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1

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

2

Wealth distribution in life-cycle economies  

Microsoft Academic Search

This paper compares the age-wealth distribution produced in life-cycle economies to the corresponding distribution in the US economy. The idea is to calibrate the model economies to match features of the US earnings distribution and then examine the wealth distribution implications of the model economies. The findings are that the calibrated model economies with earnings and lifetime uncertainty can replicate

Mark Huggett

1996-01-01

3

The compositional distribution of asteroids  

NASA Astrophysics Data System (ADS)

Each compositional class of asteroid is a relic of the temperature and composition conditions in which it formed. The current distribution reveals the history of the Solar System, and each body acts as a marker of any mixing that occurred since formation. The remnant of a primordial temperature gradient, seen as transition from the S class to C class dominating in different regions of the asteroid belt has been a paradigm for three decades [1-4]. Today, we are armed with major advancements from the past decade that have revolutionized the field of asteroids in areas such as discovery, physical characterization, and dynamical models. A new and more detailed compositional map [5,6] created with data from the Sloan Digital Sky Survey [7] allows us to re-examine compositional trends in the main asteroid belt and what the physical and dynamical implications might be. This talk is related to recent work from DeMeo & Carry 2013, 2014 [5,6] and an upcoming chapter of the "Asteroids IV" book in 2015.

DeMeo, F.; Carry, B.; Alexander, C.; Walsh, K.; Chapman, C.

2014-07-01

4

Multiscale Fatigue Life Prediction for Composite Panels  

NASA Technical Reports Server (NTRS)

Fatigue life prediction capabilities have been incorporated into the HyperSizer Composite Analysis and Structural Sizing Software. The fatigue damage model is introduced at the fiber/matrix constituent scale through HyperSizer s coupling with NASA s MAC/GMC micromechanics software. This enables prediction of the micro scale damage progression throughout stiffened and sandwich panels as a function of cycles leading ultimately to simulated panel failure. The fatigue model implementation uses a cycle jumping technique such that, rather than applying a specified number of additional cycles, a specified local damage increment is specified and the number of additional cycles to reach this damage increment is calculated. In this way, the effect of stress redistribution due to damage-induced stiffness change is captured, but the fatigue simulations remain computationally efficient. The model is compared to experimental fatigue life data for two composite facesheet/foam core sandwich panels, demonstrating very good agreement.

Bednarcyk, Brett A.; Yarrington, Phillip W.; Arnold, Steven M.

2012-01-01

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

Composites of porous metal and solid lubricants increase bearing life  

NASA Technical Reports Server (NTRS)

Self-lubricating composites of porous nickel and nickel-chromium alloy impregnated with a barium fluoride-calcium fluoride eutectic, and a thin film of solid lubricant increase wear life of load bearing surfaces.

Sliney, H. E.

1967-01-01

7

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

8

Assessment of fatigue life for small composite wind turbine blades  

Microsoft Academic Search

The present design and assessment of fatigue life for the small composite wind turbine blades (SCWTBs) can be certified by IEC 61400-2 “Wind Turbines - Part2: Design requirements of small wind turbines”. The paper will establish an analytical method on the fatigue life analysis of SCWTBs. Using the Microsoft Office EXCEL to calculate the maximum stress, minimum stress and stress

Jia-Hroung Wu

2010-01-01

9

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

10

Fatigue life evaluation in composite rotor blade of multipurpose helicopter  

Microsoft Academic Search

The prediction of fatigue life and strength of the composite rotor blade for multipurpose helicopter was studied using a residual strength degradation concept. A flight-by-flight load spectrum was introduced on the basis of FELIX standard data. The composite structure analysis was performed to obtain the local stress near blade root in laminate skin and glass roving spar where fatigue damage

Jung-Ho Kwon; Kyung-Jung Hwang; Seok-Soo Kim; Pan-Jo Kim; Choon-Sam Kim

2002-01-01

11

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

12

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

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

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

16

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

17

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

18

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

19

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

20

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

21

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

22

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

23

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 Mohamed; Verrilli, M. J.; Halford, G. R.

1989-01-01

24

Two methods for determining pressure distribution in composite reservoirs  

Microsoft Academic Search

This study investigates two simplified numerical models for evaluating the transient pressure distribution in composite reservoirs. Comparisons are made between the results obtained for these two models and the general numerical solution which describes pressure in the two-member composite model. Partial differential equations for the General Composite model are developed from the continuity equation, the equation of state, and Darcy's

Hedayati

1988-01-01

25

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

26

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

27

Composite Overwrap Pressure Vessels: Mechanics and Stress Rupture Lifing Philosophy  

NASA Technical Reports Server (NTRS)

The NASA Engineering and Safety Center (NESC) has been conducting an independent technical assessment to address safety concerns related to the known stress rupture failure mode of filament wound pressure vessels in use on Shuttle and the International Space Station. The Shuttle's Kevlar-49 fiber overwrapped tanks are of particular concern due to their long usage and the poorly understood stress rupture process in Kevlar-49 filaments. Existing long term data show that the rupture process is a function of stress, temperature and time. However due to the presence of load sharing liners and the complex manufacturing procedures, the state of actual fiber stress in flight hardware and test articles is not clearly known. Indeed non-conservative life predictions have been made where stress rupture data and lifing procedures have ignored the contribution of the liner in favor of applied pressure as the controlling load parameter. With the aid of analytical and finite element results, this paper examines the fundamental mechanical response of composite overwrapped pressure vessels including the influence of elastic-plastic liners and degraded/creeping overwrap properties. Graphical methods are presented describing the non-linear relationship of applied pressure to Kevlar-49 fiber stress/strain during manufacturing, operations and burst loadings. These are applied to experimental measurements made on a variety of vessel systems to demonstrate the correct calibration of fiber stress as a function of pressure. Applying this analysis to the actual qualification burst data for Shuttle flight hardware revealed that the nominal fiber stress at burst was in some cases 23% lower than what had previously been used to predict stress rupture life. These results motivate a detailed discussion of the appropriate stress rupture lifing philosophy for COPVs including the correct transference of stress rupture life data between dissimilar vessels and test articles.

Thesken, John C.; Murthy, Pappu L. N.; Phoenix, Leigh

2007-01-01

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

Life Modeling and Design Analysis for Ceramic Matrix Composite Materials  

NASA Technical Reports Server (NTRS)

The primary research efforts focused on characterizing and modeling static failure, environmental durability, and creep-rupture behavior of two classes of ceramic matrix composites (CMC), silicon carbide fibers in a silicon carbide matrix (SiC/SiC) and carbon fibers in a silicon carbide matrix (C/SiC). An engineering life prediction model (Probabilistic Residual Strength model) has been developed specifically for CMCs. The model uses residual strength as the damage metric for evaluating remaining life and is posed probabilistically in order to account for the stochastic nature of the material s response. In support of the modeling effort, extensive testing of C/SiC in partial pressures of oxygen has been performed. This includes creep testing, tensile testing, half life and residual tensile strength testing. C/SiC is proposed for airframe and propulsion applications in advanced reusable launch vehicles. Figures 1 and 2 illustrate the models predictive capabilities as well as the manner in which experimental tests are being selected in such a manner as to ensure sufficient data is available to aid in model validation.

2005-01-01

30

Creep-fatigue life prediction of in situ composite solders  

SciTech Connect

Eutectic tin-lead solder alloys subjected to cyclic loading at room temperature experience creep-fatigue interactions due to high homologous temperature. Intermetallic reinforcements of Ni{sub 3}Sn{sub 4} and Cu{sub 6}Sn{sub 5} are incorporated into eutectic tin-lead alloy by rapid solidification processes to form in situ composite solders. In this study, the in situ composite solders were subjected to combined creep and fatigue deformation at room temperature. Under cyclic deformation, the dominant damage mechanism of in situ composite solders is proposed to be growth of cavities. A constrained cavity growth model is applied to predict creep-fatigue life by taking into account the tensile loading component as well as the compressive loading component when reversed processes can occur. An algorithm to calculate cavity growth in each fatigue cycle is used to predict the number of fatigue cycles to failure, based on a critical cavity size of failure. Calculated lives are compared to experimental data under several fatigue histories, which include fully reversed stress-controlled fatigue, zero-tension stress-controlled fatigue, stress-controlled fatigue with tension hold time, fully reversed strain-controlled fatigue, and zero-tension strain-controlled fatigue. The model predicts the creep-fatigue lives within a factor of 2 with the incorporation of an appropriate compressive healing factor in most cases. Discrepancy between calculated lives and experimental results is discussed.

Kuo, C.G.; Sastry, S.M.L.; Jerina, K.L. [Washington Univ., St. Louis, MO (United States)

1995-12-01

31

The composition of the gut microbiota throughout life, with an emphasis on early life.  

PubMed

The intestinal microbiota has become a relevant aspect of human health. Microbial colonization runs in parallel with immune system maturation and plays a role in intestinal physiology and regulation. Increasing evidence on early microbial contact suggest that human intestinal microbiota is seeded before birth. Maternal microbiota forms the first microbial inoculum, and from birth, the microbial diversity increases and converges toward an adult-like microbiota by the end of the first 3-5 years of life. Perinatal factors such as mode of delivery, diet, genetics, and intestinal mucin glycosylation all contribute to influence microbial colonization. Once established, the composition of the gut microbiota is relatively stable throughout adult life, but can be altered as a result of bacterial infections, antibiotic treatment, lifestyle, surgical, and a long-term change in diet. Shifts in this complex microbial system have been reported to increase the risk of disease. Therefore, an adequate establishment of microbiota and its maintenance throughout life would reduce the risk of disease in early and late life. This review discusses recent studies on the early colonization and factors influencing this process which impact on health. PMID:25651996

Rodríguez, Juan Miguel; Murphy, Kiera; Stanton, Catherine; Ross, R Paul; Kober, Olivia I; Juge, Nathalie; Avershina, Ekaterina; Rudi, Knut; Narbad, Arjan; Jenmalm, Maria C; Marchesi, Julian R; Collado, Maria Carmen

2015-01-01

32

The composition of the gut microbiota throughout life, with an emphasis on early life  

PubMed Central

The intestinal microbiota has become a relevant aspect of human health. Microbial colonization runs in parallel with immune system maturation and plays a role in intestinal physiology and regulation. Increasing evidence on early microbial contact suggest that human intestinal microbiota is seeded before birth. Maternal microbiota forms the first microbial inoculum, and from birth, the microbial diversity increases and converges toward an adult-like microbiota by the end of the first 3–5 years of life. Perinatal factors such as mode of delivery, diet, genetics, and intestinal mucin glycosylation all contribute to influence microbial colonization. Once established, the composition of the gut microbiota is relatively stable throughout adult life, but can be altered as a result of bacterial infections, antibiotic treatment, lifestyle, surgical, and a long-term change in diet. Shifts in this complex microbial system have been reported to increase the risk of disease. Therefore, an adequate establishment of microbiota and its maintenance throughout life would reduce the risk of disease in early and late life. This review discusses recent studies on the early colonization and factors influencing this process which impact on health. PMID:25651996

Rodríguez, Juan Miguel; Murphy, Kiera; Stanton, Catherine; Ross, R. Paul; Kober, Olivia I.; Juge, Nathalie; Avershina, Ekaterina; Rudi, Knut; Narbad, Arjan; Jenmalm, Maria C.; Marchesi, Julian R.; Collado, Maria Carmen

2015-01-01

33

Composition in distributional models of semantics   

E-print Network

Distributional models of semantics have proven themselves invaluable both in cognitive modelling of semantic phenomena and also in practical applications. For example, they have been used to model judgments of semantic ...

Mitchell, Jeffrey John

2011-06-30

34

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 siblings in utero on morphology and life-history traits. However, in wild animals, such effects of litter-bellied marmots (Marmota flaviventris) and documented the effects of weaned litter sex composition and anogenital

Blumstein, Daniel T.

