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Sample records for accelerated growth rate

  1. The effects of accelerated growth rates and estrogen implants in prepubertal Holstein heifers on growth, feed efficiency, and blood parameters.

    PubMed

    Lammers, B P; Heinrichs, A J; Kensinger, R S

    1999-08-01

    Sixty-eight Holstein heifers were used to determine the effects of accelerated growth rates by increased nutrient intake and estrogen implants on feed efficiency, structural growth, and blood parameters in heifers between 19 and 39 wk of age. At the beginning of the treatment period, the heifers were assigned to one of four treatment groups by using a randomized complete block design in a 2 x 2 factorial arrangement. The treatments were standard growth rate (700 g/d), accelerated growth rate (1000 g/d), standard growth rate with an estradiol implant, and accelerated growth rate with an estradiol implant. All heifers received the same diet, but dry matter intake was adjusted weekly to achieve the target rate of gain. Accelerating heifer growth rates from 705 to 1007 g/d improved feed efficiency 5.1%, increased the rate of withers height, heart girth, and hip width growth 12, 27, and 27%, respectively, and body condition scores 0.25 points. Estradiol implants improved feed efficiency 2.4% and decreased the rate of withers height 6% and heart girth growth 3.5%. Increased nutrient intake and average daily gain depressed mean plasma growth hormone and urea nitrogen content 17 and 7%, respectively, while elevating insulin-like growth factor-1 levels by 10%. Estradiol implants increased mean plasma growth hormone content by 29% and insulin-like growth factor-1 levels by 17%, but decreased urea nitrogen content by 11%. Feeding prepubertal heifers for accelerated growth rates increased structural growth with a small increase in body condition, whereas estradiol implants improved feed efficiency and decreased the growth rate of withers height and heart girth without affecting the rate of hip width growth. PMID:10480101

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

    PubMed Central

    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

  3. 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

  4. Growth rates made easy.

    PubMed

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

    2014-01-01

    In the 1960s-1980s, determination of bacterial growth rates was an important tool in microbial genetics, biochemistry, molecular biology, and microbial physiology. The exciting technical developments of the 1990s and the 2000s eclipsed that tool; as a result, many investigators today lack experience with growth rate measurements. Recently, investigators in a number of areas have started to use measurements of bacterial growth rates for a variety of purposes. Those measurements have been greatly facilitated by the availability of microwell plate readers that permit the simultaneous measurements on up to 384 different cultures. Only the exponential (logarithmic) portions of the resulting growth curves are useful for determining growth rates, and manual determination of that portion and calculation of growth rates can be tedious for high-throughput purposes. Here, we introduce the program GrowthRates that uses plate reader output files to automatically determine the exponential portion of the curve and to automatically calculate the growth rate, the maximum culture density, and the duration of the growth lag phase. GrowthRates is freely available for Macintosh, Windows, and Linux. We discuss the effects of culture volume, the classical bacterial growth curve, and the differences between determinations in rich media and minimal (mineral salts) media. This protocol covers calibration of the plate reader, growth of culture inocula for both rich and minimal media, and experimental setup. As a guide to reliability, we report typical day-to-day variation in growth rates and variation within experiments with respect to position of wells within the plates. PMID:24170494

  5. 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.

  6. Myth Exposed: Academically Deficient Students Gain 2.3 Grade Equivalents in Only One Semester at a 96% Black Inner-City Community College in South Central Los Angeles Or Inner-City Academic Acceleration: How to Structure a Developmental Skills Program so that Black, Inner-City Students Accelerate Their Academic Growth Rate to a Rate 5.9 Times as Great as They Have Achieved in the Past.

    ERIC Educational Resources Information Center

    Wallace, Ruby; And Others

    The success of the Developmental Skills Program offered at Los Angeles Southwest College, a 96% black institution, is indicated by an average student grade equivalent gain of 2.3 years in one semester; a 5 year average accelerated academic growth rate that is 5.9 times the rate of academic growth black inner-city students have experienced in the…

  7. 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 curve models when change…

  8. Dinosaurian growth patterns and rapid avian growth rates.

    PubMed

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

    2001-07-26

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

  9. Accelerating the Rate of Astronomical Discovery

    NASA Astrophysics Data System (ADS)

    This meeting marks the the International Year of Astronomy by reviewing the extent to which astronomers are achieving the optimal rate of astronomical discovery. Can we identify and overcome the limits to progress? What steps can be taken to accelerate the rate of expansion of astronomical knowledge? What lessons can be learnt both from the recent and distant past? As the public announcements regarding the 2009 IYA have emphasized, new astronomical discoveries are currently being made at an extraordinary rate, while the invention of the telescope ushered in an equally momentous "golden age of discovery" 400 years ago. The meeting addresses a range of potential limits to progress-paradigmatic, technological, organizational, and political-examining each issue both from modern and historical perspectives, and drawing lessons to guide future progress. The program focusses on how astronomy actually progresses, using careful historical studies and real data, rather than anecdotes and folklore.

  10. Accelerated transport and growth with symmetrized dynamics

    NASA Astrophysics Data System (ADS)

    Merikoski, Juha

    2013-12-01

    In this paper we consider a model of accelerated dynamics with the rules modified from those of the recently proposed [Dong et al., Phys. Rev. Lett. 109, 130602 (2012), 10.1103/PhysRevLett.109.130602] accelerated exclusion process (AEP) such that particle-vacancy symmetry is restored to facilitate a mapping to a solid-on-solid growth model in 1+1 dimensions. In addition to kicking a particle ahead of the moving particle, as in the AEP, in our model another particle from behind is drawn, provided it is within the "distance of interaction" denoted by ℓmax. We call our model the doubly accelerated exclusion process (DAEP). We observe accelerated transport and interface growth and widening of the cluster size distribution for cluster sizes above ℓmax, when compared with the ordinary totally asymmetric exclusion process (TASEP). We also characterize the difference between the TASEP, AEP, and DAEP by computing a "staggered" order parameter, which reveals the local order in the steady state. This order in part explains the behavior of the particle current as a function of density. The differences of the steady states are also reflected by the behavior of the temporal and spatial correlation functions in the interface picture.

  11. Growth Rate and Turgor Pressure

    PubMed Central

    Green, Paul B.; Cummins, W. Raymond

    1974-01-01

    Because turgor pressure is regarded as the driving force for cell extension, any general theory of plant growth requires quantitative information on the relationship between steady irreversible growth rate and turgor pressure. To investigate contrasting views of this relation an automated apparatus was constructed which perfused both the outer and inner epidermis of a single coleoptile while its growth rate was continuously recorded. Turgor was altered abruptly by perfusing with solutions of varying tonicity. With specially grown rye coleoptiles the half-time of the osmo-elastic response was reduced to 2 minutes or less. After decay of this response, however, rate continued to change (so as to partially compensate the effects of the turgor shift in question) for 30 to 60 minutes. Only then could a steady rate be taken. A characterization of steady rate versus turgor covering five turgor values for a single coleoptile thus required many hours. The conclusions are as follows. (a) The change in steady rate, per unit change in turgor, was much greater +IAA than −IAA. (b) Both auxin and turgor act to reset an apparent stabilizing system whose presence is shown in the partial compensation of the initial response to turgor shifts. The above “extensibility” changes are operational only. They need not reflect changes in the immediate physical extensibility of the wall; they could reflect changes in a process acting on the wall. (c) The growth rate versus turgor relation shows some hysteresis. PMID:16658991

  12. 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.

  13. 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.

  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. 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.

  16. ON PARTICLE ACCELERATION RATE IN GAMMA-RAY BURST AFTERGLOWS

    SciTech Connect

    Sagi, Eran; Nakar, Ehud

    2012-04-10

    It is well known that collisionless shocks are major sites of particle acceleration in the universe, but the details of the acceleration process are still not well understood. The particle acceleration rate, which can shed light on the acceleration process, is rarely measured in astrophysical environments. Here, we use observations of gamma-ray burst (GRB) afterglows, which are weakly magnetized relativistic collisionless shocks in ion-electron plasma, to constrain the rate of particle acceleration in such shocks. We find, based on X-ray and GeV afterglows, an acceleration rate that is most likely very fast, approaching the Bohm limit, when the shock Lorentz factor is in the range of {Gamma} {approx} 10-100. In that case X-ray observations may be consistent with no amplification of the magnetic field in the shock upstream region. We examine the X-ray afterglow of GRB 060729, which is observed for 642 days showing a sharp decay in the flux starting about 400 days after the burst, when the shock Lorentz factor is {approx}5. We find that inability to accelerate X-ray-emitting electrons at late time provides a natural explanation for the sharp decay, and that also in that case acceleration must be rather fast, and cannot be more than a 100 times slower than the Bohm limit. We conclude that particle acceleration is most likely fast in GRB afterglows, at least as long as the blast wave is ultrarelativistic.

  17. Growth rate study of canavalin single crystals

    NASA Technical Reports Server (NTRS)

    Demattei, R. C.; Feigelson, R. S.

    1989-01-01

    The dependence on supersaturation of the growth rate of single crystals of the protein canavalin is studied. In the supersaturation ranges studied, the rate-limiting step for growth is best described by a screw dislocation mechanism associated with interface attachment kinetics. Using a ln-ln plot, the growth-rate data is found to fit a predictive relationship of the form G = 0.012 x the supersaturation to the 6.66, which, together with the solubility curves, allows the growth rate to be estimated under a variety of conditions.

  18. 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.

  19. 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.

  20. Particle acceleration during substorm growth and onset

    NASA Technical Reports Server (NTRS)

    Williams, D. J.; Mitchell, D. G.; Huang, C. Y.; Frank, L. A.; Russell, C. T.

    1990-01-01

    ISEE-1 observations of ion and electron energization made at 11 RE during a substorm event on April 2, 1978 are presented. An analysis of the dominant cross-tail current systems in this event (Mitchell et al., 1990) has made it possible to uniquely associate particle energization processes with the development and/or disruption of the cross-tail currents. It is found that significant ion acceleration occurs as the ions participate in serpentine cross-tail motion (Speiser, 1965), establishing the dominant plasma sheet current system just prior to onset. As this current disrupts, the magnetic field configuration dipolarizes and further ion energization and the bulk of the electron energization occurs. During dipolarization energization is due primarily to the inductive electric field, including betatron and Fermi acceleration processes.

  1. 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.

  2. 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.

  3. 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. PMID:26195108

  4. 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.

  5. Accelerated Molecular Dynamics studies of He Bubble Growth in Tungsten

    NASA Astrophysics Data System (ADS)

    Uberuaga, Blas; Sandoval, Luis; Perez, Danny; Voter, Arthur

    2015-11-01

    Understanding how materials respond to extreme environments is critical for predicting and improving performance. In materials such as tungsten exposed to plasmas for nuclear fusion applications, novel nanoscale fuzzes, comprised of tendrils of tungsten, form as a consequence of the implantation of He into the near surface. However, the detailed mechanisms that link He bubble formation to the ultimate development of fuzz are unclear. Molecular dynamics simulations provide insight into the He implantation process, but are necessarily performed at implantation rates that are orders of magnitudes faster than experiment. Here, using accelerated molecular dynamics methods, we examine the role of He implantation rates on the physical evolution of He bubbles in tungsten. We find that, as the He rate is reduced, new types of events involving the response of the tungsten matrix to the pressure in the bubble become competitive and change the overall evolution of the bubble as well as the subsequent morphology of the tungsten surface. We have also examined how bubble growth differs at various microstructural features. These results highlight the importance of performing simulations at experimentally relevant conditions in order to correctly capture the contributions of the various significant kinetic processes and predict the overall response of the material.

  6. THE SPECIFIC ACCELERATION RATE IN LOOP-STRUCTURED SOLAR FLARES-IMPLICATIONS FOR ELECTRON ACCELERATION MODELS

    SciTech Connect

    Guo, Jingnan; Emslie, A. Gordon; Piana, Michele E-mail: piana@dima.unige.it

    2013-03-20

    We analyze electron flux maps based on RHESSI hard X-ray imaging spectroscopy data for a number of extended coronal-loop flare events. For each event, we determine the variation of the characteristic loop length L with electron energy E, and we fit this observed behavior with models that incorporate an extended acceleration region and an exterior 'propagation' region, and which may include collisional modification of the accelerated electron spectrum inside the acceleration region. The models are characterized by two parameters: the plasma density n in, and the longitudinal extent L{sub 0} of, the acceleration region. Determination of the best-fit values of these parameters permits inference of the volume that encompasses the acceleration region and of the total number of particles within it. It is then straightforward to compute values for the emission filling factor and for the specific acceleration rate (electrons s{sup -1} per ambient electron above a chosen reference energy). For the 24 events studied, the range of inferred filling factors is consistent with a value of unity. The inferred mean value of the specific acceleration rate above E{sub 0} = 20 keV is {approx}10{sup -2} s{sup -1}, with a 1{sigma} spread of about a half-order-of-magnitude above and below this value. We compare these values with the predictions of several models, including acceleration by large-scale, weak (sub-Dreicer) fields, by strong (super-Dreicer) electric fields in a reconnecting current sheet, and by stochastic acceleration processes.

  7. 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. PMID:22692089

  8. 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

  9. Gearbox gene expression and growth rate.

    PubMed

    Aldea, M; Garrido, T; Tormo, A

    1993-07-01

    Regulation of gene expression in prokaryotic cells usually takes place at the level of transcription initiation. Different forms of RNA polymerase recognizing specific promoters are engaged in the control of many prokaryotic regulons. This also seems to be the case for some Escherichia coli genes that are induced at low growth rates and by nutrient starvation. Their gene products are synthesized at levels inversely proportional to growth rate, and this mode of regulation has been termed gearbox gene expression. This kind of growth-rate modulation is exerted by specific transcriptional initiation signals, the gearbox promoters, and some of them depend on a putative new σ factor (RpoS). Gearbox promoters drive expression of morphogenetic and cell division genes at constant levels per cell and cycle to meet the demands of cell division and septum formation. A mechanism is proposed that could sense the growth rate of the cell to alter gene expression by the action of specific σ factors. PMID:24420108

  10. 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.

  11. 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

  12. 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. PMID:27482462

  13. 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

  14. 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.

  15. High data-rate atom interferometer for measuring acceleration

    SciTech Connect

    McGuinness, Hayden J.; Rakholia, Akash V.; Biedermann, Grant W.

    2012-01-02

    We demonstrate a high data-rate light-pulse atom interferometer for measuring acceleration. The device is optimized to operate at rates between 50 Hz to 330 Hz with sensitivities of 0.57{mu}g/{radical}(Hz) to 36.7{mu}g/{radical}(Hz), respectively. Our method offers a dramatic increase in data rate and demonstrates a path to applications in highly dynamic environments. The performance of the device can largely be attributed to the high recapture efficiency of atoms from one interferometer measurement cycle to another.

  16. Unexpectedly large dose rate dependent output from a linear accelerator.

    PubMed

    Cheng, P C; Kubo, H

    1988-01-01

    During our routine calibration of a Varian Clinac-20 linear accelerator, the absorbed dose for a fixed monitor unit (mu) was found to decrease with increasing dose rate. Between dose rates of 100 and 500 mu/min, there was up to 20% difference in absorbed dose for a 20-MeV electron beam. The cause of this problem was a failure in the electronics circuit of an integrating board. This paper presents our analysis of the problem and suggests a possible means of isolating such a failure to warn technologists, physicists, and engineers. PMID:3141760

  17. 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

  18. SCIRAS sensor - Sundstrand Coriolis Inertial Rate and Acceleration Sensor

    NASA Astrophysics Data System (ADS)

    Hulsing, Rand H., II

    The evolution of the design of SCIRAS (Sundstrand Coriolis Inertial Rate and Acceleration Sensor) from operational theory through three generations of hardware is discussed. SCIRAS measures both angular rotation and linear acceleration and is suitable for a full three-axis inertial navigation package replacing conventional clusters of gyros and accelerometers. Using only accelerometers, the package can be made smaller, lighter, and at less cost than equivalent performance sensors. Since a microprocessor is included, thermal modeling, misaligment correction, and size effect corrections can be made providing 'ideal' delta velocity and delta angle in digital format to a navigational computer. Since the sensor is all flexure, it has no wearout, is extremely rugged, and requires no special backfill, sealing, or maintenance.

  19. Effects of normal acceleration on transient burning rate augmentation of an aluminized solid propellant

    NASA Technical Reports Server (NTRS)

    Northam, G. B.

    1972-01-01

    Instantaneous burning rate data for a polybutadiene acrylic acid propellant, containing 16 weight percent aluminum, were calculated from the pressure histories of a test motor with 96.77 sq cm of burning area and a 5.08-cm-thick propellant web. Additional acceleration tests were conducted with reduced propellant web thicknesses of 3.81, 2.54, and 1.27 cm. The metallic residue collected from the various web thickness tests was characterized by weight and shape and correlated with the instantaneous burning rate measurements. Rapid depressurization extinction tests were conducted in order that surface pitting characteristics due to localized increased burning rate could be correlated with the residue analysis and the instantaneous burning rate data. The acceleration-induced burning rate augmentation was strongly dependent on propellant distance burned, or burning time, and thus was transient in nature. The results from the extinction tests and the residue analyses indicate that the transient rate augmentation was highly dependent on local enhancement of the combustion zone heat feedback to the surface by the growth of molten residue particles on or just above the burning surface. The size, shape, and number density of molten residue particles, rather than the total residue weight, determined the acceleration-induced burning rate augmentation.

  20. Forest stand growth dynamics in Central Europe have accelerated since 1870

    PubMed Central

    Pretzsch, Hans; Biber, Peter; Schütze, Gerhard; Uhl, Enno; Rötzer, Thomas

    2014-01-01

    Forest ecosystems have been exposed to climate change for more than 100 years, whereas the consequences on forest growth remain elusive. Based on the oldest existing experimental forest plots in Central Europe, we show that, currently, the dominant tree species Norway spruce and European beech exhibit significantly faster tree growth (+32 to 77%), stand volume growth (+10 to 30%) and standing stock accumulation (+6 to 7%) than in 1960. Stands still follow similar general allometric rules, but proceed more rapidly through usual trajectories. As forest stands develop faster, tree numbers are currently 17–20% lower than in past same-aged stands. Self-thinning lines remain constant, while growth rates increase indicating the stock of resources have not changed, while growth velocity and turnover have altered. Statistical analyses of the experimental plots, and application of an ecophysiological model, suggest that mainly the rise in temperature and extended growing seasons contribute to increased growth acceleration, particularly on fertile sites. PMID:25216297

  1. Growth rates of Chinese and American alligators.

    PubMed

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

    2002-04-01

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

  2. 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

    2015-01-01

    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

  3. 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

  4. 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.

  5. 1-year retention rates and performance ratings: comparing associate degree, baccalaureate, and accelerated baccalaureate degree nurses.

    PubMed

    Weathers, Suzanne M; Raleigh, Edith D Hunt

    2013-09-01

    The purpose of this study was to examine 1-year retention and managerial performance ratings of newly licensed RNs (NLRNs) according to nursing education program types (associate degree, traditional baccalaureate, and accelerated 2nd degree baccalaureate). Findings revealed retention and performance differences, suggesting the possibility of tradeoffs related to educational program type when selecting NLRNs for open positions. PMID:23958525

  6. 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. PMID:25896544

  7. 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. PMID:26913943

  8. 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

  9. In situ investigation of growth rates and growth rate dispersion of α-lactose monohydrate crystals

    NASA Astrophysics Data System (ADS)

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

    2009-02-01

    The growth rates and growth rate dispersion (GRD) of four different faces of α-lactose monohydrate crystal were measured at 30, 40 and 50 °C in the relative supersaturation range 0.55-2.33 in aqueous solutions. The overall growth rate of the crystal is around 50-60% of the (0 1 0) face of the crystal. The power law was applied to the growth rates of the four faces and the activation energies were calculated to be between 9.5 and 13.7 kcal/mol. This indicates a diffusion-controlled growth, but the exponents calculated are between 2.5 and 3.1 which are higher than unity. Introduction of critical supersaturation decreased the exponents to between 1.8 and 2.4. The variance of GRD for the (0 1 0) face is twice the variance of the GRD of the (1 1 0) and (1 0 0) faces and 10 times higher than the (1 1¯ 1¯) face at the same supersaturations and temperatures. The GRD of the four faces were similar when expressed as a function of growth rate. However, the (0 1 1) face displayed lower GRD than the other faces at the same temperatures and supersaturations.

  10. 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.

  11. Growth rate degeneracies in kinematic dynamos

    NASA Astrophysics Data System (ADS)

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

    2013-09-01

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

  12. 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.

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

    PubMed

    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. PMID:25493797

  14. The Determination of Relative Elemental Growth Rate Profiles from Segmental Growth Rates (A Methodological Evaluation).

    PubMed Central

    Peters, W. S.; Bernstein, N.

    1997-01-01

    Relative elemental growth rate (REGR) profiles describe spatial patterns of growth intensity; they are indispensable for causal growth analyses. Published methods of REGR profile determination from marking experiments fall in two classes: the profile is either described by a series of segmental growth rates, or calculated as the slope of a function describing the displacement velocities of points along the organ. The latter technique is usually considered superior for theoretical reasons, but to our knowledge, no comparative methodological study of the two approaches is currently available. We formulated a model REGR profile that resembles those reported from primary roots. We established the displacement velocity profile and derived growth trajectories, which enabled us to perform hypothetical marking experiments on the model with varying spacing of marks and durations of measurement. REGR profiles were determined from these data by alternative methods, and results were compared to the original profile. We find that with our model plotting of segmental relative growth rates versus segment position provides exact REGR profile estimations, if the initial segment length is less than 10% of the length of the whole growing zone, and if less than 20% of the growing zone is displaced past its boundary during the measurement. Based on our analysis, we discuss systematic errors that occur in marking experiments. PMID:12223680

  15. DnaK-Dependent Accelerated Evolutionary Rate in Prokaryotes.

    PubMed

    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

  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. The temporal relationship between infant heart rate acceleration and crying in an aversive situation.

    PubMed

    Vaughn, B; Sroufe, L A

    1979-06-01

    The temporal relationship between heart rate (HR) acceleration and crying was examined in 16 8-16-month-old infants. Consistently, the HR acceleration began well before the onset of crying, suggesting that such acceleration is not merely a by-product of crying. The accelerations observed were above and beyond a return to baseline following orienting. The crying itself validates the association between these instances of HR acceleration and negative effect. PMID:487890

  18. Derivatives of the Stochastic Growth Rate

    PubMed Central

    Steinsaltz, David; Tuljapurkar, Shripad; Horvitz, Carol

    2011-01-01

    We consider stochastic matrix models for population driven by random environments which form a Markov chain. The top Lyapunov exponent a, which describes the long-term growth rate, depends smoothly on the demographic parameters (represented as matrix entries) and on the parameters that define the stochastic matrix of the driving Markov chain. The derivatives of a — the “stochastic elasticities” — with respect to changes in the demographic parameters were derived by Tuljapurkar (1990). These results are here extended to a formula for the derivatives with respect to changes in the Markov chain driving the environments. We supplement these formulas with rigorous bounds on computational estimation errors, and with rigorous derivations of both the new and the old formulas. PMID:21463645

  19. Temperature accelerated dynamics : introduction and application to crystal growth.

    SciTech Connect

    Montalenti, F.

    2002-01-01

    Temperature accelerated dynamics (TAD) simulations allow one to reach long time scales without needing any a priori information on the system dynamics. As a consequence, TAD is a powerful method for simulating complex phenomena where the dynamics is highly unpredictable and the time scale is longer than the one reachable by standard molecular dynamics (ns-ps) . In this paper, we shall focus our attention on crystal growth. We give an overview of the TAD method, and we demonstrate that at low temperatures a TAD simulation can be faster than a standard molecular dynamics simulation by several orders of magnitude, allowing one to match typical experimental time scales of seconds or longer. Moreover, we explicitely show how critical it is to match the experimental time scale, in order to predict the correct geometry of the growing surface.

  20. 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.

  1. Effect of acceleration rate on automatic transmission shift-speeds for two 1979 Novas. Technical report

    SciTech Connect

    Jones, R.

    1980-01-01

    Variations in acceleration rates will result in variations in vehicle fuel economy. If typical vehicle acceleration rates are distributed in the same manner as the accelerations are distributed on the EPA test cycles, or if the vehicle operational characteristics do not significantly change with acceleration rate, then results from the EPA cycles should be representative of average vehicle use. However, if vehicle operational characteristics change with changing acceleration rates, and if vehicle accelerations in consumer use are not distributed in the same manner as the accelerations of the EPA test cycle, then significant differences between EPA estimated fuel economy and actual vehicle fuel consumption may result. One vehicle characteristic which often changes with acceleration rate is the transmission shift speed for vehicles with automatic transmissions. To determine the effects of acceleration rates on transmission shift speeds, EPA recently conducted a short test sequence on two vehicles with automatic transmissions. These tests determined the relation between vehicle acceleration rate and transmission shift speed for acceleration rates from 1 to 6 mph/sec.

  2. 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. PMID:22583121

  3. 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.

  4. Growth rate dispersion of small ammonium alum crystals

    NASA Astrophysics Data System (ADS)

    Teodossiev, N.

    1987-01-01

    The growth rates of small (below 60 μm) and large (about 1 mm) crystals of ammonium alum was measured during batch crystallization from aqueous solutions. The growth rate distribution of small crystals is close to normal. With increasing supersaturation the growth rate of the large crystals increases more rapidly than that of small crystals.

  5. Acceleration- and deceleration-phase nonlinear Rayleigh-Taylor growth at spherical interfaces

    NASA Astrophysics Data System (ADS)

    Clark, Daniel S.; Tabak, Max

    2005-11-01

    The Layzer model for the nonlinear evolution of bubbles in the Rayleigh-Taylor instability has recently been generalized to the case of spherically imploding interfaces [D. S. Clark and M. Tabak, Phys. Rev. E 71, 055302(R) (2005)]. The spherical case is more relevant to, e.g., inertial confinement fusion or various astrophysical phenomena when the convergence is strong or the perturbation wavelength is comparable to the interface curvature. Here, the model is further extended to the case of bubble growth during the deceleration (stagnation) phase of a spherical implosion and to the growth of spikes during both the acceleration and deceleration phases. Differences in the nonlinear growth rates for both bubbles and spikes are found when compared with planar results. The model predictions are verified by comparison with numerical hydrodynamics simulations.

  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. Recombinant basic fibroblast growth factor accelerates wound healing.

    PubMed

    McGee, G S; Davidson, J M; Buckley, A; Sommer, A; Woodward, S C; Aquino, A M; Barbour, R; Demetriou, A A

    1988-07-01

    Basic fibroblast growth factor (bFGF) stimulates extracellular matrix metabolism, growth, and movement of mesodermally derived cells. We have previously shown that collagen content in polyvinyl alcohol sponges increased after bFGF treatment. We hypothesized that bFGF-treated incisional wounds would heal more rapidly. After intraperitoneal pentobarbital anesthesia, male, 200- to 250-g, Sprague-Dawley rats (n = 27) each underwent two sets of paired, transverse, dorsal incisions closed with steel sutures. On Day 3 postwounding, 0.4 ml of bFGF (recombinant, 400 ng. Synergen) or normal saline was injected into one of each paired incisions. Animals were killed with ether on postwounding Days 5, 6, and 7 and their dorsal pelts were excised. Fresh or formalin-fixed wound strips were subjected to tensile strength measurements using a tensiometer. Breaking energy was calculated. Wound collagen content (hydroxyproline) was measured in wound-edge samples following hydrolysis using high-performance liquid chromatography. There was an overall significant increase in fresh wound tensile strength (13.7 +/- 1.06 vs 19.1 +/- 1.99 g/mm, P less than 0.01) and wound breaking energy (476 +/- 47 vs 747 +/- 76 mm2, P less than 0.001) in bFGF-treated incisions. There was an increase in wound collagen content which was not statistically significant and there was no difference in fixed incisional tensile strength. Histologic examination showed better organization and maturation in bFGF wounds. Recombinant bFGF accelerates normal rat wound healing. This may be due to earlier accumulation of collagen and fibroblasts and/or to greater collagen crosslinking in bFGF-treated wounds. PMID:3392988

  8. Surprising decline in Iran's growth rates.

    PubMed

    Roudi, F

    1997-11-01

    According to Iran's 1996 census, the country's population was 60 million, about 6-7 million people fewer than estimates used by the UN and other international organizations. These findings surprised Iranian demographers and have been examined with skepticism outside of the country. However, if Iran's 1986 and 1996 censuses are comparable and children were not undercounted, these results indicate a remarkable decline in fertility. The proportion of Iran's population under age 5 years fell from 18% in 1986 to 10% in 1996. An Institut National d'Etudes Demographiques, Paris, study published in 1996 estimated that Iran's total fertility rate (TFR) fell from an average of 6.2 children/woman in 1986 to 3.5 in 1993. However, based upon analyses of sample surveys, the Iranian government's health ministry reported that the TFR dropped from 5.0 in 1991 to 3.3 in 1995. Irrespective of questions over the magnitude of Iran's fertility decline, it is clear that the Iranian government is committed to limiting population growth. The UN Population Fund considers Iran's family planning program to be one of the world's best-functioning, with the Ministry of Health Care and Medical Education providing free contraceptives. A bill was passed in 1993 which penalizes couples who have more than 3 children and posters around the country encourage the one- or two-child family. Iran's family planning program is integrated into the national primary health care system and provides a broad range of reproductive health services to women. The program is also the only one in the region which promotes both male and female sterilization. PMID:12321257

  9. Calcite crystal growth rate inhibition by polycarboxylic acids

    USGS Publications Warehouse

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

    2001-01-01

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

  10. 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.

  11. Acceleration and Deceleration Phase Nonlinear Rayleigh-Taylor Growth at Spherical Interfaces

    NASA Astrophysics Data System (ADS)

    Clark, Daniel

    2005-10-01

    The Layzer model for the nonlinear evolution of bubbles in the Rayleigh-Taylor instability has recently been generalized to the case of spherically imploding interfaces [D. S. Clark and M. Tabak, Phys. Rev. E 71, 055302(R) (2005).]. The spherical case is more relevant to, e.g., Inertial Confinement Fusion (ICF) or various astrophysical phenomena when the convergence is strong or the perturbation wavelength is comparable to the interface curvature. Here, the model is further extended to the case of bubble growth during the deceleration (stagnation) phase of a spherical implosion and to the growth of spikes during both the acceleration and deceleration phases. Differences in the nonlinear growth rates for both bubbles and spikes are found when compared with planar results, and the model predictions are verified by comparison with numerical hydrodynamics simulations. The new nonlinear growth rates are also incorporated into a Haan-type saturation model to give improved predictions of multi-mode saturated growth for ICF capsules.

  12. Growth rate enhancement of potash alum crystals by microcrystals

    NASA Astrophysics Data System (ADS)

    Matsuoka, Masakuni; Kamada, Toyohiro; Takiyama, Hiroshi

    1996-01-01

    During the steady growth of a single crystal of potash alum fixed in a clear supersaturated solution, secondary nucleation was intentionally induced by adding ground potash alum crystals and the resulting changes in the growth rate and the solution concentration were measured. The growth rates after the nucleation were found to abruptly increase by a factor of up to 3, and to gradually return to the steady growth rates or to some constant values. At the same time, the solution concentration started to decrease at the moment of the nucleation. As a measure of the growth rate increase the enhancement coefficient, ɛ 0, was introduced which was defined as the ratio of the growth rates in the presence to the absence of microcrystals at the same supersaturation. The values of ɛ 0 were found to be almost independent of the growth rate in the absence of microcrystals, i.e. the solution supersaturation.

  13. Accelerated fatigue crack growth behavior of PWA 1480

    NASA Technical Reports Server (NTRS)

    Telesman, Jack; Ghosn, Louis J.

    1988-01-01

    An investigation of the fatigue crack growth (FCG) behavior of PWA 1480 single crystal nickel base superalloy was conducted. Typical Paris region behavior was observed above a delta K of 8 MPa sq rt of m. However, below that stress intensity range, the alloy exhibited highly unusual behavior. This behavior consisted of a region where the crack growth rate became essentially independent of the applied stress intensity. The transition in the FCG behavior was related to a change in the observed crack growth mechanisms. In the Paris region, fatigue failure occurred along (111) facets; however, at the lower stress intensities, (001) fatigue failure was observed. A mechanism was proposed, based on barriers to dislocation motion, to explain the changes in the observed FCG behavior. The FCG data were also evaluated in terms of a recently proposed stress intensity parameter, K sub rss. This parameter, based on the resolved shear stresses on the slip planes, quantified the crack driving force as well as the mode I delta K, and at the same time was also able to predict the microscopic crack path under different stress states.

