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Sample records for affected zone size

  1. The Effect of Substrate Microstructure on the Heat-Affected Zone Size in Sn-Zn Alloys Due to Adjoining Ni-Al Reactive Multilayer Foil Reaction

    NASA Astrophysics Data System (ADS)

    Hooper, R. J.; Adams, D. P.; Hirschfeld, D.; Manuel, M. V.

    2016-01-01

    The rapid release of energy from reactive multilayer foils can create extreme local temperature gradients near substrate materials. In order to fully exploit the potential of these materials, a better understanding of the interaction between the substrate or filler material and the foil is needed. Specifically, this work investigates how variations in local properties within the substrate (i.e. differences between properties in constituent phases) can affect heat transport into the substrate. This can affect the microstructural evolution observed within the substrate, which may affect the final joint properties. The effect of the initial substrate microstructure on microstructural evolution within the heat-affected zone is evaluated experimentally in two Sn-Zn alloys and numerical techniques are utilized to inform the analysis.

  2. Economic Effects of Increased Control Zone Sizes in Conflict Resolution

    NASA Technical Reports Server (NTRS)

    Datta, Koushik

    1998-01-01

    A methodology for estimating the economic effects of different control zone sizes used in conflict resolutions between aircraft is presented in this paper. The methodology is based on estimating the difference in flight times of aircraft with and without the control zone, and converting the difference into a direct operating cost. Using this methodology the effects of increased lateral and vertical control zone sizes are evaluated.

  3. How Tongue Size and Roughness Affect Lapping

    NASA Astrophysics Data System (ADS)

    Hubbard, M. J.; Hay, K. M.

    2012-10-01

    The biomechanics of domestic cat lapping (Felis catus) and domestic dog lapping (Canis familiaris) is currently under debate. Lapping mechanics in vertebrates with incomplete cheeks, such as cats and dogs, is a balance of inertia and the force of gravity likely optimized for ingestion and physical necessities. Physiology dictates vertebrate mass, which dictates vertebrate tongue size, which dictates lapping mechanics to achieve optimum liquid ingestion; with either touch lapping, scooping, or a hybrid lapping method. The physics of this optimized system then determines how high a column of liquid can be raised before it collapses due to gravity, and therefore, lapping frequency. Through tongue roughness model variation experiments it was found that pore-scale geometrical roughness does not appear to affect lapping or liquid uptake. Through tongue size model variation experiments it was found that there is a critical tongue radius in the range of 25 mm to 35 mm above which touch lapping is no longer an efficient way to uptake liquid. Vertebrates with incomplete cheeks may use a touch lapping method to ingest water if their tongue radius is less than this critical radius and use an alternative ingestion method if their tongue radius is larger.

  4. Characteristics of GTA fusion zones and heat affected zones in superalloy 713C

    NASA Astrophysics Data System (ADS)

    Lachowicz, M. B.; Dudziński, W.

    2012-09-01

    In this paper, metallographic examinations, characterising microstructural changes in the 713C superalloy subjected to remelting by GTA method, are presented. In the fusion zone, precipitation of M23C6 or M6C carbides based on chromium and molybdenum was observed. Eutectic mixtures of ( γ- gg')-M x C y type with highly developed morphology were also perceived. It was found that, in the matrix areas with non-homogeneous chemical composition, the eutectic reaction γ-γ' can occur at the temperature close to that of the precipitation of the M x C y carbides. The presence of silicon in the carbide phases can be conducive to lowering their solidification point by creating low-melting compound NbSi. Both in the fusion zone (FZ) and in the heat-affected zone (HAZ), the secondary precipitates of the Ni3(AlTi)- γ' phase, varying in size from 50 to 100 nm, were found. The lattice mismatch factor of the γ and γ' particles was +0.48 % to +0.71 %, which is characteristic of the coherent precipitates of the Ni3Al phase enriched with titanium. No dislocations or stacking faults were observed in the microstructure of the FZ. In the HAZ, some primary undissolved γ' precipitates, with a part of aluminium probably replaced with niobium were observed, which raised their melting point.

  5. Document zone classification using sizes of connected components

    NASA Astrophysics Data System (ADS)

    Liang, Jisheng; Phillips, Ihsin T.; Ha, Jaekyu; Haralick, Robert M.

    1996-03-01

    In this paper, we describe a feature based supervised zone classifier using only the knowledge of the widths and the heights of the connected-components within a given zone. The distribution of the widths and the heights of the connected-components is encoded into a n multiplied by m dimensional vector in the decision making. Thus, the computational complexity is in the order of the number of connected-components within the given zone. A binary decision tree is used to assign a zone class on the basis of its feature vector. The training and testing data sets for the algorithm are drawn from the scientific document pages in the UW-I database. The classifier is able to classify each given scientific and technical document zone into one of the eight labels: text of font size 8-12, text of font size 13-18, text of font size 19-36, display math, table, halftone, line drawing, and ruling, in real time. The classifier is able to discriminate text from non-text with an accuracy greater than 97%.

  6. Limits on great earthquake size at subduction zones

    NASA Astrophysics Data System (ADS)

    McCaffrey, R.

    2012-12-01

    Subduction zones are where the world's greatest earthquakes occur due to the large fault area available to slip. Yet some subduction zones are thought to be immune from these massive events, where quake size is limited by some physical processes or properties. Accordingly, the size of the 2011 Tohoku-oki Mw 9.0 earthquake caught some in the earthquake research community by surprise. The expectations of these massive quakes have been driven in the past by reliance on our short, incomplete history of earthquakes and causal relationships derived from it. The logic applied is that if a great earthquake has not happened in the past, that we know of, one cannot happen in the future. Using the ~100-year global earthquake seismological history, and in some cases extended with geologic observations, relationships between maximum earthquake sizes and other properties of subduction zones are suggested, leading to the notion that some subduction zones, like the Japan Trench, would never produce a magnitude ~9 event. Empirical correlations of earthquake behavior with other subduction parameters can give false positive results when the data are incomplete or incorrect, of small numbers and numerous attributes are examined. Given multi-century return times of the greatest earthquakes, ignorance of those return times and our relatively limited temporal observation span (in most places), I suggest that we cannot yet rule out great earthquakes at any subduction zones. Alternatively, using the length of a subduction zone that is available for slip as the predominant factor in determining maximum earthquake size, we cannot rule out that any subduction zone of a few hundred kilometers or more in length may be capable of producing a magnitude 9 or larger earthquake. Based on this method, the expected maximum size for the Japan Trench was 9.0 (McCaffrey, Geology, p. 263, 2008). The same approach indicates that a M > 9 off Java, with twice the population density as Honshu and much lower

  7. Crack arrest toughness of a heat-affected zone containing local brittle zones

    SciTech Connect

    Malik, L.; Pussegoda, L.N.; Graville, B.A.; Tyson, W.R.

    1996-11-01

    The awareness of the presence of local brittle zones (LBZs) in the heat-affected zone (HAZ) of welds has led to the requirements for minimum initiation toughness for the HAZ for critical applications. A fracture control philosophy that is proposed to be an attractive alternative for heat-affected zones containing LBZs is the prevention of crack propagation rather than of crack initiation. Such an approach would be viable if it could be demonstrated that cracks initiated in the LBZs will be arrested without causing catastrophic failure, notwithstanding the low initiation (CTOD) toughness resulting from the presence of LBZs. Unstable propagation of a crack initiating from an LBZ requires the rupture of tougher microstructural regions surrounding the LBZ in HAZ, and therefore the CTOD value reflecting the presence of LBZ is unlikely to provide a true indication of the potential for fast fracture along the heat-affected zone. Base metal specifications usually ensure that small unstable cracks propagating from the weld zone into the base metal would be arrested. To investigate the likelihood of fast fracture within the HAZ, a test program has been carried out that involved performing compact plane strain and plane stress crack arrest tests on a heat-affected zone that contained LBZs, and thus exhibited unacceptable low CTOD toughness for resistance to brittle fracture initiation. The results indicated that the crack arrest toughness was little influenced by the presence of local brittle zones. Instead, the superior toughness of the larger proportion of finer-grain HAZ surrounding the LBZ present along the crack path has a greater influence on the crack arrest toughness.

  8. EFFECT OF PARTICLE DIAMETER ON EXCLUSION-ZONE SIZE

    PubMed Central

    NHAN, D.T.; POLLACK, G.H.

    2011-01-01

    Particles and solutes are excluded from the vicinity of hydrophilic surfaces, leaving large microsphere-free regions known as exclusion zones (EZs). Prior work had indicated that EZs could extend to distances of up to several hundred micrometers from the nucleating surface. These observations were made on large, extended surfaces, leaving open the question whether EZ size might depend on the characteristic dimension of the excluding surface. We placed one or few ion-exchange-resin beads whose diameters varied from 15 μm to 300 μm in cuvettes. The beads were suffused with aqueous microsphere suspensions for observing the surfaces’ exclusionary behavior. Results showed a direct relation between bead size and EZ size over the full range of bead diameter, implying a similar relation for smaller particles or molecules, perhaps extending beyond the resolution of the light microscope. PMID:22389653

  9. Root-Zone Glyphosate Exposure Adversely Affects Two Ditch Species

    PubMed Central

    Saunders, Lyndsay E.; Koontz, Melissa B.; Pezeshki, Reza

    2013-01-01

    Glyphosate, one of the most applied herbicides globally, has been extensively studied for its effects on non-target organisms. In the field, following precipitation, glyphosate runs off into agricultural ditches where it infiltrates into the soil and thus may encounter the roots of vegetation. These edge-of-field ditches share many characteristics with wetlands, including the ability to reduce loads of anthropogenic chemicals through uptake, transformation, and retention. Different species within the ditches may have a differential sensitivity to exposure of the root zone to glyphosate, contributing to patterns of abundance of ruderal species. The present laboratory experiment investigated whether two species commonly found in agricultural ditches in southcentral United States were affected by root zone glyphosate in a dose-dependent manner, with the objective of identifying a sublethal concentration threshold. The root zone of individuals of Polygonum hydropiperoides and Panicum hemitomon were exposed to four concentrations of glyphosate. Leaf chlorophyll content was measured, and the ratio of aboveground biomass to belowground biomass and survival were quantified. The findings from this study showed that root zone glyphosate exposure negatively affected both species including dose-dependent reductions in chlorophyll content. P. hydropiperdoides showed the greatest negative response, with decreased belowground biomass allocation and total mortality at the highest concentrations tested. PMID:24833234

  10. Mechanical Properties of Heat Affected Zone of High Strength Steels

    NASA Astrophysics Data System (ADS)

    Sefcikova, K.; Brtnik, T.; Dolejs, J.; Keltamaki, K.; Topilla, R.

    2015-11-01

    High Strength Steels became more popular as a construction material during last decade because of their increased availability and affordability. On the other hand, even though general use of Advanced High Strength Steels (AHSS) is expanding, the wide utilization is limited because of insufficient information about their behaviour in structures. The most widely used technique for joining steels is fusion welding. The welding process has an influence not only on the welded connection but on the area near this connection, the so-called heat affected zone, as well. For that reason it is very important to be able to determine the properties in the heat affected zone (HAZ). This area of investigation is being continuously developed in dependence on significant progress in material production, especially regarding new types of steels available. There are currently several types of AHSS on the world market. Two most widely used processes for AHSS production are Thermo-Mechanically Controlled Processing (TMCP) and Quenching in connection with Tempering. In the presented study, TMCP and QC steels grade S960 were investigated. The study is focused on the changes of strength, ductility, hardness and impact strength in heat affected zone based on the used amount of heat input.

  11. The first Earth-sized habitable zone exoplanets

    NASA Astrophysics Data System (ADS)

    Barclay, T.; Quintana, E.

    2014-03-01

    The goal of the Kepler mission is the discovery of Earth-sized planets orbiting within the habitable zone (HZ) of their host star. Most HZ planets found to date are gas giants, but a few such as Kepler-62f are potentially rocky despite being larger than Earth. Here we report on the progress being made to identify transiting planets in Kepler data that are truly Earth-sized and unambiguously terrestrial in nature. We consider the structure of the identified systems and deduce likely formation scenarios. We consider whether water delivery to these planets is probable or even possible. The discovery of the first Earth-like planets will be a milestone on the road toward the finding life outside our solar system.

  12. Particle size and energetics of gouge from earthquake rupture zones.

    PubMed

    Wilson, Brent; Dewers, Thomas; Reches, Ze'ev; Brune, James

    2005-04-01

    Grain size reduction and gouge formation are found to be ubiquitous in brittle faults at all scales, and most slip along mature faults is observed to have been localized within gouge zones. This fine-grain gouge is thought to control earthquake instability, and thus understanding its properties is central to an understanding of the earthquake process. Here we show that gouge from the San Andreas fault, California, with approximately 160 km slip, and the rupture zone of a recent earthquake in a South African mine with only approximately 0.4 m slip, display similar characteristics, in that ultrafine grains approach the nanometre scale, gouge surface areas approach 80 m2 g(-1), and grain size distribution is non-fractal. These observations challenge the common perception that gouge texture is fractal and that gouge surface energy is a negligible contributor to the earthquake energy budget. We propose that the observed fine-grain gouge is not related to quasi-static cumulative slip, but is instead formed by dynamic rock pulverization during the propagation of a single earthquake. PMID:15815626

  13. The role of cyclic plastic zone size on fatigue crack growth behavior in high strength steels

    NASA Astrophysics Data System (ADS)

    Korda, Akhmad A.; Miyashita, Y.; Mutoh, Y.

    2015-09-01

    The role of cyclic plastic zone in front of the crack tip was studied in high strength steels. Estimated plastic zone size would be compared with actual observation. Strain controlled fatigue tests of the steels were carried out to obtain cyclic stress-strain curves for plastic zone estimation. Observations of plastic zone were carried out using in situ SEM fatigue crack growth tests under a constant-ΔK. Hard microstructures in structural steels showed to inhibit the extent of plastic deformation around the crack tip. The rate of crack growth can be correlated with the size of plastic zone. The smaller the plastic zone size, the slower the fatigue crack growth.

  14. Scalable screen-size enlargement by multi-channel viewing-zone scanning holography.

    PubMed

    Takaki, Yasuhiro; Nakaoka, Mitsuki

    2016-08-01

    Viewing-zone scanning holographic displays can enlarge both the screen size and the viewing zone. However, limitations exist in the screen size enlargement process even if the viewing zone is effectively enlarged. This study proposes a multi-channel viewing-zone scanning holographic display comprising multiple projection systems and a planar scanner to enable the scalable enlargement of the screen size. Each projection system produces an enlarged image of the screen of a MEMS spatial light modulator. The multiple enlarged images produced by the multiple projection systems are seamlessly tiled on the planar scanner. This screen size enlargement process reduces the viewing zones of the projection systems, which are horizontally scanned by the planar scanner comprising a rotating off-axis lens and a vertical diffuser to enlarge the viewing zone. A screen size of 7.4 in. and a viewing-zone angle of 43.0° are demonstrated. PMID:27505840

  15. Understanding Correlation: Factors that Affect the Size of r

    ERIC Educational Resources Information Center

    Goodwin, Laura D.; Leech, Nancy L.

    2006-01-01

    The authors describe and illustrate 6 factors that affect the size of a Pearson correlation: (a) the amount of variability in the data, (b) differences in the shapes of the 2 distributions, (c) lack of linearity, (d) the presence of 1 or more "outliers," (e) characteristics of the sample, and (f) measurement error. Also discussed are ways to…

  16. Offspring size in a resident species affects community assembly.

    PubMed

    Davis, Kurt; Marshall, Dustin J

    2014-03-01

    Offspring size is a trait of fundamental importance that affects the ecology and evolution of a range of organisms. Despite the pervasive impact of offspring size for those offspring, the influence of offspring size on other species in the broader community remains unexplored. Such community-wide effects of offspring size are likely, but they have not been anticipated by theory or explored empirically. For a marine invertebrate community, we manipulated the size and density of offspring of a resident species (Watersipora subtorquata) in the field and examined subsequent community assembly around that resident species. Communities that assembled around larger offspring were denser and less diverse than communities that assembled around smaller offspring. Differences in niche usage by colonies from smaller and larger offspring may be driving these community-level effects. Our results suggest that offspring size is an important but unexplored source of ecological variation and that life-history theory must accommodate the effects of offspring size on community assembly. Life-history theory often assumes that environmental variation drives intraspecific variation in offspring size, and our results show that the converse can also occur. PMID:26046291

  17. Bead temperature effects on FCAW heat-affected zone hardness

    SciTech Connect

    Kiefer, J.H.

    1995-11-01

    Hardness limits for welding procedure qualification are often imposed to lessen the chances of delayed hydrogen cracking during production fabrication. Temper bead techniques have been used by fabricators during these qualifications to improve their chances of success. This practice involves using the heat of additional weld beads to soften the heat-affected zone (HAZ) hardness in the base metal next to the weld where the hardness is the greatest. The technique works under controlled conditions, but the consistency for field use was questionable. This report describes an investigate of the effect of welding parameters, base metal chemical composition, and weld bead placement on HAZ softening. An empirical formula developed from base plate chemical composition, weld cooling time, and temper bead placement can be used to estimate the amount of HAZ tempering. Combined with an appropriate hardness prediction formula, it can help find the welding procedure needed to achieve a desired maximum HAZ hardness, or predict the HAZ hardness of existing welds. Based on the results of the study, bead temperature is not recommended for HAZ hardness control on large scale fabrications.

  18. Sneaker Males Affect Fighter Male Body Size and Sexual Size Dimorphism in Salmon.

    PubMed

    Weir, Laura K; Kindsvater, Holly K; Young, Kyle A; Reynolds, John D

    2016-08-01

    Large male body size is typically favored by directional sexual selection through competition for mates. However, alternative male life-history phenotypes, such as "sneakers," should decrease the strength of sexual selection acting on body size of large "fighter" males. We tested this prediction with salmon species; in southern populations, where sneakers are common, fighter males should be smaller than in northern populations, where sneakers are rare, leading to geographical clines in sexual size dimorphism (SSD). Consistent with our prediction, fighter male body size and SSD (fighter male∶female size) increase with latitude in species with sneaker males (Atlantic salmon Salmo salar and masu salmon Oncorhynchus masou) but not in species without sneakers (chum salmon Oncorhynchus keta and pink salmon Oncorhynchus gorbuscha). This is the first evidence that sneaker males affect SSD across populations and species, and it suggests that alternative male mating strategies may shape the evolution of body size. PMID:27420790

  19. Clonal Patch Size and Ramet Position of Leymus chinensis Affected Reproductive Allocation

    PubMed Central

    Zhang, Zhuo; Yang, Yunfei

    2015-01-01

    Reproductive allocation is critically important for population maintenance and usually varies with not only environmental factors but also biotic ones. As a typical rhizome clonal plant in China's northern grasslands, Leymus chinensis usually dominates the steppe communities and grows in clonal patches. In order to clarify the sexual reproductive allocation of L. chinensis in the process of the growth and expansion, we selected L. chinensis clonal patches of a range of sizes to examine the reproductive allocation and allometric growth of the plants. Moreover, the effects of position of L. chinensis ramets within the patch on their reproductive allocation were also examined. Clonal patch size and position both significantly affected spike biomass, reproductive tiller biomass and SPIKE/TILLER biomass ratio. From the central to the marginal zone, both the spike biomass and reproductive tiller biomass displayed an increasing trend in all the five patch size categories except for reproductive tiller biomass in 15–40m2 category. L. chinensis had significantly larger SPIKE/TILLER biomass ratio in marginal zone than in central zone of clonal patches that are larger than 15 m2 in area. Regression analysis showed that the spike biomass and SPIKE/TILLER biomass ratio were negatively correlated with clonal patch size while patch size showed significantly positive effect on SEED/SPIKE biomass ratio, but the reproductive tiller biomass and SEED/TILLER biomass ratio were not dependent on clonal patch size. The relationships between biomass of spike and reproductive tiller, between mature seed biomass and spike biomass and between mature seed biomass and reproductive tiller biomass were significant allometric for all or some of patch size categories, respectively. The slopes of all these allometric relationships were significantly different from 1. The allometric growth of L. chinensis is patch size-dependent. This finding will be helpful for developing appropriate practices for

  20. Does body size affect a bird's sensitivity to patch size and landscape structure?

    USGS Publications Warehouse

    Winter, M.; Johnson, D.H.; Shaffer, J.A.

    2006-01-01

    Larger birds are generally more strongly affected by habitat loss and fragmentation than are smaller ones because they require more resources and thus larger habitat patches. Consequently, conservation actions often favor the creation or protection of larger over smaller patches. However, in grassland systems the boundaries between a patch and the surrounding landscape, and thus the perceived size of a patch, can be indistinct. We investigated whether eight grassland bird species with different body sizes perceived variation in patch size and landscape structure in a consistent manner. Data were collected from surveys conducted in 44 patches of northern tallgrass prairie during 1998-2001. The response to patch size was very similar among species regardless of body size (density was little affected by patch size), except in the Greater Prairie-Chicken (Tympanuchus cupido), which showed a threshold effect and was not found in patches smaller than 140 ha. In landscapes containing 0%-30% woody vegetation, smaller species responded more negatively to increases in the percentage of woody vegetation than larger species, but above an apparent threshold of 30%, larger species were not detected. Further analyses revealed that the observed variation in responses to patch size and landscape structure among species was not solely due to body size per se, but to other differences among species. These results indicate that a stringent application of concepts requiring larger habitat patches for larger species appears to limit the number of grassland habitats that can be protected and may not always be the most effective conservation strategy. ?? The Cooper Ornithological Society 2006.

  1. TEM observation of the heat-affected zone in electron beam welded superalloy Inconel 713C

    SciTech Connect

    Lachowicz, Maciej Dudzinski, Wlodzimierz; Podrez-Radziszewska, Marzena

    2008-05-15

    The paper presents results of microstructural observations and phase analysis of electron-beam-welded fusion zones in superalloy Inconel 713C using transmission electron microscopy. In the fusion zone, a 90% fraction of fine-grained {gamma}' precipitates was found, with sizes up to 30 nm. No dislocations were observed in the precipitates or at the {gamma}-{gamma}' interface. Primary, undissolved inclusions of {gamma}' were found in the heat-affected zone (HAZ). In the HAZ, a very high concentration of dislocations was found at the {gamma}-{gamma}' boundaries, as well as inside the {gamma}' particles and in the {gamma} solid solution. The increased dislocation density indicates loss of coherence of that phase and the creation of a semi-coherent boundary, and is related to dissolution of the particles and intensified diffusion through the interphase {gamma}-{gamma}' boundary. The lattice misfit coefficient {delta}a/a between the {gamma}' particles and {gamma} solution in the HAZ indicates negative values from - 0.20% to - 0.06%. The presence of semi-coherent boundaries and the negative lattice misfit coefficient leads to dislocation locking and can result in cracking in the HAZ.

  2. Rate of language evolution is affected by population size.

    PubMed

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

    2015-02-17

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

  3. Rate of language evolution is affected by population size

    PubMed Central

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

    2015-01-01

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

  4. Grain size in lithospheric-scale shear zones: Chicken or Egg?

    NASA Astrophysics Data System (ADS)

    Thielmann, M.; Rozel, A.; Kaus, B. J. P.; Ricard, Y.

    2012-04-01

    Lithospheric-scale shear zones are commonly defined as regions inhomogeneous and localized deformation. Strain softening has been demonstrated to be necessary for localization in those shear zones, but there is still debate about the physical cause of this softening. As natural shear zones typically have a significantly reduced grain size, it has been proposed that grain size reduction provides the necessary strain softening to localize deformation. As grain size reduces, the dominant deformation mechanism switches from dislocation to diffusion creep, thus requiring less stress to deform the rock. Until recently, the equilibrium grain size has been thought to follow a piezometric relationship, thus indicating the stress under which a shear zone deformed. More recent work (Austin and Evans (2007), Rozel et. al. (2011)) suggests that the equilibrium grain size is not dependent on stress, but rather on the deformational work. Using this relationship, we use numerical models to investigate the effect of grain size evolution on lithospheric deformation. We focus on the question if grain size provides sufficient weakening to effectively localize deformation under lithospheric conditions or if it's effect is rather passive and as such a marker for the deformational work done in a shear zone. We then compare the localization potential of grain size reduction to shear heating and investigate the interplay between the two weakening mechanisms.

  5. The effect of the melt thermal gradient on the size of the constitutionally supercooled zone

    NASA Astrophysics Data System (ADS)

    Prasad, A.; Yuan, L.; Lee, P. D.; Easton, M.; StJohn, D.

    2016-03-01

    Recent verification of the analytical Interdependence model by a numerical solidification model (µMatIC) confirmed the critical role of constitutional supercooling (CS) in achieving sufficient undercooling to trigger successful nucleation events. The location of the maximum amount of CS (ΔTCSmax) is some distance from the interface of the previously growing grain and this distance contributes to the final as-cast grain size. The effect of the thermal gradient, G, on the size of the CS zone (CSZ) was neglected in that work. However, G is expected to affect the size of the CSZ (i.e. the length of the CSZ, x’ CSZ , and the location of ΔTCSmax, x’ CSmax ). This investigation assesses the effect of G on x’csz and x' CSmax . A range of G values is introduced into both the analytical and the numerical models to obtain a correlation between the value of G and the dimensions of the CSZ. The result of a test case from the analytical model shows that x’ CSmax initially decreases rapidly and then decreases gradually approaching zero at very high values of G. Independent of the analytical model, the results from the numerical model replicate the trend obtained from the analytical model.

  6. Factors affecting ground-water exchange and catchment size for Florida lakes in mantled karst terrain

    USGS Publications Warehouse

    Lee, Terrie Mackin

    2002-01-01

    In the mantled karst terrain of Florida, the size of the catchment delivering ground-water inflow to lakes is often considerably smaller than the topographically defined drainage basin. The size is determined by a balance of factors that act individually to enhance or diminish the hydraulic connection between the lake and the adjacent surficial aquifer, as well as the hydraulic connection between the surficial aquifer and the deeper limestone aquifer. Factors affecting ground-water exchange and the size of the ground-water catchment for lakes in mantled karst terrain were examined by: (1) reviewing the physical and hydrogeological characteristics of 14 Florida lake basins with available ground-water inflow estimates, and (2) simulating ground-water flow in hypothetical lake basins. Variably-saturated flow modeling was used to simulate a range of physical and hydrogeologic factors observed at the 14 lake basins. These factors included: recharge rate to the surficial aquifer, thickness of the unsaturated zone, size of the topographically defined basin, depth of the lake, thickness of the surficial aquifer, hydraulic conductivity of the geologic units, the location and size of karst subsidence features beneath and onshore of the lake, and the head in the Upper Floridan aquifer. Catchment size and the magnitude of ground-water inflow increased with increases in recharge rate to the surficial aquifer, the size of the topographically defined basin, hydraulic conductivity in the surficial aquifer, the degree of confinement of the deeper Upper Floridan aquifer, and the head in the Upper Floridan aquifer. The catchment size and magnitude of ground-water inflow increased with decreases in the number and size of karst subsidence features in the basin, and the thickness of the unsaturated zone near the lake. Model results, although qualitative, provided insights into: (1) the types of lake basins in mantled karst terrain that have the potential to generate small and large

  7. Fatigue Resistance of the Grain Size Transition Zone in a Dual Microstructure Superalloy Disk

    NASA Technical Reports Server (NTRS)

    Gabb, T. P.; Kantzos, P. T.; Telesman, J.; Gayda, J.; Sudbrack, C. K.; Palsa, B. S.

    2010-01-01

    Mechanical property requirements vary with location in nickel-based superalloy disks. To maximize the associated mechanical properties, heat treatment methods have been developed for producing tailored microstructures. In this study, a specialized heat treatment method was applied to produce varying grain microstructures from the bore to the rim portions of a powder metallurgy processed nickel-based superalloy disk. The bore of the contoured disk consisted of fine grains to maximize strength and fatigue resistance at lower temperatures. The rim microstructure of the disk consisted of coarse grains for maximum resistance to creep and dwell crack growth at high temperatures up to 704 C. However, the fatigue resistance of the grain size transition zone was unclear, and needed to be evaluated. This zone was located as a band in the disk web between the bore and rim. Specimens were extracted parallel and transverse to the transition zone, and multiple fatigue tests were performed at 427 and 704 C. Mean fatigue lives were lower at 427 C than for 704 C. Specimen failures often initiated at relatively large grains, which failed on crystallographic facets. Grain size distributions were characterized in the specimens, and related to the grains initiating failures as well as location within the transition zone. Fatigue life decreased with increasing maximum grain size. Correspondingly, mean fatigue resistance of the transition zone was slightly higher than that of the rim, but lower than that of the bore. The scatter in limited tests of replicates was comparable for all transition zone locations examined.

  8. The structure and size of sensory bursts encode stimulus information but only size affects behavior.

    PubMed

    Marsat, Gary; Pollack, Gerald S

    2010-04-01

    Cricket ultrasound avoidance is a classic model system for neuroethology. Avoidance steering is triggered by high-firing-rate bursts of spikes in the auditory command neuron AN2. Although bursting is common among sensory neurons, and although the detailed structure of bursts may encode information about the stimulus, it is as yet unclear whether this information is decoded. We address this question in two ways: from an information coding point of view, by showing the relationship between stimulus and burst structure; and also from a functional point of view by showing the relationship between burst structure and behavior. We conclude that the burst structure carries detailed temporal information about the stimulus but that this has little impact on the behavioral response, which is affected mainly by burst size. PMID:20213110

  9. Fatigue Failure Modes of the Grain Size Transition Zone in a Dual Microstructure Disk

    NASA Technical Reports Server (NTRS)

    Gabb, Timothy P.; Kantzos, Pete T.; Palsa, Bonnie; Telesman, Jack; Gayda, John; Sudbrack, Chantal K.

    2012-01-01

    Mechanical property requirements vary with location in nickel-based superalloy disks. In order to maximize the associated mechanical properties, heat treatment methods have been developed for producing tailored grain microstructures. In this study, fatigue failure modes of a grain size transition zone in a dual microstructure disk were evaluated. A specialized heat treatment method was applied to produce varying grain microstructure in the bore to rim portions of a powder metallurgy processed nickel-based superalloy disk. The transition in grain size was concentrated in a zone of the disk web, between the bore and rim. Specimens were extracted parallel and transversely across this transition zone, and multiple fatigue tests were performed at 427 C and 704 C. Grain size distributions were characterized in the specimens, and related to operative failure initiation modes. Mean fatigue life decreased with increasing maximum grain size, going out through the transition zone. The scatter in limited tests of replicates was comparable for failures of uniform gage specimens in all transition zone locations examined.

  10. How Methodological Features Affect Effect Sizes in Education

    ERIC Educational Resources Information Center

    Cheung, Alan; Slavin, Robert

    2016-01-01

    As evidence-based reform becomes increasingly important in educational policy, it is becoming essential to understand how research design might contribute to reported effect sizes in experiments evaluating educational programs. The purpose of this study was to examine how methodological features such as types of publication, sample sizes, and…

  11. How Supernova Feedback Affects Observed Galaxy Sizes and Structures

    NASA Astrophysics Data System (ADS)

    Joung, M. K. Ryan; Cen, R.; Bryan, G. L.

    2009-01-01

    Feedback from massive stars is perhaps the least understood aspect of galaxy formation. Based on adaptive mesh refinement (AMR) cosmological simulations and stellar population synthesis models, we compute half-light radii of high redshift galaxies and use them to compare simulated and observed size-mass and size-luminosity relations in the rest-frame UV/optical. The sizes of the simulated galaxies depend on the assumed strength of supernova feedback; we investigate the origin of this relation. We discuss minimum requirements for correct numerical modeling of supernova feedback in starburst galaxies.

  12. 75 FR 51668 - Optional Mail Preparation Standards for Flat-Size Mailpieces in FSS Zones

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-08-23

    ... From the Federal Register Online via the Government Publishing Office POSTAL SERVICE 39 CFR Part 111 Optional Mail Preparation Standards for Flat-Size Mailpieces in FSS Zones AGENCY: Postal Service TM . ACTION: Final rule. SUMMARY: The Postal Service TM is revising the Mailing Standards of...

  13. Formation processes of floe size distribution in the marginal ice zone (Invited)

    NASA Astrophysics Data System (ADS)

    Toyota, T.; Kohout, A.; Fraser, A.

    2013-12-01

    Since the marginal ice zone (MIZ) is the outer sea ice zone, its behavior is key to the understanding of the variability of sea ice extent associated with climate change. Especially for the melting processes in MIZ, where relatively small ice floes are dominant, floe size distribution (FSD) is an important parameter because smaller ice floes are subject to stronger lateral melting due to their larger cumulative perimeters. As the MIZ is characterized by vigorous interaction between sea ice and waves, breakup of sea ice due to flexural forcing and collisions is considered to play an essential role in the determination of FSD there. However, the available data have been very limited so far. Analysis of the observations of ice floes with a heli-borne video camera, focusing on the floe size ranging from 2 m to 100 m, in the Sea of Okhotsk, the Weddell Sea and off East Antarctica, revealed that while FSD is basically scale-invariant, a regime shift occurs at a size of about a few tens of meters, irrespective of the study region. It was also shown 1) that the floe size at which regime shift occurs slightly increases from 20 to 40 m with ice thickness, consistent with the theory of the flexural failure of sea ice; and 2) that to explain the scale invariance in FSD for smaller floes, a fragility of sea ice which is relevant to the strength of sea ice relative to waves can be a useful physical parameter to be correlated with the fractal dimension. Thus these results confirm the importance of wave-ice interaction to the formation of FSD. Based on this, a possible mechanism of the melting process was hypothesized that in the melting season sea ice extent retreats keeping the FSD relative to the ice edge nearly constant. As a next step and to confirm and further investigate this result, we planned to conduct the concurrent measurements of FSD, wave activities, and ice thickness off East Antarctica during the Sea Ice Physics and Ecosystem Experiment 2 (SIPEX2) in September to

  14. Effects of Fusion Zone Size and Failure Mode on Peak Load and Energy Absorption of Advanced High Strength Steel Spot Welds

    SciTech Connect

    Sun, Xin; Stephens, Elizabeth V.; Khaleel, Mohammad A.

    2007-01-01

    This paper examines the effects of fusion zone size on failure modes, static strength and energy absorption of resistance spot welds (RSW) of advanced high strength steels (AHSS). DP800 and TRIP800 spot welds are considered. The main failure modes for spot welds are nugget pullout and interfacial fracture. Partial interfacial fracture is also observed. The critical fusion zone sizes to ensure nugget pull-out failure mode are developed for both DP800 and TRIP800 using limit load based analytical model and micro-hardness measurements of the weld cross sections. Static weld strength tests using cross tension samples were performed on the joint populations with controlled fusion zone sizes. The resulted peak load and energy absorption levels associated with each failure mode were studied for all the weld populations using statistical data analysis tools. The results in this study show that AHSS spot welds with fusion zone size of can not produce nugget pullout mode for both the DP800 and TRIP800 materials examined. The critical fusion zone size for nugget pullout shall be derived for individual materials based on different base metal properties as well as different heat affected zone (HAZ) and weld properties resulted from different welding parameters.

  15. Radish (Raphanus sativus) seed size affects germination response to coumarin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The inhibition of seed germination by an allelochemical is generally greater in small seeds than in large seeds. Studies reporting these results used a large number of plant species that varied in seed size, which might have introduced differences in germination characteristics or various parameter...

  16. Brood size modifications affect plumage bacterial assemblages of European starlings.

    PubMed

    Lucas, Françoise S; Moureau, Benoit; Jourdie, Violaine; Heeb, Philipp

    2005-02-01

    During reproduction, birds face trade-offs between time and energy devoted to parental effort and traits associated with self-maintenance. We manipulated brood sizes to investigate the effects of such trade-offs on feather bacterial densities and the structure of bacterial assemblages on feathers in adult European starlings, Sturnus vulgaris, and in vitro feather degradation. As predicted by a trade-off between parental effort and self-maintenance, we found that birds with enlarged broods had more free-living bacteria on their feathers than birds with reduced broods. Furthermore, we found a significant interaction between brood manipulation and original brood size on free-living bacterial densities suggesting that the trade-off is mediated by the adults' initial reproductive investment. In contrast, brood size manipulations had no significant effect on densities of attached bacteria. Using ribosomal intergenic spacer analysis (RISA), we demonstrated that brood manipulations significantly modified the structure (band pattern) of feather-degrading bacterial assemblages, but had no significant effect on their richness (number of bands) or the in vitro feather degradation. In vitro feather degradation varied in relation to the premanipulation brood size and positively with the richness of the feather degrading bacterial community. Besides brood manipulation effect, we found that ecological factors and individual traits, such as the age, the nest location or the capture date, shaped bacterial assemblages and feather degradation capacities. PMID:15660952

  17. How Methodological Features Affect Effect Sizes in Education

    ERIC Educational Resources Information Center

    Cheung, Alan C. K.; Slavin, Robert E.

    2016-01-01

    As evidence becomes increasingly important in educational policy, it is essential to understand how research design might contribute to reported effect sizes in experiments evaluating educational programs. A total of 645 studies from 12 recent reviews of evaluations of preschool, reading, mathematics, and science programs were studied. Effect…

  18. Kinetics of grain growth in the weld heat-affected zone of Alloy 718

    SciTech Connect

    Radhakrishnan, B.; Thompson, R.G.

    1993-12-01

    Grain-boundary liquation occurs in the weld heat-affected zone (HAZ) of the Ni-base superalloy 718 at locations where the peak temperatures are greater than about 1,200 C. The evolution of the grain structure at the HAZ locations depends upon the interaction between the grains and the grain-boundary liquid. The evolution of grain structure in the presence of grain-boundary liquid was simulated by subjecting samples to controlled thermal cycles using resistance heating. A measurement of grain size as a function of isothermal hold at two peak temperatures of 1,200 C and 1,227 C indicated that in alloy 718, the kinetics of grain growth depended upon the prior thermal history of the alloy. In the solution-treated alloy, the presence of grain-boundary liquid did not arrest grain growth at either peak temperature. In the homogenized and aged alloy, a grain refinement was observed at the peak temperature of 1,227 C, while an arrest of grain growth was observed at a peak temperature of 1,200 C. Liquid film migration (LFM) and subgrain coalescence, either acting alone or simultaneously, are shown to explain most of the observed microstructural phenomena and the kinetics of grain growth in the alloy.

  19. Kinetics of grain growth in the weld heat-affected zone of alloy 718

    NASA Astrophysics Data System (ADS)

    Radhakrishnan, B.; Thompson, R. G.

    1993-12-01

    Grain-boundary liquation occurs in the weld heat-affected zone (HAZ) of the Ni-base superalloy 718 at locations where the peak temperatures are greater than about 1200 ‡C. The evolution of the grain structure at these HAZ locations depends upon the interaction between the grains and the grain-boundary liquid. The evolution of grain structure in the presence of grain-boundary liquid was simulated by subjecting samples to controlled thermal cycles using resistance heating. A measurement of grain size as a function of isothermal hold at two peak temperatures of 1200 ‡C and 1227 ‡C indicated that in alloy 718, the kinetics of grain growth depended upon the prior thermal history of the alloy. In the solution-treated alloy, the presence of grain-boundary liquid did not arrest grain growth at either peak temperature. In the homogenized and aged alloy, a grain refinement was observed at the peak temperature of 1227 ‡C, while an arrest of grain growth was observed at a peak temperature of 1200‡C. Liquid film migration (LFM) and subgrain coalescence, either acting alone or simultaneously, are shown to explain most of the observed microstructural phenomena and the kinetics of grain growth in the alloy.

  20. Effect of welding parameters on the heat-affected zone of AISI409 ferritic stainless steel

    NASA Astrophysics Data System (ADS)

    Ranjbarnodeh, Eslam; Hanke, Stefanie; Weiss, Sabine; Fischer, Alfons

    2012-10-01

    One of the main problems during the welding of ferritic stainless steels is severe grain growth within the heat-affected zone (HAZ). In the present study, the microstructural characteristics of tungsten inert gas (TIG) welded AISI409 ferritic stainless steel were investigated by electron backscattered diffraction (EBSD), and the effects of welding parameters on the grain size, local misorientation, and low-angle grain boundaries were studied. A 3-D finite element model (FEM) was developed to predict the effects of welding parameters on the holding time of the HAZ above the critical temperature of grain growth. It is found that the base metal is not fully recrystallized. During the welding, complete recrystallization is followed by severe grain growth. A decrease in the number of low-angle grain boundaries is observed within the HAZ. FEM results show that the final state of residual strains is caused by competition between welding plastic strains and their release by recrystallization. Still, the decisive factor for grain growth is heat input.

  1. Quantifying the effect size of changing environmental controls on carbon release from permafrost-affected soils

    NASA Astrophysics Data System (ADS)

    Schaedel, C.; Bader, M. K. F.; Schuur, E. A. G.; Bracho, R. G.; Capek, P.; De Baets, S. L.; Diakova, K.; Ernakovich, J. G.; Hartley, I. P.; Iversen, C. M.; Kane, E. S.; Knoblauch, C.; Lupascu, M.; Natali, S.; Norby, R. J.; O'Donnell, J. A.; Roy Chowdhury, T.; Santruckova, H.; Shaver, G. R.; Sloan, V. L.; Treat, C. C.; Waldrop, M. P.

    2014-12-01

    High-latitude surface air temperatures are rising twice as fast as the global mean, causing permafrost to thaw and thereby exposing large quantities of previously frozen organic carbon (C) to microbial decomposition. Increasing temperatures in high latitude ecosystems not only increase C emissions from previously frozen C in permafrost but also indirectly affect the C cycle through changes in regional and local hydrology. Warmer temperatures increase thawing of ice-rich permafrost, causing land surface subsidence where soils become waterlogged, anoxic conditions prevail and C is released in form of anaerobic CO2 and CH4. Although substrate quality, physical protection, and nutrient availability affect C decomposition, increasing temperatures and changes in surface and sub-surface hydrology are likely the dominant factors affecting the rate and form of C release from permafrost; however, their effect size on C release is poorly quantified. We have compiled a database of 24 incubation studies with soils from active layer and permafrost from across the entire permafrost zone to quantify a) the effect size of increasing temperatures and b) the changes from aerobic to anaerobic environmental soil conditions on C release. Results from two different meta-analyses show that a 10°C increase in temperature increased C release by a factor of two in boreal forest, peatland and tundra ecosystems. Under aerobic incubation conditions, soils released on average three times more C than under anaerobic conditions with large variation among the different ecosystems. While peatlands showed similar amounts of C release under aerobic and anaerobic soil conditions, tundra and boreal forest ecosystems released up to 8 times more C under anoxic conditions. This pan-arctic synthesis shows that boreal forest and tundra soils will have a larger impact on climate change when newly thawed permafrost C decomposes in an aerobic environment compared to an anaerobic environment even when

  2. Mechanical Properties and Microstructural Evolution of Simulated Heat-Affected Zones in Wrought Eglin Steel

    NASA Astrophysics Data System (ADS)

    Leister, Brett M.; DuPont, John N.; Watanabe, Masashi; Abrahams, Rachel A.

    2015-12-01

    A comprehensive study was performed to correlate the mechanical properties and microstructural evolution in the heat-affected zone of Eglin steel. A Gleeble 3500 thermo-mechanical simulator was used to simulate weld thermal cycles with different peak temperatures at a heat input of 1500 J/mm. These samples underwent mechanical testing to determine strength and toughness in the as-welded and post-weld heat-treated conditions. The inter-critical heat-affected zone (HAZ) had the lowest strength following thermal simulation, while the fine-grain and coarse-grain heat-affected zone exhibited increased strength when compared to the inter-critical HAZ. The toughness of the heat-affected zone in the as-simulated condition is lower than that of the base metal in all regions of the HAZ. Post-weld heat treatments (PWHTs) increased the toughness of the HAZ, but at the expense of strength. In addition, certain combinations of PWHTs within specific HAZ regions exhibited low toughness caused by tempered martensite embrittlement or intergranular failure. Synchrotron X-ray diffraction data have shown that Eglin steel has retained austenite in the fine-grain HAZ in the as-simulated condition. In addition, alloy carbides (M23C6, M2C, M7C3) have been observed in the diffraction spectra for the fine-grain and coarse-grain HAZ following a PWHT of 973 K (700 °C)/4 hours.

  3. Microhabitat use affects brain size and structure in intertidal gobies.

    PubMed

    White, Gemma E; Brown, Culum

    2015-01-01

    The ecological cognition hypothesis poses that the brains and behaviours of individuals are largely shaped by the environments in which they live and the associated challenges they must overcome during their lives. Here we examine the effect of environmental complexity on relative brain size in 4 species of intertidal gobies from differing habitats. Two species were rock pool specialists that lived on spatially complex rocky shores, while the remainder lived on dynamic, but structurally simple, sandy shores. We found that rock pool-dwelling species had relatively larger brains and telencephalons in particular, while sand-dwelling species had a larger optic tectum and hypothalamus. In general, it appears that various fish species trade off neural investment in specific brain lobes depending on the environment in which they live. Our previous research suggests that rock pool species have greater spatial learning abilities, enabling them to navigate their spatially complex environment, which may account for their enlarged telencephalon, while sand-dwelling species likely have a reduced need for spatial learning, due to their spatially simple habitat, and a greater need for visual acuity. The dorsal medulla and cerebellum size was unaffected by the habitat in which the fish lived, but there were differences between species indicative of species-specific trade-offs in neural investment. PMID:25896449

  4. Body size affects the evolution of eyespots in caterpillars

    PubMed Central

    Skelhorn, John; Breinholt, Jesse W.; Kawahara, Akito Y.; Sherratt, Thomas N.

    2015-01-01

    Many caterpillars have conspicuous eye-like markings, called eyespots. Despite recent work demonstrating the efficacy of eyespots in deterring predator attack, a fundamental question remains: Given their protective benefits, why have eyespots not evolved in more caterpillars? Using a phylogenetically controlled analysis of hawkmoth caterpillars, we show that eyespots are associated with large body size. This relationship could arise because (i) large prey are innately conspicuous; (ii) large prey are more profitable, and thus face stronger selection to evolve such defenses; and/or (iii) eyespots are more effective on large-bodied prey. To evaluate these hypotheses, we exposed small and large caterpillar models with and without eyespots in a 2 × 2 factorial design to avian predators in the field. Overall, eyespots increased prey mortality, but the effect was particularly marked in small prey, and eyespots decreased mortality of large prey in some microhabitats. We then exposed artificial prey to naïve domestic chicks in a laboratory setting following a 2 × 3 design (small or large size × no, small, or large eyespots). Predators attacked small prey with eyespots more quickly, but were more wary of large caterpillars with large eyespots than those without eyespots or with small eyespots. Taken together, these data suggest that eyespots are effective deterrents only when both prey and eyespots are large, and that innate aversion toward eyespots is conditional. We conclude that the distribution of eyespots in nature likely results from selection against eyespots in small caterpillars and selection for eyespots in large caterpillars (at least in some microhabitats). PMID:25964333

  5. Body size affects the evolution of eyespots in caterpillars.

    PubMed

    Hossie, Thomas John; Skelhorn, John; Breinholt, Jesse W; Kawahara, Akito Y; Sherratt, Thomas N

    2015-05-26

    Many caterpillars have conspicuous eye-like markings, called eyespots. Despite recent work demonstrating the efficacy of eyespots in deterring predator attack, a fundamental question remains: Given their protective benefits, why have eyespots not evolved in more caterpillars? Using a phylogenetically controlled analysis of hawkmoth caterpillars, we show that eyespots are associated with large body size. This relationship could arise because (i) large prey are innately conspicuous; (ii) large prey are more profitable, and thus face stronger selection to evolve such defenses; and/or (iii) eyespots are more effective on large-bodied prey. To evaluate these hypotheses, we exposed small and large caterpillar models with and without eyespots in a 2 × 2 factorial design to avian predators in the field. Overall, eyespots increased prey mortality, but the effect was particularly marked in small prey, and eyespots decreased mortality of large prey in some microhabitats. We then exposed artificial prey to naïve domestic chicks in a laboratory setting following a 2 × 3 design (small or large size × no, small, or large eyespots). Predators attacked small prey with eyespots more quickly, but were more wary of large caterpillars with large eyespots than those without eyespots or with small eyespots. Taken together, these data suggest that eyespots are effective deterrents only when both prey and eyespots are large, and that innate aversion toward eyespots is conditional. We conclude that the distribution of eyespots in nature likely results from selection against eyespots in small caterpillars and selection for eyespots in large caterpillars (at least in some microhabitats). PMID:25964333

  6. Luminance controlled pupil size affects Landolt C task performance. Revision

    SciTech Connect

    Berman, S.M.; Fein, G.; Jewett, D.L.; Ashford, F.

    1993-02-01

    Subjects judged the orientation of a 2 min. gap Landolt C located at a distance of 2.4 m. The stimuli were presented in central vision on a CRT, at low to medium contrast. The effects of varying the spectrum and luminance of surround lighting were assessed on both pupil size (measured using infrared pupillometry during task performance) and task accuracy. The task display was protected from the surround lighting, so that its luminance and contrast could be varied independently of the changes in the surround lighting. Indirect surround illumination was provided by either two illuminants of very different scotopic spectral content but with the same photopic luminance (Experiments 1 and 3), or by using the same illuminant at two different luminance levels (Experiment 2). In Experiment 3, the effect of changing surround spectrum was compared to the effect of varying task background luminance between 12 cd/m{sup 2} and 73 cd/m{sup 2}. In all experiments, scotopically enhanced surround lighting produced pupil areas which were reduced by almost 50% in comparison with surround lighting with relatively less scotopic luminance. Concomitantly there was improvement in Landolt C task performance with the scotopically enhanced surround lighting at all contrast and luminance levels. In these experiments, smaller pupil sizes were associated with significantly better visual-task performance in spite of lower task retinal illuminance when compared to the condition with larger pupils. These results suggest that changes in surround spectrum can compensate for the effect on task performance of a reduction in task luminance and supports the hypothesis that lighting energy savings could accrue in the workplace by shifting lamp spectra to obtain greater scotopic efficacy.

  7. Luminance controlled pupil size affects Landolt C task performance

    SciTech Connect

    Berman, S.M. ); Fein, G. ); Jewett, D.L.; Ashford, F. )

    1993-02-01

    Subjects judged the orientation of a 2 min. gap Landolt C located at a distance of 2.4 m. The stimuli were presented in central vision on a CRT, at low to medium contrast. The effects of varying the spectrum and luminance of surround lighting were assessed on both pupil size (measured using infrared pupillometry during task performance) and task accuracy. The task display was protected from the surround lighting, so that its luminance and contrast could be varied independently of the changes in the surround lighting. Indirect surround illumination was provided by either two illuminants of very different scotopic spectral content but with the same photopic luminance (Experiments 1 and 3), or by using the same illuminant at two different luminance levels (Experiment 2). In Experiment 3, the effect of changing surround spectrum was compared to the effect of varying task background luminance between 12 cd/m[sup 2] and 73 cd/m[sup 2]. In all experiments, scotopically enhanced surround lighting produced pupil areas which were reduced by almost 50% in comparison with surround lighting with relatively less scotopic luminance. Concomitantly there was improvement in Landolt C task performance with the scotopically enhanced surround lighting at all contrast and luminance levels. In these experiments, smaller pupil sizes were associated with significantly better visual-task performance in spite of lower task retinal illuminance when compared to the condition with larger pupils. These results suggest that changes in surround spectrum can compensate for the effect on task performance of a reduction in task luminance and supports the hypothesis that lighting energy savings could accrue in the workplace by shifting lamp spectra to obtain greater scotopic efficacy.

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

    PubMed

    Ackland, Timothy; Elliott, Bruce; Richards, Joanne

    2003-07-01

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

  9. How does poaching affect the size of national parks?

    PubMed

    Dobson, Andy; Lynes, Laura

    2008-04-01

    A variety of human activities have detrimental impacts on populations of species the park is designed to protect. These impacts range from direct hunting for trophy or subsistence needs, through vehicular collisions, to the direct loss of habitat due to forestry and agricultural activity. These impacts reduce the effective size of the parks and require changes in management policy that deal both with the direct cause of the problem and the underlying social conflicts that the presence of parks can place on humans in the surrounding communities. Recent studies from the Serengeti illustrate that increases in anti-poaching patrols increase the risk of poacher detection and lead to dramatic declines in levels of poaching. The economic arguments that support investment in anti-poaching patrols, rather than increased sentences for poachers who are caught, can be generalized to examine the costs and benefits of other changes in natural resource management that arise when attempting to manage the impact of anthropogenic activities in and around national parks. PMID:18313793

  10. A topology reorganization scheme for reliable communication in underwater wireless sensor networks affected by shadow zones.

    PubMed

    Domingo, Mari Carmen

    2009-01-01

    Effective solutions should be devised to handle the effects of shadow zones in Underwater Wireless Sensor Networks (UWSNs). An adaptive topology reorganization scheme that maintains connectivity in multi-hop UWSNs affected by shadow zones has been developed in the context of two Spanish-funded research projects. A mathematical model has been proposed to find the optimal location for sensors with two objectives: the minimization of the transmission loss and the maintenance of network connectivity. The theoretical analysis and the numerical evaluations reveal that our scheme reduces the transmission loss under all propagation phenomena scenarios for all water depths in UWSNs and improves the signal-to-noise ratio. PMID:22291531

  11. A Topology Reorganization Scheme for Reliable Communication in Underwater Wireless Sensor Networks Affected by Shadow Zones

    PubMed Central

    Domingo, Mari Carmen

    2009-01-01

    Effective solutions should be devised to handle the effects of shadow zones in Underwater Wireless Sensor Networks (UWSNs). An adaptive topology reorganization scheme that maintains connectivity in multi-hop UWSNs affected by shadow zones has been developed in the context of two Spanish-funded research projects. A mathematical model has been proposed to find the optimal location for sensors with two objectives: the minimization of the transmission loss and the maintenance of network connectivity. The theoretical analysis and the numerical evaluations reveal that our scheme reduces the transmission loss under all propagation phenomena scenarios for all water depths in UWSNs and improves the signal-to-noise ratio. PMID:22291531

  12. The Floe Size Distribution in the Marginal Ice Zone of the Beaufort and Chukchi Seas

    NASA Astrophysics Data System (ADS)

    Schweiger, A. J. B.; Stern, H. L., III; Stark, M.; Zhang, J.; Steele, M.; Hwang, P. B.

    2014-12-01

    Several key processes in the Marginal Ice Zone (MIZ) of the Arctic Ocean are related to the size of the ice floes, whose diameters range from meters to tens of kilometers. The floe size distribution (FSD) influences the mechanical properties of the ice cover, air-sea momentum and heat transfer, lateral melting, and light penetration. However, no existing sea-ice/ocean models currently simulate the FSD in the MIZ. Model development depends on observations of the FSD for parameterization, calibration, and validation. To support the development and implementation of the FSD in the Marginal Ice Zone Modeling and Assimilation System (MIZMAS), we have analyzed the FSD in the Beaufort and Chukchi seas using multiple sources of satellite imagery: NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra and Aqua satellites (250 m pixel size), the USGS Landsat 8 satellite (80 m pixel size), the Canadian Space Agency's synthetic aperture radar (SAR) on RADARSAT (50 meter pixel size), and declassified National Technical Means imagery from the Global Fiducials Library (GFL) of the USGS (1 m pixel size). The procedure for identifying ice floes in the imagery begins with manually delineating cloud-free regions (if necessary). A threshold is then chosen to separate ice from water. Morphological operations and other semi-automated techniques are used to identify individual floes, whose properties are then easily calculated. We use the mean caliper diameter as the measure of floe size. The FSD is adequately described by a power-law in which the exponent characterizes the relative number of large and small floes. Changes in the exponent over time and space reflect changes in physical processes in the MIZ, such as sea-ice deformation, fracturing, and melting. We report results of FSD analysis for the spring and summer of 2013 and 2014, and show how the FSD will be incorporated into the MIZMAS model.

  13. The active zone protein CAST regulates synaptic vesicle recycling and quantal size in the mouse hippocampus.

    PubMed

    Kobayashi, Shizuka; Hida, Yamato; Ishizaki, Hiroyoshi; Inoue, Eiji; Tanaka-Okamoto, Miki; Yamasaki, Miwako; Miyazaki, Taisuke; Fukaya, Masahiro; Kitajima, Isao; Takai, Yoshimi; Watanabe, Masahiko; Ohtsuka, Toshihisa; Manabe, Toshiya

    2016-09-01

    Synaptic efficacy is determined by various factors, including the quantal size, which is dependent on the amount of neurotransmitters in synaptic vesicles at the presynaptic terminal. It is essential for stable synaptic transmission that the quantal size is kept within a constant range and that synaptic efficacy during and after repetitive synaptic activation is maintained by replenishing release sites with synaptic vesicles. However, the mechanisms for these fundamental properties have still been undetermined. We found that the active zone protein CAST (cytomatrix at the active zone structural protein) played pivotal roles in both presynaptic regulation of quantal size and recycling of endocytosed synaptic vesicles. In the CA1 region of hippocampal slices of the CAST knockout mice, miniature excitatory synaptic responses were increased in size, and synaptic depression after prolonged synaptic activation was larger, which was attributable to selective impairment of synaptic vesicle trafficking via the endosome in the presynaptic terminal likely mediated by Rab6. Therefore, CAST serves as a key molecule that regulates dynamics and neurotransmitter contents of synaptic vesicles in the excitatory presynaptic terminal in the central nervous system. PMID:27422015

  14. Aerial observations of floe size distribution in the marginal ice zone of summer Prydz Bay

    NASA Astrophysics Data System (ADS)

    Lu, P.; Li, Z. J.; Zhang, Z. H.; Dong, X. L.

    2008-02-01

    On the basis of aerial photographs of sea ice floes in the marginal ice zone (MIZ) of Prydz Bay acquired from December 2004 to February 2005 during the 21st Chinese National Antarctic Research Expedition, image processing techniques are employed to extract some geometric parameters of floes from two merged transects covering the whole MIZ. Variations of these parameters with the distance into the MIZ are then obtained. Different parameters of floe size, namely area, perimeter, and mean caliper diameter (MCD), follow three similar stages of increasing, flat and increasing again, with distance from the open ocean. Floe shape parameters (roundness and the ratio of perimeter to MCD), however, have less significant variations than that of floe size. Then, to modify the deviation of the cumulative floe size distribution from the ideal power law, an upper truncated power-law function and a Weibull function are used, and four calculated parameters of the above functions are found to be important descriptors of the evolution of floe size distribution in the MIZ. Among them, Lr of the upper truncated power-law function indicates the upper limit of floe size and roughly equals the maximum floe size in each square sample area. L0 in the Weibull distribution shows an increasing proportion of larger floes in squares farther from the open ocean and roughly equals the mean floe size. D in the upper truncated power-law function is closely associated with the degree of confinement during ice breakup. Its decrease with the distance into MIZ indicates the weakening of confinement conditions on floes owing to wave attenuation. The γ of the Weibull distribution characterizes the degree of homogeneity in a data set. It also decreases with distance into MIZ, implying that floe size distributes increase in range. Finally, a statistical test on floe size is performed to divide the whole MIZ into three distinct zones made up of floes of quite different characteristics. This zonal structure

  15. Analysis of laser ablation dynamics of CFRP in order to reduce heat affected zone

    NASA Astrophysics Data System (ADS)

    Sato, Yuji; Tsukamoto, Masahiro; Nariyama, Tatsuya; Nakai, Kazuki; Matsuoka, Fumihiro; Takahashi, Kenjiro; Masuno, Shinichiro; Ohkubo, Tomomasa; Nakano, Hitoshi

    2014-03-01

    A carbon fiber reinforced plastic [CFRP], which has high strength, light weight and weather resistance, is attractive material applied for automobile, aircraft and so on. The laser processing of CFRP is one of suitable way to machining tool. However, thermal affected zone was formed at the exposure part, since the heat conduction property of the matrix is different from that of carbon fiber. In this paper, we demonstrated that the CFRP plates were cut with UV nanosecond laser to reduce the heat affected zone. The ablation plume and ablation mass were investigated by laser microscope and ultra-high speed camera. Furthermore, the ablation model was constructed by energy balance, and it was confirmed that the ablation rate was 0.028 μg/ pulse in good agreement with the calculation value of 0.03 μg/ pulse.

  16. Mathematical modeling of microstructure evolution in the heat affected zone of electroslag cladding

    SciTech Connect

    Li, M.V.; Atteridge, D.G.; Meekisho, L.

    1996-12-31

    An algorithm is presented for computing microstructure evolution in weld heat affected zone of low alloy steels. It contains computational models for multicomponent Fe-C-M system equilibria, austenite grain growth kinetics, and austenite decomposition kinetics. A new kinetics model for austenite decomposition has been developed based on first principles of phase transformations expressed with Zener-Hillert type formulas. Coefficients in this model were calibrated with CCT diagrams of low alloy steels. This algorithm has the capability of computing TTT diagrams, CCT diagrams Jominy hardness curves, and phase transformations in the weld heat affected zone of low alloy steels. Excellent agreement was observed between the experimentally observed and the predicted microstructure and hardness.

  17. Estimating the size of a radio quiet zone for the radio astronomy service

    NASA Astrophysics Data System (ADS)

    Peng, Bo; Han, Wenjun

    2009-12-01

    The size of a radio quiet zone (RQZ) is largely determined by transmission losses of interfering signals, which can be divided into free space loss and diffraction loss. The free space loss is dominant. The diffraction loss presented in this paper is described as unified smooth spherical and knife edge diffractions, which is a function of minimum path clearance. We present a complete method to calculate the minimum path clearance. The cumulative distribution of the lapse rate of refractivity ( g n ), between the earth surface and 1 km above, is studied by using Chinese radio climate data. Because the size of an RQZ is proportional to g n , the cumulative distribution of g n can be used as an approximation for the size of the RQZ. When interference originates from mobile communication or television transmissions at a frequency of 408 MHz, and overline {g_n } is 40 N/km, where the refractivity N=left( {n-1} right) × 10^6, the size of the RQZ would be 180 km for a mobile source or 210 km for a television source, with a probability in the range of 15-100% in different months and for different stations. When speaking of the size of an RQZ, the radius in the case of a circular zone is implied. It results that a size of an RQZ is mainly influenced by transmission loss rather than effective radiated power. In the case where the distance between an interfering source and a radio astronomical observatory is about 100 km, at a frequency of 408 MHz, the allowable effective radiated power of the interfering source should be less than -30 dBW with a probability of about 85% for overline {g_n } equals 40 N/km, or -42 dBW with a probability less than 1 % for overline {g_n } equals 80 N/km.

  18. Morphology of weld heat-affected zone liquation cracking in Ta-modified cast alloy 718

    SciTech Connect

    West, S.L.; Baeslack, W.A. . Dept. of Welding Engineering); Kelly, T.J. . Aircraft Engine Business Group)

    1989-11-01

    The authors' discuss some problems involved in the use of alloy 718 which is a precipitation-hardenable, nickel-base superalloy developed in the early 1960s for medium temperature (540-705{sup 0}C) aerospace applications. The use of Nb as a substitute for Al and Ti leads to a susceptibility to liquation cracking in the weld heat-affected zone (HAZ). This problem is discussed in detail in the article.

  19. SCC Initiation in Alloy 600 Heat Affected Zones Exposed to High Temperature Water

    SciTech Connect

    E Richey; DS Morton; RA Etien; GA Young; RB Bucinell

    2006-11-03

    Studies have shown that grain boundary chromium carbides improve the stress corrosion cracking (SCC) resistance of nickel based alloys exposed to high temperature, high purity water. However, thermal cycles from welding can significantly alter the microstructure of the base material near the fusion line. In particular, the heat of welding can solutionize grain boundary carbides and produce locally high residual stresses and strains, reducing the SCC resistance of the Alloy 600 type material in the heat affected zone (HAZ). Testing has shown that the SCC growth rate in Alloy 600 heat affected zone samples can be {approx}30x faster than observed in the Alloy 600 base material under identical testing conditions due to fewer intergranular chromium rich carbides and increased plastic strain in the HAZ [1, 2]. Stress corrosion crack initiation tests were conducted on Alloy 600 HAZ samples at 360 C in hydrogenated, deaerated water to determine if these microstructural differences significantly affect the SCC initiation resistance of Alloy 600 heat affected zones compared to the Alloy 600 base material. Alloy 600 to EN82H to Alloy 600 heat-affected-zone (HAZ) specimens where fabricated from an Alloy 600 to Alloy 600 narrow groove weld with EN82H filler metal. The approximate middle third of the specimen gauge region was EN82H such that each specimen had two HAZ regions. Tests were conducted with in-situ monitored smooth tensile specimens under a constant load, and a direct current electric potential drop was used for in-situ detection of SCC. Test results suggest that the SCC initiation resistance of Alloy 600 and its weld metal follows the following order: EN82H > Alloy 600 HAZ > Alloy 600. The high SCC initiation resistance observed to date in Alloy 600 heat affected zones compared to wrought Alloy 600 is unexpected based on the microstructure of HAZ versus wrought material and based on prior SCC growth rate studies. The observed behavior for the HAZ specimens is likely

  20. Modeling the Ferrite-Austenite Transformation in the Heat-Affected Zone of Stainless Steel Welds

    SciTech Connect

    Vitek, J.M.; David, S.A.

    1997-12-01

    The diffusion-controlled ferrite-austenite transformation in stainless steel welds was modeled. An implicit finite-difference analysis that considers multi-component diffusion was used. The model was applied to the Fe-Cr-Ni system to investigate the ferrite- austenite transformation in the heat-affected zone of stainless steel weld metal. The transformation was followed as a function of time as the heat-affected zone was subjected to thermal cycles comparable to those experienced during gas-tungsten arc welding. The results showed that the transformation behavior and the final microstructural state are very sensitive to the maximum temperature that is experienced by the heat-affected zone. For high maximum exposure temperatures ({approximately} 1300{degree} C), the ferrite formation that occurs at the highest temperatures is not completely offset by the reverse ferrite dissolution at lower temperatures. As a result, for high temperature exposures there is a net increase in the amount of ferrite in the microstructure. It was also found that if compositional gradients are present in the initial ferrite and austenite phases, the extent of the transformation is impacted.

  1. ELECTROSTATIC BARRIER AGAINST DUST GROWTH IN PROTOPLANETARY DISKS. II. MEASURING THE SIZE OF THE 'FROZEN' ZONE

    SciTech Connect

    Okuzumi, Satoshi; Sakagami, Masa-aki; Tanaka, Hidekazu; Takeuchi, Taku

    2011-04-20

    Coagulation of submicron-sized dust grains into porous aggregates is the initial step of dust evolution in protoplanetary disks. Recently, it has been pointed out that negative charging of dust in the weakly ionized disks could significantly slow down the coagulation process. In this paper, we apply the growth criteria obtained in Paper I to finding out a location ('frozen' zone) where the charging stalls dust growth at the fractal growth stage. For low-turbulence disks, we find that the frozen zone can cover a major part of the disks at a few to 100 AU from the central star. The maximum mass of the aggregates is approximately 10{sup -7}g at 1 AU and as small as a few monomer masses at 100 AU. Strong turbulence can significantly reduce the size of the frozen zone, but such turbulence will cause the fragmentation of macroscopic aggregates at later stages. We examine a possibility that complete freezeout of dust evolution in low-turbulence disks could be prevented by global transport of dust in the disks. Our simple estimation shows that global dust transport can lead to the supply of macroscopic aggregates and the removal of frozen aggregates on a timescale of 10{sup 6} yr. This overturns the usual understanding that tiny dust particles get depleted on much shorter timescales unless collisional fragmentation is effective. The frozen zone together with global dust transport might explain 'slow' ({approx}10{sup 6} yr) dust evolution suggested by infrared observation of T Tauri stars and by radioactive dating of chondrites.

  2. Nano-sized and micro-sized polystyrene particles affect phagocyte function

    PubMed Central

    Prietl, B.; Meindl, C.; Roblegg, E.; Pieber, T. R.; Lanzer, G.; Fröhlich, E.

    2015-01-01

    Adverse effect of nanoparticles may include impairment of phagocyte function. To identify the effect of nanoparticle size on uptake, cytotoxicity, chemotaxis, cytokine secretion, phagocytosis, oxidative burst, nitric oxide production and myeloperoxidase release, leukocytes isolated from human peripheral blood, monocytes and macrophages were studied. Carboxyl polystyrene (CPS) particles in sizes between 20 and 1,000 nm served as model particles. Twenty nanometers CPS particles were taken up passively, while larger CPS particles entered cells actively and passively. Twenty nanometers CPS were cytotoxic to all phagocytes, ≥500 nm CPS particles only to macrophages. Twenty nanometers CPS particles stimulated IL-8 secretion in human monocytes and induced oxidative burst in monocytes. Five hundred nanometers and 1,000 nm CPS particles stimulated IL-6 and IL-8 secretion in monocytes and macrophages, chemotaxis towards a chemotactic stimulus of monocytes and phagocytosis of bacteria by macrophages and provoked an oxidative burst of granulocytes. At very high concentrations, CPS particles of 20 and 500 nm stimulated myeloperoxidase release of granulocytes and nitric oxide generation in macrophages. Cytotoxic effect could contribute to some of the observed effects. In the absence of cytotoxicity, 500 and 1,000 nm CPS particles appear to influence phagocyte function to a greater extent than particles in other sizes. PMID:24292270

  3. Characterizing multiple timescales of stream and storage zone interaction that affect solute fate and transport in streams

    USGS Publications Warehouse

    Choi, J.; Harvey, J.W.; Conklin, M.H.

    2000-01-01

    The fate of contaminants in streams and rivers is affected by exchange and biogeochemical transformation in slowly moving or stagnant flow zones that interact with rapid flow in the main channel. In a typical stream, there are multiple types of slowly moving flow zones in which exchange and transformation occur, such as stagnant or recirculating surface water as well as subsurface hyporheic zones. However, most investigators use transport models with just a single storage zone in their modeling studies, which assumes that the effects of multiple storage zones can be lumped together. Our study addressed the following question: Can a single-storage zone model reliably characterize the effects of physical retention and biogeochemical reactions in multiple storage zones? We extended an existing stream transport model with a single storage zone to include a second storage zone. With the extended model we generated 500 data sets representing transport of nonreactive and reactive solutes in stream systems that have two different types of storage zones with variable hydrologic conditions. The one storage zone model was tested by optimizing the lumped storage parameters to achieve a best fit for each of the generated data sets. Multiple storage processes were categorized as possessing I, additive; II, competitive; or III, dominant storage zone characteristics. The classification was based on the goodness of fit of generated data sets, the degree of similarity in mean retention time of the two storage zones, and the relative distributions of exchange flux and storage capacity between the two storage zones. For most cases (> 90%) the one storage zone model described either the effect of the sum of multiple storage processes (category I) or the dominant storage process (category III). Failure of the one storage zone model occurred mainly for category II, that is, when one of the storage zones had a much longer mean retention time (t(s) ratio > 5.0) and when the dominance of

  4. Grain Boundary Character Distribution in the Heat-Affected Zone of Friction Stir-Processed AL 7075 T7

    NASA Astrophysics Data System (ADS)

    Basinger, J. A.; Adams, B. L.

    2007-06-01

    Current transmission electron microscopy (TEM) research (Cai et al., 2006) in the heat-affected zone (HAZ) of friction stir-welded Al 7075 T7 finds a correlation between precipitate-free zone (PFZ) width and grain boundary (GB) geometry. Based on these correlations, this article makes a comparison of grain boundary character distributions (GBCDs) in the HAZ and the parent metal via multisection plane five-parameter stereology. The stereology is conducted in a convenient macroscopic coordinate frame, associated with the HAZ. Further comparisons between the two microstructures are conducted relative to two-dimensional (2-D) GB network connectivity, recovered from electron backscatter diffraction (EBSD) data in each section plane. It is shown that the relative fraction of GBs of misorientation character associated with smaller PFZ size is larger in the HAZ as compared to the parent material. A commensurate decrease in the connectivity (radius of gyration) of GBs of character conducive to larger PFZ size is also found in the HAZ, relative to the parent material. Distribution of inclinations changes as a function of GB geometry. Surface area per unit volume of low-angle random (LAR) misorientations increases in the HAZ, while high-angle random (HAR) and coincident site lattice (CSL) boundaries decrease. In the case of LAR and some CSL boundaries, a reorientation occurs in which macroscopic normals of these interfaces rotate.

  5. Enhancement of Heat-Affected Zone Toughness of a Low Carbon Steel by TiN Particle

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Li, Xiaobao; Ma, Han

    2015-11-01

    Enhancement of heat-affected zone toughness of a weight percentage of 0.014 pct Ti-bearing low carbon steel by TiN particle was investigated. An increase in nitrogen weight percentage from 0.0031 to 0.0083 pct results in increasing of number density of TiN precipitates from 4 × 103 to 3 × 105/mm2, and reduces prior austenite grain size from 850 to 350 μm with a soaking of 1673 K (1400 °C) for 2000 seconds. Effective refinement of austenite grain prohibits formation of ferrite side plate and/or upper bainite, and densely distributed TiN particles promote intra-granular ferrite formation, which is accompanied by an increase of 40 K to 60 K (40 °C to 60 °C) in austenite decomposition temperature during continuous cooling process. The changes in transformed products improved impact toughness of heat-affected zone efficiently, ex., increase absorbed energy of less than 42 J to more than 320 J with a simulated t 8/5 of 550 seconds.

  6. Enhancement of Heat-Affected Zone Toughness of a Low Carbon Steel by TiN Particle

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Li, Xiaobao; Ma, Han

    2016-08-01

    Enhancement of heat-affected zone toughness of a weight percentage of 0.014 pct Ti-bearing low carbon steel by TiN particle was investigated. An increase in nitrogen weight percentage from 0.0031 to 0.0083 pct results in increasing of number density of TiN precipitates from 4 × 103 to 3 × 105/mm2, and reduces prior austenite grain size from 850 to 350 μm with a soaking of 1673 K (1400 °C) for 2000 seconds. Effective refinement of austenite grain prohibits formation of ferrite side plate and/or upper bainite, and densely distributed TiN particles promote intra-granular ferrite formation, which is accompanied by an increase of 40 K to 60 K (40 °C to 60 °C) in austenite decomposition temperature during continuous cooling process. The changes in transformed products improved impact toughness of heat-affected zone efficiently, ex., increase absorbed energy of less than 42 J to more than 320 J with a simulated t 8/5 of 550 seconds.

  7. Performance processes within affect-related performance zones: a multi-modal investigation of golf performance.

    PubMed

    van der Lei, Harry; Tenenbaum, Gershon

    2012-12-01

    Individual affect-related performance zones (IAPZs) method utilizing Kamata et al. (J Sport Exerc Psychol 24:189-208, 2002) probabilistic model of determining the individual zone of optimal functioning was utilized as idiosyncratic affective patterns during golf performance. To do so, three male golfers of a varsity golf team were observed during three rounds of golf competition. The investigation implemented a multi-modal assessment approach in which the probabilistic relationship between affective states and both, performance process and performance outcome, measures were determined. More specifically, introspective (i.e., verbal reports) and objective (heart rate and respiration rate) measures of arousal were incorporated to examine the relationships between arousal states and both, process components (i.e., routine consistency, timing), and outcome scores related to golf performance. Results revealed distinguishable and idiosyncratic IAPZs associated with physiological and introspective measures for each golfer. The associations between the IAPZs and decision-making or swing/stroke execution were strong and unique for each golfer. Results are elaborated using cognitive and affect-related concepts, and applications for practitioners are provided. PMID:22562463

  8. An Earth-sized planet in the habitable zone of a cool star.

    PubMed

    Quintana, Elisa V; Barclay, Thomas; Raymond, Sean N; Rowe, Jason F; Bolmont, Emeline; Caldwell, Douglas A; Howell, Steve B; Kane, Stephen R; Huber, Daniel; Crepp, Justin R; Lissauer, Jack J; Ciardi, David R; Coughlin, Jeffrey L; Everett, Mark E; Henze, Christopher E; Horch, Elliott; Isaacson, Howard; Ford, Eric B; Adams, Fred C; Still, Martin; Hunter, Roger C; Quarles, Billy; Selsis, Franck

    2014-04-18

    The quest for Earth-like planets is a major focus of current exoplanet research. Although planets that are Earth-sized and smaller have been detected, these planets reside in orbits that are too close to their host star to allow liquid water on their surfaces. We present the detection of Kepler-186f, a 1.11 ± 0.14 Earth-radius planet that is the outermost of five planets, all roughly Earth-sized, that transit a 0.47 ± 0.05 solar-radius star. The intensity and spectrum of the star's radiation place Kepler-186f in the stellar habitable zone, implying that if Kepler-186f has an Earth-like atmosphere and water at its surface, then some of this water is likely to be in liquid form. PMID:24744370

  9. Middle East measurements of concentration and size distribution of aerosol particles for coastal zones

    NASA Astrophysics Data System (ADS)

    Bendersky, Sergey; Kopeika, Norman S.; Blaunstein, Natan S.