35

Notch sensitivity of fatigue life in a Sylramic TM composite at elevated temperature  

E-print Network

in advanced gas turbine engines. The motivation for this activity is the desire to increase operatingNotch sensitivity of fatigue life in a Sylramic TM /SiC composite at elevated temperature J.C. Mc The effects of holes and notches on the fatigue life of an advanced SylramicTM /SiC composite at 815 C have

Zok, Frank

36

Life history, diversity and distribution: A study of Japanese pteridophytes  

USGS Publications Warehouse

Many studies address the relationships between diversity or distribution and attributes of the physical environment. However, how these relationships are connected to variation in life history is poorly understood. This is particularly true in the case of pteridophytes. Japanese ferns and their allies comprise one of the best-known pteridophyte floras in the world. We analyzed ca 600 species of Japanese pteridophytes for which there is detailed information on distribution, reproduction, and chromosome number. Species richness was greatest in groups with a single reproductive mode (sexual, followed by apogamous), but distribution was greatest in species groups with multiple reproductive modes: sexual plus either sterile (irregular in meiosis) or apogamous. Geographical ranges varied greatly among species with small chromosome numbers but were uniformly small among species having high chromosome numbers. Seasonally green (mostly summer green) species had significantly larger distribution ranges than evergreen species. Endemic species had higher proportions of apogamy and sterility than non-endemic species. Seasonally green species had significantly larger distributional ranges, and a smaller proportion of species with apogamous reproduction, than evergreen species. There was no clear relationship between distribution and spore size, either among endemic species, non-endemic species, or all species combined. There was no relationship between spore size and chromosome number when all species were combined. However, positive relationships were detected within three of the nine largest genera, suggesting potential phylogenetic effects. We concluded that habitat availability, rather than dispersability, may be the limiting factor for the distribution of pteridophytes in Japan.

Guo, Q.; Kato, M.; Ricklefs, R.E.

2003-01-01

37

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

38

Model Driven Design of Distribution Patterns for Web Service Compositions  

Microsoft Academic Search

Increasingly, distributed systems are being constructed by composing a number of discrete components. This prac- tice, termed composition, is particularly prevalent within the Web service domain. Here, enterprise systems are built from many existing discrete applications, often legacy ap- plications exposed using Web service interfaces. There are a number of architectural configurations or distribution patterns, which express how a composed

Ronan Barrett; Claus Pahl

2006-01-01

39

Composite Fading Channel Modeling and Information Capacity of Distributed Antenna  

E-print Network

at each distributed antenna port (DAP) on the design and analysis of optimal/suboptimal transmissionComposite Fading Channel Modeling and Information Capacity of Distributed Antenna Architectures-Carleton Institute for Electrical and Computer Engineering (OCIECE) Department of Systems and Computer Engineering

Yanikomeroglu, Halim

40

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

41

Fatigue Life Methodology for Tapered Hybrid Composite Flexbeams  

NASA Technical Reports Server (NTRS)

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 geometrically nonlinear finite element codes, ANSYS and ABAQUS, are presented and compared. Strain energy release rates (G) associated with simulated delamination growth in the flexbeams are presented from both codes. These results compare well with each other and suggest that the initial delamination growth from the tip of the ply-drop 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 for comparison with test data. A curve relating maximum surface strain to number of loading cycles at delamination onset compared well with the test results.

urri, Gretchen B.; Schaff, Jeffery R.

2006-01-01

42

A distributed scheme for autonomous service composition  

Microsoft Academic Search

Some multimedia content may be divisible into independently routable components, e.g. audio and video flows. As a result media content adaptation services may be linked in serial, parallel and hybrid configurations to form a directed, acyclic graph of composed services. We specify a distributed service path selection scheme for the construction of composed directed service graphs, which integrates a peer-to-peer

Stephen Herborn; Yoann Lopez; Aruna Seneviratne

2005-01-01

43

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

44

Barium distributions in teeth reveal early-life dietary transitions in primates.  

PubMed

Early-life dietary transitions reflect fundamental aspects of primate evolution and are important determinants of health in contemporary human populations. Weaning is critical to developmental and reproductive rates; early weaning can have detrimental health effects but enables shorter inter-birth intervals, which influences population growth. Uncovering early-life dietary history in fossils is hampered by the absence of prospectively validated biomarkers that are not modified during fossilization. Here we show that large 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 through the weaning process. We also document dietary 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, indicating 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

2013-06-13

45

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

46

Species composition and distribution of the macrozooplankton in Postoak Lake  

E-print Network

SPECIFS COMPOSITION AND DISTRIBUTION OF THE MACROZOOP~XKTON IN POSTOAK LAI& A Thos ts by DOUGLAS EDWARD WELCH Submitted to the Graduate College of Texas A&M University in partial fulfillment of the requirement for the degree of MASTER... and winter months. Cladocera predominated in late October and early November. The lnean momentary composition of Postoak Lake included 5. 6 cladoceran species and 3. 0 copepod species. Density differences between inshore and offshore areas occurred...

Welch, Douglas Edward

1977-01-01

47

Fast adaptive composite grid methods on distributed parallel architectures  

NASA Technical Reports Server (NTRS)

The fast adaptive composite (FAC) grid method is compared with the adaptive composite method (AFAC) under variety of conditions including vectorization and parallelization. Results are given for distributed memory multiprocessor architectures (SUPRENUM, Intel iPSC/2 and iPSC/860). It is shown that the good performance of AFAC and its superiority over FAC in a parallel environment is a property of the algorithm and not dependent on peculiarities of any machine.

Lemke, Max; Quinlan, Daniel

1992-01-01

48

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

49

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

50

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

51

Stress Rupture Life Reliability Measures for Composite Overwrapped Pressure Vessels  

NASA Technical Reports Server (NTRS)

Composite Overwrapped Pressure Vessels (COPVs) are often used for storing pressurant gases onboard spacecraft. Kevlar (DuPont), glass, carbon and other more recent fibers have all been used as overwraps. Due to the fact that overwraps are subjected to sustained loads for an extended period during a mission, stress rupture failure is a major concern. It is therefore important to ascertain the reliability of these vessels by analysis, since the testing of each flight design cannot be completed on a practical time scale. The present paper examines specifically a Weibull statistics based stress rupture model and considers the various uncertainties associated with the model parameters. The paper also examines several reliability estimate measures that would be of use for the purpose of recertification and for qualifying flight worthiness of these vessels. Specifically, deterministic values for a point estimate, mean estimate and 90/95 percent confidence estimates of the reliability are all examined for a typical flight quality vessel under constant stress. The mean and the 90/95 percent confidence estimates are computed using Monte-Carlo simulation techniques by assuming distribution statistics of model parameters based also on simulation and on the available data, especially the sample sizes represented in the data. The data for the stress rupture model are obtained from the Lawrence Livermore National Laboratories (LLNL) stress rupture testing program, carried out for the past 35 years. Deterministic as well as probabilistic sensitivities are examined.

Murthy, Pappu L. N.; Thesken, John C.; Phoenix, S. Leigh; Grimes-Ledesma, Lorie

2007-01-01

52

Composite-flywheel durability and life. Part I. Test program  

Microsoft Academic Search

It has been demonstrated that flywheels made from composite materials are capable of storing energy at a significantly greater energy density than flywheels made from conventional metals. Composite flywheels which can store up to 80 Wh\\/kg have been successfully tested. In addition, composite flywheels are inherently safer for applications in vehicles and other devices since the failure of such wheels

S. V. Kulkarni; K. L. Reifsnider

1982-01-01

53

Inferences on a life distribution by sampling from the ages or the ages at death  

Microsoft Academic Search

Consider a system where units having independent and identically distributed lifetimes enter according to a nonhomogeneous Poisson process. After the unit’s life in the system, the unit departs the system. For a fixed system time, this paper relates the units’ common underlying life distribution with the distribution of the ages of units in the system, the distribution for the system

Mark D. Rothmann

2006-01-01

54

ORIGINAL PAPER Floristic composition and spatial distribution of germinable  

E-print Network

ORIGINAL PAPER Floristic composition and spatial distribution of germinable seeds in a spruce germinable seeds in those stands. & Methods We analysed the soil seed bank by germination method and characterised germination dynamics and distri- bution of seedlings throughout the samples according to a sigmoid

Paris-Sud XI, Université de

55

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, and exotics (WIMPS, axions,...) striking the earth. The primary cosmic rays are those entering the upper atmosphere, the cosmic rays of the interstellar medium. Secondary cosmic rays are those produced

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

56

Composition and analysis of a model waste for a CELSS (Controlled Ecological Life Support System)  

NASA Technical Reports Server (NTRS)

A model waste based on a modest vegetarian diet is given, including composition and elemental analysis. Its use is recommended for evaluation of candidate waste treatment processes for a Controlled Ecological Life Support System (CELSS).

Wydeven, T. J.

1983-01-01

57

Composition distributions of particles in a gelling mixture  

NASA Astrophysics Data System (ADS)

Gelation in a two component disperse system wherein binary coagulation governs the temporal changes of particle composition spectra is studied for the crossproduct coagulation kernel proportional to m1n2+m2n1, with m ,n being the numbers of monomers of the first and the second component in the coalescing pair of particles. This model reveals the sol-gel transition, i.e., after a finite interval of time the conservation of the total particle mass concentration violates because of the formation of giant particles (the gel). This paper reports on the exact solution of this model for arbitrary initial particle composition spectra. Exact expressions for the particle composition spectrum, the gel mass, and the second moments of the composition distribution are derived. Two scenarios of gelation, where the gel is either active or passive, are considered.

Lushnikov, A. A.

2014-03-01

58

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

59

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

60

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

61

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

62

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

63

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

64

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

65

Changes in the Lipid Composition of Thalassiosira pseudonana during Its Life Cycle  

Microsoft Academic Search

The lipid and fatty acid (FA) compositions of a marine diatom alga Thalassiosira pseudonana grown in culture were investigated. The relative content of separate lipid classes and their FA composition varied during of the life cycle. During the periods of active cell division and resting cell production, the proportion of polar lipids, as the structural components of cell membranes, increased.

N. V. Zhukova

2004-01-01

66

Spatial distribution of volatile compounds in graphite composites  

NASA Technical Reports Server (NTRS)

The distribution of water and other volatile compounds such as acetone and phenol was measured as a function of depth in four graphite resin matrix composites. Precision abrasion mass spectrometry was used to qualitatively and quantitatively characterize the indigenous volatile compounds in the as received condition and after drying in an environmentally controlled oven. The total amount of water in the composites varied from 0.12 wt% to 1.1 wt% and the times required to dry the samples ranged from less than 96 h to much greater than 555 h.

Grayson, M. A.; Wolf, C. J.; Kourtides, D. A.

1980-01-01

67

Accelerated Life Testing Model for a Generalized Birnbaum-Saunders Distribution  

E-print Network

-S distribution in order to estimate reliability at normal operating conditions. A. Birnbaum-Saunders Life ModelAccelerated Life Testing Model for a Generalized Birnbaum-Saunders Distribution Yao Cheng and E. A modeled by Birnbaum-Saunders (B-S) and Weibull distributions. Sometimes, materials with high cycle fatigue

Boyer, Edmond

68

Carbon nanofiber polymer composites: evaluation of life cycle energy use.  

PubMed

Holistic evaluation of emerging nanotechnologies using systems analysis is pivotal for guiding their safe and sustainable development. While toxicity studies of engineered nanomaterials are essential, understanding of the potential large scale impacts of nanotechnology is also critical for developing sustainable nanoproducts. This work evaluates the life cycle energetic impact associated with the production and use of carbon nanofiber (CNF) reinforced polymer nanocomposites (PNC). Specifically, both simple CNF and carbon nanofiber-glass fiber (CNF-GF) hybrid PNCs are evaluated and compared with steel for equal stiffness design. Life cycle inventory is developed based on published literature and best available engineering information. A cradle-to-gate comparison suggests that for equal stiffness design, CNF reinforced PNCs are 1.6-12 times more energy intensive than steel. It is anticipated that the product use phase may strongly influence whether any net savings in life cycle energy consumption can be realized. A case study involving the use of CNF and CNF-GF reinforced PNCs in the body panels of automobiles highlights that the use of PNCs with lower CNF loading ratios has the potential for net life cycle energy savings relative to steel owing to improved fuel economy benefits. Other factors such as cost, toxicity impact of CNF, and end-of-life issues specific to CNFs need to be considered to evaluate the final economic and environmental performance of CNF reinforced PNC materials. PMID:19368217

Khanna, Vikas; Bakshi, Bhavik R

2009-03-15

69

The life, death, and composition of exoterrestrial planets around intermediate mass stars  

NASA Astrophysics Data System (ADS)

This thesis attempts to comprehensively address the life, death, and composition of terrestrial-like planets orbiting around intermediate-mass stars. All-sky optical and infrared catalogs were cross-correlated to identify new main sequence stellar systems with evidence for terrestrial planet zone formation and evolution events. One such system is identified and its mid- infrared spectral energy distribution is characterized. In the course of cross- correlating the all-sky catalogs a new class of dusty, accreting, first-ascent giant star was discovered. Rough characterization of this new class of giants in the optical and infrared is provided with an emphasis on two giant-disk systems. The final throes of planetary systems around intermediate mass stars were investigated through the study of three gas-disk hosting white dwarfs. A dusty component to one white dwarf is identified, and the physical parameters regarding all three disks are determined. A model for the gas disk heating mechanism is suggested. By examining the pollution of the white dwarf photosphere by infalling disk material the first-ever bulk composition of an extra-solar rocky body is determined.

