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1

Assuring Life in Composite Systems  

NASA Technical Reports Server (NTRS)

A computational simulation method is presented to assure life in composite systems by using dynamic buckling of smart composite shells as an example. The combined use of composite mechanics, finite element computer codes, and probabilistic analysis enable the effective assessment of the dynamic buckling load of smart composite shells. A universal plot is generated to estimate the dynamic buckling load of composite shells at various load rates and probabilities. The shell structure is also evaluated with smart fibers embedded in the plies right below the outer plies. The results show that, on the average, the use of smart fibers improved the shell buckling resistance by about 9% at different probabilities and delayed the buckling occurrence time. The probabilistic sensitivities results indicate that uncertainties in the fiber volume ratio and ply thickness have major effects on the buckling load. The uncertainties in the electric field strength and smart material volume fraction have moderate effects and thereby in the assured life of the shell.

Chamis, Christos c.

2008-01-01

2

SPECIES COMPOSITION, DISTRIBUTION, LIFE FORMS AND FOLK NOMENCLATURE OF FOREST AND COMMON LAND PLANTS OF WESTERN CHITWAN, NEPAL  

PubMed Central

This paper enumerates 349 plant species belonging to 77 families of vascular plants collected in the winter seasons of 1996 and 2000 by the flora teams of the Population and Ecology Research Laboratory, Nepal. Of the total species, 249 species belong to dicotyledons, 87 species to monocotyledons and 13 species to pteridophytes. Among the families, dicotyledons contributed the highest number of families (55 in number) followed by monocotyledons and pteridophytes. In the study areas, species composition varies with the type of habitats in the study plots. Some species are unique in distribution. The highest unique species are contributed by common lands (87 spp.), followed by the Chitwan National Park forest (36 spp.) and Tikauli forest (32 spp.). Ageratum houstonianum Mill., Cynodon dactylon (L.) Pers., Imperata cylindrica (L.) Beauv., Rungia parviflora (Retz.) Nees, Saccharum spontaneum L. and Thelypteris auriculata (J. Sm.) K. Iwats are the most common species across all the research blocks. Of the listed plants, many plants have local names either in Nepalese or other tribal languages. Plants are named in different ways on the basis of habit, habitat, smell, taste, and morphological characters of the plants, which are also the basis of nomenclature in plant taxonomy. PMID:22962539

Dangol, D. R.

2012-01-01

3

Effect of Individual Component Life Distribution on Engine Life Prediction  

NASA Technical Reports Server (NTRS)

The effect of individual engine component life distributions on engine life prediction was determined. A Weibull-based life and reliability analysis of the NASA Energy Efficient Engine was conducted. The engine s life at a 95 and 99.9 percent probability of survival was determined based upon the engine manufacturer s original life calculations and assumed values of each of the component s cumulative life distributions as represented by a Weibull slope. The lives of the high-pressure turbine (HPT) disks and blades were also evaluated individually and as a system in a similar manner. Knowing the statistical cumulative distribution of each engine component with reasonable engineering certainty is a condition precedent to predicting the life and reliability of an entire engine. The life of a system at a given reliability will be less than the lowest-lived component in the system at the same reliability (probability of survival). Where Weibull slopes of all the engine components are equal, the Weibull slope had a minimal effect on engine L(sub 0.1) life prediction. However, at a probability of survival of 95 percent (L(sub 5) life), life decreased with increasing Weibull slope.

Zaretsky, Erwin V.; Hendricks, Robert C.; Soditus, Sherry M.

2003-01-01

4

Estimating Linear Models for Compositional Distributional Semantics  

Microsoft Academic Search

In distributional semantics studies, there is a growing attention in compositionally determining the distributional meaning of word sequences. Yet, compositional dis- tributional models depend on a large set of parameters that have not been explored. In this paper we propose a novel approach to estimate parameters for a class of com- positional distributional models: the addi- tive models. Our approach

Fabio Massimo Zanzotto; Ioannis Korkontzelos; Francesca Fallucchi; Suresh Manandhar

2010-01-01

5

A distributed program composition system  

NASA Technical Reports Server (NTRS)

A graphical technique for creating distributed computer programs is investigated and a prototype implementation is described which serves as a testbed for the concepts. The type of programs under examination is restricted to those comprising relatively heavyweight parts that intercommunicate by passing messages of typed objects. Such programs are often presented visually as a directed graph with computer program parts as the nodes and communication channels as the edges. This class of programs, called parts-based programs, is not well supported by existing computer systems; much manual work is required to describe the program to the system, establish the communication paths, accommodate the heterogeneity of data types, and to locate the parts of the program on the various systems involved. The work described solves most of these problems by providing an interface for describing parts-based programs in this class in a way that closely models the way programmers think about them: using sketches of diagraphs. Program parts, the computational modes of the larger program system are categorized in libraries and are accessed with browsers. The process of programming has the programmer draw the program graph interactively. Heterogeneity is automatically accommodated by the insertion of type translators where necessary between the parts. Many decisions are necessary in the creation of a comprehensive tool for interactive creation of programs in this class. Possibilities are explored and the issues behind such decisions are presented. An approach to program composition is described, not a carefully implemented programming environment. However, a prototype implementation is described that can demonstrate the ideas presented.

Brown, Robert L.

1989-01-01

6

Fatigue Life Methodology for Bonded Composite Skin/Stringer Configurations  

NASA Technical Reports Server (NTRS)

A methodology is presented for determining the fatigue life of composite structures based on fatigue characterization data and geometric nonlinear finite element (FE) analyses. To demonstrate the approach, predicted results were compared to fatigue tests performed on specimens which represented a tapered composite flange bonded onto a composite skin. In a first step, tension tests were performed to evaluate the debonding mechanisms between the flange and the skin. In a second step, a 2D FE model was developed to analyze the tests. To predict matrix cracking onset, the relationship between the tension load and the maximum principal stresses transverse to the fiber direction was determined through FE analysis. Transverse tension fatigue life data were used to -enerate an onset fatigue life P-N curve for matrix cracking. The resulting prediction was in good agreement with data from the fatigue tests. In a third step, a fracture mechanics approach based on FE analysis was used to determine the relationship between the tension load and the critical energy release rate. Mixed mode energy release rate fatigue life data were used to create a fatigue life onset G-N curve for delamination. The resulting prediction was in good agreement with data from the fatigue tests. Further, the prediction curve for cumulative life to failure was generated from the previous onset fatigue life curves. The results showed that the methodology offers a significant potential to Predict cumulative fatigue life of composite structures.

Krueger, Ronald; Paris, Isabelle L.; OBrien, T. Kevin; Minguet, Pierre J.

2001-01-01

7

Considerations concerning fatigue life of metal matrix composites  

NASA Technical Reports Server (NTRS)

Since metal matrix composites (MMC) are composed from two very distinct materials each having their own physical and mechanical properties, it is feasible that the fatigue resistance depends on the strength of the weaker constituent. Based on this assumption, isothermal fatigue lives of several MMC's were analyzed utilizing a fatigue life diagram approach. For each MMC, the fatigue life diagram was quantified using the mechanical properties of its constituents. The fatigue life regions controlled by fiber fracture and matrix were also quantitatively defined.

Radhakrishnan, V. M.; Bartolotta, Paul A.

1993-01-01

8

Life prediction of short fiber composites  

Microsoft Academic Search

A procedure is described for estimating the fatigue lives (i.e. the number of cycles to failure) of parts made of short fiber reinforced thermoplastic matrix composites. First, S-N curves were generated at stress ratios of R = 0 and R = -1 for short glass fiber reinforced Copolyamide coupons with 0° (30% or 50% fiber content by weight), 45° (50%

Alessandro Zago

2002-01-01

9

Fatigue Life Methodology for Bonded Composite Skin/Stringer Configurations  

NASA Technical Reports Server (NTRS)

A methodology is presented for determining the fatigue life of bonded composite skin/stringer structures based on delamination fatigue characterization data and geometric nonlinear finite element analyses. Results were compared to fatigue tests on stringer flange/skin specimens to verify the approach.

Krueger, Ronald; Paris, Isabelle L.; OBrien, T. Kevin

2000-01-01

10

Durability/life of fiber composites in hygrothermomechanical environments  

NASA Technical Reports Server (NTRS)

Statistical analysis and multiple regression were used to determine and quantify the significant hygrothermomechanical variables which infuence the tensile durability/life (cycle loading, fatigue) of boron-fiber/epoxy-matrix (B/E) and high-modulus-fiber/epoxy-matrix (HMS/E) composites. The use of the multiple regression analysis reduced the variables from fifteen, assumed initially, to six or less with a probability of greater than 0.999. The reduced variables were used to derive predictive models for compression an intralaminar shear durability/life of B/E and HMS/E composites assuming isoparametric fatigue behavior. The predictive models were subsequently generalized to predict the durability/life of graphite-fiber-r generalized model is of simple form, predicts conservative values compared with measured data and should be adequate for use in preliminary designs.

Chamis, C. C.; Sinclair, J. H.

1981-01-01

11

Life prediction of short fiber composites  

NASA Astrophysics Data System (ADS)

A procedure is described for estimating the fatigue lives (i.e. the number of cycles to failure) of parts made of short fiber reinforced thermoplastic matrix composites. First, S-N curves were generated at stress ratios of R = 0 and R = -1 for short glass fiber reinforced Copolyamide coupons with 0° (30% or 50% fiber content by weight), 45° (50% fiber content) and 90° (30% or 50% fiber content) fiber orientations. Second, these S-N curves were compared to data reported in the literature for a wide range of short glass and short carbon fiber reinforced thermoplastics materials. On the basis of these comparison, all available data were "collapsed" on two S-N curves, one for R = 0 and one for R = -l. The fatigue lives of short fiber reinforced thermoplastics were modeled by a Generalized Miner's Rule. Tests were conducted measuring the fatigue lives of 150 by 10 by 2 mm short glass fiber reinforced Copolyamide coupons under different types of cyclic loads. The fatigue lives measured in these tests were compared to those provided by the Generalized Miner's Rule, and good agreements were found between the test and model results. The fatigue lives of two different parts (made of short glass fiber reinforced Copolyamide) were then investigated. The first one was a 150 by 10 by 4 mm coupon with a 2 mm hole at the center. The second one was an automotive gear shift link. The fiber orientations and the stresses inside these parts were calculated, respectively, by the commercial softwares C-Mold and by ABAQUS. The fatigue lives under different cyclic loads were measured; they were also calculated by the Generalized Miner's Rule together with the results of C-Mold and ABAQUS and the S-N data generated in this study. Comparisons between the measured and estimated (by the model) fatigue lives are in reasonable agreement, indicating that the procedure employed is a useful tool for estimating the fatigue lives of parts made of short fiber reinforced thermoplastics.

Zago, Alessandro

12

Fatigue life prediction of composite laminates by FEA simulation method  

Microsoft Academic Search

This paper is to simulate the fatigue damage evolution in composite laminates and predict fatigue life of the laminates with different lay-up sequences on the basis of the fatigue characteristics of longitudinal, transverse and in-plane shear directions by finite element analysis (FEA) method. In FEA model, considering the scatter of the material’s properties, each element was assigned with different material’s

Wei Lian; Weixing Yao

2010-01-01

13

A life prediction model for laminated composite structural components  

NASA Technical Reports Server (NTRS)

A life prediction methodology for laminated continuous fiber composites subjected to fatigue loading conditions was developed. A summary is presented of research completed. A phenomenological damage evolution law was formulated for matrix cracking which is independent of stacking sequence. Mechanistic and physical support was developed for the phenomenological evolution law proposed above. The damage evolution law proposed above was implemented to a finite element computer program. And preliminary predictions were obtained for a structural component undergoing fatigue loading induced damage.

Allen, David H.

1990-01-01

14

Dramatic increase in fatigue life in hierarchical graphene composites.  

PubMed

We report the synthesis and fatigue characterization of fiberglass/epoxy composites with various weight fractions of graphene platelets infiltrated into the epoxy resin as well as directly spray-coated on to the glass microfibers. Remarkably only ?0.2% (with respect to the epoxy resin weight and ?0.02% with respect to the entire laminate weight) of graphene additives enhanced the fatigue life of the composite in the flexural bending mode by up to 1200-fold. By contrast, under uniaxial tensile fatigue conditions, the graphene fillers resulted in ?3-5-fold increase in fatigue life. The fatigue life increase (in the flexural bending mode) with graphene additives was ?1-2 orders of magnitude superior to those obtained using carbon nanotubes. In situ ultrasound analysis of the nanocomposite during the cyclic fatigue test suggests that the graphene network toughens the fiberglass/epoxy-matrix interface and prevents the delamination/buckling of the glass microfibers under compressive stress. Such fatigue-resistant hierarchical materials show potential to improve the safety, reliability, and cost effectiveness of fiber-reinforced composites that are increasingly the material of choice in the aerospace, automotive, marine, sports, biomedical, and wind energy industries. PMID:20863061

Yavari, F; Rafiee, M A; Rafiee, J; Yu, Z-Z; Koratkar, N

2010-10-01

15

12 CFR 2.3 - Distribution of credit life insurance income.  

Code of Federal Regulations, 2013 CFR

...2013-01-01 false Distribution of credit life insurance income. 2.3 Section 2.3...DEPARTMENT OF THE TREASURY SALES OF CREDIT LIFE INSURANCE § 2.3 Distribution of credit life insurance income. (a) Distribution of...

2013-01-01

16

12 CFR 2.3 - Distribution of credit life insurance income.  

Code of Federal Regulations, 2012 CFR

...2012-01-01 false Distribution of credit life insurance income. 2.3 Section 2.3...DEPARTMENT OF THE TREASURY SALES OF CREDIT LIFE INSURANCE § 2.3 Distribution of credit life insurance income. (a) Distribution of...

2012-01-01

17

12 CFR 2.3 - Distribution of credit life insurance income.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Distribution of credit life insurance income. 2.3 Section 2.3...DEPARTMENT OF THE TREASURY SALES OF CREDIT LIFE INSURANCE § 2.3 Distribution of credit life insurance income. (a) Distribution of...

2010-01-01

18

12 CFR 2.3 - Distribution of credit life insurance income.  

Code of Federal Regulations, 2014 CFR

...2014-01-01 false Distribution of credit life insurance income. 2.3 Section 2.3...DEPARTMENT OF THE TREASURY SALES OF CREDIT LIFE INSURANCE § 2.3 Distribution of credit life insurance income. (a) Distribution of...

2014-01-01

19

12 CFR 2.3 - Distribution of credit life insurance income.  

Code of Federal Regulations, 2011 CFR

...2011-01-01 false Distribution of credit life insurance income. 2.3 Section 2.3...DEPARTMENT OF THE TREASURY SALES OF CREDIT LIFE INSURANCE § 2.3 Distribution of credit life insurance income. (a) Distribution of...

2011-01-01

20

Progressive Failure And Life Prediction of Ceramic and Textile Composites  

NASA Technical Reports Server (NTRS)

An engineering approach to predict the fatigue life and progressive failure of multilayered composite and textile laminates is presented. Analytical models which account for matrix cracking, statistical fiber failures and nonlinear stress-strain behavior have been developed for both composites and textiles. The analysis method is based on a combined micromechanics, fracture mechanics and failure statistics analysis. Experimentally derived empirical coefficients are used to account for the interface of fiber and matrix, fiber strength, and fiber-matrix stiffness reductions. Similar approaches were applied to textiles using Repeating Unit Cells. In composite fatigue analysis, Walker's equation is applied for matrix fatigue cracking and Heywood's formulation is used for fiber strength fatigue degradation. The analysis has been compared with experiment with good agreement. Comparisons were made with Graphite-Epoxy, C/SiC and Nicalon/CAS composite materials. For textile materials, comparisons were made with triaxial braided and plain weave materials under biaxial or uniaxial tension. Fatigue predictions were compared with test data obtained from plain weave C/SiC materials tested at AS&M. Computer codes were developed to perform the analysis. Composite Progressive Failure Analysis for Laminates is contained in the code CPFail. Micromechanics Analysis for Textile Composites is contained in the code MicroTex. Both codes were adapted to run as subroutines for the finite element code ABAQUS and CPFail-ABAQUS and MicroTex-ABAQUS. Graphic user interface (GUI) was developed to connect CPFail and MicroTex with ABAQUS.

Xue, David Y.; Shi, Yucheng; Katikala, Madhu; Johnston, William M., Jr.; Card, Michael F.

1998-01-01

21

Development of a Composite Delamination Fatigue Life Prediction Methodology  

NASA Technical Reports Server (NTRS)

Delamination is one of the most significant and unique failure modes in composite structures. Because of a lack of understanding of the consequences of delamination and the inability to predict delamination onset and growth, many composite parts are unnecessarily rejected upon inspection, both immediately after manufacture and while in service. NASA Langley is leading the efforts in the U.S. to develop a fatigue life prediction methodology for composite delamination using fracture mechanics. Research being performed to this end will be reviewed. Emphasis will be placed on the development of test standards for delamination characterization, incorporation of approaches for modeling delamination in commercial finite element codes, and efforts to mature the technology for use in design handbooks and certification documents.

OBrien, Thomas K.

2009-01-01

22

Generation of Finite Life Distributional Goodman Diagrams for Reliability Prediction  

NASA Technical Reports Server (NTRS)

The methodology of developing finite life distributional Goodman diagrams and surfaces is described for presenting allowable combinations of alternating stress and mean stress to the design engineer. The combined stress condition is that of an alternating bending stress and a constant shear stress. The finite life Goodman diagrams and surfaces are created from strength distributions developed at various ratios of alternating to mean stress at particular cycle life values. The conclusions indicate that the Von Mises-Hencky ellipse, for cycle life values above 1000 cycles, is an adequate model of the finite life Goodman diagram. In addition, suggestions are made which reduce the number of experimental data points required in a fatigue data acquisition program.

Kececioglu, D.; Guerrieri, W. N.

1971-01-01

23

Life Cycle Assessment of Carbon Fiber-Reinforced Polymer Composites  

SciTech Connect

Carbon fiber-reinforced polymer matrix composites is gaining momentum with the pressure to lightweight vehicles, however energy-intensity and cost remain some of the major barriers before this material could be used in large-scale automotive applications. A representative automotive part, i.e., a 30.8 kg steel floor pan having a 17% weight reduction potential with stringent cash performance requirements has been considered for the life cycle energy and emissions analysis based on the latest developments occurring in the precursor type (conventional textile-based PAN vs. renewable-based lignin), part manufacturing (conventional SMC vs. P4) and fiber recycling technologies. Carbon fiber production is estimated to be about 14 times more energy-intensive than conventional steel production, however life cycle primary energy use is estimated to be quite similar to the conventional part, i.e., 18,500 MJ/part, especially when considering the uncertainty in LCI data that exists from using numerous sources in the literature. Lignin P4 technology offers the most life cycle energy and CO2 emissions benefits compared to a conventional stamped steel technology. With a 20% reduction in energy use in the lignin conversion to carbon fiber and free availability of lignin as a by-product of ethanol and wood production, a 30% reduction in life cycle energy use could be obtained. A similar level of life cycle energy savings could also be obtained with a higher part weight reduction potential of 43%.

Das, Sujit [ORNL

2011-01-01

24

Natural Language Processing with Distributional Compositional Models Jean Maillard  

E-print Network

Natural Language Processing with Distributional Compositional Models Jean Maillard Supervised by: Dr Stephen Clark, Computer Laboratory, University of Cambridge Natural Language Processing language. Tradi- tionally, the field has been divided into two "camps": compositional and distri- butional

25

Isothermal life prediction of composite lamina using a damage mechanics approach  

NASA Technical Reports Server (NTRS)

A method for predicting isothermal plastic fatigue life of a composite lamina is presented in which both fibers and matrix are isotropic materials. In general, the fatigue resistances of the matrix, fibers, and interfacial material must be known in order to predict composite fatigue life. Composite fatigue life is predicted using only the matrix fatigue resistance due to inelasticity micromechanisms. The effect of the fiber orientation on loading direction is accounted for while predicting composite life. The application is currently limited to isothermal cases where the internal thermal stresses that might arise from thermal strain mismatch between fibers and matrix are negligible. The theory is formulated to predict the fatigue life of a composite lamina under either load or strain control. It is applied currently to predict the life of tungsten-copper composite lamina at 260 C under tension-tension load control. The calculated life of the lamina is in good agreement with available composite low cycle fatigue data.

Abuelfoutouh, Nader M.; Verrilli, Michael J.; Halford, Gary R.

1989-01-01

26

Maximum likelihood estimation for life distributions with competing failure modes  

NASA Technical Reports Server (NTRS)

Systems which are placed on test at time zero, function for a period and die at some random time were studied. Failure may be due to one of several causes or modes. The parameters of the life distribution may depend upon the levels of various stress variables the item is subject to. Maximum likelihood estimation methods are discussed. Specific methods are reported for the smallest extreme-value distributions of life. Monte-Carlo results indicate the methods to be promising. Under appropriate conditions, the location parameters are nearly unbiased, the scale parameter is slight biased, and the asymptotic covariances are rapidly approached.

Sidik, S. M.

1979-01-01

27

Proposed framework for thermomechanical life modeling of metal matrix composites  

NASA Technical Reports Server (NTRS)

The framework of a mechanics of materials model is proposed for thermomechanical fatigue (TMF) life prediction of unidirectional, continuous-fiber metal matrix composites (MMC's). Axially loaded MMC test samples are analyzed as structural components whose fatigue lives are governed by local stress-strain conditions resulting from combined interactions of the matrix, interfacial layer, and fiber constituents. The metallic matrix is identified as the vehicle for tracking fatigue crack initiation and propagation. The proposed framework has three major elements. First, TMF flow and failure characteristics of in situ matrix material are approximated from tests of unreinforced matrix material, and matrix TMF life prediction equations are numerically calibrated. The macrocrack initiation fatigue life of the matrix material is divided into microcrack initiation and microcrack propagation phases. Second, the influencing factors created by the presence of fibers and interfaces are analyzed, characterized, and documented in equation form. Some of the influences act on the microcrack initiation portion of the matrix fatigue life, others on the microcrack propagation life, while some affect both. Influencing factors include coefficient of thermal expansion mismatch strains, residual (mean) stresses, multiaxial stress states, off-axis fibers, internal stress concentrations, multiple initiation sites, nonuniform fiber spacing, fiber debonding, interfacial layers and cracking, fractured fibers, fiber deflections of crack fronts, fiber bridging of matrix cracks, and internal oxidation along internal interfaces. Equations exist for some, but not all, of the currently identified influencing factors. The third element is the inclusion of overriding influences such as maximum tensile strain limits of brittle fibers that could cause local fractures and ensuing catastrophic failure of surrounding matrix material. Some experimental data exist for assessing the plausibility of the proposed framework.

Halford, Gary R.; Lerch, Bradley A.; Saltsman, James F.

1993-01-01

28

Ceramic Matrix Composites (CMC) Life Prediction Method Development  

NASA Technical Reports Server (NTRS)

Advanced launch systems (e.g., Reusable Launch Vehicle and other Shuttle Class concepts, Rocket-Based Combine Cycle, etc.), and interplanetary vehicles will very likely incorporate fiber reinforced ceramic matrix composites (CMC) in critical propulsion components. The use of CMC is highly desirable to save weight, to improve reuse capability, and to increase performance. CMC candidate applications are mission and cycle dependent and may include turbopump rotors, housings, combustors, nozzle injectors, exit cones or ramps, and throats. For reusable and single mission uses, accurate prediction of life is critical to mission success. The tools to accomplish life prediction are very immature and not oriented toward the behavior of carbon fiber reinforced silicon carbide (C/SiC), the primary system of interest for a variety of space propulsion applications. This paper describes an approach to satisfy the need to develop an integrated life prediction system for CMC that addresses mechanical durability due to cyclic and steady thermomechanical loads, and takes into account the impact of environmental degradation.

Levine, Stanley R.; Calomino, Anthony M.; Ellis, John R.; Halbig, Michael C.; Mital, Subodh K.; Murthy, Pappu L.; Opila, Elizabeth J.; Thomas, David J.; Thomas-Ogbuji, Linus U.; Verrilli, Michael J.

2000-01-01

29

An overview of computational simulation methods for composite structures failure and life analysis  

SciTech Connect

Three parallel computational simulation methods are being developed at the LeRC Structural Mechanics Branch (SMB) for composite structures failure and life analysis: progressive fracture CODSTRAN; hierarchical methods for high-temperature composites; and probabilistic evaluation. Results to date demonstrate that these methods are effective in simulating composite structures failure/life/reliability.

Chamis, C.C.

1993-10-01

30

A Distributed Constraint Satisfaction Problem Approach to Virtual Device Composition  

E-print Network

A Distributed Constraint Satisfaction Problem Approach to Virtual Device Composition Eric Karmouch, Member, IEEE, and Amiya Nayak, Senior Member, IEEE Abstract--The dynamic composition of networked MANET-based composition schemes use service discovery mechanisms that depend on periodic service

Chen, Ing-Ray

31

Bayesian estimation of life parameters in the Weibull distribution.  

NASA Technical Reports Server (NTRS)

Development of a Bayesian analysis of the scale and shape parameters in the Weibull distribution and the corresponding reliability function with respect to the usual life-testing procedures. For the scale parameter theta, Bayesian estimates of theta and reliability are obtained for the uniform, exponential, and inverted gamma prior probability densities. Bhattacharya's results (1967) for the one-parameter exponential life-testing distribution are reduced to a special case of these results. A fully Bayesian analysis of both the scale and shape parameters is developed by assuming independent prior distributions; since in the latter case, analytical tractability is not possible, Bayesian estimates are obtained through a conjunction of Monte Carlo simulation and numerical-integration techniques. In both cases, a computer simulation is carried out, and a comparison is made between the Bayesian and the corresponding minimum-variance unbiased, or maximum likelihood, estimates. As expected, the Bayesian estimates are superior.

Canavos, G. C.; Tsokos, C. P.

1973-01-01

32

A hybrid model for fatigue life estimation of polymer matrix composites  

NASA Astrophysics Data System (ADS)

A major limitation of current fatigue life prediction methods for polymer matrix composite laminates is that they rely on empirical S-N data. In contrast to fatigue life prediction methods for metals which are based on physical crack growth models, the heart of fatigue life models for composites is empirical S-N data for each specific material system and specific loading conditions. This implies that the physical nature and processes responsible for tensile fatigue are not well understood. In this work a mechanism-based approach is used to model the damage growth and failure of uniaxial polymer matrix composites under uni-axial tension-tension fatigue loading. The model consists of three parts: an initial damage model, a damage growth model, and a tensile failure model. The damage growth portion of the model is based on fracture mechanics at the fiber/matrix level. The tensile failure model is based on a chain of bundles failure theory originally proposed for predicting the static strength of unidirectional laminates using fiber strength distributions. The tensile fatigue life prediction model developed in this work uses static tensile strength data and basic material properties to calculate the strength degradation due to fiber-matrix damage growth caused by fatigue loading and does not use any experimental S-N data. The output of the model is the probability of failure under tensile fatigue loading for a specified peak load level. Experimental data is used to validate and refine the model and good correlation between the model and experimental data has been shown. The principal contribution of this work is a hybrid-mechanistic model for analyzing and predicting the tension-tension fatigue life behavior of uniaxial polymer matrix composites. This model represents the very foundation to build upon a comprehensive model for fatigue. It demonstrates the validity of the ideas as they apply to uniaxial laminates that may in turn be used to apply to more complex laminates. Additionally, because the model is mechanism based it can be used for evaluation of the effects of constituent property changes such as matrix stiffness and toughness, or environmental conditions such as temperature and moisture.

Uleck, Kevin R.

33

Amplitude distribution of composite terrain radar clutter and the K-distribution  

Microsoft Academic Search

A novel class of probability distributions resulting from a compound Poisson process is found to correlate well with amplitude distributions of radar clutter returns spatially sampled from composite terrain. This class of distributions, derived from assumptions of random scattering phase and Poisson spatial distribution of elementary scattering sources, is specified by several physical and statistical parameters in its complete generality.

J. K. Jao

1984-01-01

34

Fatigue Life Analysis of Tapered Hybrid Composite Flexbeams  

NASA Technical Reports Server (NTRS)

Nonlinear-tapered flexbeam laminates from a full-size composite helicopter rotor hub flexbeam were tested under combined constant axial tension and cyclic bending loads. The two different graphite/glass hybrid configurations tested under cyclic loading failed by delamination in the tapered region. A 2-D finite element model was developed which closely approximated the flexbeam geometry, boundary conditions, and loading. The analysis results from two geometrically nonlinear finite element codes, ANSYS and ABAQUS, are presented and compared. Strain energy release rates (G) obtained from the above codes using the virtual crack closure technique (VCCT) at a resin crack location in the flexbeams are presented for both hybrid material types. These results compare well with each other and suggest that the initial delamination growth from the resin crack toward the thick region of the flexbeam is strongly mode II. The peak calculated G values were used with material characterization data to calculate fatigue life curves and compared with test data. A curve relating maximum surface strain to number of loading cycles at delamination onset compared reasonably well with the test results.

Murri, Gretchen B.; Schaff, Jeffery R.; Dobyns, Alan L.

2002-01-01

35

Barium distributions in teeth reveal early life dietary transitions in primates  

PubMed Central

Early life dietary transitions reflect fundamental aspects of primate evolution and are important determinants of health in contemporary human populations1,2. Weaning is critical to developmental and reproductive rates; early weaning can have detrimental health effects but enables shorter inter-birth intervals, which influences population growth3. Uncovering early life dietary history in fossils is hampered by the absence of prospectively-validated biomarkers that are not modified during fossilisation4. Here we show that major dietary shifts in early life manifest as compositional variations in dental tissues. Teeth from human children and captive macaques, with prospectively-recorded diet histories, demonstrate that barium (Ba) distributions accurately reflect dietary transitions from the introduction of mother’s milk and through the weaning process. We also document transitions in a Middle Palaeolithic juvenile Neanderthal, which shows a pattern of exclusive breastfeeding for seven months, followed by seven months of supplementation. After this point, Ba levels in enamel returned to baseline prenatal levels, suggesting an abrupt cessation of breastfeeding at 1.2 years of age. Integration of Ba spatial distributions and histological mapping of tooth formation enables novel studies of the evolution of human life history, dietary ontogeny in wild primates, and human health investigations through accurate reconstructions of breastfeeding history. PMID:23698370

Austin, Christine; Smith, Tanya M.; Bradman, Asa; Hinde, Katie; Joannes-Boyau, Renaud; Bishop, David; Hare, Dominic J.; Doble, Philip; Eskenazi, Brenda; Arora, Manish

2013-01-01

36

Quantum logic unites compositional functional semantics and distributional semantic models  

E-print Network

Quantum logic unites compositional functional semantics and distributional semantic models Anne but to sentences, paragraphs etc. They are ruled by laws of logic inherent to language. Natural language conveys in by the familiar logical models, the intensional aspect by distributional semantic models, DSM's. We propose

Paris-Sud XI, Université de

37

A Distributed Model of Ionomeric Polymer Metal Composite  

Microsoft Academic Search

This article presents a novel model of an ionomeric polymer metal composite (IPMC) material. An IPMC is modeled as a lossy RC distributed line. Unlike other electro-mechanical models of an IPMC, the distributed nature of our model permits modeling the non-uniform bending of the material. Instead of modeling the tip deflection or uniform deformation of the material, we model the

A. Punning; U. Johanson; M. Anton; A. Aabloo; M. Kruusmaa

2009-01-01

38

An empirical Bayes approach for the Poisson life distribution.  

NASA Technical Reports Server (NTRS)

A smooth empirical Bayes estimator is derived for the intensity parameter (hazard rate) in the Poisson distribution as used in life testing. The reliability function is also estimated either by using the empirical Bayes estimate of the parameter, or by obtaining the expectation of the reliability function. The behavior of the empirical Bayes procedure is studied through Monte Carlo simulation in which estimates of mean-squared errors of the empirical Bayes estimators are compared with those of conventional estimators such as minimum variance unbiased or maximum likelihood. Results indicate a significant reduction in mean-squared error of the empirical Bayes estimators over the conventional variety.

Canavos, G. C.

1973-01-01

39

Distributed Middleware Services Composition and Synthesis Technology  

E-print Network

and actuators, and a power supply. These systems are tightly coupled to physical processes, distributed across, communication, and com- puting hardware, along with a power supply, in a volume no more than a few cubic-scale active noise control, active flow control over aircraft wings, micro-satellite constellations, smart

Maróti, Miklós

40

Fatigue Life Methodology for Tapered Composite Flexbeam Laminates  

NASA Technical Reports Server (NTRS)

The viability of a method for determining the fatigue life of composite rotor hub flexbeam laminates using delamination fatigue characterization data and a geometric non-linear finite element (FE) analysis was studied. Combined tension and bending loading was applied to non-linear tapered flexbeam laminates with internal ply drops. These laminates, consisting of coupon specimens cut from a full-size S2/E7T1 glass-epoxy flexbeam were tested in a hydraulic load frame under combined axial-tension and transverse cyclic bending. The magnitude of the axial load remained constant and the direction of the load rotated with the specimen as the cyclic bending load was applied. The first delamination damage observed in the specimens occurred at the area around the tip of the outermost ply-drop group. Subsequently, unstable delamination occurred by complete delamination along the length of the specimen. Continued cycling resulted in multiple delaminations. A 2D finite element model of the flexbeam was developed and a geometrically non-linear analysis was performed. The global responses of the model and test specimens agreed very well in terms of the transverse displacement. The FE model was used to calculate strain energy release rates (G) for delaminations initiating at the tip of the outer ply-drop area and growing toward the thick or thin regions of the flexbeam, as was observed in the specimens. The delamination growth toward the thick region was primarily mode 2, whereas delamination growth toward the thin region was almost completely mode 1. Material characterization data from cyclic double-cantilevered beam tests was used with the peak calculated G values to generate a curve predicting fatigue failure by unstable delamination as a function of the number of loading cycles. The calculated fatigue lives compared well with the test data.

Murri, Gretchen B.; OBrien, T. Kevin; Rousseau, Carl Q.

1997-01-01

41

Fatigue Life Methodology for Tapered Composite Flexbeam Laminates  

NASA Technical Reports Server (NTRS)

The viability of a method for determining the fatigue life of composite rotor hub flexbeam laminates using delamination fatigue characterization data and a geometric non-linear finite element (FE) analysis was studied. Combined tension and bending loading was applied to nonlinear tapered flexbeam laminates with internal ply drops. These laminates, consisting of coupon specimens cut from a full-size S2/E7T1 glass-epoxy flexbeam were tested in a hydraulic load frame under combined axial-tension and transverse cyclic bending loads. The magnitude of the axial load remained constant and the direction of the load rotated with the specimen as the cyclic bending load was applied. The first delamination damage observed in the specimens occurred at the area around the tip of the outermost ply-drop group. Subsequently, unstable delamination occurred by complete delamination along the length of the specimen. Continued cycling resulted in multiple delaminations. A 2D finite element model of the flexbeam was developed and a geometrically non-linear analysis was performed. The global responses of the model and test specimens agreed very well in terms of the transverse flexbeam tip-displacement and flapping angle. The FE model was used to calculate strain energy release rates (G) for delaminations initiating at the tip of the outer ply-drop area and growing toward the thick or thin regions of the flexbeam, as was observed in the specimens. The delamination growth toward the thick region was primarily mode 2, whereas delamination growth toward the thin region was almost completely mode 1. Material characterization data from cyclic double-cantilevered beam tests was used with the peak calculated G values to generate a curve predicting fatigue failure by unstable delamination as a function of the number of loading cycles. The calculated fatigue lives compared well with the test data.

Murri, Gretchen B.; O''Brien, T. Kevin; Rousseau, Carl Q.

1997-01-01

42

Effects of cyclic stress distribution models on fatigue life predictions  

NASA Astrophysics Data System (ADS)

The fatigue analysis of a wind turbine component typically uses representative samples of cyclic loads to determine lifetime loads. In this paper, several techniques currently in use are compared to one another based on fatigue life analyses. The generalized Weibull fitting technique is used to remove the artificial truncation of large-amplitude cycles that is inherent in relatively short data sets. Using data from the Sandia/DOE 34-m Test Bed, the generalized Weibull file technique is shown to be excellent for matching the body of the distribution of cyclic loads and for extrapolating the tail of the distribution. However, the data also illustrate that the fitting technique is not a substitute for an adequate data base.

Sutherland, H. J.; Veers, P. S.

1994-10-01

43

Distributed Feature Composition: A Virtual Architecture for Telecommunications Services  

Microsoft Academic Search

Distributed Feature Composition (DFC) is a new technology for feature specification and composition, based on a virtual architecture offering benefits analogous to those of a pipe-and-filter architecture. In the DFC architecture, customer calls are processed by dynamically assembled configurations of filter-like components: each component implements an applicable feature, and communicates with its neighbors by featureless internal calls that are connected

Michael Jackson; Pamela Zave

1998-01-01

44

Nondestructive Characterization Techniques Used for Ceramic Matrix Composite Life Determination  

NASA Technical Reports Server (NTRS)

Recent results indicate that the specific damping capacity and resonant frequency measurements taken periodically during a component's lifetime is able to quantify the mechanical fatigue of CMCS. This gives hope for the potential of determining the actual and residual life of CMC materials using a combination of nondestructive techniques. If successful, then this new paradigm for life prediction of CMCs could revolutionize the approach for designing and servicing CMC components, thereby significantly reducing costs for design, development, health monitoring, and maintenance of CMC components and systems. The Nondestructive Characterization (NDC) life prediction approach would complement life prediction using micromechanics and continuum finite element models. This paper reports on the initial concept of NDC life prediction, a review of the C/SiC blisk damping data, and how changes in the specific damping capacity & ultrasonic elastic modulus data have established the concept as a possibility.

Effinger, Michael; Koenig, John; Ellingson, Bill; Spohnholtz, Todd

2000-01-01

45

41 CFR 101-27.209 - Utilization and distribution of shelf-life items.  

Code of Federal Regulations, 2011 CFR

...Utilization and distribution of shelf-life items. 101-27.209 Section 101-27...MANAGEMENT 27.2-Management of Shelf-Life Materials § 101-27.209 Utilization and distribution of shelf-life items. Where it is determined...

2011-07-01

46

41 CFR 101-27.209 - Utilization and distribution of shelf-life items.  

Code of Federal Regulations, 2014 CFR

...Utilization and distribution of shelf-life items. 101-27.209 Section 101-27...MANAGEMENT 27.2-Management of Shelf-Life Materials § 101-27.209 Utilization and distribution of shelf-life items. Where it is determined...

2014-07-01

47

41 CFR 101-27.209 - Utilization and distribution of shelf-life items.  

Code of Federal Regulations, 2010 CFR

...Utilization and distribution of shelf-life items. 101-27.209 Section 101-27...MANAGEMENT 27.2-Management of Shelf-Life Materials § 101-27.209 Utilization and distribution of shelf-life items. Where it is determined...

2010-07-01

48

41 CFR 101-27.209 - Utilization and distribution of shelf-life items.  

Code of Federal Regulations, 2012 CFR

...Utilization and distribution of shelf-life items. 101-27.209 Section 101-27...MANAGEMENT 27.2-Management of Shelf-Life Materials § 101-27.209 Utilization and distribution of shelf-life items. Where it is determined...

2012-07-01

49

41 CFR 101-27.209 - Utilization and distribution of shelf-life items.  

Code of Federal Regulations, 2013 CFR

...Utilization and distribution of shelf-life items. 101-27.209 Section 101-27...MANAGEMENT 27.2-Management of Shelf-Life Materials § 101-27.209 Utilization and distribution of shelf-life items. Where it is determined...

2013-07-01

50

A study of factors affecting life prediction of composites under spectrum loading  

Microsoft Academic Search

The influence of damage accumulation metric, constant life diagram formulation and cycle counting method on life prediction schemes for composite materials under variable amplitude (VA) loading is investigated in this paper. Special focus is put on residual strength based methodologies; different degradation functions are implemented and compared with the Palmgren–Miner (PM) damage accumulation rule. The predictions are validated by comparison

V. A. Passipoularidis; T. P. Philippidis

2009-01-01

51

A Framework for Event Composition in Distributed Systems  

E-print Network

occurred within the system. Components either act as event sources and publish new events, or event sinksA Framework for Event Composition in Distributed Systems Peter R. Pietzuch ? , Brian Shand such as internet-wide or ubiquitous systems, event-based communication is an e#11;ective messag- ing mechanism

Cambridge, University of

52

A Framework for Event Composition in Distributed Systems  

E-print Network

occurred within the system. Components either act as event sources and publish new events, or event sinksA Framework for Event Composition in Distributed Systems Peter R. Pietzuch , Brian Shand , and Jean such as internet-wide or ubiquitous systems, event-based communication is an effective messag- ing mechanism

Cambridge, University of

53

Cosmic Rays 8.1 Composition and energy distribution  

E-print Network

Chapter 8 Cosmic Rays 8.1 Composition and energy distribution Cosmic rays can be broadly defined as the massive particles, photons ( rays, X-rays, ultra- violet and infrared radiation, ...), neutrinos, and exotics (WIMPS, axions,...) striking the earth. The primary cosmic rays are those entering the upper

Washington at Seattle, University of - Department of Physics, Electroweak Interaction Research Group

54

Composition and Distribution of Beach Debris in Orange County, California  

Microsoft Academic Search

Many studies have quantified debris collected on beaches around the world. Only a few of those studies have been conducted in the United States, and they are largely limited to semi-quantitative efforts performed as part of volunteer clean-up activities. This study quantifies the distribution and composition of beach debris by sampling 43 stratified random sites on the Orange County, California

Shelly L. Moore; Dominic Gregorio; Michael Carreon; Stephen B. Weisberg; Molly K. Leecaster

2001-01-01

55

Integration of distributed strain and temperature sensors in composite coiled tubing  

NASA Astrophysics Data System (ADS)

Composite coiled tubing is an emerging technology in the oil and gas sector that presents important advantages compared to the steel coiled tubing and conventional drilling. The composite tube has reduced weight, allowing extended reach and improved fatigue life. An additional advantage resides in the fact that the coiled tube wall can contain and protect additional functional elements, such as electrical conductors and fiber optics for sensing and data communication. Sensing systems based on Brillouin and Raman scattering can be used to verify the pipe operational parameters, prevent failure, optimize oil production from the well, provide strain distribution along the tubing and detect hot-spots in high-power cables. The integration of such sensing elements into composite tubing presents additional advantages and challenges. On one hand the embedded sensors are protected by the composite material and can be installed during production, avoiding external installation that could interfere with the tubing operations. In the other hand, the integration of optical fiber sensors into the composite structure requires the development of appropriate packaging and installation techniques that allow easy handling during production and avoid and damage to the sensor and the composite structure itself. This contribution presents the sensing cable designs for temperature and strain sensing in a composite coiled tubing as well as testing results form initial field demonstrations.

Inaudi, Daniele; Glisic, Branko

2006-03-01

56

Applying a Composite Process Framework (CPF) in Real Life Software Development Project  

Microsoft Academic Search

This paper presents the outcome of an action research study that was conducted to validate the application of a Composite Process Framework (CPF) in real life software development project. This research extends an existing application software development methodology to incorporate the composite process framework and tailor it to meet the needs of a particular software development project. This paper also

Mohammed Al-Maharmeh; Bhuvan Unhelkar

2009-01-01

57

Litter sex composition affects life-history traits in yellow-bellied marmots  

E-print Network

Litter sex composition affects life-history traits in yellow-bellied marmots Raquel Monclu´ s1-bellied marmots (Marmota flaviventris) and documented the effects of weaned litter sex composition and anogenital-bellied marmots Introduction Litter sex ratio has important consequences for parental fit- ness because male

Blumstein, Daniel T.

58

Bounds on the Strength Distribution of Unidirectional Fiber Composites  

SciTech Connect

Failure mechanisms under tensile loading of unidirectional fiber composites comprising of Weibull fibers embedded in a matrix are studied using Monte-Carlo simulations. Two fundamental mechanisms of failure are recognized--stress concentration driven failure and strength driven failure. It is shown that the cumulative distribution function for composite strength predicted by the stressconcentration-driven failure and strength-driven failure form apparent upper and lower bounds respectively and also that failure mechanism switches from one to the other as fiber strength variability changes.

Mahesh, S.; Beyerlein, I.J.; Phoenix, S.L.

1999-06-13

59

Distribution of early life history stages of fishes in selected pools of the upper Mississippi River  

USGS Publications Warehouse

Effective management of the fishery resources of the Upper Mississippi River and successful mitigation of the loss of critical habitat depend in part on an understanding of the reproductive and early life history requirements of the affected fishes. However, little is known about the use of nursery areas by fishes in the river. Of the nearly 130 species identified in the adult ichthyofauna, only a few are represented proportionally in the available data on early life stages because study designs have not included consideration of the early stages, collection gears have not adequately sampled the young, and eggs and larvae of some species are difficult to sample by conventional approaches. For the species collected, information is available on seasonal variations in total densities, composition, and catch among different habitat types. However, the data are most accurate for species with buoyant early life stages, such as freshwater drum (Aplodinotus grunniens) and gizzard shad (Dorosoma cepedianum). Eggs and larvae of freshwater drum dominate collections made in the main channel, whereas other larval fishes are usually most abundant in backwater habitats. The species found there usually deposit eggs on the substrate or on vegetation. Habitat preferences (as indicated by relative abundance) often shift as development proceeds and physical and behavioral changes occur in the larvae. Only limited information is available on the distribution of larvae within habitats, but it is clear that variations within habitats are significant.

Holland, L.E.

1986-01-01

60

Amplitude distribution of composite terrain radar clutter and the K-distribution  

NASA Astrophysics Data System (ADS)

A novel class of probability distributions resulting from a compound Poisson process is found to correlate well with amplitude distributions of radar clutter returns spatially sampled from composite terrain. This class of distributions, derived from assumptions of random scattering phase and Poisson spatial distribution of elementary scattering sources, is specified by several physical and statistical parameters in its complete generality. These parameters are: (1) the number of scatterer types; (2) the average radar scattering cross section and the cross-sectional distribution of each different scatterer type; (3) the occurrence probability or the average scatterer size and spatial density; (4) the radar resolution area; and (5) the average background radiation as well as the radar internal noise power. Excellent fits of the theoretical clutter distributions to the measurement data are obtained by assuming a Rayleigh amplitude distribution for the elementary scatterer return for high grazing angle cases and a more general K-distribution for low grazing angle cases.

Jao, J. K.

1984-10-01

61

A comparison of taxonomic composition and diversity between reef coral life and death assemblages in Madang Lagoon, Papua New Guinea  

Microsoft Academic Search

The comparative taphonomy of reef coral life and death assemblages makes an important contribution in estimating bias in the taxonomic composition of fossil reef ecosystems. In Madang Lagoon, Papua New Guinea, the taxonomic composition of reef coral death assemblages shows varying degrees of congruence with adjacent life assemblages in fringing reefs. The original composition of coral communities from low energy

John M. Pandolfi; Peter R. Minchin

1996-01-01

62

Increased volume of distribution prolongs midazolam half-life.  

PubMed Central

It has recently been shown by several investigators that the half-life (t1/2) of midazolam is prolonged (greater than 7 h) in a small proportion of the population. One group has inferred that this subpopulation represents a group of slow metabolizers of midazolam to alpha-OH-midazolam. Others disagree and postulate that there is an increase in the volume of distribution (V) resulting in a prolonged t1/2. This controversy led us to report experience from 90 subjects and patients where t1/2, V, and clearance (CL) were determined by both model-dependent and -independent pharmacokinetic analysis. We found a 5.6% (5 of 90) incidence of prolonged t1/2, similar to that previously reported. V was clearly increased without a decrease in CL in the five subjects with prolonged t1/2. Thus, the prolonged t1/2 is secondary to an increase in V and not a result of alterations in CL and metabolism. PMID:2306422

Wills, R J; Khoo, K C; Soni, P P; Patel, I H

1990-01-01

63

Flame structure in aluminized wide-distribution AP composite propellants  

Microsoft Academic Search

Flame structure in wide-distribution ammonium-perchlorate (AP), hydroxyl-terminated-polybutadiene (HTPB) binder, aluminum (Al) composite propellants is studied using 2-D laminates with oxygenated binder. Very fine (2-?m) AP (FAP) is used to produce fuel-rich, matrix propellant (oxygenated binder) with a FAP\\/binder ratio of 75\\/25. Coarse AP (CAP) is simulated by pressed AP lamina. A flame-structure regime map for the CAP\\/oxy-fuel matrix interaction flame

M. Q. Brewster; J. C. Mullen

2010-01-01

64

Fatigue life methodology for tapered hybrid composite flexbeams  

Microsoft Academic Search

Nonlinear-tapered flexbeam specimens from a full-size composite helicopter rotor hub flexbeam were tested under combined constant axial tension and cyclic bending loads. Two different graphite\\/glass hybrid configurations tested under cyclic loading failed by delamination in the tapered region. A 2-D finite element model was developed which closely approximated the flexbeam geometry, boundary conditions, and loading. The analysis results from two

Gretchen B. Murri; Jeffery R. Schaff

2006-01-01

65

Concept for Determining the Life of Ceramic Matrix Composites Using Nondestructive Characterization Techniques  

NASA Technical Reports Server (NTRS)

Damping measurements have been taken on ceramic matrix composite (CMC) turbopump blisks in the as fabricated, post proof testing, and post turbopump testing conditions. These results indicate that damping is able to quantify fatigue of the CMC blisk. This gives hope for the potential of determining the actual and residual life of CMC materials using a combination of nondestructive techniques. If successful, then this new paradigm for life prediction of CMCs could revolutionize the approach for designing and servicing CMC components, thereby significantly reducing costs for design, development, health monitoring, and maintenance of CMC components and systems. The Nondestructive Characterization (NDC) life prediction approach would complement life prediction using micromechanics and continuum finite element models. This paper reports on the initial concept of NDC life prediction and how changes in damping and ultrasonic elastic modulus data have established the concept as a possibility.

Effinger, Michael; Ellingson, Bill; Spohnholtz, Todd; Koenig, John

2000-01-01

66

Durability and Life of Ceramic Matrix Composites in Combustion Environment  

NASA Technical Reports Server (NTRS)

It is now generally recognized that the next frontier in the commercial air travel will be achieved by an optimum combination of the concepts being used for the air and space transports. It will depend upon the new engines specifically designed to meet the demanding strength, temperature, environment and economy requirements. The successful development of an advanced propulsion system for a 21st Century High Speed Civil Transport will require key advances in the combustor system. Minimizing nitrous oxide (NO(x)) emission is critical, since the deleterious interaction within the ozone layer would occur at the proposed vehicle cruise level of about 75,000 feet. In order to achieve the low NOx levels an efficient combustor operating at controlled equivalence ratios and high combustion temperatures are required. This requires a combustor, whose one portion will be operating in an oxidizing environment while the other portion will operate in a reducing environment. This rather unusual requirement has introduced considerable challenge to the materials scientists and engineers, the development of material systems capable of long-life at high temperatures (up to 3000 F) in an oxidizing and/or reducing environment.

Tewari, Surendra

1997-01-01

67

Computational Mechanics of Fatigue and Life Predictions for Composite Materials and Structures  

E-print Network

are introduced to model the fatigue damage. The degradation of material response under cyclic loading initiation, propaga- tion and overall structural failure under cyclic loading. When applying the CDM based1 Computational Mechanics of Fatigue and Life Predictions for Composite Materials and Structures

Fish, Jacob

68

Physical Activity, Body Composition, and Perceived Quality of Life of Adults with Visual Impairments  

ERIC Educational Resources Information Center

Relatively little is known about the health and fitness of adults with visual impairments. This article documents the physical activity levels and body-composition profiles of young and middle-aged adults with visual impairments and addresses the concomitant effects of these factors on perceived quality of life. (Contains 2 tables.)

Holbrook, Elizabeth A.; Caputo, Jennifer L.; Perry, Tara L.; Fuller, Dana K.; Morgan, Don W.

2009-01-01

69

25 CFR 179.101 - How does the Secretary distribute principal and income to the holder of a life estate?  

Code of Federal Regulations, 2010 CFR

...distribute principal and income to the holder of a life estate? 179.101 Section 179.101 Indians...DEPARTMENT OF THE INTERIOR LAND AND WATER LIFE ESTATES AND FUTURE INTERESTS Life Estates Not Created Under AIPRA §...

2010-04-01

70

25 CFR 179.101 - How does the Secretary distribute principal and income to the holder of a life estate?  

Code of Federal Regulations, 2014 CFR

...distribute principal and income to the holder of a life estate? 179.101 Section 179.101 Indians...DEPARTMENT OF THE INTERIOR LAND AND WATER LIFE ESTATES AND FUTURE INTERESTS Life Estates Not Created Under AIPRA §...

2014-04-01

71

25 CFR 179.101 - How does the Secretary distribute principal and income to the holder of a life estate?  

Code of Federal Regulations, 2013 CFR

...distribute principal and income to the holder of a life estate? 179.101 Section 179.101 Indians...DEPARTMENT OF THE INTERIOR LAND AND WATER LIFE ESTATES AND FUTURE INTERESTS Life Estates Not Created Under AIPRA §...

2013-04-01

72

25 CFR 179.101 - How does the Secretary distribute principal and income to the holder of a life estate?  

Code of Federal Regulations, 2012 CFR

...distribute principal and income to the holder of a life estate? 179.101 Section 179.101 Indians...DEPARTMENT OF THE INTERIOR LAND AND WATER LIFE ESTATES AND FUTURE INTERESTS Life Estates Not Created Under AIPRA §...

2012-04-01

73

25 CFR 179.101 - How does the Secretary distribute principal and income to the holder of a life estate?  

Code of Federal Regulations, 2011 CFR

...distribute principal and income to the holder of a life estate? 179.101 Section 179.101 Indians...DEPARTMENT OF THE INTERIOR LAND AND WATER LIFE ESTATES AND FUTURE INTERESTS Life Estates Not Created Under AIPRA §...

2011-04-01

74

Strength and fatigue life evaluation of composite laminate with embedded sensors  

NASA Astrophysics Data System (ADS)

Prognosis regarding durability of composite structures using various Structural Health Monitoring (SHM) techniques is an important and challenging topic of research. Ultrasonic SHM systems with embedded transducers have potential application here due to their instant monitoring capability, compact packaging potential toward unobtrusiveness and noninvasiveness as compared to non-contact ultrasonic and eddy current techniques which require disassembly of the structure. However, embedded sensors pose a risk to the structure by acting as a flaw thereby reducing life. The present paper focuses on the determination of strength and fatigue life of the composite laminate with embedded film sensors like CNT nanocomposite, PVDF thin films and piezoceramic films. First, the techniques of embedding these sensors in composite laminates is described followed by the determination of static strength and fatigue life at coupon level testing in Universal Testing Machine (UTM). Failure mechanisms of the composite laminate with embedded sensors are studied for static and dynamic loading cases. The coupons are monitored for loading and failure using the embedded sensors. A comparison of the performance of these three types of embedded sensors is made to study their suitability in various applications. These three types of embedded sensors cover a wide variety of applications, and prove to be viable in embedded sensor based SHM of composite structures.

Rathod, Vivek T.; Hiremath, S. R.; Roy Mahapatra, D.

2014-04-01

75

Testing and Life Prediction for Composite Rotor Hub Flexbeams  

NASA Technical Reports Server (NTRS)

A summary of several studies of delamination in tapered composite laminates with internal ply-drops is presented. Initial studies used 2D FE models to calculate interlaminar stresses at the ply-ending locations in linear tapered laminates under tension loading. Strain energy release rates for delamination in these laminates indicated that delamination would likely start at the juncture of the tapered and thin regions and grow unstably in both directions. Tests of glass/epoxy and graphite/epoxy linear tapered laminates under axial tension delaminated as predicted. Nonlinear tapered specimens were cut from a full-size helicopter rotor hub and were tested under combined constant axial tension and cyclic transverse bending loading to simulate the loading experienced by a rotorhub flexbeam in flight. For all the tested specimens, delamination began at the tip of the outermost dropped ply group and grew first toward the tapered region. A 2D FE model was created that duplicated the test flexbeam layup, geometry, and loading. Surface strains calculated by the model agreed very closely with the measured surface strains in the specimens. The delamination patterns observed in the tests were simulated in the model by releasing pairs of MPCs along those interfaces. Strain energy release rates associated with the delamination growth were calculated for several configurations and using two different FE analysis codes. Calculations from the codes agreed very closely. The strain energy release rate results were used with material characterization data to predict fatigue delamination onset lives for nonlinear tapered flexbeams with two different ply-dropping schemes. The predicted curves agreed well with the test data for each case studied.

Murri, Gretchen B.