  14. Multiple disturbances accelerate clonal growth in a potentially monodominant bamboo.

    PubMed

    Gagnon, Paul R; Platt, William J

    2008-03-01

    Organisms capable of rapid clonal growth sometimes monopolize newly freed space and resources. We hypothesize that sequential disturbances might change short-term clonal demography of these organisms in ways that promote formation of monotypic stands. We examined this hypothesis by studying the clonal response of Arundinaria gigantea (giant cane, a bamboo) to windstorm and fire. We studied giant cane growing in both a large tornado-blowdown gap and under forest canopy, in burned and unburned plots, using a split-block design. We measured density of giant cane ramets (culms) and calculated finite rates of increase (lamda) for populations of ramets over three years. Ramet density nearly doubled in stands subjected to both windstorm and fire; the high ramet densities that resulted could inhibit growth in other plants. In comparison, ramet density increased more slowly after windstorm alone, decreased after fire alone, and remained in stasis in controls. We predict that small, sparse stands of giant cane could spread and amalgamate to form dense, monotypic stands (called "canebrakes") that might influence fire return intervals and act as an alternative state to bottomland forest. Other clonal species may similarly form monotypic stands following successive disturbances via rapid clonal growth. PMID:18459325

  15. The Temporal Relationship between Infant Heart Rate Acceleration and Crying in an Aversive Situation.

    ERIC Educational Resources Information Center

    Vaughn, Brian; Sroufe, L. Alan

    1979-01-01

    Shows that the heart rate acceleration of 16 infants ranging in age from 8 to 16 months consistently began well before the onset of crying. This suggests that heart rate acceleration is not merely a by-product of crying but that it is associated with negative affect. (JMB)

  16. 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

  17. 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.

  18. Dinosaurian growth rates and bird origins.

    PubMed

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

    2001-07-26

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

  19. Analysis of Cell Division and Elongation Underlying the Developmental Acceleration of Root Growth in Arabidopsis thaliana1

    PubMed Central

    Beemster, Gerrit T.S.; Baskin, Tobias I.

    1998-01-01

    To investigate the relation between cell division and expansion in the regulation of organ growth rate, we used Arabidopsis thaliana primary roots grown vertically at 20°C with an elongation rate that increased steadily during the first 14 d after germination. We measured spatial profiles of longitudinal velocity and cell length and calculated parameters of cell expansion and division, including rates of local cell production (cells mm−1 h−1) and cell division (cells cell−1 h−1). Data were obtained for the root cortex and also for the two types of epidermal cell, trichoblasts and atrichoblasts. Accelerating root elongation was caused by an increasingly longer growth zone, while maximal strain rates remained unchanged. The enlargement of the growth zone and, hence, the accelerating root elongation rate, were accompanied by a nearly proportionally increased cell production. This increased production was caused by increasingly numerous dividing cells, whereas their rates of division remained approximately constant. Additionally, the spatial profile of cell division rate was essentially constant. The meristem was longer than generally assumed, extending well into the region where cells elongated rapidly. In the two epidermal cell types, meristem length and cell division rate were both very similar to that of cortical cells, and differences in cell length between the two epidermal cell types originated at the apex of the meristem. These results highlight the importance of controlling the number of dividing cells, both to generate tissues with different cell lengths and to regulate the rate of organ enlargement. PMID:9536070

  20. 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.

  1. Buoyancy and rotation in small-scale vertical Bridgman growth of cadmium zinc telluride using accelerated crucible rotation

    NASA Astrophysics Data System (ADS)

    Yeckel, Andrew; Derby, Jeffrey J.

    2001-12-01

    Theoretical simulations of vertical Bridgman growth of cadmium zinc telluride are performed to study the effects of the accelerated crucible rotation technique (ACRT). The results indicate that thermal buoyancy has a dramatic effect on the flow, even in a relatively small system at high rotation rate, contrary to assertions made in recent papers by Liu et al. (J. Crystal Growth 219 (2000) 22). We demonstrate their prior results greatly overstate the effectiveness of ACRT at promoting mixing. Contrary to conventional wisdom, the ACRT rotation cycle considered here for a small-scale growth system actually suppresses mixing in the melt near the ampoule wall, resulting in diffusion-limited mass transport there.

  2. 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.

  3. Near-term acceleration in the rate of temperature change

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    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 present 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 past 1,000 years. The rate of global-mean temperature increase in the CMIP5 (ref. ) archive over 40-year periods increases to 0.25 +/- 0.05 °C (1σ) per decade by 2020, an average greater than peak rates of change during the previous one to two 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.

  4. 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.

  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. PMID:22613786

  6. 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

  7. 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

  8. Early Acceleration of Students in Mathematics: Does It Promote Growth and Stability of Growth in Achievement across Mathematical Areas?

    ERIC Educational Resources Information Center

    Ma, Xin

    2005-01-01

    Using data from the Longitudinal Study of American Youth (LSAY), the present study examined whether early acceleration of students into formal algebra at the beginning of middle school promoted evident growth in different mathematical areas (basic skills, algebra, geometry, and quantitative literacy) and stable growth across these mathematical…

  9. FETAL DEXAMETHASONE EXPOSURE ACCELERATES DEVELOPMENT OF RENAL FUNCTION: RELATIONSHIP TO DOSE, CELL DIFFERENTIATION AND GROWTH INHIBITION

    EPA Science Inventory

    Fetal exposure to high doses of glucocorticoids slows cellular development and impairs organ performance, in association with growth retardation. evertheless, low doses of glucocorticoids may enhance cell differentiation and accelerate specific functions. he current study examine...

  10. 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.

  11. 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

  12. 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

  13. Seasonal Growth Rate of the Sponge Haliclona oculata (Demospongiae: Haplosclerida)

    PubMed Central

    Wijffels, René H.

    2008-01-01

    The interest in sponges has increased rapidly since the discovery of potential new pharmaceutical compounds produced by many sponges. A good method to produce these compounds by using aquaculture of sponges is not yet available, because there is insufficient knowledge about the nutritional needs of sponges. To gain more insight in the nutritional needs for growth, we studied the growth rate of Haliclona oculata in its natural environment and monitored environmental parameters in parallel. A stereo photogrammetry approach was used for measuring growth rates. Stereo pictures were taken and used to measure volumetric changes monthly during 1 year. Volumetric growth rate of Haliclona oculata showed a seasonal trend with the highest average specific growth rate measured in May: 0.012 ± 0.004 day−1. In our study a strong positive correlation (p < 0.01) was found for growth rate with temperature, algal biomass (measured as chlorophyll a), and carbon and nitrogen content in suspended particulate matter. A negative correlation (p < 0.05) was found for growth rate with salinity, ammonium, nitrate, nitrite, and phosphate. No correlation was found with dissolved organic carbon, suggesting that Haliclona oculata is more dependent on particulate organic carbon. PMID:18293037

  14. 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.

  15. 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

    2016-02-01

    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

  16. 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)

  17. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  19. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2011-04-01

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

  1. 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.

  2. 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.

  3. 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.

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

    PubMed

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

    2014-05-27

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

  5. Response of Escherichia coli growth rate to osmotic shock

    PubMed Central

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

    2014-01-01

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

  6. Growth Rates of Global Energy Systems and Future Outlooks

    SciTech Connect

    Hoeoek, Mikael; Li, Junchen; Johansson, Kersti; Snowden, Simon

    2012-03-15

    The world is interconnected and powered by a number of global energy systems using fossil, nuclear, or renewable energy. This study reviews historical time series of energy production and growth for various energy sources. It compiles a theoretical and empirical foundation for understanding the behaviour underlying global energy systems' growth. The most extreme growth rates are found in fossil fuels. The presence of scaling behaviour, i.e. proportionality between growth rate and size, is established. The findings are used to investigate the consistency of several long-range scenarios expecting rapid growth for future energy systems. The validity of such projections is questioned, based on past experience. Finally, it is found that even if new energy systems undergo a rapid 'oil boom'-development-i.e. they mimic the most extreme historical events-their contribution to global energy supply by 2050 will be marginal.

  7. 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. PMID:18460374

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Insights for Analyzing Earnings Growth Rates: A Case Study.

    ERIC Educational Resources Information Center

    Hannah, Richard L.

    1994-01-01

    A study at one public university investigated the annualized rate of salary/wage increase of employees from the time of hiring until July 1992. It examined promotion patterns, equity adjustments, employee degree acquisition, and certification of clerical workers. The study underscored the wide variation in earnings growth rates due in large part…

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

    PubMed Central

    Ren, Yuan

    2016-01-01

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

  14. 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.

  15. 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

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

    PubMed

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

    2015-12-01

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

  17. Noise in gene expression is coupled to growth rate

    PubMed Central

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

    2015-01-01

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

  18. Pattern of variation in avian population growth rates.

    PubMed Central

    Saether, Bernt-Erik; Engen, Steinar

    2002-01-01

    A central question in population ecology is to understand why population growth rates differ over time. Here, we describe how the long-term growth of populations is not only influenced by parameters affecting the expected dynamics, for example form of density dependence and specific population growth rate, but is also affected by environmental and demographic stochasticity. Using long-term studies of fluctuations of bird populations, we show an interaction between the stochastic and the deterministic components of the population dynamics: high specific growth rates at small densities r(1) are typically positively correlated with the environmental variance sigma(e)(2). Furthermore, theta, a single parameter describing the form of the density regulation in the theta-logistic density-regulation model, is negatively correlated with r(1). These patterns are in turn correlated with interspecific differences in life-history characteristics. Higher specific growth rates, larger stochastic effects on the population dynamics and stronger density regulation at small densities are found in species with large clutch sizes or high adult mortality rates than in long-lived species. Unfortunately, large uncertainties in parameter estimates, as well as strong stochastic effects on the population dynamics, will often make even short-term population projections unreliable. We illustrate that the concept of population prediction interval can be useful in evaluating the consequences of these uncertainties in the population projections for the choice of management actions. PMID:12396511

  19. 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

    2002-01-01

    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. PMID:11800957

  20. Pre- and Post-natal Growth Acceleration and Increased Sugar Consumption in Canadian Eskimos

    PubMed Central

    Schaefer, O.

    1970-01-01

    A striking increase in birth weights and height measurements in children of Canadian Eskimos was observed in recent years. The growth acceleration seen to varying degrees in different Eskimo groups appears most closely to parallel the increase in the per capita annual sugar consumption which has more than quadrupled during the last decade in some trading areas of the Canadian Central and Eastern Arctic, while the per capita consumption of protein derived from animal sources shows a reverse relationship. Canadian Eskimos do, therefore, contrary to what is stated in earlier publications, conform to the general secular growth acceleration patterns observed in all populations coming under the influence of modern civilization. They do not, however, conform to the commonly held explanation for this acceleration, namely increased consumption of high-quality proteins, since their traditionally extremely high consumption of meat and fish decreased markedly during the same period. Our observations confirm the relation of growth acceleration and consumption of sugar first established by the Swiss pediatrician, Eugen Ziegler. A hypothesis first advanced by Ziegler is elaborated to link this growth acceleration, in particular the extraordinary increase in birth weight, to “pseudo-diabetic” oral glucose tolerance patterns described previously by the author in a large proportion of Eskimos. ImagesFIG. 1 PMID:5494825

  1. Non-monotonic growth rates of sawtooth precursors evidenced with a new method on ASDEX Upgrade

    NASA Astrophysics Data System (ADS)

    Vezinet, D.; Igochine, V.; Weiland, M.; Yu, Q.; Gude, A.; Meshcheriakov, D.; Sertoli, M.; the Asdex Upgrade Team; the EUROfusion MST1 Team

    2016-08-01

    This paper describes a new method to derive, from soft x-ray (SXR) tomography, robust estimates of the core displacement, growth rate and frequency of a 1/1 sawtooth crash precursor. The method is valid for very peaked SXR profiles and is robust against both the inversion algorithm and the presence of tungsten in a rotating plasma. Three typical ASDEX Upgrade crashes are then analysed. In all cases a postcursor is observed, suggesting incomplete reconnection. Despite different dynamics, in all three cases the growth rate of the core displacement shows similar features. First, it is not constant, supporting the idea of non-linear growth. Second, it can be divided into clearly identified phases with quasi-constant growth rates, suggesting sudden change of growth regime rather than smooth transitions. Third, its evolution is non-monotonic, with phases of accelerated growth followed by damped phases. This damping is interpreted for two cases respectively as an effect of fast ions and of mode coupling, based on the result of a MHD simulation. The mode frequency is observed in all cases to be closely related to the plasma bulk rotation profile, with little or no visible effect of the electron diamagnetic drift frequency. The onset criterion could not be clearly identified and it is shown that the role of the pressure gradient is not as expected from a naive extrapolation of the linear stability theory.

  2. Greenhouse Gas Growth Rates from AIRS Hyperspectral Radiance Time Series

    NASA Astrophysics Data System (ADS)

    Strow, L. L.; Desouza-Machado, S. G.; Hannon, S.; Imbiriba, B.; Schou, P.

    2009-12-01

    The AIRS seven year hyperspectral radiance record provides an ideal platform for measurings growth rates of infrared active minor gases, especially carbon dioxide and methane. The largest changes in CLARREO radiances will likely be due to increasing carbon dioxide and other greenhouse gases. We have produced a 5+ year record of almost cloud-free AIRS radiances, from which we have derived the radiance anomaly and linear time rate of change. The source of these radiances are the L1b radiances corrected for small frequency drifts. Growth rates of carbon dioxide, nitrous oxide, methane, ozone, and CFC11 are simultaneously derived from zonal averages of these radiance rates for tropics, and mid-latitude northern and southern hemispheres. The effective linear rate of change of ~5 layers of water vapor and temperature, plus the surface temperature are also simultaneously derived with the minor gas rates. No model data or prior is needed and more than 1000 channels are used in the fit. Sampling issues may preclude the use of the mid-latitude temperature and water vapor rates for climate analysis, but possibly not for the tropics. The resulting greenhouse gas growth rates agree very well with in-situ measurements, which suggests high radiometric stability for AIRS. Radiance intercomparisons for climate analysis between IASI and AIRS will also be presented.

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

    PubMed Central

    Szymanowska-Pułka, Joanna; Lipowczan, Marcin

    2014-01-01

    Background and Aims Microscopic observations of lateral roots (LRs) in Arabidopsis thaliana reveal that the cross-sectional shape of the organ changes from its basal to its apical region. The founder cells for LRs are elongated along the parent root axis, and thus from the site of initiation the base of LRs resemble an ellipse. The circumference of the apical part of LRs is usually a circle. The objective of this study was to analyse the characteristics of changes in the growth field of LRs possessing various shapes in their basal regions. Methods The LRs of the wild type (Col-0) and two transgenic arabidopsis lines were analysed. On the basis of measurements of the long and short diameters (DL and DS, respectively) of the ellipse-like figure representing the bases of particular LRs, their asymmetry ratios (DL/DS) were determined. Possible differences between accessions were analysed by applying statistical methods. Key Results No significant differences between accessions were detected. Comparisons were therefore made of the maximal, minimal and mean value of the ratio of all the LRs analysed. Taking into consideration the lack of circular symmetry of the basal part, rates of growth were determined at selected points on the surface of LRs by the application of the growth tensor method, a mathematical tool previously applied only to describe organs with rotational symmetry. Maps showing the distribution of growth rates were developed for surfaces of LRs of various asymmetry ratios. Conclusions The maps of growth rates on the surfaces of LRs having various shapes of the basal part show differences in both the geometry and the manner of growth, thus indicating that the manner of growth of the LR primordium is correlated to its shape. This is the first report of a description of growth of an asymmetric plant organ using the growth tensor method. The mathematical modelling adopted in the study provides new insights into plant organ formation and shape. PMID:25108392

  4. Stress-induced martensitic transformation in metastable austenitic stainless steels: Effect on fatigue crack growth rate

    NASA Astrophysics Data System (ADS)

    Khan, Z.; Ahmed, M.

    1996-04-01

    This paper addresses the influence of cyclic stress-induced martensitic transformation on fatigue crack growth rates in metastable austenitic stainless steels. At low applied stress and mean stress values in AISI type 301 stainless steel, fatigue crack growth rate is substantially retarded due to a cyclic stress-induced γ-α' and γ-ɛ martensitic transformation occurring at the crack-tip plastic zone. It is suggested that the transformation products produce a compressive residual stress at the tip of the fatigue crack, which essentially lowers the effective stress intensity and hence retards the fatigue crack growth rate. At high applied stress or mean stress values, fatigue crack growth rates in AISI type 301 steels become almost equal to those of stable AISI type 302 alloy. As the amount of transformed products increases (with an increase in applied or mean stress), the strain-hardening effect brought about by the transformed martensite phase appears to accelerate fatigue crack growth, offsetting the contribution from the compressive residual stress produced by the positive volume change of γ → α' or ɛ transformation.

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

    SciTech Connect

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

    1992-12-01

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

  6. 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.

  7. 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.

  8. 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.

  9. 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. PMID:24327963

  10. The growth rate of gas hydrate from refrigerant R12

    SciTech Connect

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

    2006-07-15

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

  11. Cooling rate based on schreibersite growth for the Emery mesosiderite

    NASA Technical Reports Server (NTRS)

    Kulpecz, A. A., Jr.; Hewins, R. H.

    1978-01-01

    Computer simulation of diffusion-controlled growth of the large Ni-rich grains of schreibersite found in the Emery mesosiderite indicates that exsolution from kamacite occurred during cooling at the rate of 0.1 C/Myr. This finding agrees with the mesosiderite cooling rate determined by Powell (1969) from taenite-kamacite data. The cooling rate is the lowest found for any meteorite group, and implications for the cooling history, with a possibility of reheating, are considered. The procedure for computing a family of cooling rate curves is based on Randich's (1975) method.

  12. 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

  13. 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.

  14. Growth rate and cell size: A re-examination of the growth law

    PubMed Central

    Vadia, Stephen; Levin, Petra Anne

    2015-01-01

    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. PMID:25662920

  15. Phycocyanobilin accelerates liver regeneration and reduces mortality rate in carbon tetrachloride-induced liver injury mice

    PubMed Central

    Liu, Jie; Zhang, Qing-Yu; Yu, Li-Ming; Liu, Bin; Li, Ming-Yi; Zhu, Run-Zhi

    2015-01-01

    AIM: To investigate the hepatoprotective effects of phycocyanobilin (PCB) in reducing hepatic injury and accelerating hepatocyte proliferation following carbon tetrachloride (CCl4) treatment. METHODS: C57BL/6 mice were orally administered PCB 100 mg/kg for 4 d after CCl4 injection, and then the serum and liver tissue of the mice were collected at days 1, 2, 3, 5 and 7 after CCl4 treatment. A series of evaluations were performed to identify the curative effects on liver injury and recovery. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), albumin and superoxide dismutase (SOD) were detected to indirectly assess the anti-inflammatory effects of PCB. Meanwhile, we detected the expressions of hepatocyte growth factor, transforming growth factor alpha (TGF-α), TGF-β, tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6), the factors which are associated with inflammation and liver regeneration. The protein expressions of proliferating cell nuclear antigen (PCNA), TNF-α and cytochrome C were detected by western blot. Furthermore, the survival rates were analyzed of mice which were administered a lethal dose of CCl4 (2.6 mg/kg) with or without PCB. RESULTS: In our research, PCB showed a strongly anti-inflammatory effect on CCl4-induced liver injury in mice. The ALT was significantly decreased after CCl4 treatment from day 1 (P < 0.01) and the AST was significantly decreased from day 2 (P < 0.001). Both albumin and liver SOD were increased from day 2 (P < 0.001 and P < 0.01), but serum SOD levels did not show a significant increase (P > 0.05). PCB protected the structure of liver from the injury by CCl4. TUNEL assay showed that PCB dramatically reduced the number of apoptotic cells after CCl4 treatment compared to the control (101.0 ± 25.4 vs 25.7 ± 6.4, P < 0.01). The result of western blotting showed that PCB could increase PCNA expression, decrease TNF-α and cytochrome C expression. Furthermore, data shows that PCB could improve the

  16. 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

  17. Concentration dependence of variability in growth rates of microtubules.

    PubMed Central

    Pedigo, Susan; Williams, Robley C

    2002-01-01

    Growth and shortening of microtubules in the course of their polymerization and depolymerization have previously been observed to occur at variable rates. To gain insight into the meaning of this prominent variability, we studied the way in which its magnitude depends on the growth rate of experimentally observed and computer-simulated microtubules. The dynamic properties of plus-ended microtubules nucleated by pieces of Chlamydomonas flagellar axonemes were observed in real time by video-enhanced differential interference contrast light microscopy at differing tubulin concentrations. By means of a Monte Carlo algorithm, populations of microtubules were simulated that had similar growth and dynamic properties to the experimentally observed microtubules. By comparison of the experimentally observed and computer-simulated populations of microtubules, we found that 1) individual microtubules displayed an intrinsic variability that did not change as the rate of growth for a population increased, and 2) the variability was approximately fivefold greater than predicted by a simple model of subunit addition and loss. The model used to simulate microtubule growth has no provision for incorporation of lattice defects of any type, nor sophisticated geometry of the growing end. Thus, these as well as uncontrolled experimental variables were eliminated as causes for the prominent variability. PMID:12324403

  18. Upscaling Calcite Growth Rates From the Mesoscale to the Macroscale

    SciTech Connect

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

    2013-01-01

    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.

  19. Islamic Republic of Iran population growth rate declines.

    PubMed

    1996-01-01

    In April 1996, at the 52nd Session of the UN Economic and Social Commission for Asia and the Pacific (ESCAP), the delegate from the Islamic Republic of Iran announced that social indicators indicate acceptable improvement. The average population growth rate fell from 3.9% (1981-1991) to less than 2% (1995). High birth rates and an influx of refugees during 1981-1991 accounted for the high population growth rate. The marked decline in the birth rate, brought about mainly by effective family planning and health programs, has contributed greatly to the reduced population growth rate. The government has focused on rural areas. 86% of rural households now have access to piped water. More than 60% have electricity. The overall literacy rate in Iran has reached 79%. The entire population has access to free or subsidized primary health care services. The Second Development Plan of Iran centers on the significance of the role that mothers have in shaping society and individuals by their child raising abilities, particularly in the early years. The Iranian delegate endorsed the secretariat's plan for helping members and associate members to reach their development goals and objectives. PMID:12291139

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

    PubMed

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

    2016-01-01

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

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

    PubMed Central

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

    2016-01-01

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

  2. 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.

  3. Delays and Growth Rates of Multiple TEOAE Components

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

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

  4. Lateral growth rates in laser CVD of microstructures

    NASA Astrophysics Data System (ADS)

    Petzoldt, F.; Piglmayer, K.; Kräuter, W.; Bäuerle, D.

    1984-11-01

    Lateral growth rates of Ni spots deposited on absorbing substrates by decomposition of Ni(CO)4 with visible Kr+ laser light have been measured. The experimental data are consistent with the calculated temperature distributions. The mechanism of decomposition is thermal with an apparent chemical activation energy of 22±3 kcal/mole for the temperature range 350 K≦ T≦500 K.

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

    PubMed

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

    2007-01-01

    We measured resting and peak metabolic rates (RMR and PMR, respectively) during development of chicks of seven species of shorebirds: least sandpiper (Calidris minutilla; adult mass 20-22 g), dunlin (Calidris alpina; 56-62 g), lesser yellowlegs (Tringa flavipes; 88-92 g), short-billed dowitcher (Limnodromus griseus; 85-112 g), lesser golden plover (Pluvialis dominicana; 150-156 g), Hudsonian godwit (Limosa haemastica; 205-274 g), and whimbrel (Numenius phaeopus; 380 g). We tested two opposing hypotheses: the growth rate-maturity hypothesis, which posits that growth rate in chicks is inversely related to functional maturity of tissues, and the fast growth rate-high metabolism hypothesis, which suggests that rapid growth is possible only with a concomitant increase in either RMR or PMR. We have found no evidence that chicks of shorebirds with fast growth rates have lower RMRs or lower PMRs, as would be predicted by the growth rate-maturity hypothesis, but our data suggested that faster-growing chest muscles resulted in increased thermogenic capacity, consistent with the fast growth-high metabolism hypothesis. The development of homeothermy in smaller species is a consequence primarily of greater metabolic intensities of heat-generating tissues. The maximum temperature gradient between a chick's body and environment that can be maintained in the absence of a net radiative load increased rapidly with body mass during development and was highest in least sandpipers and lowest among godwits. Chicks of smaller species could maintain a greater temperature gradient at a particular body mass because of their higher mass-specific maximum metabolic rates. PMID:17717813

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

    PubMed Central

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

    1993-01-01

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

  7. Relating Productivity Events to Holocene Bivalve Shell Growth Rates

    NASA Astrophysics Data System (ADS)

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

    2007-12-01

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

  8. 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.

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

    USGS Publications Warehouse

    Tappeiner, J. C., II; 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.

  10. 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. PMID:26896714

  11. 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.

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

    NASA Astrophysics Data System (ADS)

    Li, Qianzhong; Luo, Liaofu

    1996-12-01

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

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

    PubMed

    Perrin, Bruce; Walker, Anne; Mackay, Ranald

    2003-03-01

    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. PMID:12696804

  14. 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.

  15. Charge Accretion Rate and Injection Radius of Ionized-Induced Injections in Laser Wakefield Accelerators

    NASA Astrophysics Data System (ADS)

    Zeng, Ming; Chen, Min; Sheng, Zheng-Ming

    2016-03-01

    Ionization-induced injection has recently been proved to be a stable injection method with several advantages in laser wakefield accelerators. However, the controlling of this injection process aiming at producing high quality electron beams is still challenging. In this paper, we examine the ionization injection processes and estimate the injection rate with two-dimensional particle-in-cell simulations. The injection rate is shown to increase linearly with the high-Z gas density as long as its ratio is smaller than some threshold in the mix gases. It is also shown that by changing the transverse mode of the driving lasers one can control the injection rate.

  16. 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. PMID:24483736

  17. The influence of acceleration forces on dendritic growth and grain structure

    NASA Technical Reports Server (NTRS)

    Johnston, M. H.; Parr, R. A.

    1982-01-01

    The results of experiments on the tin-15 wt pct lead system are presented, showing the effects on microstructure of solidification in the presence of acceleration forces from 0.0001 to 5 g for three cooling rates. An increase in the acceleration level is shown to drive fluid flow and cause dendrite remelting, fragmentation, and macrosegregation. The cooling rate impacts the final structure through its control of dendrite arm spacings and permeability to fluid flow. At the low (0.0001 g) acceleration, dendrite arm spacings deviated from the predicted relationship to cooling rate. An explanation for this anomaly is given which considers the temperature and concentration gradients in the low-gravity environment.

  18. 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.

  19. Withaferin A inhibits in vivo growth of breast cancer cells accelerated by Notch2 knockdown.

    PubMed

    Kim, Su-Hyeong; Hahm, Eun-Ryeong; Arlotti, Julie A; Samanta, Suman K; Moura, Michelle B; Thorne, Stephen H; Shuai, Yongli; Anderson, Carolyn J; White, Alexander G; Lokshin, Anna; Lee, Joomin; Singh, Shivendra V

    2016-05-01

    The present study offers novel insights into the molecular circuitry of accelerated in vivo tumor growth by Notch2 knockdown in triple-negative breast cancer (TNBC) cells. Therapeutic vulnerability of Notch2-altered growth to a small molecule (withaferin A, WA) is also demonstrated. MDA-MB-231 and SUM159 cells were used for the xenograft studies. A variety of technologies were deployed to elucidate the mechanisms underlying tumor growth augmentation by Notch2 knockdown and its reversal by WA, including Fluorescence Molecular Tomography for measurement of tumor angiogenesis in live mice, Seahorse Flux analyzer for ex vivo measurement of tumor metabolism, proteomics, and Luminex-based cytokine profiling. Stable knockdown of Notch2 resulted in accelerated in vivo tumor growth in both cells reflected by tumor volume and/or latency. For example, the wet tumor weight from mice bearing Notch2 knockdown MDA-MB-231 cells was about 7.1-fold higher compared with control (P < 0.0001). Accelerated tumor growth by Notch2 knockdown was highly sensitive to inhibition by a promising steroidal lactone (WA) derived from a medicinal plant. Molecular underpinnings for tumor growth intensification by Notch2 knockdown included compensatory increase in Notch1 activation, increased cellular proliferation and/or angiogenesis, and increased plasma or tumor levels of growth stimulatory cytokines. WA administration reversed many of these effects providing explanation for its remarkable anti-cancer efficacy. Notch2 functions as a tumor growth suppressor in TNBC and WA offers a novel therapeutic strategy for restoring this function. PMID:27097807

  20. The BMP roof plate chemorepellent regulates the rate of commissural axonal growth

    PubMed Central

    Phan, Keith D.; Hazen, Virginia M.; Frendo, Michele; Jia, Zhengping; Butler, Samantha J.

    2010-01-01

    Commissural spinal axons extend away from the roof plate (RP) in response to a chemorepellent mediated by the Bone Morphogenetic Proteins (BMPs). Previous studies have focused on the ability of commissural axons to translate a spatial gradient of BMPs into directional information in vitro. However, a notable feature of this system in vivo is that the gradient of BMPs is thought to act from behind the commissural cell bodies, making it possible for the BMPs to have a continued effect on commissural axons as they grow away from the RP. Here, we demonstrate that BMPs activate the cofilin regulator Limk1 to control the rate of commissural axon extension in the dorsal spinal cord. By modulating Limk1 activity in both rodent and chicken commissural neurons, the rate of axon growth can either be stalled or accelerated. Altering the activation state of Limk1 also influences subsequent guidance decisions: accelerated axons make rostrocaudal projection errors while navigating their intermediate target, the floor plate. These results suggest that guidance cues can specify information about the rate of growth, to ensure that axons reach subsequent signals either at particular times or speeds during development. PMID:21084599

  1. 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

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

    PubMed Central

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

    2016-01-01

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

  3. Flute growth rate of plasma jet in mirror machine

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

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

  4. Polar cap plasma patch primary linear instability growth rates compared

    NASA Astrophysics Data System (ADS)

    Burston, Robert; Mitchell, Cathryn; Astin, Ivan

    2016-04-01

    Four primary plasma instability processes have been proposed in the literature to explain the generation of phase scintillation associated with polar cap plasma patches. These are the gradient drift, current convective, and Kelvin-Helmholtz instabilities and a small-scale "turbulence" process. In this paper the range of possible values of the linear growth rates for each of these processes is explored using Dynamics Explorer 2 satellite observations. It is found that the inertial turbulence instability is the dominant process, followed by inertial gradient drift, collisional turbulence, and collisional shortwave current convective instabilities. The other processes, such as Kelvin-Helmholtz, collisional gradient drift, and inertial shortwave current convective instabilities, very rarely (<1% of the time) give rise to a growth rate exceeding 1/60, that is deemed to be significant (in publications) to give rise to GPS scintillation.

  5. Simulation of Crack Growth Rate in Martensitic Steel

    NASA Astrophysics Data System (ADS)

    Odukwe, A. O.; Ajayi, O. O.; Oluwadare, G. O.

    This research used the stress intensity factor with rate of crack growth per cycle of loading to model and simulates the crack growth in Martensitic steel in air environment. The basic parameters used were da/dN and ΔK, log (da/dN) was analyzed against log (ΔK) and a regression analysis using data from log (da/dN) vs log (ΔK) was carried out and the outcome employed to develop a model and simulation which gave rise to interactive software that can be used to predict the behavior of a structural member under conditions of certain loading. Additionally, it can be employed to have quick access to data and design considerations, when input data are supplied. This became useful in monitoring the point at which crack can initiate and the rate at which it would grow in a particular structural member of interest. The software has been tested with theoretical and experimental data.

  6. Vapor transport and crystal growth of GeSe under normal and high acceleration

    NASA Technical Reports Server (NTRS)

    Wiedemeier, H.; Regel', L. L.; Palosz, W.