Melis, Carl Anthony

70

Measurement of Dijet Angular Distributions and Search for Quark Compositeness  

SciTech Connect

We have measured the dijet angular distribution in {radical}(s)=1.8 TeV p {bar p} collisions using the D0 detector. Order {alpha}{sup 3}{sub s} QCD predictions are in good agreement with the data. At 95{percent} confidence limit the data exclude models of quark compositeness in which the contact interaction scale is below 2TeV. {copyright} {ital 1998} {ital The American Physical Society}

Gomez, B.; Hoeneisen, B.; Mooney, P.; Negret, J.P. [Universidad de los Andes, Bogota (Colombia); Davis, K.; Fein, D.; Forden, G.E.; Guida, J.A.; James, E.; Johns, K.; Nang, F.; Narayanan, A.; Rutherfoord, J. [University of Arizona, Tucson, Arizona 85721 (United States); Butler, J.M. [Boston University, Boston, Massachusetts 02215 (United States); Fatyga, M.; Featherly, J.; Gibbard, B.; Gordon, H.; Graf, N.; Kahn, S.; Kotcher, J.; Protopopescu, S.; Rajagopalan, S. [Brookhaven National Laboratory, Upton, New York 11973 (United States); Bantly, J.; Cullen-Vidal, D.; Cutts, D.; Guida, J.M.; Hoftun, J.S.; Partridge, R. [Brown University, Providence, Rhode Island 02912 (United States); Grinstein, S.; Piegaia, R. [Universidad de Buenos Aires, Buenos Aires (Argentina); Bloom, P.; Fisyak, Y.; Glenn, S.; Grim, G.; Klopfenstein, C.; Lander, R.; Mani, S. [University of California, Davis, California 95616 (United States); Fahland, T.; Hall, R.E. [University of California, Irvine, California 92697 (United States); Boswell, C.; Choudhary, B.C.; Cochran, J.; Ellison, J.; Gartung, P.; Gounder, K.; Huehn, T. [University of California, Riverside, California 92521 (United States); Alves, G.A.; Carvalho, W.; Maciel, A.K.; da Motta, H.; Nicola, M.; Santoro, A. [LAFEX, Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro (Brazil); Castilla-Valdez, H.; Gonzalez Solis, J.L.; Hernandez-Montoya, R.; Magana-Mendoza, L.; Sanchez-Hernandez, A. [CINVESTAV, Mexico City (Mexico); Adam, I.; Kotwal, A.V. [Columbia University, New York, New York 10027 (United States); Bhattacharjee, M. [Delhi University, Delhi, (India) 110007; Ahn, S.; Baldin, B.; Bartlett, J.F.; Bhat, P.C.; Boehnlein, A.; Borcherding, F.; Brandt, A.; Bross, A.; Christenson, J.H.; Cooper, W.E.; Demarteau, M.; Denisov, D.; Diehl, H.T.; Diesburg, M.; Feher, S.; Fisk, H.E.; Flattum, E.; Fuess, S.; Genser, K.; Gerber, C.E.; Green, D.R.; Greenlee, H.; Grossman, N.; Haggerty, H.; Hansen, S.; Heintz, U.; Hobbs, J.; and others

1998-01-01

71

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

72

Three-Axis Distributed Fiber Optic Strain Measurement in 3D Woven Composite Structures  

NASA Technical Reports Server (NTRS)

Recent advancements in composite materials technologies have broken further from traditional designs and require advanced instrumentation and analysis capabilities. Success or failure is highly dependent on design analysis and manufacturing processes. By monitoring smart structures throughout manufacturing and service life, residual and operational stresses can be assessed and structural integrity maintained. Composite smart structures can be manufactured by integrating fiber optic sensors into existing composite materials processes such as ply layup, filament winding and three-dimensional weaving. In this work optical fiber was integrated into 3D woven composite parts at a commercial woven products manufacturing facility. The fiber was then used to monitor the structures during a VARTM manufacturing process, and subsequent static and dynamic testing. Low cost telecommunications-grade optical fiber acts as the sensor using a high resolution commercial Optical Frequency Domain Reflectometer (OFDR) system providing distributed strain measurement at spatial resolutions as low as 2mm. Strain measurements using the optical fiber sensors are correlated to resistive strain gage measurements during static structural loading. Keywords: fiber optic, distributed strain sensing, Rayleigh scatter, optical frequency domain reflectometry

Castellucci, Matt; Klute, Sandra; Lally, Evan M.; Froggatt, Mark E.; Lowry, David

2013-01-01

73

A Component-based Programming Model for Composite, Distributed Applications  

NASA Technical Reports Server (NTRS)

The nature of scientific programming is evolving to larger, composite applications that are composed of smaller element applications. These composite applications are more frequently being targeted for distributed, heterogeneous networks of computers. They are most likely programmed by a group of developers. Software component technology and computational frameworks are being proposed and developed to meet the programming requirements of these new applications. Historically, programming systems have had a hard time being accepted by the scientific programming community. In this paper, a programming model is outlined that attempts to organize the software component concepts and fundamental programming entities into programming abstractions that will be better understood by the application developers. The programming model is designed to support computational frameworks that manage many of the tedious programming details, but also that allow sufficient programmer control to design an accurate, high-performance application.

Eidson, Thomas M.; Bushnell, Dennis M. (Technical Monitor)

2001-01-01

74

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

75

The influence of lipid nanocapsule composition on their size distribution.  

PubMed

A formulation process, based on the inversion phase of an emulsion, was used to prepare lipid nanocapsules. Triglycerides, lecithin, salted water and hydroxy stearate of poly(ethylene glycol) were used in the preparation. The amounts of each that allowed nanocapsules to be formed described a feasibility domain within a ternary diagram. The size distribution of various nanoparticulate carriers has already been shown to influence their applications. An experimental mixture design inside the feasibility domain has been used in order to approximate, through an empirical model, the influence of the quantitative composition of nanocapsules on their size distribution. Reduced cubic polynomial equations successfully modelled the evolution of responses in terms of particle average diameters and coefficients of variation. The results were presented using an analysis of response surface showing a scale of possible particle sizes between 20 and 95 nm and a coefficient of variation between 11 and 40%. Furthermore, this technique showed that the proportion of hydrophilic surfactant had a major influence on the average diameter and the size distribution of the particles decreasing when its proportion increased. On the contrary, the coefficient of variation and the average diameter slightly increase with the proportion of triglycerides. Such a tool offers major advantages to design the formulation of particles as a function of the required size distribution. PMID:12554073

Heurtault, Béatrice; Saulnier, Patrick; Pech, Brigitte; Venier-Julienne, Marie-Claire; Proust, Jacques-Emile; Phan-Tan-Luu, Roger; Benoît, Jean-Pierre

2003-01-01

76

Aerosol size distribution, composition, and CO2 backscatter  

NASA Technical Reports Server (NTRS)

The aerosol size distribution, composition, and CO2 backscatter at 10.6 microns (beta-CO2) were measured continuosly at the Mauna Loa Observatory (Hawaii) during January-March and November-December, 1988 periods to compare the characteristics of periods associated with appreciable Asian dust transport to that site (January-March) with those of periods characterized by low-dust condition. The aerosol size distribution in the range 0.15 micron to 7.6 microns was measured at temperatures of 40, 150, and 340 C to differentiate between volatile and nonvolatile aerosols. Large ranges of variability was found in measurements of aerosol size distribution during both periods, but the average distributions were similar for both the high-dust and the low-dust periods. However, values for beta-CO2 were more elevated (by about six times) during periods associated with active Asian dust transport to the observatory site than during the low-dust periods.

Clarke, Antony D.; Porter, John N.

1991-01-01

77

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

78

Generalized parton distributions of hadrons with composite constituents  

NASA Astrophysics Data System (ADS)

A method is described for calculating the Generalized Parton Distributions (GPDs) of spin 1/2 hadrons made of composite constituents, in an Impulse Approximation framework. GPDs are obtained from the convolution between the light cone non-diagonal momentum distribution of the hadron and the GPD of the constituent. DIS structure functions and electromagnetic form factors are consistently recovered with the proposed formalism. Results are presented for the nucleon and for the 3He nucleus. For a nucleon assumed to be made of composite constituent quarks, the proposed scheme permits to study the so-called Efremov-Radyushkin-Brodsky-Lepage (ERBL) region, difficult to access in model calculations. Results are presented for both helicity-independent and helicity-dependent GPDs. For 3He, the calculation has been performed by evaluating a non-diagonal spectral function within the AV18 interaction. It turns out that a measurement of GPDs for 3He could shed new light on the short-range nuclear structure at the quark level.

Scopetta, S.

2007-02-01

79

Three-axis distributed fiber optic strain measurement in 3D woven composite structures  

NASA Astrophysics Data System (ADS)

Recent advancements in composite materials technologies have broken further from traditional designs and require advanced instrumentation and analysis capabilities. Success or failure is highly dependent on design analysis and manufacturing processes. By monitoring smart structures throughout manufacturing and service life, residual and operational stresses can be assessed and structural integrity maintained. Composite smart structures can be manufactured by integrating fiber optic sensors into existing composite materials processes such as ply layup, filament winding and three-dimensional weaving. In this work optical fiber was integrated into 3D woven composite parts at a commercial woven products manufacturing facility. The fiber was then used to monitor the structures during a VARTM manufacturing process, and subsequent static and dynamic testing. Low cost telecommunications-grade optical fiber acts as the sensor using a high resolution commercial Optical Frequency Domain Reflectometer (OFDR) system providing distributed strain measurement at spatial resolutions as low as 2mm. Strain measurements using the optical fiber sensors are correlated to resistive strain gage measurements during static structural loading.

Castellucci, Matt; Klute, Sandra; Lally, Evan M.; Froggatt, Mark E.; Lowry, David

2013-03-01

80

Design and life prediction issues for high-temperature engineering ceramics and their composites  

Microsoft Academic Search

Perspectives are presented on ceramics and ceramic matrix composites (CMCs) as high-temperature materials. The emphasis is on design and life prediction requirements and their role in directing research. Important themes include the relative roles of fracture toughness and inelastic strain (ductility), as well as scaling and stochastic effects caused by manufacturing defects. Ceramics with high toughness have been developed. However,

1997-01-01

81

Unequal geographic distribution of life expectancy in seoul.  

PubMed

This study examined life expectancies in 25 gus, administrative districts of Seoul, the capital of Korea, by gender in 1995, 2002, and 2008 to explore trends in mortality inequality among areas. The authors constructed single-decrement life tables and employed between-group variance, the Theil index, and mean log deviation to measure absolute and relative disparities in life expectancy among areas during the periods 1995-2002 and 2002-2008. It was found that life expectancy gaps between gus have widened in absolute and relative terms in both genders over the decade, and that this pattern was particularly dramatic in females after 2002. This increasing gap could be attributable to the more negative health impact on females since the late 1990s stemming from the economic crisis, eventually reflected in their places of residence. Thus, a social buffer system to narrow the health gap between geographic areas and social classes must be established. PMID:22535557

Kim, Sangmi; Yi, Seonju; Kim, Meekyung; Kim, Bokyung; Lee, Hwayoung; Jeon, Taekryeon; Cho, Youngtae

2015-03-01

82

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

83

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

84

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

85

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

86

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

87

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

88

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

89

Trends in the diversity, distribution and life history strategy of arctic hydrozoa (cnidaria).  