    2005-10-01

    Recently, an extension of the Navy Aerosol Model (NAM) was proposed based on analysis of an extensive series of measurements at the Irish Atlantic Coast and at the French Mediterranean Coast. We confirm the relevance of that work for the distant eastern Meditteranean and extend several coefficients of that coastal model, proposed by Piazzola et al. for the Meditteranean Coast (a form of the Navy Aerosol Model), to midland Middle East coastal environments. This analysis is based on data collected at three different Middle East coastal areas: the Negev Desert (Eilat) Red Sea Coast, the Sea of Galilee (Tiberias) Coast, and the Mediterranean (Haifa) Coast. Aerosol size distributions are compared with those obtained through measurements carried out over the Atlantic, Pacific, and Indian Ocean Coasts, and Mediterranean, and Baltic Seas Coasts. An analysis of these different results allows better understanding of the similarities and differences between different coastal lake, sea, and open ocean zones. It is shown that in the coastal regions in Israel, compared to open ocean and other sea zones, larger differences in aerosol particle concentration are observed. The aerosol particle concentrations and their dependences on wind speed for these coastal zones are analyzed and discussed. We propose to classify the aerosol distribution models to either: 1. a coastal model with marine aerosol domination; 2. a coastal model with continental aerosol domination (referred to as midland coast in this work); or 3. a coastal model with balanced marine and continental conditions.

  10. Analysis of heat affected zone obtained by CO2 laser cutting of low carbon steel (S235)

    NASA Astrophysics Data System (ADS)

    Zaied, M.; Miraoui, I.; Boujelbene, M.; Bayraktar, E.

    2013-12-01

    Laser cutting is associated with thermal effects at the cutting surface resulting in alteration of microstructure and mechanical properties. An abrupt change on the cutting surface is caused by a structural modified zone called heat affected zone (HAZ) due to weld heat treatment introduced by a high thermal gradient in the substrate material. Heat affected zone is often associated with undesirable effects such as surface cracking, fatigue resistance, etc. Therefore, it is important to minimize the thickness of this zone (HAZ). The objective of this work is to study the effect of high-power CO2 laser cutting on the heat affected zone. The laser cutting of low carbon steel (S235) is investigated with the aim of evaluating the effect of the input laser cutting parameters: laser power and cutting speed, on heat affected zone. An overall optimization was applied to find out the optimal cutting parameters that would minimize the thickness of heat affected zone. It was found that laser cutting parameters have an effect on the heat affected zone. The HAZ can be minimized by increasing the laser cutting speed and decreasing the laser power.

  11. Heat-affected zone liquation crack on resistance spot welded TWIP steels

    SciTech Connect

    Saha, Dulal Chandra; Chang, InSung; Park, Yeong-Do

    2014-07-01

    In this study, the heat affected zone (HAZ) liquation crack and segregation behavior of the resistance spot welded twinning induced plasticity (TWIP) steel have been reported. Cracks appeared in the post-welded joints that originated at the partially melted zone (PMZ) and propagated from the PMZ through the heat affected zone (HAZ) to the base metal (BM). The crack length and crack opening widths were observed increasing with heat input; and the welding current was identified to be the most influencing parameter for crack formation. Cracks appeared at the PMZ when nugget diameter reached at 4.50 mm or above; and the liquation cracks were found to occur along two sides of the notch tip in the sheet direction rather than in the electrode direction. Cracks were backfilled with the liquid films which has lamellar structure and supposed to be the eutectic constituent. Co-segregation of alloy elements such as, C and Mn were detected on the liquid films by electron-probe microanalysis (EPMA) line scanning and element map which suggests that the liquid film was enrich of Mn and C. The eutectic constituent was identified by analyzing the calculated phase diagram along with thermal temperature history of finite element simulation. Preliminary experimental results showed that cracks have less/no significant effect on the static cross-tensile strength (CTS) and the tensile-shear strength (TSS). In addition, possible ways to avoid cracking were discussed. - Highlights: • The HAZ liquation crack during resistance spot welding of TWIP steel was examined. • Cracks were completely backfilled and healed with divorced eutectic secondary phase. • Co-segregation of C and Mn was detected in the cracked zone. • Heat input was the most influencing factor to initiate liquation crack. • Cracks have less/no significant effect on static tensile properties.

  12. Factors Affecting Crater Size-Frequency Distribution Measurements: Insights Supported by the LRO Mission

    NASA Astrophysics Data System (ADS)

    van der Bogert, C. H.; Hiesinger, H.; Zanetti, M.; Plescia, J. B.; Ostrach, L. R.; Mahanti, P.; Meyer, H. M.; McEwen, A. S.; Pasckert, J. H.; Michael, G.; Kneissl, T.; Robinson, M. S.

    2016-05-01

    CSFD measurements are affected by illumination angle, count area size/slope, secondary cratering, target property effects, and differential degradation. Investigations using LRO data have made progress characterizing and quantifying these factors.

  13. Metagenomic analysis of size-fractionated picoplankton in a marine oxygen minimum zone.

    PubMed

    Ganesh, Sangita; Parris, Darren J; DeLong, Edward F; Stewart, Frank J

    2014-01-01

    Marine oxygen minimum zones (OMZs) support diverse microbial communities with roles in major elemental cycles. It is unclear how the taxonomic composition and metabolism of OMZ microorganisms vary between particle-associated and free-living size fractions. We used amplicon (16S rRNA gene) and shotgun metagenome sequencing to compare microbial communities from large (>1.6 μm) and small (0.2-1.6 μm) filter size fractions along a depth gradient in the OMZ off Chile. Despite steep vertical redox gradients, size fraction was a significantly stronger predictor of community composition compared to depth. Phylogenetic diversity showed contrasting patterns, decreasing towards the anoxic OMZ core in the small size fraction, but exhibiting maximal values at these depths within the larger size fraction. Fraction-specific distributions were evident for key OMZ taxa, including anammox planctomycetes, whose coding sequences were enriched up to threefold in the 0.2-1.6 μm community. Functional gene composition also differed between fractions, with the >1.6 μm community significantly enriched in genes mediating social interactions, including motility, adhesion, cell-to-cell transfer, antibiotic resistance and mobile element activity. Prokaryotic transposase genes were three to six fold more abundant in this fraction, comprising up to 2% of protein-coding sequences, suggesting that particle surfaces may act as hotbeds for transposition-based genome changes in marine microbes. Genes for nitric and nitrous oxide reduction were also more abundant (three to seven fold) in the larger size fraction, suggesting microniche partitioning of key denitrification steps. These results highlight an important role for surface attachment in shaping community metabolic potential and genome content in OMZ microorganisms. PMID:24030599

  14. Metagenomic analysis of size-fractionated picoplankton in a marine oxygen minimum zone

    PubMed Central

    Ganesh, Sangita; Parris, Darren J; DeLong, Edward F; Stewart, Frank J

    2014-01-01

    Marine oxygen minimum zones (OMZs) support diverse microbial communities with roles in major elemental cycles. It is unclear how the taxonomic composition and metabolism of OMZ microorganisms vary between particle-associated and free-living size fractions. We used amplicon (16S rRNA gene) and shotgun metagenome sequencing to compare microbial communities from large (>1.6 μm) and small (0.2–1.6 μm) filter size fractions along a depth gradient in the OMZ off Chile. Despite steep vertical redox gradients, size fraction was a significantly stronger predictor of community composition compared to depth. Phylogenetic diversity showed contrasting patterns, decreasing towards the anoxic OMZ core in the small size fraction, but exhibiting maximal values at these depths within the larger size fraction. Fraction-specific distributions were evident for key OMZ taxa, including anammox planctomycetes, whose coding sequences were enriched up to threefold in the 0.2–1.6 μm community. Functional gene composition also differed between fractions, with the >1.6 μm community significantly enriched in genes mediating social interactions, including motility, adhesion, cell-to-cell transfer, antibiotic resistance and mobile element activity. Prokaryotic transposase genes were three to six fold more abundant in this fraction, comprising up to 2% of protein-coding sequences, suggesting that particle surfaces may act as hotbeds for transposition-based genome changes in marine microbes. Genes for nitric and nitrous oxide reduction were also more abundant (three to seven fold) in the larger size fraction, suggesting microniche partitioning of key denitrification steps. These results highlight an important role for surface attachment in shaping community metabolic potential and genome content in OMZ microorganisms. PMID:24030599

  15. Analysis of heat-affected zone cracking in Ni/sub 3/Al alloys

    SciTech Connect

    Santella, M.L.; Maguire, M.C.; David, S.A.

    1986-01-01

    A key issue in the development of Ni/sub 3/Al for engineering applications is their weldability. Detailed welding studies have been done which show that iron-containing nickel aluminides are prone to heat-affected zone (HAZ) cracking. Hot ductility testing of these alloys has suggested that grain boundary cohesive strength controls high temperature ductility and the resistance to HAZ cracking. This analysis cannot, however, be used to explain the behavior of other aluminide alloys. The intention of this work is to more fully characterize the relationship between mechanical behavior and HAZ cracking susceptibility for Ni/sub 3/Al alloys.

  16. Microstructure characterization of heat affected zone after welding in Mod.9Cr–1Mo steel

    SciTech Connect

    Sawada, K.; Hara, T.; Tabuchi, M.; Kimura, K.; Kubushiro, K.

    2015-03-15

    The microstructure of the heat affected zone after welding was investigated in Mod.9Cr–1Mo steel, using TEM and STEM-EDX. The microstructure of thin foil was observed at the fusion line, and at the positions of 0.5 mm, 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm and 3.5 mm to the base metal side of the fusion line. Martensite structure with very fine lath and high dislocation density was confirmed at all positions. Twins with a twin plane of (112) were locally observed at all positions. Elemental mapping was obtained for all positions by means of STEM-EDX. Inclusions of mainly Si were formed at the fusion line but not at the other positions. No precipitates could be detected at the fusion line or at the position of 0.5 mm. On the other hand, MX particles were observed at the positions of 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, 3.0 mm and 3.5 mm even after welding. M{sub 23}C{sub 6} particles were also confirmed at the positions of 2.0 mm, 2.5 mm, 3.0 mm and 3.5 mm. Very fine equiaxed grains were locally observed at the positions of 2.0 mm and 2.5 mm. The Cr content of the equiaxed grains was about 12 mass%, although the martensite area included about 8 mass% Cr. - Graphical abstract: Display Omitted - Highlights: • Nonequilibrium microstructure of heat affected zone was observed after welding in Mod.9Cr–1Mo steel. • Inclusions containing Si were detected at the fusion line. • Undissolved M{sub 23}C{sub 6} and MX particles were confirmed in heat affected zone. • Twins with a twin plane of (112) were locally observed at all positions. • Very fine ferrite grains with high Cr content were observed in fine grained heat affected zone.

  17. Femtosecond laser heat affected zones profiled in Co/Si multilayer thin films

    SciTech Connect

    Picard, Yoosuf N.; Yalisove, Steven M.

    2008-01-07

    In this letter, we describe an approach for assessing collateral thermal damage resulting from high intensity, femtosecond laser irradiation. Polycrystalline Co thin films deposited on Si (100) substrates and buried under an amorphous Si film were prepared for plan-view transmission electron microscopy (TEM) prior to laser irradiation by femtosecond laser pulses. A heat affected zone (HAZ) resulting from single pulse irradiation at a fluence of 0.9 J/cm{sup 2} was determined by TEM imaging and point-wise selected area diffraction. The spatially Gaussian laser pulse generated a HAZ extending up to 3 {mu}m radially from the femtosecond laser irradiated region.

  18. In-situ Phase transformation study in fine grained heat affected zone of Grade 91 steels

    SciTech Connect

    Babu, Sudarsanam Suresh; Yamamoto, Yukinori; Santella, Michael L; Yu, Xinghua; Komizo, Prof. Y; Terasaki, Prof. H

    2014-01-01

    Creep strength-enhanced ferritic (CSEF) steels such as the 9 Cr steel [ASTM A387 Grade 91] are widely used as tubing and piping in the new generation of fossil fired power plants. Microstructures in the fine-grained heat affected zone (FGHAZ) may significantly reduce creep strength leading Type IV failures. Current research suggest that reducing pre-weld tempering temperature from 760 C (HTT) to 650 C (LTT) has the potential to double the creep life of these welds. To understand this improvement, time-resolved X-ray diffraction (TRXRD) measurement with synchrotron radiation was used to characterize the microstructure evolution during fine grained heat-affected zone (HAZ) thermal cycling of grade 91 steel. The measurements showed both M23C6 (M=Fe, Cr) and MX (M=Nb, V; X=C,N) are present in the sample after the HTT condition. Near equilibrium fraction of M23C6 was measured in high temperature tempering condition (HTT, 760 C). However, the amount of M23C6 in LTT condition was very low since the diffraction peaks are close to the background. During simulated FGHAZ thermal cycling, the M23C6 partially dissolved in HTT sample. Interestingly, MX did not dissolve in both LTT and HTT samples. Hypothesis for correlation of M23C6 carbide distribution and pre-mature creep failure in FGHAZ will be made.

  19. Microstructural Characterization of Thermomechanical and Heat-Affected Zones of an Inertia Friction Welded Astroloy

    NASA Astrophysics Data System (ADS)

    Oluwasegun, K. M.; Olawale, J. O.; Ige, O. O.; Shittu, M. D.; Adeleke, A. A.; Malomo, B. O.

    2014-08-01

    The behaviour of γ' phase to thermal and mechanical effects during rapid heating of Astroloy, a powder metallurgy nickel-based superalloy has been investigated. The thermo-mechanical-affected zone (TMAZ) and heat-affected zone (HAZ) microstructures of an inertia friction welded (IFW) Astroloy were simulated using a Gleeble thermo-mechanical simulation system. Detailed microstructural examination of the simulated TMAZ and HAZ and those present in actual IFW specimens showed that γ' particles persisted during rapid heating up to a temperature where the formation of liquid is thermodynamically favored and subsequently re-solidified eutectically. The result obtained showed that forging during the thermo-mechanical simulation significantly enhanced resistance to weld liquation cracking of the alloy. This is attributable to strain-induced rapid isothermal dissolution of the constitutional liquation products within 150 μm from the center of the forged sample. This was not observed in purely thermally simulated samples. The microstructure within the TMAZ of the as-welded alloy is similar to the microstructure in the forged Gleeble specimens.

  20. Finding Earth-size planets in the habitable zone: the Kepler Mission

    NASA Astrophysics Data System (ADS)

    Borucki, William; Koch, David; Basri, Gibor; Batalha, Natalie; Brown, Timothy; Caldwell, Douglas; Christensen-Dalsgaard, Jørgen; Cochran, William; Dunham, Edward; Gautier, Thomas N.; Geary, John; Gilliland, Ronald; Jenkins, Jon; Kondo, Yoji; Latham, David; Lissauer, Jack J.; Monet, David

    2008-05-01

    The Kepler Mission is a space-based mission whose primary goal is to detect Earth-size and smaller planets in the habitable zone of solar-like stars. The mission will monitor more than 100,000 stars for transits with a differential photometric precision of 20 ppm at V=12 for a 6.5 hour transit. It will also provide asteroseismic results on several thousand dwarf stars. It is specifically designed to continuously observe a single field of view of greater than 100 square degrees for 3.5 or more years. This overview describes the mission design, its goals and capabilities, the measured performance for those photometer components that have now been tested, the Kepler Input Catalog, an overview of the analysis pipeline, the plans for the Follow-up Observing Program to validate the detections and characterize the parent stars, and finally, the plans for the Guest Observer and Astrophysical Data Program.

  1. Selections from 2015: Earth-Sized Planet Found in Star's Habitable Zone

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2015-03-01

    Editors Note:In these last two weeks of 2015, well be looking at a few selections from among the most-downloaded paperspublished in AAS journals this year. The usual posting schedule will resume after the AAS winter meeting.Discovery and Validation of Kepler-452b: a 1.6 R Super Earth Exoplanet in the Habitable Zone of a G2 StarPublished July2015Main takeaway:A phase-folded light curve showing the transit of Kepler-452b. Its transit lasts 10.5 hours, and its period is 385 days. [Jenkins et al. 2015]A team led by Jon Jenkins (NASA Ames Research Center) announced the discovery and confirmation of Kepler-452b, an exoplanet only 60% larger than Earth and located in the habitable zone of its G2 star. This planet orbits its star at a distance of just over 1 AU, taking 385 days to complete an orbit. Kepler-452b also stands a good chance of being rocky, according to estimates.Why its interesting:Kepler-452b is the first near-Earth-sized planet to be found in the habitable zone of a Sun-like star making this the closest analog to the Earth-Sun system found in the Kepler dataset so far.About the history of the system (and the future of ours?):The authors estimate that the system is ~6 billion years old, and that Kepler-452b has been in the habitable zone of its star throughout its lifetime a substantially longer time than Earth has been around and habitable! Kepler-452bs host star, in addition to being 1.5 billion years older than the Sun, is roughly 10% larger. This system might therefore provide a glimpse of what Earths environment may be like in the future, as the Sun slowly expands on its way to becoming a red giant.CitationJon M. Jenkins et al 2015 AJ 150 56. doi:10.1088/0004-6256/150/2/56

  2. Kepler Mission: A Mission to Find Earth-size Planets in the Habitable Zone

    NASA Technical Reports Server (NTRS)

    Borucki, W. J.

    2003-01-01

    The Kepler Mission is a Discovery-class mission designed to continuously monitor the brightness of 100,000 solar-like stars to detect the transits of Earth-size and larger planets. It is a wide field of view photometer Schmidt-type telescope with an array of 42 CCDs. It has a 0.95 m aperture and 1.4 m primary and is designed to attain a photometric precision of 2 parts in 10(exp 5) for 12th magnitude solar-like stars for a 6 hr transit duration. It will continuously observe 100,000 main-sequence stars from 9th to 14th magnitude in the Cygnus constellation for a period of four years with a cadence of 4/hour. An additional 250 stars can be monitored at a cadence of l/minute to do astro-seismology of stars brighter than 11.5 mv. The photometer is scheduled to be launched into heliocentric orbit in 2007. When combined with ground-based spectrometric observations of these stars, the positions of the planets relative to the habitable zone can be found. The spectra of the stars are also used to determine the relationships between the characteristics of terrestrial planets and the characteristics of the stars they orbit. In particular, the association of planet size and occurrence frequency with stellar mass and metallicity will be investigated. Based on the results of the current Doppler-velocity discoveries, over a thousand giant planets will also be found. Information on the albedos and densities of those giants showing transits will be obtained. At the end of the four year mission, hundreds of Earth-size planets should be discovered in and near the HZ of their stars if such planets are common. A null result would imply that terrestrial planets in the HZ are very rare and that life might also be quite rare.

  3. Magnetic Barkhausen noise for reliable detection of the heat affected zone in welded ship steel plate

    NASA Astrophysics Data System (ADS)

    Blaow, Mohamed M.; Shaw, Brian A.

    2014-02-01

    The applicability of the Barkhausen noise technique to non-destructively determine the heat affected zone (HAZ) in welded steel plates was investigated. Magnetic Barkhausen noise measurements were conducted on welded hot-rolled low carbon ship steel plates to determine the MBN behaviour following the exposure to elevated heat in a localized region by welding. The exciting field was applied parallel to the weld bead. The results showed a variation in MBN level along a line that crosses the weld bead. The MBN intensity was higher in the near weld material compared with a lower intensity when the measurement setup was moved away from the weld bead in both sides of the weld. The increased MBN level was attributed to the induced residual tensile stresses as a result of the shrinkage of the hot zone. The variation of MBN along the measurement line was eliminated after the welded plate was shot peened. The decrease in MBN intensity after shot peening was attributed to the induced compressive stresses. The results were explained in terms of different mechanisms of interaction of domain walls with residual tensile and compressive stresses.

  4. Low temperature sensitization of type 304 stainless steel pipe weld heat affected zone

    NASA Astrophysics Data System (ADS)

    Schmidt, Charles G.; Caligiuri, Robert D.; Eiselstein, Lawrence E.; Wing, Sharon S.; Cubicciotti, Daniel

    1987-08-01

    Large-diameter Type 304 stainless steel pipe weld heat-affected zone (HAZ) was investigated to determine the rate at which low temperature sensitization (LTS) can occur in weld HAZ at nuclear reactor operating temperatures and to determine the effects of LTS on the initiation and propagation of intergranular stress corrosion cracks (IGSCC). The level of sensitization was determined with the electrochemical potentiokinetic reactivation (EPR) test, and IGSCC susceptibility was determined with constant extension rate tests (CERT) and actively loaded compact tension (CT) tests. Substructural changes and carbide compositions were analyzed by electron microscopy. Weld HAZ was found to be susceptible to IGSCC in the as-welded condition for tests conducted in 8-ppm-oxygen, high-purity water at 288 °C. For low oxygen environments ( i.e., 288 °C/0.2 ppm O2 or 180 °C/1.0 ppm O2), IGSCC susceptibility was detected only in weld HAZ that had been sensitized at temperatures from 385 °C to 500 °C. Lower temperature heat treatments did not produce IGSCC. The microscopy studies indicate that the lack of IGSCC susceptibility from LTS heat treatments below 385 °C is a result of the low chromium-to-iron ratio in the carbide particles formed at grain boundaries. Without chromium enrichment of carbides, no chromium depleted zone is produced to enhance IGSCC susceptibility.

  5. The role of fault zone in affecting multiphase flow at Yucca Mountain

    SciTech Connect

    Tsang, Y.W.; Pruess, K.; Wang, J.S.Y.

    1993-12-31

    Within Yucca Mountain, the potential High Level Nuclear-Waste Repository site, there are large scale fault zones, most notably the Ghost Dance Fault. The effect of such high-permeability, large-scale discontinuities on the flow and transport is a question of concern in assessing the ability of the site to isolate radio-nuclides from the biosphere. In this paper, we present a numerical study to investigate the role of the fault in affecting both the liquid and gas phase flows in the natural state at Yucca Mountain prior to waste emplacement, as well as after the waste emplacement when the fluid flow is strongly heat-driven. Our study shows that if the characteristic curves of the Ghost Dance Fault obey the same relationship between saturated permeability and capillary scaling parameter, is as observed from the measured data of Yucca Mountain welded and nonwelded tuffs, Apache Leap tuffs, and Las Cruces soil, then a large saturated permeability of the Ghost Dance Fault will play little role in channeling water into the fault, or in enhancing the flow of water down the fault. However, the Fault may greatly enhance the upward gas flow after emplacement of waste. This may have implications on the transport of gaseous radio-nuclides such as C{sup 14}. The results of this study also focus attention on the need for field measurements of fluid flow in the fault zones.

  6. The role of fault zones in affecting multiphase flow at Yucca Mountain

    SciTech Connect

    Tsang, Y.W.; Pruess, K.; Wang, J.S.Y.

    1993-01-01

    Within Yucca Mountain, the potential High Level Nuclear-Waste Repository site, there are large scale fault zones, most notably the Ghost Dance Fault. The effect of such high-permeability, large scale discontinuities on the flow and transport is a question of concern in assessing the ability of the site to isolate radio-nuclides from the biosphere. In this paper, we present a numerical study to investigate the role of the fault in affecting both the liquid and gas phase flows in the natural state at Yucca Mountain prior to waste emplacement, as well as after the waste emplacement when the fluid flow is strongly heat-driven. Our study shows that if the characteristic curves of the Ghost Dance Fault obey the same relationship between saturated permeability and capillary scaling parameter, as is observed from the measured data of Yucca Mountain welded and nonwelded tuffs. Apache Leap tuffs, and Las Cruces soil, then a large saturated permeability of the Ghost Dance Fault will play little role in channeling water into the fault, or inenhancing the flow of water down the fault. However, the Fault may greatly enhance the upward gas flow after emplacement of waste. This may have implications on the transport of gaseous radio-nuclides such as C{sup 14}. The results of this study also focus attention on the need for field measurements of fluid flow in the fault zones.

  7. Zones of impact around icebreakers affecting beluga whales in the Beaufort Sea.

    PubMed

    Erbe, C; Farmer, D M

    2000-09-01

    A software model estimating zones of impact on marine mammals around man-made noise [C. Erbe and D. M. Farmer, J. Acoust. Soc. Am. 108, 1327-1331 (2000)] is applied to the case of icebreakers affecting beluga whales in the Beaufort Sea. Two types of noise emitted by the Canadian Coast Guard icebreaker Henry Larsen are analyzed: bubbler system noise and propeller cavitation noise. Effects on beluga whales are modeled both in a deep-water environment and a near-shore environment. The model estimates that the Henry Larsen is audible to beluga whales over ranges of 35-78 km, depending on location. The zone of behavioral disturbance is only slightly smaller. Masking of beluga communication signals is predicted within 14-71-km range. Temporary hearing damage can occur if a beluga stays within 1-4 km of the Henry Larsen for at least 20 min. Bubbler noise impacts over the short ranges quoted; propeller cavitation noise accounts for all the long-range effects. Serious problems can arise in heavily industrialized areas where animals are exposed to ongoing noise and where anthropogenic noise from a variety of sources adds up. PMID:11008834

  8. The maternal environment affects offspring viability via an indirect effect of yolk investment on offspring size.

    PubMed

    Warner, Daniel A; Lovern, Matthew B

    2014-01-01

    Environmental conditions that reproductive females experience can influence patterns of offspring provisioning and fitness. In particular, prey availability can influence maternal reproduction and, in turn, affect the viability of their offspring. Although such maternal effects are widespread, the mechanisms by which these effects operate are poorly understood. We manipulated the amount of prey available to female brown anole lizards (Anolis sagrei) to evaluate how this factor affects patterns of reproductive investment (total egg output, egg size, yolk steroids) and offspring viability (morphology, growth, survival). Experimental reduction of yolk in a subset of eggs enabled us to evaluate a potential causal mechanism (yolk investment) that mediates the effect of maternal prey availability on offspring viability. We show that limited prey availability significantly reduced egg size, which negatively influenced offspring size, growth, and survival. Experimental yolk removal from eggs directly reduced offspring size, which, in turn, negatively affected offspring growth and survival. These findings show that maternal environments (i.e., low prey) can affect offspring fitness via an indirect effect of yolk investment on offspring size and highlight the complex set of indirect effects by which maternal effects can operate. PMID:24642545

  9. Microstructure and embrittlement of the fine-grained heat-affected zone of ASTM4130 steel

    NASA Astrophysics Data System (ADS)

    Li, Li-Ying; Wang, Yong; Han, Tao; Li, Chao-Wen

    2011-08-01

    The mechanical properties and microstructure features of the fine-grained heat-affected zone (FGHAZ) of ASTM4130 steel was investigated by optical microscope (OM), scanning electron microscope (SEM), transmission electron microscope (TEM), and welding thermal simulation test. It is found that serious embrittlement occurs in the FGHAZ with an 81.37% decrease of toughness, compared with that of the base metal. Microstructure analysis reveals that the FGHAZ is mainly composed of acicular, equiaxed ferrite, granular ferrite, martensite, and martensite-austenite (M-A) constituent. The FGHAZ embrittlement is mainly induced by granular ferrite because of carbides located at its boundaries and sub-boundaries. Meanwhile, the existence of martensite and M-A constituent, which distribute in a discontinuous network, is also detrimental to the mechanical properties.

  10. Plant hybrid zones affect biodiversity: Tools for a genetic-based understanding of community structure

    SciTech Connect

    Whitham, T.G.; Martinsen, G.D.; Keim, P.; Floate, K.D.; Dungey, H.S. |; Potts, B.M.

    1999-03-01

    Plant hybrid zones are dynamic centers of ecological and evolutionary processes for plants and their associated communities. Studies in the wild and in gardens with synthetic crosses showed that hybrid eucalypts supports the greatest species richness and abundances of insect and fungal taxa. In an updated review of 152 case studies of taxa associated with diverse hybridizing systems, there were 43 (28%) cases of hybrids being more susceptible than their parent species, 7 (5%) resistant, 35 (23%) additive, 35 (23%) dominant, and 32 (21%) showed no response to hybridization. Thus, most taxa respond to hybrids in ways that result in equal or greater abundance, and hybrids tend to accumulate the taxa of their parent species. These studies suggest that genetic-based plant traits affect the distribution of many species and that the variation in hybrids can be used as tools to examine the genetic components of community structure and biodiversity.

  11. Microstructural transformations of heat affected zones in duplex steel welded joints

    SciTech Connect

    Nowacki, Jerzy . E-mail: jnowacki@ps.pl; Lukojc, Aleksander

    2006-06-15

    The influence of the welding thermal conditions exemplified by heat input and heat treatment after welding on the structure of the heat affected zone (HAZ) UNS S31803 has been analysed. The post weld treatment was used to create the precisely defined thermal conditions for the decomposition of primary phases in the HAZ, by a multi-layer welding thermal cycle stimulation. Detailed analyses of the microstructure and chemical composition of the phases in the different post welded conditions were performed by scanning electron microscopy (SEM) combined with energy dispersive spectrometry (EDS) and transmission electron microscopy (TEM). Three types of secondary precipitates have been observed: secondary austenite ({gamma}{sub 2}), carbides: M{sub 23}C{sub 6} and M{sub 7}C{sub 3}. The dependence of the secondary austenite volume fraction and morphology in the HAZ on thermal cycle have been interpreted. The eutectoid decomposition of the primary phases in the analysed thermal conditions was confirmed.

  12. Moessbauer analysis of heat affected zones of an SA 508 steel weld

    SciTech Connect

    Kwon, S.J.; Oh, S.J.; Kim, S.; Lee, S.; Kim, J.H.

    1998-12-18

    Microstructure of a heat affected zone (HAZ) in a weld is influenced by many factors such as chemical composition, welding condition, and peak temperature. It is more complex under multi-pass welding because of the repeated heat input. For the analysis of the HAZ microstructure, optical microscope, electron microscope, and X-ray diffraction techniques have been widely used. However, their application is limited since they can hardly make quantitative analysis of HAZ where numerous phases such as martensite, bainite, ferrite, pearlite, austenite, and carbides are co-existing. Moessbauer spectroscopy, in such a case, is particularly useful due to the capability of quantitative analysis on the fraction of each phase. In this study, phases present in the HAZ of an SA 508 steel were identified, and their fractions were quantitatively determined by Moessbauer spectroscopy in conjunction with microscopic observations.

  13. Correlation of the microstructure and fracture toughness of the heat-affected zones of an SA 508 steel

    SciTech Connect

    Kim, S.; Kang, S.Y.; Oh, S.J.; Kwon, S.J.; Lee, S.; Kim, J.H.; Hong, J.H.

    2000-04-01

    In this study, microstructures of a heat-affected zone (HAZ) of an SA 508 steel were identified by Moessbauer spectroscopy in conjunction with microscopic observations, and were correlated with fracture toughness. Specimens with the peak temperature raised to 1350 C showed mostly martensite. With the peak temperature raised to 900 C, the martensite fraction was reduced, while bainite or martensite islands were formed because of the slow cooling from the lower austenite region and the increase in the prior austenite grain size. As the martensite fraction present inside the HAZ increased, hardness and strength tended to increase, whereas fracture toughness decreased. The microstructures were not changed much from the base metal because of the minor tempering effect when it was raised to 650 C or 700 C. However, fracture toughness of the subcritical HAZ with the peak temperature raised to 650 C to 700 C was seriously reduced after postweld heat treatment (PWHT) because carbide particles were of primary importance in initiating voids. Thus, the most important microstructural factors affecting fracture toughness were the martensite fraction before PWHT and the carbide fraction after PWHT.

  14. Microstructural changes in HSLA-100 steel thermally cycled to simulate the heat-affected zone during welding

    SciTech Connect

    Spanos, G.; Fonda, R.W.; Vandermeer, R.A.; Matuszeski, A.

    1995-12-01

    The microstructural changes that occur in a commercial HSLA-100 steel thermally cycled to simulate weld heat affected zone (HAZ) behavior were systematically investigated primarily by transmission electron microscopy (TEM). Eight different weld thermal cycles, with peak temperatures representative of four HAZ regions (the tempered region, the intercritical region, the fine-grained austenitized region, and the coarse-grained austenitized region) and cooling rates characteristic of high heat input (cooling rate (CR) = 5 C/s) and low heat input (CR = 60 C/s) welding were simulated in a heating/quenching dilatometer. The as-received base plate consisted of heavily tempered lath martensite, acicular ferrite, and retained austenite matrix phases with precipitates of copper, niobium-carbonitride, and cementite. The microstructural changes in both the matrix and precipitate phases due to thermal cycling were examined by TEM and correlated with the results of (1) conventional optical microscopy, (2) prior austenite grain size measurements, (3) microhardness testing, and (4) dilatometric analysis. Many of the thermal cycles resulted in dramatic changes in both the microstructures and the properties due to the synergistic interaction between the simulated position in the HAZ and the heat input. Some of these microstructures deviate substantially from those predicted from published continuous cooling transformation (CCT) curves. The final microstructure was predominantly dependent upon peak temperature (i.e., position within the HAZ), although the cooling rate (i.e., heat input) strongly affected the microstructures of the simulated intercritical and fine-grained austenitized regions.

  15. Flavor of oranges as impacted by abscission zone formation for trees affected by huanglongbing disease and Lasiodiploida infection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Trees affected by Huanglongbing (HLB) exhibit excessive fruit drop, which is exacerbated by secondary infection of the abscission zone by the fungus Lasiodiplodia. ‘Hamlin’ orange trees, both healthy and affected by HLB, Candidatus Liberibacter asiaticus (CLas, determined by Polymerase chain reactio...

  16. Root-zone acidity affects relative uptake of nitrate and ammonium from mixed nitrogen sources

    NASA Technical Reports Server (NTRS)

    Vessey, J. K.; Henry, L. T.; Chaillou, S.; Raper, C. D. Jr; Raper CD, J. r. (Principal Investigator)

    1990-01-01

    Soybean plants (Glycine max [L.] Merr. cv Ransom) were grown for 21 days on 4 sources of N (1.0 mM NO3-, 0.67 mM NO3- plus 0.33 mM NH4+, 0.33 mM NO3- plus 0.67 mM NH4+, and 1.0 mM NH4+) in hydroponic culture with the acidity of the nutrient solution controlled at pH 6.0, 5.5, 5.0, and 4.5. Dry matter and total N accumulation of the plants was not significantly affected by N-source at any of the pH levels except for decreases in these parameters in plants supplied solely with NH4+ at pH 4.5. Shoot-to-root ratios increased in plants which had an increased proportion [correction of proporiton] of NH4(+)-N in their nutrient solutions at all levels of root-zone pH. Uptake of NO3- and NH4+ was monitored daily by ion chromatography as depletion of these ions from the replenished hydroponic solutions. At all pH levels the proportion of either ion that was absorbed increased as the ratio of that ion increased in the nutrient solution. In plants which were supplied with sources of NO3- plus NH4+, NH4+ was absorbed at a ratio of 2:1 over NO3- at pH 6.0. As the pH of the root-zone declined, however, NH4+ uptake decreased and NO3- uptake increased. Thus, the NH4+ to NO3- uptake ratio declined with decreases in root-zone pH. The data indicate a negative effect of declining root-zone pH on NH4+ uptake and supports a hypothesis that the inhibition of growth of plants dependent on NH4(+)-N at low pH is due to a decline in NH4+ uptake and a consequential limitation of growth by N stress.

  17. Characterization of microstructure, local deformation and microchemistry in Alloy 690 heat-affected zone and stress corrosion cracking in high temperature water

    NASA Astrophysics Data System (ADS)

    Lu, Zhanpeng; Chen, Junjie; Shoji, Tetsuo; Takeda, Yoichi; Yamazaki, Seiya

    2015-10-01

    With increasing the distance from the weld fusion line in an Alloy 690 heat-affected zone, micro-hardness decreases, kernel average misorientation decreases and the fraction of Σ3 boundaries increases. Chromium depletion at grain boundaries in the Alloy 690 heat-affected zone is less significant than that in an Alloy 600 heat-affected zone. Alloy 690 heat-affected zone exhibits much higher IGSCC resistance than Alloy 600 heat-affected zone in simulated pressurized water reactor primary water. Heavily cold worked Alloy 690 exhibits localized intergranular stress corrosion cracking. The effects of metallurgical and mechanical properties on stress corrosion cracking in Alloy 690 are discussed.

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

    SciTech Connect

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

    2006-01-31

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

  19. Initial Evaluation of the Heat-Affected Zone, Local Embrittlement Phenomenon as it Applies to Nuclear Reactor Vessels

    SciTech Connect

    McCabe, D.E.

    1999-09-01

    The objective of this project was to determine if the local brittle zone (LBZ) problem, encountered in the testing of the heat-affected zone (HAZ) part of welds in offshore platform construction, can also be found in reactor pressure vessel (RPV) welds. Both structures have multipass welds and grain coarsening along the fusion line. Literature was obtained that described the metallurgical evidence and the type of research work performed on offshore structure welds.

  20. Brain size affects female but not male survival under predation threat

    PubMed Central

    Kotrschal, Alexander; Buechel, Séverine D; Zala, Sarah M; Corral-Lopez, Alberto; Penn, Dustin J; Kolm, Niclas; Sorci, Gabriele

    2015-01-01

    There is remarkable diversity in brain size among vertebrates, but surprisingly little is known about how ecological species interactions impact the evolution of brain size. Using guppies, artificially selected for large and small brains, we determined how brain size affects survival under predation threat in a naturalistic environment. We cohoused mixed groups of small- and large-brained individuals in six semi-natural streams with their natural predator, the pike cichlid, and monitored survival in weekly censuses over 5 months. We found that large-brained females had 13.5% higher survival compared to small-brained females, whereas the brain size had no discernible effect on male survival. We suggest that large-brained females have a cognitive advantage that allows them to better evade predation, whereas large-brained males are more colourful, which may counteract any potential benefits of brain size. Our study provides the first experimental evidence that trophic interactions can affect the evolution of brain size. PMID:25960088

  1. Brain size affects female but not male survival under predation threat.

    PubMed

    Kotrschal, Alexander; Buechel, Séverine D; Zala, Sarah M; Corral-Lopez, Alberto; Penn, Dustin J; Kolm, Niclas

    2015-07-01

    There is remarkable diversity in brain size among vertebrates, but surprisingly little is known about how ecological species interactions impact the evolution of brain size. Using guppies, artificially selected for large and small brains, we determined how brain size affects survival under predation threat in a naturalistic environment. We cohoused mixed groups of small- and large-brained individuals in six semi-natural streams with their natural predator, the pike cichlid, and monitored survival in weekly censuses over 5 months. We found that large-brained females had 13.5% higher survival compared to small-brained females, whereas the brain size had no discernible effect on male survival. We suggest that large-brained females have a cognitive advantage that allows them to better evade predation, whereas large-brained males are more colourful, which may counteract any potential benefits of brain size. Our study provides the first experimental evidence that trophic interactions can affect the evolution of brain size. PMID:25960088

  2. [New methodologicalapproaches to establishment the sizes of the sanitary protection zone and roadside clear zones of civil airports].

    PubMed

    Kartyshev, O A

    2013-01-01

    This circumstance leads to considerable mistakes it creation of SPZ borders of the airports, in some cases it impedes development of the latters and causes objective difficulties for hygienic assessment of projects. In this article the results of studies on the creation and validation of two new domestic methods for the construction of impact zones of aircraft noise and dispersion of the concentrations of pollutants in assessing the negative impact of airports are considered. Both branch methods agreed upon with the Ministry of Transport have been harmonized with ICAO (International Civil Aviation Organization) requirements. The results of full-scale measurements have confirmed the possibilities of developed software for their implementation in the formation of a common SPZ border of an airport. PMID:23805707

  3. Genome size variation affects song attractiveness in grasshoppers: evidence for sexual selection against large genomes.

    PubMed

    Schielzeth, Holger; Streitner, Corinna; Lampe, Ulrike; Franzke, Alexandra; Reinhold, Klaus

    2014-12-01

    Genome size is largely uncorrelated to organismal complexity and adaptive scenarios. Genetic drift as well as intragenomic conflict have been put forward to explain this observation. We here study the impact of genome size on sexual attractiveness in the bow-winged grasshopper Chorthippus biguttulus. Grasshoppers show particularly large variation in genome size due to the high prevalence of supernumerary chromosomes that are considered (mildly) selfish, as evidenced by non-Mendelian inheritance and fitness costs if present in high numbers. We ranked male grasshoppers by song characteristics that are known to affect female preferences in this species and scored genome sizes of attractive and unattractive individuals from the extremes of this distribution. We find that attractive singers have significantly smaller genomes, demonstrating that genome size is reflected in male courtship songs and that females prefer songs of males with small genomes. Such a genome size dependent mate preference effectively selects against selfish genetic elements that tend to increase genome size. The data therefore provide a novel example of how sexual selection can reinforce natural selection and can act as an agent in an intragenomic arms race. Furthermore, our findings indicate an underappreciated route of how choosy females could gain indirect benefits. PMID:25200798

  4. A process model for the heat-affected zone microstructure evolution in duplex stainless steel weldments: Part I. the model

    NASA Astrophysics Data System (ADS)

    Hemmer, H.; Grong, Ø.

    1999-11-01

    The present investigation is concerned with modeling of the microstructure evolution in duplex stainless steels under thermal conditions applicable to welding. The important reactions that have been modeled are the dissolution of austenite during heating, subsequent grain growth in the delta ferrite regime, and finally, the decomposition of the delta ferrite to austenite during cooling. As a starting point, a differential formulation of the underlying diffusion problem is presented, based on the internal-state variable approach. These solutions are later manipulated and expressed in terms of the Scheil integral in the cases where the evolution equation is separable or can be made separable by a simple change of variables. The models have then been applied to describe the heat-affected zone microstructure evolution during both thick-plate and thin-plate welding of three commercial duplex stainless steel grades: 2205, 2304, and 2507. The results may conveniently be presented in the form of novel process diagrams, which display contours of constant delta ferrite grain size along with information about dissolution and reprecipitation of austenite for different combinations of weld input energy and peak temperature. These diagrams are well suited for quantitative readings and illustrate, in a condensed manner, the competition between the different variables that lead to structural changes during welding of duplex stainless steels.

  5. A process model for the heat-affected zone microstructure evolution in duplex stainless steel weldments: Part I. The model

    SciTech Connect

    Hemmer, H.; Grong, O.

    1999-11-01

    The present investigation is concerned with modeling of the microstructure evolution in duplex stainless steels under thermal conditions applicable to welding. The important reactions that have been modeled are the dissolution of austenite during heating, subsequent grain growth in the delta ferrite regime, and finally, the decomposition of the delta ferrite to austenite during cooling. As a starting point, a differential formulation of the underlying diffusion problem is presented, based on the internal-state variable approach. These solutions are later manipulated and expressed in terms of the Scheil integral in the cases where the evolution equation is separable or can be made separable by a simple change of variables. The models have then been applied to describe the heat-affected zone microstructure evolution during both thick-plate and thin-plate welding of three commercial duplex stainless steel grades: 2205, 2304, and 2507. The results may conveniently be presented in the form of novel process diagrams, which display contours of constant delta ferrite grain size along with information about dissolution and reprecipitation of austenite for different combinations of weld input energy and peak temperature. These diagrams are well suited for quantitative readings and illustrate, in a condensed manner, the competition between the different variables that lead to structural changes during welding of duplex stainless steels.

  6. Dynamic Material Properties of the Heat-Affected Zone (haz) in Resistance SPOT Welding

    NASA Astrophysics Data System (ADS)

    Ha, Ji-Woong; Song, Jung-Han; Huh, Hoon; Lim, Ji-Ho; Park, Sung-Ho

    This paper is concerned with a methodology to identify the dynamic material properties of the heat-affected zone (HAZ) near the base metal in a resistance spot weld process at various strain rates. In order to obtain the dynamic material properties of the HAZ in the spot-welded steel sheet, specimens are prepared to have similar material properties, hardness and microstructure to the actual HAZ. Such thermally simulated specimens are fabricated with the material thermal cycle simulator (MTCS) and compared with the real one for the hardness and microstructure. Dynamic tensile tests are then conducted with a high speed material testing machine. Stress-strain curves of the thermally simulated HAZ are obtained at various strain rates ranged from 0.001/sec to 100/sec. Obtained material properties are applied to the finite element analysis of the spot-welded tensile-shear specimen in order to verify validity of the proposed testing methodology and obtained results. Analysis results demonstrate that the material properties obtained are appropriate for the FE analysis of spot-welded specimens.

  7. A model for heat-affected zone hardness profiles in Al-Li-X alloys

    SciTech Connect

    Rading, G.O.; Berry, J.T.

    1998-09-01

    A model based on reaction kinetics and elemental diffusion is proposed to account for the presence of double inflection in the hardness profiles of the heat-affected zone (HAZ) in weldments of Al-Li-X alloys tested without postweld heat treatment (PWHT). Such profiles are particularly evident when (1) the base metal is in the peak-aged (T8 or T6) temper condition prior to welding; (2) the welding process is a high-heat input process, i.e., gas tungsten arc (GTA), gas metal arc (GMA) or plasma arc (PA) welding; and (3) a filler alloy deficient in lithium (i.e., AA 2319) is used. In the first part of this paper, the theoretical mechanisms are presented. It is proposed that the double inflection appears due to complete or partial reversion of the semi-coherent, plate-like precipitates (i.e., {theta}{prime}, T{sub 1} or S{prime}); coarsening of the plate-like precipitates at constant volume fraction; precipitation of {delta}{prime} as a result of natural aging; and diffusion of lithium from the HAZ into the weld pool due to the concentration gradient between the weld pool and the base metal. In the second part (to be published in next month`s Welding Journal), experimental validation of the model is provided using weldments of the Al-Li-Cu Alloy 2095.

  8. Prediction of carbon steel heat-affected zone microstructure induced by electroslag cladding

    SciTech Connect

    Li, M.V.; Atteridge, D.G.

    1994-12-31

    One of the major concerns in developing electroslag cladding technique is the mechanical properties of the clad heat-affected zone. During the cladding operation, the base metal adjacent to the clad deposit undergoes intensive heating and fast cooling. Mechanical properties of this area are different from, and in most cases inferior to, those of the base metal due to the formation of undesirable microstructure which results from the thermal cycle. To optimize mechanical properties of clad components, steps must be taken to optimize the HAZ microstructure, which is determined by the cladding heat input, geometry of the components, chemistry of the steel, and the thermodynamics and kinetics of phase transformations. There are four main methods for predicting HAZ hardness and microstructure: weld simulation experiments, CCT diagrams, regression analysis based on the carbon equivalents of steels and hardenability studies, and the computational models based on phase transformationkineticss and thermodynamics. The computational approach was adopted in the study to predict the carbon steel HAZ microstructure evolution during electroslag cladding because it is a general approach applicable to a wide range of chemical compositions and welding conditions. The computation model in the study incorporates a grain growth model and a model for austenite decomposition. The empirical grain growth kinetics models and the reaction kinetics model for austenite decomposition originally proposed by Kirkaldy and Venugopalan were calibrated with experimental studies and then coded into a computer program to predict microstructure development. Reasonable agreement was observed between the computer predictions and experimental observations; discrepanciesweree also discussed.

  9. Weld heat-affected-zone response to elevated-temperature deformation

    SciTech Connect

    Bowers, R.J.; Nippes, E.F.

    1996-11-01

    The mechanical response to elevated-temperature deformation was assessed for weld heat-affected-zone (HAZ) and base-metal microstructures in 2.25Cr-1Mo steel. A constant-displacement-rate (CDR) test, capable of determining long-time, notch-sensitivity tendencies, was implemented on a Gleeble 1,500 thermal/mechanical simulator and an Instron. Microstructures representative of the coarse-grained, grain-refined, and intercritical regions of the HAZ were simulated on a Gleeble. Microstructural reproduction reflected the preheat and postweld heat treatments in accordance with the required codes. A K{sub 1} analysis of the data was conducted, which showed that small-scale yielding criteria were adhered to throughout the test. The test results indicated that the high-temperature extensometer control of the Instron was better able to maintain stable crack growth after peak load than the crosshead control of the Gleeble. The CDR test was seen to be an effective, short-time procedure to delineate and compare the strength and relative service life of the structures present in the weld HAZ.

  10. Thermal embrittlement of simulated heat-affected zone in cast austenitic stainless steels

    SciTech Connect

    Mimura, H.; Taniguchi, T.; Horii, Y.; Kume, R.; Uesugi, N.

    1998-08-01

    Metallurgical factors controlling thermal embrittlement in the heat-affected zone (HAZ) of cast austenitic stainless steels were investigated by using the simulated HAZ. It was shown that the simulated HAZ was more susceptible to the thermal embrittlement by aging at 673 K in correspondence with its higher tendency to age hardening and a higher content of ferrite than the parent casting. Electron microprobe analyzer measurement showed that application of the simulated thermal cycle gave a change in the chemical composition of the ferrite, which might be a cause of the higher age hardening of the ferrite in the simulated HAZ. This higher ferrite hardness had a good correlation with fine precipitates of presumably G-phase in the ferrite grain, which existed more in the simulated HAZ than in the parent casting, though it is not clear whether this correlation was only apparent. Ductility of the austenite portion was found to reduce remarkably when surrounded by the hard ferrite of a high fraction. Annealing after aging restored CTOD to some degree. Aging after fatigue cracking gave more embrittlement than a usual procedure for preparation of test specimens, i.e., fatigue cracking after aging.

  11. Fracture analysis of the heat-affected zone in the NESC-1 spinning cylinder experiment

    SciTech Connect

    Keeney, J.A.

    1999-02-01

    This paper presents updated analyses of the cylinder specimen being used in the international Network for Evaluating Steel Components (NESC) large-scale spinning-cylinder project (NESC-1). The NESC was organized as an international forum to exchange information on procedures for structural integrity assessment, to collaborate on specific projects, and to promote the harmonization of international standards. The objective of the NESC-1 project is to focus on a complete procedure for assessing the structural integrity of aged reactor pressure vessels. A clad cylinder containing through-clad and subclad cracks will be tested under pressurized-thermal shock conditions at AEA Technology, Risley, U.K. Three-dimensional finite-element analyses were carried out to determine the effects of including the cladding heat-affected zone (HAZ) in the models. The cylinder was modeled with inner-surface through-clad cracks having a depth of 74 mm and aspect ratios of 2:1 and 6:1. The cylinder specimen was subjected to centrifugal loading followed by a thermal shock and analyzed with a thermoelastic-plastic material model. The peak K{sub 1} values occurred at the clad/HAZ interface for the 6:1 crack and at the HAZ/base interface for the 2:1 crack. The analytical results indicate that cleavage initiation is likely to be achieved for the 6:1 crack, but questionable for the 2:1 crack.

  12. Constitutional liquid film migration in the weld heat affected zone of a nickel-base alloy

    SciTech Connect

    Acoff, V.L.; Thompson, R.G.

    1996-12-31

    It has been discovered that when multiphase alloys are rapidly heated, it is possible to cause melting of the interface between phases. This phenomenon was discovered to exist in the weld heat-affected zone (HAZ) of several alloys and is called constitutional liquation. Constitutional liquation occurs if during melting, the bulk composition is in a non-liquid region of the phase diagram but the tie-line between the liquating phases passes through a liquid region. The liquid produced during constitutional liquation can spread along grain boundaries and promote constitutional liquid film migration (CLFM). Nickel-base alloy 718 has been studied to determine the effect that HAZ peak temperature has on supersaturated solute concentration in the areas behind CLFM grain boundaries. In order to promote CLFM, a Gleeble 1000 thermomechanical device was used to subject heat treated rods of alloy 718 to rapid thermal cycles. Results show that the concentration of niobium in the migrated region (area behind the migrated boundary) was higher than the niobium concentration in the matrix for HAZ peak temperatures below the solidus temperature (1,227 C and 1,240 C). For an HAZ peak temperature above the solidus temperature (1,250 C), there was no significant difference between the niobium concentration in the migrated region and the matrix.

  13. Microstructural response to heat affected zone cracking of prewelding heat-treated Inconel 939 superalloy

    SciTech Connect

    Gonzalez, M.A.; Garza, A.

    2011-12-15

    The microstructural response to cracking in the heat-affected zone (HAZ) of a nickel-based IN 939 superalloy after prewelding heat treatments (PWHT) was investigated. The PWHT specimens showed two different microstructures: 1) spherical ordered {gamma} Prime precipitates (357-442 nm), with blocky MC and discreet M{sub 23}C{sub 6} carbides dispersed within the coarse dendrites and in the interdendritic regions; and 2) ordered {gamma} Prime precipitates in 'ogdoadically' diced cube shapes and coarse MC carbides within the dendrites and in the interdendritic regions. After being tungsten inert gas welded (TIG) applying low heat input, welding speed and using a more ductile filler alloy, specimens with microstructures consisting of spherical {gamma} Prime precipitate particles and dispersed discreet MC carbides along the grain boundaries, displayed a considerably improved weldability due to a strong reduction of the intergranular HAZ cracking associated with the liquation microfissuring phenomena. - Highlights: Black-Right-Pointing-Pointer Homogeneous microstructures of {gamma} Prime spheroids and discreet MC carbides of Ni base superalloys through preweld heat treatments. Black-Right-Pointing-Pointer {gamma} Prime spheroids and discreet MC carbides reduce the intergranular HAZ liquation and microfissuring of Nickel base superalloys. Black-Right-Pointing-Pointer Microstructure {gamma} Prime spheroids and discreet blocky type MC carbides, capable to relax the stress generated during weld cooling. Black-Right-Pointing-Pointer Low welding heat input welding speeds and ductile filler alloys reduce the HAZ cracking susceptibility.

  14. [Characteristics of particle size structure of plankton community in turbidity zone of near-shore waters, Liaoning Province of Northeast China].

    PubMed

    Song, Lun; Wang, Nian-bin; Song, Yong-Gang; Li, Nan

    2013-04-01

    Estuary and nearshore waters have complicated environment, where plankton community has a frequent feedback regulation and a very unstable particle size structure. In this paper, an investigation was made on the particle size structure of plankton in the turbidity zone of nearshore and port area waters in Liaoning Province of Northeast China. In the waters with high concentration inorganic nitrogen, phytoplankton biomass was mainly of small particle sizes, with the equivalent sphere diameter (ESD) being primarily 20-100 micro m, while in low nutrient waters, the phytoplankton biomass was mainly of larger size particles, with the ESD>100 micro m, indicating that the phytoplankton feedback regulation caused the phytoplankton community to be comprised of small sized organisms as part of the biological responses to high concentration suspended solids, which reduced the individual number of larger organisms such as Coscinodiscus. sp. and other species, and in turn, directly affected the fisheries resources, including a variety of fish and shrimp larvae fed on phytoplankton. A normalized biomass size spectrum with the characteristics of nearshore shallow aquatic oceanic ecosystems exhibiting eutrophication was constructed. The spectrum slope indicated that the plankton community biomass would gradually increase in size. The feasibility of using dinoflagellates and cladocerans as the bio-indicators for eutrophication was discussed. PMID:23898643

  15. Particle size distribution and estimated carbon flux across the Arabian Sea oxygen minimum zone

    NASA Astrophysics Data System (ADS)

    Roullier, F.; Berline, L.; Guidi, L.; Durrieu De Madron, X.; Picheral, M.; Sciandra, A.; Pesant, S.; Stemmann, L.

    2014-08-01

    The goal of the Arabian Sea section of the TARA oceans expedition was to study large particulate matter (LPM > 100 μm) distributions and possible impact of associated midwater biological processes on vertical carbon export through the oxygen minimum zone (OMZ) of this region. We propose that observed spatial patterns in LPM distribution resulted from the timing and location of surface phytoplankton bloom, lateral transport, microbial processes in the core of the OMZ, and enhanced biological processes mediated by bacteria and zooplankton at the lower oxycline. Indeed, satellite-derived net primary production maps showed that the northern stations of the transect were under the influence of a previous major bloom event while the most southern stations were in a more oligotrophic situation. Lagrangian simulations of particle transport showed that deep particles of the northern stations could originate from the surface bloom while the southern stations could be considered as driven by 1-D vertical processes. In the first 200 m of the OMZ core, minima in nitrate concentrations and the intermediate nepheloid layer (INL) coincided with high concentrations of 100 μm < LPM < 200 μm. These particles could correspond to colonies of bacteria or detritus produced by anaerobic microbial activity. However, the calculated carbon flux through this layer was not affected. Vertical profiles of carbon flux indicate low flux attenuation in the OMZ, with a Martin model b exponent value of 0.22. At three stations, the lower oxycline was associated to a deep nepheloid layer, an increase of calculated carbon flux and an increase in mesozooplankton abundance. Enhanced bacterial activity and zooplankton feeding in the deep OMZ is proposed as a mechanism for the observed deep particle aggregation. Estimated lower flux attenuation in the upper OMZ and re-aggregation at the lower oxycline suggest that OMZ may be regions of enhanced carbon flux to the deep sea relative to non OMZ regions.

  16. Particles size distribution and carbon flux across the Arabian Sea Oxygen Minimum Zone

    NASA Astrophysics Data System (ADS)

    Roullier, F.; Berline, L.; Guidi, L.; Sciandra, A.; Durrieu De Madron, X.; Picheral, M.; Pesant, S.; Stemmann, L.

    2013-12-01

    The goal of the Arabian Sea section of the TARA oceans expedition was to study Large Particulate Matter (LPM > 100 μm) distributions and possible impact of associated midwater biological processes on vertical carbon export through the Oxygen Minimum Zone (OMZ) of this region. We found that spatial patterns in LPM distribution resulted from the timing and location of surface phytoplankton bloom, lateral transport, microbial processes in the core of the OMZ, and zooplankton activity at the lower oxycline. Indeed, satellite-derived net primary production maps showed that the northern stations of the transect were under the influence of a previous major bloom event while, the most southern stations were in a more oligotrophic situation. Lagrangian simulations of particle transport showed that deep particles of the northern stations could originate from the surface bloom while the southern stations could be considered as driven by 1-D vertical processes. In the first 200 m of the OMZ core, minima in nitrate concentrations and the Intermediate Nepheloid Layer (INL) coincided with high concentrations of 100 μm < LPM < 200 μm. These particles could correspond to colonies of bacteria or detritus produced by anaerobic microbial activity. However, the calculated carbon flux through this layer was not affected. Vertical profiles of carbon flux indicate low flux attenuation in the OMZ, with a Martin model b exponent value of 0.22. At the lower oxycline, a deep nepheloid layer was associated to an increase of carbon flux and an increase in mesozooplankton abundance. Zooplankton feeding on un-mineralized sinking particles in the OMZ is proposed as a mechanism for the observed deep particle aggregation. These results suggest that OMZ may be regions of enhanced carbon flux to the deep sea relative to non-OMZ regions.

  17. Beam size measurement of the stored electron beam at the APS storage ring using zone plate optics and undulator radiation

    SciTech Connect

    Cai, Z.; Lai, B.; Yun, W.

    1997-10-01

    Beam sizes of the stored electron beam at the Advanced Photon Source storage ring were measured using zone-plate optics and undulator radiation. A gold Fresnel zone plate (3.5 {micro}m thick) located 33.9 meters from the x-ray source focused radiation of 18 keV, selected by a cryogenically cooled Si(111) crystal in horizontal deflection, and formed a source image in a transverse plane 2.41 m downstream. The sizes of the source image were determined from measured intensity profiles of x-ray fluorescence from a smooth nickel edge (1.5 {micro}m thick), fabricated using a lithographic technique, while the nickel edge was scanned across over the beam in the transverse plane. The measured vertical and horizontal sizes of the electron beam were 60 {+-} 4.3 {micro}m and 300 {+-} 13 {micro}m, respectively, in reasonable agreement with the expected values.

  18. Orchestrating immune responses: How size, shape and rigidity affect the immunogenicity of particulate vaccines.

    PubMed

    Benne, Naomi; van Duijn, Janine; Kuiper, Johan; Jiskoot, Wim; Slütter, Bram

    2016-07-28

    Particulate carrier systems are promising drug delivery vehicles for subunit vaccination as they can enhance and direct the type of T cell response. In order to develop vaccines with optimal immunogenicity, a thorough understanding of parameters that could affect the strength and quality of immune responses is required. Pathogens have different dimensions and stimulate the immune system in a specific way. It is therefore not surprising that physicochemical characteristics of particulate vaccines, such as particle size, shape, and rigidity, affect multiple processes that impact their immunogenicity. Among these processes are the uptake of the particles from the site of administration, passage through lymphoid tissue and the uptake, antigen processing and activation of antigen-presenting cells. Herein, we systematically review the role of the size, shape and rigidity of particulate vaccines in enhancing and skewing T cell response and attempted to provide a "roadmap" for rational vaccine design. PMID:27221070

  19. Improved Resistance to Laser Weld Heat-Affected Zone Microfissuring in a Newly Developed Superalloy HAYNES 282

    NASA Astrophysics Data System (ADS)

    Osoba, L. O.; Ding, R. G.; Ojo, O. A.

    2012-11-01

    Gleeble thermomechanical simulation and microstrucutural analyses of laser beam weldability of a newly developed precipitation-hardened nickel-base HAYNES alloy 282 were performed to better understand the fundamental cause of heat-affected zone (HAZ) cracking and how to prevent the cracking problem in the material. Submicron size intergranular M5B3 particles are identified for the first time in the present work by transmission electron microscopy, and were found to be the primary cause of HAZ grain boundary liquation cracking in the alloy. Complete dissolution of the liquating M5B3 particles by preweld heat treatment exacerbated rather than reduced susceptibility to cracking, which could be attributed to nonequilibrium intergranular segregation of boron atoms, liberated by the complete dissolution of the boride particles, during cooling from heat treatment temperature. Consequently, to reduce the HAZ cracking, a preweld heat treatment that reduces the volume fraction of the M5B3 particles while minimizing nonequilibrium grain boundary boron segregation is necessary, and this is possible by heat treating the alloy at 1353 K to 1373 K (1080 °C to 1100 °C). Further improvement in cracking resistance to produce crack-free welds is achieved by subjecting the alloy to thermomechanically induced grain refinement coupled with the preweld heat treatment at 1353 K (1080 °C). A Gleeble hot ductility test showed that formation of the crack-free welds is unexplainable by mere reduction in grain size without considering the effect of grain refinement on intergranular liquid produced by subsolidus liquation of the M5B3 borides.

  20. Use of coastal zone color scanner imagery to identify nearshore ocean areas affected by land-based pollutants. Final report

    SciTech Connect

    LaPointe, T.F.; Basta, D.J.

    1981-01-01

    The purpose of the analysis was to use remotely sensed satellite imagery to determine the spatial boundaries of nearshore areas or zones likely to be affected by pollutants from land-based sources, so that data collected on the presence or absence of living marine resources could be combined with information on land-based pollutant discharges in a preliminary relative assessment of potential risk. Ocean zones of impact related to East Coast estuaries and embayments were approximated using reflectance patterns from data transmitted from the Coastal Zone Color Scanner (CZCS) instrument mounted on the NASA Nimbus-7 satellite. Data were transformed from numerical measures of radiance to photographic images suitable for identifying and mapping ocean impact zones through a simple enhancement technique.

  1. Increasing the size of portion options affects intake but not portion selection at a meal.

    PubMed

    Zuraikat, Faris M; Roe, Liane S; Privitera, Gregory J; Rolls, Barbara J

    2016-03-01

    In an environment with large portion sizes, allowing consumers more control over their portion selection could moderate the effects on energy intake. We tested whether having subjects choose a portion from several options influenced the amount selected or consumed when all portion sizes were systematically increased. In a crossover design, 24 women and 26 men ate lunch in the lab once a week for 3 weeks. At each meal, subjects chose a portion of macaroni and cheese from a set of 3 portion options and consumed it ad libitum. Across 3 conditions, portion sizes in the set were increased; the order of the conditions was counterbalanced across subjects. For women the portion sets by weight (g) were 300/375/450, 375/450/525, and 450/525/600; for men the portions were 33% larger. The results showed that increasing the size of available portions did not significantly affect the relative size selected; across all portion sets, subjects chose the smallest available portion at 59% of meals, the medium at 27%, and the largest at 15%. The size of portions offered did, however, influence meal intake (P < 0.0001). Mean intake (±SEM) was 16% greater when the largest set was offered (661 ± 34 kcal) than when the medium and smallest sets were offered (both 568 ± 18 kcal). These results suggest that portions are selected in relation to the other available options, and confirm the robust effect of portion size on intake. Although presenting a choice of portions can allow selection of smaller amounts, the sizes offered are a critical determinant of energy intake. Thus, the availability of choices could help to moderate intake if the portions offered are within an appropriate range for energy needs. PMID:26721718

  2. On the decomposition of austenite in the heat-affected zone upon welding of high-strength steels

    NASA Astrophysics Data System (ADS)

    Efimenko, L. A.; Ramus', A. A.; Merkulova, A. O.

    2015-05-01

    The kinetics of the decomposition of austenite in the heat-affected zone of welded joints of low-carbon microalloyed high-strength steels has been investigated. A new approach to selecting the parameters of the thermal cycle of welding that ensure the service characteristics of welded joints on a level no lower than the normative requirements is suggested.

  3. Factors Affecting Motivation and Job Satisfaction of Academic Staff of Universities in South-South Geopolitical Zone of Nigeria

    ERIC Educational Resources Information Center

    Osakwe, Regina N.

    2014-01-01

    This study determined the factors affecting motivation and job satisfaction of non-management academic staff of universities in South-South geopolitical zone of Nigeria. It employed an expost-facto research design. Three research questions and two hypotheses were raised for the study. A sample of four hundred and fifty non-management academic…

  4. Factors affecting the dynamics of the honeybee (Apis mellifera) hybrid zone of South Africa.

    PubMed

    Beekman, M; Allsopp, M H; Wossler, T C; Oldroyd, B P

    2008-01-01

    Hybrid zones are found wherever two populations distinguishable on the basis of heritable characters overlap spatially and temporally and hybridization occurs. If hybrids have lower fitness than the parental types a tension zone may emerge, in which there is a barrier to gene flow between the two parental populations. Here we discuss a hybrid zone between two honeybee subspecies, Apis mellifera capensis and A. m. scutellata and argue that this zone is an example of a tension zone. This tension zone is particularly interesting because A. m. capensis can be a lethal social parasite of A. m. scutellata. However, despite its parasitic potential, A. m. capensis appears to be unable to increase its natural range unassisted. We propose three interlinked mechanisms that could maintain the South African honeybee hybrid zone: (1) low fitness of intercrossed and genetically mixed colonies arising from inadequate regulation of worker reproduction; (2) higher reproductive success of A. m. scutellata via both high dispersal rates into the hybrid zone and increased competitiveness of males, countered by (3) the parasitic nature of A. m. capensis. PMID:17848972

  5. Evaluation of Heat-affected Zone Hydrogen-induced Cracking in High-strength Steels

    NASA Astrophysics Data System (ADS)

    Yue, Xin

    Shipbuilding is heavily reliant on welding as a primary fabrication technique. Any high performance naval steel must also possess good weldability. It is therefore of great practical importance to conduct weldability testing of naval steels. Among various weldability issues of high-strength steels, hydrogen-induced cracking (HIC) in the heat-affected zone (HAZ) following welding is one of the biggest concerns. As a result, in the present work, research was conducted to study the HAZ HIC susceptibility of several naval steels. Since the coarse-grained heat-affected zone (CGHAZ) is generally known to be the most susceptible to HIC in the HAZ region, the continuous cooling transformation (CCT) behavior of the CGHAZ of naval steels HSLA-65, HSLA-100, and HY-100 was investigated. The CGHAZ microstructure over a range of cooling rates was characterized, and corresponding CCT diagrams were constructed. It was found that depending on the cooling rate, martensite, bainite, ferrite and pearlite can form in the CGHAZ of HSLA-65. For HSLA-100 and HY-100, only martensite and bainite formed over the range of cooling rates that were simulated. The constructed CCT diagrams can be used as a reference to select welding parameters to avoid the formation of high-hardness martensite in the CGHAZ, in order to ensure resistance to hydrogen-induced cracking. Implant testing was conducted on the naval steels to evaluate their susceptibility to HAZ HIC. Stress vs. time to failure curves were plotted, and the lower critical stress (LCS), normalized critical stress ratio (NCSR) and embrittlement index (EI) for each steel were determined, which were used to quantitatively compare HIC susceptibility. The CGHAZ microstructure of the naval steels was characterized, and the HIC fracture behavior was studied. Intergranular (IG), quasi-cleavage (QC) and microvoid coalescence (MVC) fracture modes were found to occur in sequence during the crack initiation and propagation process. This was

  6. Sediment size distribution and composition in a reservoir affected by severe water level fluctuations.

    PubMed

    López, Pilar; López-Tarazón, José A; Casas-Ruiz, Joan P; Pompeo, Marcelo; Ordoñez, Jaime; Muñoz, Isabel

    2016-01-01

    The reservoir sediments are important sinks for organic carbon (OC), the OC burial being dependent on two opposite processes, deposition and mineralization. Hence factors such as severe water level fluctuations are expected to influence the rate of OC accumulation as they may affect both deposition and mineralization. The Barasona Reservoir has been historically threatened by siltation, whilst the use of water for irrigation involves a drastic decrease of the water level. In this context, we have studied the physical and chemical characteristics (grain size, major and minor elemental compositions, organic and inorganic carbon, and nitrogen) of the recent sediments of the Barasona Reservoir and the relationships among them in order to: a) elucidate the main processes governing OC accumulation, b) evaluate the rate of OC mineralization and c) approach the effect of drought on the sediment characteristics in this system. Our results indicated that Barasona sediments were dominated by fine silts (>60%) and clays (>20%), the mean particle size decreasing from tail to dam. Desiccation increased particle sorting and size distribution became bimodal, but no effect on average size was observed. Attending to the composition, Barasona sediments were very homogeneous with low concentrations of nitrogen (TN) and phosphorus (<1.2 g kg(-1) dw and <0.6 g kg(-1) dw, respectively) and high concentration of OC (≈36 g kg(-1) dw). TN was negatively related to dry weight. Sediment mixing due to drastic changes in water level may have favoured the observed homogeneity of Barasona sediments affecting carbon, major ions and grain size. The high amount of OC deposited in Barasona sediment suggested that the adsorption of OC onto fine particles was more important than in boreal lakes. The rate of oxygen consumption by wet sediment ranged from 2.26 to 3.15 mg O2 m(-2) day(-1), values close to those compiled for Mediterranean running waters. PMID:26105704

  7. How does the spaceborne radar blind zone affect derived surface snowfall statistics in polar regions?

    NASA Astrophysics Data System (ADS)

    Maahn, Maximilian; Burgard, Clara; Crewell, Susanne; Gorodetskaya, Irina V.; Kneifel, Stefan; Lhermitte, Stef; Van Tricht, Kristof; Lipzig, Nicole P. M.

    2014-12-01

    Global statistics of snowfall are currently only available from the CloudSat satellite. But CloudSat cannot provide observations of clouds and precipitation within the so-called blind zone, which is caused by ground-clutter contamination of the CloudSat radar and covers the last 1200 m above land/ice surface. In this study, the impact of the blind zone of CloudSat on derived snowfall statistics in polar regions is investigated by analyzing three 12 month data sets recorded by ground-based Micro Rain Radar (MRR) at the Belgian Princess Elisabeth station in East Antarctica and at Ny-Ålesund and Longyearbyen in Svalbard, Norway. MRR radar reflectivity profiles are investigated in respect to vertical variability in the frequency distribution, changes in the number of observed snow events, and impacts on total precipitation. Results show that the blind zone leads to reflectivity being underestimated by up to 1 dB, the number of events being altered by ±5% and the precipitation amount being underestimated by 9 to 11 percentage points. Besides investigating a blind zone of 1200 m, the impacts of a reduced blind zone of 600 m are also analyzed. This analysis will help in assessing future missions with a smaller blind zone. The reduced blind zone leads to improved representation of mean reflectivity but does not improve the bias in event numbers and precipitation amount.

  8. Analysis of Microstructural Changes in the Heat-Affected Zone and Fusion Zone of a Fiber Laser Welded DP980 Steel

    NASA Astrophysics Data System (ADS)

    Zhang, Jianqi; Khan, Abdul; Ojo, Olanrewaju A.; Zhou, Norman; Chen, Daolun

    2015-08-01

    Dual phase (DP) steels are designed to consist of hard martensite dispersed in a relatively soft ferrite matrix, which offers a favorable combination of high strength with good deformability. Fiber laser welding (FLW) is becoming increasingly important for joining advanced materials due to its flexibility and deep penetration. In this study, the microstructure of a DP steel, DP980, welded by FLW technique was carefully analyzed. Gleeble thermo-mechanical simulation coupled with analytical transmission electron microscopy revealed that the FLW process produced significant microstructural changes in a narrow heat-affected zone (HAZ) and fusion zone (FZ), which can result in dramatic changes in mechanical properties. This is reflected in the micro-hardness profile obtained across the welded material. The salient phase transitions induced by the FLW, including the formation of new martensite grains in the upper-critical HAZ and FZ, are discussed.

  9. The sensitivity of mechanical properties of TFRS composites to variations in reaction zone size and properties. [Tungsten Fiber Reinforced Superalloys

    NASA Technical Reports Server (NTRS)

    Craddock, James N.; Hopkins, Dale A.; Petrasek, Donald W.; Brindley, Pamela K.

    1987-01-01

    The properties of tungsten fiber reinforced superalloys (TFRS) composites are calculated using a 3-component micromechanical model. The properties and size of the reaction zone are varied and the effect of these variations on the composite properties are studied. Results are presented in graphical and tabular form. Post-matrix yield behavior is examined in terms of the tangent modulus of the composite and measures of the effective strength of the lamina.

  10. How do different data logger sizes and attachment positions affect the diving behaviour of little penguins?

    NASA Astrophysics Data System (ADS)

    Ropert-Coudert, Yan; Knott, Nathan; Chiaradia, André; Kato, Akiko

    2007-02-01

    It is crucial in any bio-logging study to establish the potential effect that attachment of loggers may have on the animal. This ensures that the behaviour monitored by the loggers has a biological relevance, as well as for ethical reasons. Evaluation of the effects of externally attached loggers shows that they increase the drag of swimming animals and increase their energy expenditure. Nevertheless, little research has been done on the effects of size or position of such loggers. In this study, we tested whether the size (i.e. large: 4.9% versus small: 3.4% of the bird's frontal area) or the place of attachment (middle versus lower back) affected the diving behaviour of male and female little penguins ( Eudyptula minor). The positioning of the data logger on the middle or lower section of little penguins' back had little, if no effect, on the diving variables measured in this study. Size of the loggers, however, had strong effects. Birds with large loggers made shorter dives and reached shallower depths than those with small loggers. In addition, birds with large loggers made more dives probably to compensate for the extra cost of carrying a large logger. The measured variables also differed between the sexes, with males diving deeper and longer than females. Logger size had a sex-specific effect on the trip duration and descent speed, with males equipped with large loggers staying longer at sea than those with small loggers, and females with large loggers descending faster than those with small loggers. From our results, it appears that effects of logger position do not exist or are very small in comparison with the effects of logger size. The results of the current study indicate that the effects of size of loggers be evaluated more commonly in bio-logging research into the diving activity of free-ranging birds.

  11. Airborne endotoxin associated with particles of different sizes and affected by water content in handled straw.

    PubMed

    Madsen, A M; Nielsen, S H

    2010-07-01

    makes attempts to influence the endotoxin exposure a possibility. Water content in straw affected the concentration, exposure level and size distribution of airborne endotoxin. PMID:20362504

  12. Vein Controlled Index Mineral Crystal Size Distribution in Barrow's Metamorphic Zones, Glen Esk, Scotland

    NASA Astrophysics Data System (ADS)

    Lewerentz, A.; Skelton, A.; Linde, J. K.; Nilsson, J.; Möller, C.; Crill, P. M.; Spicuzza, M. J.

    2015-12-01

    The concept of index mineral based metamorphic zones was first introduced by George Barrow a little more than 100 years ago, and the Barrovian metamorphic zones are still today used as framework by metamorphic petrologists. Today the importance of metamorphic fluids for driving metamorphic reactions is widely recognised. Even so, a general view is that Barrovian metamorphism is solely controlled by pressure, temperature, and protolith composition. This study aims to establish if and how fluids control index mineral formation and distribution during Barrovian metamorphism. To do so, we use samples from Barrow's own type locality in Glen Esk, Southeast Scottish Highlands, and study possible relationships between veining and index mineral distribution. In addition to petrographic and textural observations and analyses, we also use whole rock chemistry, mineral chemistry, and oxygen isotope analyses. At low grade, in the chlorite zone and most of the biotite zone, no correlation between veining and index mineral distribution is seen. At higher grade, the index mineral abundance is shown to decrease away from veins in the garnet and staurolite zones. Pseudosection analysis show larger garnet stability fields in vein-adjacent rock. In addition, quartz abundance and oxygen isotope ratios of quartz coincidentally decrease, which we interpret as evidence for fluid-rock interaction. The kyanite zone shows a fairly homogenous kyanite distribution, but also indications of extensive fluid-rock interaction, such as high vein density and oxygen isotope ratios in equilibrium with the fluid. Based on our observations and the geochemical datasets, we conclude that fluid played a major role in the stabilisation and distribution of the Barrovian index minerals in Glen Esk, and that the fluid control was larger at higher metamorphic grades.

