especially the gonatid squid Berryteuthis anonychus, in connecting zooplankton to upper trophic level production in the subarctic North Pacific. The results highlight the need to uncover natural mechanisms responsible for accelerated late winter and early spring growth of salmon, especially with respect to climate change and zooplankton bloom timing. Our results indicate that the best match between modeled and observed high-seas pink salmon growth requires the inclusion of two factors into bioenergetics models: (1) decreasing energetic foraging costs for salmon as zooplankton are concentrated by the spring shallowing of pelagic mixed-layer depth and (2) the ontogenetic switch of salmon diets from zooplankton to squid. Finally, we varied the timing and input levels of coastal salmon production to examine effects of density-dependent coastal processes on ocean feeding; coastal processes that place relatively minor limitations on salmon growth may delay the seasonal timing of ontogenetic diet shifts and thus have a magnified effect on overall salmon growth rates.

  15. Upper bounds for convergence rates of acceleration methods with initial iterations

    NASA Astrophysics Data System (ADS)

    Sidi, Avram; Shapira, Yair

    1998-06-01

    GMRES(n,k), a version of GMRES for the solution of large sparse linear systems, is introduced. A cycle of GMRES(n,k) consists of n Richardson iterations followed by k iterations of GMRES. Such cycles can be repeated until convergence is achieved. The advantage in this approach is in the opportunity to use moderate k, which results in time and memory saving. Because the number of inner products among the vectors of iteration is about k2/2, using a moderate k is particularly attractive on message-passing parallel architectures, where inner products require expensive global communication. The present analysis provides tight upper bounds for the convergence rates of GMRES(n,k) for problems with diagonalizable coefficient matrices whose spectra lie in an ellipse in 0. The advantage of GMRES(n,k) over GMRES(k) is illustrated numerically.

  16. Circulation rate of change: A vortex approach for understanding accelerated inhomogeneous flows through intermediate times

    NASA Astrophysics Data System (ADS)

    Lee, Dong-Kee; Peng, Gaozhu; Zabusky, Norman J.

    2006-09-01

    We present a new simple diagnostic formula, Eq. (4) in this paper, involving a pressure difference, for determining the rate-of-change of total circulation, Γ˙D (within a domain M =1.3), single-mode, inviscid environment with an initially finite-width interfacial transition layer (ITL), and various postshock Atwood numbers, 0.2≤A*≤0.75. We show that for intermediate times (up to t /tM<8.0), Γ˙D/(Γshock/tM), has several consistent behaviors and scaling laws depending on A*. Here Γshock, is the circulation deposited by the initial shock on the region of finite density gradient and tM is the time at which the single mode interfacial midcontour becomes multivalued.

  17. High growth rate 4H-SiC epitaxial growth using dichlorosilane in a hot-wall CVD reactor

    NASA Astrophysics Data System (ADS)

    Chowdhury, Iftekhar; Chandrasekhar, M. V. S.; Klein, Paul B.; Caldwell, Joshua D.; Sudarshan, Tangali

    2011-02-01

    Thick, high quality 4H-SiC epilayers have been grown in a vertical hot-wall chemical vapor deposition system at a high growth rate on (0 0 0 1) 8° off-axis substrates. We discuss the use of dichlorosilane as the Si-precursor for 4H-SiC epitaxial growth as it provides the most direct decomposition route into SiCl 2, which is the predominant growth species in chlorinated chemistries. A specular surface morphology was attained by limiting the hydrogen etch rate until the system was equilibrated at the desired growth temperature. The RMS roughness of the grown films ranged from 0.5-2.0 nm with very few morphological defects (carrots, triangular defects, etc.) being introduced, while enabling growth rates of 30-100 μm/h, 5-15 times higher than most conventional growths. Site-competition epitaxy was observed over a wide range of C/Si ratios, with doping concentrations <1×10 14 cm -3 being recorded. X-ray rocking curves indicated that the epilayers were of high crystallinity, with linewidths as narrow as 7.8 arcsec being observed, while microwave photoconductive decay (μPCD) measurements indicated that these films had high injection (ambipolar) carrier lifetimes in the range of 2 μs.

  18. Longitudinal and seasonal variation of the equatorial flux tube integrated Rayleigh-Taylor instability growth rate

    NASA Astrophysics Data System (ADS)

    Wu, Qian

    2015-09-01

    Using the National Center for Atmospheric Research Thermosphere Ionosphere Electrodynamics General Circulation Model (TIEGCM), the ionospheric Rayleigh-Taylor instability growth rate is calculated. The seasonal and longitudinal variations of the growth rate from the TIEGCM appear to match that of the spread F observed by various satellite missions. The growth rate is strongly dependent on the angle between the sunset terminator and the geomagnetic field line near the magnetic equator. The TIEGCM simulations with nonmigrating tides show the zonal wave number 4 structure in the Rayleigh-Taylor instability due to the inclusion of the nonmigrating diurnal eastward zonal wave number 3 and semidiurnal eastward zonal wave number 2 tides.

  19. A model for scaling in firms’ size and growth rate distribution

    NASA Astrophysics Data System (ADS)

    Metzig, Cornelia; Gordon, Mirta B.

    2014-03-01

    We introduce a simple agent-based model which allows us to analyze three stylized facts: a fat-tailed size distribution of companies, a ‘tent-shaped’ growth rate distribution, the scaling relation of the growth rate variance with firm size, and the causality between them. This is achieved under the simple hypothesis that firms compete for a scarce quantity (either aggregate demand or workforce) which is allocated probabilistically. The model allows us to relate size and growth rate distributions. We compare the results of our model to simulations with other scaling relationships, and to similar models and relate it to existing theory. Effects arising from binning data are discussed.

  20. Sex differentiation in postnatal growth rate: a test in a wild boar population.

    PubMed

    Gaillard, J -M; Pontier, D; Brandt, S; Jullien, J-M; Allainé, D

    1992-05-01

    In wild boar individual growth rate is linear between 0.5 and 6 months after birth, based on successive body weight measurements. Contrary to expectation for a dimorphic and polygynous mammal like wild boar, no sexual dimorphism in growth rate could be detected between 0.5 and 6 months. We argue that high total maternal invesment in offspring due to large litter size and/or strong selection for early reproduction in this population with a short generation time could explain this absence of early differentiation in postnatal growth rate according to offspring sex.

  1. Thin film growth rate effects for primary ion beam deposited diamondlike carbon films

    NASA Technical Reports Server (NTRS)

    Nir, D.; Mirtich, M.

    1986-01-01

    Diamondlike carbon (DLC) films were grown by primary ion beam deposition and the growth rates were measured for various beam energies, types of hydrocarbon gases and their ratio to Ar, and substrate materials. The growth rate had a linear dependence upon hydrocarbon content in the discharge chamber, and only small dependence on other parameters. For given deposition conditions a threshold in the atomic ratio of carbon to argon gas was identified below which films did not grow on fused silica substrate, but grew on Si substrate and on existing DLC films. Ion source deposition parameters and substrate material were found to affect the deposition threshold and film growth rates.

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

    PubMed

    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; Hernández, Vicente Guzmán; 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

    2017-04-04

    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 demonstrates the

  3. Patient-derived xenograft (PDX) tumors increase growth rate with time.

    PubMed

    Pearson, Alexander T; Finkel, Kelsey A; Warner, Kristy A; Nör, Felipe; Tice, David; Martins, Manoela D; Jackson, Trachette L; Nör, Jacques E

    2016-02-16

    Patient-derived xenograft (PDX) models are frequently used for translational cancer research, and are assumed to behave consistently as the tumor ages. However, growth rate constancy as a function of time is unclear. Notably, variable PDX growth rates over time might have implications for the interpretation of translational studies. We characterized four PDX models through several in vivo passages from primary human head and neck squamous cell carcinoma and salivary gland adenoid cystic carcinoma. We developed a mathematical approach to merge growth data from different passages into a single measure of relative tumor volume normalized to study initiation size. We analyzed log-relative tumor volume increase with linear mixed effect models. Two oral pathologists analyzed the PDX tissues to determine if histopathological feature changes occurred over in vivo passages. Tumor growth rate increased over time. This was determined by repeated measures linear regression statistical analysis in four different PDX models. A quadratic statistical model for the temporal effect predicted the log-relative tumor volume significantly better than a linear time effect model. We found a significant correlation between passage number and histopathological features of higher tumor grade. Our mathematical treatment of PDX data allows statistical analysis of tumor growth data over long periods of time, including over multiple passages. Non-linear tumor growth in our regression models revealed the exponential growth rate increased over time. The dynamic tumor growth rates correlated with quantifiable histopathological changes that related to passage number in multiple types of cancer.

  4. Effects of loading on the growth rates of deep stress-corrosion cracks

    SciTech Connect

    Beavers, J.A.; Christman, T.K.

    1990-08-01

    The goal of this research program was to determine the effects of loading on growth of stress-corrosion cracks (SCC) in line pipe steel and whether special loading procedures could actually inhibit crack growth. Of particular interest was the effect of hydrostatic retesting on the subsequent growth of existing cracks. The growth rate experiments showed that the slow-strain rate loading could successfully nucleate a group of fine cracks with depths up to 0.025 inches (0.64 mm). However, the subsequent cyclic loading at typical operating stress levels (lower than experienced during the slow- strain rate loading) produced minimal crack growth and stopped soon after the test was started. The limited growth is believed to be a real phenomenon which means this is not a suitable procedure for the measurement of average crack growth rates. These experiments indicate that cracks grown at high stress (as in the slow-strain rate phase) do not readily propagate at lower stress levels. This may be because of crack closure (compressive crack tip residual stress) induced by the initial higher stress level. If that is true, then hydrostatic retests could inhibit the growth of existing stress-corrosion cracks, especially if the hydrostatic tests are conducted at high stress levels. 15 figures, 3 tabs.

  5. Patient-derived xenograft (PDX) tumors increase growth rate with time

    PubMed Central

    Pearson, Alexander T.; Finkel, Kelsey A.; Warner, Kristy A.; Nör, Felipe; Tice, David; Martins, Manoela D.; Jackson, Trachette L.; Nör, Jacques E.