PubMed

This is the first attempt to compile a comprehensive and updated species list for Hydrozoa in the Arctic, encompassing both hydroid and medusa stages and including Siphonophorae. We address the hypothesis that the presence of a pelagic stage (holo- or meroplanktonic) was not necessary to successfully recolonize the Arctic by Hydrozoa after the Last Glacial Maximum. Presence-absence data of Hydrozoa in the Arctic were prepared on the basis of historical and present-day literature. The Arctic was divided into ecoregions. Species were grouped into distributional categories according to their worldwide occurrences. Each species was classified according to life history strategy. The similarity of species composition among regions was calculated with the Bray-Curtis index. Average and variation in taxonomic distinctness were used to measure diversity at the taxonomic level. A total of 268 species were recorded. Arctic-boreal species were the most common and dominated each studied region. Nineteen percent of species were restricted to the Arctic. There was a predominance of benthic species over holo- and meroplanktonic species. Arctic, Arctic-Boreal and Boreal species were mostly benthic, while widely distributed species more frequently possessed a pelagic stage. Our results support hypothesis that the presence of a pelagic stage (holo- or meroplanktonic) was not necessary to successfully recolonize the Arctic. The predominance of benthic Hydrozoa suggests that the Arctic could have been colonised after the Last Glacial Maximum by hydroids rafting on floating substrata or recolonising from glacial refugia. PMID:25793294

Ronowicz, Marta; Kukli?ski, Piotr; Mapstone, Gillian M

2015-01-01

90

Trends in the Diversity, Distribution and Life History Strategy of Arctic Hydrozoa (Cnidaria)  

PubMed Central

This is the first attempt to compile a comprehensive and updated species list for Hydrozoa in the Arctic, encompassing both hydroid and medusa stages and including Siphonophorae. We address the hypothesis that the presence of a pelagic stage (holo- or meroplanktonic) was not necessary to successfully recolonize the Arctic by Hydrozoa after the Last Glacial Maximum. Presence-absence data of Hydrozoa in the Arctic were prepared on the basis of historical and present-day literature. The Arctic was divided into ecoregions. Species were grouped into distributional categories according to their worldwide occurrences. Each species was classified according to life history strategy. The similarity of species composition among regions was calculated with the Bray-Curtis index. Average and variation in taxonomic distinctness were used to measure diversity at the taxonomic level. A total of 268 species were recorded. Arctic-boreal species were the most common and dominated each studied region. Nineteen percent of species were restricted to the Arctic. There was a predominance of benthic species over holo- and meroplanktonic species. Arctic, Arctic-Boreal and Boreal species were mostly benthic, while widely distributed species more frequently possessed a pelagic stage. Our results support hypothesis that the presence of a pelagic stage (holo- or meroplanktonic) was not necessary to successfully recolonize the Arctic. The predominance of benthic Hydrozoa suggests that the Arctic could have been colonised after the Last Glacial Maximum by hydroids rafting on floating substrata or recolonising from glacial refugia. PMID:25793294

Ronowicz, Marta; Kukli?ski, Piotr; Mapstone, Gillian M.

2015-01-01

91

Spatial distribution and life-history aspects of blackspot seabream Pagellus bogaraveo (Osteichthyes: Sparidae).  

PubMed

Spatial distribution and life history aspects of Pagellus bogaraveo in the eastern Ionian Sea were investigated using the data from 13 different studies carried out in the area from 1983 to 2010. The spatial patterns of the abundance, biomass and mean size showed that the species inhabits the shallow waters of the shelf (<170?m depth) as juveniles up to a certain size (<180?mm total length, LT ), moving to deeper waters of the slope (mainly 400-500?m depth) as adults. The spatial pattern of abundance indicated a continuous distribution of the species in deep waters, with hot-spot areas of high values, whereas in shallow waters distribution was more discontinuous, with higher concentrations of juveniles in estuaries and brackish waters. The study of biological aspects of the species revealed (1) a difference in the increase in mass between males and females, (2) protandrous hermaphroditism, accompanied by the presence of primary females and males that do not change sex, (3) a sex ratio in favour of females >250?mm LT , (4) the presence of hermaphrodites between 200 and 370?mm, (5) a long reproduction period from June to March, (6) a size at first maturity around 300?mm and (7) a diet composition of adults based mainly on fishes, and also on opportunistic behaviour in the food scarce environment of deep waters. The results suggest that the species' distribution and feeding strategies are the most appropriate for the oligotrophic eastern Ionian waters and that these conditions result in smaller sizes of the species in the east Mediterranean Sea compared to the west basin and the east Atlantic Ocean, with implications for the growth and reproductive biology of the species. PMID:24298951

Mytilineou, Ch; Tsagarakis, K; Bekas, P; Anastasopoulou, A; Kavadas, S; Machias, A; Haralabous, J; Smith, C J; Petrakis, G; Dokos, J; Kapandagakis, A

2013-12-01

92

Stress distribution in composite flatwise tension test specimens  

NASA Technical Reports Server (NTRS)

A finite element analysis was conducted to determine the stress distribution in typical graphite/epoxy composite flat wise tension (FWT) specimens under normal loading conditions. The purpose of the analysis was to determine the relationship between the applied load and the stress in the sample to evaluate the validity of the test as a means of measuring the out-of-plane strength of a composite laminate. Three different test geometries and three different material lay ups were modeled. In all cases, the out-of-plane component of stress in the test section was found to be uniform, with no stress concentrations, and very close to the nominal applied stress. The stress in the sample was found to be three-dimensional, and the magnitude of in-plane normal and shear stresses varied with the anisotropy of the test specimen. However, in the cases considered here, these components of stress were much smaller than the out-of-plane normal stress. The geometry of the test specimen had little influence on the results. It was concluded that the flat wise tension test provides a good measure of the out-of-plane strength for the representative materials that were studied.

Scott, Curtis A.; Pereira, J. Michael

1993-01-01

93

Effects of particle size distribution, surface area and chemical composition on Portland cement strength  

Microsoft Academic Search

The fineness of a Portland cement and its chemical composition are the key factors in determining cement strength characteristics. This paper describes a study of the relationship between cement particle size distribution and surface area, and the effects of size distribution, surface area and chemical composition on concrete strength. A new correlation between particle size distribution and surface area has

Y. M. Zhang; T. J. Napier-Munn

1995-01-01

94

Probabilistic Residual Strength Model Developed for Life Prediction of Ceramic Matrix Composites  

NASA Technical Reports Server (NTRS)

For the next generation of reusable launch vehicles, NASA is investigating introducing ceramic matrix composites (CMCs) in place of current superalloys for structural propulsion applications (e.g., nozzles, vanes, combustors, and heat exchangers). The higher use temperatures of CMCs will reduce vehicle weight by eliminating and/or reducing cooling system requirements. The increased strength-to-weight ratio of CMCs relative to superalloys further enhances their weight savings potential. However, in order to provide safe designs for components made of these new materials, a comprehensive life prediction methodology for CMC structures needs to be developed. A robust methodology for lifing composite structures has yet to be adopted by the engineering community. Current industry design practice continues to utilize deterministic empirically based models borrowed from metals design for predicting material life capabilities. The deterministic nature of these models inadequately addresses the stochastic character of brittle composites, and their empirical reliance makes predictions beyond the experimental test conditions a risky extrapolation. A team of engineers at the NASA Glenn Research Center has been developing a new life prediction engineering model. The Probabilistic Residual Strength (PRS) model uses the residual strength of the composite as its damage metric. Expected life and material strength are both considered probabilistically to account for the observed stochastic material response. Extensive experimental testing has been carried out on C/SiC (a candidate aerospace CMC material system) in a controlled 1000 ppm O2/argon environment at elevated temperatures of 800 and 1200 C. The test matrix was established to allow observation of the material behavior, characterization of the model, and validation of the model's predictive capabilities. Sample results of the validation study are illustrated in the graphs.

Thomas, David J.; Verrilli, Michael J.; Calomino, Anthony M.

2004-01-01

95

Estimating cumulative incidence functions when the life distributions are constrained  

Microsoft Academic Search

In competing risks studies, the Kaplan–Meier estimators of the distribution functions (DFs) of lifetimes and the corresponding estimators of cumulative incidence functions (CIFs) are used widely when no prior information is available for these distributions. In some cases better estimators of the DFs of lifetimes are available when they obey some inequality constraints, e.g., if two lifetimes are stochastically or

Hammou Elbarmi; Matthew Johnson; Hari Mukerjee

2010-01-01

96

Life cycle strain monitoring of composite airframe structures by FBG sensors  

NASA Astrophysics Data System (ADS)

Life cycle health monitoring technology for composite airframe structures based on strain mapping is proposed. It detects damages and deformation harmful to the structures by strain mapping using fiber Bragg grating (FBG) sensors through their life cycles including the stages of molding, machining, assembling, operation, and maintenance. In this paper, we firstly carried out a strain monitoring test of CFRP mock-up structure through the life cycle including the stage of molding, machining, assembling, and operation. The experimental result confirms that the strain which arises in each life cycle stage can be measured by FBG sensors embedded in molding stage and demonstrates the feasibility of life cycle structural health monitoring by using FBG sensors. Secondly, we conducted the strain monitoring test of CFRP scarf-repaired specimen subject to fatigue load. FBG sensors were embedded in the scarf-repaired part of the specimen and their reflection spectra were measured in uni-axial cyclic load test. Strain changes were compared with the pulse thermographic inspection. As a result, strain measured by FBG sensors changed sensitively with debonded area of repair patch, which demonstrates that the debondings of repair patches in scarf-repaired composites due to fatigue load can be detected by FBG sensors.

Takahashi, I.; Sekine, K.; Kume, M.; Takeya, H.; Minakuchi, S.; Takeda, N.; Enomoto, K.

2013-04-01

97

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

98

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

99

[Composition and dynamics of the bacteriocenosis accompanying algae in human biological life support systems].  

PubMed

The species and group composition as well as the number of bacteria concomitant with algae in the course of their continuous cultivation on a mineral medium as a self-contained system and as part of the biological life-support system were investigated. The major components of urine were passed to the reactor after its premineralization in a special unit. The experiments were carried out for 37 to 51 days. Under such cultivation conditions the number and generic composition of the algal microflora were stable. The common gas line between the algal reactors, units for urine microbiological mineralization and the manned module facilitated the generation of new bacterial groups which were, however, unable to develop in actively growing algal cultures and therefore disappeared rapidly. This indicates that the algal-bacterial cenosis within a biological life-support system has signs of a self-regulating system. PMID:2859386

Kondrat'eva, E M

1985-01-01

100

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

101

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

102

Characterization of reinforcement distribution in Al\\/(Al 2O 3) p composites obtained from composite powder  

Microsoft Academic Search

A composite powder Al–(Al2O3)p obtained in a rotary-vibration mill was used as a semifinished component to manufacture particle-reinforced metal matrix composites (PRMMCs) using cast and powder metallurgy technologies. For a quantitative description of the inhomogeneity of Al2O3 particle distributions in the aluminum matrix the following methods were applied: nearest neighbor distance, radial distribution function, influence zone morphology, systematic scanning and

Anita Olszówka-Myalska; Janusz Szala; Jan Cwajna

2001-01-01

103

Fatigue of Composite Materials: Damage Mechanisms and Fatigue-Life Diagrams  

Microsoft Academic Search

The basic fatigue damage mechanisms in composite laminates are reviewed. Based on these mechanisms a pattern in the fatigue-life diagrams is proposed. Several experimental data are shown to agree with this basic pattern. Fatigue ratio is defined in terms of strains, and fatigue limit is shown to exist for unidirectional, cross-plied and angle-plied laminates. The limitations to the fatigue performance

R. Talreja

1981-01-01

104

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

105

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. PMID:25538953

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

2014-01-01

106

TESTS FOR EQUALITY OF TWO DISTRIBUTIONS WITH CORRELATED INTERVAL CENSORED LIFE-TIMES  

Microsoft Academic Search

Large sample properties of Life-Table estimator are discussed for interval censored bivariate survival data. We restrict our attention to the situation where response times within pairs are not distinguishable, and the univariate survival distribution is the same for any individual within any pair. The large sample properties are applied to test for equality of two distributions with correlated response times

Shin-Soo Kang

2002-01-01

107

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

108

Distribution of Protein Folds in the Three Superkingdoms of Life  

E-print Network

differs between parasitic and free-living species. In all analyzed genomes, the P-loop NTPases%­6% more detectable by additional analysis of conserved motifs. The distribution of the most common folds, structure is generally more conserved than sequence, and therefore even subtle but reliable sequence

109

Effect of Internal Clearance on Load Distribution and Life of Radially Loaded Ball and Roller Bearings  

NASA Technical Reports Server (NTRS)

The effect of internal clearance on radially loaded deepgroove ball and cylindrical roller bearing load distribution and fatigue life was determined for four clearance groups defined in the bearing standards. The analysis was extended to negative clearance (interference) conditions to produce a curve of life factor versus internal clearance. Rolling-element loads can be optimized and bearing life maximized for a small negative operating clearance. Life declines gradually with positive clearance and rapidly with increasing negative clearance. Relationships were found between bearing life and internal clearance as a function of ball or roller diameter, adjusted for load. Results are presented as life factors for radially loaded bearings independent of bearing size or applied load. In addition, a modified Stribeck Equation is presented that relates the maximum rolling-element load to internal bearing clearance.