  13. Gephyrin expression and clustering affects the size of glutamatergic synaptic contacts

    PubMed Central

    Yu, Wendou; De Blas, Angel L.

    2009-01-01

    We have recently shown that disrupting the expression and postsynaptic clustering of gephyrin in cultured hippocampal pyramidal cells, by either gephyrin RNAi (RNA interference) or overexpression of a dominant negative gephyrin-EGFP fusion protein, leads to decreased number of postsynaptic gephyrin and GABAA receptor clusters and to reduced GABAergic innervation of these cells. On the other hand, increasing gephyrin expression led to a small increase in the number of gephyrin and GABAA receptor clusters and to little or no effect on GABAergic innervation. We are now reporting that altering gephyrin expression and clustering affects the size but not the density of glutamatergic synaptic contacts. Knocking down gephyrin with gephyrin RNAi, or preventing gephyrin clustering by overexpression of the dominant negative gephyrin-EGFP fusion protein, leads to larger postsynaptic PSD-95 clusters and larger presynaptic glutamatergic terminals. On the other hand, overexpression of gephyrin leads to slightly smaller PSD-95 clusters and presynaptic glutamatergic terminals. The change in size of PSD-95 clusters were accompanied by a parallel change in the size of NR2-NMDA receptor clusters. It is concluded that the levels of expression and clustering of gephyrin, a protein that concentrates at the postsynaptic complex of the inhibitory synapses, not only has homotypic effects on GABAergic synaptic contacts, but also has heterotypic effects on glutamatergic synaptic contacts. We are proposing that gephyrin is a counterpart of the postsynaptic glutamatergic scaffold protein PSD-95 in regulating the number and/or size of the excitatory and inhibitory synaptic contacts. PMID:18199120

  14. Population size and relatedness affect fitness of a self-incompatible invasive plant.

    PubMed

    Elam, Diane R; Ridley, Caroline E; Goodell, Karen; Ellstrand, Norman C

    2007-01-01

    One of the lingering paradoxes in invasion biology is how founder populations of an introduced species are able to overcome the limitations of small size and, in a "reversal of fortune," proliferate in a new habitat. The transition from colonist to invader is especially enigmatic for self-incompatible species, which must find a mate to reproduce. In small populations, the inability to find a mate can result in the Allee effect, a positive relationship between individual fitness and population size or density. Theoretically, the Allee effect should be common in founder populations of self-incompatible colonizing species and may account for the high rate of failed introductions, but little supporting evidence exists. We created a field experiment to test whether the Allee effect affects the maternal fitness of a self-incompatible invasive species, wild radish (Raphanus sativus). We created populations of varying size and relatedness. We measured maternal fitness in terms of both fruit set per flower and seed number per fruit. We found that both population size and the level of genetic relatedness among individuals influence maternal reproductive success. Our results explicitly define an ecological genetic obstacle faced by populations of an exotic species on its way to becoming invasive. Such a mechanistic understanding of the invasions of species that require a mate can and should be exploited for both controlling current outbreaks and reducing their frequency in the future. PMID:17197422

  15. Cotyledon damage affects seed number through final plant size in the annual grassland species Medicago lupulina

    PubMed Central

    Zhang, Shiting; Zhao, Chuan; Lamb, Eric G.

    2011-01-01

    Background and Aims The effects of cotyledon damage on seedling growth and survival are relatively well established, but little is known about the effects on aspects of plant fitness such as seed number and size. Here the direct and indirect mechanisms linking cotyledon damage and plant fitness in the annual species Medicago lupulina are examined. Methods Growth and reproductive traits, including mature plant size, time to first flowering, flower number, seed number and individual seed mass were monitored in M. lupulina plants when zero, one or two cotyledons were removed at 7 d old. Structural equation modelling (SEM) was used to examine the mechanisms linking cotyledon damage to seed number and seed mass. Key Results Cotyledon damage reduced seed number but not individual seed mass. The primary mechanism was a reduction in plant biomass with cotyledon damage that in turn reduced seed number primarily through a reduction in flower numbers. Although cotyledon damage delayed flower initiation, it had little effect on seed number. Individual seed mass was not affected by cotyledon removal, but there was a trade-off between seed number and seed mass. Conclusions It is shown how a network of indirect mechanisms link damage to cotyledons and fitness in M. lupulina. Cotyledon damage had strong direct effects on both plant size and flowering phenology, but an analysis of the causal relationships among plant traits and fitness components showed that a reduction in plant size associated with cotyledon damage was an important mechanism influencing fitness. PMID:21196450

  16. Brain size affects the behavioural response to predators in female guppies (Poecilia reticulata)

    PubMed Central

    van der Bijl, Wouter; Thyselius, Malin; Kotrschal, Alexander; Kolm, Niclas

    2015-01-01

    Large brains are thought to result from selection for cognitive benefits, but how enhanced cognition leads to increased fitness remains poorly understood. One explanation is that increased cognitive ability results in improved monitoring and assessment of predator threats. Here, we use male and female guppies (Poecilia reticulata), artificially selected for large and small brain size, to provide an experimental evaluation of this hypothesis. We examined their behavioural response as singletons, pairs or shoals of four towards a model predator. Large-brained females, but not males, spent less time performing predator inspections, an inherently risky behaviour. Video analysis revealed that large-brained females were further away from the model predator when in pairs but that they habituated quickly towards the model when in shoals of four. Males stayed further away from the predator model than females but again we found no brain size effect in males. We conclude that differences in brain size affect the female predator response. Large-brained females might be able to assess risk better or need less sensory information to reach an accurate conclusion. Our results provide experimental support for the general idea that predation pressure is likely to be important for the evolution of brain size in prey species. PMID:26203003

  17. Brain size affects the behavioural response to predators in female guppies (Poecilia reticulata).

    PubMed

    van der Bijl, Wouter; Thyselius, Malin; Kotrschal, Alexander; Kolm, Niclas

    2015-08-01

    Large brains are thought to result from selection for cognitive benefits, but how enhanced cognition leads to increased fitness remains poorly understood. One explanation is that increased cognitive ability results in improved monitoring and assessment of predator threats. Here, we use male and female guppies (Poecilia reticulata), artificially selected for large and small brain size, to provide an experimental evaluation of this hypothesis. We examined their behavioural response as singletons, pairs or shoals of four towards a model predator. Large-brained females, but not males, spent less time performing predator inspections, an inherently risky behaviour. Video analysis revealed that large-brained females were further away from the model predator when in pairs but that they habituated quickly towards the model when in shoals of four. Males stayed further away from the predator model than females but again we found no brain size effect in males. We conclude that differences in brain size affect the female predator response. Large-brained females might be able to assess risk better or need less sensory information to reach an accurate conclusion. Our results provide experimental support for the general idea that predation pressure is likely to be important for the evolution of brain size in prey species. PMID:26203003

  18. Animal Slurry Acidification Affects Particle Size Distribution and Improves Separation Efficiency.

    PubMed

    Regueiro, I; Pociask, M; Coutinho, J; Fangueiro, D

    2016-05-01

    Solid-liquid separation is performed to improve slurry management, and acidification of the slurry is used to reduce ammonia emissions. Acidification is known to affect slurry characteristics, and we hypothesized that it may affect mechanical separation. Our objective in this study was to assess the effects of slurry acidification on particle size distribution and separation efficiency. Two types of slurry, aged pig and fresh dairy, and two different acidification additives, sulfuric acid and aluminum sulfate (alum), were studied. We found that acidification with sulfuric acid promoted phosphorus (P) solubilization for both slurries, but no change was observed with alum. More ammonium was found in the acidified dairy slurry compared with raw dairy slurry, but no difference was found in aged pig slurry. Acidification before separation increased the proportion of the solid fraction in the slurries, and the effect was significantly higher with alum. When alum was used to acidify the slurries, the proportion of particles larger than 100 μm increased significantly, as did the P concentration in this particle size range. The efficiency of P separation increased markedly in both slurries when alum was used, with the removal to the solid fraction of the dairy slurry being almost complete (90%). Because the priority in mechanical separation is to increase the P content in the solid fraction, the use of alum before centrifugation may be the most suitable option for enhancing its nutrient content. We conclude that separation efficiency and particle size distribution are significantly affected by acidification, but the extent of the effects depends on slurry type and on the type of additive used for acidification. PMID:27136179

  19. Size, but not experience, affects the ontogeny of constriction performance in ball pythons (Python regius).

    PubMed

    Penning, David A; Dartez, Schuyler F

    2016-03-01

    Constriction is a prey-immobilization technique used by many snakes and is hypothesized to have been important to the evolution and diversification of snakes. However, very few studies have examined the factors that affect constriction performance. We investigated constriction performance in ball pythons (Python regius) by evaluating how peak constriction pressure is affected by snake size, sex, and experience. In one experiment, we tested the ontogenetic scaling of constriction performance and found that snake diameter was the only significant factor determining peak constriction pressure. The number of loops applied in a coil and its interaction with snake diameter did not significantly affect constriction performance. Constriction performance in ball pythons scaled differently than in other snakes that have been studied, and medium to large ball pythons are capable of exerting significantly higher pressures than those shown to cause circulatory arrest in prey. In a second experiment, we tested the effects of experience on constriction performance in hatchling ball pythons over 10 feeding events. By allowing snakes in one test group to gain constriction experience, and manually feeding snakes under sedation in another test group, we showed that experience did not affect constriction performance. During their final (10th) feedings, all pythons constricted similarly and with sufficiently high pressures to kill prey rapidly. At the end of the 10 feeding trials, snakes that were allowed to constrict were significantly smaller than their non-constricting counterparts. J. Exp. Zool. 9999A:XX-XX, 2016. © 2016 Wiley Periodicals, Inc. PMID:26847931

  20. Heat-affected zone toughness of a TMCP steel designed for low-temperature applications

    SciTech Connect

    Gianetto, J.A.; Braid, J.E.M.; Bowker, J.T.; Tyson, W.R.

    1997-05-01

    The objective of this investigation was to provide a detailed evaluation of the heat-affected zone (HAZ) toughness of a high-strength TMCP steel designed for low-temperature applications. The results form both Charpy-vee notch (CVN) and crack-tip-opening displacement (CTOD) tests conducted on two straight-walled narrow groove welds, produced at energy inputs of 1.5 and 3.0 kJ/mm, show that significantly lower toughness was exhibited by the grain-coarsened HAZ (GCHAZ) compared with the intercritical HAZ (ICHAZ) region. This is explained based on the overall GCHAZ microstructure, and the initiation mechanism which caused failure. For the particular TMCP steel investigated in this study very good ICHAZ toughness properties were recorded using both HAZ Charpy and CTOD tests. In general, this was attributable to the low hardness, relatively fine ferrite microstructure, and the formation of secondary microphases that were not overly detrimental to the toughness. The lower-bound GCHAZ CTOD results obtained for both welds (KAW-L and KAW-H) did not meet the targeted requirement of {delta} = 0.07 mm at {minus}50 C. It was found in both welds that low CTOD toughness was associated with the initiation of fracture from nonmetallic inclusions, which were complex oxides containing Ce, La, and S. The sites were located in the subcritical GCHAZ (SCGHAZ) region in the case of the 1.5 kJ/mm weld and in the GCHAZ for the 3.0 kJ/mm weld. Some variation in CVN toughness was observed at different through-thickness locations. Toughness was lowest for the GCHAZ of the weld deposited at 3.0 kJ/mm and was related to the proportion of GCHAZ being samples, which was {approximately} 55% for the bottom compared to 25--30% for that of the top location. Recommendations are proposed on the preferred practices and criteria that should be used in establishing guidelines and specifications for evaluating the HAZ toughness of candidate steels for construction of Arctic class ships.

  1. Analysis of heat-affected zone phase transformations using in situ spatially resolved x-ray diffraction with synchrotron radiation

    SciTech Connect

    Elmer, J.W.; Wong, J.; Froeba, M.; Waide, P.A.; Larson, E.M.

    1996-03-01

    Spatially resolved X-ray diffraction (SRXRD) consists of producing a submillimeter size X-ray beam from an intense synchrotron radiation source to perform real-time diffraction measurements on solid materials. This technique was used int his study to investigate the crystal phases surrounding a liquid weld pool in commercial purity titanium and to determine the location of the phase boundary separating the high-temperature body-centered-cubic (bcc) {beta} phase from the low-temperature hexagonal-close-packed (hcp) {alpha} phase. The experiments were carried out at the Stanford Synchrotron Radiation Laboratory (SSRL) using a 0.25 x 0.50 mm X-ray probe that could be positioned with 10-{micro}m precision on the surface of a quasistationary gas tungsten arc weld (GTAW). The SRXRD results showed characteristic hcp, bcc, and liquid diffraction patterns at various points along the sample, starting from the base metal through the heat-affected zone (HAZ) and into the weld pool, respectively. Analyses of the SRXRD data show the coexistence of bcc and hcp phases in the partially transformed (outer) region of the HAZ and single-phase bcc in the fully transformed (inner) region of the HAZ. Postweld metallographic examinations of the HAZ, combined with a conduction-based thermal model of the weld, were correlated with the SRXRD results. Finally, analysis of the diffraction intensities of the hcp and bcc phases was performed on the SRXRD data to provide additional information about the microstructural conditions that may exist in the HAZ at temperature during welding. This work represents the first direct in situ mapping of phase boundaries in fusion welds.

  2. Species-abundance--seed-size patterns within a plant community affected by grazing disturbance.

    PubMed

    Wu, Gao-lin; Shang, Zhan-huan; Zhu, Yuan-jun; Ding, Lu-ming; Wang, Dong

    2015-04-01

    Seed size has been advanced as a key factor that influences the dynamics of plant communities, but there are few empirical or theoretical predictions of how community dynamics progress based on seed size patterns. Information on the abundance of adults, seedlings, soil seed banks, seed rains, and the seed mass of 96 species was collected in alpine meadows of the Qinghai-Tibetan Plateau (China), which had different levels of grazing disturbance. The relationships between seed-mass-abundance patterns for adults, seedlings, the soil seed bank, and seed rain in the plant community were evaluated using regression models. Results showed that grazing levels affected the relationship between seed size and abundance properties of adult species, seedlings, and the soil seed bank, suggesting that there is a shift in seed-size--species-abundance relationships as a response to the grazing gradient. Grazing had no effect on the pattern of seed-size-seed-rain-abundance at four grazing levels. Grazing also had little effect on the pattern of seed-size--species-abundance and pattern of seed-size--soil-seed-bank-abundance in meadows with no grazing, light grazing, and moderate grazing), but there was a significant negative effect in meadows with heavy grazing. Grazing had little effect on the pattern of seed-size--seedling-abundance with no grazing, but had significant negative effects with light, moderate, and heavy grazing, and the |r| values increased with grazing levels. This indicated that increasing grazing pressure enhanced the advantage of smaller-seeded species in terms of the abundances of adult species, seedlings, and soil seed banks, whereas only the light grazing level promoted the seed rain abundance of larger-seeded species in the plant communities. This study suggests that grazing disturbances are favorable for increasing the species abundance for smaller-seeded species but not for the larger-seeded species in an alpine meadow community. Hence, there is a clear

  3. Changes in Arctic Sea Ice Floe Size Distribution in the Marginal Ice Zone in a Thickness and Floe Size Distribution Model

    NASA Astrophysics Data System (ADS)

    Zhang, J.; Stern, H. L., III; Hwang, P. B.; Schweiger, A. J. B.; Stark, M.; Steele, M.

    2015-12-01

    To better describe the state of sea ice in the marginal ice zone (MIZ) with floes of varying thicknesses and sizes, both an ice thickness distribution (ITD) and a floe size distribution (FSD) are needed. We have developed a FSD theory [Zhang et al., 2015] that is coupled to the ITD theory of Thorndike et al. [1975] in order to explicitly simulate the evolution of FSD and ITD jointly. The FSD theory includes a FSD function and a FSD conservation equation in parallel with the ITD equation. The FSD equation takes into account changes in FSD due to ice advection, thermodynamic growth, and lateral melting. It also includes changes in FSD because of mechanical redistribution of floe size due to ice opening, ridging and, particularly, ice fragmentation induced by stochastic ocean surface waves. The floe size redistribution due to ice fragmentation is based on the assumption that wave-induced breakup is a random process such that when an ice floe is broken, floes of any smaller sizes have an equal opportunity to form, without being either favored or excluded. It is also based on the assumption that floes of larger sizes are easier to break because they are subject to larger flexure-induced stresses and strains than smaller floes that are easier to ride with waves with little bending; larger floes also have higher areal coverages and therefore higher probabilities to break. These assumptions with corresponding formulations ensure that the simulated FSD follows a power law as observed by satellites and airborne surveys. The FSD theory has been tested in the Pan-arctic Ice/Ocean Modeling and Assimilation System (PIOMAS). The existing PIOMAS has 12 categories each for ice thickness, ice enthalpy, and snow depth. With the implementation of the FSD theory, PIOMAS is able to represent 12 categories of floe sizes ranging from 0.1 m to ~3000 m. It is found that the simulated 12-category FSD agrees reasonably well with FSD derived from SAR and MODIS images. In this study, we will

  4. Hydroxyapatite crystallinity does not affect the repair of critical size bone defects

    PubMed Central

    CONZ, Marcio Baltazar; GRANJEIRO, José Mauro; SOARES, Gloria de Almeida

    2011-01-01

    Objective The physicochemical properties of hydroxyapatite (HA) granules were observed to affect the biological behavior of graft materials. The aim of this work was to analyze the tissue response of two HA granules with different crystallinity and Ca/P ratio in vivo. Material and Methods The HA granules were produced in the Biomaterials Laboratory (COPPE/UFRJ). The testing materials were HA granules presenting a Ca/P molar ratio of 1.60 and 28% crystallinity (HA-1), and a Ca/P molar ratio of 1.67 and 70% crystallinity (HA-2). Both HAs were implanted into a critical-size calvaria rat defects. Results To note, in the control group, the bone defects were filled with blood clot only. Descriptive and histomorphometric analyses after 1, 3, and 6 months postoperatively showed mild inflammatory infiltrate, mainly comprising macrophage-like and multinucleated giant cells, and an increase in the volume density of the fibrous tissues (p<0.05), which was in contrast to the similar volume density of the newly formed bone and biomaterials in relation to the control group. Conclusion Thus, we concluded that HA-1 and HA-2 are biocompatible and non-degradable, and that crystallinity does not affect bone repair of critical size defects. PMID:21655775

  5. Atrazine exposure affects longevity, development time and body size in Drosophila melanogaster.

    PubMed

    Marcus, Sarah R; Fiumera, Anthony C

    2016-01-01

    Atrazine is the one of the most widely used herbicides in the United States and non-target organisms may encounter it in the environment. Atrazine is known to affect male reproduction in both vertebrates and invertebrates but less is known about its effects on other fitness traits. Here we assessed the effects of five different chronic exposure levels on a variety of fitness traits in Drosophila melanogaster. We measured male and female longevity, development time, proportion pupated, proportion emerged, body size, female mating rate, fertility and fecundity. Atrazine exposure decreased the proportion pupated, the proportion emerged and adult survival. Development time was also affected by atrazine and exposed flies pupated and emerged earlier than controls. Although development time was accelerated, body size was actually larger in some of the exposures. Atrazine exposure had no effect on female mating rate and the effects on female fertility and fecundity were only observed in one of the two independent experimental blocks. Many of the traits showed non-monotonic dose response curves, where the intermediate concentrations showed the largest effects. Overall this study shows that atrazine influences a variety of life history traits in the model genetic system, D. melanogaster, and future studies should aim to identify the molecular mechanisms of toxicity. PMID:27317622

  6. Factors Affecting Pathogen Survival in Finished Dairy Compost with Different Particle Sizes Under Greenhouse Conditions.

    PubMed

    Diao, Junshu; Chen, Zhao; Gong, Chao; Jiang, Xiuping

    2015-09-01

    This study investigated the survival of Escherichia coli O157:H7 and Salmonella Typhimurium in finished dairy compost with different particle sizes during storage as affected by moisture content and temperature under greenhouse conditions. The mixture of E. coli O157:H7 and S. Typhimurium strains was inoculated into the finished composts with moisture contents of 20, 30, and 40%, separately. The finished compost samples were then sieved into 3 different particle sizes (>1000, 500-1000, and <500 μm) and stored under greenhouse conditions. For compost samples with moisture contents of 20 and 30%, the average Salmonella reductions in compost samples with particle sizes of >1000, 500-1000, and <500 μm were 2.15, 2.27, and 2.47 log colony-forming units (CFU) g(-1) within 5 days of storage in summer, respectively, as compared with 1.60, 2.03, and 2.26 log CFU g(-1) in late fall, respectively, and 2.61, 3.33, and 3.67 log CFU g(-1) in winter, respectively. The average E. coli O157:H7 reductions in compost samples with particle sizes of >1000, 500-1000, and <500 μm were 1.98, 2.30, and 2.54 log CFU g(-1) within 5 days of storage in summer, respectively, as compared with 1.70, 2.56, and 2.90 log CFU g(-1) in winter, respectively. Our results revealed that both Salmonella and E. coli O157:H7 in compost samples with larger particle size survived better than those with smaller particle sizes, and the initial rapid moisture loss in compost may contribute to the fast inactivation of pathogens in the finished compost. For the same season, the pathogens in the compost samples with the same particle size survived much better at the initial moisture content of 20% compared to 40%. PMID:26153914

  7. Offspring size at weaning affects survival to recruitment and reproductive performance of primiparous gray seals

    PubMed Central

    Bowen, William D; den Heyer, Cornelia E; McMillan, Jim I; Iverson, Sara J

    2015-01-01

    Offspring size affects survival and subsequent reproduction in many organisms. However, studies of offspring size in large mammals are often limited to effects on juveniles because of the difficulty of following individuals to maturity. We used data from a long-term study of individually marked gray seals (Halichoerus grypus; Fabricius, 1791) to test the hypothesis that larger offspring have higher survival to recruitment and are larger and more successful primiparous mothers than smaller offspring. Between 1998 and 2002, 1182 newly weaned female pups were branded with unique permanent marks on Sable Island, Canada. Each year through 2012, all branded females returning to the breeding colony were identified in weekly censuses and a subset were captured and measured. Females that survived were significantly longer offspring than those not sighted, indicating size-selective mortality between weaning and recruitment. The probability of female survival to recruitment varied among cohorts and increased nonlinearly with body mass at weaning. Beyond 51.5 kg (mean population weaning mass) weaning mass did not influence the probability of survival. The probability of female survival to recruitment increased monotonically with body length at weaning. Body length at primiparity was positively related to her body length and mass at weaning. Three-day postpartum mass (proxy for birth mass) of firstborn pups was also positively related to body length of females when they were weaned. However, females that were longer or heavier when they were weaned did not wean heavier firstborn offspring. PMID:25897381

  8. Offspring size at weaning affects survival to recruitment and reproductive performance of primiparous gray seals.

    PubMed

    Bowen, William D; den Heyer, Cornelia E; McMillan, Jim I; Iverson, Sara J

    2015-04-01

    Offspring size affects survival and subsequent reproduction in many organisms. However, studies of offspring size in large mammals are often limited to effects on juveniles because of the difficulty of following individuals to maturity. We used data from a long-term study of individually marked gray seals (Halichoerus grypus; Fabricius, 1791) to test the hypothesis that larger offspring have higher survival to recruitment and are larger and more successful primiparous mothers than smaller offspring. Between 1998 and 2002, 1182 newly weaned female pups were branded with unique permanent marks on Sable Island, Canada. Each year through 2012, all branded females returning to the breeding colony were identified in weekly censuses and a subset were captured and measured. Females that survived were significantly longer offspring than those not sighted, indicating size-selective mortality between weaning and recruitment. The probability of female survival to recruitment varied among cohorts and increased nonlinearly with body mass at weaning. Beyond 51.5 kg (mean population weaning mass) weaning mass did not influence the probability of survival. The probability of female survival to recruitment increased monotonically with body length at weaning. Body length at primiparity was positively related to her body length and mass at weaning. Three-day postpartum mass (proxy for birth mass) of firstborn pups was also positively related to body length of females when they were weaned. However, females that were longer or heavier when they were weaned did not wean heavier firstborn offspring. PMID:25897381

  9. Structure and ductility of the heat-affected zone of welded joints of a high-strength steel

    NASA Astrophysics Data System (ADS)

    Tabatchikova, T. I.; Nosov, A. D.; Goncharov, S. N.; Gudnev, N. Z.; Delgado Reina, S. Yu.; Yakovleva, I. L.

    2014-12-01

    Methods of optical microscopy and scanning and transmission electron microscopy have been used to study the structure of welded joints of a high-strength structural steel with different types of the weld metal. The impact toughness of the heat-affected zone (HAZ) has been determined at temperatures of +20 and -40°C. Based on the fractograph investigations of the character of the fracture of the welded joints after tests for impact bending, the regions that are the most dangerous for crack initiation have been determined. Structural factors that affect the brittleness of the near-weld zone of welded joints with the austenite metal of the weld are indicated, including the existence of an austenite-bainite structure and coarse carbides, as well as the specific distribution of hydrogen.

  10. Climate controls how ecosystems size the root zone storage capacity at catchment scale

    NASA Astrophysics Data System (ADS)

    Gao, H.; Hrachowitz, M.; Schymanski, S. J.; Fenicia, F.; Sriwongsitanon, N.; Savenije, H. H. G.

    2014-11-01

    The root zone moisture storage capacity (SR) of terrestrial ecosystems is a buffer providing vegetation continuous access to water and a critical factor controlling land-atmospheric moisture exchange, hydrological response, and biogeochemical processes. However, it is impossible to observe directly at catchment scale. Here, using data from 300 diverse catchments, it was tested that, treating the root zone as a reservoir, the mass curve technique (MCT), an engineering method for reservoir design, can be used to estimate catchment-scale SR from effective rainfall and plant transpiration. Supporting the initial hypothesis, it was found that MCT-derived SR coincided with model-derived estimates. These estimates of parameter SR can be used to constrain hydrological, climate, and land surface models. Further, the study provides evidence that ecosystems dynamically design their root systems to bridge droughts with return periods of 10-40 years, controlled by climate and linked to aridity index, inter-storm duration, seasonality, and runoff ratio.

  11. A SUPER-EARTH-SIZED PLANET ORBITING IN OR NEAR THE HABITABLE ZONE AROUND A SUN-LIKE STAR

    SciTech Connect

    Barclay, Thomas; Burke, Christopher J.; Howell, Steve B.; Rowe, Jason F.; Huber, Daniel; Jenkins, Jon M.; Quintana, Elisa V.; Still, Martin; Twicken, Joseph D.; Bryson, Stephen T.; Borucki, William J.; Caldwell, Douglas A.; Clarke, Bruce D.; Christiansen, Jessie L; Coughlin, Jeffrey L.; Ciardi, David; Fischer, Debra A.; and others

    2013-05-10

    We present the discovery of a super-Earth-sized planet in or near the habitable zone of a Sun-like star. The host is Kepler-69, a 13.7 mag G4V-type star. We detect two periodic sets of transit signals in the 3-year flux time series of Kepler-69, obtained with the Kepler spacecraft. Using the very high precision Kepler photometry, and follow-up observations, our confidence that these signals represent planetary transits is >99.3%. The inner planet, Kepler-69b, has a radius of 2.24{sup +0.44}{sub -0.29} R{sub Circled-Plus} and orbits the host star every 13.7 days. The outer planet, Kepler-69c, is a super-Earth-sized object with a radius of 1.7{sup +0.34}{sub -0.23} R{sub Circled-Plus} and an orbital period of 242.5 days. Assuming an Earth-like Bond albedo, Kepler-69c has an equilibrium temperature of 299 {+-} 19 K, which places the planet close to the habitable zone around the host star. This is the smallest planet found by Kepler to be orbiting in or near the habitable zone of a Sun-like star and represents an important step on the path to finding the first true Earth analog.

  12. Plastic zone size and crack tip opening displacement of a Dugdale crack interacting with a coated circular inclusion

    NASA Astrophysics Data System (ADS)

    Hoh, H. J.; Xiao, Z. M.; Luo, J.

    2010-09-01

    An analytical investigation on the plastic zone size of a crack near a coated circular inclusion under three different loading conditions of uniaxial tension, uniform tension and pure shear was carried out. Both the crack and coated circular inclusion are embedded in an infinite matrix, with the crack oriented along the radial direction of the inclusion. In the solution procedure, the crack is simulated as a continuous distribution of edge dislocations. With the Dugdale model of small-scale yielding [J. Mech. Phys. Solids 8 (1960) p. 100], two thin strips of yielded plastic zones are introduced at both crack tips. Using the solution for a coated circular inclusion interacting with a single dislocation as the Green's function, the physical problem is formulated into a set of singular integral equations. Using the method of Erdogan and Gupta [Q. J. Appl. Math. 29 (1972) p. 525] and iterative numerical procedures, the singular integral equations are solved numerically for the plastic zone sizes and crack tip opening displacement.

  13. Pore size controls on the base of the methane hydrate stability zone in the Kumano Basin, offshore Japan

    NASA Astrophysics Data System (ADS)

    Daigle, Hugh; Dugan, Brandon

    2014-11-01

    The base of the methane hydrate stability zone (MHSZ) in the Kumano Basin, offshore Japan, is marked by a bottom-simulating reflection (BSR) on seismic data. At Integrated Ocean Drilling Program Site C0002, which penetrates this BSR, the in situ temperature profile combined with bulk seawater methane equilibrium conditions suggest that the base of the MHSZ is 428 m below seafloor (bsf), which is 28 m deeper than the observed BSR (400 m bsf). We found that submicron pore sizes determined by mercury injection capillary pressure are sufficiently small to cause 64% of the observed uplift of the base of the MHSZ by the Gibbs-Thomson effect. This is the most thorough characterization of pore sizes within the MHSZ performed to date and illustrates the extent to which pore size can influence MHSZ thickness. Our results demonstrate the importance of considering lithology and pore structure when assessing methane hydrate stability conditions in marine sediments.

  14. Characterization of hole circularity and heat affected zone in pulsed CO2 laser drilling of alumina ceramics

    NASA Astrophysics Data System (ADS)

    Bharatish, A.; Narasimha Murthy, H. N.; Anand, B.; Madhusoodana, C. D.; Praveena, G. S.; Krishna, M.

    2013-12-01

    Circularity of drilled hole at the entry and exit, heat affected zone and taper are important attributes which influence the quality of a drilled hole in laser drilling. This paper examines the effect of laser parameters on the quality of drilled holes in Alumina ceramics which are widely used in microelectronic devices, based on orthogonal array experimentation and response surface methodology. Both entrance and exit circularities were significantly influenced by hole diameter and laser power. Heat affected zone was influenced by frequency. Taper was also significantly influenced by laser power. Response surface model predicted nominal entrance circularity at 2.5 kHz, 240 W, 2.5 mm/s, 1 mm hole, exit circularity and taper at 7.5 kHz, 240 W, 4.5 mm/s, and 1 mm hole. The model predicted lowest heat affected zone at 7.5 kHz, 240 W, 2.5 mm/s, and 1 mm. Multiobjective optimization achieved using both response surface model and gray relational analysis indicated that all the four quality parameters are optimized at 7.5 kHz, 240 W, 3.85 mm/s and 1 mm.

  15. Nano-sized polystyrene affects feeding, behavior and physiology of brine shrimp Artemia franciscana larvae.

    PubMed

    Bergami, Elisa; Bocci, Elena; Vannuccini, Maria Luisa; Monopoli, Marco; Salvati, Anna; Dawson, Kenneth A; Corsi, Ilaria

    2016-01-01

    Nano-sized polymers as polystyrene (PS) constitute one of the main challenges for marine ecosystems, since they can distribute along the whole water column affecting planktonic species and consequently disrupting the energy flow of marine ecosystems. Nowadays very little knowledge is available on the impact of nano-sized plastics on marine organisms. Therefore, the present study aims to evaluate the effects of 40nm anionic carboxylated (PS-COOH) and 50nm cationic amino (PS-NH2) polystyrene nanoparticles (PS NPs) on brine shrimp Artemia franciscana larvae. No signs of mortality were observed at 48h of exposure for both PS NPs at naplius stage but several sub-lethal effects were evident. PS-COOH (5-100μg/ml) resulted massively sequestered inside the gut lumen of larvae (48h) probably limiting food intake. Some of them were lately excreted as fecal pellets but not a full release was observed. Likewise, PS-NH2 (5-100µg/ml) accumulated in larvae (48h) but also adsorbed at the surface of sensorial antennules and appendages probably hampering larvae motility. In addition, larvae exposed to PS-NH2 undergo multiple molting events during 48h of exposure compared to controls. The activation of a defense mechanism based on a physiological process able to release toxic cationic NPs (PS-NH2) from the body can be hypothesized. The general observed accumulation of PS NPs within the gut during the 48h of exposure indicates a continuous bioavailability of nano-sized PS for planktonic species as well as a potential transfer along the trophic web. Therefore, nano-sized PS might be able to impair food uptake (feeding), behavior (motility) and physiology (multiple molting) of brine shrimp larvae with consequences not only at organism and population level but on the overall ecosystem based on the key role of zooplankton on marine food webs. PMID:26422775

  16. The Affective Establishment and Maintenance of Vygotsky's Zone of Proximal Development

    ERIC Educational Resources Information Center

    Levykh, Michael G.

    2008-01-01

    Many recent articles, research papers, and conference presentations about Lev Vygotsky's zone of proximal development (ZPD) emphasize the "extended" version of the ZPD that reflects human emotions and desires. In this essay, Michael G. Levykh expands on the extant literature on the ZPD through developing several new ideas. First, he maintains that…

  17. Mineralogical constraint for metamorphic conditions in a shear zone affecting the Archean Ngoulemakong tonalite, Congo craton (Southern Cameroon) and retentivity of U-Pb SHRIMP zircon dates

    NASA Astrophysics Data System (ADS)

    Tchameni, R.; Lerouge, C.; Penaye, J.; Cocherie, A.; Milesi, J. P.; Toteu, S. F.; Nsifa, N. E.

    2010-08-01

    In the Ngoulemakong region of the Ntem unit (South Cameroon), tonalite crops out as intrusions of various sizes cross-cutting the charnockite suite. Both of these granitoids are affected by NE-SW and WNW-ESE sinistral and dextral shear zones. Tonalite in the WNW-ESE shear zone are deformed and shows metamorphic assemblages represented by quartz-microcline-biotite-garnet-plagioclase-scapolite-fluoro-apatite and chlorite-sulfides-epidote-muscovite-quartz-calcite not recorded by the undeformed rocks outside it. These mineralogical assemblages provide evidence of decreasing pressure-temperature conditions from granulite-amphibolite-facies in the moderate deformed part to greenschist-facies in the central part of the shear plane. The higher fluid (H 2O, CO 2, S, F, Cl, K, and Na) activities and high-grade recrystallizations recorded in the shear zone favour a Pb loss hypothesis in the zircons. U-Pb SHRIMP zircon dating yield an emplacement age of 2865 ± 4 Ma for the tonalite but does not permit the determination of the age of the high-grade event responsible for the Pb loss. These results provide evidence of the retentivity of U-Pb zircon dates under high grade conditions.

  18. Lithospheric Thermal Structure: One of Factors Affecting the Depth of the Seismogenic Zone

    NASA Astrophysics Data System (ADS)

    Tanaka, A.

    2008-12-01

    Evidence that the base of the crustal seismogenic zone may be critically dependent on temperature has been bolstered for more than three decades. This paper addresses and reviews several topics related to relationship between lithospheric thermal regime and depth extent of seismicity. The base of the seismogenic crustal zone correlates with surface heat flow in most intraplate seismic areas of the world [e.g., Kobayshi, 1976; Sibson, 1982]. Compilation of previous studies shows that temperatures at the base of seismogenic zone appear to be distributed from about 250°C to 450°C over a large depth interval, 5-30 km, at different tectonic settings [e.g., Tanaka, 2008]. It supports that temperature is one of factors governing the focal depth. Variations in lithology, slip rate, pore pressure, and focal mechanism may account for the temperature difference. Inverse relationship between the base of the seismogenic crustal zone and surface heat flow is obvious, however this relationship is shown at geographically restricted area due to uneven data distribution. In order to overcome this spatial limitation, determination of the basal depth of magnetic layer, Curie point depth (Zb), based on spectrum analysis of magnetic anomaly data was applied to estimate regional thermal structure. This analysis is still controversial and Zb does not necessarily represent an isotherm, however, previous studies suggested that there was an inverse correlation between Zb and heat-flow measurements. Recently, the correlation between Zb and the base of the seismogenic crustal zone has been shown at Japan [Tanaka and Ishikawa, 2005] and California [Ross et al., 2006]. Correlations between them in both regions are good, however each region has own cluster; Zb of California region are significantly deeper than those of Japan. The lithological difference may cause the cluster shift between Japan and California.

  19. Dynamics of Particle Size Distribution in Slide-Hold Tests on Laboratory Gouge Zones

    NASA Astrophysics Data System (ADS)

    Muhuri, S. K.; Dewers, T. A.; Scott, T. E.

    2001-12-01

    Slide-hold tests using triaxially-loaded precut forcing blocks and artificial gouge examine contrasts in gouge particle size dynamics during frictional sliding and annealing or healing stages. A series of room-dry sliding experiments were conducted to various shear strains using dry gypsum gouge in between precut steel forcing members. A separate series of experiments saturated with distilled water was conducted at a pore pressure of 6.9 MPa (effective pressure of 13.8 MPa identical to the dry tests). The latter experiments were taken to a constant shear strain but were held under shear loading for various lengths of time (0.01-10 hours) after slip. Pore-volume change was monitored during hold periods. Particle size distribution (PSD) of gouge was measured using a laser particle size analyzer with a measurement range of 0.4-2000 microns. Stress-strain behavior for both dry and wet tests revealed multiple stress drops or stick-slip events and were similar suggesting no marked strengthening or weakening effect due to presence of water over the time scale of sliding. Gouge PSD's were fit to a log-normal distribution function and then analyzed in terms of the moments of mass-size distributions. The best log-normal fits were obtained in the coarser fraction of the gouge (larger than peak size). PSD means decreased with shear while higher moments such as skewness increased with shear. Particle number-size relationships computed from the mass-size distributions revealed a fractal nature of the gouge with excellent fits obtained for fine and intermediate fractions (smaller than peak size). A fractal dimension (D) around 2.6 consistent with previous work on both natural and experimental fault gouge was obtained. There appears to be a correlation between D and the amount of shear strain and an inverse relationship between D and the maximum particle size. Empirical distributions such as the Weibull, Rosin-Rammler distribution functions and others provide good approximations

  20. Dissolved barium behavior in Louisiana Shelf waters affected by the Mississippi/Atchafalaya River mixing zone

    NASA Astrophysics Data System (ADS)

    Joung, DongJoo; Shiller, Alan M.

    2014-09-01

    In order to better understand the constraints on the use of barium as a coastal paleo-freshwater tracer, we surveyed the dissolved Ba distribution in Louisiana Shelf waters, including the Mississippi (MR) and Atchafalaya (AR) River plumes, during May and November 2008, and June/July 2009, which represent high, low and intermediate river discharges, respectively. Dissolved Ba was found dominantly in the <0.02 μm fraction, with no significant contribution from the 0.02-0.45 μm colloidal size fraction. Although apparent non-conservative surface water Ba behavior was observed during all three sampling periods, there were significant differences among the distribution patterns. River-seawater mixing experiments were supportive of substantial desorptive Ba addition only during the high discharge survey. At other times, input of Ba-enriched shelf bottom water as well as river endmember variability contributed to the apparent non-conservative behavior. During at least two of our surveys (high and intermediate river discharge), shelf bottom waters were significantly enriched in dissolved Ba relative to surface waters. While the cause of this enrichment (e.g., submarine groundwater discharge, dissolution/diffusion from the sediment, and/or an anthropogenic source such as drilling muds) could not be determined, we did observe that bottom Ba enrichment correlated with diminishing dissolved oxygen during summertime shelf bottom water hypoxia. Another interesting observation was Ba depletion in some high-salinity surface waters associated with a diatom bloom during June/July 2009. In addition, different Ba concentrations in the MR and AR appear related to inputs to the AR from the Red River as well as from the wetlands in the Atchafalaya River Basin. Overall, our study of the Ba distribution in Louisiana Shelf waters implies that the seasonal variation of the surface water Ba-salinity relationship could lead to a considerable uncertainty in salinity prediction when using Ba as

  1. Climate controls how ecosystems size the root zone storage capacity at catchment scale

    NASA Astrophysics Data System (ADS)

    Gao, Hongkai; Hrachowitz, Markus; Schymanski, Stan; Fenicia, Fabrizio; Sriwongsitanon, Nutchanart; Savenije, Hubert

    2015-04-01

    The root zone moisture storage capacity (SR) of terrestrial ecosystems is a buffer providing vegetation continuous access to water and a critical factor controlling land-atmospheric moisture exchange, hydrological response and biogeochemical processes. However, it is impossible to observe directly at catchment scale. Here, using data from 300 diverse catchments, it was tested that, treating the root zone as a reservoir, the mass curve technique (MCT), an engineering method for reservoir design, can be used to estimate catchment-scale SR from effective rainfall and plant transpiration. Supporting the initial hypothesis, it was found that MCT-derived SR coincided with model-derived estimates. These estimates of parameter SR can be used to constrain hydrological, climate and land surface models. Further, the study provides evidence that ecosystems dynamically design their root systems to bridge droughts with return periods of 10-40 years, controlled by climate and linked to aridity index, inter-storm duration, seasonality and runoff ratio. This adaptation of ecosystems to climate could be explored for prediction in ungauged basins. We found that implementing the MCT-derived SR without recalibration has dramatically increased hydrological model transferability.

  2. Continent-sized anomalous zones with low seismic velocity at the base of Earth's mantle

    NASA Astrophysics Data System (ADS)

    Garnero, Edward J.; McNamara, Allen K.; Shim, Sang-Heon

    2016-07-01

    Seismic images of Earth's interior reveal two massive anomalous zones at the base of the mantle, above the core, where seismic waves travel slowly. The mantle materials that surround these anomalous regions are thought to be composed of cooler rocks associated with downward advection of former oceanic tectonic plates. However, the origin and composition of the anomalous provinces is uncertain. These zones have long been depicted as warmer-than-average mantle materials related to convective upwelling. Yet, they may also be chemically distinct from the surrounding mantle, and potentially partly composed of subducted or primordial material, and have therefore been termed thermochemical piles. From seismic, geochemical and mineral physics data, the emerging view is that these thermochemical piles appear denser than the surrounding mantle materials, are dynamically stable and long-lived, and are shaped by larger-scale mantle flow. Whether remnants of a primordial layer or later accumulations of more-dense materials, the composition of the piles is modified over time by stirring and by chemical reactions with material from the surrounding mantle, underlying core and potentially from volatile elements transported into the deep Earth by subducted plates. Upwelling mantle plumes may originate from the thermochemical piles, so the unusual chemical composition of the piles could be the source of distinct trace-element signatures observed in hotspot lavas.

  3. Visualization of microcrack anisotropy in granite affected by afault zone, using confocal laser scanning microscope

    SciTech Connect

    Onishi, Celia T.; Shimizu, Ichiko

    2004-01-02

    Brittle deformation in granite can generate a fracture system with different patterns. Detailed fracture analyses at both macroscopic and microscopic scales, together with physical property data from a drill-core, are used to classify the effects of reverse fault deformation in four domains: (1) undeformed granite, (2) fractured granite with cataclastic seams, (3) fractured granite from the damage zone, and (4) foliated cataclasite from the core of the fault. Intact samples from two orthogonal directions, horizontal (H) and vertical (V), from the four domains indicate a developing fracture anisotropy toward the fault, which is highly developed in the damage zone. As a specific illustration of this phenomenon, resin impregnation, using a confocal laser scanning microscope (CLSM) technique is applied to visualize the fracture anisotropy developed in the Toki Granite, Japan. As a result, microcrack networks have been observed to develop in H sections and elongate open cracks in V sections, suggesting that flow pathways can be determined by deformation.

  4. Exon size affects competition between splicing and cleavage-polyadenylation in the immunoglobulin mu gene.

    PubMed

    Peterson, M L; Bryman, M B; Peiter, M; Cowan, C

    1994-01-01

    The alternative RNA processing of microseconds and microns mRNAs from a single primary transcript depends on competition between a cleavage-polyadenylation reaction to produce microseconds mRNA and a splicing reaction to produce microns mRNA. The ratio of microseconds to microns mRNA is regulated during B-cell maturation; relatively more spliced microns mRNA is made in B cells than in plasma cells. The balance between the efficiencies of splicing and cleavage-polyadenylation is critical to the regulation. The mu gene can be modified to either reduce or improve the efficiency of each reaction and thus alter the ratio of the two RNAs produced. However, as long as neither reaction is so strong that it totally dominates, expression of the modified mu genes is regulated in B cells and plasma cells. The current experiments reveal a relationship between the C mu 4 exon size and the microseconds/microns expression ratio. The shorter the distance between the C mu 4 5' splice site and the nearest upstream 3' splice site, the more spliced microns mRNA was produced. Conversely, when this exon was expanded, more microseconds mRNA was produced. Expression from these mu genes with altered exon sizes were regulated between B cells and plasma cells. Since RNA processing in the mu gene can be considered a competition between defining the C mu 4 exon as an internal exon (in microns mRNA) versus a terminal exon (in microseconds mRNA), exon size may affect the competition among factors interacting with this exon. PMID:7903422

  5. Fewer but better: Proportionate size of the group affects evaluation of transgressive leaders.

    PubMed

    Travaglino, Giovanni A; Abrams, Dominic; Randsley de Moura, Georgina; Yetkili, Orkun

    2016-06-01

    A group may be badly affected if its leader transgresses important rules. Nonetheless, an emerging body of evidence suggests that in intergroup contexts, group members apply a double standard when judging ingroup leaders - They respond less punitively to transgressions by their leader than by non-leaders. In this article, two experiments investigated how proportionate ingroup size affects reactions to transgressive ingroup leaders. We demonstrate that ingroup leaders from larger, but not smaller, groups benefit from the double standard. The experiments testing the effects of two different types of transgressions (nepotistic favouritism and corruption, respectively) show that transgressive leaders from larger groups are evaluated more positively than both comparable non-leaders and leaders from smaller groups. In contrast, transgressive leaders from smaller groups are evaluated similarly to comparable transgressive non-leaders. Experiment 2 investigated a potential explanation for this phenomenon. Faced with a transgressive leader, members of a smaller group report greater embarrassment than do members of larger groups in relation to the leaders' actions. Implications of these findings and directions for future research are discussed. PMID:26334165

  6. Techniques for determining partial size distribution of particulate matter: Laser diffraction versus electrical sensing zone

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The study of health impacts, emission estimation of particulate matter (PM), and development of new control technologies require knowledge of PM characteristics. Among these PM characteristics, the particle size distribution (PSD) is perhaps the most important physical parameter governing particle b...

  7. 49 CFR 222.41 - How does this rule affect Pre-Rule Quiet Zones and Pre-Rule Partial Quiet Zones?

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...-Rule Quiet Zone may be established by automatic approval and remain in effect, subject to § 222.51, if the Pre-Rule Quiet Zone is in compliance with §§ 222.35 (minimum requirements for quiet zones) and 222... Zone may be established by automatic approval and remain in effect, subject to § 222.51, if the...

  8. 49 CFR 222.41 - How does this rule affect Pre-Rule Quiet Zones and Pre-Rule Partial Quiet Zones?

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...-Rule Quiet Zone may be established by automatic approval and remain in effect, subject to § 222.51, if the Pre-Rule Quiet Zone is in compliance with §§ 222.35 (minimum requirements for quiet zones) and 222... Zone may be established by automatic approval and remain in effect, subject to § 222.51, if the...

  9. 49 CFR 222.41 - How does this rule affect Pre-Rule Quiet Zones and Pre-Rule Partial Quiet Zones?

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...-Rule Quiet Zone may be established by automatic approval and remain in effect, subject to § 222.51, if the Pre-Rule Quiet Zone is in compliance with §§ 222.35 (minimum requirements for quiet zones) and 222... Zone may be established by automatic approval and remain in effect, subject to § 222.51, if the...

  10. 49 CFR 222.41 - How does this rule affect Pre-Rule Quiet Zones and Pre-Rule Partial Quiet Zones?

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...-Rule Quiet Zone may be established by automatic approval and remain in effect, subject to § 222.51, if the Pre-Rule Quiet Zone is in compliance with §§ 222.35 (minimum requirements for quiet zones) and 222... Zone may be established by automatic approval and remain in effect, subject to § 222.51, if the...

  11. 49 CFR 222.41 - How does this rule affect Pre-Rule Quiet Zones and Pre-Rule Partial Quiet Zones?

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...-Rule Quiet Zone may be established by automatic approval and remain in effect, subject to § 222.51, if the Pre-Rule Quiet Zone is in compliance with §§ 222.35 (minimum requirements for quiet zones) and 222... Zone may be established by automatic approval and remain in effect, subject to § 222.51, if the...

  12. Hydrogen-induced cold cracking in heat-affected zone of low-carbon high-strength steel

    NASA Astrophysics Data System (ADS)

    Lan, Liangyun; Kong, Xiangwei; Hu, Zhiyong; Qiu, Chunlin

    2014-12-01

    The Y-groove cracking test by submerged arc welding was employed to study the susceptibility of a low-carbon high-strength steel to hydrogen-induced cold cracking (HICC). The morphology of hydrogen cracks was observed using an electron probe microscope. The results showed that the heat-affected zone (HAZ) has a higher susceptibility to HICC than the weld metal and that increasing heat input can improve the HICC resistance of the weldment. The intergranular microcracking is the main HICC mode at the lowest heat input condition, accompanied with some transgranular microcracks attached to complex inclusions. In combination with phase transformation behaviour in sub-zones, the effect of the phase transformation sequence is proposed to try to illustrate the fact that the fine-grained HAZ has higher probability of hydrogen cracking than the coarse-grained HAZ owing to the occurrence of hydrogen enrichment in the fine-grained HAZ after the transformation.

  13. Determination of elastoplastic mechanical properties of the weld and heat affected zone metals in tailor-welded blanks by nanoindentation test

    NASA Astrophysics Data System (ADS)

    Ma, Xiangdong; Guan, Yingping; Yang, Liu

    2015-09-01

    The elastoplastic mechanical properties of the weld and heat affected zone metals have comparatively major impact on the forming process of tailor-welded blanks. A few scholars investigated the elastoplastic mechanical properties of the weld and heat affected zone, but they only simply assumed that it was a uniform distribution elastoplastic material different from the base materials. Four types of tailor-welded blanks which consist of ST12 and 304 stainless steel plates are selected as the research objects, the elastoplastic mechanical properties of the tailor-welded blanks weld and heat affected zone metals are obtained based on the nanoindentation tests, and the Erichsen cupping tests are conducted by combining numerical simulation with physical experiment. The nanoindentation tests results demonstrate that the elastoplastic mechanical properties of the weld and heat affected zone metals are not only different from the base materials, but also varying between the weld metals and the heat affected zone metals. Comparing the Erichsen cupping test resulted from numerical with that from experimental method, it is found that the numerical value of Erichsen cupping test which consider the elastoplastic mechanical properties of the weld and heat affected zone metals have a good agreement with the experimental result, and the relative error is only 4.8%. The proposed research provides good solutions for the inhomogeneous elastoplastic mechanical properties of the tailor-welded blanks weld and heat affected zone metals, and improves the control performance of tailor-welded blanks forming accuracy.

  14. Slip-weakening zone sizes at nucleation of catastrophic subaerial and submarine landslides by gradually increasing pore pressure

    NASA Astrophysics Data System (ADS)

    Viesca, R. C.; Rice, J. R.

    2011-12-01

    We address the nucleation of dynamic landslide rupture in response to gradual pore pressure increases. Nucleation marks the onset of acceleration of the overlying slope mass due to the suddenly rapid enlargement of a sub-surface zone of shear failure, previously deforming quasi-statically. We model that zone as a planar surface undergoing initially linear slip-weakening frictional failure within a bordering linear-elastic medium. The results are also relevant to earthquake nucleation. The sub-surface rupture zone considered runs parallel to the free surface of a uniform slope, under a 2D plane-strain deformation state. We show results for ruptures with friction coefficients following linear slip weakening (i.e., the residual friction is not yet reached). For spatially broad increases in pore pressure, the nucleation length depends on a ratio of depth to a cohesive zone length scale. In the very broad-increase limit, a direct numerical solution for nucleation lengths compares well with solutions to a corresponding eigenvalue problem (similar to Uenishi and Rice [JGR '03]), in which spatial variations in normal stress are neglected. We estimate nucleation lengths for subaerial and submarine conditions using data [e.g., Bishop et al., Géotech. '71; Stark et al., JGGE '05] from ring-shear tests on sediments (peak friction fp = 0.5, frictional slip-weakening rate within the range w = -df/d(slip) = 0.1/cm-1/cm). We assume that only pre-stresses, and not material properties, vary with depth. With such fp and w, we find for a range of subsurface depths and shear moduli μ that nucleation lengths are typically several hundred meters long for shallow undersea slopes, and up to an order of magnitude less for steeper slopes on the Earth's surface. In the submarine case, this puts nucleation lengths in a size range comparable to observed pore-pressure-generated seafloor disturbances as pockmarks [e.g., Gay et al., MG '06].

  15. The study on microstructural and mechanical properties of weld heat affected zone of 7075-T651 aluminum alloy

    SciTech Connect

    Hwang, R.Y.; Chou, C.P.

    1997-12-22

    Aluminum alloys play an important role in aerospace industry due to their high strength and low density. The general accepted precipitation behavior of 7075 alloy was represented as: supersaturated solid solution {alpha}{sub ss} {yields} Gp zones {yields} {eta}{prime}(MgZn{sub 2}) {yields} {eta}(MgZn{sub 2}). The Addition of Cu in Al-Zn-Mg alloy would promote the transformation of GP zones into {eta}{prime}(MgZn{sub 2}) phase and stabilize the {eta}(MgZn{sub 2}) phase. The T6 temper has the maximum strength but lower ductility. The T73 temper may lose some strength, but can gain higher corrosion resistance and lower susceptibility to stress corrosion cracking as compared to the T6 temper. The welding fabrication can produce thermal cycling on the weldment. In the heat affected zone (HAZ) beside the fusion zone, different temperatures can be obtained. This would cause change of microstructure in the HAZ of aluminum alloy weldment. Many workers studied the behavior of weld HAZ by cutting the HAZ into many small pieces or using short time isothermal heat treatment to simulate the HAZ. This may lose some information, especially near the fusion zone, because high temperature gradient occurred in this region. In this study, the Gleeble system was used to simulate the weld HAZ. It can accurately simulate every point of weld HAZ by heating and cooling the specimen to the thermal history of weld HAZ as the same as measured. The microstructural and mechanical properties of weld HAZ of 7075-T651 alloy were investigated.

  16. Determination of degradation rates of organic substances in the unsaturated soil zone depending on the grain size fractions of various soil types

    NASA Astrophysics Data System (ADS)

    Fichtner, Thomas; Stefan, Catalin; Goersmeyer, Nora

    2015-04-01

    Rate and extent of the biological degradation of organic substances during transport through the unsaturated soil zone is decisively influenced by the chemical and physical properties of the pollutants such as water solubility, toxicity and molecular structure. Furthermore microbial degradation processes are also influenced by soil-specific properties. An important parameter is the soil grain size distribution on which the pore volume and the pore size depends. Changes lead to changes in air and water circulation as well as preferred flow paths. Transport capacity of water inclusive nutrients is lower in existing bad-drainable fine pores in soils with small grain size fractions than in well-drainable coarse pores in a soil with bigger grain size fractions. Because fine pores are saturated with water for a longer time than the coarse pores and oxygen diffusion in water is ten thousand times slower than in air, oxygen is replenished much slower in soils with small grain size fractions. As a result life and growth conditions of the microorganisms are negatively affected. This leads to less biological activity, restricted degradation/mineralization of pollutants or altered microbial processes. The aim of conducted laboratory column experiments was to study the correlation between the grain size fractions respectively pore sizes, the oxygen content and the biodegradation rate of infiltrated organic substances. Therefore two columns (active + sterile control) were filled with different grain size fractions (0,063-0,125 mm, 0,2-0,63 mm and 1-2 mm) of soils. The sterile soil was inoculated with a defined amount of a special bacteria culture (sphingobium yanoikuae). A solution with organic substances glucose, oxalic acid, sinaphylic alcohol and nutrients was infiltrated from the top in intervals. The degradation of organic substances was controlled by the measurement of dissolved organic carbon in the in- and outflow of the column. The control of different pore volumes

  17. Effect of Mg Content on the Microstructure and Toughness of Heat-Affected Zone of Steel Plate after High Heat Input Welding

    NASA Astrophysics Data System (ADS)

    Xu, Long-Yun; Yang, Jian; Wang, Rui-Zhi; Wang, Yu-Nan; Wang, Wan-Lin

    2016-05-01

    The effect of Mg content on the microstructure and toughness of the heat-affected zone (HAZ) of steel plates after high heat input welding was investigated by means of welding thermal simulation test and in situ observation through high-temperature laser scanning confocal microscopy. It was found that with the increase of Mg content in the steel, the former austenite grain sizes were greatly decreased and the mainly microstructural constituents in HAZ were changed from the brittle constituents of Widmanstätten ferrite, ferrite side plate and upper bainite to the ductile constituents of intragranular acicular ferrite and polygonal ferrite. The proportion of grain boundary ferrite was decreased greatly with the further addition of Mg from 27 to 99 ppm. As a result, the HAZ toughness after welding with heat input of 400 kJ cm-1 is increased with increasing Mg content in the steel plate.

  18. Effect of Mg Content on the Microstructure and Toughness of Heat-Affected Zone of Steel Plate after High Heat Input Welding

    NASA Astrophysics Data System (ADS)

    Xu, Long-Yun; Yang, Jian; Wang, Rui-Zhi; Wang, Yu-Nan; Wang, Wan-Lin

    2016-07-01

    The effect of Mg content on the microstructure and toughness of the heat-affected zone (HAZ) of steel plates after high heat input welding was investigated by means of welding thermal simulation test and in situ observation through high-temperature laser scanning confocal microscopy. It was found that with the increase of Mg content in the steel, the former austenite grain sizes were greatly decreased and the mainly microstructural constituents in HAZ were changed from the brittle constituents of Widmanstätten ferrite, ferrite side plate and upper bainite to the ductile constituents of intragranular acicular ferrite and polygonal ferrite. The proportion of grain boundary ferrite was decreased greatly with the further addition of Mg from 27 to 99 ppm. As a result, the HAZ toughness after welding with heat input of 400 kJ cm-1 is increased with increasing Mg content in the steel plate.

  19. [Determination of average particle diameter and size distribution of ultra-fine beta zeolite by capillary zone electrophoresis].

    PubMed

    Xue, Yan; Yang, Haiying; Yang, Yongtan

    2004-09-01

    A new method was developed for the determination of average particle diameter and size distribution of ultra-fine beta zeolite by capillary zone electrophoresis (CZE). The dispersion and stabilization conditions of ultra-fine beta zeolite powder in suspensions were investigated by measuring the isoelectric point (IEP) of the powder suspension. Stable dispersion condition of beta zeolite ultrafine particles in aqueous solution was obtained by adding beta zeolite into the buffer (1.25 mmol/L NaHCO3-5 mmol/L Na2CO3, pH 10.82). The calibration equation between migration time and particle size was established to obtain the data of particle diameter by relating the beta zeolite diameters determined by laser particle sizer with the migration time from electropherogram of beta zeolite through the cumulative percentage of particle distribution. The calibration equation between particle size and amount was also established to correct the deviation of the response caused by particle size as the special relating principle suggested in the paper. The method is advantageous in small sample quantity required, low cost and short measurement period for each individual analysis. PMID:15706938

  20. Group Size and Nest Spacing Affect Buggy Creek Virus (Togaviridae: Alphavirus) Infection in Nestling House Sparrows

    PubMed Central

    O'Brien, Valerie A.; Brown, Charles R.

    2011-01-01

    The transmission of parasites and pathogens among vertebrates often depends on host population size, host species diversity, and the extent of crowding among potential hosts, but little is known about how these variables apply to most vector-borne pathogens such as the arboviruses (arthropod-borne viruses). Buggy Creek virus (BCRV; Togaviridae: Alphavirus) is an RNA arbovirus transmitted by the swallow bug (Oeciacus vicarius) to the cliff swallow (Petrochelidon pyrrhonota) and the introduced house sparrow (Passer domesticus) that has recently invaded swallow nesting colonies. The virus has little impact on cliff swallows, but house sparrows are seriously affected by BCRV. For house sparrows occupying swallow nesting colonies in western Nebraska, USA, the prevalence of BCRV in nestling sparrows increased with sparrow colony size at a site but decreased with the number of cliff swallows present. If one nestling in a nest was infected with the virus, there was a greater likelihood that one or more of its nest-mates would also be infected than nestlings chosen at random. The closer a nest was to another nest containing infected nestlings, the greater the likelihood that some of the nestlings in the focal nest would be BCRV-positive. These results illustrate that BCRV represents a cost of coloniality for a vertebrate host (the house sparrow), perhaps the first such demonstration for an arbovirus, and that virus infection is spatially clustered within nests and within colonies. The decreased incidence of BCRV in sparrows as cliff swallows at a site increased reflects the “dilution effect,” in which virus transmission is reduced when a vector switches to feeding on a less competent vertebrate host. PMID:21966539

  1. Grain size reduction of feldspar and pyroxene, phase mixing, and strain localization in lower crustal shear zones (Lofoten, Norway)

    NASA Astrophysics Data System (ADS)

    Menegon, L.; Stunitz, H.; Nasipuri, P.; Svahnberg, H.; Heilbronner, R.

    2011-12-01

    High temperature shear zones are common in the magmatic suite of the granulite facies Lofoten basement of Norway, and typically consist of narrow structures (1 cm to 1 m in thickness) showing a mylonite-to ultramylonite transition from the shear zone boundary to the shear zone center. In this contribution we examine the deformation microstructures and synkinematic mineral assemblages of shear zones developed from a mangerite (=monzonite) protolith. The mineral assemblage in the host mangerite indicates anhydrous conditions (mesoperthite + clinopyroxene ± orthopyroxene), whereas the mineral assemblage in the shear zones consists of plagioclase + K-feldspar + quartz + hornblende + calcite + biotite ± clinopyroxene and indicates hydrated conditions. Hornblende-plagioclase geothermobarometry yields upper amphibolite- to granulite facies conditions during shearing (730-760° C, 0.55-0.8 GPa). The mylonite consists of two distinct compositional domains: a pyroxene-derived aggregate and a feldspar-derived aggregate. The pyroxene-derived aggregate consists of the products of the following breakdown reaction: clinopyroxene + plagioclase ± K-feldspar ± orthopyroxene + H2O + CO2 --> quartz + hornblende + calcite ± biotite. In the feldspar-derived aggregate fractured fragments of mesoperthite are surrounded by a bi-phase mixture of recrystallized plagioclase and K-feldspar. EBSD analysis indicates that the recrystallized grains originated as micro-fragments from fracturation, and recrystallization was compositionally-induced (e.g. An22 average composition of plagioclase in the mesoperthite, An14 in the recrystallized aggregate). Detailed grain size, grain shape and EBSD analysis indicate that diffusion creep was the dominant deformation mechanism in both aggregates. Spatial distribution of K-feldspar and plagioclase shows a well dispersed aggregate and may serve as a tool to characterize diffusion creep deformation in phase mixtures. In the ultramylonite the two

  2. The effect of weld Heat-Affected zone (HAZ) liquation kinetics on the hot cracking susceptibility of alloy 718

    NASA Astrophysics Data System (ADS)

    Radhakrishnan, B.; Thompson, R. G.

    1993-06-01

    A delay in grain boundary liquation was observed in the subsolidus portion of the weld heat affected zone (HAZ) of alloy 718 for the solution-treated material. However, for the homogenized or the homogenized and aged alloy, an instantaneous liquation of the grain boundaries occurred in the subsolidus HAZ. The above difference in the grain boundary liquation kinetics may account for the greater hot-cracking susceptibility of the homogenized or the homogenized and aged alloy compared to that of the solution-treated alloy. Existing models of grain boundary liquation are used to explain the observed kinetic effects associated with liquation in the subsolidus HAZ of alloy 718.

  3. Influence of rapid thermal cycles in multipass welding on heat-affected-zone properties in ferritic cryogenic steels

    SciTech Connect

    Kim, H.J.; Shin, H.K.; Morris, J.W. Jr.

    1982-05-01

    The results of both welding and weld simulation studies on 2BT-treated 9Ni steel show that multiple rapid thermal cycles have a very beneficial effect on heat-affected zone toughness at cryogenic temperatures. The metallurgical sources of toughness are, however, different from those in the furnace-treated base plate. The rapidly cycled material contains no detectable austenite phase. The alloy is grain-refined by the rapid thermal cycle, and the matrix carbon content is relieved by the formation of interlathcementite precipitates which do not destroy toughness.

  4. The effect of weld heat-affected zone (HAZ) liquation kinetics on the hot cracking susceptibility of alloy 718

    SciTech Connect

    Radhakrishnan, B.; Thompson, R.G. . Department of Materials Science and Engineering)

    1993-06-01

    A delay in grain boundary liquation was observed in the subsolidus portion of the weld heat affected zone (HAZ) of alloy 718 for the solution-treated material. However, for the homogenized and aged alloy, an instantaneous liquation of the grain boundaries occurred in the subsolidus HAZ. The above difference in the grain boundary liquation kinetics may account for the greater hot-cracking susceptibility of the homogenized or the homogenized and aged alloy compared to that of the solution-treated alloy. Existing models of grain boundary liquation are used to explain the observed kinetic effects associated with liquation in the subsolidus HAZ of alloy 718.

  5. Hot-cracking studies of Inconel 718 weld- heat-affected zones

    NASA Technical Reports Server (NTRS)

    Thompson, E. G.

    1969-01-01

    Hot ductility tests, gas-tungsten-arc fillerless fusion tests, and circle patch-weld-restraint tests were conducted on Inconel 718 to better understand and correlate the weldability /resistance to hot cracking/ of the alloy. A correlation of the test results with composition, heat-treat condition, grain size, and microstructure was made.

  6. Fractal Scaling of Particle Size Distribution and Relationships with Topsoil Properties Affected by Biological Soil Crusts

    PubMed Central

    Gao, Guang-Lei; Ding, Guo-Dong; Wu, Bin; Zhang, Yu-Qing; Qin, Shu-Gao; Zhao, Yuan-Yuan; Bao, Yan-Feng; Liu, Yun-Dong; Wan, Li; Deng, Ji-Feng

    2014-01-01

    Background Biological soil crusts are common components of desert ecosystem; they cover ground surface and interact with topsoil that contribute to desertification control and degraded land restoration in arid and semiarid regions. Methodology/Principal Findings To distinguish the changes in topsoil affected by biological soil crusts, we compared topsoil properties across three types of successional biological soil crusts (algae, lichens, and mosses crust), as well as the referenced sandland in the Mu Us Desert, Northern China. Relationships between fractal dimensions of soil particle size distribution and selected soil properties were discussed as well. The results indicated that biological soil crusts had significant positive effects on soil physical structure (P<0.05); and soil organic carbon and nutrients showed an upward trend across the successional stages of biological soil crusts. Fractal dimensions ranged from 2.1477 to 2.3032, and significantly linear correlated with selected soil properties (R2 = 0.494∼0.955, P<0.01). Conclusions/Significance Biological soil crusts cause an important increase in soil fertility, and are beneficial to sand fixation, although the process is rather slow. Fractal dimension proves to be a sensitive and useful index for quantifying changes in soil properties that additionally implies desertification. This study will be essential to provide a firm basis for future policy-making on optimal solutions regarding desertification control and assessment, as well as degraded ecosystem restoration in arid and semiarid regions. PMID:24516668

  7. Loss of phylloquinone in Chlamydomonas affects plastoquinone pool size and photosystem II synthesis.

    PubMed

    Lefebvre-Legendre, Linnka; Rappaport, Fabrice; Finazzi, Giovanni; Ceol, Mauro; Grivet, Chantal; Hopfgartner, Gérard; Rochaix, Jean-David

    2007-05-01

    Phylloquinone functions as the electron transfer cofactor at the A(1) site of photosystem I. We have isolated and characterized a mutant of Chlamydomonas reinhardtii, menD1, that is deficient in MenD, which encodes 2-succinyl-6-hydroxy-2,4-cyclohexadiene-1-carboxylate synthase, an enzyme that catalyzes the first specific step of the phylloquinone biosynthetic pathway. The mutant is photosynthetically active but light-sensitive. Analysis of total pigments by mass spectrometry reveals that phylloquinone is absent in menD1, but plastoquinone levels are not affected. This is further confirmed by the rescue of menD1 by addition of phylloquinone to the growth medium. Analysis of electron transfer by absorption spectroscopy indicates that plastoquinone replaces phylloquinone in photosystem I and that electron transfer from A(1) to the iron-sulfur centers is slowed down at least 40-fold. Consistent with a replacement of phylloquinone by plastoquinone, the size of the free plastoquinone pool of menD1 is reduced by 20-30%. In contrast to cyanobacterial MenD-deficient mutants, photosystem I accumulates normally in menD1, whereas the level of photosystem II declines. This decrease is because of reduced synthesis of the photosystem II core subunits. The relationship between plastoquinone occupancy of the A(1) site in photosystem I and the reduced accumulation of photosystem II is discussed. PMID:17339322

  8. Size separation of proteins by capillary zone electrophoresis with cationic hitchhiking (CZECH)

    PubMed Central

    Dolnik, Vladislav; Gurske, William A.

    2012-01-01

    The paper describes a method of size separation of proteins by capillary sieving electrophoresis with cationic surfactant. Proteins are separated within 12 minutes with repeatability of migration times better than 0.2%. Some proteins achieve the separation efficiency of 200,000 theoretical plates. The method can be used for determination of protein relative molecular masses. The accuracy of the determined relative molecular masses and the limitation of the method were investigated by the analysis of more than 60 proteins. The method also allows separation of protein oligomers. Proteins can be quantitated after the electrokinetic injection in the concentration range 0.07–0.43 g/L. The average detection limit is about 2 mg/L. PMID:21948216

  9. Size-fractionated diversity of eukaryotic microbial communities in the Eastern Tropical North Pacific oxygen minimum zone.

    PubMed

    Duret, Manon T; Pachiadaki, Maria G; Stewart, Frank J; Sarode, Neha; Christaki, Urania; Monchy, Sébastien; Srivastava, Ankita; Edgcomb, Virginia P

    2015-05-01

    Oxygen minimum zones (OMZs) caused by water column stratification appear to expand in parts of the world's ocean, with consequences for marine biogeochemical cycles. OMZ formation is often fueled by high surface primary production, and sinking organic particles can be hotspots of interactions and activity within microbial communities. This study investigated the diversity of OMZ protist communities in two biomass size fractions (>30 and 30-1.6 μm filters) from the world's largest permanent OMZ in the Eastern Tropical North Pacific. Diversity was quantified via Illumina MiSeq sequencing of V4 region of 18S SSU rRNA genes in samples spanning oxygen gradients at two stations. Alveolata and Rhizaria dominated the two size fractions at both sites along the oxygen gradient. Community composition at finer taxonomic levels was partially shaped by oxygen concentration, as communities associated with versus anoxic waters shared only ∼32% of operational taxonomic unit (OTU) (97% sequence identity) composition. Overall, only 9.7% of total OTUs were recovered at both stations and under all oxygen conditions sampled, implying structuring of the eukaryotic community in this area. Size-fractionated communities exhibited different taxonomical features (e.g. Syndiniales Group I in the 1.6-30 μm fraction) that could be explained by the microniches created on the surface-originated sinking particles. PMID:25873468

  10. How Well Does Fracture Set Characterization Reduce Uncertainty in Capture Zone Size for Wells Situated in Sedimentary Bedrock Aquifers?

    NASA Astrophysics Data System (ADS)

    West, A. C.; Novakowski, K. S.

    2005-12-01

    beyond a threshold concentration within the specified time. Aquifers are simulated by drawing the random spacings and apertures from specified distributions. Predictions are made of capture zone size assuming various degrees of knowledge of these distributions, with the parameters of the horizontal fractures being estimated using simulated hydraulic tests and a maximum likelihood estimator. The uncertainty is evaluated by calculating the variance in the capture zone size estimated in multiple realizations. The results show that despite good strategies to estimate the parameters of the horizontal fractures the uncertainty in capture zone size is enormous, mostly due to the lack of available information on vertical fractures. Also, at realistic distances (less than ten kilometers) and using realistic transmissivity distributions for the horizontal fractures the uptake of solute from fractures into matrix cannot be relied upon to protect the production well from contamination.

  11. Effect of homogenization heat treatment on the microstructure and heat-affected zone microfissuring in welded cast alloy 718

    SciTech Connect

    Xiao Huang; Richards, N.L.; Chaturvedi, M.C.

    1996-03-01

    The effect of homogenization temperature on microfissuring in the heat-affected zones of electron-beam welded cast INCONEL 718 has been studied. The material was homogenized at various temperatures in the range of 1,037 C and 1,163 C and air-cooled. The homogenized material was then electron-beam welded by the bead-on-plate welding technique. The microstructures and microfissuring in the heat-affected zone (HAZ) were evaluated by analytical scanning electron microscopy (SEM). The grain boundary segregation of various elements was evaluated by secondary ion mass spectroscopy (SIMS). It was observed that the total crack length (TCL) of microfissures first decreases with homogenization temperature and then increases, with a minimum occurring in the specimen heat treated at 1,163 C. This trend coincides with the variation in segregation of B at grain boundaries with homogenization temperature and has been explained by equilibrium and nonequilibrium segregation of B to grain boundaries during the homogenization heat treatment. No other element was observed to segregate at the grain boundaries. The variation in volume fraction of phases like {delta}-Ni{sub 3}Nb, MC carbide, and Laves phases does not follow the same trend as that observed for TCL and B segregation at the grain boundaries. Therefore, microfissuring in HAZ of welded cast INCONEL 718 is attributed to the segregation of B at the grain boundaries.

  12. Effect of homogenization heat treatment on the microstructure and heat- affected zone microfissuring in welded cast alloy 718

    NASA Astrophysics Data System (ADS)

    Huang, Xiao; Chaturvedi, M. C.; Richards, N. L.

    1996-03-01

    The effect of homogenization temperature on microfissuring in the heat-affected zones of electronwelded cast INCONEL 718 has been studied. The material was homogenized at various temperatures in the range of 1037 ° to 1163 ° and air-cooled. The homogenized material was then electron-beam welded by the bead-on-plate welding technique. The microstructures and microfissuring in the heat-affected zone (HAZ) were evaluated by analytical scanning electron microscopy (SEM). The grain boundary segregation of various elements was evaluated by secondary ion mass spectroscopy (SIMS). It was observed that the total crack length (TCL) of microfissures first decreases with homogenization temperature and then increases, with a minimum occurring in the specimen heat treated at 1163 °. This trend coincides with the variation in segregation of B at grain boundaries with homogenization temperature and has been explained by equilibrium and nonequilibrium segregation of B to grain boundaries during the homogenization heat treatment. No other element was observed to segregate at the grain boundaries. The variation in volume fraction of phases like δ-Ni3Nb, MC carbide, and Laves phases does not follow the same trend as that observed for TCL and B segregation at the grain boundaries. Therefore, microfissuring in HAZ of welded cast INCONEL 718 is attributed to the segregation of B at the grain boundaries.

  13. Factors Affecting the Latitudinal Location of the Intertropical Convergence Zone in a GCM

    NASA Technical Reports Server (NTRS)

    Chao, Winston C.; Chen, Baode

    2002-01-01

    The dominant role of the latitudinal peak of the sea surface temperature (SST) in determining the latitudinal location of the intertropical convergence zone (ITCZ) is well-known. However, the roles of the other factors are less well-known and are the topic of this study. These other factors include the inertial stability, the interaction between convection and surface fluxes and the interaction between convection and radiation. Since these interactions involve convection, in a model they involve the cumulus parameterization scheme. These factors are studied with a general circulation model with uniform SST and solar angle. Under the aforementioned model settings, the latitudinal location of the ITCZ is the latitude where the balance of two types of attraction on the ITCZ, both due to earth's rotation, exists. Directly related to the Coriolis parameter, the first type pulls the ITCZ toward the equator and is not sensitive to model design changes. Related to the convective circulation, the second type pulls the ITCZ poleward and is sensitive to model design changes. Due to the shape and the magnitude of the attractors, the balance of the two types of attractions is reached either at the equator or more than 10 degrees away from the equator. The former case results in a single ITCZ over the equator and the latter case a double ITCZ straddling the equator.

  14. Mechanics of lipid bilayer junctions affecting the size of a connecting lipid nanotube

    NASA Astrophysics Data System (ADS)

    Karlsson, Roger; Kurczy, Michael; Grzhibovskis, Richards; Adams, Kelly L.; Ewing, Andrew G.; Cans, Ann-Sofie; Voinova, Marina V.