2004-01-01

76

Determining molecular mass distributions and compositions of functionalized dendrimer nanoparticles  

PubMed Central

This study demonstrates that a combination of unconventional electron microscopy techniques provides a quantitative means of assessing the degree of monodispersity of gadolinium (Gd) diethylenetriamine pentaacetic acid-conjugated polyamidoamine (PAMAM) dendrimers, which are designed for diagnostic imaging and delivering chemotherapeutics. Specifically, analysis of images acquired in the scanning transmission electron microscopy mode yields the distribution of molecular weights of individual dendrimers, whereas analysis of images acquired in the energy-filtering transmission electron microscopy mode yields the distribution of Gd atoms bound to the dendrimer nanoparticles. Measured compositions of Gd-conjugated G7 and G8 PAMAM dendrimers were consistent with the known synthetic chemistry. The G7 dendrimers had a mass of 330 ± 4 kDa and 266 ± 4 Gd atoms (± standard error of the mean). The G8 dendrimers had a mass of 600 ± 8 kDa and 350 ± 5 Gd atoms (± standard error of the mean). This approach will be particularly attractive for assessing the mass, composition and homogeneity of metal-containing organic nanoparticles used in nanomedicine. PMID:19505242

Sousa, AA; Aronova, MA; Wu, H; Sarin, H; Griffiths, GL

2009-01-01

77

DISTRIBUTION AND DURATION OF PELAGIC LIFE OF LARVAE OF DOVER SOLE, MICROSTOMUS PACIFICUS,. REX SOLE,  

E-print Network

DISTRIBUTION AND DURATION OF PELAGIC LIFE OF LARVAE OF DOVER SOLE, MICROSTOMUS PACIFICUS,. REX SOLE. HOSIE,2 AND SALLY L. RICHARDSONI ABSTRACT Dover and rex sole larvae attain an exceptionally large size and have a long pelagic life. Dover sole larvae (9-65 mm standard length) were collected in mid

78

Aspects of Chub Shiner Notropis potteri Life History with Comments on Native Distribution and Conservation Status  

E-print Network

Aspects of Chub Shiner Notropis potteri Life History with Comments on Native Distribution/Aquatic Station, Texas State University-San Marcos, San Marcos 78666 ABSTRACT.--Chub shiner Notropis potteri is unique among Notropis species in dietary habits, but remaining aspects of life history as well as native

Aspbury, Andrea S. - Department of Biology, Texas State University

79

Electrical Resistance of Ceramic Matrix Composites for Damage Detection and Life-Prediction  

NASA Technical Reports Server (NTRS)

The electric resistance of woven SiC fiber reinforced SiC matrix composites were measured under tensile loading conditions. The results show that the electrical resistance is closely related to damage and that real-time information about the damage state can be obtained through monitoring of the resistance. Such self-sensing capability provides the possibility of on-board/in-situ damage detection or inspection of a component during "down time". The correlation of damage with appropriate failure mechanism can then be applied to accurate life prediction for high-temperature ceramic matrix composites.

Smith, Craig; Morscher, Gregory N.; Xia, Zhenhai

2008-01-01

80

Particle size distribution dynamics during precipitative softening: constant solution composition.  

PubMed

In the treatment of surface water for potable use, precipitative coagulation (e.g., lime softening, alum or iron sweep coagulation) is widely utilized prior to particle removal processes. The particle size distribution (PSD) formed during such processes is a prime determinant of the removal efficiency for suspended and dissolved contaminants, but little is known quantitatively about how PSDs change by simultaneous precipitation and flocculation. Using precipitative softening as an example, detailed measurements of the PSD (using electronic particle counting) were made during precipitation of CaCO(3) under conditions of constant solution composition. Examination of the time-varying PSDs revealed dramatic changes resulting from nucleation, crystal growth, and flocculation. The influence of the saturation ratio, seed concentration, and mixing intensity on those processes was quantified. Implications with respect to the design and operation of water treatment facilities are discussed. PMID:18656223

Nason, Jeffrey A; Lawler, Desmond F

2008-08-01

81

Composition and distribution of beach debris in Orange County, California.  

PubMed

Many studies have quantified debris collected on beaches around the world. Only a few of those studies have been conducted in the United States, and they are largely limited to semi-quantitative efforts performed as part of volunteer clean-up activities. This study quantifies the distribution and composition of beach debris by sampling 43 stratified random sites on the Orange County, California coast, from August to September 1998. We estimated that approximately 106 million items, weighing 12 metric tons, occur on Orange County beaches. The most abundant items were pre-production plastic pellets, foamed plastics, and hard plastics. Debris density on the remote rocky shoreline was greater than that on high-use sandy beaches for most debris items. This finding partially reflects the periodic clean-up of high-use beaches by local municipalities, and also indicates that a high percentage of the observed debris was transported to the site from waterborne sources. PMID:11381879

Moore, S L; Gregorio, D; Carreon, M; Weisberg, S B; Leecaster, M K

2001-03-01

82

Identification of Heredity Kernels and Their Influence on the Life Time of Glass/Polyester Composites  

NASA Astrophysics Data System (ADS)

One of the major problems encountered in prediction of hereditary viscoelastic behavior of polymeric composites is the determination of heredity kernels. This issue comes down to identification of the model characterizing the viscoelastic properties of these materials. The purpose of this work is to propose a model for prediction of viscoelastic nonlinear behavior of laminate composite with polyester matrix, through the study and analysis of heredity kernels and their influence on the life time of this material. Identification of this model required experimental determination at room temperature, of viscoelastic parameters of heredity kernels by macroscopic approach. These data provide predictive tools for establishment of the life time and long term stress limit under static complex loading for this type of material.

Olodo, E. T.; Adjovi, E. C.; Adanhounme, V.

2014-11-01

83

Fatigue life prediction of an intermetallic matrix composite at elevated temperatures  

NASA Technical Reports Server (NTRS)

A strain-based fatigue life prediction method is proposed for an intermetallic matrix composite (IMC) under tensile cyclic loadings at elevated temperatures. Styled after the Universal Slopes method, the model utilizes the composite's tensile properties to estimate fatigue life. Factors such as fiber volume ratio, number of plys and temperature dependence are implicitly incorporated into the model through these properties. The model constants are determined by using unidirectional fatigue data at temperatures of 425 and 815 C. Fatigue lives from two independent sources are used to verify the model at temperatures of 650 and 760 C. Cross-ply lives at 760 C are also predicted. It is demonstrated that the correlation between experimental and predicted lives is within a factor of two.

Bartolotta, Paul A.

1991-01-01

84

Fatigue life prediction of an intermetallic matrix composite at elevated temperatures  

NASA Technical Reports Server (NTRS)

A strain-based fatigue life prediction method is proposed for an intermetallic matrix composite (IMC) under tensile cyclic loadings at elevated temperatures. Styled after the 'Universal Slopes' method, the model utilizes the composite's tensile properties to estimate fatigue life. Factors such as fiber volume ratio (Vf), number of plys and temperature dependence are implicitly incorporated into the model through these properties. The model constants are determined by using unidirectional fatigue data at temperatures of 425 and 815 C. Fatigue lives from two independent sources are used to verify the model at temperatures of 650 and 760 C. Cross-ply lives at 760 C are also predicted. It is demonstrated that the correlation between experimental and predicted lives is within a factor of two.

Bartolotta, P. A.

1991-01-01

85

An approach to fatigue life modeling in titanium-matrix composites  

Microsoft Academic Search

A review of the procedures developed by the author and his colleagues over the last several years for predicting elevated-temperature fatigue life of metal-matrix composites is presented. Modeling approaches involve concepts of both linear and non-linear summation of damage from cycle-dependent as well as time-dependent mechanisms. The analyses, further, treat the micromechanical stresses in the constituents as parameters in the

Theodore Nicholas

1995-01-01

86

Influence of Weight Gain Rate on Early Life Nutritional Status and Body Composition of Children  

PubMed Central

Objective. To evaluate the influence of the weight gain rate at 4–6 months on nutritional status and body composition in children between 4 and 7 years of age. Methods. Retrospective cohort study, sample of 257 children. Data collection was performed in two stages, with the first relating to retrospective data of weight gain from birth to the first 4–6 months of life in the patient records. Measurements of weight, height, waist circumference, and body composition in children between ages 4 and 7 years were obtained. Nutritional status was assessed by the BMI/age. Control variables, such as pregnancy, breastfeeding, lifestyle, and sociodemographics, were studied. Descriptive analysis and multiple linear regression were performed. Results. In the nutritional status assessment, the prevalence of overweight observed was 24.9%. After adjusting for control variables, it was found that the increase of the WGR at 4–6 months of age explained the occurrence of higher BMI/age, percentage of total body fat, body fat percentage in the android region, and waist circumference in children between 4 and 7 years of age. Conclusion. The increase of the WGR in the first months of life can lead to the occurrence of higher values of parameters of nutritional status and body composition in later life.

Magalhães, Taís Cristina Araújo; Ribeiro, Andréia Queiroz; Priore, Silvia Eloiza; Franceschini, Sylvia do Carmo Castro; Sant'Ana, Luciana Ferreira da Rocha

2014-01-01

87

Erosion Coatings Developed to Increase the Life and Durability of Composites  

NASA Technical Reports Server (NTRS)

Both the NASA Glenn Research Center and the Allison Advanced Development Company (AADC) have worked to develop and demonstrate erosion-resistant coatings that would increase the life and durability of composite materials used in commercial aircraft engines. These composite materials reduce component weight by 20 to 30 percent and result in less fuel burn and emissions and more fuel savings. Previously, however, their use was limited because of poor erosion resistance, which causes concerns about safety and leads to high maintenance costs. The coatings were tested by the University of Cincinnati, and the composites were manufactured by Texas Composites and coated by Engelhard and NASA Glenn. Rolls-Royce Corporation uses composite materials, which are stronger and less dense than steel or titanium, to make bypass vanes for their AE3007 engines. These engines are widely used in regional jet aircraft (Embraer) and unmanned air vehicles such as the Northrop Grumman Global Hawk. Coatings developed by NASA/Rolls-Royce can reduce erosion from abrasive materials and from impurities in the air that pass over these vanes, allowing Rolls-Royce to take advantage of the benefits of composite materials over titanium without the added costs of increased maintenance and/or engine failure. The Higher Operating Temperature Propulsion Components (HOTPC) Project developed cost-effective, durable coatings as part of NASA's goal to increase aviation system capacity growth. These erosion coatings will reduce the number of special inspections or instances of discontinued service due to erosion, allowing aircraft capacity to be maintained without inconveniencing the traveling public. A specific example of extending component life showed that these coatings increased the life of graphite fiber and polymer composite bypass vanes up to 8 times over that of the uncoated vanes. This increased durability allows components to operate to full design life without the fear of wear or failure. Recently, Rolls-Royce completed over 2000 hr of engine testing with the coated fan exit bypass vanes. There was no loss of coating after nearly 5000 typical engine cycles. Midway through the engine tests, the coated vanes were removed from the engine during a scheduled maintenance and inspection period. The vanes were shipped back to Glenn, where they underwent further stress testing in the Structural Dynamics Lab, mimicking more extreme conditions than those typical of the AE3007 engine cycle. These vanes were then replaced in the AE3007 and subjected to another 1000 hr of engine tests. Once again, there was no loss of coating and only a minimal appearance of cracking.

Sutter, James K.; Naik, Subhash K.; Bowman, Cheryl L.; Siefker, Robert; Miyoshi, Kazuhisa; Perusek, Gail P.

2004-01-01

88

Concrete Sentence Spaces for Compositional Distributional Models of Meaning  

E-print Network

Coecke, Sadrzadeh, and Clark (arXiv:1003.4394v1 [cs.CL]) developed a compositional model of meaning for distributional semantics, in which each word in a sentence has a meaning vector and the distributional meaning of the sentence is a function of the tensor products of the word vectors. Abstractly speaking, this function is the morphism corresponding to the grammatical structure of the sentence in the category of finite dimensional vector spaces. In this paper, we provide a concrete method for implementing this linear meaning map, by constructing a corpus-based vector space for the type of sentence. Our construction method is based on structured vector spaces whereby meaning vectors of all sentences, regardless of their grammatical structure, live in the same vector space. Our proposed sentence space is the tensor product of two noun spaces, in which the basis vectors are pairs of words each augmented with a grammatical role. This enables us to compare meanings of sentences by simply taking the inner product...

Grefenstette, Edward; Clark, Stephen; Coecke, Bob; Pulman, Stephen

2011-01-01

89

Asteroid taxonomy and the distribution of the compositional types  

NASA Technical Reports Server (NTRS)

Physical observations of minor planets documented in the TRIAD computer file are used to classify 752 objects into the broad compositional types C, S, M, E, R, and U (unclassifiable) according to the prescriptions adopted by Bowell et al. (1978). Diameters are computed from the photometric magnitude using radiometric and/or polarimetric data where available, or else from albedos characteristic of the indicated type. An analysis of the observational selection effects leads to tabulation of the actual number of asteroids, as a function of type and diameter, in each of 15 orbital element zones. For the whole main belt the population is 75% of type C, 15% of type S, and 10% of other types, with no belt-wide dependence of the mixing ratios on diameter. In some zones the logarithmic diameter-frequency relations are decidedly nonlinear. The relative frequency of S-type objects decreases smoothly outward through the main belt, with exponential scale length 0.5 AU. The rarer types show a more chaotic, but generally flatter, distribution over distance. Characteristic type distributions, contrasting with the background population, are found for the Eos, Koronis, Nysa and Themis families.

Zellner, B.

1979-01-01

90

Environmental Factors Related to the Distribution, Abundance, and Life History Characteristics of Mountain Whitefish in Idaho  

Microsoft Academic Search

Mountain whitefish Prosopium williamsoni are a broadly distributed native salmonid in western North America, but comparatively little investigation has been made regarding their population characteristics. We surveyed 2,043 study sites to assess whether physiochemical stream conditions affected mountain whitefish distribution and abundance in southern Idaho, and at 20 of these sites life history characteristics were also estimated. A total of

Kevin A. Meyer; F. Steven Elle; James A. Lamansky Jr

2009-01-01

91

The distribution of stars most likely to harbor intelligent life.  

PubMed

Simple heuristic models and recent numerical simulations show that the probability of habitable planet formation increases with stellar mass. We combine those results with the distribution of main-sequence stellar masses to obtain the distribution of stars most likely to possess habitable planets as a function of stellar lifetime. We then impose the self-selection condition that intelligent observers can only find themselves around a star with a lifetime greater than the time required for that observer to have evolved, T(i). This allows us to obtain the stellar timescale number distribution for a given value of T(i). Our results show that for habitable planets with a civilization that evolved at time T(i) = 4.5 Gyr the median stellar lifetime is 13 Gyr, corresponding approximately to a stellar type of G5, with two-thirds of the stars having lifetimes between 7 and 30 Gyr, corresponding approximately to spectral types G0-K5. For other values of T(i) the median stellar lifetime changes by less than 50%. PMID:19778273

Whitmire, Daniel P; Matese, John J

2009-09-01

92

Integration of distributed strain and temperature sensors in composite coiled tubing  

Microsoft Academic Search

Composite coiled tubing is an emerging technology in the oil and gas sector that presents important advantages compared to the steel coiled tubing and conventional drilling. The composite tube has reduced weight, allowing extended reach and improved fatigue life. An additional advantage resides in the fact that the coiled tube wall can contain and protect additional functional elements, such as

Daniele Inaudi; Branko Glisic

2006-01-01

93

Surface composition and barium evaporation rate of ``pedigreed'' impregnated tungsten dispenser cathodes during accelerated life testing  

NASA Astrophysics Data System (ADS)

A study has been made of the surface composition and barium evaporation rate of "pedigreed" impregnated tungsten dispenser cathodes. The effect of air exposure on coated cathodes was examined and was found to have no significant effect on barium evaporation rate although in some cases longer reactivation times were required. No changes in surface topography were apparent following air exposure and reactivation. Life testing was done at 100°C above the typical operating temperature for the cathode, where the typical operating temperature was taken to be 950°C for coated cathodes and 1050°C for uncoated cathodes. The cathodes were examined at different stages of life testing, up to 1200 h. Significant decreases in barium evaporation rates were found after as few as 500 h of life testing. After 1000 h the evaporation rate had decreased more than an order of magnitude. Changes in surface composition were also found. The effects of tungsten particle size, used in manufacture of the billet, on barium evaporation rate were also studied but no correlation was found.

Tomich, D. H.; Mescher, J. A.; Grant, J. T.

1987-03-01

94

The chemical composition and distribution of interstellar grains  

NASA Technical Reports Server (NTRS)

The chemical composition of interstellar grains is derived here on the basis of (1) the cosmic abundance of the elements; (2) the wavelength dependence of extinction and polarization; (3) the average total extinction; (4) the ratio of polarization to extinction; (5) the predominantly dielectric character of grains in the visible spectral region; and (6) infrared spectral characteristics of grains. Inferences of the core-mantle model with respect to spatial distribution are consistent with the proposition that growth of the mantles occurs in the galactic shock region predicted by the density-wave theory. Estimates of the total visual extinction toward the galactic center and the consequent estimates of the total amount of far infrared radiation are shown to depend critically on the grain model. Variations of the ratio of far ultraviolet to visual extinction are correlated with the conditions for growth of mantles on the bare small particles which are generally prevented from accreting mantles primarily because of their extreme temperature fluctuations produced by the ultraviolet photons in the radiation field.

Greenberg, J. M.; Hong, S.-S.

1974-01-01

95

Litter sex composition affects life-history traits in yellow-bellied marmots.  

PubMed

1. The presence of siblings might have long-lasting fitness consequences because they influence the early environment in which an animal develops. Several studies under laboratory conditions have shown long-lasting consequences from the presence of male siblings in utero on morphology and life-history traits. However, in wild animals, such effects of litter sex composition are unexplored. 2. We capitalized on a long-term study of individually marked yellow-bellied marmots (Marmota flaviventris) and documented the effects of weaned litter sex composition and anogenital distance on several life-history and fitness traits. 3. First, we demonstrated that the number of males in a litter influenced anogenital distance. Then, we found that masculinized females, those with larger anogenital distances, were less likely to survive their first hibernation, were more likely to disperse and were less likely to become pregnant and wean young. Males from male-biased litters had lower growth rates, but we failed to detect longer-term consequences. 4. Taken together, our results show profound sex-dependent effects of litter sex composition, probably due to differential prenatal exposure to androgens, in free-living animals. We conclude that masculinization might constitute an alternative mechanism explaining variation in different demographic traits. This finding highlights the importance of studying these maternal effects, and they enhance our concern over the widespread use of endocrine disrupting compounds. PMID:21801175

Monclús, Raquel; Blumstein, Daniel T

2012-01-01

96

JUVENILE LIFE HISTORY AND AGE COMPOSITION OF MATURE FALL CHINOOK SALMON RETURNING TO THE KLAMATH RIVER, 1984-1986  

Microsoft Academic Search

ABSTRACT The juvenile life history and age composition of Klamath River fall chinook salmon (Oncorhvnchus tshawvtscha) were determined for adult populations returning to major spawning tributaries from 1984 to 1986. Three juvenile life histories were identified from the analysis of adult scales. Most adults exhibited scale patterns indicative of typical summer emigration but a significant portion of some tributary populations

Cornelius M. Sullivan

1989-01-01

97

The cosmic ray primary composition at the knee region from lateral distributions of atmospheric C  

E-print Network

The cosmic ray primary composition at the knee region from lateral distributions of atmospheric C.40.De 96.40.Pq Keywords: Cosmic rays Extensive air showers Atmospheric C erenkov Chemical composition associated with extensive air showers to study the chemical composition of the primary cosmic rays

98

Agent-based semantic composition of Web services using distributed description logics  

E-print Network

Agent-based semantic composition of Web services using distributed description logics Mourad Ouziri Distributed Description Logics (DDL) to achieve the semantic composition of web services. DDL allows one to make semantic connections between ontologies and thus web services, as well as to reason to get

Paris-Sud XI, Université de

99

Strong Neutral Spatial Effects Shape Tree Species Distributions across Life Stages at Multiple Scales  

PubMed Central

Traditionally, ecologists use lattice (regional summary) count data to simulate tree species distributions to explore species coexistence. However, no previous study has explicitly compared the difference between using lattice count and basal area data and analyzed species distributions at both individual species and community levels while simultaneously considering the combined scenarios of life stage and scale. In this study, we hypothesized that basal area data are more closely related to environmental variables than are count data because of strong environmental filtering effects. We also address the contribution of niche and the neutral (i.e., solely dependent on distance) factors to species distributions. Specifically, we separately modeled count data and basal area data while considering life stage and scale effects at the two levels with simultaneous autoregressive models and variation partitioning. A principal coordinates of neighbor matrix (PCNM) was used to model neutral spatial effects at the community level. The explained variations of species distribution data did not differ significantly between the two types of data at either the individual species level or the community level, indicating that the two types of data can be used nearly identically to model species distributions. Neutral spatial effects represented by spatial autoregressive parameters and the PCNM eigenfunctions drove species distributions on multiple scales, different life stages and individual species and community levels in this plot. We concluded that strong neutral spatial effects are the principal mechanisms underlying the species distributions and thus shape biodiversity spatial patterns. PMID:22666497

Hu, Yue-Hua; Lan, Guo-Yu; Sha, Li-Qing; Cao, Min; Tang, Yong; Li, Yi-De; Xu, Da-Ping

2012-01-01

100

Influence of Interfacial Bond Strength on Fatigue Life and ThermoMechanical Behavior of a Particulate Composite: An Experimental Study  

Microsoft Academic Search

Experimental studies conducted on a particular cast acrylic composite demonstrate the significant influence of the interfacial bond strength between filler particles and the polymer matrix on the fatigue life, and mechanical properties. The composite studied in this project is composed of a ductile matrix, which is lightly cross-linked poly-methyl methacrylate (PMMA) and hard, brittle alumina trihydrate (ATH) agglomerate particle filler.

C. Basaran; S. Nie; C. S. Hutchins; H. Ergun

2008-01-01

101

Thermodynamic models of the distribution of life-related organic molecules in the interstellar medium  

NASA Astrophysics Data System (ADS)

New equilibrium thermodynamic distribution models of organic substances important to life in giant molecular clouds are suggested. These models use the normal distribution law of the standard enthalpy and the free energy (Helmholtz energy) for various organic molecules, amino acids, and nucleic acid components. These models were used to forecast organic molecule resources in the interstellar medium of the observable universe. The resources of the main biological molecules were estimated from radio-astronomical data.

Dolomatov, Michel Y.; Zhuravleva, Nadezhda A.

2014-05-01

102

Effect of carbide distribution on rolling-element fatigue life of AMS 5749  

NASA Technical Reports Server (NTRS)

Endurance tests with ball bearings made of corrosion resistant bearing steel which resulted in fatigue lives much lower than were predicted are discussed. Metallurgical analysis revealed an undesirable carbide distribution in the races. It was shown in accelerated fatigue tests in the RC rig that large, banded carbides can reduce rolling element fatigue life by a factor of approximately four. The early spalling failures on the bearing raceways are attributed to the large carbide size and banded distribution.

Parker, R. J.; Bamberger, E. N.

1983-01-01

103

Species composition, richness, and distribution of marine bivalve molluscs in Bahía de Mazatlán, México  

PubMed Central

Abstract We describe the composition and distribution of bivalve molluscs from the sandy and rocky intertidal and the shallow subtidal environments of Bahía de Mazatlán, México. The bivalve fauna of the bay is represented by 89 living species in 28 families, including 37 new records and four range extensions: Lithophaga hastasia, Adula soleniformis, Mactrellona subalata, and Strigilla ervilia. The number of species increases from the upper (44) and lower intertidal (53) to the shallow subtidal (76), but only 11 (17%) have a wide distribution in the bay (i.e., found in all sampling sites and environments). The bivalve assemblages are composed of four main life forms: 27 epifaunal species, 26 infaunal, 16 semi-infaunal, and 20 endolithic. A taxonomic distinctness analysis identified the sampling sites and environments that contribute the most to the taxonomic diversity (species to suborder categories) of the bay. The present work increased significantly (31%) to 132 species previous inventories of bivalves of Bahía de Mazatlán. These species represent 34% of the bivalve diversity of the southern Golfo de California and approximately 15% of the Eastern Tropical Pacific region. PMID:24843252

Esqueda-González, María del Carmen; Ríos-Jara, Eduardo; Galván-Villa, Cristian Moises; Rodríguez-Zaragoza, Fabian Alejandro

2014-01-01

104

OBSERVATIONS ON DISTRIBUTION AND LIFE HISTORY OF SKIPJACK TUNA, KATSUWONUS PELAMIS, IN  

E-print Network

OBSERVATIONS ON DISTRIBUTION AND LIFE HISTORY OF SKIPJACK TUNA, KATSUWONUS PELAMIS, IN AUSTRALIAN WATERS MAURICE BLACKBURN1 AND D. L. SERVENTy2 ABSTRACT Skipjack tuna occur in many areas around Australia in coastal waters is probably highest in the southeast. The southern limit of skipjack tuna range varies

105

THE COMPOSITION, ABUNDANCE, AND DEPTH DISTRIBUTION OF THE  

E-print Network

to 1952, possibly as a combined result of their long life cycle and effective predation." The potential supply and, subsequently, the growth and survival of juvenile sockeye salmon, Oncorhynchus nerka (Walbaum

106

DAMAGE DETECTION IN COMPOSITE STRUCTURES FROM FIBRE OPTIC DISTRIBUTED STRAIN MEASUREMENTS  

E-print Network

DAMAGE DETECTION IN COMPOSITE STRUCTURES FROM FIBRE OPTIC DISTRIBUTED STRAIN MEASUREMENTS Alfredo that the fiber does not need to have local engraved sensors. Distributed sensing is done by collecting - 7th European Workshop on Structural Health Monitoring (2014)" #12;1 DISTRIBUTED SENSING FOR STRAIN

Boyer, Edmond

107

Development of an eco-friendly method to convert life expired composite propellant into liquid fertilizer.  

PubMed

Large quantity of composite propellants is produced as waste due to life expiry of missiles/rejection of propellant lots during manufacturing. The environmental protection agency does not allow the hazardous materials for open burning/open detonation. Therefore, a systematic study has been carried out to develop a method for the disposal of composite propellant into liquid fertilizer without affecting the environment. In this study, propellant compositions were digested in dilute nitric acid followed by neutralization with 5M KOH solution to get precipitated out aluminium as aluminium hydroxide and finally the obtained liquid was treated with orthophosphoric acid for further neutralization. The liquid fertilizer, thus, obtained was characterized for nitrate and phosphate content using ion chromatography while ICP-AES was used for the estimation of potassium, aluminium and other noxious metallic elements such as Pb, Cd, As, Cr, Cu, Ni and Zn. The analyses data indicate that liquid fertilizer is free from aluminium and noxious metallic elements while ratio of nitrogen, phosphorous and potassium are close to the Indian NPK value. PMID:22265654

Mehilal; Dhabbe, K I; Kumari, Anjali; Manoj, V; Singh, P P; Bhattacharya, B

2012-02-29

108

Automated Shape Composition Based on Cell Biology and Distributed Genetic Programming  

E-print Network

Automated Shape Composition Based on Cell Biology and Distributed Genetic Programming Linge Bai lb to developmental biology for concepts that lead to a more organic, cell-biology-inspired approach to shape

Fernandez, Thomas

109

Primary igneous rocks on Mars: Composition and distribution  

NASA Technical Reports Server (NTRS)

The present knowledge of the crustal composition of Mars is synthesized and implications discussed for in-situ resource utilization. Sources of information include remote sensing observations, Viking XRF chemical measurements, and characteristics of the SNC meteorites (which most researchers now believe originated on Mars). There are a number of lines of evidence that abundant ferrous-iron rich igneous crustal rocks (and derivative soils) are available at or very near the current Martian surface at many locations on the planet. Most of these exposures show spectroscopic evidence for abundant pyroxene, consistent with basaltic compositions. The SNC meteorites, which have basaltic compositions, were also studied extensively. Interpretations of Mars crustal chemistry and mineralogy (petrology) based on these various sources are reviewed, and their consistencies and differences are discussed.

Singer, Robert B.; Mcsween, Harry Y., Jr.

1991-01-01

110

A model for predicting damage induced fatigue life of laminated composite structural components  

NASA Technical Reports Server (NTRS)

This paper presents a model for predicting the life of laminated composite structural components subjected to fatigue induced microstructural damage. The model uses the concept of continuum damage mechanics, wherein the effects of microcracks are incorporated into a damage dependent lamination theory instead of treating each crack as an internal boundary. Internal variables are formulated to account for the effects of both matrix cracks and internal delaminations. Evolution laws for determining the damage variables as functions of ply stresses are proposed, and comparisons of predicted damage evolution are made to experiment. In addition, predicted stiffness losses, as well as ply stresses are shown as functions of damage state for a variety of stacking sequences.

Allen, David H.; Lo, David C.; Georgiou, Ioannis T.; Harris, Charles E.

1990-01-01

111

A Framework for ObjectBased Event Composition in Distributed Systems  

E-print Network

are either event sources that publish new events or event sinks that subscribe to events. Events can be seen composite event detections to be placed as near to the event sources as possible, and reused amongA Framework for Object­Based Event Composition in Distributed Systems Peter R. Pietzuch and Brian

Cambridge, University of

112

A Framework for Object-Based Event Composition in Distributed Systems  

E-print Network

are either event sources that publish new events or event sinks that subscribe to events. Events can be seen composite event detections to be placed as near to the event sources as possible, and reused amongA Framework for Object-Based Event Composition in Distributed Systems Peter R. Pietzuch and Brian

Cambridge, University of

113

The distribution and composition of organic matter in recent deltaic and submarine fan sediments  

E-print Network

THE DISTRIBUTION AND COMPOSITION OF ORGANIC MATTER IN RECFNT DELTAIC AND SUBMARINE FAN SEDIMENTS A Thesis by DEBRA ANN DEFREITAS Submitted to the Graduate College of Texas A&N University in partial fulfillment of the requirement... for the degree of MASTER OF SCIENCE May 1988 Major Subject: Oceanography THE DISTRIBUTION AND COMPOSITION OF ORGANIC MATTER IN RECENT DELTAIC AND SUBMARINE FAN SEDIMENTS A Thesis by DEBRA ANN DEFREITAS Approved as to style and content by: James M. Bro...

DeFreitas, Debra Ann

2012-06-07

114

Fatigue-life behavior and matrix fatigue crack spacing in unnotched SCS-6/Timetal 21S metal matrix composites  

NASA Technical Reports Server (NTRS)

Fatigue tests of the SCS-6/Timetal 21S composite system were performed to characterize the fatigue behavior for unnotched conditions. The stress-life behavior of the unnotched (9/90)2s laminates was investigated for stress ratios of R = 0.1 and R = 0.3. The occurrence of matrix cracking was also examined in these specimens. This revealed multiple matrix crack initiation sites throughout the composite, as well as evenly spaced surface cracks along the length of the specimens. No difference in fatigue lives were observed for stress ratios of R = 0.1 and R = 0.3 when compared on a stress range basis. The unnotched SCS-6/Timetal 21S composites had shorter fatigue lives than the SCS-6/Ti-15-3 composites, however the neat Timetal 21S matrix material had a longer fatigue life than the neat Ti-15-3.

Ward, G. T.; Herrmann, D. J.; Hillberry, B. M.

1993-01-01

115

CONTROL OF DROPLET SIZE DISTRIBUTION IN STARCH-OIL COMPOSITES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Previous work has shown that a stable dispersion of oil droplets can be obtained by combining an aqueous slurry of starch and oil in an excess steam jet cooker. The resulting starch oil composites have been used in a broad range of food and industrial applications. During jet cooking, the starch i...

116

Grana Padano cheese whey starters: Microbial composition and strain distribution  

Microsoft Academic Search

The aim of this work was to evaluate the species composition and the genotypic strain heterogeneity of dominant lactic acid bacteria (LAB) isolated from whey starter cultures used to manufacture Grana Padano cheese. Twenty-four Grana Padano cheese whey starters collected from dairies located over a wide geographic production area in the north of Italy were analyzed. Total thermophilic LAB streptococci

Lia Rossetti; Maria Emanuela Fornasari; Monica Gatti; Camilla Lazzi; Erasmo Neviani; Giorgio Giraffa

2008-01-01

117

Viral Distribution and Life Strategies in the Bach Dang Estuary, Vietnam  

Microsoft Academic Search

Although the structure and dynamics of planktonic viruses in freshwater and seawater environments are relatively well documented,\\u000a little is known about the occurrence and activity of these viruses in estuaries, especially in the tropics. Viral abundance,\\u000a life strategies, and morphotype distribution were examined in the Bach Dang Estuary (Vietnam) during the dry season in 2009.\\u000a The abundance of both viruses

Yvan Bettarel; Thierry Bouvier; Martin Agis; Corinne Bouvier; Thuoc Van Chu; Marine Combe; Xavier Mari; Minh Ngoc Nghiem; Thuy Thanh Nguyen; Thu The Pham; Olivier Pringault; Emma Rochelle-Newall; Jean-Pascal Torréton; Huy Quang Tran

118

A counter-reductionist argument for the influence of solute composition on ostracode distribution: Implications for paleoecology  

SciTech Connect

The utility of fossil ostracodes for tracking climatically-driven Holocene physicochemical changes of lakes has been a recurrent theme in paleoenvironmental research. Recent studies, aimed at improving the precision of ostracode-mediated environmental reconstructions, have attempted to decipher this robust, ostracode-climate, couplet, and strong correlational evidence concerning the influence of solute composition on ostracode distribution has emerged. By drawing on two examples, namely the response of ostracodes to (1) Holocene hydrocompositional changes in a lake from Russell, Manitoba, and (2) the anthropogenic contamination of groundwater along an urban-rural transect in south-central Ontario, a hypothesis is generated to explain this apparent association. Contrary to the reductionist opinions (i.e. that hydrochemistry operates on ostracode distribution through the direct imposition of physiological barriers), solute composition is viewed as a surrogate variable through which to evaluate cumulative, immeasurable effects of climate, geology, hydrology and the biosphere (including humans). By virtue of their short life-cycles, it is suggested that ostracodes would overcome evolutionary barriers imposed by gradual changes in solute composition if it uniquely controlled their occurrence. Solving this problem would enhance the resolving power of paleoenvironmental reconstructions and, if the proposed argument is valid, it may lend credibility to uniformitarian principles operative in Quaternary paleoecology. The replacement of one group of species by another better adapted to an environment in its totality, seems more likely to hold up in ecological time, than adaptation to a single, specific, overriding hydrochemical parameter.

Taylor, L.C.; Howard, K.W.F. (Univ. of Toronto, Ontario (Canada))

1992-01-01

119

Spatial distribution of total, ammonia-oxidizing, and denitrifying bacteria in biological wastewater treatment reactors for bioregenerative life support  

NASA Technical Reports Server (NTRS)

Bioregenerative life support systems may be necessary for long-term space missions due to the high cost of lifting supplies and equipment into orbit. In this study, we investigated two biological wastewater treatment reactors designed to recover potable water for a spacefaring crew being tested at Johnson Space Center. The experiment (Lunar-Mars Life Support Test Project-Phase III) consisted of four crew members confined in a test chamber for 91 days. In order to recycle all water during the experiment, an immobilized cell bioreactor (ICB) was employed for organic carbon removal and a trickling filter bioreactor (TFB) was utilized for ammonia removal, followed by physical-chemical treatment. In this study, the spatial distribution of various microorganisms within each bioreactor was analyzed by using biofilm samples taken from four locations in the ICB and three locations in the TFB. Three target genes were used for characterization of bacteria: the 16S rRNA gene for the total bacterial community, the ammonia monooxygenase (amoA) gene for ammonia-oxidizing bacteria, and the nitrous oxide reductase (nosZ) gene for denitrifying bacteria. A combination of terminal restriction fragment length polymorphism (T-RFLP), sequence, and phylogenetic analyses indicated that the microbial community composition in the ICB and the TFB consisted mainly of Proteobacteria, low-G+C gram-positive bacteria, and a Cytophaga-Flexibacter-Bacteroides group. Fifty-seven novel 16S rRNA genes, 8 novel amoA genes, and 12 new nosZ genes were identified in this study. Temporal shifts in the species composition of total bacteria in both the ICB and the TFB and ammonia-oxidizing and denitrifying bacteria in the TFB were also detected when the biofilms were compared with the inocula after 91 days. This result suggests that specific microbial populations were either brought in by the crew or enriched in the reactors during the course of operation.

Sakano, Yuko; Pickering, Karen D.; Strom, Peter F.; Kerkhof, Lee J.; Janes, H. W. (Principal Investigator)

2002-01-01

120

Thermal analysis of soft magnetic composite motors using a hybrid model with distributed heat sources  

Microsoft Academic Search

This paper presents a hybrid thermal model with distributed heat sources for thermal analysis of soft magnetic composite (SMC) motors. The model uses a combination of lumped and distributed thermal parameters, which can be obtained from motor dimensions and thermal constants. The model can be used to calculate the core loss in each part, in combination with three-dimensional magnetic field

Youguang Guo; Jian Guo Zhu; Wei Wu

2005-01-01

121

Application of distributed PVDF actuators to the control of sound transmission through composite plate  

Microsoft Academic Search

Using the fact that anisotropy and shape of distributed piezopolymer actuator have coupling effects with vibration modes of structure, studies on the design of distributed piezopolymer actuator are performed in order to improve the effectiveness in active control of the sound transmission through composite structures. Sound fields from integrated structure are highly influenced by the vibration modes of structure. Therefore

Ki Won Yoon; Seung-Jo Kim; Wie Dae Kim

1997-01-01

122

25 CFR 179.201 - How does the Secretary distribute principal and income to the holder of a life estate without...  

Code of Federal Regulations, 2014 CFR

...distribute principal and income to the holder of a life estate without regard to waste? 179.201 ...DEPARTMENT OF THE INTERIOR LAND AND WATER LIFE ESTATES AND FUTURE INTERESTS Life Estates Created Under AIPRA § 179.201...

2014-04-01

123

25 CFR 179.201 - How does the Secretary distribute principal and income to the holder of a life estate without...  

Code of Federal Regulations, 2012 CFR

...distribute principal and income to the holder of a life estate without regard to waste? 179.201 ...DEPARTMENT OF THE INTERIOR LAND AND WATER LIFE ESTATES AND FUTURE INTERESTS Life Estates Created Under AIPRA § 179.201...

2012-04-01

124

25 CFR 179.201 - How does the Secretary distribute principal and income to the holder of a life estate without...  

Code of Federal Regulations, 2013 CFR

...distribute principal and income to the holder of a life estate without regard to waste? 179.201 ...DEPARTMENT OF THE INTERIOR LAND AND WATER LIFE ESTATES AND FUTURE INTERESTS Life Estates Created Under AIPRA § 179.201...

2013-04-01

125

25 CFR 179.201 - How does the Secretary distribute principal and income to the holder of a life estate without...  

Code of Federal Regulations, 2010 CFR

...distribute principal and income to the holder of a life estate without regard to waste? 179.201 ...DEPARTMENT OF THE INTERIOR LAND AND WATER LIFE ESTATES AND FUTURE INTERESTS Life Estates Created Under AIPRA § 179.201...

2010-04-01

126

25 CFR 179.201 - How does the Secretary distribute principal and income to the holder of a life estate without...  

Code of Federal Regulations, 2011 CFR

...distribute principal and income to the holder of a life estate without regard to waste? 179.201 ...DEPARTMENT OF THE INTERIOR LAND AND WATER LIFE ESTATES AND FUTURE INTERESTS Life Estates Created Under AIPRA § 179.201...

2011-04-01

127

A creep cavity growth model for creep-fatigue life prediction of a unidirectional W/Cu composite  

NASA Technical Reports Server (NTRS)

A microstructural model was developed to predict creep-fatigue life in a (0)(sub 4), 9 volume percent tungsten fiber-reinforced copper matrix composite at the temperature of 833 K. The mechanism of failure of the composite is assumed to be governed by the growth of quasi-equilibrium cavities in the copper matrix of the composite, based on the microscopically observed failure mechanisms. The methodology uses a cavity growth model developed for prediction of creep fracture. Instantaneous values of strain rate and stress in the copper matrix during fatigue cycles were calculated and incorporated in the model to predict cyclic life. The stress in the copper matrix was determined by use of a simple two-bar model for the fiber and matrix during cyclic loading. The model successfully predicted the composite creep-fatigue life under tension-tension cyclic loading through the use of this instantaneous matrix stress level. Inclusion of additional mechanisms such as cavity nucleation, grain boundary sliding, and the effect of fibers on matrix-stress level would result in more generalized predictions of creep-fatigue life.

Kim, Young-Suk; Verrilli, Michael J.; Halford, Gary R.

1992-01-01

128

Composite Weibull-Inverse Transformed Gamma distribution and its actuarial application  

NASA Astrophysics Data System (ADS)

This paper introduces a new composite model, namely, composite Weibull-Inverse Transformed Gamma distribution which assumes Weibull distribution for the head up to a specified threshold and inverse transformed gamma distribution beyond it. The closed form of probability density function (pdf) as well as the estimation of parameters by maximum likelihood method is presented. The model is compared with several benchmark distributions and their performances are measured. A well-known data set, Danish fire loss data, is used for this purpose and it's Value at Risk (VaR) using the new model is computed. In comparison to several standard models, the composite Weibull- Inverse Transformed Gamma model proved to be a competitor candidate.

Maghsoudi, Mastoureh; Bakar, Shaiful Anuar Abu; Hamzah, Nor Aishah

2014-07-01

129

Context Distribution for Supporting Composition of Applications in Ubiquitous Computing  

E-print Network

explained previously would be represented by the following Java code. @Entity public class Cellphone { @Attribute static String phoneNumber ; } @RuleSet class LightRules { @Rule public void rule1 (){ if(Cellphone without fee provided that copies are not made or distributed for profit or commercial advantage

Paris-Sud XI, Université de

130

Identifying the failure mechanism in accelerated life tests by two-parameter lognormal distributions  

NASA Astrophysics Data System (ADS)

The failure mechanism stimulated by accelerated stress in the degradation may be different from that under normal conditions, which would lead to invalid accelerated life tests. To solve the problem, we study the relation between the Arrhenius equation and the lognormal distribution in the degradation process. Two relationships of the lognormal distribution parameters must be satisfied in the conclusion of the unaltered failure mechanism, the first is that the logarithmic standard deviations must be equivalent at different temperature levels, and the second is that the ratio of the differences between logarithmic means must be equal to the ratio of the differences between reciprocals of temperature. The logarithm of distribution lines must simultaneously have the same slope and regular interval lines. We studied the degradation of thick-film resistors in MCM by accelerated stress at four temperature levels (390, 400, 410 and 420 K), and the result agreed well with our method.

Chunsheng, Guo; Yanfeng, Zhang; Ning, Wan; Hui, Zhu; Shiwei, Feng

2014-08-01

131

Nutrient composition and respiration characteristics of silkworms in the Bioregenerative Life Support System  

NASA Astrophysics Data System (ADS)

As the appropriate space animal candidate, silkworm(Bombyx Mori L.) can supply animal food for taikonauts and consume inedible parts of plants in Bioregenerative Life Support Sys-tem(BLSS). Due to the features of BLSS, the silkworm breeding method in the system differ-ent from the conventional one is feeding the silkworm in the first three developing stages with mulberry leaves and with lettuce leaves in the latter two developing stages. Therefore, it is nec-essary to investigate the biochemical components and respiration characteristics of silkworms raised with this method to supply data bases for the inclusion of silkworms in the system to conduct system experiments. The nutrient compositions of silkworm powder (SP) which are the grinded and freeze-dried silkworm on the 3rd day in the fifth developing stage containing protein, fat, vitamins, minerals and fatty acids were determined with international standard analyzing methods in this study. The results showed that SP was rich in protein and amino acids. There were twelve kinds of essential vitamins, nine kinds of minerals and twelve kinds of fatty acids in SP. In contrast, SP had much better nutrient components than snail, fish, chicken, beef and pork as animal food for crew members. Moreover, 359 kCal can be generated per 100g of SP (dry weight). The respirations of silkworm during its whole growing process under two main physiological statuses which were eating and non-eating leaves were studied. According to the results measured by the animal respiration measuring system, there were much difference among the respirations of silkworms under the two main physiological statuses. The amounts of O2 inhaled and CO2 exhaled by the silkworms when they were eating leaves were more than those under the non-eating status. Even under the same status, the respiration characteristics of silkworms in five different developing stages were also different from one an-other. The respiratory quotients of silkworms under two statuses are largely different (eating F=3.191, P<0.05; non-eating F=2.935, P <0.05). Moreover, the amounts of O2 inhaled and CO2 exhaled by the silkworms in the first three developing stages were much more than those of the silkworms in the latter two developing stages per unit weight of leaves. These results concerning the nutrient compositions and respiration characteristics of silkworms can provide valuable data for the establishment of complex bioregenerative life support systems including different biological units in the lunar or mars bases in the future.

Tong, Ling; Yu, Xiaohui; Liu, Hong

132

Particle distribution control in cast aluminium alloy-mica composites  

Microsoft Academic Search

A suspension of mica particles (40µm diameter and 3.7µ thick) obtained in a mechanically stirred Al-4 wt % Cu-1.5 wt % Mg melt was poured and solidified in a variety of moulds under different heat flow configurations. The resulting cast structure showed a non-uniform distribution of dispersed mica particles with mica-depleted and segregated zones due to their flotation before and

Deo Nath; Rajiv Asthana; P. K. Rohatgi

1987-01-01

133

6-year changes in body composition in women at mid-life: ovarian and chronological aging  

PubMed Central

Context Understanding the menopause association with body weight is important because excess weight increases risk for stroke, incident cardiovascular disease, cardiovascular mortality, and all-cause mortality among the middle-aged. Objective To examine chronological age and ovarian age and consider how these could influence body size and composition in mid-life women. Design and Setting The Study of Women’s Health Across the Nation is a longitudinal, community-based study. This report uses data from the Michigan SWAN site. Participants 543 pre- or early perimenopausal African-American and Caucasian women aged 42–52 years at baseline examination. Main Outcome Measures Waist circumference, fat mass and skeletal muscle mass, from bioelectrical impedance, was assessed in 7 annual serial measures. Annual follicle-stimulating hormone (FSH) values were assayed by ELISA. The final menstrual period (FMP) was defined retrospectively following 12 months of amenorrhea. Results There was an absolute cumulative six-year increase in fat mass of 3.4 kg and a six-year decrease in skeletal muscle mass of ~0.23 kg. There was an absolute cumulative six-year increase of ~5.7 cm in waist circumference. The logFSH change was positively correlated with log(fat mass) change. Waist circumference increased over the time period, but one year following FMP, the rate of increase slowed. Fat mass continued to increase with no change in rate. Conclusions Both time (chronological aging) and ovarian aging contributed to substantial changes in body composition (fat and skeletal muscle mass) and waist circumference. These changes have important ramifications for establishing a metabolic environment that can be healthy or unhealthy. PMID:17192296

Sowers, MaryFran; Zheng, Huiyong; Tomey, Kristin; Karvonen-Gutierrez, Carrie; Jannausch, Mary; Li, Xizhao; Yosef, Matheos; Symons, James

2009-01-01

134

Activity energy expenditure and change in body composition in late life123  

PubMed Central

Background: Change in body composition, specifically loss of fat-free mass and gain in fat mass, in older adults is a major pathway leading to the onset of functional decline and physical disability. Objective: The objective was to determine the association of activity-related energy expenditure with change in body mass and composition among older men and women. Design: Total energy expenditure (TEE) was assessed over 2 wk by using the doubly labeled water method in 302 community-dwelling older adults aged 70–82 y. Resting metabolic rate (RMR) was measured by using indirect calorimetry, and the thermic effect of meals was estimated at 10% of TEE. Activity energy expenditure (AEE) was calculated as [TEE(0.9) ? RMR]. Total body mass, fat-free mass (FFM), and fat mass (FM) were assessed by dual-energy X-ray absorptiometry annually over a mean (±SD) of 4.9 ± 1.3 y. Results: In multivariate models adjusted for baseline age, smoking status, and race, men and women had a decline (in kg/y) in body mass (men: ?0.34, 95% CI: ?0.71, 0.02; women: ?0.45, 95% CI: ?0.71, ?0.19) and FFM (men: ?0.48, 95% CI: ?0.67, ?0.29; women: ?0.14, 95% CI: ?0.026, ?0.03). No changes (in kg/y) were observed in FM (men: 0.14, 95% CI: ?0.10, 0.38; women: ?0.28, 95% CI: ?0.49, ?0.07). In men and women, higher AEE at baseline was associated with greater FFM. The average change in these outcomes (ie, slope), however, was similar across tertiles of AEE. Conclusions: These data suggest that accumulated energy expenditure from all physical activities is associated with greater FFM, but the effect does not alter the trajectory of FFM change in late life. PMID:19740971

Everhart, James E; Anton, Stephen D; Schoeller, Dale A; Cummings, Steve R; Mackey, Dawn C; Delmonico, Matthew J; Bauer, Douglas C; Simonsick, Eleanor M; Colbert, Lisa H; Visser, Marjolein; Tylavsky, Frances; Newman, Anne B; Harris, Tamara B

2009-01-01

135

Forced wave propagation and energy distribution in anisotropic laminate composites.  

PubMed

Elastodynamic response of anisotropic laminate composite structures subjected to a force loading is evaluated based on the integral representations in terms of Green's matrices. Explicit and asymptotic expressions for guided waves generated by a given source are then obtained from those integrals by means of series expansions and the residue technique. Unlike to conventional modal expansions, such representations keep information about the source, giving an opportunity for a quantitative near- and far-field analysis of generated waves. An effective computer implementation is achieved by the use of fast and stable algorithms for the Green matrix, pole, and residue calculations. The potential of the model is demonstrated by examples of anisotropy manifestation in the directivity of radiated waves. The effect of main energy outflow in the direction of either upper- or inner-ply orientation depending on the source size and frequency is discussed. PMID:21568395

Glushkov, Evgeny; Glushkova, Natalia; Eremin, Artem

2011-05-01

136

Life Limiting Behavior in Interlaminar Shear of Continuous Fiber-Reinforced Ceramic Matrix Composites at Elevated Temperatures  

NASA Technical Reports Server (NTRS)

Interlaminar shear strength of four different fiber-reinforced ceramic matrix composites was determined with doublenotch shear test specimens as a function of test rate at elevated temperatures ranging from 1100 to 1316 C in air. Life limiting behavior, represented as interlaminar shear strength degradation with decreasing test rate, was significant for 2-D crossplied SiC/MAS-5 and 2-D plain-woven C/SiC composites, but insignificant for 2-D plain-woven SiC/SiC and 2-D woven Sylramic (Dow Corning, Midland, Michigan) SiC/SiC composites. A phenomenological, power-law delayed failure model was proposed to account for and to quantify the rate dependency of interlaminar shear strength of the composites. Additional stress rupture testing in interlaminar shear was conducted at elevated temperatures to validate the proposed model. The model was in good agreement with SiC/MAS-5 and C/SiC composites, but in poor to reasonable agreement with Sylramic SiC/SiC. Constant shear stress-rate testing was proposed as a possible means of life prediction testing methodology for ceramic matrix composites subjected to interlaminar shear at elevated temperatures when short lifetimes are expected.

Choi, Sung R.; Calomino, Anthony M.; Bansal, Narottam P.; Verrilli, Michael J.

2006-01-01

137

Kinetics of Formation of Molecular Weight Distribution of Epoxy Composite  

NASA Astrophysics Data System (ADS)

Curing of epoxy matrix prepreg in free space environment is a complex problem. A simulation of the chemical reaction, evaporation and radiation effects in the matrix is a way to understand and predict the curing process. We have developed a mathematical apparatus of the epoxy resin kinetics in term of molecular weight distribution (MWD), which includes the polymerization mechanism of bifunctional epoxy and sixfunctional triethylenetetraamine (TETA) molecules. The mathematical model for a number of molecules with the mass m at time t is based on the following equation $ beta(t,m)=m_{am} / m sum(6}_{i=0) alpha(am) _i (t,m)+ m_{ep} / m sum(2}_{i=0) alpha(ep) _i (t,m), where m_{am} and m_{ep} are the masses of one amine block and one epoxy block, respectively; alpha^{am}_i (t,m) is the MWD near the TETA blocks with the chemical bonds i at time t for the mass values m>0; alpha_i^{ep}(t,m) is the MWD parameters of the epoxy blocks with chemical bonds i at time t for the mass values m>0. For the distribution densities alpha^{am}_i (t,m) and alpha_i^{ep}(t,m), we propose the differential system of equations, which has been solved by applying boundary conditions which are based on the results of chromatography and infrared spectroscopy measurements of the epoxy matrix having different concentration of the hardener. For the initial MWD we accept a Gaussian distribution with parameters alpha^{am}_0 (t,m_1) =146 amu, alpha_0^{ep}(t,m_1) =340 amu and alpha_1^{ep}(t,m_1) =624 amu. Dispersion of the molecular weight for the initial distribution equals to 25 amu. A portion of TETA molecules in the fraction was 25%, and the portion of epoxy molecules with i=0 and i=1 was 67.5% and 7.5%$, respectively. Solutions were obtained at mass step equals to 5 amu and at time step equals to 0.25 min over the interval from 0 to 500 min. The model gives a full kinetic of MWD during the curing reaction. The study is supported by the RFBR (grants N 12-08-00970-a and N 14-08-96011-r-ural-a).

Komar, Lyudmila A.; Kondyurin, Alexey; Svistkov, Alexander L.

138

Loading Analysis of Composite Wind Turbine Blade for Fatigue Life Prediction of Adhesively Bonded Root Joint  

NASA Astrophysics Data System (ADS)

Nowadays wind energy is widely used as a non-polluting cost-effective renewable energy resource. During the lifetime of a composite wind turbine which is about 20 years, the rotor blades are subjected to different cyclic loads such as aerodynamics, centrifugal and gravitational forces. These loading conditions, cause to fatigue failure of the blade at the adhesively bonded root joint, where the highest bending moments will occur and consequently, is the most critical zone of the blade. So it is important to estimate the fatigue life of the root joint. The cohesive zone model is one of the best methods for prediction of initiation and propagation of debonding at the root joint. The advantage of this method is the possibility of modeling the debonding without any requirement to the remeshing. However in order to use this approach, it is necessary to analyze the cyclic loading condition at the root joint. For this purpose after implementing a cohesive interface element in the Ansys finite element software, one blade of a horizontal axis wind turbine with 46 m rotor diameter was modelled in full scale. Then after applying loads on the blade under different condition of the blade in a full rotation, the critical condition of the blade is obtained based on the delamination index and also the load ratio on the root joint in fatigue cycles is calculated. These data are the inputs for fatigue damage growth analysis of the root joint by using CZM approach that will be investigated in future work.

Salimi-Majd, Davood; Azimzadeh, Vahid; Mohammadi, Bijan

2014-07-01

139

A Comparison of Various Stress Rupture Life Models for Orbiter Composite Pressure Vessels and Confidence Intervals  

NASA Technical Reports Server (NTRS)

In conjunction with a recent NASA Engineering and Safety Center (NESC) investigation of flight worthiness of Kevlar Overwrapped Composite Pressure Vessels (COPVs) on board the Orbiter, two stress rupture life prediction models were proposed independently by Phoenix and by Glaser. In this paper, the use of these models to determine the system reliability of 24 COPVs currently in service on board the Orbiter is discussed. The models are briefly described, compared to each other, and model parameters and parameter uncertainties are also reviewed to understand confidence in reliability estimation as well as the sensitivities of these parameters in influencing overall predicted reliability levels. Differences and similarities in the various models will be compared via stress rupture reliability curves (stress ratio vs. lifetime plots). Also outlined will be the differences in the underlying model premises, and predictive outcomes. Sources of error and sensitivities in the models will be examined and discussed based on sensitivity analysis and confidence interval determination. Confidence interval results and their implications will be discussed for the models by Phoenix and Glaser.

Grimes-Ledesma, Lorie; Murthy, Pappu L. N.; Phoenix, S. Leigh; Glaser, Ronald

2007-01-01

140

A Comparison of Various Stress Rupture Life Models for Orbiter Composite Pressure Vessels and Confidence Intervals  

NASA Technical Reports Server (NTRS)

In conjunction with a recent NASA Engineering and Safety Center (NESC) investigation of flight worthiness of Kevlar Ovenvrapped Composite Pressure Vessels (COPVs) on board the Orbiter, two stress rupture life prediction models were proposed independently by Phoenix and by Glaser. In this paper, the use of these models to determine the system reliability of 24 COPVs currently in service on board the Orbiter is discussed. The models are briefly described, compared to each other, and model parameters and parameter error are also reviewed to understand confidence in reliability estimation as well as the sensitivities of these parameters in influencing overall predicted reliability levels. Differences and similarities in the various models will be compared via stress rupture reliability curves (stress ratio vs. lifetime plots). Also outlined will be the differences in the underlying model premises, and predictive outcomes. Sources of error and sensitivities in the models will be examined and discussed based on sensitivity analysis and confidence interval determination. Confidence interval results and their implications will be discussed for the models by Phoenix and Glaser.