Oswald, Fred B.; Zaretsky, Erwin V.; Poplawski, Joseph V.

2012-01-01

110

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

111

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

112

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

113

Validation of Framework Code Approach to a Life Prediction System for Fiber Reinforced Composites  

NASA Technical Reports Server (NTRS)

The grant was conducted by the MMC Life Prediction Cooperative, an industry/government collaborative team, Ohio Aerospace Institute (OAI) acted as the prime contractor on behalf of the Cooperative for this grant effort. See Figure I for the organization and responsibilities of team members. The technical effort was conducted during the period August 7, 1995 to June 30, 1996 in cooperation with Erwin Zaretsky, the LERC Program Monitor. Phil Gravett of Pratt & Whitney was the principal technical investigator. Table I documents all meeting-related coordination memos during this period. The effort under this grant was closely coordinated with an existing USAF sponsored program focused on putting into practice a life prediction system for turbine engine components made of metal matrix composites (MMC). The overall architecture of the NMC life prediction system was defined in the USAF sponsored program (prior to this grant). The efforts of this grant were focussed on implementing and tailoring of the life prediction system, the framework code within it and the damage modules within it to meet the specific requirements of the Cooperative. T'he tailoring of the life prediction system provides the basis for pervasive and continued use of this capability by the industry/government cooperative. The outputs of this grant are: 1. Definition of the framework code to analysis modules interfaces, 2. Definition of the interface between the materials database and the finite element model, and 3. Definition of the integration of the framework code into an FEM design tool.

Gravett, Phillip

1997-01-01

114

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

115

Some roles of mechanics in the prediction of life in metal matrix composites  

SciTech Connect

In the current presentation the author will attempt to underscore the need for cooperative research between materials engineers and mechanicians by discussing the example of the much studied titanium matrix/silicon carbide fiber systems, commonly called TMC`s (titanium matrix composites). There are a variety of matrix materials under study, including Ti- 1 5-3, Ti-6-2-4-2, Ti Beta21 S, and a variety of titanium aluminides. The fiber is generally either SCS-6 or sigma. Both are trade names for CVD formed fibers; the former has a carbon substrate, whereas the latter has a tungsten substrate. Composites are fabricated from these constituents by a variety of techniques, including tape casting, powder mats, foil-fiber-foil hot pressing, HIPing, arc spraying, and plasma spraying. Complications arise from the fact that many of the titanium based matrix materials undergo substantial oxidation at temperatures in excess of 500/C. Prediction of life is clearly dependent on the development of an accurate processing model, as residual stresses develop during cool down. Since it is known that surface embrittlement due to oxidation can have a detrimental effect on life, it is also imperative to include this effect in life prediction models. Finally, the evolution of microstructural damage is a key to effective life prediction. The author will discuss recent research performed at Texas A&M University dealing with the thermomechanics of the above three effects. It will be shown that with an accurate mechanics framework predictions can be utilized to help develop improved models for predicting life in advanced continuous fiber MMC`S.

Allen, D.H.; Lagoudas, D.C. [Texas A& M Univ., College Station, TX (United States)

1995-12-31

116

Energy, ecology and the distribution of microbial life.  

PubMed

Mechanisms that govern the coexistence of multiple biological species have been studied intensively by ecologists since the turn of the nineteenth century. Microbial ecologists in the meantime have faced many fundamental challenges, such as the lack of an ecologically coherent species definition, lack of adequate methods for evaluating population sizes and community composition in nature, and enormous taxonomic and functional diversity. The accessibility of powerful, culture-independent molecular microbiology methods offers an opportunity to close the gap between microbial science and the main stream of ecological theory, with the promise of new insights and tools needed to meet the grand challenges humans face as planetary engineers and galactic explorers. We focus specifically on resources related to energy metabolism because of their direct links to elemental cycling in the Earth's history, engineering applications and astrobiology. To what extent does the availability of energy resources structure microbial communities in nature? Our recent work on sulfur- and iron-oxidizing autotrophs suggests that apparently subtle variations in the concentration ratios of external electron donors and acceptors select for different microbial populations. We show that quantitative knowledge of microbial energy niches (population-specific patterns of energy resource use) can be used to predict variations in the abundance of specific taxa in microbial communities. Furthermore, we propose that resource ratio theory applied to micro-organisms will provide a useful framework for identifying how environmental communities are organized in space and time. PMID:23754819

Macalady, Jennifer L; Hamilton, Trinity L; Grettenberger, Christen L; Jones, Daniel S; Tsao, Leah E; Burgos, William D

2013-07-19

117

Energy, ecology and the distribution of microbial life  

PubMed Central

Mechanisms that govern the coexistence of multiple biological species have been studied intensively by ecologists since the turn of the nineteenth century. Microbial ecologists in the meantime have faced many fundamental challenges, such as the lack of an ecologically coherent species definition, lack of adequate methods for evaluating population sizes and community composition in nature, and enormous taxonomic and functional diversity. The accessibility of powerful, culture-independent molecular microbiology methods offers an opportunity to close the gap between microbial science and the main stream of ecological theory, with the promise of new insights and tools needed to meet the grand challenges humans face as planetary engineers and galactic explorers. We focus specifically on resources related to energy metabolism because of their direct links to elemental cycling in the Earth's history, engineering applications and astrobiology. To what extent does the availability of energy resources structure microbial communities in nature? Our recent work on sulfur- and iron-oxidizing autotrophs suggests that apparently subtle variations in the concentration ratios of external electron donors and acceptors select for different microbial populations. We show that quantitative knowledge of microbial energy niches (population-specific patterns of energy resource use) can be used to predict variations in the abundance of specific taxa in microbial communities. Furthermore, we propose that resource ratio theory applied to micro-organisms will provide a useful framework for identifying how environmental communities are organized in space and time. PMID:23754819

Macalady, Jennifer L.; Hamilton, Trinity L.; Grettenberger, Christen L.; Jones, Daniel S.; Tsao, Leah E.; Burgos, William D.

2013-01-01

118

Structure, composition, and distribution of plastid nucleoids in Narcissus pseudonarcissus.  

PubMed

The size, frequency and distribution of the nucleoids of chloroplasts (cl-nucleoids) and chromoplasts (cr-nucleoids) of the daffodil have been investigated in situ using the DNA-specific fluorochrome 4'6-diamidino-2-phenylindole. Chromoplasts contain fewer nucleoids (approx. 4) than chloroplasts (> 10), and larger chromoplasts (cultivated form, approx. 4) contain more than smaller ones (wild type, approx. 2). During chromoplast development the nucleoid number decreases in parallel with the chlorophyll content. Each nucleoid contains 2-3 plastome copies on average. In chloroplasts the nucleoids are evenly distributed, whereas they are peripherally located in chromoplasts. The fine structure of isolated cl-and cr-nucleoids, purified either by Sepharose 4B-CL columns or by metrizamide gradients, was investigated electron microscopically. The cl-nucleoids consist of a central protein-rich core with 'naked' DNA-loops protruding from it. In cr-nucleoids, on the other hand, the total DNA is tightly packed within the proteinaceous core. The protein-containing core region of the nucleoids is made up of knotty and fibrillar sub-structures with diameters of 18 and 37 nm, respectively. After proteinase treatment, or incressing ion concentration, most of the proteins are removed and the DNA is exposed even in the case of cr-nucleoids, the stability of which proved to be greater than that of cl-nucleoids. The chemical composition of isolated plastid nucleoids has been determined qualitatively and quantitatively. Chromoplast-nucleoids contain, relative to the same DNA quantity, about six times as much protein as cl-nucleoids. Accordingly the buoyant density of cr-nucleoids in metrizamide gradients is higher than that of cl-nucleoids. In addition to DNA and protein, RNA could be found in the nucleoid fraction. No pigments were present. The cr-and cl-nucleoids have many identical proteins. There are, however, also characteristic differences in their protein pattern which are possibly related to the different expression of the genomes of chloroplasts and chromoplasts. Nucleoids of both plastid types contain some proteins which also occur in isolated envelope membranes (probably partly in the outer membrane) and thus possibly take part in binding the DNA to membranes. PMID:24248218

Hansmann, P; Falk, H; Ronai, K; Sitte, P

1985-07-01

119

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

120

The Effect of Pasteurization Temperature on Consumer Acceptability, Sensory Characteristics, Volatile Compound Composition, and ShelfLife of Fluid Milk  

Microsoft Academic Search

The relationship among consumer acceptability, de- scriptive sensory attributes, and shelf-life was deter- mined for 2% milk pasteurized at 77, 79, 82, and 85°C. Sensory descriptive attributes and volatile compound composition were monitored over the shelf-life of the products to determine if treatments could be differen- tiated at various times through out the shelf-life of the product. Consumers preferred 79°C

A. L. Gandy; M. W. Schilling; P. C. Coggins; C. H. White; Y. Yoon; V. V. Kamadia

2008-01-01

121

Behavioural early-life exposures and body composition at age 15 years  

PubMed Central

Background/Objectives: Previous studies have demonstrated associations between some early-life exposures and later obesity, but most have used body mass index in childhood or adulthood as the outcome. The objective of this study was to investigate whether early-life exposures were associated with directly measured fat and lean mass in adolescence. Subjects/Methods: This study used data on 4750 mother–offspring pairs, collected as a part of the Avon Longitudinal Study of Parents and Children, Bristol, UK between 1991 and 1992; associations between behavioural exposures occurring from conception up to 5 years of age (maternal and paternal smoking during pregnancy, breastfeeding, age at introduction to solids, dietary patterns and physical inactivity during early childhood) and offspring body composition measured by dual-energy X-ray absorptiometry at ~15 years were assessed. Results: After full adjustment for potential confounders, maternal smoking during pregnancy, having a junk food diet and spending more time watching television in early childhood were all associated with higher fat mass at age 15, whereas maternal smoking, having a healthy diet and playing computer games more frequently in early childhood were all associated with a higher lean mass at age 15. Associations with paternal smoking were generally weaker for both fat and lean mass, but as there was no strong statistical evidence for maternal vs paternal differences, confounding by social factors rather than a direct effect of maternal smoking cannot be ruled out. Early feeding was not associated with fat or lean mass at age 15. Conclusions: This study does not provide compelling evidence for associations between most early-life factors and body composition in adolescence. However, possible associations with dietary patterns and physical inactivity in early childhood require further investigation in other cohorts that have direct measurements of adolescent body composition. PMID:25664839

Leary, S D; Lawlor, D A; Davey Smith, G; Brion, M J; Ness, A R

2015-01-01

122

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

123

Modeling and life prediction methodology for Titanium Matrix Composites subjected to mission profiles  

NASA Technical Reports Server (NTRS)

Titanium matrix composites (TMC) are being evaluated as structural materials for elevated temperature applications in future generation hypersonic vehicles. In such applications, TMC components are subjected to complex thermomechanical loading profiles at various elevated temperatures. Therefore, thermomechanical fatigue (TMF) testing, using a simulated mission profile, is essential for evaluation and development of life prediction methodologies. The objective of the research presented in this paper was to evaluate the TMF response of the (0/90)2s SCS-6/Timetal-21S subjected to a generic hypersonic flight profile and its portions with a temperature ranging from -130 C to 816 C. It was found that the composite modulus, prior to rapid degradation, had consistent values for all the profiles tested. A micromechanics based analysis was used to predict the stress-strain response of the laminate and of the constituents in each ply during thermomechanical loading conditions by using only constituent properties as input. The fiber was modeled as elastic with transverse orthotropic and temperature dependent properties. The matrix was modeled using a thermoviscoplastic constitutive relation. In the analysis, the composite modulus degradation was assumed to result from matrix cracking and was modeled by reducing the matrix modulus. Fatigue lives of the composite subjected to the complex generic hypersonic flight profile were well correlated using the predicted stress in 0 degree fibers.

Mirdamadi, M.; Johnson, W. S.