    2016-01-01

    Patient-derived xenograft (PDX) models are frequently used for translational cancer research, and are assumed to behave consistently as the tumor ages. However, growth rate constancy as a function of time is unclear. Notably, variable PDX growth rates over time might have implications for the interpretation of translational studies. We characterized four PDX models through several in vivo passages from primary human head and neck squamous cell carcinoma and salivary gland adenoid cystic carcinoma. We developed a mathematical approach to merge growth data from different passages into a single measure of relative tumor volume normalized to study initiation size. We analyzed log-relative tumor volume increase with linear mixed effect models. Two oral pathologists analyzed the PDX tissues to determine if histopathological feature changes occurred over in vivo passages. Tumor growth rate increased over time. This was determined by repeated measures linear regression statistical analysis in four different PDX models. A quadratic statistical model for the temporal effect predicted the log-relative tumor volume significantly better than a linear time effect model. We found a significant correlation between passage number and histopathological features of higher tumor grade. Our mathematical treatment of PDX data allows statistical analysis of tumor growth data over long periods of time, including over multiple passages. Non-linear tumor growth in our regression models revealed the exponential growth rate increased over time. The dynamic tumor growth rates correlated with quantifiable histopathological changes that related to passage number in multiple types of cancer. PMID:26783960

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

    PubMed

    Matos, Dominick A; Cole, Benjamin J; Whitney, Ian P; MacKinnon, Kirk J-M; Kay, Steve A; Hazen, Samuel P

    2014-01-01

    Plant growth is commonly regulated by external cues such as light, temperature, water availability, and internal cues generated by the circadian clock. Changes in the rate of growth within the course of a day have been observed in the leaves, stems, and roots of numerous species. However, the relative impact of the circadian clock on the growth of grasses has not been thoroughly characterized. We examined the influence of diurnal temperature and light changes, and that of the circadian clock on leaf length growth patterns in Brachypodium distachyon using high-resolution time-lapse imaging. Pronounced changes in growth rate were observed under combined photocyles and thermocycles or with thermocycles alone. A considerably more rapid growth rate was observed at 28°C than 12°C, irrespective of the presence or absence of light. In spite of clear circadian clock regulated gene expression, plants exhibited no change in growth rate under conditions of constant light and temperature, and little or no effect under photocycles alone. Therefore, temperature appears to be the primary cue influencing observed oscillations in growth rate and not the circadian clock or photoreceptor activity. Furthermore, the size of the leaf meristem and final cell length did not change in response to changes in temperature. Therefore, the nearly five-fold difference in growth rate observed across thermocycles can be attributed to proportionate changes in the rate of cell division and expansion. A better understanding of the growth cues in B. distachyon will further our ability to model metabolism and biomass accumulation in grasses.

  7. Crack growth rate in core shroud horizontal welds using two models for a BWR

    NASA Astrophysics Data System (ADS)

    Arganis Juárez, C. R.; Hernández Callejas, R.; Medina Almazán, A. L.

    2015-05-01

    An empirical crack growth rate correlation model and a predictive model based on the slip-oxidation mechanism for Stress Corrosion Cracking (SCC) were used to calculate the crack growth rate in a BWR core shroud. In this study, the crack growth rate was calculated by accounting for the environmental factors related to aqueous environment, neutron irradiation to high fluence and the complex residual stress conditions resulting from welding. In estimating the SCC behavior the crack growth measurements data from a Boiling Water Reactor (BWR) plant are referred to, and the stress intensity factor vs crack depth throughout thickness is calculated using a generic weld residual stress distribution for a core shroud, with a 30% stress relaxation induced by neutron irradiation. Quantitative agreement is shown between the measurements of SCC growth rate and the predictions of the slip-oxidation mechanism model for relatively low fluences (5 × 1024 n/m2), and the empirical model predicted better the SCC growth rate than the slip-oxidation model for high fluences (>1 × 1025 n/m2). The relevance of the models predictions for SCC growth rate behavior depends on knowing the model parameters.

  8. Phytoplankton growth rates in a light-limited environment, San Francisco Bay

    USGS Publications Warehouse

    Alpine, Andrea E.; Cloern, James E.

    1988-01-01

    This study was motivated by the need for quantitative measures of phytoplankton population growth rate in an estuarine environment, and was designed around the presumption that growth rates can be related empirically to light exposure. We conducted the study in San Francisco Bay (California, USA), which has large horizontal gradients in light availability (Zp:Zm) typical of many coastal plain estuaries, and nutrient concentrations that often exceed those presumed to limit phytoplankton growth (Cloern et al. 1985). We tested the hypothesis that light availability is the primary control of phytoplankton growth, and that previous estimates of growth rate based on the ratio of productivity to biomass (Cloern et al. 1985) are realistic. Specifically, we wanted to verify that growth rate varies spatially along horizontal gradients of light availability indexed as Zp:Zm, such that phytoplankton turnover rate is rapid in shallow clear areas (high Zp:Zm) and slow in deep turbid areas (low Zp:Zm). We used an in situ incubation technique which simulated vertical mixing, and measured both changes in cell number and carbon production as independent estimates of growth rate across a range of Zp:Zm ratios.

  9. Threshold effect of growth rate on population variability of Escherichia coli cell lengths

    PubMed Central

    2017-01-01

    A long-standing question in biology is the effect of growth on cell size. Here, we estimate the effect of Escherichia coli growth rate (r) on population cell size distributions by estimating the coefficient of variation of cell lengths (CVL) from image analysis of fixed cells in DIC microscopy. We find that the CVL is constant at growth rates less than one division per hour, whereas above this threshold, CVL increases with an increase in the growth rate. We hypothesize that stochastic inhibition of cell division owing to replication stalling by a RecA-dependent mechanism, combined with the growth rate threshold of multi-fork replication (according to Cooper and Helmstetter), could form the basis of such a threshold effect. We proceed to test our hypothesis by increasing the frequency of stochastic stalling of replication forks with hydroxyurea (HU) treatment and find that cell length variability increases only when the growth rate exceeds this threshold. The population effect is also reproduced in single-cell studies using agar-pad cultures and ‘mother machine’-based experiments to achieve synchrony. To test the role of RecA, critical for the repair of stalled replication forks, we examine the CVL of E. coli ΔrecA cells. We find cell length variability in the mutant to be greater than wild-type, a phenotype that is rescued by plasmid-based RecA expression. Additionally, we find that RecA-GFP protein recruitment to nucleoids is more frequent at growth rates exceeding the growth rate threshold and is further enhanced on HU treatment. Thus, we find growth rates greater than a threshold result in increased E. coli cell lengths in the population, and this effect is, at least in part, mediated by RecA recruitment to the nucleoid and stochastic inhibition of division. PMID:28386413

  10. Elevational variation in adult body size and growth rate but not in metabolic rate in the tree weta Hemideina crassidens.

    PubMed

    Bulgarella, Mariana; Trewick, Steven A; Godfrey, A Jonathan R; Sinclair, Brent J; Morgan-Richards, Mary

    2015-04-01

    Populations of the same species inhabiting distinct localities experience different ecological and climatic pressures that might result in differentiation in traits, particularly those related to temperature. We compared metabolic rate (and its thermal sensitivity), growth rate, and body size among nine high- and low-elevation populations of the Wellington tree weta, Hemideina crassidens, distributed from 9 to 1171 m a.s.l across New Zealand. Our results did not indicate elevational compensation in metabolic rates (metabolic cold adaptation). Cold acclimation decreased metabolic rate compared to warm-acclimated individuals from both high- and low-elevation populations. However, we did find countergradient variation in growth rates, with individuals from high-elevation populations growing faster and to a larger final size than individuals from low-elevation populations. Females grew faster to a larger size than males, although as adults their metabolic rates did not differ significantly. The combined physiological and morphological data suggest that high-elevation individuals grow quickly and achieve larger size while maintaining metabolic rates at levels not significantly different from low-elevation individuals. Thus, morphological differentiation among tree weta populations, in concert with genetic variation, might provide the material required for adaptation to changing conditions.

  11. Growth against entropy in bacterial metabolism: the phenotypic trade-off behind empirical growth rate distributions in E. coli

    NASA Astrophysics Data System (ADS)

    De Martino, Daniele; Capuani, Fabrizio; De Martino, Andrea

    2016-06-01

    The solution space of genome-scale models of cellular metabolism provides a map between physically viable flux configurations and cellular metabolic phenotypes described, at the most basic level, by the corresponding growth rates. By sampling the solution space of E. coli's metabolic network, we show that empirical growth rate distributions recently obtained in experiments at single-cell resolution can be explained in terms of a trade-off between the higher fitness of fast-growing phenotypes and the higher entropy of slow-growing ones. Based on this, we propose a minimal model for the evolution of a large bacterial population that captures this trade-off. The scaling relationships observed in experiments encode, in such frameworks, for the same distance from the maximum achievable growth rate, the same degree of growth rate maximization, and/or the same rate of phenotypic change. Being grounded on genome-scale metabolic network reconstructions, these results allow for multiple implications and extensions in spite of the underlying conceptual simplicity.

  12. Delta L: An Apparatus for Measuring Macromolecular Crystal Growth Rates in Microgravity

    NASA Technical Reports Server (NTRS)

    Judge, Russell A.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    In order to determine how macromolecule crystal quality improvement in microgravity is related to crystal growth characteristics, is was necessary to develop new hardware that could measure the crystal growth rates of a population of crystals growing under the same solution conditions. As crystal growth rate is defined as the change or delta in a defined dimension or length (L) of a crystal over time, the hardware was named Delta L. Delta L consists of fluids, optics, and data acquisition, sub-assemblies. Temperature control is provided for the crystal growth chamber. Delta L will be used in connection with the Glovebox Integrated Microgravity Isolation Technology (g-LIMIT) inside the Microgravity Science Glovebox (MSG), onboard the International Space Station (ISS). Delta L prototype hardware has been assembled. This paper will describe an overview of the design of Delta L and present preliminary crystal growth rate data.

  13. Ab initio determination of the instability growth rate of warm dense beryllium-deuterium interface

    SciTech Connect

    Wang, Cong; Zhang, Ping; Li, Zi; Li, DaFang

    2015-10-15

    Accurate knowledge about the interfacial unstable growth is of great importance in inertial confinement fusion. During implosions, the deuterium-tritium capsule is driven by laser beams or X-rays to access the strongly coupled and partially degenerated warm dense matter regime. At this stage, the effects of dissipative processes, such as diffusion and viscosity, have significant impact on the instability growth rates. Here, we present ab initio molecular dynamics simulations to determine the equations of state and the transport coefficients. Several models are used to estimate the reduction in the growth rate dispersion curves of Rayleigh-Taylor and Richtmyer-Meshkov instabilities with considering the presence of these dissipative effects. We show that these instability growth rates are effectively reduced when considering diffusion. The findings provide significant insights into the microscopic mechanism of the instability growth at the ablator-fuel interface and will refine the models used in the laser-driven hydrodynamic instability experiments.