    2011-06-01

    In this study we report a physical analysis of the membrane mechanics affecting the size of the highly curved region of a lipid nanotube (LNT) that is either connected between a lipid bilayer vesicle and the tip of a glass microinjection pipette (tube-only) or between a lipid bilayer vesicle and a vesicle that is attached to the tip of a glass microinjection pipette (two-vesicle). For the tube-only configuration (TOC), a micropipette is used to pull a LNT into the interior of a surface-immobilized vesicle, where the length of the tube L is determined by the distance of the micropipette to the vesicle wall. For the two-vesicle configuration (TVC), a small vesicle is inflated at the tip of the micropipette tip and the length of the tube L is in this case determined by the distance between the two interconnected vesicles. An electrochemical method monitoring diffusion of electroactive molecules through the nanotube has been used to determine the radius of the nanotube R as a function of nanotube length L for the two configurations. The data show that the LNT connected in the TVC constricts to a smaller radius in comparison to the tube-only mode and that tube radius shrinks at shorter tube lengths. To explain these electrochemical data, we developed a theoretical model taking into account the free energy of the membrane regions of the vesicles, the LNT and the high curvature junctions. In particular, this model allows us to estimate the surface tension coefficients from R( L) measurements.

  15. Epigenetic Mutation of RAV6 Affects Leaf Angle and Seed Size in Rice.

    PubMed

    Zhang, Xiangqian; Sun, Jing; Cao, Xiaofeng; Song, Xianwei

    2015-11-01

    Heritable epigenetic variants of genes, termed epialleles, can broaden genetic and phenotypic diversity in eukaryotes. Epialleles may also provide a new source of beneficial traits for crop breeding, but very few epialleles related to agricultural traits have been identified in crops. Here, we identified Epi-rav6, a gain-of-function epiallele of rice (Oryza sativa) RELATED TO ABSCISIC ACID INSENSITIVE3 (ABI3)/VIVIPAROUS1 (VP1) 6 (RAV6), which encodes a B3 DNA-binding domain-containing protein. The Epi-rav6 plants show larger lamina inclination and smaller grain size; these agronomically important phenotypes are inherited in a semidominant manner. We did not find nucleotide sequence variation of RAV6. Instead, we found hypomethylation in the promoter region of RAV6, which caused ectopic expression of RAV6 in Epi-rav6 plants. Bisulfite analysis revealed that cytosine methylation of four CG and two CNG loci within a continuous 96-bp region plays essential roles in regulating RAV6 expression; this region contains a conserved miniature inverted repeat transposable element transposon insertion in cultivated rice genomes. Overexpression of RAV6 in the wild type phenocopied the Epi-rav6 phenotype. The brassinosteroid (BR) receptor BR INSENSITIVE1 and BR biosynthetic genes EBISU DWARF, DWARF11, and BR-DEFICIENT DWARF1 were ectopically expressed in Epi-rav6 plants. Also, treatment with a BR biosynthesis inhibitor restored the leaf angle defects of Epi-rav6 plants. This indicates that RAV6 affects rice leaf angle by modulating BR homeostasis and demonstrates an essential regulatory role of epigenetic modification on a key gene controlling important agricultural traits. Thus, our work identifies a unique rice epiallele, which may represent a common phenomenon in complex crop genomes. PMID:26351308

  16. The Binding Ring Illusion: assimilation affects the perceived size of a circular array

    PubMed Central

    Caplovitz, Gideon P

    2013-01-01

    Our perception of an object’s size arises from the integration of multiple sources of visual information including retinal size, perceived distance and its size relative to other objects in the visual field. This constructive process is revealed through a number of classic size illusions such as the Delboeuf Illusion, the Ebbinghaus Illusion and others illustrating size constancy. Here we present a novel variant of the Delbouef and Ebbinghaus size illusions that we have named the Binding Ring Illusion. The illusion is such that the perceived size of a circular array of elements is underestimated when superimposed by a circular contour – a binding ring – and overestimated when the binding ring slightly exceeds the overall size of the array. Here we characterize the stimulus conditions that lead to the illusion, and the perceptual principles that underlie it. Our findings indicate that the perceived size of an array is susceptible to the assimilation of an explicitly defined superimposed contour. Our results also indicate that the assimilation process takes place at a relatively high level in the visual processing stream, after different spatial frequencies have been integrated and global shape has been constructed. We hypothesize that the Binding Ring Illusion arises due to the fact that the size of an array of elements is not explicitly defined and therefore can be influenced (through a process of assimilation) by the presence of a superimposed object that does have an explicit size. PMID:24555042

  17. Quantifying the Floe Size Distribution in the Marginal Ice Zone from Satellite Imagery for use in Model Development and Validation

    NASA Astrophysics Data System (ADS)

    Schweiger, A. J.; Stern, H. L.; Stark, M.; Zhang, J.; Hwang, P.; Steele, M.

    2013-12-01

    Several key processes in the Marginal Ice Zone (MIZ) of the Arctic Ocean are related to the size of the ice floes, whose diameters range from meters to tens of kilometers. The floe size distribution (FSD) influences mechanical properties of the ice and thus its response to winds, currents, and waves, which is likely to modify the air-sea momentum transfer. The FSD also influences the air-sea heat transfer and the response of the MIZ ice cover to the thermal forcing. The FSD also has a significant role in lateral melting. No existing sea-ice/ocean models currently simulate the FSD in the MIZ. Significant uncertainties in FSD-related processes hinder model incorporation of the FSD, and model development must heavily depend on observations of the FSD for parameterization, calibration, and validation. To support the development and implementation of the FSD in the Marginal Ice Zone Modeling and Assimilation System (MIZMAS), we have conducted an analysis of the FSD in the Beaufort and Chukchi seas using three sources of satellite imagery: NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) on the Terra and Aqua satellites, the Canadian Space Agency's synthetic aperture radar (SAR) on RADARSAT, and declassified National Technical Means imagery from the Global Fiducials Library (GFL) of the U.S. Geological Survey. The MODIS visible and short-wave infrared bands have a pixel size of 250 meters, and are only useful in cloud-free regions. The SAR imagery is unaffected by clouds and darkness, and has a pixel size of 50 meters. The GFL visible imagery, with a pixel size of 1 meter, is only useful in cloud-free regions. The resolution and spatial extent of the various image products allows us to identify ice floes of all sizes from 10 meters to 100 kilometers. The general procedure for identifying ice floes in the imagery is as follows: delineate cloud-free regions (if necessary); choose a threshold to separate ice from water, and create a binary image; apply the

  18. Nutrient demand interacts with legume maturity to affect rumen pool sizes in dairy cows.

    PubMed

    Kammes, K L; Ying, Y; Allen, M S

    2012-05-01

    Effects of legume maturity on dry matter intake (DMI), milk production, ruminal fermentation and pool sizes, and digestion and passage kinetics, and the relationship of these effects with preliminary DMI (pDMI) were evaluated using 16 ruminally and duodenally cannulated Holstein cows in a crossover design with a 14-d preliminary period and two 17-d treatment periods. During the preliminary period, the pDMI of individual cows ranged from 22.9 to 30.0 kg/d (mean=25.9 kg/d) and the 3.5% fat-corrected milk yield ranged from 34.1 to 68.2 kg/d (mean=43.7 kg/d). Experimental treatments were diets containing alfalfa silage harvested either a) early-cut, less mature (EC) or b) late-cut, more mature (LC) as the sole forage. Early- and late-cut alfalfa contained 40.8 and 53.1% neutral detergent fiber (NDF) and 23.7 and 18.1% crude protein, respectively. Forage:concentrate ratios were 53:47 and 42:58 for EC and LC, respectively; both diets contained approximately 22% forage NDF and 27% total NDF. Preliminary DMI, an index of nutrient demand, was determined during the last 4d of the preliminary period when cows were fed a common diet and used as a covariate. Main effects of alfalfa maturity and their interaction with pDMI were tested by ANOVA. Alfalfa maturity and its interaction with pDMI did not affect milk yield but EC increased DMI compared with LC; thus, EC had lower efficiency of milk production than LC. The EC diet decreased milk fat concentration more per kilogram of pDMI increase than the LC diet, but milk fat yield was not affected. The lower concentration and faster passage rate of indigestible NDF for EC resulted in lower rumen pools of indigestible NDF, total NDF, and dry matter than did LC, which EC increased at a slower rate than did LC as pDMI increased. The EC diet decreased starch intake and increased ruminal pH compared with the LC diet. The rate of ruminal starch digestion was related to level of intake, but this did not affect ruminal or postruminal starch

  19. Health in the hot zone - How could global warming affect humans?

    SciTech Connect

    Monastersky, R.

    1996-04-06

    A soon-to-be-released report from the World Health Organization examines the health effects of global warming, calling climate change one of the largest public health challenges for the upcoming century. The issue extends beyond tropical illness: deaths caused directly by heat, dwindling agricultural yields etc. could all affect human health. This article looks at the following health related effects and gives an overview of the scientific information available on each: temperature and mortality; tropical trouble, including vecorborne diseases and increase in susceptable populations; and waterborne problems such as cholera, harmful algal bloomes, food shortages.

  20. The granule size distribution in an anammox-based granular sludge reactor affects the conversion--implications for modeling.

    PubMed

    Volcke, E I P; Picioreanu, C; De Baets, B; van Loosdrecht, M C M

    2012-07-01

    Mathematical models are useful tools to optimize the performance of granular sludge reactors. In these models, typically a uniform granule size is assumed for the whole reactor, even though in reality the granules follow a size distribution and the granule size as such affects the process performance. This study assesses the effect of the granule size distribution on the performance of a granular sludge reactor in which autotrophic nitrogen removal is realized through one-stage partial nitritation-anammox. A comparison is made between different approaches to deal with particle size distributions in one-dimensional biofilm models, from the use of a single characteristic diameter to applying a multiple compartment model. The results show a clear impact on the conversion efficiency of the way in which particle size distribution is modeled, resulting from the effect of the granule size on the competition between nitrite oxidizing and anammox bacteria and from the interaction between granules of different sizes in terms of the exchange of solutes. Whereas the use of a uniform granule size is sufficient in case only the overall reactor behavior needs to be assessed, taking into account the detailed granule size distribution is required to study the solute exchange between particles of different sizes. For the latter purpose, the application of the widespread software package Aquasim is limited and the development of dedicated software applications is required. PMID:22252967

  1. Water Vapor Diffusion through Soil as Affected by Temperature and Aggregate Size

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Water vapor diffusion through the soil is an important part in the total water flux in the unsaturated zone of arid or semiarid regions and has several significant agricultural and engineering applications because soil moisture contents near the surface are relatively low. Water vapor diffusing thro...

  2. The physical modeling of grain boundary liquation mechanisms within the heat-affected zone of an aluminum-copper alloy

    NASA Astrophysics Data System (ADS)

    Wilson, Andre Lamont

    This dissertation describes the results of a research program which was conducted to physically model, weld heat-affected zone (HAZ) liquation processes observed in Aluminum alloys during welding in the absence of an external strain. Three liquation processes were analyzed using a binary Al-3Cu alloy: (1) intergranular liquid infiltration from the fusion zone; (2) sub-solidus (below the equilibrium solidus temperature) grain boundary liquation due to non-equilibrium segregation during welding; and, (3) sub-solidus liquation (constitutional liquation) of undissolved precipitates in the matrix and along the grain boundary. Silicon, from an Al-Si filler metal, was observed at the base metal, HAZ grain boundaries, of a solution treated Al-3Cu alloy after gas-tungsten arc welding. With no evidence for crack-backfilling, the mechanism of transport of fusion zone material into the matrix was tentatively identified as liquid metal penetration of grain boundaries governed by liquid diffusion kinetics. Grain boundary regions in the heat-affected zone (HAZ) of arc welds, in a solution treated Al-3Cu alloy, were examined for liquation susceptibility. The welding experiments showed that certain grain boundaries, adjacent to the fusion line, were depleted in solute (copper), but were not liquated. Investigation of the third mechanism, involved a comprehensive study of the solid-state, dissolution and liquation-dissolution of matrix and grain boundary precipitates. This represents the first complete study of its type, for any alloy system. The isothermal kinetics of solid-state and liquation-dissolution of theta (Al2Cu) precipitates, were fully quantified during salt bath annealing. The stability of the grain boundary precipitate dispersion was examined in order to determine the susceptibility of the grain boundary microstructure to liquation. These latter experiments were facilitated by a large, "static" grain structure, and this study may mark the first time that any grain

  3. Statistical analysis of factors affecting landslide distribution in the new Madrid seismic zone, Tennessee and Kentucky

    USGS Publications Warehouse

    Jibson, R.W.; Keefer, D.K.

    1989-01-01

    More than 220 large landslides along the bluffs bordering the Mississippi alluvial plain between Cairo, Ill., and Memphis, Tenn., are analyzed by discriminant analysis and multiple linear regression to determine the relative effects of slope height and steepness, stratigraphic variation, slope aspect, and proximity to the hypocenters of the 1811-12 New Madrid, Mo., earthquakes on the distribution of these landslides. Three types of landslides are analyzed: (1) old, coherent slumps and block slides, which have eroded and revegetated features and no active analogs in the area; (2) old earth flows, which are also eroded and revegetated; and (3) young rotational slumps, which are present only along near-river bluffs, and which are the only young, active landslides in the area. Discriminant analysis shows that only one characteristic differs significantly between bluffs with and without young rotational slumps: failed bluffs tend to have sand and clay at their base, which may render them more susceptible to fluvial erosion. Bluffs having old coherent slides are significantly higher, steeper, and closer to the hypocenters of the 1811-12 earthquakes than bluffs without these slides. Bluffs having old earth flows are likewise higher and closer to the earthquake hypocenters. Multiple regression analysis indicates that the distribution of young rotational slumps is affected most strongly by slope steepness: about one-third of the variation in the distribution is explained by variations in slope steepness. The distribution of old coherent slides and earth flows is affected most strongly by slope height, but the proximity to the hypocenters of the 1811-12 earthquakes also significantly affects the distribution. The results of the statistical analyses indicate that the only recently active landsliding in the area is along actively eroding river banks, where rotational slumps formed as bluffs are undercut by the river. The analyses further indicate that the old coherent slides

  4. Gouge Powder from Earthquakes Rupture-zones and Laboratory Rupture Experiments: Sub- microscopic Observations and Particle size Distribution

    NASA Astrophysics Data System (ADS)

    Reches, Z.; Mishima, T. D.; Strout, G.; Lockner, D. A.; Hamilton, M.; Heesakkers, V.

    2007-12-01

    We examine grain features and estimate the particle size distribution (PSD) in gouge collected from three sources: rupture zones of two recent earthquakes in South African mines (m3.7 event in 1997 and m2.2 event in 2004); unstable faulting experiments of quartzite cylinders; and the San Andreas fault-zone at Tejon Pass, California. Studies in nanotechnology indicate that PSD measurements of fine powders are susceptible to major errors due to aggregation and agglomeration of the fine particles that cause a systematic bias toward coarser PSD. Thus, our central analytical objective is to determine the true grain size of the gouge that forms during an earthquake and we have employed several techniques. In the TEM (Jeol-2010F) we use bright-field and dark-field modes for magnifications smaller than 200,000, and FFT-filtering mode for high-resolution (HREM) magnifications of 200,000-500,000. We also test several methods to disperse the agglomerates (with ethanol, silanes and toluene) and measure the PDS in the Dynamic Light Scattering method (using the Zeta particle analyzer ZetaPALS-90Plus of Brookhaven Instruments). The grains in the TEM analyses of eight gouge samples display similar shapes: aspect ratios range up to 1:3 with small amounts of very elongated grains, and most grains are angular to very angular while grains of the rock mechanics experiment are the most angular. The samples display wide ranges of grain sizes (5 nm to 5 microns), however, quantitative PSD cannot be determined as most (if not all) grains appear in clusters and aggregates that are hardly separable in the bright-field mode. We thus use the dark-field and FFT-filter methods to map the internal structure of tens of grains ranging in size from a few nanometers to about 2 microns. With a few exceptions, all examined grains are composites of 3 to more than 15 (and probably more) secondary grains that are as small as a few nanometers in size. The PSD of these samples is measured with the Zeta

  5. The likelihood of being affected with Huntington disease by a particular age, for a specific CAG size.

    PubMed Central

    Brinkman, R R; Mezei, M M; Theilmann, J; Almqvist, E; Hayden, M R

    1997-01-01

    Prior studies describing the relationship between CAG size and the age at onset of Huntington disease (HD) have focused on affected persons. To further define the relationship between CAG repeat size and age at onset of HD, we now have analyzed a large cohort of affected and asymptomatic at-risk persons with CAG expansion. This cohort numbered 1,049 persons, including 321 at-risk and 728 affected individuals with a CAG size of 29-121 repeats. Kaplan-Meier analysis has provided curves for determining the likelihood of onset at a given age, for each CAG repeat length in the 39-50 range. The curves were significantly different (P < .0005), with relatively narrow 95% confidence intervals (95% CI) (+/-10%). Penetrance of the mutation for HD also was examined. Although complete penetrance of HD was observed for CAG sizes of > or = 42, only a proportion of those with a CAG repeat length of 36-41 showed signs or symptoms of HD within a normal life span. These data provide information concerning the likelihood of being affected, by a specific age, with a particular CAG size, and they may be useful in predictive-testing programs and for the design of clinical trials for persons at increased risk for HD. PMID:9150168

  6. Remote sensing for assessing the zone of benefit where deep drains improve productivity of land affected by shallow saline groundwater.

    PubMed

    Kobryn, H T; Lantzke, R; Bell, R; Admiraal, R

    2015-03-01

    The installation of deep drains is an engineering approach to remediate land salinised by the influence of shallow groundwater. It is a costly treatment and its economic viability is, in part, dependent on the lateral extent to which the drain increases biological productivity by lowering water tables and soil salinity (referred to as the drains' zone of benefit). Such zones may be determined by assessing the biological productivity response of adjacent vegetation over time. We tested a multi-temporal satellite remote sensing method to analyse temporal and spatial changes in vegetation condition surrounding deep drainage sites at five locations in the Western Australian wheatbelt affected by dryland salinity-Morawa, Pithara, Beacon, Narembeen and Dumbleyung. Vegetation condition as a surrogate for biological productivity was assessed by Normalised Difference Vegetation Index (NDVI) during the peak growing season. Analysis was at the site scale within a 1000 m buffer zone from the drains. There was clear evidence of NDVI increasing with elevation, slope and distance from the drain. After accounting for elevation, slope and distance from the drain, there was a significant increase in NDVI across the five locations after installation of deep drains. Changes in NDVI after drainage were broadly consistent with measured changes at each site in groundwater levels after installation of the deep drains. However, this study assessed the lateral extent of benefit for biological productivity and gave a measure of the area of benefit along the entire length of the drain. The method demonstrated the utility of spring NDVI images for rapid and relatively simple assessment of the change in site condition after implementation of drainage, but approaches for further improvement of the procedure were identified. PMID:25481499

  7. Linking river, floodplain, and vadose zone hydrology to improve restoration of a coastal river affected by saltwater intrusion.

    PubMed

    Kaplan, D; Muñoz-Carpena, R; Wan, Y; Hedgepeth, M; Zheng, F; Roberts, R; Rossmanith, R

    2010-01-01

    Floodplain forests provide unique ecological structure and function, which are often degraded or lost when watershed hydrology is modified. Restoration of damaged ecosystems requires an understanding of surface water, groundwater, and vadose (unsaturated) zone hydrology in the floodplain. Soil moisture and porewater salinity are of particular importance for seed germination and seedling survival in systems affected by saltwater intrusion but are difficult to monitor and often overlooked. This study contributes to the understanding of floodplain hydrology in one of the last bald cypress [Taxodium distichum (L.) Rich.] floodplain swamps in southeast Florida. We investigated soil moisture and porewater salinity dynamics in the floodplain of the Loxahatchee River, where reduced freshwater flow has led to saltwater intrusion and a transition to salt-tolerant, mangrove-dominated communities. Twenty-four dielectric probes measuring soil moisture and porewater salinity every 30 min were installed along two transects-one in an upstream, freshwater location and one in a downstream tidal area. Complemented by surface water, groundwater, and meteorological data, these unique 4-yr datasets quantified the spatial variability and temporal dynamics of vadose zone hydrology. Results showed that soil moisture can be closely predicted based on river stage and topographic elevation (overall Nash-Sutcliffe coefficient of efficiency = 0.83). Porewater salinity rarely exceeded tolerance thresholds (0.3125 S m(-1)) for bald cypress upstream but did so in some downstream areas. This provided an explanation for observed vegetation changes that both surface water and groundwater salinity failed to explain. The results offer a methodological and analytical framework for floodplain monitoring in locations where restoration success depends on vadose zone hydrology and provide relationships for evaluating proposed restoration and management scenarios for the Loxahatchee River. PMID:21043263

  8. Climate change affects low trophic level marine consumers: warming decreases copepod size and abundance.

    PubMed

    Garzke, Jessica; Ismar, Stefanie M H; Sommer, Ulrich

    2015-03-01

    Concern about climate change has re-ignited interest in universal ecological responses to temperature variations: (1) biogeographical shifts, (2) phenology changes, and (3) size shifts. In this study we used copepods as model organisms to study size responses to temperature because of their central role in the pelagic food web and because of the ontogenetic length constancy between molts, which facilitates the definition of size of distinct developmental stages. In order to test the expected temperature-induced shifts towards smaller body size and lower abundances under warming conditions, a mesocosm experiment using plankton from the Baltic Sea at three temperature levels (ambient, ambient +4 °C, ambient -4 °C) was performed in summer 2010. Overall copepod and copepodit abundances, copepod size at all life stages, and adult copepod size in particular, showed significant temperature effects. As expected, zooplankton peak abundance was lower in warm than in ambient treatments. Copepod size-at-immature stage significantly increased in cold treatments, while adult size significantly decreased in warm treatments. PMID:25413864

  9. Modeling phase transformation behavior during thermal cycling in the heat-affected zone of stainless steel welds

    SciTech Connect

    Vitek, J.M.; Iskander, Y.S.; David, S.A.

    1995-12-31

    An implicit finite-difference analysis was used to model the diffusion-controlled transformation behavior in a ternary system. The present analysis extends earlier work by examining the transformation behavior under the influence of multiple thermal cycles. The analysis was applied to the Fe-Cr-Ni ternary system to simulate the microstructural development in austenitic stainless steel welds. The ferrite-to-austenite transformation was studied in an effort to model the response of the heat-affected zone to multiple thermal cycles experienced during multipass welding. Results show that under some conditions, a transformation ``inertia`` exists that delays the system`s response when changing from cooling to heating. Conditions under which this ``inertia`` is most influential were examined. It was also found that under some conditions, the transformation behavior does not follow the equilibrium behavior as a function of temperature. Results also provide some insight into effect of composition distribution on transformation behavior.

  10. Cleavage initiation in the intercritically reheated coarse-grained heat affected zone. Part 2: Failure criteria and statistical effects

    SciTech Connect

    Davis, C.L.; King, J.E.

    1996-10-01

    In part 1 of this article, cleavage initiation in the intercritically reheated coarse-grained heat affected zone (IC CG HAZ) of high-strength low-alloy (HSLA) steels was determined to occur between two closely spaced blocky MA particles. Blunt notch, crack tip opening displacement (CTOD), and precracked Charpy testing were used in this investigation to determine the failure criteria required for cleavage initiation to occur by this mechanism in the IC CG HAZ. It was found that the attainment of a critical level of strain was required in addition to a critical level of stress. This does not occur in the case of high strain rate testing, for example, during precracked Charpy testing. A different cleavage initiation mechanism is then found to operate. The precise fracture criteria and microstructural requirements (described in part 1 of this article) result in competition between potential cleavage initiation mechanisms in the IC CG HAZ.

  11. Case Study: Pitting and Stress Corrosion Cracking in Heat-Affected Zone of Welded Underground 304 Stainless Steel Pipe

    NASA Astrophysics Data System (ADS)

    Tawancy, H. M.; Al-Hadhrami, Luai. M.

    2012-08-01

    A jacketed underground pipeline made of 304 stainless steel tubing to transport utility water in a petrochemical plant at ambient temperature was perforated after few months of operation. Perforation started preferentially at the outer bottom surface of the pipe in the weld heat-affected zones where the insulating coating was damaged. Detailed microstructural characterization was carried out to determine the cause of failure using optical metallography, x-ray diffraction, scanning electron microscopy combined with energy dispersive spectroscopy, and transmission electron microscopy. Experimental results indicated that the failure occurred by interaction between the outer bottom surface of the pipe and surrounding environment leading to pitting and stress corrosion cracking in the presence of chloride ions. This could have been aided by residual welding stresses and the characteristic low stacking fault energy of the material.

  12. Factors affecting the quality of fish caught by Native Americans in the Zone 6 fishery 1991 through 1993

    SciTech Connect

    Abernethy, C.S.

    1994-09-01

    A program to monitor the salmon and steelhead (Oncorhynchus spp.) fishery in the lower Columbia River (Zone 6 fishery) was initiated in 1991 to respond to questions and comments frequently made by Native Americans at public meetings. Native Americans were concerned that the quality of the Columbia River had deteriorated and that the poor environmental conditions had affected the health and quality of fish they relied on for subsistence, ceremonial, religious, and commercial purposes. They also feared that eating contaminated fish might endanger the health of their children and future generations. Operations at the Hanford Site were listed as one of many causes of the deteriorating environment. Fisheries pathologists concluded that most of the external symptoms on fish were related to bacterial infection of gill net abrasions and pre-spawning trauma, and were not caused by pollution or contamination of the Columbia River. The pathologists also stated that consumption of the fish posed no threat to human consumers.

  13. Influence of timing of sea ice retreat on phytoplankton size during marginal ice zone bloom period on the Chukchi and Bering shelves

    NASA Astrophysics Data System (ADS)

    Fujiwara, A.; Hirawake, T.; Suzuki, K.; Eisner, L.; Imai, I.; Nishino, S.; Kikuchi, T.; Saitoh, S.-I.

    2016-01-01

    The size structure and biomass of a phytoplankton community during the spring bloom period can affect the energy use of higher-trophic-level organisms through the predator-prey body size relationships. The timing of the sea ice retreat (TSR) also plays a crucial role in the seasonally ice-covered marine ecosystem, because it is tightly coupled with the timing of the spring bloom. Thus, it is important to monitor the temporal and spatial distributions of a phytoplankton community size structure. Prior to this study, an ocean colour algorithm was developed to derive phytoplankton size index FL, which is defined as the ratio of chlorophyll a (chl a) derived from cells larger than 5 µm to the total chl a, using satellite remote sensing for the Chukchi and Bering shelves. Using this method, we analysed the pixel-by-pixel relationships between FL during the marginal ice zone (MIZ) bloom period and TSR over the period of 1998-2013. The influences of the TSR on the sea surface temperature (SST) and changes in ocean heat content (ΔOHC) during the MIZ bloom period were also investigated. A significant negative relationship between FL and the TSR was widely found in the shelf region during the MIZ bloom season. However, we found a significant positive (negative) relationship between the SST (ΔOHC) and TSR. Specifically, an earlier sea ice retreat was associated with the dominance of larger phytoplankton during a colder and weakly stratified MIZ bloom season, suggesting that the duration of the nitrate supply, which is important for the growth of large-sized phytoplankton in this region (i.e. diatoms), can change according to the TSR. In addition, under-ice phytoplankton blooms are likely to occur in years with late ice retreat, because sufficient light for phytoplankton growth can pass through the ice and penetrate into the water columns as a result of an increase in solar radiation toward the summer solstice

  14. Both population size and patch quality affect local extinctions and colonizations.

    PubMed

    Franzén, Markus; Nilsson, Sven G

    2010-01-01

    Currently, the habitat of many species is fragmented, resulting in small local populations with individuals occasionally dispersing between the remaining habitat patches. In a solitary bee metapopulation, extinction probability was related to both local bee population sizes and pollen resources measured as host plant population size. Patch size, on the other hand, had no additional predictive power. The turnover rate of local bee populations in 63 habitat patches over 4 years was high, with 72 extinction events and 31 colonization events, but the pollen plant population was stable with no extinctions or colonizations. Both pollen resources and bee populations had strong and independent effects on extinction probability, but connectivity was not of importance. Colonizations occurred more frequently within larger host plant populations. For metapopulation survival of the bee, large pollen plant populations are essential, independent of current bee population size. PMID:19793747

  15. Body ownership affects visual perception of object size by rescaling the visual representation of external space.

    PubMed

    van der Hoort, Björn; Ehrsson, H Henrik

    2014-07-01

    Size perception is most often explained by a combination of cues derived from the visual system. However, this traditional cue approach neglects the role of the observer's body beyond mere visual comparison. In a previous study, we used a full-body illusion to show that objects appear larger and farther away when participants experience a small artificial body as their own and that objects appear smaller and closer when they assume ownership of a large artificial body ("Barbie-doll illusion"; van der Hoort, Guterstam, & Ehrsson, PLoS ONE, 6(5), e20195, 2011). The first aim of the present study was to test the hypothesis that this own-body-size effect is distinct from the role of the seen body as a direct familiar-size cue. To this end, we developed a novel setup that allowed for occlusion of the artificial body during the presentation of test objects. Our results demonstrate that the feeling of ownership of an artificial body can alter the perceived sizes of objects without the need for a visible body. Second, we demonstrate that fixation shifts do not contribute to the own-body-size effect. Third, we show that the effect exists in both peri-personal space and distant extra-personal space. Finally, through a meta-analysis, we demonstrate that the own-body-size effect is independent of and adds to the classical visual familiar-size cue effect. Our results suggest that, by changing body size, the entire spatial layout rescales and new objects are now perceived according to this rescaling, without the need to see the body. PMID:24806404

  16. Particulate Size of Microalgal Biomass Affects Hydrolysate Properties and Bioethanol Concentration

    PubMed Central

    Harun, Razif; Danquah, Michael K.; Thiruvenkadam, Selvakumar

    2014-01-01

    Effective optimization of microalgae-to-bioethanol process systems hinges on an in-depth characterization of key process parameters relevant to the overall bioprocess engineering. One of the such important variables is the biomass particle size distribution and the effects on saccharification levels and bioethanol titres. This study examined the effects of three different microalgal biomass particle size ranges, 35 μm ≤ x ≤ 90 μm, 125 μm ≤ x ≤ 180 μm, and 295 μm ≤ x ≤ 425 μm, on the degree of enzymatic hydrolysis and bioethanol production. Two scenarios were investigated: single enzyme hydrolysis (cellulase) and double enzyme hydrolysis (cellulase and cellobiase). The glucose yield from biomass in the smallest particle size range (35 μm ≤ x ≤ 90 μm) was the highest, 134.73 mg glucose/g algae, while the yield from biomass in the larger particle size range (295 μm ≤ x ≤ 425 μm) was 75.45 mg glucose/g algae. A similar trend was observed for bioethanol yield, with the highest yield of 0.47 g EtOH/g glucose obtained from biomass in the smallest particle size range. The results have shown that the microalgal biomass particle size has a significant effect on enzymatic hydrolysis and bioethanol yield. PMID:24971327

  17. Habitat traits and species interactions differentially affect abundance and body size in pond-breeding amphibians.

    PubMed

    Ousterhout, Brittany H; Anderson, Thomas L; Drake, Dana L; Peterman, William E; Semlitsch, Raymond D

    2015-07-01

    In recent studies, habitat traits have emerged as stronger predictors of species occupancy, abundance, richness and diversity than competition. However, in many cases, it remains unclear whether habitat also mediates processes more subtle than competitive exclusion, such as growth, or whether intra- and interspecific interactions among individuals of different species may be better predictors of size. To test whether habitat traits are a stronger predictor of abundance and body size than intra- and interspecific interactions, we measured the density and body size of three species of larval salamanders in 192 ponds across a landscape. We found that the density of larvae was best predicted by models that included habitat features, while models incorporating interactions among individuals of different species best explained the body size of larvae. Additionally, we found a positive relationship between focal species density and congener density, while focal species body size was negatively related to congener density. We posit that salamander larvae may not experience competitive exclusion and thus reduced densities, but instead compensate for increased competition behaviourally (e.g. reduced foraging), resulting in decreased growth. The discrepancy between larval density and body size, a strong predictor of fitness in this system, also highlights a potential shortcoming in using density or abundance as a metric of habitat quality or population health. PMID:25643605

  18. Does Litter Size Variation Affect Models of Terrestrial Carnivore Extinction Risk and Management?

    PubMed Central

    Devenish-Nelson, Eleanor S.; Stephens, Philip A.; Harris, Stephen; Soulsbury, Carl; Richards, Shane A.

    2013-01-01

    Background Individual variation in both survival and reproduction has the potential to influence extinction risk. Especially for rare or threatened species, reliable population models should adequately incorporate demographic uncertainty. Here, we focus on an important form of demographic stochasticity: variation in litter sizes. We use terrestrial carnivores as an example taxon, as they are frequently threatened or of economic importance. Since data on intraspecific litter size variation are often sparse, it is unclear what probability distribution should be used to describe the pattern of litter size variation for multiparous carnivores. Methodology/Principal Findings We used litter size data on 32 terrestrial carnivore species to test the fit of 12 probability distributions. The influence of these distributions on quasi-extinction probabilities and the probability of successful disease control was then examined for three canid species – the island fox Urocyon littoralis, the red fox Vulpes vulpes, and the African wild dog Lycaon pictus. Best fitting probability distributions differed among the carnivores examined. However, the discretised normal distribution provided the best fit for the majority of species, because variation among litter-sizes was often small. Importantly, however, the outcomes of demographic models were generally robust to the distribution used. Conclusion/Significance These results provide reassurance for those using demographic modelling for the management of less studied carnivores in which litter size variation is estimated using data from species with similar reproductive attributes. PMID:23469140

  19. Does population size affect genetic diversity? A test with sympatric lizard species.

    PubMed

    Hague, M T J; Routman, E J

    2016-01-01

    Genetic diversity is a fundamental requirement for evolution and adaptation. Nonetheless, the forces that maintain patterns of genetic variation in wild populations are not completely understood. Neutral theory posits that genetic diversity will increase with a larger effective population size and the decreasing effects of drift. However, the lack of compelling evidence for a relationship between genetic diversity and population size in comparative studies has generated some skepticism over the degree that neutral sequence evolution drives overall patterns of diversity. The goal of this study was to measure genetic diversity among sympatric populations of related lizard species that differ in population size and other ecological factors. By sampling related species from a single geographic location, we aimed to reduce nuisance variance in genetic diversity owing to species differences, for example, in mutation rates or historical biogeography. We compared populations of zebra-tailed lizards and western banded geckos, which are abundant and short-lived, to chuckwallas and desert iguanas, which are less common and long-lived. We assessed population genetic diversity at three protein-coding loci for each species. Our results were consistent with the predictions of neutral theory, as the abundant species almost always had higher levels of haplotype diversity than the less common species. Higher population genetic diversity in the abundant species is likely due to a combination of demographic factors, including larger local population sizes (and presumably effective population sizes), faster generation times and high rates of gene flow with other populations. PMID:26306730

  20. Habitat richness affects home range size in a monogamous large rodent.

    PubMed

    Lovari, Sandro; Sforzi, Andrea; Mori, Emiliano

    2013-10-01

    In monogamous species, after pair formation, the main reason for ranging movements is not searching for a mate, but for other important resources e.g. food. We monitored a total of 20 radio-tagged adult, paired crested porcupines in four areas of different habitat richness. No sexual size dimorphism was assessed. Body mass and habitat richness showed collinearity. For both sexes, home range size was correlated to habitat richness, with a significant inverse exponential regression. Opposite to natural foragers, living in poor habitats, crop foragers had smaller home ranges, with their dens significantly closer to cultivations. Both availability of food resources and den sites are key variables to determine home range size. PMID:23796772

  1. Effects of Fusion Zone Size and Failure Mode on Peak Load and Energy Absorption of Advanced High Strength Steel Spot Welds under Lap Shear Loading Conditions

    SciTech Connect

    Sun, Xin; Stephens, Elizabeth V.; Khaleel, Mohammad A.

    2008-06-01

    This paper examines the effects of fusion zone size on failure modes, static strength and energy absorption of resistance spot welds (RSW) of advanced high strength steels (AHSS) under lap shear loading condition. DP800 and TRIP800 spot welds are considered. The main failure modes for spot welds are nugget pullout and interfacial fracture. Partial interfacial fracture is also observed. Static weld strength tests using lap shear samples were performed on the joint populations with various fusion zone sizes. The resulted peak load and energy absorption levels associated with each failure mode were studied for all the weld populations using statistical data analysis tools. The results in this study show that AHSS spot welds with conventionally required fusion zone size of can not produce nugget pullout mode for both the DP800 and TRIP800 welds under lap shear loading. Moreover, failure mode has strong influence on weld peak load and energy absorption for all the DP800 welds and the TRIP800 small welds: welds failed in pullout mode have statistically higher strength and energy absorption than those failed in interfacial fracture mode. For TRIP800 welds above the critical fusion zone level, the influence of weld failure modes on peak load and energy absorption diminishes. Scatter plots of peak load and energy absorption versus weld fusion zone size were then constructed, and the results indicate that fusion zone size is the most critical factor in weld quality in terms of peak load and energy absorption for both DP800 and TRIP800 spot welds.

  2. Perturbation of nucleo-cytoplasmic transport affects size of nucleus and nucleolus in human cells.

    PubMed

    Ganguly, Abira; Bhattacharjee, Chumki; Bhave, Madhura; Kailaje, Vaishali; Jain, Bhawik K; Sengupta, Isha; Rangarajan, Annapoorni; Bhattacharyya, Dibyendu

    2016-03-01

    Size regulation of human cell nucleus and nucleolus are poorly understood subjects. 3D reconstruction of live image shows that the karyoplasmic ratio (KR) increases by 30-80% in transformed cell lines compared to their immortalized counterpart. The attenuation of nucleo-cytoplasmic transport causes the KR value to increase by 30-50% in immortalized cell lines. Nucleolus volumes are significantly increased in transformed cell lines and the attenuation of nucleo-cytoplasmic transport causes a significant increase in the nucleolus volume of immortalized cell lines. A cytosol and nuclear fraction swapping experiment emphasizes the potential role of unknown cytosolic factors in nuclear and nucleolar size regulation. PMID:26813731

  3. Propagule size and predispersal damage by insects affect establishment and early growth of mangrove seedlings.

    PubMed

    Sousa, Wayne P; Kennedy, Peter G; Mitchell, Betsy J

    2003-05-01

    Variation in rates of seedling recruitment, growth, and survival can strongly influence the rate and course of forest regeneration following disturbance. Using a combination of field sampling and shadehouse experiments, we investigated the influence of propagule size and predispersal insect damage on the establishment and early growth of the three common mangrove species on the Caribbean coast of Panama: Avicennia germinans, Laguncularia racemosa, and Rhizophora mangle. In our field samples, all three species exhibited considerable intraspecific variation in mature propagule size, and suffered moderate to high levels of predispersal attack by larval insects. Rates of insect attack were largely independent of propagule size both within and among trees. Our experimental studies using undamaged mature propagules showed that, for all three species, seedlings established at high rates regardless of propagule size. However, propagule size did have a marked effect on early seedling growth: seedlings that developed from larger propagules grew more rapidly. Predispersal insect infestations that had destroyed or removed a substantial amount of tissue, particularly if that tissue was meristematic or conductive, reduced the establishment of propagules of all three species. The effect of sublethal tissue damage or loss on the subsequent growth of established seedlings varied among the three mangrove species. For Avicennia, the growth response was graded: for a propagule of a given size, the more tissue lost, the slower the growth of the seedling. For Laguncularia, the response to insect attack appeared to be all-or-none. If the boring insect penetrated the outer spongy seed coat and reached the developing embryo, it usually caused sufficient damage to prevent a seedling from developing. On the other hand, if the insect damaged but did not penetrate the seed coat, a completely healthy seedling developed and its growth rate was indistinguishable from a seedling developing from an

  4. Why does offspring size affect performance? Integrating metabolic scaling with life-history theory.

    PubMed

    Pettersen, Amanda K; White, Craig R; Marshall, Dustin J

    2015-11-22

    Within species, larger offspring typically outperform smaller offspring. While the relationship between offspring size and performance is ubiquitous, the cause of this relationship remains elusive. By linking metabolic and life-history theory, we provide a general explanation for why larger offspring perform better than smaller offspring. Using high-throughput respirometry arrays, we link metabolic rate to offspring size in two species of marine bryozoan. We found that metabolism scales allometrically with offspring size in both species: while larger offspring use absolutely more energy than smaller offspring, larger offspring use proportionally less of their maternally derived energy throughout the dependent, non-feeding phase. The increased metabolic efficiency of larger offspring while dependent on maternal investment may explain offspring size effects-larger offspring reach nutritional independence (feed for themselves) with a higher proportion of energy relative to structure than smaller offspring. These findings offer a potentially universal explanation for why larger offspring tend to perform better than smaller offspring but studies on other taxa are needed. PMID:26559952

  5. Factors Affecting Teachers' Adoption of Technology in Classrooms: Does School Size Matter?

    ERIC Educational Resources Information Center

    Wu, Hsin-Kai; Hsu, Ying-Shao; Hwang, Fu-Kwun

    2008-01-01

    Researchers in educational technology have searched for factors to explain teachers' acceptance and resistance to using technology for instruction. Among the many identified factors, however, organizational and school factors have not yet been explored and discussed. This study investigates the effects of school size on science and mathematics…

  6. Primary particle size distribution of eroded material affected by degree of aggregate slaking and seal development

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Primary particle size distribution (PSD) of eroded sediments can be used to estimate potential nutrient losses from soil and pollution hazards to the environment. We studied eroded sediment PSDs from three saturated soils, packed in trays (20 x 40 x 4 cm), that had undergone either minimal aggregate...

  7. Navy bean flour particle size and protein content affect cake baking and batter quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Whole navy bean flour and its fine and coarse particle size fractions were used to completely replace wheat flour in cakes. Replacement of wheat flour with whole bean flour significantly increased the protein content. The protein content was adjusted to three levels with navy bean starch. The effect...

  8. Do Birth Order, Family Size and Gender Affect Arithmetic Achievement in Elementary School?

    ERIC Educational Resources Information Center

    Desoete, Annemie

    2008-01-01

    Introduction: For decades birth order and gender differences have attracted research attention. Method: Birth order, family size and gender, and the relationship with arithmetic achievement is studied among 1152 elementary school children (540 girls, 612 boys) in Flanders. Children were matched on socioeconomic status of the parents and…

  9. Foraging mode affects the evolution of egg size in generalist predators embedded in complex food webs.

    PubMed

    Verdeny-Vilalta, O; Fox, C W; Wise, D H; Moya-Laraño, J

    2015-06-01

    Ecological networks incorporate myriad biotic interactions that determine the selection pressures experienced by the embedded populations. We argue that within food webs, the negative scaling of abundance with body mass and foraging theory predict that the selective advantages of larger egg size should be smaller for sit-and-wait than active-hunting generalist predators, leading to the evolution of a difference in egg size between them. Because body mass usually scales negatively with predator abundance and constrains predation rate, slightly increasing egg mass should simultaneously allow offspring to feed on more prey and escape from more predators. However, the benefits of larger offspring would be relatively smaller for sit-and-wait predators because (i) due to their lower mobility, encounters with other predators are less common, and (ii) they usually employ a set of alternative hunting strategies that help to subdue relatively larger prey. On the other hand, for active predators, which need to confront prey as they find them, body-size differences may be more important in subduing prey. This difference in benefits should lead to the evolution of larger egg sizes in active-hunting relative to sit-and-wait predators. This prediction was confirmed by a phylogenetically controlled analysis of 268 spider species, supporting the view that the structure of ecological networks may serve to predict relevant selective pressures acting on key life history traits. PMID:25882583

  10. Mating status and body size in Aedes albopictus (Diptera: Culicidae) affect host finding and DEET repellency

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Variations in the conditions accompanying mosquito development and mating can result in females of variable size that have not been inseminated. In this study, we compared the host finding activity of mated and unmated large and small Aedes albopictus and the repellency to these mosquitoes of 25% D...

  11. Distribution of metals in various particle-size fractions in topsoil of a gully system (European Russia, forest zone)

    NASA Astrophysics Data System (ADS)

    Samonova, Olga; Aseyeva, Elena

    2014-05-01

    Being depressions in a relief gullies often serve as locations for illegal dumping of hazardous substances, which may be mobilized, retained or recycled during the transport. In the present study we analyze concentrations and distributions of Fe, Ti and potentially hazardous trace elements in various grain-size fractions of a gully's topsoil and focus on examination of spatial variations and grain-size effect. The study object is located in the southern taiga zone of European Russia and represents a relatively young erosional landform, incised in Quaternary deposits. It has a simple rhomboid plan view and the length of about 200 m. Sampling of cross-sectional and longitudinal sequences of soils was performed. In total 25 samples of surface soil horizons were collected in different positions of the system including its internal (slopes, bottom, detrial fan) and external (watershed) units. The distributions of Fe, Ti, Mn, Cu, Ni, Co, Cr, Zn, Pb, Zr were analyzed in undifferentiated samples and in particle-size fractions: coarse and medium sand (1-0,25 mm), fine and very fine sand (0,25-0,05 mm), coarse silt (0,05-0,01 mm), medium and fine silt (0,01-0,001 mm) and clay (<0,001 mm). The concentrations of the studied metals in total sample population vary differently in each particle-size fraction: for the majority of elements the variations are diminishing from coarser to finer fractions. Clearly defined relationship between fraction size and metal concentrations is typical of Ti and Zr. The highest levels of Ti are found in silt fractions, while concentrations of Zr show highest values in coarse silt and finer sand fraction. The concentrations of many elements (Mn, Co, Ni, Cr, Zn) are generally higher in clay fractions than in other fractions while the concentrations of Cu and Pb are higher in medium and fine silt. The comparison between the samples collected in different landform positions revealed that soil material in the gully's bottom in all size fractions

  12. How the Assumed Size Distribution of Dust Minerals Affects the Predicted Ice Forming Nuclei

    NASA Technical Reports Server (NTRS)

    Perlwitz, Jan P.; Fridlind, Ann M.; Garcia-Pando, Carlos Perez; Miller, Ron L.; Knopf, Daniel A.

    2015-01-01

    The formation of ice in clouds depends on the availability of ice forming nuclei (IFN). Dust aerosol particles are considered the most important source of IFN at a global scale. Recent laboratory studies have demonstrated that the mineral feldspar provides the most efficient dust IFN for immersion freezing and together with kaolinite for deposition ice nucleation, and that the phyllosilicates illite and montmorillonite (a member of the smectite group) are of secondary importance.A few studies have applied global models that simulate mineral specific dust to predict the number and geographical distribution of IFN. These studies have been based on the simple assumption that the mineral composition of soil as provided in data sets from the literature translates directly into the mineral composition of the dust aerosols. However, these tables are based on measurements of wet-sieved soil where dust aggregates are destroyed to a large degree. In consequence, the size distribution of dust is shifted to smaller sizes, and phyllosilicates like illite, kaolinite, and smectite are only found in the size range 2 m. In contrast, in measurements of the mineral composition of dust aerosols, the largest mass fraction of these phyllosilicates is found in the size range 2 m as part of dust aggregates. Conversely, the mass fraction of feldspar is smaller in this size range, varying with the geographical location. This may have a significant effect on the predicted IFN number and its geographical distribution.An improved mineral specific dust aerosol module has been recently implemented in the NASA GISS Earth System ModelE2. The dust module takes into consideration the disaggregated state of wet-sieved soil, on which the tables of soil mineral fractions are based. To simulate the atmospheric cycle of the minerals, the mass size distribution of each mineral in aggregates that are emitted from undispersed parent soil is reconstructed. In the current study, we test the null

  13. Interannual Variability in Carbon and Nitrogen Stable Isotopic Signatures of Size-Fractionated POM from the South Florida Coastal Zone

    NASA Astrophysics Data System (ADS)

    Evans, S. L.; Anderson, W. T.; Jochem, F. J.; Fourqurean, J. W.

    2004-12-01

    Environmental conditions in South Florida coastal waters have been of local and national concern over the past 15 years. Attention has focused on the ecosystem impacts of salinity increases, seagrass die-off, increased algal bloom frequency, waste water influence, groundwater discharge, and exchange between Florida Bay, the Gulf of Mexico, and the Atlantic Ocean. Changes in water quality and productivity levels may be reflected in the isotopic signatures of coastal zone primary producers. Recent work with seagrasses in South Florida has demonstrated high seasonal and spatial variability in C and N isotopic signatures and decoupling between the two isotopic systems as they vary. To better understand the sources of seasonal and spatial fluctuation, size fractionated POM (particulate organic matter) samples have been collected on a quarterly basis since Sept. 2002. Fractions collected include >150μ m, 50-150μ m, and 0.1-50μ m using Nitex mesh sieves and a portable pump system deployed from a small boat at 10 sites around the Florida Keys and Florida Bay. It was hypothesized that planktonic groups respond more quickly to changes in water quality then seagrasses, and thus variations may be more clearly attributed to environmental parameters. Significant spatial and temporal variability is evident both within site between size fractions and between sites. Seasonal oscillations of up to 4‰ were observed in N isotopic values and 6‰ in C isotopic values of the 50-150μ m size fraction, which is dominated by diatoms and dinoflagellates. δ 13C values are depleted in the late winter/early spring sampling period possibly reflecting decreased productivity stress on available C pools. 13C depletion is generally coincident with δ 15N enrichment in the late winter/early spring, possibly demonstrating changes in DIN pools (NO3- and NH4+ concentrations) or changes in decomposition or denitrification rates. Broad groupings appear to separate Atlantic coral reef sites

  14. Orthographic Consistency Affects Spoken Word Recognition at Different Grain-Sizes

    ERIC Educational Resources Information Center

    Dich, Nadya

    2014-01-01

    A number of previous studies found that the consistency of sound-to-spelling mappings (feedback consistency) affects spoken word recognition. In auditory lexical decision experiments, words that can only be spelled one way are recognized faster than words with multiple potential spellings. Previous studies demonstrated this by manipulating…

  15. Gum tragacanth dispersions: Particle size and rheological properties affected by high-shear homogenization.

    PubMed

    Farzi, Mina; Yarmand, Mohammad Saeed; Safari, Mohammad; Emam-Djomeh, Zahra; Mohammadifar, Mohammad Amin

    2015-08-01

    The effect of high-shear homogenization on the rheological and particle size characteristics of three species of gum tragacanth (GT) was detected. Dispersions were subjected to 0-20 min treatment. Static light scattering techniques and rheological tests were used to study the effect of treatment. The results showed that the process caused a decrease in particle size parameters for all three species, but interestingly, the apparent viscosities increased. The highest increase of apparent viscosity was found for solutions containing Astragalus gossypinus, which possessed the highest insoluble fraction. The viscoelastic behaviors of dispersions were also significantly influenced by the process. Homogenization caused an increase in both G' and G″, in all three species. The alterations seem to be highly dependent on GT species and structure. The results could be of high importance in the industry, since the process will lead to textural modifications of food products containing GT. PMID:25987462

  16. Does size and buoyancy affect the long-distance transport of floating debris?

    NASA Astrophysics Data System (ADS)

    Ryan, Peter G.

    2015-08-01

    Floating persistent debris, primarily made from plastic, disperses long distances from source areas and accumulates in oceanic gyres. However, biofouling can increase the density of debris items to the point where they sink. Buoyancy is related to item volume, whereas fouling is related to surface area, so small items (which have high surface area to volume ratios) should start to sink sooner than large items. Empirical observations off South Africa support this prediction: moving offshore from coastal source areas there is an increase in the size of floating debris, an increase in the proportion of highly buoyant items (e.g. sealed bottles, floats and foamed plastics), and a decrease in the proportion of thin items such as plastic bags and flexible packaging which have high surface area to volume ratios. Size-specific sedimentation rates may be one reason for the apparent paucity of small plastic items floating in the world’s oceans.

  17. Formation of vitamin E emulsion stabilized by octenylsuccinic starch: factors affecting particle size and oil load.

    PubMed

    Qiu, Dan; Yang, Lei; Shi, Yong-Cheng

    2015-04-01

    Vitamin E (VE) emulsions were formed by adding VE acetate in an octenylsuccinic (OS) starch solution with distilled water and homogenizing with a microfluidizer at 20000 psi. The objective of this study was to investigate the effects of total concentration of starch and oil, ratio of oil to starch, pH value, and free OS content on emulsion properties. A method using HPLC was developed to analyze VE in emulsion, and the results were used to estimate the amount of surface VE oil. Lower total concentration of starch and oil and lower ratio of oil to starch resulted in more stable emulsions, whereas differences in the pH between 3 and 8 had little effect. Free OS content increased with greater particle size and decreased oil load. Increasing the number of passes reduced the initial particle size of the emulsion but increased free OS content. PMID:25808448

  18. Flocculation and particle size analysis of expansive clay sediments affected by biological, chemical, and hydrodynamic factors

    NASA Astrophysics Data System (ADS)

    Tan, Xiaoling; Hu, Liming; Reed, Allen H.; Furukawa, Yoko; Zhang, Guoping

    2014-01-01

    Expansive clay sediments are abundant in riverine and estuarine waters and bottom beds, and their particle size distributions (PSD) are important for the analysis of sediment transport. This paper presents an experimental study to evaluate, using a laser particle size analyzer under varying flow conditions, the intrinsic PSD of two expansive clays, a Ca- and a Na-montmorillonite and the influence of biological, chemical, and hydrodynamic factors on their flocculation and PSD. The considered biological factor consists of three extracellular polymeric substances of varying polarity, including xanthan gum, guar gum, and chitosan; the chemical factor is the salinity; and the hydrodynamic factor is the types of flow indicated by the Reynolds number and shear rate. The intrinsic PSD of both clays show a multimodal lognormal distribution with sizes ranging from 0.2 to 50 μm. All three biopolymers, xanthan gum, guar gum, and chitosan, can facilitate flocculation through long-range polymer bridging and short-range ion-dipole interaction, hydrogen bonding, and Coulomb force. The influence of salinity is different for the two clays: the particle size of the Na-montmorillonite increases with salinity, which is caused by flocculation resulting from the suppressed electrical double layer, while that of the Ca-montmorillonite is slightly reduced owing to the decreased basal spacing and cation exchange. For different hydrodynamic conditions, higher shear rate promotes the flocculation of Ca-montmorillonite, but breaks the Na-montmorillonite flocs. The significance of understanding the flocculation and PSD of expansive clays is also discussed in terms of sediment transport under different aquatic environments.

  19. Acute sleep deprivation increases portion size and affects food choice in young men.

    PubMed

    Hogenkamp, Pleunie S; Nilsson, Emil; Nilsson, Victor C; Chapman, Colin D; Vogel, Heike; Lundberg, Lina S; Zarei, Sanaz; Cedernaes, Jonathan; Rångtell, Frida H; Broman, Jan-Erik; Dickson, Suzanne L; Brunstrom, Jeffrey M; Benedict, Christian; Schiöth, Helgi B

    2013-09-01

    Acute sleep loss increases food intake in adults. However, little is known about the influence of acute sleep loss on portion size choice, and whether this depends on both hunger state and the type of food (snack or meal item) offered to an individual. The aim of the current study was to compare portion size choice after a night of sleep and a period of nocturnal wakefulness (a condition experienced by night-shift workers, e.g. physicians and nurses). Sixteen men (age: 23 ± 0.9 years, BMI: 23.6 ± 0.6 kg/m(2)) participated in a randomized within-subject design with two conditions, 8-h of sleep and total sleep deprivation (TSD). In the morning following sleep interventions, portion size, comprising meal and snack items, was measured using a computer-based task, in both fasted and sated state. In addition, hunger as well as plasma levels of ghrelin were measured. In the morning after TSD, subjects had increased plasma ghrelin levels (13%, p=0.04), and chose larger portions (14%, p=0.02), irrespective of the type of food, as compared to the sleep condition. Self-reported hunger was also enhanced (p<0.01). Following breakfast, sleep-deprived subjects chose larger portions of snacks (16%, p=0.02), whereas the selection of meal items did not differ between the sleep interventions (6%, p=0.13). Our results suggest that overeating in the morning after sleep loss is driven by both homeostatic and hedonic factors. Further, they show that portion size choice after sleep loss depend on both an individual's hunger status, and the type of food offered. PMID:23428257

  20. Flowering synchrony and floral display size affect pollination success in a deceit-pollinated tropical orchid

    NASA Astrophysics Data System (ADS)

    Parra-Tabla, Victor; Vargas, Carlos F.

    2007-07-01

    ue to frequency-dependent negative selection, a strong relationship between reproductive phenology traits and pollination success is expected in deceit-pollinated species. This paper assesses the effects of floral display size on both female (fruit production) and male (pollen removal) pollination success in a population of the deceit-pollinated tropical orchid Myrmecophila christinae during two consecutive years (1998-1999). Low pollen removal (˜9% of total flowers) and fruit production values (˜3% of total flowers) were recorded during both years. As expected, binary logistic regressions showed a significant negative effect of floral synchrony, and a positive effect of floral display size on both male and female success, although these effects varied across years. Pollination rates in the field and in hand pollinations suggest a doubling in pollinator abundance between years. Results suggest that floral display size and flowering synchrony are of adaptive value for M. christinae. However, between-year fluctuations might indicate that reproductive phenology traits in deceit-pollinated species undergo fluctuating selection regimes among years and are probably linked to short-term changes in environmental (abiotic and biotic) conditions.

  1. Microclimatic Divergence in a Mediterranean Canyon Affects Richness, Composition, and Body Size in Saproxylic Beetle Assemblages

    PubMed Central

    Buse, Jörn; Fassbender, Samuel; Entling, Martin H.; Pavlicek, Tomas

    2015-01-01

    Large valleys with opposing slopes may act as a model system with which the effects of strong climatic gradients on biodiversity can be evaluated. The advantage of such comparisons is that the impact of a change of climate can be studied on the same species pool without the need to consider regional differences. The aim of this study was to compare the assemblage of saproxylic beetles on such opposing slopes at Lower Nahal Oren, Mt. Carmel, Israel (also known as “Evolution Canyon”) with a 200–800% higher solar radiation on the south-facing (SFS) compared to the north-facing slope (NFS). We tested specific hypotheses of species richness patterns, assemblage structure, and body size resulting from interslope differences in microclimate. Fifteen flight-interception traps per slope were distributed over three elevation levels ranging from 50 to 100 m a.s.l. Richness of saproxylic beetles was on average 34% higher on the SFS compared with the NFS, with no detected influence of elevation levels. Both assemblage structure and average body size were determined by slope aspect, with more small-bodied beetles found on the SFS. Both the increase in species richness and the higher prevalence of small species on the SFS reflect ecological rules present on larger spatial grain (species-energy hypothesis and community body size shift hypothesis), and both can be explained by the metabolic theory of ecology. This is encouraging for the complementary use of micro- and macroclimatic gradients to study impacts of climate warming on biodiversity. PMID:26047491

  2. Prediction and characterization of heat-affected zone formation in tin-bismuth alloys due to nickel-aluminum multilayer foil reaction

    NASA Astrophysics Data System (ADS)

    Hooper, R. J.; Davis, C. G.; Johns, P. M.; Adams, D. P.; Hirschfeld, D.; Nino, J. C.; Manuel, M. V.

    2015-06-01

    Reactive multilayer foils have the potential to be used as local high intensity heat sources for a variety of applications. Most of the past research effort concerning these materials have focused on understanding the structure-property relationships of the foils that govern the energy released during a reaction. To improve the ability of researchers to more rapidly develop technologies based on reactive multilayer foils, a deeper and more predictive understanding of the relationship between the heat released from the foil and microstructural evolution in the neighboring materials is needed. This work describes the development of a numerical model for the purpose of predicting heat affected zone size in substrate materials. The model is experimentally validated using a commercially available Ni-Al multilayer foils and alloys from the Sn-Bi binary system. To accomplish this, phenomenological models for predicting the variation of physical properties (i.e., thermal conductivity, density, and heat capacity) with temperature and composition in the Sn-Bi system were utilized using literature data.

  3. Prediction and characterization of heat-affected zone formation in tin-bismuth alloys due to nickel-aluminum multilayer foil reaction

    DOE PAGESBeta

    Hooper, R. J.; Davis, C. G.; Johns, P. M.; Adams, D. P.; Hirschfeld, D.; Nino, J. C.; Manuel, M. V.

    2015-06-26

    Reactive multilayer foils have the potential to be used as local high intensity heat sources for a variety of applications. In this study, most of the past research effort concerning these materials have focused on understanding the structure-property relationships of the foils that govern the energy released during a reaction. To improve the ability of researchers to more rapidly develop technologies based on reactive multilayer foils, a deeper and more predictive understanding of the relationship between the heat released from the foil and microstructural evolution in the neighboring materials is needed. This work describes the development of a numerical modelmore » for the purpose of predicting heat affected zone size in substrate materials. The model is experimentally validated using a commercially available Ni-Al multilayer foils and alloys from the Sn-Bi binary system. To accomplish this, phenomenological models for predicting the variation of physical properties (i.e., thermal conductivity, density, and heat capacity) with temperature and composition in the Sn-Bi system were utilized using literature data.« less

  4. Weld heat-affected zone in Ti-6Al-4V alloy. Part 2: Modeling and experimental simulation of growth and phase transformations

    SciTech Connect

    Shah, A.K.; Kulkarni, S.D.; Gopinathan, V.; Krishnan, R.

    1995-10-01

    The work carried out involved development of theoretical models to predict the {alpha} + {beta} {R_arrow} {beta} transformation during heating, grain growth, and subsequent transformation of {beta} on cooling in the Ti-6Al-4V alloy. The data for correlation of microstructure to mechanical properties have been generated experimentally using simulated HAZ (heat-affected zone) specimens. The overall effect of the weld variables on the HAZ microstructure can be visualized from the HAZ microstructure diagram which depicts various phase transformations occurring during the weld thermal cycle in t{sub 8/5}-T{sub p} space. The results of computer modeling indicate that due to the rapid heating and cooling cycles encountered in welding, the shift in {beta} transus may be hundreds of degrees. Also, in the near-HAZ region, the grains can grow an order of magnitude larger than the original grain size. The formation of lamellar {alpha} can be minimized by reducing the t{sub 8/5} parameter. The experimental simulation results confirm excessive grain growth in the HAZ region. The hardness values do not show any significant trend, but the fracture toughness is found to deteriorate in the HAZ.

  5. Prediction and characterization of heat-affected zone formation in tin-bismuth alloys due to nickel-aluminum multilayer foil reaction

    SciTech Connect

    Hooper, R. J.; Davis, C. G.; Johns, P. M.; Adams, D. P.; Hirschfeld, D.; Nino, J. C.; Manuel, M. V.

    2015-06-26

    Reactive multilayer foils have the potential to be used as local high intensity heat sources for a variety of applications. In this study, most of the past research effort concerning these materials have focused on understanding the structure-property relationships of the foils that govern the energy released during a reaction. To improve the ability of researchers to more rapidly develop technologies based on reactive multilayer foils, a deeper and more predictive understanding of the relationship between the heat released from the foil and microstructural evolution in the neighboring materials is needed. This work describes the development of a numerical model for the purpose of predicting heat affected zone size in substrate materials. The model is experimentally validated using a commercially available Ni-Al multilayer foils and alloys from the Sn-Bi binary system. To accomplish this, phenomenological models for predicting the variation of physical properties (i.e., thermal conductivity, density, and heat capacity) with temperature and composition in the Sn-Bi system were utilized using literature data.

  6. Body size affects individual winter foraging strategies of thick-billed murres in the Bering Sea.

    PubMed

    Orben, Rachael A; Paredes, Rosana; Roby, Daniel D; Irons, David B; Shaffer, Scott A

    2015-11-01

    Foraging and migration often require different energetic and movement strategies. Though not readily apparent, constraints during one phase might influence the foraging strategies observed in another. For marine birds that fly and dive, body size constraints likely present a trade-off between foraging ability and migration as smaller bodies reduce flight costs, whereas larger bodies are advantageous for diving deeper. This study examines individual wintering strategies of deep diving thick-billed murres (Uria lomvia) breeding at three colonies in the south-eastern Bering Sea: St Paul, St George and Bogoslof. These colonies, arranged north to south, are located such that breeding birds forage in a gradient from shelf to deep-water habitats. We used geolocation time-depth recorders and stable isotopes from feathers to determine differences in foraging behaviour and diet of murres during three non-breeding periods, 2008-2011. Body size was quantified by a principal component analysis (wing, culmen, head+bill and tarsus length). A hierarchical cluster analysis identified winter foraging strategies based on individual movement, diving behaviour and diet (inferred from stable isotopes). Structural body size differed by breeding island. Larger birds from St Paul had higher wing loading than smaller birds from St George. Larger birds, mainly from St Paul, dove to deeper depths, spent more time in the Bering Sea, and likely consumed higher trophic-level prey in late winter. Three winter foraging strategies were identified. The main strategy, employed by small birds from all three breeding colonies in the first 2 years, was characterized by high residency areas in the North Pacific south of the Aleutians and nocturnal diving. In contrast, 31% of birds from St Paul remained in the Bering Sea and foraged mainly during the day, apparently feeding on higher trophic-level prey. Throat feather stable isotopes indicated that individuals exhibited flexibility in the use of this

  7. Rheological quality of pearl millet porridge as affected by grits size.

    PubMed

    Yadav, Deep N; Chhikara, Navnidhi; Anand, Tanupriya; Sharma, Monika; Singh, Ashish K

    2014-09-01

    Study was conducted to optimize pearl millet grits size for the preparation of acceptable porridge with skimmed milk powder (SMP). Pearl millet porridge was prepared with different grits size (1.410, 0.841, 0.595, and 0.420 mm). A positive (r = 0.904) correlation was observed between water absorption index and grits size. Porridge showed shear thinning behavior as, initially shear stress increased with increase in shear rate and later on decreased. Porridge prepared with larger grits (1.410 mm) exhibited higher firmness (38.4 ± 1.27 N) and viscosity (446 ± 3.9 cP), whereas smaller grits (0.420 mm) resulted in less viscous (118.8 ± 1.74 cP) and firm (20.4 ± 1.85 N) porridge. The medium grits (0.841 mm) produced porridge with acceptable firmness (30.7 ± 1.56 N) and viscosity (298.1 ± 8.81 cP) with moderate (6.0 ± 0.10) acceptability. To improve sensory quality of porridge (grits size 0.841 mm); skimmed milk powder at different levels (0, 5, 10 and 15 %) was added and its effect on various quality parameters was studied. SMP addition significantly (P ≤ 0.05) modified the gelatinization and gelling behavior of grits and decreased (P ≤ 0.05) all the pasting characteristics except pasting temperature, which increased from 77.1 ± 1.85 to 85.9 ± 3.46 °C. The peak (499 ± 6.6 cP) and final viscosity (450 ± 11.9 cP) of porridge (0.841 mm) prepared with 15 % SMP are quite similar. Hence, it maintains viscosity on cooling, similar to maximum viscosity attained during cooking. Keeping in view the rheological, firmness and sensory quality, 0.841 mm grits of pearl millet with 15 % SMP was found optimum for preparation of acceptable porridge. PMID:25190879

  8. Effect of boron segregation at grain boundaries on heat-affected zone cracking in wrought INCONEL 718

    NASA Astrophysics Data System (ADS)

    Chen, W.; Chaturvedi, M. C.; Richards, N. L.

    2001-04-01

    Susceptibility to heat-affected zone (HAZ) cracking during electron-beam welding was studied in two INCONEL 718-based alloys doped with different levels of boron. By lowering the carbon, sulfur, and phosphorous concentrations to be “as low as possible,” the occurrence of HAZ cracking was related directly to the level of segregation of boron at grain boundaries, which occurred by nonequilibrium segregation during a preweld heat treatment. The study has demonstrated a direct correlation between the amount of boron segregated at grain boundaries and their susceptibility to HAZ cracking, in terms of the total crack length and number of cracks observed in the HAZ. The analysis of results suggests that both the melting and resolidification temperatures of the boron-segregated grain boundaries can be about 100 °C to 200 °C lower than those of the grain boundaries that were susceptible to constitutional liquation of Nb carbides on them, making boron more deleterious in causing HAZ cracking.

  9. Texture Evolution within the Thermomechanically Affected Zone of an Al-Li Alloy 2195 Friction Stir Weld

    NASA Astrophysics Data System (ADS)

    Tayon, Wesley A.; Domack, Marcia S.; Hoffman, Eric K.; Hales, Stephen J.

    2013-11-01

    Friction stir welding (FSW) of Al -Li alloy 2195 plate produces strong texture gradients. The microstructural characteristics evolve from the base plate, through the thermomechanically affected zone (TMAZ), to the weld nugget interface. In the current study, electron backscattered diffraction (EBSD) analyses were employed to quantify the spatial distribution of texture gradients associated with the evolution of texture within the TMAZ. The strong texture of the base plate enabled the texture evolution to be characterized as a function of location. Systematic partitioning of EBSD data relative to the degree of lattice rotation at each point accurately captured the crystallographic transitions across the advancing side TMAZ. Over a large section of this region, the texture evolves as a result of continuous rigid body rotations. The rigid body rotations were correlated with the complex material flow patterns commonly associated with the FSW process and prior observations of shear-related textures. Finally, a correlation between texture and fracture in a subscale tensile specimen is observed, where failure occurs within a visible band of low-Taylor factor grains.

  10. Green reconstruction of the tsunami-affected areas in India using the integrated coastal zone management concept.

    PubMed

    Sonak, Sangeeta; Pangam, Prajwala; Giriyan, Asha

    2008-10-01

    A tsunami, triggered by a massive undersea earthquake off Sumatra in Indonesia, greatly devastated the lives, property and infrastructure of coastal communities in the coastal states of India, Andaman and Nicobar Islands, Indonesia, Sri Lanka, Malaysia and Thailand. This event attracted the attention of environmental managers at all levels, local, national, regional and global. It also shifted the focus from the impact of human activities on the environment to the impacts of natural hazards. Recovery/reconstruction of these areas is highly challenging. A clear understanding of the complex dynamics of the coast and the types of challenges faced by the several stakeholders of the coast is required. Issues such as sustainability, equity and community participation assume importance. The concept of ICZM (integrated coastal zone management) has been effectively used in most parts of the world. This concept emphasizes the holistic assessment of the coast and a multidisciplinary analysis using participatory processes. It integrates anthropocentric and eco-centric approaches. This paper documents several issues involved in the recovery of tsunami-affected areas and recommends the application of the ICZM concept to the reconstruction efforts. PMID:17544565

  11. Recovery approach affects soil quality in the water level fluctuation zone of the Three Gorges Reservoir, China: implications for revegetation.

    PubMed

    Ye, Chen; Cheng, Xiaoli; Zhang, Quanfa

    2014-02-01

    Plants in the water level fluctuation zone of the Three Gorges Reservoir Region disappeared due to winter-flooding and prolonged inundation. Revegetation (plantation and natural recovery) have been promoted to restore and protect the riparian ecosystem in recent years. Revegetation may affect soil qualities and have broad important implications both for ecological services and soil recovery. In this study, we investigated soil properties including soil pH values, bulk density, soil organic matter (SOM), soil nutrients and heavy metals, soil microbial community structure, microbial biomass, and soil quality index under plantation and natural recovery in the Three Gorges Reservoir Region. Most soil properties showed significant temporal and spatial variations in both the plantation and natural recovery areas. Higher contents of SOM and NO3-N were found in plantation area, while higher contents of soil pH values, bulk density, and total potassium were observed in the natural recovery area. However, there were no significant differences in plant richness and diversity and soil microbial community structure between the two restoration approaches. A soil quality index derived from SOM, bulk density, Zn, Cd, and Hg indicated that natural recovery areas with larger herbaceous coverage had more effective capacity for soil restoration. PMID:24019143

  12. Hydrogen cracking in the heat affected zone of high strength steels - year 2, development of weld metal test

    SciTech Connect

    Graville, B.A.

    1997-03-01

    In previous work the notched bend test had been developed for evaluating the sensitivity of the heat affected zone (HAZ) of a weld to hydrogen cracking. In the present work the test was modified to allow the evaluation of weld metal. The test specimen uses a Charpy-V notch placed in the weld metal after welding and prior to loading in three point bending. The deflection to first load drop is used as the measure of sensitivity to cracking. The results showed that weld metal could readily be evaluated with the test discriminating among weld metals of different composition and hydrogen content. Finite element analysis was undertaken and showed that for the two weld metals tested, cracking occurred at the same local stress when the hydrogen content was the same despite differences in strength. A finite difference model was used to calculate the distribution of hydrogen as a function of aging time. Although the general trends were confirmed by the experimental measurements of hydrogen content, there was considerable scatter attributed to the small hydrogen volumes measured.

  13. The influence of solidification mode on heat affected zone microfissuring in a nickel-iron base superalloy

    SciTech Connect

    Nakkalil, R.; Chaturvedi, M.C. . Metallurgical Sciences Lab.); Richards, N.L. )

    1993-12-01

    The heat affected zone (HAZ) microfissuring of thermomechanically processed Incoloy 903 with a duplex grain structure, has been examined with a view to understand the mechanism(s) of, and to reduce the incidence of microfissuring. Extensive formation of liquid films on the HAZ grain boundaries primarily due to the complete constitutional liquation of preexisting MNP phosphides, MC carbides and partial constitutional liquation of primary MX carbide insolubles was observed. The liquid films resulted in considerable microfissuring on the long warm worked grain boundaries and extensive grain boundary liquid film migration (LFM) on the fine recrystallized grain boundaries. The liquid films formed on the warm worked boundaries were observed to have undergone normal solidification accompanied with the formation of dendritic gamma and terminal interdendritic constituents. The exclusive occurrence of LFM only on the fine grains and not on warm worked grains is attributed to the increased driving force and velocity for LFM arising due to substantial interface curvature of the fine grains. It is shown that HAZ microfissuring is minimized if the liquid films on the HAZ grain boundaries can partially equilibrate by LFM instead of by normal solidification.

  14. Direct observation of phase transformations in the simulated heat-affected zone of a 9Cr martensitic steel

    SciTech Connect

    Mayr, Peter; Palmer, T. A.; Elmer, J. W.; Specht, Eliot D

    2008-01-01

    An experimental test melt of a boron alloyed 9Cr-3W-3Co-V,Nb steel for high temperature applications in the thermal power generation industry was produced by vacuum induction melting. This grade of steel typically displays a homogeneous tempered martensitic microstructure in the as-received condition. However, after welding, this microstructure is significantly altered, resulting in a loss of its desired properties. The phase transformations during simulated thermal cycles typical of those experienced in the weld heat-affected zone (HAZ) were directly observed by in situ X-ray diffraction experiments using synchrotron radiation. Heating rates of 10 C s-1 and 100 C s-1 up to a peak temperature of 1300 C are investigated here. The final microstructures observed after both simulated weld thermal cycles are primarily composed of martensite with approximately 4% retained delta ferrite and 4% retained austenite, by volume. With the temporal resolution of the in situ X-ray diffraction technique, phase transformations from tempered martensite to austenite to delta ferrite during heating and to martensite during cooling were monitored. With this technique, the evolution of the final microstructure through both heating and cooling is monitored, providing additional context to the microstructural observations.

  15. The Stress Corrosion Crack Growth Rate of Alloy 600 Heat Affected Zones Exposed to High Purity Water

    SciTech Connect

    George A. Young; Nathan Lewis

    2003-04-05

    Grain boundary chromium carbides improve the resistance of nickel based alloys to primary water stress corrosion cracking (PWSCC). However, in weld heat affected zones (HAZ's), thermal cycles from fusion welding can solutionize beneficial grain boundary carbides, produce locally high residual stresses and strains, and promote PWSCC. The present research investigates the crack growth rate of an A600 HAZ as a function of test temperature. The A600 HAZ was fabricated by building up a gas-tungsten-arc-weld deposit of EN82H filler metal onto a mill-annealed A600 plate. Fracture mechanics based, stress corrosion crack growth rate testing was performed in high purity water between 600 F and 680 F at an initial stress intensity factor of 40 ksi {radical}in and at a constant electrochemical potential. The HAZ samples exhibited significant SCC, entirely within the HAZ at all temperatures tested. While the HAZ samples showed the same temperature dependence for SCC as the base material (HAZ: 29.8 {+-} 11.2{sub 95%} kcal/mol vs A600 Base: 35.3 {+-} 2.58{sub 95%} kcal/mol), the crack growth rates were {approx} 30X faster than the A600 base material tested at the same conditions. The increased crack growth rates of the HAZ is attributed to fewer intergranular chromium rich carbides and to increased plastic strain in the HAZ as compared to the unaffected base material.