    1992-01-01

    Physical vapor transport experiments on GeSe in the presence of 2 atm xenon and for a nominal temperature difference of 600-500 C were performed under 1 g, 5 g, and 10 g acceleration conditions. Under high acceleration and destabilizing conditions, the GeSe crystals are generally larger than those under 1 g, stabilizing, and up to three orders of magnitude larger in surface area than those under 1 g, destabilizing conditions. The mass transport rates of the 5 g and 10 g destabilizing experiments are considerably greater than those of the 10 g, stabilizing, and 1 g experiments. The observed increase in mass flux (under destabilizing conditions) with acceleration is significantly greater than the anticipated dependence (mass flux proportional to g exp 1/4) for laminar, boundary-layer driven free convection. In view of the considerable convection under high acceleration, destabilizing conditions, the surface morphology and bulk crystallinity of the large crystal platelets are unexpectedly good.

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

    PubMed Central

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

    2005-01-01

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

  8. 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

  9. 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.

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

    PubMed Central

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

    2013-01-01

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

  11. The GroEL protein of Porphyromonas gingivalis accelerates tumor growth by enhancing endothelial progenitor cell function and neovascularization.

    PubMed

    Lin, F-Y; Huang, C-Y; Lu, H-Y; Shih, C-M; Tsao, N-W; Shyue, S-K; Lin, C-Y; Chang, Y-J; Tsai, C-S; Lin, Y-W; Lin, S-J

    2015-06-01

    Porphyromonas gingivalis is a bacterial species that causes destruction of periodontal tissues. Additionally, previous evidence indicates that GroEL from P. gingivalis may possess biological activities involved in systemic inflammation, especially inflammation involved in the progression of periodontal diseases. The literature has established a relationship between periodontal disease and cancer. However, it is unclear whether P. gingivalis GroEL enhances tumor growth. Here, we investigated the effects of P. gingivalis GroEL on neovasculogenesis in C26 carcinoma cell-carrying BALB/c mice and chick eggs in vivo as well as its effect on human endothelial progenitor cells (EPC) in vitro. We found that GroEL treatment accelerated tumor growth (tumor volume and weight) and increased the mortality rate in C26 cell-carrying BALB/c mice. GroEL promoted neovasculogenesis in chicken embryonic allantois and increased the circulating EPC level in BALB/c mice. Furthermore, GroEL effectively stimulated EPC migration and tube formation and increased E-selectin expression, which is mediated by eNOS production and p38 mitogen-activated protein kinase activation. Additionally, GroEL may enhance resistance against paclitaxel-induced cell cytotoxicity and senescence in EPC. In conclusion, P. gingivalis GroEL may act as a potent virulence factor, contributing to the neovasculogenesis of tumor cells and resulting in accelerated tumor growth. PMID:25220060

  12. 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. PMID:24379437

  13. Numerical study of liquid phase diffusion growth of SiGe subjected to accelerated crucible rotation

    NASA Astrophysics Data System (ADS)

    Sekhon, M.; Lent, B.; Dost, S.

    2016-03-01

    The effect of accelerated crucible rotation technique (ACRT) on liquid phase diffusion (LPD) growth of SixGe1-x crystal has been investigated numerically. Transient, axisymmetric simulations have been carried out for triangular and trapezoidal ACRT cycles. Natural convection driven flow in the early growth hours is found to be modified by the ACRT induced Ekman flow. Results also reveal that a substantial mixing in the solution can be induced by the application of ACRT in the later hours of growth which is otherwise a diffusion dominated growth period for LPD growth technique. A comparison is drawn to the cases of stationary crucible and crucible rotating at a constant speed examined previously for this growth system by Sekhon and Dost (J. Cryst. Growth 430 (2015) 63). It is found that a superior interface flattening effect and radial compositional uniformity along the growth interface can be accomplished by employing ACRT at 12 rpm than that which could be achieved by using steady crucible rotation at 25 rpm, owing to the higher time averaged growth velocity achieved in the former case. Furthermore, minor differences are also predicted in the results obtained for trapezoidal and triangular ACRT cycles.

  14. 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.

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

    NASA Astrophysics Data System (ADS)

    Zhang, Anwei

    2016-05-01

    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.

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

    PubMed

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

    2015-11-01

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

  17. 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. PMID:24626875

  18. Rayleigh-Taylor Growth Measurements in the Acceleration Phase of Spherical Implosions on OMEGA

    SciTech Connect

    Smalyuk, V. A.; Hu, S. X.; Hager, J. D.; Delettrez, J. A.; Meyerhofer, D. D.; Sangster, T. C.; Shvarts, D.

    2009-09-04

    The Rayleigh-Taylor (RT) growth of 3D broadband nonuniformities was measured using x-ray radiography in spherical plastic shells accelerated by laser light at an intensity of approx2x10{sup 14} W/cm{sup 2}. The 20- and 24-mum-thick spherical shells were imploded with 54 beams on the OMEGA laser system. The shells contained diagnostic openings for backlighter x rays used to image shell modulations. The measured shell trajectories and modulation RT growth were in fair agreement with 2D hydro simulations during the acceleration phase of the implosions with convergence ratios of up to approx2.2. Since the ignition designs rely on these simulations, improvements in the numerical codes will be implemented to achieve better agreement with experiments.

  19. Rayleigh-Taylor Growth Measurements in the Acceleration Phase of Spherical Implosions on OMEGA

    SciTech Connect

    Smalyuk, V.A.; Hu, S.X.; Hager, J.D.; Delettrez, J.A.; Meyerhofer, D.D.; Sangster, T.C.; Shvarts, D.

    2009-09-10

    The Rayleigh-Taylor (RT) growth of 3D broadband nonuniformities was measured using x-ray radiography in spherical plastic shells accelerated by laser light at an intensity of ~2 x 10^14 W/cm^2. The 20- and 24-um-thick spherical shells were imploded with 54 beams on the OMEGA laser system. The shells contained diagnostic openings for backlighter x rays used to image shell modulations. The measured shell trajectories and modulation RT growth were in fair agreement with 2D hydro simulations during the acceleration phase of the implosions with convergence ratios of up to ~2:2. Since the ignition designs rely on these simulations, improvements in the numerical codes will be implemented to achieve better agreement with experiments.

  20. 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.

  1. 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.

  2. 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.

  3. BBU and Corkscrew Growth Predictions for the Darht Second Axis Accelerator

    NASA Astrophysics Data System (ADS)

    Chen, Y. J.; Fawley, W. M.

    2001-06-01

    This paper discusses the means by which we plan to control BBU and corkscrew growth in DARHT-II. In section 2 we present the current design for the solenoidal field tune; since the last PAC meeting in 1999, the design beam current has been lowered from 4 to 2 kA which has lowered the necessary field strengths. In Sec. 3 we discuss the present predictions for the expected BBU growth; these predictions were made having used recent experimental measurements for the impedance of the DARHT-II accelerator cells. Finally, in Sec. 4 we present our most recent calculations for the expected corkscrew growth and also the expected performance of the tuning-V algorithm, which can reduce this growth by more than an order of magnitude.

  4. 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

  5. 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. PMID:26274183

  6. Theory about interrelationships between macromineral nutrients and growth rate during recovery from undernutrition.

    PubMed

    Portela, M L; Zeni, S; Río, M E

    1985-10-01

    Previous papers of our group have reported that, in the first stages of nutritional recovery, the needs of undernourished infants, in terms of Protein Calories percentage (P%) were higher than normal, and similar to those of other mammals which double their birth weight faster than man. During this period, a high dietary P% produces an accelerated catch-up growth. Therefore, Calcium and Phosphorus balances increase proportionally to weight gain rate (WGR), and Calcium retention per gram of new tissue is dependent on dietary Calcium/Protein ratio. On the other hand, Bernhart demonstrated that there was a direct correlation between the growth rate of the sucklings of several species, including humans, and the percentage of protein and ash in the fluid milk. As a consequence of these facts, we assume that during catch-up growth, in order to attain a normal body composition, dietary level of essential minerals must be related to factors affecting weight gain. These relationships suggest the hypothesis that, during the recovery from undernutrition, in order to meet the needs of the catch-up growth allowed by the Protein/Calories ratio, Calcium and Phosphorus milk concentrations would be in relation to the Protein/Calorie concentration. In this way, Calcium and Phosphorus concentrations might be the limiting factors for attaining a normal body composition. This hypothesis might also be generalized to other minerals in order to prevent them from becoming the limiting factors for attaining a normal body composition. PMID:3870820

  7. Intrauterine growth restriction programs an accelerated age-related increase in cardiovascular risk in male offspring.

    PubMed

    Dasinger, John Henry; Intapad, Suttira; Backstrom, Miles A; Carter, Anthony J; Alexander, Barbara T

    2016-08-01

    Placental insufficiency programs an increase in blood pressure associated with a twofold increase in serum testosterone in male growth-restricted offspring at 4 mo of age. Population studies indicate that the inverse relationship between birth weight and blood pressure is amplified with age. Thus, we tested the hypothesis that intrauterine growth restriction programs an age-related increase in blood pressure in male offspring. Growth-restricted offspring retained a significantly higher blood pressure at 12 but not at 18 mo of age compared with age-matched controls. Blood pressure was significantly increased in control offspring at 18 mo of age relative to control counterparts at 12 mo; however, blood pressure was not increased in growth-restricted at 18 mo relative to growth-restricted counterparts at 12 mo. Serum testosterone levels were not elevated in growth-restricted offspring relative to control at 12 mo of age. Thus, male growth-restricted offspring no longer exhibited a positive association between blood pressure and testosterone at 12 mo of age. Unlike hypertension in male growth-restricted offspring at 4 mo of age, inhibition of the renin-angiotensin system with enalapril (250 mg/l for 2 wk) did not abolish the difference in blood pressure in growth-restricted offspring relative to control counterparts at 12 mo of age. Therefore, these data suggest that intrauterine growth restriction programs an accelerated age-related increase in blood pressure in growth-restricted offspring. Furthermore, this study suggests that the etiology of increased blood pressure in male growth-restricted offspring at 12 mo of age differs from that at 4 mo of age. PMID:27147668

  8. 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.

  9. 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

  10. Artificial accelerators of the molecular chaperone Hsp90 facilitate rate-limiting conformational transitions.

    PubMed

    Zierer, Bettina K; Weiwad, Matthias; Rübbelke, Martin; Freiburger, Lee; Fischer, Gunter; Lorenz, Oliver R; Sattler, Michael; Richter, Klaus; Buchner, Johannes

    2014-11-01

    The molecular chaperone Hsp90 undergoes an ATP-driven cycle of conformational changes in which large structural rearrangements precede ATP hydrolysis. Well-established small-molecule inhibitors of Hsp90 compete with ATP-binding. We wondered whether compounds exist that can accelerate the conformational cycle. In a FRET-based screen reporting on conformational rearrangements in Hsp90 we identified compounds. We elucidated their mode of action and showed that they can overcome the intrinsic inhibition in Hsp90 which prevents these rearrangements. The mode of action is similar to that of the co-chaperone Aha1 which accelerates the Hsp90 ATPase. However, while the two identified compounds influence conformational changes, they target different aspects of the structural transitions. Also, the binding site determined by NMR spectroscopy is distinct. This study demonstrates that small molecules are capable of triggering specific rate-limiting transitions in Hsp90 by mechanisms similar to those in protein cofactors. PMID:25244159

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

    PubMed

    He, Wei; 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

  12. Modeling accelerated and decelerated drug release in terms of fractional release rate.

    PubMed

    Weiss, Michael

    2015-02-20

    The model of a proportional change in fractional dissolution rate was used to quantify influences on the vitro dissolution process. After fitting the original dissolution profile with an empirical model (inverse Gaussian distribution), acceleration and deceleration effects due to dissolution conditions or formulation parameters could be described by one parameter only. Acceleration of dissolution due to elevated temperature and deceleration by increasing the content of glyceryl monostearate in theophylline tablets are presented as examples. Likewise, this approach was applied to in vitro-in vivo correlation (IVIVC). It is shown that the model is appropriate when the plot of the in vivo versus in vivo times is nonlinear and can be described by a power function. The results demonstrate the utility of the model in dissolution testing and IVIVC assessment. PMID:25486334

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

    USGS Publications Warehouse

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

    1998-01-01

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

  14. 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

  15. Network effect of knowledge spillover: Scale-free networks stimulate R&D activities and accelerate economic growth

    NASA Astrophysics Data System (ADS)

    Konno, Tomohiko

    2016-09-01

    We study how knowledge spillover networks affect research and development (R&D) activities and economic growth. For this purpose, we extend a Schumpeterian growth model to the one on networks that depict the knowledge spillover relationships of R&D. We show that scale-free networks stimulate R&D activities and accelerate economic growth.

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

    NASA Astrophysics Data System (ADS)

    Chen, Chun-Long; Qi, Jiahui; Tao, Jinhui; Zuckermann, Ronald N.; Deyoreo, James J.

    2014-09-01

    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 and hydrophobic interactions, with hydrophobic interactions playing the dominant role. While either strong electrostatic or hydrophobic interactions inhibit growth and reduces expression of the {104} faces, correlations between peptoid-crystal binding energies and observed changes in calcite growth indicate moderate electrostatic interactions allow peptoids to weakly adsorb while moderate hydrophobic interactions cause disruption of surface-adsorbed water layers, leading to growth acceleration with retained expression of the {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.

  17. BBU and Corkscrew Growth Predictions for the DARHT Second Axis Accelerator

    SciTech Connect

    Chen, Y J; Fawley, W M

    2001-06-12

    The second axis accelerator of the Dual Axis Radiographic Hydrodynamic Test (DARHT-II) facility will produce a 2-kA, 20-MeV, 2-{micro}s output electron beam with a design goal of less than 1000 {pi} mm-mrad normalized transverse emittance. In order to meet this goal, both the beam breakup instability (BBU) and transverse ''corkscrew'' motion (due to chromatic phase advance) must be limited in growth. Using data from recent experimental measurements of the transverse impedance of actual DARHT-II accelerator cells by Briggs et al., they have used the LLNL BREAKUP code to predict BBU and corkscrew growth in DARHT-II. The results suggest that BBU growth should not seriously degrade the final achievable spot size at the x-ray converter, presuming the initial excitation level is of the order 100 microns or smaller. For control of corkscrew growth, a major concern is the number of ''tuning'' shots needed to utilize effectively the ''tuning-V'' algorithm. Presuming that the solenoid magnet alignment falls within spec, they believe that possibly as few as 50-100 shots will be necessary to set the dipole corrector magnet currents. They give some specific examples of tune determination for a hypothetical set of alignment errors.

  18. BBU and Corkscrew Growth Predictions for the Darht Second Axis Accelerator

    SciTech Connect

    Chen, Y.J.; Fawley, W.M.

    2001-06-12

    The second axis accelerator of the Dual Axis Radiographic Hydrodynamic Test (DARHT-II) facility will produce a 2-kA, 20-MeV, 2-{micro}s output electron beam with a design goal of less than 1000 {pi} mm-mrad normalized transverse emittance. In order to meet this goal, both the beam breakup instability (BBJ) and transverse corkscrew motion (due to chromatic phase advance) must be limited in growth. Using data from recent experimental measurements of the transverse impedance of actual DARHT-II accelerator cells by Briggs et al. [2], they have used the LLNL BREAKUP code to predict BBU and corkscrew growth in DARHT-II. The results suggest that BBU growth should not seriously degrade the final achievable spot size at the x-ray converter, presuming the initial excitation level is of the order 100 microns or smaller. For control of corkscrew growth, a major concern is the number of tuning shots needed to utilize effectively the tuning-V algorithm [3]. Presuming that the solenoid magnet alignment falls within spec, they believe that possibly as few as 50-100 shots will be necessary to set the dipole corrector magnet currents. They give some specific examples of tune determination for a hypothetical set of alignment errors.

  19. 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.

  20. Estimation of Eruption Source Parameters from Plume Growth Rate

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  1. 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.

  2. 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.

  3. 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.

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

    PubMed

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

    2016-07-01

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

  5. 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. PMID:25907061

  6. 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.

  7. Stationary Vortices in Karman Grooves. I.Vortex Growth Rate

    NASA Astrophysics Data System (ADS)

    Balle, Gregory J.; Kier, Thiemo M.; Breidenthal, Robert E.

    1999-11-01

    The effect of a stationary vortex on wall fluxes in turbulent flow is predicted by the vortex persistence theory of turbulence. As a first step to test the theory, the feasibility of holding a vortex sufficiently stationary whilst embedded in a turbulent boundary layer is investi gated. Exploiting the stationarity of von Karman vortices in a wake, the dividing stream line is replaced by a wavy wall. Vortex generators are accurately positioned in the valleys (the "Karman grooves") so that the resulting streamwise vortices correspond to those in the vortex street. Complex potential theory predicts stationary points for such vortices, while there are no such points near a flat wall. Flow visualization experiments explore the basic properties of these vortices. In comparison to vortices near a flat plate, the growth rate of the stationary vortex in a Karman groove is reduced dramatically, i.e. by about an order of magnitude. This is consistent with the idea that the stationarity, persistence and growth rate of a turbulent vortex are intimately linked. Passive control of near-wall stream wise vortices is demonstrated, a foundation for the next step, measurement of a wall flux.

  8. Damage segregation at fissioning may increase growth rates

    PubMed Central

    Evans, Steven N.; Steinsaltz, David

    2007-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Jennings, Elise; Jennings, David

    2015-06-01

    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 = nabla \\cdot 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 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) for k < 0.1 h Mpc-1. 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. 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. 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.

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

    PubMed

    Lough, Janice M; Cantin, Neal E

    2014-06-01

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

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

    DOE PAGESBeta

    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

  13. The Use of Growth Factors and Other Humoral Agents to Accelerate and Enhance Burn Wound Healing

    PubMed Central

    Ching, Yiu-Hei; Sutton, Thomas L.; Pierpont, Yvonne N.; Robson, Martin C.; Payne, Wyatt G.

    2011-01-01

    Objective: Certain cytokines, especially those known as growth factors, have been demonstrated to mediate or modulate burn wound healing. Experimental and clinical evidence suggests that there are therapeutic advantages to the wound healing process when these agents are utilized. Positive effects have been reported for 4 types of wounds seen in the burn patient: partial-thickness wounds, full-thickness wounds, interstices of meshed skin grafts, and skin graft donor sites. Methods: A comprehensive literature search was performed using the MEDLINE, Ovid, and Web of Science databases to identify pertinent articles regarding growth factors and other cytokines in burns and wound healing. Results: The current knowledge about cytokine growth factors and their potential therapeutic applications in burn wound healing are discussed and reviewed. Conclusions: Platelet-derived growth factor, fibroblast growth factors, epidermal growth factors, transforming growth factor alpha, vascular endothelial growth factor, insulin-like growth factor I, nerve growth factor, transforming growth factor beta, granulocyte-macrophage colony-stimulating factor, and amnion-derived cellular cytokine solution have all been suggested to enhance the rate and quality of healing in 1 or more of these wounds encountered in burn care. PMID:22084646

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

    NASA Astrophysics Data System (ADS)

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

    2000-01-01

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

  15. 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.

  16. 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

  17. 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…

  18. 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. PMID:21147211

  19. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    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.

  1. 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.

  2. 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

  3. A role for pectin de-methylesterification in a developmentally regulated growth acceleration in dark-grown Arabidopsis hypocotyls.

    PubMed

    Pelletier, Sandra; Van Orden, Jürgen; Wolf, Sebastian; Vissenberg, Kris; Delacourt, Julien; Ndong, Yves Assoumou; Pelloux, Jérôme; Bischoff, Volker; Urbain, Aurélie; Mouille, Grégory; Lemonnier, Gaëtan; Renou, Jean-Pierre; Höfte, Herman

    2010-11-01

    • We focused on a developmentally regulated growth acceleration in the dark-grown Arabidopsis hypocotyl to study the role of changes in cell wall metabolism in the control of cell elongation. • To this end, precise transcriptome analysis on dissected dark-grown hypocotyls, Fourier transform infrared (FT-IR) microspectroscopy and kinematic analysis were used. • Using a cellulose synthesis inhibitor, we showed that the growth acceleration marks a developmental transition during which growth becomes uncoupled from cellulose synthesis. We next investigated the cellular changes that take place during this transition. FT-IR microspectroscopy revealed significant changes in cell wall composition during, but not after, the growth acceleration. Transcriptome analysis suggested a role for cell wall remodeling, in particular pectin modification, in this growth acceleration. This was confirmed by the overexpression of a pectin methylesterase inhibitor, which caused a delay in the growth acceleration. • This study shows that the acceleration of cell elongation marks a developmental transition in dark-grown hypocotyl cells and supports a role for pectin de-methylesterification in the timing of this event. PMID:20819179

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

    PubMed

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

    2013-05-17

    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(-)]/[Zn(2+)] = 1.5 and pH=  4.8 ± 0.1. This film shows >80% optical transmittance and a field-effect mobility of 2.730 cm(2) V(-1) s(-1) at zero back-gate bias. PMID:23595114

  5. Accelerated fracture healing in transgenic mice overexpressing an anabolic isoform of fibroblast growth factor 2.

    PubMed

    Hurley, Marja M; Adams, Douglas J; Wang, Liping; Jiang, Xi; Burt, Patience Meo; Du, Erxia; Xiao, Liping

    2016-03-01

    The effect of targeted expression of an anabolic isoform of basic fibroblast growth factor (FGF2) in osteoblastic lineage on tibial fracture healing was assessed in mice. Closed fracture of the tibiae was performed in Col3.6-18 kDaFgf2-IRES-GFPsaph mice in which a 3.6 kb fragment of type I collagen promoter (Col3.6) drives the expression of only the 18 kD isoform of FGF2 (18 kDaFgf2/LMW) with green fluorescent protein-sapphire (GFPsaph) as well as Vector mice (Col3.6-IRES-GFPsaph, Vector) that did not harbor the FGF2 transgene. Radiographic, micro-CT, DEXA, and histologic analysis of fracture healing of tibiae harvested at 3, 10 and 20 days showed a smaller fracture callus but accelerated fracture healing in LMWTg compared with Vector mice. At post fracture day 3, FGF receptor 3 and Sox 9 mRNA were significantly increased in LMWTg compared with Vector. Accelerated fracture healing was associated with higher FGF receptor 1, platelet derived growth factors B, C, and D, type X collagen, vascular endothelial cell growth factor, matrix metalloproteinase 9, tartrate resistant acid phosphatase, cathepsin K, runt-related transcription factor-2, Osterix and Osteocalcin and lower Sox9, and type II collagen expression at 10 days post fracture. We postulate that overexpression of LMW FGF2 accelerated the fracture healing process due to its effects on factors that are important in chondrocyte and osteoblast differentiation and vascular invasion. PMID:26252425

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

    PubMed

    Houghton, Jennie; Thompson, Ken; Rees, Mark

    2013-07-01

    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. PMID:23677351

  7. Accelerated evolutionary rate in sulfur-oxidizing endosymbiotic bacteria associated with the mode of symbiont transmission.

    PubMed

    Peek, A S; Vrijenhoek, R C; Gaut, B S

    1998-11-01

    The nearly neutral theory of molecular evolution predicts that the rate of nucleotide substitution should accelerate in small populations at sites under low selective constraint. We examined these predictions with respect to the relative population sizes for three bacterial life histories within chemolithoautotrophic sulfur-oxidizing bacteria: (1) free-living bacteria, (2) environmentally captured symbionts, and (3) maternally transmitted symbionts. Both relative rates of nucleotide substitution and relative ratios of loop, stem, and domain substitutions from 1,165 nt of the small-subunit 16S rDNA were consistent with expectations of the nearly neutral theory. Relative to free-living sulfur-oxidizing autotrophic bacteria, the maternally transmitted symbionts have faster substitution rates overall and also in low-constraint domains of 16S rDNA. Nucleotide substitition rates also differ between loop and stem positions. All of these findings are consistent with the predictions that these symbionts have relatively small effective population sizes. In contrast, the rates of nucleotide substitution in environmentally captured symbionts are slower, particularly in high-constraint domains, than in free-living bacteria. PMID:12572615

  8. Extended Simulations of Graphene Growth with Updated Rate Coefficients

    SciTech Connect

    Whitesides, R; You, X; Frenklach, M

    2010-03-18

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

  9. Carbon dioxide limitation of marine phytoplankton growth rates

    NASA Astrophysics Data System (ADS)

    Riebesell, U.; Wolf-Gladrow, D. A.; Smetacek, V.

    1993-01-01

    THE supply of dissolved inorganic carbon (DIC) is not considered to limit oceanic primary productivity1, as its concentration in sea water exceeds that of other plant macronutrients such as nitrate and phosphate by two and three orders of magnitude, respectively. But the bulk of oceanic new production2 and a major fraction of vertical carbon flux is mediated by a few diatom genera whose ability to use DIG components other than CO2, which comprises < 1% of total DIC3, is unknown4. Here we show that under optimal light and nutrient conditions, diatom growth rate can in fact be limited by the supply of CO2. The doubling in surface water pCO2 levels since the last glaciation from 180 to 355 p.p.m.5,6 could therefore have stimulated marine productivity, thereby increasing oceanic carbon sequestration by the biological pump.

  10. Instability growth patterns of a shock-accelerated thin fluid layer

    SciTech Connect

    Jacobs, J.W. ); Klein, D.L.; Jenkins, D.G.; Benjamin, R.F. )

    1993-02-01

    Laser-induced fluorescence imaging of a shock-accelerated thin gas layer, produced by a planar SF[sub 6] jet in air, shows multiple flow evolutions. Richtmyer-Meshkov instability causes spatially periodic perturbations initially imposed on the jet to develop into one of three distinct flow patterns, indicating nonlinear instability growth. Slight differences in the vorticity distribution deposited on the air-SF[sub 6] interfaces by the shock interaction produce a bifurcated flow, observed as mushroom-shaped or sinuous-shaped interfacial patterns.

  11. In-Situ Monitoring of Particle Growth at PEMFC Cathode under Accelerated Cycling Conditions

    SciTech Connect

    Redmond, Erin L.; Setzler, Brian P.; Juhas, Pavol; Billinge, Simon J.L.; Fuller, Thomas F.

    2012-10-25

    An in-situ method to measure changes in catalyst particle size at the cathode of a proton exchange membrane fuel cell is demonstrated. Synchrotron X-rays, 58 keV, were used to measure the pair distribution function on an operating fuel cell and observe the growth of catalyst particles under accelerated degradation conditions. The stability of Pt/C and PtCo/C with different initial particle sizes was monitored over 3000 potential cycles. The increase in particle size was fit to a linear trend as a function of cycles. The most stable electrocatalyst was found to be the alloyed PtCo with the larger initial particle size.

  12. Aerosol observations and growth rates in the tropical tropopause layer

    NASA Astrophysics Data System (ADS)

    Waddicor, D. A.; Vaughan, G.; Choularton, T. W.; Bower, K. N.; Coe, H.; Gallagher, M.; Williams, P. I.; Flynn, M.; Volz-Thomas, A.; Pätz, W.; Isaac, P.; Hacker, J.; Arnold, F.; Schlager, H.; Whiteway, J. A.

    2012-01-01

    We present a case study of Aitken and accumulation mode aerosol observed downwind of the anvils of deep tropical thunderstorms. The measurements were made by condensation nuclei counters flown on the Egrett high-altitude aircraft from Darwin during the ACTIVE campaign, in monsoon conditions producing widespread convection over land and ocean. Maximum measured concentrations of aerosol in the size range 10-100 nm were 25 000 cm-3 STP. By calculating back-trajectories from the observations, and projecting on to infrared satellite images, the time since the air exited cloud was estimated. In this way a time scale of ~ 3-4 h was derived for the 10-100 nm aerosol concentration to reach its peak. We examine the hypothesis that the growth in aerosol concentrations can be explained by production of sulphuric acid from SO2 followed by particle nucleation and coagulation. Estimates of the sulphuric acid production rate show that the observations are only consistent with this hypothesis if the particles coagulate to sizes > 10 nm much more quickly than is suggested by current theory. Alternatively, other condensible gases (possibly organic) drive the growth of aerosol particles in the TTL.

  13. 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.

  14. Error Growth Rate in the MM5 Model

    NASA Astrophysics Data System (ADS)

    Ivanov, S.; Palamarchuk, J.

    2006-12-01

    The goal of this work is to estimate model error growth rates in simulations of the atmospheric circulation by the MM5 model all the way from the short range to the medium range and beyond. The major topics are addressed to: (i) search the optimal set of parameterization schemes; (ii) evaluate the spatial structure and scales of the model error for various atmospheric fields; (iii) determine geographical regions where model errors are largest; (iv) define particular atmospheric patterns contributing to the fast and significant model error growth. Results are presented for geopotential, temperature, relative humidity and horizontal wind components fields on standard surfaces over the Atlantic-European region during winter 2002. Various combinations of parameterization schemes for cumulus, PBL, moisture and radiation are used to identify which one provides a lesser difference between the model state and analysis. The comparison of the model fields is carried out versus ERA-40 reanalysis of the ECMWF. Results show that the rate, at which the model error grows as well as its magnitude, varies depending on the forecast range, atmospheric variable and level. The typical spatial scale and structure of the model error also depends on the particular atmospheric variable. The distribution of the model error over the domain can be separated in two parts: the steady and transient. The first part is associated with a few high mountain regions including Greenland, where model error is larger. The transient model error mainly moves along with areas of high gradients in the atmospheric flow. Acknowledgement: This study has been supported by NATO Science for Peace grant #981044. The MM5 modelling system used in this study has been provided by UCAR. ERA-40 re-analysis data have been obtained from the ECMWF data server.

  15. 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

  16. 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.

  17. 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. PMID:18252662

  18. High rates of carbon storage in old deciduous forests: Emerging mechanisms from the Forest Accelerated Succession ExperimenT (FASET)

    NASA Astrophysics Data System (ADS)

    Gough, C. M.; Nave, L. E.; Hardiman, B. S.; Bohrer, G.; Halperin, A.; Maurer, K.; Le Moine, J.; Nadelhoffer, K.; Vogel, C. S.; Curtis, P.; University Of Michigan Biological Station Forest Ecosystem Study (Umbs-Fest) Team

    2010-12-01

    Deciduous forests of the eastern US are broadly approaching an ecological threshold in which early successional dominant trees are senescing and giving way to later successional species, with unknown consequences for regional carbon (C) cycling. Though recent research demonstrates that forests may accumulate C for centuries, the mechanisms behind sustained rates of C storage in old, particularly deciduous, forests have not been identified. In a regionally representative forest at the University of Michigan Biological Station, we are combining observational and experimental C cycling studies to forecast how forest C storage responds to climate variation, disturbance, and succession. The Forest Accelerated Succession ExperimenT (FASET), in which >6,700 aspen and birch trees (~35 % LAI) were stem girdled within a 39 ha area, is testing the hypothesis that forest production will increase rather than decline with age, due to increases in nitrogen (N) availability, N allocation to the canopy, and the concurrent development of a more biologically and structurally complex canopy. Results thus far support our hypothesis that aging forests in the region may sustain high rates of C storage through shifts in N cycling and increased canopy complexity. Girdling-induced mortality of early successional species reduced soil respiration, accelerated fine root turnover, and prompted the redistribution of N from the foliage of early to later successional species. Nitrogen redistribution increased leaf area index (LAI) production by later successional species, offsetting declines in LAI from senescing early successional species. High rates of net primary production (NPP) were sustained in stands comprising a diverse assemblage of early and later successional species because later successional species, when already present in the canopy, rapidly compensated for declining growth of early successional species. Canopy structural complexity, which increased with forest age, was positively

  19. 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. PMID:24932606

  20. 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.