  14. Growth rate regulation of translation initiation factor IF3 biosynthesis in Escherichia coli.

    PubMed Central

    Liveris, D; Klotsky, R A; Schwartz, I

    1991-01-01

    infC, the gene encoding translation initiation factor IF3 in Escherichia coli, can be transcribed from three promoters. Two of these promoters, PI1 and PI2, are located in the upstream thrS sequence which codes for threonyl-tRNA synthetase. Previous studies had shown that PI2 was the major promoter for infC. In the present study, the extent of transcription from PI1 and/or PI2 at a variety of steady-state growth rates was analyzed by promoter fusion studies. PI2 was the more active promoter (two- to threefold stronger than PI1) at all growth rates tested. A fusion plasmid containing both PI1 and PI2 exhibited a transcription level approximately equal to the sum of those observed with the fusion plasmids containing the individual promoters. The transcriptional activities of PI1 and PI2 did not change as the growth rate was varied from 0.3 to 1.7 doublings per h. In contrast, a fusion plasmid carrying the rrnB P1 promoter displayed the expected growth rate response. The steady-state concentrations of infC mRNA in cells grown at different rates were measured and found not to vary. These results indicate that the previously reported growth rate regulation of IF3 biosynthesis neither is accomplished by transcriptional control nor is a result of differential mRNA stability. In view of these results, the steady-state levels of IF3 in cells grown at a number of different growth rates were determined by quantitative immunoblotting. IF3 levels were found to vary with growth rate in a manner essentially identical to that observed for ribosomes. A model accounting for these results and describing a mechanism for coordinate growth rate-regulated expression of ribosomes and IF3 is presented. Images PMID:2050639

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

    PubMed

    Lee, Donghun; Kim, Young-Sik; Song, Jungbin; Kim, Hyun Soo; Lee, Hyun Jung; Guo, Hailing; Kim, Hocheol

    2016-04-07

    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.

  16. Acceleration in the rate of CNS remyelination in lysolecithin-induced demyelination.

    PubMed

    Pavelko, K D; van Engelen, B G; Rodriguez, M

    1998-04-01

    One important therapeutic goal during CNS injury from trauma or demyelinating diseases such as multiple sclerosis is to develop methods to promote remyelination. We tested the hypothesis that spontaneous remyelination in the toxic nonimmune model of lysolecithin-induced demyelination can be enhanced by manipulating the inflammatory response. In PBS-treated SJL/J mice, the number of remyelinating axons per square millimeter of lesion area increased significantly 3 and 5 weeks after lysolecithin injection in the spinal cord. However, methylprednisolone or a monoclonal antibody (mAb), SCH94.03, developed for its ability to promote remyelination in the Theiler's virus murine model of demyelination, further increased the number of remyelinating axons per lesion area at 3 weeks by a factor of 2.6 and 1.9, respectively, but did not increase the ratio of myelin sheath thickness to axon diameter or the number of cells incorporating tritiated thymidine in the lesion. After 3 weeks, the number of remyelinating axons in the methylprednisolone or mAb SCH94.03 treatment groups was similar to the spontaneous remyelination in the 5 week PBS control-treated group, indicating that these treatments promoted remyelination by increasing its rate rather than its extent. To address a mechanism for promoting remyelination, through an effect on scavenger function, we assessed morphometrically the number of macrophages in lesions after methylprednisolone and mAb SCH94.03 treatment. Methylprednisolone reduced the number of macrophages, but SCH94.03 did not, although both enhanced remyelination. This study supports the hypothesis that even in toxic nonprimary immune demyelination, manipulating the inflammatory response is a benefit in myelin repair.

  17. Using scale characteristics and water temperature to reconstruct growth rates of juvenile steelhead Oncorhynchus mykiss.

    PubMed

    Beakes, M P; Sharron, S; Charish, R; Moore, J W; Satterthwaite, W H; Sturm, E; Wells, B K; Sogard, S M; Mangel, M

    2014-01-01

    Juvenile steelhead Oncorhynchus mykiss from a northern California Central Valley population were reared in a controlled laboratory experiment. Significantly different rates of growth were observed among fish reared under two ration treatments and three temperature treatments (8, 14 and 20°C). Wider circulus spacing and faster deposition was associated with faster growth. For the same growth rate, however, circulus spacing was two-fold wider and deposited 36% less frequently in the cold compared to the hot temperature treatment. In a multiple linear regression, median circulus spacing and water temperature accounted for 68% of the variation in observed O. mykiss growth. These results corroborate previous research on scale characteristics and growth, while providing novel evidence that highlights the importance of water temperature in these relationships. Thus, this study establishes the utility of using scale analysis as a relatively non-invasive method for inferring growth in salmonids.

  18. Wakefield-acceleration of relativistic electrons with few-cycle laser pulses at kHz-repetition-rate

    NASA Astrophysics Data System (ADS)

    Guenot, Diego; Gustas, Dominykas; Vernier, Aline; Boehle, Frederik; Beaurepaire, Benoit; Lopez-Martens, Rodrigo; Faure, Jerome; Appli Team

    2016-10-01

    The generation of relativistic electron beams using laser wakefield acceleration has become a standard technique, providing low emittance electron bunches with femtosecond durations. However, this technique usually requires multi-ten-terawatt lasers and is thus limited to low repetition-rate (typically 10 Hz or less). We have recently demonstrated the generation of few MeV electrons using 2.5-mJ, 4-fs, 1-kHz repetition-rate laser pulses, focused to relativistic intensity onto a gas jet with electron density 1020 cm-3. We have investigated the influence of the pulse duration, the gas density. We demonstrated that an electron beam with a charge in the range of 10-fC/shot, with a divergence of 20-mrad and a peaked spectrum with energies between 2 and 4 MeV can be generated at kHz repetition-rate. These results confirm the possibility of using few-cycle laser pulses with very low energy for exciting wakefields in the bubble regime and for trapping electrons, as predicted by PIC simulations. This kHz electron source is ideally suited for performing electron diffraction experiments with very high temporal resolution. Our results also open the way to other applications, such as the generation of a kHz ultrafast X-ray source. ERC femtoelec.

  19. Application of Overall Dynamic Body Acceleration as a Proxy for Estimating the Energy Expenditure of Grazing Farm Animals: Relationship with Heart Rate

    PubMed Central

    Miwa, Masafumi; Oishi, Kazato; Nakagawa, Yasuhiro; Maeno, Hiromichi; Anzai, Hiroki; Kumagai, Hajime; Okano, Kanji; Tobioka, Hisaya; Hirooka, Hiroyuki

    2015-01-01

    Estimating the energy expenditure of farm animals at pasture is important for efficient animal management. In recent years, an alternative technique for estimating energy expenditure by measuring body acceleration has been widely performed in wildlife and human studies, but the availability of the technique in farm animals has not yet been examined. In the present study, we tested the potential use of an acceleration index, overall dynamic body acceleration (ODBA), as a new proxy for estimating the energy expenditure of grazing farm animals (cattle, goats and sheep) at pasture with the simultaneous evaluation of a conventional proxy, heart rate. Body accelerations in three axes and heart rate for cows (n = 8, two breeds), goats (n = 6) and sheep (n = 5) were recorded, and the effect of ODBA calculated from the body accelerations on heart rate was analyzed. In addition, the effects of the two other activity indices, the number of steps and vectorial dynamic body acceleration (VeDBA), on heart rate were also investigated. The results of the comparison among three activity indices indicated that ODBA was the best predictor for heart rate. Although the relationship between ODBA and heart rate was different between the groups of species and breeds and between individuals (P<0.01), the difference could be explained by different body weights; a common equation could be established by correcting the body weights (M: kg): heart rate (beats/min) = 147.263∙M-0.141 + 889.640∙M-0.179∙ODBA (g). Combining this equation with the previously reported energy expenditure per heartbeat, we estimated the energy expenditure of the tested animals, and the results indicated that ODBA is a good proxy for estimating the energy expenditure of grazing farm animals across species and breeds. The utility and simplicity of the procedure with acceleration loggers could make the accelerometry technique a worthwhile option in field research and commercial farm use. PMID:26030931

  20. Application of overall dynamic body acceleration as a proxy for estimating the energy expenditure of grazing farm animals: relationship with heart rate.

    PubMed

    Miwa, Masafumi; Oishi, Kazato; Nakagawa, Yasuhiro; Maeno, Hiromichi; Anzai, Hiroki; Kumagai, Hajime; Okano, Kanji; Tobioka, Hisaya; Hirooka, Hiroyuki

    2015-01-01

    Estimating the energy expenditure of farm animals at pasture is important for efficient animal management. In recent years, an alternative technique for estimating energy expenditure by measuring body acceleration has been widely performed in wildlife and human studies, but the availability of the technique in farm animals has not yet been examined. In the present study, we tested the potential use of an acceleration index, overall dynamic body acceleration (ODBA), as a new proxy for estimating the energy expenditure of grazing farm animals (cattle, goats and sheep) at pasture with the simultaneous evaluation of a conventional proxy, heart rate. Body accelerations in three axes and heart rate for cows (n = 8, two breeds), goats (n = 6) and sheep (n = 5) were recorded, and the effect of ODBA calculated from the body accelerations on heart rate was analyzed. In addition, the effects of the two other activity indices, the number of steps and vectorial dynamic body acceleration (VeDBA), on heart rate were also investigated. The results of the comparison among three activity indices indicated that ODBA was the best predictor for heart rate. Although the relationship between ODBA and heart rate was different between the groups of species and breeds and between individuals (P<0.01), the difference could be explained by different body weights; a common equation could be established by correcting the body weights (M: kg): heart rate (beats/min) = 147.263∙M-0.141 + 889.640∙M-0.179∙ODBA (g). Combining this equation with the previously reported energy expenditure per heartbeat, we estimated the energy expenditure of the tested animals, and the results indicated that ODBA is a good proxy for estimating the energy expenditure of grazing farm animals across species and breeds. The utility and simplicity of the procedure with acceleration loggers could make the accelerometry technique a worthwhile option in field research and commercial farm use.