  16. Structure-Property-Fracture Mechanism Correlation in Heat-Affected Zone of X100 Ferrite-Bainite Pipeline Steel

    NASA Astrophysics Data System (ADS)

    Li, Xueda; Ma, Xiaoping; Subramanian, S. V.; Misra, R. D. K.; Shang, Chengjia

    2015-03-01

    Structural performance of a weld joint primarily depends on the microstructural characteristics of heat-affected zone (HAZ). In this regard, the HAZ in X100 ferrite-bainite pipeline steel was studied by separating the HAZ into intercritically reheated coarse-grained (ICCG) HAZ containing and non-containing regions. These two regions were individually evaluated for Charpy impact toughness and characterized by electron back-scattered diffraction (EBSD). Low toughness of ~50 J was obtained when the notch of impact specimen encountered ICCGHAZ and high toughness of ~180 J when the notch did not contain ICCGHAZ. Fracture surface was ~60 pct brittle in the absence of ICCGHAZ, and 95 pct brittle (excluding shear lip) in the presence of ICCGHAZ in the impact tested samples. The underlying reason is the microstructure of ICCGHAZ consisted of granular bainite and upper bainite with necklace-type martensite-austenite (M-A) constituent along grain boundaries. The presence of necklace-type M-A constituent notably increases the susceptibility of cleavage microcrack nucleation. ICCGHAZ was found to be both the initiation site of the whole fracture and cleavage facet initiation site during brittle fracture propagation stage. Furthermore, the study of secondary microcracks beneath CGHAZ and ICCGHAZ through EBSD suggested that the fracture mechanism changes from nucleation-controlled in CGHAZ to propagation-controlled in ICCGHAZ because of the presence of necklace-type M-A constituent in ICCGHAZ. Both fracture mechanisms contribute to the poor toughness of the sample contained ICCGHAZ.

  17. Characterization of Low Temperature Ferrite/Austenite Transformations in the Heat Affected Zone of 2205 Duplex Stainless Steel Arc Welds

    SciTech Connect

    Palmer, T A; Elmer, J W; Babu, S S; Vitek, J M

    2003-08-20

    Spatially Resolved X-Ray Diffraction (SRXRD) has been used to identify a previously unobserved low temperature ferrite ({delta})/austenite({gamma}) phase transformation in the heat affected zone (HAZ) of 2205 Duplex Stainless Steel (DSS) welds. In this ''ferrite dip'' transformation, the ferrite transforms to austenite during heating to peak temperatures on the order of 750 C, and re-transforms to ferrite during cooling, resulting in a ferrite volume fraction equivalent to that in the base metal. Time Resolved X-Ray Diffraction (TRXRD) and laser dilatometry measurements during Gleeble{reg_sign} thermal simulations are performed in order to verify the existence of this low temperature phase transformation. Thermodynamic and kinetic models for phase transformations, including both local-equilibrium and para-equilibrium diffusion controlled growth, show that diffusion of substitutional alloying elements does not provide a reasonable explanation for the experimental observations. On the other hand, the diffusion of interstitial alloying elements may be rapid enough to explain this behavior. Based on both the experimental and modeling results, two mechanisms for the ''ferrite dip'' transformation, including the formation and decomposition of secondary austenite and an athermal martensitic-type transformation of ferrite to austenite, are considered.

  18. Putting Up a Big Front: Car Design and Size Affect Road-Crossing Behaviour.

    PubMed

    Klatt, Wilhelm K; Chesham, Alvin; Lobmaier, Janek S

    2016-01-01

    Previous research suggests that people tend to see faces in car fronts and that they attribute personality characteristics to car faces. In the present study we investigated whether car design influences pedestrian road-crossing behaviour. An immersive virtual reality environment with a zebra crossing scenario was used to determine a) whether the minimum accepted distance for crossing the street is larger for cars with a dominant appearance than for cars with a friendly appearance and b) whether the speed of dominant-looking cars is overestimated as compared to friendly-looking cars. Participants completed both tasks while either standing on the pavement or on the centre island. We found that people started to cross the road later in front of friendly-looking low-power cars compared to dominant-looking high-power cars, but only if the cars were relatively large in size. For small cars we found no effect of power. The speed of smaller cars was estimated to be higher compared to large cars (size-speed bias). Furthermore, there was an effect of starting position: From the centre island, participants entered the road significantly later (i. e. closer to the approaching car) and left the road later than when starting from the pavement. Similarly, the speed of the cars was estimated significantly lower when standing on the centre island compared to the pavement. To our knowledge, this is the first study to show that car fronts elicit responses on a behavioural level. PMID:27434187

  19. Putting Up a Big Front: Car Design and Size Affect Road-Crossing Behaviour

    PubMed Central

    Klatt, Wilhelm K.; Chesham, Alvin; Lobmaier, Janek S.

    2016-01-01

    Previous research suggests that people tend to see faces in car fronts and that they attribute personality characteristics to car faces. In the present study we investigated whether car design influences pedestrian road-crossing behaviour. An immersive virtual reality environment with a zebra crossing scenario was used to determine a) whether the minimum accepted distance for crossing the street is larger for cars with a dominant appearance than for cars with a friendly appearance and b) whether the speed of dominant-looking cars is overestimated as compared to friendly-looking cars. Participants completed both tasks while either standing on the pavement or on the centre island. We found that people started to cross the road later in front of friendly-looking low-power cars compared to dominant-looking high-power cars, but only if the cars were relatively large in size. For small cars we found no effect of power. The speed of smaller cars was estimated to be higher compared to large cars (size-speed bias). Furthermore, there was an effect of starting position: From the centre island, participants entered the road significantly later (i. e. closer to the approaching car) and left the road later than when starting from the pavement. Similarly, the speed of the cars was estimated significantly lower when standing on the centre island compared to the pavement. To our knowledge, this is the first study to show that car fronts elicit responses on a behavioural level. PMID:27434187

  20. β-lactoglobulin stabilized nanemulsions--Formulation and process factors affecting droplet size and nanoemulsion stability.

    PubMed

    Ali, Ali; Mekhloufi, Ghozlene; Huang, Nicolas; Agnely, Florence

    2016-03-16

    To avoid the toxicological concerns associated to synthetic surfactants, proteins might be an alternative for the stabilization of pharmaceutical nanoemulsions. The present study investigates the use of β-lactoglobulin (β-lg) to stabilize oil in water biocompatible nanoemulsions intended for a pharmaceutical use and prepared by high pressure homogenization (HPH). The effects of composition (nature and weight fraction of oil, β-lg concentration) and of process parameters (pressure and number of cycles) on the droplet size and on the stability of nanoemulsions were thoroughly assessed. The nanoemulsions prepared with β-lg at 1 wt% and with 5 wt% Miglyol 812 (the oil with the lowest viscosity) displayed a relatively small particle size (about 200 nm) and a low polydispersity when a homogenization pressure of 100 MPa was applied for 4 cycles. These nanoemulsions were the most stable formulations over 30 days at least. Emulsification efficiency of β-lg was reduced at higher homogenization pressures (200 MPa and 300 MPa). The effect of HPH process on the interfacial properties of β-lg was evaluated by drop shape analysis. This treatment had an effect neither on the interfacial tension nor on the interfacial dilatational rheology of β-lg at the Miglyol 812/water interface. PMID:26784982

  1. Recruitment and post-recruit immigration affect the local population size of coral reef fishes

    NASA Astrophysics Data System (ADS)

    Lewis, A. R.

    1997-07-01

    This study quantifies the contributions of larval recruitment and post-recruit (juvenile and adult) immigration to net increases in population size for 150 species of fishes found on ten isolated coral patches or `bommies' (108-267 m2) within a typical reef of the Great Barrier Reef system. At least one third of the total number of recruits and immigrants to all bommies were post-recruit fishes, and movement between bommies in 136 species was detected at some time during the 22 month sampling period. The relative numbers of recruits and post-recruit immigrants per species varied widely within the assemblage, and between the replicate bommies. Populations of 95 species received both types of immigrants, 41 species had only post-recruit immigrants, and 14 species received only larval recruitment. In most species, recruitment occurred over the austral summer between October and February, while post-recruit movements occurred in both summer and winter. Rates of post-recruit immigration varied temporally within bommies, and pulses of post-recruits were less temporally concordant between bommies than pulses of recruits. This study is further evidence that post-settlement processes can have a significant effect on the local population size of reef fishes.

  2. Effect of simulated thermal cycles on the microstructure of the heat-affected zone in HSLA-80 and HSLA-100 steel plates

    NASA Astrophysics Data System (ADS)

    Shome, M.; Gupta, O. P.; Mohanty, O. N.

    2004-03-01

    The influence of weld thermal simulation on the transformation kinetics and heat-affected zone (HAZ) microstructure of two high-strength low-alloy (HSLA) steels, HSLA-80 and HSLA-100, has been investigated. Heat inputs of 10 kJ/cm (fast cooling) and 40 kJ/cm (slow cooling) were used to generate single-pass thermal cycles with peak temperatures in the range of 750 °C to 1400 °C. The prior-austenite grain size is found to grow rapidly beyond 1100 °C in both the steels, primarily with the dissolution of niobium carbonitride (Nb(CN)) precipitates. Dilatation studies on HSLA-80 steel indicate transformation start temperatures (T s ) of 550 °C to 560 °C while cooling from a peak temperature (T p ) of 1000 °C. Transmission electron microscopy studies show here the presence of accicular ferrite in the HAZ. The T s value is lowered to 470 °C and below when cooled from a peak temperature of 1200 °C and beyond, with almost complete transformation to lath martensite. In HSLA-100 steel, the T s value for accicular ferrite is found to be 470 °C to 490 °C when cooled from a peak temperature of 1000 °C, but is lowered below 450 °C when cooled from 1200 °C and beyond, with correspondingly higher austenite grain sizes. The transformation kinetics appears to be relatively faster in the fine-grained austenite than in the coarse-grained austenite, where the niobium is in complete solid solution. A mixed microstructure consisting of accicular ferrite and lath martensite is observed for practically all HAZ treatments. The coarse-grained HAZ (CGHAZ) of HSLA-80 steel shows a higher volume fraction of lath martensite in the final microstructure and is harder than the CGHAZ of HSLA-100 steel.

  3. Family size preference and factors affecting the fertility rate in Hyogo, Japan

    PubMed Central

    2013-01-01

    Background Japan has consistently shown a low fertility rate, which has been lower than the replacement level since 1974, and represents one of the least fertile countries in the world. This study was designed to determine the family size preference of and its effect on Japanese women. Methods We conducted a questionnaire survey among women who visited the obstetrics and gynecology department of 18 hospitals and clinics in the Hyogo Prefecture, Japan, between October 2011 and February 2012. All the women were categorized according to age group and area of residence, and the survey results were statistically analyzed using a t test. Results A total of 1616 women were included in this study. There was no significant difference between the mean desired and actual marital ages (26.70 and 26.67 years, respectively). The mean desired number of children was 2.55, which was significantly more than the mean actual number of children (1.77) in all generations. The mean desired and actual numbers of children were more in the rural areas (2.73 and 2.09, respectively) than in the urban (2.54 and 1.70, respectively) and semi-urban areas (2.49 and 1.60, respectively). The mean number of family members was significantly greater in the rural areas (3.84) than in the urban (3.25) and semi-urban areas (3.05). The most important concern among women who had never delivered a baby was childbearing itself, followed by the expenses related to pregnancy and childbearing. Conclusions The family size preference of the women in our study was higher than the actual numbers of children. The fertility intentions were low among the younger women but high among those living in rural areas with larger families. PMID:23363875

  4. Population Structure, Genetic Diversity, Effective Population Size, Demographic History and Regional Connectivity Patterns of the Endangered Dusky Grouper, Epinephelus marginatus (Teleostei: Serranidae), within Malta's Fisheries Management Zone.

    PubMed

    Buchholz-Sørensen, Molly; Vella, Adriana

    2016-01-01

    The objective of this study is to describe the genetic population structure and demographic history of the endangered marine fish, Epinephelus marginatus, within Malta's Fisheries Management Zone for the purpose of localised conservation planning. Epinephelus marginatus is a long-lived, sedentary, reef-associated protogynous hermaphrodite with high commercial and recreational value that is at risk of extinction throughout its global distribution. Based on global trends, population substructuring and gaps in local knowledge this has led to an increased interest in evaluation of local stock. Assessment of Maltese demography was based on historical and contemporary catch landings data whilst genetic population structure and regional connectivity patterns were evaluated by examining 175 individuals collected within the central Mediterranean region between 2002 and 2009 using 14 nuclear microsatellite loci. Demographic stock assessment of Maltese E. marginatus' revealed a 99% decline in catch landings between 1947 and 2009 within the Fisheries Management Zone. A contemporary modest mean size was observed, 3 ± 3 kg, where approximately 17% of the population was juvenile, 68% female/sex-changing and 15% were male with a male-to-female sex ratio of 1:5. Genetic analysis describes the overall population of E. marginatus' within the Fisheries Management Zone as decreasing in size (ƟH = 2.2), which has gone through a significant size reduction in the past (M = 0.41) and consequently shows signs of moderate inbreeding (FIS = 0.10, p < 0.001) with an estimated effective population size of 130 individuals. Results of spatially explicit Bayesian genetic cluster analysis detected two geographically distinct subpopulations within Malta's Fisheries Management Zone and that they are connected to a larger network of E. marginatus' within the Sicily Channel. Results suggest conservation management should be designed to reflect E. marginatus' within Malta's Fisheries Management Zone

  5. Hot Ductility Behaviors in the Weld Heat-Affected Zone of Nitrogen-Alloyed Fe-18Cr-10Mn Austenitic Stainless Steels

    NASA Astrophysics Data System (ADS)

    Moon, Joonoh; Lee, Tae-Ho; Hong, Hyun-Uk

    2015-04-01

    Hot ductility behaviors in the weld heat-affected zone (HAZ) of nitrogen-alloyed Fe-18Cr-10Mn austenitic stainless steels with different nitrogen contents were evaluated through hot tension tests using Gleeble simulator. The results of Gleeble simulations indicated that hot ductility in the HAZs deteriorated due to the formation of δ-ferrite and intergranular Cr2N particles. In addition, the amount of hot ductility degradation was strongly affected by the fraction of δ-ferrite.

  6. Portion Size Variably Affects Food Intake of 6-year-old and 4-year-old Children in Kunming, China

    PubMed Central

    Smith, Lindsey; Conroy, Katharine; Wen, Hongmei; Rui, Li; Humphries, Debbie

    2015-01-01

    Age and portion size have been found to influence food intake in American children but have not been examined in an international context. This study evaluated the association between age and the effects of portion size on the food intake of kindergarteners in Kunming, China. Using a within-subjects crossover design in a classroom setting, 173 children in two age groups, mean age 4.2 years and 6.1 years, were served a predefined reference, small (-30%) and large (+30%) portion of rice, vegetables, and a protein source during lunchtime over three consecutive days. Each portion was weighed before and after the meal to determine amount of food consumed. Linear mixed modeling, controlling for repeated measures and clustering by classroom, was used to compare food intake under small and large portion size conditions to the reference portion. Children ate significantly less food when served small portions. When served a large portion, 6-year-old children increased food intake while 4-year-old children decreased food intake in comparison to the reference portion. Findings indicate that portion size affects food intake in Chinese children 4- to 6-years old. Older children show larger increases in food intake with increased portion size than do younger children. PMID:23702260

  7. Estimating the Size of HIV Key Affected Populations in Chongqing, China, Using the Network Scale-Up Method

    PubMed Central

    Lin, Wen; Wu, Guohui; Zhang, Wei; Hladik, Wolfgang; Abdul-Quader, Abu; Bulterys, Marc; Fuller, Serena; Wang, Lu

    2013-01-01

    Objectives To estimate the average social network size in the general population and the size of HIV key affected populations (KAPs) in Chongqing municipality using the network scale-up method (NSUM). Methods A general population survey was conducted in 2011 through a multistage random sampling method. Participants aged between 18 and 60 years were recruited. The average social network size (c) was estimated and adjusted by known population method. The size of HIV KAP in Chongqing municipality was estimated using the adjusted c value with adjustment for the transmission effect using the scaled respect factor. Results 3,026 inhabitants of Chongqing agreed to the survey, and 2,957 (97.7%) completed the questionnaire. The adjusted c value was 310. The estimated size of KAP was 28,418(95% Confidence Interval (CI):26,636∼30,201) for female sex workers (FSW), 163,199(95%CI:156,490∼169,908) for clients of FSW, 37,959(95%CI: 34,888∼41,030) for drug users (DU), 14,975(95%CI:13,047∼16,904) for injecting drug users (IDU) and 16,767(95%CI:14,602∼18,932) for men who have sex with men (MSM). The ratio of clients to FSW was 5.74∶1, and IDU accounted for 39.5% of the DU population. The estimates suggest that FSW account for 0.37% of the female population aged 15–49 years in Chongqing, and clients of FSW and MSM represent 2.09% and 0.21% of the male population aged 15–49 years in the city, respectively. Conclusion NSUM provides reasonable population size estimates for FSW, their clients, DU and IDU in Chongqing. However, it is likely to underestimate the population size of MSM even after adjusting for the transmission effect. PMID:23967246

  8. Does the Finite Size of Electrons Affect Quantum Noise in Electronic Devices?

    NASA Astrophysics Data System (ADS)

    Colomés, E.; Marian, D.; Oriols, X.

    2015-10-01

    Quantum transport is commonly studied with the use of quasi-particle infinite- extended states. This leads to a powerful formalism, the scattering-states theory, able to capture in compact formulas quantities of interest, such as average current, noise, etc.. However, when investigating the spatial size-dependence of quasi-particle wave packets in quantum noise with exchange and tunneling, unexpected new terms appear in the quantum noise expression. For this purpose, the two particle transmission and reflection probabilities for two initial one-particle wave packets (with opposite central momentums) spatially localized at each side of a potential barrier are studied. After the interaction, each wave packet splits into a transmitted and a reflected component. It can be shown that the probability of detecting two (identically injected) electrons at the same side of the barrier is different from zero in very common (single or double barrier) scenarios. This originates an increase of quantum noise which cannot be obtained through the scattering states formalism.

  9. Granular size of potato starch affects structural properties, octenylsuccinic anhydride modification and flowability.

    PubMed

    Wang, Chan; Tang, Chuan-He; Fu, Xiong; Huang, Qiang; Zhang, Bin

    2016-12-01

    Native potato starch (PS) granules were separated into three size fractions: larger than 30μm (P-L), 15-30μm (P-M), and smaller than 15μm (P-S). The morphological and crystalline structure of fractionated potato starches were investigated by light and scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The P-L fraction showed ellipsoidal shape and B-type X-ray pattern, whereas the P-S fraction had spherical shape and A-type pattern. The fluorophore-assisted capillary electrophoresis data showed that the P-L fraction had more B2 chains and less short A and B1 chains than the P-S counterparts. Smaller granules with larger specific surface area had higher degree of substitution when reacted with octenylsuccinic anhydride (OSA), and showed more uniform distribution of octenylsuccinate substituents. Both OSA modified and unmodified P-S samples showed higher flowability compared with the P-L counterparts. PMID:27374555

  10. Navy Bean Flour Particle Size and Protein Content Affect Cake Baking and Batter Quality(1).

    PubMed

    Singh, Mukti; Byars, Jeffrey A; Liu, Sean X

    2015-06-01

    Whole navy bean flour and its fine and coarse particle size fractions were used to completely replace wheat flour in cakes. Replacement of wheat flour with whole bean flour significantly increased the protein content. The protein content was adjusted to 3 levels with navy bean starch. The effect of navy bean flour and its fractions at 3 levels of protein on cake batter rheology and cake quality was studied and compared with wheat flour samples. Batters prepared from navy bean flour and its fractions had higher viscosity than the cake flour. Reducing the protein content by addition of starch significantly lowered the viscosity of cake batters. The whole navy bean flour and coarse bean fraction cakes were softer than cakes made with wheat flour but had reduced springiness. Principal component analysis showed a clear discrimination of cakes according to protein. It also showed that low protein navy bean flour cakes were similar to wheat flour cakes. Navy bean flour with protein content adjusted to the level of cake (wheat) flour has potential as a healthy alternative in gluten-free cakes. PMID:25922214

  11. Overexpression of diacylglycerol acyltransferase in Yarrowia lipolytica affects lipid body size, number and distribution.

    PubMed

    Gajdoš, Peter; Ledesma-Amaro, Rodrigo; Nicaud, Jean-Marc; Čertík, Milan; Rossignol, Tristan

    2016-09-01

    In the oleaginous yeast Yarrowia lipolytica, the diacylglycerol acyltransferases (DGATs) are major factors for triacylglycerol (TAG) synthesis. The Q4 strain, in which the four acyltransferases have been deleted, is unable to accumulate lipids and to form lipid bodies (LBs). However, the expression of a single acyltransferase in this strain restores TAG accumulation and LB formation. Using this system, it becomes possible to characterize the activity and specificity of an individual DGAT. Here, we examined the effects of DGAT overexpression on lipid accumulation and LB formation in Y. lipolytica Specifically, we evaluated the consequences of introducing one or two copies of the Y. lipolytica DGAT genes YlDGA1 and YlDGA2 Overall, multi-copy DGAT overexpression increased the lipid content of yeast cells. However, the size and distribution of LBs depended on the specific DGAT overexpressed. YlDGA2 overexpression caused the formation of large LBs, while YlDGA1 overexpression generated smaller but more numerous LBs. This phenotype was accentuated through the addition of a second copy of the overexpressed gene and might be linked to the distinct subcellular localization of each DGAT, i.e. YlDga1 being localized in LBs, while YlDga2 being localized in a structure strongly resembling the endoplasmic reticulum. PMID:27506614

  12. Gene size differentially affects the binding of yeast transcription factor tau to two intragenic regions.

    PubMed Central

    Baker, R E; Camier, S; Sentenac, A; Hall, B D

    1987-01-01

    Yeast transcription factor tau (transcription factor IIIC) specifically interacts with tRNA genes, binding to both the A block and the B block elements of the internal promoter. To study the influence of A block-B block spacing, we analyzed the binding of purified tau protein to a series of internally deleted yeast tRNA(3Leu) genes with A and B blocks separated by 0 to 74 base pairs. Optimal binding occurred with genes having A block-B block distances of 30-60 base pairs; the relative helical orientation of the A and B blocks was unimportant. Results from DNase I "footprinting" and lambda exonuclease protection experiments were consistent with these findings and further revealed that changes in A block-B block distance primarily affect the ability of tau to interact with A block sequences; B block interactions are unaltered. When the A block-B block distance is 17 base pairs or less, tau interacts with a sequence located 15 base pairs upstream of the normal A block, and a new RNA initiation site is observed by in vitro transcription. We propose that the initial binding of tau to the B block activates transcription by enhancing its ability to bind at the A block, and that the A block interaction ultimately directs initiation by RNA polymerase III. Images PMID:2827154

  13. Processing Conditions Affecting Grain Size and Mechanical Properties in Nanocomposites Produced via Cold Spray

    NASA Astrophysics Data System (ADS)

    Cavaliere, P.; Perrone, A.; Silvello, A.

    2014-10-01

    Cold spray is a coating technology based on aerodynamics and high-speed impact dynamics. In this process, spray particles (usually 1-50 μm in diameter) are accelerated to a high velocity (typically 300-1200 m/s) by a high-speed gas (pre-heated air, nitrogen, or helium) flow that is generated through a convergent-divergent de Laval-type nozzle. A coating is formed through the intensive plastic deformation of particles impacting on a substrate at a temperature below the melting point of the spray material. In the present paper the main processing parameters affecting the microstructural and mechanical behavior of metal-metal cold spray deposits are described. The effect of process parameters on grain refinement and mechanical properties were analyzed for composite particles of Al-Al2O3, Ni-BN, Cu-Al2O3, and Co-SiC. The properties of the formed nanocomposites were compared with those of the parent materials sprayed under the same conditions. The process conditions, leading to a strong grain refinement with an acceptable level of the deposit mechanical properties such as porosity and adhesion strength, are discussed.

  14. Parameter sensitivities affecting the flutter speed of a MW-sized blade.

    SciTech Connect

    Lobitz, Donald Wayne, Jr.

    2004-10-01

    With the current trend toward larger and larger horizontal axis wind turbines, classical flutter is becoming a more critical issue. Recent studies have indicated that for a single blade turning in still air the flutter speed for a modern 35 m blade occurs at approximately twice its operating speed (2 per rev), whereas for smaller blades (5-9 m), both modern and early designs, the flutter speeds are in the range of 3.5-6 per rev. Scaling studies demonstrate that the per rev flutter speed should not change with scale. Thus, design requirements that change with increasing blade size are producing the concurrent reduction in per rev flutter speeds. In comparison with an early small blade design (5 m blade), flutter computations indicate that the non rotating modes which combine to create the flutter mode change as the blade becomes larger (i.e., for the larger blade the second flapwise mode, as opposed to the first flapwise mode for the smaller blade, combines with the first torsional mode to produce the flutter mode). For the more modern smaller blade design (9 m blade), results show that the non rotating modes that couple are similar to those of the larger blade. For the wings of fixed-wing aircraft, it is common knowledge that judicious selection of certain design parameters can increase the airspeed associated with the onset of flutter. Two parameters, the chordwise location of the center of mass and the ratio of the flapwise natural frequency to the torsional natural frequency, are especially significant. In this paper studies are performed to determine the sensitivity of the per rev flutter speed to these parameters for a 35 m wind turbine blade. Additional studies are performed to determine which structural characteristics of the blade are most significant in explaining the previously mentioned per rev flutter speed differences. As a point of interest, flutter results are also reported for two recently designed 9 m twist/coupled blades.

  15. Parameter sensitivities affecting the flutter speed of a MW-sized blade.

    SciTech Connect

    Lobitz, Donald Wayne, Jr.

    2005-08-01

    With the current trend toward larger and larger horizontal axis wind turbines, classical flutter is becoming a more critical issue. Recent studies have indicated that for a single blade turning in still air the flutter speed for a modern 35 m blade occurs at approximately twice its operating speed (2 per rev), whereas for smaller blades (5-9 m), both modern and early designs, the flutter speeds are in the range of 3.5-6 per rev. Scaling studies demonstrate that the per rev flutter speed should not change with scale. Thus, design requirements that change with increasing blade size are producing the concurrent reduction in per rev flutter speeds. In comparison with an early small blade design (5 m blade), flutter computations indicate that the non rotating modes which combine to create the flutter mode change as the blade becomes larger (i.e., for the larger blade the second flapwise mode, as opposed to the first flapwise mode for the smaller blade, combines with the first torsional mode to produce the flutter mode). For the more modern smaller blade design (9 m blade), results show that the non rotating modes that couple are similar to those of the larger blade. For the wings of fixed-wing aircraft, it is common knowledge that judicious selection of certain design parameters can increase the airspeed associated with the onset of flutter. Two parameters, the chordwise location of the center of mass and the ratio of the flapwise natural frequency to the torsional natural frequency, are especially significant. In this paper studies are performed to determine the sensitivity of the per rev flutter speed to these parameters for a 35 m wind turbine blade. Additional studies are performed to determine which structural characteristics of the blade are most significant in explaining the previously mentioned per rev flutter speed differences. As a point of interest, flutter results are also reported for two recently designed 9 m twist/coupled blades.

  16. Fire affects size and shape of Fabiana imbricata Shurblands in northwestern Patagonia

    NASA Astrophysics Data System (ADS)

    Oddi, Facundo; Ghermandi, Luciana

    2010-05-01

    Fire is a major environmental ecological agent acting in the landscape configuration and a factor that models vegetation in Mediterranean environments. Fire impacts differently in the landscape due to the intrinsic heterogeneity of the environments and the characteristics associated with each fire event. After fire, density of patches may be increased and the size of them may be reduced because fire generates areas of different successional stages. Landscape ecology seems to be the ideal theoretical approach to study the fire impact in fire prone environments. Landscape ecology has been greatly favoured by a significant progress in the last years of geographic information technologies (GIT) (remote sensing, GIS, GPS). The study area of this work is the San Ramon ranch (22,000 ha) located in Northwester Patagonia in the ecotone between the sub Antarctic forest in the West and the Patagonian steppe in the East. We studied sectors of the ranch with different fire recurrence in the last 40 years and we mapped Fabiana imbricata shrubland with GPS. This specie is a native shrub characteristic of Northwester Patagonia grasslands and its dynamic is not very known. Shrublands compete for the space with palatable grasses that are used for forage and livestock production, the main economic resource of the region. We analysed the mapped patches with GIS software, and we assessed landscape metrics to determine differences between sites with different fire recurrence. In the future we foresee the integrated use of satellite imagery with different resolution to add to GIS other important spatial variables (topography, hydrography, aspect, soil) to develop models that can explain landscape metrics, spatial configuration and the potential shrub invasion in the grassland.

  17. Maternal immune activation affects litter success, size and neuroendocrine responses related to behavior in adult offspring.

    PubMed

    French, Susannah S; Chester, Emily M; Demas, Gregory E

    2013-07-01

    It is increasingly evident that influences other than genetics can contribute to offspring phenotype. In particular, maternal influences are an important contributing factor to offspring survival, development, physiology and behavior. Common environmental pathogens such as viral or bacterial microorganisms can induce maternal immune responses, which have the potential to alter the prenatal environment via multiple independent pathways. The effects of maternal immune activation on endocrine responses and behavior are less well studied and provide the basis for the current study. Our approach in the current study was two-pronged: 1) quantify sickness responses during pregnancy in adult female hamsters experiencing varying severity of immune responsiveness (i.e., differing doses of lipopolysaccharide [LPS]), and 2) assess the effects of maternal immune activation on offspring development, immunocompetence, hormone profiles, and social behavior during adulthood. Pregnancy success decreased with increasing doses of LPS, and litter size was reduced in LPS dams that managed to successfully reproduce. Unexpectedly, pregnant females treated with LPS showed a hypothermic response in addition to the more typical anorexic and body mass changes associated with sickness. Significant endocrine changes related to behavior were observed in the offspring of LPS-treated dams; these effects were apparent in adulthood. Specifically, offspring from LPS treated dams showed significantly greater cortisol responses to stressful resident-intruder encounters compared with offspring from control dams. Post-behavior cortisol was elevated in male LPS offspring relative to the offspring of control dams, and was positively correlated with the frequency of bites during agonistic interactions, and cortisol levels in both sexes were related to defensive behaviors, suggesting that changes in hypothalamo-pituitary-adrenal axis responsiveness may play a regulatory role in the observed behavioral

  18. Urban bat communities are affected by wetland size, quality, and pollution levels.

    PubMed

    Straka, Tanja Maria; Lentini, Pia Eloise; Lumsden, Linda Faye; Wintle, Brendan Anthony; van der Ree, Rodney

    2016-07-01

    Wetlands support unique biota and provide important ecosystem services. These services are highly threatened due to the rate of loss and relative rarity of wetlands in most landscapes, an issue that is exacerbated in highly modified urban environments. Despite this, critical ecological knowledge is currently lacking for many wetland-dependent taxa, such as insectivorous bats, which can persist in urban areas if their habitats are managed appropriately. Here, we use a novel paired landscape approach to investigate the role of wetlands in urban bat conservation and examine local and landscape factors driving bat species richness and activity. We acoustically monitored bat activity at 58 urban wetlands and 35 nonwetland sites (ecologically similar sites without free-standing water) in the greater Melbourne area, southeastern Australia. We analyzed bat species richness and activity patterns using generalized linear mixed-effects models. We found that the presence of water in urban Melbourne was an important driver of bat species richness and activity at a landscape scale. Increasing distance to bushland and increasing levels of heavy metal pollution within the waterbody also negatively influenced bat richness and individual species activity. Areas with high levels of artificial night light had reduced bat species richness, and reduced activity for all species except those adapted to urban areas, such as the White-striped free-tailed bat (Austronomus australis). Increased surrounding tree cover and wetland size had a positive effect on bat species richness. Our findings indicate that wetlands form critical habitats for insectivorous bats in urban environments. Large, unlit, and unpolluted wetlands flanked by high tree cover in close proximity to bushland contribute most to the richness of the bat community. Our findings clarify the role of wetlands for insectivorous bats in urban areas and will also allow for the preservation, construction, and management of wetlands

  19. Liquation Microfissuring in the Weld Heat-Affected Zone of an Overaged Precipitation-Hardened Nickel-Base Superalloy

    NASA Astrophysics Data System (ADS)

    Ojo, O. A.; Chaturvedi, M. C.

    2007-02-01

    The effect of preweld overaging heat treatment on the microstructural response in the heat-affected zone (HAZ) of a precipitation-hardened nickel-base superalloy INCONEL 738LC subjected to the welding thermal cycle ( i.e., rapid) was investigated. The overaging heat treatment resulted in the formation of an interfacial microconstituent containing M23X6 particles and coarsening of primary and secondary γ' precipitates. The HAZ microstructures around welds in the overaged alloy were simulated using the Gleeble thermomechanical simulation system. Microstructural examination of simulated HAZs and those present in tungsten inert gas (TIG) welded specimens showed the occurrence of extensive grain boundary liquation involving liquation reaction of the interfacial microconstituents containing M23X6 particles and MC-type carbides. In addition, the coarsened γ' precipitate particles present in the overaged alloy persisted well above their solvus temperature to temperatures where they constitutionally liquated and contributed to considerable liquation of grain boundaries, during continuous rapid heating. Intergranular HAZ microfissuring, with resolidified product formed mostly on one side of the microfissures, was observed in welded specimens. This suggested that the HAZ microfissuring generally occurred by decohesion across one of the solid-liquid interfaces during the grain boundary liquation stage of the weld thermal cycle. Correlation of simulated HAZ microstructures with hot ductility properties of the alloy revealed that the temperature at which the alloy exhibited zero ductility during heating was within the temperature range at which grain boundary liquation was observed. The on-cooling ductility of the alloy was significantly damaged by the on-heating liquation reaction, as reflected by the considerably low ductility recovery temperature (DRT). Important characteristics of the intergranular liquid that could influence HAZ microfissuring of the alloy in overaged

  20. A SYNCHROTRON DIFFRACTION STUDY OF TRANSFORMATION BEHAVIOUR IN 9 CR STEELS USING SIMULATED WELD HEAT-AFFECTED ZONE CONDITIONS

    SciTech Connect

    Santella, Michael L; Specht, Eliot D; Shingledecker, John P; Abe, Fujio

    2007-01-01

    Synchrotron diffraction experiments were conducted to examine the real-time transformation behaviours of an ex-perimental 9Cr-3W-3Co-NbV steel with high B and low N (N130B), and the commercial P92 steel under simulated weld heat-affected zone thermal cycles. When heated to peak temperatures near 1100 C, both steels rapidly trans-formed from ferrite to 100% austenite. During cooling, both transformed to martensite near 400 C. Both steels also retained untransformed austenite: 1.7% in N130B, and 5.8% in P92. The N130B was also heated to about 60 C above its A3 of 847 C. About 56% of the original ferrite never transformed to austenite. During cooling an additional 21% of ferrite and 23% of martensite formed. It retained no austenite. The P92 was heated to just above its A3 of 889 C. About 15% of the original ferrite never transformed to austenite. During cooling an additional 22% of ferrite and 60% of martensite formed. This steel retained about 2.3% austenite. Metallographic examina-tions indicated that the M23C6 in N130B was much more stable than that in P92 for heating to the lower peak tem-peratures. Analysis using equilibrium thermodynamics suggested that the more stable M23C6 in N130B could raise its apparent A3 by sequestering C. This could cause the ferrite-austenite transformation to appear sluggish. Ther-modynamic analysis also indicated that the M23C6 in N130B contained about 3.9 at% B compared to about 0.08 at% B in that of P92. In contrast, the refractory metal element content of the M23C6 was predicted to be higher in P92.

  1. Interdisciplinary mathematics and science: Characteristics, forms, and related effect sizes for student achievement and affective outcomes

    NASA Astrophysics Data System (ADS)

    Hurley, Marlene M.

    1999-12-01

    This study provides an analytic description of quasi-experimental studies that may either support or deny the wisdom of educational reform through interdisciplinary mathematics and science. Interdisciplinarity is examined on two dimensions, the philosophic and the pedagogic, and by two methodologies, meta-analytic and qualitative, in a search for greater understanding of the definitions, forms, characteristics, and effects from studies of interdisciplinary mathematics and science. Thirty-four studies were collected from a search of the literature that spanned the century, the grade levels, and included many forms of interdisciplinarity. Several research questions were asked: (1) What forms of interdisciplinarity, philosophically and practically, are represented by the studies? (2) What are their qualitative effects in school settings? (3) What are the characteristics of interdisciplinary quasi-experimental research? (4) What achievement effects typify the interdisciplinary comparative studies? (5) What factors account for variation in these achievement effects? (6) What claims or criticisms regarding interdisciplinarity are supported or refuted by the qualitative analysis of forms and effects and the quantitative meta-analytic study? Results from this study support the concerns that terms of interdisciplinarity are used without regard for context and that there is a trend toward a great diversity of ideas regarding the nature of interdisciplinary education. Student achievement data were provided by the 34 studies for mathematics and/or science. The mean effect sizes for student achievement were computed as: mathematics achievement, .27 (SE = .09); science achievement, .37 (SE = .12). Curricular materials developed by teachers were significantly less related to student achievement than materials developed by researchers or commercially. The methods of integration employed by the 34 studies formed a continuum from sequenced instructional integration to total

  2. Sample Size Calculation: Inaccurate A Priori Assumptions for Nuisance Parameters Can Greatly Affect the Power of a Randomized Controlled Trial

    PubMed Central

    Tavernier, Elsa; Giraudeau, Bruno

    2015-01-01

    We aimed to examine the extent to which inaccurate assumptions for nuisance parameters used to calculate sample size can affect the power of a randomized controlled trial (RCT). In a simulation study, we separately considered an RCT with continuous, dichotomous or time-to-event outcomes, with associated nuisance parameters of standard deviation, success rate in the control group and survival rate in the control group at some time point, respectively. For each type of outcome, we calculated a required sample size N for a hypothesized treatment effect, an assumed nuisance parameter and a nominal power of 80%. We then assumed a nuisance parameter associated with a relative error at the design stage. For each type of outcome, we randomly drew 10,000 relative errors of the associated nuisance parameter (from empirical distributions derived from a previously published review). Then, retro-fitting the sample size formula, we derived, for the pre-calculated sample size N, the real power of the RCT, taking into account the relative error for the nuisance parameter. In total, 23%, 0% and 18% of RCTs with continuous, binary and time-to-event outcomes, respectively, were underpowered (i.e., the real power was < 60%, as compared with the 80% nominal power); 41%, 16% and 6%, respectively, were overpowered (i.e., with real power > 90%). Even with proper calculation of sample size, a substantial number of trials are underpowered or overpowered because of imprecise knowledge of nuisance parameters. Such findings raise questions about how sample size for RCTs should be determined. PMID:26173007

  3. Factors affecting size and swelling of poly(ethylene glycol) microspheres formed in aqueous sodium sulfate solutions without surfactants.

    PubMed

    Nichols, Michael D; Scott, Evan A; Elbert, Donald L

    2009-10-01

    The LCST behavior of poly(ethylene glycol) (PEG) in aqueous sodium sulfate solutions was exploited to fabricate microspheres without the use of other monomers, polymers, surfactants or organic solvents. Reactive PEG derivatives underwent thermally induced phase separation to produce spherical PEG-rich domains that coarsened in size pending gelation, resulting in stable hydrogel microspheres between approximately 1 and 100 microns in size. The time required to reach the gel point during the coarsening process and the extent of crosslinking after gelation both affected the final microsphere size and swelling ratio. The gel point could be varied by pre-reaction of the PEG derivatives below the cloud point, or by controlling pH and temperature above the cloud point. Pre-reaction brought the PEG derivatives closer to the gel point prior to phase separation, while the pH and temperature influenced the rate of reaction. Dynamic light scattering indicated a percolation-to-cluster transition about 3-5 min following phase separation. The mean radius of PEG-rich droplets subsequently increased with time to the 1/4th power until gelation. PEG microspheres produced by these methods with controlled sizes and densities may be useful for the production of modular scaffolds for tissue engineering. PMID:19615738

  4. Contents and toxicity of heavy metals in soils of the zone affected by aerial emissions from the Severonikel Enterprise

    NASA Astrophysics Data System (ADS)

    Evdokimova, G. A.; Kalabin, G. V.; Mozgova, N. P.

    2011-02-01

    In 2009, the zoning of the terrestrial ecosystems in the area exposed to aerial emissions from the Severonikel Enterprise (Murmansk oblast) was performed on the basis of the parameters characterizing the state of the soils, including the contents of the main heavy metal pollutants and exchangeable calcium and magnesium, the soils' pH, the ratio of the organic to mineral soil components, and the state of the soils' microbiota. Three zones differing in the degree of the soil pollution were delimited. These were the zones of heavy, moderate, and weak pollution, which extended for up to 3, 25, and 50 km from the emission source in the prevailing wind direction. The data on the amount of bacterial and fungal biomass provided evidence of the profound degradation of the soils in the heavily polluted zone. In particular, the biomass of the soil microbiota, including its prokaryotic and eukaryotic components, was two to six times lower in this zone than in the background (control) area. The soils of the heavily polluted zone can be classified as strongly toxic for plants, and most of the soils of the moderately polluted zone also fall into the same category.

  5. Calibrated heat flow model for the determination of different heat-affected zones in single-pass laser-cut CFRP using a cw CO2 laser

    NASA Astrophysics Data System (ADS)

    Mucha, P.; Berger, P.; Weber, R.; Speker, N.; Sommer, B.; Graf, T.

    2015-03-01

    Laser machining has great potential for automated manufacturing of parts made of carbon-fiber-reinforced plastic (CFRP) due to the nearly force and tool-wear free processing. The high vaporization temperatures and the large heat conductivity of the carbon fibers, however, lead to unintentional heat conduction into the material causing damage in zones close to the process. In this paper, the matrix damage zone (MDZ) is subdivided into a matrix sublimation zone (MSZ) where the matrix material was sublimated and a zone where the temperature temporarily exceeded a value causing structural damage in the matrix. In order to investigate the extent of these zones, a one-dimensional heat flow model was applied, which was calibrated by cutting experiments using temperature sensors embedded in the CFRP samples. The investigations showed that the extents of the MSZ and MDZ are dominated by a total interaction time, which includes the passage of the laser beam and the continued interaction of the cloud of hot ablation products with the carbon fibers at the kerf wall and that from a practical point of view, the experimentally determined effective heat conductivity is suitable for simple estimations of the heat-affected zones in CFRP.

  6. Can interface features affect aggression resulting from violent video game play? An examination of realistic controller and large screen size.

    PubMed

    Kim, Ki Joon; Sundar, S Shyam

    2013-05-01

    Aggressiveness attributed to violent video game play is typically studied as a function of the content features of the game. However, can interface features of the game also affect aggression? Guided by the General Aggression Model (GAM), we examine the controller type (gun replica vs. mouse) and screen size (large vs. small) as key technological aspects that may affect the state aggression of gamers, with spatial presence and arousal as potential mediators. Results from a between-subjects experiment showed that a realistic controller and a large screen display induced greater aggression, presence, and arousal than a conventional mouse and a small screen display, respectively, and confirmed that trait aggression was a significant predictor of gamers' state aggression. Contrary to GAM, however, arousal showed no effects on aggression; instead, presence emerged as a significant mediator. PMID:23505967

  7. On the spatial variability of the hyporheic zone: in-situ investigation of porosity and grain size using diving bells and 3D photogrammetry

    NASA Astrophysics Data System (ADS)

    Frings, R. M.; Vollmer, S.

    2012-04-01

    In order to improve the ecological status of rivers, lakes and other water bodies, recent legislation, such as the European Water Framework Directive, requires for each water body an assessment of its suitability as habitat for organisms. Such an assessment, though, is not easy. This is especially true for the lowest part of the water body: the substrate or hyporheic zone. Even if it is known which kind of hyporheic zone is preferred by an organism, it remains difficult to determine where it can be found, because it is often impossible to observe the hyporheic zone from the banks or shores. It has become common to classify an entire water body as suitable or unsuitable as habitat, using only limited field observations of the hyporheic zone. This is a doubtful practice, which disregards the huge spatial variability of this zone. The objective of this study was to quantify the spatial variability in hyporheic-zone characteristics in the river Rhine. We focused on two basic characteristics: grain size and porosity, the latter being a primary control on the transport of nutrients, heat, oxygen and organic matter. A diving bell (caisson) was used to obtain access to the river bed, which enabled undisturbed sampling of the hyporheic zone. Between 1968 and 2009 6436 sediment samples were taken and sieved to determine their grain size distribution. Furthermore, in 2009 and 2011 about 100 porosity measurements were carried out, using a novel technique based on a combination of field measurements using three-dimensional photogrammetry and laboratory measurements using the water displacement method. The measurements revealed a strong cross-sectional variability in porosity and grain size. Each river cross-section contains spots with high porosity (order 0.40) and spots with low porosity (order 0.10). The large cross-sectional variability made it impossible to recognize systematic streamwise porosity trends from the data. Therefore we investigated if porosity was correlated to

  8. Increasing lengths of aftershock zones with depths of moderate-size earthquakes on the San Jacinto Fault suggests triggering of deep creep in the middle crust

    NASA Astrophysics Data System (ADS)

    Meng, Xiaofeng; Peng, Zhigang

    2016-01-01

    Recent geodetic studies along the San Jacinto Fault (SJF) in southern California revealed a shallower locking depth than the seismogenic depth outlined by microseismicity. This disagreement leads to speculations that creeping episodes drive seismicity in the lower part of the seismogenic zone. Whether deep creep occurs along the SJF holds key information on how fault slips during earthquake cycle and potential seismic hazard imposed to southern California. Here we apply a matched filter technique to 10 M > 4 earthquake sequences along the SJF since 2000 and obtain more complete earthquake catalogues. We then systematic investigate spatio-temporal evolutions of these aftershock sequences. We find anomalously large aftershock zones for earthquakes occurred below the geodetically inferred locking depth (i.e. 11-12 km), while aftershock zones of shallower main shocks are close to expectations from standard scaling relationships. Although we do not observe clear migration of aftershocks, most aftershock zones do expand systematically with logarithmic time since the main shock. All the evidences suggest that aftershocks near or below the locking depth are likely driven by deep creep following the main shock. The presence of a creeping zone below 11-12 km may have significant implications on the maximum sizes of events in this region.

  9. Analytical Investigation of the Decrease in the Size of the Habitable Zone Due to a Limited CO2 Outgassing Rate

    NASA Astrophysics Data System (ADS)

    Abbot, Dorian S.

    2016-08-01

    The habitable zone concept is important because it focuses the scientific search for extraterrestrial life and aids the planning of future telescopes. Recent work has shown that planets near the outer edge of the habitable zone might not actually be able to stay warm and habitable if CO2 outgassing rates are not large enough to maintain high CO2 partial pressures against removal by silicate weathering. In this paper, I use simple equations for the climate and CO2 budget of a planet in the habitable zone that can capture the qualitative behavior of the system. With these equations I derive an analytical formula for an effective outer edge of the habitable zone, including limitations imposed by the CO2 outgassing rate. I then show that climate cycles between a snowball state and a warm climate are only possible beyond this limit if the weathering rate in the snowball climate is smaller than the CO2 outgassing rate (otherwise stable snowball states result). I derive an analytical solution for the climate cycles including a formula for their period in this limit. This work allows us to explore the qualitative effects of weathering processes on the effective outer edge of the habitable zone, which is important because weathering parameterizations are uncertain.

  10. 7 CFR 4290.760 - How a change in size or activity of a Portfolio Concern affects the RBIC and the Portfolio Concern.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false How a change in size or activity of a Portfolio Concern affects the RBIC and the Portfolio Concern. 4290.760 Section 4290.760 Agriculture Regulations of... size or activity of a Portfolio Concern affects the RBIC and the Portfolio Concern. (a) Effect on...

  11. Upgrade of the hot zone for large-size high-performance multi-crystalline silicon ingot casting

    NASA Astrophysics Data System (ADS)

    Wu, Zhiyong; Zhong, Genxiang; Zhou, Xucheng; Zhang, Zhaoyu; Wang, Zixu; Chen, Wenliang; Huang, Xinming

    2016-05-01

    Casting larger silicon ingots by upgrading the hot zone is one of the main methods used to reduce the cost of multi-crystalline silicon wafers. In this paper, a new hot zone is designed and a transient global model is applied to investigate the effects of the new hot zone on the electricity consumption, the crystal growth rate, and the shape of the C-M interface during the solidification process. Based on the simulation results, a generation-five, directional-solidification furnace was upgraded and implemented in casting experiments. The experimental results show that the feedstock capacity increased by 77.8%, the crystal growth efficiency increased by 53.8%, and the average yield rate of the silicon ingots increased by 9%. The crystal-melt interface was flatter and the growth direction of the grains was almost straight upward.

  12. Exploring the size adaptability of the B ring binding zone of the colchicine site of tubulin with para-nitrogen substituted isocombretastatins.

    PubMed

    Jiménez, Carmen; Ellahioui, Younes; Álvarez, Raquel; Aramburu, Laura; Riesco, Alejandra; González, Myriam; Vicente, Alba; Dahdouh, Abdelaziz; Ibn Mansour, Ahmed; Jiménez, Carlos; Martín, Diego; Sarmiento, Rogelio G; Medarde, Manuel; Caballero, Esther; Peláez, Rafael

    2015-07-15

    We have synthesized and assayed dimethylaminophenyl, pyrrolidin-1-ylphenyl and carbazole containing phenstatins and isocombretastatins as analogues of the highly potent indoleisocombretastatins with extended or reduced ring sizes. This is an attempt to explore beyond the structural constraints of the X-ray crystal structures the zone of the colchicine site where the tropolone ring of colchicine binds to tubulin (zone 1). The isocombretastatins display up to 30 fold increased water solubility when compared with combretastatin A-4, potent inhibition of tubulin polymerization, and nanomolar cytotoxicities against several human cancer cell lines irrespective of the size of the B ring. On the other hand, substitutions ortho to the nitrogen cause an important reduction in potency. We have also shown that representative compounds inhibit autophagy. These results show that zone 1 can adapt to systems of different size as far as they stay in a common plane, but does not tolerate substituents protruding above or below it. These results can help in the understanding of the binding modes of structures with similar systems and in the design of new colchicine site ligands. PMID:26092446

  13. Impacts of Different Tree Species of Different Sizes on Spatial Distribution of Herbaceous Plants in the Nigerian Guinea Savannah Ecological Zone

    PubMed Central

    Buba, Toma

    2015-01-01

    This study was aimed at finding the impacts of different tree species and individual trees of different sizes on species richness, diversity, and composition of the herbaceous layer. All the three tree species have greatly increased species richness and diversity both within and outside their crown zones compared with the open grassland. Both species richness and diversity were found to be higher under all the three tree species than outside their crowns, which was in turn higher than the open field. Daniella oliveri has the highest species richness and diversity both within and outside its crown zone followed by Vitellaria paradoxa and then Parkia biglobosa. The result also revealed that the same tree species with different sizes leads to different herbaceous species richness, diversity, and composition under and around the trees' crowns. P. biglobosa and V. paradoxa trees with smaller sizes showed higher species richness and diversity under their crowns than the bigger ones. The dissimilarity of species composition differs between the inside and outside crown zones of the individuals of the same tree species and among the different trees species and the open field. PMID:26618024

  14. Impacts of Different Tree Species of Different Sizes on Spatial Distribution of Herbaceous Plants in the Nigerian Guinea Savannah Ecological Zone.

    PubMed

    Buba, Toma

    2015-01-01

    This study was aimed at finding the impacts of different tree species and individual trees of different sizes on species richness, diversity, and composition of the herbaceous layer. All the three tree species have greatly increased species richness and diversity both within and outside their crown zones compared with the open grassland. Both species richness and diversity were found to be higher under all the three tree species than outside their crowns, which was in turn higher than the open field. Daniella oliveri has the highest species richness and diversity both within and outside its crown zone followed by Vitellaria paradoxa and then Parkia biglobosa. The result also revealed that the same tree species with different sizes leads to different herbaceous species richness, diversity, and composition under and around the trees' crowns. P. biglobosa and V. paradoxa trees with smaller sizes showed higher species richness and diversity under their crowns than the bigger ones. The dissimilarity of species composition differs between the inside and outside crown zones of the individuals of the same tree species and among the different trees species and the open field. PMID:26618024

  15. Floral display size, conspecific density and florivory affect fruit set in natural populations of Phlox hirsuta, an endangered species

    PubMed Central

    Ruane, Lauren G.; Rotzin, Andrew T.; Congleton, Philip H.

    2014-01-01

    Background and Aims Natural variation in fruit and seed set may be explained by factors that affect the composition of pollen grains on stigmas. Self-incompatible species require compatible outcross pollen grains to produce seeds. The siring success of outcross pollen grains, however, can be hindered if self (or other incompatible) pollen grains co-occur on stigmas. This study identifies factors that determine fruit set in Phlox hirsuta, a self-sterile endangered species that is prone to self-pollination, and its associated fitness costs. Methods Multiple linear regressions were used to identify factors that explain variation in percentage fruit set within three of the five known populations of this endangered species. Florivorous beetle density, petal colour, floral display size, local conspecific density and pre-dispersal seed predation were quantified and their effects on the ability of flowers to produce fruits were assessed. Key Results In all three populations, percentage fruit set decreased as florivorous beetle density increased and as floral display size increased. The effect of floral display size on fruit set, however, often depended on the density of nearby conspecific plants. High local conspecific densities offset – even reversed – the negative effects of floral display size on percentage fruit set. Seed predation by mammals decreased fruit set in one population. Conclusions The results indicate that seed production in P. hirsuta can be maximized by selectively augmenting populations in areas containing isolated large plants, by reducing the population sizes of florivorous beetles and by excluding mammals that consume unripe fruits. PMID:24557879

  16. How group size affects vigilance dynamics and time allocation patterns: the key role of imitation and tempo.

    PubMed

    Michelena, Pablo; Deneubourg, Jean-Louis

    2011-01-01

    In the context of social foraging, predator detection has been the subject of numerous studies, which acknowledge the adaptive response of the individual to the trade-off between feeding and vigilance. Typically, animals gain energy by increasing their feeding time and decreasing their vigilance effort with increasing group size, without increasing their risk of predation ('group size effect'). Research on the biological utility of vigilance has prevailed over considerations of the mechanistic rules that link individual decisions to group behavior. With sheep as a model species, we identified how the behaviors of conspecifics affect the individual decisions to switch activity. We highlight a simple mechanism whereby the group size effect on collective vigilance dynamics is shaped by two key features: the magnitude of social amplification and intrinsic differences between foraging and scanning bout durations. Our results highlight a positive correlation between the duration of scanning and foraging bouts at the level of the group. This finding reveals the existence of groups with high and low rates of transition between activities, suggesting individual variations in the transition rate, or 'tempo'. We present a mathematical model based on behavioral rules derived from experiments. Our theoretical predictions show that the system is robust in respect to variations in the propensity to imitate scanning and foraging, yet flexible in respect to differences in the duration of activity bouts. The model shows how individual decisions contribute to collective behavior patterns and how the group, in turn, facilitates individual-level adaptive responses. PMID:21525987

  17. How Group Size Affects Vigilance Dynamics and Time Allocation Patterns: The Key Role of Imitation and Tempo

    PubMed Central

    Michelena, Pablo; Deneubourg, Jean-Louis

    2011-01-01

    In the context of social foraging, predator detection has been the subject of numerous studies, which acknowledge the adaptive response of the individual to the trade-off between feeding and vigilance. Typically, animals gain energy by increasing their feeding time and decreasing their vigilance effort with increasing group size, without increasing their risk of predation (‘group size effect’). Research on the biological utility of vigilance has prevailed over considerations of the mechanistic rules that link individual decisions to group behavior. With sheep as a model species, we identified how the behaviors of conspecifics affect the individual decisions to switch activity. We highlight a simple mechanism whereby the group size effect on collective vigilance dynamics is shaped by two key features: the magnitude of social amplification and intrinsic differences between foraging and scanning bout durations. Our results highlight a positive correlation between the duration of scanning and foraging bouts at the level of the group. This finding reveals the existence of groups with high and low rates of transition between activies, suggesting individual variations in the transition rate, or ‘tempo’. We present a mathematical model based on behavioral rules derived from experiments. Our theoretical predictions show that the system is robust in respect to variations in the propensity to imitate scanning and foraging, yet flexible in respect to differences in the duration of activity bouts. The model shows how individual decisions contribute to collective behavior patterns and how the group, in turn, facilitates individual-level adaptive responses. PMID:21525987

  18. Aggregate-cement paste transition zone properties affecting the salt-frost damage of high-performance concretes

    SciTech Connect

    Cwirzen, Andrzej; Penttala, Vesa

    2005-04-01

    The influence of the cement paste-aggregate interfacial transition zone (ITZ) on the frost durability of high-performance silica fume concrete (HPSFC) has been studied. Investigation was carried out on eight non-air-entrained concretes having water-to-binder (W/B) ratios of 0.3, 0.35 and 0.42 and different additions of condensed silica fume. Studies on the microstructure and composition of the cement paste have been made by means of environmental scanning electron microscope (ESEM)-BSE, ESEM-EDX and mercury intrusion porosimetry (MIP) analysis. The results showed that the transition zone initiates and accelerates damaging mechanisms by enhancing movement of the pore solution within the concrete during freezing and thawing cycles. Cracks filled with ettringite were primarily formed in the ITZ. The test concretes having good frost-deicing salt durability featured a narrow transition zone and a decreased Ca/Si atomic ratio in the transition zone compared to the bulk cement paste. Moderate additions of silica fume seemed to densify the microstructure of the ITZ.

  19. Effect of long-term aging on microstructure and local behavior in the heat-affected zone of a Ni–Cr–Mo–V steel welded joint

    SciTech Connect

    Zhu, Ming-Liang Wang, De-Qiang; Xuan, Fu-Zhen

    2014-01-15

    Evolution of microstructure, micro-hardness and micro-tensile strength behavior was investigated in the heat-affected zone of a Ni–Cr–Mo–V steel welded joint after the artificial aging at 350 °C for 3000 h. After detailed characterization of microstructures in optical microscopy, scanning electron microscopy and transmission electron microscopy, it is revealed that the change of martensite–bainite constituent promotes more homogeneous microstructure distribution. The aging treatment facilitates redistribution of carbon and chromium elements along the welded joint, and the micro-hardness is increased slightly through the welds due to enrichment of carbon. The types of precipitates in the weldment mainly include M{sub 3}C, MC, M{sub 2}C and M{sub 23}C{sub 6}. The carbides in base metal, weld metal and coarse-grained heat-affected zone are prone to change from ellipsoidal to platelet form whereas more uniform spherical carbides are observed in the fine-grained zone. Precipitation and coarsening of M{sub 23}C{sub 6} near the fusion line, and formation of MC and M{sub 2}C, are responsible for the tensile strength decrease and its smooth distribution in the aged heat-affected zone. This implies that the thermal aging can relieve strength mismatch in the weldments. - Highlights: • Microstructure homogeneity improved in HAZ after long-term aging. • Tensile strength decreased in HAZ due to precipitation and coarsening of M{sub 23}C{sub 6}. • Strength mismatch in NiCrMoV steel welds was relieved after aging at 350 °C × 3000 h.

  20. Transformation, metallurgical response and behavior of the weld fusion zone and heat affected zone in Cr-Mo steels for fossil energy application: Final technical report for January 1985-September 1987

    SciTech Connect

    Lundin, C.D.; Henning, J.A.; Menon, R.; Khan, K.K.

    1987-09-30

    This research program was undertaken to provide fundamental and basic metallurgical information on the behavior of the heat affected zone (HAZ) in Cr-Mo steel welds as well as practical information on their relative weldability. The principal work was the evaluation of the post weld heat treatment (PWHT) cracking of Cr-Mo steels ranging in Cr content from 2-1/4% to 9%. Differences in observed cracking behavior were contrasted with composition, on cooling transformation behavior and HAZ microstructure. Hydrogen assisted cracking (HAC) studies using a large scale cracking test were conducted on 2-1/4 Cr and 3 Cr steels. Soft zone studies were conducted on 9 Cr NKK steel to determine the reason for the development of a low hardness region (''Soft Zone'') at the outer boundary of the HAZ. The literature review provides a concise historical review and the basis of theories for PWHT cracking and HAC in Cr-Mo steels which were employed to explain the weld cracking susceptibility of various Cr-Mo alloys. PWHT cracking susceptibility was investigated using Gleeble simulated heat affected zone (HAZ) specimens. A new test was developed at the University of Tennessee, The C-ring test, to evaluate the PWHT cracking behavior. The C-ring test was found to be an extremely useful test for PWHT cracking susceptibility and for verifying the results obtained from Gleeble tsting. An excellent correlation was obtained for the two tests. The standard Y-groove test was selected for HAC susceptibility testing. This test is very suitable for evaluating the HAC of the base metal and is defined in Japanese Industrial Standard JIS Z 3158.

  1. Lake size and water-column stability affect the importance of methane for pelagic food webs of boreal lakes

    NASA Astrophysics Data System (ADS)

    Kankaala, Paula; Lopez-Bellido, Jessica; Ojala, Anne; Tulonen, Tiina; Jones, Roger I.

    2013-04-01

    Physical forcing, related to lake size and morphometry, plays an important role in the landscape-scale biogeochemical processing and fluxes of terrestrial carbon in lakes. Boreal lakes are typically dimictic, with mixing of the water column in spring and autumn, but in small, sheltered, humic, forest lakes the spring mixing is often incomplete. This leads to a steep summer stratification and oxygen depletion in the hypolimnion of the lakes. As a result of anaerobic decomposition of organic matter, high concentrations of CH4are typical in these lakes. At the oxic-anoxic interface zone methanotrophic microbes oxidize CH4 to CO2 and partly incorporate CH4-C into microbial biomass, and thus potentially provide a diet source for pelagic consumers. We studied production at the base of the pelagic food web by methane oxidising bacteria (MOB), heterotrophic bacteria (HB) and phytoplankton (PP) in five boreal lakes with a dissolved organic carbon (DOC) concentration varying between 7 and 25 mg C L-1 and an area ranging from 0.004 to 13.4 km2. High MOB activity was detected in the water columns of the three smallest lakes having anoxia in the hypolimnion during summer. The highest MOB activities (ca. 2-12 μmol L-1 d-1) were observed when the CH4:O2 ratio varied between ca. 0.5-12. Seasonally, the highest MOB activities were measured during late-summer mixed layer deepening and autumnal mixing of the whole water column. The proportion of MOB in the total basal production was highest in the two smallest lakes (24-56 and 13-36%), having the steepest summertime stratification. The proportion MOB in the basal production decreased with lake size being 70% of basal production was by PP. In all studied lakes HB contributed only 10-23% of the total basal production, suggesting that a transfer of allochthonous DOC via HB plays only a modest role for the nutrition of the higher trophic levels.

  2. Characterization of Microstructures across the Heat-Affected Zone of the Modified 9Cr-1Mo Weld Joint to Understand Its Role in Promoting Type IV Cracking

    NASA Astrophysics Data System (ADS)

    Laha, K.; Chandravathi, K. S.; Parameswaran, P.; Rao, K. Bhanu Sankara; Mannan, S. L.

    2007-01-01

    In the postweld heat-treated (PWHT) fusion welded modified 9Cr-1Mo steel joint, a soft zone was identified at the outer edge of the heat-affected zone (HAZ) of the base metal adjacent to the deposited weld metal. Hardness and tensile tests were performed on the base metal subjected to soaking for 5 minutes at temperatures below Ac1 to above Ac3 and tempering at the PWHT condition. These tests indicated that the soft zone in the weld joint corresponds to the intercritical region of HAZ. Creep tests were conducted on the base metal and cross weld joint. At relatively lower stresses and higher test temperatures, the weld joint possessed lower creep rupture life than the base metal, and the difference in creep rupture life increased with the decrease in stress and increase in temperature. Preferential accumulation of creep deformation coupled with extensive creep cavitation in the intercritical region of HAZ led to the premature failure of the weld joint in the intercritical region of the HAZ, commonly known as type IV cracking. The microstructures across the HAZ of the weld joint have been characterized to understand the role of microstructure in promoting type IV cracking. Strength reduction in the intercritical HAZ of the joint resulted from the combined effects of coarsening of dislocation substructures and precipitates. Constrained deformation of the soft intercritical HAZ sandwich between relatively stronger constitutes of the joint induced creep cavitation in the soft zone resulting in premature failure.

  3. Tomato growth as affected by root-zone temperature and the addition of gibberellic acid and kinetin to nutrient solutions

    NASA Technical Reports Server (NTRS)

    Bugbee, B.; White, J. W.; Salisbury, F. B. (Principal Investigator)

    1984-01-01

    The effect of root-zone temperature on young tomato plants (Lycopersicon esculentum Mill. cv. Heinz 1350) was evaluated in controlled environments using a recirculating solution culture system. Growth rates were measured at root-zone temperatures of 15 degrees, 20 degrees, 25 degrees, and 30 degrees C in a near optimum foliar environment. Optimum growth occurred at 25 degrees to 30 degrees during the first 4 weeks of growth and 20 degrees to 25 degrees during the 5th and 6th weeks. Growth was severely restricted at 15 degrees. Four concentrations of gibberellic acid (GA3) and kinetin were added to the nutrient solution in a separate trial; root-zone temperature was maintained at 15 degrees and 25 degrees. Addition of 15 micromoles GA3 to solutions increased specific leaf area, total leaf area, and dry weight production of plants in both temperature treatments. GA3-induced growth stimulation was greater at 15 degrees than at 25 degrees. GA3 may promote growth by increasing leaf area, enhancing photosynthesis per unit leaf area, or both. Kinetic was not useful in promoting growth at either temperature.

  4. Colloid formation and metal transport through two mixing zones affected by acid mine drainage near Silverton, Colorado

    USGS Publications Warehouse

    Schemel, L.E.; Kimball, B.A.; Bencala, K.E.

    2000-01-01

    Stream discharges and concentrations of dissolved and colloidal metals (Al, Ca, Cu, Fe, Mg, Mn, Pb, and Zn), SO4, and dissolved silica were measured to identify chemical transformations and determine mass transports through two mixing zones in the Animas River that receive the inflows from Cement and Mineral Creeks. The creeks were the dominant sources of Al, Cu, Fe, and Pb, whereas the upstream Animas River supplied about half of the Zn. With the exception of Fe, which was present in dissolved and colloidal forms, the metals were dissolved in the acidic, high-SO4 waters of Cement Creek (pH 3.8). Mixing of Cement Creek with the Animas River increased pH to near-neutral values and transformed Al and some additional Fe into colloids which also contained Cu and Pb. Aluminium and Fe colloids had already formed in the mildly acidic conditions in Mineral Creek (pH 6.6) upstream of the confluence with the Animas River. Colloidal Fe continued to form downstream of both mixing zones. The Fe- and Al-rich colloids were important for transport of Cu, Pb, and Zn, which appeared to have sorbed to them. Partitioning of Zn between dissolved and colloidal phases was dependent on pH and colloid concentration. Mass balances showed conservative transports for Ca, Mg, Mn, SO4, and dissolved silica through the two mixing zones and small losses (< 10%) of colloidal Al, Fe and Zn from the water column.

  5. An Engineering Solution for Solving Mesh Size Effects in the Simulation of Delamination with Cohesive Zone Models

    NASA Technical Reports Server (NTRS)

    Turon, A.; Davila, C. G.; Camanho, P. P.; Costa, J.

    2007-01-01

    This paper presents a methodology to determine the parameters to be used in the constitutive equations of Cohesive Zone Models employed in the simulation of delamination in composite materials by means of decohesion finite elements. A closed-form expression is developed to define the stiffness of the cohesive layer. A novel procedure that allows the use of coarser meshes of decohesion elements in large-scale computations is also proposed. The procedure ensures that the energy dissipated by the fracture process is computed correctly. It is shown that coarse-meshed models defined using the approach proposed here yield the same results as the models with finer meshes normally used for the simulation of fracture processes.

  6. Diet supplementation with the cis-9,trans-11 conjugated linoleic acid isomer affects the size of adipocytes in Wistar rats.

    PubMed

    Lopes, Paula A; Martins, Susana V; Pinho, Mário S; Alfaia, Cristina M; Fontes, Carlos M G A; Rodrigues, Pedro O; Morais, Graça S L; Castro, Matilde F; Pinto, Rui; Prates, José A M

    2008-07-01

    Previous reports have demonstrated that conjugated linoleic acid (CLA) acts on body fat accumulation in a variety of animal models. The aim of the present study was to investigate the effect of cis (c)-9,trans (t)-11 and t10,c12 CLA isomers on the number and size of adipocytes from the inguinal and retroperitoneal fats in Wistar male rats. A 5.1% palm oil-based diet was supplemented with CLA isomers as follows: 0.6% of c9,t11, 0.6% of t10,c12, 1.3% of c9,t11 and t10,c12 isomers in mixture, and a control nonsupplemented group for comparative purposes. Fat tissues were prepared on microscope slides for histologic examination using an image-analysis software to count the number of adipocytes and measure cell sizes. The results showed that CLA isomers did not affect (P > .05) either final body and fat depot weights or serum lipids (with the exception of triacylglycerols) and adipocytokines (leptin and adiponectin). Animals fed the c9,t11 CLA isomer diet showed larger adipocytes when compared to other groups. Independently of the CLA dietary treatment, retroperitoneal fat showed larger adipocytes (3319 microm(2)) and therefore a smaller number of adipocytes per unit of area, compared to inguinal fat (3055 microm(2)). Taken together, the data suggest that a palm oil-based diet supplemented with the c9,t11 CLA isomer in Wistar rats, in contrast to the t10,c12 isomer and the mixture of both isomers, increases adipocyte dimensions in inguinal and retroperitoneal fat depots, while having a minor effect in serum lipids and adipocytokines. PMID:19083449

  7. The Stress-Relief Cracking Susceptibility of a New Ferritic Steel - Part I: Single-Pass Heat-Affected Zone Simulations

    SciTech Connect

    NAWROCKI,J.G.; DUPONT,J.N.; ROBINO,CHARLES V.; MARDER,A.R.

    1999-12-15

    The stress-relief cracking susceptibility of single-pass welds in a new ferritic steel, HCM2S, has been evaluated and compared to 2.25Cr-1Mo steel using Gleeble techniques. Simulated coarse-grained heat-affected zones (CGHAZ) were produced under a range of energy inputs and tested at various post-weld heat treatment (PWHT) temperatures. Both alloys were tested at a stress of 325 MPa. The 2.25 Cr-1Mo steel was also tested at 270 MPa to normalize for the difference in yield strength between the two materials. Light optical and scanning electron microscopy were used to characterize the CGHAZ microstructure. The ''as-welded'' CGHAZ of each alloy consisted of lath martensite or bainite and had approximately equal prior austenite grain sizes. The as-welded hardness of the 2.25Cr-1Mo steel CGHAZ was significantly higher than that of the HCM2S alloy. Over the range studied energy input had no effect on the as-welded microstructure or hardness of either alloy. The energy input also had no effect on the stress-relief cracking susceptibility of either material. Both alloys failed intergranularly along prior austenite grain boundaries under all test conditions. The 2.25Cr-1Mo steel samples experienced significant macroductility and some microductility when tested at 325 MPa. The ductility decreased significantly when tested at 270 MPa but was still higher that than of HCM2S at each test condition. The time to failure decreased with increasing PWHT Temperature for each material. There was no significant difference in the times to failure between the two materials. Varying energy input and stress had no effect on the time-to failure. The ductility, as measured by reduction in are% increased with increasing PWHT temperature for 2.25 Cr-1Mo steel tested at both stresses. However, PWHT temperature had no effect on the ductility of HCM2S. The hardness of the CGHAZ for 2.25Cr-1Mo steel decreased significantly after PWHT, but remained constant for HCM2S. The differences in stress

  8. Microstructure and Toughness of Simulated Heat-Affected Zone of Laser Welded Joint for 960 MPa Grade High Strength Steel

    NASA Astrophysics Data System (ADS)

    Meng, Wei; Li, Zhuguo; Jiang, Xiaoxia; Huang, Jian; Wu, Yixiong; Katayama, Seiji

    2014-10-01

    The microstructure and toughness of coarse grain zone (CGZ) and mixed grain zone (MGZ) for laser welded 960 MPa grade high strength steel joints were investigated by thermal simulation with a Gleeble-3500 thermal simulator. The results show that microstructure of the stimulated CGZ mainly consists of uniform interweaved lath martensite, and grain growth is not severe upon increasing the cooling time ( t 8/5). Microstructure of the stimulated MGZ presents strip-like in low peak temperature, and small block martensite is formed on the grain boundary. However, in high peak temperature, the strip-like microstructure disappears and small block martensite presents net-like structure. The lath character for MGZ and CGZ is very obvious under TEM observation, and the average lath thickness of BM, MGZ, and CGZ is 100, 150 and 200 nm, respectively. The impact energy and microhardness of CGZ are higher than MGZ and reduce with increasing the cooling time. The fracture toughness deteriorating drastically for MGZ may be related with the formation of the mixture microstructure, in which the small block martensite is distributed in the shape of a network.

  9. Evolution of a Directional Wave Spectrum in a 3D Marginal Ice Zone with Random Floe Size Distribution

    NASA Astrophysics Data System (ADS)

    Montiel, F.; Squire, V. A.

    2013-12-01

    A new ocean wave/sea-ice interaction model is proposed that simulates how a directional wave spectrum evolves as it travels through a realistic marginal ice zone (MIZ), where wave/ice dynamics are entirely governed by coherent conservative wave scattering effects. Field experiments conducted by Wadhams et al. (1986) in the Greenland Sea generated important data on wave attenuation in the MIZ and, particularly, on whether the wave spectrum spreads directionally or collimates with distance from the ice edge. The data suggest that angular isotropy, arising from multiple scattering by ice floes, occurs close to the edge and thenceforth dominates wave propagation throughout the MIZ. Although several attempts have been made to replicate this finding theoretically, including by the use of numerical models, none have confronted this problem in a 3D MIZ with fully randomised floe distribution properties. We construct such a model by subdividing the discontinuous ice cover into adjacent infinite slabs of finite width parallel to the ice edge. Each slab contains an arbitrary (but finite) number of circular ice floes with randomly distributed properties. Ice floes are modeled as thin elastic plates with uniform thickness and finite draught. We consider a directional wave spectrum with harmonic time dependence incident on the MIZ from the open ocean, defined as a continuous superposition of plane waves traveling at different angles. The scattering problem within each slab is then solved using Graf's interaction theory for an arbitrary incident directional plane wave spectrum. Using an appropriate integral representation of the Hankel function of the first kind (see Cincotti et al., 1993), we map the outgoing circular wave field from each floe on the slab boundaries into a directional spectrum of plane waves, which characterizes the slab reflected and transmitted fields. Discretizing the angular spectrum, we can obtain a scattering matrix for each slab. Standard recursive

  10. Corrosion behavior in high heat input welded heat-affected zone of Ni-free high-nitrogen Fe–18Cr–10Mn–N austenitic stainless steel

    SciTech Connect

    Moon, Joonoh Ha, Heon-Young; Lee, Tae-Ho

    2013-08-15

    The pitting corrosion and interphase corrosion behaviors in high heat input welded heat-affected zone (HAZ) of a metastable high-nitrogen Fe–18Cr–10Mn–N austenitic stainless steel were explored through electrochemical tests. The HAZs were simulated using Gleeble simulator with high heat input welding condition of 300 kJ/cm and the peak temperature of the HAZs was changed from 1200 °C to 1350 °C, aiming to examine the effect of δ-ferrite formation on corrosion behavior. The electrochemical test results show that both pitting corrosion resistance and interphase corrosion resistance were seriously deteriorated by δ-ferrite formation in the HAZ and their aspects were different with increasing δ-ferrite fraction. The pitting corrosion resistance was decreased by the formation of Cr-depleted zone along δ-ferrite/austenite (γ) interphase resulting from δ-ferrite formation; however it didn't depend on δ-ferrite fraction. The interphase corrosion resistance depends on the total amount of Cr-depleted zone as well as ferrite area and thus continuously decreased with increasing δ-ferrite fraction. The different effects of δ-ferrite fraction on pitting corrosion and interphase corrosion were carefully discussed in terms of alloying elements partitioning in the HAZ based on thermodynamic consideration. - Highlights: • Corrosion behavior in the weld HAZ of high-nitrogen austenitic alloy was studied. • Cr{sub 2}N particle was not precipitated in high heat input welded HAZ of tested alloy. • Pitting corrosion and interphase corrosion show a different behavior. • Pitting corrosion resistance was affected by whether or not δ-ferrite forms. • Interphase corrosion resistance was affected by the total amount of δ-ferrite.

  11. Micromechanism of Decrease of Impact Toughness in Coarse-Grain Heat-Affected Zone of HSLA Steel with Increasing Welding Heat Input

    NASA Astrophysics Data System (ADS)

    Cao, R.; Li, J.; Liu, D. S.; Ma, J. Y.; Chen, J. H.