Grimes-Ledesma, Lorie; Murthy, Pappu, L. N.; Phoenix, S. Leigh; Glaser, Ronald

2006-01-01

141

Nonparametric Fine Tuning of Mixtures: Application to Non-Life Insurance Claims Distribution Estimation  

NASA Astrophysics Data System (ADS)

When pricing a specific insurance premium, actuary needs to evaluate the claims cost distribution for the warranty. Traditional actuarial methods use parametric specifications to model claims distribution, like lognormal, Weibull and Pareto laws. Mixtures of such distributions allow to improve the flexibility of the parametric approach and seem to be quite well-adapted to capture the skewness, the long tails as well as the unobserved heterogeneity among the claims. In this paper, instead of looking for a finely tuned mixture with many components, we choose a parsimonious mixture modeling, typically a two or three-component mixture. Next, we use the mixture cumulative distribution function (CDF) to transform data into the unit interval where we apply a beta-kernel smoothing procedure. A bandwidth rule adapted to our methodology is proposed. Finally, the beta-kernel density estimate is back-transformed to recover an estimate of the original claims density. The beta-kernel smoothing provides an automatic fine-tuning of the parsimonious mixture and thus avoids inference in more complex mixture models with many parameters. We investigate the empirical performance of the new method in the estimation of the quantiles with simulated nonnegative data and the quantiles of the individual claims distribution in a non-life insurance application.

Sardet, Laure; Patilea, Valentin

142

Waste prevention in liquid detergent distribution: a comparison based on life cycle assessment.  

PubMed

The distribution of liquid detergents through self-dispensing systems has been adopted in some Italian retail stores over the last few years. By enabling the consumer to refill several times the same container, it is proposed as a less waste-generating and more environmentally friendly alternative to the traditional distribution with single-use plastic containers. For this reason, its implementation is encouraged by the national waste prevention programme recently adopted in Italy. In order to assess such claims, a life cycle assessment was carried out to evaluate whether detergent distribution through self-dispensing systems actually allows to achieve the expected reduction in waste generation and environmental impacts. The focus was on the distribution within the large-scale retail trade and on the categories of laundry detergents, fabric softeners and hand dishwashing detergents. For each of them, a set of baseline single-use scenarios were compared with two alternative waste prevention scenarios, where the detergent is distributed through self-dispensing systems. Beyond waste generation, also the Cumulative Energy Demand and thirteen midpoint-level potential impact indicators were calculated for the comparison. Results showed that a reduction in waste generation up to 98% can be achieved, depending on the category of detergent, on the baseline scenario of comparison and on the number of times the refillable container is used. A progressive reduction in the energy demand and in most of the potential impacts was also observed, starting from a minimum number of uses of the refillable container. PMID:25209251

Nessi, Simone; Rigamonti, Lucia; Grosso, Mario

2014-11-15

143

Distribution patterns of different carbon nanostructures in silicon nitride composites.  

PubMed

The dispersion properties of single- and multi-walled carbon nanotubes as well as mechanically exfoliated few layer graphene flakes within the silicon nitride ceramic matrix have been investigated. Small angle neutron scattering experiments have been employed to gain information on the dispersion of the nano-scale carbon fillers throughout the entire volume of the samples. The neutron scattering data combined with scanning electron microscopy revealed strikingly different distribution patterns for different types of carbon nanostructures. The scattering intensities for single wall carbon nanotubes (SWCNTs) reveal a decay exponent characteristic to surface fractals, which indicate that the predominant part of nanotubes can be found in loose networks wrapping the grains of the polycrystalline matrix. By contrast, multi wall carbon nanotubes (MWCNTs) were found to be present mainly in the form of bulk aggregate structures, while few-layer graphene (FLG) flakes have been individually dispersed within the host matrix, under the very same preparation and processing conditions. PMID:23421284

Tapasztó, Orsolya; Markó, Márton; Balázsi, Csaba

2012-11-01

144

Distribution of graphene oxide and TiO2-graphene oxide composite in A549 cells.  

PubMed

Graphene and its derivatives are increasingly applied in nanoelectronics, biosensing, drug delivery, and biomedical applications. However, the information about its cytotoxicity remains limited. Herein, the distribution and cytotoxicity of graphene oxide (GO) and TiO2-graphene oxide composite (TiO2-GO composite) were evaluated in A549 cells. Cell viability and cell ultrastructure were measured. Our results indicated that GO could enter A549 cells and located in the cytoplasm and nucleus without causing any cell damage. TiO2 nanoparticles and GO would be separated after TiO2-GO composite entered A549 cells. TiO2-GO composite could induce cytotoxicity similar to TiO2 nanoparticles, which was probably attributed to oxidative stress. These results should be considered in the development of biological applications of GO and TiO2-GO composite. PMID:24869803

Jin, Chan; Wang, Fude; Tang, Ying; Zhang, Xiangzhi; Wang, Jianqiang; Yang, Yongji

2014-06-01

145

Perchlorate in The Great Lakes: Distribution, Isotopic Composition and Origin  

NASA Astrophysics Data System (ADS)

Concentrations, stable chlorine and oxygen isotopic compositions, and 36Cl abundances of perchlorate were investigated in the five Laurentian Great Lakes. Samples were collected during monitoring cruises in 2007 and 2008 of the U.S. EPA's RV Lake Guardian and in 2010 at the water supply intake of Marquette, MI on the southern shore of Lake Superior. Concentrations of perchlorate were measured by IC/MS/MS at 24 locations, including one or two depth profiles in each lake. Mean concentrations (?g/L) are: Superior, 0.06 × 0.01; Michigan, 0.10 × 0.01; Huron, 0.11 × 0.01; Erie, 0.08 × 0.01, and Ontario, 0.09 × 0.01. Concentration vs. depth is nearly constant in each lake, indicating well-mixed conditions. Perchlorate was extracted from near-surface water by passing 15,000 to 80,000 L of water through 1-L cartridges containing Purolite A530E bifunctional anion-exchange resin. In the laboratory, perchlorate was eluted from the resin, purified, and precipitated as a >99% pure crystalline phase. Milligram amounts were recovered from each lake. Chlorine and oxygen isotopic analyses were performed at Caltech using the Cameca 7f-GEO SIMS instrument, following validation of the SIMS method with analyses of USGS-37 and USGS-38 isotopic reference materials. Results indicate a relatively narrow range in ?37Cl values (+2.9 to +3.9 ‰) and a wider range in ?18O values (-4.0 to +4.1 ‰), with a general geographic trend of increasing ?18O from west to east. Oxygen-17 was measured at UIC using dual-inlet IRMS of O2 produced by decomposition of KClO4. Great Lakes perchlorate has mass-independent oxygen isotopic variations with positive ?17O values (+1.6 ‰ to +2.7 ‰) divided into two distinct groups: Lake Superior (+2.7 ‰) and the other four lakes (~ +1.7 ‰). The isotopic data indicate that perchlorate is dominantly of natural origin, having stable isotopic compositions resembling those of perchlorate from pre-industrial groundwaters in the western USA. The 36Cl/Cl ratios decrease from Lake Superior (66,500×10-15) to Lake Ontario (7,400×10-15). The high 36Cl/Cl ratios in the lakes having longer water residence times may be explained by retention of perchlorate formed during the time of the 36Cl bomb pulse (1952-1964). Mass balance of perchlorate indicates that substantial biodegradation or uptake of perchlorate may occur in Lake Erie. 36Cl/Cl results confirm that perchlorate in the Great Lakes has dominantly natural origin. These data provide better constraints on possible perchlorate source(s), mixing proportions, and isotopic exchange or fractionation processes within the lakes, as well as better estimates of the regional atmospheric deposition flux of perchlorate and the 36Cl abundance of bomb-pulse perchlorate.

Poghosyan, A.; Sturchio, N. C.; Jackson, W. A.; Guan, Y.; Eiler, J. M.; Hatzinger, P. B.

2013-12-01

146

Characterization of Cyanobacterial Hydrocarbon Composition and Distribution of Biosynthetic Pathways  

PubMed Central

Cyanobacteria possess the unique capacity to naturally produce hydrocarbons from fatty acids. Hydrocarbon compositions of thirty-two strains of cyanobacteria were characterized to reveal novel structural features and insights into hydrocarbon biosynthesis in cyanobacteria. This investigation revealed new double bond (2- and 3-heptadecene) and methyl group positions (3-, 4- and 5-methylheptadecane) for a variety of strains. Additionally, results from this study and literature reports indicate that hydrocarbon production is a universal phenomenon in cyanobacteria. All cyanobacteria possess the capacity to produce hydrocarbons from fatty acids yet not all accomplish this through the same metabolic pathway. One pathway comprises a two-step conversion of fatty acids first to fatty aldehydes and then alkanes that involves a fatty acyl ACP reductase (FAAR) and aldehyde deformylating oxygenase (ADO). The second involves a polyketide synthase (PKS) pathway that first elongates the acyl chain followed by decarboxylation to produce a terminal alkene (olefin synthase, OLS). Sixty-one strains possessing the FAAR/ADO pathway and twelve strains possessing the OLS pathway were newly identified through bioinformatic analyses. Strains possessing the OLS pathway formed a cohesive phylogenetic clade with the exception of three Moorea strains and Leptolyngbya sp. PCC 6406 which may have acquired the OLS pathway via horizontal gene transfer. Hydrocarbon pathways were identified in one-hundred-forty-two strains of cyanobacteria over a broad phylogenetic range and there were no instances where both the FAAR/ADO and the OLS pathways were found together in the same genome, suggesting an unknown selective pressure maintains one or the other pathway, but not both. PMID:24475038

Coates, R. Cameron; Podell, Sheila; Korobeynikov, Anton; Lapidus, Alla; Pevzner, Pavel; Sherman, David H.; Allen, Eric E.; Gerwick, Lena; Gerwick, William H.

2014-01-01

147

Characterization of cyanobacterial hydrocarbon composition and distribution of biosynthetic pathways.  

PubMed

Cyanobacteria possess the unique capacity to naturally produce hydrocarbons from fatty acids. Hydrocarbon compositions of thirty-two strains of cyanobacteria were characterized to reveal novel structural features and insights into hydrocarbon biosynthesis in cyanobacteria. This investigation revealed new double bond (2- and 3-heptadecene) and methyl group positions (3-, 4- and 5-methylheptadecane) for a variety of strains. Additionally, results from this study and literature reports indicate that hydrocarbon production is a universal phenomenon in cyanobacteria. All cyanobacteria possess the capacity to produce hydrocarbons from fatty acids yet not all accomplish this through the same metabolic pathway. One pathway comprises a two-step conversion of fatty acids first to fatty aldehydes and then alkanes that involves a fatty acyl ACP reductase (FAAR) and aldehyde deformylating oxygenase (ADO). The second involves a polyketide synthase (PKS) pathway that first elongates the acyl chain followed by decarboxylation to produce a terminal alkene (olefin synthase, OLS). Sixty-one strains possessing the FAAR/ADO pathway and twelve strains possessing the OLS pathway were newly identified through bioinformatic analyses. Strains possessing the OLS pathway formed a cohesive phylogenetic clade with the exception of three Moorea strains and Leptolyngbya sp. PCC 6406 which may have acquired the OLS pathway via horizontal gene transfer. Hydrocarbon pathways were identified in one-hundred-forty-two strains of cyanobacteria over a broad phylogenetic range and there were no instances where both the FAAR/ADO and the OLS pathways were found together in the same genome, suggesting an unknown selective pressure maintains one or the other pathway, but not both. PMID:24475038

Coates, R Cameron; Podell, Sheila; Korobeynikov, Anton; Lapidus, Alla; Pevzner, Pavel; Sherman, David H; Allen, Eric E; Gerwick, Lena; Gerwick, William H

2014-01-01

148

Application of a Fiber Optic Distributed Strain Sensor System to Woven E-Glass Composite  

NASA Technical Reports Server (NTRS)

A distributed strain sensing system utilizing a series of identically written Bragg gratings along an optical fiber is examined for potential application to Composite Armored Vehicle health monitoring. A vacuum assisted resin transfer molding process was used to fabricate a woven fabric E-glass/composite panel with an embedded fiber optic strain sensor. Test samples machined from the panel were mechanically tested in 4-point bending. Experimental results are presented that show the mechanical strain from foil strain gages comparing well to optical strain from the embedded sensors. Also, it was found that the distributed strain along the sample length was consistent with the loading configuration.

Anastasi, Robert F.; Lopatin, Craig

2001-01-01

149

Distribution of motor impairment influences quality of life in Parkinson's disease.  

PubMed

We evaluated the relationship between upper extremity (UE) and lower extremity (LE) motor impairments in Parkinson's disease (PD) to overall disability and quality of life (QoL) measures. A total of 639 patients who were diagnosed with idiopathic PD were administered the Unified Parkinson's Disease Rating Scale (UPDRS), QoL, activities of daily living (ADL), and behavioral scales. Composite UE and LE scores from the motor section of the UPDRS were correlated with ADL, QoL, and behavioral measurement scores while controlling for disease duration. Patients with greater UE and LE motor impairments had lower QoL scores. However, LE impairments had a greater influence than UE impairments across all QoL measures. PMID:18546324

Stewart, Kim C; Fernandez, Hubert H; Okun, Michael S; Jacobson, Charles E; Hass, Chris J

2008-07-30

150

Orderly Packed Anodes for High-Power Lithium-Ion Batteries with Super-Long Cycle Life: Rational Design of MnCO3 /Large-Area Graphene Composites.  

PubMed

MnCO3 particles uniformly distributed on large-area graphene form 2D composites whose large-area character enables them to self-assemble face-to-face into orderly packed electrodes. Such regular structures form continuous and efficient transport networks, leading to outstanding lithium storage with high capacity, ultralong cycle life, and excellent rate capability - all characteristics that are required for high-power lithium-ion batteries. PMID:25523603

Zhong, Yiren; Yang, Mei; Zhou, Xianlong; Luo, Yuting; Wei, Jinping; Zhou, Zhen

2015-02-01

151

Viral distribution and life strategies in the Bach Dang Estuary, Vietnam.  

PubMed

Although the structure and dynamics of planktonic viruses in freshwater and seawater environments are relatively well documented, little is known about the occurrence and activity of these viruses in estuaries, especially in the tropics. Viral abundance, life strategies, and morphotype distribution were examined in the Bach Dang Estuary (Vietnam) during the dry season in 2009. The abundance of both viruses and their prokaryotic hosts decreased significantly from upstream to downstream, probably as the result of nutrient dilution and osmotic stress faced by the freshwater communities. The antibiotic mitomycin-C revealed that the fraction of lysogenic cells was substantially higher in the lower seawater part of the estuary (max 27.1%) than in the upper freshwater area where no inducible lysogens were observed. The question of whether there is a massive, continuous induction of marine lysogens caused by the mixing with freshwater is considered. Conversely, the production of lytic viruses declined as salinity increased, indicating a spatial succession of viral life strategies in this tropical estuary. Icosahedral tailless viruses with capsids smaller than 60 nm dominated the viral assemblage throughout the estuary (63.0% to 72.1% of the total viral counts), and their distribution was positively correlated with that of viral lytic production. Interestingly, the gamma-proteobacteria explained a significant portion of the variance in the <60 nm and 60 to 90 nm tailless viruses (92% and 80%, respectively), and in the Myoviridae (73%). Also, 60% of the variance of the tailless larger viruses (>90 nm) was explained by the beta-proteobacteria. Overall, these results support the view that the environment, through selection mechanisms, probably shapes the structure of the prokaryotic community. This might be in turn a source of selection for the virioplankton community via specific affiliation favoring particular morphotypes and life strategies. PMID:21390531

Bettarel, Yvan; Bouvier, Thierry; Agis, Martin; Bouvier, Corinne; Chu, Thuoc Van; Combe, Marine; Mari, Xavier; Nghiem, Minh Ngoc; Nguyen, Thuy Thanh; Pham, Thu The; Pringault, Olivier; Rochelle-Newall, Emma; Torréton, Jean-Pascal; Tran, Huy Quang

2011-07-01

152

Concept for Determining the Life of Ceramic Matrix Composites Using Nondestructive Characterization Techniques  

NASA Technical Reports Server (NTRS)

An idea is put forth for a nondestructive characterization (NDC) generated algorithm-N curve to replace a S-N curve. A scenario for NDC life determination has been proposed. There are many challenges for the NDC life determination and prediction, but it could yield a grand payoff. The justification for NDC life determination and prediction is documented.

Effinger, M.; Ellingson, B.; Spohnholtz, T.; Koenig, J.

2001-01-01

153

Size and composition distribution of fine particulate matter emitted from wood burning, meat charbroiling, and cigarettes  

SciTech Connect

A dilution source sampling system is augmented to measure the size-distributed chemical composition of fine particle emissions from air pollution sources. Measurements are made using a laser optical particle counter (OPC), a differential mobility analyzer/condensation nucleus counter (DMA/CNC) combination, and a pair of microorifice uniform deposit impactors (MOUDIs). The sources tested with this system include wood smoke (pine, oak, eucalyptus), meat charbroiling, and cigarettes. The particle mass distributions from all wood smoke sources have a single mode that peaks at approximately 0.1--0.2 {micro}m particle diameter. The smoke from meat charbroiling shows a major peak in the particle mass distribution at 0.1--0.2 {micro}m particle diameter, with some material present at larger particle sizes. Particle mass distributions from cigarettes peak between 0.3 and 0.4 {micro}m particle diameter. Chemical composition analysis reveals that particles emitted from the sources tested here are largely composed of organic compounds. Noticeable concentrations of elemental carbon are found in the particles emitted from wood burning. The size distributions of the trace species emissions from these sources also are presented, including data for Na, K, Ti, Fe, Br, Ru, Cl, Al, Zn, Ba, Sr, V, Mn, Sb, La, Ce, as well as sulfate, nitrate, and ammonium ion when present in statistically significant amounts. These data are intended for use with air quality models that seek to predict the size distribution of the chemical composition of atmospheric fine particles.

Kleeman, M.J.; Schauer, J.J.; Cass, G.R.

1999-10-15

154

Influence of weight-loss diets with different macronutrient compositions on health-related quality of life in obese youth  

Microsoft Academic Search

The aims of this study were to compare the effects of weight-loss diets of different macronutrient compositions on weight and health-related quality of life (HRQOL), and to examine the relationship between changes in HRQOL parameters and weight loss during weight-loss programs in obese adolescents.Seventy one adolescents (12–18 years, BMI>95th percentile) were randomly allocated to one of three 12-week diet regimens:

Michal Yackobovitch-Gavan; Nessia Nagelberg; Sharon Demol; Moshe Phillip; Shlomit Shalitin

2008-01-01

155

Distribution, composition, and transport of suspended particulate matter in the vicinity of Willapa submarine canyon, Washington  

Microsoft Academic Search

The distribution and composition of suspended particulate matter in the waters over Willapa submarine canyon and the adjacent continental slope off the coast of Wasington describe an apparently continuous botton nepheloid layer ranging in thickness from 160 to 530 m and composed of particles supplied primarily by the nearby Columbia River. Near-bottom particulate concentrations, estimated by continuous vertical profiles of

EDWARD T. BAKER

1976-01-01

156

Depth distribution of ammonia oxidation rates and ammonia-oxidizer community composition in the Sargasso Sea  

E-print Network

Depth distribution of ammonia oxidation rates and ammonia-oxidizer community composition University, Princeton, New Jersey Abstract Ammonia oxidation rates and ammonia-oxidizer community structure in December 2009. Ammonia oxidation rates, measured from trace additions of 15NHz 4 (12­18 nmol L21), ranged

Ward, Bess

157

Composition and On Demand Deployment of Distributed Brain Activity Analysis Application on Global Grids  

E-print Network

1 Composition and On Demand Deployment of Distributed Brain Activity Analysis Application on Global are brain science and high-energy physics. The analysis of brain activity data gathered from the MEG and analyze brain functions and requires access to large-scale computational resources. The potential platform

Abramson, David

158

Species composition, abundance, habitat requirements and regional distribution of terrestrial gastropods in Arctic Norway  

Microsoft Academic Search

The species composition, abundance and habitat distributions of the terrestrial gastropods at lat. 70° N in Finnmark county, northern Norway were studied. Within an area with bedrocks of sandstone there were few snail species and abundance was low. Calciumrich bogs and birch woods with a luxuriant undergrowth had a richer gastropod fauna both in number of species and abundance. The

J. Andersen; O. Halvorsen

1984-01-01

159

Investigating low frequency dielectric properties of a composite using the distribution of relaxation times technique  

SciTech Connect

The distribution of relaxation times approach, a less frequently employed dielectric data analysis technique, is utilized to better understand the relaxation characteristics of composites consisting of metal-coated, hollow glass spheres dispersed in a paraffin wax matrix. The dielectric properties of the composite samples are measured by means of impedance spectroscopy in the frequency range 0.1mHz to 10 MHz. The application of a mixture law is not appropriate for the analysis of the frequency-dependent properties of the considered system on this broad frequency range. However, utilization of the distribution of relaxation times procedure to study the dielectric behaviour shows clear trends in the mixtures' relaxation spectra. Relaxation processes of the paraffin wax and those specific to the composites are found from the extracted distribution of relaxation times spectra. The influence of the filler concentration, q, on the dielectric properties is examined; a relaxation with a narrow distribution at intermediate frequencies becomes broad with the addition of the filler. This relaxation, in the form of the low-frequency-dispersions (also known as constant phase angle) phenomenon, dominates the dielectric properties of the composites with high bead concentration, q > 0:15. The variation in dielectric properties of individual samples whose bead concentrations q are nominally the same is discussed in terms of possible microstructural variations.

Tuncer, Enis [ORNL

2006-01-01

160

Investigating low-frequency dielectric properties of a composite using the distribution of relaxation times technique  

SciTech Connect

The distribution of relaxation times approach, a less frequently employed dielectric data analysis technique, is utilized to better understand the relaxation characteristics of composites consisting of metal-coated, hollow glass spheres dispersed in a paraffin wax matrix. The dielectric properties of the composite samples are measured by means of impedance spectroscopy in the frequency range 0.1 mHz to 10 MHz. The application of a mixture law is not appropriate for the analysis of the frequency-dependent properties of the considered system on this broad frequency range. However, utilization of the distribution of relaxation times procedure to study the dielectric behaviour shows clear trends in the mixtures' relaxation spectra. Relaxation processes of the paraffin wax and those specific to the composites are found from the extracted distribution of relaxation times spectra. The influence of the filler concentration, q, on the dielectric properties is examined; a relaxation with a narrow distribution at intermediate frequencies becomes broad with the addition of the filler. This relaxation, in the form of the low-frequency-dispersions (also known as constant phase angle) phenomenon, dominates the dielectric properties of the composites with high bead concentration, q>0.15. The variation in dielectric properties of individual samples whose bead concentrations q are nominally the same is discussed in terms of possible microstructural variations.

Tuncer, Enis [ORNL; Bowler, Nicola [Center for Nondestructive Evaluation, Ames, Iowa; Youngs, I. J. [DSTL, Porton Down, Salisbury, Wiltshire, UK; Lymer, K. P. [QinetiQ Ltd, Hampshire, UK

2006-01-01

161

Fine root distribution and persistence under field conditions of three co-occurring Great Basin species of different life form  

Microsoft Academic Search

Summary • Fine roots of an annual grass, a perennial grass and a perennial shrub were examined. Based on life histories and tissue composition, we expected the greatest root persistence for the shrub and shortest for the annual grass. • Roots were observed with minirhizotrons over 2 yr for number, length and diameter changes. A Cox proportional hazard regression correlated

Michael S. Peek; A. Joshua Leffler; Carolyn Y. Ivans; Ronald J. Ryel; Martyn M. Caldwell

2004-01-01

162

Reliability and life prediction of ceramic composite structures at elevated temperatures  

NASA Astrophysics Data System (ADS)

Methods are highlighted that ascertain the structural reliability of components fabricated of composites with ceramic matrices reinforced with ceramic fibers or whiskers and subject to quasi-static load conditions at elevated temperatures. Each method focuses on a particular composite microstructure: whisker-toughened ceramics, laminated ceramic matrix composites, and fabric reinforced ceramic matrix composites. In addition, since elevated service temperatures usually involve time-dependent effects, a section dealing with reliability degradation as a function of load history has been included. A recurring theme throughout this chapter is that even though component failure is controlled by a sequence of many microfailure events, failure of ceramic composites will be modeled using macrovariables.

Duffy, Stephen F.; Gyekenyesi, John P.

1994-01-01

163

Controls on the distribution and isotopic composition of helium in deep ground-water flows  

USGS Publications Warehouse

The distribution and isotopic composition of helium in sedimentary basins can be used to interpret the ages of very old ground waters. The piston-flow model commonly used in such interpretation, how ever, does not account for several important factors and as such works well only in very simple flow regimes. In this study of helium transport in a hypothetical sedimentary basin, we develop a numerical model that accounts for the magnitude and distribution of the basal helium flux, hydrodynamic dispersion, and complexities in flow regimes such as subregional flow cells. The modeling shows that these factors exert strong controls on the helium distribution and isotopic composition. The simulations may provide a basis for more accurate interpretations of observed helium concentrations and isotopic ratios in sedimentary basins.

Zhao, X.; Fritzel, T.L.B.; Quinodoz, H.A.M.; Bethke, C.M.; Torgersen, T.

1998-01-01

164

Major elements composition, Li distribution and isotopic composition in peridotite xenoliths from Allegre and Mont Coupet (French Massif Central)  

NASA Astrophysics Data System (ADS)

The peridotite xenoliths from two localities (the Ringue quarry in Allegre; Mont Coupet) belong to the Massif Central southern domain, which have been accredited as a circumcratonic segment and been rejuvenated during the Variscan orogeny (Lenoir et al. 2000). The Ringue quarry is opened in a lava lake and, in contrast, Mont Coupet is a strombolian eruptive volcano. Major element compositions, Li distribution and isotope compositions in minerals from these xenoliths were measured to describe the evolution of the sub-continental lithospheric mantle, and to look for Li exchange during the melt-rock interaction. As for major element compositions, the samples from two localities fall into the off-craton field (Rudnick et al., 2004) and the compositional ranges of the southern domain of the French Massif Central (Downes et al., 2003). They have also been imprinted by mantle metasomatism, which engendered much higher Mg# of cpx (up to 93.5) relative to their co-existing olivines (89.2 to 91.5). In the Allegre samples, large variations between the equilibration temperatures of mineral cores and rims indicate disequilibrium resulting from mantle metasomatism. Cpx display enriched Li contents (up to 24 ppm) and Li partitioning between cpx and olivine/opx strongly deviates from the equilibrated trend (Seitz and Woodland, 2000), suggestive of their interaction with mafic silicate melts and/or fluids with high Li contents. The highly negative ?7Li values (down to -25o ) compared to the primary mantle value of 4±2o (Rudnick and Ionov, 2007) and the large inter-mineral Li isotope fractionations attest for Li exchange with melts and/or fluids during metasomatic events. Mont Coupet samples display equilibrated Li distribution and isotopic composition at the thin section scale, but an inverse relationship between the Li contents and Li isotope compositions between the different samples, indicating a large-scale Li diffusion process, occurring before the xenoliths exhumation. In conclusion, the different types of host magmas should be a significant factor that leads to these extremely diverse characteristics of Li distribution and isotope compositions in the samples from Allegre and Mont Coupet. In the lava lake, host magmas have kept relatively long-term high temperatures and this provided time for Li to diffuse from infiltrated metasomatic melts or host magmas. On the contrary, Mont Coupet has cooled rapidly and the xenoliths could preserve the geochemical state of Li in the mantle depth. Lenoir et al, 2000, Earth Planet. Sci. Lett. 181, 359- 375. Rudnick et al., 2004, Lithos 77, 609-637. Downes et al., 2003, Chem. Geol. 200, 71-87. Seitz and Woodland, 2000, Chem. Geol. 166, 47-64. Rudnick and Ionov, 2007, Earth Planet. Sci. Lett. 256, 278-293.

Xiaoyan, Gu; Etienne, Deloule; Lyderic, France; Jannick, Ingrin

2014-05-01

165

Habitat and distribution of post-recruit life stages of the squid Loligo forbesii  

NASA Astrophysics Data System (ADS)

This study models habitat preferences of the squid Loligo forbesii through its post-recruitment life cycle in waters around Scotland (UK). Trawl survey and market sample data from 1985 to 2004 are used to model seasonal habitats of immature, maturing and mature squid (maturity being inferred from size and season). Squid presence-absence and catch rate in areas of presence were analysed using generalised additive models, relating spatiotemporal patterns of distribution and abundance to ecogeographic variables. For all maturity classes, higher abundance in winter and spring (i.e., quarters 1 and 2) was associated with deeper water while higher abundance in summer and autumn (quarters 3 and 4) was associated with shallower water, consistent with seasonal onshore-offshore migrations but suggesting that most spawning may take place in deeper waters. The preferred SST range was generally 8-8.75 °C while preferred salinity values were below 35‰ in winter and summer and above 35‰ in spring and autumn. Squid were positively associated with gravel substrate and negatively associated with mud. Seasonal changes in habitat use were more clearly evident than changes related to inferred maturity, although the two effects cannot be fully separated due to the annual life cycle. Habitat selection for this species can be satisfactorily modelled on a seasonal basis; predictions based on such models could be useful for fishers to target the species more effectively, and could assist managers wishing to protect spawning grounds. The extent to which this approach may be useful for other cephalopods is discussed.

Smith, Jennifer M.; Macleod, Colin D.; Valavanis, Vasilis; Hastie, Lee; Valinassab, Tooraj; Bailey, Nick; Santos, M. Begoña; Pierce, Graham J.

2013-10-01

166

Frequency Distributions of Geochemical Data, Scaling Laws, and Properties of Compositions  

NASA Astrophysics Data System (ADS)

Many random processes occur in geochemistry. Accurate predictions of the manner in which elements or chemical species interact with each other are needed to construct models able to treat the presence of random components. Although modelling of frequency distributions with some probabilistic models (for example Gaussian, log-normal, Pareto) has been well discussed in several fields of application, little attention has been devoted to the features of compositional data and, in particular, to their multivariate nature. In this contribution an approach coherent with the properties of compositional information is proposed and used to investigate the shape of the frequency distribution of geochemical indices obtained by robust multivariate analysis. The purpose is to understand data-generation processes from the perspective of compositional theory. The approach is based on use of transformations of the log-ratio family, each with peculiar theoretical and practical advantages, depending on the statistical methods adopted. Accordingly, because, in compositional data, all the relevant information about one term (x i ) of a D-part composition is contained in the ratios to each of the remaining parts x 2,…, x D , analysis of single variables is abandoned. The proposed methodology directs attention to modelling of the frequency distribution of more complex indices, linking all the terms of the composition to better represent the dynamics of geochemical processes. An example of its application is presented and discussed on the basis of consideration of the chemistry of 616 ocean floor basaltic (OFB) glasses from the abyssal volcanic glass data file (AVGDF) of the Smithsonian Institution.

Buccianti, Antonella

2014-11-01

167

Groundwater age, life expectancy and transit time distributions in advective-dispersive systems: 1. Generalized reservoir theory  

E-print Network

We present a methodology for determining reservoir groundwater age and transit time probability distributions in a deterministic manner, considering advective-dispersive transport in steady velocity fields. In a first step, we propose to model the statistical distribution of groundwater age at aquifer scale by means of the classical advection-dispersion equation for a conservative and nonreactive tracer, associated to proper boundary conditions. The evaluated function corresponds to the density of probability of the random variable age, age being defined as the time elapsed since the water particles entered the aquifer. An adjoint backward model is introduced to characterize the life expectancy distribution, life expectancy being the time remaining before leaving the aquifer. By convolution of these two distributions, groundwater transit time distributions, from inlet to outlet, are fully defined for the entire aquifer domain. In a second step, an accurate and efficient method is introduced to simulate the tr...

Cornaton, F; 10.1016/j.advwatres.2005.10.009

2011-01-01

168

A model for predicting the damage and oxidation dependent life of SCS-6/Ti-B21S [0]4 metal matrix composite  

E-print Network

A method for predicting the life of an embrittled metal matrix composite using the finite element method coupled with models for material inelasticity, surface embrittlement, and crack propagation was developed herein. The titanium metal matrix...

Foulk, James Wesley

2012-06-07

169

Determing Lamprey Species Composition, Larval Distribution, and Adult Abundance in the Deschutes River, Oregon, Subbasin; 2001-2002 Annual Report.  

SciTech Connect

Information about lamprey species composition, distribution, life history, abundance, habitat requirements and exploitation in lower Deschutes River tributaries is extremely limited. To assess the status of lampreys in the Deschutes River subbasin, baseline information is needed. We operated to rotary screw traps in the Warm Springs River and Shitike Creek to gain an understanding of species composition, migration time and production. We identified Pacific lampreys in two life stages, ammocoete and macropthalmia. It appears that Pacific lamprey macropthalmia out-migrate during winter in the Warm Springs River. We saw peak movements by ammocoetes in the spring in Shitike Creek and winter in the Warm Springs River. We found no relationship between stream discharge and the number of lamprey collected. Very few macropthalmia were collected in Shitike Creek. Ammocoete size in the Warm Springs River and Shitike Creek were different. The ammocoetes in the Shitike Creek trap were close in size to the macropthalmia collected in the Warm Springs River trap. We also completed planning and preparation for larval and associated habitat data collection. This preparation included purchasing necessary field equipment, selecting and marking sampling areas and attending training with US Fish and Wildlife Service (USFWS) and the Confederated Tribes of Umatilla Indian Reservation (CTUIR). Because lamprey identification is difficult we met with US Geological Survey (USGS) to assist us with larval lamprey identification techniques. We have also been working in coordination with the Oregon Department of Fish and Wildlife (ODFW) to prepare and implement creel surveys and a mark-recapture study at Sherar's Falls to estimate adult lamprey escapement.

Graham, Jennifer C.; Brun, Christopher V. (Confederated Tribes of the Warm Springs Reservation of Oregon, Department of Natural Resources)

2003-05-01

170

Visceral Adipocyte Hypertrophy is Associated With Dyslipidemia Independent of Body Composition and Fat Distribution in Women  

PubMed Central

OBJECTIVE We assessed whether subcutaneous and omental adipocyte hypertrophy are related to metabolic alterations independent of body composition and fat distribution in women. RESEARCH DESIGN AND METHODS Mean adipocyte diameter of paired subcutaneous and omental adipose tissue samples was obtained in lean to obese women. Linear regression models predicting adipocyte size in both adipose tissue depots were computed using body composition and fat distribution measures (n = 150). In a given depot, women with larger adipocytes than predicted by the regression were considered as having adipocyte hypertrophy, whereas women with smaller adipocytes than predicted were considered as having adipocyte hyperplasia. RESULTS Women characterized by omental adipocyte hypertrophy had higher plasma and VLDL triglyceride levels as well as a higher total-to-HDL cholesterol ratio compared with women characterized by omental adipocyte hyperplasia (P < 0.05). Conversely, women characterized by subcutaneous adipocyte hypertrophy or hyperplasia showed a similar lipid profile. In logistic regression analyses, a 10% enlargement of omental adipocytes increased the risk of hypertriglyceridemia (adjusted odds ratio [OR] 4.06, P < 0.001) independent of body composition and fat distribution measures. A 10% increase in visceral adipocyte number also raised the risk of hypertriglyceridemia (adjusted OR 1.55, P < 0.02). Associations between adipocyte size and homeostasis model assessment of insulin resistance were not significant once adjusted for adiposity and body fat distribution. CONCLUSIONS These results suggest that omental, but not subcutaneous, adipocyte hypertrophy is associated with an altered lipid profile independent of body composition and fat distribution in women. PMID:21421806

Veilleux, Alain; Caron-Jobin, Maude; Noël, Suzanne; Laberge, Philippe Y.; Tchernof, André

2011-01-01

171

Recycling and reuse of waste from electricity distribution networks as reinforcement agents in polymeric composites.  

PubMed

Of the waste generated from electricity distribution networks, wooden posts treated with chromated copper arsenate (CCA) and ceramic insulators make up the majority of the materials for which no effective recycling scheme has been developed. This study aims to recycle and reuse this waste as reinforcement elements in polymer composites and hybrid composites, promoting an ecologically and economically viable alternative for the disposal of this waste. The CCA wooden posts were cut, crushed and recycled via acid leaching using 0.2 and 0.4N H2SO4 in triplicate at 70°C and then washed and dried. The ceramic insulators were fragmented in a hydraulic press and separated by particle size using a vibrating sieve. The composites were mixed in a twin-screw extruder and injected into the test specimens, which were subjected to physical, mechanical, thermal and morphological characterization. The results indicate that the acid treatment most effective for removing heavy metals in the wood utilizes 0.4NH2SO4. However, the composites made from wood treated with 0.2NH2SO4 exhibited the highest mechanical properties of the composites, whereas the use of a ceramic insulator produces composites with better thermal stability and impact strength. This study is part of the research and development project of ANEEL (Agência Nacional de Energia Elétrica) and funded by CPFL (Companhia Paulista de Força e Luz). PMID:23663959

Zimmermann, Matheus V G; Zattera, Ademir J

2013-07-01

172

Electrical Resistance of SiC/SiC Ceramic Matrix Composites for Damage Detection and Life-Prediction  

NASA Technical Reports Server (NTRS)

Ceramic matrix composites (CMC) are suitable for high temperature structural applications such as turbine airfoils and hypersonic thermal protection systems due to their low density high thermal conductivity. The employment of these materials in such applications is limited by the ability to accurately monitor and predict damage evolution. Current nondestructive methods such as ultrasound, x-ray, and thermal imaging are limited in their ability to quantify small scale, transverse, in-plane, matrix cracks developed over long-time creep and fatigue conditions. CMC is a multifunctional material in which the damage is coupled with the material s electrical resistance, providing the possibility of real-time information about the damage state through monitoring of resistance. Here, resistance measurement of SiC/SiC composites under mechanical load at both room temperature monotonic and high temperature creep conditions, coupled with a modal acoustic emission technique, can relate the effects of temperature, strain, matrix cracks, fiber breaks, and oxidation to the change in electrical resistance. A multiscale model can in turn be developed for life prediction of in-service composites, based on electrical resistance methods. Results of tensile mechanical testing of SiC/SiC composites at room and high temperatures will be discussed. Data relating electrical resistivity to composite constituent content, fiber architecture, temperature, matrix crack formation, and oxidation will be explained, along with progress in modeling such properties.

Smith, Craig; Morscher, Gregory; Xia, Zhenhai

2009-01-01

173

A normalization method for life-time prediction of composite materials  

E-print Network

Introduction Industrials are increasingly using more composite materi- als in various fields particularly in aviation and automobiles fields. Their great advantage is their strength and stiffness associated are given. 2 Materials and test 2.1 Materials The studied materials were manufactured by moulding composite

Paris-Sud XI, Université de

174

Chemosymbiotic species from the Gulf of Cadiz (NE Atlantic): distribution, life styles and nutritional patterns  

NASA Astrophysics Data System (ADS)

Previous work in the mud volcanoes from the Gulf of Cadiz (South Iberian Margin) revealed a high number of chemosymbiotic species, namely bivalves and siboglinid polychaetes. In this study we give an overview of the distribution and life styles of these species in the Gulf of Cadiz, determine the role of autotrophic symbionts in the nutrition of selected species using stable isotope analyses (?13C, ?15N and ?34S) and investigate the intra-specific variation of isotope signatures within and between study sites. During our studies, we identified twenty siboglinidae and nine bivalve chemosymbiotic species living in fifteen mud volcanoes. Solemyid bivalves and tubeworms of the genus Siboglinum are widespread in the study area, whereas other species were found in a single mud volcano (e.g. "Bathymodiolus" mauritanicus) or restricted to deeper mud volcanoes (e.g. Polybrachia sp., Lamelisabella denticulata). Species distribution suggests that different species may adjust their position within the sediment according to their particular needs, and to the intensity and variability of the chemical substrata supply. Tissue stable isotope signatures for selected species are in accordance with values found in other studies, with thiotrophy as the dominant nutritional pathway, and with methanotrophy and mixotrophy emerging as secondary strategies. The heterogeneity in terms of nutrient sources (expressed in the high variance of nitrogen and sulphur values) and the ability to exploit different resources by the different species may explain the high diversity of chemosymbiotic species found in the Gulf of Cadiz. This study increases the knowledge on distributional patterns and resource partitioning of chemosymbiotic species and highlights how trophic fuelling varies on spatial scales with direct implications to seep assemblages and potentially to the biodiversity of continental margin.

Rodrigues, C. F.; Hilário, A.; Cunha, M. R.

2013-04-01

175

The influence of particle distribution on the mechanical response of a particulate metal matrix composite  

SciTech Connect

A self-consistent model, based on Eshelby's equivalent inclusion method, has been developed to predict to flow of a particulate-reinforced alloy. The model gives excellent agreement with the measured elastic moduli for Al/SiC composites. Beyond the elastic limit, the model predicts an increase in the initial work hardening rate with increasing particle content. At large strains (above about 1%) the stress-strain behavior of the composite is parallel to that of the unreinforced alloy. The results agree well with those obtained by Bao et al. using finite element methods, indicating that solutions based on average stress fields around particles do capture the essential features of composite strengthening. However, the current treatment can be readily extended to treat the effect of an inhomogeneous particle distribution on strength. As the degree of particle clustering increases, an increase in the rate of initial work hardening is predicted. Moreover, the strengthening ratio is increased substantially by clustering.

Corbin, S.F.; Wilkinson, D.S. (McMaster Univ., Hamilton, Ontario (Canada). Dept. of Materials Science and Engineering)

1994-04-01

176

Life Prediction Issues in Thermal/Environmental Barrier Coatings in Ceramic Matrix Composites  

NASA Technical Reports Server (NTRS)

Issues and design requirements for the environmental barrier coating (EBC)/thermal barrier coating (TBC) life that are general and those specific to the NASA Ultra-Efficient Engine Technology (UEET) development program have been described. The current state and trend of the research, methods in vogue related to the failure analysis, and long-term behavior and life prediction of EBCITBC systems are reported. Also, the perceived failure mechanisms, variables, and related uncertainties governing the EBCITBC system life are summarized. A combined heat transfer and structural analysis approach based on the oxidation kinetics using the Arrhenius theory is proposed to develop a life prediction model for the EBC/TBC systems. Stochastic process-based reliability approach that includes the physical variables such as gas pressure, temperature, velocity, moisture content, crack density, oxygen content, etc., is suggested. Benefits of the reliability-based approach are also discussed in the report.

Shah, Ashwin R.; Brewer, David N.; Murthy, Pappu L. N.

2001-01-01

177

Size and composition distribution of fine particulate matter emitted from wood burning, meat charbroiling, and cigarettes  

Microsoft Academic Search

A dilution source sampling system is augmented to measure the size-distributed chemical composition of fine particle emissions from air pollution sources. Measurements are made using a laser optical particle counter (OPC), a differential mobility analyzer\\/condensation nucleus counter (DMA\\/CNC) combination, and a pair of microorifice uniform deposit impactors (MOUDIs). The sources tested with this system include wood smoke (pine, oak, eucalyptus),

Michael J. Kleeman; James J. Schauer; Glen R. Cass

1999-01-01

178

Chemical composition distribution analysis of photoresist copolymers and influence on ArF lithographic performance  

Microsoft Academic Search

For getting information about the distribution of chemical composition, several model polymers were prepared under different polymerization conditions and were measured by critical adsorption point-liquid chromatography (CAP-LC). In the copolymer system of 8- and 9- (4-oxatricyclo[5.2.1.02,6]decane-3-one) acrylate (OTDA) and 2-ethyl-2-adamantyl methacrylate (EAdMA), the peak shapes of the CAP-LC chromatogram varied according to the polymerization condition although they indicated same molecular

Hikaru Momose; Atsushi Yasuda; Akifumi Ueda; Takayuki Iseki; Koichi Ute; Takashi Nishimura; Ryo Nakagawa; Tatsuki Kitayama

2007-01-01

179

Relationship between Defect Size and Fatigue Life Distributions in Al-7 Pct Si-Mg Alloy Castings  

NASA Astrophysics Data System (ADS)

A new method for predicting the variability in fatigue life of castings was developed by combining the size distribution for the fatigue-initiating defects and a fatigue life model based on the Paris-Erdo?an law for crack propagation. Two datasets for the fatigue-initiating defects in Al-7 pct Si-Mg alloy castings, reported previously in the literature, were used to demonstrate that (1) the size of fatigue-initiating defects follow the Gumbel distribution; (2) the crack propagation model developed previously provides respectable fits to experimental data; and (3) the method developed in the present study expresses the variability in both datasets, almost as well as the lognormal distribution and better than the Weibull distribution.

Tiryakio?lu, Murat

2009-07-01

180

USE OF A NOVEL PEDIATRIC BODY COMPOSITION TECHNIQUE FOR ASSESSING BODY FATNESS AND ITS CHANGES DURING THE FIRST 6 MONTHS OF LIFE  

Technology Transfer Automated Retrieval System (TEKTRAN)

Clinical assessment of infant growth and nutritional status is enhanced by accurate measurement of body composition and its changes over time. OBJECTIVE: To evaluate the accuracy of an air-displacement plethysmograph, the PEA POD® Infant Body Composition System (Life Measurement, Inc., Concord, CA)...

181

Body composition of infants fed breast-milk, milk-based formula or soy-based formula during the first 6 months of life  

Technology Transfer Automated Retrieval System (TEKTRAN)

Literature on the impact of infant feeding on body composition is sparse and inconclusive. We assessed body composition in infants exclusively fed breast-milk (BF), milk-based formula (MF) or soy-based formula (SF) for at least the first 4 months of life. Participants are part of the on-going prosp...

182

Development of a fatigue-life methodology for composite structures subjected to out-of-plane load components  

NASA Technical Reports Server (NTRS)

The efforts to identify and implement a fatigue life methodology applicable to demonstrate delamination failures for use in certifying composite rotor blades are presented. The RSRA/X-Wing vehicle was a proof-of-concept stopped rotor aircraft configuration which used rotor blades primarily constructed of laminated carbon fiber. Delamination of the main spar during ground testing demonstrated that significant interlaminar stresses were produced. Analysis confirmed the presence of out-of-plane load components. The wear out (residual strength) methodology and the requirements for its implementation are discussed.

Sumich, Mark; Kedward, Keith T.

1991-01-01

183

The effect of shape distribution of inclusions on the frequency dependence of permeability in composites  

NASA Astrophysics Data System (ADS)

Microwave material parameters of composites filled with Fe powder are measured as a function of frequency and volume fraction of the powder. The powder is prepared by mechanical milling of Fe in argon atmosphere. The host matrix of the composites is paraffin wax. The permittivity and permeability are measured in the frequency range 0.01-3 GHz. The measured frequency dependences of the permeability is considered in terms of the Bergman-Milton theory, with no additional suggestions imposed on the volume fraction dependence of effective material parameters of composites and the frequency dependence of intrinsic permeability of magnetic powders. The Ghosh-Fuchs theory is found to provide an excellent agreement with the measured permittivity and permeability of the composites, in contrast to the theories employing averaged demagnetization factor of inclusions, such as the Maxwell Garnet approximation. Therefore, the effective material parameters of the composites are affected greatly by the shape distribution of the powder particles. From the measured frequency dependence of permittivity and permeability, the intrinsic permeability of the powder is found.

Rozanov, K. N.; Osipov, A. V.; Petrov, D. A.; Starostenko, S. N.; Yelsukov, E. P.

2009-04-01

184

Roles of maternal effects and nuclear genetic composition change across the life cycle of crop-wild hybrids.  

PubMed

• Premise of the study: The fitness of an offspring may depend on its nuclear genetic composition (via both parental genotypes) as well as on genetic maternal effects (via only the maternal parent). Understanding the relative importance of these two genetic factors is particularly important for research on crop-wild hybridization, since traits with important genetic maternal effects (e.g., seed size) often differ among crops and their relatives. We hypothesized that the effects of these genetic factors on fitness components would change across the life cycle of hybrids.• Methods: We followed seed, plant size, and reproductive traits in field experiments with wild and four crop-wild hybrids of sunflower (Helianthus annuus), which differed in nuclear genetic composition and maternal parent (wild or F1 hybrid).• Key results: We identified strong genetic maternal effects for early life cycle characteristics, with seeds produced on an F1 mother having premature germination, negligible seed dormancy, and greater seedling size. Increased percentages of crop alleles also increased premature germination and reduced dormancy in seeds produced on a wild mother. For mature plants, nuclear genetic composition dominated: greater percentages of crop alleles reduced height, branching, and fecundity.• Conclusions: Particular backcrosses between hybrids and wilds may differentially facilitate movement of crop alleles into wild populations due to their specific features. For example, backcross seeds produced on wild mothers can persist in the seed bank, illustrating the importance of genetic maternal effects, whereas backcross individuals with either wild or F1 mothers have high fecundity, resulting from their wild-like nuclear genetic composition. PMID:25016007

Alexander, Helen M; Emry, D Jason; Pace, Brian A; Kost, Matthew A; Sparks, Kathryn A; Mercer, Kristin L

2014-07-11

185

Molecular Structures of Polymer/Sulfur Composites for Lithium-Sulfur Batteries with Long Cycle Life  

SciTech Connect

Vulcanizedpolyaniline/sulfur (SPANI/S) nanostructures were investigated for Li-S battery applications, but the detailed molecular structures of such composites have not been fully illustrated. In this paper, we synthesize SPANI/S composites with different S content in a nanorod configuration. FTIR, Raman, XPS, XRD, SEM and elemental analysis methods are used to characterize the molecular structure of the materials. We provide clear evidence that a portion of S was grafted on PANI during heating and connected the PANI chains with disulfide bonds to form a crosslinked network and the rest of S was encapsulated within it.. Polysulfides and elementary sulfur nanoparticles are physically trapped inside the polymer network and are not chemically bound to the polymer. The performance of the composites is further improved by reducing the particle size. Even after 500 cycles a capacity retention rate of 68.8% is observed in the SPANI/S composite with 55% S content.

Xiao, Lifen; Cao, Yuliang; Xiao, Jie; Schwenzer, Birgit; Engelhard, Mark H.; Saraf, Laxmikant V.; Nie, Zimin; Exarhos, Gregory J.; Liu, Jun

2013-04-26

186

Local Abundance Patterns of Noctuid Moths in Olive Orchards: Life-History Traits, Distribution Type and Habitat Interactions  

PubMed Central

Local species abundance is related to range size, habitat characteristics, distribution type, body size, and life-history variables. In general, habitat generalists and polyphagous species are more abundant in broad geographical areas. Underlying this, local abundance may be explained from the interactions between life-history traits, chorological pattern, and the local habitat characteristics. The relationship within taxa between life-history traits, distribution area, habitat characteristics, and local abundance of the noctuid moth (Lepidoptera: Noctuidae) assemblage in an olive orchard, one of the most important agro-ecosystems in the Mediterranean basin, was analyzed. A total of 66 species were detected over three years of year-round weekly samplings using the light-trap method. The life-history traits examined and the distribution type were found to be related to the habitat-species association, but none of the biological strategies defined from the association to the different habitats were linked with abundance. In contrast to general patterns, dispersal ability and number of generations per year explained differences in abundance. The relationships were positive, with opportunistic taxa that have high mobility and several generations being locally more abundant. In addition, when the effect of migrant species was removed, the distribution type explained abundance differences, with Mediterranean taxa (whose baricenter is closer to the studied area) being more abundant. PMID:21529251

Pérez-Guerrero, Sergio; Redondo, Alberto José; Yela, José Luis

2011-01-01

187

Astrobiology: The Study of the Origin, Evolution, and Distribution of Life in the Universe  

ERIC Educational Resources Information Center

Life as people know it here on Earth exchanges energy and materials with the environment. Life forms grow, develop, produce waste products, and reproduce, storing genetic information in DNA and RNA and passing it from one generation to the next. Life evolves, adapting to changes in the environment and changing the environment in return. The basic…

Scalice, Daniella; Wilmoth, Krisstina

2004-01-01

188

Astrobiology: The Study of the Origin, Evolution, and Distribution of the Life in the Universe  

ERIC Educational Resources Information Center

Life as known here on Earth exchanges energy and materials with the environment. Life forms grow, develop, produce waste products, and reproduce, storing genetic information in DNA and RNA and passing it from one generation to the next. Life evolves, adapting to changes in the environment and changing the environment in return. The basic unit of…

Scalice, Daniella; Wilmoth, Krisstina

2004-01-01

189

Somatic Maintenance Resources in the Honeybee Worker Fat Body Are Distributed to Withstand the Most Life-Threatening Challenges at Each Life Stage  

PubMed Central

In a global transcriptome analysis of three natural and three manipulated honeybee worker phenotypes at different ages, we have investigated the distribution of investment in somatic maintenance of the fat body. Gene expression is modulated so that the bees are able to resist the most life-threatening challenges at the actual life stage. Different modes of maintenance and repair are regulated, apparently to meet the environmental challenges most detrimental to survival and reproductive potential for the hive. We observed a broad down-regulation of genomic and cellular maintenance in the short-lived foragers and nurse bees compared to the long-lived winter bees. Our results show that survival and reproduction of the entire hive is given priority over the individual bees, hence supporting the idea of the honeybee society as a superorganism. Our results also fit the disposable soma theory of aging. PMID:23940531

Seehuus, Siri-Christine; Taylor, Simon; Petersen, Kjell; Aamodt, Randi M.

2013-01-01

190

A Model to Predict Shelf-Life Loss Ofhorticultural Produce During Distribution Withfluctuated Temperature and Vehicle Vibration  

NASA Astrophysics Data System (ADS)

Fresh fruits and vegetables has become a public concern from the food security aspect. And the prediction of shelf-life loss under the fluctuated temperature becomes one of the key problems in food supply chain operation. So this paper identifies the impact aspects of produce decaying during distribution. For the key temperature factor, the process is divided into three phases: sorting, traveling and door-opening. Based on time-temperature function, a model of shelf-life loss of horticultural produce during distribution is developed by evaluating respiration rate of vegetables and fruits considering both the environment fluctuated temperature and vehicle vibration during traveling. Taking eggplant as an example, the numerical experiment result demonstrates that the average cost for ambient distribution is 2.8 times of the insulation way.

Gong, Weiwei; Li, Daoliang; Liu, Xue; Yue, Jun; Fu, Zetian

191

On the limit theorem for life time distribution connected with some reliability systems and their validation by means of the Monte Carlo method  

NASA Astrophysics Data System (ADS)

We prove the limit theorem for life time distribution connected with reliability systems when their life time is a Pascal Convolution of independent and identically distributed random variables. We show that, in some conditions, such distributions may be approximated by means of Erlang distributions. As a consequnce, survival functions for such systems may be, respectively, approximated by Erlang survival functions. By using Monte Carlo method we experimantally confirm the theoretical results of our theorem.

Gheorghe, Munteanu Bogdan; Alexei, Leahu; Sergiu, Cataranciuc

2013-09-01

192

Transverse Tension Fatigue Life Characterization Through Flexure Testing of Composite Materials  

NASA Technical Reports Server (NTRS)

The transverse tension fatigue life of S2/8552 glass-epoxy and IM7/8552 carbon-epoxy was characterized using flexure tests of 90-degree laminates loaded in 3-point and 4-point bending. The influence of specimen polishing and specimen configuration on transverse tension fatigue life was examined using the glass-epoxy laminates. Results showed that 90-degree bend specimens with polished machined edges and polished tension-side surfaces, where bending failures where observed, had lower fatigue lives than unpolished specimens when cyclically loaded at equal stress levels. The influence of specimen thickness and the utility of a Weibull scaling law was examined using the carbon-epoxy laminates. The influence of test frequency on fatigue results was also documented for the 4-point bending configuration. A Weibull scaling law was used to predict the 4-point bending fatigue lives from the 3-point bending curve fit and vice-versa. Scaling was performed based on maximum cyclic stress level as well as fatigue life. The scaling laws based on stress level shifted the curve fit S-N characterizations in the desired direction, however, the magnitude of the shift was not adequate to accurately predict the fatigue lives. Furthermore, the scaling law based on fatigue life shifted the curve fit S-N characterizations in the opposite direction from measured values. Therefore, these scaling laws were not adequate for obtaining accurate predictions of the transverse tension fatigue lives.