  1. The effects of population density on juvenile growth rate in white-tailed deer.

    PubMed

    Barr, Brannon; Wolverton, Steve

    2014-10-01

    Animal body size is driven by habitat quality, food availability, and nutrition. Adult size can relate to birth weight, to length of the ontogenetic growth period, and/or to the rate of growth. Data requirements are high for studying these growth mechanisms, but large datasets exist for some game species. In North America, large harvest datasets exist for white-tailed deer (Odocoileus virginianus), but such data are collected under a variety of conditions and are generally dismissed for ecological research beyond local population and habitat management. We contend that such data are useful for studying the ecology of white-tailed deer growth and body size when analyzed at ordinal scale. In this paper, we test the response of growth rate to food availability by fitting a logarithmic equation that estimates growth rate only to harvest data from Fort Hood, Texas, and track changes in growth rate over time. Results of this ordinal scale model are compared to previously published models that include additional parameters, such as birth weight and adult weight. It is shown that body size responds to food availability by variation in growth rate. Models that estimate multiple parameters may not work with harvest data because they are prone to error, which renders estimates from complex models too variable to detect interannual changes in growth rate that this ordinal scale model captures. This model can be applied to harvest data, from which inferences about factors that influence animal growth and body size (e.g., habitat quality and nutritional availability) can be drawn.

  2. The Effects of Population Density on Juvenile Growth Rate in White-Tailed Deer

    NASA Astrophysics Data System (ADS)

    Barr, Brannon; Wolverton, Steve

    2014-10-01

    Animal body size is driven by habitat quality, food availability, and nutrition. Adult size can relate to birth weight, to length of the ontogenetic growth period, and/or to the rate of growth. Data requirements are high for studying these growth mechanisms, but large datasets exist for some game species. In North America, large harvest datasets exist for white-tailed deer ( Odocoileus virginianus), but such data are collected under a variety of conditions and are generally dismissed for ecological research beyond local population and habitat management. We contend that such data are useful for studying the ecology of white-tailed deer growth and body size when analyzed at ordinal scale. In this paper, we test the response of growth rate to food availability by fitting a logarithmic equation that estimates growth rate only to harvest data from Fort Hood, Texas, and track changes in growth rate over time. Results of this ordinal scale model are compared to previously published models that include additional parameters, such as birth weight and adult weight. It is shown that body size responds to food availability by variation in growth rate. Models that estimate multiple parameters may not work with harvest data because they are prone to error, which renders estimates from complex models too variable to detect interannual changes in growth rate that this ordinal scale model captures. This model can be applied to harvest data, from which inferences about factors that influence animal growth and body size (e.g., habitat quality and nutritional availability) can be drawn.

  3. Reduction of translating ribosomes enables Escherichia coli to maintain elongation rates during slow growth

    PubMed Central

    Dai, Xiongfeng; Zhu, Manlu; Warren, Mya; Balakrishnan, Rohan; Patsalo, Vadim; Okano, Hiroyuki; Williamson, James R.; Fredrick, Kurt; Wang, Yi-Ping; Hwa, Terence

    2017-01-01

    Bacteria growing in different conditions experience a broad range of demand on the rate of protein synthesis which profoundly affects cellular resource allocation. During fast growth, protein synthesis is long known to be modulated by adjusting the ribosome content, with the vast majority of ribosomes engaged at a near-maximal rate of elongation. Here we characterized protein synthesis by E. coli systematically, focusing on slow growth conditions. We establish that the translational elongation rate decreases as growth slows down, exhibiting a Michaelis-Menten dependence on the abundance of the cellular translational apparatus. However, an appreciable elongation rate is maintained even towards zero growth including the stationary phase. This maintenance, critical for timely protein synthesis in harsh environments, is accompanied by a drastic reduction in the fraction of active ribosomes. Interestingly, well-known antibiotics such as chloramphenicol also cause substantial reduction in the pool of active ribosomes, instead of slowing down translational elongation as commonly thought. PMID:27941827

  4. Reduction of translating ribosomes enables Escherichia coli to maintain elongation rates during slow growth.

    PubMed

    Dai, Xiongfeng; Zhu, Manlu; Warren, Mya; Balakrishnan, Rohan; Patsalo, Vadim; Okano, Hiroyuki; Williamson, James R; Fredrick, Kurt; Wang, Yi-Ping; Hwa, Terence

    2016-12-12

    Bacteria growing under different conditions experience a broad range of demand on the rate of protein synthesis, which profoundly affects cellular resource allocation. During fast growth, protein synthesis has long been known to be modulated by adjusting the ribosome content, with the vast majority of ribosomes engaged at a near-maximal rate of elongation. Here, we systematically characterize protein synthesis by Escherichia coli, focusing on slow-growth conditions. We establish that the translational elongation rate decreases as growth slows, exhibiting a Michaelis-Menten dependence on the abundance of the cellular translational apparatus. However, an appreciable elongation rate is maintained even towards zero growth, including the stationary phase. This maintenance, critical for timely protein synthesis in harsh environments, is accompanied by a drastic reduction in the fraction of active ribosomes. Interestingly, well-known antibiotics such as chloramphenicol also cause a substantial reduction in the pool of active ribosomes, instead of slowing down translational elongation as commonly thought.

  5. Crossflow effects on the growth rate of inviscid Goertler vortices in a hypersonic boundary layer

    NASA Technical Reports Server (NTRS)

    Fu, Yibin; Hall, Philip

    1992-01-01

    The effects of crossflow on the growth rate of inviscid Goertler vortices in a hypersonic boundary layer with pressure gradient are studied. Attention is focused on the inviscid mode trapped in the temperature adjustment layer; this mode has greater growth rate than any other mode. The eigenvalue problem which governs the relationship between the growth rate, the crossflow amplitude, and the wavenumber is solved numerically, and the results are then used to clarify the effects of crossflow on the growth rate of inviscid Goertler vortices. It is shown that crossflow effects on Goertler vortices are fundamentally different for incompressible and hypersonic flows. The neutral mode eigenvalue problem is found to have an exact solution, and as a by-product, we have also found the exact solution to a neutral mode eigenvalue problem which was formulated, but unsolved before, by Bassom and Hall (1991).

  6. Theoretical growth rates, periods, and pulsation constants for long-period variables

    NASA Astrophysics Data System (ADS)

    Fox, M. W.; Wood, P. R.

    1982-08-01

    An extensive set of linear, nonadiabatic pulsation models for red giant and supergiant stars is computed, in order that the dependence of pulsation periods (P), pulsation constants (Q), and growth rate on physical input parameters can be determined from the systematic behavior seen in the models. Also investigated is the extent of the dependence of P, Q, and growth rate on uncertain quantities such as atmospheric molecular opacity, surface boundary conditions, and effective temperature. The growth rate for the fundamental mode is found to increase with luminosity on the giant branch while the growth rate for the first overtone decreases. Dynamical instabilities found in previous adiabatic models of extreme red giants do not occur when nonadiabatic effects are included in the models.

  7. The annual cycle in ENSO growth rate as a cause of the spring predictability barrier

    NASA Astrophysics Data System (ADS)

    Levine, Aaron F. Z.; McPhaden, Michael J.

    2015-06-01

    The spring predictability barrier increases the uncertainty in ENSO forecasts starting before and during the boreal spring. Recent work has shown that the annual cycle of ENSO growth rate is responsible for phase locking of peak ENSO development to the boreal winter, suggesting that this annual cycle may play a role in the spring predictability barrier. To test this hypothesis, the annual cycle of ENSO growth rate is added to a damped, noise-driven conceptual recharge oscillator model. When the annual cycle of ENSO growth rate is included, a spring predictability barrier develops, whereas without it ENSO predictability is independent of the forecast start date. When state-dependent noise is included in the simulations in addition to the annual cycle of the growth rate, the spring predictability barrier is enhanced and more realistic.

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

    PubMed Central

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

    2014-01-01

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

  9. Initial results of Alloy 600 crack growth rate testing in PWR environments

    SciTech Connect

    Foster, J.P.; Bamford, W.H.; Pathania, R.S.

    1995-12-31

    Initial crack growth rate results on the effects of stress intensity factor, temperature, material heat and experimental methods were studied on Alloy 600 control rod drive head penetrations using fracture mechanics samples. Crack growth rate data were obtained using the reverse DC potential difference crack monitoring method on 1/2T CT samples tested at temperatures of 310 to 330 C in 1200 ppm B + 2 ppm Li + 25 cc/kg H{sub 2} water. The results are consistent with a crack growth rate estimation model developed by Scott. Most of the heats tested to date are consistent with the Scott model; however, enhanced crack growth rates were exhibited by two heats with low grain boundary carbide coverage.

  10. Dependence of growth rate of quartz in fused silica on pressure and impurity content

    NASA Technical Reports Server (NTRS)

    Fratello, V. J.; Hays, J. F.; Turnbull, D.

    1980-01-01

    The effects of pressure, temperature, and some variations in impurity content on the growth rate u of quartz into fused silica were measured. Under all conditions the growth rate was interface controlled and increased exponentially with pressure with an activation volume averaging -21.2 cu cm/mole. The activation enthalpy for all specimens is extrapolated to a zero pressure value of 64 kcal/mole, within the experimental uncertainty. At a given stoichiometry the effect of hydroxyl content on growth rate is described entirely by a linear term C(OH) in the prefactor of the equation for the growth rate. The effect of chlorine impurity can be described similarly. Also u is increased as the ideal stoichiometry is approached from the partially reduced state.

  11. In situ growth rates of deep-water octocorals determined from 3D photogrammetric reconstructions

    NASA Astrophysics Data System (ADS)

    Bennecke, Swaantje; Kwasnitschka, Tom; Metaxas, Anna; Dullo, Wolf-Christian

    2016-12-01

    Growth rates of deep-water corals provide important information on the recovery potential of these ecosystems, for example from fisheries-induced impacts. Here, we present in situ growth dynamics that are currently largely unknown for deep-water octocorals, calculated by applying a non-destructive method. Videos of a boulder harbouring multiple colonies of Paragorgia arborea and Primnoa resedaeformis in the Northeast Channel Coral Conservation Area at the entrance to the Gulf of Maine at 863 m depth were collected in 2006, 2010 and 2014. Photogrammetric reconstructions of the boulder and the fauna yielded georeferenced 3D models for all sampling years. Repeated measurements of total length and cross-sectional area of the same colonies allowed the observation of growth dynamics. Growth rates of total length of Paragorgia arborea decreased over time with higher rates between 2006 and 2010 than between 2010 and 2014, while growth rates of cross-sectional area remained comparatively constant. A general trend of decreasing growth rates of total length with size of the coral colony was documented. While no growth was observed for the largest colony (165 cm in length) between 2010 and 2014, a colony 50-65 cm in length grew 3.7 cm yr-1 between 2006 and 2010. Minimum growth rates of 1.6-2.7 cm yr-1 were estimated for two recruits (<23 cm in 2014) of Primnoa resedaeformis. We successfully extracted biologically meaningful data from photogrammetric models and present the first in situ growth rates for these coral species in the Northwest Atlantic.