    2015-07-01

    This paper analyzes the micromechanism of decrease of impact toughness with increasing the welding heat input in coarse-grain heat-affected zone (CGHAZ) of a low-alloy high-strength ship-building steel plate. By comparing the microstructures, measuring the extending length of the fibrous crack, identifying the critical event of cleavage fracture, measuring the critical length, and calculating the local cleavage fracture stress σ f, and then using the basic principles of the micromechanism of cleavage fracture, this work reveals the essential causes of deteriorated toughness in the CGHAZ of high-strength steel welded joints.

  12. Creep deformation and rupture behavior of 2.25Cr-1Mo steel weldments and its constituents (base metal, weld metal and simulated heat affected zones)

    SciTech Connect

    Laha, K.; Chandravathi, K.S.; Rao, K.B.S.; Mannan, S.L.

    1995-12-31

    Microstructure across a weldment base metal through transformed heat-affected zone (HAZ) to cast weld metal. HAZ of 2.25Cr-1Mo weldment consists of coarse-grain bainite, fine-grain bainite and intercritical region. These HAZ microstructures were simulated by isothermal heat-treatments. Creep tests were carried out on base metal, weld metal, weldment and the simulated HAZ structures. Creep deformation and fracture behavior of 2.25Cr-1Mo weldments has been assessed based on the properties of its constituents. Coarse-grain bainite with low ductility and intercritical structure with low strength are the critical components of HAZ determining performance of the weldments.

  13. Study of Reservoir Heterogencities and Structural Features Affecting Production in the Shallow Oil Zone, Eastern Elk Hills Area, California

    SciTech Connect

    Janice Gillespie

    2004-11-01

    Late Neogene (Plio-Pleistocene) shallow marine strata of the western Bakersfield Arch and Elk Hills produce hydrocarbons from several different reservoirs. This project focuses on the shallow marine deposits of the Gusher and Calitroleum reservoirs in the Lower Shallow Oil Zone (LSOZ). In the eastern part of the study area on the Bakersfield Arch at North and South Coles Levee field and in two wells in easternmost Elk Hills, the LSOZ reservoirs produce dry (predominantly methane) gas. In structurally higher locations in western Elk Hills, the LSOZ produces oil and associated gas. Gas analyses show that gas from the eastern LSOZ is bacterial and formed in place in the reservoirs, whereas gas associated with oil in the western part of the study area is thermogenic and migrated into the sands from deeper in the basin. Regional mapping shows that the gas-bearing LSOZ sands in the Coles Levee and easternmost Elk Hills area are sourced from the Sierra Nevada to the east whereas the oil-bearing sands in western Elk Hills appear to be sourced from the west. The eastern Elk Hills area occupied the basin depocenter, farthest from either source area. As a result, it collected mainly low-permeability offshore shale deposits. This sand-poor depocenter provides an effective barrier to the updip migration of gases from east to west. The role of small, listric normal faults as migration barriers is more ambiguous. Because our gas analyses show that the gas in the eastern LSOZ reservoirs is bacterial, it likely formed in-place near the reservoirs and did not have to migrate far. Therefore, the gas could have been generated after faulting and accumulated within the fault blocks as localized pools. However, bacterial gas is present in both the eastern AND western parts of Elk Hills in the Dry Gas Zone (DGZ) near the top of the stratigraphic section even though the measured fault displacement is greatest in this zone. Bacterial gas is not present in the west in the deeper LSOZ which

  14. Size-fraction partitioning of community gene transcription and nitrogen metabolism in a marine oxygen minimum zone.

    PubMed

    Ganesh, Sangita; Bristow, Laura A; Larsen, Morten; Sarode, Neha; Thamdrup, Bo; Stewart, Frank J

    2015-12-01

    The genetic composition of marine microbial communities varies at the microscale between particle-associated (PA; >1.6 μm) and free-living (FL; 0.2-1.6 μm) niches. It remains unclear, however, how metabolic activities differ between PA and FL fractions. We combined rate measurements with metatranscriptomics to quantify PA and FL microbial activity in the oxygen minimum zone (OMZ) of the Eastern Tropical North Pacific, focusing on dissimilatory processes of the nitrogen (N) cycle. Bacterial gene counts were 8- to 15-fold higher in the FL compared with the PA fraction. However, rates of all measured N cycle processes, excluding ammonia oxidation, declined significantly following particle (>1.6 μm) removal. Without particles, rates of nitrate reduction to nitrite (1.5-9.4nMNd(-1)) fell to zero and N2 production by denitrification (0.5-1.7nMNd(-1)) and anammox (0.3-1.9nMNd(-1)) declined by 53-85%. The proportional representation of major microbial taxa and N cycle gene transcripts in metatranscriptomes followed fraction-specific trends. Transcripts encoding nitrate reductase were uniform among PA and FL fractions, whereas anammox-associated transcripts were proportionately enriched up to 15-fold in the FL fraction. In contrast, transcripts encoding enzymes for N2O and N2 production by denitrification were enriched up to 28-fold in PA samples. These patterns suggest that the majority of N cycle activity, excluding N2O and N2 production by denitrification, is confined to a FL majority that is critically dependent on access to particles, likely as a source of organic carbon and inorganic N. Variable particle distributions may drive heterogeneity in N cycle activity and gene expression in OMZs. PMID:25848875

  15. Distribution of polychlorinated biphenyls in an urban riparian zone affected by wastewater treatment plant effluent and the transfer to terrestrial compartment by invertebrates.

    PubMed

    Yu, Junchao; Wang, Thanh; Han, Shanlong; Wang, Pu; Zhang, Qinghua; Jiang, Guibin

    2013-10-01

    In this study, we investigated the distribution of polychlorinated biphenyls (PCBs) in a riparian zone affected by the effluent from a wastewater treatment plant (WWTP). River water, sediment, aquatic invertebrates and samples from the surrounding terrestrial compartment such as soil, reed plants and several land based invertebrates were collected. A relatively narrow range of δ(13)C values was found among most invertebrates (except butterflies, grasshoppers), indicating a similar energy source. The highest concentration of total PCBs was observed in zooplankton (151.1 ng/g lipid weight), and soil dwelling invertebrates showed higher concentrations than phytophagous insects at the riparian zone. The endobenthic oligochaete Tubifex tubifex (54.28 ng/g lw) might be a useful bioindicator of WWTP derived PCBs contamination. High bioaccumulation factors (BAFs) were observed in collected aquatic invertebrates, although the biota-sediment/soil accumulation factors (BSAF) remained relatively low. Emerging aquatic insects such as chironomids could carry waterborne PCBs to the terrestrial compartment via their lifecycles. The estimated annual flux of PCBs for chironomids ranged from 0.66 to 265 ng⋅m(-2)⋅y(-1). Although a high prevalence of PCB-11 and PCB-28 was found for most aquatic based samples in this riparian zone, the mid-chlorinated congeners (e.g. PCB-153 and PCB-138) became predominant among chironomids and dragonflies as well as soil dwelling invertebrates, which might suggest a selective biodriven transfer of different PCB congeners. PMID:23811358

  16. Root zone temperature affects the phytoextraction of Ba, Cl, Sn, Pt, and Rb using potato plants (Solanum tuberosum L. var. Spunta) in the field.

    PubMed

    Baghour, M; Moreno, D A; Víllora, G; Hernández, J; Castilla, N; Romero, L

    2002-01-01

    Three consecutive years of field experiments were conducted to investigate how different root-zone temperatures, manipulated by using different mulches, affect the phytoextraction of Ba, Cl, Sn, Pt and Rb in different organs of potato plants (roots, tubers, stems and leaves). Four different plastic covers were used (T1: transparent polyethylene; T2: white polyethylene; T3: white and black coextruded polyethylene, and T4: black polyethylene), using uncovered plants as control (T0). The different treatments had a significant effect on mean root zone temperatures (T0 = 16 degrees C, T1 = 20 degrees C, T2 = 23 degrees C, T3 = 27 degrees C and T4 = 30 degrees C) and induced a significantly different response in Ba, Cl, Sn, Pt and Rb concentration and accumulation. The T3 treatment gave rise to the greatest phytoextraction of Ba, Pt, Cl and Sn in the roots, leaflets and tubers. In terms of the relative distribution of the phytoaccumulated elements (as percentage of the total within the plant), Pt and Ba accumulated mainly in the roots whereas Rb, Sn and Cl accumulated primarily in tubers, establishing a close relationship between the biomass development of each organ and phytoaccumulation capacity of metals in response to temperature in the root zone. PMID:11846271

  17. Cleavage Fracture Initiation at M-A Constituents in Intercritically Coarse-Grained Heat-Affected Zone of a HSLA Steel

    NASA Astrophysics Data System (ADS)

    Mohseni, Peyman; Solberg, Jan Ketil; Karlsen, Morten; Akselsen, Odd Magne; Østby, Erling

    2014-01-01

    Local brittle zones, i.e., martensite-austenite (M-A) islands, are formed within the coarse-grained heat-affected zone (CGHAZ) and the intercritically reheated CGHAZ (ICCGHAZ) during welding of many HSLA steels. In the current study, the M-A constituents in the microstructure of simulated ICCGHAZ of an API X80 pipeline steel were investigated using transmission electron microscopy and scanning electron microscopy. The focused ion beam technique was applied to make TEM specimens of M-A constituents that were located in the initiation sites of cleavage cracks. The main purpose of the study was to identify crack-initiation sites of cleavage fracture in ICCGHAZ and to prove the presence of M-A constituents in such initiation sites. Twinned martensite was detected in all local brittle zones that were investigated in the current study, demonstrating that they are M-A constituents. It was also demonstrated that the fracture initiation occurred preferentially at M-A constituents by a debonding mechanism rather than cracking of the M-A constituents.

  18. Turbulence control of floc size in suspended particulate matter (SPM) in the river estuary transition zone (RETZ)

    NASA Astrophysics Data System (ADS)

    Jackson, Suzanna; Jago, Colin

    2016-04-01

    Quantifying floc properties in relation to physical forcings are key in determining the transfer flux of SPM from the catchment to the coastal ocean. Observations of floc development require high resolution data; in situ optical and acoustic instruments were deployed in the RETZ to obtain SPM and hydrodynamic properties. Results suggest that turbulent kinetic energy dissipation (TKE) can be correlated to median particle size (D50) and concentration on tidal and lunar time scales. Analysis on a tidal scale indicates terrestrially derived SPM and SPM of a marine origin display different relationships with the local turbulence regime, suggesting the D50 of terrestrially derived SPM is not limited to the eddy length scales of the Kolmogorov microscale. It is essential to improve methods to quantify the role of hydrodynamic processes in controlling SPM properties and thus the fate of the transfer of terrestrially derived organic matter to the coastal ocean.

  19. Population sizes and growth pressure responses of intestinal microfloras of deep-sea fish retrieved from the abyssal zone.

    PubMed

    Yano, Y; Nakayama, A; Yoshida, K

    1995-12-01

    The intestinal floras of seven deep-sea fish retrieved at depths of from 3,200 to 5,900 m were examined for population sizes and growth responses to pressure. Large populations of culturable bacteria, ranging from 1.1 x 10(sup6) to 3.6 x 10(sup8) cells per ml of contents, were detected when samples were incubated at conditions characteristic of those of the deep sea. Culturable cell counts at in situ pressures were greater than those at atmospheric pressure in all samples. Most of the strains isolated by the spread-plating method at atmospheric pressure later proved barophilic. Barophilic bacteria were the predominant inhabitants of the abyssal fish intestines. PMID:16535199

  20. Surface Features Analysis in Salt-Affected Area Using Hyperspectral Data: A Case Study in the Zone of Chotts, Tunisia

    NASA Astrophysics Data System (ADS)

    Bouaziz, Moncef; Liesenberg, Veraldo; Bouaziz, Samir; Gloaguen, Richard

    2010-12-01

    Arid and semi-arid regions are most affected by Salinity. Chotts regions in southern Tunisia are such an area, where the excessive content of salt in the soil is a hard faced problem. Soil salinity in this area enforces several environmental problems such as limiting plant growth, reducing crop productivity, degrading soil quality and leads to accelerated rates rill and gully erosion . Remote sensing analysis by the mean of spectral analysis, geomorphologic aspect from digital elevation models and distribution of rainfall intensity from satellite data are used in this study to discern features and patterns of areas affected by salt. Correlation between these remote sensing indicators is made in order to assess the contribution of each indicator to identify the salt-affected area. The approach followed in this study was applied on Hyperspectral data from EO-1 Mission. Hyperion data are promoted due to their very high spectral resolution and wide enhanced spatial information. The present study highlighted the high correlation between the flat surfaces and the high content of salt in the soil (from soil salinity indices) on one hand and a low correlation between the high intensity of rainfall distribution and indicators of low salt content in the soil on the other hand.

  1. Potential health risk for residents around a typical e-waste recycling zone via inhalation of size-fractionated particle-bound heavy metals.

    PubMed

    Huang, Chun-Li; Bao, Lian-Jun; Luo, Pei; Wang, Zhao-Yi; Li, Shao-Meng; Zeng, Eddy Y

    2016-11-01

    Health risk of residents dwelling around e-waste recycling zones has been a global concern, but has not been adequately examined. The present study was intended to evaluate the potential health risk of residents through inhalation exposure to size-fractionated particle-bound heavy metals in a typical e-waste recycling zone, South China. Anthropogenic metals (Zn, Se, Pb, Sb, As, and Cd) were predominantly enriched in fine particles (Dp<1.8μm), whereas the crustal elements (Ti, Fe, and Co) tended to accumulate in coarse particles (Dp>1.8μm). Although the daily inhalation intakes of the target metals were significantly lower than those through food consumption and ingestion of house dust, the hazard quotients of total metals for adults (95% CI: 1.0-5.5) and children (95% CI: 3.0-17) were greater than 1. Moreover, the incremental lifetime cancer risks of five carcinogenic metals (Cr, Co, Ni, As, and Cd) for adults and children were 1.3×10(-3) (95% CI: 4.1×10(-4)-3.0×10(-3)) and 3.9×10(-3) (95% CI: 1.3×10(-3)-8.6×10(-3)), respectively, substantially higher than the acceptable cancer risk range of 10(-6)-10(-4). All these findings suggested that health risks were high for local residents dwelling around the e-waste recycling zone through inhalation exposure to particle-bound heavy metals, for both adults and children. PMID:27322902

  2. PLANET HUNTERS. V. A CONFIRMED JUPITER-SIZE PLANET IN THE HABITABLE ZONE AND 42 PLANET CANDIDATES FROM THE KEPLER ARCHIVE DATA

    SciTech Connect

    Wang, Ji; Fischer, Debra A.; Boyajian, Tabetha S.; Schmitt, Joseph R.; Giguere, Matthew J.; Brewer, John M.; Barclay, Thomas; Schwamb, Megan E.; Lintott, Chris; Simpson, Robert; Jek, Kian J.; Hoekstra, Abe J.; Jacobs, Thomas Lee; LaCourse, Daryll; Schwengeler, Hans Martin; Smith, Arfon M.; Parrish, Michael; Lynn, Stuart; Schawinski, Kevin; and others

    2013-10-10

    We report the latest Planet Hunter results, including PH2 b, a Jupiter-size (R{sub PL} = 10.12 ± 0.56 R{sub ⊕}) planet orbiting in the habitable zone of a solar-type star. PH2 b was elevated from candidate status when a series of false-positive tests yielded a 99.9% confidence level that transit events detected around the star KIC 12735740 had a planetary origin. Planet Hunter volunteers have also discovered 42 new planet candidates in the Kepler public archive data, of which 33 have at least 3 transits recorded. Most of these transit candidates have orbital periods longer than 100 days and 20 are potentially located in the habitable zones of their host stars. Nine candidates were detected with only two transit events and the prospective periods are longer than 400 days. The photometric models suggest that these objects have radii that range between those of Neptune and Jupiter. These detections nearly double the number of gas-giant planet candidates orbiting at habitable-zone distances. We conducted spectroscopic observations for nine of the brighter targets to improve the stellar parameters and we obtained adaptive optics imaging for four of the stars to search for blended background or foreground stars that could confuse our photometric modeling. We present an iterative analysis method to derive the stellar and planet properties and uncertainties by combining the available spectroscopic parameters, stellar evolution models, and transiting light curve parameters, weighted by the measurement errors. Planet Hunters is a citizen science project that crowd sources the assessment of NASA Kepler light curves. The discovery of these 43 planet candidates demonstrates the success of citizen scientists at identifying planet candidates, even in longer period orbits with only two or three transit events.

  3. Natural Radiation for Identification and Evaluation of Risk Zones for Affectation of Activated Faults in Aquifer Overexploited.

    NASA Astrophysics Data System (ADS)

    Ramos-Leal, J.; Lopez-Loera, H.; Carbajal-Perez, N.

    2007-05-01

    In basins as Mexico, Michoacán, Guanajuato, Queretaro, Aguascalientes and San Luis Potosi, the existence of faults and fractures have affected the urban infrastructure, lines of conduction of drinkable water, pipelines, etc., that when not being identified and considered, they don't reflect the real impact that these cause also to the aquifer system, modifying the permeability of the means and in occasions they work as preferential conduits that communicate hydraulically potentially to the aquifer with substances pollutants (metals, fertilizers, hydrocarbons, waste waters, etc.) located in the surface. In the Valley of San Luis Potosi, Villa of Reyes, Arista, Ahualulco and recently The Huizache-Matehuala is being strongly affected by faulting and supposedly due cracking to subsidence, however, the regional tectonic could also be the origin of this phenomenon. To know the origin of the faults and affectation to the vulnerability of the aquifer few works they have been carried out in the area. A preliminary analysis indicates that it is possible that a tectonic component is affecting the area and that the vulnerability of the aquifer in that area you this increasing. Before such a situation, it is necessary to carry out the isotopic study of the same one, for this way to know among other things, isotopic characterization, recharge places and addresses of flow of the groundwater; quality of waters and the behavior hydrochemistry with relationship to the faults. High radon values were measured in San Luis Potosi Valley, the natural source of radon could be the riolites and however, these are located to almost a once thousand meters deep for what the migration of the gas is not very probable. The anomalies radiometrics was not correlation with the faults in this case. In some areas like the Valley of Celaya, the origin of the structures and the tectonic activity in the area was confirmed, identifying the structural arrangement of the faulting, the space relationships

  4. Why person affected by leprosy did not look after their plantar ulcer? Experience from Pakokku zone, Myanmar.

    PubMed

    Win, Le Le; Shwe, San; Maw, Win; Ishida, Yutaka; Myint, Kyaw; Mar, Kyi Kyi; Min, Thandar; Oo, Phyo Min; Khine, Aye Win

    2010-09-01

    A cross-sectional study was carried out to identify methods of caring plantar ulcers in leprosy patients and the underlying causes of poor plantar ulcer care during January and February 2008. This was conducted in Pakokku zone as it was one of the "9 selected townships of the Disabilities survey, i.e., Basic Health Staff project 2003/4", which was funded by Japan International Cooperation Agency. After getting consent, all available leprosy cases, i.e., 101 cases with foot disability grade 2 were interviewed with the pre-tested questionnaire. Among 101 cases, 13 cases who took care of their ulcer poorly and 20 who did none of the recommended measures were recruited for in-depth interview (IDI). The subjects were largely old people, males and people with no marriage partner. The majority had earned money by doing sedentary job. Prolongation of ulcers was observed in 78 cases. Most had been suffering from ulcers for years. When asking face-to-face interview, all the recommended care measures were not reported. Among these recommended measures, a large number of respondents reported about soaking measure. However, these reported measures were contradicted to the preventive methods which they disclosed in IDI. Plantar ulcer care seemed to be an individualised practice. The individual ways of performing were related to their view of ulcer, the environment, and occupation, and custom, communication with family and health staff. The findings identified the actual practice of plantar ulcer care in study areas. It is suggested that the current performance of planar ulcer care is inadequate and more attention should be given to achieve the target set by the programme as a recommendation. PMID:20857653

  5. Differences in Water Vapor Radiative Transfer among 1D Models Can Significantly Affect the Inner Edge of the Habitable Zone

    NASA Astrophysics Data System (ADS)

    Yang, Jun; Leconte, Jérémy; Wolf, Eric T.; Goldblatt, Colin; Feldl, Nicole; Merlis, Timothy; Wang, Yuwei; Koll, Daniel D. B.; Ding, Feng; Forget, François; Abbot, Dorian S.

    2016-08-01

    An accurate estimate of the inner edge of the habitable zone is critical for determining which exoplanets are potentially habitable and for designing future telescopes to observe them. Here, we explore differences in estimating the inner edge among seven one-dimensional radiative transfer models: two line-by-line codes (SMART and LBLRTM) as well as five band codes (CAM3, CAM4_Wolf, LMDG, SBDART, and AM2) that are currently being used in global climate models. We compare radiative fluxes and spectra in clear-sky conditions around G and M stars, with fixed moist adiabatic profiles for surface temperatures from 250 to 360 K. We find that divergences among the models arise mainly from large uncertainties in water vapor absorption in the window region (10 μm) and in the region between 0.2 and 1.5 μm. Differences in outgoing longwave radiation increase with surface temperature and reach 10–20 W m‑2 differences in shortwave reach up to 60 W m‑2, especially at the surface and in the troposphere, and are larger for an M-dwarf spectrum than a solar spectrum. Differences between the two line-by-line models are significant, although smaller than among the band models. Our results imply that the uncertainty in estimating the insolation threshold of the inner edge (the runaway greenhouse limit) due only to clear-sky radiative transfer is ≈10% of modern Earth’s solar constant (i.e., ≈34 W m‑2 in global mean) among band models and ≈3% between the two line-by-line models. These comparisons show that future work is needed that focuses on improving water vapor absorption coefficients in both shortwave and longwave, as well as on increasing the resolution of stellar spectra in broadband models.

  6. Nutrient demand interacts with legume particle length to affect digestion responses and rumen pool sizes in dairy cows.

    PubMed

    Kammes, K L; Ying, Y; Allen, M S

    2012-05-01

    Effects of legume particle length on dry matter intake (DMI), milk production, ruminal fermentation and pool sizes, and digestion and passage kinetics, and the relationship of these effects with preliminary DMI (pDMI) were evaluated using 13 ruminally and duodenally cannulated Holstein cows in a crossover design with a 14-d preliminary period and two 19-d treatment periods. During the preliminary period, pDMI of individual cows ranged from 22.8 to 32.4 kg/d (mean=26.5 kg/d) and 3.5% fat-corrected milk yield ranged from 22.9 to 62.4 kg/d (mean=35.1 kg/d). Experimental treatments were diets containing alfalfa silage chopped to (1) 19 mm (long cut, LC) or (2) 10 mm (short cut, SC) theoretical length of cut as the sole forage. Alfalfa silages contained approximately 43% neutral detergent fiber (NDF); diets contained approximately 47% forage and 20% forage NDF. Preliminary DMI, an index of nutrient demand, was determined during the last 4 d of the preliminary period, when cows were fed a common diet, and used as a covariate. Main effects of legume particle length and their interaction with pDMI were tested by ANOVA. Alfalfa particle length and its interaction with pDMI did not affect milk yield or rumen pH. The LC diet decreased milk fat concentration more per kilogram of pDMI increase than the SC diet and increased yields of milk fat and fat-corrected milk less per kilogram of pDMI increase than the SC diet, resulting in a greater benefit for LC at low pDMI and for SC at high pDMI. The LC diet tended to decrease DMI compared with the SC diet. Ruminal digestion and passage rates of feed fractions did not differ between LC and SC and were not related to level of intake. The LC diet tended to decrease the rate of ruminal turnover for NDF but increased NDF rumen pools at a slower rate than the SC diet as pDMI increased. This indicated that the faster NDF turnover rate did not counterbalance the higher DMI for SC, resulting in larger NDF rumen pools for SC than LC. As p

  7. Brittle grain-size reduction of feldspar, phase mixing and strain localization in granitoids at mid-crustal conditions (Pernambuco shear zone, NE Brazil)

    NASA Astrophysics Data System (ADS)

    Viegas, Gustavo; Menegon, Luca; Archanjo, Carlos

    2016-03-01

    The Pernambuco shear zone (northeastern Brazil) is a large-scale strike-slip fault that, in its eastern segment, deforms granitoids at mid-crustal conditions. Initially coarse-grained (> 50 µm) feldspar porphyroclasts are intensively fractured and reduced to an ultrafine-grained mixture consisting of plagioclase and K-feldspar grains (< 15 µm) localized in C' shear bands. Detailed microstructural observations and electron backscatter diffraction (EBSD) analysis do not show evidence of intracrystalline plasticity in feldspar porphyroclasts and/or fluid-assisted replacement reactions. Quartz occurs either as thick (˜ 1-2 mm) monomineralic veins transposed along the shear zone foliation or as thin ribbons ( ≤ 25 µm width) dispersed in the feldspathic mixture. The microstructure and c axis crystallographic-preferred orientation are similar in the thick monomineralic veins and in the thin ribbons, and they suggest dominant subgrain rotation recrystallization and activity of prism < a > and rhomb < a > slip systems. However, the grain size in monophase recrystallized domains decreases when moving from the quartz monomineralic veins to the thin ribbons embedded in the feldspathic C' bands (14 µm vs. 5 µm respectively). The fine-grained feldspar mixture has a weak crystallographic-preferred orientation interpreted as the result of shear zone parallel-oriented growth during diffusion creep, as well as the same composition as the fractured porphyroclasts, suggesting that it generated by mechanical fragmentation of rigid porphyroclasts with a negligible role of chemical disequilibrium. Once C' shear bands were generated and underwent viscous deformation at constant stress conditions, the polyphase feldspathic aggregate would have deformed at a strain rate 1 order of magnitude faster than the monophase quartz monomineralic veins, as evidenced by applying experimentally and theoretically calibrated flow laws for dislocation creep in quartz and diffusion creep in

  8. How do changes in the Diurnal Cycle affect Bi-stability and Climate Sensitivity in the Habitable Zone?

    NASA Astrophysics Data System (ADS)

    Boschi, R.; Valerio, L.

    2013-09-01

    fundamental properties of planets in the habitable zone from relatively simple observables.

  9. Pore size distribution of soil near saturation as affected by soil type, land use, and soil amendments

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Storage and flow of water in soil voids, which are related to the size and geometry of the voids and flow rate are usually controlled by the void of the smallest size. Another reason for the complexity of water flow in soils is the intricate nature and change of the soil pores due to the modificatio...

  10. Physicochemical characteristics of the hyporheic zone affect redd site selection of chum salmon and fall chinook salmon in the Columbia River

    SciTech Connect

    Geist, David R. ); Hanrahan, Timothy P. ); Arntzen, Evan V. ); McMichael, Geoffrey A. ); Murray, Christopher J. ); Chien, Yi-Ju )

    2002-11-01

    Chum salmon Oncorhynchus keta and fall chinook salmon O. tshawytscha spawned at different locations in the vicinity of Ives Island, Washington, a side channel to the Columbia River downstream of Bonneville Dam. We hypothesized that measurements of water depth, substrate size, and water velocity alone would not explain the separation in spawning areas and began a 2-year investigation of physicochemical characteristics of the hyporheic zone. We found that chum salmon spawned in upwelling water that was significantly warmer than the surrounding river water. In contrast, fall chinook salmon constructed redds at downwelling sites where there was no difference in temperature between the river and its bed. Understanding the specific features that are important for chum salmon and fall chinook salmon redd site selection at Ives Island will be useful to resource managers attempting to maximize available spawning habitat for these species within the constraints imposed by other water resource needs.

  11. Injection of colloidal size particles of Fe{sup 0} in porous media with shearthinning fluids as a method to emplace a permeable reactive zone

    SciTech Connect

    Cantrell, K.J.; Kaplan, D.I.; Gilmore, T.J.

    1997-12-31

    Previous work has demonstrated the feasibility of injecting suspensions of micron-size zero-valent (FeO) particles into porous media as a method to emplace a permeable reactive zone. Further studies were conducted to evaluate the effects of several shearthinning fluids on enhancing the injectability of micron-size FeO particles into porous media. In contrast to Newtonian fluids, whose viscosities are constant with shear rate, certain non-Newtonian fluids are shearthinning, that is, the viscosity of these fluids decreases with increasing shear rate. The primary benefit of using these fluids for this application is that they increase the viscosity of the aqueous phase without adversely decreasing the hydraulic conductivity. A suspension formulated with a shearthinning fluid will maintain a relatively high viscosity in solution near the FeO particles (where the shear stress is low) relative to locations near the surfaces of the porous media, where the shear stress is high. The increased viscosity decreases the rate of gravitational settling of the dense FeO colloids (7.6 9/cm3) while maintaining a relatively high hydraulic conductivity that permits pumping the colloid suspensions into porous media at greater flowrates and distances. Aqueous solutions of three polymers at different concentrations were investigated. It was determined that, the use of shear thinning fluids greatly increases the injectability of the colloidal FeO suspensions in porous media.

  12. Design requirements for ERD in diffusion-dominated media: how do injection interval, bioactive zones and reaction kinetics affect remediation performance?

    NASA Astrophysics Data System (ADS)

    Chambon, J.; Lemming, G.; Manoli, G.; Broholm, M. M.; Bjerg, P.; Binning, P. J.

    2011-12-01

    Enhanced Reductive Dechlorination (ERD) has been successfully used in high permeability media, such as sand aquifers, and is considered to be a promising technology for low permeability settings. Pilot and full-scale applications of ERD at several sites in Denmark have shown that the main challenge is to get contact between the injected bacteria and electron donor and the contaminants trapped in the low-permeability matrix. Sampling of intact cores from the low-permeability matrix has shown that the bioactive zones (where degradation occurs) are limited in the matrix, due to the slow diffusion transport processes, and this affects the timeframes for the remediation. Due to the limited ERD applications and the complex transport and reactive processes occurring in low-permeability media, design guidelines are currently not available for ERD in such settings, and remediation performance assessments are limited. The objective of this study is to combine existing knowledge from several sites with numerical modeling to assess the effect of the injection interval, development of bioactive zones and reaction kinetics on the remediation efficiency for ERD in diffusion-dominated media. A numerical model is developed to simulate ERD at a contaminated site, where the source area (mainly TCE) is located in a clayey till with fractures and interbedded sand lenses. Such contaminated sites are common in North America and Europe. Hydro-geological characterization provided information on geological heterogeneities and hydraulic parameters, which are relevant for clay till sites in general. The numerical model couples flow and transport in the fracture network and low-permeability matrix. Sequential degradation of TCE to ethene is modeled using Monod kinetics, and the kinetic parameters are obtained from laboratory experiments. The influence of the reaction kinetics on remediation efficiency is assessed by varying the biomass concentration of the specific degraders. The injected

  13. Physicochemical Characteristics of the Hyporheic Zone Affect Redd Site Selection of Chum and Fall Chinook Salmon, Columbia River.

    SciTech Connect

    Geist, David R.

    2001-10-01

    Chum salmon (Oncorhynchus keta) may historically have been the most abundant species of Columbia River salmon, contributing as much as 50% of the total biomass of all salmon in the Pacific Ocean prior to the 1940's (Neave 1961). By the 1950's, however, run sizes to the Columbia River dropped dramatically and in 1999 the National Marine Fisheries Service (NMFS) listed Columbia River chum salmon as threatened under the Endangered Species Act (ESA; NMFS 1999). Habitat degradation, water diversions, harvest, and artificial propagation are the major human-induced factors that have contributed to the species decline (NMFS 1998). Columbia River chum salmon spawn exclusively in the lower river below Bonneville Dam, including an area near Ives Island. The Ives Island chum salmon are part of the Columbia River evolutionary significant unit (ESU) for this species, and are included in the ESA listing. In addition to chum salmon, fall chinook salmon (O. tshawytscha) also spawn at Ives Island. Spawning surveys conducted at Ives Island over the last several years show that chum and fall chinook salmon spawned in clusters in different locations (US Fish and Wildlife Service and Washington Department of Fish and Wildlife, unpublished data). The presence of redd clusters suggested that fish were selecting specific habitat features within the study area (Geist and Dauble 1998). Understanding the specific features of these spawning areas is needed to quantify the amount of habitat available to each species so that minimum flows can be set to protect fish and maintain high quality habitat.

  14. Effects of welding and weld heat-affected zone simulation on the microstructure and mechanical behavior of a 2195 aluminum-lithium alloy

    NASA Astrophysics Data System (ADS)

    Chen, D. L.; Chaturvedi, M. C.

    2001-11-01

    The microstructures, tensile properties, and fatigue properties of a 2195-T8 Al-Li alloy subjected to a weld heat-affected zone (HAZ) simulation and gas-tungsten-arc (GTA) welding using a 4043 filler metal, with and without a postweld heat treatment, were studied. The principal strengthening precipitate in the T8 base alloy was the T 1 (Al2CuLi) phase. The HAZ simulation resulted in the dissolution of T 1 precipitates and the formation of T B(Al7Cu4Li) phase, Guinier-Preston (G-P) zones, and δ' (Al3Li) particles. When the HAZ simulation was conducted at the highest temperature of 600 °C, microcracks and voids also formed along the grain boundaries (GBs). In the specimens welded with the 4043 alloy, T (AlLiSi) phase was found to form in the fusion zone (FZ). An elongated T Bphase and microcracks were observed to occur along the GBs in the HAZ close to the FZ interface. The T 1 phase was not observed in the HAZ. The postweld heat treatment resulted in the spheroidization of primary T phase and the precipitation of small secondary T particles in the FZ, the dissolution of T B phase, and the reprecipitation of the T 1 phase in the HAZ. Both the HAZ simulation and welding gave rise to a considerable decrease in the hardness, tensile properties, and fatigue strength. The hardness in the FZ was lower than that in the HAZ. Although the postweld heat treatment improved both the hardness and tensile properties due to the reprecipitation of T 1 phase in the HAZ and a smaller interparticle spacing in the FZ, no increase in the fatigue strength was observed because of the presence of microcracks in the HAZ.

  15. Brittle grain size reduction of feldspar, phase mixing and strain localization in granitoids at mid-crustal conditions (Pernambuco shear zone, NE Brazil)

    NASA Astrophysics Data System (ADS)

    Viegas, Gustavo; Menegon, Luca; Archanjo, Carlos

    2016-04-01

    The Pernambuco shear zone (northeastern Brazil) is a large-scale strike-slip fault that, in its eastern segment, deforms granitoids at mid-crustal conditions. Initially coarse (> 50 μm) grained feldspar porphyroclasts are intensively fractured and reduced to an ultrafine-grained mixture consisting of plagioclase and K-feldspar grains (< 15 μm in size) localized in C' shear bands. Detailed microstructural observations and EBSD analysis do not show evidence of intracrystalline plasticity in feldspar porphyroclasts and/or fluid-assisted replacement reactions. Quartz occurs either as thick (˜ 1-2 mm) monomineralic bands or as thin ribbons dispersed in the feldspathic mixture. The microstructure and c-axis crystallographic preferred orientation are similar in the thick monomineralic band and in the thin ribbons, and suggest dominant subgrain rotation recrystallization and activity of prism and rhomb slip systems. However, the grain size in monophase recrystallized domains decreases when moving from the monomineralic veins to the thin ribbons embedded in the feldspathic C' bands (14 μm vs 5 μm, respectively).The fine-grained feldspar mixture has a weak crystallographic preferred orientation interpreted as the result of oriented growth during diffusion creep, as well as the same composition as the fractured porphyroclasts, suggesting that it generated by mechanical fragmentation of rigid porphyroclasts with a negligible role of chemical disequilibrium. Assuming that the C' shear bands deformed under constant stress conditions, the polyphase feldspathic aggregate would have deformed at a strain rate one order of magnitude faster than the monophase quartz ribbons. Overall, our dataset indicates that feldspar underwent a brittle-viscous transition while quartz was deforming via crystalline plasticity. The resulting rock microstructure consists of a two-phase rheological mixture (fine-grained feldspars and recrystallized quartz) in which the feldspathic material

  16. Factors Affecting Utilization of Maternal Health Care Services in Kombolcha District, Eastern Hararghe Zone, Oromia Regional State, Eastern Ethiopia

    PubMed Central

    Belayihun, Bekele; Teji, Kedir; Admassu Ayana, Desalegn

    2014-01-01

    Introduction. World health organization estimates that more than half a million women lose their lives in the process of reproduction worldwide every year and most of these mortalities are avoidable if mothers have access to maternal health care services. Objectives. This study was conducted with objectives of determining the prevalence of utilization of maternal health care services and identifying factors affecting it. Methodology. A community based cross-sectional survey was conducted in six kebeles of Kombolcha district. A total of 495 women of reproductive age participated in the study and their selection was made using simple random sampling technique and data was collected using an interviewer-administered structured questionnaire. The data was analyzed using SPSS version 16. Results. A total of 495 women were included in this study and from these women about 86.1% had at least one ANC visit during their last pregnancy. About 61.7% of mothers had less than four visits which is less than the recommended and 46.2% started it in the second trimester. Only 25.3% of respondents gave birth in health institutions and rural women were less likely to use institutional delivery 20.9% compared to urban women 35.9%. Recommendations. More efforts should be given to educate society in general and mothers in particular, to strengthen community participation and to increase the accessibility of maternal health care services. Moreover, providing accurate information about the services provided in the health institutions is required from the concerned governmental and nongovernmental organizations.

  17. THE SIZE AND SURFACE COATING OF NANOSILVER DIFFERENTIALLY AFFECTS BIOLOGICAL ACTIVITY IN BLOOD BRAIN BARRIER (RBEC4) CELLS.

    EPA Science Inventory

    Linking the physical properties of nanoparticles with differences in their biological activity is critical for understanding their potential toxicity and mode of action. The influence of aggregate size, surface coating, and surface charge on nanosilver's (nanoAg) movement through...

  18. 78 FR 51746 - Trade Barriers That U.S. Small and Medium-sized Enterprises Perceive as Affecting Exports to the...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-08-21

    ... European Union; Scheduling of an Additional Public Hearing With Simplified Filing Procedures AGENCY: United... Barriers that U.S. Small and Medium-sized Enterprises Perceive as Affecting Exports to the European Union... and Investment Partnership (TTIP) negotiations with the European Union (EU), is seeking to...

  19. THE ESTROGENIC AND ANTIANDROGENIC PESTICIDE METHOXYCHLOR ALTERS THE REPRODUCTIVE TRACT AND BEHAVIOR WITHOUT AFFECTING PITUITARY SIZE OR LH AND PROLACTIN SECRETION IN MALE RATS

    EPA Science Inventory

    The estrogenic and antiandrogenic pesticide methoxychlor alters the reproductive tract and behavior without affecting pituitary size or LH and prolactin secretion in male rats.

    Gray LE Jr, Ostby J, Cooper RL, Kelce WR.

    Endocrinology Branch, United States Environment...

  20. Growth of salmonellae on sprouting alfalfa seeds as affected by the inoculum size, native microbial load, and Pseudomonas fluorescens 2-79

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The incidence of human illness associated with the consumption of fresh sprouts has increased very sharply during the past decade. The objective of this study was to investigate the growth dynamics of salmonellae on sprouting alfalfa seeds as affected by the inoculum size, native microbial load, an...

  1. A process model for the heat-affected zone microstructure evolution in duplex stainless steel weldments: Part II. Application to electron beam welding

    NASA Astrophysics Data System (ADS)

    Hemmer, H.; Grong, Ø.; Klokkehaug, S.

    2000-03-01

    In the present investigation, a process model for electron beam (EB) welding of different grades of duplex stainless steels (i.e. SAF 2205 and 2507) has been developed. A number of attractive features are built into the original finite element code, including (1) a separate module for prediction of the penetration depth and distribution of the heat source into the plate, (2) adaptive refinement of the three-dimensional (3-D) element mesh for quick and reliable solution of the differential heat flow equation, and (3) special subroutines for calculation of the heat-affected zone (HAZ) microstructure evolution. The process model has been validated by comparison with experimental data obtained from in situ thermocouple measurements and optical microscope examinations. Subsequently, its aptness to alloy design and optimization of welding conditions for duplex stainless steels is illustrated in different numerical examples and case studies pertaining to EB welding of tubular joints.

  2. Mechanisms and modeling of cleavage fracture in simulated heat-affected zone microstructures of a high-strength low alloy steel

    NASA Astrophysics Data System (ADS)

    Lambert-Perlade, A.; Sturel, T.; Gourgues, A. F.; Besson, J.; Pineau, A.

    2004-03-01

    The effect of the welding cycle on the fracture toughness properties of high-strength low alloy (HSLA) steels is examined by means of thermal simulation of heat-affected zone (HAZ) microstructures. Tensile tests on notched bars and fracture toughness tests at various temperatures are performed together with fracture surface observations and cross-sectional analyses. The influence of martensite-austenite (M-A) constituents and of “crystallographic” bainite packets on cleavage fracture micromechanisms is, thus, evidenced as a function of temperature. Three weakest-link probabilistic models (the “Master-curve” (MC) approach, the Beremin model, and a “double-barrier” (DB) model) are applied to account for the ductile-to-brittle transition (DBT) fracture toughness curve. Some analogy, but also differences, are found between the MC approach and the Beremin model. The DB model, having nonfitted, physically based scatter parameters, is applied to the martensite-containing HAZ microstructures and gives promising results.

  3. Estimation of the most influential factors on the laser cutting process heat affected zone (HAZ) by adaptive neuro-fuzzy technique

    NASA Astrophysics Data System (ADS)

    Petković, Dalibor; Nikolić, Vlastimir; Milovančević, Miloš; Lazov, Lyubomir

    2016-07-01

    Heat affected zone (HAZ) of the laser cutting process may be developed on the basis on combination of different factors. In this investigation was analyzed the HAZ forecasting based on the different laser cutting parameters. The main aim in this article was to analyze the influence of three inputs on the HAZ of the laser cutting process. The method of ANFIS (adaptive neuro fuzzy inference system) was applied to the data in order to select the most influential factors for HAZ forecasting. Three inputs are considered: laser power, cutting speed and gas pressure. According the results the cutting speed has the highest influence on the HAZ forecasting (RMSE: 0.0553). Gas pressure has the smallest influence on the HAZ forecasting (RMSE: 0.0801). The results can be used in order to simplify HAZ prediction and analyzing.

  4. Synchrotron-Based Experimental Investigations and Numerical Modeling of the Kinetics of Phase Transformations in the Heat Affected Zone of Welds

    SciTech Connect

    2000-05-04

    Spatially Resolved X-Ray Diffraction (SRXRD) and Time Resolved X-Ray Diffraction (TRXRD) methods are being developed at LLNL for in-situ investigations of phase transformations in the heat-affected zone (HAZ) of welds. In this region of the weld, severe temperature gradients, high peak temperatures and rapid thermal fluctuations occur as the heat source passes through the material. These non-isothermal temperature fluctuations produce HAZ microstructures that cannot be predicted by conventional methods. The unique synchrotron-based experiments being developed here will enable the determination of phase transformation kinetics under true non-isothermal welding conditions, and can be used to aid in the development of models to predict HAZ microstructural evolution under a wide range of welding conditions. Commercially pure titanium, stainless steel alloys and plain carbon steels are currently under investigation.

  5. Effects of Thermal History and Microstructure on Segregation of Phosphorus and Alloying Elements in the Heat-Affected Zone of a Low Alloy Steel

    NASA Astrophysics Data System (ADS)

    Zhai, Ziqing; Miyahara, Yuichi; Abe, Hiroshi; Watanabe, Yutaka

    2014-12-01

    The grain boundary segregation of phosphorus and alloying elements in the heat-affected zone (HAZ) of a low alloy steel was studied quantitatively with atom probe tomography. Non-equilibrium segregation mainly occurred during welding and subsequent fast cooling, leading to remarkable segregation of P, C, Mn, and Mo. The segregation of these four types of solutes showed similar microstructure-dependence at this stage, in which the segregation levels are higher in coarse-grained HAZ and intercritically reheated coarse-grained HAZ than in fine-grained HAZ. After simulated aging, P and Mn showed further enrichment at grain boundaries through equilibrium segregation, while desegregation was observed for C and Mo. In addition, it seems that precipitation of Mo at dislocations was greatly promoted during aging, which probably also contributed to the increase of P and Mn at grain boundaries.

  6. Effects of Thermal History and Microstructure on Segregation of Phosphorus and Alloying Elements in the Heat-Affected Zone of a Low Alloy Steel

    NASA Astrophysics Data System (ADS)

    Zhai, Ziqing; Miyahara, Yuichi; Abe, Hiroshi; Watanabe, Yutaka

    2014-09-01

    The grain boundary segregation of phosphorus and alloying elements in the heat-affected zone (HAZ) of a low alloy steel was studied quantitatively with atom probe tomography. Non-equilibrium segregation mainly occurred during welding and subsequent fast cooling, leading to remarkable segregation of P, C, Mn, and Mo. The segregation of these four types of solutes showed similar microstructure-dependence at this stage, in which the segregation levels are higher in coarse-grained HAZ and intercritically reheated coarse-grained HAZ than in fine-grained HAZ. After simulated aging, P and Mn showed further enrichment at grain boundaries through equilibrium segregation, while desegregation was observed for C and Mo. In addition, it seems that precipitation of Mo at dislocations was greatly promoted during aging, which probably also contributed to the increase of P and Mn at grain boundaries.

  7. Influence of timing of sea ice retreat on phytoplankton size during marginal ice zone bloom period in the Chukchi and Bering shelves

    NASA Astrophysics Data System (ADS)

    Fujiwara, A.; Hirawake, T.; Suzuki, K.; Eisner, L.; Imai, I.; Nishino, S.; Kikuchi, T.; Saitoh, S. I.

    2015-08-01

    Timing of sea ice retreat (TSR) as well as cell size of primary producers (i.e., phytoplankton) plays crucial roles in seasonally ice-covered marine ecosystem. Thus, it is important to monitor the temporal and spatial distribution of phytoplankton community size structure. Prior to this study, an ocean color algorithm has been developed to derive phytoplankton size index FL, which is defined as the ratio of chlorophyll a derived from the cells larger than 5 μm to the total chl a using satellite remote sensing for the Chukchi and Bering shelves. Using this method, we analyzed pixel-by-pixel relationships between FL during marginal ice zone (MIZ) bloom period and TSR over a period of 1998-2013. The influence of TSR on sea surface temperature (SST) and changes in ocean heat content (ΔOHC) during the MIZ bloom period were also investigated. A significant negative relationship between FL and TSR was widely found in the shelf region during MIZ bloom season. On the other hand, we found a significant positive (negative) relationship between SST (ΔOHC) and TSR. That is, earlier sea-ice retreat was associated with a dominance of larger phytoplankton during a colder and weakly stratified MIZ bloom season, suggesting that duration of nitrate supply, which is important for large-sized phytoplankton growth in this region (i.e., diatoms), can change according to TSR. In addition, under-ice phytoplankton blooms are likely to occur in years with late ice retreat, because sufficient light for phytoplankton growth can pass through the ice and penetrate into the water columns due to an increase in solar radiation toward the summer solstice. Moreover, we found not only the length of ice-free season but also annual median of FL positively correlated with annual net primary production (APP). Thus, both phytoplankton community composition and growing season are important for APP in the study area. Our findings showed quantitative relationship between the inter-annual variability of FL

  8. Do changes in the size of mud flocs affect the acoustic backscatter values recorded by a Vector ADV?

    NASA Astrophysics Data System (ADS)

    Rouhnia, Mohamad; Keyvani, Ali; Strom, Kyle

    2014-08-01

    A series of experiments were conducted to examine the effect of mud floc growth on the acoustic back-scatter signal recorded by a Nortek Vector acoustic Doppler velocimeter (ADV). Several studies have shown that calibration equations can be developed to link the backscatter strength with average suspended sediment concentration (SSC) when the sediment particle size distribution remains constant. However, when mud is present, the process of flocculation can alter the suspended particle size distribution. Past studies have shown that it is still unclear as to the degree of dependence of the calibration equation on changes in floc size. Part of the ambiguity lies in the fact that flocs can be porous and rather loosely packed and therefore will not scatter sound waves as a solid particle would. In addition, direct, detailed measurements of floc size have not accompanied experiments examining the dependence of ADV backscatter and suspended sediment concentration. In this set of experiments, direct measurement of the floc size distribution is made with time in a mixing chamber using a floc camera system. A Vector ADV and an OBS are also placed within the tank to measure acoustic backscatter and SSC as the flocs change size with time; concentration in the experiments ranges from 15 to 90 mg/l. Results showed that the growth of mud flocs did influence the SNR recorded by the Vector ADV, and that the sensitivity of the SNR signal to changes in floc size was higher for flocs with diameters less than ≈80 μm (it kr=1 at a diameter of 80 μm). The response of SNR to changes in floc size and SSC was modeled with a modified sonar equation. If properly calibrated, the model was able to capture the functional behavior of SNR with changes in floc size and concentration. Values of the calibration coefficients showed that while changes in floc diameter up to about 80 μm did alter the SNR, the change was less than what would be expected from a similar change in the size of solid

  9. Lateral spike conduction velocity in the visual cortex affects spatial range of synchronization and receptive field size without visual experience: a learning model with spiking neurons.

    PubMed

    Saam, M; Eckhorn, R

    2000-07-01

    Classical receptive fields (cRF) increase in size from the retina to higher visual centers. The present work shows how temporal properties, in particular lateral spike velocity and spike input correlation, can affect cRF size and position without visual experience. We demonstrate how these properties are related to the spatial range of cortical synchronization if Hebbian learning dominates early development. For this, a largely reduced model of two successive levels of the visual cortex is developed (e.g., areas V1 and V2). It consists of retinotopic networks of spiking neurons with constant spike velocity in lateral connections. Feedforward connections between level 1 and 2 are additive and determine cRF size and shape, while lateral connections within level 1 are modulatory and affect the cortical range of synchronization. Input during development is mimicked by spike trains with spatially homogeneous properties and a confined temporal correlation width. During learning, the homogeneous lateral coupling shrinks to limited coupling structures defining synchronization and related association fields (AF). The size of level-1 synchronization fields determines the lateral coupling range of developing level-1-to-2 connections and, thus, the size of level-2 cRFs, even if the feedforward connections have distance-independent delays. AFs and cRFs increase with spike velocity in the lateral network and temporal correlation width of the input. Our results suggest that AF size of V1 and cRF size of V2 neurons are confined during learning by the temporal width of input correlations and the spike velocity in lateral connections without the need of visual experience. During learning from visual experience, a similar influence of AF size on the cRF size may be operative at successive levels of processing, including other parts of the visual system. PMID:10933233

  10. The sequence of moderate-size earthquakes at the junction of the Ligurian basin and the Corsica margin (western Mediterranean): The initiation of an active deformation zone revealed?

    NASA Astrophysics Data System (ADS)

    Larroque, Christophe; Delouis, Bertrand; Sage, Françoise; Régnier, Marc; Béthoux, Nicole; Courboulex, Françoise; Deschamps, Anne

    2016-04-01

    A new seismically active zone is found in the southern part of the Ligurian basin, 80-km west of Corsica (western Mediterranean). The activity began in February 2011 with a foreshock (ML 4) and a mainshock (ML 5.3) 5 days later, followed by numerous aftershocks. We first analyze the fore- and mainshock in detail. We compare the results obtained using classical methods (linear location in a 1D medium and focal mechanisms from P and S polarities) and new approaches (non-linear location in a 3D medium and waveform modeling for determining the seismic moment and the focal mechanism). Both methods provided similar results for location, depth (in the range of 6-13 km) and focal mechanisms, which reveal reverse faulting with nodal planes oriented N-S and NE-SW. We then locate 27 of the aftershocks in the 3D model and find a 10-km-long NE-SW alignment with a depth between 7 and 16 km. In 2012 and 2013, three other moderate-size events (ML 3.8, 4 and 4.5) occurred and confirm that this zone is still active. The epicentral area is located in the oceanic domain of the Ligurian Basin. From analysis of the bathymetry and high-resolution multi-channel seismic profiles, no morphologic anomaly at surface and no inherited fault in the shallow ~ 4 km depth were imaged, which suggest that no significant deformation occurred in the area since 5 Ma. Thus, the structure(s) activated during the 2011-2013 sequence remain unknown. In light of these results, we point out a notable difference on both sides of the Ligurian Basin: the northern margin, close to the alpine chain, suffered strong earthquakes and large cumulated deformation since 5 Ma, while the southern margin, close to the Corsica-Sardinia continental block, is poorly deformed since 5 Ma.

  11. Freeze-drying of polycaprolactone and poly(D,L-lactic-glycolic) nanoparticles induce minor particle size changes affecting the oral pharmacokinetics of loaded drugs.

    PubMed

    Saez, A; Guzmán, M; Molpeceres, J; Aberturas, M R

    2000-11-01

    The present study was geared at identifying the conditions to stabilize poly (D,L-lactic-glycolic) (PLGA) and polycaprolactone (PCL) nanoparticles (NP) by freeze-drying with several cryoprotective agents. Differential scanning calorimetry and freeze-thawing studies were used to optimize the lyophilization process. These studies showed that all samples were totally frozen at -45 degrees C and evidenced the necessity of adding sucrose, glucose, trehalose or gelatine to preserve the properties of NP regardless of the freezing procedure. However, only 20% sucrose and 20% glucose exerted an acceptable lyoprotective effect on PLGA and PCL NP, respectively. Nonetheless, the final to initial size ratios ( approximately 1.5) indicated that particle size was slightly affected in both cases. In vivo studies with CyA-loaded PCL NP whose sizes matched those obtained after NP preparation (100 nm) and after being lyophilized (160 nm) showed that the changes of particle size might have some relevance on drug pharmacokinetics. The MRT was significantly (P<0.05) modified after an oral CyA dose of 5 mg/kg and the treatment with 160-nm sized CyA-loaded NP produced a higher drug partition into the liver of Wistar rats potentially affecting the toxic and immunosuppressive profile of the drug. Therefore, although the particle size changes induced by NP lyophilization were slight, they need to be carefully evaluated and cannot be neglected. PMID:11072195

  12. Body size affects the predatory interactions between introduced American Bullfrogs (Rana catesbeiana) and native anurans in China: An experimental study

    USGS Publications Warehouse

    Wang, Y.; Guo, Z.; Pearl, C.A.; Li, Y.

    2007-01-01

    Introduced American Bullfrogs (Rana catesbeiana) have established breeding populations in several provinces in China since their introduction in 1959. Although Bullfrogs are viewed as a potentially important predator of Chinese native anurans, their impacts in the field are difficult to quantify. We used two experiments to examine factors likely to mediate Bullfrog predation on native anurans. First, we examined effects of Bullfrog size and sex on daily consumption of a common Chinese native (Rana limnocharis). Second, we examined whether Bullfrogs consumed similar proportions of four Chinese natives: Black-Spotted Pond Frog (Rana nigromaculata), Green Pond Frog (Rana plancyi plancyi), Rice Frog (R. limnocharis), and Zhoushan Toad (Bufo bufo gargarizans). We found that larger Rana catesbeiana consumed more R. limnocharis per day than did smaller R. catesbeiana, and that daily consumption of R. limnocharis was positively related to R. catesbeiana body size. When provided with adults of four anurans that differed significantly in body size, R. catesbeiana consumed more individuals of the smallest species (R. limnocharis). However, when provided with similarly sized juveniles of the same four species, R. catesbeiana did not consume any species more than expected by chance. Our results suggest that body size plays an important role in the predatory interactions between R. catesbeiana and Chinese native anurans and that, other things being equal, smaller species and individuals are at greater risk of predation by R. catesbeiana. Copyright 2007 Society for the Study of Amphibians and Reptiles.

  13. Inter-pulse Interval Affects the Size of Single-pulse TMS-induced Motor Evoked Potentials: A Reliability Study

    PubMed Central

    Vaseghi, Bita; Zoghi, Maryam; Jaberzadeh, Shapour

    2015-01-01

    Introduction: Measuring the size of motor evoked potentials (MEPs) induced by transcranial magnetic stimulation (TMS) is an investigational technique to show the level of corticospinal excitability; however, some of the fundamental methodological aspects of TMS (such as the effects of inter-pulse intervals (IPI) on MEP size) are not fully understood, this issue raises concerns about the reliability of MEPs, especially in pre-test post-test studies. Methods: MEP size at short and long IPIs was assessed during two separate sessions. Inter- and intra-session reliability of MEP size also was assessed at both short and long IPIs. Results: The results indicated that long IPIs induced larger MEPs (P< 0.05) across all time points. The intra-class correlation coefficient (ICC) indicated high intra- and inter-session reliability for short (0.87 to 0.96) and long (0.80 to 0.97) IPIs respectively. The amplitude of MEPs also had high intersession reliability for short (ICC=0.87) and long (ICC = 0.80) IPIs. Discussion: This study provides evidence that the length of IPIs determines the size of MEPs. As a result, it is recommended to add the length of IPI to the international checklist of considerations for TMS application.

  14. Colony Size Affects the Efficacy of Bait Containing Chlorfluazuron Against the Fungus-Growing Termite Macrotermes gilvus (Blattodea: Termitidae).

    PubMed

    Lee, Ching-Chen; Neoh, Kok-Boon; Lee, Chow-Yang

    2014-12-01

    The efficacy of chitin synthesis inhibitors (CSIs) against fungus-growing termites is known to vary. In this study, 0.1% chlorfluazuron (CFZ) cellulose bait was tested against medium and large field colonies of Macrotermes gilvus (Hagen). The termite mounds were dissected to determine the health of the colony. Individual termites (i.e., workers and larvae) and fungus combs were subjected to gas chromatography-mass spectrometry (GC-MS) analysis to detect the presence of CFZ. In this study, 540.0 ± 25.8 g (or equivalent to 540.0 ± 25.8 mg active ingredient) and 680.0 ± 49.0 g (680.0 ± 49.0 mg active ingredient) of bait matrix were removed by the medium- and large-sized colonies, respectively, after baiting. All treated medium-sized colonies were moribund. The dead termites were scattered in the mound, larvae were absent, population size had decreased by 90%, and the queens appeared unhealthy. In contrast, no or limited effects were found in large-sized colonies. Only trace amounts of CFZ were detected in workers, larvae, and fungus combs, and the population of large-sized colonies had declined by only up to 40%. This might be owing to the presence of large amount of basidiomycete fungus and a drastic decrease of CFZ content per unit fungus comb (a main food source of larvae) in the large-sized colonies, and hence reduced the toxic effect and longer time is required to accumulate the lethal dose in larvae. Nevertheless, we do not deny the possibility of CSI bait eliminating or suppressing the higher termite if the test colonies could pick up adequate lethal dose by installing more bait stations and prolonging the baiting period. PMID:26470081

  15. Impact of contact lens zone geometry and ocular optics on bifocal retinal image quality

    PubMed Central

    Bradley, Arthur; Nam, Jayoung; Xu, Renfeng; Harman, Leslie; Thibos, Larry

    2014-01-01

    Purpose To examine the separate and combined influences of zone geometry, pupil size, diffraction, apodisation and spherical aberration on the optical performance of concentric zonal bifocals. Methods Zonal bifocal pupil functions representing eye + ophthalmic correction were defined by interleaving wavefronts from separate optical zones of the bifocal. A two-zone design (a central circular inner zone surrounded by an annular outer-zone which is bounded by the pupil) and a five-zone design (a central small circular zone surrounded by four concentric annuli) were configured with programmable zone geometry, wavefront phase and pupil transmission characteristics. Using computational methods, we examined the effects of diffraction, Stiles Crawford apodisation, pupil size and spherical aberration on optical transfer functions for different target distances. Results Apodisation alters the relative weighting of each zone, and thus the balance of near and distance optical quality. When spherical aberration is included, the effective distance correction, add power and image quality depend on zone-geometry and Stiles Crawford Effect apodisation. When the outer zone width is narrow, diffraction limits the available image contrast when focused, but as pupil dilates and outer zone width increases, aberrations will limit the best achievable image quality. With two-zone designs, balancing near and distance image quality is not achieved with equal area inner and outer zones. With significant levels of spherical aberration, multi-zone designs effectively become multifocals. Conclusion Wave optics and pupil varying ocular optics significantly affect the imaging capabilities of different optical zones of concentric bifocals. With two-zone bifocal designs, diffraction, pupil apodisation spherical aberration, and zone size influence both the effective add power and the pupil size required to balance near and distance image quality. Five-zone bifocal designs achieve a high degree of

  16. Site specific fertilization affects yield, fruit size, quality, and shelf-life of ‘Kent' mango

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Site specific fertilization (SSF) defines the type and rate of fertilizer needed for individual orchards. This study presents preliminary results (2010-2011) of a medium term project to quantify the effects of SSF on yield, fruit size, quality, and shelf-life of ‘Kent’ mango. Two orchards are used f...

  17. Inclusions and Microstructure of Ce-Added Weld Metal Coarse Grain Heat-Affected Zone in Twin-Wire Submerged-Arc Welding

    NASA Astrophysics Data System (ADS)

    Yu, S. F.; Yan, N.; Chen, Y.

    2016-04-01

    In high heat-input multi-pass twin-wire submerged-arc welding, weld metal of previous pass will be affected by the heat input of subsequent one and form coarse-grained heat-affected zone (CGHAZ). This study focused on the effects of welding thermal cycle on the inclusions and microstructure of Ce-alloyed weld metal CGHAZ. According to the study of inclusions and microstructure of weld metal CGHAZ, it was found that the composition and type of the inclusions did not change under the effect of welding thermal cycle. Although the inclusions were coarsened slightly, the promoting ability to acicular ferrite (AF) was not deprived after thermal cycling. There are three types of AF in weld metal CGHAZ, which include oxy-sulfides of Ce inclusions-promoted AF, home-position-precipitated AF, and sympathetic AF. Results showed more than 80% of microstructure was AF, which greatly benefited the mechanical properties of weld metal CGHAZ, even though granular bainite and M-A constituents were generated.

  18. Inclusions and Microstructure of Ce-Added Weld Metal Coarse Grain Heat-Affected Zone in Twin-Wire Submerged-Arc Welding

    NASA Astrophysics Data System (ADS)

    Yu, S. F.; Yan, N.; Chen, Y.

    2016-06-01

    In high heat-input multi-pass twin-wire submerged-arc welding, weld metal of previous pass will be affected by the heat input of subsequent one and form coarse-grained heat-affected zone (CGHAZ). This study focused on the effects of welding thermal cycle on the inclusions and microstructure of Ce-alloyed weld metal CGHAZ. According to the study of inclusions and microstructure of weld metal CGHAZ, it was found that the composition and type of the inclusions did not change under the effect of welding thermal cycle. Although the inclusions were coarsened slightly, the promoting ability to acicular ferrite (AF) was not deprived after thermal cycling. There are three types of AF in weld metal CGHAZ, which include oxy-sulfides of Ce inclusions-promoted AF, home-position-precipitated AF, and sympathetic AF. Results showed more than 80% of microstructure was AF, which greatly benefited the mechanical properties of weld metal CGHAZ, even though granular bainite and M-A constituents were generated.

  19. Plant population size and isolation affect herbivory of Silene latifolia by the specialist herbivore Hadena bicruris and parasitism of the herbivore by parasitoids.

    PubMed

    Elzinga, Jelmer A; Turin, Hans; van Damme, Jos M M; Biere, Arjen

    2005-07-01

    Habitat fragmentation can affect levels of herbivory in plant populations if plants and herbivores are differentially affected by fragmentation. Moreover, if herbivores are top-down controlled by predators or parasitoids, herbivory may also be affected by differential effects of fragmentation on herbivores and their natural enemies. We used natural Silene latifolia populations to examine the effects of plant population size and isolation on the level of herbivory by the seed predating noctuid Hadena bicruris and the rate of parasitism of the herbivore by its parasitoids. In addition, we examined oviposition rate, herbivory and parasitism in differently sized experimental populations. In natural populations, the level of herbivory increased and the rate of parasitism decreased with decreasing plant population size and increasing degree of isolation. The number of parasitoid species also declined with decreasing plant population size. In the experimental populations, the level of herbivory was also higher in smaller populations, in accordance with higher oviposition rates, but was not accompanied by lower rates of parasitism. Similarly, oviposition rate and herbivory, but not parasitism rate, increased near the edges of populations. These results suggests that in this system with the well dispersing herbivore H. bicruris, habitat fragmentation increases herbivory of the plant through a behavioural response of the moth that leads to higher oviposition rates in fragmented populations with a reduced population size, increased isolation and higher edge-to-interior ratio. Although the rate of parasitism and the number of parasitoid species declined with decreasing population size in the natural populations, we argue that in this system it is unlikely that this decline made a major contribution to increased herbivory. PMID:15891816

  20. FACTORS AFFECTING OVULATORY FOLLICLE SIZE AND OVULATION SUCCESS TO GNRH-INDUCED OVULATION IN POSTPARTUM BEEF COWS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In the present study, the effects of day of the estrous cycle and ovulatory response at the first GnRH injection on size of the dominant follicle at the second GnRH were examined in multi-parous lactating beef cows (n=60). GnRH was administered on day -9 (GnRH1), prostaglandin F2' on day -2, and Gn...

  1. Observations of Ferrite/Austenite Transformations in the Heat Affected Zone of 2205 Duplex Stainless Steel Spot Welds Using Time Resolved X-Ray Diffraction

    SciTech Connect

    Palmer, T; Elmer, J; Babu, S

    2003-10-29

    Time Resolved X-Ray Diffraction (TRXRD) measurements are made in the Heat Affected Zone (HAZ) of 2205 Duplex Stainless Steel (DSS) spot welds. Both the {gamma} {yields} {delta} and {delta} {yields} {gamma} transformations are monitored as a function of time during the rapid spot weld heating and cooling cycles. These observations are then correlated with calculated thermal cycles. Where the peak temperatures are highest ({approx}1342 C), the {gamma} {yields} {delta} transformation proceeds to completion, leaving a ferritic microstructure at the end of heating. With lower peak temperatures, the {gamma} {yields} {delta} transformation proceeds to only partial completion, resulting in a microstructure containing both transformed and untransformed austenite. Further analyses of the individual diffraction patterns show shifts in the peak positions and peak widths as a function of both time and temperature. In addition, these changes in the peak characteristics are correlated with measured changes in the ferrite volume fraction. Such changes in the peak positions and widths during the {gamma} {yields} {delta} transformation provide an indication of changes occurring in each phase. These changes in peak properties can be correlated with the diffusion of nitrogen and other substitutional alloying elements, which are recognized as the primary mechanisms for this transformation. Upon cooling, the {delta} {yields} {gamma} transformation is observed to proceed from both the completely and partially transformed microstructural regions in the TRXRD data. An examination of the resulting microstructures confirms the TRXRD observation as the evidence shows that austenite both nucleates and grows from the ferritic microstructure at locations closest to the fusion zone boundary and grows from untransformed austenite grains at locations further from this boundary.

  2. Magnetic characterization of radio frequency heat affected micron size Fe3O4 powders: a bio-application perspective.

    PubMed

    Roul, B K; Mishra, D K; Ray, M; Sahu, D R; Mishra, P K; Srinivasu, V V; Pradhan, A K

    2009-05-01

    Micron size Fe3O4 powders were chemically prepared and processed by radio frequency (13.56 MHz) oxygen plasma irradiation technique at different elevated temperatures using low radio frequency (RF) power level. Low magnetic field RF superconducting quantum interference device (SQUID) magnetization studies were performed up to a maximum magnetic field of 100 Oe, which was well below the magnetic field tolerance factor of human beings and at different temperatures (down to 5 K). Heat-treated powders in RF oxygen plasma showed significant changes in blocking temperature, magnetization and susceptibility, which are important parameters for bio-applications. It is observed that blocking temperature is decreased under identical RF heat treatment in oxygen plasma and noted to be dependent on average particle size. Microscopic rise in electron temperature during RF heating may likely to enhance the electron-hopping rate between Fe(+2) and Fe(+3) in the octahedral site of Fe3O4 molecular crystal structure, which in turn exhibit changes in blocking temperature including low field magnetization and susceptibility. These properties of Fe3O4 fine powder are likely to play important role in generating and processing biocompatible Ferro-fluid down to nanoscopic size for biomaterials applications. PMID:19452992

  3. Arbuscular mycorrhizal fungal communities in sub-Saharan savannas of Benin, West Africa, as affected by agricultural land use intensity and ecological zone.

    PubMed

    Tchabi, Atti; Coyne, Danny; Hountondji, Fabien; Lawouin, Louis; Wiemken, Andres; Oehl, Fritz

    2008-04-01

    The rapid decline of soil fertility of cultivated lands in the sub-Saharan savannas of West Africa is considered to be the main cause of the increasingly severe constraints of food production. The soils in this tropical area are highly fragile, and crop yields are limited by characteristically low levels of available phosphorus. Under such preconditions, the multiple benefits of the arbuscular mycorrhizal (AM) symbiosis are likely to play a pivotal role for maintaining natural soil fertility by enhancing plant nutrient use efficiency, plant health, and stabilization of a favorable soil structure. Thus, it is important to explore the impact of the commonly applied farming practices on the native AM fungal community. In the present study, we determined the AM fungal species composition in three ecological zones differing by an increasingly prolonged dry season from South to North, from the Southern Guinea Savanna (SG), to the Northern Guinea Savanna (NG), to the Sudan Savanna (SU). In each zone, four "natural" and four "cultivated" sites were selected. "Natural" sites were three natural forest savannas (at least 25-30 years old) and a long-term fallow (6-7 years old). "Cultivated" sites comprised a field with yam (Dioscorea spp.) established during the first year after forest clearance, a field under mixed cropping with maize (Zea mays) and peanut (Arachis hypogaea), a field under peanut, and a field under cotton (Gossypium hirsutum) which was the most intensively managed crop. Soil samples were collected towards the end of the wet season in each zone. AM fungal spores were extracted and morphologically identified. Soil subsamples were used to inoculate AM fungal trap cultures using Stylosanthes guianensis and Brachiaria humidicola as host plants to monitor AM root colonization and spore formation over 10 and 24 months, respectively. A total of 60 AM fungal species were detected, with only seven species sporulating in the trap cultures. Spore density and species

  4. Brittle grain size reduction of feldspar, phase mixing and strain localization in granitoids at mid-crustal conditions (Pernambuco shear zone, NE Brazil)

    NASA Astrophysics Data System (ADS)

    Viegas, G.; Menegon, L.; Archanjo, C. J.

    2015-10-01

    The Pernambuco shear zone (northeastern Brazil) is a large-scale strike-slip fault that, in its eastern segment, deforms granitoids at mid-crustal conditions. Initially coarse (> 50 μm) grained feldspar porphyroclasts are intensively fractured and reduced to an ultrafine-grained mixture consisting of plagioclase and K-feldspar grains (~ < 15 μm in size) localized in C' shear bands. Detailed microstructural observations and EBSD analysis do not show evidence of intracrystalline plasticity in feldspar porphyroclasts and/or fluid-assisted replacement reactions. Quartz occurs either as thick (~ 1-2 mm) monomineralic bands or as thin ribbons dispersed in the feldspathic mixture. The microstructure and c axis crystallographic preferred orientation are similar in the thick monomineralic band and in the thin ribbons, and suggest dominant subgrain rotation recrystallization and activity of prism ⟨a⟩ and rhomb ⟨a⟩ slip systems. However, the grain size in monophase recrystallized domains decreases when moving from the transposed veins to the thin ribbons embedded in the feldspathic C' bands (14 μm vs. 5 μm, respectively). The fine-grained feldspar mixture has a weak crystallographic preferred orientation interpreted as the result of oriented growth during diffusion creep, as well as the same composition as the fractured porphyroclasts, suggesting that it generated by mechanical fragmentation of rigid porphyroclasts with a negligible role of chemical disequilibrium. Assuming that the C' shear bands deformed under constant stress conditions, the polyphase feldspathic aggregate would have deformed at a strain rate one order of magnitude faster than the monophase quartz ribbons. Overall, our dataset indicates that feldspar underwent a brittle-viscous transition while quartz was deforming via crystal plasticity. The resulting rock microstructure consists of a two-phase rheological mixture (fine-grained feldspars and recrystallized quartz) in which the polyphase

  5. Elevated air humidity affects hydraulic traits and tree size but not biomass allocation in young silver birches (Betula pendula)

    PubMed Central

    Sellin, Arne; Rosenvald, Katrin; Õunapuu-Pikas, Eele; Tullus, Arvo; Ostonen, Ivika; Lõhmus, Krista

    2015-01-01

    As changes in air temperature, precipitation, and air humidity are expected in the coming decades, studies on the impact of these environmental shifts on plant growth and functioning are of major importance. Greatly understudied aspects of climate change include consequences of increasing air humidity on forest ecosystems, predicted for high latitudes. The main objective of this study was to find a link between hydraulic acclimation and shifts in trees’ resource allocation in silver birch (Betula pendula Roth) in response to elevated air relative humidity (RH). A second question was whether the changes in hydraulic architecture depend on tree size. Two years of application of increased RH decreased the biomass accumulation in birch saplings, but the biomass partitioning among aboveground parts (leaves, branches, and stems) remained unaffected. Increased stem Huber values (xylem cross-sectional area to leaf area ratio) observed in trees under elevated RH did not entail changes in the ratio of non-photosynthetic to photosynthetic tissues. The reduction of stem–wood density is attributable to diminished mechanical load imposed on the stem, since humidified trees had relatively shorter crowns. Growing under higher RH caused hydraulic conductance of the root system (KR) to increase, while KR (expressed per unit leaf area) decreased and leaf hydraulic conductance increased with tree size. Saplings of silver birch acclimate to increasing air humidity by adjusting plant morphology (live crown length, slenderness, specific leaf area, and fine-root traits) and wood density rather than biomass distribution among aboveground organs. The treatment had a significant effect on several hydraulic properties of the trees, while the shifts were largely associated with changes in tree size but not in biomass allocation. PMID:26528318

  6. Habitat complexity and fish size affect the detection of Indo-Pacific lionfish on invaded coral reefs

    NASA Astrophysics Data System (ADS)

    Green, S. J.; Tamburello, N.; Miller, S. E.; Akins, J. L.; Côté, I. M.

    2013-06-01

    A standard approach to improving the accuracy of reef fish population estimates derived from underwater visual censuses (UVCs) is the application of species-specific correction factors, which assumes that a species' detectability is constant under all conditions. To test this assumption, we quantified detection rates for invasive Indo-Pacific lionfish ( Pterois volitans and P. miles), which are now a primary threat to coral reef conservation throughout the Caribbean. Estimates of lionfish population density and distribution, which are essential for managing the invasion, are currently obtained through standard UVCs. Using two conventional UVC methods, the belt transect and stationary visual census (SVC), we assessed how lionfish detection rates vary with lionfish body size and habitat complexity (measured as rugosity) on invaded continuous and patch reefs off Cape Eleuthera, the Bahamas. Belt transect and SVC surveys performed equally poorly, with both methods failing to detect the presence of lionfish in >50 % of surveys where thorough, lionfish-focussed searches yielded one or more individuals. Conventional methods underestimated lionfish biomass by ~200 %. Crucially, detection rate varied significantly with both lionfish size and reef rugosity, indicating that the application of a single correction factor across habitats and stages of invasion is unlikely to accurately characterize local populations. Applying variable correction factors that account for site-specific lionfish size and rugosity to conventional survey data increased estimates of lionfish biomass, but these remained significantly lower than actual biomass. To increase the accuracy and reliability of estimates of lionfish density and distribution, monitoring programs should use detailed area searches rather than standard visual survey methods. Our study highlights the importance of accounting for sources of spatial and temporal variation in detection to increase the accuracy of survey data from

  7. Endogenous leptin receptor signaling in the medial nucleus tractus solitarius affects meal size and potentiates intestinal satiation signals

    PubMed Central

    Kanoski, Scott E.; Zhao, Shiru; Guarnieri, Douglas J.; DiLeone, Ralph J.; Yan, Jianqun; De Jonghe, Bart C.; Bence, Kendra K.; Hayes, Matthew R.

    2012-01-01

    Leptin receptor (LepRb) signaling in the hindbrain is required for energy balance control. Yet the specific hindbrain neurons and the behavioral processes mediating energy balance control by hindbrain leptin signaling are unknown. Studies here employ genetic [adeno-associated virally mediated RNA interference (AAV-RNAi)] and pharmacological methodologies to specify the neurons and the mechanisms through which hindbrain LepRb signaling contributes to the control of food intake. Results show that AAV-RNAi-mediated LepRb knockdown targeting a region encompassing the mNTS and area postrema (AP) (mNTS/AP LepRbKD) increases overall cumulative food intake by increasing the size of spontaneous meals. Other results show that pharmacological hindbrain leptin delivery and RNAi-mediated mNTS/AP LepRb knockdown increased and decreased the intake-suppressive effects of intraduodenal nutrient infusion, respectively. These meal size and intestinally derived signal amplification effects are likely mediated by LepRb signaling in the mNTS and not the AP, since 4th icv and mNTS parenchymal leptin (0.5 μg) administration reduced food intake, whereas this dose did not influence food intake when injected into the AP. Overall, these findings deepen the understanding of the distributed neuronal systems and behavioral mechanisms that mediate the effects of leptin receptor signaling on the control of food intake. PMID:22693203

  8. Effect of Heat Input on Microstructure Evolution and Mechanical Properties in the Weld Heat-Affected Zone of 9Cr-2W-VTa Reduced Activation Ferritic-Martensitic Steel for Fusion Reactor

    NASA Astrophysics Data System (ADS)

    Moon, Joonoh; Lee, Chang-Hoon; Lee, Tae-Ho; Kim, Hyoung Chan

    2015-01-01

    The phase transformation and mechanical properties in the weld heat-affected zone (HAZ) of a reduced activation ferritic/martensitic steel were explored. The samples for HAZs were prepared using a Gleeble simulator at different heat inputs. The base steel consisted of tempered martensite and carbides through quenching and tempering treatment, whereas the HAZs consisted of martensite, δ-ferrite, and a small volume of autotempered martensite. The prior austenite grain size, lath width of martensite, and δ-ferrite fraction in the HAZs increased with increase in the heat input. The mechanical properties were evaluated using Vickers hardness and Charpy V-notch impact test. The Vickers hardness in the HAZs was higher than that in the base steel but did not change noticeably with increase in the heat input. The HAZs showed poor impact property due to the formation of martensite and δ-ferrite as compared to the base steel. In addition, the impact property of the HAZs deteriorated more with the increase in the heat input. Post weld heat treatment contributed to improve the impact property of the HAZs through the formation of tempered martensite, but the impact property of the HAZs remained lower than that of base steel.