OBrien, T. Kevin; Chawan, Arun D.; Krueger, Ronald; Paris, Isabelle

2001-01-01

193

A requirement for reduced pressure and modified atmosphere composition in lunar and martian biological life support systems  

NASA Astrophysics Data System (ADS)

The Controlled Environment Systems Research Facility at the PlaceTypeUniversity of Place- NameGuelph (country-regionplaceCanada) represents an extensive collection of variable pressure plant growth chambers devoted to the study of biological systems including plants and microbes, in life support roles for space exploration. To simplify engineering requirements for plant growth structures on the Moon or Mars, lower pressures are required in order to reduce mass and decrease atmospheric leakage. Few facilities exist that can provide low pressure plant growth capabilities coupled with complete control over temperature, vapour pressure deficit (humidity), gas composition, nutrient delivery, and pressure. The Controlled Environment Systems Research Facility maintains five canopy-scale hypobaric plant growth chambers with capabilities ideally suited for low pressure advanced life support research. System performance evaluations during low pressure experiments on radish (Raphanus sativa L. cv. Cherry Bomb II) have demonstrated temperature control of +/- 0.5 ° C, vapour pressure deficit control of +/- 0.5 mb, CO2 injection control of +/- 20 ` ?mol mol-1 , and leakage rates of less than 1% per day. Keywords: hypobaric, plant growth chamber, advanced life support, controlled environment, low pressure, atmospheric control

Dixon, Mike; Stasiak, Michael; Wehkamp, Cara Ann; Lawson, Jamie

194

The effect of mesostructure heterogeneity on cracks initiation and the displacement distribution in NCF composites  

NASA Astrophysics Data System (ADS)

Non Crimp Fabrics (NCF) are promising new generation composite materials. They are now being used in some sections of composite industry, for example in wind turbine blades and boat hulls. The aerospace industry also shows an increasing interest in this material, thanks to the low cost of its manufacturing process. NCFs are special types of textile composites, made of layers of parallel fiber bundles oriented in different directions and separated by resin. Due to the manufacturing process the fiber bundles are not perfectly straight. They show a certain degree of waviness which decreases the stiffness and the strength of the material. The heterogeneous mesostructure affects the mechanical properties of the material and the failure mechanisms. This was studied using both numerical and experimental methods. In our experimental approach, a carbon fiber/epoxy resin laminate with uniform fiber distribution was manufactured by voluntarily introducing waviness to simulate the NCF composites. The displacement map was studied against the thickness of a sample loaded in tension, using ESPI (Electronic Speckle Pattern Interferometry). This can give us a primary idea of the micro damage initiation and the cracks' shapes.

Zrida, H.; Giannadis, K.; Varna, J.; Ayadi, Z.

2012-02-01

195

A study of the charged ice grains in the Enceladus plume with a composite size distribution  

NASA Astrophysics Data System (ADS)

We study the negatively charged ice grains in the Enceladus plume ranging from nanometer to micrometer in size based on Cassini's multiple instrument observations. We have constructed a composite size distribution by combining the CAPS nanograin size distributions (Hill et al., 2012 JGR) and the CDA dust power-law size distribution (Kempf et al., 2008 Icarus). We also study the charging of the ice grains using RPWS-LP data (Morooka et al., 2011 JGR). E3 and E5 CDA data are not available, but RPWS detected impacts of micron sized dust grains with the same power law size distribution (Ye et al., 2012 AGU meeting). Our size distribution formula is fitted with E3 and E5 CAPS and RPWS data, and constrained with the total dust charge density inferred from the RPWS-LP cold plasma data. The fitting with E17 and E18 CAPS nanograin data (Tokar et al., 2012 AGU meeting) and RPWS dust data (Ye et al., 2013 MAPS workshop) will also be discussed. Based on the charge per grain and the size distribution, the densities, source rate, motion, and currents of the ice grains can be calculated. Our size distribution implies that the grains ~2-20 nm dominate in both charge density and number density. But the mass density is very sensitive to the larger grains. We discuss the mass densities and source rates with different size distribution parameters, and compare with the water vapor plume. We study the trajectories of the charged ice grains in both Enceladus and Saturn frames, and calculate the dust currents from their motion. We find that the total dust pickup current at Enceladus is ?10^5 A. We will also discuss the ion and dust current systems and resulting magnetic perturbations near the moon.

Dong, Y.; Hill, T. W.

2013-12-01

196

The primary divisions of life: a phylogenomic approach employing composition-heterogeneous methods  

PubMed Central

The three-domains tree, which depicts eukaryotes and archaebacteria as monophyletic sister groups, is the dominant model for early eukaryotic evolution. By contrast, the ‘eocyte hypothesis’, where eukaryotes are proposed to have originated from within the archaebacteria as sister to the Crenarchaeota (also called the eocytes), has been largely neglected in the literature. We have investigated support for these two competing hypotheses from molecular sequence data using methods that attempt to accommodate the across-site compositional heterogeneity and across-tree compositional and rate matrix heterogeneity that are manifest features of these data. When ribosomal RNA genes were analysed using standard methods that do not adequately model these kinds of heterogeneity, the three-domains tree was supported. However, this support was eroded or lost when composition-heterogeneous models were used, with concomitant increase in support for the eocyte tree for eukaryotic origins. Analysis of combined amino acid sequences from 41 protein-coding genes supported the eocyte tree, whether or not composition-heterogeneous models were used. The possible effects of substitutional saturation of our data were examined using simulation; these results suggested that saturation is delayed by among-site rate variation in the sequences, and that phylogenetic signal for ancient relationships is plausibly present in these data. PMID:19571240

Foster, Peter G.; Cox, Cymon J.; Embley, T. Martin

2009-01-01

197

Experimental Investigation of the Shuttle Transportation System Composite Overwrapped Pressure Vessels for Stress Rupture Life  

NASA Technical Reports Server (NTRS)

A viewgraph presentation describing stress rupture testing on Composite Overwrapped Pressure Vessels (COPV) is shown. The topics include: 1) Purpose for Testing; 2) NASA WSTF COPV Test Program; 3) NASA WSTF Test Facilities; 4) COPV Impact Study; 5) Fluids Compatibility Testing; 6) Stress Rupture Testing; and 7) COPV Lifting.

Greene, Nathanael; Saulsberry, Regor; Yoder, Tommy; Forsyth, Brad; Carillo, Marlene; Thesken, John

2006-01-01

198

Composites  

NSDL National Science Digital Library

In this activity, learners explore how composites work by creating and testing their own composite for an imaginary company. This activity shows learners that composites are simply materials that are made up of two or more visibly distinct substances. Use this activity to talk about how composites are everywhere in our lives.

Research, Cornell C.

2003-01-01

199

Fatigue life prediction of rotor blade composites: Validation of constant amplitude formulations with variable amplitude experiments  

NASA Astrophysics Data System (ADS)

The effect of Constant Life Diagram (CLD) formulation on the fatigue life prediction under variable amplitude (VA) loading was investigated based on variable amplitude tests using three different load spectra representative for wind turbine loading. Next to the Wisper and WisperX spectra, the recently developed NewWisper2 spectrum was used. Based on these variable amplitude fatigue results the prediction accuracy of 4 CLD formulations is investigated. In the study a piecewise linear CLD based on the S-N curves for 9 load ratios compares favourably in terms of prediction accuracy and conservativeness. For the specific laminate used in this study Boerstra's Multislope model provides a good alternative at reduced test effort.

Westphal, T.; Nijssen, R. P. L.

2014-12-01

200

Distributed sensing of Composite Over-wrapped Pressure Vessels using Fiber-Bragg Gratings  

NASA Technical Reports Server (NTRS)

The increasing use of advanced composite materials in the wide range of applications including Space Structures is a great impetus to the development of smart materials. These materials offer a wide range of possibilities within the space program. But before they can be reliably incorporated into space flight applications, additional understanding is required in the area of damage tolerance of these materials. Efforts to enhance our understanding of failure modes, mechanical properties, long and short term environmental effects, cyclic damage accumulation and residual strength are needed. Thus we have employed the use of fiber optical sensors which offers an excellent opportunity exploit these materials through monitoring and characterizing their mechanical properties and thus the integrity of structures made from such materials during their life cycle. Use of these optical innovations provides an insight into structures that have not been available in the past, as well as the technology available to provide real time health monitoring throughout its life cycle. The embedded fiber optical sensor shows a clearly detectable sensitivity to changes in the near strain and stress fields of the host structure promoted by mechanical or thermal loading or, in certain conditions, structural damage. The last ten years have seen a large increase in the use of FBG based monitoring systems in a broad range of applications. Fiber Bragg gratings are use to monitor the structural properties of composite pressure vessels. These gratings optically inscribed into the core of a single mode fiber are used as a tool to monitor the stress strain relation in composite structures. The fiber Bragg sensors are both embedded within the composite laminates and bonded to the surface of the vessel with varying orientations with respect to the carbon fiber in the epoxy matrix. The response of these fiber-optic sensors is investigated by pressurizing the cylinder up to its burst pressure of around 4400 psi. This is done at both ambient and cryogenic temperatures using water and liquid nitrogen. The recorded response is compared with the response from conventional strain gauge also present on the vessel. Additionally, several vessels were tested that had been damaged to simulate different type of events, such as cut tow, delimitation and impact damage.

Grant, Joseph

2005-01-01

201

The small volume particle microsampler (SVPM): a new approach to particle size distribution and composition  

NASA Astrophysics Data System (ADS)

The characterization of trophically and geochemically important suspended particulate matter (SPM) has traditionally relied on bottle sampling and subsequent analysis with Coulter Multisizers and other instruments, which are not sufficient in preserving the in situ size, shape and composition of aggregated particles. The small volume particle microsampler (SVPM) is a sampling device that captures individual particles on filters with minimal disturbance for microscope image analysis of size distribution and composition. Sand grains, microalga ( Dunaliella tertiolecta) and laboratory cultivated flocs were used to test the SVPM's ability to determine particle size. For statistical analysis of the SVPM's capabilities, sand grain and algal size distribution, calculated as equivalent spherical diameter (ESD), were compared to Multisizer data while video images provided a comparison for the flocs. Non-aggregated sand particles sampled by the SVPM showed a size distribution that was similar to that of the Multisizer. Aggregated D. tertiolecta flocs were broken up by the Multisizer, and SVPM data indicated a significantly greater mean ESD. The SVPM showed significantly smaller mean ESDs than the video images because of the higher resolution of the sampler for small particles. In terms of particle concentration, the microsampler measured values similar to those of the Multisizer and video camera. The most important feature of the SVPM is its ability to capture aggregates for the analysis of composition, by histological stains or other means. The SVPM is an alternative method of sampling that is more effective in preserving aggregates for laboratory analyses and is less complicated and expensive than in situ optical sampling techniques, especially in documenting the lower end of the particle size spectrum.

Archambault, Marie-Claude; Grant, Jon; Hatcher, Annamarie

2001-10-01

202

26 CFR 1.401(a)(9)-9 - Life expectancy and distribution period tables.  

Code of Federal Regulations, 2010 CFR

...minimum distributions during an employee's lifetime under section 401(a)(9...following table, referred to as the Uniform Lifetime Table, is used for determining the distribution period for lifetime distributions to an...

2010-04-01

203

Burning-rate behavior in aluminized wide-distribution AP composite propellants  

Microsoft Academic Search

Burning-rate behavior of aluminized, wide-distribution ammonium-perchlorate (AP), hydroxyl-terminated-polybutadiene (HTPB)\\u000a binder composite propellants, both 2D laminates and 3D particulate propellants, is investigated experimentally. Very fine\\u000a (2-µm) AP (FAP) is used at a high FAP\\/binder ratio (75\\/25) with either coarse (>200 µm) AP (CAP) particles (3D particulate\\u000a propellants) or pressed AP slabs (simulating CAP particles in over-ventilated, 2D laminates). The results indicate

M. Q. Brewster; J. C. Mullen

2011-01-01

204

Biochemical composition of deep-sea decapod crustaceans with two different benthic life strategies off the Portuguese south coast  

NASA Astrophysics Data System (ADS)

The objectives of the present study were to characterize the benthic life strategies of Aristeus antennatus (Crustacea: Penaeidea), Parapenaeus longirostris (Crustacea: Penaeidea) and Nephrops norvegicus (Crustacea: Astacidea) on the basis of biochemical composition (proximate chemical composition, total lipids, glycogen and cholesterol contents), and its response to biological and environmental factors (sex, maturation, reproduction, food availability and depth) into account. The specimens were collected at depths between 200 and 600 m off the Portuguese south coast (Algarve). The nektobenthic species ( A. antennatus and P. longirostris) showed higher protein, lipid, cholesterol and glycogen contents, and lower moisture content in the muscle than the benthic-endobenthic species ( N. norvegicus). Consequently, the energy content of the nektobenthic species was also higher. Principal component analyses were used to assess the relationship between the different biochemical contents and to relate them to the biotic and abiotic factors. Depth seems to have the most important role in the observed trends of the biochemical composition. The increase of the ovarian lipid levels occurs as a result of the maturation process. The highest values were obtained in mature N. norvegicus females. The differences can be due to maternal investment (lipid metabolism of the female is geared to the provision of egg lipid), since N. norvegicus produce large lecithotrophic eggs. The biochemical differences observed in the three species did not seem to be due to distinct trophic strategies, but instead were a consequence of depth, which may have a significant interspecific effect on food intake. It was also evident that reproductive cycle has profound effects upon the biochemistry of the three species. Gonadal maturation has large associated energy costs due to the increase in biosynthetic work. Moreover, the biochemical composition would be influenced by or synchronized with seasonal feeding activity or food availability.

Rosa, R.; Nunes, M. L.

2003-01-01

205

Nuclear micro-beam analysis of deuterium distribution in carbon fibre composites for controlled fusion devices  

NASA Astrophysics Data System (ADS)

Probes made of carbon fibre composite NB41 were exposed to deuterium plasmas in the TEXTOR tokamak and in a simulator of plasma-wall interactions, PISCES. The aim was to assess the deuterium retention and its lateral and depth distribution. The analysis was performed by means of D( 3He, p) 4He and 12C( 3He, p) 14N nuclear reactions analysis using a standard (1 mm spot) and micro-beam (20 ?m resolution). The measurements have revealed non uniform distribution of deuterium atoms in micro-regions: differences by a factor of 3 between the maximum and minimum deuterium concentrations. The differences were associated with the orientation and type of fibres for samples exposed in PICSES. For surface structure in the erosion zone of samples exposed to a tokamak plasma the micro-regions were more complex. Depth profiling has indicated migration of fuel into the bulk of materials.

Petersson, P.; Kreter, A.; Possnert, G.; Rubel, M.

2010-06-01

206

Progressive failure methodologies for predicting residual strength and life of laminated composites  

NASA Technical Reports Server (NTRS)

Two progressive failure methodologies currently under development by the Mechanics of Materials Branch at NASA Langley Research Center are discussed. The damage tolerance/fail safety methodology developed by O'Brien is an engineering approach to ensuring adequate durability and damage tolerance by treating only delamination onset and the subsequent delamination accumulation through the laminate thickness. The continuum damage model developed by Allen and Harris employs continuum damage laws to predict laminate strength and life. The philosophy, mechanics framework, and current implementation status of each methodology are presented.

Harris, Charles E.; Allen, David H.; Obrien, T. Kevin

1991-01-01

207

Central Appalachian basin natural gas database: distribution, composition, and origin of natural gases  

USGS Publications Warehouse

The U.S. Geological Survey (USGS) has compiled a database consisting of three worksheets of central Appalachian basin natural gas analyses and isotopic compositions from published and unpublished sources of 1,282 gas samples from Kentucky, Maryland, New York, Ohio, Pennsylvania, Tennessee, Virginia, and West Virginia. The database includes field and reservoir names, well and State identification number, selected geologic reservoir properties, and the composition of natural gases (methane; ethane; propane; butane, iso-butane [i-butane]; normal butane [n-butane]; iso-pentane [i-pentane]; normal pentane [n-pentane]; cyclohexane, and hexanes). In the first worksheet, location and American Petroleum Institute (API) numbers from public or published sources are provided for 1,231 of the 1,282 gas samples. A second worksheet of 186 gas samples was compiled from published sources and augmented with public location information and contains carbon, hydrogen, and nitrogen isotopic measurements of natural gas. The third worksheet is a key for all abbreviations in the database. The database can be used to better constrain the stratigraphic distribution, composition, and origin of natural gas in the central Appalachian basin.

Roman-Colon, Yomayra A.; Ruppert, Leslie F.

2015-01-01

208

Carotenoids and carotenogenic genes in Podospora anserina: engineering of the carotenoid composition extends the life span of the mycelium.  

PubMed

Carotenoids have been identified in the fungus Podospora anserina and a parallel pathway to neurosporene and beta-carotene was established. Three genes for the beta-carotene branch have been cloned and their function elucidated. They correspond to the al-1, al-2 and al-3 genes from Neurospora crassa. They were individually and in combinations over-expressed in P. anserina in order to modify the carotenoid composition qualitatively and quantitatively. In the resulting transformants, carotenoid synthesis was up to eightfold increased and several intermediates of the pathway together with special cyclic carotenoids, beta-zeacarotene and 7,8-dihydro-beta-carotene, accumulated. All transformants with an over-expressed al-2 gene (encoding a phytoene synthase and a lycopene cyclase) displayed up to 31% prolonged life span. PMID:19277665

Strobel, Ingmar; Breitenbach, Jürgen; Scheckhuber, Christian Q; Osiewacz, Heinz D; Sandmann, Gerhard

2009-04-01

209

Effects of Life History Strategy on Fish Distribution and Use of Estuarine Salt Marsh and Shallow-Water Flat Habitats  

Microsoft Academic Search

To assess the potential for habitat isolation effects on estuarine nekton, we used two species with different dispersal abilities\\u000a and life history strategies, mummichog (Fundulus heteroclitus) and pinfish (Lagodon rhomboides) to examine: (1) distribution trends among estuarine shallow-water flat and various intertidal salt marsh habitats and (2)\\u000a the influence of salt marsh habitat size and isolation. Collections were conducted using

David L. Meyer; Martin H. Posey

2009-01-01

210

Shape reconstruction of composite structures with monitoring of modeling changes using Brillouin scattering based distributed optical fiber strain sensor network  

Microsoft Academic Search

This research proposes a novel approach for the shape reconstruction of composite structures using one of Brillouinscattering based distributed optical fiber strain sensors, PPP-BOTDA system. We have constructed a displacement reconstruction algorithm using the finite element model of the target structure. The remarkable point is that, not only using raw distributed strain data, but using an index of the non-uniformity

Mayuko Nishio; Nobuo Takeda

2009-01-01

211

Analysis of fragmentation in the single filament composite: Roles of fiber strength distributions and exclusion zone models  

Microsoft Academic Search

Exact equations are derived governing the evolution of fragments in a long fiber loaded according to the “single filament composite test.” These equations are derived with no a priori assumptions regarding the distribution for fiber strength except that the distribution of fiber flaws along the length follows a compound Poisson process in terms of flaw strength. Furthermore, the interface model

C.-Y. Hui; S. L. Phoenix; L. Kogan

1996-01-01

212

ACTIVE CONTROL OF SOUND FIELDS FROM A COMPOSITE PLATE USING THE ANISOTROPY AND SHAPE OF DISTRIBUTED PVDF ACTUATORS  

Microsoft Academic Search

Compared to piezoceramic material, polyvinylidene fluoride polymer has anisotropic electromechanical material properties. Using the fact that the anisotropy and shape of distributed piezopolymer actuators have coupling effects with the vibration modes of structures, studies on the design of distributed piezopolymer actuators are performed in order to improve the effectiveness of active control of the sound fields radiated from composite structures.

S. J. Kim; K. W. Yoon

1997-01-01

213

Electric field distribution around the chain of composite nanoparticles in ferrofluids  

NASA Astrophysics Data System (ADS)

Composite nanoparticles (NPs) have the ability of combining materials with different properties together, thus receiving extensive attention in many fields. Here we theoretically investigate the electric field distribution around core/shell NPs (a type of composite NPs) in ferrofluids under the influence of an external magnetic field. The NPs are made of cobalt (ferromagnetic) coated with gold (metallic). Under the influence of the external magnetic field, these NPs will align along the direction of this field, thus forming a chain of NPs. According to Laplace's equations, we obtain electric fields inside and outside the NPs as a function of the incident wavelength by taking into account the mutual interaction between the polarized NPs. Our calculation results show that the electric field distribution is closely related to the resonant incident wavelength, the metallic shell thickness, and the inter-particle distance. These analytical calculations agree well with our numerical simulation results. This kind of field-induced anisotropic soft-matter systems offers the possibility of obtaining an enhanced Raman scattering substrate due to enhanced electric fields.

Fan, Chun-Zhen; Wang, Jun-Qiao; Cheng, Yong-Guang; Ding, Pei; Liang, Er-Jun; Huang, Ji-Ping

2013-08-01

214

The distribution of compositional classes in the asteroid belt: A cosmochemical fingerprint?  

NASA Technical Reports Server (NTRS)

Studies of the physical properties of the asteroids show a nonrandom distribution of types across the belt for asteroid classes E, S, M, F, C, P, and D. The general trend is for asteroids in the inner belt to have higher albedos and stronger mafic silicate absorption features than those asteroids located further out in the belt. One interpretation of this trend is that the asteroids, which occupy the region between the silicate rich terrestrial planets and the volatile rich outer planets, have preserved in their heliocentric compositional distribution a cosmochemical fingerprint of the thermodynamic conditions present in the solar nebula at the time of their formation. This hypothesis predicts that the differences in the spectral properties among the low albedo classes (C, P, F, P, and D) are due to temperature controlled processes which formed carbonaceous opaques. If this is true then the exact composition of the opaque components could, in principle, be used to determine the thermodynamic conditions between the orbits of Mars and Jupiter during the formation of the asteroids.

Gradie, J.

1985-01-01

215

Feeding into old age: long-term effects of dietary fatty acid supplementation on tissue composition and life span in mice  

PubMed Central

Smaller mammals, such as mice, possess tissues containing more polyunsaturated fatty acids (PUFAs) than larger mammals, while at the same time live shorter lives. These relationships have been combined in the ‘membrane pacemaker hypothesis of aging’. It suggests that membrane PUFA content might determine an animal’s life span. PUFAs in general and certain long-chain PUFAs in particular, are highly prone to lipid peroxidation which brings about a high rate of reactive oxygen species (ROS) production. We hypothesized that dietary supplementation of either n-3 or n-6 PUFAs might affect (1) membrane phospholipid composition of heart and liver tissues and (2) life span of the animals due to the altered membrane composition, and subsequent effects on lipid peroxidation. Therefore, we kept female laboratory mice from the C57BL/6 strain on three diets (n-3 PUFA rich, n-6 PUFA rich, control) and assessed body weights, life span, heart, and liver phospholipid composition after the animals had died. We found that while membrane phospholipid composition clearly differed between feeding groups, life span was not directly affected. However, we were able to observe a positive correlation between monounsaturated fatty acids in cardiac muscle and life span. PMID:20981551

Ruf, Thomas

2010-01-01

216

A detailed investigation of ambient aerosol composition and size distribution in an urban atmosphere.  

PubMed

This research was executed between March 2009 and March 2010 to monitor particulate matter size distribution and its composition in Istanbul. Particulate matter composition was determined using ion chromatography and inductively coupled plasma optical emission spectrometry. The sampling point is adjacent to a crowded road and the Bosporus Strait. Two prevailing particulate modes are found throughout PM10 by sampling with a nine-stage low-volume cascade impactor. First mode in the fine mode is found to be between 0.43 and 0.65 ?m, whereas the other peak was observed between 3.3 and 4.7 ?m, referring to the coarse mode. The mean PM10 concentration was determined as 41.2 ?g/m(3), with a standard deviation of 16.92 ?g/m(3). PM0.43 had the highest mean concentration value of 10.67 ?g/m(3), making up nearly one fourth of the total PM10 mass. For determining the effect of traffic on particulate matter (PM) composition and distribution, four different sampling cycles were applied: entire day, nighttime, rush hour, and rush hour at weekdays. SO4(-2) and organic carbon/elemental carbon proportions are found to be lower in night samples, representing a decrease in traffic. The long-range transports of dust storms were observed during the sampling periods. Their effects were determined analytically and their route models were run by the HYSPLIT model and validated through satellite photographs taken by the NASA Earth Observatory. PMID:22968673

Kuzu, S Levent; Saral, Arslan; Demir, Selami; Summak, Gülsüm; Demir, Göksel

2013-04-01

217

Temporal Variations in the Abundance and Composition of Biofilm Communities Colonizing Drinking Water Distribution Pipes  

PubMed Central

Pipes that transport drinking water through municipal drinking water distribution systems (DWDS) are challenging habitats for microorganisms. Distribution networks are dark, oligotrophic and contain disinfectants; yet microbes frequently form biofilms attached to interior surfaces of DWDS pipes. Relatively little is known about the species composition and ecology of these biofilms due to challenges associated with sample acquisition from actual DWDS. We report the analysis of biofilms from five pipe samples collected from the same region of a DWDS in Florida, USA, over an 18 month period between February 2011 and August 2012. The bacterial abundance and composition of biofilm communities within the pipes were analyzed by heterotrophic plate counts and tag pyrosequencing of 16S rRNA genes, respectively. Bacterial numbers varied significantly based on sampling date and were positively correlated with water temperature and the concentration of nitrate. However, there was no significant relationship between the concentration of disinfectant in the drinking water (monochloramine) and the abundance of bacteria within the biofilms. Pyrosequencing analysis identified a total of 677 operational taxonomic units (OTUs) (3% distance) within the biofilms but indicated that community diversity was low and varied between sampling dates. Biofilms were dominated by a few taxa, specifically Methylomonas, Acinetobacter, Mycobacterium, and Xanthomonadaceae, and the dominant taxa within the biofilms varied dramatically between sampling times. The drinking water characteristics most strongly correlated with bacterial community composition were concentrations of nitrate, ammonium, total chlorine and monochloramine, as well as alkalinity and hardness. Biofilms from the sampling date with the highest nitrate concentration were the most abundant and diverse and were dominated by Acinetobacter. PMID:24858562

Kelly, John J.; Minalt, Nicole; Culotti, Alessandro; Pryor, Marsha; Packman, Aaron

2014-01-01

218

Impact of filler size and distribution on roughness and wear of composite resin after simulated toothbrushing  

PubMed Central

Objectives Nanofilled composite resins are claimed to provide superior mechanical properties compared with microhybrid resins. Thus, the aim of this study was to compare nanofilled with microhybrid composite resins. The null hypothesis was that the size and the distribution of fillers do not influence the mechanical properties of surface roughness and wear after simulated toothbrushing test. Material and methods Ten rectangular specimens (15 mm x 5 mm x 4 mm) of Filtek Z250 (FZ2), Admira (A), TPH3 (T),Esthet-X (EX), Estelite Sigma (ES), Concept Advanced (C), Grandio (G) and Filtek Z350 (F) were prepared according to manufacturer's instructions. Half of each top surface was protected with nail polish as control surface (not brushed) while the other half was assessed with five random readings using a roughness tester (Ra). Following, the specimens were abraded by simulated toothbrushing with soft toothbrushes and slurry comprised of 2:1 water and dentifrice (w/w). 100,000 strokes were performed and the brushed surfaces were re-analyzed. Nail polish layers were removed from the specimens so that the roughness (Ra) and the wear could be assessed with three random readings (µm). Data were analyzed by ANOVA and Tukey's multiple-comparison test (?=0.05). Results Overall outcomes indicated that composite resins showed a significant increase in roughness after simulated toothbrushing, except for Grandio, which presented a smoother surface. Generally, wear of nanofilled resins was significantly lower compared with microhybrid resins. Conclusions As restorative materials suffer alterations under mechanical challenges, such as toothbrushing, the use of nanofilled materials seem to be more resistant than microhybrid composite resins, being less prone to be rougher and worn. PMID:23138735

de OLIVEIRA, Gabriela Ulian; MONDELLI, Rafael Francisco Lia; CHARANTOLA RODRIGUES, Marcela; FRANCO, Eduardo Batista; ISHIKIRIAMA, Sérgio Kiyoshi; WANG, Linda

2012-01-01

219

Development of a Composite Lifestyle Index and Its Relationship to Quality of Life Improvement: The CLI Pilot Study  

PubMed Central

An important component to optimal health is quality of life (QOL). Several healthy lifestyle behaviors have independently shown to improve QOL. The simultaneous implementation of multiple lifestyle behaviors is thought to be difficult, and the current literature lacks the assessment of multiple lifestyle behaviors simultaneously with respect to the effect on QOL. This current pilot study sought to develop a method to quantify multiple lifestyle behaviors into a single index value. This value was then measured with QOL for a possible correlation. The results showed that it is possible to convert multiple raw healthy lifestyle data points into a composite value and that an improvement in this value correlates to an improved QOL. After 12 months of participation in a cardiovascular risk reduction program, study participants (N = 35) demonstrated a 37.4% (P < 0.001) improvement in the composite lifestyle index (CLI). The improved CLI demonstrated a correlation with a statistically significant improvement in how participants rated their overall health in 12 months (r = 0.701, P < 0.001) as well as the number of self-reported unhealthy days per month in 12 months (r = ?0.480, P = 0.004). PMID:24967137

Lenz, Thomas L.; Gillespie, Nicole D.; Skradski, Jessica J.; Viereck, Laura K.; Packard, Kathleen A.; Monaghan, Michael S.

2013-01-01

220

Application of Distribution Transformer Thermal Life Models to Electrified Vehicle Charging Loads Using Monte-Carlo Method: Preprint  

SciTech Connect

Concentrated purchasing patterns of plug-in vehicles may result in localized distribution transformer overload scenarios. Prolonged periods of transformer overloading causes service life decrements, and in worst-case scenarios, results in tripped thermal relays and residential service outages. This analysis will review distribution transformer load models developed in the IEC 60076 standard, and apply the model to a neighborhood with plug-in hybrids. Residential distribution transformers are sized such that night-time cooling provides thermal recovery from heavy load conditions during the daytime utility peak. It is expected that PHEVs will primarily be charged at night in a residential setting. If not managed properly, some distribution transformers could become overloaded, leading to a reduction in transformer life expectancy, thus increasing costs to utilities and consumers. A Monte-Carlo scheme simulated each day of the year, evaluating 100 load scenarios as it swept through the following variables: number of vehicle per transformer, transformer size, and charging rate. A general method for determining expected transformer aging rate will be developed, based on the energy needs of plug-in vehicles loading a residential transformer.

Kuss, M.; Markel, T.; Kramer, W.

2011-01-01

221

Estimation of prokaryotic supergenome size and composition from gene frequency distributions  

PubMed Central

Background Because prokaryotic genomes experience a rapid flux of genes, selection may act at a higher level than an individual genome. We explore a quantitative model of the distributed genome whereby groups of genomes evolve by acquiring genes from a fixed reservoir which we denote as supergenome. Previous attempts to understand the nature of the supergenome treated genomes as random, independent collections of genes and assumed that the supergenome consists of a small number of homogeneous sub-reservoirs. Here we explore the consequences of relaxing both assumptions. Results We surveyed several methods for estimating the size and composition of the supergenome. The methods assumed that genomes were either random, independent samples of the supergenome or that they evolved from a common ancestor along a known tree via stochastic sampling from the reservoir. The reservoir was assumed to be either a collection of homogeneous sub-reservoirs or alternatively composed of genes with Gamma distributed gain probabilities. Empirical gene frequencies were used to either compute the likelihood of the data directly or first to reconstruct the history of gene gains and then compute the likelihood of the reconstructed numbers of gains. Conclusions Supergenome size estimates using the empirical gene frequencies directly are not robust with respect to the choice of the model. By contrast, using the gene frequencies and the phylogenetic tree to reconstruct multiple gene gains produces reliable estimates of the supergenome size and indicates that a homogeneous supergenome is more consistent with the data than a supergenome with Gamma distributed gain probabilities. PMID:25572821

2014-01-01

222

Using and Distributing Spaceflight Data: The Johnson Space Center Life Sciences Data Archive  

NASA Technical Reports Server (NTRS)

Life sciences data collected before, during and after spaceflight are valuable and often irreplaceable. The Johnson Space Center Life is hard to find, and much of the data (e.g. Sciences Data Archive has been designed to provide researchers, engineers, managers and educators interactive access to information about and data from human spaceflight experiments. The archive system consists of a Data Acquisition System, Database Management System, CD-ROM Mastering System and Catalog Information System (CIS). The catalog information system is the heart of the archive. The CIS provides detailed experiment descriptions (both written and as QuickTime movies), hardware descriptions, hardware images, documents, and data. An initial evaluation of the archive at a scientific meeting showed that 88% of those who evaluated the catalog want to use the system when completed. The majority of the evaluators found the archive flexible, satisfying and easy to use. We conclude that the data archive effectively provides key life sciences data to interested users.

Cardenas, J. A.; Buckey, J. C.; Turner, J. N.; White, T. S.; Havelka,J. A.

1995-01-01

223

Optical design of LED edge-lit backlight based on molecular dynamics method using a random/regular composite distribution  

NASA Astrophysics Data System (ADS)

A dot generation scheme for random/regular composite distribution is developed based on the molecular dynamics (MD) method for application in light guide design. This is done by introducing random r-cut values in the force field acting between dots. The results indicated that the developed scheme can effectively randomize a regular distribution by increasing the random component of the r-cut value. In addition, for a composite distribution, in order to obtain a smooth distribution across the random/regular distribution interface, there cannot be a large difference between the expected r-cut value for these two distributions; otherwise, a distinct linear strip will occur. Finally, two practical examples are presented. One randomizes an already optimized dot distribution in a regular arrangement. The other uses a composite distribution generated by the present scheme which is substituted into the optical software to perform the optical optimization. These two examples prove the validity of the present scheme and its efficient application in the optical design of light guides.

Chang, Jee-Gong; Ju, Shin-Pon; Lee, Shin-Chin; Hsieh, Jin-Yuan

2009-12-01

224

Unusual compositions of microflora of vacuum-packaged beef primal cuts of very long storage life.  

PubMed

Vacuum-packaged top butt cuts from a beef packing plant that does not use any carcass decontaminating interventions were assessed for their organoleptic and microbiological properties during storage at 2 or -1.5°C. Cuts stored at 2°C were acceptable after storage for 140 days but were unacceptable after 160 days because of persistent sour, acid odors. Odors of cuts stored at -1.5°C for 160 days were acceptable. The numbers of aerobes on cuts increased from <1 log CFU/cm(2) to 7 or 6 log CFU/cm(2) for cuts stored at 2 or -1.5°C, respectively. The numbers of Enterobacteriaceae increased from <-1 log CFU/cm(2) to 5 or 3 log CFU/cm(2) for cuts stored at 2 or -1.5°C, respectively. Bacteria recovered from initial microflora were, mainly, strictly aerobic organisms. Bacteria recovered from cuts stored for 160 days were mainly Carnobacterium spp. that grew on an acetate-containing agar generally selective for lactic acid bacteria other than Carnobacterium. C. divergens and C. maltaromaticum were recovered from cuts stored at 2°C, but C. maltaromaticum was the only species of Carnobacterium recovered from cuts stored at -1.5°C. No lactic acid bacteria of genera that usually predominate in the spoilage microflora of vacuum-packaged beef at late storage times were recovered from the spoilage microflora. The findings indicate that carnobacteria, initially present at very small numbers, grew exponentially to persistently dominate the spoilage microflora of vacuum-packaged beef cuts of unusually long storage life. PMID:25474067

Youssef, M K; Gill, C O; Tran, F; Yang, X

2014-12-01

225

Deformation and Life Analysis of Composite Flywheel Disk and Multi-disk Systems  

NASA Technical Reports Server (NTRS)

In this study an attempt is made to put into perspective the problem of a rotating disk, be it a single disk or a number of concentric disks forming a unit. An analytical model capable of performing an elastic stress analysis for single/multiple, annular/solid, anisotropic/isotropic disk systems, subjected to both pressure surface tractions, body forces (in the form of temperature-changes and rotation fields) and interfacial misfits is derived and discussed. Results of an extensive parametric study are presented to clearly define the key design variables and their associated influence. In general the important parameters were identified as misfit, mean radius, thickness, material property and/or load gradation, and speed; all of which must be simultaneously optimized to achieve the "best" and most reliable design. Also, the important issue of defining proper performance/merit indices (based on the specific stored energy), in the presence of multiaxiality and material anisotropy is addressed. These merit indices are then utilized to discuss the difference between flywheels made from PMC and TMC materials with either an annular or solid geometry. Finally two major aspects of failure analysis, that is the static and cyclic limit (burst) speeds are addressed. In the case of static limit loads, upper, lower, and out-of-plane bounds for disks with constant thickness are presented for both the case of internal pressure loading (as one would see in a hydroburst test) and pure rotation (as in the case of a free spinning disk). The results (interaction diagrams) are displayed graphically in designer friendly format. For the case of fatigue, a representative fatigue/life master curve is illustrated in which the normalized limit speed versus number of applied cycles is given for a cladded TMC disk application.

Arnold, S. M.; Saleeb, A. F.; AlZoubi, N. R.

2001-01-01

226

Glass Composition Constraint Recommendations for Use in Life-Cycle Mission Modeling  

SciTech Connect

The component concentration limits that most influence the predicted Hanford life-cycle HLW glass volume by HTWOS were re-evaluated. It was assumed that additional research and development work in glass formulation and melter testing would be performed to improve the understanding of component effects on the processability and product quality of these HLW glasses. Recommendations were made to better estimate the potential component concentration limits that could be applied today while technology development is underway to best estimate the volume of HLW glass that will eventually be produced at Hanford. The limits for concentrations of P2O5, Bi2O3, and SO3 were evaluated along with the constraint used to avoid nepheline formation in glass. Recommended concentration limits were made based on the current HLW glass property models being used by HTWOS (Vienna et al. 2009). These revised limits are: 1) The current ND should be augmented by the OB limit of OB ? 0.575 so that either the normalized silica (NSi) is less that the 62% limit or the OB is below the 0.575 limit. 2) The mass fraction of P2O5 limit should be revised to allow for up to 4.5 wt%, depending on CaO concentrations. 3) A Bi2O3 concentration limit of 7 wt% should be used. 4) The salt accumulation limit of 0.5 wt% SO3 may be increased to 0.6 wt%. Again, these revised limits do not obviate the need for further testing, but make it possible to more accurately predict the impact of that testing on ultimate HLW glass volumes.

McCloy, John S.; Vienna, John D.

2010-05-03

227

Investigation on stress distribution of multilayered composite structure (MCS) using infrared thermographic technique  

NASA Astrophysics Data System (ADS)

In this paper, the thermoelastic stress analysis (TSA) on a multilayered composite structure (MCS) was investigated by means of lock-in thermographic image technique (LITI). The application of thermoelastic stress analysis on MCS becomes particularly complicated due to consisting of different material components, which determines the different thermoelastic coupling response depended on material thermal-physical property. The thermoelastic coupling constants (TCC) of GFRP, medium-carbon steel and foam were obtained through thermomechanical calibration experiments, respectively. An artificial neural network was proposed to determine the component of MCS. Comparisons between finite element analysis (FEA) and LITI measurement are reported. It is found that the stress distribution of MCS can be evaluated with good accuracies using LITI measurement.

Liu, Junyan; Gong, Jinlong; Liu, Liqiang; Qin, Lei; Wang, Yang

2013-11-01

228

Decompression vs. Decomposition: Distribution, Amount, and Gas Composition of Bubbles in Stranded Marine Mammals  

PubMed Central

Gas embolic lesions linked to military sonar have been described in stranded cetaceans including beaked whales. These descriptions suggest that gas bubbles in marine mammal tissues may be more common than previously thought. In this study we have analyzed gas amount (by gas score) and gas composition within different decomposition codes using a standardized methodology. This broad study has allowed us to explore species-specific variability in bubble prevalence, amount, distribution, and composition, as well as masking of bubble content by putrefaction gases. Bubbles detected within the cardiovascular system and other tissues related to both pre- and port-mortem processes are a common finding on necropsy of stranded cetaceans. To minimize masking by putrefaction gases, necropsy, and gas sampling must be performed as soon as possible. Before 24?h post mortem is recommended but preferably within 12?h post mortem. At necropsy, amount of bubbles (gas score) in decomposition code 2 in stranded cetaceans was found to be more important than merely presence vs. absence of bubbles from a pathological point of view. Deep divers presented higher abundance of gas bubbles, mainly composed of 70% nitrogen and 30% CO2, suggesting a higher predisposition of these species to suffer from decompression-related gas embolism. PMID:22675306

de Quirós, Yara Bernaldo; González-Diaz, Oscar; Arbelo, Manuel; Sierra, Eva; Sacchini, Simona; Fernández, Antonio

2012-01-01

229

On effect of particle size distribution on the elastic/plastic deformation of metal matrix composites  

SciTech Connect

The elastic-plastic deformation behavior of particulate reinforced metal matrix composites is strongly influenced by not only properties of the metal matrix and reinforcement but also microstructural parameters such as particle size, volume fraction, reinforcement shape and topology that are dependent on the particular processing route used to fabricate the materials. Nan and Clarke have recently developed a hybrid, analytical model by incorporating essential features of both continuum plasticity and dislocation plasticity, which is a combination of the key features of dislocation plasticity with a continuum mechanics approach based on effective medium approximations (EMA). In the present contribution, particular attention will be paid to two problems on the hybrid model. Firstly, the authors introduce a volume-weighted averaging procedure in Nan and Clarke`s methodology and then re-estimate the effect of particle size distribution on deformation in the case of both no damage and including particle fracture. For illustrative and quantitative purposes, the calculations are compared with the experimental results on particular SiC-Al composite by Lloyd. Secondly, the difference between the deformation, secant and the incremental, tangent modulus approaches chosen for EMA modeling is addressed.

Nan, C.W. [Univ. des Saarlandes, Saarbruecken (Germany)] [Univ. des Saarlandes, Saarbruecken (Germany); [Wuhan Univ. of Technology, Hubei (China). Advanced Materials Research Inst.; Birringer, R. [Univ. des Saarlandes, Saarbruecken (Germany)] [Univ. des Saarlandes, Saarbruecken (Germany); Gleiter, H. [Forschungszentrum Karlsruhe GmbH (Germany)] [Forschungszentrum Karlsruhe GmbH (Germany)

1997-10-01

230

Temperature Distribution in a Composite of Opaque and Semitransparent Spectral Layers  

NASA Technical Reports Server (NTRS)

The analysis of radiative transfer becomes computationally complex for a composite when there are multiple layers and multiple spectral bands. A convenient analytical method is developed for combined radiation and conduction in a composite of alternating semitransparent and opaque layers. The semi- transparent layers absorb, scatter, and emit radiation, and spectral properties with large scattering are included. The two-flux method is used, and its applicability is verified by comparison with a basic solution in the literature. The differential equation in the two-flux method Is solved by deriving a Green's function. The solution technique is applied to analyze radiation effects in a multilayer zirconia thermal barrier coating with internal radiation shields for conditions in an aircraft engine combustor. The zirconia radiative properties are modeled by two spectral bands. Thin opaque layers within the coating are used to decrease radiant transmission that can degrade the zirconia insulating ability. With radiation shields, the temperature distributions more closely approach the opaque limit that provides the lowest metal wall temperatures.

Siegel, Robert

1997-01-01

231

Body composition and fat distribution pattern of urban elderly females, Delhi, India.  

PubMed

The present study was conducted on females (n = 279) in the age range of 51-89 year, living in the urban dwellings of Delhi, India. Another group of 21-25 years old young adult females was taken as a control group. A total of 14 anthropometric measurements were taken: stature, sitting height, weight, skinfold thickness at nine different sites over the body and body girths such as upper arm, waist and hip circumference. Indices like body mass index, grand mean thickness, waist-hip ratio were computed to assess the body composition. Fat profile and responsiveness of different skinfold sites towards fat accumulation were studied to find out the regional fat distribution with advancing age. Redistribution of body fat was found to take place with increasing age. A relative preponderance of upper body fat was visible among elderly subjects. However, a clear reverse trend was observed in the young control group females. Significant differences were observed with regards to the body composition and fat profile between young adult females and test group females. Abdomen and the sub-scapular area were reported to be the most sensitive sites for fat deposition as the age advanced. The stature and sitting height showed significant decline with age. All the indices of adiposity i.e. grand mean thickness, waist-hip ratio and body mass index revealed significant changes in elderly females when compared with young adult control group females. PMID:16417150

Tyagi, Renu; Kapoor, Satwanti; Kapoor, Anup Kumar

2005-12-01

232

Europa's Crust and Ocean: Origin, Composition, and the Prospects for Life  

USGS Publications Warehouse

We have considered a wide array of scenarios for Europa's chemical evolution in an attempt to explain the presence of ice and hydrated materials on its surface and to understand the physical and chemical nature of any ocean that may lie below. We postulate that, following formation of the jovian system, the europan evolutionary sequence has as its major links: (a) initial carbonaceous chondrite rock, (b) global primordial aqueous differentiation and formation of an impure primordial hydrous crust, (c) brine evolution and intracrustal differentiation, (d) degassing of Europa's mantle and gas venting, (e) hydrothermal processes, and (f) chemical surface alteration. Our models were developed in the context of constraints provided by Galileo imaging, near infrared reflectance spectroscopy, and gravity and magnetometer data. Low-temperature aqueous differentiation from a carbonaceous CI or CM chondrite precursor, without further chemical processing, would result in a crust/ocean enriched in magnesium sulfate and sodium sulfate, consistent with Galileo spectroscopy. Within the bounds of this simple model, a wide range of possible layered structures may result; the final state depends on the details of intracrustal differentiation. Devolatilization of the rocky mantle and hydrothermal brine reactions could have produced very different ocean/crust compositions, e.g., an ocean/crust of sodium carbonate or sulfuric acid, or a crust containing abundant clathrate hydrates. Realistic chemical-physical evolution scenarios differ greatly in detailed predictions, but they generally call for a highly impure and chemically layered crust. Some of these models could lead also to lateral chemical heterogeneities by diapiric upwellings and/or cryovolcanism. We describe some plausible geological consequences of the physical-chemical structures predicted from these scenarios. These predicted consequences and observed aspects of Europa's geology may serve as a basis for further analys is and discrimination among several alternative scenarios. Most chemical pathways could support viable ecosystems based on analogy with the metabolic and physiological versatility of terrestrial microorganisms. ?? 2000 Academic Press.

Kargel, J.S.; Kaye, J.Z.; Head, J. W., III; Marion, G.M.; Sassen, R.; Crowley, J.K.; Ballesteros, O.P.; Grant, S.A.; Hogenboom, D.L.

2000-01-01

233

Supporting Distributed Team Working in 3D Virtual Worlds: A Case Study in Second Life  

ERIC Educational Resources Information Center

Purpose: The purpose of this paper is to report on a study into how a three-dimensional (3D) virtual world (Second Life) can facilitate socialisation and team working among students working on a team project at a distance. This models the situation in many commercial sectors where work is increasingly being conducted across time zones and between…

Minocha, Shailey; Morse, David R.

2010-01-01

234

Optimum Accelerated Life Test Plans for Log-Location-Scale Distributions with Multiple Objectives  

Microsoft Academic Search

Most of the previous work on planning accelerated life tests (ALTs) is focused on a sole estimating objective, such as some specified 100p-th quantitle lifetime, the reliability of the product over some specified period of time, and accelerating factor. However, it is impossible to estimate only a single objective parameter after conducting such costly tests. In this paper, we consider

Hai-Yan Xu; He-Liang Fei

2009-01-01

235

Antarctic Marine Biodiversity - What Do We Know About the Distribution of Life in the Southern Ocean?  

Microsoft Academic Search

The remote and hostile Southern Ocean is home to a diverse and rich community of life that thrives in an environment dominated by glaciations and strong currents. Marine biological studies in the region date back to the nineteenth century, but despite this long history of research, relatively little is known about the complex interactions between the highly seasonal physical environment

Huw J. Griffiths; Richard Kazimierz Frank Unsworth

2010-01-01

236

Tracing subsoil organic matter compositional changes by radiocarbon and plant leaf wax distributional changes  

NASA Astrophysics Data System (ADS)

The carbon pool in subsoils is thought to be considerably larger than in the upper 30 cm. However, factors like turnover, stabilization and distribution of organic matter (OM) are less well understood than in topsoils. The investigation of changes in OM composition with depth enables a better understanding of the peculiarity of subsoil OM in contrast to the already extensively studied topsoil OM. Analysis of long chained n-alkanes and n-fatty acids in soil profiles sampled in high resolution, combined with radiocarbon data of bulk soil, is a tool to demonstrate spatial distribution and the degradation of plant leaf wax-derived material as a defined source of soil organic. We analysed the OM in 3.15 m long soil transects under an even aged European beech (Fagus sylvatica L.) forest in Northern Germany (Grinderwald, Lower Saxony) for lipid and radiocarbon analysis. Samples were taken from a grid raster with eight sampling points increasing in distance to the main tree (45cm grid dimension) and from five depths (10, 35, 60, 85, 110 cm) resulting 40 samples per transect. Organic carbon contents in the podzolic Cambisol decrease from 1.69 % in the A-horizon to 0.02 % in the C-horizon at 110 cm depth. The distribution of organic carbon contents shows no significant trend with increasing distance to the beeches in all transects. We compare the distribution of long-chain n-alkanes (C27, C29 and C31) and n-fatty acids (>C20), known as components mainly derived from leaf waxes of higher plants, in the different transect/depth intervals. Distributional and quantitative changes in the transects, combined with bulk soil 14C-analyses, reflecting apparent mean residence time of OM, are used to identify how fast OM is degraded from surface to subsoil horizons. Furthermore, spatial OM heterogeneity in the transects is investigated. We expect a more significant heterogeneity in the lipid distribution and nearly similar decreasing contents for n-alkanes as well as n-fatty acids. Furthermore, the comparison between these two compound classes with increasing depth gives information on the accumulation of more resistant (aliphatic) and more easily degradable (carboxylic acids) OM components.

John, Stephan; Angst, Gerrit; Mueller, Carsten W.; Heinze, Stefanie; Marschner, Bernd; Rethemeyer, Janet

2014-05-01

237

USE OF MULTI-PHOTON LASER-SCANNING MICROSCOPY TO DESCRIBE THE DISTRIBUTION OF XENOBIOTIC CHEMICALS IN FISH EARLY LIFE STAGES  

EPA Science Inventory

To better understand the mechanisms by which persistent bioaccumulative toxicants (PBTs) produce toxicity during fish early life stages (ELS), dose response relationships need to be determined in relation to the dynamic distribution of chemicals in sensitive tissues. In this stud...

238

Failure models for textile composites  

NASA Technical Reports Server (NTRS)

The goals of this investigation were to: (1) identify mechanisms of failure and determine how the architecture of reinforcing fibers in 3D woven composites controlled stiffness, strength, strain to failure, work of fracture, notch sensitivity, and fatigue life; and (2) to model composite stiffness, strength, and fatigue life. A total of 11 different angle and orthogonal interlock woven composites were examined. Composite properties depended on the weave architecture, the tow size, and the spatial distributions and strength of geometrical flaws. Simple models were developed for elastic properties, strength, and fatigue life. A more complicated stochastic model, called the 'Binary Model,' was developed for damage tolerance and ultimate failure. These 3D woven composites possessed an extraordinary combination of strength, damage tolerance, and notch insensitivity.

Cox, Brian

1995-01-01

239

Archaeal Assemblages Inhabiting Temperate Mixed Forest Soil Fluctuate in Taxon Composition and Spatial Distribution over Time  

PubMed Central

This study explored the persistence and spatial distribution of a diverse Archaeal assemblage inhabiting a temperate mixed forest ecosystem. Persistence under native conditions was measured from 2001 to 2010, 2011, and 2012 by comparison of 16S rRNA gene clone libraries. The Archaeal assemblages at each of these time points were found to be significantly different (AMOVA, P < 0.01), and the nature of this difference was dependent on taxonomic rank. For example, the cosmopolitan genus g_Ca. Nitrososphaera (I.1b) was detected at all time points, but within this taxon the abundance of s_SCA1145, s_SCA1170, and s_Ca. N. gargensis fluctuated over time. In addition, spatial heterogeneity (patchiness) was measured at these time points using 1D TRFLP-SSCP fingerprinting to screen soil samples covering multiple spatial scales. This included soil collected from small volumes of 3 cubic centimeters to larger scales—over a surface area of 50?m2, plots located 1.3?km apart, and a separate locality 23?km away. The spatial distribution of Archaea in these samples changed over time, and while g_Ca. Nitrososphaera (I.1b) was dominant over larger scales, patches were found at smaller scales that were dominated by other taxa. This study measured the degree of change for Archaeal taxon composition and patchiness over time in temperate mixed forest soil. PMID:23983618

Swanson, Colby A.; Sliwinski, Marek K.

2013-01-01

240

Atmospheric Neutral Analyzer (ANA) for In-situ Neutral Mass Composition and Velocity Distribution Measurements  

NASA Astrophysics Data System (ADS)

We present the design and the development of an atmospheric neutral analyzer, a new imaging instrument for in-situ measurements of both the mass composition of neutrals and their 2-dimensional velocities in the upper atmosphere. This instrument combines radio-frequency mass analysis and CCD particle imaging to provide images of detailed 2D velocity distribution functions of individual mass species. It comprises an entrance aperture, electron source, ion accelerator, a radio-frequency (RF) ion mass analyzer, and an imaging particle detector. The electron source ionizes a collimated fraction of the incident neutral particles while preserving their velocities. The ion accelerator accelerates all ionized neutrals to a fixed energy in the perpendicular direction to the entrance aperture plane. The mass analyzer further accelerates those of a specific velocity (and hence mass) for further detection, using a RF electric field of specific amplitude and frequency. In the imaging particle detector, the detected ions produce charges on the surface of a micro-channel plate (MCP) detector, and a phosphor screen converts these charges to a visual image of the incident velocity distribution and registers the image on a CCD detector.

Yau, A. W.; King, P.; Amerl, P. V.

2006-12-01

241

Method for uniformly distributing carbon flakes in a positive electrode, the electrode made thereby and compositions  

DOEpatents

A positive electrode for a secondary electrochemical cell wherein an electrically conductive current collector is in electrical contact with a particulate mixture of gray cast iron and an alkali metal sulfide and an electrolyte including alkali metal halides or alkaline earth metal halides. Also present may be a transition metal sulfide and graphite flakes from the conversion of gray cast iron to iron sulfide. Also disclosed is a method of distributing carbon flakes in a cell wherein there is formed an electrochemical cell of a positive electrode structure of the type described and a suitable electrolyte and a second electrode containing a material capable of alloying with alkali metal ions. The cell is connected to a source of electrical potential to electrochemically convert gray cast iron to an iron sulfide and uniformly to distribute carbon flakes formerly in the gray cast iron throughout the positive electrode while forming an alkali metal alloy in the negative electrode. Also disclosed are compositions useful in preparing positive electrodes.

Mrazek, Franklin C. (Hickory Hills, IL); Smaga, John A. (Lemont, IL); Battles, James E. (Oak Forest, IL)

1983-01-01

242

Archaeal assemblages inhabiting temperate mixed forest soil fluctuate in taxon composition and spatial distribution over time.  

PubMed

This study explored the persistence and spatial distribution of a diverse Archaeal assemblage inhabiting a temperate mixed forest ecosystem. Persistence under native conditions was measured from 2001 to 2010, 2011, and 2012 by comparison of 16S rRNA gene clone libraries. The Archaeal assemblages at each of these time points were found to be significantly different (AMOVA, P < 0.01), and the nature of this difference was dependent on taxonomic rank. For example, the cosmopolitan genus g_Ca. Nitrososphaera (I.1b) was detected at all time points, but within this taxon the abundance of s_SCA1145, s_SCA1170, and s_Ca. N. gargensis fluctuated over time. In addition, spatial heterogeneity (patchiness) was measured at these time points using 1D TRFLP-SSCP fingerprinting to screen soil samples covering multiple spatial scales. This included soil collected from small volumes of 3 cubic centimeters to larger scales-over a surface area of 50?m(2), plots located 1.3?km apart, and a separate locality 23?km away. The spatial distribution of Archaea in these samples changed over time, and while g_Ca. Nitrososphaera (I.1b) was dominant over larger scales, patches were found at smaller scales that were dominated by other taxa. This study measured the degree of change for Archaeal taxon composition and patchiness over time in temperate mixed forest soil. PMID:23983618

Swanson, Colby A; Sliwinski, Marek K

2013-01-01

243

Analysis of composition, distribution and origin of hexachlorocyclohexane residues in agricultural soils from NW Spain.  