  12. Growth rates of rainbow smelt in Lake Champlain: Effects of density and diet

    USGS Publications Warehouse

    Stritzel, Thomson J.L.; Parrish, D.L.; Parker-Stetter, S. L.; Rudstam, L. G.; Sullivan, P.J.

    2011-01-01

    Stritzel Thomson JL, Parrish DL, Parker-Stetter SL, Rudstam LG, Sullivan PJ. Growth rates of rainbow smelt in Lake Champlain: effects of density and diet. Ecology of Freshwater Fish 2010. ?? 2010 John Wiley & Sons A/S Abstract- We estimated the densities of rainbow smelt (Osmerus mordax) using hydroacoustics and obtained specimens for diet analysis and groundtruthed acoustics data from mid-water trawl sampling in four areas of Lake Champlain, USA-Canada. Densities of rainbow smelt cohorts alternated during the 2-year study; age-0 rainbow smelt were very abundant in 2001 (up to 6fish per m2) and age-1 and older were abundant (up to 1.2fish per m2) in 2002. Growth rates and densities varied among areas and years. We used model selection on eight area-year-specific variables to investigate biologically plausible predictors of rainbow smelt growth rates. The best supported model of growth rates of age-0 smelt indicated a negative relationship with age-0 density, likely associated with intraspecific competition for zooplankton. The next best-fit model had age-1 density as a predictor of age-0 growth. The best supported models (N=4) of growth rates of age-1 fish indicated a positive relationship with availability of age-0 smelt and resulting levels of cannibalism. Other plausible models were contained variants of these parameters. Cannibalistic rainbow smelt consumed younger conspecifics that were up to 53% of their length. Prediction of population dynamics for rainbow smelt requires an understanding of the relationship between density and growth as age-0 fish outgrow their main predators (adult smelt) by autumn in years with fast growth rates, but not in years with slow growth rates. ?? 2011 John Wiley & Sons A/S.

  13. Flavonoids Released Naturally from Alfalfa Seeds Enhance Growth Rate of Rhizobium meliloti1

    PubMed Central

    Hartwig, Ueli A.; Joseph, Cecillia M.; Phillips, Donald A.

    1991-01-01

    Alfalfa (Medicago sativa L.) releases different flavonoids from seeds and roots. Imbibing seeds discharge 3′,4′,5,7-substituted flavonoids; roots exude 5-deoxy molecules. Many, but not all, of these flavonoids induce nodulation (nod) genes in Rhizobium meliloti. The dominant flavonoid released from alfalfa seeds is identified here as quercetin-3-O-galactoside, a molecule that does not induce nod genes. Low concentrations (1-10 micromolar) of this compound, as well as luteolin-7-O-glucoside, another major flavonoid released from germinating seeds, and the aglycones, quercetin and luteolin, increase growth rate of R. meliloti in a defined minimal medium. Tests show that the 5,7-dihydroxyl substitution pattern on those molecules was primarily responsible for the growth effect, thus explaining how 5-deoxy flavonoids in root exudates fail to enhance growth of R. meliloti. Luteolin increases growth by a mechanism separate from its capacity to induce rhizobial nod genes, because it still enhanced growth rate of R. meliloti lacking functional copies of the three known nodD genes. Quercetin and luteolin also increased growth rate of Pseudomonas putida. They had no effect on growth rate of Bacillus subtilis or Agrobacterium tumefaciens, but they slowed growth of two fungal pathogens of alfalfa. These results suggest that alfalfa can create ecochemical zones for controlling soil microbes by releasing structurally different flavonoids from seeds and roots. PMID:16668056

  14. The sustainable growth rate: the elephant in the room of deficit reduction.

    PubMed

    Perez, Ken

    2012-05-01

    The sustainable growth rate (SGR) is a formulaic approach intended to restrain the growth of Medicare spending on physician services. Permanently replacing the SGR will cost $300 billion to $400 billion. Ten years of congressional overrides have contributed to higher Medicare spending on physician services. The absence of a replacement for the SGR leaves the federal government with a significant budget deficit exposure.

  15. Landscape scale measures of steelhead (Oncorhynchus mykiss) bioenergetic growth rate potential in Lake Michigan and comparison with angler catch rates

    USGS Publications Warehouse

    Hook, T.O.; Rutherford, E.S.; Brines, Shannon J.; Geddes, C.A.; Mason, D.M.; Schwab, D.J.; Fleischer, G.W.

    2004-01-01

    The relative quality of a habitat can influence fish consumption, growth, mortality, and production. In order to quantify habitat quality, several authors have combined bioenergetic and foraging models to generate spatially explicit estimates of fish growth rate potential (GRP). However, the capacity of GRP to reflect the spatial distributions of fishes over large areas has not been fully evaluated. We generated landscape scale estimates of steelhead (Oncorhynchus mykiss) GRP throughout Lake Michigan for 1994-1996, and used these estimates to test the hypotheses that GRP is a good predictor of spatial patterns of steelhead catch rates. We used surface temperatures (measured with AVHRR satellite imagery) and acoustically measured steelhead prey densities (alewife, Alosa pseudoharengus) as inputs for the GRP model. Our analyses demonstrate that potential steelhead growth rates in Lake Michigan are highly variable in both space and time. Steelhead GRP tended to increase with latitude, and mean GRP was much higher during September 1995, compared to 1994 and 1996. In addition, our study suggests that landscape scale measures of GRP are not good predictors of steelhead catch rates throughout Lake Michigan, but may provide an index of interannual variation in system-wide habitat quality.

  16. A hyperspectral image can predict tropical tree growth rates in single-species stands.

    PubMed

    Caughlin, T Trevor; Graves, Sarah J; Asner, Gregory P; van Breugel, Michiel; Hall, Jefferson S; Martin, Roberta E; Ashton, Mark S; Bohlman, Stephanie A

    2016-12-01

    Remote sensing is increasingly needed to meet the critical demand for estimates of forest structure and composition at landscape to continental scales. Hyperspectral images can detect tree canopy properties, including species identity, leaf chemistry and disease. Tree growth rates are related to these measurable canopy properties but whether growth can be directly predicted from hyperspectral data remains unknown. We used a single hyperspectral image and light detection and ranging-derived elevation to predict growth rates for 20 tropical tree species planted in experimental plots. We asked whether a consistent relationship between spectral data and growth rates exists across all species and which spectral regions, associated with different canopy chemical and structural properties, are important for predicting growth rates. We found that a linear combination of narrowband indices and elevation is correlated with standardized growth rates across all 20 tree species (R(2)  = 53.70%). Although wavelengths from the entire visible-to-shortwave infrared spectrum were involved in our analysis, results point to relatively greater importance of visible and near-infrared regions for relating canopy reflectance to tree growth data. Overall, we demonstrate the potential for hyperspectral data to quantify tree demography over a much larger area than possible with field-based methods in forest inventory plots.

  17. Plate Thickness Variation Effects on Crack Growth Rates in 7050-T7451 Alloy Thick Plate

    NASA Astrophysics Data System (ADS)

    Schubbe, Joel J.

    2011-02-01

    A study has been accomplished to characterize the fatigue crack growth rates and mechanisms in thick plate (16.51 cm) commercial grade 7050-T7451 aluminum plate in the L-S orientation. Examination of the effects of potential property gradients in the plate material was accomplished through hardness measurements along the short transverse direction and with compact tension tests. Tests exhibited a distinct trend of reduced center plane hardness in the plates. Compact tension specimens and the compliance method were used to determine crack growth rates for specimens machined from the t/4 and t/2 planar locations and oriented for L-S crack growth. Crack growth rate data (long crack) from the tests highlighted significant growth rate differences between the t/4 and t/2 locations. No significant effect of R-ratio was observed in the 0.05-0.3 range tested. Additionally, crack front splitting was noted in all specimens to differing degrees with data showing significant retardation of growth rate curves for the L-S orientation above 13 MPa √m in the center plane, and 10 MPa √m at quarter plane, where branching and splitting parallel to the load axis are dominant growth mechanisms.

  18. Phylogenetic, functional, and structural components of variation in bone growth rate of amniotes.

    PubMed

    Cubo, Jorge; Legendre, Pierre; de Ricqlès, Armand; Montes, Laëtitia; de Margerie, Emmanuel; Castanet, Jacques; Desdevises, Yves

    2008-01-01

    The biological features observed in every living organism are the outcome of three sets of factors: historical (inherited by homology), functional (biological adaptation), and structural (properties inherent to the materials with which organs are constructed, and the morphogenetic rules by which they grow). Integrating them should bring satisfactory causal explanations of empirical data. However, little progress has been accomplished in practice toward this goal, because a methodologically efficient tool was lacking. Here we use a new statistical method of variation partitioning to analyze bone growth in amniotes. (1) Historical component. The variation of bone growth rates contains a significant phylogenetic signal, suggesting that the observed patterns are partly the outcome of shared ancestry. (2) Functional causation. High growth rates, although energy costly, may be adaptive (i.e., they may increase survival rates) in taxa showing short growth periods (e.g., birds). In ectothermic amniotes, low resting metabolic rates may limit the maximum possible growth rates. (3) Structural constraint. Whereas soft tissues grow through a multiplicative process, growth of mineralized tissues is accretionary (additive, i.e., mineralization fronts occur only at free surfaces). Bone growth of many amniotes partially circumvents this constraint: it is achieved not only at the external surface of the bone shaft, but also within cavities included in the bone cortex as it grows centrifugally. Our approach contributes to the unification of historicism, functionalism, and structuralism toward a more integrated evolutionary biology.

  19. Computation of Growth Rates of Random Sequences with Multi-step Memory

    NASA Astrophysics Data System (ADS)

    Zhang, Chenfei; Lan, Yueheng

    2013-02-01

    We extend the generating function approach to the computation of growth rate of random Fibonacci sequences with long memory. Functional iteration equations are obtained and its general form is conjectured and proved, based on which an asymptotic representation of the growth rate is obtained. The validity of both the derived and the conjectured formula are verified upon comparison with Monte Carlo simulation. A numerical scheme of the functional iteration is designed and implemented successfully.