1994-01-01

124

Spatial, temporal, and life history assumptions influence consistency of landscape effects on species distributions  

Microsoft Academic Search

Models describing relationships between landscape features and species distribution patterns often display inter-study inconsistencies.\\u000a Identifying factors contributing to these inconsistencies is a vital step in clarifying the ecological importance of landscape\\u000a features and synthesizing an effective knowledge base for use in conservation contexts. We examined the influence of several\\u000a spatial, temporal, and life history assumptions on the outcomes of distribution

Brian G. TaverniaJ; J. Michael Reed

2010-01-01

125

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

126

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

127

Preservation of classes of life distributions under weighting with a general weight function  

Microsoft Academic Search

In the paper a representation of weighted distributions is used to obtain some results concerning their relations with life distributions. Extensions of the results by Gupta [Gupta, R.C., Keating, J.P., 1986. Relations for the reliability measures under length biased sampling. Scand. J. Statist. 13, 49-56], Jain et al. [Jain, K., Singh, H., Bagai, I., 1989. Relations for the reliability measures

Pawel Blazej

2008-01-01

128

Multilayer electromechanical composites with controlled piezoelectric coefficient distribution  

E-print Network

. This technique is an extremely versatile method to fabricate displacement actuators to fabricate monolithic ceramic parts with controlled material property gradients. To obtain a quantifiable method to optimize-2875 ABSTRACT We have fabricated multilayer electromechanical composites with controlled piezoelectric

Aksay, Ilhan A.

129

Disparate distribution patterns between canopy and subcanopy life-forms in two temperate North American forests  

Microsoft Academic Search

Quantitative vegetational data of canopy and woody subcanopy species (two life-forms adapted to occupy different strata at maturity) were compared with data collected in two temperate forest ecosystems to determine whether they exhibit a similar pattern of distribution. Tidal freshwater swamps (21 stands) and southern Appalachian forests (19 stands) were examined from data obtained using identical sampling methods. Separate structural

R. D. Rheinhardt

1992-01-01

130

Distribution, ecology, life history, genetic variation, and risk of extinction of nonhuman primates from Costa Rica  

Microsoft Academic Search

We examined the association between geographic distribution, ecological traits, life history, genetic diversity , and risk of extinction in nonhuman primate species from Costa Rica. All of the current nonhuman pri- mate species from Costa Rica are included in the study; spider monkeys (Ateles geoffroyi), howling monkeys (Alouatta palliata), capuchins (Cebus capucinus), and squirrel monkeys (Saimiri oerstedii). Geographic distri- bution

María E. Zaldívar; Oscar Rocha; Kenneth E. Glander; Gabriel Aguilar; Ana S. Huertas; Ronald Sánchez; Grace Wong

2004-01-01

131

Life cycles and distribution of atherinids in the marine and estuarine waters of southern Australia  

Microsoft Academic Search

New and published data have been collated for the biology and distribution of atherinid species abundant in the coastal saline waters of Australia below 30°S. This information has been used to determine whether these species typically spawn at sea or pass through the whole of their life cycle in estuaries, and in one case, also lagoons and saline lakes. Length-frequency

I. C. Potter; W. Ivantsoff; R. Cameron; J. Minnard

1986-01-01

132

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

133

Mori–Tanaka models for the thermal conductivity of composites with interfacial resistance and particle size distributions  

Microsoft Academic Search

A Mori–Tanaka scheme is presented for modeling the overall thermal conduction behavior of composites containing reinforcements with interfacial resistances and prescribed size distributions. The approach is used for studying composites reinforced by spherical particles with monomodal and bimodal log-normal volume fraction distributions. Relevant effects of the distribution functions on the overall conductivity of the composites are found for particle volume

Helmut J. Böhm; Sergio Nogales

2008-01-01

134

Temperature Effects on Gametophyte Life-History Traits and Geographic Distribution of Two Cryptic Kelp Species  

PubMed Central

A major determinant of the geographic distribution of a species is expected to be its physiological response to changing abiotic variables over its range. The range of a species often corresponds to the geographic extent of temperature regimes the organism can physiologically tolerate. Many species have very distinct life history stages that may exhibit different responses to environmental factors. In this study we emphasized the critical role of the haploid microscopic stage (gametophyte) of the life cycle to explain the difference of edge distribution of two related kelp species. Lessonia nigrescens was recently identified as two cryptic species occurring in parapatry along the Chilean coast: one located north and the other south of a biogeographic boundary at latitude 29–30°S. Six life history traits from microscopic stages were identified and estimated under five treatments of temperature in eight locations distributed along the Chilean coast in order to (1) estimate the role of temperature in the present distribution of the two cryptic L. nigrescens species, (2) compare marginal populations to central populations of the two cryptic species. In addition, we created a periodic matrix model to estimate the population growth rate (?) at the five temperature treatments. Differential tolerance to temperature was demonstrated between the two species, with the gametophytes of the Northern species being more tolerant to higher temperatures than gametophytes from the south. Second, the two species exhibited different life history strategies with a shorter haploid phase in the Northern species contrasted with considerable vegetative growth in the Southern species haploid stage. These results provide strong ecological evidence for the differentiation process of the two cryptic species and show local adaptation of the life cycle at the range limits of the distribution. Ecological and evolutionary implications of these findings are discussed. PMID:22723987

Oppliger, L. Valeria; Correa, Juan A.; Engelen, Aschwin H.; Tellier, Florence; Vieira, Vasco; Faugeron, Sylvain; Valero, Myriam; Gomez, Gonzalo; Destombe, Christophe

2012-01-01

135

Embedded quasi-distributed sensor for composite material  

Microsoft Academic Search

This work presents the first example of structure mode shapes recovering by means of an embedded quasi-distributed fiber-optic sensor. The developed feed-forward quasi-distributed polarimetric sensor allows a distributed recovery of the structure strain while maintaining low- invasivity, high-sensitivity, and high spatial resolution. The first three modes of a CRFP cantilever have been recovered both in frequency and in modal shape

Valeria Gusmeroli; Mario Martinelli; Priscilla Escobar Rojo; Angelo Barberis

1993-01-01

136

Effects of branching characteristics and copolymer composition distribution on non-isothermal crystallization  

E-print Network

- orimetry (MDSC), and Crystaf. Several m-LLDPEs and an m-HDPE ­ all having comparable Mw and PDI ­ were; Copolymer composition distribution (CCD); Non-isothermal crystallization; MDSC 1. Introduction

Hussein, Ibnelwaleed A.

137

Moment distributions around holes in symmetric composite laminates subjected to bending moments  

NASA Technical Reports Server (NTRS)

An analytical investigation of the effects of holes on the moment distribution of symmetric composite laminates subjected to bending moments is described. A general, closed-form solution for the moment distribution of an infinite anisotropic plate is derived, and this solution is used to determine stress distributions both on the hole boundary and throughout the plate. Results are presented for several composite laminates that have holes and are subjected to either pure bending or cylindrical bending. Laminates with a circular hole or with an elliptical hole are studied. Laminate moment distributions are discussed, and ply stresses are described.

Prasad, C. B.; Shuart, M. J.

1989-01-01

138

Bayesian Analysis of Step-Stress Accelerated Life Test with Exponential Distribution  

SciTech Connect

In this article, we propose a general Bayesian inference approach to the step-stress accelerated life test with type II censoring. We assume that the failure times at each stress level are exponentially distributed and the test units are tested in an increasing order of stress levels. We formulate the prior distribution of the parameters of life-stress function and integrate the engineering knowledge of product failure rate and acceleration factor into the prior. The posterior distribution and the point estimates for the parameters of interest are provided. Through the Markov chain Monte Carlo technique, we demonstrate a nonconjugate prior case using an industrial example. It is shown that with the Bayesian approach, the statistical precision of parameter estimation is improved and, consequently, the required number of failures could be reduced.

Lee, J.; Pan, R.

2012-04-01

139

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

140

Electric-field distribution in composite media D. Cule and S. Torquato  

E-print Network

evaluate the density of states for three different continuum models of dielectric composites: the Hashin such as breakdown phenomenon2 and the nonlinear behavior of composites.3 Much of the work on field distributions has been carried out for lattice models using numerical4,5 and perturbation methods.6 Recently, con- tinuum

Torquato, Salvatore

141

Statistical Two-Scale Method for Strength Prediction of Composites with Random Distribution and Its Applications  

Microsoft Academic Search

A Statistical two-order and Two-Scale computational Method (STSM) based on two-scale homogenization approach is developed\\u000a and successfully applied to predicting the strength parameters of random particle reinforced composites. Firstly, the probability\\u000a distribution model of composites with random distribution of a great number of particles in any ? - size statistic screen,\\u000a as ?- size cell, is described. And then, the

Junzhi Cui; X. G. Yu; Fei Han; Yan Yu

142

Composite bridge behavior and load distribution influenced by shakedown and diaphragms  

E-print Network

for the degree of MASTER OF SCIENCE December 1991 Major Subject: Civil Engineering COMPOSITE BRIDGE BEHAVIOR AND LOAD DISTRIBUTION INFLUENCED BY SHAKEDOWN AND DIAPHRAGMS A Thesis by CHRISTOPHER MAX GILSTRAP approved as to style and content by: James S...COMPOSITE BRIDGE BEHAVIOR AND LOAD DISTRIBUTION INFLUENCED BY SHAKEDOWN AND DIAPHRAGMS A Thesis by CHRISTOPHER MAX GILSTRAP Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements...

Gilstrap, Christopher Max

1991-01-01

143

NMDA receptor function: subunit composition versus spatial distribution  

Microsoft Academic Search

NMDA receptors (NMDARs) play a pivotal role in the regulation of neuronal communication and synaptic function in the central nervous system. The subunit composition and compartmental localization of NMDARs in neurons affect channel activity and downstream signaling. This review discusses the distinct NMDAR subtypes and their function at synaptic, perisynaptic, and extrasynaptic sites of excitatory and inhibitory neurons. Many neurons

Georg Köhr

2006-01-01

144

Distributed multifunctional sensor network for composite structural state sensing  

NASA Astrophysics Data System (ADS)

Advanced fiber reinforced composite materials are becoming the main structural materials of next generation of aircraft because of their high strength and stiffness to weight ratios, and strong designability. In order to take full advantages of composite materials, there is a need to develop an embeddable multifunctional sensing system to allow a structure to "feel" and "think" its structural state. In this paper, the concept of multifunctional sensor network integrated with a structure, similar to the human nervous system, has been developed. Different types of network sensors are permanently integrated within a composite structure to sense structural strain, temperature, moisture, aerodynamic pressure; monitor external impact on the structure; and detect structural damages. Utilizing this revolutionary concept, future composite structures can be designed and manufactured to provide multiple modes of information, so that the structures have the capabilities for intelligent sensing, environmental adaptation and multi-functionality. The challenges for building such a structural state sensing system and some solutions to address the challenges are also discussed in the paper.

Qing, Xinlin P.; Wang, Yishou; Gao, Limin; Kumar, Amrita

2012-04-01

145

Multi-scale mechanism based life prediction of polymer matrix composites for high temperature airframe applications  

NASA Astrophysics Data System (ADS)

A multi-scale mechanism-based life prediction model is developed for high-temperature polymer matrix composites (HTPMC) for high temperature airframe applications. In the first part of this dissertation the effect of Cloisite 20A (C20A) nano-clay compounding on the thermo-oxidative weight loss and the residual stresses due to thermal oxidation for a thermoset polymer bismaleimide (BMI) are investigated. A three-dimensional (3-D) micro-mechanics based finite element analysis (FEA) was conducted to investigate the residual stresses due to thermal oxidation using an in-house FEA code (NOVA-3D). In the second part of this dissertation, a novel numerical-experimental methodology is outlined to determine cohesive stress and damage evolution parameters for pristine as well as isothermally aged (in air) polymer matrix composites. A rate-dependent viscoelastic cohesive layer model was implemented in an in-house FEA code to simulate the delamination initiation and propagation in unidirectional polymer composites before and after aging. Double cantilever beam (DCB) experiments were conducted (at UT-Dallas) on both pristine and isothermally aged IM-7/BMI composite specimens to determine the model parameters. The J-Integral based approach was adapted to extract cohesive stresses near the crack tip. Once the damage parameters had been characterized, the test-bed FEA code employed a micromechanics based viscoelastic cohesive layer model to numerically simulate the DCB experiment. FEA simulation accurately captures the macro-scale behavior (load-displacement history) simultaneously with the micro-scale behavior (crack-growth history).