  1. 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. PMID:24888684

  2. 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. PMID:22194939

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

    NASA Astrophysics Data System (ADS)

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

    2006-09-01

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

  4. RPRD1B promotes tumor growth by accelerating the cell cycle in endometrial cancer.

    PubMed

    Wang, Yuan; Qiu, Haifeng; Hu, Weixu; Li, Shaoru; Yu, Jinjin

    2014-03-01

    RPRD1B, the regulation of nuclear pre-mRNA domain containing 1B gene, functions as a cell cycle manipulator and has been found overexpressed in a small panel of endometrial cancer types. In the present study, we investigated the roles of RPRD1B in endometrial cancer using various in vitro and in vivo experiments. According to our results, RPRD1B mRNA was significantly upregulated in endometrial cancer tissues (P=0.0012). RPRD1B overexpression was correlated with tumor stage (P=0.0004), histology type (P=0.0146) and depth of myometrial invasion (P=0.024). In vitro, RPRD1B promoted cellular proliferation (P=0.032 for MTT assay and P=0.018 for colony formation assay), and accelerated the cell cycle (P=0.007) by upregulating cyclin D1, CDK4 and CDK6, while knockdown of RPRD1B suppressed cellular proliferation (P=0.02 for MTT assay and P=0.031 for colony formation assay), and led to G1 phase arrest (P=0.025) through downregulating cyclin D1, CDK4 and CDK6. Consistently, in the nude mice model, RPRD1B overexpression significantly accelerated the tumor xenograft growth (P=0.0012), accompanied by elevated Ki-67 and cyclin D1. In addition, we demonstrated that downregulating RPRD1B could sensitize Ishikawa cells to Raloxifene (P=0.01). In summary, we demonstrated that RPRD1B was frequently overexpressed in human endometrial cancer. Both in vitro and in vivo, over-abundant RPRD1B could promote tumor growth and accelerate cellular cell cycle. In addition, knockdown of RPRD1B also increased cell sensitivity to Raloxifene, making RPRD1B a potent therapeutic target for endometrial cancer, particularly in patients with resistance to the selective ER modulators. PMID:24452636

  5. Accelerating axonal growth promotes motor recovery after peripheral nerve injury in mice

    PubMed Central

    Ma, Chi Him Eddie; Omura, Takao; Cobos, Enrique J.; Latrémolière, Alban; Ghasemlou, Nader; Brenner, Gary J.; van Veen, Ed; Barrett, Lee; Sawada, Tomokazu; Gao, Fuying; Coppola, Giovanni; Gertler, Frank; Costigan, Michael; Geschwind, Dan; Woolf, Clifford J.

    2011-01-01

    Although peripheral nerves can regenerate after injury, proximal nerve injury in humans results in minimal restoration of motor function. One possible explanation for this is that injury-induced axonal growth is too slow. Heat shock protein 27 (Hsp27) is a regeneration-associated protein that accelerates axonal growth in vitro. Here, we have shown that it can also do this in mice after peripheral nerve injury. While rapid motor and sensory recovery occurred in mice after a sciatic nerve crush injury, there was little return of motor function after sciatic nerve transection, because of the delay in motor axons reaching their target. This was not due to a failure of axonal growth, because injured motor axons eventually fully re-extended into muscles and sensory function returned; rather, it resulted from a lack of motor end plate reinnervation. Tg mice expressing high levels of Hsp27 demonstrated enhanced restoration of motor function after nerve transection/resuture by enabling motor synapse reinnervation, but only within 5 weeks of injury. In humans with peripheral nerve injuries, shorter wait times to decompression surgery led to improved functional recovery, and, while a return of sensation occurred in all patients, motor recovery was limited. Thus, absence of motor recovery after nerve damage may result from a failure of synapse reformation after prolonged denervation rather than a failure of axonal growth. PMID:21965333

  6. Human microRNAs originated from two periods at accelerated rates in mammalian evolution.

    PubMed

    Iwama, Hisakazu; Kato, Kiyohito; Imachi, Hitomi; Murao, Koji; Masaki, Tsutomu

    2013-03-01

    MicroRNAs (miRNAs) are short, noncoding RNAs that modulate genes posttranscriptionally. Frequent gains and losses of miRNA genes have been reported to occur during evolution. However, little is known systematically about the periods of evolutionary origin of the present miRNA gene repertoire of an extant mammalian species. Thus, in this study, we estimated the evolutionary periods during which each of 1,433 present human miRNA genes originated within 15 periods, from human to platypus-human common ancestral branch and a class "conserved beyond theria," primarily using multiple genome alignments of 38 species, plus the pairwise genome alignments of five species. The results showed two peak periods in which the human miRNA genes originated at significantly accelerated rates. The most accelerated rate appeared in the period of the initial phase of hominoid lineage, and the second appeared shortly before Laurasiatherian divergence. Approximately 53% of the present human miRNA genes have originated within the simian lineage to human. In particular, approximately 28% originated within the hominoid lineage. The early phase of placental mammal radiation comprises approximately 28%, while no more than 15% of human miRNAs have been conserved beyond placental mammals. We also clearly showed a general trend, in which the miRNA expression level decreases as the miRNA becomes younger. Intriguingly, amid this decreasing trend of expression, we found one significant rise in the expression level that corresponded to the initial phase of the hominoid lineage, suggesting that increased functional acquisitions of miRNAs originated at this particular period. PMID:23171859

  7. 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...

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

    USGS Publications Warehouse

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

    2006-01-01

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

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

    SciTech Connect

    Pirjol, Dan

    2014-08-01

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

  10. Accelerated Testing Methodology for the Determination of Slow Crack Growth of Advanced Ceramics

    NASA Technical Reports Server (NTRS)

    Choi, Sung R.; Salem, Jonathan A.; Gyekenyesi, John P.

    1997-01-01

    Constant stress-rate (dynamic fatigue) testing has been used for several decades to characterize slow crack growth behavior of glass and ceramics at both ambient and elevated temperatures. The advantage of constant stress-rate testing over other methods lies in its simplicity: Strengths are measured in a routine manner at four or more stress rates by applying a constant crosshead speed or constant loading rate. The slow crack growth parameters (n and A) required for design can be estimated from a relationship between strength and stress rate. With the proper use of preloading in constant stress-rate testing, an appreciable saving of test time can be achieved. If a preload corresponding to 50 % of the strength is applied to the specimen prior to testing, 50 % of the test time can be saved as long as the strength remains unchanged regardless of the applied preload. In fact, it has been a common, empirical practice in strength testing of ceramics or optical fibers to apply some preloading (less then 40%). The purpose of this work is to study the effect of preloading on the strength to lay a theoretical foundation on such an empirical practice. For this purpose, analytical and numerical solutions of strength as a function of preloading were developed. To verify the solution, constant stress-rate testing using glass and alumina at room temperature and alumina silicon nitride, and silicon carbide at elevated temperatures was conducted in a range of preloadings from O to 90 %.

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

    SciTech Connect

    Kheiri, Golshad; Esmaeilzadeh, Mahdi

    2013-12-15

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

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

    SciTech Connect

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

    1998-09-01

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

  13. 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.

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

    PubMed

    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; Brindley, Paul J; Loukas, Alex

    2015-10-01

    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. 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

  16. Effect of Tides On Sea Ice Deformation and Growth Rate

    NASA Astrophysics Data System (ADS)

    Hutchings, J.; Heil, P.; Hibler, W. D.

    Due to high ice strength in present formulations of non-linear plastic sea ice dynamic models, the relatively small tides in the Arctic Basin produces little relative motion. However, recent work with a stand alone sea ice model including a more realistic for- mulation of ice-ocean coupling [Heil & Hibler, accepted] has produced more realistic inertial motion in agreement with observations. With such improved model physics, we expect tidal motion of the ice pack to have a more pronounced effect on simulated periodic lead opening and closing, enhancing winter ice growth rate. To investigate this process, tidal forcing [Kowalik 1998] is included in the momentum balance of a stand alone sea ice model [Heil & Hibler, accepted]. The model includes a modi- fied coulombic rheology, hourly interpolated NCEP reanalysis atmospheric forcing, climatological cloud fraction [Gorshkov,1980] , oceanic currents and heat flux from Polyakov et al. [1998] and inertial embedding as Hibler et al. [1998]. Arctic sea ice is simulated for the period 1948-2000 and compared to a control without tidal forcing. It is investigated how tidal motion and inertial motion interact. As the inertial period is close to the major semi-diurnal tidal period we expect ice deformation in tidally active regions (such as the Barents Sea) to be amplified through inertial resonance. The tidal influence on ice mass balance is estimated. The interannual variability of ice mass is examined to show how tidal influence differs between years of high Arctic Oscillation (AO) index, when ice divergence is increased and trans-polar transport widened, and low AO index, when the Arctic high dominates and convergent motion prevails.

  17. 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

  18. Implications of a concentration-dependent growth rate on the boundary layer crystal-melt model

    NASA Astrophysics Data System (ADS)

    Lasaga, Antonio C.

    1981-12-01

    The influence of a melt boundary layer on crystal growth is analyzed. The treatment extends the results of Burton, Prim and Slichter (1953) and incorporates composition-dependent growth rates. It is shown that in these general cases the growth rate cannot be arbitrarily fixed but must satisfy a self-consistent equation. Self-consistency problems arise because the growth rate determines the composition profile in the melt and, in turn, the composition profile determines the growth rate. The self-consistent growth rate is shown to vary markedly with the ratio δ/D, where δ is the thickness of the boundary layer and D is the appropriate diffusion coefficient in the melt. This self-consistency can be very important in the analysis of both field and laboratory growth rates as well as in trace element partition kinetic models.

  19. A study of the growth rate of GaSb using TEGa and TMSb or TESb

    NASA Astrophysics Data System (ADS)

    Bhat, Rajaram; Caneau, Catherine G.

    2015-09-01

    The growth rate of gallium antimonide using triethylgallium and either trimethylantimony or triethylantimony has been studied over a wide temperature range, from 475 to 675 °C. In contrast to earlier reports of the growth being diffusion controlled when trimethylantimony is used, we find that it is kinetically controlled at temperatures below 650 °C. The growth rate of gallium antimonide when trietylantimony is used varies in a complex way with temperature but is ultimately diffusion controlled above 650 °C, with both trimethylantimony and triethylantimony yielding the same growth rate. For comparison, the growth rate of gallium arsenide was studied with triethylgallium and arsine or tertiarybutylarsine, and with trimethylgallium and arsine: in both case, it is diffusion controlled in the entire temperature range studied. However, the diffusion controlled growth rate of gallium antimonide predicted from the gallium arsenide growth rate is lower than what is experimentally observed.

  20. Growth Rate of Bumblebee Larvae is Related to Pollen Amino Acids.

    PubMed

    Moerman, Romain; Vanderplanck, Maryse; Roger, Nathalie; Declèves, Sylvain; Wathelet, Bernard; Rasmont, Pierre; Fournier, Denis; Michez, Denis

    2016-02-01

    The use of Bombus terrestris L. commercial colonies for outdoor and greenhouse crop pollination is currently widespread. Colony breeding includes bumblebee feeding, mostly by using the honeybee pollen loads of diverse palynological composition. Because the chemical content of pollen is highly variable, the choice of commercial blend should not be random but has to be carefully selected to ensure the optimal development of workers and then pollination efficacy. In this work, we compared the impact of three common commercial blends on the development of bumblebee microcolonies, namely, Actinidia deliciosa L., Cistus sp., and Salix sp. We focus on amino acids (i.e., composition and amount), as they are currently used as an indicator of diet performance. Five parameters were used to determine microcolonies growth rate: 1) number of eggs, 2) number of alive larvae, 3) number of ejected larvae, 4) number of pupae, and 5) total number of offspring. Syrup collection was also monitored to estimate energetic requirement for colony growth. Results revealed that the three commercial blends chemically differed in their amino acid contents, with those displaying higher concentrations (i.e., Salix sp. and A. deliciosa) accelerating microcolony development along with an increase of syrup collection. The advantages of rearing bumblebee commercial colonies using a pollen diet with an optimal amino acid content are discussed. PMID:26385047

  1. 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.

  2. 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.

  3. Accelerated Testing Methodology Developed for Determining the Slow Crack Growth of Advanced Ceramics

    NASA Technical Reports Server (NTRS)

    Choi, Sung R.; Gyekenyesi, John P.

    1998-01-01

    Constant stress-rate ("dynamic fatigue") testing has been used for several decades to characterize the slow crack growth behavior of glass and structural ceramics at both ambient and elevated temperatures. The advantage of such testing over other methods lies in its simplicity: strengths are measured in a routine manner at four or more stress rates by applying a constant displacement or loading rate. The slow crack growth parameters required for component design can be estimated from a relationship between strength and stress rate. With the proper use of preloading in constant stress-rate testing, test time can be reduced appreciably. If a preload corresponding to 50 percent of the strength is applied to the specimen prior to testing, 50 percent of the test time can be saved as long as the applied preload does not change the strength. In fact, it has been a common, empirical practice in the strength testing of ceramics or optical fibers to apply some preloading (<40 percent). The purpose of this work at the NASA Lewis Research Center is to study the effect of preloading on measured strength in order to add a theoretical foundation to the empirical practice.

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

    PubMed

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

    2015-01-01

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

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

    PubMed

    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

  6. 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

  7. Sulforaphane promotes murine hair growth by accelerating the degradation of dihydrotestosterone.

    PubMed

    Sasaki, Mari; Shinozaki, Shohei; Shimokado, Kentaro

    2016-03-25

    Dihydrotestosterone (DHT) causes the regression of human hair follicles in the parietal scalp, leading to androgenic alopecia (AGA). Sulforaphane (SFN) increases the expression of DHT degrading enzymes, such as 3α-hydroxysteroid dehydrogenases (3α-HSDs), and, therefore, SFN treatment may improve AGA. To determine the effects of SFN on hair growth, we administered SFN (10 mg/kg BW, IP) or vehicle (DMSO) to ob/ob mice for six weeks and examined hair regeneration and the plasma levels of testosterone and DHT. We also tested the effects of SFN on the expression of two forms of 3α-HSD, aldo-keto reductase 1c21 and dehydrogenase/reductase (SDR family) member 9, both in vitro and in vivo. SNF significantly enhanced hair regeneration in ob/ob mice. The mice treated with SFN showed lower plasma levels of testosterone and DHT than those treated with vehicle. SFN increased the mRNA and protein levels of the two forms of 3α-HSD in the liver of the mice and in cultured murine hepatocyte Hepa1c1c7 cells. These results suggest that SFN treatment increases the amount of 3α-HSDs in the liver, accelerates the degradation of blood DHT, and subsequently blocks the suppression of hair growth by DHT. PMID:26923074

  8. Rate-related accelerating (autodecremental) atrial pacing for reversion of paroxysmal supraventricular tachycardia.

    PubMed

    Nathan, A; Hellestrand, K; Ward, D; Spurrell, R; Camm, J

    1982-01-01

    Twenty consecutive patients with paroxysmal intra A-V nodal or atrio-ventricular tachycardia had a new tachycardia reversion pacing modality evaluated during routine electrophysiological study. The pacing was controlled by a micropressor interfaced with a stimulator connected to a right atrial pacing electrode. On detection of tachycardia the first pacing cycle interval is equal to the tachycardia cycle length minus a decrement value D. Each subsequent pacing cycle is further reduced by the same value of D, thus accelerating the pacing burst until a plateau of 100 beats/min faster than tachycardia (with an absolute lower limit of 275 beats/min) is reached. Seven different values of D (2, 4, 8, 16, 24, 34, 50 msec) were assessed in combination with three different durations of pacing P (500, 5000 msec). With P:500, only 2/20 tachycardias were terminated, but with P:1000, 16/20 were terminated. With P:5000 all were terminated and the combination successful in all patients was P:5000 and D:16. No unwanted arrhythmias were induced. In contrast, competitive constant rate overdrive atrial pacing accomplished tachycardia termination in all cases, but in four instances resulted in atrial flutter or fibrillation. Autodecremental pacing, which tends to avoid stimulation in the vulnerable period, allowed safe and successful termination of all tachycardias evaluated in this study. PMID:7069321

  9. 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

    2011-04-01

    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. PMID:21364260

  10. Thermal runaway features of large format prismatic lithium ion battery using extended volume accelerating rate calorimetry

    NASA Astrophysics Data System (ADS)

    Feng, Xuning; Fang, Mou; He, Xiangming; Ouyang, Minggao; Lu, Languang; Wang, Hao; Zhang, Mingxuan

    2014-06-01

    In this paper, the thermal runaway features of a 25 Ah large format prismatic lithium ion battery with Li(NixCoyMnz)O2 (NCM) cathode are evaluated using the extended volume-accelerating rate calorimetry (EV-ARC). 4 thermocouples are set at different positions of the battery. The temperature inside the battery is 870 °C or so, much higher than that outside the battery. The temperature difference is calculated from the recorded data. The temperature difference within the battery stays lower than 1 °C for 97% of the test period, while it rises to its highest, approximately 520 °C, when thermal runaway happens. The voltage of the battery is also measured during the test. It takes 15-40 s from the sharp drop of voltage to the instantaneous rise of temperature. Such a time interval is beneficial for early warning of the thermal runaway. Using a pulse charge/discharge profile, the internal resistance is derived from the quotient of the pulse voltage and the current during the ARC test. The internal resistance of the battery increases slowly from 20 mΩ to 60 mΩ before thermal runaway, while it rises to 370 mΩ when thermal runaway happens indicating the loss of the integrity of the separator or the battery swell.

  11. The neurotransmitters serotonin and glutamate accelerate the heart rate of the mosquito Anopheles gambiae.

    PubMed

    Hillyer, Julián F; Estévez-Lao, Tania Y; Mirzai, Homa E

    2015-10-01

    Serotonin and glutamate are neurotransmitters that in insects are involved in diverse physiological processes. Both serotonin and glutamate have been shown to modulate the physiology of the dorsal vessel of some insects, yet until the present study, their activity in mosquitoes remained unknown. To test whether serotonin or glutamate regulate dorsal vessel physiology in the African malaria mosquito, Anopheles gambiae, live mosquitoes were restrained, and a video of the contracting heart (the abdominal portion of the dorsal vessel) was acquired. These adult female mosquitoes were then injected with various amounts of serotonin, glutamate, or a control vehicle solution, and additional videos were acquired at 2 and 10 min post-treatment. Comparison of the videos taken before and after treatment revealed that serotonin accelerates the frequency of heart contractions, with the cardioacceleration being significantly more pronounced when the wave-like contractions of cardiac muscle propagate in the anterograde direction (toward the head). Comparison of the videos taken before and after treatment with glutamate revealed that this molecule is also cardioacceleratory. However, unlike serotonin, the activity of glutamate does not depend on whether the contractions propagate in the anterograde or the retrograde (toward the posterior of the abdomen) directions. Serotonin or glutamate induces a minor change or no change in the percentage of contractions and the percentage of the time that the heart contracts in the anterograde or the retrograde directions. In summary, this study shows that the neurotransmitters serotonin and glutamate increase the heart contraction rate of mosquitoes. PMID:26099947

  12. 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.

  13. 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.

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

    PubMed

    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

  15. 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

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

    USGS Publications Warehouse

    Ton, Riccardo; Martin, Thomas E.

    2015-01-01

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

  17. Simulation of sandsage-bluestem forage growth under varying stocking rates

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of stocking rate on forage growth has attracted a great deal of research attention in forage science. Findings show that forage growth may be affected by stocking rate and there is the consensus that high stocking rates lead to soil compaction, which could also in turn affect forage growt...

  18. 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

  19. 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.

  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. Growth rates of gibbsite single crystals determined using in situ optical microscopy

    NASA Astrophysics Data System (ADS)

    Lee, Mei-yin; Parkinson, Gordon M.

    1999-03-01

    Although the crystallization of gibbsite via the Bayer process is an established industry, the mechanism by which gibbsite crystallizes is not well understood. In the microscopic investigation of gibbsite crystal growth, the phenomenon of growth rate dispersion was observed. The study of the growth rate dependence on supersaturation showed that growth of the prismatic faces is occurring via a spiral growth mechanism. In the case of the basal face, above a relative supersaturation of 0.67, birth and spread is the principal mechanism operating, while spiral growth is the major mechanism operating below a relative supersaturation of 0.67.

  2. Changes of deceleration and acceleration capacity of heart rate in patients with acute hemispheric ischemic stroke

    PubMed Central

    Xu, Yan-Hong; Wang, Xing-De; Yang, Jia-Jun; Zhou, Li; Pan, Yong-Chao

    2016-01-01

    Background and purpose Autonomic dysfunction is common after stroke, which is correlated with unfavorable outcome. Phase-rectified signal averaging is a newly developed technique for assessing cardiac autonomic function, by detecting sympathetic and vagal nerve activity separately through calculating acceleration capacity (AC) and deceleration capacity (DC) of heart rate. In this study, we used this technique for the first time to investigate the cardiac autonomic function of patients with acute hemispheric ischemic stroke. Methods A 24-hour Holter monitoring was performed in 63 patients with first-ever acute ischemic stroke in hemisphere and sinus rhythm, as well as in 50 controls with high risk of stroke. DC, AC, heart rate variability parameters, standard deviation of all normal-to-normal intervals (SDNN), and square root of the mean of the sum of the squares of differences between adjacent normal-to-normal intervals (RMSSD) were calculated. The National Institutes of Health Stroke Scale (NIHSS) was used to assess the severity of stroke. We analyzed the changes of DC, AC, SDNN, and RMSSD and also studied the correlations between these parameters and NIHSS scores. Results The R–R (R wave to R wave on electrocardiogram) intervals, DC, AC, and SDNN in the cerebral infarction group were lower than those in controls (P=0.003, P=0.002, P=0.006, and P=0.043), but the difference of RMSSD and the D-value and ratio between absolute value of AC (|AC|) and DC were not statistically significant compared with those in controls. The DC of the infarction group was significantly correlated with |AC|, SDNN, and RMSSD (r=0.857, r=0.619, and r=0.358; P=0.000, P=0.000, and P=0.004). Correlation analysis also showed that DC, |AC|, and SDNN were negatively correlated with NIHSS scores (r=−0.279, r=−0.266, and r=−0.319; P=0.027, P=0.035, and P=0.011). Conclusion Both DC and AC of heart rate decreased in patients with hemispheric infarction, reflecting a decrease in both vagal

  3. 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.

  4. 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…

  5. 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.

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

    NASA Astrophysics Data System (ADS)

    Hansen, James; Kharecha, Pushker; Sato, Makiko

    2013-03-01

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

  7. Rapid warming accelerates tree growth decline in semi-arid forests of Inner Asia.

    PubMed

    Liu, Hongyan; Park Williams, A; Allen, Craig D; Guo, Dali; Wu, Xiuchen; Anenkhonov, Oleg A; Liang, Eryuan; Sandanov, Denis V; Yin, Yi; Qi, Zhaohuan; Badmaeva, Natalya K

    2013-08-01

    Forests around the world are subject to risk of high rates of tree growth decline and increased tree mortality from combinations of climate warming and drought, notably in semi-arid settings. Here, we assess how climate warming has affected tree growth in one of the world's most extensive zones of semi-arid forests, in Inner Asia, a region where lack of data limits our understanding of how climate change may impact forests. We show that pervasive tree growth declines since 1994 in Inner Asia have been confined to semi-arid forests, where growing season water stress has been rising due to warming-induced increases in atmospheric moisture demand. A causal link between increasing drought and declining growth at semi-arid sites is corroborated by correlation analyses comparing annual climate data to records of tree-ring widths. These ring-width records tend to be substantially more sensitive to drought variability at semi-arid sites than at semi-humid sites. Fire occurrence and insect/pathogen attacks have increased in tandem with the most recent (2007-2009) documented episode of tree mortality. If warming in Inner Asia continues, further increases in forest stress and tree mortality could be expected, potentially driving the eventual regional loss of current semi-arid forests. PMID:23564688

  8. Growth-rate dependent global effects on gene expression in bacteria

    PubMed Central

    Klumpp, Stefan; Zhang, Zhongge; Hwa, Terence

    2010-01-01

    Summary Bacterial gene expression depends not only on specific regulations but also directly on bacterial growth, because important global parameters such as the abundance of RNA polymerases and ribosomes are all growth-rate dependent. Understanding these global effects is necessary for a quantitative understanding of gene regulation and for the robust design of synthetic genetic circuits. The observed growth-rate dependence of constitutive gene expression can be explained by a simple model using the measured growth-rate dependence of the relevant cellular parameters. More complex growth dependences for genetic circuits involving activators, repressors and feedback control were analyzed, and salient features were verified experimentally using synthetic circuits. The results suggest a novel feedback mechanism mediated by general growth-dependent effects and not requiring explicit gene regulation, if the expressed protein affects cell growth. This mechanism can lead to growth bistability and promote the acquisition of important physiological functions such as antibiotic resistance and tolerance (persistence). PMID:20064380

  9. Cultivation of a thermo-tolerant microalga in an outdoor photobioreactor: influences of CO2 and nitrogen sources on the accelerated growth.

    PubMed

    Huang, Chai-Cheng; Hung, Jia-Jang; Peng, Shao-Hung; Chen, Ching-Nen Nathan

    2012-05-01

    A photobioreactor was designed to evaluate the performance of a newly isolated thermo-tolerant microalga Desmodesmus sp. F2 in municipal wastewater under tropical outdoor conditions. The environmental parameters, levels of nutrients, and growth rates were monitored during the cultivations to elucidate the factors that contributed to accelerated growth after lag phase. Cultures bubbled with CO(2)-air had about 20% higher yields than the air-bubbled culture, and 2% of CO(2) at a flux rate of 5L/min was sufficient to reach this increased yield. In the cultures bubbled with CO(2)-air, the microalgal cells preferentially utilized ammonium and nitrate, while the air-bubbled culture made greater use of ammonium and organic nitrogen. In conclusion, the factors required for microalga Desmodesmus sp. F2 to achieve accelerated growth in tropical outdoor conditions include (1) 2% CO(2) bubbling; (2) a level of ammonium higher than 100 μM; and (3) a level of nitrate higher than 400 μM. PMID:22414576

  10. 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…

  11. MEDUSAHEAD OUTPERFORMS SQUIRRELTAIL THROUGH INTERFERENCE AND GROWTH RATE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Understanding the ecological processes fostering invasion and dominance by medusahead is central to its management. The objectives of this study were 1) to quantify and compare interference between medusahead and squirreltail under different concentrations of soil N and P and 2) to compare growth r...

  12. The physiological basis of reaction norms: the interaction among growth rate, the duration of growth and body size.

    PubMed

    Davidowitz, Goggy; Nijhout, H Frederik

    2004-12-01

    The general effects of temperature and nutritional quality on growth rate and body size are well known. We know little, however, about the physiological mechanisms by which an organism translates variation in diet and temperature into reaction norms of body size or development time. We outline an endocrine-based physiological mechanism that helps explain how this translation occurs in the holometabolous insect Manduca sexta (Sphingidae). Body size and development time are controlled by three factors: (i) growth rate, (ii) the timing of the cessation of juvenile hormone secretion (measured by the critical weight) and (iii) the timing of ecdysteroid secretion leading to pupation (the interval to cessation of growth [ICG] after reaching the critical weight). Thermal reaction norms of body size and development time are a function of how these three factors interact with temperature. Body size is smaller at higher temperatures, because the higher growth rate decreases the ICG, thereby reducing the amount of mass that can accumulate. Development time is shorter at higher temperatures because the higher growth rate decreases the time required to attain the critical weight and, independently, controls the duration of the ICG. Life history evolution along altitudinal, latitudinal and seasonal gradients may occur through differential selection on growth rate and the duration of the two independently controlled determinants of the growth period. PMID:21676730

  13. 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.

  14. 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.

  15. Effects of early-developmental stress on growth rates, body composition and developmental plasticity of the HPG-axis.

    PubMed

    Farrell, Tara M; Morgan, Amanda; Sarquis-Adamson, Yanina; MacDougall-Shackleton, Scott A

    2015-10-01

    In altricial songbirds, food restriction in early development has adverse effects on various physiological systems. When conditions improve birds can accelerate growth, but this compensatory strategy is associated with long-term adverse consequences. One system affected by altered growth rates is the hypothalamic-pituitary-gonadal (HPG) axis. Here, we subjected European starlings, Sturnus vulgaris, to an unpredictable food manipulation from 35 to 115days of age. We assessed the effects of the treatment by measuring overall body mass and body composition during and following the treatment period (i.e., accelerated growth). In adulthood, we measured the long-term effects of the treatment on overall body mass, testis volume, and HPG axis function in both sexes by quantifying androgen levels before and after a gonadotropin-releasing hormone (GnRH) challenge. During the treatment period, treatment birds had less body fat than controls. Following the treatment period, treatment birds weighed more than controls, but these gains were attributed to changes in lean mass. In adulthood, treatment males had lower baseline androgen levels, but there was no difference in peak androgen levels compared to controls. Treatment females did not differ from controls on any of the androgen measures. However, females that accelerated growth faster following the termination of the treatment had lower integrated androgen levels. When faced with limited developmental resources, birds may alter the developmental trajectory of physiological systems as a compensatory strategy. Such a strategy may have long-term consequences on endocrine regulation that could affect courtship and reproductive behaviors. PMID:26253500

  16. 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.

  17. 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

  18. 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. PMID:27073913

  19. 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…

  20. 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.

  1. 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

  2. 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. PMID:26106343

  3. 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.

  4. Paying for value: replacing Medicare's sustainable growth rate formula with incentives to improve care.

    PubMed

    Guterman, Stuart; Zezza, Mark A; Schoen, Cathy

    2013-03-01

    This brief sets forth a set of policy options to improve the way health care providers are paid by Medicare. The authors suggest repealing Medicare's sustain­able growth rate (SGR) formula for physician fees and replacing it with a pay-for-value approach that would: 1) increase payments over time only for physicians and other provid­ers who participate in innovative care arrangements; 2) strengthen primary care and care teams; and 3) implement bundled payments for hospital-related care. These reforms would be adopted by Medicare, Medicaid, and private plans in the new insurance marketplaces, with the goal of accelerating innovation in care delivery throughout the health system. Together, these policies could more than offset the cost of repealing the SGR formula, saving $788 billion for the federal government over 10 years and $1.3 trillion nationwide. Savings also would accrue to state and local governments ($163 billion), private employ­ers ($91 billion), and households ($291 billion). PMID:23547336

  5. Effects of winter stocker growth rate and finishing system on: I. Animal performance and carcass characteristics

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Angus-crossbred steers (n = 216) were used in a three-year study to assess the effects of winter stocker growth rate and finishing system on finishing performance and carcass characteristics. During winter months (December to April) steers were randomly allotted to three stocker growth rates: low (...

  6. Growth rates and water stability of 2D boronate ester covalent organic frameworks.

    PubMed

    Smith, Brian J; Hwang, Nicky; Chavez, Anton D; Novotney, Jennifer L; Dichtel, William R

    2015-05-01

    We examine the growth rates, activation energies, and hydrolytic stability of multiple 2D boronate ester covalent organic frameworks by turbidity measurements, observing a 200-fold range in stability. The rate-determining step in boronate ester 2D COF growth is not in-solution condensation, but rather interlayer polymer stacking through a nucleation-elongation process. PMID:25848654

  7. 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

  8. 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. PMID:24349025

  9. Taste development: differential growth rates of tongue regions in humans.

    PubMed

    Temple, Elizabeth C; Hutchinson, Ian; Laing, David G; Jinks, Anthony L

    2002-04-30

    There is a paucity of information about the anatomical and functional development of the human gustatory system. Although the anatomical development of the taste-sensitive fungiform, circumvallate and foliate papillae in the respective anterior, posterior and latero-posterior regions of the dorsal surface of the tongue has been well documented in the fetus, there is limited information about how these regions grow and when they exhibit adult function. The present study is concerned with determining when the growth of one of these taste-sensitive regions becomes adult in size, namely, the anterior region, and how this growth compares with that of the remaining posterior region. Two-hundred and thirty-two living subjects aged between 4 and 32 years participated. Following the identification and marking of a series of landmarks on the dorsal surface of the tongue with blue food dye, five measurements of the width and length of various parts of the tongue allowed calculation of the growth of the anterior and posterior regions. The results indicate that the fungiform papillae-rich anterior region attains adult-size by 8-10 years of age whilst the posterior region continues to grow until 15-16 years. Interestingly, this early development is not matched by achievement of adult function [Dev. Brain Res. 82 (1994) 286] or adult size papillae or taste pores [Dev. Brain Res., submitted]. Finally, the findings of the present study will allow studies of the development of taste function in humans to be conducted using equivalent tongue areas in subjects of different ages. PMID:11978394

  10. Overexpression of the Arabidopsis anaphase promoting complex subunit CDC27a increases growth rate and organ size.

    PubMed

    Rojas, Cristian Antonio; Eloy, Nubia Barbosa; Lima, Marcelo de Freitas; Rodrigues, Roberta Lopes; Franco, Luciana Ozório; Himanen, Kristiina; Beemster, Gerrit T S; Hemerly, Adriana Silva; Ferreira, Paulo Cavalcanti Gomes

    2009-10-01

    The Anaphase Promoting Complex (APC) controls CDK activity by targeting the ubiquitin-dependent proteolysis of S-phase and mitosis-promoting cyclins. Here, we report that the ectopic expression of the Arabidopsis CDC27a, an APC subunit, accelerates plant growth and results in plants with increased biomass production. CDC27a overexpression was associated to apical meristem restructuration, protoplasts with higher (3)H-thimidine incorporation and altered cell-cycle marker expression. Total protein extracts immunoprecipitated with a CDC27a antibody showed ubiquitin ligase activity, indicating that the Arabidopsis CDC27a gets incorporated into APC complexes. These results indicate a role of AtCDC27a in regulation of plant growth and raise the possibility that the activity of the APC and the rates of plant cell division could be regulated by the concentration of the CDC27a subunit. PMID:19629716

  11. 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.