  20. Fibrin biomatrix-conjugated platelet-derived growth factor AB accelerates wound healing in severe thermal injury.

    PubMed

    Mittermayr, Rainer; Branski, Ludwik; Moritz, Martina; Jeschke, Marc G; Herndon, David N; Traber, Daniel; Schense, Jason; Gampfer, Jörg; Goppelt, Andreas; Redl, Heinz

    2016-05-01

    Controlled delivery of growth factors from biodegradable biomatrices could accelerate and improve impaired wound healing. The study aim was to determine whether platelet-derived growth factor AB (PDGF.AB) with a transglutaminase (TG) crosslinking substrate site released from a fibrin biomatrix improves wound healing in severe thermal injury. The binding and release kinetics of TG-PDGF.AB were determined in vitro. Third-degree contact burns (dorsum of Yorkshire pigs) underwent epifascial necrosectomy 24 h post-burn. Wound sites were covered with autologous meshed (3:1) split-thickness skin autografts and either secured with staples or attached with sprayed fibrin sealant (FS; n = 8/group). TG-PDGF.AB binds to the fibrin biomatrix using the TG activity of factor XIIIa, and is subsequently released through enzymatic cleavage. Three doses of TG-PDGF.AB in FS (100 ng, 1 µg and 11 µg/ml FS) were tested. TG-PDGF.AB was bound to the fibrin biomatrix as evidenced by western blot analysis and subsequently released by enzymatic cleavage. A significantly accelerated and improved wound healing was achieved using sprayed FS containing TG-PDGF.AB compared to staples alone. Low concentrations (100 ng-1 µg TG-PDGF.AB/ml final FS clot) demonstrated to be sufficient to attain a nearly complete closure of mesh interstices 14 days after grafting. TG-PDGF.AB incorporated in FS via a specific binding technology was shown to be effective in grafted third-degree burn wounds. The adhesive properties of the fibrin matrix in conjunction with the prolonged growth factor stimulus enabled by this binding technology could be favourable in many pathological situations associated with wound-healing disturbances. Copyright © 2013 John Wiley & Sons, Ltd.

  1. Dual-rate-loop control based on disturbance observer of angular acceleration for a three-axis aerial inertially stabilized platform.

    PubMed

    Zhou, Xiangyang; Jia, Yuan; Zhao, Qiang; Cai, Tongtong

    2016-07-01

    This paper presents a dual-rate-loop control method based on disturbance observer (DOB) of angular acceleration for a three-axis ISP for aerial remote sensing applications, by which the control accuracy and stabilization of ISP are improved obviously. In stabilization loop of ISP, a dual-rate-loop strategy is designed through constituting inner rate loop and the outer rate loop, by which the capability of disturbance rejection is advanced. Further, a DOB-based on angular acceleration is proposed to attenuate the influences of the main disturbances on stabilization accuracy. Particularly, an information fusion method is suggested to obtain accurate angular acceleration in DOB design, which is the key for the disturbance compensation. The proposed methods are theoretically analyzed and experimentally validated to illustrate the effectiveness.

  2. Prediction of microbial growth rate versus biomass yield by a metabolic network with kinetic parameters.

    PubMed

    Adadi, Roi; Volkmer, Benjamin; Milo, Ron; Heinemann, Matthias; Shlomi, Tomer

    2012-01-01

    Identifying the factors that determine microbial growth rate under various environmental and genetic conditions is a major challenge of systems biology. While current genome-scale metabolic modeling approaches enable us to successfully predict a variety of metabolic phenotypes, including maximal biomass yield, the prediction of actual growth rate is a long standing goal. This gap stems from strictly relying on data regarding reaction stoichiometry and directionality, without accounting for enzyme kinetic considerations. Here we present a novel metabolic network-based approach, MetabOlic Modeling with ENzyme kineTics (MOMENT), which predicts metabolic flux rate and growth rate by utilizing prior data on enzyme turnover rates and enzyme molecular weights, without requiring measurements of nutrient uptake rates. The method is based on an identified design principle of metabolism in which enzymes catalyzing high flux reactions across different media tend to be more efficient in terms of having higher turnover numbers. Extending upon previous attempts to utilize kinetic data in genome-scale metabolic modeling, our approach takes into account the requirement for specific enzyme concentrations for catalyzing predicted metabolic flux rates, considering isozymes, protein complexes, and multi-functional enzymes. MOMENT is shown to significantly improve the prediction accuracy of various metabolic phenotypes in E. coli, including intracellular flux rates and changes in gene expression levels under different growth rates. Most importantly, MOMENT is shown to predict growth rates of E. coli under a diverse set of media that are correlated with experimental measurements, markedly improving upon existing state-of-the art stoichiometric modeling approaches. These results support the view that a physiological bound on cellular enzyme concentrations is a key factor that determines microbial growth rate.

  3. Rate of head circumference growth as a function of autism diagnosis and history of autistic regression.

    PubMed

    Webb, Sara Jane; Nalty, Theresa; Munson, Jeff; Brock, Catherine; Abbott, Robert; Dawson, Geraldine

    2007-10-01

    Several reports indicate that autism spectrum disorder is associated with increased rate of head growth in early childhood. Increased rate of growth may index aberrant processes during early development, may precede the onset of symptoms, and may predict severity of the disease course. We examined rate of change in occipitofrontal circumference measurements (abstracted from medical records) in 28 boys with autism spectrum disorder and in 8 boys with developmental delay without autism from birth to age 36 months. Only children who had more than 3 occipitofrontal circumference measurements available during this age period were included. All data were converted to z scores based on the Centers for Disease Control and Prevention norms. Rate of growth from birth to age 36 months was statistically significantly higher for the autism spectrum disorder group than the developmental delay group, with children with autism spectrum disorder showing a statistically significant increase in occipitofrontal circumference relative to norms between 7 and 10 months; this group difference in rate of growth was more robust when height was used as a covariate. Rate of growth was not found to be different for children with autism spectrum disorder whose parents reported a history of loss of skills (regression) vs those whose parents reported early onset of autism symptoms. Findings from this study suggest that the aberrant growth is present in the first year of life and precedes the onset and diagnosis in children with autism spectrum disorder with and without a history of autistic regression.

  4. The Modellers' Halting Foray into Ecological Theory: Or, What is This Thing Called 'Growth Rate'?

    PubMed

    Deveau, Michael; Karsten, Richard; Teismann, Holger

    2015-06-01

    This discussion paper describes the attempt of an imagined group of non-ecologists ("Modellers") to determine the population growth rate from field data. The Modellers wrestle with the multiple definitions of the growth rate available in the literature and the fact that, in their modelling, it appears to be drastically model-dependent, which seems to throw into question the very concept itself. Specifically, they observe that six representative models used to capture the data produce growth-rate values, which differ significantly. Almost ready to concede that the problem they set for themselves is ill-posed, they arrive at an alternative point of view that not only preserves the identity of the concept of the growth rate, but also helps discriminate between competing models for capturing the data. This is accomplished by assessing how robustly a given model is able to generate growth-rate values from randomized time-series data. This leads to the proposal of an iterative approach to ecological modelling in which the definition of theoretical concepts (such as the growth rate) and model selection complement each other. The paper is based on high-quality field data of mites on apple trees and may be called a "data-driven opinion piece".

  5. Growth rate of a deep-sea coral using sup 210 Pb and other isotopes

    SciTech Connect

    Druffel, E.R.M.; King, L.I.; Belastock, R.A.; Buesseler, K.O. )

    1990-05-01

    A deep-sea coral was studied to determine its growth rate and to reconstruct time histories of isotope distributions in the deep ocean. The specimen was collected at a depth of 600 m off Little Bahama Banks using the Deep Submergence Vehicle (DSV) Alvin. The growth rate of the calcitic coral trunk was determined using excess {sup 210}Pb measured in concentric bands. Excess {sup 210}Pb was found in the outer half of the coral's radius, and a growth rate of 0.11 {plus minus} 0.02 mm/a is calculated. Assuming a constant growth rate during formation of the entire trunk, an age of 180 {plus minus} 40 a is estimated for the coral. The decrease observed in radiocarbon activities measured on the same bands (Griffin and Druffel, 1989) concurred with the growth rate estimated from excess {sup 210}Pb activity. {sup 239,240}Pu activities measured by mass spectrometry were also detected in the outer two bands of the coral, as expected from the {sup 210}Pb chronology. Stable oxygen and carbon isotopes measured in samples collected by a variety of techniques are positively correlated. This is evidence of a variable kinetic isotope effect most likely caused by variations in the skeletal growth rate. Long-lived corals such as this specimen have the potential for serving as integrators of seawater chemistry in the deep-sea over several century timescales.

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

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  7. Anisotropic interpolation method of silicon carbide oxidation growth rates for three-dimensional simulation

    NASA Astrophysics Data System (ADS)

    Šimonka, Vito; Nawratil, Georg; Hössinger, Andreas; Weinbub, Josef; Selberherr, Siegfried

    2017-02-01

    We investigate anisotropical and geometrical aspects of hexagonal structures of Silicon Carbide and propose a direction dependent interpolation method for oxidation growth rates. We compute three-dimensional oxidation rates and perform one-, two-, and three-dimensional simulations for 4H- and 6H-Silicon Carbide thermal oxidation. The rates of oxidation are computed according to the four known growth rate values for the Si- (0 0 0 1) , a- (1 1 2 bar 0) , m- (1 1 bar 0 0) , and C-face (0 0 0 1 bar) . The simulations are based on the proposed interpolation method together with available thermal oxidation models. We additionally analyze the temperature dependence of Silicon Carbide oxidation rates for different crystal faces using Arrhenius plots. The proposed interpolation method is an essential step towards highly accurate three-dimensional oxide growth simulations which help to better understand the anisotropic nature and oxidation mechanism of Silicon Carbide.

  8. Rapid, bilateral changes in growth rate and curvature during gravitropism of cucumber hypocotyls: implications for mechanism of growth control

    NASA Technical Reports Server (NTRS)

    Cosgrove, D. J.