Upadhyaya, Priyank

146

Elemental composition and size distribution of particulates in Cleveland, Ohio  

NASA Technical Reports Server (NTRS)

Measurements were made of the elemental particle size distribution at five contrasting urban environments with different source-type distributions in Cleveland, Ohio. Air quality conditions ranged from normal to air pollution alert levels. A parallel network of high-volume cascade impactors (5-state) were used for simultaneous sampling on glass fiber surfaces for mass determinations and on Whatman-41 surfaces for elemental analysis by neutron activation for 25 elements. The elemental data are assessed in terms of distribution functions and interrelationships and are compared between locations as a function of resultant wind direction in an attempt to relate the findings to sources.

King, R. B.; Fordyce, J. S.; Neustadter, H. E.; Leibecki, H. F.

1975-01-01

147

Composition of Autonomous Services with Distributed Data Flows and Computations  

E-print Network

frameworks, such as CORBA, J2EE and SOAP. The distributed data-flow approach allows direct data exchange@db.stanford.edu 5 Group Leader, Manufacturing Systems Integration Division, National Institute of Standards

Stanford University

148

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

149

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

150

Viscoelastic stress distributions and elastic properties in unidirectional composites with large volume fractions of fibers  

Microsoft Academic Search

In this work, the visco-elastic stress distributions and elastic properties of unidirectional graphite\\/polyimide composites have been examined as a function of the volume fraction of fibers. The stress distributions were determined by employing two different methods, namely the finite element method (FEM) assuming either hexagonal or square fiber arrangements, and the Eshelby method modified by Mori and Tanaka to account

B. Benedikt; P. Rupnowski; M. Kumosa

2003-01-01

151

Influence of meteorological conditions on aerosol vertical distribution and composition off the northeast American coastline  

Microsoft Academic Search

The size distribution and composition of lower tropospheric aerosols were measured off the northeast American coastline under clear air and disturbed meteorological conditions. Under the clear air conditions observed on 5 August 1982, with air flow from west to east, sulfate-rich stratified layers are the dominant feature of aerosol distribution in the lowest 3000 m of the troposphere. The encroachment

D. I. Sebacher; R. C. Harriss; W. R. Cofer III; E. V. Browell

1985-01-01

152

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

E-print Network

the fiber, using coaxial electrospinning35-43 among other approaches. Alternative methods of surfaceEffect of pH on Protein Distribution in Electrospun PVA/BSA Composite Nanofibers Christina Tang, A observe that the distribution of BSA is affected by the pH of the electrospinning solution. Therefore, we

Khan, Saad A.

153

Synergy: Sharing-Aware Component Composition for Distributed Stream Processing Systems  

E-print Network

. For QoS provision, Synergy performs QoS impact projection to examine whether the shared processing canSynergy: Sharing-Aware Component Composition for Distributed Stream Processing Systems Thomas and quality-of-service (QoS) pro- vision. In this paper we present Synergy, a distributed stream processing

Gu, Xiaohui "Helen"

154

Cutting glass fibre reinforced composites using CO 2 laser with multimodal-Gaussian distribution  

Microsoft Academic Search

This paper deals with cutting glass fibre reinforced plastic (GFRP) composites using a CO2 laser with multimodal-Gaussian power distribution. An analytical model is proposed which allows the depth of the kerf to be predicted as a function of the direction of beam travel in relation to the material being worked. The model allows us to describe the beam power distribution

G. Caprino; V. Tagliaferri; L. Covelli

1995-01-01

155

Changes in chemical composition and antioxidative properties of rye ginger cakes during their shelf-life.  

PubMed

Changes in chemical composition and antioxidative properties of rye ginger cakes during their shelf-life were investigated in this study. In particular, the changes in antioxidants content, antioxidative and reducing capacity, and Maillard reaction development in rye ginger cakes after long-term storage were addressed. Ginger cakes produced according to the traditional and current recipe were stored for 5 years at room temperature in a dark place. The total phenolic compounds (TPC), inositol hexaphosphate (IP6), reduced (GSH) and oxidised glutathione (GSSG) contents, antioxidant and reducing capacity and Maillard reaction products (MRPs) were determined in ginger cakes after storage and then compared to those measured after baking. After long-term storage a decrease in TPC and IP6 contents in cakes was noted. In contrast, an increase in antioxidative and reducing capacity of stored cakes was observed. Long-term storage induced formation of furosine, advanced and final Maillard reaction products and caused changes in both reduced and oxidised forms of glutathione. After long-term storage the modest changes in furosine, FAST index and browning in ginger cake formulated with dark rye flour may suggest that this product is the healthiest among others. Therefore, traditional rye ginger cakes can be considered as an example of a healthy food that is also relatively stable during long term storage as noted by the small chemical changes observed in its composition. PMID:22980898

Zieli?ski, Henryk; del Castillo, Maria Dolores; Przygodzka, Ma?gorzata; Ciesarova, Zuzana; Kukurova, Kristina; Zieli?ska, Danuta

2012-12-15

156

Space Station environmental control and life support system distribution and loop closure studies  

NASA Technical Reports Server (NTRS)

The NASA Space Station's environmental control and life support system (ECLSS) encompasses functional elements concerned with temperature and humidity control, atmosphere control and supply, atmosphere revitalization, fire detection and suppression, water recovery and management, waste management, and EVA support. Attention is presently given to functional and physical module distributions of the ECLSS among these elements, with a view to resource requirements and safety implications. A strategy of physical distribution coupled with functional centralization is for the air revitalization and water reclamation systems. Also discussed is the degree of loop closure desirable in the initial operational capability status Space Station's oxygen and water reclamation loops.

Humphries, William R.; Reuter, James L.; Schunk, Richard G.

1986-01-01

157

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

158

Compositional modelling of distributed-parameter B.M. Maschke  

E-print Network

is to be expected in the distributed-parameter case. However, in extending the theory as for instance exposed in [26'Automatique et de Genie des Procedes, Universite Claude Bernard Lyon-1, F-69622 Villeurbanne, Cedex, France Dept of its subsystems via their boundary variables; for example in the case of coupled fluid-solid dynamics

Schaft, Arjan van der

159

Event Composition in Time-dependent Distributed Systems  

Microsoft Academic Search

Many interesting application systems, ranging from work- flow management and CSCW to air traffic control, are event- driven a nd time-dependent and must i nteract with heteroge- neous components in the real world. Event services are used to glue together distributed components. They assume a vir- tual global time base to trigger actions and to order events. The notion of

Christoph Liebig; Mariano Cilia; Alejandro P. Buchmann

1999-01-01

160

Poly (?-caprolactone)\\/hydroxyapatite composites: effects of particle size, molecular weight distribution and irradiation on interfacial interaction and properties  

Microsoft Academic Search

Hydroxyapatite reinforced poly(?-caprolactone) composites with different particle sizes and molecular weight distributions were prepared using a simple melt-processing method. Some composites were modified by electron beam irradiation. Dynamic viscoelastic properties were investigated using dynamic mechanical thermal analysis (DMTA) and an advanced rheometric expansion system. The results showed that the composite with narrower molecular weight distribution and smaller particle sizes had

Biqiong Chen; Kang Sun

2005-01-01

161

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

PubMed

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. PMID:11976099

Sakano, Yuko; Pickering, Karen D; Strom, Peter F; Kerkhof, Lee J

2002-05-01

162

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

163

Biochemical composition of cephalopods with different life strategies, with special reference to a giant squid, Architeuthis sp  

Microsoft Academic Search

The present study is a comprehensive comparison of the biochemical composition (protein, lipid, glycogen and cholesterol contents, and amino acid and fatty acid profiles) of 14 species of cephalopods with different life strategies (benthic, nektobenthic, benthopelagic and pelagic) in distinct habitats (neritic, demersal, oceanic and deep sea), with special emphasis placed on a male Architeuthis sp. The giant squid showed

R. Rosa; J. Pereira; M. L. Nunes

2005-01-01

164

Overview No. 125 Design and life prediction issues for high-temperature engineering ceramics and their composites  

Microsoft Academic Search

Perspectives are presented on ceramics and ceramic matrix composites (CMCs) as high-temperature materials. The emphasis is on design and life prediction requirements and their role in directing research. Important themes include the relative roles of fracture toughness and inelastic strain (ductility), as well as scaling and stochastic effects caused by manufacturing defects. Ceramics with high toughness have been developed. However,

A. G. Evans

1997-01-01

165

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

166

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

167

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

168

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

169

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

170

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

171

Corona Characteristics of Distribution Line in Contact with Conductive Material and Life Estimation of Conductor Insulation  

NASA Astrophysics Data System (ADS)

In relation to the accidents due to bird nests in contact with overhead distribution lines, the authors investigated on life estimation of conductor insulation. The accident is often caused by crow or magpie. There is a region in which magpie is being specified to the protected bird in Japan. In that region, the nest in the breeding season can not be removed easily. Recently, metal wires are used for the nest material. When this conductive material is in contact with the distribution line and the arm, corona discharge will occur. The conductor insulation of the distribution line receives deterioration and there is a possibility of causing the accident. In this study, acceleration test was done to examine time from nest building to causing the accident in the distribution line. The acceleration factor based on the charge amount of corona and the influence of the applied voltage on corona characteristics were discussed. Moreover, the life of the conductor insulation was discussed from the V-t characteristics and the acceleration factor.

Yamashita, Takahiko; Fujishima, Tomoyuki; Kuba, Hiroyuki

172

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

173

Distributed Fiber Optic Strain Measurement Using Rayleigh Scatter in Composite Structures  

Microsoft Academic Search

\\u000a This paper presents the use of distributed fiber optic sensing to achieve centimeter level resolution strain data along the\\u000a entire length of a large composite beam. A 6.5 meter long composite beam, designed for use in a corrosive flue gas desulfurization\\u000a (FGD) unit, was instrumented. A section of optical fiber was embedded into a fiberglass rope, which in turn was

Eric E. Sanborn; Alex K. Sang; Ed Wesson; Donald E. Wigent; Gregory Lucier

174

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

175

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

176

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

177

Sleep EEG composition in the first three months of life in monozygotic and dizygotic twins.  

PubMed

We investigated genetic influence on sleep electroencephalogram (EEG) composition by a classical twin study of monozygotic (MZ) and dizygotic (DZ) twins in the first 3 months of life. Polysomnographic (PSG) recordings were obtained in 10 MZ and 20 DZ twin pairs in the 37th, 46th, and 52nd week of postmenstrual age (PMA). The EEG power spectra were generated on the basis of fast Fourier transformation (FFT). Genetic influence on active sleep/rapid eye movement (AS/REM)] and quiet sleep/non rapid eye movement (QS/NREM) sleep composition was estimated by calculating within pair concordance and the intraclass correlation coefficients (ICCs) for delta (0.5-3.5 Hz), theta (4-7.5 Hz), alpha (8-11.5 Hz), sigma (12-14 Hz), and beta (14.5-20 Hz) at central derivation. MZ twins show higher ICCs than DZ twins for alpha, sigma, and beta spectral powers during QS/NREM sleep in the 37th, 46th, and 52nd week PMA. However, there was no significant difference (P > .05) between the 2 types of twins in absolute differences of EEG spectral power of the alpha, beta, and sigma frequency ranges in the 37th, 46th, and 52nd week PMA. The greatest mean absolute difference within MZ and DZ twin pairs and also between MZ and DZ twin groups was identified in the delta frequency range. Our findings gave an indication of genetic influence on alpha, sigma, and beta frequency ranges in the QS/NREM sleep stage. PMID:24323198

Vucinovic, Mirjana; Kardum, Goran; Bonkovic, Mirjana; Resic, Biserka; Ursic, Anita; Vukovics, Jonatan

2014-07-01

178

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

179

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

180

Simulations of Fiber Distribution Effects in Fiber-Reinforced Cement Composites  

SciTech Connect

This paper describes a lattice model for coupled moisture transport/stress analyses of fiber-reinforced cement composites (FRCC). Each fiber, and its interface with the matrix material, is explicitly represented within the three-dimensional material volume. This enables the direct study of fiber orientation and distribution effects on composite performance. Realistic, nonuniform fiber distributions can be specified as model input. Basic applications of the model are presented, with emphasis toward simulating the durability mechanics of FRCC exposed to drying environments. The modeling of functionally graded FRCC is an obvious potential extension of this work.