  12. 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

  13. 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.

  14. The relationship between the growth rate and the lifetime in carbon nanotube synthesis

    NASA Astrophysics Data System (ADS)

    Chen, Guohai; Davis, Robert C.; Kimura, Hiroe; Sakurai, Shunsuke; Yumura, Motoo; Futaba, Don N.; Hata, Kenji

    2015-05-01

    We report an inverse relationship between the carbon nanotube (CNT) growth rate and the catalyst lifetime by investigating the dependence of growth kinetics for ~330 CNT forests on the carbon feedstock, carbon concentration, and growth temperature. We found that the increased growth temperature led to increased CNT growth rate and shortened catalyst lifetime for all carbon feedstocks, following an inverse relationship of a fairly constant maximum height. For the increased carbon concentration, the carbon feedstocks fell into two groups where ethylene/butane showed an increased/decreased growth rate and a decreased/increased lifetime indicating different rate-limiting growth processes. In addition, this inverse relationship held true for different types of CNTs synthesized by various chemical vapor deposition techniques and continuously spanned a 1000-times range in both the growth rate and catalyst lifetime, indicating the generality and fundamental nature of this behavior originating from the growth mechanism of CNTs itself. These results suggest that it would be fundamentally difficult to achieve a fast growth with a long lifetime.

  15. The relationship between the growth rate and the lifetime in carbon nanotube synthesis.

    PubMed

    Chen, Guohai; Davis, Robert C; Kimura, Hiroe; Sakurai, Shunsuke; Yumura, Motoo; Futaba, Don N; Hata, Kenji

    2015-05-21

    We report an inverse relationship between the carbon nanotube (CNT) growth rate and the catalyst lifetime by investigating the dependence of growth kinetics for ∼330 CNT forests on the carbon feedstock, carbon concentration, and growth temperature. We found that the increased growth temperature led to increased CNT growth rate and shortened catalyst lifetime for all carbon feedstocks, following an inverse relationship of a fairly constant maximum height. For the increased carbon concentration, the carbon feedstocks fell into two groups where ethylene/butane showed an increased/decreased growth rate and a decreased/increased lifetime indicating different rate-limiting growth processes. In addition, this inverse relationship held true for different types of CNTs synthesized by various chemical vapor deposition techniques and continuously spanned a 1000-times range in both the growth rate and catalyst lifetime, indicating the generality and fundamental nature of this behavior originating from the growth mechanism of CNTs itself. These results suggest that it would be fundamentally difficult to achieve a fast growth with a long lifetime. PMID:25913386

  16. DIFFERENTIAL PHYTOPLANKTON SINKING- AND GROWTH-RATES: AN EIGENVALUE ANALYSIS

    EPA Science Inventory

    An eigenvalue analysis of the vertical phytoplankton biomass equation is applied to calculate the differential sinking- and loss-rates of phytoplankton for different taxonomic groups in Lake Lyndon B. Johnson (Texas) and in Lake Erie. The analysis includes factors determining the...

  17. 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…

  18. 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. PMID:25087723

  19. Setting accelerated dissolution test for PLGA microspheres containing peptide, investigation of critical parameters affecting drug release rate and mechanism.

    PubMed

    Tomic, I; Vidis-Millward, A; Mueller-Zsigmondy, M; Cardot, J-M

    2016-05-30

    The objective of this study was development of accelerated in vitro release method for peptide loaded PLGA microspheres using flow-through apparatus and assessment of the effect of dissolution parameters (pH, temperature, medium composition) on drug release rate and mechanism. Accelerated release conditions were set as pH 2 and 45°C, in phosphate buffer saline (PBS) 0.02M. When the pH was changed from 2 to 4, diffusion controlled phases (burst and lag) were not affected, while release rate during erosion phase decreased two-fold due to slower ester bonds hydrolyses. Decreasing temperature from 45°C to 40°C, release rate showed three-fold deceleration without significant change in release mechanism. Effect of medium composition on drug release was tested in PBS 0.01M (200 mOsm/kg) and PBS 0.01M with glucose (380 mOsm/kg). Buffer concentration significantly affected drug release rate and mechanism due to the change in osmotic pressure, while ionic strength did not have any effect on peptide release. Furthermore, dialysis sac and sample-and-separate techniques were used, in order to evaluate significance of dissolution technique choice on the release process. After fitting obtained data to different mathematical models, flow-through method was confirmed as the most appropriate for accelerated in vitro dissolution testing for a given formulation. PMID:27025293

  20. In Vivo Human Left-to-Right Ventricular Differences in Rate Adaptation Transiently Increase Pro-Arrhythmic Risk following Rate Acceleration

    PubMed Central

    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 τs = 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 (r2 = 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. PMID:23284948

  1. 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.

  2. 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.

  3. Microalgal growth with intracellular phosphorus for achieving high biomass growth rate and high lipid/triacylglycerol content simultaneously.

    PubMed

    Wu, Yin-Hu; Yu, Yin; Hu, Hong-Ying

    2015-09-01

    Nutrient deprivation is a commonly-used trigger for microalgal lipid accumulation, but its adverse impact on microalgal growth seems to be inevitable. In this study, Scenedesmus sp. LX1 was found to show similar physiological and biochemical variation under oligotrophic and eutrophic conditions during growth with intracellular phosphorus. Under both conditions microalgal chlorophyll content and photosynthesis activity was stable during this growth process, leading to significant increase of single cell weight and size. Therefore, while algal density growth rate dropped significantly to below 1.0 × 10(5)cells mL(-1) d(-1) under oligotrophic condition, the biomass dry weight growth rate still maintained about 40 mg L(-1) d(-1). Meanwhile, the lipid content in biomass and triacylglycerols (TAGs) content in lipids increased significantly to about 35% and 65%, respectively. Thus, high biomass growth rate and high lipid/TAG content were achieved simultaneously at the late growth phase with intracellular phosphorus. Besides, microalgal biomass produced was rich in carbohydrate with low protein content. PMID:26056779

  4. 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. PMID:23850820

  5. Keratinocyte growth factor accelerates wound closure in airway epithelium during cyclic mechanical strain.

    PubMed

    Waters, C M; Savla, U

    1999-12-01

    The airway epithelium may be damaged by inhalation of noxious agents, in response to pathogens, or during endotracheal intubation and mechanical ventilation. Maintenance of an intact epithelium is important for lung fluid balance, and the loss of epithelium may stimulate inflammatory responses. Epithelial repair in the airways following injury must occur on a substrate that undergoes cyclic elongation and compression during respiration. We have previously shown that cyclic mechanical strain inhibits wound closure in the airway epithelium (Savla and Waters, 1998b). In this study, we investigated the stimulation of epithelial wound closure by keratinocyte growth factor (KGF) in vitro and the mechanisms by which KGF overcomes the inhibition due to mechanical strain. Primary cultures of normal human bronchial epithelial cells (NHBE) and a cell line of human airway epithelial cells, Calu 3, were grown on Silastic membranes, and a wound was scraped across the well. The wells were then exposed to cyclic strain using the Flexercell Strain Unit, and wound closure was measured. While cyclic elongation (20% maximum) and cyclic compression (approximately 2%) both inhibited wound closure in untreated wells, treatment with KGF (50 ng/ml) significantly accelerated wound closure and overcame the inhibition due to cyclic strain. Since wound closure involves cell spreading, migration, and proliferation, we investigated the effect of cyclic strain on cell area, cell-cell distance, and cell velocity at the wound edge. While the cell area increased in unstretched monolayers, the cell area of monolayers in compressed regions decreased significantly. Treatment with KGF increased the cell area in both cyclically elongated and compressed cells. Also, when cells were treated with KGF, cell velocity was significantly increased in both static and cyclically strained monolayers, and cyclic strain did not inhibit cell migration. These results suggest that KGF is an important factor in

  6. The effects of temperature and NaCl concentration on tetragonal lysozyme face growth rates

    NASA Astrophysics Data System (ADS)

    Forsythe, Elizabeth; Lee Pusey, Marc

    1994-05-01

    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 ˜4 to ˜63. Both decreasing temperature and increasing salt concentrations shifted plots of the growth rate versus C/ Csat 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. 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.

  8. 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. PMID:21429043

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

    SciTech Connect

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

    2012-06-15

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

  10. The effect of environment on the sustained load crack growth rates of forged WASPALOY

    NASA Astrophysics Data System (ADS)

    Vasatis, Ioannis P.; Pelloux, Regis M.

    1985-08-01

    The sustained load crack growth rates of wrought WASPALOY* were measured in air and in high purity argon at 650 °C using single edge notched (SEN) and compact tension (CT) specimens machined out of a turbine disk. The crack growth rates measured in air exhibited great variability across the WASPALOY disk, while the crack growth rates measured in purified argon were of the same order of magnitude. This difference in crack growth rates is attributed to local variations in oxidation resistance at the tip of the growing crack. The density and the distribution of carbides in different locations of the WASPALOY disk accounts for the variability in crack growth resistance in air.

  11. 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…

  12. Accelerated Schools Centers: How To Address Challenges to Institutionalization and Growth.

    ERIC Educational Resources Information Center

    Meza, James, Jr.

    The Accelerated Schools Project (ASP) at the University of New Orleans (UNO) was established in spring 1990, funded by a 3-year grant from Chevron. Beginning with 1 pilot school in 1991, the UNO Accelerated Schools Center has expanded to 36 schools representing 19 school districts in Louisiana and 3 schools from the Memphis City Schools district.…

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

    PubMed

    Monro, Keyne; Marshall, Dustin J

    2014-06-01

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

  14. Extension growth rates in two coral species from high-latitude reefs of Bermuda

    NASA Astrophysics Data System (ADS)

    Logan, A.; Tomascik, T.

    1991-09-01

    Mean annual growth rates (skeletal linear extension) in the hermatypic corals Porites astreoides Lamarck and Diploria labyrinthiformis (L.) were investigated mainly by X-radiography from a variety of localities at various depths on the high-latitude coral reefs of Bermuda. Growth rates of both species show an inverse curvilinear relationship with depth, with highest growth rates in the shallow inshore waters of Castle Harbour and lowest at the edge of the Bermuda platform and on the adjacent fore-reef slope. Annual density bands form seasonal couplets, with narrow, high density bands appearing to form in the spring-summer months and wider, low density bands over the rest of the year in both species. Comparison of the growth rates of P. astreoides from Bermuda with those from lower latitude West Indian localities, particularly Jamaica, indicates an inverse relationship with latitude and a similar inverse curvilinear relationship with depth at both geographic locations. Growth rate-locality differences in Bermuda for both species are suggested to be controlled mainly by local differences in wave energy and food supply and possibly seasonal water temperature fluctuations; growth rate-depth differences by decreasing illumination with depth; and growth rate-latitudinal differences by reduction in winter water temperatures and light levels with increasing latitude.

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

    PubMed

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

    1993-08-01

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

  16. 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

  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. Effect of Growth Rate on Histidine Catabolism and Histidase Synthesis in Aerobacter aerogenes1

    PubMed Central

    Jensen, Donald E.; Neidhardt, Frederick C.

    1969-01-01

    A study was made of how the catabolism of a carbon and energy source is affected by the biosynthetic demands of growing bacterial cells. Cultures of Aerobacter aerogenes in l-histidine medium were grown in a chemostat at rates determined by the supply of either sulfate or a required amino acid, l-arginine. It was discovered that the rate at which these cells grow under a biosynthetic restriction determines both the rate and the pattern of histidine degradation. (i) Histidine catabolism is partially coupled to the growth rate. This coupling is achieved by catabolite repression of histidase (histidine ammonia lyase; EC 4.3.1.3.), and also by a slightly decreased in vivo function of this enzyme at low growth rates. (ii) The looseness of the coupling results in a direct relationship between growth rate and growth yield, and possibly is correlated with an altered pattern of carbon flow from histidine. (iii) Sudden decreases in growth rate cause total repression of histidase synthesis for substantial periods of time. (iv) Sudden release of biosynthetic restriction leads rapidly to an increase in the functioning of the cells' complement of histidase, an increase in the rate of synthesis of this enzyme, and an increase in the growth yield from histidine. PMID:5781570

  19. Growth pattern and carcase development in male ducks selected for growth rate.

    PubMed

    Maruyama, K; Akbar, M K; Turk, C M

    1999-05-01

    1. Growth patterns of the whole body, eviscerated carcases, breast muscle, leg and thigh muscles and abdominal fat pads were compared in 4 lines (Lines A, B, C, and D) of male ducks selected for market weight (n = 1305) using growth curve analysis, allometric growth analysis and repeated measure analysis. At 49 d of age, Line A was heaviest, followed by Line B, Line C and Line D. 2. Ducks were fed ad libitum under 24-h lighting and 12 or 24 ducks were killed to determine body, carcase, breast-muscle, leg and thigh-muscle, and abdominal fat weights at time points from hatching until 53 d of age. 3. The Weibull function was chosen for growth curve analysis. The asymptote and inflection point from the Weibull growth curves identified 3 lines (Lines B, C, and D) with discrete body and carcase growth patterns but did not distinguish Line A from Line B. In all 4 lines the asymptote ranged from 4437 g to 3008 g for body weight and from 3334 g to 2098 g for carcase weight; the inflection point ranged from 22.5 d to 25.3 d for body weight and from 25.4 d to 29.6 d for carcase weight. 4. The allometric growth coefficient, relative to whole-body growth, was higher than 1.00 for breast muscle and lower than 1.00 for leg and thigh muscles during from 4 d to 53 d of age. 5. Body fat accumulation was estimated by abdominal fat. Line D accumulated more abdominal fat than other lines. The pattern of fat accumulation in Line D was different from Lines A, B and C and there were no differences between Lines A, B and C. PMID:10465391

  20. Optimized ion acceleration using high repetition rate, variable thickness liquid crystal targets

    NASA Astrophysics Data System (ADS)

    Poole, Patrick; Willis, Christopher; Cochran, Ginevra; Andereck, C. David; Schumacher, Douglass

    2015-11-01

    Laser-based ion acceleration is a widely studied plasma physics topic for its applications to secondary radiation sources, advanced imaging, and cancer therapy. Recent work has centered on investigating new acceleration mechanisms that promise improved ion energy and spectrum. While the physics of these mechanisms is not yet fully understood, it has been observed to dominate for certain ranges of target thickness, where the optimum thickness depends on laser conditions including energy, pulse width, and contrast. The study of these phenomena is uniquely facilitated by the use of variable-thickness liquid crystal films, first introduced in P. L. Poole et al. PoP21, 063109 (2014). Control of the formation parameters of these freely suspended films such as volume, temperature, and draw speed allows on-demand thickness variability between 10 nanometers and several 10s of microns, fully encompassing the currently studied thickness regimes with a single target material. The low vapor pressure of liquid crystal enables in-situ film formation and unlimited vacuum use of these targets. Details on the selection and optimization of ion acceleration mechanism with target thickness will be presented, including recent experiments on the Scarlet laser facility and others. This work was performed with support from the DARPA PULSE program through a grant from AMRDEC and by the NNSA under contract DE-NA0001976.

  1. 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

  2. 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.

  3. Energy-release rate associated with diffusional crack growth

    SciTech Connect

    Chuang, T.

    1982-12-01

    A general expression for the energy release rates (G) that arise during steady state crack propagation by diffusion is derived from the standpoint of irreversible thermodynamics. Three contributing components of G are identified: (1) the Griffith energy (G/sub Gr/); (2) heat generated in the process of surface diffusion; and (3) grain-boundary diffusion. Further, the total G is shown to be directly related to the well-known J-integral if formulated in the framework of finite deformation elasticity. This expression for G is valid in general even if the response of the material is not linear and the mass transport kinetics does not follow Fick's law. Quantitative evaluations of each component are made for the linear case where field solutions are available. The results show that component (2) is approximately equal to G/sub Gr/ and is independent of the crack velocity (nu) whereas component (3) is a monotonically increasing function with G starting from 0.85 G/sub Gr/ when nu is at threshold value; and that strain energy contributions can be neglected leading to G = J = (1-..nu../sup 2/)K/sup 2//E. This means that G is not primarily associated with the release of the strain energy; rather, it stems mostly from the negative work done by the normal stresses on the thickening of the grain boundary due to nonuniform deposition of matter along it.

  4. 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.

  5. 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.

  6. Interrelationship between single- and multi-wall carbon nanotube growth rates for CVD process

    SciTech Connect

    Wood, Richard F; Pannala, Sreekanth; Wells, Jack C; Puretzky, Alexander A; Geohegan, David B

    2007-01-01

    Recent time-resolved measurements of carbon nanotube (CNT) growth on Fe and Fe/Mo catalysts have identified a maximum growth rate and temperature corresponding to the onset of small-diameter, single-wall CNT (SWNT) formation. A simple model described here emphasizes the essential role of the SWNTs in the growth process of CNTs. Remarkably, it shows that the growth rate (i.e. the time derivative of the length) of a multi-walled CNT (MWNT) is the same as that of a SWNT at the carbon flux and diffusion coefficient corresponding to a given temperature. Moreover, below ~700C, the temperature above which SWNT growth is observed for a 6 sccm C2H2 flow rate, the number of walls as a function of temperature is uniquely determined by the interplay of the incident flux of atomic C and diffusion rates consistent with bulk diffusion. Even partial melting of the catalytic particle is unnecessary to explain the experimental results on growth rate and number of walls. Above 700C, where severe catalyst poisoning ordinarily begins, the growth rate without poisoning is consistent with recent results of Hata and co-workers for "supergrowth".

  7. Growth against entropy in bacterial metabolism: the phenotypic trade-off behind empirical growth rate distributions in E. coli.

    PubMed

    Martino, Daniele De; Capuani, Fabrizio; Martino, Andrea De

    2016-01-01

    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. PMID:27232645

  8. 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.

  9. 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.

  10. Ab initio determination of the instability growth rate of warm dense beryllium-deuterium interface

    NASA Astrophysics Data System (ADS)

    Wang, Cong; Li, Zi; Li, DaFang; Zhang, Ping

    2015-10-01

    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.

  11. Independence of buoyant cell density and growth rate in Escherichia coli

    SciTech Connect

    Kubitchek, H.E.; Baldwin, W.W.; Schroeter, S.J.; Graetzer, R.

    1984-04-01

    The relationship between growth rate and buoyant density was determined for cells from exponential-phase cultures of Escherichia coli B/r NC32 by equilibrium centrifugation in Percoll gradients at growth rates ranging from 0.15 to 2.3 doublings per h. The mean buoyant density did not change significantly with growth rate in any of three sets of experiments in which different gradient conditions were used. In addition, when cultures were allowed to enter the stationary phase of growth, mean cell volumes and buoyant densities usually remained unchanged for extended periods. These and earlier results support the existence of a highly regulated, discrete state of buoyant density during steady-state growth of E. coli and other cells that divide by equatorial fission. 11 references, 3 figures.

  12. 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.

  13. Strain-energy release rate analysis of cyclic delamination growth in compressively loaded laminates

    NASA Technical Reports Server (NTRS)

    Whitcomb, J. D.

    1984-01-01

    Delamination growth in compressively loaded composite laminates was studied analytically and experimentally. The configuration used was a laminate with an across-the-width delamination. An approximate super-position stress analysis was developed to quantify the effects of various geometric, material, and load parameters on mode 1 and mode 2 strain energy release rates G sub 1 and G sub 2, respectively. Calculated values of G sub 1 and G sub 2 were then compared with measured cyclic delamination growth rates to determine the relative importance of G sub 1 and G sub 2. High growth rates were observed only when G sub 1 was large. However, slow growth was observed even when G sub 1 was negligibly small. This growth was apparently due to a large value of G sub 2.

  14. Strain energy release rate analysis of cyclic delamination growth in compressively loaded laminates

    NASA Technical Reports Server (NTRS)

    Whitcomb, J. D.

    1983-01-01

    Delamination growth in compressively loaded composite laminates was studied analytically and experimentally. The configuration used was a laminate with an across-the-width delamination. An approximate super-position stress analysis was developed to quantify the effects of various geometric, material, and load parameters on mode 2 and mode 2 strain energy release rates G sub/1 and G sub 2, respectively. Calculated values of G sub 1 and G sub 2 were then compared with measured cyclic delamination growth rates to determine the relative importance of G sub 1 and G sub 2. High growth rates were observed only when G sub 1 was large. However, slow growth was observed even when G sub 1 was negligibly small. This growth apparently was due to a large value of G sub 2.

  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

    2016-01-01

    This study aimed to investigate the effects of Phlomis umbrosa root on bone growth and growth mediators in rats. Female adolescent rats were administered P. umbrosa extract, recombinant human growth hormone or vehicle for 10 days. Tetracycline was injected intraperitoneally to produce a glowing fluorescence band on the newly formed bone on day 8, and 5-bromo-2'-deoxyuridine was injected to label proliferating chondrocytes on days 8-10. To assess possible endocrine or autocrine/paracrine mechanisms, we evaluated insulin-like growth factor-1 (IGF-1), insulin-like growth factor binding protein-3 (IGFBP-3) or bone morphogenetic protein-2 (BMP-2) in response to P. umbrosa administration in either growth plate or serum. Oral administration of P. umbrosa significantly increased longitudinal bone growth rate, height of hypertrophic zone and chondrocyte proliferation of the proximal tibial growth plate. P. umbrosa also increased serum IGFBP-3 levels and upregulated the expressions of IGF-1 and BMP-2 in growth plate. In conclusion, P. umbrosa increases longitudinal bone growth rate by stimulating proliferation and hypertrophy of chondrocyte with the increment of circulating IGFBP-3. Regarding the immunohistochemical study, the effect of P. umbrosa may also be attributable to upregulation of local IGF-1 and BMP-2 expressions in the growth plate, which can be considered as a GH dependent autocrine/paracrine pathway. PMID:27070559

  16. 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.

  17. CCAP and FMRFamide-like peptides accelerate the contraction rate of the antennal accessory pulsatile organs (auxiliary hearts) of mosquitoes.

    PubMed

    Suggs, Julia M; Jones, Talitha H; Murphree, Steven C; Hillyer, Julián F

    2016-08-01

    Insects rely on specialized accessory pulsatile organs (APOs), also known as auxiliary hearts, to propel hemolymph into their antennae. In most insects, this is accomplished via the pulsations of a pair of ampulla located in the head, each of which propels hemolymph across an antenna via an antennal vessel. Once at the distal end of the appendage, hemolymph returns to the head via the antennal hemocoel. Although the structure of the antennal hearts has been elucidated in various insect orders, their hormonal modulation has only been studied in cockroaches and other hemimetabolous insects within the superorder Polyneoptera, where proctolin and FMRFamide-like peptides accelerate the contraction rate of these auxiliary hearts. Here, we assessed the hormonal modulation of the antennal APOs of mosquitoes, a group of holometabolous (Endopterygota) insects within the order Diptera. We show that crustacean cardioactive peptide (CCAP), FMRFamide and SALDKNFMRFamide increase the contraction rate of the antennal APOs and the heart of Anopheles gambiae Both antennal hearts are synchronously responsive to these neuropeptides, but their contractions are asynchronous with the contraction of the heart. Furthermore, we show that these neuropeptides increase the velocity and maximum acceleration of hemolymph within the antennal space, suggesting that each contraction is also more forceful. To our knowledge, this is the first report demonstrating that hormones of a holometabolous insect modulate the contraction dynamics of an auxiliary heart, and the first report that shows that the hormones of any insect accelerate the velocity of hemolymph in the antennal space. PMID:27247317

  18. Accelerated follicle growth during the culture of isolated caprine preantral follicles is detrimental to follicular survival and oocyte meiotic resumption.

    PubMed

    Apolloni, Livia Brunetti; Bruno, Jamily Bezerra; Alves, Benner Geraldo; Ferreira, Anna Clara Accioly; Paes, Victor Macêdo; Moreno, Jesus de Los Reyes Cadenas; de Aguiar, Francisco Léo Nascimento; Brandão, Felipe Zandonadi; Smitz, Johan; Apgar, Gary; de Figueiredo, José Ricardo

    2016-10-01

    This study investigated the effect of androstenedione (A4) alone or in association with different concentrations of bovine recombinant FSH on the IVC of isolated goat preantral follicles. Follicles were mechanically isolated from ovarian tissue and cultured for 18 days in α-minimum essential medium supplemented or not with A4 (10 ng/mL) alone or in association with fixed (A4 + FixFSH: 100 ng/mL) or sequential (A4 + SeqFSH: Day 0, 100 ng/mL; Day 6, 500 ng/mL; Day 12, 1000 ng/mL) concentrations of FSH. After 18 days, the oocytes were recovered for IVM and fluorescence analysis. At Day 18 of culture, only A4 + SeqFSH treatment showed a lower (P < 0.05) rate of intact follicles, survival probability, and meiotic resumption, as well as higher (P < 0.05) percentage of degeneration and/or extrusion after antrum formation. Taken together, these results reported a positive correlation between fast-growing follicles and follicles that degenerated and/or extruded after antrum formation. When compared with control, the addition of A4 alone or in association of FSH did not increase (P > 0.05) the estradiol production or androstenedione levels on Day 6. However, on Day 18, the androstenedione levels were significantly lower in A4 + SeqFSH treatment when compared with A4 alone or to A4 + FixFSH treatments, whereas the estradiol production did not differ (P > 0.05). In summary, this study found that accelerated follicle growth negatively impacted the morphology of caprine preantral follicle cultured in vitro. In addition, the association of androstenedione with increasing concentration of FSH was detrimental to follicular survival and oocyte meiotic resumption. PMID:27371972

  19. 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

  20. 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

  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. PMID:25148782

  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. The interaction among age, thermal acclimation and growth rate in determining muscle metabolic capacities and tissue masses in the threespine stickleback, Gasterosteus aculeatus.

    PubMed

    Guderley, H; Lavoie, B A; Dubois, N

    1994-11-01

    Thermal acclimation may directly modify muscle metabolic capacities, or may modify them indirectly via effects upon physiological processes such as growth, reproduction or senescence. To evaluate these interacting effects, we examined the influence of thermal acclimation and acclimatization upon muscle metabolic capacities and tissue masses in 1 + stickleback, Gasterosteus aculeatus, in which confounding interactions between temperature and senescense should be absent. Furthermore, we examined the influence of thermal acclimation upon individual growth rate, muscle enzyme levels and tissue masses in 2 + stickleback sampled at the beginning of their final reproductive season. For 1 + stickleback, cold acclimation more than doubles mitochondrial enzyme levels in the axial muscle. Thermal acclimation did not change the condition of 1 + stickleback at feeding levels which could not maintain the condition of 2+ stickleback. Compensatory metabolic responses to temperature were not apparent in field acclimatized 1 + stickleback. The growth rate of 2 + stickleback was markedly affected by temperature: warm-acclimated fish generally lost mass even at very high levels of feeding (up to 78 enchytraid worms per day) while cold-acclimated fish gained mass. This suggests that warm temperatures accelerate the senescence of 2 + stickleback. Generally, muscle enzyme activities increased with growth rate. In axial muscle, the relationships between CS activity and growth rate differed with acclimation temperature. Independent of the influence of growth rate, CS activities were consistently higher in cold- than warm-acclimated 2 + stickleback, suggesting compensatory increases of CS activity with cold acclimation. PMID:24197078

  4. 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.

  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. Maximum likelihood estimation of population growth rates based on the coalescent.

    PubMed Central

    Kuhner, M K; Yamato, J; Felsenstein, J

    1998-01-01

    We describe a method for co-estimating 4Nemu (four times the product of effective population size and neutral mutation rate) and population growth rate from sequence samples using Metropolis-Hastings sampling. Population growth (or decline) is assumed to be exponential. The estimates of growth rate are biased upwards, especially when 4Nemu is low; there is also a slight upwards bias in the estimate of 4Nemu itself due to correlation between the parameters. This bias cannot be attributed solely to Metropolis-Hastings sampling but appears to be an inherent property of the estimator and is expected to appear in any approach which estimates growth rate from genealogy structure. Sampling additional unlinked loci is much more effective in reducing the bias than increasing the number or length of sequences from the same locus. PMID:9584114

  7. Is the Oort A-value a universal growth rate limit for accretion disk shear instabilities?

    NASA Technical Reports Server (NTRS)

    Balbus, Steven A.; Hawley, John F.

    1992-01-01

    A weak-field local MHD instability that is of importance to accretion disks is examined. The maximum growth rate of the instability is found to be not only independent of the magnetic field strength but independent of field geometry as well. In particular, all Keplerian disks are unstable in the presence of any weak poloidal field, with the ratio of the maximum growth rate to disk angular velocity given by 3/4. The maximum growth rate of any weak field configuration that is not purely toroidal is given by the local Oort A-value of the disk. The behavior is studied by using a form of the dynamical Hill equations. It is conjectured that the Oort A-value is an upper bound to the growth rate of any instability feeding upon the free energy of differential rotation.

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

    PubMed

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

    2013-01-01

    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. Selection on herbivory resistance and growth rate in an invasive plant

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Invasive species face different conditions in their new range, which may lead to evolutionary change. The evolution of increased competitive ability (EICA) hypothesis proposes that invasive species evolve decreased defense and increased growth rate and competitive ability following introduction. W...

  10. 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

  11. 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.

  12. ORAL N-CARBAMYLGLUTAMATE (NCG) SUPPLEMENTATION INCREASES GROWTH RATE IN SOW-REARED PIGLETS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Oral supplementation of NCG, an analogue of N-acetylglutamate, increases plasma arginine concentrations and growth rate in sow-reared piglets. To investigate the mechanism involved in this growth response, nursing piglets (n = 18; BW = 3.19 kg) were orally administered 0 or 50 mg/kg BW of NCG twice...

  13. Modeling of kinetically limited growth rate for solution-synthesized germanium nanocrystals

    NASA Astrophysics Data System (ADS)

    Shoop, Nicholas; Tribby, Louis J.; Han, Sang M.

    2015-08-01

    Solution synthesis is a common method for preparing semiconductor nanocrystals (NCs). For such solution synthesis, many investigations have considered diffusion-limited growth, in which the diffusion of reactants through the boundary layer (BL) limits the NC growth rate. These studies often model the growth rate with a diffusion BL thickness much larger than the NC size and with unphysically low diffusion constants on the order of 10-12 cm2 s-1. In this work, we have examined the growth of Ge NCs synthesized by injecting Ge amide precursors into a solution of 1-octadecene, oleylamine, and hexadecylamine. We have previously established this low-temperature, low-pressure synthesis route. The resulting Ge growth rate compares well with our model, in which we consider both BL diffusion and surface kinetics of Ge precursors and organic ligand adsorbates. Our modeling results suggest that the NC growth is limited not by diffusion, but by the surface adsorption and desorption kinetics. The BL thickness in the stirred reaction vessel is calculated to be on the same order of magnitude as the crystal radius; therefore, the surface kinetics cannot be ignored. Furthermore, the synthesis temperature is near 300 °C, where the Ge monomer diffusion coefficient within the growth solution is substantially increased and estimated to be on the order of 10-5 cm2 s-1. These considerations agree well with our experimentally measured growth rate and strongly suggest that the NC size evolution is controlled primarily by the surface kinetics.

  14. Effect of step edge transition rates and anisotropy in simulations of epitaxial growth

    SciTech Connect

    Chason, E.; Dodson, B.W.

    1990-01-01

    We present the results of a hybrid rate equation/Monte Carlo simulation of epitaxial growth on vicinal surfaces. We have studied the effect on surface morphology of changing transition rates at step edges, of changing detachment rates from step edges and clusters, and of adding anisotropy to the diffusion and incorporation kinetics at step edges and islands. The effect of the transition rates on surface morphology are discussed in terms of a balance between growth by nucleation and coalescence of islands and by the propagation of steps. 11 refs., 6 figs., 1 tab.