    1990-01-01

    The growth response of etiolated cucumber (Cucumis sativus L.) hypocotyls to gravitropic stimulation was examined by means of time-lapse photography and high-resolution analysis of surface expansion and curvature. In comparison with video analysis, the technique described here has five- to 20-fold better resolution; moreover, the mathematical fitting method (cubic splines) allows direct estimation of local and integrated curvature. After switching seedlings from a vertical to horizontal position, both upper and lower surfaces of the stem reacted after a lag of about 11 min with a two- to three-fold increase in surface expansion rate on the lower side and a cessation of expansion, or slight compression, on the upper surface. This growth asymmetry was initiated simultaneously along the length of the hypocotyl, on both upper and lower surfaces, and did not migrate basipetally from the apex. Later stages in the gravitropic response involved a complex reversal of the growth asymmetry, with the net result being a basipetal migration of the curved region. This secondary growth reversal may reflect oscillatory and/or self-regulatory behaviour of growing cells. With some qualifications, the kinetics and pattern of growth response are consistent with a mechanism involving hormone redistribution, although they do not prove such a mechanism. The growth kinetics require a growth mechanism which can be stimulated by two- to three-fold or completely inhibited within a few minutes.

  9. Effects of climate change on plant population growth rate and community composition change.

    PubMed

    Chang, Xiao-Yu; Chen, Bao-Ming; Liu, Gang; Zhou, Ting; Jia, Xiao-Rong; Peng, Shao-Lin

    2015-01-01

    The impacts of climate change on forest community composition are still not well known. Although directional trends in climate change and community composition change were reported in recent years, further quantitative analyses are urgently needed. Previous studies focused on measuring population growth rates in a single time period, neglecting the development of the populations. Here we aimed to compose a method for calculating the community composition change, and to testify the impacts of climate change on community composition change within a relatively short period (several decades) based on long-term monitoring data from two plots-Dinghushan Biosphere Reserve, China (DBR) and Barro Colorado Island, Panama (BCI)-that are located in tropical and subtropical regions. We proposed a relatively more concise index, Slnλ, which refers to an overall population growth rate based on the dominant species in a community. The results indicated that the population growth rate of a majority of populations has decreased over the past few decades. This decrease was mainly caused by population development. The increasing temperature had a positive effect on population growth rates and community change rates. Our results promote understanding and explaining variations in population growth rates and community composition rates, and are helpful to predict population dynamics and population responses to climate change.

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

    SciTech Connect

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

    1991-12-01

    Concentrations of phytoplankton and NO{sub 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 {approximately}0.7 d{sup {minus}1} or 1 biomass doubling d{sup {minus}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.

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

    USGS Publications Warehouse

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

    2010-01-01

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

  12. A model for predicting crack growth rate for mixed mode fracture under biaxial loads

    NASA Astrophysics Data System (ADS)

    Shliannikov, V. N.; Braude, N. Z.

    1992-09-01

    A model for predicting the crack growth rate of an initially angled crack under biaxial loads of arbitrary direction is suggested. The model is based on a combination of both the Manson-Coffin equation for low cycle fatigue and the Paris equation for fatigue crack propagation. The model takes into consideration the change in material plastic properties in the region around the crack tip due to the stress state, together with the initial orientation of the crack and also its trajectory of growth. Predictions of crack growth rate for any mixed mode fracture is based on the results of uniaxial tension experiments.

  13. 7075-T6 and 2024-T351 Aluminum Alloy Fatigue Crack Growth Rate Data

    NASA Technical Reports Server (NTRS)

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

    2005-01-01

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

  14. Effects of Sled Towing on Peak Force, the Rate of Force Development and Sprint Performance During the Acceleration Phase.

    PubMed

    Martínez-Valencia, María Asunción; Romero-Arenas, Salvador; Elvira, José L L; González-Ravé, José María; Navarro-Valdivielso, Fernando; Alcaraz, Pedro E

    2015-06-27

    Resisted sprint training is believed to increase strength specific to sprinting. Therefore, the knowledge of force output in these tasks is essential. The aim of this study was to analyze the effect of sled towing (10%, 15% and 20% of body mass (Bm)) on sprint performance and force production during the acceleration phase. Twenty-three young experienced sprinters (17 men and 6 women; men = 17.9 ± 3.3 years, 1.79 ± 0.06 m and 69.4 ± 6.1 kg; women = 17.2 ± 1.7 years, 1.65 ± 0.04 m and 56.6 ± 2.3 kg) performed four 30 m sprints from a crouch start. Sprint times in 20 and 30 m sprint, peak force (Fpeak), a peak rate of force development (RFDpeak) and time to RFD (TRFD) in first step were recorded. Repeated-measures ANOVA showed significant increases (p ≤ 0.001) in sprint times (20 and 30 m sprint) for each resisted condition as compared to the unloaded condition. The RFDpeak increased significantly when a load increased (3129.4 ± 894.6 N·s-1, p ≤ 0.05 and 3892.4 ± 1377.9 N·s-1, p ≤ 0.01). Otherwise, no significant increases were found in Fpeak and TRFD. The RFD determines the force that can be generated in the early phase of muscle contraction, and it has been considered a factor that influences performance of force-velocity tasks. The use of a load up to 20% Bm might provide a training stimulus in young sprinters to improve the RFDpeak during the sprint start, and thus, early acceleration.

  15. Effects of Sled Towing on Peak Force, the Rate of Force Development and Sprint Performance During the Acceleration Phase

    PubMed Central

    Martínez-Valencia, María Asunción; Romero-Arenas, Salvador; Elvira, José L.L.; González-Ravé, José María; Navarro-Valdivielso, Fernando; Alcaraz, Pedro E.

    2015-01-01

    Resisted sprint training is believed to increase strength specific to sprinting. Therefore, the knowledge of force output in these tasks is essential. The aim of this study was to analyze the effect of sled towing (10%, 15% and 20% of body mass (Bm)) on sprint performance and force production during the acceleration phase. Twenty-three young experienced sprinters (17 men and 6 women; men = 17.9 ± 3.3 years, 1.79 ± 0.06 m and 69.4 ± 6.1 kg; women = 17.2 ± 1.7 years, 1.65 ± 0.04 m and 56.6 ± 2.3 kg) performed four 30 m sprints from a crouch start. Sprint times in 20 and 30 m sprint, peak force (Fpeak), a peak rate of force development (RFDpeak) and time to RFD (TRFD) in first step were recorded. Repeated-measures ANOVA showed significant increases (p ≤ 0.001) in sprint times (20 and 30 m sprint) for each resisted condition as compared to the unloaded condition. The RFDpeak increased significantly when a load increased (3129.4 ± 894.6 N·s−1, p ≤ 0.05 and 3892.4 ± 1377.9 N·s−1, p ≤ 0.01). Otherwise, no significant increases were found in Fpeak and TRFD. The RFD determines the force that can be generated in the early phase of muscle contraction, and it has been considered a factor that influences performance of force-velocity tasks. The use of a load up to 20% Bm might provide a training stimulus in young sprinters to improve the RFDpeak during the sprint start, and thus, early acceleration. PMID:26240657

  16. Two-Body Orbit Expansion Due to Time-Dependent Relative Acceleration Rate of the Cosmological Scale Factor

    NASA Astrophysics Data System (ADS)

    Iorio, Lorenzo

    2014-01-01

    By phenomenologically assuming a slow temporal variation of the percent acceleration rate S̈S -1 of the cosmic scale factor S(t), it is shown that the orbit of a local binary undergoes a secular expansion. To first order in the power expansion of S̈S -1 around the present epoch t0, a non-vanishing shift per orbit (Δr) of the two-body relative distance r occurs for eccentric trajectories. A general relativistic expression, which turns out to be cubic in the Hubble parameter H0 at the present epoch, is explicitly calculated for it in the case of matter-dominated epochs with Dark Energy. For a highly eccentric Oort comet orbit with period Pb ≈ 31 Myr, the general relativistic distance shift per orbit turns out to be of the order of (Δr) ≈ 70 km. For the Large Magellanic Cloud, assumed on a bound elliptic orbit around the Milky Way, the shift per orbit is of the order of (Δr) ≈ 2-4 pc. Our result has a general validity since it holds in any cosmological model admitting the Hubble law and a slowly varying S̈S-1(t). More generally, it is valid for an arbitrary Hooke-like extra-acceleration whose "elastic" parameter κ is slowly time-dependent, irrespectively of the physical mechanism which may lead to it. The coefficient κ1 of the first-order term of the power expansion of κ(t) can be preliminarily constrained in a model-independent way down to a κ1 ≤ 2 x 10-13 year-3 level from latest Solar System's planetary observations. The radial velocities of the double lined spectroscopic binary ALPHA Cen AB yield κ1 ≤ 10-8 year-3.

  17. Mimosoid legume plastome evolution: IR expansion, tandem repeat expansions, and accelerated rate of evolution in clpP.

    PubMed

    Dugas, Diana V; Hernandez, David; Koenen, Erik J M; Schwarz, Erika; Straub, Shannon; Hughes, Colin E; Jansen, Robert K; Nageswara-Rao, Madhugiri; Staats, Martijn; Trujillo, Joshua T; Hajrah, Nahid H; Alharbi, Njud S; Al-Malki, Abdulrahman L; Sabir, Jamal S M; Bailey, C Donovan

    2015-11-23

    The Leguminosae has emerged as a model for studying angiosperm plastome evolution because of its striking diversity of structural rearrangements and sequence variation. However, most of what is known about legume plastomes comes from few genera representing a subset of lineages in subfamily Papilionoideae. We investigate plastome evolution in subfamily Mimosoideae based on two newly sequenced plastomes (Inga and Leucaena) and two recently published plastomes (Acacia and Prosopis), and discuss the results in the context of other legume and rosid plastid genomes. Mimosoid plastomes have a typical angiosperm gene content and general organization as well as a generally slow rate of protein coding gene evolution, but they are the largest known among legumes. The increased length results from tandem repeat expansions and an unusual 13 kb IR-SSC boundary shift in Acacia and Inga. Mimosoid plastomes harbor additional interesting features, including loss of clpP intron1 in Inga, accelerated rates of evolution in clpP for Acacia and Inga, and dN/dS ratios consistent with neutral and positive selection for several genes. These new plastomes and results provide important resources for legume comparative genomics, plant breeding, and plastid genetic engineering, while shedding further light on the complexity of plastome evolution in legumes and angiosperms.