  9. Evidence of multi-stage faulting by clay mineral analysis: Example in a normal fault zone affecting arkosic sandstones (Annot sandstones)

    NASA Astrophysics Data System (ADS)

    Buatier, Martine D.; Cavailhes, Thibault; Charpentier, Delphine; Lerat, Jérémy; Sizun, Jean Pierre; Labaume, Pierre; Gout, Claude

    2015-06-01

    Fault affecting silicoclastic sediments are commonly enriched in clay minerals. Clays are sensitive to fluid-rock interactions and deformation mechanisms; in this paper, they are used as proxy for fault activity and behavior. The present study focuses on clay mineral assemblages from the Point Vert normal fault zone located in the Annot sandstones, a Priabonian-Rupelian turbidite succession of the Alpine foredeep in SE France. In this area, the Annot sandstones were buried around 6-8 km below the front of Alpine nappes soon after their deposition and exhumed during the middle-late Miocene. The fault affects arkosic sandstone beds alternating with pelitic layers, and displays throw of about thirty meters. The fault core zone comprises intensely foliated sandstones bounding a corridor of gouge about 20 cm thick. The foliated sandstones display clay concentration along S-C structures characterized by dissolution of K-feldspar and their replacement by mica, associated with quartz pressure solution, intense microfracturation and quartz vein precipitation. The gouge is formed by a clayey matrix containing fragments of foliated sandstones and pelites. However, a detailed petrographical investigation suggests complex polyphase deformation processes. Optical and SEM observations show that the clay minerals fraction of all studied rocks (pelites and sandstones from the damage and core zones of the fault) is dominated by white micas and chlorite. These minerals have two different origins: detrital and newly-formed. Detrital micas are identified by their larger shape and their chemical composition with a lower Fe-Mg content than the newly-formed white micas. In the foliated sandstones, newly-formed white micas are concentrated along S-C structures or replace K-feldspar. Both types of newly formed micas display the same chemical composition confirmed microstructural observations suggesting that they formed in the same conditions. They have the following structural formulas: Na0

  10. Heat-affected zone fracture toughness of 420-500 MPa yield strength steels: Effects of chemical composition and welding conditions

    SciTech Connect

    Tronskar, J.P. )

    1993-02-01

    During the last five years, high-strength steels with yield strengths in the range 420 to 500 MPa have attracted considerable interest within the offshore industry, primarily due to the potential for weight saving and reduction in volume of weld metal through the use of reduced section thicknesses. With respect to chemical composition these steels are developed following much the same philosophy as for the modern normalized structural steels. Due to the increased stress level in these higher strength steels, it is anticipated that brittle fracture initiation occurring in the coarse-gained HAZ will be more critical for these steels than for the lower strength normalized grades. The objective of this paper is to present the results from several experimental investigations carried out at VERITEC during the last five years to study the factors affecting the crack tip opening displacement (CTOD) fracture toughness of the heat-affected zone (HAZ) in structural steels in the yield strength range 420-500 MPa. Typical CTOD fracture toughnesses of the HAZ in normalized 350-MPa yield strength steels used in offshore structures are also presented for comparison. The results of the investigations confirm that the same chemical compositional factors which are known to influence the HAZ fracture toughness of normalized steels are also important for the 420-500-MPa yield strength steels. It is demonstrated that the width of the HAZ is important for the initiation of brittle fracture of pop-in and that this width must exceed a certain minimum value for such events to occur.

  11. Precipitation Behavior in the Heat-Affected Zone of Boron-Added 9Cr-3W-3Co Steel During Post-Weld Heat Treatment and Creep Deformation

    NASA Astrophysics Data System (ADS)

    Liu, Yuan; Tsukamoto, Susumu; Sawada, Kota; Tabuchi, Masaaki; Abe, Fujio

    2015-05-01

    In the previous paper, we demonstrated that the addition of boron was effective in preventing type IV failure due to suppression of grain refinement in the heat-affected zone at the peak temperature of around AC3 (AC3 HAZ). However, some fine prior austenite grains (PAGs) still remained around the coarse PAG boundaries, and these fine PAGs may affect the creep property of the welded joint. In the present study, the effect of these fine PAGs on the creep property of the boron-added 9Cr-3Co-3W steel (B steel) Ac3 HAZ is investigated. Different heat treatments are carried out on B steel base metal to form different Ac3 HAZ-simulated microstructures of coarse PAG with and without fine PAGs. Ac3 HAZ microstructure shows that a lot of M23C6 carbides are formed at the block boundary in the interior of coarse PAG. On the other hand, few M23C6 carbides are formed at the fine PAG boundaries, but a number of μ phases (W6Fe7 type) cover the boundary. The formation of μ phase retards the recovery of dislocation at the fine PAG boundary and contributes to stabilizing the microstructure in the primary and transient creep regions. The μ phase transforms to the Laves phase during creep. As the growth rate of Laves phase is higher than that of M23C6 carbides during creep, the creep strength of fine PAG boundary, which is strengthened only by Laves phase, becomes a little bit lower than the other boundaries strengthened by M23C6 carbides after long-term creep. The mismatch of creep strength between the fine PAG boundary and the matrix should be taken into account to attain an excellent long-term creep property of the B steel welded joint.

  12. How parasitism affects critical patch-size in a host-parasitoid model: application to the forest tent caterpillar.

    PubMed

    Cobbold, C A; Lewis, M A; Lutscher, F; Roland, J

    2005-03-01

    Habitat structure has broad impacts on many biological systems. In particular, habitat fragmentation can increase the probability of species extinction and on the other hand it can lead to population outbreaks in response to a decline in natural enemies. An extreme consequence of fragmentation is the isolation of small regions of suitable habitat surrounded by a large region of hostile matrix. This scenario can be interpreted as a critical patch-size problem, well studied in a continuous time framework, but relatively new to discrete time models. In this paper we present an integrodifference host-parasitoid model, discrete in time and continuous in space, to study how the critical habitat-size necessary for parasitoid survival changes in response to parasitoid life history traits, such as emergence time. We show that early emerging parasitoids may be able to persist in smaller habitats than late emerging species. The model predicts that these early emerging parasitoids lead to more severe host outbreaks. We hypothesise that promoting efficient late emerging parasitoids may be key in reducing outbreak severity, an approach requiring large continuous regions of suitable habitat. We parameterise the model for the host species of the forest tent caterpillar Malacosoma disstria Hbn., a pest insect for which fragmented landscape increases the severity of outbreaks. This host is known to have several parasitoids, due to paucity of data and as a first step in the modelling we consider a single generic parasitoid. The model findings are related to observations of the forest tent caterpillar offering insight into this host-parasitoid response to habitat structure. PMID:15713324

  13. Effect of welding conditions on transformation and properties of heat-affected zones in LWR (light-water reactor) vessel steels

    SciTech Connect

    Lundin, C.D.; Mohammed, S. . Welding Research and Engineering)

    1990-11-01

    The continuous cooling transformation behavior (CCT) and isothermal transformation (IT) behavior were determined for SA-508 and SA-533 materials for conditions pertaining to standard heat treatment and for the coarse-grained region of the heat-affected zone (HAZ). The resulting diagrams help to select welding conditions that produce the most favorable microconstituent for the development of optimum postweld heat treatment (PWHT) toughness levels. In the case of SA-508 and SA-533, martensite responds more favorably to PWHT than does bainite. Bainite is to be avoided for the optimum toughness characteristics of the HAZ. The reheat cracking tendency for both steels was evaluated by metallographic studies of simulated HAZ structures subjected to PWHT cycles and simultaneous restraint. Both SA-533, Grade B, Class 1, and SA-508, Class 2, cracked intergranularly. The stress rupture parameter (the product of the stress for a rupture life of 10 min and the corresponding reduction of area) calculated for both steels showed that SA-508, Class 2, was more susceptible to reheat cracking than SA-533, Grade B, Class 1. Cold cracking tests (Battelle Test and University of Tennessee modified hydrogen susceptibility test) indicated that a higher preheat temperature is required for SA-508, Class 2, to avoid cracking than is required for SA-533, Grade B, Class 1. Further, the Hydrogen Susceptibility Test showed that SA-508, Class 2, is more susceptible to hydrogen embrittlement than is SA-533, Grade B, Class 1.

  14. Effects of alloying elements on mechanical and fracture properties of base metals and simulated heat-affected zones of SA 508 steels

    NASA Astrophysics Data System (ADS)

    Kim, Sangho; Lee, Sunghak; Im, Young-Roc; Lee, Hu-Chul; Oh, Yong Jun; Hong, Jun Hwa

    2001-04-01

    This study was aimed at developing low-alloy steels for nuclear reactor pressure vessels by investigating the effects of alloying elements on mechanical and fracture properties of base metals and heat-affected zones (HAZs). Four steels whose compositions were variations of the composition specification for SA 508 steel (class 3) were fabricated by vacuum-induction melting and heat treatment, and their tensile properties and Charpy impact toughness were evaluated. Microstructural analyses indicated that coarse M3C-type carbides and fine M2C-type carbides were precipitated along lath boundaries and inside laths, respectively. In the steels having decreased carbon content and increased molybdenum content, the amount of fine M2C carbides was greatly increased, while that of coarse M3C carbides was decreased, thereby leading to the improvement of tensile properties and impact toughness. Their simulated HAZs also had sufficient impact toughness after postweld heat treatment (PWHT). These findings suggested that the low-alloy steels with high strength and toughness could be processed by decreasing carbon and manganese contents and by increasing molybdenum content.

  15. Effects of cooling time and alloying elements on the microstructure of the gleeble-simulated heat-affected zone of 22% Cr duplex stainless steels

    NASA Astrophysics Data System (ADS)

    Hsieh, Rong-Iuan; Liou, Horng-Yih; Pan, Yeong-Tsuen

    2001-10-01

    The effects of austenite stabilizers, such as nitrogen, nickel, and manganese, and cooling time on the microstructure of the Gleeble simulated heat-affected zone (HAZ) of 22% Cr duplex stainless steels were investigated. The submerged are welding was performed for comparison purposes. Optical microscopy (OM) and transmission electron microscopy (TEM) were used for microscopic studies. The amount of Cr2N precipitates in the simulated HAZ was determined using the potentiostatic electrolysis method. The experimental results indicate that an increase in the nitrogen and nickel contents raised the δ to transformation temperature and also markedly increased the amount of austenite in the HAZ. The lengthened cooling time promotes the reformation of austenite. An increase in the austenite content reduces the supersaturation of nitrogen in ferrite matrix as well as the precipitation tendency of Cr2N. The optimum cooling time from 800 to 500 °C (Δ t 8/5) obtained from the Gleeble simulation is between 30 and 60 s, which ensures the austenite content in HAZ not falling below 25% and superior pitting and stress corrosion cracking resistance for the steels. The effect of manganese on the formation of austenite can be negligible.

  16. The structure of the heat-affected zone in welds of a Ni-29 wt. % Mo commercial alloy (Hastelloy B2)

    SciTech Connect

    Cao, S.; Brooks, C.R. ); Whittaker, G. )

    1994-07-01

    The microstructure of a welded pipe of Hastelloy B2 removed from a coal gasification plant was examined. Although this alloy is susceptible to severe embrittlement if ordering occurs, no significant ordering was found in the heat-affected zone (HAZ) or the weld, and the material was ductile. However, intergranular corrosion was found in the HAZ, and fine (e.g., 0.1mm) particles of Mo-rich M[sub 12]C carbide and the intermetallic compound NiMo were found in the grain boundaries. These are apparently depleting the adjacent matrix of Mo, rendering the grain boundary region susceptible to corrosion. A single- and a double-pass autogeneous weld made on the base-plate material were examined. No ordering was detected in the HAZ, which is consistent with the measured temperature-time curves of regions adjacent to the weld and with the known ordering kinetics. In the HAZ, fine grain boundary particles of M[sub 12] carbide were detected, and NiMo may also be present.

  17. Phase transformation and impact properties in the experimentally simulated weld heat-affected zone of a reduced activation ferritic/martensitic steel

    NASA Astrophysics Data System (ADS)

    Moon, Joonoh; Lee, Chang-Hoon; Lee, Tae-Ho; Jang, Min-Ho; Park, Min-Gu; Han, Heung Nam

    2014-12-01

    In this work, the phase transformation and impact properties in the weld heat-affected zone (HAZ) of a reduced activation ferritic/martensitic (RAFM) steel are investigated. The HAZs were experimentally simulated using a Gleeble simulator. The base steel consisted of tempered martensite through normalizing at 1000 °C and tempering at 750 °C, while the HAZs consisted of martensite, δ-ferrite and a small volume of autotempered martensite. The impact properties using a Charpy V-notch impact test revealed that the HAZs showed poor impact properties due to the formation of martensite and δ-ferrite as compared with the base steel. In addition, the impact properties of the HAZs further deteriorated with an increase in the δ-ferrite fraction caused by increasing the peak temperature. The impact properties of the HAZs could be improved through the formation of tempered martensite after post weld heat treatment (PWHT), but they remained lower than that of the base steel because the δ-ferrite remained in the tempered HAZs.

  18. Interdependence of character of grain boundaries, intergranular segregation of boron and grain boundary liquation in simulated weld heat-affected zone in Inconel 718

    SciTech Connect

    Guo, H.; Chaturvedi, M.C.; Richards, N.L.; McMahon, G.S.

    1999-01-08

    Intergranular microfissuring is frequently observed in the weld heat-affected zones (HAZ) in Inconel 718. Extensive studies of this phenomenon have established that the HAZ microfissuring in Inconel 718 is associated with the constitutional liquation of grain boundary (GB) precipitates of carbides, Laves and {delta} phases. In addition, HAZ microfissuring has been also attributed to the GB segregation of B and S. To differentiate between the influence of B from other factors, studies were initiated on Inconel 718 that was almost free of C, P, and S, and contained different concentrations of B. These studies have shown that B in Inconel 718 can segregate to the grain boundaries by a non-equilibrium mechanism during cooling from the pre-weld solution heat treatment temperature, which would lower the melting temperature of the GB material. If the segregation of B is sufficiently high, the GBs are likely to liquate in the HAZ during the heating component of the welding thermal cycle. The inability of the liquated GBs to support tensile stresses that develop during cooling of the welds would result in microfissuring in the HAZs. It was also observed that the GB liquation in the HAZs was heterogeneously distributed. That is, while a GB liquated others connected to it did not. Therefore, an investigation was initiated to determine the interdependence of segregation of B on GBs, their crystallographic character and liquation. The results are presented in this communication.

  19. Segregation behavior of phosphorus in the heat-affected zone of an A533B/A182 dissimilar weld joint before and after simulated thermal aging

    NASA Astrophysics Data System (ADS)

    Zhai, Ziqing; Miyahara, Yuichi; Abe, Hiroshi; Watanabe, Yutaka

    2014-09-01

    The segregation behavior of phosphorus (P) in the heat-affected zone (HAZ) of an A533B/A182 dissimilar weld joint before and after step cooling was investigated with atom probe tomography. At grain/packet boundaries, the final P segregation level consisted of non-equilibrium segregation that occurred during cooling after welding and post-weld heat treatment (PWHT) and equilibrium segregation that occurred during step cooling. In both processes, higher P coverage was observed in the coarse-grained and intercritically reheated coarse-grained HAZ than in the fine-grained HAZ and base material. The cooling after welding and PWHT seemed to have a pronounced impact on P segregation in the subsequent aging process. In addition, P segregation also occurred at the precipitate/matrix interfaces of cementite, Mo2C and Al-Si rich precipitates. The evolution of P coverage at these two types of sites suggested increasing risks of embrittlement with an increase in aging time.

  20. Mapping Phase Transformations in the Heat-Affected-Zone of Carbon Manganese Steel Welds using Spatially Resolved X-Ray Diffraction

    SciTech Connect

    Elmer, J W; Wong, J; Ressler, T; Palmer, T A

    2001-12-04

    Spatially Resolved X-Ray Diffraction (SRXRD) was used to investigate phase transformations that occur in the heat affected zone (HAZ) of gas tungsten arc (GTA) welds in AISI 1005 carbon-manganese steel. In situ SRXRD experiments performed at the Stanford Synchrotron Radiation Laboratory (SSRL) probed the phases present in the HAZ during welding, and these real-time observations of the HAZ phases were used to construct a map of the phase transformations occurring in the HAZ. This map identified 5 principal phase regions between the liquid weld pool and the unaffected base metal for the carbon-manganese steel studied in this investigation. Regions of annealing, recrystallization, partial transformation and complete transformation to {alpha}-Fe, {gamma}-Fe, and {delta}-Fe phases were identified using SRXRD, and the experimental results were combined with a heat flow model of the weld to investigate transformation kinetics under both positive and negative temperature gradients in the HAZ. From the resulting phase transformation map, the kinetics of phase transformations that occur under the highly non-isothermal heating and cooling cycles produced during welding of steels can now be better understood and modeled.

  1. Physical metallurgical basis for heat-affected zone and base-plate properties of a microalloyed HSLA steel. Final report 1984-1986

    SciTech Connect

    Nichting, R.A.; Brown, E.L.

    1986-12-01

    The overall objective of this study was to elucidate the processing structure/property relationship associated with the heat-affected zone (HAZ) produced in an HSLA microalloyed steel during arc welding. Single-pass submerged arc welds on a Nb-V microalloyed steel were made with variable heat input. The thermal cycle as a function of heat input and position in the HAZ was determined experimentally in the course of welding. In addition, weld simulations were produced for selected heat inputs and HAZ locations. The evolution of austenite and transformation product microstructure as well as the state of microalloy precipitation was monitored as a function of heat input and HAZ location primarily via light and electron microscopy on specimens from actual welds and simulation specimens. These observations were utilized to support efforts to model austenite microstructure evolution and continuous-cooling transformation behavior in the HAZ. Charpy-impact-toughness testing was performed on actual weld HAZ specimens and specimens of selected simulation specimens. Impact transition curves were determined, and the microsctructure through which fracture propagated was correlated with impact transition energies and fracture surface morphology determined via scanning electron microscopy.

  2. Mapping Phase Transformations in the Heat-Affected-Zone of Carbon Manganese Steel Welds using Spatially Resolved X-Ray Diffraction

    SciTech Connect

    Elmer, J W; Wong, J; Ressler, T; Palmer, T A

    2002-02-12

    Spatially Resolved X-Ray Diffraction (SRXRD) was used to investigate phase transformations that occur in the heat affected zone (HAZ) of gas tungsten arc (GTA) welds in AISI 1005 carbon-manganese steel. In situ SRXRD experiments performed at the Stanford Synchrotron Radiation Laboratory (SSRL) probed the phases present in the HAZ during welding, and these real-time observations of the HAZ phases were used to construct a map of the phase transformations occurring in the HAZ. This map identified 5 principal phase regions between the liquid weld pool and the unaffected base metal. Regions of annealing, recrystallization, partial transformation and complete transformation to {alpha}-Fe, {gamma}-Fe, and {delta}-Fe phases were identified using SRXRD, and the experimental results were combined with a heat flow model of the weld and thermodynamic calculations to compare these results with the important phase transformation isotherms. From the resulting phase transformation map, the kinetics of phase transformations that occur under the highly non-isothermal heating and cooling cycles produced during welding of steels can be better understood and modeled.

  3. Vein attribute scaling in strike-slip and extensional fault damage zones affecting the platform carbonates in the Jabal Qusaybah anticline, Salakh Arc, Oman

    NASA Astrophysics Data System (ADS)

    Clemenzi, Luca; Balsamo, Fabrizio; Storti, Fabrizio; Solum, John; Taberner, Conxita; Tueckmantel, Christian

    2015-04-01

    Understanding factors that determine deformation intensity and vein attributes in fault damage zones is important to predict fracture patterns and fault system permeability in the subsurface. In this contribution we present a new dataset on vein attributes collected along 26 fault zones (extensional and strike-slip) developed in the Cretaceous platform carbonates of the Natih Formation during the growth of the Jabal Qusaybah anticline, in the foreland basin of the Oman Mountains. Extensional and strike slip fault zones accommodated comparable displacements (~0.1 up to ~100 m), but were active at different burial depths. Extensional fault zones developed at shallow burial depth (<1-2 km) during late-stage folding and strike-slip faulting, and are laterally restricted by sub-vertical strike-slip fault zones. Vein aperture (A), eight (H), and spacing (S) were measured in vertical sections by scanlines across 10 strike-slip and 16 extensional fault damage zones, and then statistically analyzed. In both strike-slip and extensional fault damage zones vein aperture and height generally increase approaching the master slip surfaces, while vein spacing decreases approaching them. Deformation intensity, calculated as vein H/S ratio per meter, exponentially increases moving from background host rock toward master slip surfaces. Furthermore, the mean vein H/S ratio calculated in each damage zone increases also with increasing fault displacement in extensional fault zones, whereas it remain almost constant in strike-slip fault zones. Different vein pattern evolutions in the two fault systems are due to the presence of sub-vertical strike-slip fault zones which provided mechanical barriers that hindered the lateral propagation of extensional fault zones. During extensional faulting, the vertical downthrown was not inhibited, thus resulting in a progressively higher deformation intensity in laterally-restricted, extensional fault damage zones.

  4. Scattering Properties of Jovian Tropospheric Cloud Particles from Cassini/ISS: Mie Scattering Phase Function and Particle Size in the South Tropical Zone

    NASA Astrophysics Data System (ADS)

    Sato, Takao M.; Satoh, T.; Kasaba, Y.

    2010-10-01

    It is essential to know scattering properties (e.g., scattering phase function) of clouds for determination of vertical cloud structure. However, we cannot derive those from ground-based and Earth-orbit observations because of the limitation of solar phase angle as viewed from the Earth. Then, most previous studies have used the scattering phase function deduced from the Pioneer 10/IPP data (blue: 440 nm, red: 640nm) [Tomasko et al., 1978]. There are two shortcomings in the Pioneer scattering phase function. One is that we have to use this scattering phase function at red as a substitute for analyses of imaging photometry using CH4 bands (center: 727 and 890 nm), although clouds should have wavelength dependency. The other is that the red pass band of IPP was so broad (595-720 nm) that this scattering phase function in red just show wavelength-averaged scattering properties of clouds. To provide a new reference scattering phase function with wavelength dependency, we have analyzed the Cassini/ISS data in BL1 (451 nm), CB1 (619 nm), CB2 (750 nm), and CB3 (938 nm) over wide solar phase angles (3-141 degrees) during its Jovian flyby in 2000-2001. A simple cloud model which consists of a thin stratospheric haze, a semi-infinite cloud, and an intervening Rayleigh gas layers is adopted. Applying Mie theory to scattering by clouds, we deduce the scattering phase function of cloud and effective particle size in the South Tropical Zone. When we use the nominal value of reflective index for ammonia ice (Martonchik et al., 1984), we cannot obtain reasonable fit to the observed limb-darkening profiles. This would imply that we should consider possible effects on the impurity and/or the nonsphericiy of clouds. In this presentation, we will show detail model description and these results. Finally, we discuss scattering properties of clouds through comparison with previous works.

  5. Understanding the Fluvial Critical Zone

    NASA Astrophysics Data System (ADS)

    Bätz, N.; Lane, S. N.; Temme, A. J. A. M.; Lang, F.

    2012-04-01

    Geomorphological modelling has evolved significantly the representation of the link between river morphology, flow processes and sediment transport; notably recently, with an emphasis upon the interactions between vegetation dynamics and morphodynamics. Nevertheless, vegetation dynamics have tended to be treated as a simplistic "black box" in which time replaces the more complex underlying processes. Thus, riparian vegetation dynamics not only result from interactions between surface-flow, topography and vegetation resistance to disturbance, but also soil development within the fluvial zone, which affects nutrient and water supply. More generally labeled the critical zone, there is a lack of considering the "critical fluvial zone" in geomorphological models. Understanding the key drivers of this system, thus the processes interrelating vegetation, topography, soil (formation), subsurface- and surface-flow, are crucial to understand how riverine landscapes respond to increasing human pressure and to climate change. In this poster, we consider the likely nature of a braided river critical fluvial zone. Braided rivers in deglaciated forelands provide an opportunity to study the fluvial critical zone due to their dynamic properties, the restricted physical size, the simple ecosystems and the space-for-time relation caused by glacier retreatment after the "Little Ice Age". The poster aims to commence a discussion on the fluvial critical zone, showing first results about: a) the system understanding of a braided river set in a recently deglaciated alpine foreland; b) methodological approaches to quantify the identified interrelating key processes; c) how quantitative understanding can be integrated into fluvial geomorphological modelling.

  6. Genetic deletion of Rab27B in pancreatic acinar cells affects granules size and has inhibitory effects on amylase secretion.

    PubMed

    Hou, Yanan; Ernst, Stephen A; Lentz, Stephen I; Williams, John A

    2016-03-18

    Small G protein Rab27B is expressed in various secretory cell types and plays a role in mediating secretion. In pancreatic acinar cells, Rab27B was found to be expressed on the zymogen granule membrane and by overexpression to regulate the secretion of zymogen granules. However, the effect of Rab27B deletion on the physiology of pancreatic acinar cells is unknown. In the current study, we utilized the Rab27B KO mouse model to better understand the role of Rab27B in the secretion of pancreatic acinar cells. Our data show that Rab27B deficiency had no obvious effects on the expression of major digestive enzymes and other closely related proteins, e.g. similar small G proteins, such as Rab3D and Rab27A, and putative downstream effectors. The overall morphology of acinar cells was not changed in the knockout pancreas. However, the size of zymogen granules was decreased in KO acinar cells, suggesting a role of Rab27B in regulating the maturation of secretory granules. The secretion of digestive enzymes was moderately decreased in KO acini, compared with the WT control. These data indicate that Rab27B is involved at a different steps of zymogen granule maturation and secretion, which is distinct from that of Rab3D. PMID:26845357

  7. Biases in grant proposal success rates, funding rates and award sizes affect the geographical distribution of funding for biomedical research.

    PubMed

    Wahls, Wayne P

    2016-01-01

    The ability of the United States to most efficiently make breakthroughs on the biology, diagnosis and treatment of human diseases requires that physicians and scientists in each state have equal access to federal research grants and grant dollars. However, despite legislative and administrative efforts to ensure equal access, the majority of funding for biomedical research is concentrated in a minority of states. To gain insight into the causes of such disparity, funding metrics were examined for all NIH research project grants (RPGs) from 2004 to 2013. State-by-state differences in per application success rates, per investigator funding rates, and average award size each contributed significantly to vast disparities (greater than 100-fold range) in per capita RPG funding to individual states. To the extent tested, there was no significant association overall between scientific productivity and per capita funding, suggesting that the unbalanced allocation of funding is unrelated to the quality of scientists in each state. These findings reveal key sources of bias in, and new insight into the accuracy of, the funding process. They also support evidence-based recommendations for how the NIH could better utilize the scientific talent and capacity that is present throughout the United States. PMID:27077009

  8. Biases in grant proposal success rates, funding rates and award sizes affect the geographical distribution of funding for biomedical research

    PubMed Central

    2016-01-01

    The ability of the United States to most efficiently make breakthroughs on the biology, diagnosis and treatment of human diseases requires that physicians and scientists in each state have equal access to federal research grants and grant dollars. However, despite legislative and administrative efforts to ensure equal access, the majority of funding for biomedical research is concentrated in a minority of states. To gain insight into the causes of such disparity, funding metrics were examined for all NIH research project grants (RPGs) from 2004 to 2013. State-by-state differences in per application success rates, per investigator funding rates, and average award size each contributed significantly to vast disparities (greater than 100-fold range) in per capita RPG funding to individual states. To the extent tested, there was no significant association overall between scientific productivity and per capita funding, suggesting that the unbalanced allocation of funding is unrelated to the quality of scientists in each state. These findings reveal key sources of bias in, and new insight into the accuracy of, the funding process. They also support evidence-based recommendations for how the NIH could better utilize the scientific talent and capacity that is present throughout the United States. PMID:27077009

  9. How Do the Size, Charge and Shape of Nanoparticles Affect Amyloid β Aggregation on Brain Lipid Bilayer?

    PubMed

    Kim, Yuna; Park, Ji-Hyun; Lee, Hyojin; Nam, Jwa-Min

    2016-01-01

    Here, we studied the effect of the size, shape, and surface charge of Au nanoparticles (AuNPs) on amyloid beta (Aβ) aggregation on a total brain lipid-based supported lipid bilayer (brain SLB), a fluid platform that facilitates Aβ-AuNP aggregation process. We found that larger AuNPs induce large and amorphous aggregates on the brain SLB, whereas smaller AuNPs induce protofibrillar Aβ structures. Positively charged AuNPs were more strongly attracted to Aβ than negatively charged AuNPs, and the stronger interactions between AuNPs and Aβ resulted in fewer β-sheets and more random coil structures. We also compared spherical AuNPs, gold nanorods (AuNRs), and gold nanocubes (AuNCs) to study the effect of nanoparticle shape on Aβ aggregation on the brain SLB. Aβ was preferentially bound to the long axis of AuNRs and fewer fibrils were formed whereas all the facets of AuNCs interacted with Aβ to produce the fibril networks. Finally, it was revealed that different nanostructures induce different cytotoxicity on neuroblastoma cells, and, overall, smaller Aβ aggregates induce higher cytotoxicity. The results offer insight into the roles of NPs and brain SLB in Aβ aggregation on the cell membrane and can facilitate the understanding of Aβ-nanostructure co-aggregation mechanism and tuning Aβ aggregate structures. PMID:26782664

  10. How Do the Size, Charge and Shape of Nanoparticles Affect Amyloid β Aggregation on Brain Lipid Bilayer?

    NASA Astrophysics Data System (ADS)

    Kim, Yuna; Park, Ji-Hyun; Lee, Hyojin; Nam, Jwa-Min

    2016-01-01

    Here, we studied the effect of the size, shape, and surface charge of Au nanoparticles (AuNPs) on amyloid beta (Aβ) aggregation on a total brain lipid-based supported lipid bilayer (brain SLB), a fluid platform that facilitates Aβ-AuNP aggregation process. We found that larger AuNPs induce large and amorphous aggregates on the brain SLB, whereas smaller AuNPs induce protofibrillar Aβ structures. Positively charged AuNPs were more strongly attracted to Aβ than negatively charged AuNPs, and the stronger interactions between AuNPs and Aβ resulted in fewer β-sheets and more random coil structures. We also compared spherical AuNPs, gold nanorods (AuNRs), and gold nanocubes (AuNCs) to study the effect of nanoparticle shape on Aβ aggregation on the brain SLB. Aβ was preferentially bound to the long axis of AuNRs and fewer fibrils were formed whereas all the facets of AuNCs interacted with Aβ to produce the fibril networks. Finally, it was revealed that different nanostructures induce different cytotoxicity on neuroblastoma cells, and, overall, smaller Aβ aggregates induce higher cytotoxicity. The results offer insight into the roles of NPs and brain SLB in Aβ aggregation on the cell membrane and can facilitate the understanding of Aβ-nanostructure co-aggregation mechanism and tuning Aβ aggregate structures.

  11. The grape berry-specific basic helix–loop–helix transcription factor VvCEB1 affects cell size

    PubMed Central

    Lecourieux, Fatma

    2013-01-01

    The development of fleshy fruits involves complex physiological and biochemical changes. After fertilization, fruit growth usually begins with cell division, continues with both cell division and expansion, allowing fruit set to occur, and ends with cell expansion only. In spite of the economical importance of grapevine, the molecular mechanisms controlling berry growth are not fully understood. The present work identified and characterized Vitis vinifera cell elongation bHLH protein (VvCEB1), a basic helix–loop–helix (bHLH) transcription factor controlling cell expansion in grape. VvCEB1 was expressed specifically in berry-expanding tissues with a maximum around veraison. The study of VvCEB1 promoter activity in tomato confirmed its specific fruit expression during the expansion phase. Overexpression of VvCEB1 in grape embryos showed that this protein stimulates cell expansion and affects the expression of genes involved in cell expansion, including genes of auxin metabolism and signalling. Taken together, these data show that VvCEB1 is a fruit-specific bHLH transcription factor involved in grape berry development. PMID:23314819

  12. Intrauterine infusion of latency-associated peptide (LAP) during early porcine pregnancy affects conceptus elongation and placental size.

    PubMed

    Massuto, Dana A; Hooper, R Neil; Kneese, Eric C; Johnson, Greg A; Ing, Nancy H; Weeks, Bradley R; Jaeger, Laurie A

    2010-03-01

    In the pig, transforming growth factor beta (TGFB), TGFB receptors (TGFBRs), and integrins are present during the peri-implantation period. Latency-associated peptide (LAP), a part of latent TGFB, can bind to integrin heterodimers via its Arg-Gly-Asp (RGD) sequence; therefore, ligand-receptor interactions between TGFB and TGFBRs, along with LAP and integrin heterodimers, may be functional in mediating events supporting conceptus elongation and attachment. With the use of surgically implantable osmotic pumps, we were able to maintain pregnancy with the aim of mechanistically altering in vivo receptor-ligand interactions involving TGFB with TGFBRs and LAP with integrins during porcine pregnancy. Day 9 pregnant gilts received intrauterine infusions of LAP-RGD, a recombinant mutant of LAP (LAP-RGE), or vehicle control and were ovariohysterectomized on Day 13 or 24 of pregnancy. We hypothesized that intrauterine infusion of LAP-RGD would decrease downstream signaling of TGFB while increasing LAP-integrin interactions and that net effect would enhance conceptus survival and attachment early in the peri-implantation period but possibly increase the chance of abnormal placentation later in pregnancy. Additionally, we hypothesized that infusion of LAP-RGE would disrupt TGFB signals but not alter integrin signaling, and thus the net result would be decreased conceptus survival and abnormal development. Unexpectedly, LAP-RGD intrauterine infusions resulted in a reduction of conceptus elongation, whereas infusions of LAP-RGE permitted implantation and placentation but resulted in larger fetal weight, allantois length, and allantoic fluid volume. Results suggest TGFB and integrins are contributing factors in the regulation of conceptus elongation and placental and fetal size. PMID:19906685

  13. Spider Movement, UV Reflectance and Size, but Not Spider Crypsis, Affect the Response of Honeybees to Australian Crab Spiders

    PubMed Central

    Llandres, Ana L.; Rodríguez-Gironés, Miguel A.

    2011-01-01

    According to the crypsis hypothesis, the ability of female crab spiders to change body colour and match the colour of flowers has been selected because flower visitors are less likely to detect spiders that match the colour of the flowers used as hunting platform. However, recent findings suggest that spider crypsis plays a minor role in predator detection and some studies even showed that pollinators can become attracted to flowers harbouring Australian crab spider when the UV contrast between spider and flower increases. Here we studied the response of Apis mellifera honeybees to the presence of white or yellow Thomisus spectabilis Australian crab spiders sitting on Bidens alba inflorescences and also the response of honeybees to crab spiders that we made easily detectable painting blue their forelimbs or abdomen. To account for the visual systems of crab spider's prey, we measured the reflectance properties of the spiders and inflorescences used for the experiments. We found that honeybees did not respond to the degree of matching between spiders and inflorescences (either chromatic or achromatic contrast): they responded similarly to white and yellow spiders, to control and painted spiders. However spider UV reflection, spider size and spider movement determined honeybee behaviour: the probability that honeybees landed on spider-harbouring inflorescences was greatest when the spiders were large and had high UV reflectance or when spiders were small and reflected little UV, and honeybees were more likely to reject inflorescences if spiders moved as the bee approached the inflorescence. Our study suggests that only the large, but not the small Australian crab spiders deceive their preys by reflecting UV light, and highlights the importance of other cues that elicited an anti-predator response in honeybees. PMID:21359183

  14. Analysis of candidate genes underlying two epistatic quantitative trait loci on SSC12 affecting litter size in pig.

    PubMed

    Fernández-Rodríguez, A; Rodríguez, C; Varona, L; Balcells, I; Noguera, J L; Ovilo, C; Fernández, A I

    2010-02-01

    The previous results from a genome scan for total number of piglets born and number of piglets born alive in a F(2) Iberian by Meishan intercross showed several single and epistatic QTL. One of the most interesting results was obtained for SSC12, where two QTL affecting both traits showed epistatic interaction. In this study, we proposed two genes (SLC9A3R1 and NOS2) as biological and potentially positional candidates underlying these QTL. Both cDNAs were characterized and 23 polymorphisms were detected. A chromosome scan was conducted with 12 markers, plus one SNP in SLC9A3R1 and one in NOS2, covering 110 cM of SSC12. The epistatic QTL (QTL1 at 15 cM and QTL2 at 97 cM) were confirmed, and SLC9A3R1 and NOS2 were mapped around the QTL1 and QTL2 regions respectively. Several SNPs in both genes were tested with standard animal model and marker assisted association tests. The most significant results were obtained with the NOS2 haplotype defined by one missense SNP c.2192C > T (Val to Ala) and a 15 bp duplication at the 3'UTR. This duplication seems to include AU-rich elements, and could be a target site for miRNA, therefore there are statistical and biological indications to consider this haplotype as the potential causal mutation underlying QTL2. SLC9A3R1 results were not conclusive. Although the interaction between the SNPs was not significant, we cannot reject the possibility of interaction of the NOS2 haplotype with other polymorphisms closely linked to the SL9A3R1 SNPs analysed. PMID:19793269

  15. Population Structure, Genetic Diversity, Effective Population Size, Demographic History and Regional Connectivity Patterns of the Endangered Dusky Grouper, Epinephelus marginatus (Teleostei: Serranidae), within Malta’s Fisheries Management Zone

    PubMed Central

    Vella, Adriana

    2016-01-01

    The objective of this study is to describe the genetic population structure and demographic history of the endangered marine fish, Epinephelus marginatus, within Malta’s Fisheries Management Zone for the purpose of localised conservation planning. Epinephelus marginatus is a long-lived, sedentary, reef-associated protogynous hermaphrodite with high commercial and recreational value that is at risk of extinction throughout its global distribution. Based on global trends, population substructuring and gaps in local knowledge this has led to an increased interest in evaluation of local stock. Assessment of Maltese demography was based on historical and contemporary catch landings data whilst genetic population structure and regional connectivity patterns were evaluated by examining 175 individuals collected within the central Mediterranean region between 2002 and 2009 using 14 nuclear microsatellite loci. Demographic stock assessment of Maltese E. marginatus’ revealed a 99% decline in catch landings between 1947 and 2009 within the Fisheries Management Zone. A contemporary modest mean size was observed, 3 ± 3 kg, where approximately 17% of the population was juvenile, 68% female/sex-changing and 15% were male with a male-to-female sex ratio of 1:5. Genetic analysis describes the overall population of E. marginatus’ within the Fisheries Management Zone as decreasing in size (ƟH = 2.2), which has gone through a significant size reduction in the past (M = 0.41) and consequently shows signs of moderate inbreeding (FIS = 0.10, p < 0.001) with an estimated effective population size of 130 individuals. Results of spatially explicit Bayesian genetic cluster analysis detected two geographically distinct subpopulations within Malta’s Fisheries Management Zone and that they are connected to a larger network of E. marginatus’ within the Sicily Channel. Results suggest conservation management should be designed to reflect E. marginatus’ within Malta’s Fisheries

  16. Can Supersaturation Affect Protein Crystal Quality?

    NASA Technical Reports Server (NTRS)

    Gorti, Sridhar

    2013-01-01

    In quiescent environments (microgravity, capillary tubes, gels) formation of a depletion zone is to be expected, due either to limited sedimentation, density driven convection or a combination of both. The formation of a depletion zone can: Modify solution supersaturation near crystal; Give rise to impurity partitioning. It is conjectured that both supersaturation and impurity partitioning affect protein crystal quality and size. Further detailed investigations on various proteins are needed to assess above hypothesis.

  17. Effects of Oxides on Tensile and Charpy Impact Properties and Fracture Toughness in Heat Affected Zones of Oxide-Containing API X80 Linepipe Steels

    NASA Astrophysics Data System (ADS)

    Sung, Hyo Kyung; Sohn, Seok Su; Shin, Sang Yong; Oh, Kyung Shik; Lee, Sunghak

    2014-06-01

    This study is concerned with effects of complex oxides on acicular ferrite (AF) formation, tensile and Charpy impact properties, and fracture toughness in heat affected zones (HAZs) of oxide-containing API X80 linepipe steels. Three steels were fabricated by adding Mg and O2 to form oxides, and various HAZ microstructures were obtained by conducting HAZ simulation tests under different heat inputs. The no. of oxides increased with increasing amount of Mg and O2, while the volume fraction of AF present in the steel HAZs increased with increasing the no. of oxides. The strengths of the HAZ specimens were generally higher than those of the base metals because of the formation of hard microstructures of bainitic ferrite and granular bainite. When the total Charpy absorbed energy was divided into the fracture initiation and propagation energies, the fracture initiation energy was maintained constant at about 75 J at room temperature, irrespective of volume fraction of AF. The fracture propagation energy rapidly increased from 75 to 150 J and saturated when the volume fraction of AF exceeded 30 pct. At 253 K (-20 °C), the total absorbed energy increased with increasing volume fraction of AF, as the cleavage fracture was changed to the ductile fracture when the volume fraction of AF exceeded 45 pct. Thus, 45 vol pct of AF at least was needed to improve the Charpy impact energy, which could be achieved by forming a no. of oxides. The fracture toughness increased with increasing the no. of oxides because of the increased volume fraction of AF formed around oxides. The fracture toughness did not show a visible correlation with the Charpy absorbed energy at room temperature, because toughness properties obtained from these two toughness testing methods had different significations in view of fracture mechanics.

  18. On the development of a new pre-weld thermal treatment procedure for preventing heat-affected zone (HAZ) liquation cracking in nickel-base IN 738 superalloy

    NASA Astrophysics Data System (ADS)

    Ola, O. T.; Ojo, O. A.; Chaturvedi, M. C.

    2014-10-01

    Hot cracking in the heat-affected zone (HAZ) of precipitation strengthened nickel-base superalloys, such as IN 738, during fusion welding remains a major factor limiting reparability of nickel-base gas turbine components. The problem of HAZ intergranular cracking can be addressed by modifying the microstructure of the pre-weld material through thermal treatment, which requires significant understanding of the critical factors controlling cracking behaviour. The decomposition of Mo-Cr-W-and Cr-rich borides in the alloy, among other factors, has been observed to contribute significantly to non-equilibrium intergranular liquation and, hence, intergranular liquation cracking during welding. Gleeble physical simulation of HAZ microstructure has also shown that non-equilibrium liquation is more severe in the vicinity of decomposed borides in the alloy and can occur at temperatures as low as 1,150 °C. Although currently existing pre-weld heat treatments for IN 738 superalloy minimize the contributions of dissolution of second phases, including borides, to HAZ intergranular liquation, these heat treatments are not industrially feasible due to process-related difficulties. Therefore, a new industrially feasible and effective pre-weld thermal treatment process, designated as FUMT, was developed during the present research by controlling both the formation of borides and the segregation of boron at the grain boundaries in the pre-weld heat-treated material. This thermal treatment was observed to very significantly reduce intergranular HAZ cracking in welded IN 738 superalloy. The details of the development process and developed procedure are presented in this paper.

  19. Uterine Artery Embolization in 101 Cases of Uterine Fibroids: Do Size, Location, and Number of Fibroids Affect Therapeutic Success and Complications?

    SciTech Connect

    Firouznia, Kavous Ghanaati, Hossein; Jalali, Amir H.; Shakiba, Madjid

    2008-05-15

    The purpose of this study was to evaluate whether the size, location, or number of fibroids affects therapeutic efficacy or complications of uterine artery embolization (UAE). Patients with symptomatic uterine fibroids (n = 101) were treated by selective bilateral UAE using 500- to 710-{mu}m polyvinyl alcohol (PVA) particles. Baseline measures of clinical symptoms, sonography, and MRI taken before the procedure were compared to those taken 1, 3, 6, and 12 months later. Complications and outcomes were analyzed for associations with fibroid size, location, and number. Reductions in mean fibroid volume were similar in patients with single (66.6 {+-} 21.5%) and multiple (67.4 {+-} 25.0%) fibroids (p-value = 0.83). Menstrual improvement occurred in patients with single (93.3%) and multiple (72.2%) fibroids (p = 0.18). Changes in submucosal and other fibroids were not significantly different between the two groups (p's > 0.56). Linear regression analysis between primary fibroid volume as independent variable and percentage reduction of fibroid volume after 1 year yielded an R{sup 2} of 0.083 and the model coefficient was not statistically significant (p = 0.072). Multivariate regression models revealed no statistically or clinically significant coefficients or odds ratios for three independent variables (primary fibroid size, total number, and fibroid location) and all outcome variables (percent reduction of uterus and fibroid volumes in 1 year, improvement of clinical symptoms [menstrual, bulk related, and urinary] in 1 year, and complications after UAE). In conclusion, neither the success rate nor the probability of complications was affected by the primary fibroid size, location, or total number of fibroids.

  20. Urban field classification by "local climate zones" in a medium-sized Central European city: the case of Olomouc (Czech Republic)

    NASA Astrophysics Data System (ADS)

    Lehnert, Michal; Geletič, Jan; Husák, Jan; Vysoudil, Miroslav

    2015-11-01

    The stations of the Metropolitan Station Network in Olomouc (Czech Republic) were assigned to local climatic zones, and the temperature characteristics of the stations were compared. The classification of local climatic zones represents an up-to-date concept for the unification of the characterization of the neighborhoods of climate research sites. This study is one of the first to provide a classification of existing stations within local climate zones. Using a combination of GIS-based analyses and field research, the values of geometric and surface cover properties were calculated, and the stations were subsequently classified into the local climate zones. It turned out that the classification of local climatic zones can be efficiently used for representative documentation of the neighborhood of the climate stations. To achieve a full standardization of the description of the neighborhood of a station, the classification procedures, including the methods used for the processing of spatial data and methods used for the indication of specific local characteristics, must be also standardized. Although the main patterns of temperature differences between the stations with a compact rise, those with an open rise and the stations with no rise or sparsely built areas were evident; the air temperature also showed considerable differences within particular zones. These differences were largely caused by various geometric layout of development and by unstandardized placement of the stations. For the direct comparison of temperatures between zones, particularly those stations which have been placed in such a way that they are as representative as possible for the zone in question should be used in further research.

  1. Extensional Failure of "Pre-Stressed" Lithosphere Above a Subduction Zone May Have Contributed to the Size of the Tohoku-Oki Earthquake and Tsunami

    NASA Astrophysics Data System (ADS)

    Buck, W. R.; Lavier, L. L.; Petersen, K. D.

    2015-12-01

    The Tohoku-oki earthquake was not only the costliest natural disaster in history it was the best monitored. The unprecedented data set showed that anomalously large lateral motion of the seafloor near the trench contributed to the size of the tsunami. Also, for the first time it was shown that a large subduction earthquake was followed by extensional aftershocks in a broad region of the upper plate (up to 250 km from the Japan Trench). Several observations suggest that the near-trench seafloor motion and the extensional aftershocks are linked. For example, a seismically imaged fault, just landward of the region of large seafloor motion, slipped in a normal sense during the earthquake. Also, inspired by the Tohoku data, researchers have searched for and found upper plate extensional aftershocks associated with several other subduction earthquakes that produced large tsunami. Extension of the upper plate can be driven by a reduction in the dip of a subducting slab. Such a dip change is suggested by the post-Miocene westward migration of the volcanic arc in Honshu. Numerical models show that a long-term reduction in slab dip can generate enough extensional stress to cause normal faulting over a broad region of the upper plate. The time step of the numerical model is then reduced to treat the inter-seismic time scale of 100-1000 years, when the subduction interface is locked. The interface dip continues to be reduced during the inter-seismic period, but extensional fault slip is suppressed by the relative compression of the upper plate caused by continued convergence. The relief of compressional stresses during dynamic weakening of the megathrust triggers a release of bending-related extensional strain energy. This extensional yielding can add significantly to the co-seismic radiated seismic energy and seafloor deformation. This mechanism is analogous to the breaking of a pre-stressed concrete beam supporting a bending moment when the compressional pre-stress is

  2. Did the late spring frost in 2007 and 2011 affect tree-ring width and earlywood vessel size in Pedunculate oak (Quercus robur) in northern Poland?

    NASA Astrophysics Data System (ADS)

    Puchałka, Radosław; Koprowski, Marcin; Przybylak, Julia; Przybylak, Rajmund; Dąbrowski, Henryk P.

    2015-11-01

    Trees are sensitive to extreme weather and environmental conditions. This sensitivity is visible in tree-ring widths and cell structure. In our study, we hypothesized that the sudden frost noted at the beginning of May in both 2007 and 2011 affected cambial activity and, consequently, the number and size of vessels in the tree rings. It was decided to test this hypothesis after damage to leaves was observed. The applied response function model did not show any significant relationships between spring temperature and growth. However, this method uses average values for long periods and sometimes misses the short-term effects. This is why we decided to study each ring separately, comparing them with rings unaffected by the late frost. Our study showed that the short-term effect of sudden frost in late spring did not affect tree rings and selected cell parameters. The most likely reasons for this are (i) cambial activity producing the earlywood vessels before the occurrence of the observed leaf damage, (ii) the forest micro-climate protecting the trees from the harsh frost and (iii) the temperature decline being too short-lived an event to affect the oaks. On the other hand, the visible damage may be occasional and not affect cambium activity and tree vitality at all. We conclude that oak is well-adapted to this phenomenon.

  3. Did the late spring frost in 2007 and 2011 affect tree-ring width and earlywood vessel size in Pedunculate oak (Quercus robur) in northern Poland?

    PubMed

    Puchałka, Radosław; Koprowski, Marcin; Przybylak, Julia; Przybylak, Rajmund; Dąbrowski, Henryk P

    2016-08-01

    Trees are sensitive to extreme weather and environmental conditions. This sensitivity is visible in tree-ring widths and cell structure. In our study, we hypothesized that the sudden frost noted at the beginning of May in both 2007 and 2011 affected cambial activity and, consequently, the number and size of vessels in the tree rings. It was decided to test this hypothesis after damage to leaves was observed. The applied response function model did not show any significant relationships between spring temperature and growth. However, this method uses average values for long periods and sometimes misses the short-term effects. This is why we decided to study each ring separately, comparing them with rings unaffected by the late frost. Our study showed that the short-term effect of sudden frost in late spring did not affect tree rings and selected cell parameters. The most likely reasons for this are (i) cambial activity producing the earlywood vessels before the occurrence of the observed leaf damage, (ii) the forest micro-climate protecting the trees from the harsh frost and (iii) the temperature decline being too short-lived an event to affect the oaks. On the other hand, the visible damage may be occasional and not affect cambium activity and tree vitality at all. We conclude that oak is well-adapted to this phenomenon. PMID:26607274

  4. Did the late spring frost in 2007 and 2011 affect tree-ring width and earlywood vessel size in Pedunculate oak ( Quercus robur) in northern Poland?

    NASA Astrophysics Data System (ADS)

    Puchałka, Radosław; Koprowski, Marcin; Przybylak, Julia; Przybylak, Rajmund; Dąbrowski, Henryk P.

    2016-08-01

    Trees are sensitive to extreme weather and environmental conditions. This sensitivity is visible in tree-ring widths and cell structure. In our study, we hypothesized that the sudden frost noted at the beginning of May in both 2007 and 2011 affected cambial activity and, consequently, the number and size of vessels in the tree rings. It was decided to test this hypothesis after damage to leaves was observed. The applied response function model did not show any significant relationships between spring temperature and growth. However, this method uses average values for long periods and sometimes misses the short-term effects. This is why we decided to study each ring separately, comparing them with rings unaffected by the late frost. Our study showed that the short-term effect of sudden frost in late spring did not affect tree rings and selected cell parameters. The most likely reasons for this are (i) cambial activity producing the earlywood vessels before the occurrence of the observed leaf damage, (ii) the forest micro-climate protecting the trees from the harsh frost and (iii) the temperature decline being too short-lived an event to affect the oaks. On the other hand, the visible damage may be occasional and not affect cambium activity and tree vitality at all. We conclude that oak is well-adapted to this phenomenon.

  5. The Size of Activating and Inhibitory Killer Ig-like Receptor Nanoclusters Is Controlled by the Transmembrane Sequence and Affects Signaling.

    PubMed

    Oszmiana, Anna; Williamson, David J; Cordoba, Shaun-Paul; Morgan, David J; Kennedy, Philippa R; Stacey, Kevin; Davis, Daniel M

    2016-05-31

    Super-resolution microscopy has revealed that immune cell receptors are organized in nanoscale clusters at cell surfaces and immune synapses. However, mechanisms and functions for this nanoscale organization remain unclear. Here, we used super-resolution microscopy to compare the surface organization of paired killer Ig-like receptors (KIR), KIR2DL1 and KIR2DS1, on human primary natural killer cells and cell lines. Activating KIR2DS1 assembled in clusters two-fold larger than its inhibitory counterpart KIR2DL1. Site-directed mutagenesis established that the size of nanoclusters is controlled by transmembrane amino acid 233, a lysine in KIR2DS1. Super-resolution microscopy also revealed two ways in which the nanoscale clustering of KIR affects signaling. First, KIR2DS1 and DAP12 nanoclusters are juxtaposed in the resting cell state but coalesce upon receptor ligation. Second, quantitative super-resolution microscopy revealed that phosphorylation of the kinase ZAP-70 or phosphatase SHP-1 is favored in larger KIR nanoclusters. Thus, the size of KIR nanoclusters depends on the transmembrane sequence and affects downstream signaling. PMID:27210755

  6. Microstructural Evolution and Mechanical Properties of Fusion Welds and Simulated Heat-Affected Zones in an Iron-Copper Based Multi-Component Steel

    NASA Astrophysics Data System (ADS)

    Farren, Jeffrey David

    NUCu-140 is a copper-precipitation strengthened steel that exhibits excellent mechanical properties with a relatively simple chemical composition and processing schedule. As a result, NUCu-140 is a candidate material for use in many naval and structural applications. Before NUCu-140 can be implemented as a replacement for currently utilized materials, a comprehensive welding strategy must be developed under a wide range of welding conditions. This research represents an initial step toward understanding the microstructural and mechanical property evolution that occurs during fusion welding of NUCu-140. The following dissertation is presented as a series of four chapters. Chapter one is a review of the relevant literature on the iron-copper system including the precipitation of copper in steel, the development of the NUCu family of alloys, and the formation of acicular ferrite in steel weldments. Chapter two is a detailed study of the precipitate, microstructural, and mechanical property evolution of NUCu-140 fusion welds. Microhardness testing, tensile testing, local-electrode atom probe (LEAP) tomography, MatCalc kinetic simulations, and Russell-Brown strengthening results for gas-tungsten and gas-metal arc welds are presented. Chapter three is a thorough study of the microstructural and mechanical property evolution that occurs in the four critical regions of the HAZ. Simulated HAZ specimens were produced and evaluated using microhardness, tensile testing, and charpy impact testing. MatCalc simulations and R-B strengthening calculations were also performed in an effort to model the experimentally observed mechanical property trends. Chapter 4 is a brief investigation into the capabilities of MatCalc and the R-B model to determine if the two techniques could be used as predictive tools for a series of binary iron-copper alloys without the aid of experimentally measured precipitate data. The mechanical property results show that local softening occurs in the heat-affected

  7. Development of embrittlement prediction models for U.S. power reactors and the impact of the heat-affected zone to thermal annealing

    SciTech Connect

    Wang, J.A.

    1998-05-01

    The NRC Regulatory Guide 1.99 Revision 2 was based on 177 surveillance data points and the EPRI data base, where 76% of 177 data points and 60% of EPRI data base were from Westinghouse`s data. Therefore, other vendors` radiation environment may not be properly characterized by R.G. 1.99`s prediction. To minimize scatter from the influences of the irradiation temperature, neutron energy spectrum, displacement rate, and plant operation procedures on embrittlement models, improved embrittlement models based on group data that have similar radiation environments and reactor design and operation criteria are examined. A total of 653 shift data points from the current FR-EDB, including 397 Westinghouse data, 93 B and W data, 37 CE data, and 106 GE data, are used. A nonlinear least squares fitting FORTRAN program, incorporating a Monte Carlo procedure with 35% and 10% uncertainty assigned to the fluence and shift data, respectively, was written for this study. In order to have the same adjusted fluence value for the weld and plate material in the same capsule, the Monte Carlo least squares fitting procedure has the ability to adjust the fluence values while running the weld and plate formula simultaneously. Six chemical components, namely, copper, nickel, phosphorus, sulfur, manganese, and molybdenum, were considered in the development of the new embrittlement models. The overall percentage of reduction of the 2-sigma margins per delta RTNDT predicted by the new embrittlement models, compared to that of R.G. 1.99, for weld and base materials are 42% and 36%, respectively. Currently, the need for thermal annealing is seriously being considered for several A302B type RPVs. From the macroscopic view point, even if base and weld materials were verified from mechanical tests to be fully recovered, the linking heat affected zone (HAZ) material has not been properly characterized. Thus the final overall recovery will still be unknown. The great data scatter of the HAZ metals may

  8. Direct Observations of the (Alpha to Gamma) Transformation at Different Input Powers in the Heat Affected Zone of 1045 C-Mn Steel Arc Welds Observed by Spatially Resolved X-Ray Diffraction

    SciTech Connect

    Palmer, T A; Elmer, J W

    2005-03-16

    Spatially Resolved X-Ray Diffraction (SRXRD) experiments have been performed during Gas Tungsten Arc (GTA) welding of AISI 1045 C-Mn steel at input powers ranging from 1000 W to 3750 W. In situ diffraction patterns taken at discreet locations across the width of the heat affected zone (HAZ) near the peak of the heating cycle in each weld show regions containing austenite ({gamma}), ferrite and austenite ({alpha}+{gamma}), and ferrite ({alpha}). Changes in input power have a demonstrated effect on the resulting sizes of these regions. The largest effect is on the {gamma} phase region, which nearly triples in width with increasing input power, while the width of the surrounding two phase {alpha}+{gamma} region remains relatively constant. An analysis of the diffraction patterns obtained across this range of locations allows the formation of austenite from the base metal microstructure to be monitored. After the completion of the {alpha} {yields} {gamma} transformation, a splitting of the austenite peaks is observed at temperatures between approximately 860 C and 1290 C. This splitting in the austenite peaks results from the dissolution of cementite laths originally present in the base metal pearlite, which remain after the completion of the {alpha} {yields} {gamma} transformation, and represents the formation of a second more highly alloyed austenite constituent. With increasing temperatures, carbon, originally present in the cementite laths, diffuses from the second newly formed austenite constituent to the original austenite constituent. Eventually, a homogeneous austenitic microstructure is produced at temperatures of approximately 1300 C and above, depending on the weld input power.

  9. Scattering Properties of Jovian Tropospheric Cloud Particles Inferred from Cassini/ISS: Mie Scattering Phase Function and Particle Size in South Tropical Zone III

    NASA Astrophysics Data System (ADS)

    Sato, T.; Satoh, T.; Kasaba, Y.

    2010-12-01

    nm), CB2 (750 nm), and CB3 (938 nm) over wide solar phase angles (3-141 degrees) during its Jovian flyby in 2000-2001. A simple cloud model which consists of a thin stratospheric haze, a semi-infinite cloud, and an intervening Rayleigh gas layers is adopted. Applying Mie theory to scattering by clouds, we deduce the scattering phase function of cloud and effective particle size in the South Tropical Zone. When we use the nominal value of reflective index for ammonia ice (Martonchik et al., 1984), we cannot obtain reasonable fit to the observed limb-darkening profiles. This would imply that we should consider possible effects on the impurity and/or the nonsphericiy of clouds. In this presentation, we will show detail model description and these results. Finally, we discuss scattering properties of clouds through comparison with previous works.

  10. Microgravity silicon zoning investigation

    NASA Technical Reports Server (NTRS)

    Kern, E. L.; Gill, G. L., Jr.

    1983-01-01

    A resistance heated zoner, suitable for early zoning experiments with silicon, was designed and put into operation. The initial power usage and size was designed for an shown to be compatible with payload carriers contemplated for the Shuttle. This equipment will be used in the definition and development of flight experiments and apparatus for float zoning silicon and other materials in microgravity.

  11. Seasonal and size-related variation of subcellular biomarkers in quagga mussels (Dreissena bugensis) inhabiting sites affected by moderate contamination with complex mixtures of pollutants.

    PubMed

    Ács, A; Vehovszky, Á; Győri, J; Farkas, A

    2016-07-01

    The size-related differences in subcellular biomarker responses were assessed in Dreissena bugensis mussels inhabiting harbours moderately affected by pollution with complex mixtures of heavy metals and polycyclic aromatic hydrocarbons (PAHs). Adult D. bugensis samples were collected from three harbours of Lake Balaton (Hungary) characterized by moderate shipping activity, and as reference site, from a highly protected remote area of the lake. Biomarkers of exposure (metallothioneins (MTs), ethoxyresorufin-o-deethylase (EROD)), oxidative stress (lipid peroxidation (LPO), DNA strand breaks (DNAsb)) and possible endocrine disruption (vitellogenin-like proteins (VTG)) were analysed in whole-tissue homogenates of differently sized groups of mussels in relation to environmental parameters and priority pollutants (heavy metals and polycyclic aromatic hydrocarbons). Integrated biomarker response (IBR) indices were calculated for biomarker responses gained through in situ measurements to signalize critical sites and to better distinguish natural tendencies from biological effects of contaminants. Biomarker responses showed close positive correlation in case of MT, EROD, LPO, and DNAsb and negative correlation with VTG levels with mussel shell length in autumn, when higher levels of biomarkers appeared, possibly due to natural lifecycle changes of animals. PMID:27329477

  12. Overexpression of PhEXPA1 increases cell size, modifies cell wall polymer composition and affects the timing of axillary meristem development in Petunia hybrida.

    PubMed

    Zenoni, Sara; Fasoli, Marianna; Tornielli, Giovanni Battista; Dal Santo, Silvia; Sanson, Andrea; de Groot, Peter; Sordo, Sara; Citterio, Sandra; Monti, Francesca; Pezzotti, Mario

    2011-08-01

    • Expansins are cell wall proteins required for cell enlargement and cell wall loosening during many developmental processes. The involvement of the Petunia hybrida expansin A1 (PhEXPA1) gene in cell expansion, the control of organ size and cell wall polysaccharide composition was investigated by overexpressing PhEXPA1 in petunia plants. • PhEXPA1 promoter activity was evaluated using a promoter-GUS assay and the protein's subcellular localization was established by expressing a PhEXPA1-GFP fusion protein. PhEXPA1 was overexpressed in transgenic plants using the cauliflower mosaic virus (CaMV) 35S promoter. Fourier transform infrared (FTIR) and chemical analysis were used for the quantitative analysis of cell wall polymers. • The GUS and GFP assays demonstrated that PhEXPA1 is present in the cell walls of expanding tissues. The constitutive overexpression of PhEXPA1 significantly affected expansin activity and organ size, leading to changes in the architecture of petunia plants by initiating premature axillary meristem outgrowth. Moreover, a significant change in cell wall polymer composition in the petal limbs of transgenic plants was observed. • These results support a role for expansins in the determination of organ shape, in lateral branching, and in the variation of cell wall polymer composition, probably reflecting a complex role in cell wall metabolism. PMID:21534969

  13. Does Choice of Head Size and Neck Geometry Affect Stem Migration in Modular Large-Diameter Metal-on-Metal Total Hip Arthroplasty? A Preliminary Analysis

    PubMed Central

    Georgiou, CS; Evangelou, KG; Theodorou, EG; Provatidis, CG; Megas, PD

    2012-01-01

    Due to their theoretical advantages, hip systems combining modular necks and large diameter femoral heads have gradually gained popularity. However, among others, concerns regarding changes in the load transfer patterns were raised. Recent stress analyses have indeed shown that the use of modular necks and big femoral heads causes significant changes in the strain distribution along the femur. Our original hypothesis was that these changes may affect early distal migration of a modular stem. We examined the effect of head diameter and neck geometry on migration at two years of follow-up in a case series of 116 patients (125 hips), who have undergone primary Metal-on-Metal total hip arthroplasty with the modular grit-blasted Profemur®E stem combined with large-diameter heads (>36 mm). We found that choice of neck geometry and head diameter has no effect on stem migration. A multivariate regression analysis including the potential confounding variables of the body mass index, bone quality, canal fill and stem positioning revealed only a negative correlation between subsidence and canal fill in midstem area. Statistical analysis, despite its limitations, did not confirm our hypothesis that choice of neck geometry and/or head diameter affects early distal migration of a modular stem. However, the importance of correct stem sizing was revealed. PMID:23284597

  14. Low pH affects survival, growth, size distribution, and carapace quality of the postlarvae and early juveniles of the freshwater prawn Macrobrachium rosenbergii de Man

    NASA Astrophysics Data System (ADS)

    Kawamura, Gunzo; Bagarinao, Teodora; Yong, Annita Seok Kian; Chen, Chiau Yu; Noor, Siti Norasidah Mat; Lim, Leong Seng

    2015-06-01

    Acidification of rain water caused by air pollutants is now recognized as a serious threat to aquatic ecosystems. We examined the effects of low pH (control pH 7.5, pH 6, pH 5, pH 4) on the survival, growth, and shell quality of Macrobrachium rosenbergii postlarvae and early juveniles in the laboratory. Hatcheryproduced postlarvae (PL 5) were stocked at 250 PL per aquarium, acclimated over 7 d to experimental pH adjusted with hydrochloric acid, and reared for 30 d. Dead specimens were removed and counted twice a day. After 27 d rearing, all specimens were measured for total length and body weight. Carapace quality was assessed by spectrophotometry. Survival of juveniles was highest at pH 6 (binomial 95% confidence interval 79 - 89%) followed by control pH 7.5 (56 - 68%) and pH 5 (50 - 60%) and was lowest for unmetamorphosed postlarvae and juveniles at pH 4 (43 - 49%). The final median total length and body weight of juveniles were similar at control pH 7.5 (18.2 TL, 50.2 mg BW) and pH 6 (17.7 mm TL, 45.0 mg BW) but significantly less at pH 5 (16.7 mm TL, 38.2 mg BW); at pH 4, the postlarvae did not metamorphose and measured only 9.8 mm TL, 29.3 mg BW. Length frequency distribution showed homogeneous growth at pH 6, positive skew at control pH 7.5 and pH 5, and extreme heterogeneity at pH 4. The carapace showed different transmittance spectra and lower total transmittance (i.e. thicker carapace) in juveniles at pH 7.5, pH 6, and pH 5 than in unmetamorphosed postlarvae and juveniles with thinner carapace at pH 4. Thus, survival, growth, size distribution, and carapace quality of M. rosenbergii postlarvae and early juveniles were negatively affected by pH 5 and especially pH 4. The thinner carapace of the survivors at pH 4 was mostly due to their small size and failure to metamorphose. Natural waters affected by acid rain could decimate M. rosenbergii populations in the wild.

  15. Differences in the surface composition of seemingly similar F75 cobalt-chromium micron-sized particulates can affect synovial fibroblast viability.

    PubMed

    Kovacik, M W; Mostardi, R A; Neal, D R; Bear, T F; Askew, M J; Bender, E T; Walker, J I; Ramsier, R D

    2008-09-01

    We present data and analyses concerning the cytotoxicity and bioreactivity associated with the surface composition of fine metal particulates that are similar to those commonly released in the body by prostheses used in total joint replacement surgery. Here we study the bulk and surface compositions of three separately procured cobalt-chromium-molybdenum (CoCrMo) micron-sized particulate powders, each identified by their corresponding vendor as being ASTM F75 grade material. We use energy dispersive spectroscopy (EDS) to verify the bulk metallic composition and X-ray photoelectron spectroscopy (XPS) to examine the surface metallic composition of each CoCrMo powder. Cultured synovial fibroblasts were then exposed to the particulate powders to see how the metallic surfaces might affect cellular viability. Results indicate that while the bulk metallic composition of each CoCrMo powder was similar, the surface metallic compositions were found to be dramatically different and yielded equally dramatic differences in terms of cytotoxicity and bioreactivity of synovial fibroblast in culture. PMID:18583107

  16. Differences in extreme low salinity timing and duration differentially affect eastern oyster (Crassostrea virginica) size class growth and mortality in Breton Sound, LA

    NASA Astrophysics Data System (ADS)

    La Peyre, Megan K.; Eberline, Benjamin S.; Soniat, Thomas M.; La Peyre, Jerome F.

    2013-12-01

    Understanding how different life history stages are impacted by extreme or stochastic environmental variation is critical for predicting and modeling organism population dynamics. This project examined recruitment, growth, and mortality of seed (25-75 mm) and market (>75 mm) sized oysters along a salinity gradient over two years in Breton Sound, LA. In April 2010, management responses to the Deepwater Horizon oil spill resulted in extreme low salinity (<5) at all sites through August 2010; in 2011, a 100-year Mississippi River flood event resulted in low salinity in late spring. Extended low salinity (<5) during hot summer months (>25 °C) significantly and negatively impacted oyster recruitment, survival and growth in 2010, while low salinity (<5) for a shorter period that did not extend into July (<25 °C) in 2011 had minimal impacts on oyster growth and mortality. In 2011, recruitment was limited, which may be due to a combination of low spring time salinities, high 2010 oyster mortality, minimal 2010 recruitment, cumulative effects from 10 years of declining oyster stock in the area, and poor cultch quality. In both 2010 and 2011, Perkinsus marinus infection prevalence remained low throughout the year at all sites and almost all infection intensities were light. Oyster plasma osmolality failed to match surrounding low salinity waters in 2010, while oysters appeared to osmoconform throughout 2011 indicating that the high mortality in 2010 may be due to extended valve closing and resulting starvation or asphyxiation in response to the combination of low salinity during high temperatures (>25 °C). With increasing management of our freshwater inputs to estuaries combined with predicted climate changes, how extreme events affect different life history stages is key to understanding variation in population demographics of commercially important species and predicting future populations.

  17. Differences in extreme low salinity timing and duration differentially affect eastern oyster (Crassostrea virginica) size class growth and mortality in Breton Sound, LA

    USGS Publications Warehouse

    LaPeyre, Megan K.; Eberline, Benjamin S.; Soniat, Thomas M.; La Peyre, Jerome F.

    2013-01-01

    Understanding how different life history stages are impacted by extreme or stochastic environmental variation is critical for predicting and modeling organism population dynamics. This project examined recruitment, growth, and mortality of seed (25–75 mm) and market (>75 mm) sized oysters along a salinity gradient over two years in Breton Sound, LA. In April 2010, management responses to the Deepwater Horizon oil spill resulted in extreme low salinity (<5) at all sites through August 2010; in 2011, a 100-year Mississippi River flood event resulted in low salinity in late spring. Extended low salinity (<5) during hot summer months (>25 °C) significantly and negatively impacted oyster recruitment, survival and growth in 2010, while low salinity (<5) for a shorter period that did not extend into July (<25 °C) in 2011 had minimal impacts on oyster growth and mortality. In 2011, recruitment was limited, which may be due to a combination of low spring time salinities, high 2010 oyster mortality, minimal 2010 recruitment, cumulative effects from 10 years of declining oyster stock in the area, and poor cultch quality. In both 2010 and 2011, Perkinsus marinusinfection prevalence remained low throughout the year at all sites and almost all infection intensities were light. Oyster plasma osmolality failed to match surrounding low salinity waters in 2010, while oysters appeared to osmoconform throughout 2011 indicating that the high mortality in 2010 may be due to extended valve closing and resulting starvation or asphyxiation in response to the combination of low salinity during high temperatures (>25 °C). With increasing management of our freshwater inputs to estuaries combined with predicted climate changes, how extreme events affect different life history stages is key to understanding variation in population demographics of commercially important species and predicting future populations.

  18. Zones of Peace.

    ERIC Educational Resources Information Center

    Evans, Judith L.; And Others

    1996-01-01

    Children affected by armed violence face a specific set of stressors and challenges which calls for appropriate programming. This Coordinator's Notebook focuses on how to work with children affected by organized violence in order to provide them the best possible early childhood experiences. It is divided into five sections. "Children as Zones of…

  19. Localized ageing in the heat affected zone of welded X5CrNiCuNbl6-4 and X4CrNiSiTi14-7 sheets

    NASA Astrophysics Data System (ADS)

    Sakhawat, S.; Falahati, A.; Degischer, H. P.; Spiradek, K.; Dománková, M.

    2014-06-01

    Localized ageing and corresponding microstructural developments as a result of welding heat in the heat-affected zone (HAZ) of two different precipitation-hardened Cr-Steels (X5CrNiCuNb16-4 and X4CrNiSiTi14-7) have been studied. The X5CrNiCuNb16-4 sheet was in solution annealed condition and X4CrNiSiTi14-7 sheet was in peak aged condition. The results showed that despite of initial heat treated condition, the fusion zone formed in both welded sheets has typical cast structure. The HAZ has different microstructure compared to fusion zone and base metal. The HAZ is found to be sensitive to the welding heat and was aged locally due to thermal effects of welding. This localized ageing forms regions in HAZ varying from over-aged to under aged, depending upon the initial ageing condition of the base sheet.

  20. Tensile Deformation Behavior and Phase Transformation in the Weld Coarse-Grained Heat-Affected Zone of Metastable High-Nitrogen Fe-18Cr-10Mn-N Stainless Steel

    NASA Astrophysics Data System (ADS)

    Moon, Joonoh; Lee, Tae-Ho; Park, Seong-Jun; Jang, Jae-il; Jang, Min-Ho; Ha, Heon-Young; Hwang, Byoungchul

    2013-07-01

    The tensile deformation behavior and phase transformation in the weld coarse-grained heat-affected zone (CGHAZ) of a metastable high-nitrogen austenitic stainless steel was explored through tensile tests, nanoindentation experiments, and transmission electron microscopy analysis. True stress-strain response during tensile test was found to be seriously affected by δ-ferrite fraction, which depends on peak temperature of the CGHAZs. The strain-induced martensitic transformation (SIMT) occurred in base steel, whereas the SIMT disappeared and deformation twinning occurred predominantly in the CGHAZs. The relationship among true stress-strain response, nanoindentation hardness, and deformed microstructures was carefully investigated and discussed in terms of changes of stacking fault energy.

  1. Cold seep and oxygen minimum zone associated sources of margin heterogeneity affect benthic assemblages, diversity and nutrition at the Cascadian margin (NE Pacific Ocean)

    NASA Astrophysics Data System (ADS)

    Guilini, Katja; Levin, Lisa A.; Vanreusel, Ann

    2012-04-01

    Hydrate Ridge (HR), located on the northeastern Pacific margin off Oregon, is characterized by the presence of outcropping hydrates and active methane seepage. Additionally, permanent low oxygen conditions overlay the benthic realm. This study evaluated the relative influence of both seepage and oxygen minima as sources of habitat heterogeneity and potential stress-inducing features on the bathyal metazoan benthos (primarily nematodes) at three different seep and non-seep HR locations, exposed to decreasing bottom-water oxygen concentrations with increasing water depth. The nematode seep communities at HR exhibited low diversity with dominance of only one or two genera (Daptonema and Metadesmolaimus), elevated average individual biomass and δ13C evidence for strong dependance on chemosynthesis-derived carbon, resembling deep-sea seeps worldwide. Although the HR seep habitats harbored a distinct nematode community like in other known seep communities, they differed from deep-sea seeps in well-oxygenated waters based on that they shared the dominant genera with the surrounding non-seep sediments overlain by oxygen-deficient bottom water. The homogenizing effect of the oxygen minimum zone on the seep nematode assemblages and surrounding sediments was constant with increasing water depth and concomitant greater oxygen-deficiency, resulting in a loss of habitat heterogeneity.

  2. How lithology and climate affect REE mobility and fractionation along a shale weathering transect of the Susquehanna Shale Hills Critical Zone Observatory

    NASA Astrophysics Data System (ADS)

    Ma, L.; Jin, L.; Dere, A. L.; White, T.; Mathur, R.; Brantley, S. L.