PubMed

Concentrations of the isomers of the organochlorine pesticide hexachlorocyclohexane (HCH) were determined in 252 surface soil samples collected within a sampling network covering agricultural areas in Galicia (NW Spain). The concentration of total HCH (sum of ?+?+?+?) ranged between 4 and 2305ngg(-)¹ (dry weight), with the ?-HCH and ?-HCH isomers predominating (<1-1404ngg(-)¹ and <1-569ngg(-)¹, respectively). The distribution of the pesticide residues was very heterogeneous, with the largest concentrations present in one of the studied areas (the province of A Coruña). The distribution of HCH was not found to be related to any soil property (organic matter, pH, clays, and metals). Multivariate statistical analysis of the data revealed that three populations of samples with a defined composition of HCH, can be related to the source of HCH: technical HCH (?/?>3), lindane (99% ?-HCH), or both. The existence of a third population consisting almost exclusively of ?-HCH suggests that background contamination of anthropogenic origin dates from several decades ago. The detailed analysis of these populations enabled the possible temporal scale of the application of these pesticides to be deduced. PMID:20810148

Calvelo Pereira, R; Monterroso Martínez, M C; Martínez Cortízas, A; Macías, F

2010-10-15

244

Composition and distribution of selected munnopsid genera (Crustacea, Isopoda, Asellota) in Icelandic waters  

NASA Astrophysics Data System (ADS)

The Greenland-Scotland Ridge (GSR) is a major topographic feature, extending from Greenland to Scotland. It constrains the water exchange between the northernmost North Atlantic Ocean and the Greenland, Iceland and Norwegian Seas (GIN Seas) and thus forms a potential barrier for faunal exchange from the Arctic to the North Atlantic (and vice versa). Recently an increase in Atlantic water inflow has been observed, leading to changes in physical parameters (i.e. temperature and salinity), which may have an impact on the resident fauna. In this study, we analyzed the composition and distribution of six selected genera of the isopod family Munnopsidae (Crustacea) occurring north and south of the GSR. We examined 82 epibenthic sledge samples and 26 additional sub-samples taken in the course of the Benthic Invertebrates of Icelandic Waters (BIOICE) and Icelandic Marine Animals: Genetics and Ecology (IceAGE) projects, respectively, covering a total depth range from 103 to 2752 m depth. Overall, 58 of the evaluated stations originated in the area north of the GSR, while the remaining 50 samples were collected south of the ridge. In total, 10517 individuals could be assigned to 15 species, most belonging to the genus EurycopeSars, 1864. Due to the presence of the GSR as well as differences in the environment, we expected significant dissimilarities in faunal composition between the two study areas. However, most species (8) occurred on both sides of the ridge, while four species were restricted to the region north of Iceland, and three to the region south of the ridge. Depth (or factors related to depth) appeared to be the most important factor in driving distributional patterns of the studied species. Temperature was also an important driver, but not to the same extent as depth. On the contrary, salinity and sediment type did not have much influence on munnopsid distribution patterns. Hence, the presence of the ridge does not restrict faunal exchange between the northern North Atlantic Ocean and GIN Seas for most of the investigated species, which may be explained by the good swimming abilities and the ecological flexibility of these munnopsid species.

Schnurr, Sarah; Brandt, Angelika; Brix, Saskia; Fiorentino, Dario; Malyutina, Marina; Svavarsson, Jörundur

2014-02-01

245

MinSORTING: an Excel macro for modelling sediment composition and grain-size distribution  

NASA Astrophysics Data System (ADS)

Detrital mineral analyses are gaining increasing attention in the geosciences as new single-grain analytical techniques are constantly improving their resolution, and consequently widening their range of application, including sedimentary petrology, tectonic geomorphology and archaeology (Mange and Wright, 2007; von Eynatten and Dunkl, 2012). We present here MinSORTING, a new tool to quickly predict the size distribution of various minerals and rock fragments in detrital sediments, based on the physical laws that control sedimentation by tractive wind or water currents (Garzanti et al., 2008). The input values requested by the software are the sediment mean size, sorting, fluid type (seawater, freshwater, air) and standard sediment composition chosen from a given array including nine diverse tectonic settings. MinSORTING calculates the bulk sediment density and the settling velocity. The mean size of each single detrital component, assumed as lognormally-distributed, is calculated from its characteristic size-shift with respect to bulk sediment mean size, dependent in turn on its density and shape. The final output of MinSORTING is the distribution of each single detrital mineral in each size classes (at the chosen 0.25, 0.5 or 1 phi intervals). This allows geochronolgists to select the most suitable grain size of sediment to be sampled in the field, as well as the most representative size-window for analysis. Also, MinSORTING provides an estimate of the volume/weight of the fractions not considered in both sizes finer and coarser than the selected size-window. A beta version of the software is available upon request from: alberto.resentini@unimib.it Mange, M., and Wright, D. (eds), 2007. Heavy minerals in use. Developments in Sedimentology Series, 58. Elsevier, Amsterdam. Garzanti, E., Andò, S., Vezzoli, G., 2008. Settling-equivalence of detrital minerals and grain-size dependence of sediment composition. Earth and Planetary Science Letters 273, 138-151. von Eynatten, H., and Dunkl, I., 2012. Assessing the sediment factory: The role of single grain analysis. Earth Sciences Reviews, 115, 97-120.

Resentini, Alberto; Malusà, Marco G.; Garzanti, Eduardo

2013-04-01

246

The Role of Distribution Infrastructure and Equipment in the Life-cycle Air Emissions of Liquid Transportation Fuels  

NASA Astrophysics Data System (ADS)

Production of fuel ethanol in the United States has increased ten-fold since 1993, largely as a result of government programs motivated by goals to improve domestic energy security, economic development, and environmental impacts. Over the next decade, the growth of and eventually the total production of second generation cellulosic biofuels is projected to exceed first generation (e.g., corn-based) biofuels, which will require continued expansion of infrastructure for producing and distributing ethanol and perhaps other biofuels. In addition to identifying potential differences in tailpipe emissions from vehicles operating with ethanol-blended or ethanol-free gasoline, environmental comparison of ethanol to petroleum fuels requires a comprehensive accounting of life-cycle environmental effects. Hundreds of published studies evaluate the life-cycle emissions from biofuels and petroleum, but the operation and maintenance of storage, handling, and distribution infrastructure and equipment for fuels and fuel feedstocks had not been adequately addressed. Little attention has been paid to estimating and minimizing emissions from these complex systems, presumably because they are believed to contribute a small fraction of total emissions for petroleum and first generation biofuels. This research aims to quantify the environmental impacts associated with the major components of fuel distribution infrastructure, and the impacts that will be introduced by expanding the parallel infrastructure needed to accommodate more biofuels in our existing systems. First, the components used in handling, storing, and transporting feedstocks and fuels are physically characterized by typical operating throughput, utilization, and lifespan. US-specific life-cycle GHG emission and water withdrawal factors are developed for each major distribution chain activity by applying a hybrid life-cycle assessment methodology to the manufacturing, construction, maintenance and operation of each component. In order to apply the new emission factors to policy-relevant scenarios, a projection is made for the fleet inventory of infrastructure components necessary to distribute 21 billion gallons of ethanol (the 2022 federal mandate for advanced biofuels under the Energy Independence and Security Act of 2007) derived entirely from Miscanthus grass, for comparison to the baseline petroleum system. Due to geographic, physical and chemical properties of biomass and alcohols, the distribution system for Miscanthus-based ethanol is more capital- and energy-intensive than petroleum per unit of fuel energy delivered. The transportation of biofuels away from producer regions poses environmental, health, and economic trade-offs that are herein evaluated using a simplified national distribution network model. In just the last ten years, ethanol transportation within the contiguous United States is estimated to have increased more than ten-fold in total t-km as ethanol has increasingly been transported away from Midwest producers due to air quality regulations pertaining to gasoline, renewable fuel mandates, and the 10% blending limit (i.e., the E10 blend wall). From 2004 to 2009, approximately 10 billion t-km of ethanol transportation are estimated to have taken place annually for reasons other than the E10 blend wall, leading to annual freight costs greater than $240 million and more than 300,000 tonnes of CO2-e emissions and significant emissions of criteria air pollutants from the combustion of more than 90 million liters of diesel. Although emissions from distribution activities are small when normalized to each unit of fuel, they are large in scale. Archetypal fuel distribution routes by rail and by truck are created to evaluate the significance of mode choice and route location on the severity of public health impacts from locomotive and truck emissions, by calculating the average PM2.5 pollution intake fraction along each route. Exposure to pollution resulting from trucking is found to be approximately twice as harmful as rail (while trucking is five times more ene

Strogen, Bret Michael

247

Unequally Distributed Psychological Assets: Are There Social Disparities in Optimism, Life Satisfaction, and Positive Affect?  

PubMed Central

Socioeconomic status is associated with health disparities, but underlying psychosocial mechanisms have not been fully identified. Dispositional optimism may be a psychosocial process linking socioeconomic status with health. We hypothesized that lower optimism would be associated with greater social disadvantage and poorer social mobility. We also investigated whether life satisfaction and positive affect showed similar patterns. Participants from the Midlife in the United States study self-reported their optimism, satisfaction, positive affect, and socioeconomic status (gender, race/ethnicity, education, occupational class and prestige, income). Social disparities in optimism were evident. Optimistic individuals tended to be white and highly educated, had an educated parent, belonged to higher occupational classes with more prestige, and had higher incomes. Findings were generally similar for satisfaction, but not positive affect. Greater optimism and satisfaction were also associated with educational achievement across generations. Optimism and life satisfaction are consistently linked with socioeconomic advantage and may be one conduit by which social disparities influence health. PMID:25671665

Boehm, Julia K.; Chen, Ying; Williams, David R.; Ryff, Carol; Kubzansky, Laura D.

2015-01-01

248

In situ formation by laser cladding of a TiC composite coating with a gradient distribution  

Microsoft Academic Search

An in situ method was developed to produce an Ni alloy composite coating reinforced by in situ reacted TiC particles with a gradient distribution, using one-step laser cladding with a pre-placed powder mixture on a 5CrMnMo steel substrate. Dispersed and ultra-fine TiC particles were formed in situ in the coating. Most of the TiC particles, with a marked gradient distribution,

Xiaolei Wu

1999-01-01

249

Vertical distributions of the early life stages of walleye pollock (Theragra chalcogramma) in the Southeastern Bering Sea  

NASA Astrophysics Data System (ADS)

The present study examines vertical distributions of the early life stages of walleye pollock (Theragra chalcogramma) in the Southeastern Bering Sea to assess ontogenetic and diel vertical migration in relation to development and habitat. Walleye pollock demonstrated a decrease in the depth of occurrence following hatching, indicating an ontogenetic change in vertical distribution. Eggs occurred deepest in the water column and early juveniles occurred shallowest. Vertical distributions were related to the date of collection, water column depth, and thermocline depth. Non-feeding stages (eggs and yolksac larvae, <4.5 mm standard length [SL]) did not exhibit diel vertical migration. Feeding larvae exhibited diel vertical migration, although patterns varied between two feeding stages. Preflexion stage larvae (4.5-9.9 mm SL) were concentrated between 10 and 20 m during the day and deeper at night. Postflexion stage larvae (flexion and postflexion, 10.0-24.5 mm SL) underwent regular diel migrations (0-20 m, night; 10-40 m, day). Low sample sizes limited our ability to assess diel vertical migration in early juveniles, but this stage tends to occur in the upper 20 m of the water column, regardless of time of day. These results suggest that vertical distributions and diel migration potentially are driven by prey availability at sufficient light levels for preflexion larvae to feed and a trade-off between prey access and predation risk for postflexion larvae. Vertical distributions of eggs and preflexion larvae varied with habitat examined (on the continental shelf versus over the continental slope). Vertical distributions of walleye pollock eggs, yolksac larvae, and preflexion larvae in the Bering Sea are different from distributions in other ecosystems, which can impact transport and modeling efforts.

Smart, T. I.; Siddon, E. C.; Duffy-Anderson, J. T.

2013-10-01

250

[Composition, abundance and distribution of populations of commercially important gastropods in La Guajira, Colombian Caribbean].  

PubMed

In the continental Colombian Caribbean the conch resource exploitation and the status of snails populations has been poorly studied, which are reflected in the lack of fisheries management. This study assesses composition, population density and distribution of the gastropods species that make conch resource in La Guajira region. Underwater visual censuses for snails were performed between September-November 2009 in 145100x4m (400m2) transects, spanning a total area of 56920m2 between Riohacha and Cabo de la Vela. The study was complemented with the evaluation of composition, abundance and size of gastropods conch found in the discarded-by-fishermen shell mounds in 13 beaches. In October 2010 another 40 transects were evaluated (16 000 m2) from the Southern of Riohacha to the Camarones village (La Guajira). We found a total of 9911 snails belonging to 12 species, the most abundant being Strombus pugilis with 8 912 individuals and an average density of 1 538.4 +/- 3 662.6 ind./ha, followed by Vasum muricatum with 374 individuals and an average density of 51.8 +/- 91.2 ind./ha. Calculating the importance value index (IVI) for both living organisms as the empty shells on beaches, shows that Turbinella angulata is the most used species by artisanal fishermen in the region. Cassis madagascariensis and Cassis tuberosa are also important snail resources in the region (as suggested by the number of empty shells found in beaches), but its densities were low. Strombus gigas, with only three living organisms found in the area, presented the lowest abundance ever found in the Colombian Caribbean (0.52 +/- 3.6 ind./ha), showing that queen conch population in La Guajira cannot support commercial exploitation. The abundance of discarded S. gigas shells on beaches suggests resource exploitation in the recent past. Results remarks the urgency of implementing management plans for snail fisheries in the region. PMID:23885583

Nieto-Bernal, Ramón; Luis, Chasqui; Rodriguez, Angélica María; Castro, Erick; Gil-Agudelo, Diego L

2013-06-01

251

Spatial distribution and cellular composition of adult brain proliferative zones in the teleost, Gymnotus omarorum.  

PubMed

Proliferation of stem/progenitor cells during development provides for the generation of mature cell types in the CNS. While adult brain proliferation is highly restricted in the mammals, it is widespread in teleosts. The extent of adult neural proliferation in the weakly electric fish, Gymnotus omarorum has not yet been described. To address this, we used double thymidine analog pulse-chase labeling of proliferating cells to identify brain proliferation zones, characterize their cellular composition, and analyze the fate of newborn cells in adult G. omarorum. Short thymidine analog chase periods revealed the ubiquitous distribution of adult brain proliferation, similar to other teleosts, particularly Apteronotus leptorhynchus. Proliferating cells were abundant at the ventricular-subventricular lining of the ventricular-cisternal system, adjacent to the telencephalic subpallium, the diencephalic preoptic region and hypothalamus, and the mesencephalic tectum opticum and torus semicircularis. Extraventricular proliferation zones, located distant from the ventricular-cisternal system surface, were found in all divisions of the rombencephalic cerebellum. We also report a new adult proliferation zone at the caudal-lateral border of the electrosensory lateral line lobe. All proliferation zones showed a heterogeneous cellular composition. The use of short (24 h) and long (30 day) chase periods revealed abundant fast cycling cells (potentially intermediate amplifiers), sparse slow cycling (potentially stem) cells, cells that appear to have entered a quiescent state, and cells that might correspond to migrating newborn neural cells. Their abundance and migration distance differed among proliferation zones: greater numbers and longer range and/or pace of migrating cells were associated with subpallial and cerebellar proliferation zones. PMID:25249943

Olivera-Pasilio, Valentina; Peterson, Daniel A; Castelló, María E

2014-01-01

252

Spatial distribution and cellular composition of adult brain proliferative zones in the teleost, Gymnotus omarorum  

PubMed Central

Proliferation of stem/progenitor cells during development provides for the generation of mature cell types in the CNS. While adult brain proliferation is highly restricted in the mammals, it is widespread in teleosts. The extent of adult neural proliferation in the weakly electric fish, Gymnotus omarorum has not yet been described. To address this, we used double thymidine analog pulse-chase labeling of proliferating cells to identify brain proliferation zones, characterize their cellular composition, and analyze the fate of newborn cells in adult G. omarorum. Short thymidine analog chase periods revealed the ubiquitous distribution of adult brain proliferation, similar to other teleosts, particularly Apteronotus leptorhynchus. Proliferating cells were abundant at the ventricular-subventricular lining of the ventricular-cisternal system, adjacent to the telencephalic subpallium, the diencephalic preoptic region and hypothalamus, and the mesencephalic tectum opticum and torus semicircularis. Extraventricular proliferation zones, located distant from the ventricular-cisternal system surface, were found in all divisions of the rombencephalic cerebellum. We also report a new adult proliferation zone at the caudal-lateral border of the electrosensory lateral line lobe. All proliferation zones showed a heterogeneous cellular composition. The use of short (24 h) and long (30 day) chase periods revealed abundant fast cycling cells (potentially intermediate amplifiers), sparse slow cycling (potentially stem) cells, cells that appear to have entered a quiescent state, and cells that might correspond to migrating newborn neural cells. Their abundance and migration distance differed among proliferation zones: greater numbers and longer range and/or pace of migrating cells were associated with subpallial and cerebellar proliferation zones. PMID:25249943

Olivera-Pasilio, Valentina; Peterson, Daniel A.; Castelló, María E.

2014-01-01

253

Application of composite flow laws to grain size distributions derived from polar ice cores  

NASA Astrophysics Data System (ADS)

Apart from evaluating the crystallographic orientation, focus of microstructural analysis of natural ice during the last decades has been to create depth-profiles of mean grain size. Several ice flow models incorporated mean grain size as a variable. Although such a mean value may coincide well with the size of a large proportion of the grains, smaller/larger grains are effectively ignored. These smaller/larger grains, however, may affect the ice flow modeling. Variability in grain size is observed on centimeter, meter and kilometer scale along deep polar ice cores. Composite flow laws allow considering the effect of this variability on rheology, by weighing the contribution of grain-size-sensitive (GSS, diffusion/grain boundary sliding) and grain-size-insensitive (GSI, dislocation) creep mechanisms taking the full grain size distribution into account [1]. Extraction of hundreds of grain size distributions for different depths along an ice core has become relatively easy by automatic image processing techniques [2]. The shallow ice approximation is widely adopted in ice sheet modeling and approaches the full-Stokes solution for small ratios of vertical to horizontal characteristic dimensions. In this approximation shear stress in the vertical plain dominates the strain. This assumption is not applicable at ice divides or dome structures, where most deep ice core drilling sites are located. Within the upper two thirds of the ice column longitudinal stresses are not negligible and ice deformation is dominated by vertical strain. The Dansgaard-Johnsen model [3] predicts a dominating, constant vertical strain rate for the upper two thirds of the ice sheet, whereas in the lower ice column vertical shear becomes the main driver for ice deformation. We derived vertical strain rates from the upper NEEM ice core (North-West Greenland) and compared them to classical estimates of strain rates at the NEEM site. Assuming intervals of constant accumulation rates, we found a variation of vertical strain rates by a factor 2-3 in the upper ice column. We discuss the current applicability of composite flow laws to grain size distributions extracted from ice cores drilled at sites where the flow direction rotates by 90 degrees with depth (i.e. ice divide). An interesting finding is that a transition to a glacial period in future would be associated with a decrease in vertical strain rate (due to a reduced accumulation rate) and an increase of the frequency of small grains (due to an enhanced impurity content). Composite flow laws assign an enhanced contribution of GSS creep to this transition. It is currently unclear which factor would have a greater influence. [1] Herwegh et al., 2005, J. Struct. Geol., 27, 503-521 [2] T. Binder et al., 2013, J. Microsc., 250, 130-141 [3] W. Dansgaard & S.J. Johnsen, 1969, J. Glaciol., 8, 215-223

Binder, Tobias; de Bresser, Hans; Jansen, Daniela; Weikusat, Ilka; Garbe, Christoph; Kipfstuhl, Sepp

2014-05-01

254

Composite resin reinforced with pre-tensioned fibers: a three-dimensional finite element study on stress distribution.  

PubMed

Pre-tensioned construction material is utilized in engineering applications of high strength demands. The purpose of this study was to evaluate the effect of the pre-tensioning fibers of fiber-reinforced composite (FRC) using three-dimensional finite element (FE) analysis. The 3D FE models of particulate composite resin (CR), FRC and composite resin reinforced with pre-tensioned fibers (PRE-T-FRC) were constructed. The uniaxial three-point bending test was simulated using FE analysis to calculate the principal stress distribution. In the FRC and PRE-T-FRC, stresses were higher than CR, and they were located in the fiber. However, the maximum principal stress value at the composite of PRE-T-FRC was lower than the FRC and CR. Composite resin reinforced with pre-tensioned fibers was advantageous for stress distribution and lowering the stress at the composite itself. Experimental studies on physical properties of pre-tensioned FRC are encouraged to be conducted. PMID:22371018

Jie, Lin; Shinya, Akikazu; Lassila, Lippo V J; Vallittu, Pekka K

2013-01-01

255

The plankton community in Norwegian coastal waters—abundance, composition, spatial distribution and diel variation  

NASA Astrophysics Data System (ADS)

The purpose of the present study was to explore the composition and variation of the pico-, nano- and micro-plankton communities in Norwegian coastal waters and Skagerrak, and the co-occurrence of bacteria and viruses. Samples were collected along three cruise transects from Jæren, Lista and Oksøy on the south coast of Norway and into the North Sea and Skagerrak. We also followed a drifting buoy for 55 h in Skagerrak in order to observe diel variations. Satellite ocean color images (SeaWiFS) of the chlorophyll a (chl a) distribution compared favorably to in situ measurements in open waters, while closer to the shore remote sensing chl a data was overestimated compared to the in situ data. Using light microscopy, we identified 49 micro- and 15 nanoplankton sized phototrophic forms as well as 40 micro- and 12 nanoplankton sized heterotrophic forms. The only picoeukaryote (0.2-2.0 ?m) we identified was Resultor micron (Pedinophyceae ). Along the transects a significant variation in the distribution and abundance of different plankton forms were observed, with Synechococcus spp and autotrophic picoeukaryotes as the most notable examples. There was no correlation between viruses and chl a, but between viruses and bacteria, and between viruses and some of the phytoplankton groups, especially the picoeukaryotes. Moreover, there was a negative correlation between nutrients and small viruses (Low Fluorescent Viruses) but a positive correlation between nutrients and large viruses (High Fluorescent Viruses). The abundance of autotrophic picoplankton, bacteria and viruses showed a diel variation in surface waters with higher values around noon and late at night and lower values in the evening. Synechococcus spp were found at 20 m depth 25-45 nautical miles from shore apparently forming a bloom that stretched out for more than 100 nautical miles from Skagerrak and up the south west coast of Norway. The different methods used for assessing abundance, distribution and diversity of microorganisms yielded complementary information about the plankton community. Flow cytometry enabled us to map the distribution of the smaller phytoplankton forms, bacteria and viruses in more detail than has been possible before but detection and quantification of specific forms (genus or species) still requires taxonomic skills, molecular analysis or both.

Bratbak, Gunnar; Jacquet, Stéphan; Larsen, Aud; Pettersson, Lasse H.; Sazhin, Andrey F.; Thyrhaug, Runar

2011-09-01

256

Resonance line shape, strain and electric potential distributions of composite magnetoelectric sensors  

NASA Astrophysics Data System (ADS)

Multiferroic composite magnetoelectric (ME) sensors are based on the elastic coupling of a magnetostrictive phase and a piezoelectric phase. A deformation of the magnetostrictive phase causes strain in the piezoelectric phase and thus an induced voltage. Such sensors may be applied both for static as well as for dynamic magnetic field measurements. Particularly high sensitivities are achieved for operation at a mechanical resonance. Here, the resonance line shape of layered (2-2 composite) cantilever ME sensors at the first bending-mode resonance is investigated theoretically. Finite element method (FEM) simulations using a linear material model reveal an asymmetric resonance profile and a zero-response frequency for the ME coefficient. Frequency-dependent strain and electric potential distributions inside the magnetoelectric composite are studied for the case of a magnetostrictive-piezoelectric bilayer. It is demonstrated that a positive or a negative voltage may be induced across the piezoelectric layer depending on the position of the neutral plane. The frequency-dependent induced electric potential is investigated for structured cantilevers that exhibit magnetostriction only at specific positions. For static operation an induced voltage is obtained locally at positions with magnetostriction. In addition to this direct effect a resonance-assisted effect is observed for dynamic operation. Magnetostriction in a limited area of the cantilever causes a global vibration of the cantilever. Thus, deformation of the piezoelectric layer and an induced electric potential also occur in areas of the cantilever without magnetostriction. The direct and the resonance-assisted pathway may induce voltages of equal or of opposite sign. The net induced voltage results from the superposition of the two effects. As the resonance-assisted induced voltage changes sign upon passing the resonance frequency, while the direct component is constant, an asymmetric line shape and a zero-response frequency result for the ME coefficient. The zero-response oscillator frequency may be below or above the resonance frequency. The calculated FEM resonance line shapes are fitted successfully to a superposition function of a constant component and a resonant component with a Lorentzian line shape. Equivalence of the superposition function line shape to a Fano resonance profile is derived for frequencies around the resonance. Fano resonances are ubiquitous in physics occurring due to the constructive and destructive quantum interference of two different scattering pathways, e.g., for photons or electrons. The superposition fit parameters describing the resonance line shape are calculated as a function of the cantilever substrate thickness. The inclusion of loss by adjustment of the damping parameter is discussed. The results derived here also are applicable to higher order modes or longitudinal resonance modes.

Gerken, Martina

2013-06-01

257

Effect of sulfate on the transformation of corrosion scale composition and bacterial community in cast iron water distribution pipes  

EPA Science Inventory

The stability of iron corrosion products and the bacterial composition of biofilm in drinking water distribution systems (DWDS) could have great impact on the water safety at the consumer ends. In this work, pipe loops were setup to investigate the transformation characteristics ...

258

Distribution of REE between clinopyroxene and basaltic melt along a mantle adiabat: Effects of major element composition, water, and temperature  

Microsoft Academic Search

The distribution of REE between clinopyroxene (cpx) and basaltic melt is important in deciphering the processes of mantle melting. Most models for mantle melting assume constant mineral-melt partition coefficient (D) for trace elements, even though partitioning experiments have demonstrated that D depends on pressure (P), temperature (T), and compositions of mineral and melt. In general, DREE from a given cpx-melt

C. Sun; Y. Liang

2010-01-01

259

Spatial variation in life-history trade-offs results in an ideal free distribution in Black Brant Geese.  

PubMed

Ideal free distribution theory predicts that individuals distribute themselves so fitness is equal among patches. In this paper we evaluate all components of adult fitness to assess the hypothesis that individuals distribute themselves among seven brood-rearing areas so that trade-offs among different life history traits result in equal mean fitness among individuals using different areas. We used estimates of vital rates (clutch size, nest survival, pre-fledging survival, post-fledging survival, juvenile survival, and breeding probability) to estimate brood-rearing-area-specific per capita recruitment rates and survival for adult females. We summed brood-rearing-area-specific per capita recruitment and adult survival to calculate brood-rearing-area-specific estimates of lambda. We found little variation in lambda among brood-rearing areas and lifetime fitness implications of changing brood-rearing area were negligible (< 1% brood-rearing area mean fitness). We conclude that adult female Black Brant distribute themselves in an ideal free manner, resulting in equal fitness among females using these areas. PMID:25000763

Nicolai, Christopher A; Sedinger, James S; Ward, David H; Boyd, W Sean

2014-05-01

260

Efficient estimation of the distribution of time to composite endpoint when some endpoints are only partially observed  

PubMed Central

Two common features of clinical trials, and other longitudinal studies, are (1) a primary interest in composite endpoints, and (2) the problem of subjects withdrawing prematurely from the study. In some settings, withdrawal may only affect observation of some components of the composite endpoint, for example when another component is death, information on which may be available from a national registry. In this paper, we use the theory of augmented inverse probability weighted estimating equations to show how such partial information on the composite endpoint for subjects who withdraw from the study can be incorporated in a principled way into the estimation of the distribution of time to composite endpoint, typically leading to increased efficiency without relying on additional assumptions above those that would be made by standard approaches. We describe our proposed approach theoretically, and demonstrate its properties in a simulation study. PMID:23722304

Daniel, Rhian M.; Tsiatis, Anastasios A.

2014-01-01

261

The influence of reinforcement particle size distribution on the mechanical behavior of a stainless steel/tin composite  

SciTech Connect

A stainless steel-based composite reinforced with TiN particles has been developed for potential applications in industry. The results show that the compatibility between the matrix and reinforcement is good and the bonding between the two phases is strong and of the diffusion type. The ductility and toughness of the composites are lower than those of the matrix. The strengthening behavior of the composites, however, is not straightforward. It is also found that reinforcements that differ only in particle-size distribution can bring about a large change in the mechanical properties of the composites. It is believed that the microstructural change of the matrix after incorporating the reinforcement, together with the load-bearing effect of the reinforcement, gives rise to the results.

Liu, X.; Pagounis, E.; Hellman, J.; Lindroos, V.K.

2000-01-01

262

Strength distribution of reinforcing fibers in a Nicalon fiber/chemically vapor infiltrated silicon carbide matrix composite  

NASA Technical Reports Server (NTRS)

The strength distribution of fibers within a two-dimensional laminate ceramic/ceramic composite consisting of an eight harness satin weave of Nicalon continuous fiber within a chemically vapor infiltrated SiC matrix was determined from analysis of the fracture mirrors of the fibers. Comparison of the fiber strengths and the Weibull moduli with those for Nicalon fibers prior to incorporation into composites suggests that possible fiber damage may occur either during the weaving or during another stage of the composite manufacture. Observations also indicate that it is the higher-strength fibers which experience the greatest extent of fiber pullout and thus make a larger contribution to the overall composite toughness than do the weaker fibers.

Eckel, Andrew J.; Bradt, Richard C.

1989-01-01

263

Particle number concentration, size distribution and chemical composition during haze and photochemical smog episodes in Shanghai.  

PubMed

The aerosol number concentration and size distribution as well as size-resolved particle chemical composition were measured during haze and photochemical smog episodes in Shanghai in 2009. The number of haze days accounted for 43%, of which 30% was severe (visibility<2km) and moderate (2km?visibility<3km) haze, mainly distributed in winter and spring. The mean particle number concentration was about 17,000/cm(3) in haze, more than 2 times that in clean days. The greatest increase of particle number concentration was in 0.5-1?m and 1-10?m size fractions during haze events, about 17.78 times and 8.78 times those of clean days. The largest increase of particle number concentration was within 50-100nm and 100-200nm fractions during photochemical smog episodes, about 5.89 times and 4.29 times those of clean days. The particle volume concentration and surface concentration in haze, photochemical smog and clean days were 102, 49, 15?m(3)/cm(3) and 949, 649, 206?m(2)/cm(3), respectively. As haze events got more severe, the number concentration of particles smaller than 50nm decreased, but the particles of 50-200nm and 0.5-1?m increased. The diurnal variation of particle number concentration showed a bimodal pattern in haze days. All soluble ions were increased during haze events, of which NH4(+), SO4(2-) and NO3(-) increased greatly, followed by Na(+), K(+), Ca(2+) and Cl(-). These ions were very different in size-resolved particles during haze and photochemical smog episodes. PMID:25193840

Wang, Xuemei; Chen, Jianmin; Cheng, Tiantao; Zhang, Renyi; Wang, Xinming

2014-09-01

264

Carbon nanotube sensor thread for distributed strain and damage monitoring on IM7/977-3 composites  

NASA Astrophysics Data System (ADS)

Laminated composite materials are used in applications where light weight is a key requirement. However, minor delamination damage in composites can propagate and lead to the failure of components. Failure occurs because delamination reduces the local bending stiffness and increases bending stress, which leads to the propagation of damage and eventual failure. These failures may be avoided if the damage could be detected early and repaired. Although many damage detection methods have been investigated, none are in widespread use today to prevent the failure of composites. This paper describes the use of carbon nanotube sensor thread to monitor strain and damage in composite materials. Sensor thread was bonded onto an IM7-laminated composite coupon to measure surface strain in a quasi-static uniaxial tensile test. The sensor thread was calibrated against a strain gage, which was also mounted to the coupon. The sensor thread measured the average strain over the length of the sample and indicated when the strain exceeded a nominal safe level. Sensor thread was also bonded to the surface of laminated composite panels in different patterns and detected, located and partially characterized the damage caused by multiple impacts to the panel. The new findings in this paper can be summarized as; (1) carbon nanotube sensor thread was tested as a distributed sensor for the first time on IM7/977-3 composites; (2) the sensor thread was found to monitor strain and detect damage in the composites with a potential sensitivity down to the micro-crack level; (3) the sensor thread was barely visible on the composite and did not add significant mass or affect the integrity of the composite; (4) the data acquisition system developed was simple and reliable.

Song, Yi; Hehr, Adam; Shanov, Vesselin; Alvarez, Noe; Kienzle, Nicholas; Cummins, Joshua; Koester, Dave; Schulz, Mark

2014-07-01

265

The affine equivalence of local stress and displacement distributions in damaged composites and Batdorf's electric analog  

NASA Technical Reports Server (NTRS)

The composite solid/analog device affine equations are shown to be elastically and electrically material independent. Analog experimental solutions yield the stress and displacement fields of the composite solid for a wide range of physical variables.

Brunelle, E. J.

1984-01-01

266

Design, fabrication, and properties of 2-2 connectivity cement/polymer based piezoelectric composites with varied piezoelectric phase distribution  

NASA Astrophysics Data System (ADS)

The laminated 2-2 connectivity cement/polymer based piezoelectric composites with varied piezoelectric phase distribution were fabricated by employing Lead Zirconium Titanate ceramic as active phase, and mixture of cement powder, epoxy resin, and hardener as matrix phase with a mass proportion of 4:4:1. The dielectric, piezoelectric, and electromechanical coupling properties of the composites were studied. The composites with large total volume fraction of piezoelectric phase have large piezoelectric strain constant and relative permittivity, and the piezoelectric and dielectric properties of the composites are independent of the dimensional variations of the piezoelectric ceramic layer. The composites with small total volume fraction of piezoelectric phase have large piezoelectric voltage constant, but also large dielectric loss. The composite with gradually increased dimension of piezoelectric ceramic layer has the smallest dielectric loss, and that with the gradually increased dimension of matrix layer has the largest piezoelectric voltage constant. The novel piezoelectric composites show potential applications in fabricating ultrasonic transducers with varied surface vibration amplitude of the transducer.

Dongyu, Xu; Xin, Cheng; Banerjee, Sourav; Shifeng, Huang

2014-12-01

267

New Method for Determining the Elemental Composition and Distribution in Semiconductor Core-Shell Quantum Dots  

PubMed Central

In the biological sciences the use of core-shell quantum dots (QDs) has gained wide usage, but analytical challenges still exist for characterizing the QD structure. The application of energy-dispersive x-ray spectroscopy and x-ray photoelectron spectroscopy (XPS) to bulk materials is relatively straightforward, however, for meaningful applications of surface science techniques to multilayer nanoparticles requires novel modifications and analysis methods. To experimentally characterize the elemental composition and distribution in CdSe/CdS/ZnS QDs, we first develop a XPS signal subtraction technique capable of separating the overlapped selenium 3s (core) and sulfur 2s (shell) peaks (both peaks have binding energies near 230eV) with higher precision than is typically reported in the nanoparticle literature. This method is valid for any nanoparticle containing selenium and sulfur. Then we apply a correction formula to the XPS data and determine that the 2 nm stoichiometric CdSe core is surrounded by 2 CdS layers and a stoichimetric ZnS monolayer. These findings and the multi-approach methodology represent a significant advancement in the detailed surface science study of multi-layer nanoparticles. In agreement with recent surprising findings, the time-of-flight secondary mass spectrometry measurements suggest that the surface sites of the QDs used in this study are primarily covered with a mixture of octadecylphosphonic acid and trioctylphophine oxide. PMID:21226467

Zorn, Gilad; Dave, Shivang R.; Gao, Xiaohu; Castner, David G.

2011-01-01

268

Cosmopolitan distribution of the large composite microbial mat spirochete, Spirosymplokos deltaeiberi  

NASA Technical Reports Server (NTRS)

Inocula from organic-rich black muds immediately underlying intertidal laminated microbial mats dominated by Microcoleus chthonoplastes yielded large, variable diameter spirochetes. These unusual spirochetes, previously reported only from the Alfacs Peninsula at the delta of the Ebro river in northeast Spain, contain striking arrays of cytoplasmic granules packed into their protoplasmic cylinders. On several occasions, both in summer and winter, the huge spirochetes were recognized in samples from mats growing in the Sippewissett salt marsh at Woods Hole Massachusetts. They were also seen in similar samples from microbial mats at North Pond, Laguna Figueroa, Baja California Norte, Mexico. The identity of these spirochetes was confirmed by electron microscopy: number and disposition of flagella, composite structure, measurements of their distinctive cytoplasmic granules. The granules, larger, more conspicuous and present in addition to ribosomes, are hypothesized to contain ATPases. As culture conditions worsen, these spirochetes retract into membrane-bounded round bodies in which they form refractile inclusions. From morphology and behavior we conclude the North American spirochetes from both Atlantic and Pacific intertidal microbial mats are indistinguishable from those at the delta of the Ebro river. We conclude a cosmopolitan distribution for Spirosymplokos deltaeiberi.

Margulis, L.; Navarrete, A.; Sole, M.

1998-01-01

269

Distribution and size composition of the arctic lamprey Lethenteron camtschaticum in the North Pacific  

NASA Astrophysics Data System (ADS)

Results of the long-term study of the spatial and vertical distribution of the parasitic anadromous Arctic lamprey Lethenteron camtschaticum (Tilesius, 1811) (Petromyzontidae) in the North Pacific and data on its size composition are given. This species is most frequent in the northwestern Sea of Japan and the western Bering Sea. The maximum concentrations are noted in waters of southern Primorye, southwestern Sakhalin, the northwestern part of the Sea of Okhotsk, and the northern part of the Bering Sea, which is probably explained by the increased number of its victims, Pacific salmon. Near the bottom, Pacific lampreys are extremely few and are primarily encountered at depths less that 400 m, and in the Pelagic zone, in the 100-m layer. The catches have contained Arctic lampreys having a total length of 15-79 cm. The lampreys of several size groups in the catches may indicate that L. camtschaticum spends not less than four years in the sea. No relationship has been found between the body length and the capture depth. Analyzed are the relationships between the body length and weight and the body length and the condition factor. The seasonal dynamics of these indices are considered.

Orlov, A. M.; Baitalyuk, A. A.; Pelenev, D. V.

2014-03-01

270

Composition and distribution of bacteria in an operating rainwater harvesting tank.  

PubMed

In this study, we investigated the phylogenetic distribution of the bacteria present in an operating rainwater tank by denaturing gradient gel electrophoresis (DGGE), and compared the bacterial composition in rainwater and biofilm from the inlet and outlet of the tank. Seventeen species were identified, the DGGE profiles of which showed a clear difference between the planktonic bacterial community and the community in the biofilm. Most of the bacteria were closely related to fresh water, soil, and biofilm bacteria found in natural environments. The high proportion of Proteobacteria indicates the generally clean oligotrophic nature of the tank water. Biofilm formation is an advantage for bacteria that exist in oligotrophic environments. The groups identified in the biofilm, such as Sphingomonas, Bacillus, and Sphingophyxis, have been demonstrated to degrade certain contaminants and to act as bio-control agents. Thus, biofilm formation in rainwater tanks not only represents a survival strategy for bacteria, but also serves as a natural filter by removing contaminants and bacteria from rainwater. PMID:21508560

Kim, Mikyeong; Han, Mooyoung

2011-01-01

271

Spatiotemporal distribution and composition of phytoplankton assemblages in a coastal tropical lagoon: Chilika, India.  

PubMed

The Asia's largest lagoon, Chilika, is a shallow water estuary and a designated "Ramsar" site located in the east coast of India. The spatiotemporal diversity of phytoplankton based on the monthly sampling between July 2011 and June 2012 was investigated in relation to physicochemical variables of the surface water column from 13 stations. The salinity was minimum (average 9) during the monsoon which was primarily due to riverine discharge. As the season progressed towards post-monsoon, average salinity of the whole lagoon reached to 10 which further increased to 20 during pre-monsoon season. A total of 259 species of phytoplankton, mostly dominated by the Bacillariophyta (138 species) followed by Dinophyta (38 species), Chlorophyta (32 species), Cyanophyta (29 species), Euglenophyta (18 species), and Chrysophyta (4 species), were recorded in this study. Different ecological sectors of the lagoon (except the northern sector) were dominated by diatoms, while the northern sector due to its freshwater regime supported large population of euglenoids. Based on the multivariate ordination analysis, salinity regime and light availability played important role in determining the distribution, diversity, and composition of phytoplankton communities. Overall, this study documented a very high diversity of phytoplankton and highlighted the importance of taking extensive sampling in getting a clearer understanding of phytoplankton community structure in less-studied environments such as Chilika lagoon. PMID:25638055

Srichandan, Suchismita; Kim, Ji Yoon; Bhadury, Punyasloke; Barik, Saroja K; Muduli, Pradipta R; Samal, Rabindro N; Pattnaik, Ajit K; Rastogi, Gurdeep

2015-02-01

272

Composition, physiochemical properties, nitrogen fraction distribution, and amino acid profile of donkey milk.  

PubMed

This study investigated the changes in chemical composition, nitrogen fraction distribution, and AA profile of milk samples obtained during lactation from the Jiangyue breed of donkey in Northwest China. Results showed that donkey milk contained 9.53% total solids, 1.57% protein, 1.16% fat, 6.33% lactose, and 0.4% ash on average, which is more similar to mare and human milk than to the milk of other mammals. Throughout the lactation investigated, pH and density were constant, protein and ash content showed an apparent negative trend (an increase in lactose content during 120 d postpartum, followed by a decrease), fat content exhibited wide variability, and variations in the content and percentage of whey protein, casein, and AA were small. The casein to whey protein ratio of 52:37 was between the lower value of human milk and the higher value of cow milk. Sodium dodecyl sulfate-PAGE results demonstrated that donkey milk is rich in beta-lactoglobulin and lysozyme. The percentages of 8 essential AA in protein of donkey milk were 38.2%, higher than those of mare and cow milk; donkey milk also had higher levels of serine (6.2%), glutamic acid (22.8%), arginine (4.6%), and valine (6.5%) and a lower level of cystine (0.4%). PMID:17369203

Guo, H Y; Pang, K; Zhang, X Y; Zhao, L; Chen, S W; Dong, M L; Ren, F Z

2007-04-01

273

Effects of fiber spatial distribution and interphase on transverse damage in fiber-reinforced ceramic matrix composites  

NASA Astrophysics Data System (ADS)

The major objectives of this research were to study the effects of fiber spatial distribution and interphase thermo-mechanical properties on transverse damage initiation. The material model studied was a unidirectional, continuous fiber-reinforced composite. Radial matrix cracking and interfacial debonding at the fiber/matrix interface were of primary concern. With regards to the fiber spatial distribution, a reconstruction scheme was devised from the spatial descriptors of the actual material. In the reconstruction scheme, representative volume elements (RVEs) of transverse sections of the composite were developed and modeled within the framework of the finite element method (FEM). Two separate loading conditions were considered, uniaxial tension and thermal cooldown from a stress free state. Issues such as fiber spatial distribution within an RVE, RVE size and RVE boundary conditions were addressed.

Bulsara, Vatsal Narottamdas

1998-12-01

274

Structural Health Monitoring of Composite Materials Using Distributed Fiber Bragg Sensors  

NASA Technical Reports Server (NTRS)

Health monitoring of polymer matrix composite materials using fiber optic Bragg grating (FBG) sensors is accomplished using a tunable IR (infrared) laser via transmission mode. Results are presented from experiments of composite structures with FBG's embedded at various orientations, and surface measurements of various cryogenic composite vessels.

Grant, Joseph; Kual, Raj; Taylor, Scott; Jackson, Kurt V.; Myers, George; Wang, Y.; Sharma, A.; Burdine, Robert (Technical Monitor)

2002-01-01

275

Biology, Systematics, Life Cycle, and Distribution of Angiostrongylus cantonensis, the Cause of Rat Lungworm Disease  

PubMed Central

Angiostrongylus cantonensis is a metastrongyloid nematode in the family Angiostrongylidae. It is the cause of angiostrongyliasis (rat lungworm disease), which manifests as eosinophilic meningitis. First described in 1935 from rats in China, A. cantonensis was placed in the genus Parastrongylus in 1986, but most workers have not adopted this treatment. The taxonomy of A. cantonensis and related worms is largely based on adult morphology, notably of the male bursa. However, identification of infective third stage larvae is more difficult. The natural life cycle involves rats as the definitive host and snails or slugs as the intermediate host. Human infection, as accidental hosts, results in worms maturing in the brain, but dying there instead of moving back into the bloodstream, as in rats, thereby leading to eosinophilic meningitis. The disease is an emerging infectious disease; Angiostrongylus cantonensis continues to be reported in new regions beyond its native range. PMID:23901372

2013-01-01

276

The LifeWatch approach to the exploration of distributed species information  

PubMed Central

Abstract This paper introduces a new method of automatically extracting, integrating and presenting information regarding species from the most relevant online taxonomic resources. First, the information is extracted and joined using data wrappers and integration solutions. Then, an analytical tool is used to provide a visual representation of the data. The information is then integrated into a user friendly content management system. The proposal has been implemented using data from the Global Biodiversity Information Facility (GBIF), the Catalogue of Life (CoL), the World Register of Marine Species (WoRMS), the Integrated Taxonomic Information System (ITIS) and the Global Names Index (GNI). The approach improves data quality, avoiding taxonomic and nomenclature errors whilst increasing the availability and accessibility of the information. PMID:25589865

Fuentes, Daniel; Fiore, Nicola

2014-01-01

277

A method for determining oceanic particle size distributions and particle composition using scanning electron microscopy coupled with energy dispersive spectroscopy  

NASA Astrophysics Data System (ADS)

To understand the behavior of light scattered in seawater, it is necessary to know the size distribution of particles in seawater, as well as their composition (refractive index distribution) and complex shape. A method has been developed to determine marine PSDs and simultaneously characterize their chemical compositions by utilizing a scanning electron microscope (SEM) coupled with an energy dispersive spectrometer (EDS) and applying sophisticated image analysis techniques that minimized user bias including automatic image thresholding. The method was validated by verifying the PSD and chemical composition of Arizona test dust, which has a well-documented size distribution and chemical composition. PSDs of field samples collected from the coastal Long Island Sound and the remote South Pacific Ocean were also determined. Where applicable, PSDs agreed well overall with other PSD determining methods such as electroresistive counting and near-forward diffraction theory inversions. The method performed optimally when the particle mass on the filter was between 0.4mg and 1.0mg. With this in mind, measuring particle beam attenuation coefficient at 650nm (c650) can provide immediate feedback in the field to determine filter volumes for sample preparation.

Groundwater, Heather; Twardowski, Michael S.; Dierssen, Heidi M.; Sciandre, Antoine; Freeman, Scott A.

2010-06-01

278

Fatigue behavior and life prediction of a SiC/Ti-24Al-11Nb composite under isothermal conditions. Ph.D. Thesis  

NASA Technical Reports Server (NTRS)

Metal Matrix Composites (MMC) and Intermetallic Matrix Composites (IMC) were identified as potential material candidates for advanced aerospace applications. They are especially attractive for high temperature applications which require a low density material that maintains its structural integrity at elevated temperatures. High temperature fatigue resistance plays an important role in determining the structural integrity of the material. This study attempts to examine the relevance of test techniques, failure criterion, and life prediction as they pertain to an IMC material, specifically, unidirectional SiC fiber reinforced titanium aluminide. A series of strain and load controlled fatigue tests were conducted on unidirectional SiC/Ti-24Al-11Nb composite at 425 and 815 C. Several damage mechanism regimes were identified by using a strain-based representation of the data, Talreja's fatigue life diagram concept. Results of these tests were then used to address issues of test control modes, definition of failure, and testing techniques. Finally, a strain-based life prediction method was proposed for an IMC under tensile cyclic loadings at elevated temperatures.

Bartolotta, Paul A.

1991-01-01

279

Distribution and Composition of Particulate Organic Carbon along Oregon's Upwelling Zone  

NASA Astrophysics Data System (ADS)

Direct measurements of particulate organic carbon (POC) concentrations are needed to quantitatively understand the carbon cycle in Eastern Boundary ocean margins. However, in the past these measurements have been somewhat restricted due to the time-intensive nature of the sample collection and manual filtration procedures. To increase temporal and spatial coverage of POC distributions, we designed and built a semi-automated filtration system (SAFS) linked to a towed profiling vehicle with pumping capabilities. This set up allowed us to perform filtrations at high frequency and measure POC concentrations throughout the entire water column along several shore-perpendicular transects across the Oregon shelf. We combined these data with in-situ optical measurements (i.e., beam transmission, chlorophyll fluorescence and optical backscatter) and characterized several distinct pools of particles within different geographical and depth regions of the water column off the central Oregon Coast. For example, early in the upwelling season (May 2009) surface waters were characterized by elevated POC concentrations (> 20 uM) and displayed significant patchiness with areas of very high concentrations (> 80 uM). Below 50 m POC concentrations were uniformly low (< 20 uM), even within the benthic boundary layer (BBL). Beam transmission-normalized compositions indicate surface particles were be enriched in POC and chlorophyll and displayed low backscatter relative to particles within the BBL. In contrast, mid-water particles were carbon and chlorophyll rich but had elevated backscatter properties that approached those of particles in the BBL. These compositions indicate phytoplankton contributed predominantly to the particle pool in both surface and mid-depth waters, with the main differences between them being overall concentration (much higher at the surface) and particle size (much smaller at the mid-depths). The lack of fresh algal materials in the BBL suggests labile OM transport to the deeper regions of the water column had not occurred at this early stage in the upwelling season. The elevated backscatter properties of BBL particles are consistent with high lithogenic content and resuspended seabed provenance.

Goni, M. A.; Holser, R. R.; Hales, B. R.; Succes Team

2010-12-01

280

Bayesian statistical approaches to compositional analyses of transgenic crops 2. Application and validation of informative prior distributions.  

PubMed

Bayesian approaches to evaluation of crop composition data allow simpler interpretations than traditional statistical significance tests. An important advantage of Bayesian approaches is that they allow formal incorporation of previously generated data through prior distributions in the analysis steps. This manuscript describes key steps to ensure meaningful and transparent selection and application of informative prior distributions. These include (i) review of previous data in the scientific literature to form the prior distributions, (ii) proper statistical model specification and documentation, (iii) graphical analyses to evaluate the fit of the statistical model to new study data, and (iv) sensitivity analyses to evaluate the robustness of results to the choice of prior distribution. The validity of the prior distribution for any crop component is critical to acceptance of Bayesian approaches to compositional analyses and would be essential for studies conducted in a regulatory setting. Selection and validation of prior distributions for three soybean isoflavones (daidzein, genistein, and glycitein) and two oligosaccharides (raffinose and stachyose) are illustrated in a comparative assessment of data obtained on GM and non-GM soybean seed harvested from replicated field sites at multiple locations in the US during the 2009 growing season. PMID:23261475

Harrison, Jay M; Breeze, Matthew L; Berman, Kristina H; Harrigan, George G

2013-03-01

281

The role of microstructure and phase distribution in the failure mechanisms and life prediction model for PSZ coatings  

NASA Technical Reports Server (NTRS)

Partially Stabilized Zirconia (PSZ) may become widely used for Thermal Barrier Coatings (TBC). Failure of these coatings can occur due to thermal fatigue in oxidizing atmospheres. The failure is due to the strains that develop due to thermal gradients, differences in thermal expansion coefficients, and oxidation of the bond coating. The role of microstructure and the cubic, tetragonal, and monoclinic phase distribution in the strain development and subsequent failure will be discussed. An X-ray diffraction technique for accurate determination of the fraction of each phase in PSZ will be applied to understanding the phase transformations and strain development. These results will be discussed in terms of developing a model for life prediction in PSZ coatings during thermal cycling.

Sisson, R. D., Jr.; Sone, Ichiro; Biederman, R. R.

1985-01-01

282

Within-twig leaf distribution patterns differ among plant life-forms in a subtropical Chinese forest.  

PubMed

In theory, plants can alter the distribution of leaves along the lengths of their twigs (i.e., within-twig leaf distribution patterns) to optimize light interception in the context of the architectures of their leaves, branches and canopies. We hypothesized that (i) among canopy tree species sharing similar light environments, deciduous trees will have more evenly spaced within-twig leaf distribution patterns compared with evergreen trees (because deciduous species tend to higher metabolic demands than evergreen species and hence require more light), and that (ii) shade-adapted evergreen species will have more evenly spaced patterns compared with sun-adapted evergreen ones (because shade-adapted species are generally light-limited). We tested these hypotheses by measuring morphological traits (i.e., internode length, leaf area, lamina mass per area, LMA; and leaf and twig inclination angles to the horizontal) and physiological traits (i.e., light-saturated net photosynthetic rates, Amax; light saturation points, LSP; and light compensation points, LCP), and calculated the 'evenness' of within-twig leaf distribution patterns as the coefficient of variation (CV; the higher the CV, the less evenly spaced leaves) of within-twig internode length for 9 deciduous canopy tree species, 15 evergreen canopy tree species, 8 shade-adapted evergreen shrub species and 12 sun-adapted evergreen shrub species in a subtropical broad-leaved rainforest in eastern China. Coefficient of variation was positively correlated with large LMA and large leaf and twig inclination angles, which collectively specify a typical trait combination adaptive to low light interception, as indicated by both ordinary regression and phylogenetic generalized least squares analyses. These relationships were also valid within the evergreen tree species group (which had the largest sample size). Consistent with our hypothesis, in the canopy layer, deciduous species (which were characterized by high LCP, LSP and Amax) had more even leaf distribution patterns than evergreen species (which had low LCP, LSP and Amax); shade-adapted evergreen species had more even leaf distribution patterns than sun-adapted evergreen species. We propose that the leaf distribution pattern (i.e., 'evenness' CV, which is an easily measured functional trait) can be used to distinguish among life-forms in communities similar to the one examined in this study. PMID:23933830

Meng, Fengqun; Cao, Rui; Yang, Dongmei; Niklas, Karl J; Sun, Shucun

2013-07-01

283

Inherited Depletion in the Oceanic Mantle: Peridotite Composition and Distribution Along Gakkel Ridge  

NASA Astrophysics Data System (ADS)

Gakkel Ridge exploration dramatically improved our knowledge about melting processes under ultraslow- spreading ridges, particularly from a peridotite perspective. We present the result of a joint petrological- geochemical 5-yr study conducted at the MPI and WHOI labs. The first-order petrologic segmentation Gakkel Ridge is straightforward. The western part is dominated by robust magmatism. At 3°E, the axial water depth increases abruptly from 4500 to 5500 m and only abyssal peridotites occur for nearly 100 km along the axis. Between 10 and 30°E, there is a sparsely magmatic zone. Eastwards, Gakkel Ridge is again basalt-dominated with only sporadic peridotite occurrences. Based on the peridotite compositions (n>300) and that of breccia-hosted spinels, the magma-poor region between 3 and 20°E can be divided into 4 domains. Domains A and B in the west are devoid of basalts. The spinel Cr-nr in modally fertile lhz varies between 0.14 and 0.21. In the E-most B dredge haul, dunites were sampled (Cr-nr 0.41-0.43), as yet the only evidence for local heterogeneity. Cpx in B are LREE-depleted, in A they are unfractionated. Domain C is basalt-dominated. Peridotites display large compositional variation (lhz, hzb, dun: Cr-nr: 0.15- 0.53: LREE-depleted and -enriched samples within a single dredge). The samples with the lowest Cr-nr also are the most LREE depleted, best explained by near-fractional melting. The low-Cr-nr, LREE-depleted samples therefore reflect the regional degree of melting, which is similar for domains A and B. The modally depleted hzb have REE patterns that require extensive reactive melt migration, as do the opx-free dunites. This reactive melt transport is superimposed on the near-fractional melting, and must have been restricted to focused melt transport channels. Domain D consists exclusively of virtually cpx-free hzb and dunites (4 dredges, n=11, 40 km). The change from C to D is abrupt (<20 km). Cr-nrs between 0.53 and 0.63 are among the most depleted on the ocean floor, and not consistent with a spreading-rate dependent F. Most cpx REE patterns are LREE-enriched, one dunite is LREE-depleted, two hzb have hump-shaped cpx REE patterns. The distribution of breccia-hosted spinels (n=113) from Domain D show a similar range (0.50-0.65), confirming that there is no fertile peridotite relict preserved in the locally exposed mantle. These results suggest that low degrees of regional partial melting occurred in domains A, B and parts of C. From A to C, the amount of reactive melt transport seems to increase. The extreme depletion of domain D may be the result of a large-scale reaction with percolating melts. However, this is not consistent with scarcity of axial or off-axis basalts, unless there was highly asymmetrical along-axis melt focussing. The LREE enrichment in the interstitial cpx of the depleted hzb is best explained by diffuse and pervasive percolation of low-F melts from a garnet-pyroxenite source. Importantly, this signature can only be preserved at low F, suggesting that a strong depletion prior to upwelling underneath Gakkel Ridge is required. Depleted 'blobs' in the upper mantle may be present 'everywhere' with different scales and extents of pre- upwelling depletion. Their identification is the combination of ultra-slow spreading, dense sampling and detailed petrologic and geochemical investigations. One consequence is that quantitative partial melting models based on the measured peridotite compositions yield a F relative to DMM, which may not have been the appropriate source.