  15. 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

  16. 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. PMID:18315815

  17. Measuring the growth rate of UK dairy heifers to improve future productivity.

    PubMed

    Bazeley, Katrine J; Barrett, David C; Williams, Paul D; Reyher, Kristen K

    2016-06-01

    Sub-optimal heifer growth is associated with higher disease rates and reduced future performance and longevity in the dairy herd. This report describes a system for measuring heifer growth from birth to first calving that was used on commercial dairy farms in South West England, in order to gather benchmarking data to feed back to farmers. Weights (n = 8443) were collected from 20 farms. There was a marked variation in individual and herd mean growth rates. Overall, calves gained no weight in the first 8 days after birth and had a very low growth rate (median 0.12 kg/day) up to 30 days, a period when feed conversion efficiency is high and calves are vulnerable to disease. Heifers whose growth rate up to 180 days was low were significantly less likely to achieve target service weight (374 kg) by 420 days. Monitoring heifer growth during the rearing period enables farmers to improve heifer growth rates and so impact both the efficiency of heifer rearing and, potentially, the productivity and performance of the adult herd. PMID:27256019

  18. Effect of Cetyltrimethylammonium Bromide (CTAB) on the Growth Rate and Morphology of Borax Crystals

    NASA Astrophysics Data System (ADS)

    Suharso; Parkinson, Gordon; Ogden, Mark

    An investigation of the effect of cetyltrimethylammonium bromide (CTAB) on both growth rate and morphology of borax crystal has been carried out. This experiment was carried out at temperature of 25°C and relative supersaturation of 0.21 and 0.74 under in situ cell optical microscopy method. The result shows that CTAB inhibits the growth rate and changes the morphology of borax crystal.

  19. Growth rate reduction of the curvature-driven flute instability by plasma blanket line tying

    SciTech Connect

    Segal, D.

    1983-09-01

    The effect of an annular, line-tied blanket, on the curvature-driven flute in a magnetic mirror is considered. The blanket is assumed to be line tied to a thermoionically emitting annular end plate. Reduction of the flute growth rate is computed as function of Larmor radius, blanket radius, and axial plasma conductance through either an external plasma or mirror sheath. It is found that significant reduction in growth rate can be achieved.

  20. 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.

  1. 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.

  2. Factors influencing crystal growth rates from undercooled liquids of pharmaceutical compounds.

    PubMed

    Trasi, Niraj S; Baird, Jared A; Kestur, Umesh S; Taylor, Lynne S

    2014-08-21

    Amorphous forms of drugs are increasingly being used to deliver poorly water-soluble compounds. Therefore, understanding the magnitude and origin of differences in crystallization kinetics is highly important. The goal of this study was to better understand the factors that influence crystal growth rates from pharmaceutically relevant undercooled liquids and to evaluate the range of growth rates observed. The crystal growth rates of 31 drugs were determined using an optical microscope in the temperature region between the glass transition temperature (Tg) and the melting temperature (Tm). Thermodynamic parameters such as Tm, melting enthalpy, and Tg were determined using a differential scanning calorimeter (DSC). Selected viscosity values for the undercooled liquid were taken from the literature. The growth rates of the different compounds were found to be very different from each other with a variation of about 5 orders of magnitude between the fastest growing compounds and the slowest growing compounds. A comparison of the physicochemical properties showed that compounds that had fast crystal growth rates had smaller molecular weights, higher melting temperatures, lower melt entropies, lower melt viscosities, and higher crystal densities. Variations in the growth rates of the compounds could be rationalized to a large extent by considering the thermodynamic driving force for crystallization, the viscosity, and the entropy difference between the melt and undercooled liquid. This study therefore provides important insight into factors that may compromise the stability of amorphous pharmaceuticals. PMID:25076138

  3. 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.

  4. The Impact of Prematriculation Admission Characteristics on Graduation Rates in an Accelerated Doctor of Pharmacy Program

    PubMed Central

    Morin, Anna K.

    2015-01-01

    Objective. To evaluate the impact of admission characteristics on graduation in an accelerated doctor of pharmacy (PharmD) program. Methods. Selected prematriculation characteristics of students entering the graduation class years of 2009-2012 on the Worcester and Manchester campuses of MCPHS University were analyzed and compared for on-time graduation. Results. Eighty-two percent of evaluated students (699 of 852) graduated on time. Students who were most likely to graduate on-time attended a 4-year school, previously earned a bachelor’s degree, had an overall prematriculation grade point average (GPA) greater than or equal to 3.6, and graduated in the spring just prior to matriculating to the university. Factors that reduced the likelihood of graduating on time were also identified. Work experience had a marginal impact on graduating on time. Conclusion. Although there is no certainty in college admission decisions, prematriculation characteristics can help predict the likelihood for academic success of students in an accelerated PharmD program. PMID:26689686

  5. In-situ observation of electric-field-induced acceleration in crystal growth of tetrathiafulvalene-tetracyanoquinodimethane

    NASA Astrophysics Data System (ADS)

    Sakai, Masatoshi; Kuniyoshi, Shigekazu; Yamauchi, Hiroshi; Iizuka, Masaaki; Nakamura, Masakazu; Kudo, Kazuhiro

    2013-04-01

    In-situ observations of vapor-phase growth of tetrathiafulvalene (TTF)-tetracyanoquinodimethane (TCNQ) crystals under an electric field were conducted without influencing the actual crystal growth process. The shortest incubation time of TTF-TCNQ nuclei and the highest initial growth rate of the crystals are obtained on the anode side and in high electric field regions. It is demonstrated that the distribution of molecules thermally diffusing on the substrate surface is controlled by an external electric field. These results indicate the potential for selective growth of highly conductive organic wires for micro- and nanoscale wiring in organic nanodevices.

  6. 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.

  7. Biogeochemical implications of comparative growth rates of Emiliania huxleyi and Coccolithus species

    NASA Astrophysics Data System (ADS)

    Daniels, C. J.; Sheward, R. M.; Poulton, A. J.

    2014-12-01

    Coccolithophores, a diverse group of phytoplankton, make important contributions to pelagic calcite production and export, yet the comparative biogeochemical role of species other than the ubiquitous Emiliania huxleyi is poorly understood. The contribution of different coccolithophore species to total calcite production is controlled by inter-species differences in cellular calcite, growth rate and relative abundance within a mixed community. In this study we examined the relative importance of E. huxleyi and two Coccolithus species in terms of daily calcite production. Culture experiments compared growth rates and cellular calcite content of E. huxleyi (Arctic and temperate strains), Coccolithus pelagicus (novel Arctic strain) and Coccolithus braarudii (temperate strain). Despite assumptions that E. huxleyi is a fast-growing species, growth rates between the three species were broadly comparable (0.16-0.85 d-1) under identical temperature and light conditions. Emiliania huxleyi grew only 12% faster on average than C. pelagicus, and 28% faster than C. braarudii. As the cellular calcite content of C. pelagicus and C. braarudii is typically 30-80 times greater than E. huxleyi, comparable growth rates suggest that Coccolithus species have the potential to be major calcite producers in mixed populations. To further explore these results we devised a simplistic model comparing daily calcite production from Coccolithus and E. huxleyi across a realistic range of relative abundances and a wide range of relative growth rates. Using the relative differences in growth rates from our culture studies, we found that C. pelagicus would be a larger source of calcite if abundances of E. huxleyi to C. pelagicus were below 34:1. Relative abundance data collected from North Atlantic field samples (spring and summer 2010) suggest that, with a relative growth rate of 88%, C. pelagicus dominated calcite production at 69% of the sites sampled. With a more extreme difference in growth

  8. First size-dependent growth rate measurements of 1 to 5 nm freshly formed atmospheric nuclei

    NASA Astrophysics Data System (ADS)

    Kuang, C.; Chen, M.; Zhao, J.; Smith, J.; McMurry, P. H.; Wang, J.

    2011-09-01

    This study presents the first measurements of size-dependent particle diameter growth rates for freshly nucleated particles down to 1 nm geometric diameter. Data analysis methods were developed, de-coupling the size and time-dependence of particle growth rates by fitting the aerosol general dynamic equation to size distributions obtained at an instant in time. Size distributions of freshly nucleated particles were measured during two intensive measurement campaigns in different environments (Atlanta, GA and Boulder, CO) using a recently developed electrical mobility spectrometer with a diethylene glycol-based ultrafine condensation particle counter as the detector. Size and time-dependent growth rates were obtained directly from measured size distributions and were found to increase approximately linearly with size from ~1 to 3 nm geometric diameter, ranging, for example, from 5.6 ± 2.0 to 27 ± 5.3 nm h-1 in Boulder (13:00) and from 5.5 ± 0.82 to 7.6 ± 0.56 nm h-1 in Atlanta (13:00). The resulting growth rate enhancement Γ, defined as the ratio of the observed growth rate to the growth rate due to the condensation of sulfuric acid only, was found to increase approximately linearly with size from ~1 to 3 nm geometric diameter, having lower limit values that approached ~1 at 1.2 nm geometric diameter in Atlanta and ~3 at 0.8 nm geometric diameter in Boulder, and having upper limit values that reached 8.3 at 4.1 nm geometric diameter in Atlanta and 25 at 2.7 nm geometric diameter in Boulder. Survival probability calculations comparing constant and size-dependent growth indicate that neglecting the strong growth rate size dependence from 1 to 3 nm observed in this study could lead to a significant overestimation of CCN survival probability.

  9. Simultaneous estimates of synechococcus spp. Growth and grazing mortality rates in the English Channel

    NASA Astrophysics Data System (ADS)

    Ning, Xiu-Ren; Vaulot, Daniel

    1996-03-01

    The marine chroococooid phycoerythrin-containing Synechococcus spp. cyanobacterium has been implicated as a substantial component of the photosynthetic picoplankton in the ocean. Although its importance as food source for heterotrophic nanoplankton is now recognized, information about the cycling of Synechococcus biomass and its diel pattern is limited and study methodology varies among authors. The selective metabolic inhibitor method was used to simultaneously estimate growth and grazing disappearance rates of Synechococcus in the English Channel where growth rates ranged from 0.25 to 0.72/d (mean ±SD=0.51±0.17/d) and grazing mortality rates ranged from 0.19 to 0.64/d (mean ±SD=0.48±0.17/d). Size-fractionated experiments demonstrated that up to 70% of Synechococcus disappearance could be attributed to grazers going through a 2 μm Nuclepore filter. Synechococcus grazing mortality rates (mean=0.74 ±0.25/d) during the day were always higher than that (mean=0.2±0.20/d) during the night, while growth rates showed no clear diel pattern. A positive correlation was observed between growth rates and in situ temperature ranging from 9 to 17°C, while in contrast grazing was independent of temperature. The close similatiry between average growth and grazing rates suggests a rapid recycling of Synechococcus biomass in English Channel coastal waters.

  10. Effects of Climate Change on Plant Population Growth Rate and Community Composition Change

    PubMed Central

    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. PMID:26039073

  11. 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.

  12. 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

  13. A simplified method for determining reactive rate parameters for reaction ignition and growth in explosives

    SciTech Connect

    Miller, P.J.

    1996-07-01

    A simplified method for determining the reactive rate parameters for the ignition and growth model is presented. This simplified ignition and growth (SIG) method consists of only two adjustable parameters, the ignition (I) and growth (G) rate constants. The parameters are determined by iterating these variables in DYNA2D hydrocode simulations of the failure diameter and the gap test sensitivity until the experimental values are reproduced. Examples of four widely different explosives were evaluated using the SIG model. The observed embedded gauge stress-time profiles for these explosives are compared to those calculated by the SIG equation and the results are described.

  14. 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.

  15. An Improved Reaction Rate Equation for Simulating the Ignition and Growth of Reaction in High Explosives

    SciTech Connect

    Murphy, M J

    2010-03-08

    We describe an improved reaction rate equation for simulating ignition and growth of reaction in high explosives. It has been implemented into CALE and ALE3D as an alternate to the baseline the Lee-Tarver reactive flow model. The reactive flow model treats the explosive in two phases (unreacted/reactants and reacted/products) with a reaction rate equation to determine the fraction reacted, F. The improved rate equation has fewer parameters, is continuous with continuous derivative, results in a unique set of reaction rate parameters for each explosive while providing the same functionality as the baseline rate equation. The improved rate equation uses a cosine function in the ignition term and a sine function in the growth and completion terms. The improved rate equation is simpler with fewer parameters.

  16. 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.

  17. 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.

  18. GTPase acceleration as the rate-limiting step in Arabidopsis G protein-coupled sugar signaling.

    PubMed

    Johnston, Christopher A; Taylor, J Philip; Gao, Yajun; Kimple, Adam J; Grigston, Jeffrey C; Chen, Jin-Gui; Siderovski, David P; Jones, Alan M; Willard, Francis S

    2007-10-30

    Heterotrimeric G protein signaling is important for cell-proliferative and glucose-sensing signal transduction pathways in the model plant organism Arabidopsis thaliana. AtRGS1 is a seven-transmembrane, RGS domain-containing protein that is a putative membrane receptor for d-glucose. Here we show, by using FRET, that d-glucose alters the interaction between the AtGPA1 and AtRGS1 in vivo. AtGPA1 is a unique heterotrimeric G protein alpha subunit that is constitutively GTP-bound given its high spontaneous nucleotide exchange coupled with slow GTP hydrolysis. Analysis of a point mutation in AtRGS1 that abrogates GTPase-accelerating activity demonstrates that the regulation of AtGPA1 GTP hydrolysis mediates sugar signal transduction during Arabidopsis development, in contrast to animals where nucleotide exchange is the limiting step in the heterotrimeric G protein nucleotide cycle. PMID:17951432

  19. 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

  20. Growth rate enhancement by microcrystals and the quality of resulting potash alum crystals

    NASA Astrophysics Data System (ADS)

    Takiyama, H.; Tezuka, N.; Matsuoka, M.; Ristic, R. I.; Sherwood, J. N.

    1998-09-01

    Growth rate enhancement resulting from the addition of ground powder crystals to a growing larger crystal has been examined for the potash alum-water system. The crystal quality of the large crystal after the addition and subsequent growth rate enhancement was evaluated in terms of the formation of inclusions and dislocations. Inclusions were observed with an optical microscope and the dislocations were analysed using X-ray transmission topography. It was found that the development of inclusions occurs at the time of the addition to the solution of the ground powder crystals and their attachment to the growing crystal surface. Simultaneously, dislocation bundles were generated. It is proposed that the inclusions form as the growing crystal surface envelopes the adhering particles and that the dislocations form both as a consequence of the strain that develops and the lattice mismatch required to refacet the surface. Both result in the development of additional growth centres which cause the growth rate enhancement.

  1. Effects of pH on the growth rate, motility and photosynthesis in Euglena gracilis.

    PubMed

    Danilov, R A; Ekelund, N G

    2001-01-01

    The influence of pH 3-10 on the growth, motility and photosynthesis in Euglena gracilis was demonstrated during a 7-d cultivation. The cells did not survive at pH < 4 and > 8, highest growth rate being detected at pH 7. Motility followed a similar pattern as growth rate. Photosynthetic response curves were shown to be of the same type over the whole pH range. High respiration was characteristic for cells grown at pH 5 and 6, the lowest one at 7. At high and also at low pH more active respiration was found which can be considered as a protective response on proton stress. Respiration was not completely inhibited with potassium cyanide. Photosynthesis was the most effective at pH 6; lower and higher pH decreased photosynthetic efficiency. pH affected more the growth rate than the photosynthesis. PMID:11898347

  2. 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.

  3. Measurement of Temperature Fluctuations and Microscopic Growth Rates in a Silicon Floating Zone and Microgravity

    NASA Technical Reports Server (NTRS)

    Schweizer, Markus; Croell, Arne

    1999-01-01

    A silicon crystal growth experiment has been accomplished using the floating-zone technique under microgravity on a sounding rocket (TEXUS 36). Measurements of temperature fluctuations in the silicon melt zone due to time dependent thermocapillary convection (Marangoni convection) and an observation of the microscopic growth rate were simultaneously performed during the experiment. Temperature fluctuations of about 0.5 - 0.7 C with a frequency range < 0.5Hz were detectable. The microscopic growth rate fluctuates considerably around the average growth rate of 1 mm/min: Growth rates up to 3 to 4mm/min, close to zero mm/min, as well as negative values (backmelting) were observed. Dopant striations are clearly visible in the Sb-doped crystal. They were characterized by Spreading Resistance measurements and Differential Interference Contrast microscopy. The frequencies of temperature fluctuations, microscopic growth rates, and the dopant inhomogeneities correspond quite well, with main frequencies between 0.1 and 0.3 Hz. 3D numerical simulations were performed to predict the optimum position of the temperature sensor, and the characteristic temperature amplitudes and frequencies. At a position 3.4mm above the interface and 1.4mm inside the melt, equivalent to the sensor tip position in the experiment, temperature fluctuations up to 1.8 C and frequencies ? 0.25Hz were found in the simulations.

  4. 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 significantly increased one or both specific growth rates in three of four experiments, and one experiment showed a secondary stimulation by organic substrates. The stimulatory effects of phosphorus addition were greatest concurrently with the highest alkaline phosphatase activity in the lake water. Because bacteria have been shown to dominate inorganic phosphorus uptake in other P-deficient systems, the demonstration that phosphorus, rather than organic carbon, can limit bacterioplankton growth suggests direct competition between phytoplankton and bacterioplankton for inorganic phosphorus.

  5. 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.

  6. Jackknife-corrected parametric bootstrap estimates of growth rates in bivalve mollusks using nearest living relatives.

    PubMed

    Dexter, Troy A; Kowalewski, Michał

    2013-12-01

    Quantitative estimates of growth rates can augment ecological and paleontological applications of body-size data. However, in contrast to body-size estimates, assessing growth rates is often time-consuming, expensive, or unattainable. Here we use an indirect approach, a jackknife-corrected parametric bootstrap, for efficient approximation of growth rates using nearest living relatives with known age-size relationships. The estimate is developed by (1) collecting a sample of published growth rates of closely related species, (2) calculating the average growth curve using those published age-size relationships, (3) resampling iteratively these empirically known growth curves to estimate the standard errors and confidence bands around the average growth curve, and (4) applying the resulting estimate of uncertainty to bracket age-size relationships of the species of interest. This approach was applied to three monophyletic families (Donacidae, Mactridae, and Semelidae) of mollusk bivalves, a group characterized by indeterministic shell growth, but widely used in ecological, paleontological, and geochemical research. The resulting indirect estimates were tested against two previously published geochemical studies and, in both cases, yielded highly congruent age estimates. In addition, a case study in applied fisheries was used to illustrate the potential of the proposed approach for augmenting aquaculture management practices. The resulting estimates of growth rates place body size data in a constrained temporal context and confidence intervals associated with resampling estimates allow for assessing the statistical uncertainty around derived temporal ranges. The indirect approach should allow for improved evaluation of diverse research questions, from sustainability of industrial shellfish harvesting to climatic interpretations of stable isotope proxies extracted from fossil skeletons. PMID:24071629

  7. Fishing directly selects on growth rate via behaviour: implications of growth-selection that is independent of size

    PubMed Central

    Biro, Peter A.; Sampson, Portia

    2015-01-01

    Size-selective harvest of fish and crustacean populations has reduced stock numbers, and led to reduced growth rates and earlier maturation. In contrast to the focus on size-selective effects of harvest, here, we test the hypothesis that fishing may select on life-history traits (here, growth rate) via behaviour, even in the absence of size selection. If true, then traditional size-limits used to protect segments of a population cannot fully protect fast growers, because at any given size, fast-growers will be more vulnerable owing to bolder behaviour. We repeatedly measured individual behaviour and growth of 86 crayfish and found that fast-growing individuals were consistently bold and voracious over time, and were subsequently more likely to be harvested in single- and group-trapping trials. In addition, there was some indication that sex had independent effects on behaviour and trappability, whereby females tended to be less active, shyer, slower-growing and less likely to be harvested, but not all these effects were significant. This study represents, to our knowledge, the first across-individual support for this hypothesis, and suggests that behaviour is an important mechanism for fishing selectivity that could potentially lead to evolution of reduced intrinsic growth rates. PMID:25608882

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

    NASA Technical Reports Server (NTRS)

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

    2003-01-01

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

  9. Effects of light intensity and temperature on Cryptomonas ovata (Cryptophyceae) growth and nutrient uptake rates

    USGS Publications Warehouse

    Cloern, James E.

    1977-01-01

    Specific growth rate of Cryptomonas ovata var. palustris Pringsheim was measured in batch culture at 14 light-temperature combinations. Both the maximum growth rate (μm) and optimum light intensity (Iopt) fit an empirical function that increases exponentially with temperature up to an optimum (Topt), then declines rapidly as temperature exceeds Topt. Incorporation of these functions into Steele's growth equation gives a good estimate of specific growth rate over a wide range of temperature and light intensity. Rates of phosphate, ammonium and nitrate uptake were measured separately at 16 combinations of irradiance and temperature and following a spike addition of all starved cells initially took up nutrient at a rapid rate. This transitory surge was followed by a period of steady, substrate-saturated uptake that persisted until external nutrient concentration fell. Substrate-saturated NO3−-uptake proceeded at very slow rates in the dark and was stimulated by both increased temperature and irradiance; NH4+-uptake apparently proceeded at a basal rate at 8 and l4 C and was also stimulated by increased temperature and irradiance. Rates of NH4−-uptake were much higher than NO3−-uptake at all light-temperature combinations. Below 20 C, PO4−3-uptake was more rapid in dark than in light, but was light enhanced at 26 C.

  10. Hydrogen Isotope Effect on the Fatigue Crack Growth Rate in Pipeline Steel

    NASA Astrophysics Data System (ADS)

    Connolly, Matthew; Slifka, Andrew; Drexler, Elizabeth; Hydrogen Pipeline Safety Team

    Hydrogen (H2) is desirable for energy storage as it is cleaner burning and can store a larger amount of energy than an equal mass of gasoline. One problem in the development of a hydrogen economy is to find or develop materials that ensure the safe, reliable, and cost-effective flow of energy from the source to the user. It is expected steels will be needed to serve this function. However, the existing network of natural gas pipeline, for example, is constructed of ferrous materials which are susceptible to embrittlement and subsequent increased fatigue crack growth rates after exposure to hydrogen. It is expected that diffusion rates play an important role on fatigue crack growth rates. We report the measurement of the fatigue crack growth rate in a high strength pipeline steel in a gaseous deuterium (D2) environment, in an effort to determine the role of diffusion rate on FCGR, because D2 is chemically identical to H2, but with twice the mass. We found that the D2 fatigue crack growth rate was not enhanced compared to air as is seen in an H2 environment; in fact our D2 rate measurement was slightly slower than in air, a result which is not expected to be due to diffusion rates alone. NIST Materials Measurement Laboratory, Applied Chemicals and Materials Division.

  11. Slow Growth Rates of Amazonian Trees: Consequences for Carbon Sequestration and Forest Management.

    NASA Astrophysics Data System (ADS)

    Vieira, S. A.; Camargo, P. B.; Selhorst, D.; Chambers, J.; Higuchi, N.; Martinelli, L. A.; Trumbore, S.

    2004-12-01

    Growth rates for tropical forest trees estimated from radiocarbon ages and dendrometer measurements illustrate differences in forest age and structure among three sites located in the eastern, central and western Amazon basin. Although growth rates vary dramatically among individual trees overall the slowest growing trees (averaging \\sim0.1mm yr-1 as opposed to 0.3mm yr-1 diameter increment) are found in the central Amazon. Small individuals (DBH \\<30cm) have slower growth rates than larger diameter trees, and trees in this size class with radiocarbon ages >500 yr are encountered at all sites. Only \\sim2MgC ha-1 year-1, or \\SIM7% of annual photosynthesis, is allocated to growth of living wood at the eastern and central Amazon sites. Rates of C allocation to stem growth are similar across the three sites we studied because slowest growth occurs at the central Amazon site that has highest stem density and greatest biomass. Extrapolating our growth increment data to forest stand, we estimate the mean age of individual trees is \\SIM350 years in the central Amazon but \\SIM200\\-250 years in the other two areas. The mean age of C making up the trees has a smaller range of \\SIM250\\-310 years, because of the greater fraction of biomass in larger individuals in the eastern and western Amazon sites. These residence times for C are longer than those of 100\\-180 years obtained by simply dividing the total biomass C by the rate of C allocation to new wood for the same reason. We estimate that >20% of trees at all sites should have ages >300 years, and that maximum tree ages of >1000 years, though not common, are in accord with the growth rates we find. The fact that many Amazon trees attain ages greater than several centuries should be accounted for in management practices in these forests.

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

    PubMed

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

    2008-05-01

    We study annual logarithmic growth rates R of various economic variables such as exports, imports, and foreign debt. For each of these variables we find that the distributions of R can be approximated by double exponential (Laplace) distributions in the central parts and power-law distributions in the tails. For each of these variables we further find a power-law dependence of the standard deviation sigma(R) on the average size of the economic variable with a scaling exponent surprisingly close to that found for the gross domestic product (GDP) [Phys. Rev. Lett. 81, 3275 (1998)]. By analyzing annual logarithmic growth rates R of wages of 161 different occupations, we find a power-law dependence of the standard deviation sigma(R) on the average value of the wages with a scaling exponent beta approximately 0.14 close to those found for the growth of exports, imports, debt, and the growth of the GDP. In contrast to these findings, we observe for payroll data collected from 50 states of the USA that the standard deviation sigma(R) of the annual logarithmic growth rate R increases monotonically with the average value of payroll. However, also in this case we observe a power-law dependence of sigma(R) on the average payroll with a scaling exponent beta approximately -0.08 . Based on these observations we propose a stochastic process for multiple cross-correlated variables where for each variable (i) the distribution of logarithmic growth rates decays exponentially in the central part, (ii) the distribution of the logarithmic growth rate decays algebraically in the far tails, and (iii) the standard deviation of the logarithmic growth rate depends algebraically on the average size of the stochastic variable. PMID:18643131

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

    NASA Astrophysics Data System (ADS)

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

    2008-05-01

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

  14. 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...

  15. Effects of carbon source and growth rate on cell wall composition of Bacillus subtilis subsp. niger.

    PubMed Central

    Kruyssen, F J; de Boer, W R; Wouters, J T

    1980-01-01

    A study was made to determine whether factors other than the availability of phosphorus were involved in the regulation of synthesis of teichoic and teichuronic acids in Bacillus subtilis subsp. niger WM. First, the nature of the carbon source was varied while the dilution rate was maintained at about 0.3 h-1. Irrespective of whether the carbon source was glucose, glycerol, galactose, or malate, teichoic acid was the main anionic wall polymer whenever phosphorus was present in excess of the growth requirement, and teichuronic acid predominated in the walls of phosphate-limited cells. The effect of growth rate was studied by varying the dilution rate. However, only under phosphate limitation did the wall composition change with the growth rate: walls prepared from cells grown at dilution rates above 0.5 h-1 contained teichoic as well as teichuronic acid, despite the culture still being phosphate limited. The wall content of the cells did not vary with the nature of the growth limitation, but a correlation was observed between the growth rate and wall content. No indications were obtained that the composition of the peptidoglycan of B. subtilis subsp. niger WM was phenotypically variable. PMID:6774960

  16. Effect of cell size and shear stress on bacterium growth rate

    NASA Astrophysics Data System (ADS)

    Fadlallah, Hadi; Jarrahi, Mojtaba; Herbert, Éric; Peerhossaini, Hassan; PEF Team

    2015-11-01

    Effect of shear stress on the growth rate of Synechocystis and Chlamydomonas cells is studied. An experimental setup was prepared to monitor the growth rate of the microorganisms versus the shear rate inside a clean room, under atmospheric pressure and 20 °C temperature. Digital magnetic agitators are placed inside a closed chamber provided with airflow, under a continuous uniform light intensity over 4 weeks. In order to study the effect of shear stress on the growth rate, different frequencies of agitation are tested, 2 vessels filled with 150 ml of each specie were placed on different agitating system at the desired frequency. The growth rate is monitored daily by measuring the optical density and then correlate it to the cellular concentration. The PH was adjusted to 7 in order to maintain the photosynthetic activity. Furthermore, to measure the shear stress distribution, the flow velocity field was measured using PIV. Zones of high and low shear stress were identified. Results show that the growth rate is independent of the shear stress magnitude, mostly for Synechocystis, and with lower independency for Chlamydomonas depending on the cell size for each species.

  17. Element content of Ochromonas danica: a replicated chemostat study controlling the growth rate and temperature.

    PubMed

    Simonds, Savannah; Grover, James P; Chrzanowski, Thomas H

    2010-11-01

    Ecological stoichiometry focuses on the balance between multiple nutrient elements in resources and in consumers of those resources. The major consumers of bacteria in aquatic food webs are heterotrophic and mixotrophic nanoflagellates. Despite the importance of this consumer-resource interaction to understanding nutrient dynamics in the aquatic food web, few data are available addressing the element stoichiometry of flagellate consumers. Ochromonas danica, a mixotrophic bacterivore, was used as a model organism to study the relationships among temperature, growth rate and element stoichiometry. Ochromonas danica was grown in chemostats at dilution rates ranging between 0.03 and 0.10 h(-1) and temperatures ranging between 15 and 28 °C. Cells accumulated elements as interactive functions of temperature and growth rate, with the highest element concentrations corresponding to cells grown at a low temperature and high growth rates. The highest concentrations of elements were associated with small cells. Temperature and growth rate affected the element stoichiometry (as C:N, C:P and N:P) of O. danica in a complex manner, but the growth rate had a greater effect on ratios than did temperature. PMID:21039649

  18. Systems Level Regulation of Rhythmic Growth Rate and Biomass Accumulation in Grasses

    SciTech Connect

    Kay, Steve A.

    2013-05-02

    Several breakthroughs have been recently made in our understanding of plant growth and biomass accumulation. It was found that plant growth is rhythmically controlled throughout the day by the circadian clock through a complex interplay of light and phytohormone signaling pathways. While plants such as the C4 energy crop sorghum (Sorghum bicolor (L.) Moench) and possibly the C3 grass (Brachypodium distachyon) also exhibit daily rhythms in growth rate, the molecular details of its regulation remain to be explored. A better understanding of diurnally regulated growth behavior in grasses may lead to species-specific mechanisms highly relevant to future strategies to optimize energy crop biomass yield. Here we propose to devise a systems approach to identify, in parallel, regulatory hubs associated with rhythmic growth in C3 and C4 plants. We propose to use rhythmicity in daily growth patterns to drive the discovery of regulatory network modules controlling biomass accumulation.

  19. 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.

  20. Pretreatment Growth Rate Predicts Radiation Response in Vestibular Schwannomas

    SciTech Connect

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

    2014-05-01

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

  1. Infant Gaze Following and Pointing Predict Accelerated Vocabulary Growth through Two Years of Age: A Longitudinal, Growth Curve Modeling Study

    ERIC Educational Resources Information Center

    Brooks, Rechele; Meltzoff, Andrew N.