    2012-12-01

    Shale weathering is an important process in global elemental cycles. Accompanied by the transformation of bedrock into regolith, many elements including rare earth elements (REE) are mobilized primarily by chemical weathering in the Critical Zone. Then, REE are subsequently transported from the vadose zone to streams, with eventual deposition in the oceans. REE have been identified as crucial and strategic natural resources; and discovery of new REE deposits will be facilitated by understanding global REE cycles. At present, the mechanisms and environmental factors controlling release, transport, and deposition of REE - the sources and sinks - at Earth's surface remain unclear. Here, we present a systematic study of soils, stream sediments, stream waters, soil water and bedrock in six small watersheds that are developed on shale bedrock in the eastern USA to constrain the mobility and fractionation of REE during early stages of chemical weathering. The selected watersheds are part of the shale transect established by the Susquehanna Shale Hills Observatory (SSHO) and are well suited to investigate weathering on shales of different compositions or within different climate regimes but on the same shale unit. Our REE study from SSHO, a small gray shale watershed in central Pennsylvania, shows that up to 65% of the REE (relative to parent bedrock) is depleted in the acidic and organic-rich soils due to chemical leaching. Both weathering soil profiles and natural waters show a preferential removal of middle REE (MREE: Sm to Dy) relative to light REE (La to Nd) and heavy REE (Ho to Lu) during shale weathering, due to preferential release of MREE from a phosphate phase (rhabdophane). Strong positive Ce anomalies observed in the regolith and stream sediments point to the fractionation and preferential precipitation of Ce as compared to other REE, in the generally oxidizing conditions of the surface environments. One watershed developed on the Marcellus black shale in

  3. Bioturbation, geochemistry and geotechnics of sediments affected by the oxygen minimum zone on the Oman continental slope and abyssal plain, Arabian Sea

    NASA Astrophysics Data System (ADS)

    Meadows, Azra; Meadows, Peter S.; West, Fraser J. C.; Murray, John M. H.

    2000-01-01

    We investigate the way the oxygen minimum zone (OMZ) alters interactions between bioturbation and sediment geochemistry, and geotechnical properties. Sediments are compared within and below the OMZ on the Oman continental slope and adjacent abyssal plain during the post monsoonal autumn season. Quantitative measurements were made of Eh and pH, of total organic matter (TOM) and carbonate, of water content and shear strength, and of bioturbation structures in vertical profiles of subcores taken from spade-box core samples. The OMZ stations had distinctively low redox conditions and high carbonate content, and different geotechnical properties and different bioturbation structures than stations below the OMZ on the abyssal plain. These differences are related to the degree of anoxia and to water depth. Within the OMZ, Eh, pH and carbonate increased with water depth, and TOM and water content decreased. We also noted the presence of subsurface sediment heterogeneity on the continental slope within the OMZ. In the OMZ, Eh, water content and bioturbation decreased with increasing sediment depth. There was a slight decrease in pH in the top 5 cm at all stations. Shear strength nearly always increased with increasing sediment depth. At each water depth correlations show down-core trends in these parameters, while across all water depths correlations were significant at deeper sediment depths (20-30 cm). An Eh-pH diagram identified two water-depth groupings: 391-1008 and 1265-3396 m. Cluster analysis showed the upper and lower sediment depths form separate clusters, the break occurring at 4-7.5 cm; while there are also distinct clusters related to water depth. We relate our results to bottom-water oxygen concentrations reported by other investigators, and to regional-scale geochemical processes.

  4. Modelling vegetation water-use and groundwater recharge as affected by climate variability in an arid-zone Acacia savanna woodland

    NASA Astrophysics Data System (ADS)

    Chen, Chao; Eamus, Derek; Cleverly, James; Boulain, Nicolas; Cook, Peter; Zhang, Lu; Cheng, Lei; Yu, Qiang

    2014-11-01

    For efficient and sustainable utilisation of limited groundwater resources, improved understanding of how vegetation water-use responds to climate variation and the corresponding controls on recharge is essential. This study investigated these responses using a modelling approach. The biophysically based model WAVES was calibrated and validated with more than two years of field experimental data conducted in Mulga (Acacia aneura) in arid central Australia. The validated model was then applied to simulate vegetation growth (as changes in overstory and understory leaf area index; LAI), vegetation water-use and groundwater recharge using observed climate data for the period 1981-2012. Due to large inter-annual climatic variability, especially precipitation, simulated annual mean LAI ranged from 0.12 to 0.35 for the overstory and 0.07 to 0.21 for the understory. These variations in simulated LAI resulted in vegetation water-use varying greatly from year-to-year, from 64 to 601 mm pa. Simulated vegetation water-use also showed distinct seasonal patterns. Vegetation dynamics affected by climate variability exerted significant controls on simulated annual recharge, which was greatly reduced to 0-48 mm compared to that (58-672 mm) only affected by climate. Understanding how climate variability and land use/land cover change interactively impact on groundwater recharge significantly improves groundwater resources management in arid and semi-arid regions.

  5. Corrosion Cyclic Voltammetry of Two Types of Heat-Affected Zones (HAZs) of API-X100 Steel in Bicarbonate Solutions

    NASA Astrophysics Data System (ADS)

    Eliyan, Faysal Fayez; Alfantazi, Akram

    2014-12-01

    This paper examined the electrochemical corrosion behavior and corrosion products of two types of heat-affected HAZs made from API-X100 steel. Cyclic voltammetry, with different scan rates and potential ranges at 10 cycles, was applied to analyze the interdependent corrosion reactions of cathodic reduction, anodic dissolution, passivation, and transpassivation. The HAZ cooled at 60 K/s, from a peak temperature of 1470 K (1197 °C) that was held for 15 seconds, exhibited better passivation and lower cathodic activity than the HAZ cooled at 10 K/s. Increasing bicarbonate concentration, from 0.05 and 0.2 to 0.6 M, increases the anodic activity and cathodic reduction, but accordingly protects the active surfaces and enhances passivation.

  6. Steady convective flow in an unsaturated state dependent anisotropic soil profile: Analysis of the affected zone from a contaminating point source

    NASA Astrophysics Data System (ADS)

    Cohen, M.; Mualem, Y.

    2011-01-01

    SummaryAnisotropy of the medium plays a dominant role in shaping the flow pattern in the soil profile. This study analyses the effect of anisotropy on the horizontal spreading of the flow trajectories from a contaminating source point at the soil surface to a high water table. It considers a phreatic aquifer with infinite lateral extension and uniform sedimentary-layered soil profile, where a state dependent anisotropy factor (SDAF) - A( ψ), and Mualem's (1984) anisotropy model might be applicable. The numerically calculated streamlines portray the effect of anisotropy, and allow discernment among various anisotropic media. Different flow cases are analyzed with regard to their dependence on A( ψ), as well as their dependence on the infiltration rate, and on the orientation of the principal axes. Theory indicates that the flux direction is dependent on the capillary head and thus on the flow rate. Consequently, it is the infiltration rate, which determines the particular path line from the contaminant source point to the ground water table. Accordingly, we have defined the "affected domain" as the domain within the unsaturated profile which is vulnerable to contamination from a source point at the soil surface, and the "affected segment" as the segment on the phreatic surface where pollutants may potentially reach the ground water aquifer. Both are determined with respect to anisotropy, infiltration rate, and depth. The non-linear horizontal shift of the contaminant trajectory indicates that a substantial error may result when adopting a constant anisotropy factor. This study suggests that the maximal horizontal shift is the relevant scale when characterizing the anisotropic flow system. This measure should be taken into consideration when designing a related laboratory experiment or a field monitoring system.

  7. Recent (2008-10) water quality in the Barton Springs segment of the Edwards aquifer and its contributing zone, central Texas, with emphasis on factors affecting nutrients and bacteria

    USGS Publications Warehouse

    Mahler, Barbara J.; Musgrove, MaryLynn; Sample, Thomas L.; Wong, Corinne I.

    2011-01-01

    The Barton Springs zone, which comprises the Barton Springs segment of the Edwards aquifer and the watersheds to the west that contribute to its recharge, is in south-central Texas, an area with rapid growth in population and increasing amounts of land area affected by development. During November 2008-March 2010, an investigation of factors affecting the fate and transport of nutrients and bacteria in the Barton Springs zone was conducted by the U.S. Geological Survey (USGS), in cooperation with the Texas Commission on Environmental Quality. The primary objectives of the study were to characterize occurrence of nutrients and bacteria in the Barton Springs zone under a range of flow conditions; to improve understanding of the interaction between surface-water quality and groundwater quality; and to evaluate how factors such as streamflow variability and dilution affect the fate and transport of nutrients and bacteria in the Barton Springs zone. The USGS collected and analyzed water samples from five streams (Barton, Williamson, Slaughter, Bear, and Onion Creeks), two groundwater wells (Marbridge and Buda), and the main orifice of Barton Springs in Austin, Texas. During the period of the study, during which the hydrologic conditions transitioned from exceptional drought to wetter than normal, water samples were collected routinely (every 3 to 4 weeks) from the streams, wells, and spring and, in response to storms, from the streams and spring. All samples were analyzed for major ions, nutrients, the bacterium Escherichia coli, and suspended sediment. During the dry period, the geochemistry of groundwater at the two wells and at Barton Springs was dominated by flow from the aquifer matrix and was relatively similar and unchanging at the three sites. At the onset of the wet period, when the streams began to flow, the geochemistry of groundwater samples from the Marbridge well and Barton Springs changed rapidly, and concentrations of most major ions and nutrients and

  8. A field technique to measure the tortuosity and sorption-affected porosity for gaseous diffusion of materials in the unsaturated zone with experimental results from near Barnwell, South Carolina

    NASA Astrophysics Data System (ADS)

    Kreamer, David K.; Weeks, Edwin P.; Thompson, Glenn M.

    1988-03-01

    A tracer experiment was conducted at the commercial low-level nuclear waste disposal site near Barnwell, South Carolina, to test a new method for determining the tortuosity and sorption-affected porosity for gaseous diffusion transport of materials in the Unsaturated zone. Two tracers, CBrClF2 and SF6, were released at constant rates of 105 and 3.3 ng/s, respectively, from permeation devices, which were placed in short screened sections in access holes. Soil gas was sampled from 15 piezometers located at various distances from the sources by sequentially pumping 60-160 mL of gas from the piezometers into a dual-column gas chromatograph located at the test site. The CBrClF2 concentration data obtained from several of the piezometers were analyzed by use of type curves for a continuous point source in an areally extensive medium bounded above and below by planar no-flow boundaries. The tortuosity of the geologic unit tested, an eolian sand, was determined to be about 0.4, and the sorption-affected porosity to be 0.22. The tortuosity value is plausible, but the sorption-affected porosity value is substantially less than that computed from the drained porosity, particularly if adjustments are made for retardation due to solution of the tracer in the liquid phase and sorption on the solid phase. The SF6 data could not be reliably analyzed.

  9. Hydrogeology, Water Chemistry, and Factors Affecting the Transport of Contaminants in the Zone of Contribution of a Public-Supply Well in Modesto, Eastern San Joaquin Valley, California

    USGS Publications Warehouse

    Jurgens, Bryant C.; Burow, Karen R.; Dalgish, Barbara A.; Shelton, Jennifer L.

    2008-01-01

    Ground-water chemistry in the zone of contribution of a public-supply well in Modesto, California, was studied by the U.S. Geological Survey National Water Quality Assessment (NAWQA) Program's topical team for Transport of Anthropogenic and Natural Contaminants (TANC) to supply wells. Twenty-three monitoring wells were installed in Modesto to record baseline hydraulic information and to collect water-quality samples. The monitoring wells were divided into four categories that represent the chemistry of different depths and volumes of the aquifer: (1) water-table wells were screened between 8.5 and 11.7 m (meter) (28 and 38.5 ft [foot]) below land surface (bls) and were within 5 m (16 ft) of the water table; (2) shallow wells were screened between 29 and 35 m (95 and 115 ft) bls; (3) intermediate wells were screened between 50.6 and 65.5 m (166 and 215 ft) bls; and (4) deep wells are screened between 100 to 106 m (328 and 348 ft) bls. Inorganic, organic, isotope, and age-dating tracers were used to characterize the geochemical conditions in the aquifer and understand the mechanisms of mobilization and movement of selected constituents from source areas to a public-supply well. The ground-water system within the study area has been significantly altered by human activities. Water levels in monitoring wells indicated that horizontal movement of ground water was generally from the agricultural areas in the northeast towards a regional water-level depression within the city in the southwest. However, intensive pumping and irrigation recharge in the study area has caused large quantities of ground water to move vertically downward within the regional and local flow systems. Analysis of age tracers indicated that ground-water age varied from recent recharge at the water table to more than 1,000 years in the deep part of the aquifer. The mean age of shallow ground water was determined to be between 30 and 40 years. Intermediate ground water was determined to be a mixture

  10. Nano-size scaling of alloy intra-particle vs. inter-particle separation transitions: prediction of distinctly interface-affected critical behaviour.

    PubMed

    Polak, M; Rubinovich, L

    2016-07-21

    Phase-separation second-order transitions in binary alloy particles consisting of ∼1000 up to ∼70 000 atoms (∼1-10 nm) are modeled focusing on the unexplored issue of finite-size scaling in such systems, particularly on evaluation of correlation-length critical exponents. Our statistical-thermodynamic approach is based on mean-field analytical expression for the Ising model free energy that facilitates highly efficient computations furnishing comprehensive data for fcc rectangular nanoparticles (NPs). These are summed up in intra- and inter-particle scaling plots as well as in nanophase separation diagrams. Temperature-induced variations in the interface thickness in Janus-type intra-particle configurations and NP size-dependent shifts in the critical temperature of their transition to solid-solution reflect power-law behavior with the same critical exponent, ν = 0.83. It is attributed to dominant interfacial effects that are absent in inter-particle transitions. Variations in ν with nano-size, as revealed by a refined analysis, are linearly extrapolated in order to bridge the gap to larger particles within and well beyond the nanoscale, ultimately yielding ν = 1.0. Besides these findings, the study indicates the key role of the surface-area to volume ratio as an effective linear size, revealing a universal, particle-shape independent, nanoscaling of the critical-temperature shifts. PMID:27338842

  11. Small Works in Arkansas: How Poverty and the Size of Schools and School Districts Affect School Performance in Arkansas. Summary of Recent Research.

    ERIC Educational Resources Information Center

    Rural School and Community Trust, Washington, DC.

    A study examined how Arkansas students' achievement is related to poverty, school and district size, and the interaction between these factors. Achievement test scores from grades 4, 5, 7, 8, and 9 in all Arkansas schools were supplied by the Arkansas Department of Education. Poverty levels were determined by percentage of students receiving…

  12. Group size of veal calves does not affect production, physiological, or hematological indicators of welfare and has transient effects on health

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Holstein-Friesian bull calves (n = 168; 44 ± 3 d of age), were used to investigate the effect of group size on performance, health, hematology, and welfare of veal calves. Groups of calves were assigned to 1 of 3 group housing treatments with 2, 4, or 8 calves per pen (initial BW 65.3 ± 3.7, 66.5 ± ...

  13. How to create mylonitic shear zones in the presence of shear heating

    NASA Astrophysics Data System (ADS)

    Thielmann, Marcel; Rozel, Antoine; Kaus, Boris; Ricard, Yanick

    2013-04-01

    (Kaus & Podlatchikov (2005), Braeck et al. (2009)) and the significant temperature increase induced by shear heating severely affects the grain size in the shear zone. Generally, we find that the elevated temperature inside the shear zone results in a larger grain size inside the shear zone compared to the surrounding rock matrix. This finding is not compatible with field observations, where shear zones are usually characterized by small grain sizes. This indicates that further mechanisms are needed to keep either the grain size small (e.g. pinning by secondary phases (Herwegh et. al (2011), Bercovici and Ricard (2012) ) or to limit the temperature increase inside the shear zone.

  14. Strongly-motivated positive affects induce faster responses to local than global information of visual stimuli: an approach using large-size Navon letters

    PubMed Central

    Noguchi, Yasuki; Tomoike, Kouta

    2016-01-01

    Recent studies argue that strongly-motivated positive emotions (e.g. desire) narrow a scope of attention. This argument is mainly based on an observation that, while humans normally respond faster to global than local information of a visual stimulus (global advantage), positive affects eliminated the global advantage by selectively speeding responses to local (but not global) information. In other words, narrowing of attentional scope was indirectly evidenced by the elimination of global advantage (the same speed of processing between global and local information). No study has directly shown that strongly-motivated positive affects induce faster responses to local than global information while excluding a bias for global information (global advantage) in a baseline (emotionally-neutral) condition. In the present study, we addressed this issue by eliminating the global advantage in a baseline (neutral) state. Induction of positive affects under this state resulted in faster responses to local than global information. Our results provided direct evidence that positive affects in high motivational intensity narrow a scope of attention. PMID:26754087

  15. DRAINAGE IN FINITE-SIZED UNSATURATED ZONES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    After the initiation of gravity drainage, water is often assumed to be either a) draining under unit gradient, or b) at capillary/gravity equilibrium. Both of these simplifications can be useful, but the regimes of validity of each assumption must be delineated. Water pressures are measured versus t...

  16. Comment on Schielzeth et al. (2014): "Genome size variation affects song attractiveness in grasshoppers: Evidence for sexual selection against large genomes".

    PubMed

    Camacho, Juan Pedro M

    2016-06-01

    Schielzeth et al. (2014) concluded that attractive grasshopper singers have significantly smaller genomes thus suggesting a possible role for sexual selection on genome size. Whereas this conclusion could still be conceivably valid, it is not supported by the data presented due to some technical flaws. In addition, the interpretation of the results, speculating on the possible presence of B chromosomes, is not justified. PMID:27327141

  17. Imaging dose in breast radiotherapy: does breast size affect the dose to the organs at risk and the risk of secondary cancer to the contralateral breast?

    SciTech Connect

    Batumalai, Vikneswary; Quinn, Alexandra; Jameson, Michael; Delaney, Geoff; Holloway, Lois

    2015-03-15

    Correct target positioning is crucial for accurate dose delivery in breast radiotherapy resulting in utilisation of daily imaging. However, the radiation dose from daily imaging is associated with increased probability of secondary induced cancer. The aim of this study was to quantify doses associated with three imaging modalities and investigate the correlation of dose and varying breast size in breast radiotherapy. Planning computed tomography (CT) data sets of 30 breast cancer patients were utilised to simulate the dose received by various organs from a megavoltage computed tomography (MV-CT), megavoltage electronic portal image (MV-EPI) and megavoltage cone-beam computed tomography (MV-CBCT). The mean dose to organs adjacent to the target volume (contralateral breast, lungs, spinal cord and heart) were analysed. Pearson correlation analysis was performed to determine the relationship between imaging dose and primary breast volume and the lifetime attributable risk (LAR) of induced secondary cancer was calculated for the contralateral breast. The highest contralateral breast mean dose was from the MV-CBCT (1.79 Gy), followed by MV-EPI (0.22 Gy) and MV-CT (0.11 Gy). A similar trend was found for all organs at risk (OAR) analysed. The primary breast volume inversely correlated with the contralateral breast dose for all three imaging modalities. As the primary breast volume increases, the likelihood of a patient developing a radiation-induced secondary cancer to the contralateral breast decreases. MV-CBCT showed a stronger relationship between breast size and LAR of developing a radiation-induced contralateral breast cancer in comparison with the MV-CT and MV-EPI. For breast patients, imaging dose to OAR depends on imaging modality and treated breast size. When considering the use of imaging during breast radiotherapy, the patient's breast size and contralateral breast dose should be taken into account.

  18. Quantitative trait loci affecting the 3D skull shape and size in mouse and prioritization of candidate genes in-silico

    PubMed Central

    Maga, A. Murat; Navarro, Nicolas; Cunningham, Michael L.; Cox, Timothy C.

    2015-01-01

    We describe the first application of high-resolution 3D micro-computed tomography, together with 3D landmarks and geometric morphometrics, to map QTL responsible for variation in skull shape and size using a backcross between C57BL/6J and A/J inbred strains. Using 433 animals, 53 3D landmarks, and 882 SNPs from autosomes, we identified seven QTL responsible for the skull size (SCS.qtl) and 30 QTL responsible for the skull shape (SSH.qtl). Size, sex, and direction-of-cross were all significant factors and included in the analysis as covariates. All autosomes harbored at least one SSH.qtl, sometimes up to three. Effect sizes of SSH.qtl appeared to be small, rarely exceeding 1% of the overall shape variation. However, they account for significant amount of variation in some specific directions of the shape space. Many QTL have stronger effect on the neurocranium than expected from a random vector that will parcellate uniformly across the four cranial regions. On the contrary, most of QTL have an effect on the palate weaker than expected. Combined interval length of 30 SSH.qtl was about 315 MB and contained 2476 known protein coding genes. We used a bioinformatics approach to filter these candidate genes and identified 16 high-priority candidates that are likely to play a role in the craniofacial development and disorders. Thus, coupling the QTL mapping approach in model organisms with candidate gene enrichment approaches appears to be a feasible way to identify high-priority candidates genes related to the structure or tissue of interest. PMID:25859222

  19. Inspiration or deflation? Feeling similar or dissimilar to slim and plus-size models affects self-evaluation of restrained eaters.

    PubMed

    Papies, Esther K; Nicolaije, Kim A H

    2012-01-01

    The present studies examined the effect of perceiving images of slim and plus-size models on restrained eaters' self-evaluation. While previous research has found that such images can lead to either inspiration or deflation, we argue that these inconsistencies can be explained by differences in perceived similarity with the presented model. The results of two studies (ns=52 and 99) confirmed this and revealed that restrained eaters with high (low) perceived similarity to the model showed more positive (negative) self-evaluations when they viewed a slim model, compared to a plus-size model. In addition, Study 2 showed that inducing in participants a similarities mindset led to more positive self-evaluations after viewing a slim compared to a plus-size model, but only among restrained eaters with a relatively high BMI. These results are discussed in the context of research on social comparison processes and with regard to interventions for protection against the possible detrimental effects of media images. PMID:21962524

  20. Effect of adsorbent particle size on the relative merits of a non-triangular and a triangular separation region in the optimal design of a three-zone simulated moving bed chromatography for binary separation with linear isotherms.

    PubMed

    Mun, Sungyong

    2016-06-24

    The design approaches for a three-zone simulated moving bed (SMB) chromatography with linear isotherms can be classified into two categories, depending on whether the SMB design is based on a classical region (i.e., triangular region of the triangle theory) in the first quadrant (m2, m3) plane or on a non-triangular separation region in the third quadrant (m2, m3) plane. The SMBs based on the classical and the non-triangular design approaches, which are named here as (m(+))_SMB and (m(-))_SMB respectively, are compared in this study using the Pareto solutions from the simultaneous optimization of throughput and desorbent usage under the constraints on product purities and pressure drop. The results showed that the (m(-))_SMB approach led to significantly lower desorbent usage than the (m(+))_SMB approach, which was due to the fact that the flow-rate-ratios from the (m(-))_SMB approach are extremely lower than those from the (m(+))_SMB approach. This factor also enables the (m(-))_SMB to have a significantly lower pressure drop, thereby making its throughput less restricted by a pressure-drop constraint. Due to such advantage of the (m(-))_SMB, it can make a further substantial improvement in throughput by modulating its adsorbent particle size properly. This issue was investigated using a model separation system containing succinic acid and acetic acid. It was confirmed that if the adsorbent particle size corresponding to the boundary between a mass-transfer limiting region and a pressure-drop limiting region is adopted, the (m(-))_SMB can lead to 82% higher throughput and 73% lower desorbent usage than the (m(+))_SMB. PMID:27208988

  1. What affects the innovation performance of small and medium-sized enterprises (SMEs) in the biotechnology industry? An empirical study on Korean biotech SMEs.

    PubMed

    Kang, Kyung-Nam; Lee, Yoon-Sik

    2008-10-01

    Research-intensive small and medium-sized enterprises (SMEs) play a crucial role in the advancement of the biotechnology industry. This paper explored the impacts of internal and contextual variables on innovative activity in Korea and compared the results of this analysis with previous studies of other countries. Our analysis of 149 Korean biotech SMEs showed that the ratio of R&D expenditure to sales, the ratio of R&D employees to total employees, CEO characteristics, governmental support and international networking are positively correlated with a firm's innovation performance. The results may help decision makers to better foster SMEs in the Korean biotechnology industry. PMID:18506395

  2. Resource quality affects weapon and testis size and the ability of these traits to respond to selection in the leaf-footed cactus bug, Narnia femorata.

    PubMed

    Sasson, Daniel A; Munoz, Patricio R; Gezan, Salvador A; Miller, Christine W

    2016-04-01

    The size of weapons and testes can be central to male reproductive success. Yet, the expression of these traits is often extremely variable. Studies are needed that take a more complete organism perspective, investigating the sources of variation in both traits simultaneously and using developmental conditions that mimic those in nature. In this study, we investigated the components of variation in weapon and testis sizes using the leaf-footed cactus bug, Narnia femorata (Hemiptera: Coreidae) on three natural developmental diets. We show that the developmental diet has profound effects on both weapon and testis expression and scaling. Intriguingly, males in the medium-quality diet express large weapons but have relatively tiny testes, suggesting complex allocation decisions. We also find that heritability, evolvability, and additive genetic variation are highest in the high-quality diet for testis and body mass. This result suggests that these traits may have an enhanced ability to respond to selection during a small window of time each year when this diet is available. Taken together, these results illustrate that normal, seasonal fluctuations in the nutritional environment may play a large role in the expression of sexually selected traits and the ability of these traits to respond to selection. PMID:27066225

  3. Sex allocation and secondary sex ratio in Cuban boa (Chilabothrus angulifer): mother's body size affects the ratio between sons and daughters.

    PubMed

    Frynta, Daniel; Vejvodová, Tereza; Šimková, Olga

    2016-06-01

    Secondary sex ratios of animals with genetically determined sex may considerably deviate from equality. These deviations may be attributed to several proximate and ultimate factors. Sex ratio theory explains some of them as strategic decisions of mothers improving their fitness by selective investment in sons or daughters, e.g. local resource competition hypothesis (LRC) suggests that philopatric females tend to produce litters with male-biased sex ratios to avoid future competition with their daughters. Until now, only little attention has been paid to examine predictions of sex ratio theory in snakes possessing genetic sex determination and exhibiting large variance in allocation of maternal investment. Cuban boa is an endemic viviparous snake producing large-bodied newborns (∼200 g). Extremely high maternal investment in each offspring increases importance of sex allocation. In a captive colony, we collected breeding records of 42 mothers, 62 litters and 306 newborns and examined secondary sex ratios (SR) and sexual size dimorphism (SSD) of newborns. None of the examined morphometric traits of neonates appeared sexually dimorphic. The sex ratio was slightly male biased (174 males versus 132 females) and litter sex ratio significantly decreased with female snout-vent length. We interpret this relationship as an additional support for LRC as competition between mothers and daughters increases with similarity of body sizes between competing snakes. PMID:27216175

  4. Sex allocation and secondary sex ratio in Cuban boa ( Chilabothrus angulifer): mother's body size affects the ratio between sons and daughters

    NASA Astrophysics Data System (ADS)

    Frynta, Daniel; Vejvodová, Tereza; Šimková, Olga

    2016-06-01

    Secondary sex ratios of animals with genetically determined sex may considerably deviate from equality. These deviations may be attributed to several proximate and ultimate factors. Sex ratio theory explains some of them as strategic decisions of mothers improving their fitness by selective investment in sons or daughters, e.g. local resource competition hypothesis (LRC) suggests that philopatric females tend to produce litters with male-biased sex ratios to avoid future competition with their daughters. Until now, only little attention has been paid to examine predictions of sex ratio theory in snakes possessing genetic sex determination and exhibiting large variance in allocation of maternal investment. Cuban boa is an endemic viviparous snake producing large-bodied newborns (˜200 g). Extremely high maternal investment in each offspring increases importance of sex allocation. In a captive colony, we collected breeding records of 42 mothers, 62 litters and 306 newborns and examined secondary sex ratios (SR) and sexual size dimorphism (SSD) of newborns. None of the examined morphometric traits of neonates appeared sexually dimorphic. The sex ratio was slightly male biased (174 males versus 132 females) and litter sex ratio significantly decreased with female snout-vent length. We interpret this relationship as an additional support for LRC as competition between mothers and daughters increases with similarity of body sizes between competing snakes.

  5. Repeated applications of compost and manure mainly affect the size and chemical nature of particulate organic matter in a loamy soil after 8 years

    NASA Astrophysics Data System (ADS)

    Peltre, Clement; Dignac, Marie-France; Doublet, Jeremy; Plante, Alain; Houot, Sabine

    2013-04-01

    Land application of exogenous organic matter (EOM) of residual origin can help to maintain or increase soil organic carbon (SOC) stocks. However, it remains necessary to quantify and predict the soil C accumulation and to determine under which form the C accumulates. Changes to the chemical composition of soil organic matter (SOM) after repeated applications of composts and farmyard manure were investigated in a field experiment (Qualiagro experiment, Ile-de-France) after 8 years of applications of green waste and sludge compost (GWS), municipal solid waste compost (MSW), biowaste compost (BIOW) or farmyard manure (FYM). The soil was fractionated into particulate organic matter >50 µm (POM), a heavy fraction >50 µm and a 0-50 µm fraction demineralized with hydrofluoric acid (HF). Repeated EOM applications significantly increased total SOC stocks, the C amount in the POM fraction and to a less extent in the 0-50 µm fraction compared to the reference treatment. Compost applications accumulated C preferentially under the form of coarse organic matter of size >50 µm, whereas the FYM accumulated similar C proportions of size >50 µm and 0-50 µm, which was attributed to the presence in the FYM of a fraction of labile C stimulating microbial activity and producing humified by-products together with a fraction of stabilized C directly alimenting the humified fraction of SOC. Pyrolysis-GC/MS and DRIFT spectroscopy revealed enrichment in lignin in the POM fractions of amended soils with GWS, BIOW and FYM. In the soil receiving MSW compost, the pyrolysate of the POM fraction revealed the presence of plastics originating from the MSW compost. A lower C mineralization during laboratory incubation was found for the POM fractions of amended soils compared with the POM from reference soil. This feature was related to a lower ratio of (furfural+acetic acid) / pyrole pyrolysis products in POM of amended vs. reference plots, indicating a higher degree of recalcitrance.. The POM

  6. Trans-generational exposure to low levels of rhodamine B does not adversely affect litter size or liver function in murine mucopolysaccharidosis type IIIA.

    PubMed

    Roberts, Ainslie L K; Fletcher, Janice M; Moore, Lynette; Byers, Sharon

    2010-01-01

    MPS IIIA is a lysosomal storage disorder caused by mutations in the sulphamidase gene, resulting in the accumulation of heparan sulphate glycosaminoglycans (HS GAGs). Symptoms predominantly manifest in the CNS and there is no current therapy that effectively addresses neuropathology in MPS IIIA patients. Recent studies in MPS IIIA mice have shown that rhodamine B substrate deprivation therapy (SDT) (also termed substrate reduction therapy/SRT) inhibits GAG biosynthesis and, improves both somatic and CNS disease pathology. Acute overexposure to high doses of rhodamine B results in liver toxicity and is detrimental to reproductive ability. However, the long-term effects of decreasing GAG synthesis, at the low dose sufficient to alter neurological function are unknown. A trans-generational study was therefore initiated to evaluate the continuous exposure of rhodamine B treatment in MPS IIIA mice over 4 generations, including treatment during pregnancy. No alterations in litter size, liver histology or liver function were observed. Overall, there are no long-term issues with the administration of rhodamine B at the low dose tested and no adverse effects were noted during pregnancy in mice. PMID:20650670

  7. Environmental factors affecting soil metals near outlet roads in Poznań, Poland: impact of grain size, soil depth, and wind dispersal.

    PubMed

    Ciazela, Jakub; Siepak, Marcin

    2016-06-01

    We determined the Cd, Cr, Cu, Ni, Pb, and Zn concentrations in soil samples collected along the eight main outlet roads of Poznań. Samples were collected at distances of 1, 5, and 10 m from the roadway edges at depth intervals of 0-20 and 40-60 cm. The metal content was determined in seven grain size fractions. The highest metal concentrations were observed in the smallest fraction (<0.063 mm), which were up to four times higher than those in sand fractions. Soil Pb, Cu, and Zn (and to a lesser extent Ni, Cr, and Cd) all increased in relation to the geochemical background. At most sampling sites, metal concentrations decreased with increasing distance from roadway edges and increasing depth. In some locations, the accumulation of metals in soils appears to be strongly influenced by wind direction. Our survey findings should contribute in predicting the behavior of metals along outlet road, which is important by assessing sources for further migration of heavy metals into the groundwater, plants, and humans. PMID:27147236

  8. Effects of alloying elements on fracture toughness in the transition temperature region of base metals and simulated heat-affected zones of Mn-Mo-Ni low-alloy steels

    NASA Astrophysics Data System (ADS)

    Kim, Sangho; Im, Young-Roc; Lee, Sunghak; Lee, Hu-Chul; Kim, Sung-Joon; Hong, Jun Hwa

    2004-07-01

    This study is concerned with the effects of alloying elements on fracture toughness in the transition temperature region of base metals and heat-affected zones (HAZs) of Mn-Mo-Ni low-alloy steels. Three kinds of steels whose compositions were varied from the composition specification of SA 508 steel (grade 3) were fabricated by vacuum-induction melting and heat treatment, and their fracture toughness was examined using an ASTM E1921 standard test method. In the steels that have decreased C and increased Mo and Ni content, the number of fine M2C carbides was greatly increased and the number of coarse M3C carbides was decreased, thereby leading to the simultaneous improvement of tensile properties and fracture toughness. Brittle martensite-austenite (M-A) constituents were also formed in these steels during cooling, but did not deteriorate fracture toughness because they were decomposed to ferrite and fine carbides after tempering. Their simulated HAZs also had sufficient impact toughness after postweld heat treatment. These findings indicated that the reduction in C content to inhibit the formation of coarse cementite and to improve toughness and the increase in Mo and Ni to prevent the reduction in hardenability and to precipitate fine M2C carbides were useful ways to improve simultaneously the tensile and fracture properties of the HAZs as well as the base metals.

  9. Insights into factors affecting nitrate in PM2.5 in a polluted high NOx environment through hourly observations and size distribution measurements

    NASA Astrophysics Data System (ADS)

    Xue, Jian; Yuan, Zibing; Lau, Alexis K. H.; Yu, Jian Zhen

    2014-04-01

    Nitrate, a major PM2.5 component in polluted environments, could be greatly elevated during pollution episodes. In this study, nitrate and other inorganic ions on PM2.5 were measured half hourly at a residential location in Hong Kong in December 2009. Hourly nitrate concentrations in PM2.5 varied from 0.8 to 40.5 µg m-3. In an episode during which hourly visibility was down to 3.7 ± 1.0 km and NO2 was 80.7 ± 14.4 ppb, PM2.5 NO3- reached 27.8 ± 8.0 µg m-3, ~6 times the level during the normal hours. Nitrate was fully balanced by NH4+, indicating abundant presence of NH3. Size-segregated measurements showed 84% of nitrate was in the fine mode during the episode and also suggested that less acidic fine particles and less abundant sea-salt particles were the contributing factors to the dominant presence in the fine mode. An observation-based model for secondary inorganic aerosols was applied to investigate the relative importance of homogeneous and heterogeneous reactions to production of NO3- potential (sum of HNO3 (g) and aerosol nitrate). The modeling analysis shows that both formation pathways were significantly more active during the episode. Gas phase production of HNO3 through reaction of NO2 + OH dominated during the initial rapid buildup of nitrate around noon time, but the heterogeneous N2O5 hydrolysis pathway made a sizable contribution in the subsequent few hours due to sustained high-NO2 concentrations combined with reduced photolysis loss of N2O5. This case study illustrates the important role of NH3 and NO2 in elevating PM2.5 in a high-NOx environment through the formation of nitrate.

  10. Shear zone nucleation and deformation transient: effect of heterogeneities and loading conditions in experimentally deformed calcite

    NASA Astrophysics Data System (ADS)

    Morales, L. F. G.; Rybacki, E.; Dresen, G. H.; Kilian, R.

    2015-12-01

    In the Earth's middle to lower crust, strain is frequently localized along ductile shear zones, which commonly nucleate at structural and material heterogeneities. To investigate shear zone nucleation and development due to heterogeneities, we performed constant strain-rate (CSR) and constant stress (CS) simple shear (torsion) deformation experiments on Carrara marble samples containing weak (limestone) inclusions. The experiments were conducted in a Paterson-type gas deformation apparatus at 900 °C temperature and 400 MPa confining pressure and maximum bulk shear strains of 3. Peak shear stress was about 20 MPa for all the samples, followed by smooth weakening and steady state behavior. The strain is predominantly localized in the host marble within the process zone in front of the inclusion, defined by a zone of intense grain size reduction due to dynamic recrystallization. In CS tests a narrow shear zone developed in front of the inclusion, whereas in CSR experiments the deformation is more heterogeneously distributed, up to g=3.. In the later, secondary foliations oblique to the process zone and alternating thin, high-strain layers are common. In samples deformed at the same shear strain (g=1), the average recrystallized grain size in the process zone is similar for CS and CSR conditions. Crystallographic preferred orientation (CPO) measurements shows that different grain sizes have slightly different CPO patterns. CPO strength varies for different grain sizes, with a CPO strength peak between 40-50 μm, decreasing progressively within smaller grain size, but with secondary peaks for different coarse-grained sizes. Our observations suggest that the initial formation and transient deformation of shear zones is strongly affected by loading conditions.

  11. An age–size reaction norm yields insight into environmental interactions affecting life-history traits: a factorial study of larval development in the malaria mosquito Anopheles gambiae sensu stricto

    PubMed Central

    Phelan, Conan; Rotiberg, Bernard D

    2013-01-01

    Environmental factors frequently act nonindependently to determine growth and development of insects. Because age and size at maturity strongly influence population dynamics, interaction effects among environmental variables complicate the task of predicting dynamics of insect populations under novel conditions. We reared larvae of the African malaria mosquito Anopheles gambiae sensu stricto (s.s.) under three factors relevant to changes in climate and land use: food level, water depth, and temperature. Each factor was held at two levels in a fully crossed design, for eight experimental treatments. Larval survival, larval development time, and adult size (wing length) were measured to indicate the importance of interaction effects upon population-level processes. For age and size at emergence, but not survival, significant interaction effects were detected for all three factors, in addition to sex. Some of these interaction effects can be understood as consequences of how the different factors influence energy usage in the context of a nonindependent relationship between age and size. Experimentally assessing interaction effects for all potential future sets of conditions is intractable. However, considering how different factors affect energy usage within the context of an insect's evolved developmental program can provide insight into the causes of complex environmental effects on populations. PMID:23919132

  12. Tensile properties of vanadium-base alloys with a tungsten/inert-gas weld zone

    SciTech Connect

    Loomis, B.A.; Konicek, C.F.; Nowicki, L.J.; Smith, D.L.

    1992-12-31

    The tensile properties of V-(0-20)Ti and V-(O-15)Cr-5Ti alloys after butt-joining by tungsten/inert-gas (TIG) welding were determined from tests at 25{degrees}C. Tensile tests were conducted on both annealed and cold-worked materials with a TIG weld zone. The tensile properties of these materials were strongly influenced by the microstructure in the heat-affected zone adjacent to the weld zone and by the intrinsic fracture toughness of the alloys. TIG weld zones in these vanadium-base alloys had tensile properties comparable to those of recrystallized alloys without a weld zone. Least affected by the TIG welding were tensile properties of the V-5Ti and V-5Cr-5Ti alloys. Although the tensile properties of the V-5Ti and V- 5Cr-5Ti alloys with a TIG weld zone were acceptable for structural material, these properties would be improved by optimization of the welding parameters for minimum grain size in the heat-affected zone.

  13. Tree size and understory phytomass production in a western Juniper woodland

    SciTech Connect

    Vaitkus, M.R.; Eddleman, L.E. )

    1991-09-01

    Understory phytomass production in a western juniper (Juniperus occidentalis) woodland was examined relative to tree size in central Oregon in 1983 and 1984. Vegetation was sampled in two zones, the canopy zone (beneath the canopy) and the intercanopy zone (the space between canopies), on two adjacent sites - a lower slope site with shallow soil and an upper slope site with deeper soil. Sampling was stratified into three tree size classes. Individual species production was significantly affected by tree size and location relative to tree canopy. Production of bottlebrush squirreltail, bluebunch wheatgrass, cheatgrass, miscellaneous annual grasses, perennial forbs, and annual forbs increased with increasing tree size. Sandberg bluegrass production was greater in the intercanopy than the canopy zone, while production of bottlebrush squirreltail, bluebunch wheatgrass, miscellaneous annual grasses, and both perennial and annual forbs was greater in the canopy zone. Production of cheatgrass was determined by the interaction of tree size and zone. Phytomass relationships were expressed to a greater degree on the upper slope site, where total production exceeded that of the lower slope site by approximately 50% the second year of the study. Individual trees appear to exert a great influence on associated vegetation as western juniper woodlands progress from the seedling (tree establishment) phase to closed stands of mature trees. Original community dominants appear to be spatially segregated beneath tree canopies and associated with large trees, while formerly less common species, such as cheatgrass, come to dominate the entire site.

  14. Geological factors affecting CO2 plume distribution

    USGS Publications Warehouse

    Frailey, S.M.; Leetaru, H.

    2009-01-01

    Understanding the lateral extent of a CO2 plume has important implications with regards to buying/leasing pore volume rights, defining the area of review for an injection permit, determining the extent of an MMV plan, and managing basin-scale sequestration from multiple injection sites. The vertical and lateral distribution of CO2 has implications with regards to estimating CO2 storage volume at a specific site and the pore pressure below the caprock. Geologic and flow characteristics such as effective permeability and porosity, capillary pressure, lateral and vertical permeability anisotropy, geologic structure, and thickness all influence and affect the plume distribution to varying degrees. Depending on the variations in these parameters one may dominate the shape and size of the plume. Additionally, these parameters do not necessarily act independently. A comparison of viscous and gravity forces will determine the degree of vertical and lateral flow. However, this is dependent on formation thickness. For example in a thick zone with injection near the base, the CO2 moves radially from the well but will slow at greater radii and vertical movement will dominate. Generally the CO2 plume will not appreciably move laterally until the caprock or a relatively low permeability interval is contacted by the CO2. Conversely, in a relatively thin zone with the injection interval over nearly the entire zone, near the wellbore the CO2 will be distributed over the entire vertical component and will move laterally much further with minimal vertical movement. Assuming no geologic structure, injecting into a thin zone or into a thick zone immediately under a caprock will result in a larger plume size. With a geologic structure such as an anticline, CO2 plume size may be restricted and injection immediately below the caprock may have less lateral plume growth because the structure will induce downward vertical movement of the CO2 until the outer edge of the plume reaches a spill

  15. Spatially resolved X-ray diffraction phase mapping and {alpha} {r_arrow} {beta} {r_arrow} {alpha} transformation kinetics in the heat-affected zone of commercially pure titanium arc welds

    SciTech Connect

    Elmer, J.W.; Wong, J.; Ressler, T.

    1998-11-01

    Spatially resolved X-ray diffraction (SRXRD) is used to map the {alpha} {r_arrow} {beta} {r_arrow} {alpha} phase transformation in the heat-affected zone (HAZ) of commercially pure titanium gas tungsten arc welds. In situ SRXRD experiments were conducted using a 180-{micro}m-diameter X-ray beam at the Stanford Synchrotron Radiation Laboratory (SSRL) (Stanford, CA) to probe the phases present in the HAZ of a 1.9 kW weld moving at 1.1 mm/s. Results of sequential linear X-ray diffraction scans made perpendicular to the weld direction were combined to construct a phase transformation map around the liquid weld pool. This map identifies six HAZ microstructural regions between the liquid weld pool and the base metal: (1) {alpha}-Ti that is undergoing annealing and recrystallization; (2) completely recrystallized {alpha}-Ti; (3) partially transformed {alpha}-Ti, where {alpha}-Ti and {beta}-Ti coexist; (4) single-phase {beta}-Ti; (5) back-transformed {alpha}Ti; and (6) recrystallized {alpha}-Ti plus back-transformed {alpha}-Ti. Although the microstructure consisted predominantly of {alpha}-Ti, both prior to and after the weld, the crystallographically textured starting material was altered during welding to produce different {alpha}-Ti textures within the resulting HAZ. Based on the travel speed of the weld, the {alpha} {r_arrow} {beta} transformation was measured to take 1.83 seconds during heat, while the {beta} {r_arrow} {alpha} transformation was measured to take 0.91 seconds during cooling. The {alpha} {r_arrow} {beta} transformation was characterized to be dominated by long-range diffusion growth on the leading (heating) side of the weld, while the {beta} {r_arrow} {alpha} transformation was characterized to be predominantly massive on the trailing (cooling) side of the weld, with a massive growth rate on the order of 100 {micro}m/s.

  16. Stratospheric aerosols in the intertropical convergence zone, Panama Canal zone

    NASA Technical Reports Server (NTRS)

    Farlow, N. H.; Ferry, G. V.; Lem, H. Y.; Hayes, D. M.

    1979-01-01

    To investigate whether injection sources of the stratospheric aerosol layer could be detected in the tropical stratosphere, an examination of the aerosol vertical and horizontal size distribution around the Intertropical Convergence Zone (ITCZ) at the Panama Canal Zone was performed during the summer of 1977. By comparing these data with similar measurements in temperate and polar regions, it was hoped to discover variations in particle size that would indicate whether a young aerosol is forming and entering the stratosphere at the ITCZ; where the aerosol matures; and finally, where it reenters the troposphere. The methods used in the investigations and the results obtained from the analyses are described.

  17. Relationship between crystallographic structure of the Ti{sub 2}O{sub 3}/MnS complex inclusion and microstructure in the heat-affected zone (HAZ) in steel processed by oxide metallurgy route and impact toughness

    SciTech Connect

    Xiong, Zhihui; Liu, Shilong; Wang, Xuemin; Shang, Chengjia; Misra, R.D.K.

    2015-08-15

    A new method based on electron back scattered diffraction (EBSD) is proposed to determine the structure of titanium oxide/MnS complex inclusion which induced the formation of intragranular acicular ferrite (IAF) in heat-affected zone (HAZ) in steel processed by oxide metallurgy route. It was found that the complex inclusion was Ti{sub 2}O{sub 3}/MnS, the orientation relationship between Ti{sub 2}O{sub 3} and MnS was also examined, and the crystallographic orientation relationship among IAF, Ti{sub 2}O{sub 3}/MnS complex inclusion, austenite, bainite formed at lower temperature is researched systematically. It was observed that MnS precipitated on Ti{sub 2}O{sub 3} at specific habit plane and direction and MnS had a specific orientation relationship ((0001) Ti{sub 2}O{sub 3}//(111) MnS), <10–10> Ti{sub 2}O{sub 3}//<110> MnS) with respect to Ti{sub 2}O{sub 3}. Intragranular acicular ferrite (IAF) nucleated on MnS part of the Ti{sub 2}O{sub 3}/MnS complex inclusion had no specific orientation relationship with MnS. IAF and the surrounding bainite had different Bain groups, so that there was an increase in high angle boundaries, which was beneficial for the toughness of HAZ. - Highlights: • The inclusion of TiO{sub x}/MnS that induced IAF formation is identified to be Ti{sub 2}O{sub 3}/MnS. • The inclusion is identified based on electron back scattered diffraction (EBSD). • MnS and Ti{sub 2}O{sub 3} had specific orientation relationship of Ti{sub 2}O{sub 3}/MnS complex inclusion. • The IAFs formed on the same inclusion tend to be in one Bain group. • IAF and the surrounding bainite tend to be in different Bain groups.

  18. Evaluation of factors that influence estimated zones of transport for six municipal wells in Clark County, Washington

    USGS Publications Warehouse

    Orzol, L.L.; Truini, Margot

    1999-01-01

    Sensitivity of the zones of transport to change in the discharge rate of the selected well, porosity, and hydraulic conductivity, as well as to the presence or absence of interfering wells, was evaluated at six well sites to evaluate the effect of uncertainties in these factors on the size and shape of zones of transport. Uncertainty in porosity contributed the most to the uncertainty in delineating the zones of transport. Uncertainty in other factors, such as well discharge rate and horizontal hydraulic conductivity, had measurable effects on the zones of transport, but errors introduced through these factors were less significant. Insight into the causes of the changes in the size and shape of the zones of transport to varying conditions was gained by evaluating the simulated water budget and ground-water levels in the vicinity of the well. Changes in the simulated water budget and ground-water levels provided information to better understand the effects of uncertainties in the data on simulation results.The results of this study suggest that ground-water velocity is the underlying control on the size of the zones of transport. The regional hydraulic gradient is the most significant factor controlling the shape and orientation of the zones of transport. Spatial variation in recharge, discharge, and hydraulic properties can also affect the shape of the zones of transport, however. Underestimation of porosity or overestimation of horizontal hydraulic conductivity leads to overestimation of ground-water velocity and overestimation of the size of zones of transport. Overestimation of porosity or underestimation of horizontal hydraulic conductivity leads to underestimation of ground-water velocity and underestimation of the size of zones of transport. Well discharge rate affects ground-water velocities near the well. Underestimation of discharge (and therefore velocities) will result in underestimation of the size of the zones of transport. The sensitivity of

  19. Twin Convergence Zones

    NASA Technical Reports Server (NTRS)

    2002-01-01

    NASA's QuikSCAT satellite has confirmed a 30-year old largely unproven theory that there are two areas near the equator where the winds converge year after year and drive ocean circulation south of the equator. By analyzing winds, QuikSCAT has found a year-round southern and northern Intertropical Convergence Zone. This find is important to climate modelers and weather forecasters because it provides more detail on how the oceans and atmosphere interact near the equator. The Intertropical Convergence Zone (ITCZ) is the region that circles the Earth near the equator, where the trade winds of both the Northern and Southern Hemispheres come together. North of the equator, strong sun and warm water of the equator heats the air in the ITCZ, drawing air in from north and south and causing the air to rise. As the air rises it cools, releasing the accumulated moisture in an almost perpetual series of thunderstorms. Satellite data, however, has confirmed that there is an ITCZ north of the equator and a parallel ITCZ south of the equator. Variation in the location of the ITCZ is important to people around the world because it affects the north-south atmospheric circulation, which redistributes energy. It drastically affects rainfall in many equatorial nations, resulting in the wet and dry seasons of the tropics rather than the cold and warm seasons of higher latitudes. Longer term changes in the ITCZ can result in severe droughts or flooding in nearby areas. 'The double ITCZ is usually only identified in the Pacific and Atlantic Oceans on a limited and seasonal basis,' said Timothy Liu, of NASA's Jet Propulsion Laboratory and California Institute of Technology, Pasadena, Calif., and lead researcher on the project. In the eastern Pacific Ocean, the southern ITCZ is usually seen springtime. In the western Atlantic Ocean, the southern ITCZ was recently clearly identified only in the summertime. However, QuikSCAT's wind data has seen the southern ITCZ in all seasons across the

  20. 32 CFR 643.33 - Policy-Coastal zone management.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 4 2014-07-01 2013-07-01 true Policy-Coastal zone management. 643.33 Section... affecting land or water uses in the coastal zone of a state will include a certification that the proposed... manner consistent with the law. (c) An activity affecting land or water uses in the coastal zone of...

  1. Influence of soil and climate on root zone storage capacity

    NASA Astrophysics Data System (ADS)

    Euser, Tanja; McMillan, Hilary; Hrachowitz, Markus; Winsemius, Hessel; Savenije, Hubert

    2015-04-01

    The root zone water storage capacity (Sr) of a catchment is an important variable for the hydrological behaviour of a catchment; it strongly influences the storage, transpiration and runoff generation in an area. However, the root zone storage capacity is largely heterogeneous and not measurable. There are different theories about the variables affecting the root zone storage capacity; among the most debated are soil, vegetation and climate. The effect of vegetation and soil is often accounted for by detailed soil and land use maps. To investigate the effect of climate on the root zone storage capacity, an analogue can be made between the root zone storage capacity of a catchment and the human habit to design and construct reservoirs: both storage capacities help to overcome a dry period of a certain length. Humans often use the mass curve technique to determine the required storage needed to design the reservoir capacity. This mass curve technique can also be used to derive the root zone storage capacity created by vegetation in a certain ecosystem and climate (Gao et al., 2014). Only precipitation and discharge or evaporation data are required for this method. This study tests whether Sr values derived by both the mass curve technique and from soil maps are comparable for a range of catchments in New Zealand. Catchments are selected over a gradient of climates and land use. Special focus lies on how Sr values derived for a larger catchment are representative for smaller nested catchments. The spatial differences are examined between values derived from soil data and from climate and flow data. Gao, H., Hrachowitz, M., Schymanski, S.J., Fenicia, F., Sriwongsitanon, N., Savenije, H.H.G, (2014): Climate controls how ecosystems size the root zone storage capacity at catchment scale. DOI: 10.1002/2014GL061668

  2. Influence of carbonate facies on fault zone architecture

    NASA Astrophysics Data System (ADS)

    Michie, E. A. H.; Haines, T. J.; Healy, D.; Neilson, J. E.; Timms, N. E.; Wibberley, C. A. J.

    2014-08-01

    Normal faults on Malta were studied to analyse fault propagation and evolution in different carbonate facies. Deformation of carbonate facies is controlled by strength, particle size and pore structure. Different deformation styles influence the damage characteristics surrounding faults, and therefore the fault zone architecture. The carbonates were divided into grain- and micrite-dominated carbonate lithofacies. Stronger grain-dominated carbonates show localised deformation, whereas weaker micrite-dominated carbonates show distributed deformation. The weaker micrite-dominated carbonates overlie stronger grain-dominated carbonates, creating a mechanical stratigraphy. A different architecture of damage, the ‘Fracture Splay Zone’ (FSZ), is produced within micrite-dominated carbonates due to this mechanical stratigraphy. Strain accumulates at the point of juxtaposition between the stronger grain-dominated carbonates in the footwall block and the weaker micrite-dominated carbonates in the hanging wall block. New slip surfaces nucleate and grow from these points, developing an asymmetric fault damage zone segment. The development of more slip surfaces within a single fault zone forms a zone of intense deformation, bound between two slip surfaces within the micrite-dominated carbonate lithofacies (i.e., the FSZ). Rather than localisation onto a single slip surface, allowing formation of a continuous fault core, the deformation will be dispersed along several slip surfaces. The dispersed deformation can create a highly permeable zone, rather than a baffle/seal, in the micrite-dominated carbonate lithofacies. The formation of a Fracture Splay Zone will therefore affect the sealing potential of the fault zone. The FSZ, by contrast, is not observed in the majority of the grain-dominated carbonates.

  3. The effects of heterogeneities and loading conditions in the development of shear zones

    NASA Astrophysics Data System (ADS)

    Morales, Luiz F. G.; Rybacki, Erik; Dresen, Georg

    2016-04-01

    Shear zones are regions of localized deformation and are frequently nucleated by material and/or structural heterogeneities and may develop under transient boundary conditions of strain rate and stress. Here we investigate shear zone nucleation and development due to mechanical heterogeneities. Experiments were performed in constant twist rate (CTR) and constant torque (CT) torsion tests to simulate the end member conditions of constant strain rate and constant stress. We have used hollow cylinders of Carrara marble samples containing weak inclusions of Solnhofen limestone. The experiments were conducted in a Paterson-type gas deformation apparatus at 900 °C temperature and 400 MPa confining pressure to maximum bulk shear strains of 3. Peak shear stress was about 20 MPa for all the samples, followed by smooth weakening and steady state behavior. The strain is predominantly localized in the host marble within the process zone in front of the inclusion, defined by a zone of intense grain size reduction due to dynamic recrystallization. Local shear strain values in the process zone are between 5 to 10 times higher than the bulk applied strain. In CT experiments, a narrow shear zone marked by intense grain size reduction is developed in front of the inclusion and the surrounding material remains relatively intact, whereas in CTR experiments the deformation is more widely distributed. The volume of recrystallized grains is nevertheless similar in the samples deformed at same bulk strains in both CT and CTR. At similar bulk strain, the crystallographic preferred orientation (CPO) in the process zone of CT experiments is stronger than in CTR experiments and CPO strength varies with grain size. Our observations suggest that the initial formation and transient deformation of shear zones is strongly affected by loading conditions.

  4. 19 CFR 146.7 - Zone changes.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... the risk and expense of the operator. The port director may require an accounting of all merchandise... surety; or (4) for any other reason that substantially affects the liability of the operator under the... (CONTINUED) FOREIGN TRADE ZONES General Provisions § 146.7 Zone changes. (a) Alteration of an activated...

  5. Growth dynamics of the seagrass Zostera japonica at its upper and lower distributional limits in the intertidal zone

    NASA Astrophysics Data System (ADS)

    Kim, Jong-Hyeob; Kim, Seung Hyeon; Kim, Young Kyun; Park, Jung-Im; Lee, Kun-Seop

    2016-06-01

    The seagrass Zostera japonica occurs mainly in the intertidal zone and is thus exposed to widely varying environmental conditions affecting its growth and distribution compared to subtidal seagrasses. The growth dynamics of Z. japonica at its upper and lower distributional limits in the intertidal zone were investigated in Koje Bay on the southern coast of Korea to examine the environmental stresses and limiting factors on the growth of intertidal seagrasses. The shoot density and morphology, biomass, and leaf productivity of Z. japonica were measured in relation to coincident measurements of environmental factors at its upper and lower distributional limits and in an intermediate zone of the intertidal area. The mean exposure time to the atmosphere during low tide in the upper intertidal zone was approximately 1.5- and 1.9-fold longer than that in the intermediate and lower intertidal zones, respectively. Shoot density and biomass were significantly higher in the intermediate zone than at the upper and lower distributional limits. Longer emersion leading to a various of environmental stresses appeared to reduce Z. japonica growth in the upper intertidal zone, whereas interspecific competitive interactions related to irradiance seemed to affect Z. japonica growth in the lower intertidal zone. Shoot size, density, biomass, and leaf productivity were lower in the upper than in the lower zone, implying that emersion-associated stresses in the upper zone had a greater detrimental effect on Z. japonica growth than did stresses occurring in the lower zone. The productivity of Z. japonica showed strong positive correlations with air and water temperature, suggesting enhancement of Z. japonica production at higher temperatures. Thus, the predicted increases in air and water temperature associated with global climate change might have positive effects on the growth and extension in distributional range of this species.

  6. Zone separator for multiple zone vessels

    DOEpatents

    Jones, John B.

    1983-02-01

    A solids-gas contact vessel, having two vertically disposed distinct reaction zones, includes a dynamic seal passing solids from an upper to a lower zone and maintaining a gas seal against the transfer of the separate treating gases from one zone to the other, and including a stream of sealing fluid at the seal.

  7. Class Size.

    ERIC Educational Resources Information Center

    Underwood, Siobhan; Lumsden, Linda S.

    1994-01-01

    The items featured in this annotated bibliography touch on several aspects of the multifaceted class-size debate. Allen Odden reviews the literature and contends that class-size reduction should be used "sparingly and strategically." C. M. Achilles and colleagues examines two different class-size situations and find student test performance in the…

  8. Class Size.

    ERIC Educational Resources Information Center

    Johnston, Holly R.

    Exploring the class-size issue, this paper focuses on the primary grades and asks questions such as "does a reduction in class size promote an increase in academic achievement?" and "how substantial does the reduction in numbers have to be in order for a significant increase to occur?" The paper surveys debates on class size and the social factors…

  9. Saturated Zone Colloid Transport

    SciTech Connect

    H. S. Viswanathan

    2004-10-07

    This scientific analysis provides retardation factors for colloids transporting in the saturated zone (SZ) and the unsaturated zone (UZ). These retardation factors represent the reversible chemical and physical filtration of colloids in the SZ. The value of the colloid retardation factor, R{sub col} is dependent on several factors, such as colloid size, colloid type, and geochemical conditions (e.g., pH, Eh, and ionic strength). These factors are folded into the distributions of R{sub col} that have been developed from field and experimental data collected under varying geochemical conditions with different colloid types and sizes. Attachment rate constants, k{sub att}, and detachment rate constants, k{sub det}, of colloids to the fracture surface have been measured for the fractured volcanics, and separate R{sub col} uncertainty distributions have been developed for attachment and detachment to clastic material and mineral grains in the alluvium. Radionuclides such as plutonium and americium sorb mostly (90 to 99 percent) irreversibly to colloids (BSC 2004 [DIRS 170025], Section 6.3.3.2). The colloid retardation factors developed in this analysis are needed to simulate the transport of radionuclides that are irreversibly sorbed onto colloids; this transport is discussed in the model report ''Site-Scale Saturated Zone Transport'' (BSC 2004 [DIRS 170036]). Although it is not exclusive to any particular radionuclide release scenario, this scientific analysis especially addresses those scenarios pertaining to evidence from waste-degradation experiments, which indicate that plutonium and americium may be irreversibly attached to colloids for the time scales of interest. A section of this report will also discuss the validity of using microspheres as analogs to colloids in some of the lab and field experiments used to obtain the colloid retardation factors. In addition, a small fraction of colloids travels with the groundwater without any significant retardation

  10. Predicting km-scale shear zone formation

    NASA Astrophysics Data System (ADS)

    Gerbi, Christopher; Culshaw, Nicholas; Shulman, Deborah; Foley, Maura; Marsh, Jeffrey

    2015-04-01

    Because km-scale shear zones play a first-order role in lithospheric kinematics, accurate conceptual and numerical models of orogenic development require predicting when and where they form. Although a strain-based algorithm in the upper crust for weakening due to faulting appears to succeed (e.g., Koons et al., 2010, doi:10.1029/2009TC002463), a comparable general rule for the viscous crust remains unestablished. Here we consider two aspects of the geological argument for a similar algorithm in the viscous regime, namely (1) whether predicting km-scale shear zone development based on a single parameter (such as strain or shear heating) is reasonable; and (2) whether lithologic variability inherent in most orogenic systems precludes a simple predictive rule. A review of tectonically significant shear zones worldwide and more detailed investigations in the Central Gneiss belt of the Ontario segment of the Grenville Province reveals that most km-scale shear zones occur at lithological boundaries and involve mass transfer, but have fairly little else in common. As examples, the relatively flat-lying Twelve Mile Bay shear zone in the western Central Gneiss belt bounds the Parry Sound domain and is likely the product of both localized anatexis and later retrograde hydration with attendant metamorphism. Moderately dipping shear zones in granitoids of the Grenville Front Tectonic Zone apparently resulted from cooperation among several complementary microstructural processes, such as grain size reduction, enhanced diffusion, and a small degree of metamorphic reaction. Localization into shear zones requires the operation of some spatially restricted processes such as stress concentration, metamorphism/fluid access, textural evolution, and thermal perturbation. All of these could be due in part to strain, but not necessarily linearly related to strain. Stress concentrations, such as those that form at rheological boundaries, may be sufficient to nucleate high strain

  11. Climate change and dead zones.

    PubMed

    Altieri, Andrew H; Gedan, Keryn B

    2015-04-01

    Estuaries and coastal seas provide valuable ecosystem services but are particularly vulnerable to the co-occurring threats of climate change and oxygen-depleted dead zones. We analyzed the severity of climate change predicted for existing dead zones, and found that 94% of dead zones are in regions that will experience at least a 2 °C temperature increase by the end of the century. We then reviewed how climate change will exacerbate hypoxic conditions through oceanographic, ecological, and physiological processes. We found evidence that suggests numerous climate variables including temperature, ocean acidification, sea-level rise, precipitation, wind, and storm patterns will affect dead zones, and that each of those factors has the potential to act through multiple pathways on both oxygen availability and ecological responses to hypoxia. Given the variety and strength of the mechanisms by which climate change exacerbates hypoxia, and the rates at which climate is changing, we posit that climate change variables are contributing to the dead zone epidemic by acting synergistically with one another and with recognized anthropogenic triggers of hypoxia including eutrophication. This suggests that a multidisciplinary, integrated approach that considers the full range of climate variables is needed to track and potentially reverse the spread of dead zones. PMID:25385668

  12. Spacecraft particulate sizing spectrometer

    NASA Technical Reports Server (NTRS)

    Miranda, Henry A., Jr.

    1992-01-01

    An evaluation prototype device is described, together with conclusions and several recommendations for follow-on flight hardware. The device detects individual particles crossing an external sensing zone, and produces a histogram displaying the size distribution of particles sensed, over the nominal range of 5 to 50 microns. The output is totally independent of the particle refractive index, and is also largely unaffected by particle shape. The reported diameters are in terms of the equivalent sphere, as judged by the scattered light intercepted by the receiving channels, which develop signals whenever a particle crosses the beam of illumination in the sensing zone. Supporting evidence for the latter assertion is discussed on the basis of experimental test data for non-spherical particulates. Also included is a technical appendix which presents theoretical arguments that provide a firm foundation for this assertion.

  13. 76 FR 63202 - Security Zones; Captain of the Port Lake Michigan Zone

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-10-12

    ... rulemaking entitled Security Zones; Captain of the Port Lake Michigan Zone in the Federal Register (76 FR... determined that to better protect such infrastructure, while also mitigating burdens on waterway users, it is... while also mitigating burdens on waterway users it is necessary to reduce the size of an...

  14. Fracture process zone in granite

    USGS Publications Warehouse

    Zang, A.; Wagner, F.C.; Stanchits, S.; Janssen, C.; Dresen, G.

    2000-01-01

    In uniaxial compression tests performed on Aue granite cores (diameter 50 mm, length 100 mm), a steel loading plate was used to induce the formation of a discrete shear fracture. A zone of distributed microcracks surrounds the tip of the propagating fracture. This process zone is imaged by locating acoustic emission events using 12 piezoceramic sensors attached to the samples. Propagation velocity of the process zone is varied by using the rate of acoustic emissions to control the applied axial force. The resulting velocities range from 2 mm/s in displacement-controlled tests to 2 ??m/s in tests controlled by acoustic emission rate. Wave velocities and amplitudes are monitored during fault formation. P waves transmitted through the approaching process zone show a drop in amplitude of 26 dB, and ultrasonic velocities are reduced by 10%. The width of the process zone is ???9 times the grain diameter inferred from acoustic data but is only 2 times the grain size from optical crack inspection. The process zone of fast propagating fractures is wider than for slow ones. The density of microcracks and acoustic emissions increases approaching the main fracture. Shear displacement scales linearly with fracture length. Fault plane solutions from acoustic events show similar orientation of nodal planes on both sides of the shear fracture. The ratio of the process zone width to the fault length in Aue granite ranges from 0.01 to 0.1 inferred from crack data and acoustic emissions, respectively. The fracture surface energy is estimated from microstructure analysis to be ???2 J. A lower bound estimate for the energy dissipated by acoustic events is 0.1 J. Copyright 2000 by the American Geophysical Union.

  15. Tissue and size-related changes in the fatty acid and stable isotope signatures of the deep sea grenadier fish Coryphaenoides armatus from the Charlie-Gibbs Fracture Zone region of the Mid-Atlantic Ridge

    NASA Astrophysics Data System (ADS)

    Mayor, Daniel J.; Sharples, Caroline J.; Webster, Lynda; Walsham, Pamela; Lacaze, Jean-Pierre; Cousins, Nicola J.

    2013-12-01

    Coryphaenoides armatus is a cosmopolitan deep-sea fish that plays a major role in the ecology of abyssal ecosystems. We investigated the trophic ecology and physiology of this species by determining the δ13C, δ15N and fatty acid signatures of muscle, liver and ovary tissues of individuals collected from ∼2700 m to the north and south of the Charlie-Gibbs Fracture Zone (CGFZ) of the Mid-Atlantic Ridge, NE Atlantic. Fatty acid and δ13C data both suggested that C. armatus shows an ontogenetic dietary shift, with the relative contributions of benthic and pelagic prey decreasing and increasing respectively as the animals grow. They also indicated that dietary overlap between animals living to the north and south of the CGFZ increases as they grow, suggesting that larger animals forage over greater distances and are not hindered by the presence of the CGFZ. Comparison of tissue-specific fatty acid signatures with previously published data suggests compositional homeostasis of the fatty acids 20:5(n-3) and 22:6(n-3) in the muscle, and 18:1(n-9) in the liver tissues. We ascribe this primarily to strict physiological requirements for these compounds, rather than simply to their abundance in the diet. We pose several speculative mechanisms to explain the observed trends in tissue-specific δ13C and δ15N values, illustrating some of the numerous processes that can influence the isotopic signatures of bulk tissues.

  16. Vadose zone microbiology

    SciTech Connect

    Kieft, Thomas L.; Brockman, Fred J.

    2001-01-17

    The vadose zone is defined as the portion of the terrestrial subsurface that extends from the land surface downward to the water table. As such, it comprises the surface soil (the rooting zone), the underlying subsoil, and the capillary fringe that directly overlies the water table. The unsaturated zone between the rooting zone and the capillary fringe is termed the "intermediate zone" (Chapelle, 1993). The vadose zone has also been defined as the unsaturated zone, since the sediment pores and/or rock fractures are generally not completely water filled, but instead contain both water and air. The latter characteristic results in the term "zone of aeration" to describe the vadose zone. The terms "vadose zone," "unsaturated zone", and "zone of aeration" are nearly synonymous, except that the vadose zone may contain regions of perched water that are actually saturated. The term "subsoil" has also been used for studies of shallow areas of the subsurface immediately below the rooting zone. This review focuses almost exclusively on the unsaturated region beneath the soil layer since there is already an extensive body of literature on surface soil microbial communities and process, e.g., Paul and Clark (1989), Metting (1993), Richter and Markowitz, (1995), and Sylvia et al. (1998); whereas the deeper strata of the unsaturated zone have only recently come under scrutiny for their microbiological properties.

  17. [Dynamics of Radioecological State of the Fresh-Water Ecosystems Affected by a Long-Term Impact from Nuclear Power Plant in the Frontiers of the Zone under Observation].

    PubMed

    Trapeznikov, A V; Trapeznikova, V N; Korjavin, A V

    2015-01-01

    The results of radioecological studies of six small rivers situated in the surveillance zone of the Beloyarskaya NPP (BNPP) and around the cooling pond of the power plant are presented. 21 radionuclides and the total α- and β-activity were studied in the main components of the aquatic ecosystems. It is shown that after the 1st and 2nd BN PP blocks decommissioning the content of 60Co and 137Cs in the Beloyarskoye storage pond water, sediments, fish fauna and macrophytes dropped tens and hundreds of times. The fundamental importance of this fact is that in a large range of time the aquatic ecosystem mechanism of self-purification from radionuclides is working due to radioactive substances decay as well as redistribution of radionuclides from water to other components, primarily to the sediments. Of 6 small rivers the maximum levels of radioactive substances is found in the river Olkhovka, which for several years has been subjected to the low-level radioactive water discharges from Beloyarskaya NPP. The radionuclide content in the main components of the aquatic ecosystems of the other five rivers studied after BNPP 47-year operation period corresponds to the regional background. PMID:26310022

  18. Kepler Discovers Earth-size Planet Candidates

    NASA Video Gallery

    NASA's Kepler mission has discovered its first Earth-size planet candidates and its first candidates in the habitable zone, a region where liquid water could exist on a planet's surface. Five of th...

  19. Pan-European Chikungunya surveillance: designing risk stratified surveillance zones.

    PubMed

    Tilston, Natasha; Skelly, Chris; Weinstein, Phil

    2009-01-01

    The first documented transmission of Chikungunya within Europe took place in Italy during the summer of 2007. Chikungunya, a viral infection affecting millions of people across Africa and Asia, can be debilitating and no prophylactic treatment exists. Although imported cases are reported frequently across Europe, 2007 was the first confirmed European outbreak and available evidence suggests that Aedes albopictus was the vector responsible and the index case was a visitor from India. This paper proposed pan-European surveillance zones for Chikungunya, based on the climatic conditions necessary for vector activity and viral transmission. Pan-European surveillance provides the best hope for an early-warning of outbreaks, because national boundaries do not play a role in defining the risk of this new vector borne disease threat. A review of climates, where Chikungunya has been active, was used to inform the delineation of three pan-European surveillance zones. These vary in size each month across the June-September period of greatest risk. The zones stretch across southern Europe from Portugal to Turkey. Although the focus of this study was to define the geography of potential surveillance zones based on the climatic limits on the vector and virus, a preliminary examination of inward bound airline passengers was also undertaken. This indicated that France and Italy are likely to be at greater risk due to the number of visitors they receive from Chikungunya active regions, principally viraemic visitors from India. Therefore this study represents a first attempt at creating risk stratified surveillance zones, which we believe could be usefully refined with the use of higher resolution climate data and more complete air travel data. PMID:19878588

  20. Conservation of the Red Kite Milvus milvus (Aves: Accipitriformes) Is Not Affected by the Establishment of a Broad Hybrid Zone with the Black Kite Milvus migrans migrans in Central Europe.

    PubMed

    Heneberg, Petr; Dolinay, Matej; Matušík, Hynek; Pfeiffer, Thomas; Nachtigall, Winfried; Bizos, Jiří; Šimčíková, Daniela; Literák, Ivan

    2016-01-01

    Among Accipitriformes sensu stricto, only a few species have been reported to form hybrid zones; these include the red kite Milvus milvus and black kite Milvus migrans migrans. M. milvus is endemic to the western Palearctic and has an estimated total population of 20-24,000 breeding pairs. The species was in decline until the 1970s due to persecution and has declined again since the 1990s due to ingestion of rodenticide-treated baits, illegal poisoning and changes in agricultural practices, particularly in its core range. Whereas F1 M. milvus × M. migr. migrans hybrid offspring have been found, F2 and F3 hybrids have only rarely been reported, with low nesting success rates of F1 hybrids and partial hybrid sterility likely playing a role. Here, we analyzed the mitochondrial (CO1 and CytB) and nuclear (Myc) DNA loci of 184 M. milvus, 124 M. migr. migrans and 3 F1 hybrid individuals collected across central Europe. In agreement with previous studies, we found low heterozygosity in M. milvus regardless of locus. We found that populations of both examined species were characterized by a high gene flow within populations, with all of the major haplotypes distributed across the entire examined area. Few haplotypes displayed statistically significant aggregation in one region over another. We did not find mitochondrial DNA of one species in individuals with the plumage of the other species, except in F1 hybrids, which agrees with Haldane´s Rule. It remains to be investigated by genomic methods whether occasional gene flow occurs through the paternal line, as the examined Myc gene displayed only marginal divergence between M. milvus and M. migr. migrans. The central European population of M. milvus is clearly subject to free intraspecific gene flow, which has direct implications when considering the origin of individuals in M. milvus re-introduction programs. PMID:27463515

  1. Conservation of the Red Kite Milvus milvus (Aves: Accipitriformes) Is Not Affected by the Establishment of a Broad Hybrid Zone with the Black Kite Milvus migrans migrans in Central Europe

    PubMed Central

    Matušík, Hynek; Pfeiffer, Thomas; Nachtigall, Winfried; Bizos, Jiří; Šimčíková, Daniela; Literák, Ivan

    2016-01-01

    Among Accipitriformes sensu stricto, only a few species have been reported to form hybrid zones; these include the red kite Milvus milvus and black kite Milvus migrans migrans. M. milvus is endemic to the western Palearctic and has an estimated total population of 20–24,000 breeding pairs. The species was in decline until the 1970s due to persecution and has declined again since the 1990s due to ingestion of rodenticide-treated baits, illegal poisoning and changes in agricultural practices, particularly in its core range. Whereas F1 M. milvus × M. migr. migrans hybrid offspring have been found, F2 and F3 hybrids have only rarely been reported, with low nesting success rates of F1 hybrids and partial hybrid sterility likely playing a role. Here, we analyzed the mitochondrial (CO1 and CytB) and nuclear (Myc) DNA loci of 184 M. milvus, 124 M. migr. migrans and 3 F1 hybrid individuals collected across central Europe. In agreement with previous studies, we found low heterozygosity in M. milvus regardless of locus. We found that populations of both examined species were characterized by a high gene flow within populations, with all of the major haplotypes distributed across the entire examined area. Few haplotypes displayed statistically significant aggregation in one region over another. We did not find mitochondrial DNA of one species in individuals with the plumage of the other species, except in F1 hybrids, which agrees with Haldane´s Rule. It remains to be investigated by genomic methods whether occasional gene flow occurs through the paternal line, as the examined Myc gene displayed only marginal divergence between M. milvus and M. migr. migrans. The central European population of M. milvus is clearly subject to free intraspecific gene flow, which has direct implications when considering the origin of individuals in M. milvus re-introduction programs. PMID:27463515

  2. Exploring Size.

    ERIC Educational Resources Information Center

    Brand, Judith, Ed.

    1995-01-01

    "Exploring" is a magazine of science, art, and human perception that communicates ideas museum exhibits cannot demonstrate easily by using experiments and activities for the classroom. This issue concentrates on size, examining it from a variety of viewpoints. The focus allows students to investigate and discuss interconnections among apparently…

  3. Coupled surface-subsurface hydrologic measurements reveal infiltration, recharge, and discharge dynamics across the swash zone of a sandy beach