Hellebrand, E.; Snow, J. E.; Dick, H. J.; von der Handt, A.

2006-12-01

284

Chemical composition and size distribution of airborne particulate matters in Beijing during the 2008 Olympics  

NASA Astrophysics Data System (ADS)

Size-segregated aerosol samples were collected daily in Beijing from 1 Jun. to 20 Sep. during the Beijing Olympic Games in 2008 to investigate aerosol concentrations, particle size distributions, and sources as well as the effects of pollution control measures on the chemical compositions (including Water-soluble ions, trace elements, elemental carbon (EC), and organic carbon (OC)) in aerosols of different sizes. Water-soluble ions, EC, OC, and trace elements accounted for 45.0%, 1.6%, 14.7%, and 11.4% of the total particle mass (PM), respectively. Approximately 56%, 56%, 30%, 71% and 55% of the PM, water-soluble ions, trace elements, EC and OC, respectively, were associated with particles smaller than 2.1 ?m. Sulfate, nitrate, and ammonium were the dominant ions, which together accounted for approximately 77% of total water-soluble ions. The crustal elements accounted for the majority of the trace elements present. Different sources showed different mass size distributions. Anthropogenic source compounds, such as sulfate, nitrate, ammonium, OC, EC, and toxic elements, were mainly present in fine mode aerosols, whereas crustal elements, such as Al, Fe, Ca, Mg and Ba, primarily occurred in the coarse mode. SO42- and NH4+ concentrations were strongly correlated (r2 = 0.90, slope = 1.63) in the fine mode, thereby indicating that SO42- was mainly present as (NH4)2SO4; in contrast, a weak correlation between SO42- and NH4+ (r2 = 0.18, slope = 0.54) was observed in the coarse mode, indicating that SO42- was associated with other ions. Similarly, SO42- and NO3- exhibited a stronger correlation in the fine mode than in the coarse mode, indicating that SO42- and NO3- were formed via the same in-cloud processes in fine particles. The OC/EC ratio and the correlations between EC and OC concentrations showed that the sources of carbonaceous species were secondary organic carbon from fine particles and the long-range transport of coarse carbonaceous particles from biomass burning. The concentrations of atmospheric pollutants declined during the 2008 Olympic Games, indicating that the pollution control measures were effective in decreasing particulate air pollution in Beijing.

Li, Xingru; Wang, Lili; Wang, Yuesi; Wen, Tianxue; Yang, Yongjie; Zhao, Yanan; Wang, Yingfeng

2012-04-01

285

Life cycle analysis of distributed concentrating solar combined heat and power: economics, global warming potential and water  

NASA Astrophysics Data System (ADS)

We report on life cycle assessment (LCA) of the economics, global warming potential and water (both for desalination and water use in operation) for a distributed concentrating solar combined heat and power (DCS-CHP) system. Detailed simulation of system performance across 1020 sites in the US combined with a sensible cost allocation scheme informs this LCA. We forecast a levelized cost of 0.25 kWh-1 electricity and 0.03 kWh-1 thermal, for a system with a life cycle global warming potential of ˜80 gCO2eq kWh-1 of electricity and ˜10 gCO2eq kWh-1 thermal, sited in Oakland, California. On the basis of the economics shown for air cooling, and the fact that any combined heat and power system reduces the need for cooling while at the same time boosting the overall solar efficiency of the system, DCS-CHP compares favorably to other electric power generation systems in terms of minimization of water use in the maintenance and operation of the plant. The outlook for water desalination coupled with distributed concentrating solar combined heat and power is less favorable. At a projected cost of 1.40 m-3, water desalination with DCS-CHP would be economical and practical only in areas where water is very scarce or moderately expensive, primarily available through the informal sector, and where contaminated or salt water is easily available as feed-water. It is also interesting to note that 0.40-1.90 m-3 is the range of water prices in the developed world, so DCS-CHP desalination systems could also be an economical solution there under some conditions.

Norwood, Zack; Kammen, Daniel

2012-12-01

286

Vertical distribution of triple oxygen isotopic composition of dissolved oxygen in the northwestern Pacific  

NASA Astrophysics Data System (ADS)

Oxygen-17 excess of dissolved oxygen calculated from ?18O and ?17O is not affected by oxygen consumption process but controlled only by processes of primary production and air-water gas transfer. Evaluating gross primary productivity using the 17O-excess in ocean surface water are one of the most advanced geochemical researches for last 10 years. Oxygen-17 excess below ocean mixed/photic layer has not been much investigated because it might be out of focus for estimating present primary productivity, except for the purpose to correct diapycnal mixing effect on surface water. In principle, water mass which has not been affected both by photosynthesis and gas transfer after its separation from ocean surface could preserve 17O-excess value where the water mass was at the surface. The purpose of this study is to determine the vertical distribution of 17O-excess from the surface to the bottom of northwestern Pacific to know whether 17O-excess could really preserve its "original" value after the long and dark travel. Near stations K2 and KNOT, water mass which has a density of 26.8 ?? is observed at depth between 100 and 300 m. This water mass is mainly originated from bottom water in the Okhotsk Sea and spreading widely to entire northwestern Pacific, which is called North Pacific Intermediate Water (NPIW). NPIW is found at depth of 700 m at station S1. Samplings were conducted by two R/V Mirai cruises (MR10-06, Oct-Nov 2010; MR11-02, Feb-Mar 2011). Dissolved oxygen gas was purified by the method of Sarma et al. (2003) and its isotopic composition was determined by dual-inlet isotope ratio mass spectrometer (Thermo Scientific Delta Plus). Gross primary productivities at mixed layer estimated by 17O-excess were well consistent with those by conventional light and dark bottle incubations for stations K2 and S1.

Abe, Osamu; Honda, Makio; Saino, Toshiro

2013-04-01

287

The Distribution of the Magnetic Field in the Spine Depends on the Composition of Bone Marrow  

NASA Astrophysics Data System (ADS)

Although the composition of bone marrow with hemopoietic cells, fat cells, and extracellular fluid can be roughly assessed by standard MR-imaging techniques and especially water and lipid-selective chemical-shift-imaging methods, a new approach to the characterization of the magnetic properties of marrow was performed by special field-mapping techniques. The distribution of the magnetic field inside and outside vertebral bodies containing paramagnetic substances was systematically studied for phantoms and by measurements in vivo. Nineteen healthy volunteers and 26 patients with alterations of the bone marrow due to hematologic diseases were examined. The amount of paramagnetic substances in the marrow was estimated by measuring steps of Larmor frequency of the water resonances at the transition between vertebral bodies and adjacent intervertebral disks. These frequency steps were exhibited by MAGSUS imaging on a 1.5 Tesla whole-body imager. Additional volume-localized H-1 spectroscopy allowed a more quantitative assessment of the spectral components. The measured frequency steps of the water resonances ranged between 0 and 26 Hz for the healthy volunteers examined. In contrast, patients with pathologically altered marrow and high amount of paramagnetic substances revealed frequency steps of up to 85 Hz. The frequency steps in 8 patients after bone marrow transplantation (BMT) with slow reconstitution (mean 48.9 Hz, standard deviation (s.d.) 21.7 Hz) were significantly ( p < 0.001) higher than in normal volunteers. Seven BMT patients with good reconstitution (frequency steps: mean 16.7 Hz, s.d. 13.9 Hz) were not clearly different from the healthy subjects. Six patients with acute leukemia showed significantly ( p < 0.01) increasing frequency steps during initial cytotoxic treatment: The frequency steps increased from a mean of 4.7 Hz (s.d, 2.7 Hz) before treatment to a mean of 30.2 Hz (s.d. 14.6 Hz) after a few months of therapy.

Schick, F.

288

Distribution of protein poly(ADP-ribosyl)ation systems across all domains of life.  

PubMed

Poly(ADP-ribosyl)ation is a post-translational modification of proteins involved in regulation of many cellular pathways. Poly(ADP-ribose) (PAR) consists of chains of repeating ADP-ribose nucleotide units and is synthesized by the family of enzymes called poly(ADP-ribose) polymerases (PARPs). This modification can be removed by the hydrolytic action of poly(ADP-ribose) glycohydrolase (PARG) and ADP-ribosylhydrolase 3 (ARH3). Hydrolytic activity of macrodomain proteins (MacroD1, MacroD2 and TARG1) is responsible for the removal of terminal ADP-ribose unit and for complete reversion of protein ADP-ribosylation. Poly(ADP-ribosyl)ation is widely utilized in eukaryotes and PARPs are present in representatives from all six major eukaryotic supergroups, with only a small number of eukaryotic species that do not possess PARP genes. The last common ancestor of all eukaryotes possessed at least five types of PARP proteins that include both mono and poly(ADP-ribosyl) transferases. Distribution of PARGs strictly follows the distribution of PARP proteins in eukaryotic species. At least one of the macrodomain proteins that hydrolyse terminal ADP-ribose is also always present. Therefore, we can presume that the last common ancestor of all eukaryotes possessed a fully functional and reversible PAR metabolism and that PAR signalling provided the conditions essential for survival of the ancestral eukaryote in its ancient environment. PARP proteins are far less prevalent in bacteria and were probably gained through horizontal gene transfer. Only eleven bacterial species possess all proteins essential for a functional PAR metabolism, although it is not known whether PAR metabolism is truly functional in bacteria. Several dsDNA viruses also possess PARP homologues, while no PARP proteins have been identified in any archaeal genome. Our analysis of the distribution of enzymes involved in PAR metabolism provides insight into the evolution of these important signalling systems, as well as providing the basis for selection of the appropriate genetic model organisms to study the physiology of the specific human PARP proteins. PMID:24865146

Perina, Dragutin; Miko?, Andreja; Ahel, Josip; Cetkovi?, Helena; Zaja, Roko; Ahel, Ivan

2014-11-01

289

Life span and tissue distribution of 111indium-labeled blood platelets in hypomagnesemic lambs  

SciTech Connect

Circulating platelets may be activated by exposed triple-helical collagen in atherosclerotic lesions in Mg-deficient ruminants. Autologous platelets, labeled in vitro with 111In and determined to be active, were injected into 5 hypomagnesemic and 3 control lambs fed semipurified diets with 100 or 2,000 mg of Mg/kg of feed for 3 months. During the first 68 hours, 111In concentrations were 11 times higher in packed cells than in plasma. Packed-cell 111In increased 60% during the first 2 hours, probably due to initial tissue sequestration and later release of labeled platelets. Thereafter, platelet half-life span averaged 60 and 63 hours for hypomagnesemic and control lambs. After 68 hours, lambs were injected with native vascular collagen fibrils at 500 micrograms/kg of body weight to initiate reversible platelet aggregation. Within 1 minute, 83% of packed-cell 111In disappeared from circulation. Thirty minutes later, the lambs were euthanatized and necropsied and in the lungs, liver, and spleen, 111In averaged 24%, 19%, and 9%, respectively, of 111In injected 68 hours earlier. Organ deposits were not affected by Mg intake, but 111In in the lungs was somewhat lower in 2 lambs injected with inactivated collagen. Pathologic changes induced by reversible platelet aggregation were compatible with right ventricular failure complicated by pulmonary edema, similar to changes in hypomagnesemic lambs that died spontaneously. Platelets in blood exposed to vascular lesions in hypomagnesemic ruminants could be a major mortality risk factor in grass tetany disease.

Schneider, M.D.; Miller, J.K.; White, P.K.; Ramsey, N.

1983-05-01

290

S3QL: A distributed domain specific language for controlled semantic integration of life sciences data  

PubMed Central

Background The value and usefulness of data increases when it is explicitly interlinked with related data. This is the core principle of Linked Data. For life sciences researchers, harnessing the power of Linked Data to improve biological discovery is still challenged by a need to keep pace with rapidly evolving domains and requirements for collaboration and control as well as with the reference semantic web ontologies and standards. Knowledge organization systems (KOSs) can provide an abstraction for publishing biological discoveries as Linked Data without complicating transactions with contextual minutia such as provenance and access control. We have previously described the Simple Sloppy Semantic Database (S3DB) as an efficient model for creating knowledge organization systems using Linked Data best practices with explicit distinction between domain and instantiation and support for a permission control mechanism that automatically migrates between the two. In this report we present a domain specific language, the S3DB query language (S3QL), to operate on its underlying core model and facilitate management of Linked Data. Results Reflecting the data driven nature of our approach, S3QL has been implemented as an application programming interface for S3DB systems hosting biomedical data, and its syntax was subsequently generalized beyond the S3DB core model. This achievement is illustrated with the assembly of an S3QL query to manage entities from the Simple Knowledge Organization System. The illustrative use cases include gastrointestinal clinical trials, genomic characterization of cancer by The Cancer Genome Atlas (TCGA) and molecular epidemiology of infectious diseases. Conclusions S3QL was found to provide a convenient mechanism to represent context for interoperation between public and private datasets hosted at biomedical research institutions and linked data formalisms. PMID:21756325

2011-01-01

291

Ion angular distribution in plasma of vacuum arc ion source with composite cathode and elevated gas pressure.  

PubMed

The Metal Vapor Vacuum Arc (MEVVA) ion sources are capable of generating ion beams of almost all metals of the periodic table. For this kind of ion source, a combination of gas feeding with magnetic field allows the simultaneous generation of both metal and gaseous ions. That makes the MEVVA ion source an excellent instrument for science and application. This work presents results of investigation for ion angular distributions in vacuum arc plasma of Mevva-V.Ru ion source for composite cathodes and for elevated gas pressure. It was shown that for all the cathode materials, singly charged ions have wider angular distribution than multiply charged ions. Increasing the working gas pressure leads to a significant change in the angular distribution of gaseous ions, while with the distribution of metal ions gas remains practically unchanged. The reasons for such different influences are discussed. PMID:24593598

Nikolaev, A G; Savkin, K P; Yushkov, G Yu; Oks, E M

2014-02-01

292

Ion angular distribution in plasma of vacuum arc ion source with composite cathode and elevated gas pressure  

NASA Astrophysics Data System (ADS)

The Metal Vapor Vacuum Arc (MEVVA) ion sources are capable of generating ion beams of almost all metals of the periodic table. For this kind of ion source, a combination of gas feeding with magnetic field allows the simultaneous generation of both metal and gaseous ions. That makes the MEVVA ion source an excellent instrument for science and application. This work presents results of investigation for ion angular distributions in vacuum arc plasma of Mevva-V.Ru ion source for composite cathodes and for elevated gas pressure. It was shown that for all the cathode materials, singly charged ions have wider angular distribution than multiply charged ions. Increasing the working gas pressure leads to a significant change in the angular distribution of gaseous ions, while with the distribution of metal ions gas remains practically unchanged. The reasons for such different influences are discussed.

Nikolaev, A. G.; Savkin, K. P.; Yushkov, G. Yu.; Oks, E. M.

2014-02-01

293

Alkenone distribution in Lake Van sediment over the last 270 ka: influence of temperature and haptophyte species composition  

NASA Astrophysics Data System (ADS)

Fossil long-chain alkenones have been used for several decades to reconstruct past ocean surface water temperatures and gained recent interest as a paleotemperature proxy for continental lake settings. However, factors besides temperature can affect alkenone distributions in haptophyte algae, and alkenone compositions can differ between haptophyte species. Alkenone-biosynthesizing haptophyte algae are genetically much more diverse in lakes than in the marine realm, and species-level variations in alkenone compositions could have implications for alkenone paleothermometry. Here, we performed a paired analysis of alkenone distributions and haptophyte species compositions using ancient DNA in up to 270 ka-old sediments of Lake Van in Turkey to reveal a possible species-effect on fossil alkenone distributions and paleotemperature estimates. The same predominant haptophyte in Lake Van today prevailed also since the last ?100 ka. However, a calibration of alkenone paleotemperature especially in the oldest analyzed intervals is complicated due to a more complex haptophyte species composition predominated by a haptophyte (LVHap_6), which is phylogenetically different from sequences recovered from currently existing lakes including Lake Van and from haptophyte species existing in culture. The predominance of LVHap_6 coincided with the presence of alkenone MeC38:3 and relatively high MeC37:3/4 (2.4) and MeC38:4/5 ratios (3.0). Uk37 index values in the sediment core over the last 270 ka reflect relative changes in past temperature and are additionally linked to haptophyte species composition. A sustained period of high salinity, as indicated by pore-water salinity measurements, could potentially have triggered the succession of haptophytes as sources of alkenones in Lake Van.

Randlett, Marie-Ève; Coolen, Marco J. L.; Stockhecke, Mona; Pickarski, Nadine; Litt, Thomas; Balkema, Cherel; Kwiecien, Ola; Tomonaga, Yama; Wehrli, Bernhard; Schubert, Carsten J.

2014-11-01

294

Mineral classification revisited: use of quasiternary diagrams in the visualization of compositional distribution of inorganic material in coal  

SciTech Connect

A comparative study to determine the elemental composition of individual inorganic particles in the Pittsburgh No. 8 coal sample has been carried out with two different magnifications by SEM-EDS. The classification of particles into mineral classes left 30-40% of the particles unclassified. It was deduced that the sample contained the following minerals: calcite, kaolinite, pyrite, quartz, apatite, muscovite, and montmorillonite. The information of the compositional distribution of inorganic material in the coal sample is enhanced by use of the quasiternary diagrams. Minerals, such as apatite, calcite, pyrite, and quartz, can clearly be identified from the quasiternary diagram. A suitable elemental definition of the three corners in the quasiternary diagram enables the discussion of the compositional distribution and identity of the inorganic material that remains unclassified in the mineral classification. By combining the information from mineral classification and quasiternary diagrams, the composition of the inorganic material of the coal sample can be understood. This information can be used in the prediction of ash-related problems regardless of the fuel type. 50 refs., 6 figs., 2 tabs.

Heikki J. Ollila; Jouni H.A. Daavitsainen; Laura H. Nuutinen; Minna S. Tiainen; Mika E. Virtanen; Risto S. Laitinen [University of Oulu, Oulu (Finland). Department of Chemistry

2006-03-15

295

Spectroscopic study of the Moses Lake dune field, Washington: Determination of compositional distributions and source lithologies  

E-print Network

spectra are composed of three components that represent basalt, granodiorite, and clay compositions. The basalt and granodiorite components are similar to spectra of clast and bedrock samples from the Grand interdune compositional variation, indicating that the basalt and granodiorite components were likely

Bandfield, Joshua L.

296

Thermoelectric figure of merit for bulk nanostructured composites with distributed parameters  

SciTech Connect

The effective properties of composites whose structure includes nanocontacts between bulk-phase macrocrystallites are considered. A model for such a nanostructured composite is constructed. Effective values of the thermoelectric power, thermal and electrical conductivities, and thermoelectric figure of merit are calculated in the mean-field approximation.

Snarskii, A. A. [National Technical University 'Kyiv Polytechnic Institute' (Ukraine); Sarychev, A. K. [Russian Academy of Sciences, Institute for Theoretical and Applied Electromagnetics (Russian Federation); Bezsudnov, I. V., E-mail: biv@akuan.ru ['Nauka-Service' Scientific and Production Company (Russian Federation); Lagarkov, A. N. [Russian Academy of Sciences, Institute for Theoretical and Applied Electromagnetics (Russian Federation)

2012-05-15

297

Strength Prediction and Optimization of Composites with Statistical Fiber Flaw Distributions  

Microsoft Academic Search

For continuous fiber reinforced polymeric composites the process domi nating tensile strength is fiber fracture. This phenomena results in stress concentrations in adjacent fibers over some distance which is directly associated with the ineffective length. This length is the controlling factor in the theory of bundle strength for polymer-based composites. The associated stress concentration factor, C, is normally associated with

Zhanjun Gao; Kenneth L. Reifsnider; Greg Carman

1992-01-01

298

Composites  

NASA Astrophysics Data System (ADS)

It is commonly known that the properties of sintered materials are strongly related to technological conditions of the densification process. This paper shows the sintering behavior of a NiAl-Al2O3 composite, and its individual components sintered separately. Each kind of material was processed via the powder metallurgy route (hot pressing). The progress of sintering at different stages of the process was tested. Changes in the microstructure were examined using scanning and transmission electron microscopy. Metal-ceramics interface was clean and no additional phases were detected. Correlation between the microstructure, density, and mechanical properties of the sintered materials was analyzed. The values of elastic constants of NiAl/Al2O3 were close to intermetallic ones due to the volume content of the NiAl phase particularly at low densities, where small alumina particles had no impact on the composite's stiffness. The influence of the external pressure of 30 MPa seemed crucial for obtaining satisfactory stiffness for three kinds of the studied materials which were characterized by a high dense microstructure with a low number of isolated spherical pores.

Chmielewski, M.; Nosewicz, S.; Pietrzak, K.; Rojek, J.; Strojny-N?dza, A.; Mackiewicz, S.; Dutkiewicz, J.

2014-11-01

299

Evaluation of two fiber optic-based solar collection and distribution systems for advanced space life support  

NASA Technical Reports Server (NTRS)

Growing plants in an enclosed controlled environment is crucial in developing bioregenerative life-support systems (BLSS) for space applications. The major challenge currently facing a BLSS is the extensive use of highly energy-intensive electric light sources, which leads to substantial energy wastes through heat dissipations by these lamps. An alternative lighting strategy is the use of a solar irradiance collection, transmission, and distribution system (SICTDS). Two types of fiber optic-based SICTDS, a Fresnel-lens Himawari and a parabolic-mirror optical waveguide (OW) lighting system, were evaluated. The overall efficiency for the OW SICTDS of 40.5% exceeded by 75% that for the Himawari of 23.2%. The spectral distributions of the light delivered by the Himawari and the OW SICTDS were almost identical and had practically no difference from that of terrestrial solar radiation. The ratios of photosynthetically active radiation (PAR) to total emitted radiation (k) of 0.39 +/- 0.02 for the Himawari and 0.41 +/- 0.04 for the OW SICTDS were statistically indistinguishable, were not significantly different from that of 0.042 +/- 0.01 for terrestrial solar radiation, and were comparable to that of 0.35 for a high-pressure sodium (HPS) lamp. The coefficients of variation (CV) of 0.34 and 0.39 for PPF distributions, both at 50 mm X 50 mm square grid arrays, corresponding to the Himawari and the OW SICTDS, respectively, were comparable with each other but were both significantly greater than the CV of 0.08 corresponding to the HPS lamp. The average fresh weight or dry weight of lettuce grown in the solar chamber with either the Himawari or the OW SICTDS showed no statistical difference from the average fresh weight or dry weight of lettuce grown in the reference chamber with the HPS lamp. The results of this study suggest that an SICTDS could help reduce the electric power demand in a BLSS.

Jack, D. A.; Nakamura, T.; Sadler, P.; Cuello, J. L.

2002-01-01

300

Mesoscale distribution and community composition of zooplankton in the Mozambique Channel  

NASA Astrophysics Data System (ADS)

Recent studies have shown the Mozambique Channel to exhibit high mesoscale variability, but how mesoscale features influence the zooplankton community in this region is not known. The biovolume, biomass, vertical distribution and community composition of mesozooplankton (>200 µm) associated with mesoscale eddies in the Mozambique Channel was investigated during four cruises in September 2007, December 2008, November 2009 and April/May 2010. Stations were categorized according to their location in cyclonic (cold-core) or anticyclonic (warm-core) eddies, frontal, divergence or shelf regions. Mean mesozooplankton biovolume in the upper 200 m was 0.33 ml m-3, with zooplankton largely concentrated in the upper 100 m during all four cruises (weighted mean depth=66.6 m). Sampling depth was the most important predictor of biovolume, which was greatest for net samples with a mid-depth of 0-40 m, but declined deeper in the water column. Biovolume at the shelf (0.37 ml m-3), divergence and cyclonic eddy stations (0.31 ml m-3) was significantly greater than at frontal and anticyclonic eddy stations (0.20 ml m-3). Mean biovolume was significantly higher during 2008 and 2010 compared to 2007 and 2009, and was also significantly higher for samples collected at night (and twilight) than during the day. The mesozooplankton community in 2007 was strongly dominated by small copepods (~70-80% abundance) followed by appendicularians (10%), ostracods (8%) and chaetognaths (7%). The most abundant copepods were the Paracalanids, Oncaea spp., Oithona spp. and Corycaeus spp. Multivariate analysis showed that the communities in 2007 and 2008 were most strongly structured by depth, but classification (cyclonic/anticyclonic) was also important in 2007 when mesoscale features were more strongly developed. Zooplankton assemblages showed a high degree of homogeneity, with differences between mesoscale features largely due to differing abundances of similar taxa. These observations suggest that mesoscale eddy and shelf interactions play a fundamental role in shaping the Mozambique Channel pelagic ecosystem through the concentration, enhanced growth and redistribution of zooplankton communities. Although frontal areas between eddies were poor in zooplankton biomass, the extensive inter-eddy divergence areas were as rich in biomass as the small cyclonic eddy core regions. These patterns are important for understanding the favorability of observed foraging areas for higher trophic levels.

Huggett, Jenny A.

2014-02-01

301

Exclusive Breastfeeding and Other Foods in the First Six Months of Life: Effects on Nutritional Status and Body Composition of Brazilian Children  

PubMed Central

Objective. To evaluate the effect of exclusive breastfeeding and consumption of other foods in the first six months of life in the nutritional status and body composition of children. Methods. A retrospective cohort study with 185 children aged from 4 to 7 years was monitored during the first months of life in a program of support to breastfeeding. We evaluated weight, height, waist circumference, and body composition by using DEXA. The nutritional status was assessed by the BMI/age index. The parameters of adiposity were classified by using as the cutoff point, the 85th percentile of the sample itself, according to gender and age. Confounding factors considered were variables related to maternal, pregnancy, birth, sociodemographic, health, lifestyle, and diet. Bivariate and multivariate analyses were performed, the latter by means of multiple logistic regression. Results. The median exclusive breastfeeding was 3 months. Of the children, 42.7% received cow's milk and 35.7% received infant formula. Regarding nutritional status, 21.1% of the children showed changes. The variables of infant feeding were not independently associated with nutritional status and body composition of the children and there were no differences between the groups studied. Conclusion. Breastfeeding was not a protective factor to overweight and body fat in children. PMID:23193378

Magalhães, Taís C. A.; Vieira, Sarah A.; Priore, Silvia E.; Ribeiro, Andréia Q.; Lamounier, Joel A.; Franceschini, Sylvia C. C.; Sant'Ana, Luciana F. R.

2012-01-01

302

Seasonal distribution and fatty acid composition of littoral microalgae in the Yenisei River  

Microsoft Academic Search

We studied fatty acid (FA) composition of littoral microalgae in the fast-flowing oligotrophic river, the Yenisei, Siberia,\\u000a monthly for 3 years. Seasonal dynamics of species composition had similar patterns in all the studied years. In springs, a\\u000a pronounced dominance of filamentous green algae occurred, in summer and autumn diatoms were abundant, and in late autumn and\\u000a winter epilithic biofilms consisted primarily

Nadezhda N. Sushchik; Michail I. Gladyshev; Elena A. Ivanova; Elena S. Kravchuk

2010-01-01

303

Distribution of stable isotopes in arid storms . I. Relation between the distribution of isotopic composition in rainfall and in the consequent runoff  

NASA Astrophysics Data System (ADS)

Temporal distributions of the isotopic composition in arid rain storms and in the associated runoff were investigated in a small arid rocky basin in Israel. Customized rain and runoff samplers provided sequential water samples hermetically sealed in high-density PVC bags. In several storms where the runoff was isotopically depleted, compared with the rainfall, the difference could not be explained by fractionation effects occurring during overland flow. A water-balance study relating the runoff discharge to rainfall over a rocky watershed showed that the entire discharge is produced by a very small segment (1-2mm) of the rain storm. The major objective, therefore, was to provide quantitative relations between segments of rainfall (rain showers and rain spells) and runoff. The time distribution of the composition of stable isotopes (oxygen and hydrogen) was used to quantify the correlation between the rain spell's amount and the consequent runoff. The aim of this work was to (a) utilize the dynamic variations in the isotopic composition in rainfall and runoff and model the magnitude of surface-storage capacity associated with runoff processes of overland flow, and (b) characterize the isotopic composition of the percolating water with respect to the isotopic distribution in rainfall and runoff events. The conceptual model postulates an isotopic mixing of overland flow with water within the depression storage. A transport model was then formulated in order to estimate the physical watershed parameters that control the development of overland flow from a certain rainfall period. Part I (this paper) presents the results and the assessment of the relative depression storage obtained from oxygen-18 and deuterium analyses that lead to the physical and mathematical formulation of a double-component model of kinematic-wave flow and transport, which is presented in Part II (accompanying paper). Résumé Les variations temporelles, en zone aride, de la composition isotopique des précipitations et du ruissellement associé ont étéétudiées dans un petit bassin rocheux aride en Israël. Des préleveurs spécialement adaptés pour la pluie et le ruissellement ont fourni des échantillons séquentiels dans des sacs en PVC haute densité hermétiquement fermés. Au cours de plusieurs épisodes pluvieux où le ruissellement était isotopiquement appauvri par rapport à la pluie, la différence ne pouvait pas être expliquée par des effets de fractionnement intervenant au cours de l'écoulement en surface. Un bilan hydrologique rapportant l'écoulement de surface à la pluie sur un bassin versant rocheux montre que l'écoulement dans sa totalité est alimenté par une très petite partie (1-2mm) de l'averse. C'est pourquoi l'objectif essentiel a été de rechercher des relations quantitatives entre des parties de la pluie (averses et épisodes pluvieux) et le ruissellement. La répartition temporelle de la composition en isotopes stables (oxygène et hydrogène) a été utilisée pour quantifier la corrélation entre la hauteur tombée pendant l'épisode pluvieux et le ruissellement produit. Le but de ce travail était (a) d'utiliser les variations dynamiques de la composition isotopique dans la pluie et dans le ruissellement pour modéliser l'ordre de grandeur de la capacité de stockage de surface associée aux processus de ruissellement de l'écoulement de surface, et (a) de caractériser la composition isotopique de l'eau d'infiltration par rapport à la variation isotopique observée dans les pluies et dans les écoulements correspondants. Resumen La distribución temporal de la composición isotópica de las tormentas en zonas áridas y la correspondiente escorrentía se analizó en una pequeña cuenca rocosa en Israel. Los medidores de lluvia y escorrentía proporcionaron muestras de agua secuenciales, selladas herméticamente en bolsas de PVC de alta densidad. En muchas tormentas en las que la escorrentía tenía una composición isotópica distinta de la lluvia, la diferencia no podía explicarse por efectos de fraccionamien

Adar, E. M.; Dody, A.; Geyh, M. A.; Yair, A.; Yakirevich, A.; Issar, A. S.

304

Variation in Spring Nearshore Resident Fish Species Composition and Life Histories in the Lower San Joaquin Watershed and Delta  

E-print Network

environmental and ecological changes within estuar- ies: afor estuarine SEPTEMBER 2006 populations. EcologicalEcological patterns of early life his- tory stages of fishes in a large river-floodplain of the San Francisco Estuary.

Brown, Larry R.; May, Jason T.

2006-01-01

305

Statistical Continuum Theory for the Effective Conductivity of Fiber Filled Polymer Composites: Effect of Orientation Distribution and Aspect Ratio  

SciTech Connect

Effective conductivity of polymer composites, filled with conducting fibers such as carbon nanotubes, is studied using statistical continuum theory. The fiber orientation distribution in the matrix plays a very important role on their effective properties. To take into account their orientation, shape and distribution, two-point and three-point probability distribution functions are used. The effect of fibers orientation is illustrated by comparing the effective conductivity of microstructures with oriented and non-oriented fibers. The randomly oriented fibers result in an isotropic effective conductivity. The increased fiber orientation distribution can lead to higher anisotropy in conductivity. The effect of fiber’s aspect ratio on the effective conductivity is studied by comparing microstructures with varying degrees of fiber orientation distribution. Results show that the increase in anisotropy leads to higher conductivity in the maximum fiber orientation distribution direction and lower conductivity in the transverse direction. These results are in agreement with various models from the literature that show the increase of the aspect ratio of fibers improves the electrical and thermal conductivity.

Mikdam, Amed; Makradi, A.; Ahzi, Said; Garmestani, Hamid; Li, Dongsheng; Remond, Y.

2010-03-01

306

Distributions  

NSDL National Science Digital Library

This online, interactive lesson on distributions provides examples, exercises, and applets which explore the basic types of probability distributions and the ways distributions can be defined using density functions, distribution functions, and quantile functions.

Siegrist, Kyle

307

Quantitative assessment on the orientation and distribution of carbon fibers in a conductive polymer composite using high-frequency ultrasound.  

PubMed

Conductive polymer composites, typically fabricated from a mix of conductive fillers and a polymer substrate, are commonly applied as bipolar plates in a fuel cell stack. Electrical conductivity is a crucial property that greatly depends on the distribution and orientation of the fillers. In this study, a 50-MHz ultrasound imaging system and analysis techniques capable of nondestructively assessing the properties of carbon fibers (CFs) in conductive polymer composites were developed. Composite materials containing a mix of polycarbonate substrates and 0 to 0.3 wt% of CFs were prepared using an injection molding technique. Ultrasonic A-line signals and C-scan images were acquired from each composite sample in regions at a depth of 0.15 mm beneath the sample surface (region A) and those at a depth of 0.3 mm (region B). The integrated backscatter (IB) and the Nakagami statistical parameter were calculated to quantitatively assess the samples. The area ratio, defined as the percentage of areas composed of CF images normalized by that of the whole C-scan image, was applied to further quantify the orientation of CFs perpendicular to the sample surface. Corresponding to the increase in CF concentrations from 0.1 to 0.3 wt%, the average IB and Nakagami parameter (m) of the composite samples increased from -78.10 ± 2.20 (mean ± standard deviation) to -72.66 ± 1.40 dB and from 0.024 ± 0.012 to 0.048 ± 0.011, respectively. The corresponding area ratios were respectively estimated to be 0.78 ± 0.35%, 2.33 ± 0.66%, and 2.20 ± 0.60% in region A of the samples; those of CFs with a perpendicular orientation were 0.04 ± 0.03%, 0.08 ± 0.02%, and 0.12 ± 0.05%. The area ratios in region B of the samples were calculated to be 1.19 ± 0.54%, 2.81 ± 0.42%, and 2.64 ± 0.76%, and those of CFs with a perpendicular orientation were 0.07 ± 0.04%, 0.12 ± 0.04%, and 0.14 ± 0.03%. According to the results of the orientations and ultrasonic images, CFs tended to distribute more uniformly in the deeper regions of the samples. This study validates that the distribution and orientation of CFs in conductive polymer composites could be sensitively and quantitatively assessed by high-frequency ultrasound in conjunction with current analysis methods. PMID:22622982

Lin, Yi-Hsun; Huang, Chih-Chung; Wang, Shyh-Hau

2012-05-01

308

Mortality of the oldest old Chinese: The role of early-life nutritional status, socioeconomic conditions, and sibling sex-composition  

PubMed Central

Based on a nationally representative sample of 8,099 Chinese drawn from the Chinese Longitudinal Healthy Longevity Survey (CLHLS), this study investigated the long-term health consequences of early-life nutritional status, sibling sex-composition, childhood socioeconomic conditions, and place of birth on mortality at ages 80 and above between 1998 and 2005. Better nutritional status in childhood predicted lower mortality at ages 80 and above, net of childhood circumstances, adult socioeconomic status, and health behaviors. In addition, sibling sex composition had long-term health consequences, net of childhood and adult characteristics, such that women benefited from having grown up in families with only daughters, while men benefited from having grown up in families with both sons and daughters. Childhood socioeconomic status was only marginally related to old-age mortality and this association was attenuated further by the inclusion of adult characteristics. Place of birth was not a significant predictor of old-age mortality. PMID:19184718

Huang, Cheng; Elo, Irma T.

2010-01-01

309

Effects of martial arts exercise on body composition, serum biomarkers and quality of life in overweight/obese premenopausal women: a pilot study  

PubMed Central

Various exercise interventions have been shown to benefit weight control and general health in different populations. However, very few studies have been conducted on martial arts exercise (MAE). The objective of this pilot study is to evaluate the efficacy of 12 weeks of MAE intervention on body composition, serum biomarkers and quality of life (QOL) in overweight/obese premenopausal women. We found that subjects in the MAE group did not lose body weight, while they significantly decreased fat-free mass and muscle mass as compared to those in the control group, who demonstrated an increase in these parameters. The MAE group demonstrated an increase in serum IGF-I concentration, but no change in others. MAE may be a feasible and effective approach to improve body composition and QOL in overweight/obese premenopausal women. Our study underscores the need for further studies using larger samples to establish possible benefits of MAE in various populations. PMID:24665215

Chyu, Ming-Chien; Zhang, Yan; Brismée, Jean-Michel; Dagda, Raul Y.; Chaung, Eugene; Von Bergen, Vera; Doctolero, Susan; Shen, Chwan-Li

2013-01-01

310

Depth distribution and composition of seed banks under different tree layers in a managed temperate forest ecosystem  

NASA Astrophysics Data System (ADS)

In the present work we examined the composition and distribution across three soil layers of the buried soil seed bank under three different overstory types ( Fagus sylvatica, Quercus robur, Pinus sylvestris) and in logging areas in a 4383-ha forest in central Belgium. The objectives were: (1) to investigate whether species composition and species richness of soil seed banks are affected by different forest stands; (2) to examine how abundant are habitat-specific forest species in seed banks under different planted tree layers. The study was carried out in stands which are replicated, managed in the same way (even-aged high forest), and growing on the same soil type with the same land-use history. In the investigated area, the seed bank did show significant differences under oak, beech, pine and in logging areas, respectively in terms of size, composition and depth occurrence. All species and layers taken together, the seed bank size ranked as follows: oakwood > beechwood > logging area > pinewood. The same pattern was found for forest species. Seed numbers of Betula pendula, Calluna vulgaris, Dryopteris dilatata and Rubus fruticosus were significantly higher under the beech canopy. Carex remota, Impatiens parviflora and Lotus sp. showed a significantly denser seed bank in logging areas, while Digitalis purpurea seeds were significantly more abundant in soils under the oak canopy. The fact that the seed bank of an originally homogeneous forest varies under different planted stands highlights that a long period of canopy conversion can affect the composition and depth of buried seeds.

Godefroid, Sandrine; Phartyal, Shyam S.; Koedam, Nico

2006-05-01

311

Effects of breed type and feeding regimen on goat composition, retail shelf-life, sensory and chemical characteristics  

E-print Network

was removed from the rough leg by a straight cut between the fourth and fifth sacral vertebra. One side of each carcass was vacuum packaged, frozen and later thawed and dissected into knife separable components to determine physical composition...

Oman, Jessica Spurling

2012-06-07

312

Title LIFE-TIME POWER EFFICIENCY IMPROVEMENT OF DISTRIBUTED PHOTO- VOLTAIC DC-DC INVERTERS IN SOLAR PANEL SYSTEMS  

E-print Network

Photo-voltaic solar panels provide a very attractive solution for future clean energy provision on site. Today's panels provide a relatively high efficiency under optimal conditions and when just fabricated. However, when external temperature, radiation angle, and radiation concentration conditions are varying, also the power efficiency fluctuates quite heavily. This is partly also true for the DC-DC inverter subsystem, especially when seen in the interaction with the solar modules. The range of these effects heavily depends on the context in which these panels are used and on the type of circuits and technology used. In this thesis, we want to model the DC-DC inverter circuits, especially for a distributed case where they are partly integrated into the solar modules. Also the control of these inverters will be investigated. We want to explore the effects of the different parameters and identify which of those effects can be effectively mitigated or counter acted. This will contribute heavily to the efficiency over the entire life time of the future solar system, with minimal hardware cost increase. That will result in a large practical impact of the work in this thesis. Keywords: photovoltaic DC-DC inverter, power-efficiency analysis, efficiency improving control, comparison of techniques

Contact Person Reinhart; Promotor Prof; Francky Catthoor; Prof Johan Driesen (imec-leuven; K. U. Leuven; Prof Francky Catthoor; Prof Johan Driesen

313

Enzymatic Activity, Bacterial Distribution, and Organic Matter Composition in Sediments of the Ross Sea (Antarctica)  

PubMed Central

Enzymatic activities of aminopeptidase and ?-glucosidase were investigated in Antarctic Ross Sea sediments at two sites (sites B and C, 567 and 439 m deep, respectively). The sites differed in trophic conditions related to organic matter (OM) composition and bacterial distribution. Carbohydrate concentrations at site B were about double those at site C, while protein and lipid levels were 10 times higher. Proteins were mainly found in a soluble fraction (>90%). Chloropigment content was generally low and phaeopigments were almost absent, indicating the presence of reduced inputs of primary organic matter. ATP concentrations (as a measure of the living microbial biomass) were significantly higher at site B. By contrast, benthic bacterial densities at site C were about double those at site B. Bacterial parameters do not appear to be “bottom-up controlled” by the amount of available food but rather “top-down controlled” by meiofauna predatory pressure, which was significantly higher at site B. Aminopeptidase and ?-glucosidase extracellular enzyme activities (EEA) in Antarctic sediments appear to be high and comparable to those reported for temperate or Arctic sediments and characterized by low aminopeptidase/?-glucosidase ratios (about 10). Activity profiles showed decreasing patterns with increasing sediment depth, indicating vertical shifts in both availability and nutritional quality of degradable OM. Vertical profiles of aminopeptidase activity were related to a decrease in protein concentration and/or to an increase in the insoluble refractory proteinaceous fraction. The highest aminopeptidase activity rates were observed at site C, characterized by much lower protein concentrations. Differences in EEA between sites do not seem to be explained by differences in the in situ temperature (?1.6 and ?0.8°C at sites B and C, respectively). Aminopeptidase activity profiles are consistent with the bacterial biomass and frequency of dividing cells. Enzyme substrate affinity was generally dependent upon substrate concentrations. EEA, normalized to bacterial numbers, indicated specific activities comparable to those reported for equally deep sediments at temperate latitudes. Vertical patterns of specific enzymatic activity appeared to be controlled by chloroplastic pigment concentrations that accumulate in the deeper sediment layers. The overall conclusion from the analysis of EEA in Antarctic sediments is that enzyme-dependent transformations of OM proceed at rates similar to those measured in temperate environments. Protein carbon potentially liberated by aminopeptidase activities (12.597 to 26.190 mg of C m?2 day?1) indicates that the whole protein pool could be mobilized within 1.3 to 17 h. Carbohydrate carbon mobilization (773 to 2,552 mg of C m?2 day?1) is sufficient to turn over the carbohydrate pool within 16 to 20 h. Such rates are 6 to 45 times higher than fluxes of particulate organic proteins and carbohydrates, indicating an “uncoupled hydrolysis” by the Antarctic benthic assemblages, in which bacteria appear to be able to rapidly exploit episodic OM pulses. PMID:9758808

Fabiano, Mauro; Danovaro, Roberto

1998-01-01

314

Influence of post and resin cement on stress distribution of maxillary central incisors restored with direct resin composite.  

PubMed

The current study evaluated the influence of two endodontic post systems and the elastic modulus and film thickness of resin cement on stress distribution in a maxillary central incisor (MCI) restored with direct resin composite using finite element analysis (FEA). A three-dimensional model of an MCI with a coronary fracture and supporting structures was performed. A static chewing pressure of 2.16 N/mm2 was applied to two areas on the palatal surface of the composite restoration. Zirconia ceramic (ZC) and glass fiber (GF) posts were considered. The stress distribution was analyzed in the post, dentin and cement layer when ZC and GF posts were fixed to the root canals using resin cements of different elastic moduli (7.0 and 18.6 GPa) and different layer thicknesses (70 and 200 microm). The different post materials presented a significant influence on stress distribution with lesser stress concentration when using the GF post. The higher elastic modulus cement created higher stress levels within itself. The cement thicknesses did not present significant changes. PMID:19363979

Spazzin, A O; Galafassi, D; de Meira-Júnior, A D; Braz, R; Garbin, C A

2009-01-01

315

How Rocky Are They? The Composition Distribution of Kepler's Sub-Neptune Planet Candidates within 0.15 AU  

E-print Network

The Kepler Mission has found thousands of planetary candidates with radii between 1 and 4 R$_\\oplus$. These planets have no analogues in our own Solar System, providing an unprecedented opportunity to understand the range and distribution of planetary compositions allowed by planet formation and evolution. A precise mass measurement is usually required to constrain the possible composition of an individual super-Earth-sized planet, but these measurements are difficult and expensive to make for the majority of Kepler planet candidates. Fortunately, adopting a statistical approach helps us to address this question without them. In particular, we apply hierarchical Bayesian modeling to a subsample of Kepler planet candidates that is complete for $P1.2$ R$_\\oplus$ and draw upon interior structure models which yield radii largely independent of mass by accounting for the thermal evolution of a gaseous envelope around a rocky core. Assuming the envelope is dominated by hydrogen and helium, we present the current-da...

Wolfgang, Angie

2014-01-01

316

Size distribution and chemical composition of aerosol particles in the free troposphere over Japan: Aircraft measurements  

SciTech Connect

Aircraft measurements of number-, mass- and volume-size distributions of aerosols and concentration of sulfate, nitrate and others contained in particulate matter were made in the free troposphere over Japan in 1991-1994. Number-size distribution frequently shows a peak in the area of a diameter of D {ge} 1 {mu}m in the free troposphere during observational periods. A few peaks are identified in the volume-size distribution as estimated on the basis of number-size distribution having single mode in a coarse range. Mass-size distribution frequently indicate enhancement in the coarse size range. This feature of the distribution is more frequent in those measurements made at 4.42 km than those at 2.29 km. On the basis of a backward trajectory analysis of the air mass containing those particles, soil particles originating from the Asian continent affect the features found in the size distributions as well as and vertical change in those size distributions. Particulate sulfate concentration in the free troposphere suggested that chemical transformation of particles with D {ge} 1 {mu}m advanced during long range transport of the particle possibly through coagulation of sulfate particles on coarse size particles such as Asian dust particles, adsorption of gaseous sulfate. Those measurements provide useful data et to discuss global geochemical cycle and radiative forcing of particles originated from the Asian continent.

Iwasaka, Y.; Mori, I.; Mastunga, K. [Nagoya Univ. (Japan)

1996-12-31

317

A composite trust model and its application to collaborative distributed information fusion  

Microsoft Academic Search

We consider the distributed state estimation of a linear dynamic system, observed by various sensors, as a problem in information fusion. We introduce a novel model of trust, using weights on the graph links and nodes that represent the sensor network. These weights can represent several interpretations of trustworthiness in sensor networks. We describe two algorithms that integrate distributed Kalman

Ion Matei; John S. Baras; Tao Jiang

2009-01-01

318

Creating Composite Age Groups to Smooth Percentile Rank Distributions of Small Samples  

ERIC Educational Resources Information Center

Individually administered tests are often normed on small samples, a process that may result in irregularities within and across various age or grade distributions. Test users often smooth distributions guided by Thurstone assumptions (normality and linearity) to result in norms that adhere to assumptions made about how the data should look. Test…

Lopez, Francesca; Olson, Amy; Bansal, Naveen

2011-01-01

319

Distribution of ether lipids and composition of the archaeal community in terrestrial geothermal springs: impact of environmental variables.  

PubMed

Archaea can respond to changes in the environment by altering the composition of their membrane lipids, for example, by modification of the abundance and composition of glycerol dialkyl glycerol tetraethers (GDGTs). Here, we investigated the abundance and proportions of polar GDGTs (P-GDGTs) and core GDGTs (C-GDGTs) sampled in different seasons from Tengchong hot springs (Yunnan, China), which encompassed a pH range of 2.5-10.1 and a temperature range of 43.7-93.6°C. The phylogenetic composition of the archaeal community (reanalysed from published work) divided the Archaea in spring sediment samples into three major groups that corresponded with spring pH: acidic, circumneutral and alkaline. Cluster analysis showed correlation between spring pH and the composition of P- and C-GDGTs and archaeal 16S rRNA genes, indicating an intimate link between resident Archaea and the distribution of P- and C-GDGTs in Tengchong hot springs. The distribution of GDGTs in Tengchong springs was also significantly affected by temperature; however, the relationship was weaker than with pH. Analysis of published datasets including samples from Tibet, Yellowstone and the US Great Basin hot springs revealed a similar relationship between pH and GDGT content. Specifically, low pH springs had higher concentrations of GDGTs with high numbers of cyclopentyl rings than neutral and alkaline springs, which is consistent with the predominance of high cyclopentyl ring-characterized Sulfolobales and Thermoplasmatales present in some of the low pH springs. Our study suggests that the resident Archaea in these hot springs are acclimated if not adapted to low pH by their genetic capacity to effect the packing density of their membranes by increasing cyclopentyl rings in GDGTs at the rank of community. PMID:25142282

Xie, Wei; Zhang, Chuanlun L; Wang, Jinxiang; Chen, Yufei; Zhu, Yuanqing; de la Torre, José R; Dong, Hailiang; Hartnett, Hilairy E; Hedlund, Brian P; Klotz, Martin G

2014-08-20

320

Long-Lasting Effects of Early-Life Antibiotic Treatment and Routine Animal Handling on Gut Microbiota Composition and Immune System in Pigs  

PubMed Central

Background In intensive pig husbandry systems, antibiotics are frequently administrated during early life stages to prevent respiratory and gastro-intestinal tract infections, often in combination with stressful handlings. The immediate effects of these treatments on microbial colonization and immune development have been described recently. Here we studied whether the early life administration of antibiotics has long-lasting effects on the pig’s intestinal microbial community and on gut functionality. Methodology/Principal Findings To investigate the long-lasting effect of early-life treatment, piglets were divided into three different groups receiving the following treatments: 1) no antibiotics and no stress, 2) antibiotics and no stress, and 3) antibiotics and stress. All treatments were applied at day four after birth. Sampling of jejunal content for community scale microbiota analysis, and jejunal and ileal tissue for genome-wide transcription profiling, was performed at day 55 (~8 weeks) and day 176 (~25 weeks) after birth. Antibiotic treatment in combination with or without exposure to stress was found to have long-lasting effects on host intestinal gene expression involved in a multitude of processes, including immune related processes. Conclusions/Significance The results obtained in this study indicate that early life (day 4 after birth) perturbations have long-lasting effects on the gut system, both in gene expression (day 55) as well as on microbiota composition (day 176). At day 55 high variance was observed in the microbiota data, but no significant differences between treatment groups, which is most probably due to the newly acquired microbiota during and right after weaning (day 28). Based on the observed difference in gene expression at day 55, it is hypothesized that due to the difference in immune programming during early life, the systems respond differently to the post-weaning newly acquired microbiota. As a consequence, the gut systems of the treatment groups develop into different homeostasis. PMID:25658611

Schokker, Dirkjan; Zhang, Jing; Vastenhouw, Stéphanie A.; Heilig, Hans G. H. J.; Smidt, Hauke; Rebel, Johanna M. J.; Smits, Mari A.

2015-01-01

321

[Species composition and main populations spatial distribution pattern in Korean pine broadleaved forest in Xiaoxing' An Mountains of Northeast China].  

PubMed

Taking the Korean pine broadleaved forest in Liangshui Nature Reserve of Heilongjiang Province, Northeast China as test object, this paper studied the species composition and diameter class structure, and by using point pattern analysis, analyzed the spatial distribution pattern and spatial association of the main populations. In the Reserve, there were a total of 16 species with diameter greater than 1 cm in tree layer, and great differences were observed in the densities of main populations. Coniferous trees such as Pinus koraiensis and Abies nephrolepis were dominant. The diameter class structure of the populations presented as an inverse "J" curve, indicating a good regeneration across the community. The main populations were mostly in aggregated distribution pattern, except that the P. koraiensis populations at the scales of 19-21 m and 44 m as well as the Acer tegmentosum populations close to the largest research scale were in random distribution. The P. koraiensis populations at all research scales were approximately in random distribution, and had the minimum aggregation. A. nephrolepis, Tilia amurensis, and A. tegmentosum populations all presented a random distribution trend. Except that the P. koraiensis and A. nephrolepis at 2-3 m scale and the A. nephrolepis and A. tegmentosum populations at 37-81 m scale had significant positive association, no significant associations were observed between other populations. All the tree species presented an overall non-significant positive association. PMID:24564130

Hou, Hong-Ya; Wang, Li-Hai

2013-11-01

322

Miscibility of hexene-LLDPE and LDPE blends: influence of branch content and composition distribution  

E-print Network

Miscibility of hexene-LLDPE and LDPE blends: influence of branch content and composition (LLDPE) on its miscibility with low-density polyethylene (LDPE) were investigated. Ziegler­Natta (ZN influenced its miscibility with LDPE. The ZN­LLDPE blend with LDPE was found to be more miscible than an m

Hussein, Ibnelwaleed A.

323

Wisconsin desmids. III. Desmid community composition and distribution in relation to lake type and water chemistry  

Microsoft Academic Search

This investigation summarizes quantitative data on the generic composition of the euplankton and aufwuchs desmid communities of 61 Wisconsin lakes, and analyzes the information with respect to 1) the role of the various genera in terms of frequency, density, and relative importance, 2) the suitability of various lake types for harboring desmid communities, and 3) the relationships between chemical parameters

William J. Woelkerling; Stephen B. Gough

1976-01-01

324

Interface Character Distributions in WCCo Composites Chang-Soo Kim,*,z,z  

E-print Network

. Introduction TUNGSTEN Carbide-Cobalt composites are used in a range of applications where hardness and abrasion and carbide volume fractions have been comprehensively characterized. The carbide crystals are most frequently terminated by (0001) and ð1010� surfaces. The average number of carbide vertices per grain and the basal

Rohrer, Gregory S.

325

IEEE TRANSACTIONS ON MULTIMEDIA, VOL. ?, NO. ?, 2005 1 Distributed Multimedia Service Composition  

E-print Network

into an application-level overlay network. Recently, several research projects (e.g., [13], [14], [20], [3]) have. In this paper, we present a fully decentralized service composition framework, called SpiderNet, to address the challenges. SpiderNet provides statistical multi-constrained QoS assurances and load bal- ancing for service

Nahrstedt, Klara

326

Piezoelectric control of composite plate vibration: Effect of electric potential distribution  

Microsoft Academic Search

The paper deals with the vibration analysis of active rectangular plates. The plates considered are composites containing piezoelectric sensor\\/actuator layers, which operate in a velocity feedback control to achieve transverse vibration suppression. The piezoelectric layers are poled through the thickness and equipped with traditional surface electrodes. In order to satisfy the Maxwell electrostatics equation the widely used simplification of the

Marek Pietrzakowski

2008-01-01

327

SPM investigations of phase distribution in lead phthalocyanine-perylene derivative composite films  

Microsoft Academic Search

During last years organic semiconductors found practical application in organic solar cells and organic LEDs (1). One possible way to advance the electronic properties of organic semiconductor materials is a doping by another organic or inorganic material (2). The arrangement of one material in matrix of another one is important characteristic that significantly influence on electronic properties of composite. In

B. A. Gribkov; V. L. Mironov; S. V. Gaponov; A. V. Misevich; N. Novgorod

328

Assessing Historical Fish Community Composition Using Surveys, Historical Collection Data, and Species Distribution Models  

Microsoft Academic Search

Accurate establishment of baseline conditions is critical to successful management and habitat restoration. We demonstrate the ability to robustly estimate historical fish community composition and assess the current status of the urbanized Barton Creek watershed in central Texas, U.S.A. Fish species were surveyed in 2008 and the resulting data compared to three sources of fish occurrence information: (i) historical records

Ben Labay; Adam E. Cohen; Blake Sissel; Dean A. Hendrickson; F. Douglas Martin; Sahotra Sarkar; Howard Browman

2011-01-01

329

Particulate backscattering ratio at LEO 15 and its use to study particle composition and distribution  

E-print Network

of refraction. The index of refraction is an indicator of the bulk particulate composition, as inorganic minerals have high indices of refraction relative to oceanic organic particles such as phytoplankton it in shallow coastal shelf waters. [3] Light scattering by particles depends on the particle's size, index

Boss, Emmanuel S.