    2008-01-01

    We found that infant gaze following and pointing predicts subsequent language development. At ages 0 ; 10 or 0 ; 11, infants saw an adult turn to look at an object in an experimental setting. Productive vocabulary was assessed longitudinally through two years of age. Growth curve modeling showed that infants who gaze followed and looked longer at…

  2. No Trade-Off between Growth Rate and Temperature Stress Resistance in Four Insect Species

    PubMed Central

    Karl, Isabell; Stoks, Robby; Bauerfeind, Stephanie S.; Dierks, Anneke; Franke, Kristin; Fischer, Klaus

    2013-01-01

    Although fast growth seems to be generally favored by natural selection, growth rates are rarely maximized in nature. Consequently, fast growth is predicted to carry costs resulting in intrinsic trade-offs. Disentangling such trade-offs is of great ecological importance in order to fully understand the prospects and limitations of growth rate variation. A recent study provided evidence for a hitherto unknown cost of fast growth, namely reduced cold stress resistance. Such relationships could be especially important under climate change. Against this background we here investigate the relationships between individual larval growth rate and adult heat as well as cold stress resistance, using eleven data sets from four different insect species (three butterfly species: Bicyclus anynana, Lycaena tityrus, Pieris napi; one Dipteran species: Protophormia terraenovae). Despite using different species (and partly different populations within species) and an array of experimental manipulations (e.g. different temperatures, photoperiods, feeding regimes, inbreeding levels), we were not able to provide any consistent evidence for trade-offs between fast growth and temperature stress resistance in these four insect species. PMID:23638084

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

    PubMed

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

    2011-01-01

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

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

    PubMed Central

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

    2011-01-01

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

  5. Coevolution within and between Regulatory Loci Can Preserve Promoter Function Despite Evolutionary Rate Acceleration

    PubMed Central

    Barrière, Antoine; Gordon, Kacy L.; Ruvinsky, Ilya

    2012-01-01

    Phenotypes that appear to be conserved could be maintained not only by strong purifying selection on the underlying genetic systems, but also by stabilizing selection acting via compensatory mutations with balanced effects. Such coevolution has been invoked to explain experimental results, but has rarely been the focus of study. Conserved expression driven by the unc-47 promoters of Caenorhabditis elegans and C. briggsae persists despite divergence within a cis-regulatory element and between this element and the trans-regulatory environment. Compensatory changes in cis and trans are revealed when these promoters are used to drive expression in the other species. Functional changes in the C. briggsae promoter, which has experienced accelerated sequence evolution, did not lead to alteration of gene expression in its endogenous environment. Coevolution among promoter elements suggests that complex epistatic interactions within cis-regulatory elements may facilitate their divergence. Our results offer a detailed picture of regulatory evolution in which subtle, lineage-specific, and compensatory modifications of interacting cis and trans regulators together maintain conserved gene expression patterns. PMID:23028368

  6. Influence of oxygen transfer on Pseudomonas putida effects on growth rate and biodesulfurization capacity.

    PubMed

    Escobar, S; Rodriguez, A; Gomez, E; Alcon, A; Santos, V E; Garcia-Ochoa, Felix

    2016-04-01

    The growth rate and desulfurization capacity accumulated by the cells during the growth of Pseudomonas putida KTH2 under different oxygen transfer conditions in a stirred and sparged tank bioreactor have been studied. Hydrodynamic conditions were changed using different agitation conditions. During the culture, several magnitudes associated to growth, such as the specific growth rate, the dissolved oxygen concentration and the carbon source consumption have been measured. Experimental results indicate that cultures are influenced by the fluid dynamic conditions into the bioreactor. An increase in the stirrer speed from 400 to 700 rpm has a positive influence on the cell growth rate. Nevertheless, the increase of agitation from 700 to 2000 rpm hardly has any influence on the growth rate. The effect of fluid dynamics on the cells development of the biodesulfurization (BDS) capacity of the cells during growth is different. The activities of the intracellular enzymes involved in the 4S pathway change with dissolved oxygen concentration. The enzyme activities have been evaluated in cells at several growth time and different hydrodynamic conditions. An increase of the agitation from 100 to 300 rpm has a positive influence on the development of the overall BDS capacity of the cells during growth. This capacity shows a decrease for higher stirrer speeds and the activity of the enzymes monooxygenases DszC and DszA decreases dramatically. The highest value of the activity of DszB enzyme was obtained with cells cultured at 100 rpm, while this activity decreases when the stirrer speed was increased higher than this value. PMID:26762940

  7. Recent Advances in High-Growth Rate Single-Crystal CVD Diamond

    SciTech Connect

    Liang, Q.; Yan, C; Meng, Y; Lai, J; Krasnicki, S; Mao, H; Hemley, R

    2009-01-01

    There have been important advances in microwave plasma chemical vapor deposition (MPCVD) of large single-crystal CVD diamond at high growth rates and applications of this diamond. The types of gas chemistry and growth conditions, including microwave power, pressure, and substrate surface temperatures, have been varied to optimize diamond quality and growth rates. The diamond has been characterized by a variety of spectroscopic and diffraction techniques. We have grown single-crystal CVD diamond over ten carats and above 1 cm in thickness at growth rates of 50-100 {micro}m/h. Colorless and near colorless single crystals up to two carats have been produced by further optimizing the process. The nominal Vickers fracture toughness of this high-growth rate diamond can be tuned to exceed 20 MPa m{sup 1/2} in comparison to 5-10 MPa m{sup 1/2} for conventional natural and CVD diamond. Post-growth high-pressure/high-temperature (HPHT) and low-pressure/high-temperature (LPHT) annealing have been carried out to alter the optical, mechanical, and electronic properties. Most recently, single-crystal CVD diamond has been successfully annealed by LPHT methods without graphitization up to 2200 C and < 300 Torr for periods of time ranging from a fraction of minute to a few hours. Significant changes observed in UV, visible, infrared, and photoluminescence spectra are attributed to changes in various vacancy centers and extended defects.

  8. Crystal Growth Rate Dispersion: A Predictor of Crystal Quality in Microgravity?

    NASA Technical Reports Server (NTRS)

    Kephart, Richard D.; Judge, Russell A.; Snell, Edward H.; vanderWoerd, Mark J.

    2003-01-01

    In theory macromolecular crystals grow through a process involving at least two transport phenomena of solute to the crystal surface: diffusion and convection. In absence of standard gravitational forces, the ratio of these two phenomena can change and explain why crystal growth in microgravity is different from that on Earth. Experimental evidence clearly shows, however, that crystal growth of various systems is not equally sensitive to reduction in gravitational forces, leading to quality improvement in microgravity for some crystals but not for others. We hypothesize that the differences in final crystal quality are related to crystal growth rate dispersion. If growth rate dispersion exists on Earth, decreases in microgravity, and coincides with crystal quality improvements then this dispersion is a predictor for crystal quality improvement. In order to test this hypothesis, we will measure growth rate dispersion both in microgravity and on Earth and will correlate the data with previously established data on crystal quality differences for the two environments. We present here the first crystal growth rate measurement data for three proteins (lysozyme, xylose isomerase and human recombinant insulin), collected on Earth, using hardware identical to the hardware to be used in microgravity and show how these data correlate with crystal quality improvements established in microgravity.

  9. Lifespan, growth rate, and body size across latitude in marine Bivalvia, with implications for Phanerozoic evolution.

    PubMed

    Moss, David K; Ivany, Linda C; Judd, Emily J; Cummings, Patrick W; Bearden, Claire E; Kim, Woo-Jun; Artruc, Emily G; Driscoll, Jeremy R

    2016-08-17

    Mean body size in marine animals has increased more than 100-fold since the Cambrian, a discovery that brings to attention the key life-history parameters of lifespan and growth rate that ultimately determine size. Variation in these parameters is not well understood on the planet today, much less in deep time. Here, we present a new global database of maximum reported lifespan and shell growth coupled with body size data for 1 148 populations of marine bivalves and show that (i) lifespan increases, and growth rate decreases, with latitude, both across the group as a whole and within well-sampled species, (ii) growth rate, and hence metabolic rate, correlates inversely with lifespan, and (iii) opposing trends in lifespan and growth combined with high variance obviate any demonstrable pattern in body size with latitude. Our observations suggest that the proposed increase in metabolic activity and demonstrated increase in body size of organisms over the Phanerozoic should be accompanied by a concomitant shift towards faster growth and/or shorter lifespan in marine bivalves. This prediction, testable from the fossil record, may help to explain one of the more fundamental patterns in the evolutionary and ecological history of animal life on this planet. PMID:27488653

  10. Effect of N2O on high-rate homoepitaxial growth of CVD single crystal diamonds

    NASA Astrophysics Data System (ADS)

    Su, Y.; Li, H. D.; Cheng, S. H.; Zhang, Q.; Wang, Q. L.; Lv, X. Y.; Zou, G. T.; Pei, X. Q.; Xie, J. G.

    2012-07-01

    Various gases such as N2, O2, and CO2 have been introduced in the typical reaction atmosphere of CH4/H2 and proposed to improve the growth of chemical vapor deposited (CVD) single-crystal diamonds (SCDs). In this paper, we study the influence of a new adding gas nitrous oxide (N2O) on the growth rate, morphology, and optical properties of homoepitaxy (100) CVD SCDs. The reaction pressure (H2/CH4 flow rates) was fixed at 300 Torr (750/90 in sccm) with the addition of a small amount of N2O gas varied at flow rates of 0, 2, 5, 8 and 10 sccm. With the appropriate addition of N2O, the growth rate was increased up to 135 μm/h and the surface roughness was decreased to around 2 nm. Furthermore, adding N2O is favorable for inhibiting the generation of large anti-pyramidal pits on the top surface of SCDs, which generally appeared in the products synthesized in CH4/H2 ambient. The combined effect of the nitrogen- and oxygen-related radicals decomposed from N2O on the growth and properties of the CVD SCDs is discussed. As a result, the addition of N2O provides a new route to realize high-rate growth CVD SCDs instead of the traditional nitrogen.

  11. Trace incorporation of heavy water reveals slow and heterogeneous pathogen growth rates in cystic fibrosis sputum

    NASA Astrophysics Data System (ADS)

    Kopf, Sebastian H.; Sessions, Alex L.; Cowley, Elise S.; Reyes, Carmen; Van Sambeek, Lindsey; Hu, Yang; Orphan, Victoria J.; Kato, Roberta; Newman, Dianne K.

    2016-01-01

    Effective treatment for chronic infections is undermined by a significant gap in understanding of the physiological state of pathogens at the site of infection. Chronic pulmonary infections are responsible for the morbidity and mortality of millions of immunocompromised individuals worldwide, yet drugs that are successful in laboratory culture are far less effective against pathogen populations persisting in vivo. Laboratory models, upon which preclinical development of new drugs is based, can only replicate host conditions when we understand the metabolic state of the pathogens and the degree of heterogeneity within the population. In this study, we measured the anabolic activity of the pathogen Staphylococcus aureus directly in the sputum of pediatric patients with cystic fibrosis (CF), by combining the high sensitivity of isotope ratio mass spectrometry with a heavy water labeling approach to capture the full range of in situ growth rates. Our results reveal S. aureus generation times with a median of 2.1 d, with extensive growth rate heterogeneity at the single-cell level. These growth rates are far below the detection limit of previous estimates of CF pathogen growth rates, and the rates are slowest in acutely sick patients undergoing pulmonary exacerbations; nevertheless, they are accessible to experimental replication within laboratory models. Treatment regimens that include specific antibiotics (vancomycin, piperacillin/tazobactam, tobramycin) further appear to correlate with slow growth of S. aureus on average, but follow-up longitudinal studies must be performed to determine whether this effect holds for individual patients.

  12. The Effect of the Laboratory Specimen on Fatigue Crack Growth Rate

    NASA Technical Reports Server (NTRS)

    Forth, S. C.; Johnston, W. M.; Seshadri, B. R.

    2006-01-01

    Over the past thirty years, laboratory experiments have been devised to develop fatigue crack growth rate data that is representative of the material response. The crack growth rate data generated in the laboratory is then used to predict the safe operating envelope of a structure. The ability to interrelate laboratory data and structural response is called similitude. In essence, a nondimensional term, called the stress intensity factor, was developed that includes the applied stresses, crack size and geometric configuration. The stress intensity factor is then directly related to the rate at which cracks propagate in a material, resulting in the material property of fatigue crack growth response. Standardized specimen configurations and experimental procedures have been developed for laboratory testing to generate crack growth rate data that supports similitude of the stress intensity factor solution. In this paper, the authors present laboratory fatigue crack growth rate test data and finite element analyses that show similitude between standard specimen configurations tested using the constant stress ratio test method is unobtainable.

  13. Trace incorporation of heavy water reveals slow and heterogeneous pathogen growth rates in cystic fibrosis sputum

    PubMed Central

    Kopf, Sebastian H.; Sessions, Alex L.; Cowley, Elise S.; Reyes, Carmen; Van Sambeek, Lindsey; Hu, Yang; Orphan, Victoria J.; Kato, Roberta; Newman, Dianne K.

    2016-01-01

    Effective treatment for chronic infections is undermined by a significant gap in understanding of the physiological state of pathogens at the site of infection. Chronic pulmonary infections are responsible for the morbidity and mortality of millions of immunocompromised individuals worldwide, yet drugs that are successful in laboratory culture are far less effective against pathogen populations persisting in vivo. Laboratory models, upon which preclinical development of new drugs is based, can only replicate host conditions when we understand the metabolic state of the pathogens and the degree of heterogeneity within the population. In this study, we measured the anabolic activity of the pathogen Staphylococcus aureus directly in the sputum of pediatric patients with cystic fibrosis (CF), by combining the high sensitivity of isotope ratio mass spectrometry with a heavy water labeling approach to capture the full range of in situ growth rates. Our results reveal S. aureus generation times with a median of 2.1 d, with extensive growth rate heterogeneity at the single-cell level. These growth rates are far below the detection limit of previous estimates of CF pathogen growth rates, and the rates are slowest in acutely sick patients undergoing pulmonary exacerbations; nevertheless, they are accessible to experimental replication within laboratory models. Treatment regimens that include specific antibiotics (vancomycin, piperacillin/tazobactam, tobramycin) further appear to correlate with slow growth of S. aureus on average, but follow-up longitudinal studies must be performed to determine whether this effect holds for individual patients. PMID:26715741

  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. 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.

  16. The acceleration rate of cosmic rays at cosmic ray modified shocks

    NASA Astrophysics Data System (ADS)

    Saito, Tatsuhiko; Hoshino, Masahiro; Amano, Takanobu

    It is a still controversial matter whether the production efficiency of cosmic rays (CRs) is relatively efficient or inefficient (e.g. Helder et al. 2009; Hughes et al. 2000; Fukui 2013). In upstream region of SNR shocks (the interstellar medium), the energy density of CRs is comparable to a substantial fraction of that of the thermal plasma (e.g. Ferriere 2001). In such a situation, CRs can possibly exert a back-reaction to the shocks and modify the global shock structure. These shocks are called cosmic ray modified shocks (CRMSs). In CRMSs, as a result of the nonlinear feedback, there are almost always up to three steady-state solutions for given upstream parameters, which are characterized by CR production efficiencies (efficient, intermediate and inefficient branch). We evaluate qualitatively the efficiency of the CR production in SNR shocks by considering the stability of CRMS, under the effects of i) magnetic fields and ii) injection, which play significant roles in efficiency of acceleration. By adopting two-fluid model (Drury & Voelk, 1981), we investigate the stability of CRMSs by means of time-dependent numerical simulations. As a result, we show explicitly the bi-stable feature of these multiple solutions, i.e., the efficient and inefficient branches are stable and the intermediate branch is unstable, and the intermediate branch transit to the inefficient one. This feature is independent of the effects of i) shock angles and ii) injection. Furthermore, we investigate the evolution from a hydrodynamic shock to CRMS in a self-consistent manner. From the results, we suggest qualitatively that the CR production efficiency at SNR shocks may be the least efficient.

  17. Consequences of different growth rates in broiler breeder and layer hens on embryogenesis, metabolism and metabolic rate: A review.

    PubMed

    Buzała, M; Janicki, B; Czarnecki, R

    2015-04-01

    Intensive genetic selection of broiler breeders and layer hens for economically important production traits, which has been carried out for almost a century, resulted in considerable differences in the mechanisms of growth and development and, thus, in avian metabolism, both during embryogenesis and after hatching. Selection for meat production (broiler breeders) and eggs (layer hens) led to increased productivity but also brought about metabolic disorders. That intensive genetic selection of broiler breeders and layer hens is effective is seen, for example, in the differences in growth and development, metabolism of the yolk sac, hormones and lipids, gas exchange, and thermogenesis. Due to genetic proximity and different developmental mechanisms in broiler breeders and layer hens, avian embryos and chicks serve as excellent models for fundamental scientific research. This review paper discusses the consequences of different growth rates as a result of long-term genetic selection on embryonic development and metabolic rate of broilers and layers. The evidence presented herein indicates that it would be worth comparing these issues in a meta-analysis. PMID:25691756

  18. Single-mode Rayleigh-Taylor growth-rate measurements with the OMEGA laser system

    NASA Astrophysics Data System (ADS)

    Knauer, J. P.; Verdon, C. P.; Meyerhofer, D. D.; Boehly, T. R.; Bradley, D. K.; Smalyuk, V. A.; Ofer, D.; McKenty, P. W.; Glendinning, S. G.; Kalantar, D. H.; Watt, R. G.; Gobby, P. L.; Willi, O.; Taylor, R. J.

    1997-04-01

    The results from a series of single-mode Rayleigh-Taylor (RT) instability growth experiments performed on the OMEGA laser system using planar targets are reported. Planar targets with imposed mass perturbations were accelerated using five to six 351-nm laser beams overlapped with total intensities up to 2.5×1014W/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 through-foil radiography and was detected with an x-ray framing camera for CH targets with and without a foam buffer. The growth of both 31-μm and 60-μm wavelength perturbations was found to be in good agreement with ORCHID simulations when the experimental details, including noise, were included. The addition of a 30-mg/cc, 100-μm-thick polystyrene foam buffer layer resulted in reduced growth of the 31-μm perturbation and essentially unchanged growth for the 60-μm case when compared to targets without foam.

  19. Single-mode Rayleigh-Taylor growth-rate measurements with the OMEGA laser system

    SciTech Connect

    Knauer, J. P.; Verdon, C. P.; Meyerhofer, D. D.; Boehly, T. R.; Bradley, D. K.; Smalyuk, V. A.; Ofer, D.; McKenty, P. W.; Glendinning, S. G.; Kalantar, D. H.; Watt, R. G.; Gobby, P. L.; Willi, O.; Taylor, R. J.

    1997-04-15

    The results from a series of single-mode Rayleigh-Taylor (RT) instability growth experiments performed on the OMEGA laser system using planar targets are reported. Planar targets with imposed mass perturbations were accelerated using five to 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 through-foil radiography and was detected with an x-ray framing camera for CH targets with and without a foam buffer. The growth of both 31-{mu}m and 60-{mu}m wavelength perturbations was found to be in good agreement with ORCHID simulations when the experimental details, including noise, were included. The addition of a 30-mg/cc, 100-{mu}m-thick polystyrene foam buffer layer resulted in reduced growth of the 31-{mu}m perturbation and essentially unchanged growth for the 60-{mu}m case when compared to targets without foam.

  20. Single-mode Rayleigh-Taylor growth-rate measurements with the OMEGA laser system

    SciTech Connect

    Knauer, J.P.; Verdon, C.P.; Meyerhofer, D.D.; Boehly, T.R.; Bradley, D.K.; Smalyuk, V.A.; Ofer, D.; McKenty, P.W.; Glendinning, S.G.; Kalantar, D.H.; Watt, R.G.; Gobby, P.L.; Willi, O.; Taylor, R.J.

    1997-04-01

    The results from a series of single-mode Rayleigh-Taylor (RT) instability growth experiments performed on the OMEGA laser system using planar targets are reported. Planar targets with imposed mass perturbations were accelerated using five to six 351-nm laser beams overlapped with total intensities up to 2.5{times}10{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{percent}{endash}7{percent} over a 600-{mu}m-diam region defined by the 90{percent} intensity contour. The temporal growth of the modulation in optical depth was measured using through-foil radiography and was detected with an x-ray framing camera for CH targets with and without a foam buffer. The growth of both 31-{mu}m and 60-{mu}m wavelength perturbations was found to be in good agreement with {ital ORCHID} simulations when the experimental details, including noise, were included. The addition of a 30-mg/cc, 100-{mu}m-thick polystyrene foam buffer layer resulted in reduced growth of the 31-{mu}m perturbation and essentially unchanged growth for the 60-{mu}m case when compared to targets without foam. {copyright} {ital 1997 American Institute of Physics.}

  1. 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

  2. Low-to-moderate nitrogen and phosphorus concentrations accelerate microbially driven litter breakdown rates.

    PubMed

    Kominoski, John S; Rosemond, Amy D; Benstead, Jonathan P; Gulis, Vladislav; Maerz, John C; Manning, David W P

    2015-04-01

    Particulate organic matter (POM) processing is an important driver of aquatic ecosystem productivity that is sensitive to nutrient enrichment and.drives ecosystem carbon (C) loss. Although studies of single concentrations of nitrogen (N) or phosphorus (P) have shown effects at relatively low concentrations, responses of litter breakdown rates along gradients of low-to-moderate N and P concentrations are needed to establish likely interdependent effects of dual N and P enrichment on baseline activity in stream ecosystems. We established 25 combinations of dissolved inorganic N (DIN; 55-545 µg/L) and soluble reactive P (SRP; 4-86 µg/L) concentrations with corresponding N:P molar ratios of 2-127 in experimental stream channels. We excluded macroinvertebrates, focusing on microbially driven breakdown of maple (Acer rubrum L.) and rhododendron (Rhododendron maximum L.) leaf litter. Breakdown rates, k, per day (d-1) and per degree-day (dd-l), increased by up to 6X for maple and 12× for rhododendron over our N and P enrichment gradient compared to rates at low ambient N and P concentrations. The best models of k (d- and dd-1) included litter species identity and N and P concentrations; there was evidence for both additive and interactive effects of N and P. Models explaining variation in k dd-1 were supported by N and P for both maple and rhododendron (R =0.67 and 0.33, respectively). Residuals in the relationship between k dd-1 and N concentration were largely explained by P, but residuals for k dd-1 and P. concentration were less adequately explained by N. Breakdown rates were more closely related to nutrient concentrations than variables associated with measurements of two mechanistic parameters associated with C loss (fungal biomass and microbial respiration rate). We also determined the effects of nutrient addition on litter C: nutrient stoichiometry and found reductions in litter C:N and C:P along our experimental nutrient gradient. Our results indicate that

  3. Determinants in 3Dpol modulate the rate of growth of hepatitis A virus.

    PubMed

    Konduru, Krishnamurthy; Kaplan, Gerardo G

    2010-08-01

    Hepatitis A virus (HAV), an atypical member of the Picornaviridae, grows poorly in cell culture. To define determinants of HAV growth, we introduced a blasticidin (Bsd) resistance gene into the virus genome and selected variants that grew at high concentrations of Bsd. The mutants grew fast and had increased rates of RNA replication and translation but did not produce significantly higher virus yields. Nucleotide sequence analysis and reverse genetic studies revealed that a T6069G change resulting in a F42L amino acid substitution in the viral polymerase (3D(pol)) was required for growth at high Bsd concentrations whereas a silent C7027T mutation enhanced the growth rate. Here, we identified a novel determinant(s) in 3D(pol) that controls the kinetics of HAV growth. PMID:20534860

  4. Environmental effects of the growth rate of intertidal invertebrates and some implications for foraging waders

    NASA Astrophysics Data System (ADS)

    Wanink, Jan H.; Zwarts, Leo

    The paper describes effects of intertidal height and sediment type on growth rate of the bivalves Cerastoderma edule, Macoma balthica, Mya arenaria, Mytilus edulis and Scrobicularia plana, and of the worms Arenicola marina, Nephtys hombergii and Nereis diversicolor in the eastern part of the Dutch Wadden Sea. In most species, exposure time was negatively correlated with length growth, although interfering effects of sediment type could not be ruled out. When controlled for the effects of exposure time, clay content of the sediment appeared to affect the growth of all species, but in different ways. The variation was related to the foraging methods of the invertebrates. Foraging waders may use the spatial variation in growth rate of the invertebrates to optimize the exploitation of individual cohorts.

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

    USGS Publications Warehouse

    Reddy, Michael M.

    2012-01-01

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

  6. Isolation of Hox cluster genes from insects reveals an accelerated sequence evolution rate.

    PubMed

    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

  7. 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.

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

    PubMed

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

    2014-10-01

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

  9. Fatigue Crack Growth Rate of Inconel 718 Sheet at Cryogenic Temperatures

    NASA Technical Reports Server (NTRS)

    Wells, Douglas; Wright, Jonathan; Hastings, Keith

    2005-01-01

    Inconel 718 sheet material was tested to determine fatigue crack growth rate (FCGR) at cryogenic conditions representative of a liquid hydrogen (LH2) environment at -423 degree F. Tests utilized M(T) and ESE(T) specimen geometries and environments were either cold gaseous helium or submersion in LH2. The test results support a significant improvement in the fatigue crack growth threshold at -423 degree F compared to -320 degree F or 70 degree F.

  10. Silencing of PMEPA1 accelerates the growth of prostate cancer cells through AR, NEDD4 and PTEN.

    PubMed

    Li, Hua; Mohamed, Ahmed A; Sharad, Shashwat; Umeda, Elizabeth; Song, Yingjie; Young, Denise; Petrovics, Gyorgy; McLeod, David G; Sesterhenn, Isabell A; Sreenath, Taduru; Dobi, Albert; Srivastava, Shiv

    2015-06-20

    Androgen Receptor (AR) is the male hormone receptor and a nuclear transcription factor which plays a central role in the growth of normal and malignant prostate gland. Our earlier studies defined a mechanistic model for male hormone dependent regulation of AR protein levels in prostate cancer (CaP) cells through a negative feed-back loop between AR and PMEPA1, an androgen induced NEDD4 E3 ubiquitin ligase binding protein. This report focuses on the impact of PMEPA1 silencing on CaP biology. PMEPA1 knockdown accelerated the growth of CaP tumor cells in athymic nude mice. In cell culture models knockdown of PMEPA1 resulted in resistance to AR inhibitors enzalutamide and bicalutamide. While, AR protein down regulation by NEDD4 was PMEPA1 dependent, we also noted a PMEPA1 independent downregulation of PTEN by NEDD4. In a subset of human CaP, decreased PMEPA1 mRNA expression significantly correlated with increased levels of AR transcription target PSA, as a surrogate for elevated AR. This study highlights that silencing of PMEPA1 accelerates the growth of CaP cells through AR, NEDD4 and PTEN. Thus, the therapeutic restoration of PMEPA1 represents a promising complementary strategy correcting for AR and PTEN defects in CaP. Statement of significance: Here we define that silencing of PMEPA1 facilitates the growth of CaP cells and modulates AR through NEDD4 and PTEN. The restoration of PMEPA1 represents a promising complementary therapeutic strategy correcting for AR and PTEN defects. PMID:25883222

  11. Interactive effects of and light on growth rates and RUBISCO content of small and large centric diatoms

    NASA Astrophysics Data System (ADS)

    Li, G.; Campbell, D. A.

    2015-10-01

    Among marine phytoplankton groups, diatoms span the widest range of cell size, with resulting effects upon their nitrogen uptake, photosynthesis and growth responses to light. We grew two strains of marine centric diatoms, the small Thalassiosira pseudonana and the larger T. punctigera in high and low nitrogen media, across a range of growth light levels. Nitrogen and total proteins per cell decreased with increasing growth light in both species when grown under low nitrogen media. Surprisingly, low nitrogen increased the cellular allocation to RUBISCO and the rate of electron transport away from Photosystem II for the smaller diatom under low growth light, and for the larger diatom across the range of growth lights. Low nitrogen decreased the growth rate of the smaller diatom, particularly under higher light, but stimulated the growth rate of the larger diatom. Our results show that the high nitrogen in common growth media favours the growth rate of a small diatom but inhibits growth of a larger species.

  12. Diabetes accelerates smooth muscle accumulation in lesions of atherosclerosis: lack of direct growth-promoting effects of high glucose levels.

    PubMed

    Suzuki, L A; Poot, M; Gerrity, R G; Bornfeldt, K E

    2001-04-01

    In combination with other factors, hyperglycemia may cause the accelerated progression of atherosclerosis in people with diabetes. Arterial smooth muscle cell (SMC) proliferation and accumulation contribute to formation of advanced atherosclerotic lesions. Therefore, we investigated the effects of hyperglycemia on SMC proliferation and accumulation in vivo and in isolated arteries and SMCs by taking advantage of a new porcine model of diabetes-accelerated atherosclerosis, in which diabetic animals are hyperglycemic without receiving exogenous insulin. We show that diabetic animals fed a cholesterol-rich diet, like humans, develop severe lesions of atherosclerosis characterized by SMC accumulation and proliferation, whereas lesions in nondiabetic animals contain fewer SMCs after 20 weeks. However, high glucose (25 mmol/l) does not directly stimulate the proliferation of SMCs in isolated arterial tissue from diabetic or nondiabetic animals, or of cultured SMCs from these animals or from humans. Furthermore, the mitogenic actions of platelet-derived growth factor, IGF-I, or serum are not enhanced by high glucose. High glucose increases SMC glucose metabolism through the citric acid cycle and the pentose phosphate pathway by 240 and 90%, respectively, but <10% of consumed glucose is metabolized through these pathways. Instead, most of the consumed glucose is converted into lactate and secreted by the SMCs. Thus, diabetes markedly accelerates SMC proliferation and accumulation in atherosclerotic lesions. The stimulatory effect of diabetes on SMCs is likely to be mediated by effects secondary to the hyperglycemic state. PMID:11289052

  13. The complete plastid genome sequence of Welwitschia mirabilis: an unusually compact plastome with accelerated divergence rates

    PubMed Central

    2008-01-01

    Background Welwitschia mirabilis is the only extant member of the family Welwitschiaceae, one of three lineages of gnetophytes, an enigmatic group of gymnosperms variously allied with flowering plants or conifers. Limited sequence data and rapid divergence rates have precluded consensus on the evolutionary placement of gnetophytes based on molecular characters. Here we report on the first complete gnetophyte chloroplast genome sequence, from Welwitschia mirabilis, as well as analyses on divergence rates of protein-coding genes, comparisons of gene content and order, and phylogenetic implications. Results The chloroplast genome of Welwitschia mirabilis [GenBank: EU342371] is comprised of 119,726 base pairs and exhibits large and small single copy regions and two copies of the large inverted repeat (IR). Only 101 unique gene species are encoded. The Welwitschia plastome is the most compact photosynthetic land plant plastome sequenced to date; 66% of the sequence codes for product. The genome also exhibits a slightly expanded IR, a minimum of 9 inversions that modify gene order, and 19 genes that are lost or present as pseudogenes. Phylogenetic analyses, including one representative of each extant seed plant lineage and based on 57 concatenated protein-coding sequences, place Welwitschia at the base of all seed plants (distance, maximum parsimony) or as the sister to Pinus (the only conifer representative) in a monophyletic gymnosperm clade (maximum likelihood, bayesian). Relative rate tests on these gene sequences show the Welwitschia sequences to be evolving at faster rates than other seed plants. For these genes individually, a comparison of average pairwise distances indicates that relative divergence in Welwitschia ranges from amounts about equal to other seed plants to amounts almost three times greater than the average for non-gnetophyte seed plants. Conclusion Although the basic organization of the Welwitschia plastome is typical, its compactness, gene content

  14. Understanding contributions of cohort effects to growth rates of fluctuating populations.

    PubMed

    Wittmer, Heiko U; Powell, Roger A; King, Carolyn M

    2007-09-01

    1. Understanding contributions of cohort effects to variation in population growth of fluctuating populations is of great interest in evolutionary biology and may be critical in contributing towards wildlife and conservation management. Cohort-specific contributions to population growth can be evaluated using age-specific matrix models and associated elasticity analyses. 2. We developed age-specific matrix models for naturally fluctuating populations of stoats Mustela erminea in New Zealand beech forests. Dynamics and productivity of stoat populations in this environment are related to the 3-5 year masting cycle of beech trees and consequent effects on the abundance of rodents. 3. The finite rate of increase (lambda) of stoat populations in New Zealand beech forests varied substantially, from 1.98 during seedfall years to 0.58 during post-seedfall years. Predicted mean growth rates for stoat populations in continuous 3-, 4- or 5-year cycles are 0.85, 1.00 and 1.13. The variation in population growth was a consequence of high reproductive success of females during seedfall years combined with low survival and fertility of females of the post-seedfall cohort. 4. Variation in population growth was consistently more sensitive to changes in survival rates both when each matrix was evaluated in isolation and when matrices were linked into cycles. Relative contributions to variation in population growth from survival and fertility, especially in 0-1-year-old stoats, also depend on the year of the cycle and the number of transitional years before a new cycle is initiated. 5. Consequently, management strategies aimed at reducing stoat populations that may be best during one phase of the beech seedfall cycle may not be the most efficient during other phases of the cycle. We suggest that management strategies based on elasticities of vital rates need to consider how population growth rates vary so as to meet appropriate economic and conservation targets. PMID:17714273

  15. Age Determination and Growth Rates in Deep-Water Bamboo Corals (Isididae)

    NASA Astrophysics Data System (ADS)

    Fallon, S. J.; Thresher, R.; Sherwood, O.

    2009-12-01

    Gorgonians are a major element of the fauna of deep-water coral reefs and very long-lived recorders of deep-water paleo-oceanography. Both ecological studies and paleo-analyses require accurate age determination and dating of colony formation, but because of the depths at which they occur (typically 1-3 km), direct validation by tagging of aging methods is logistically difficult. Radiocarbon analysis of both the node organic tissue and internode calcite provided apparently robust age and date information. Growth rates ranged from 40 to ~140 microns per year in samples collected from 600 to 1600m water depth. Following these analyses, we compiled the robust growth-rate data for recent material, and report on a first-pass analysis of ecological and regional effects on isidid growth rates.