  18. Stability and chaotic dynamics of a rate gyro with feedback control under uncertain vehicle spin and acceleration

    NASA Astrophysics Data System (ADS)

    Chen, Heng-Hui

    2004-06-01

    An analysis of stability and chaotic dynamics is presented by a single-axis rate gyro subjected to linear feedback control loops. This rate gyro is supposed to be mounted on a space vehicle which undergoes an uncertain angular velocity ωZ( t) around its spin axis. And simultaneously acceleration ω˙X(t) occurs with respect to the output axis. The necessary and sufficient conditions of stability for the autonomous case, whose vehicle undergoes a steady rotation, were provided by Routh-Hurwitz theory. Also, the degeneracy conditions of the non-hyperbolic point were derived and the dynamics of the resulting system on the center manifold near the double-zero degenerate point by using center manifold and normal form methods were examined. The stability of the non-linear non-autonomous system was investigated by Liapunov stability and instability theorems. As the electrical time constant is much smaller than the mechanical time constant, the singularly perturbed system can be obtained by the singular perturbation theory. The Liapunov stability of this system by studying the reduced and boundary-layer systems was also analyzed. Numerical simulations were performed to verify the analytical results. The stable regions of the autonomous system were obtained in parametric diagrams. For the non-autonomous case in which ωZ( t) oscillates near boundary of stability, periodic, quasiperiodic and chaotic motions were demonstrated by using time history, phase plane and Poincaré maps.

  19. Mimosoid legume plastome evolution: IR expansion, tandem repeat expansions, and accelerated rate of evolution in clpP

    PubMed Central

    Dugas, Diana V.; Hernandez, David; Koenen, Erik J.M.; Schwarz, Erika; Straub, Shannon; Hughes, Colin E.; Jansen, Robert K.; Nageswara-Rao, Madhugiri; Staats, Martijn; Trujillo, Joshua T.; Hajrah, Nahid H.; Alharbi, Njud S.; Al-Malki, Abdulrahman L.; Sabir, Jamal S. M.; Bailey, C. Donovan

    2015-01-01

    The Leguminosae has emerged as a model for studying angiosperm plastome evolution because of its striking diversity of structural rearrangements and sequence variation. However, most of what is known about legume plastomes comes from few genera representing a subset of lineages in subfamily Papilionoideae. We investigate plastome evolution in subfamily Mimosoideae based on two newly sequenced plastomes (Inga and Leucaena) and two recently published plastomes (Acacia and Prosopis), and discuss the results in the context of other legume and rosid plastid genomes. Mimosoid plastomes have a typical angiosperm gene content and general organization as well as a generally slow rate of protein coding gene evolution, but they are the largest known among legumes. The increased length results from tandem repeat expansions and an unusual 13 kb IR-SSC boundary shift in Acacia and Inga. Mimosoid plastomes harbor additional interesting features, including loss of clpP intron1 in Inga, accelerated rates of evolution in clpP for Acacia and Inga, and dN/dS ratios consistent with neutral and positive selection for several genes. These new plastomes and results provide important resources for legume comparative genomics, plant breeding, and plastid genetic engineering, while shedding further light on the complexity of plastome evolution in legumes and angiosperms. PMID:26592928

  20. Quantitative Physiology of Saccharomyces cerevisiae at Near-Zero Specific Growth Rates

    PubMed Central

    Boender, Léonie G. M.; de Hulster, Erik A. F.; van Maris, Antonius J. A.; Daran-Lapujade, Pascale A. S.; Pronk, Jack T.

    2009-01-01

    Growth at near-zero specific growth rates is a largely unexplored area of yeast physiology. To investigate the physiology of Saccharomyces cerevisiae under these conditions, the effluent removal pipe of anaerobic, glucose-limited chemostat culture (dilution rate, 0.025 h−1) was fitted with a 0.22-μm-pore-size polypropylene filter unit. This setup enabled prolonged cultivation with complete cell retention. After 22 days of cultivation, specific growth rates had decreased below 0.001 h−1 (doubling time of >700 h). Over this period, viability of the retentostat cultures decreased to ca. 80%. The viable biomass concentration in the retentostats could be accurately predicted by a maintenance coefficient of 0.50 mmol of glucose g−1 of biomass h−1 calculated from anaerobic, glucose-limited chemostat cultures grown at dilution rates of 0.025 to 0.20 h−1. This indicated that, in contrast to the situation in several prokaryotes, maintenance energy requirements in S. cerevisiae do not substantially change at near-zero specific growth rates. After 22 days of retentostat cultivation, glucose metabolism was predominantly geared toward alcoholic fermentation to meet maintenance energy requirements. The strict correlation between glycerol production and biomass formation observed at higher specific growth rates was not maintained at the near-zero growth rates reached in the retentostat cultures. In addition to glycerol, the organic acids acetate, d-lactate, and succinate were produced at low rates during prolonged retentostat cultivation. This study identifies robustness and by-product formation as key issues in attempts to uncouple growth and product formation in S. cerevisiae. PMID:19592533

  1. Quantitative description for the growth rate of self-induced GaN nanowires

    NASA Astrophysics Data System (ADS)

    Consonni, V.; Dubrovskii, V. G.; Trampert, A.; Geelhaar, L.; Riechert, H.

    2012-04-01

    We determine with high precision the growth rate of self-induced GaN nanowires grown by molecular beam epitaxy under various conditions from scanning electron micrographs by taking into account in situ measurements of the initial incubation time, which is needed before the nanowire growth starts. In order to quantitatively describe the dependence of the growth rate on growth time, gallium flux, and growth temperature, we develop a detailed theoretical model of diffusion-induced nanowire growth specifically for the self-induced approach, i.e., without any droplet at the nanowire top. The theoretical fits are in excellent agreement with the experimental data and allow us to deduce important kinetic parameters of the self-induced GaN nanowire growth. The gallium adatom effective diffusion length on the nanowire sidewalls composed of m-plane facets is only 45 nm, which is consistent with our experimental finding that the growth rate initially decreases drastically as the contribution from the adatoms on the planar substrate surface rapidly vanishes. In contrast, the gallium adatom effective diffusion length on the amorphous silicon nitride substrate surface reaches about 100 nm. Furthermore, the nucleation energy on the nanowire sidewalls is found to be 5.44 eV and is larger than on their top facet accounting for the nanowire elongation.

  2. Trophic interactions and population growth rates: describing patterns and identifying mechanisms.

    PubMed Central

    Hudson, Peter J; Dobson, Andy P; Cattadori, Isabella M; Newborn, David; Haydon, Dan T; Shaw, Darren J; Benton, Tim G; Grenfell, Bryan T

    2002-01-01

    While the concept of population growth rate has been of central importance in the development of the theory of population dynamics, few empirical studies consider the intrinsic growth rate in detail, let alone how it may vary within and between populations of the same species. In an attempt to link theory with data we take two approaches. First, we address the question 'what growth rate patterns does theory predict we should see in time-series?' The models make a number of predictions, which in general are supported by a comparative study between time-series of harvesting data from 352 red grouse populations. Variations in growth rate between grouse populations were associated with factors that reflected the quality and availability of the main food plant of the grouse. However, while these results support predictions from theory, they provide no clear insight into the mechanisms influencing reductions in population growth rate and regulation. In the second part of the paper, we consider the results of experiments, first at the individual level and then at the population level, to identify the important mechanisms influencing changes in individual productivity and population growth rate. The parasitic nematode Trichostrongylus tenuis is found to have an important influence on productivity, and when incorporated into models with their patterns of distribution between individuals has a destabilizing effect and generates negative growth rates. The hypothesis that negative growth rates at the population level were caused by parasites was demonstrated by a replicated population level experiment. With a sound and tested model framework we then explore the interaction with other natural enemies and show that in general they tend to stabilize variations in growth rate. Interestingly, the models show selective predators that remove heavily infected individuals can release the grouse from parasite-induced regulation and allow equilibrium populations to rise. By contrast, a

  3. Accelerating the dynamics of infrequent events: Combining hyperdynamics and parallel replica dynamics to treat epitaxial layer growth

    SciTech Connect

    Voter, A.F.; Germann, T.C.

    1998-12-31

    During the growth of a surface, morphology-controlling diffusion events occur over time scales that far exceed those accessible to molecular dynamics (MD) simulation. Kinetic Monte Carlo offers a way to reach much longer times, but suffers from the fact that the dynamics are correct only if all possible diffusion events are specified in advance. This is difficult due to the concerted nature of many of the recently discovered surface diffusion mechanisms and the complex configurations that arise during real growth. Here the authors describe two new approaches for this type of problem. The first, hyperdynamics, is an accelerated MD method, in which the trajectory is run on a modified potential energy surface and time is accumulated as a statistical property. Relative to regular MD, hyperdynamics can give computational gains of more than 10{sup 2}. The second method offers a way to parallelize the dynamics efficiently for systems too small for conventional parallel MD algorithms. Both methods exploit the infrequent-event nature of the diffusion process. After an introductory description of these methods, the authors present preliminary results from simulations combining the two approaches to reach near-millisecond time scales on systems relevant to epitaxial metal growth.

  4. Stress Ratio Effects on Crack Opening Loads and Crack Growth Rates in Aluminum Alloy 2024

    NASA Technical Reports Server (NTRS)

    Riddell, William T.; Piascik, Robert S.

    1998-01-01

    The effects of stress ratio (R) and crack opening behavior on fatigue crack growth rates (da/dN) for aluminum alloy (AA) 2024-T3 were investigated using constant-delta K testing, closure measurements, and fractography. Fatigue crack growth rates were obtained for a range of delta K and stress ratios. Results show that constant delta K fatigue crack growth for R ranging from near 0 to 1 is divided into three regions. In Region 1, at low R, da/dN increases with increasing R. In Region 2, at intermediate R, fatigue crack growth rates are relatively independent of R. In Region 3, at high R, further increases in da/dN are observed with increasing R.

  5. Effects of nutrients on specific growth rate of bacterioplankton in oligotrophic lake water cultures

    SciTech Connect

    Coveney, M.F.; Wetzel, R.G. )

    1992-01-01

    The effects of organic and inorganic nutrient additions on the specific growth rates of bacterioplankton in oligotrophic lake water cultures were investigated. Lake water was first passed through 0.8-{mu}m-pore-size filters (prescreening) to remove bacterivores and to minimize confounding effects of algae. Specific growth rates were calculated from changes in both bacterial cell numbers and biovolumes over 36 h. Gross specific growth rates in unmanipulated control samples were estimated through separate measurements of grazing losses by use of penicillin. The addition of mixed organic substrates alone to prescreened water did not significantly increase bacterioplankton specific growth rates. The addition of inorganic phosphorus alone s