330

Sources, distribution and composition of the suspended sediments, Kuwait Bay, Northern Arabian Gulf  

Microsoft Academic Search

Qualitative and quantitative assessment of suspended sediment levels and transport pathways in Kuwait's northern territorial waters are described, with special reference to Kuwait Bay. Near-surface water samples were collected from 12 stations, covering the whole of the embayment. Suspended sediment concentrations (SSCs) were derived. Heavy metal concentrations, mineralogical composition and grain size constituents were derived for the suspended sediments retained

A. N. Al-Ghadban; A. El-Sammak

2005-01-01

331

Monte Carlo Simulation of Thermal Conductivity in Randomly Distributed Nanowire Composites  

NASA Astrophysics Data System (ADS)

In this paper, we investigated the thermal conductivity of composites made of two types of randomly stacked nanowires with high contrast ratio of bulk thermal conductivity. Thermal conductivity predictions based on solving the phonon Boltzmann transport equation by using the Monte Carlo method are presented for different contrast ratios of thermal conductivity, sizes of nanowires and the volumetric fractions in the composites. For composites made of nanowires with high contrast ratio thermal conductivity, the thermal conductivity of the nanocomposites increase dramatically when the volumetric fraction of high thermal conductivity nanowire is higher than the geometry percolation threshold, although existing correlations in percolation theory do not fit the results due to the phonon interface scattering. On the other hand, when the the size of nanowires is small and the volumetric fraction of high thermal conductivity nanowire is less than percolation threshold, the thermal conductivity of the nanocomposites decreases with increasing the volumetric fraction of the high thermal conductivity nanowires. The results of this study may help the development of nanoscale thermoelectric materials in which the figure of merit is optimized by choosing appropriate nanowire size, property contrast and composition. RY acknowledges the funding support for this work by DoD/AFOSR MURI grant FA9550-06-1-0326. The simulation was conducted on a 24-node cluster supported by Intel Corporation and managed by Prof. Gang Chen and Mr. Lu Hu at MIT.

Tian, W.; Yang, R.

2007-03-01

332

Role of reversal incoherency in reducing switching field and switching field distribution of exchange coupled composite bit patterned media  

NASA Astrophysics Data System (ADS)

Model exchange coupled composite media, namely [Co/Pd]5/Pd(t)/[Co/Ni]3/Co multilayers, deposited onto prepatterned substrates have been investigated for potential use in bit patterned recording. Optimizing the thickness of the Pd interlayer allows decreasing the switching field (HC) and switching field distribution (?SFD) while maintaining thermal stability. The dependence of the remanent coercivity on the external field angle indicates that the gain in HC and ?SFD originates from the incoherent magnetization reversal introduced by slightly decoupling the hard and soft multilayer stacks. This tendency is confirmed by further reductions in HC and ?SFD, when inserting another Pd interlayer within the hard [Co/Pd]5 stack.

Hauet, T.; Dobisz, E.; Florez, S.; Park, J.; Lengsfield, B.; Terris, B. D.; Hellwig, O.

2009-12-01

333

Measurement of dijet angular distributions and search for quark compositeness in pp collisions at ?s = 7 TeV.  

PubMed

Dijet angular distributions are measured over a wide range of dijet invariant masses in pp collisions at ?s = 7 TeV, at the CERN LHC. The event sample, recorded with the CMS detector, corresponds to an integrated luminosity of 36 pb?¹. The data are found to be in good agreement with the predictions of perturbative QCD, and yield no evidence of quark compositeness. With a modified frequentist approach, a lower limit on the contact interaction scale for left-handed quarks of ?? = 5.6 TeV (?? = 6.7 TeV) for destructive (constructive) interference is obtained at the 95% confidence level. PMID:21668222

Khachatryan, V; Sirunyan, A M; Tumasyan, A; Adam, W; Bergauer, T; Dragicevic, M; Erö, J; Fabjan, C; Friedl, M; Frühwirth, R; Ghete, V M; Hammer, J; Hänsel, S; Hartl, C; Hoch, M; Hörmann, N; Hrubec, J; Jeitler, M; Kasieczka, G; Kiesenhofer, W; Krammer, M; Liko, D; Mikulec, I; Pernicka, M; Rohringer, H; Schöfbeck, R; Strauss, J; Taurok, A; Teischinger, F; Wagner, P; Waltenberger, W; Walzel, G; Widl, E; Wulz, C-E; Mossolov, V; Shumeiko, N; Suarez Gonzalez, J; Benucci, L; Cerny, K; De Wolf, E A; Janssen, X; Maes, T; Mucibello, L; Ochesanu, S; Roland, B; Rougny, R; Selvaggi, M; Van Haevermaet, H; Van Mechelen, P; Van Remortel, N; Beauceron, S; Blekman, F; Blyweert, S; D'Hondt, J; Devroede, O; Gonzalez Suarez, R; Kalogeropoulos, A; Maes, J; Maes, M; Tavernier, S; Van Doninck, W; Van Mulders, P; Van Onsem, G P; Villella, I; Charaf, O; Clerbaux, B; De Lentdecker, G; Dero, V; Gay, A P R; Hammad, G H; Hreus, T; Marage, P E; Thomas, L; Vander Velde, C; Vanlaer, P; Wickens, J; Adler, V; Costantini, S; Grunewald, M; Klein, B; Marinov, A; McCartin, J; Ryckbosch, D; Thyssen, F; Tytgat, M; Vanelderen, L; Verwilligen, P; Walsh, S; Zaganidis, N; Basegmez, S; Bruno, G; Caudron, J; Ceard, L; De Favereau De Jeneret, J; Delaere, C; Demin, P; Favart, D; Giammanco, A; Grégoire, G; Hollar, J; Lemaitre, V; Liao, J; Militaru, O; Ovyn, S; Pagano, D; Pin, A; Piotrzkowski, K; Schul, N; Beliy, N; Caebergs, T; Daubie, E; Alves, G A; De Jesus Damiao, D; Pol, M E; Souza, M H G; Carvalho, W; Da Costa, E M; De Oliveira Martins, C; Fonseca De Souza, S; Mundim, L; Nogima, H; Oguri, V; Prado Da Silva, W L; Santoro, A; Silva Do Amaral, S M; Sznajder, A; Torres Da Silva De Araujo, F; Dias, F A; Dias, M A F; Fernandez Perez Tomei, T R; Gregores, E M; Marinho, F; Novaes, S F; Padula, Sandra S; Darmenov, N; Dimitrov, L; Genchev, V; Iaydjiev, P; Piperov, S; Rodozov, M; Stoykova, S; Sultanov, G; Tcholakov, V; Trayanov, R; Vankov, I; Dyulendarova, M; Hadjiiska, R; Kozhuharov, V; Litov, L; Marinova, E; Mateev, M; Pavlov, B; Petkov, P; Bian, J G; Chen, G M; Chen, H S; Jiang, C H; Liang, D; Liang, S; Wang, J; Wang, J; Wang, X; Wang, Z; Xu, M; Yang, M; Zang, J; Zhang, Z; Ban, Y; Guo, S; Guo, Y; Li, W; Mao, Y; Qian, S J; Teng, H; Zhang, L; Zhu, B; Zou, W; Cabrera, A; Gomez Moreno, B; Ocampo Rios, A A; Osorio Oliveros, A F; Sanabria, J C; Godinovic, N; Lelas, D; Lelas, K; Plestina, R; Polic, D; Puljak, I; Antunovic, Z; Dzelalija, M; Brigljevic, V; Duric, S; Kadija, K; Morovic, S; Attikis, A; Galanti, M; Mousa, J; Nicolaou, C; Ptochos, F; Razis, P A; Rykaczewski, H; Finger, M; Finger, M; Assran, Y; Mahmoud, M A; Hektor, A; Kadastik, M; Kannike, K; Müntel, M; Raidal, M; Rebane, L; Azzolini, V; Eerola, P; Czellar, S; Härkönen, J; Heikkinen, A; Karimäki, V; Kinnunen, R; Klem, J; Kortelainen, M J; Lampén, T; Lassila-Perini, K; Lehti, S; Lindén, T; Luukka, P; Mäenpää, T; Tuominen, E; Tuominiemi, J; Tuovinen, E; Ungaro, D; Wendland, L; Banzuzi, K; Korpela, A; Tuuva, T; Sillou, D; Besancon, M; Choudhury, S; Dejardin, M; Denegri, D; Fabbro, B; Faure, J L; Ferri, F; Ganjour, S; Gentit, F X; Givernaud, A; Gras, P; Hamel de Monchenault, G; Jarry, P; Locci, E; Malcles, J; Marionneau, M; Millischer, L; Rander, J; Rosowsky, A; Shreyber, I; Titov, M; Verrecchia, P; Baffioni, S; Beaudette, F; Bianchini, L; Bluj, M; Broutin, C; Busson, P; Charlot, C; Dahms, T; Dobrzynski, L; Granier de Cassagnac, R; Haguenauer, M; Miné, P; Mironov, C; Ochando, C; Paganini, P; Sabes, D; Salerno, R; Sirois, Y; Thiebaux, C; Wyslouch, B; Zabi, A; Agram, J-L; Andrea, J; Besson, A; Bloch, D; Bodin, D; Brom, J-M; Cardaci, M; Chabert, E C; Collard, C; Conte, E; Drouhin, F; Ferro, C; Fontaine, J-C; Gelé, D; Goerlach, U; Greder, S; Juillot, P; Karim, M; Le Bihan, A-C; Mikami, Y; Van Hove, P; Fassi, F; Mercier, D; Baty, C; Beaupere, N; Bedjidian, M; Bondu, O; Boudoul, G; Boumediene, D; Brun, H; Chanon, N; Chierici, R; Contardo, D; Depasse, P; El Mamouni, H; Falkiewicz, A; Fay, J; Gascon, S; Ille, B; Kurca, T; Le Grand, T; Lethuillier, M; Mirabito, L; Perries, S; Sordini, V; Tosi, S; Tschudi, Y; Verdier, P; Xiao, H; Megrelidze, L; Roinishvili, V; Lomidze, D; Anagnostou, G; Edelhoff, M; Feld, L; Heracleous, N; Hindrichs, O; Jussen, R; Klein, K; Merz, J; Mohr, N; Ostapchuk, A; Perieanu, A; Raupach, F; Sammet, J; Schael, S; Sprenger, D; Weber, H; Weber, M; Wittmer, B; Ata, M; Bender, W; Erdmann, M; Frangenheim, J; Hebbeker, T; Hinzmann, A; Hoepfner, K; Hof, C; Klimkovich, T; Klingebiel, D; Kreuzer, P; Lanske, D; Magass, C; Masetti, G; Merschmeyer, M; Meyer, A; Papacz, P; Pieta, H; Reithler, H; Schmitz, S A; Sonnenschein, L; Steggemann, J; Teyssier, D; Bontenackels, M; Davids, M; Duda, M; Flügge, G; Geenen, H; Giffels, M; Haj Ahmad, W; Heydhausen, D; Kress, T; Kuessel, Y; Linn, A; Nowack, A; Perchalla, L; Pooth, O; Rennefeld, J; Sauerland, P; Stahl, A; Thomas, M

2011-05-20

334

Building a Composite Model of Business Process Management with System Development Life Cycle: An Action Research on Multiple Systems  

Microsoft Academic Search

Business Process Management (BPM) methods analyze, assess and design business processes. Although it is praised for business alignment and adaptability, this kind of method is in its initial stage and has its shortcomings in regard to detail system development and execution. However, System Development Life Cycle (SDLC) methods, though lacking a cautious consideration of business strategies, carefully examine functional goals

Shari Shang

335

The elemental composition of purple sea urchin (Strongylocentrotus purpuratus) calcite and potential effects of pCO2 during early life stages  

NASA Astrophysics Data System (ADS)

Ocean acidification will likely have negative impacts on invertebrates producing skeletons composed of calcium carbonate. Skeletal solubility is partly controlled by the incorporation of "foreign" ions (e.g. magnesium) into the crystal lattice of these skeletal structures, a process that is sensitive to a variety of biological and environmental factors. Here we explore effects of life stage, oceanographic region of origin, and changes in the partial pressure of carbon dioxide in seawater (pCO2) on trace elemental composition in the purple sea urchin (Strongylocentrotus purpuratus). We show that, similar to other urchin taxa, adult purple sea urchins have the ability to precipitate skeleton composed of a range of biominerals spanning low- to high-Mg calcites. Mg / Ca and Sr / Ca ratios were substantially lower in adult spines compared to adult tests. On the other hand, trace elemental composition was invariant among adults collected from four oceanographically distinct regions spanning a range of carbonate chemistry conditions (Oregon, Northern California, Central California, and Southern California). Skeletons of newly settled juvenile urchins that originated from adults from the four regions exhibited intermediate Mg / Ca and Sr / Ca between adult spine and test endmembers, indicating that skeleton precipitated during early life stages is more soluble than adult spines and less soluble than adult tests. Mean skeletal Mg / Ca or Sr / Ca of juvenile skeleton did not vary with source region when larvae were reared under present-day, global-average seawater carbonate conditions (400 ?atm; pHT = 8.02 ± 0.03 1 SD; ?calcite = 3.3 ± 0.2 1 SD). However, when reared under elevated pCO2 (900 ?atm; pHT = 7.73 ± 0.03; ?calcite = 1.8 ± 0.1), skeletal Sr / Ca in juveniles exhibited increased variance across the four regions. Although larvae from the northern populations (Oregon, Northern California, Central California) did not exhibit differences in Mg or Sr incorporation under elevated pCO2 (Sr / Ca = 2.10 ± 0.06 mmol mol-1; Mg / Ca = 67.4 ± 3.9 mmol mol-1), juveniles of Southern California origin partitioned ~8% more Sr into their skeletons when exposed to higher pCO2 (Sr / Ca = 2.26 ± 0.08 vs. 2.09 ± 0.005 mmol mol-1 1 SD). Together these results suggest that the diversity of carbonate minerologies present across different skeletal structures and life stages in purple sea urchins does not translate into an equivalent geochemical plasticity of response associated with geographic variation or temporal shifts in seawater properties. Rather, composition of S. purpuratus skeleton precipitated during both early and adult life history stages appears relatively robust to spatial gradients and predicted future changes in carbonate chemistry. An exception to this trend may arise during early life stages, where certain populations of purple sea urchins may alter skeletal mineral precipitation rates and composition beyond a given pCO2 threshold. This potential for geochemical plasticity during early development in contrast to adult stage geochemical resilience adds to the growing body of evidence that ocean acidification can have differing effects across organismal life stages.

LaVigne, M.; Hill, T. M.; Sanford, E.; Gaylord, B.; Russell, A. D.; Lenz, E. A.; Hosfelt, J. D.; Young, M. K.

2013-06-01

336

Effects of mechanical properties of adhesive resin cements on stress distribution in fiber-reinforced composite adhesive fixed partial dentures.  

PubMed

Using finite element analysis (FEA), this study investigated the effects of the mechanical properties of adhesive resin cements on stress distributions in fiber-reinforced resin composite (FRC) adhesive fixed partial dentures (AFPDs). Two adhesive resin cements were compared: Super-Bond C&B and Panavia Fluoro Cement. The AFPD consisted of a pontic to replace a maxillary right lateral incisor and retainers on a maxillary central incisor and canine. FRC framework was made of isotropic, continuous, unidirectional E-glass fibers. Maximum principal stresses were calculated using finite element method (FEM). Test results revealed that differences in the mechanical properties of adhesive resin cements led to different stress distributions at the cement interfaces between AFPD and abutment teeth. Clinical implication of these findings suggested that the safety and longevity of an AFPD depended on choosing an adhesive resin cement with the appropriate mechanical properties. PMID:22447051

Yokoyama, Daiichiro; Shinya, Akikazu; Gomi, Harunori; Vallittu, Pekka K; Shinya, Akiyoshi

2012-01-01

337

Effect of pH on Protein Distribution in Electrospun PVA/BSA Composite Nanofibers  

E-print Network

: We examine the protein distribution within an electrospun polymer nanofiber using polyvinyl alcohol with an electrospinnable polymer such as polyvinyl alcohol (PVA) or poly(ethylene oxide) (PEO). Additionally, protein

Khan, Saad A.

338

Distribution and enantiomeric composition of amino acids in the Murchison meteorite  

NASA Technical Reports Server (NTRS)

Studies of the amino acid contents and enantiomeric compositions of a single stone from the Murchison meteorite are reported. Water-extracted and 6M HCl-extracted samples from the meteorite interior of meteorite fragments were analyzed by gas chromatography and combined gas chromatography-chemical ionization mass spectrometry. Examination of the D/L ratios of glutamic acid, aspartic acid, proline, leucine and alanine reveals those amino acids extractable by water to be partially racemized, whereas the acid-extracted amino acids were less racemized. The amino acid composition of the stone is similar to those previously reported, including the absence of serine, threonine, tyrosine phenylalanine and methionine and the presence of unusual amino acids including such as isovaline, alpha-aminoisobutyric acid and pseudoleucine. It is concluded that the most likely mechanism accounting for the occurrence of nonracemic amino acid mixtures in the Murchison meteorite is by extraterrestrial stereoselective synthesis or decomposition reactions.

Engel, M. H.; Nagy, B.

1982-01-01

339

Measurement of internal die pressure distributions during pultrusion of thermoplastic composites  

NASA Astrophysics Data System (ADS)

This paper describes the development and use of a thin, disposable pressure sensor designed specifically for monitoring pointwise through-the-thickness consolidation forces developed during composite processing. The unique postage stamp-sized sensor (11.1 mm diameter active gage area and 0.31 mm thickness) can be placed directly at points in or on a laminate where pressure data is desired. The sonsor's small dimensions and low cost permit it to be treated as a disposable item in aerospace and other composite fabrication applications. This paper will illustrate the use of the sensor as a means of measuring the pressures developed inside a die during the pultrusion of a graphite/ULTEM thermoplastic structure, as well as with other pultrusion processing examples.

Fanucci, Jerome P.; Nolet, Stephen C.; Koppernaes, Christian; Kim, Young R.

340

Phytoplankton community compositions in the western equatorial Pacific determined from chlorophyll and carotenoid pigment distributions  

NASA Astrophysics Data System (ADS)

The chlorophyll and carotenoid pigment compositions of particulate matter from 11 locations in the western equatorial Pacific were analysed by high performance liquid chromatography (HPLC). Chlorophyll a (Chl a) concentrations were generally low, as is common in oligotrophic waters, but they differed by more than an order of magnitude between locations (0.01-0.34 ?gl -1). Chlorophyll b concentrations were high at most stations, and higher than Chl a at one site on the equator. Major carotenoids included zeaxanthin, 19'-hexanoyloxyfucoxanthin and 19'-butanoyloxyfucoxanthin. Peridinin, prasinoxanthin and fucoxanthin were present in low concentrations at every station (0-16 ng l -1), but alloxanthin was found at only three sites. The concentrations of marker pigments were used in conjuction with Chl a/pigment ratios characteristics of the different algal classes to derive the composition (by class) of the phytoplankton communities. These calculations suggest that the phytoplankton communities are dominated by algal classes which mainly contain nanoplanktonic species. Prymnesiophytes were abundant at most stations, whereas green algae, cyanobacteria and prochlorophytes were important in specific areas. Although diatoms are usually the major source of fucoxanthin in productive water bodies, in these equatorial watersprymnesiophyte contributions were much more important. Diatoms were not abundant at any station. Community composition and biomass showed greater variation than has been reported for other oligotrophic regions, probably due to local features such as water mixing near the equator and off the coast of Papua New Guinea. Some of the advantages and limitations of HPLC analysis of marker pigments for the determination of phytoplankton community compositions in oceanic waters are discussed.

Everitt, D. A.; Wright, S. W.; Volkman, J. K.; Thomas, D. P.; Lindstrom, E. J.

1990-06-01

341

Composition, distribution and supposed origin of mineral inclusions in sessile oak wood — consequences for microdensitometrical analysis  

Microsoft Academic Search

SEM and light-microscopical observations, supported by chemical microanalysis with an EDXA system, revealed that light-saturated\\u000a pixels observed in X-ray negatives of sessile oak (Quercus petraea Liebl.) wood were caused by inorganic deposits present inside multiseriate ray and axial parenchyma cells. Calcium oxalate\\u000a crystals, silica grains and amorphous granules with varied mineral compositions have been identified. The wood strips of three

Dries Vansteenkiste; Joris Van Acker; Marc Stevens; Didier Le Thiec; Gérard Nepveu

2007-01-01

342

Effect of reaction mixture composition and silica source on size distribution of zeolite X crystals  

NASA Astrophysics Data System (ADS)

Zeolite X crystals were synthesized by hydrothermal crystallization from gels with different compositions. The syntheses were performed at 95 °C using different silica sources such as sodium metasilicate anhydrous, sodium metasilicate pentahydrate, silicate solution and Cab-O-Sil. Triethanolamine was used in some syntheses in order to grow large crystals. Zeolite X crystals with diameters in the range of 1-220 ?m were obtained, and Cab-O-Sil in concert with triethanolamine yielded the largest crystals.

Tekin, Rumeysa; Bac, Nurcan; Warzywoda, Juliusz; Sacco, Albert

2015-02-01

343

The distribution and composition of vascular plant communities on Heard Island  

Microsoft Academic Search

Six major higher plant communities are defined for sub-Antarctic Heard Island: tussock grassland, meadow, herbfield, pool complex, cushion-carpet, fellfield. The communities were mapped at a scale of 1:50000, using colour aerial photographs and field observations. The floristic composition of twelve vegetation transects and of thirty sample quadrats along these is used to describe the communities and identify dominant or indicator

Jocelyne M. R. Hughes

1987-01-01

344

The influence of particle distribution on the mechanical response of a particulate metal matrix composite  

Microsoft Academic Search

A self-consistent model, based on Eshelby's equivalent inclusion method, has been developed to predict to flow of a particulate-reinforced alloy. The model gives excellent agreement with the measured elastic moduli for Al\\/SiC composites. Beyond the elastic limit, the model predicts an increase in the initial work hardening rate with increasing particle content. At large strains (above about 1%) the stress-strain

S. F. Corbin; D. S. Wilkinson

1994-01-01

345

Impacts of land use on nutrient distribution and vegetation composition of freshwater wetlands in northern Belize  

Microsoft Academic Search

The coastal plain of northern Belize consists of relatively undisturbed freshwater marshes that are strongly phosphorus-limited\\u000a and characterized by monodominant stands or mixtures of emergent macrophytes. In order to assess the impact of agricultural\\u000a activities on the nutrient dynamics and plant species composition in adjacent wetlands, we sampled along transects in 40 marshes—20\\u000a located downslope from agricultural fields and 20

Sarah Johnson; Eliška Rejmánková

2005-01-01

346

The Stability of Rankings Derived from Composite Indicators: Analysis of the "IL Sole 24 Ore" Quality of Life Report  

ERIC Educational Resources Information Center

The calculation of composite indicators and the derivation of respective rankings is a common method used to benchmark countries or regions. However, although the statistical robustness of these rankings is often criticised, they often still spark off heated political debate. Here, we assess the sensitivity of the province ranking published by the…

Lun, G.; Holzer, D.; Tappeiner, G.; Tappeiner, U.

2006-01-01

347

Species and life-history affects the utility of otolith chemical composition to determine natal stream-of-origin in Pacific salmon  

USGS Publications Warehouse

To test the utility of otolith chemical composition as a tool for determining the natal stream of origin for salmon, we examined water chemistry and otoliths of juvenile and adult Chum Salmon Oncorhynchus keta and Coho Salmon O. kisutch from three watersheds (five rivers) in the Norton Sound region of Alaska. The two species are characterized by different life histories: Coho Salmon rear in freshwater for up to 3 years, whereas Chum Salmon emigrate from freshwater shortly after emergence. We used laser ablation (LA) inductively coupled plasma (ICP) mass spectrometry (MS) to quantify element: Ca ratios for Mg, Mn, Zn, Sr, and Ba, and we used multicollector LA-ICP-MS to determine 87Sr:86Sr ratios in otolith regions corresponding to the period of freshwater residence. Significant differences existed in both water and otolith elemental composition, suggesting that otolith composition could be used to discriminate the natal origin of Coho Salmon and Chum Salmon but only when 87Sr:86Sr ratios were included in the discriminant function analyses. The best discriminant model included 87Sr:86Sr ratios, and without 87Sr:86Sr ratios it was difficult to discriminate among watersheds and rivers. Classification accuracy was 80% for Coho Salmon and 68% for Chum Salmon, indicating that this method does not provide sufficient sensitivity to estimate straying rates of Pacific salmon at the scale we studied.

Zimmerman, Christian E.; Swanson, Heidi K.; Volk, Eric C.; Kent, Adam J.R.

2013-01-01

348

The Impact of Oil Consumption Mechanisms on Diesel Exhaust Particle Size Distributions and Detailed Exhaust Chemical Composition  

SciTech Connect

Detailed exhaust emission data have been taken from a Cummins N-14 single cylinder research engine in which the oil consumption was varied by different engine modifications. Low sulfur fuel was used, and oil consumption was varied by modifying the intake valve stem seals, the exhaust valve stem seals, the oil control ring and combinations of these modifications. Detailed measurements of exhaust gas particle size distributions and chemical composition were made for the various oil consumption configurations for a range of engine loads and speeds. The particulate mass was measured with TEOM and traditional gravimetric filter methods. Filter data for EC/OC, sulfates and trace metals have been taken and analyzed. The trace metals in the particulate mass serve as the basis for assessing oil consumption at the different operating conditions. The data indicate that the oil consumption for the steady state testing done here was approximately an order of magnitude below oil consumption values cited in the literature. We did measure changes in the details of the chemical composition of the particulate for the different engine operating conditions, but it did not correlate with changes in the oil consumption. Furthermore, the data indicate that the particle size distribution is not strongly impacted by low level oil consumption variations observed in this work.

Stetter, J; Forster, N; Ghandhi, J; Foster, D

2003-08-24

349

Development of Reliability Based Life Prediction Methods for Thermal and Environmental Barrier Coatings in Ceramic Matrix Composites  

NASA Technical Reports Server (NTRS)

Literature survey related to the EBC/TBC (environmental barrier coating/thermal barrier coating) fife models, failure mechanisms in EBC/TBC and the initial work plan for the proposed EBC/TBC life prediction methods development was developed as well as the finite element model for the thermal/stress analysis of the GRC-developed EBC system was prepared. Technical report for these activities is given in the subsequent sections.

Shah, Ashwin

2001-01-01

350

Fragment yield distribution and the influence of neutron composition and excitation energy in multifragmentation reactions  

NASA Astrophysics Data System (ADS)

The isotopic properties of the primary and secondary fragment yield distribution in the multifragmentation of 58Fe+58Ni and 58Fe+58Fe reactions are studied with respect to the 58Ni+58Ni reaction at 30, 40, and 47 MeV/nucleon. The reduced neutron and proton densities from the observed fragment yield distribution show primary fragment yield distribution to undergo strongly secondary deexcitations. The effect is small at the lowest excitation energy and smallest neutron-to-proton ratio and becomes large at higher excitation energies and higher neutron-to-proton ratio. The symmetry energy of the primary fragments deduced from the reduced neutron density is significantly lower than that for the normal nuclei at saturation density, indicating that the fragments are highly excited and formed at a reduced density. Furthermore, the symmetry energy is also observed to decrease slowly with increasing excitation energy. The observed effect is explained using the statistical multifragmentation model.

Shetty, D. V.; Botvina, A. S.; Yennello, S. J.; Souliotis, G. A.; Bell, E.; Keksis, A.

2005-02-01

351

Particle size distribution of distillers dried grains with solubles (DDGS) and relationships to compositional and color properties.  

PubMed

Eleven distillers dried grains with solubles (DDGS), processed from yellow corn, were collected from different ethanol processing plants in the US Midwest area. Particle size distribution (PSD) by mass of each sample was determined using a series of six selected US standard sieves: Nos. 8, 12, 18, 35, 60, and 100, and a pan. The original sample and sieve sized fractions were measured for surface color and contents of moisture, protein, oil, ash, and starch. Total carbohydrate (CHO) and total non-starch CHO were also calculated. Results show that there was a great variation in composition and color among DDGS from different plants. Surprisingly, a few DDGS samples contained unusually high amounts of residual starch (11.1-17.6%, dry matter basis, vs. about 5% of the rest), presumably resulting from modified processing methods. Particle size of DDGS varied greatly within a sample and PSD varied greatly among samples. The 11 samples had a mean value of 0.660mm for the geometric mean diameter (dgw) of particles and a mean value of 0.440mm for the geometric standard deviation (Sgw) of particle diameters by mass. The majority had a unimodal PSD, with a mode in the size class between 0.5 and 1.0mm. Although PSD and color parameters had little correlation with composition of whole DDGS samples, distribution of nutrients as well as color attributes correlated well with PSD. In sieved fractions, protein content, L and a color values negatively while contents of oil and total CHO positively correlated with particle size. It is highly feasible to fractionate DDGS for compositional enrichment based on particle size, while the extent of PSD can serve as an index for potential of DDGS fractionation. The above information should be a vital addition to quality and baseline data of DDGS. PMID:18448335

Liu, Keshun

2008-11-01

352

Mass size distributions and size resolved chemical composition of fine particulate matter at the Pittsburgh supersite  

Microsoft Academic Search

Size-resolved aerosol mass and chemical composition were measured during the Pittsburgh Air Quality Study. Daily samples were collected for 12 months from July 2001 to June 2002. Micro-orifice uniform deposit impactors (MOUDIs) were used to collect aerosol samples of fine particulate matter smaller than 10?m. Measurements of PM0.056, PM0.10, PM0.18, PM0.32, PM0.56, PM1.0, PM1.8 and PM2.5 with the MOUDI are

Juan C. Cabada; Sarah Rees; Satoshi Takahama; Andrey Khlystov; Spyros N. Pandis; Cliff I. Davidson; Allen L. Robinson

2004-01-01

353

A hierarchical tin/carbon composite as an anode for lithium-ion batteries with a long cycle life.  

PubMed

Tin is a promising anode candidate for next-generation lithium-ion batteries with a high energy density, but suffers from the huge volume change (ca. 260?%) upon lithiation. To address this issue, here we report a new hierarchical tin/carbon composite in which some of the nanosized Sn particles are anchored on the tips of carbon nanotubes (CNTs) that are rooted on the exterior surfaces of micro-sized hollow carbon cubes while other Sn nanoparticles are encapsulated in hollow carbon cubes. Such a hierarchical structure possesses a robust framework with rich voids, which allows Sn to alleviate its mechanical strain without forming cracks and pulverization upon lithiation/de-lithiation. As a result, the Sn/C composite exhibits an excellent cyclic performance, namely, retaining a capacity of 537?mAh?g(-1) for around 1000?cycles without obvious decay at a high current density of 3000?mA?g(-1) . PMID:25504807

Huang, Xingkang; Cui, Shumao; Chang, Jingbo; Hallac, Peter B; Fell, Christopher R; Luo, Yanting; Metz, Bernhard; Jiang, Junwei; Hurley, Patrick T; Chen, Junhong

2015-01-26

354

Composition and On Demand Deployment of Distributed Brain Activity Analysis Application on Global Grids  

Microsoft Academic Search

The distribution of knowledge (by scientists) and data sources (advanced scientific instruments), and the need of large-scale computational resources for analyzing massive scientific data are two major problems commonly observed in scientific disciplines. The two popular scientific disciplines of this nature are brain science and high-energy physics. The analysis of brain activity data gathered from the MEG (Magnetoencephalography) instrument is

R. Buyya; S. Date; Y. Mizuno-Matsumoto; S. Venugopal; D. Abramson

355

Bacterial Composition of Biofilms Collected From Two Service Areas in a Metropolitan Drinking Water Distribution System  

EPA Science Inventory

The development and succession of bacteria were examined by 16S rRNA gene clone libraries generated from various biofilms within a metropolitan water distribution system. Biofilms were obtained from off-line devices using polycarbonate coupons from annular reactors incubated for ...

356

Species composition and distribution of butterfishes (Stromateidae) in waters of Russia  

Microsoft Academic Search

Descriptions and distribution of two species of butterfishes (genus Pampus) in the waters of Russia are given. All known findings in the national waters are documented. The generic and specific characteristics\\u000a are defined more exactly. The validity of P. echinogaster is confirmed.

V. N. Dolganov; V. E. Kharin; V. V. Zemnukhov

2007-01-01

357

Distribution of REE between clinopyroxene and basaltic melt along a mantle adiabat: Effects of major element composition, water, and temperature  

NASA Astrophysics Data System (ADS)

The distribution of REE between clinopyroxene (cpx) and basaltic melt is important in deciphering the processes of mantle melting. Most models for mantle melting assume constant mineral-melt partition coefficient (D) for trace elements, even though partitioning experiments have demonstrated that D depends on pressure (P), temperature (T), and compositions of mineral and melt. In general, DREE from a given cpx-melt partitioning experiment can be quantitatively described by the lattice strain model [1]. Attempts have been made to parameterize DREE between cpx and melt as a function of P, T, cpx and melt compositions [1]. However, the previous model [1] was based on limited partitioning data, many of which were determined by electron microprobe and some of the experiments might not approach equilibrium, and therefore may not provide accurate prediction. Here, we analyze published REE partitioning data between cpx and basaltic melts, and focus on data obtained by ion probe and LA-ICP-MS and experiments close to equilibrium. We use the nonlinear regression method to parameterize key partitioning parameters in the lattice strain model (D0, r0 and E) as functions of P, T and compositions of cpx and melt. We find that D0 positively correlates with AlIV and MgM2 in cpx, negatively correlates with H2O in the melt and T. Hence variations in DREE are determined by cpx composition, T and H2O in the melt. r0 negative correlates with AlVI and MgM2 in cpx, whereas E and r0 positively correlate with each other. As an application, we examine REE fractionation along a mantle adiabat. We calculate the cpx compositions and H2O contents in the melt during near-fractional melting along the mantle adiabat using pHMELTS [2-3] and for several choices of mantle source composition (DMM, PM and EM) and mantle potential temperature (Tp = 1300oC and 1400oC). As cpx has low Al and Mg abundances at high temperatures during melting in the garnet stability field, REEs are more incompatible in cpx. Melting of a hydrous mantle occurs deeper (in garnet stability field), and produces small-degree melts enriched in H2O. Consequently, REE would be highly incompatible in cpx at the beginning of melting, and become less incompatible as the hydrous melt segregated from the residual mantle. Our model calculations show that DREE in cpx display very small variations during melting in spinel lherzolite regime at a given Tp. This is due to the competing effect between T and cpx composition. Melting in spinel lherzolite regime at higher Tp could generate D values slightly lower than those at lower Tp because the effect of cpx composition is overwhelmed by the temperature effect. At a given Tp, a set of constant D could be used to accurately model adiabatic mantle melting in spinel lherzolite regime, if the major element compositions of residual cpx from pHMELTS [2-3] can be taken as exact. [1] Wood and Blundy (1997) CMP 129, 166-181. [2] Ghiorso et al. (2002) G3, doi:10.1029/2001GC000217. [3] Asimow et al. (2004) G3, doi:10.1029/2003GC000568.

Sun, C.; Liang, Y.

2010-12-01

358

Comprehensive Characterization Of Ultrafine Particulate Emission From 2007 Diesel Engines: PM Size Distribution, Loading And Indidividual Particle Size And Composition.  

NASA Astrophysics Data System (ADS)

The strong absorption of solar radiation by black carbon (BC) impacts the atmospheric radiative balance in a complex and significant manner. One of the most important sources of BC is vehicular emissions, of which diesel represents a significant fraction. To address this issue the EPA has issues new stringent regulations that will be in effect in 2007, limiting the amount of particulate mass that can be emitted by diesel engines. The new engines are equipped with aftertreatments that reduce PM emissions to the point, where filter measurements are subject to significant artifacts and characterization by other techniques presents new challenges. We will present the results of the multidisciplinary study conducted at the Cummins Technical Center in which a suite of instruments was deployed to yield comprehensive, temporally resolved information on the diesel exhaust particle loadings and properties in real-time: Particle size distributions were measured by Engine Exhaust Particle Sizer (EEPS) and Scanning Mobility Particle Sizer (SMPS). Total particle diameter concentration was obtained using Electrical Aerosol Detector (EAD). Laser Induced Incandescence and photoacoustic techniques were used to monitor the PM soot content. Single Particle Laser Ablation Time-of- flight Mass Spectrometer (SPLAT) provided the aerodynamic diameter and chemical composition of individual diesel exhaust particles. Measurements were conducted on a number of heavy duty diesel engines operated under variety of operating conditions, including FTP transient cycles, ramped-modal cycles and steady states runs. We have also characterized PM emissions during diesel particulate filter regeneration cycles. We will present a comparison of PM characteristics observed during identical cycles, but with and without the use of aftertreatment. A total of approximately 100,000 individual particles were sized and their composition characterized by SPLAT. The aerodynamic size distributions of the characterized particles were between 50 and 300 nm, depending on engine operating conditions and particle composition. We will show that while the drastically reduced diesel PM emissions often render the PM filter measurements inadequate due to organic vapor artifacts SPLAT demonstrated its capability to provide real-time information on size and composition of individual diesel exhaust particles as function of engine operating conditions with better than 1 minute resolution.

Zelenyuk, A.; Cuadra-Rodriguez, L. A.; Imre, D.; Shimpi, S.; Warey, A.

2006-12-01

359

Carbon, nitrogen and sulfur in lunar fines 15012 and 15013 - Abundances, distributions and isotopic compositions  

NASA Technical Reports Server (NTRS)

Lunar fines 15012,16 and 15013,3 were analyzed by stepwise pyrolysis and acid hydrolysis as well as complete combustion in oxygen to determine carbon, nitrogen and sulfur. In addition, hydrogen was analysed during pyrolysis as well as during hydrolysis. By comparison of the distribution frequencies of C, N, S, H2 and Fe with He-4, considered to have arisen from solar wind contribution, it is concluded that nitrogen and hydrogen have largely a solar origin. Carbon has a significant solar contribution, and metallic iron may have resulted from solar wind interaction with ferrous minerals on the lunar surface. Sulfur probably has a predominantly lunar origin. There is no direct evidence for meteorotic contribution to these samples. Solar wind interaction also has a marked effect on the stable isotope distribution of C-13/C-12, N-15/N-14, and S-34/S-32. In all cases, the heavy isotope was most enriched in the smallest grain-size fraction.

Chang, S.; Lawless, J.; Romiez, M.; Kaplan, I. R.; Petrowski, C.; Sakai, H.; Smith, J. W.

1974-01-01

360

Composition and size distribution of submicrometer aerosol particles observed on Mt. Fuji in the volcanic plumes from Miyakejima  

NASA Astrophysics Data System (ADS)

An aerosol observation campaign was conducted at the summit of Mt. Fuji (at an altitude of 3776 m), which is located 170 km northwest of Miyakejima. Individual aerosol particles were collected with an electrostatic aerosol sampler and the number-size distribution and composition were examined by electron microscopy. Number-size distributions were measured with the combination of a diffusion battery (DB) and a condensation particle counter. Sulfate and sulfur dioxide concentrations were also determined. During the first half of the campaign (13-15 September 2000), high number fractions of sulfuric-acid containing particles with a mode radius around 0.06 ?m were observed in the radius range of 0.02-0.2 ?m coincident with a humid maritime air mass originated from the south. Sulfate and sulfur dioxide also showed high concentrations in this period. These results suggested that the volcanic plumes of Miyakejima were transported up to the summit of Mt. Fuji. Number-size distributions determined by electron microscope were consistent with those derived using the DB. During the later half of the experiment (18-20 September), low fractions of sulfuric-acid containing particles represented only a small fraction of the total particle number, coincident with a dry continental air mass originating from the west.

Naoe, Hiroaki; Heintzenberg, Jost; Okada, Kikuo; Zaizen, Yuji; Hayashi, Kazuhiko; Tateishi, Takahiro; Igarashi, Yasuhito; Dokiya, Yukiko; Kinoshita, Kisei

361

The distribution and stable carbon isotopic composition of dissolved organic carbon in estuaries  

Microsoft Academic Search

The distributions of dissolved organic carbon (DOC) and the natural carbon isotope ratio of DOC (DO13C) in estuaries reflect the predominant sources and sinks of organic matter from both allochthonous and autochthonous origins.\\u000a The traditional view is that DOC in land-margin ecosystems reflects mainly the mixing of land-derived and oceanic DOC. However,\\u000a this view is not consistent with the bulk

Bruce Peterson; Brian Fry; Meredith Hullar; Susan Saupe; Richard Wright

1994-01-01

362

The evolution and distribution of life in the Precambrian eon-global perspective and the Indian record.  

PubMed

The discovery of Precambrian microfossils in 1954 opened a new vista of investigations in the field of evolution of life. Although the Precambrian encompasses 87% of the earth's history, the pace of organismal evolution was quite slow. The life forms as categorised today in the three principal domains viz. the Bacteria, the Archaea and the Eucarya evolved during this period. In this paper, we review the advancements made in the Precambrian palaeontology and its contribution in understanding the evolution of life forms on earth. These studies have enriched the data base on the Precambrian life. Most of the direct evidence includes fossil prokaryotes, protists, advanced algal fossils, acritarchs, and the indirect evidence is represented by the stromatolites, trace fossils and geochemical fossils signatures. The Precambrian fossils are preserved in the form of compressions, impressions, and permineralized and biomineralized remains. PMID:20009270

Sharma, M; Shukla, Y

2009-11-01

363

Species composition and temporal distribution of mosquito populations in Ibadan, Southwestern Nigeria  

PubMed Central

Nigeria has a high burden of vector borne diseases such as malaria and lymphatic filariasis (LF). This study aimed to determine the species composition of mosquitoes in Ibadan, Southwest Nigeria as well as determine their role in malaria and LF transmission. Adult mosquitoes were collected by Pyrethrum Spray Catch (PSC) and identified and graded according to their abdominal conditions. The mosquitoes were dissected to determine the parity status and to check for microfilariae of Wuchereria bancrofti. The presence of circumsporozoite protein of Plasmodium falciparum was examined using ELISA. A total of 1600 mosquitoes were collected of which 31 (1.9%) were Anopheles gambiae s.l. while 1756 (98%) were Culex sp. None of the mosquitoes examined was positive for Plasmodium falciparum and Wuchereria bancrofti. The lack of adequate sanitary conditions in the area could be responsible for the large number of mosquitoes collected. Health education could help in sensitizing the inhabitants. PMID:25520960

Okorie, Patricia N.; Popoola, K.O.K.; Awobifa, Olayemi M.; Ibrahim, Kolade T.; Ademowo, George O.

2014-01-01

364

Calculations using the helical filamentary structure for current distributions of a six around one superconducting strand cable and a multifilamentary composite  

NASA Astrophysics Data System (ADS)

The current and magnetic-field distributions within a twisted six around one (6-1) superconducting strand cable and a twisted simple superconducting multifilamentary composite have been studied with the assumption that the current distribution within each strand or each filament is uniform. For this purpose, the vector potential and the magnetic field due to a helical conductor with a circular cross section is calculated from the numerical integration of the analytical expression for a helical thin conductor. The current distributions among each strand or each filament are obtained by minimizing the magnetic energy for the case of the insulated strands or filaments, and by requiring zero magnetic flux enclosed between any pair of strands or filaments for the case of the noninsulated strands or filaments. For the case of the untwisted insulated strands or filaments, it is confirmed that the calculated results coincide with those due to the inductance. The screening circulation currents among strands within a multistrand cable or filaments within a composite are obtained as the difference between the current distributions for the case with the noninsulated strand or filament and for the case with the imaginarily insulated strand or filament. As a result, it is revealed that the negative current in the inner strands or filaments is a universal feature of the current distributions for superconducting multistrand cables and multifilamentary composites during the current sweep. Finally, the magnetic field distributions of a twisted 6-1 superconducting strand cable and a twisted simple superconducting multifilamentary composite have been obtained.

Tominaka, Toshiharu

2004-11-01

365

Distribution, abundance and carbon isotopic composition of gaseous hydrocarbons in Big Soda Lake, Nevada - An alkaline, meromictic lake  

NASA Technical Reports Server (NTRS)

The study of the distribution and isotopic composition of low molecular weight hydrocarbon gases at the Big Soda Lake, Nevada, has shown that while neither ethylene nor propylene were found in the lake, ethane, propane, isobutane and n-butane concentrations all increased with water column depth. It is concluded that methane has a biogenic origin in both the sediments and the anoxic water column, and that C2-C4 alkanes have biogenic origins in the monimolimnion water and shallow sediments. The changes observed in delta C-13/CH4/ and CH4/(C2H6 + C3H8) with depth in the water column and sedimeents are probably due to bacterial processes, which may include anaerobic methane oxidation and different rates of methanogenesis, and C2-to-C4 alkane production by microorganisms.

Oremland, R. S.; Des Marais, D. J.

1983-01-01

366

Composition, distribution and sources of polycyclic aromatic hydrocarbons in sediments of the Gulf of Trieste, Northern Adriatic Sea.  

PubMed

The composition, distribution and the sources of polycyclic aromatic hydrocarbons (PAHs) in the surficial sediments of the Gulf of Trieste were investigated. To document the spatial PAH input, surficial sediment samples from 17 locations throughout the Gulf were analysed. The total PAH load determined in the surficial sediment samples are between 30 and 600 ng g-1, and were the highest in the immediate vicinity of the Port of Trieste. The PAH contents decline rapidly with increasing distance from the shore. The ratios of methylphenanthrenes/phenanthrene and methylpyrene/pyrene are sensitive indicators of the origin of PAH pollution in the Gulf which is mostly pyrolitic. The phenanthrene/anthracene ratio was used to determine the approximate location and distance from the source of PAH pollution, while 1-methy 1-7-isopropylphenanthrene (retene) was used as indicator for forest fires. A sediment depth profile indicates a major increase in the PAH concentrations after the First World War. PMID:11382982

Notar, M; Leskovsek, H; Faganeli, J

2001-01-01

367

Characteristic features of first and second moments of fission-fragment energy distribution as functions of nucleon composition  

SciTech Connect

We discuss the totality of experimental data obtained at the Alma-Ata isochronous cyclotron for the mean kinetic energy /similar to/(E/sub k/) and energy dispersion sigma/sub E//sup 2/ for nuclei with Z = 68--85, A = 165--213. The dependences of these first two moments of the E/sub k/ distribution as functions of the nucleon composition of the fissioning nucleus are found to have a new feature: a ''break'' in the curve in the vicinity of (Z/sup 2//A/sup 1//sup ///sup 3/)/sub 0/approx. =1000. This effect is due to the fact that the descent-to-scission stage is absent for fissioning nuclei with Z/sup 2//A/sup 1//sup ///sup 3/<(Z/sup 2//A/sup 1//sup ///sup 3/)/sub 0/.

Gruzintsev, E.N.; Itkis, M.G.; Mul'gin, S.I.; Okolovich, V.N.; Rusanov, A.Y.; Serdyuk, O.I.; Smirenkin, G.N.; Subbotin, M.I.

1988-08-01

368

Monitoring photooxidation-induced dynamic changes in the volatile composition of extended shelf life bovine milk by PTR-MS.  

PubMed

Exposure of milk to light leads to photooxidation and the development of off-flavours. To follow these reactions, semi-skimmed (1.5% fat) and whole (3.8% fat) extended shelf life (ESL) bovine milk samples were exposed to fluorescent light for up to 20?h at room temperature, and the volatiles in the samples' headspace were measured in real time using proton-transfer-reaction mass spectrometry (PTR-MS). Compounds tentatively identified as methanethiol, acetone/propanal, pentanal/octanal/nonanal/1-octen-3-ol, hexanal, diacetyl, dimethyl disulphide, heptanal and benzaldehyde displayed dynamic release profiles relating to the changes occurring in milk upon exposure to light. PMID:25230193

Beauchamp, Jonathan; Zardin, Erika; Silcock, Patrick; Bremer, Phil J

2014-09-01

369

Properties of wine polymeric pigments formed from anthocyanin and tannins differing in size distribution and subunit composition.  

PubMed

To explore the effect of tannin composition on pigment formation, model ferments of purified 3-O-monoglucoside anthocyanins (ACN) were conducted either alone or in the presence of two different tannins. Tannins were isolated from grape seeds (Sd) or skins (Sk) following exhaustive extraction in 70% v/v acetone. The Sd and Sk tannin fractions had a mean degree of polymerization of 5.2 and 25.6, respectively. The Sd fraction was highly galloylated, at 22%, but galloylation was <2% in the Sk fraction. The Sk fraction was distinguished by a high proportion of prodelphinidin, at 58%. After a 6 month aging period, polymeric pigments were quantified and their color properties determined following isolation by solid-phase extraction. Wine color and polymeric pigment were highest in the treatment containing ACN+Sd and similar in the ACN+Sk and ACN treatments. The same trend between treatments was observed for total and polymeric nonbleachable pigments. Only minor changes in tannin subunit composition were found following ACN incorporation, but the size distribution of polymeric pigments determined by gel permeation chromatography decreased, in particular for the ACN+Sk treatment. Color incorporation in the higher molecular mass range was lower for ACN+Sk wines than for ACN+Sd wines. Compositional differences between the two tannin fractions may therefore limit the incorporation of ACNs in the colored form. The results suggest that in the ACN+Sk and ACN treatments, the formation of lower molecular mass oligomeric pigments was favored. In polymeric pigments derived from ACNs, the presence of ethyl- and vinyl-linked ACNs to the level of trimers was identified using mass spectrometry. PMID:25356846

Bindon, Keren; Kassara, Stella; Hayasaka, Yoji; Schulkin, Alex; Smith, Paul

2014-11-26

370

Influence of hydraulic regimes on bacterial community structure and composition in an experimental drinking water distribution system.  

PubMed

Microbial biofilms formed on the inner-pipe surfaces of drinking water distribution systems (DWDS) can alter drinking water quality, particularly if they are mechanically detached from the pipe wall to the bulk water, such as due to changes in hydraulic conditions. Results are presented here from applying 454 pyrosequencing of the 16S ribosomal RNA (rRNA) gene to investigate the influence of different hydrological regimes on bacterial community structure and to study the potential mobilisation of material from the pipe walls to the network using a full scale, temperature-controlled experimental pipeline facility accurately representative of live DWDS. Analysis of pyrosequencing and water physico-chemical data showed that habitat type (water vs. biofilm) and hydraulic conditions influenced bacterial community structure and composition in our experimental DWDS. Bacterial community composition clearly differed between biofilms and bulk water samples. Gammaproteobacteria and Betaproteobacteria were the most abundant phyla in biofilms while Alphaproteobacteria was predominant in bulk water samples. This suggests that bacteria inhabiting biofilms, predominantly species belonging to genera Pseudomonas, Zooglea and Janthinobacterium, have an enhanced ability to express extracellular polymeric substances to adhere to surfaces and to favour co-aggregation between cells than those found in the bulk water. Highest species richness and diversity were detected in 28 days old biofilms with this being accentuated at highly varied flow conditions. Flushing altered the pipe-wall bacterial community structure but did not completely remove bacteria from the pipe walls, particularly under highly varied flow conditions, suggesting that under these conditions more compact biofilms were generated. This research brings new knowledge regarding the influence of different hydraulic regimes on the composition and structure of bacterial communities within DWDS and the implication that this might have on drinking water quality. PMID:23182667

Douterelo, I; Sharpe, R L; Boxall, J B

2013-02-01

371

Influence of cow bone particle size distribution on the mechanical properties of cow bone-reinforced polyester composites.  

PubMed

This work was carried out to investigate the influence of cow bone particle size distribution on the mechanical properties of polyester matrix composites in order to consider the suitability of the materials as biomaterials. Cow bone was procured from an abattoir, washed with water, and sun-dried for 4 weeks after which it was crushed with a sledge hammer and was further pulverized with laboratory ball mill. Sieve size analysis was carried out on the pulverized bone where it was sieved into three different sizes of 75, 106, and 300??m sieve sizes. Composite materials were developed by casting them into tensile and flexural tests moulds using predetermined proportions of 2, 4, 6, and 8%. The samples after curing were striped from the moulds and were allowed to be further cured at room temperature for 3 weeks before tensile and flexural tests were performed on them. Both tensile and flexural strength were highly enhanced by 8 wt% from 75??m while toughness was highly enhanced by 6 and 8?wt% from 300??m. This shows that fine particles lead to improved strength while coarse particles lead to improved toughness. The results show that these materials are structurally compatible and are being developed from animal fibre based particle; it is expected to also aid the compatibility with the surface conditions as biomaterials. PMID:24324892

Oladele, Isiaka Oluwole; Adewole, Temitope Akinyemi

2013-01-01

372

Influence of Cow Bone Particle Size Distribution on the Mechanical Properties of Cow Bone-Reinforced Polyester Composites  

PubMed Central

This work was carried out to investigate the influence of cow bone particle size distribution on the mechanical properties of polyester matrix composites in order to consider the suitability of the materials as biomaterials. Cow bone was procured from an abattoir, washed with water, and sun-dried for 4 weeks after which it was crushed with a sledge hammer and was further pulverized with laboratory ball mill. Sieve size analysis was carried out on the pulverized bone where it was sieved into three different sizes of 75, 106, and 300??m sieve sizes. Composite materials were developed by casting them into tensile and flexural tests moulds using predetermined proportions of 2, 4, 6, and 8%. The samples after curing were striped from the moulds and were allowed to be further cured at room temperature for 3 weeks before tensile and flexural tests were performed on them. Both tensile and flexural strength were highly enhanced by 8 wt% from 75??m while toughness was highly enhanced by 6 and 8?wt% from 300??m. This shows that fine particles lead to improved strength while coarse particles lead to improved toughness. The results show that these materials are structurally compatible and are being developed from animal fibre based particle; it is expected to also aid the compatibility with the surface conditions as biomaterials. PMID:24324892

Oladele, Isiaka Oluwole; Adewole, Temitope Akinyemi

2013-01-01

373

Amino Acid Composition, Molecular Weight Distribution and Gel Electrophoresis of Walnut (Juglans regia L.) Proteins and Protein Fractionations  

PubMed Central

As a by-product of oil production, walnut proteins are considered as an additional source of plant protein for human food. To make full use of the protein resource, a comprehensive understanding of composition and characteristics of walnut proteins are required. Walnut proteins have been fractionated and characterized in this study. Amino acid composition, molecular weight distribution and gel electrophoresis of walnut proteins and protein fractionations were analyzed. The proteins were sequentially separated into four fractions according to their solubility. Glutelin was the main component of the protein extract. The content of glutelin, albumin, globulin and prolamin was about 72.06%, 7.54%, 15.67% and 4.73% respectively. Glutelin, albumin and globulin have a balanced content of essential amino acids, except for methionine, with respect to the FAO pattern recommended for adults. SDS-PAGE patterns of albumin, globulin and glutelin showed several polypeptides with molecular weights 14.4 to 66.2 kDa. The pattern of walnut proteins in two-dimension electrophoresis (2-DE) showed that the isoelectric point was mainly in the range of 4.8–6.8. The results of size exclusion chromatogram indicated molecular weight of the major components of walnut proteins were between 3.54 and 81.76 kDa. PMID:24473146

Mao, Xiaoying; Hua, Yufei; Chen, Guogang

2014-01-01

374

The associations of body composition and fat distribution with bone mineral density in elderly Italian men and women.  

PubMed

This study aimed to investigate the associations of body composition and fat distribution with bone mineral density (BMD) in elderly Italian subjects. In 866 women (age 64.2±6.5yr) and 168 men (age 65.1±6.1yr), we measured BMD at lumbar spine, at femur, at the total body, and at the right hand. In all subjects, we also measured sex hormones, 25-hydroxyvitamin D, bone markers, and calcium intake. In both men and women, all body composition parameters had significant positive correlations with BMD at all sites after adjusting for age only; after adjusting also for body weight only lean mass (LM) remained positively associated with BMD at all sites except BMD at lumbar spine. In males, LM was associated with BMD at all sites, whereas android fat was associated with BMD at lumbar spine, at femur, and at whole body. In females, fat mass (FM) was positively and age inversely associated with BMD at all sites, whereas gynoid fat and alkaline phosphatase were inversely associated with BMD at lumbar spine and at femur. In conclusion, the role of LM seems more important in males, whereas in women the role of FM prevails with negative associations between gynoid fat and BMD. PMID:22575590

Gonnelli, Stefano; Caffarelli, Carla; Tanzilli, Loredana; Alessi, Chiara; Tomai Pitinca, Maria Dea; Rossi, Stefania; Campagna, Maria Stella; Nuti, Ranuccio

2013-01-01

375

Spatial distribution and temporal variation of Microcystis species composition and microcystin concentration in Lake Biwa.  