  16. Growth rate models for short surface cracks in AI 2219-T851

    NASA Astrophysics Data System (ADS)

    Morris, W. L.; James, M. R.; Buck, O.

    1981-01-01

    Rates of fatigue propagation of short Mode I surface cracks in Al 2219-T851 are measured as a function of crack length and of the location of the surface crack tips relative to the grain boundaries. The measured rates are then compared to values predicted from crack growth models. The crack growth rate is modeled with an underlying assumption that slip responsible for early propagation does not extend in significant amounts beyond the next grain boundary in the direction of crack propagation. Two models that contain this assumption are combined: 1) cessation of propagation into a new grain until a mature plastic zone is developed; 2) retardation of propagation by crack closure stress, with closure stress calculated from the location of a crack tip relative to the grain boundary. The transition from short to long crack growth behavior is also discussed.

  17. Population growth rate determinants for Arbacia: Evaluating ecological relevance of toxicity test endpoints

    SciTech Connect

    Nacci, D.; Gleason, T.; Munns, W.R. Jr.

    1995-12-31

    A population dynamics model for the sea urchin, Arbacia punctulata, was recently developed incorporating life stage endpoints frequently measured in acute and chronic toxicity studies. Model elasticity analysis was used to demonstrate that population growth rate was influenced most by adult survival and least by early life stage success, calling into question the ecological relevance of results from standardized Arbacia fertilization and larval development toxicity tests. Two approaches were used to continue this evaluation. Actual and hypothetical dose-response curves for toxicant exposures over multiple life stages were used to evaluate contributions to population growth rate of stage-specific toxicant effects. Additionally, relationships between critical life stages were developed from laboratory data for Arbacia. The results of this analysis underscore the importance of understanding both endpoint sensitivity to toxicants and sensitivity of population growth rate to test endpoints in determining the ecological relevance of toxicity tests results.

  18. 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

  19. Determination of growth rate depression of some green algae by atrazine

    SciTech Connect

    Hersh, C.M.; Crumpton, W.G.

    1987-12-01

    A common contaminant of surface waters of agricultural regions is the triazine herbicide, atrazine (2-chloro-4-ethylamino-6-isoproplyamino-s-triazine). Atrazine effectively inhibits growth and photosynthesis of most plants, including freshwater algae. Both depression of growth rate and reduced yield have been used as parameters in studies of the effects of atrazine on algal growth. Considerable variation exists among algal toxicity methods despite attempts at standardization. Experimental endpoints range from percent inhibitions to EC50s. Algae from two different Iowa springs were the subjects of a study of naturally occurring atrazine tolerance. The authors report here the results of two aspects of that study: development of a quick method of assessing toxin effects on algal growth, and investigation of a ecologically meaningful endpoint for toxin-growth experiments.

  20. Effects of varying media, temperature, and growth rates on the intracellular concentrations of yeast amino acids.

    PubMed

    Martínez-Force, E; Benítez, T

    1995-01-01

    Variations of the yeast free amino acid pool under different culture conditions were studied in two Saccharomyces strains, the laboratory haploid strain S288C and the industrial fermentative yeast IFI256. The internal amino acid pool of both strains was measured when grown in laboratory (minimal and complete) versus semiindustrial (molasses with or without added biotin and/or diammonium phosphate) media, in fermentable (glucose, fructose, sucrose) versus respirable (glycerol) carbon sources, in different temperatures (22, 30, and 37 degrees C), pHs (2.0-4.75), and growth rates (0.018-0.24 h-1) in continuous culture, and at different phases of the growth curve in batch culture (lag, exponential, early and late stationary). Results indicated that environmental conditions, particularly the presence of amino acids in the media, enormously influenced the intracellular amino acid concentration. Higher values were detected in molasses than in laboratory media and in fermentable carbon sources (glucose, fructose, sucrose) than in glycerol. Variations in the amino acid pool along the growth curve were greater at 37 degrees C than at other temperatures; in all cases, the highest values were measured at the beginning of the exponential phase. In continuous culture and at different growth rates, intracellular free amino acid concentrations increased by 3-10-fold when the growth rate was lower than 0.05 h-1, representing 20-35% of the total (free plus protein) amino acid content and indicating that amino acid yield was a partly growth-linked parameter. PMID:7654310

  1. Pan-Svalbard growth rate variability and environmental regulation in the Arctic bivalve Serripes groenlandicus

    NASA Astrophysics Data System (ADS)

    Carroll, Michael L.; Ambrose, William G.; Levin, Benjamin S.; Locke V, William L.; Henkes, Gregory A.; Hop, Haakon; Renaud, Paul E.

    2011-11-01

    Growth histories contained in the shells of bivalves provide continuous records of environmental and biological information over lifetimes spanning decades to centuries, thereby linking ecosystem responses to both natural and anthropogenic climatic variations over a range of scales. We examined growth rates and temporal growth patterns of 260 individuals of the circumpolar Greenland Smooth Cockle ( Serripes groenlandicus) collected between 1997 and 2009 from 11 sites around the Svalbard Archipelago. These sites encompass a range of oceanographic and environmental conditions, from strongly Atlantic-influenced conditions on the west coast to high-Arctic conditions in northeast Svalbard. Absolute growth was up to three times greater at the most strongly Atlantic-influenced locations compared to the most Arctic-influenced areas, and growth performance was highest at sites closest to the West Spitsbergen Current. We also developed growth chronologies up to 34 years in length extending back to 1974. Standardized growth indices (SGI) exhibited substantial inter-site variability, but there were also common temporal features including steadily increasing growth from the late 1980's to the mid-1990's followed by a marked shift from relatively greater to poorer growth in the mid-1990's and from 2004 to 2008. This pattern was consistent with phase-shifts in large-scale climatic drivers. Interannual variability in SGI was also related to local manifestations of the large-scale drivers, including sea temperature and sea ice extent. The temporal growth pattern at Rijpfjorden, on northeast Svalbard, was broadly representative (R = 0.81) of the entire dataset. While there were site-related differences in the specific relationships between growth and environmental parameters, the aggregated dataset indicated an overriding regional driver of bivalve growth: the Arctic Climate Regime Index (ACRI). These results demonstrate that sclerochronological proxies can be useful retrospective

  2. Improved growth rates and purity of basic ammonothermal GaN

    NASA Astrophysics Data System (ADS)

    Pimputkar, S.; Kawabata, S.; Speck, J. S.; Nakamura, S.

    2014-10-01

    Improvements to the experimental setup for the basic ammonothermal growth of GaN and the introduction of a silver capsule into the autoclave have yielded an ultrahigh purity (UHP) growth environment with reproducible external wall temperature profiles to within the error of the thermocouples (type K with special limits of error (SLE), ±2.5 °C). 40 basic ammonothermal growth runs were performed on hydride vapor phase epitaxy (HVPE) GaN seed crystals with different crystal orientations to optimize the growth system. Due to the UHP growth environment, transition metal impurities in the GaN crystals were reduced to less than 1×1017 cm-3 and oxygen impurity concentrations were comparable to those of the polycrystalline HVPE GaN source material (1×1019 cm-3). Total growth rates improved to 344±30 μm/day for c-plane growth and 46±2 μm/day for m-plane growth. The crystal quality, as measured by the full width at half maximum (FWHM) of the ω-rocking curve using X-ray diffraction (ω-XRC), was comparable to that of the seed crystal, except for Ga-face growth on c-plane oriented seeds due to poor nucleation and cracking in thick growth layers due to strain originating from the HVPE seed crystals. The difference in total system pressure profiles during growth runs using autoclaves with and without a silver capsule was analyzed and the pressure drop due to outward diffusion of hydrogen during growth was modeled.

  3. Global observation of nitrous oxide: changes in growth rate and spatial patterns

    NASA Astrophysics Data System (ADS)

    Hall, B. D.; Dlugokencky, E. J.; Dutton, G. S.; Nance, J. D.; Crotwell, A. M.; Mondeel, D. J.; Elkins, J. W.

    2015-12-01

    Nitrous oxide (N2O) currently exerts the third largest climate forcing of the long-lived greenhouse gases, after CO2 and CH4. N2O is also involved in the destruction of stratospheric ozone. It is produced by microbial activity in soils and oceans, and also by industry. The atmospheric burden of N2O has increased more than 20% from its preindustrial level of ~270 nmol mol-1 (ppb). Much of this increase is related to the application of nitrogen-containing fertilizers, including manure. The NOAA Global Monitoring Division has measured the atmospheric mole fraction of N2O at Earth's surface in air samples collected around the globe (since the late 1970s) and at in situ sites mostly in the Western Hemisphere (since 1998). ). Measurements of the global burden and growth rate constrain global emissions, e.g. 18.2 ± 2.7 Tg N yr-1 in 2013, where most of the uncertainty is related to uncertainty in the global lifetime. The average growth rate of N2O from 1990 to 2010 was ~0.75 ppb yr-1. Since 2004, however, the growth rate has been increasing, and is now about 25% higher than the 1990-2010 average. Between 2010 and 2013 the growth rate averaged ~0.95 ppb yr-1. As the growth rate increased from 2004-2013, gradients derived from surface, zonal-mean N2O mole fraction, such the mean pole-to-pole difference, and the difference between NH temperate latitudes and the southern polar region, decreased. This suggests a change in the distribution of N2O emissions over this period. We will present our N2O data and examine trends, gradients, and other features that could shed light on recent changes in the growth rate. We will also compare N2O gradients to those of other trace gases, such as SF6.

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

    NASA Astrophysics Data System (ADS)

    Vinzenz Ullmann, Clemens

    2016-04-01

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

  5. Influence of arterial geometry on a model for growth rate of atheromas

    NASA Astrophysics Data System (ADS)

    Gessaghi, Valeria C.; Raschi, Marcelo A.; Larreteguy, Axel E.; Perazzo, y. Carlos A.

    2007-11-01

    Atherosclerosis is a disease that affects medium and large size arteries and it can partially or totally obstruct blood flow through them. The lack of blood supply to the heart or the brain can cause an infarct or a stroke with fatal consequences or permanent effects. This disease involves the proliferation of cells and the accumulation of fat, cholesterol, cell debris, calcium and other substances in the artery wall. Such accumulation results in the formation of atherosclerotic plaques called atheromas, which may cause the obstruction of the blood flow. Cardiovascular diseases, among which atherosclerosis is the most frequent, are the first cause of death in developed countries. The published works in the subject suggest that hemodynamic forces on arterial walls have influence on the localization, initial development and growth rate of atheromas. This paper presents a model for this growth rate, and explores the influence of the bifurcation angle on the blood flow patterns and on the predictions of the model in a simplified carotid artery. The choice of the carotid bifurcation as the subject for this study obeys the fact that atheromas in this artery are often responsible for strokes. Our model predicts a larger initial growth rate in the external walls of the bifurcation and smaller growth area and lower growth rates as the bifurcation angle is increased. The reason for this seems to be the appearance of helical flow patterns as the angle is increased.

  6. Periodic increases in elongation rate precede increases in cytosolic Ca2+ during pollen tube growth.

    PubMed

    Messerli, M A; Créton, R; Jaffe, L F; Robinson, K R

    2000-06-01

    Pollen tubes grown in vitro require an intracellular tip-high gradient of Ca2+ in order to elongate. Moreover, after about 2 h in vitro both the tip Ca2+ and the elongation rate of lily tubes begin to oscillate regularly with large amplitudes. This raises the question of the phase relation between these two oscillations. Previous studies lacked the temporal resolution to accurately establish this relationship. We have studied these oscillations with a newly developed, high temporal resolution system and the complementary use of both luminescent and fluorescent calcium reporters. We hereby show that the periodic increases in elongation rate during oscillatory growth of Lilium longiflorum pollen tubes clearly precede those in subtip calcium and do so by 4.1 +/- 0.2 s out of average periods of 38.7 +/- 1.8 s. Also, by collecting images of the light output of aequorin, we find that the magnitude of the [Ca2+] at the tip oscillates between 3 and 10 microM, which is considerably greater than that reported by fluorescent indicators. We propose an explanatory model that features cyclic growth and secretion in which growth oscillations give rise to secretion that is essential for the subsequent growth oscillation. We also critically compile data on L. longiflorum stylar growth rates, which show little variation from in vitro rates of pollen tubes grown in optimal medium. PMID:10885748

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

    PubMed

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

    2016-01-01

    Complex regulatory programs control cell adaptation to environmental changes by setting condition-specific proteomes. In balanced growth, bacterial protein abundances depend on the dilution rate, transcript abundances and transcript-specific translation efficiencies. We revisited the current theory claiming the invariance of bacterial translation efficiency. By integrating genome-wide transcriptome datasets and datasets from a library of synthetic gfp-reporter fusions, we demonstrated that translation efficiencies in Bacillus subtilis decreased up to fourfold from slow to fast growth. The translation initiation regions elicited a growth rate-dependent, differential production of proteins without regulators, hence revealing a unique, hard-coded, growth rate-dependent mode of regulation. We combined model-based data analyses of transcript and protein abundances genome-wide and revealed that this global regulation is extensively used in B. subtilis We eventually developed a knowledge-based, three-step translation initiation model, experimentally challenged the model predictions and proposed that a growth rate-dependent drop in free ribosome abundance accounted for the differential protein production. PMID:27193784

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

    PubMed

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

    2015-03-01

    Previous studies have shown that exposure to extremely low-frequency electromagnetic fields (ELF-EMFs) have negative effects on the rate of growth of bacteria. In the present study, two Gram-positive and two Gram-negative species were exposed to six magnetic field conditions in broth cultures. Three variations of the 'Thomas' pulsed frequency-modulated pattern; a strong-static "puck" magnet upwards of 5000G in intensity; a pair of these magnets rotating opposite one another at ∼30rpm; and finally a strong dynamic magnetic field generator termed the 'Resonator' with an average intensity of 250μT were used. Growth rate was discerned by optical density (OD) measurements every hour at 600nm. ELF-EMF conditions significantly affected the rates of growth of the bacterial cultures, while the two static magnetic field conditions were not statistically significant. Most interestingly, the 'Resonator' dynamic magnetic field increased the rates of growth of three species (Staphylococcus epidermidis, Staphylococcus aureus, and Escherichia coli), while slowing the growth of one (Serratia marcescens). We suggest that these effects are due to individual biophysical characteristics of the bacterial species. PMID:25721476

  9. Growth rates and auxin effects in graviresponding gynophores of the peanut, Arachis hypogaea (Fabaceae).

    PubMed

    Moctezuma, E; Feldman, L J

    1998-10-01

    The gynophore of the peanut plant (Arachis hypogaea) is a specialized organ that carries and buries the fertilized ovules into the soil in order for seed and fruit development to occur underground. The rates of growth of vertically and horizontally oriented gynophores were measured using a time-lapse video imaging system. We found that the region of maximum extension growth due to elongation (termed the Central Elongation Zone) is located on average at 2-5 mm from the tip. In the first 0-4 h after horizontal reorientation (gravistimulation), new zones of growth emerge on the upper surface, while the elongation zone of the lower side decreases in size and magnitude. Four to six hours after reorientation the zones of maximum growth are almost equal in size and location on the upper and lower sides. The growth rate and the gravitropic response decreased dramatically, upon the excision of the ovule region (terminal 1.5 mm), but a gravitropic growth response could be restored by applying the auxin indole-3-acetic acid exogenously to the excised tip. The addition of napthylphthalamic acid (an auxin transport inhibitor) at the ovule region allowed some growth to occur, but the gynophores do not respond normally to gravity, upon horizontal reorientation. We discuss the role of auxin in the gravitropic response of the gynophore. PMID:11541946

  10. Single high-dose vs. fractionated radiotherapy: Effects on plant growth rates

    PubMed Central

    Guedea, Marc; Castel, Antoni; Arnalte, Marc; Mollera, Alex; Muñoz, Victor; Guedea, Ferran

    2013-01-01

    Aim To evaluate the differential effects of fractionated vs. high-dose radiotherapy on plant growth. Background Interest in hypofractionated radiotherapy has increased substantially in recent years as tumours (especially of the lung, prostate, and liver) can be irradiated with ever greater accuracy due to technological improvements. The effects of low-dose ionizing radiation on plant growth have been studied extensively, yet few studies have investigated the effect of high-dose, hypofractionated radiotherapy on plant growth development. Materials and methods A total of 150 plants from the genus Capsicum annuum were randomized to receive fractionated radiotherapy (5 doses of 10 Gy each), single high-dose (SHD) radiotherapy (single 50 Gy dose), or no radiotherapy (control group). Irradiation was delivered via linear accelerator and all samples were followed daily for 26 days to assess and compare daily growth. Results On day 26, plants in the control, fractionated, and SHD groups had grown to a mean height of 7.55 cm, 4.32 cm, and 2.94 cm, respectively. These differences in overall growth were highly significant (P = 0.005). The SHD group showed the least amount of growth. Conclusions SHD effectively stunts plant growth and development. Despite the evident differences between plant and animal cells, ionizing radiation is believed to work in a similar manner in all biological cells. These findings highlight the need to continue investigating the use of hypofractionated schemes in humans to improve cancer treatment outcomes. PMID:24416565

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

    SciTech Connect

    McMurry, Peter; Smuth, James

    2015-11-12

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

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

    PubMed

    Soucek, David John

    2007-08-01

    Sodium sulfate is a ubiquitous salt that reaches toxic concentrations due to mining and other industrial activities, yet is currently unregulated at the Federal level in the United States. Previous studies have documented reduced growth of clams downstream of sulfate-dominated effluents, altered bioenergetics in filter-feeding invertebrates, and interactions between sulfate and other toxicants. Therefore, the purpose of this study was to determine if sodium sulfate affects the bioenergetics of the filter-feeding, freshwater bivalve, Corbicula fluminea, and the mechanism by which the effects are elicited. In addition to measuring effects on feeding, respiration and growth rates, I evaluated the relative sensitivity of a green algae consumed by clams to determine if top-down or bottom-up effects might be exhibited under field conditions. This study demonstrated that sodium sulfate had no effect on basal metabolic rates, but significantly reduced the feeding, post-feeding metabolic, and growth rates of C. fluminea. The proposed mechanism for these impacts is that filtering rates are reduced upon exposure, resulting in reduced food consumption and therefore, preventing increased metabolic rates normally associated with post-feeding specific dynamic action (SDA). In the field, these effects may cause changes in whole stream respiration rates and organic matter dynamics, as well as alter uptake rates of other food-associated contaminants like selenium, the toxicity of which is known to be antagonized by sulfate, in filter-feeding bivalves. PMID:17590452

  13. High rates of growth recorded for hawksbill sea turtles in Anegada, British Virgin Islands

    PubMed Central

    Hawkes, Lucy A; McGowan, Andrew; Broderick, Annette C; Gore, Shannon; Wheatley, Damon; White, Jim; Witt, Matthew J; Godley, Brendan J

    2014-01-01

    Management of species of conservation concern requires knowledge of demographic parameters, such as rates of recruitment, survival, and growth. In the Caribbean, hawksbill turtles (Eretmochelys imbricata) have been historically exploited in huge numbers to satisfy trade in their shells and meat. In the present study, we estimated growth rate of juvenile hawksbill turtles around Anegada, British Virgin Islands, using capture–mark–recapture of 59 turtles over periods of up to 649 days. Turtles were recaptured up to six times, having moved up to 5.9 km from the release location. Across all sizes, turtles grew at an average rate of 9.3 cm year−1 (range 2.3–20.3 cm year−1), and gained mass at an average of 3.9 kg year−1 (range 850 g–16.1 kg year−1). Carapace length was a significant predictor of growth rate and mass gain, but there was no relationship between either variable and sea surface temperature. These are among the fastest rates of growth reported for this species, with seven turtles growing at a rate that would increase their body size by more than half per year (51–69% increase in body length). This study also demonstrates the importance of shallow water reef systems for the developmental habitat for juvenile hawksbill turtles. Although growth rates for posthatching turtles in the pelagic, and turtles larger than 61 cm, are not known for this population, the implications of this study are that Caribbean hawksbill turtles in some areas may reach body sizes suggesting sexual maturity in less time than previously considered. PMID:24834324

  14. Plasma Instability Growth Rates in the F-Region Cusp Ionosphere

    NASA Astrophysics Data System (ADS)

    Moen, J. I.; Daabakk, Y.; Oksavik, K.; Clausen, L.; Bekkeng, T. A.; Abe, T.; Saito, Y.; Baddeley, L. J.; Lorentzen, D. A.; Sigernes, F.; Yeoman, T. K.

    2014-12-01

    There are at least two different micro-instability processes that applies to the F-region cusp/polar cap ionosphere. These are the Gradient Drift Instability (GDI) and the Kelvin Helmholtz Instability (KHI). Due to space weather effects on radio communication and satellite signals it is of practical interest to assess the relative importance of these two instability modes and to quantify their growth rates. The Investigation of Cusp Irregularities (ICI) rocket program has been developed to investigate these plasma instabilities and formation scintillation irregularities. High resolution measurements are critical to get realistic quantities on the growth rates. The results achieved so far demonstrates that cusp ionosphere precipitation can give rise to km scale plasma structures on which grow rates are down to a few tens of seconds compared to earlier measures of ten minutes based on ground observations. This has to do with the spatial resolution required for these measurements. Growth rates for the KHI instability is found to be of the same order, which is consistent with growth rates calculated from the EISCAT Svalbard Radar. I.e. both instability modes can be highly efficient in the cusp ionosphere.

  15. Survival, recruitment, and population growth rate of an important mesopredator: the northern raccoon.

    PubMed

    Troyer, Elizabeth M; Cameron Devitt, Susan E; Sunquist, Melvin E; Goswami, Varun R; Oli, Madan K

    2014-01-01

    Populations of mesopredators (mid-sized mammalian carnivores) are expanding in size and range amid declining apex predator populations and ever-growing human presence, leading to significant ecological impacts. Despite their obvious importance, population dynamics have scarcely been studied for most mesopredator species. Information on basic population parameters and processes under a range of conditions is necessary for managing these species. Here we investigate survival, recruitment, and population growth rate of a widely distributed and abundant mesopredator, the northern raccoon (Procyon lotor), using Pradel's temporal symmetry models and >6 years of monthly capture-mark-recapture data collected in a protected area. Monthly apparent survival probability was higher for females (0.949, 95% CI = 0.936-0.960) than for males (0.908, 95% CI = 0.893-0.920), while monthly recruitment rate was higher for males (0.091, 95% CI = 0.078-0.106) than for females (0.054, 95% CI = 0.042-0.067). Finally, monthly realized population growth rate was 1.000 (95% CI = 0.996-1.004), indicating that our study population has reached a stable equilibrium in this relatively undisturbed habitat. There was little evidence for substantial temporal variation in population growth rate or its components. Our study is one of the first to quantify survival, recruitment, and realized population growth rate of raccoons using long-term data and rigorous statistical models. PMID:24901349

  16. Regulation of phosphorus stoichiometry and growth rate of consumers: theoretical and experimental analyses with Daphnia.

    PubMed

    Shimizu, Yuichiro; Urabe, Jotaro

    2008-02-01

    Initial theories of ecological stoichiometry were based on the assumption that the mass-specific content of key nutrient elements (such as P), changes little within a consumer species. However, evidence has shown that this content changes substantially according to feeding conditions. To clarify how the specific P content (S (P)) of a consumer species depends on food conditions and relates to the growth rate, we constructed a multiple mass-balance model incorporating feeding and metabolic costs and stoichiometrically regulated releases for C and P. The validity of the model was then tested experimentally by examining the growth rates and S (P) of Daphnia pulicaria under various food conditions. The experimental observation agreed qualitatively well with the model, showing that the S (P) of consumers relates positively to growth rate at high food C:P ratios but negatively at low food C:P ratios. Thus, within a consumer species, individuals with high S (P) do not necessarily grow at high rates. The concordance in results between the model and our observation suggests that maintenance costs for both P and C are substantial regardless of food conditions and play crucial roles in determining the relationship between the S (P) and growth rate of consumers. PMID:17989999

  17. Delta L: An Apparatus for Measuring Macromolecule Crystal Growth Rates in Microgravity

    NASA Technical Reports Server (NTRS)

    Judge, Russell A.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Strongly diffracting high quality macromolecule crystals of suitable volume are keenly sought for X-ray diffraction analysis so that high-resolution molecular structure data can be obtained. Such data is of tremendous value to medical research, agriculture and commercial biotechnology. In previous studies by many investigators microgravity has been reported in some instances to improve biological macromolecule X-ray crystal quality while little or no improvement was observed in other cases. A better understanding of processes effecting crystal quality improvement in microgravity will therefore be of great benefit in optimizing crystallization success in microgravity. In ground based research with the protein lysozyme we have previously shown that a population of crystals grown under the same solution conditions, exhibit a variation in X-ray diffraction properties (Judge et al., 1999). We have also observed that under the same solution conditions, individual crystals will grow at slightly different growth rates. This phenomenon is called growth rate dispersion. For small molecule materials growth rate dispersion has been directly related to crystal quality (Cunningham et al., 1991; Ristic et al., 1991). We therefore postulate that microgravity may act to improve crystal quality by reducing growth rate dispersion. If this is the case then as different, Materials exhibit different degrees of growth rate dispersion on the ground then growth rate dispersion could be used to screen which materials may benefit the most from microgravity crystallization. In order to assess this theory the Delta L hardware is being developed so that macromolecule crystal growth rates can be measured in microgravity. Crystal growth rate is defined as the change or delta in crystal size (defined as a characteristic length, L) over time; hence the name of the hardware. Delta L will consist of an optics, a fluids, and a data acquisition sub-assemblies. The optics assembly will consist of a

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

    USGS Publications Warehouse

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

    2016-01-01

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

  19. Morphology and mycelial growth rate of Pleurotus spp. strains from the Mexican mixtec region

    PubMed Central

    Guadarrama-Mendoza, P.C.; del Toro, G. Valencia; Ramírez-Carrillo, R.; Robles-Martínez, F.; Yáñez-Fernández, J.; Garín-Aguilar, M.E.; Hernández, C.G.; Bravo-Villa, G.

    2014-01-01

    Two native Pleurotus spp. strains (white LB-050 and pale pink LB-051) were isolated from rotten tree trunks of cazahuate (Ipomoea murucoides) from the Mexican Mixtec Region. Both strains were chemically dedikaryotized to obtain their symmetrical monokaryotic components (neohaplonts). This was achieved employing homogenization time periods from 60 to 65 s, and 3 day incubation at 28 °C in a peptone-glucose solution (PGS). Pairing of compatible neohaplonts resulted in 56 hybrid strains which were classified into the four following hybrid types: (R1-nxB1-n, R1-nxB2-1, R2-nxB1-n and R2-nxB2-1). The mycelial growth of Pleurotus spp. monokaryotic and dikaryotic strains showed differences in texture (cottony or floccose), growth (scarce, regular or abundant), density (high, regular or low), and pigmentation (off-white, white or pale pink). To determine the rate and the amount of mycelium growth in malt extract agar at 28 °C, the diameter of the colony was measured every 24 h until the Petri dish was completely colonized. A linear model had the best fit to the mycelial growth kinetics. A direct relationship between mycelial morphology and growth rate was observed. Cottony mycelium presented significantly higher growth rates (p < 0.01) in comparison with floccose mycelium. Thus, mycelial morphology can be used as criterion to select which pairs must be used for optimizing compatible-mating studies. Hybrids resulting from cottony neohaplonts maintained the characteristically high growth rates of their parental strains with the hybrid R1-nxB1-n being faster than the latter. PMID:25477920

  20. Morphology and mycelial growth rate of Pleurotus spp. strains from the Mexican mixtec region.

    PubMed

    Guadarrama-Mendoza, P C; del Toro, G Valencia; Ramírez-Carrillo, R; Robles-Martínez, F; Yáñez-Fernández, J; Garín-Aguilar, M E; Hernández, C G; Bravo-Villa, G

    2014-01-01

    Two native Pleurotus spp. strains (white LB-050 and pale pink LB-051) were isolated from rotten tree trunks of cazahuate (Ipomoea murucoides) from the Mexican Mixtec Region. Both strains were chemically dedikaryotized to obtain their symmetrical monokaryotic components (neohaplonts). This was achieved employing homogenization time periods from 60 to 65 s, and 3 day incubation at 28 °C in a peptone-glucose solution (PGS). Pairing of compatible neohaplonts resulted in 56 hybrid strains which were classified into the four following hybrid types: (R(1-n)xB(1-n), R(1-n)xB(2-1), R(2-n)xB(1-n) and R(2-n)xB(2-1)). The mycelial growth of Pleurotus spp. monokaryotic and dikaryotic strains showed differences in texture (cottony or floccose), growth (scarce, regular or abundant), density (high, regular or low), and pigmentation (off-white, white or pale pink). To determine the rate and the amount of mycelium growth in malt extract agar at 28 °C, the diameter of the colony was measured every 24 h until the Petri dish was completely colonized. A linear model had the best fit to the mycelial growth kinetics. A direct relationship between mycelial morphology and growth rate was observed. Cottony mycelium presented significantly higher growth rates (p < 0.01) in comparison with floccose mycelium. Thus, mycelial morphology can be used as criterion to select which pairs must be used for optimizing compatible-mating studies. Hybrids resulting from cottony neohaplonts maintained the characteristically high growth rates of their parental strains with the hybrid R(1-n)xB(1-n) being faster than the latter. PMID:25477920

  1. Tropical dendrochemistry: A novel approach for reconstructing seasonally-resolved growth rates from ringless tropical trees

    NASA Astrophysics Data System (ADS)

    Poussart, P. M.; Myneni, S. C.

    2005-12-01

    Although tropical forests play an active role in the global carbon cycle and are host to a variety of pristine paleoclimate archives, they remain poorly characterized as compared to other ecosystems on the planet. In particular, dating and reconstructing the growth rate history of tropical trees remains a challenge and continues to delay research efforts towards understanding tropical forest dynamics. Traditional dendrochronological techniques have found limited applications in the tropics because temperature seasonality is often too small to initiate the production of visible annual growth rings. Dendrometers, cambium scarring methods and sub-annual records of oxygen and carbon isotopes from tree cellulose may be used to estimate growth rate histories when growth rings are absent. However, dendrometer records rarely extend beyond the past couple of decades and the generation of seasonally-resolved isotopic records remains labour intensive, currently prohibiting the level of record replication necessary for statistical analysis. Here, we present evidence that Ca may also be used as a proxy for dating and reconstructing growth rates of trees lacking visible growth rings. Using the Brookhaven National Lab Synchrotron, we recover a radial record of cyclic variations in Ca from a Miliusa velutina tree from northern Thailand. We determine that the Ca cycles are seasonal based on a comparison between radiocarbon age estimates and a trace element age model, which agree within 2 years over the period of 1955 to 2000. The amplitude of the Ca annual cycle is significantly correlated with growth rate estimates, which are also correlated to the amount of dry season rainfall. The measurements at the Synchrotron are fast, non-destructive and require little sample preparation. Application of this technique in the tropics holds the potential to resolve longstanding questions about tropical forest dynamics and interannual to decadal changes in the carbon cycle.

  2. Growth rate for the selective epitaxial growth of III-V compounds inside submicron shallow-trench-isolation trenches on Si (001) substrates by MOVPE: Modeling and experiments

    NASA Astrophysics Data System (ADS)

    Jiang, S.; Merckling, C.; Guo, W.; Waldron, N.; Caymax, M.; Vandervorst, W.; Seefeldt, M.; Heyns, M.

    2014-04-01

    A mathematical model was developed to examine the growth rate of III-V compounds inside sub-micron trenches by MOVPE. Based on this model, we theoretically analyzed the possible dependence of the growth rate on the trench width primarily from two aspects, i.e. Knudson diffusion and enhanced equilibrium vapor pressure due to the shrinking trench size. Then, associated with the experimental data from the growth of both InAlAs and InAs, we found that the average growth rate inside submicron trenches is primarily influenced by trench diffusion type under typical growth conditions.

  3. Contributions to accelerating atmospheric CO2 growth from economic activity, carbon intensity, and efficiency of natural sinks

    SciTech Connect

    Canadella, J.G.; Raupacha, M.R.; Le Quere, C.; Buitenhuis, E.T.; Gillett, N.P.; Field, C.B.; Ciais, P.; Conway, T.J.; Houghton, R.A.; Marland, G.

    2007-11-20

    The