PubMed

Spatial and temporal variation in Microcystis species composition and microcystin concentration, quantified by enzyme-linked immunosorbent assay and high-performance liquid chromatography, were investigated during a 3-year period (1998-2000) in the Northern Basin of Lake Biwa. The Northern Basin generally had a concentration of 5 microg L(-1) or less, except at station 1 (Nagahama Bay) from July to October during the study period. The maximum concentration at station 1 was 22.7, 35.9, and 22.0 microg L(-1) in October of 1998, 1999, and 2000, respectively. Eleven species of cyanobacteria were observed: Microcystis aeruginosa, M. ichthyoblabe, M. novacekii, M. wesenbergii, Oscillatoria raciborskii, Anabaena oumiana, A. affinis, A. flos-aquae, A. ucrainica, A. smithii, and A. crassa. Of these, M. aeruginosa and M. wesenbergii were the main components observed. A high concentration of microcystin in the lake water was mostly a result of variation in the relative amount of toxic M. aeruginosa rather than of the total Microcystis cell number. This was supported by the analytical results for isolated strains. Microcystis spp. cell density in the Northern Basin appeared to increase gradually over the course of the study. This is the first study to have surveyed the Northern Basin of Lake Biwa, which supplies drinking water to 14 million people and is the largest lake in Japan. PMID:15892068

Ozawa, Kazuhiko; Fujioka, Hiroki; Muranaka, Minoru; Yokoyama, Atsushi; Katagami, Yukimi; Homma, Takamitsu; Ishikawa, Kanako; Tsujimura, Shigeo; Kumagai, Michio; Watanabe, Mariyo F; Park, Ho-Dong

2005-06-01

376

Latitudinal distribution of nitrogen isotopic composition in suspended particulate organic matter in tropical/subtropical seas.  

PubMed

Natural nitrogen isotopic composition (?(15)N) of suspended particulate organic matter (POM) and nitrogen fixation rates via (15)N(2) assay were measured in surface waters along 120° E from 30° N to 30° S in the Asian marginal seas (the East/South China Seas and the Sulu/Celebes/Java Seas) and the northeastern Indian Ocean in November-December 2005 and March 2006. The POM ?(15)N values ranged from-1.8 to 12.2‰ with an average of 3.6‰ and showed a decreasing trend towards the equator in both hemispheres. In parallel, the measured N(2) fixation rates showed an increase from the subtropical to the tropical seas. This implies that a higher contribution of (15)N-depleted POM was derived from enhanced N(2) fixation. Water temperature and the stability of water column were partly responsible for the observed variations in nitrogen fixation. The large-scale spatial variations in suspended POM ?(15)N and N(2) fixation rates suggest that the suspended POM ?(15)N may be a potential indicator of nitrogen fixation in surface waters in tropical/subtropical seas. PMID:22004405

Zhang, Run; Chen, Min; Ma, Qiang; Cao, Jianping; Qiu, Yusheng

2011-12-01

377

Electrical properties of polypropylene-based composites controlled by multilayered distribution of conductive particles.  

PubMed

Materials consisting of alternating layers of pure polypropylene (PP) and carbon black filled polypropylene (PPCB) were fabricated in this work. The electrical behaviors of the multilayered composites were investigated from two directions: (1) Parallel to interfaces. The confined layer space allowed for a more compact connection between CB particles, while the conductive pathways tended to be broken up with increasing number of layers leading to a distinct enhancement of the electrical resistivity due to the separation of insulated PP layers. (2) Vertical to interfaces. The alternating assemblies of insulated and conductive layers like a parallel-plate capacitor made the electrical conductivity become frequency dependent. Following the layer multiplication process, the dielectric permittivity was significantly enhanced due to the accumulation of electrical charges at interfaces. Thus, as a microwave was incident on the dielectric medium, the interfacial polarization made the main contribution to inherent dissipation of microwave energy, so that the absorbing peak became strengthened when the material had more layers. Furthermore, the layer interfaces in the multilayered system were also effective to inhibit the propagation of cracks in the stretching process, leading to a larger elongation at the break than that of the PP/CB conventional system, which provided a potential route to fabricate electrical materials with optimal mechanical properties. PMID:25549245

Gao, Wanli; Zheng, Yu; Shen, Jiabin; Guo, Shaoyun

2015-01-28

378

NASA technology utilization survey on composite materials  

NASA Technical Reports Server (NTRS)

NASA and NASA-funded contractor contributions to the field of composite materials are surveyed. Existing and potential non-aerospace applications of the newer composite materials are emphasized. Economic factors for selection of a composite for a particular application are weight savings, performance (high strength, high elastic modulus, low coefficient of expansion, heat resistance, corrosion resistance,), longer service life, and reduced maintenance. Applications for composites in agriculture, chemical and petrochemical industries, construction, consumer goods, machinery, power generation and distribution, transportation, biomedicine, and safety are presented. With the continuing trend toward further cost reductions, composites warrant consideration in a wide range of non-aerospace applications. Composite materials discussed include filamentary reinforced materials, laminates, multiphase alloys, solid multiphase lubricants, and multiphase ceramics. New processes developed to aid in fabrication of composites are given.

Leeds, M. A.; Schwartz, S.; Holm, G. J.; Krainess, A. M.; Wykes, D. M.; Delzell, M. T.; Veazie, W. H., Jr.

1972-01-01

379

Discover Life  

NSDL National Science Digital Library

Discover Life provides information on the taxonomy, natural history, distribution, abundance, and ecology of the world's flora and fauna. Site materials include a database of all known plants and animals, featuring photos, maps, identification guides, and facts about each organism, arranged by group: amphibians, reptiles, mammals, plants, insects, and others. The site's "Tree of Life" is a diagram (phylogenetic tree) that graphically displays the relationships between major groups of living organisms. Its IDnature guides are interactive identification resources that let users select and search on physical attributes of an organism to obtain potential matches with known species. There is also a global mapping tool that lets users generate distribution maps of individual or multiple species. The education page provides images, maps, lesson plans, and other resources for teachers and students. Other materials include information on invasive species, information on specimen labels, a search tool for locating organisms, information on the Discover Life project, and links to related web sites.

380

The microscopic state of the solar wind--links between composition, velocity distributions and waves  

SciTech Connect

An overview is given of the microscopic state of the solar wind with emphasis on recent Ulysses high-latitude observations and previous Helios in-ecliptic observations. Emphasis is placed on the connection of interplanetary kinetic-scale phenomena with their generating microscopic processes in the corona. The fast streams seem to consist of mesoscale pressure-balanced magnetic flux tubes, reminiscent of the supergranular or smaller structures building the open corona, from which copious Alfven waves emanate. The wind from the magnetically structured and active corona shows considerable abundance and ionization state variations. Some modelling attempts to explain the observed element fractionation are mentioned. The nonthermal particle features, such as proton-ion differential streaming, ion beams, temperature anisotropies, and skewed electron distributions associated with collisionless heat conduction, and the related wave-particle interactions are discussed.

Marsch, E. [Max-Planck-Institut fuer Aeronomie, D-37191 Katlenburg-Lindau (Germany)

1996-07-20

381

Abundance, distribution, and isotopic composition of particulate black carbon in the northern Gulf of Mexico  

NASA Astrophysics Data System (ADS)

exists increasing evidence supporting the important role of black carbon in global carbon cycles. Particulate black carbon (PBC) is allochthonous and has distinct reactivities compared to the bulk particulate organic carbon (tot-POC) in marine environments. However, the abundance, geochemical behavior of PBC and its importance in oceanic carbon budget remain poorly understood. Here we report the abundance, distribution, and stable isotopic signatures of BC derived from the chemo-thermal oxidation (CTO-375) method (BCCTO) in the Gulf of Mexico. Our results show that BCCTO abundance decreased from shelf to basin, and more than a half of riverine BCCTO could be removed over the shelf. Moreover, BCCTO is much more refractory compared to the tot-POC and has ?13C values lower than those of BC-excluded POC. These results highlight the significance of PBC in marine carbon cycles and potentially suggest the need for a new end-member term in quantifying POC sources in the ocean.

Yang, Weifeng; Guo, Laodong

2014-11-01

382

The Effect of Community on Distributed Bio-inspired Service Composition  

NASA Astrophysics Data System (ADS)

The Future Internet is expected to cater for both a larger number and variety of services, which in turn will make basic tasks such as service lifecycle management increasingly important and difficult. At the same time, the ability for users to efficiently discover and compose these services will become a key factor for service providers to differentiate themselves in a competitive market. In previous work, we examined the effect adding biological mechanisms to services had on service management and discovery. In this paper we examine the effects of community on services, specifically in terms of composing services in a distributed fashion. By introducing aspects of community we aim to demonstrate that services can further improve their sustainability and indeed their efficiency.

Carroll, Raymond; Balasubramaniam, Sasitharan; Botvich, Dmitri; Donnelly, William

383

The species composition and seasonal distribution of mosquitoes in vernal pools in suburban Montreal, Quebec.  

PubMed

A study was conducted in the spring and summer of 1998 to determine the invertebrate community in vernal pools on the western portion of the Island of Montreal. This paper examines the mosquitoes (Diptera: Culicidae) found in 10 pools. Fifteen species in 4 genera (Aedes, Anopheles, Culex, and Ochlerotatus) were collected and the seasonal distribution of each species was determined. Ochlerotatus stimulans was the most abundant species. Two peaks occurred in larval abundance, in late April and early July. Larvae were more abundant in the spring; larval density was higher later in the summer. The abundance of mosquitoes in these pools was similar to those found in remote regions of the province. PMID:14710734

Doran, Bruce R; Lewis, David J

2003-12-01

384

Distribution and Compositional Constraints on Subsurface Ice in Arcadia Planitia, Mars  

NASA Astrophysics Data System (ADS)

Knowledge of the present-day quantity and distribution of water ice on Mars can help to understand past Martian climates, and also has implications for future human exploration. Within the northern mid-latitudes, there are many geomorphological features such as ice-exposing impacts (Dundas et al., 2014) and expanded secondary craters (Viola et al., 2014) that are indicative of widespread ice.Impact crater morphology can reveal subsurface structure, such as when terraces form in layered target material (Ormö et al., 2013). We create Digital Terrain Models (DTMs) using the Mars Reconnaissance Orbiter’s HiRISE (High Resolution Imaging Science Experiment) stereo image pairs to measure terrace depths within craters (and thus the depths to the boundary of the subsurface layer). Radar sounding from the SHARAD instrument, also on the Mars Reconnaissance Orbiter, provides an independent mechanism for probing the subsurface and shows an extensive subsurface reflector in Arcadia Planitia (180-225E, 38-50N). Assuming the change in material strengths responsible for the terraces is the same dielectric interface that causes the radar reflectors, combining the terrace depths with radar delay times allows us to determine the radar wave velocity (and thus dielectric constant) of the layer of material between the surface and subsurface reflector.We present results from combining these observational datasets to map the distribution and constrain the dielectric constant of this widespread layer. Preliminary results suggest this decameters-thick layer is relatively pure excess (higher water ice abundances than can fit into the pore spaces of the regolith) ice. We compare our dielectric constant calculations with a 3-component dielectric mixing model to put limits on the porosity and purity of the ice. Understanding the conditions that emplaced and preserved this ice layer is important to improving our understanding of the Martian climate system.

Bramson, Ali M.; Byrne, Shane; Putzig, Nathaniel E.; Mattson, Sarah; Plaut, Jeffrey J.; Holt, John W.

2014-11-01

385

A piezolaminated composite degenerated shell finite element for active control of structures with distributed piezosensors and actuators  

NASA Astrophysics Data System (ADS)

This paper deals with the formulation of a nine-noded piezolaminated degenerated shell finite element for modeling and analysis of multilayer composite general shell structures with bonded/embedded distributed piezoelectric sensors and actuators. The distributed PZT sensors and actuators used in the composite smart structures are relatively thin and could have arbitrary variation of curvatures and thicknesses. They cannot be modeled with shell elements based on curvilinear shell theories which would need the specification of constant shell curvatures and thicknesses. Modeling them with piezo finite elements available in popular commercial codes like ABAQUS, ANSYS, MARC, etc, would need relatively greater computational effort as they are based on solid element formulation. In view of these, the present proposed degenerated piezoelectric shell element would be a better choice giving good computational accuracy and efficiency. The main advantage of a degenerate shell element is that it is not based on any shell theories and is applicable over a wide range of curvatures and thicknesses. This element is developed by using the degenerate solid approach based on Reissner-Mindlin assumptions which allow the shear deformation and rotary inertia effect to be considered and the 3D field is reduced to a 2D field in terms of mid-surface nodal variables. Uniformly reduced integration is carried out to overcome membrane locking and shear locking and the numerical integration is carried out in all three directions to obtain accurate results. The present element has 45 elastic degrees of freedom and 10 electric degrees of freedom per piezoelectric layer in the element. The potential induced due to bending deformation is more accurately represented by assuming quadratic variation of the electric potential through the thickness of each piezoelectric layer. This is achieved by interpolating using nodal mid-plane electric potentials and one electric degree of freedom representing the potential difference between the top and bottom surfaces of the piezoelectric layer. Few case studies of composite general shells with piezoelectric sensors and actuators have been considered by modeling them with the above elements and the active vibration control performance has been studied using linear quadratic Gaussian (LQG) control.

Balamurugan, V.; Narayanan, S.

2008-06-01

386

Diversity, composition, and geographical distribution of microbial communities in California salt marsh sediments  

USGS Publications Warehouse

The Pacific Estuarine Ecosystem Indicators Research Consortium seeks to develop bioindicators of toxicant-induced stress and bioavailability for wetland biota. Within this framework, the effects of environmental and pollutant variables on microbial communities were studied at different spatial scales over a 2-year period. Six salt marshes along the California coastline were characterized using phospholipid fatty acid (PLFA) analysis and terminal restriction fragment length polymorphism (TRFLP) analysis. Additionally, 27 metals, six currently used pesticides, total polychlorinated biphenyls and polycyclic aromatic hydrocarbons, chlordanes, nonachlors, dichlorodiphenyldichloroethane, and dichlorodiphenyldichloroethylene were analyzed. Sampling was performed over large (between salt marshes), medium (stations within a marsh), and small (different channel depths) spatial scales. Regression and ordination analysis suggested that the spatial variation in microbial communities exceeded the variation attributable to pollutants. PLFA analysis and TRFLP canonical correspondence analysis (CCA) explained 74 and 43% of the variation, respectively, and both methods attributed 34% of the variation to tidal cycles, marsh, year, and latitude. After accounting for spatial variation using partial CCA, we found that metals had a greater effect on microbial community composition than organic pollutants had. Organic carbon and nitrogen contents were positively correlated with PLFA biomass, whereas total metal concentrations were positively correlated with biomass and diversity. Higher concentrations of heavy metals were negatively correlated with branched PLFAs and positively correlated with methyl- and cyclo-substituted PLFAs. The strong relationships observed between pollutant concentrations and some of the microbial indicators indicated the potential for using microbial community analyses in assessments of the ecosystem health of salt marshes. Copyright ?? 2006, American Society for Microbiology. All Rights Reserved.

Cordova-Kreylos, A. L.; Cao, Y.; Green, P.G.; Hwang, H.-M.; Kuivila, K.M.; LaMontagne, M.G.; Van De Werfhorst, L. C.; Holden, P.A.; Scow, K.M.

2006-01-01

387

Diversity, Composition, and Geographical Distribution of Microbial Communities in California Salt Marsh Sediments  

PubMed Central

The Pacific Estuarine Ecosystem Indicators Research Consortium seeks to develop bioindicators of toxicant-induced stress and bioavailability for wetland biota. Within this framework, the effects of environmental and pollutant variables on microbial communities were studied at different spatial scales over a 2-year period. Six salt marshes along the California coastline were characterized using phospholipid fatty acid (PLFA) analysis and terminal restriction fragment length polymorphism (TRFLP) analysis. Additionally, 27 metals, six currently used pesticides, total polychlorinated biphenyls and polycyclic aromatic hydrocarbons, chlordanes, nonachlors, dichlorodiphenyldichloroethane, and dichlorodiphenyldichloroethylene were analyzed. Sampling was performed over large (between salt marshes), medium (stations within a marsh), and small (different channel depths) spatial scales. Regression and ordination analysis suggested that the spatial variation in microbial communities exceeded the variation attributable to pollutants. PLFA analysis and TRFLP canonical correspondence analysis (CCA) explained 74 and 43% of the variation, respectively, and both methods attributed 34% of the variation to tidal cycles, marsh, year, and latitude. After accounting for spatial variation using partial CCA, we found that metals had a greater effect on microbial community composition than organic pollutants had. Organic carbon and nitrogen contents were positively correlated with PLFA biomass, whereas total metal concentrations were positively correlated with biomass and diversity. Higher concentrations of heavy metals were negatively correlated with branched PLFAs and positively correlated with methyl- and cyclo-substituted PLFAs. The strong relationships observed between pollutant concentrations and some of the microbial indicators indicated the potential for using microbial community analyses in assessments of the ecosystem health of salt marshes. PMID:16672478

Córdova-Kreylos, Ana Lucía; Cao, Yiping; Green, Peter G.; Hwang, Hyun-Min; Kuivila, Kathryn M.; LaMontagne, Michael G.; Van De Werfhorst, Laurie C.; Holden, Patricia A.; Scow, Kate M.

2006-01-01

388

Spatial distribution of summertime particulate matter and its composition in Greece  

NASA Astrophysics Data System (ADS)

A field campaign was conducted in Greece during the summer of 2012 (8 June - 26 July) to investigate ambient particulate matter (PM) levels, chemical composition and contribution of regional and local sources. Simultaneous collection of PM1, PM2.5 and PM10 samples from seven different sampling sites in Greece were collected, two sites in Athens - Ag. Paraskevi Demokritos campus (suburban background), - Penteli (National Observatory of Athens NOA premises, suburban background), one in Thessaloniki (suburban background), two stations in Patras - Centre (urban background), - suburbs/ICE FORTH campus (suburban background), one at Finokalia in the northeast part of Crete (remote background) and the last one at the Navarino Environmental Observatory (NEO) in southwest Peloponnese (rural background). These different background sites were chosen in order to estimate both the local emissions sources and the long range transport. A suite of continuous/online instruments were deployed in selected sites including an Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF AMS), an Aerosol Chemical Speciation Monitor (ACSM), a Proton Transfer Reaction-Mass Spectrometer (PTR-MS), a Tapered Element Oscillating Microbalance (TEOM), Nephelometers and Aethalometers, gas-phase monitors, etc. The collected filter samples from all sites were analyzed for major ions, OC/EC, metals, etc. The fine PM mass concentration and chemical measurements were quite similar in all sites suggesting significant contributions of transported regional pollution and smaller contributions of local sources. The campaign average PM2.5 ranged from 17.5 to 20 ?g m-3 for the different sites. The Athens suburban site in Demokritos had the highest concentration PM2.5 levels. Sulphates and organics were the major PM2.5 components while nitrates, mineral dust and sea-salt for the coastal areas were also important for the PM10 fraction. The sulphate levels were similar in all sites, while the concentration of the organics and mineral dust were more variable. Most of the organic aerosol was highly oxygenated.

Tsiflikiotou, Maria; Papanastasiou, Dimitris; Zarmpas, Paulos; Paraskevopoulou, Despoina; Diapouli, Evangelia; Kostenidou, Evangelia; Kaltsonoudis, Christos; Bougiatioti, Aikaterini; Theodosi, Christina; Kouvarakis, George; Liakakou, Eleni; Vassilatou, Vassiliki; Siakavaras, Dimitris; Biskos, George; Eleftheriadis, Konstantinos; Gerasopoulos, Evangelos; Mihalopoulos, Nikos; Pandis, Spyros

2014-05-01

389

Lipid composition and vertical distribution of bacteria in aerobic sediments of the Venezuela Basin  

NASA Astrophysics Data System (ADS)

Box cores of surface (0 to 30-cm) sediments from carbonate, hemipelagic, and turbidite sediment types of the deep (3493 to 5039-m) Venezuelan Basin were analyzed to investigate the relationship between the vertical distribution of bacteria, lipids, lipid phosphate, and grain size. The polar lipid fraction was isolated chromatographically and quantified by flame-ionization detection using the Iatroscan TH-10 analyzer. Total bacterial abundance was measured by epifluorescence microscopy in sediments (0 to 20-cm) from the carbonate and turbidite sediments. In all three sediment types investigated, both total and polar lipid concentrations decreased with increasing depth in the sediment. The highest total and polar lipid concentrations were at the sediment-water interface (0 to 2-cm) of hemipelagic sediments (62.0 and 25.7 ?g g -1 dry sediment, respectively) followed by the carbonate and turbidite sediments. A similar decline in lipid phosphate was also observed. Bacterial abundance was > 5 × 10 8 bacteria (per gram dry sediment) at the sediment surface in both sediments examined and over 1 × 10 7 bacteria 20 cm below the sediment-water interface. Polar lipid and lipid phosphate concentrations did not appear to correlate with estimates of bacterial biomass, even in regions where bacteria were apparently the only organisms present.

Harvey, H. Rodger; Richardson, Michael D.; Patton, John S.

1984-04-01

390

Amphiura filiformis (Ophiuroidea: Echinodermata) in the North Sea. Distribution, present and former abundance and size composition  

NASA Astrophysics Data System (ADS)

During the North Sea Benthos Survey undertaken by the ICES Benthos Ecology Working Group in spring 1986, a synoptic inventory was made of the benthos in the southern, central and part of the northern North Sea. The present paper deals with the status of the population of the infaunal ophiuroid Amphiura filiformis on the basis of measurements from 150 stations. A. filiformis was found at all the offshore muddy stations, but densities were generally highest in the shallow area south of the Dogger Bank. Stations with more than 1000 ind·m -2 were mainly situated near the frontiers between turbid and summer-stratified water masses, viz. along the southern border of the Oyster Ground, the southern slope of the Dogger Bank and in the northern part of the Pleistocene Elbe river valley. The size-distributions of A. filiformis show that juveniles were generally scarce at stations with high numbers of adults, whereas highest numbers of juveniles occur at stations with few adults. An unequivocal relation between adults and juveniles was, however, absent. This stresses the importance of other factors involved in recruitment. Comparison between the present and former (1938 and 1950) density of A. filiformis suggests that density has increased in the shallower parts but has remained stable in the deeper northern North Sea. An increase of A. filiformis shallow part of the North Sea could point to an enhanced food supply for the benthos, which may have some relation to the eutrophication in nearshore areas.

Duineveld, G. C. A.; Künitzer, A.; Heyman, R. P.

391

Macrobenthos composition, distribution and abundance within Sungai Pulai estuary, Johor, Malaysia  

NASA Astrophysics Data System (ADS)

Macrobenthos are very useful organisms for monitoring marine environmental and widely use in marine ecology research. They are able to monitor the difference phase in the recovery stage of disturbed sites by appear different species macrobenthos after the cessation of the impact. Univariate and multivariate methods were use to study the macrobenthos community within Sungai Pulai estuary, Johor, Malaysia. Five sub-samples were taken at each sampling sites by using 10 cm diameter corer. Crustaceans were the most abundant at Tanjung Adang (St. 1) and the station of non-seagrass area (St. 2) while polychaetes were the most abundant at Merambong Shoal (St. 3). Higher density of macrobenthos was found at St.3 followed by St. 1 and St. 2. The commonly used population indices such as diversity, richness, evenness and dominance were employed to determine the differences in diversity and abundance of macrobenthos. The diversity, richness and evenness index values showed slight increment from Station 1 to Station 3, while the dominance index decreasing trend from Station 1 to Station 3. A total 21 polychaete families were collected in Sungai Pulai estuary, which was dominated by the Spionidae, Capitellidae and Glyceridae. Cluster (Bray-Curtis similarities) analyses revealed that the Tanjung Adang and Merambong Shoal population were clearly separated from the station non-seagrass. For the time being factors that influence the pattern of distribution of the macrobenthos cannot be determined and subjected to further studies.

Shi, Guan Wan; Min, Lee Di; Ghaffar, Mazlan Abd; Ali, Masni Md; Cob, Zaidi Che

2014-09-01

392

Optimization of stresses in the end-fittings of composite insulators for distribution and transmission lines  

SciTech Connect

This paper addresses the problem of stress calculation and optimization in a FRP (Fiberglass Reinforced Plastic) pultruded rod crimped into a metal end-fitting. This type of assembly is used mainly for suspension and line post insulators. The authors discuss herein some aspects that merit consideration in any given design approach. In many respects FRP pultruded materials are anisotropic. The anisotropy of their elastic constants influences the distribution of stresses while the anisotropy of their mechanical properties (ultimate strengths) limits their load carrying capacity. Finally, the anisotropy of their failure modes governs the progression and the spread of the damage. Each level of anisotropy will be discussed distinctly. Geometrical considerations are also necessary to arrive at an efficient design. Namely, the authors will consider the frictional interactions between the end-fitting inner wall and the rod, then they will present their approach in selecting the appropriate L/D ratio (i.e. the ratio of the end-fitting length over the rod diameter), and finally they will discuss the influence of the compression profile, i.e. the permanent radial displacement imparted to the rod due to the action of the crimping force.

Lanteigne, J.; Lalonde, S.; Tourreil, C. de [Hydro-Quebec, Varennes, Quebec (Canada). Inst. de Recherche d`Hydro

1995-11-01

393

A study on the sensitivities of simulated aerosol optical properties to composition and size distribution using airborne measurements  

NASA Astrophysics Data System (ADS)

We present a flexible framework to calculate the optical properties of atmospheric aerosols at a given relative humidity based on their composition and size distribution. The similarity of this framework to climate model parameterisations allows rapid and extensive sensitivity tests of the impact of uncertainties in data or of new measurements on climate relevant aerosol properties. The data collected by the FAAM BAe-146 aircraft during the EUCAARI-LONGREX and VOCALS-REx campaigns have been used in a closure study to analyse the agreement between calculated and measured aerosol optical properties for two very different aerosol types. The agreement achieved for the EUCAARI-LONGREX flights is within the measurement uncertainties for both scattering and absorption. However, there is poor agreement between the calculated and the measured scattering for the VOCALS-REx flights. The high concentration of sulphate, which is a scattering aerosol with no absorption in the visible spectrum, made the absorption measurements during VOCALS-REx unreliable, and thus no closure study was possible for the absorption. The calculated hygroscopic scattering growth factor overestimates the measured values during EUCAARI-LONGREX and VOCALS-REx by ?30% and ?20%, respectively. We have also tested the sensitivity of the calculated aerosol optical properties to the uncertainties in the refractive indices, the hygroscopic growth factors and the aerosol size distribution. The largest source of uncertainty in the calculated scattering is the aerosol size distribution (?35%), followed by the assumed hygroscopic growth factor for organic aerosol (?15%), while the predominant source of uncertainty in the calculated absorption is the refractive index of organic aerosol (28-60%), although we would expect the refractive index of black carbon to be important for aerosol with a higher black carbon fraction.

Esteve, A. R.; Highwood, E. J.; Morgan, W. T.; Allen, G.; Coe, H.; Grainger, R. G.; Brown, P.; Szpek, K.

2014-06-01

394

Paradata for 'Distribution, Habitat Use and Life History of Stream-dwelling Crayfish in the Spring River Drainage of Arkansas and Missouri with a Focus on the Imperiled Mammoth Spring Crayfish (Orconectes marchandi)'  

NSDL National Science Digital Library

This record contains paradata for the resource 'Distribution, Habitat Use and Life History of Stream-dwelling Crayfish in the Spring River Drainage of Arkansas and Missouri with a Focus on the Imperiled Mammoth Spring Crayfish (Orconectes marchandi)'

395

Composition and distribution of phytoplankton with size fraction results at southwestern east/japan sea  

NASA Astrophysics Data System (ADS)

Abundance and distribution of phytoplankton in seawater at southwestern East/Japan Sea near Gampo were investigated by HPLC analysis of photosynthetic pigments during summer of 1999. Detected photosynthetic pigments were chlorophyll a, b, c1+2 (Chl a, Chl b, Chl c1+2), fucoxanthin (Fuco), prasinoxanthin (Pras), zeaxanthin (Zea), 19’-butanoyloxyfucoxanthin (But-fuco) and beta-carotene (?-Car). Major carotenoid was fucoxanthin (bacillariophyte) and minor carotenoids were Pras (prasinophyte), Zea (cyanophyte) and But-fuco (chrysophyte). Chl a concentrations were in the range of 0.16-8.3/land subsurface chlorophyll maxima were observed at 0-10m at inshore and 30-50 m at offshore. Thermocline and nutricline tilted to the offshore direction showed a mild upwelling condition. Results from size-fraction showed that contribution from nano+picoplankton at Chl a maximum layer was increased from 18% at inshore to 69% at offshore on average. The maximum contribution from nano+picoplankton was found as 87% at St. E4. It was noteworthy that contribution from nano+picoplanktonic crysophytes and green algae to total biomass of phytoplankton was significant at offshore. Satellite images of sea surface temperature indicated that an extensive area of the East/Japan Sea showed lower temperature (<18 °C) but the enhanced Chl a patch was confined to a narrow coastal region in summer, 1999. Exceptionally high flux of low saline water from the Korea/Tsushima Strait seemed to make upwelling weak in summer of 1999 in the study area. Results of comparisons among Chl a from SeaWIFs, HPLC and fluorometric analysis showed that presence of Chl b cause underestimation of Chl a about 30% by fluorometric analysis but overestimation by satellite data about 30-75% compared to HPLC data.

Park, Mi Ok

2006-12-01

396

Composition and distribution of glycosaminoglycans in cultures of human normal and malignant glial cells.  

PubMed Central

The glycosaminoglycans of human cultured normal glial and malignant glioma cells were studied. [35S]Sulphate or [3H]glucosamine added to the culture medium was incorporated into glycosaminoglycans; labelled glycosaminoglycans were isolated by DEAE-cellulose chromatography or gel chromatography. A simple procedure was developed for measurement of individual sulphated glycosaminoglycans in cell-culture fluids. In normal cultures the glycosaminoglycans of the pericellular pool (trypsin-susceptible material), the membrane fraction (trypsin-susceptible material of EDTA-detached cells) and the substrate-attached material consisted mainly of heparan sulphate. The intra- and extra-cellular pools showed a predominance of dermatan sulphate. The net production of hyaluronic acid was low. The accumulation of 35S-labelled glycosaminoglycans in the extracellular pool was essentially linear with time up to 72h. The malignant glioma cells differed in most aspects tested. The total production of glycosaminoglycans was much greater owing to a high production of hyaluronic acid and hyaluronic acid was the major cell-surface-associated glycosaminoglycan in these cultures. Among the sulphated glycosaminoglycans chondroitin sulphate, rather than heparan sulphate, was the predominant species of the pericellular pool. This was also true for the membrane fraction and substrate-attached material. Furthermore, the accumulation of extracellular 35S-labelled glycosaminoglycans was initially delayed for several hours and did not become linear with time until after 24 h of incubation. The glioma cells produced little dermatan sulphate and the dermatan sulphate chains differed from those of normal cultures with respect to the distribution of iduronic acid residues. The observed differences between normal glial and malignant glioma cells were not dependent on cell density; rather they were due to the malignant transformation itself. PMID:687354

Glimelius, B; Norling, B; Westermark, B; Wasteson, A

1978-01-01

397

Revisiting spatial distribution and biochemical composition of calcium-containing crystals in human osteoarthritic articular cartilage  

PubMed Central

Introduction Calcium-containing (CaC) crystals, including basic calcium phosphate (BCP) and calcium pyrophosphate dihydrate (CPP), are associated with destructive forms of osteoarthritis (OA). We assessed their distribution and biochemical and morphologic features in human knee OA cartilage. Methods We prospectively included 20 patients who underwent total knee replacement (TKR) for primary OA. CaC crystal characterization and identification involved Fourier-transform infra-red spectrometry and scanning electron microscopy of 8 to 10 cartilage zones of each knee, including medial and lateral femoral condyles and tibial plateaux and the intercondyle zone. Differential expression of genes involved in the mineralization process between cartilage with and without calcification was assessed in samples from 8 different patients by RT-PCR. Immunohistochemistry and histology studies were performed in 6 different patients. Results Mean (SEM) age and body mass index of patients at the time of TKR was 74.6 (1.7) years and 28.1 (1.6) kg/m², respectively. Preoperative X-rays showed joint calcifications (chondrocalcinosis) in 4 cases only. The medial femoro-tibial compartment was the most severely affected in all cases, and mean (SEM) Kellgren-Lawrence score was 3.8 (0.1). All 20 OA cartilages showed CaC crystals. The mineral content represented 7.7% (8.1%) of the cartilage weight. All patients showed BCP crystals, which were associated with CPP crystals for 8 joints. CaC crystals were present in all knee joint compartments and in a mean of 4.6 (1.7) of the 8 studied areas. Crystal content was similar between superficial and deep layers and between medial and femoral compartments. BCP samples showed spherical structures, typical of biological apatite, and CPP samples showed rod-shaped or cubic structures. The expression of several genes involved in mineralization, including human homolog of progressive ankylosis, plasma-cell-membrane glycoprotein 1 and tissue-nonspecific alkaline phosphatase, was upregulated in OA chondrocytes isolated from CaC crystal-containing cartilages. Conclusions CaC crystal deposition is a widespread phenomenon in human OA articular cartilage involving the entire knee cartilage including macroscopically normal and less weight-bearing zones. Cartilage calcification is associated with altered expression of genes involved in the mineralisation process. PMID:24004678

2013-01-01

398

Distribution and composition of suspended biogenic particles in surface waters across Subarctic and Arctic Seas  

NASA Astrophysics Data System (ADS)

Suspended biogenic particles were examined across Subarctic and Arctic Seas during the Canada-Three-Oceans (C3O) program in the summers of 2007 and 2008. Particulate organic carbon (POC) and nitrogen (PON), biogenic silica (bSiO2), and size-fractionated chlorophyll a (chl a) concentrations were measured within the euphotic zone throughout five domains: Eastern Subarctic North Pacific (ESNP), Bering and Chukchi Seas (BE-CH), Southern Beaufort Sea and Canada Basin (BS-CB), Canadian Arctic Archipelago (CAA), and Baffin Bay and Labrador Sea (BB-LS). Despite large variability along the sampling transect and vertically throughout the euphotic zone, domain averages of depth-integrated POC and PON were relatively invariant across the ESNP, BE-CH, CAA, and BB-LS, ranging from 546 to 670 mmol m-2 (POC) and 101 to 154 mmol m-2 (PON), but were much lower in BS-CB (199 and 78 mmol m-2, respectively). In contrast, depth-integrated bSiO2 averages were highest in BE-CH and CAA (>100 mmol m-2), intermediate in ESNP and BB-LS (34-48 mmol m-2), and low in BS-CB (6 mmol m-2). Similarly to the bSiO2 distribution, the biomass of the >5 ?m chl a size-fraction averaged 68-69% of total chl a in BE-CH and CAA, 56% in BB-LS, and 22-23% in ESNP and BS-CB. Ratios of bSiO2:PON averaged 1.10-1.30 in BE-CH and CAA, 0.30-0.34 in ESNP and BB-LS, and 0.08 in BS-CB. This study highlights the relative importance of siliceous phytoplankton such as diatoms in BE-CH and CAA, smaller nonsiliceous cells in BS-CB and ESNP, and a mixed assemblage of variably sized phytoplankton with a less siliceous component in BB-LS.

Wyatt, Shea N.; Crawford, David W.; Wrohan, Ian A.; Varela, Diana E.

2013-12-01

399

Environmental drivers of megafaunal assemblage composition and biomass distribution over mainland and insular slopes of the Balearic Basin (Western Mediterranean)  

NASA Astrophysics Data System (ADS)

The influence of mesoscale physical and trophic variables on deep-sea megafauna, a scale of variation often neglected in deep-sea studies, is crucial for understanding their role in the ecosystem. Drivers of megafaunal assemblage composition and biomass distribution have been investigated in two contrasting areas of the Balearic basin in the NW Mediterranean: on the mainland slope (Catalonian coasts) and on the insular slope (North of Mallorca, Balearic Islands). An experimental bottom trawl survey was carried out during summer 2010, at stations in both sub-areas located between 450 and 2200 m water depth. Environmental data were collected simultaneously: near-bottom physical parameters, and the elemental and isotopic composition of sediments. Initially, data were analysed along the whole depth gradient, and then assemblages from the two areas were compared. Analysis of the trawls showed the existence of one group associated with the upper slope (US=450-690 m), another with the middle slope (MS=1000-1300 m) and a third with the lower slope (LS=1400-2200 m). Also, significant differences in the assemblage composition were found between mainland and insular slopes at MS. Dominance by different species was evident when the two areas were compared by SIMPER analysis. The greatest fish biomass was recorded in both areas at 1000-1300 m, a zone linked to minimum temperature and maximum O2 concentration on the bottom. Near the mainland, fish assemblages were best explained (43% of total variance, DISTLM analysis) by prey availability (gelatinous zooplankton biomass). On the insular slope, trophic webs seemed less complex and were based on vertical input of surface primary production. Decapods, which reached their highest biomass values on the upper slope, were correlated with salinity and temperature in both the areas. However, while hydrographic conditions (temperature and salinity) seemed to be the most important variables over the insular slope, resource availability (gelatinous zooplankton and Calocaris macandreae) predominated and explained 59% of decapod assemblage variation over the mainland slope. Both fish and decapods were linked to net primary production recorded over the mainland 3 months before sampling, while the delay between the input of food from the surface and fish abundance was only 1 month on the insular slope. Our results suggest that trophic relationships over insular slopes probably involve a shorter food chain than over mainland slopes and one that is likely more efficient in terms of energy transfer.

Fanelli, E.; Cartes, J. E.; Papiol, V.; López-Pérez, C.

2013-08-01

400

Effect of Seawater on the Fatigue Life and Failure Distribution of Flood-Lubricated Angular Contact Ball Bearings  

Microsoft Academic Search

Reductions in rolling contact fatigue life as high as 80 percent were observed during flood-lubricated angular-contact ball bearing studies when 1 percent by volume of seawater was added to various lubricants as a contaminant. The lubricants investigated were of different chemical and physical classes and included mineral oils, triaryl phosphate, and two recently developed mineral-oil-base sea-water-emulsifying hydraulic fluids of different

I. M. Felsen; R. W. McQuaid; J. A. Marzani

1972-01-01

401

Plasma and cold sprayed aluminum carbon nanotube composites: Quantification of nanotube distribution and multi-scale mechanical properties  

NASA Astrophysics Data System (ADS)

Carbon nanotubes (CNT) could serve as potential reinforcement for metal matrix composites for improved mechanical properties. However dispersion of carbon nanotubes (CNT) in the matrix has been a longstanding problem, since they tend to form clusters to minimize their surface area. The aim of this study was to use plasma and cold spraying techniques to synthesize CNT reinforced aluminum composite with improved dispersion and to quantify the degree of CNT dispersion as it influences the mechanical properties. Novel method of spray drying was used to disperse CNTs in Al-12 wt.% Si prealloyed powder, which was used as feedstock for plasma and cold spraying. A new method for quantification of CNT distribution was developed. Two parameters for CNT dispersion quantification, namely Dispersion parameter (DP) and Clustering Parameter (CP) have been proposed based on the image analysis and distance between the centers of CNTs. Nanomechanical properties were correlated with the dispersion of CNTs in the microstructure. Coating microstructure evolution has been discussed in terms of splat formation, deformation and damage of CNTs and CNT/matrix interface. Effect of Si and CNT content on the reaction at CNT/matrix interface was thermodynamically and kinetically studied. A pseudo phase diagram was computed which predicts the interfacial carbide for reaction between CNT and Al-Si alloy at processing temperature. Kinetic aspects showed that Al4C3 forms with Al-12 wt.% Si alloy while SiC forms with Al-23wt.% Si alloy. Mechanical properties at nano, micro and macro-scale were evaluated using nanoindentation and nanoscratch, microindentation and bulk tensile testing respectively. Nano and micro-scale mechanical properties (elastic modulus, hardness and yield strength) displayed improvement whereas macro-scale mechanical properties were poor. The inversion of the mechanical properties at different scale length was attributed to the porosity, CNT clustering, CNT-splat adhesion and Al 4C3 formation at the CNT/matrix interface. The Dispersion parameter (DP) was more sensitive than Clustering parameter (CP) in measuring degree of CNT distribution in the matrix.

Bakshi, Srinivasa Rao

402

Linking catalyst composition to chirality distributions of as-grown single-walled carbon nanotubes by tuning Ni(x)Fe(1-x) nanoparticles.  

PubMed

Chirally pure single-walled carbon nanotubes (SWCNTs) are required for various applications ranging from nanoelectronics to nanomedicine. Although significant efforts have been directed towards separation of SWCNT mixtures, including density-gradient ultracentrifugation , chromatography and electrophoresis, the initial chirality distribution is determined during growth and must be controlled for non-destructive, scalable and economical production. Here, we show that the chirality distribution of as-grown SWCNTs can be altered by varying the composition of Ni(x)Fe(1-x) nanocatalysts. Precise tuning of the nanocatalyst composition at constant size is achieved by a new gas-phase synthesis route based on an atmospheric-pressure microplasma. The link between the composition-dependent crystal structure of the nanocatalysts and the resulting nanotube chirality supports epitaxial models and is a step towards chiral-selective growth of SWCNTs. PMID:19767738

Chiang, Wei-Hung; Sankaran, R Mohan

2009-11-01

403

Effects of Gas Composition in the Modified Atmosphere Packaging on the Shelf-life of Longissimus dorsi of Korean Native Black Pigs-Duroc Crossbred during Refrigerated Storage  

PubMed Central

This study was conducted to observe the effects of gas composition in modified atmosphere packaging (MAP) on the shelf-life of Longissimus dorsi of Korean Native Black Pigs-Duroc Crossbred (KNP×D) during refrigerated storage. Muscle sample was obtained from the left side of carcass of seven months old of KNP×D barrow. The sample was sliced into 1 cm in thickness, placed on trays (two slices/tray) and filled with different gas composition, i.e. 0:20:80/O2:CO2:N2 (MAP1), 30:20:50/O2:CO2:N2 (MAP2) and 70:20:10/O2:CO2:N2 (MAP3). Other slices of sample were vacuum packed (VP) as a control. All packs were stored at 5±1°C. At 12 d of storage, pH value of MAP2 and MAP3 were higher (p<0.05) than that of MAP1 and pH value of MAP1 was higher (p<0.05) than that of VP. At 6 d of storage, redness (a*) value of MAP2 and MAP3 were higher (p<0.05) than that of VP and MAP1 and, at 9 and 12 d of storage, redness value of MAP3 was higher (p<0.05) than that of VP, MAP1, and MAP2. At 3, 6, 9, and 12 d of storage, the 2-thiobarbituric acid reactive substances (TBARS) value of MAP3 was higher than that of MAP2 and TBARS value of MAP2 was higher than that of VP and MAP1. At 3, 6, 9, and 12 d of storage, volatile basic nitrogen values of MAP2 and MAP3 were higher (p<0.05) than those of VP and MAP1. At 3 d of storage, total aerobic plate counts of MAP2 and MAP3 were higher (p<0.05) than those of VP and MAP1 and, at 6 d of storage, total aerobic plate counts of MAP3 was higher (p<0.05) than that of MAP1 and MAP2. However, there was no significant different total aerobic plate count among MAP1, MAP2, and MAP3 at 9 and 12 d of storage. There was no significant different total anaerobic plate count among MAP1, MAP2, and MAP3 during storage. It is concluded that the MAP containing 30:20:50/O2:CO2:N2 gas composition (MAP2) might be ideal for better meat quality for KNP×D meat. PMID:25083110

Muhlisin; Panjono; Kim, Dong Soo; Song, Yeong Rae; Lee, Sung-Jin; Lee, Jeong Koo; Lee, Sung Ki

2014-01-01

404

The effect of flow velocity on the distribution and composition of extracellular polymeric substances in biofilms and the detachment mechanism of biofilms.  

PubMed

Flume experiments were conducted to investigate the distribution and composition of extracellular polymeric substances (EPS) in biofilms and the detachment mechanism of biofilms grown under different flow velocity conditions. The results of biofilm growth kinetics showed that the growth trends were coincident with the logistic growth model. The growth kinetics parameters reached their maximum under intermediate velocity (IV) condition. Biofilms exhibited different profiles of EPS composition and distribution, depending on the flow conditions in which the biofilms were grown. The amounts of total polysaccharide and total protein in the thin biofilm (high velocity condition 2 - HV2) were both generally greater than those in the thick biofilm (IV). As compared to the heterogeneous distribution of EPS in the thick biofilms (IV), the EPS in the thin biofilms (HV2) exhibited more homogeneous distribution, and the bound EPS in the thin biofilms (HV2) were much greater than those in the thick biofilms (IV). From the detachment tests, an inverse relationship was observed between the proportion of detached biomass and the value of flow velocity during growth. Biofilms grown under higher velocities showed stronger cohesion than those grown under lower velocities. Therefore, water velocity during biofilm growth conditioned the distribution and composition of EPS, as well as its detachment characteristics under higher shear stress. PMID:24569283

Wang, Chao; Miao, Lingzhan; Hou, Jun; Wang, Peifang; Qian, Jin; Dai, Shanshan

2014-01-01

405

Fatigue reliability evaluation for composite laminates via a direct numerical integration technique  

Microsoft Academic Search

A direct numerical integration technique for evaluating fatigue reliability of composite laminates under varying stress amplitudes is presented. A number of cumulative damage models are adopted to construct the limit state equation for the laminates in the reliability analysis. Existing fatigue life distributions of composite laminates under cyclic stresses of constant amplitude are used in the reliability assessment of the

T. Y. Kam; K. H. Chu; S. Y. Tsai

1998-01-01

406

Influence of the composition and removal characteristics of organic matter on heavy metal distribution in compost leachates.  

PubMed

Compost leachates were collected to investigate the influence of the composition and removal of volatile fatty acids (VFAs), humic-like substances (HSs), and dissolved organic nitrogen (DON) on heavy metal distribution during the leachate treatment process. The results showed that acetic and propionic acids accounted for 81.3 to 93.84% of VFAs, and that these acids were removed by the anaerobic-aerobic process. Humic- and fulvic-like substances were detected by excitation-emission matrix spectroscopy coupled with parallel factor analysis, and their content significantly decreased after the anaerobic and membrane treatments. DON in compost leachates ranged from 26.53 mg L(-1) to 919.46 mg L(-1), comprised of dissolved free amino acids and the protein-like matter bound to humic- and fulvic-like substances, and was removed by the aerobic process. Correlation analysis showed that Mn, Ni, and Pb were bound to VFAs and protein-, fulvic-, and humic-like substances in the leachates. Co was primarily bound to fulvic- and humic-like matter and inorganic sulfurs, whereas Cu, Zn, and Cd interacted with inorganic sulfur. PMID:24595753

He, Xiao-Song; Xi, Bei-Dou; Li, Dan; Guo, Xu-Jing; Cui, Dong-Yu; Pan, Hong-Wei; Ma, Yan

2014-06-01

407

Evaluation of the Fiber Stress Distribution in Aramid/Epoxy Model Composite Using Micro-Raman Spectroscopy and FEM Analysis  

NASA Astrophysics Data System (ADS)

A single-fiber pull-out model composite for an aramid/epoxy system was specially designed to measure the stress distribution of the aramid fiber embedded in the matrix using micro-Raman spectroscopy. The stress transfer length of the fiber obtained was about 400-500 ?m, which was equal to the result of FEM analysis. Just after the initiation and propagation of the fiber/matrix interfacial debonding, the fiber was broken, and the fiber in the matrix had the axial tensile residual stress. The tensile residual axial stress showed the maximum at around the tip of the interfacial debonding. The stress was reduced after the specimen was kept in air at 80°C for 44h, and it became almost equal to zero after being immersed in deionized water at 80°C for 44h. This behavior agreed with the result of FEM analysis, in which the friction coefficient was introduced in the fiber/matrix interface. The axial residual stress was caused by the friction between the fiber and matrix, due to the compressive stress acting between the resin and the fiber, which was caused by the difference of the coefficient of thermal expansion.

Tanaka, Kazuto; Minoshima, Kohji; Yamada, Hideo

408

Mangrove habitat partitioning by Ucides cordatus (Ucididae): effects of the degree of tidal flooding and tree-species composition during its life cycle  

NASA Astrophysics Data System (ADS)

Environmental factors strongly affect mangrove crabs, and some factors modulate population structure and habitat partitioning during the crabs' life cycle. However, the effect of these environmental factors on habitat selection by mangrove crabs is still unknown. We evaluated habitat selection by the mangrove crab Ucides cordatus in mangrove forests with different degrees of predominance of Rhizophora mangle, Laguncularia racemosa or Avicennia schaueriana, two tidal flooding levels (less- and more-flooded), and two biological periods (breeding and non-breeding seasons). Sampling was conducted in four mangrove forests with different influences of these biotic and abiotic parameters. We used the data for sex ratio to explain environmental partitioning by this species. Females predominated in R. mangle mangroves, independently of the biological period (breeding or non-breeding seasons), and males predominated only in the less-flooded L. racemosa mangroves. The flooding level affected the sex ratio of U. cordatus, with a predominance of males in less-flooded mangroves, independently of the biological period; and a gender balance in the more-flooded mangroves only during the breeding season. Outside the breeding season, the largest specimens were recorded in the R. mangle mangroves, but in the breeding season, the largest crabs were recorded in the L. racemosa mangroves with a higher level of flooding. These results suggest that tree-species composition and tidal flooding level can have a significant effect on the habitat partitioning of sexes and sizes of the mangrove crab U. cordatus both during and outside the breeding season.

Wunderlich, A. C.; Pinheiro, M. A. A.

2013-06-01

409

Spatial distribution of the upside-down jellyfish Cassiopea sp. within fringing coral reef environments of the Northern Red Sea: implications for its life cycle  

NASA Astrophysics Data System (ADS)

The zooxanthellate mangrove jellyfish Cassiopea sp. represents a prominent invasive species and a potential bioindicator for nutrient monitoring in coral reefs. However, information about its spatial distribution in combination with abundance, habitat specificity and life cycle elements is barely available. This study, therefore, presents the results of field surveys conducted within four different benthic habitat types (coral reef, seagrass meadow, reef-sand transition and sand flat) in the Northern Red Sea. Cassiopea sp. exhibited a highly patchy distribution within the entire study area with mean abundance of 1.6 ± 0.3 animals m-2 and benthic coverage of 3.2%. Within coral reef habitats, maximum abundance of up to 31 animals m-2 and benthic coverage of up to 20% were detected. Additionally, this study revealed that 65% of all observed Cassiopea specimens were associated with the commensalistic crustacean mysid Idiomysis tsurnamali. Cassiopea abundance and size as well as association patterns with mysids differed between most of the surveyed habitats. In summary, the findings of the present study (1) characterize Cassiopea as one of the key organisms in investigated benthic habitats, (2) indicate active habitat selection by the jellyfish and (3) may hint to an unexplored life cycle of Cassiopea with central role of seagrass meadows providing cues for larval settlement and metamorphosis in the absence of mangroves.

Niggl, Wolfgang; Wild, Christian

2010-12-01

410

Distribution  

Microsoft Academic Search

e're closer than you think: Portland's geographic location and Oregon's transportation infra - structure offer unmatched con - nectivity and time savings to international and domestic markets. Our economic development practices combine project-ready property with efficient, high-capacity infrastructure to create today's logistics advantages. Connecting people, places and products is the core of Portland's distribution and logistics industry sec - tor.

F. Gregory; B. Boyd; R. Bridges; D. Mitchell; J. Halsell; S. Fancher; D. King; R. Fore; E. Mango; D. Berlinrut; M. Leinbach; M. Maier; M. Wetmore; H. Herring; J. Guidi; M. Coolidge; J. Heald; T. Knox; D. Bartine; R. Bailey; H. Delgado; P. Conant; J. Madura; R. Thomas; F. Merceret; G. Allen; E. Bensman; R. Dittemore; N. Feldman; C. Boykin; H. Tileston; F. Brody; L. Hagerman; S. Pearson; L. Uccellini; W. Vaughan; J. Golden; D. Johnson; J. McQueen; B. Roberts; L. Freeman; G. Jasper; B. Hagemeyer; A. McCool; X. W. Proenza; S. Glover

2006-01-01

411

Species of Interest: Pacific and Western Brook Lamprey and Freshwater Mussels Detailed Life History, Distribution, Abundance, and Other Information  

E-print Network

History, Distribution, Abundance, and Other Information Developed by: Confederated Tribes of the Umatilla in North America from the Aleutian Islands south along the Pacific coast to Baja California, Mexico wherever salmon occurred (Simpson and Wallace 1978). Access rather than distance from the ocean

412

The control of grain size and distribution of particles in a (6061 alloym/(Al2O3)P composite by solutionizing treatment  

NASA Astrophysics Data System (ADS)

The grain growth during an isothermal treatment at a solutionizing temperature of 540°C has been studied in a composite containing 6061 aluminum alloy matrix with A12O3 particles. The grain growth law is generally applicable to the composites containing 0.10, 0.15, and 0.20 volume fraction of the A12O3 particles (VFAP). It has been observed that the grain growth process involves the disintegration of the agglomerated particles first and then particles coalesce at longer solutionizing times in the composite containing 0.20 VFAP. The process of coalescence has not been observed up to a heating time of 20 hours at this temperature in the composites containing 0.10 and 0.15 VFAP. The trans-mission electron microscopy (TEM) study indicates the generation of a large number of dislocations in both the matrix and the area adjacent to the particles. The dislocation densities at these two locations in the composites increase with an increase in VFAP and the particle size. The microhard-ness measurements confirm the microstructural observations, and the hardness values for the com-posite and the matrix appear to be more sensitive to the particle distribution and the particle size compared to the grain size.

Varma, S. K.; Ponce, Javier; Solis, Michael; Andrews, Shane; Salas, Daniel

1996-07-01

413

Use of multi-photon laser-scanning microscopy to describe the distribution of xenobiotic chemicals in fish early life stages.  

PubMed

To better understand the mechanisms by which persistent bioaccumulative toxicants (PBTs) produce toxicity during fish early life stages (ELS), dose-response relationships need to be understood in relation to the dynamic distribution of chemicals in sensitive tissues. In this study, a multi-photon laser scanning microscope (MPLSM) was used to determine the multi-photon excitation spectra of several polyaromatic hydrocarbons (PAHs) and to describe chemical distribution among tissues during fish ELS. The multi-photon excitation spectra revealed intense fluorescent signal from the model fluorophore, pentamethyl-difluoro-boro-indacene (BODIPY), less signal from benzo[a]pyrene and fluoranthene, and no detectable signal from pyrene. The imaging method was tested by exposing newly fertilized medaka (Oryzias latipes) eggs to BODIPY or fluoranthene for 6 h, followed by transfer to clean media. Embryos and larvae were then imaged through 5 days post-hatch. The two test chemicals partitioned similarly throughout development and differences in fluorescence intensity among tissues were evident to a depth of several hundred microns. Initially, the most intense signal was observed in the oil droplet within the yolk, while a moderate signal was seen in the portion of the yolk containing the yolk-platelets. As embryonic development progressed, the liver biliary system, gall bladder, and intestinal tract accumulated strong fluorescent signal. After hatch, once the gastrointestinal tract was completely developed, most of the fluorescent signal was cleared. The MPLSM is a useful tool to describe the tissue distribution of fluorescent PBTs during fish ELS. PMID:15019246

Hornung, Michael W; Cook, Philip M; Flynn, Kevin M; Lothenbach, Doug B; Johnson, Rodney D; Nichols, John W

2004-03-30

414

Kinetics and product distribution of end of life tyres (ELTs) pyrolysis: a novel approach in polyisoprene and SBR thermal cracking.  

PubMed

Thermo-chemical treatments (mainly pyrolysis) directed towards energy and products recovery provide a very promising alternative to open space disposal or landfilling, reducing in the process hazardous waste and potential contamination to soil and water resources. In this communication, we present results of end of life tyres (ELTs) pyrolysis via isothermal and dynamic thermogravimetry of two ELT grades. The aim of this study is to demonstrate the possibility of utilizing a pre-set temperature (T(c)=500 degrees C) pyrolysis process (conversion time, t(c), of 120 s), to the benefit of intensifying the global product yields recovered. A novel engineering kinetics approach was undertaken to propose a thermal cracking scheme of four primary and two secondary side reactions. Thermal degradation of ELTs was taken from a depolymerization approach of the present polyisoprene polymer in the tyres, resulting in a high regression of 0.959. The products of ELTs pyrolysis were lumped into four categories, namely aromatics, liquids, char and gases. The thermal cracking model evaluation of kinetic rate constants and lumped products showed a regression ranging between 0.90 and 0.94. Dynamic runs were performed to extend the model derived, taking into account heating rate (beta) influence and products prediction and interaction. The results obtained can be used in designing industrial ELTs pyrolysis units. PMID:19713038

Al-Salem, S M; Lettieri, P; Baeyens, J

2009-12-30

415

Impacts of variability of habitat factors on species composition of ichthyoplankton and distribution of fish spawning ground in the Changjiang River estuary and its adjacent waters  

Microsoft Academic Search

During June, August and October 2006, there were three multi-disciplinary surveys carried out in the Changjiang River estuary and its adjacent waters (122°00?–125°00?E, 27°50?–34°00?N) by R\\/V Beidou to study the species composition and abundance of ichthyoplankton (including fish eggs, larvae and juveniles), the spatial distribution of fish spawning ground and their relationship with habitat factors. There were 29, 29 and