Bolander, John E. [Department of Civil and Environmental Engineering, University of California, Davis Davis, CA 95616-5294 (United States); Lim, Yun Mook [School of Civil and Environmental Engineering, Yonsei University, Seoul 120-749 (Korea, Republic of)

2008-02-15

181

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

182

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

183

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

184

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

185

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

186

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

187

THE ECOLOGICAL BOUNDARIES OF SIX CAROLINA BAYS: COMMUNITY COMPOSITION AND ECOTONE DISTRIBUTION  

E-print Network

of Biology P.O. Box 261954 Coastal Carolina University Conway, South Carolina, USA 29528-6054 E-mail: Joluken rims of each of six Carolina bays in northeastern South Carolina to characterize the community gradientTHE ECOLOGICAL BOUNDARIES OF SIX CAROLINA BAYS: COMMUNITY COMPOSITION AND ECOTONE DISTRIBUTION

Hutchens, John

188

Composition, Abundance and Distribution of Zooplankton in the Bay of Bengal  

Microsoft Academic Search

A 58 days-collaborative survey (25 October-21 December, 2007) of the BIMSTEC member countries (Bangladesh, India, Myanmar, Sri Lanka, Nepal and Thailand) was carried on in the Bay of Bengal in order to elucidate the fertility of the area as a new fishery ground. The purpose of this study was to determine the composition, abundance and distribution of zooplankton in 3

Issarapon Jitlang; Sunan Pattarajinda; Ramananda Mishra

189

The Ichthyoplankton of Selected Estuaries in Sarawak and Sabah: Composition, Distribution and Habitat Affinities  

Microsoft Academic Search

The ichthyoplankton assemblages of 23 estuaries in Sarawak and Sabah were surveyed with particular reference to the culturally and commercially important clupeidTenualosa toli. The species composition, distribution and density of all fish larvae were recorded, together with the physical characteristics of each estuary. A more detailed study was made of the Lupar and Lassa estuaries, which are the ‘core area’

S. J. M. Blaber; M. J. Farmer; D. A. Milton; J. Pang; O. Boon-Teck; P. Wong

1997-01-01

190

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

191

DAMAGE DETECTION IN COMPOSITE STRUCTURES FROM FIBRE OPTIC DISTRIBUTED STRAIN MEASUREMENTS  

E-print Network

of the technique. . KEYWORDS : Rayleigh scattering, fibre optic sensors. INTRODUCTION FBG (Fibre Bragg GratingDAMAGE DETECTION IN COMPOSITE STRUCTURES FROM FIBRE OPTIC DISTRIBUTED STRAIN MEASUREMENTS Alfredo of backscattered radiation), placing the plain optical fibre at the region where damage is expected. Because of its

Boyer, Edmond

192

Composition-resolved size distributions of volcanic aerosols in the Mt. Etna plumes  

Microsoft Academic Search

Particle size distributions for soluble and insoluble species in Mt. Etna's summit plumes were measured across an extended size range (10 nm < d < 100 ?m) using a combination of techniques. Automated scanning electron microscopy (QEMSCAN) was used to chemically analyze many thousands of insoluble particles (collected on pumped filters) allowing the relationships between particle size, shape, and composition

R. S. Martin; T. A. Mather; D. M. Pyle; M. Power; A. G. Allen; A. Aiuppa; C. J. Horwell; E. P. W. Ward

2008-01-01

193

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

194

Oceanic distribution and life cycle of Calanus species in the Norwegian Sea and adjacent waters  

NASA Astrophysics Data System (ADS)

The distribution and demography of Calanus finmarchicus, C. glacialis and C. hyperboreus were studied throughout their growth season on a basin scale in the Norwegian Sea using ordination techniques and generalized additive models. The distribution and demographic data were related to the seasonal development of the phytoplankton bloom and physical characteristics of water masses. The resulting quantified relationships were related to knowledge on life cycle and adaptations of Calanus species. C. finmarchicus was the numerically dominant Calanus species in Coastal, Atlantic and Arctic waters, showing strong association with both Atlantic and Arctic waters. C. hyperboreus and C. glacialis were associated with Arctic water; however, C. glacialis was occasionally observed in the Norwegian Sea and is probably an expatriate advected into the area from various origins. Demography indicated one generation per year of C. finmarchicus, a two-year life cycle of C. hyperboreus, and both one- and two-year life cycles for C. glacialis in the water masses where they were most abundant. For the examined Calanus species, young copepodites of the new generation seemed to be tuned to the phytoplankton bloom in their main water mass. The development of C. finmarchicus was delayed in Arctic water, and mis-match between feeding stages and the phytoplankton bloom may reduce survival and reproductive success of C. finmarchicus in Arctic water. Based on low abundances of C. hyperboreus CI-III in Atlantic water and main recruitment to CI prior to the phytoplankton bloom, we suggest that reproduction of C. hyperboreus in Atlantic water is not successful.

Broms, Cecilie; Melle, Webjørn; Kaartvedt, Stein

2009-10-01

195

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

196

Determing Lamprey Species Composition, Larval Distribution, and Adult Abundance in the Deschutes River, Oregon, Subbasin; 2005-2006 Annual Report.  

SciTech Connect

Information about lamprey species composition, distribution, life history, abundance, habitat requirements, and exploitation in the lower Deschutes River Subbasin is extremely limited. During 2002, we began a multi-year study to assess the status of lamprey in the Deschutes River subbasin. The objectives of this project are to determine ammocoete (larval lamprey) distribution and associated habitats; Lampretra species composition; numbers of emigrants; adult escapement and harvest rates at Sherars Falls. This report describes the preliminary results of data collected during 2005. We continued documenting ammocoete (larval) habitat selection by surveying four perennial eastside tributaries to the Deschutes River (Warm Springs River, Badger, Beaver and Shitike creeks) within the known ammocoete distribution. The results of 2003-2005 sampling indicate that positive relationships exist between: presence of wood (P = < 0.001), depositional area (P = < 0.001), flow (P = < 0.001), and fine substrate (P = < 0.001). Out-migrants numbers were not estimated during 2005 due to our inability to recapture marked larvae. In Shitike Creek, ammocoete and microphthalmia out-migration peaked during November 2005. In the Warm Spring River, out-migration peaked for ammocoetes in April 2006 and December 2005 for microphthalmia. Samples of ammocoetes from each stream were retained in a permanent collection of future analysis. An escapement estimate was generated for adult Pacific lamprey in the lower Deschutes River using a two event mark-recapture experiment during run year 2005. A modified Peterson model was used to estimate the adult population of Pacific lamprey at 3,895 with an estimated escapement of 2,881 during 2005 (95% CI= 2,847; M = 143; C = 1,027 R = 37). A tribal creel was also conducted from mid-June through August. We estimated tribal harvest to be approximately 1,015 adult lamprey during 2005 (95% CI= +/- 74).

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

2006-05-01

197

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

PubMed Central

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 and the species that inhabit the Southern Ocean. Oceanographically, the Southern Ocean is a major driver of global ocean circulation and plays a vital role in interacting with the deep water circulation in each of the Pacific, Atlantic, and Indian oceans. The Census of Antarctic Marine Life and the Scientific Committee on Antarctic Research Marine Biodiversity Information Network (SCAR-MarBIN) have strived to coordinate and unify the available scientific expertise and biodiversity data to improve our understanding of Southern Ocean biodiversity. Taxonomic lists for all marine species have been compiled to form the Register of Antarctic Marine Species, which currently includes over 8,200 species. SCAR-MarBIN has brought together over 1 million distribution records for Southern Ocean species, forming a baseline against which future change can be judged. The sample locations and numbers of known species from different regions were mapped and the depth distributions of benthic samples plotted. Our knowledge of the biodiversity of the Southern Ocean is largely determined by the relative inaccessibility of the region. Benthic sampling is largely restricted to the shelf; little is known about the fauna of the deep sea. The location of scientific bases heavily influences the distribution pattern of sample and observation data, and the logistical supply routes are the focus of much of the at-sea and pelagic work. Taxa such as mollusks and echinoderms are well represented within existing datasets with high numbers of georeferenced records. Other taxa, including the species-rich nematodes, are represented by just a handful of digital records. PMID:20689841

Griffiths, Huw J.

2010-01-01

198

Evaluation of flawed composite structural components under static and cyclic loading. [fatigue life of graphite-epoxy composite materials  

NASA Technical Reports Server (NTRS)

The effects of initial defects on the fatigue and fracture response of graphite-epoxy composite laminates are presented. The structural laminates investigated were a typical angle ply laminate, a polar/hoop wound pressure vessel laminate, and a typical engine fan blade laminate. Defects investigated were full and half penetration circular holes, full and half penetration slits, and countersink holes. The effects of the defect size and type on the static fracture strength, fatigue performance, and residual static strength are shown as well as the results of loadings on damage propagation in composite laminates. The data obtained were used to define proof test levels as a qualification procedure in composite structure subjected to cyclic loading.

Porter, T. R.

1979-01-01

199

Effect of ceramic thickness and composite bases on stress distribution of inlays - a finite element analysis.  

PubMed

The purpose of this study was to determine the effect of cavity depth, ceramic thickness, and resin bases with different elastic modulus on von Mises stress patterns of ceramic inlays. Tridimensional geometric models were developed with SolidWorks image software. The differences between the models were: depth of pulpal wall, ceramic thickness, and presence of composite bases with different thickness and elastic modulus. The geometric models were constrained at the proximal surfaces and base of maxillary bone. A load of 100 N was applied. The stress distribution pattern was analyzed with von Mises stress diagrams. The maximum von Mises stress values ranged from 176 MPa to 263 MPa and varied among the 3D-models. The highest von Mises stress value was found on models with 1-mm-thick composite resin base and 1-mm-thick ceramic inlay. Intermediate values (249-250 MPa) occurred on models with 2-mm-thick composite resin base and 1-mm-thick ceramic inlay and 1-mm-thick composite resin base and 2-mm-thick ceramic inlay. The lowest values were observed on models restored exclusively with ceramic inlay (176 MPa to 182 MPa). It was found that thicker inlays distribute stress more favorably and bases with low elastic modulus increase stress concentrations on the internal surface of the ceramic inlay. The increase of ceramic thickness tends to present more favorable stress distribution, especially when bonded directly onto the cavity without the use of supporting materials. When the use of a composite base is required, composite resin with high elastic modulus and reduced thickness should be preferred. PMID:25831105

Durand, Letícia Brandão; Guimarães, Jackeline Coutinho; Monteiro Junior, Sylvio; Baratieri, Luiz Narciso

2015-01-01

200

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

201

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

202

Reliability and life prediction of ceramic composite structures at elevated temperatures  

NASA Technical Reports Server (NTRS)

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

203

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

204

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

205

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

206

Initial fate of prions upon peripheral infection: half-life, distribution, clearance, and tissue uptake  

PubMed Central

Prion diseases are infectious neurodegenerative disorders associated with the misfolded prion protein (PrPSc), which appears to be the sole component of the infectious agent (termed prion). To produce disease, prions have to be absorbed into the body and reach sufficient quantities in the brain. Very little is known about the biological mechanisms controlling the initial fate of prions. Here, we studied the systemic pharmacokinetics and biodistribution of PrPSc in vivo. After an intravenous injection of highly purified radiolabeled or native unlabeled PrPSc, the protein was eliminated rapidly from the serum (half-life of 3.24 h), mostly through tissue uptake. The quantity of intact PrPSc reaching the brain was ?0.2% of the injected dose per gram of brain tissue (ID/g). The highest levels were found in liver (?20% ID/g), spleen (?13% ID/g), and kidney (?7.4% ID/g). Cell surface PrPC does not appear to play a role in PrPSc pharmacokinetics, since the infectious protein distributed similarly in wild-type and PrP-null mice. To measure tissue uptake kinetics and biodistribution accurately, vascular space in tissues was measured with radioactively labeled albumin coinjected with radioactively labeled PrPSc. Our results provide a fundamental pharmacokinetic characterization of PrPSc in vivo, which may be relevant to estimate tissue risks and mechanisms of prion neuroinvasion and to identify novel therapeutic strategies.—Urayama, A., Morales, R., Niehoff, M. L., Banks, W. A., Soto, C. Initial fate of prions upon peripheral infection: half-life, distribution, clearance, and tissue uptake PMID:21555356

Urayama, Akihiko; Morales, Rodrigo; Niehoff, Michael L.; Banks, William A.; Soto, Claudio

2011-01-01

207

Hierarchical Process Composition: Dynamic maintenance of structure in a distributed environment. Doctoral thesis  

SciTech Connect

This dissertation is an in-depth study of a method, called Hierarchial Process Composition (HPC), for organizing, developing, and maintaining large distributed programs. HPC extends the process abstraction to nested collections of processes, allowing a multiprocess program in place of any single process, and provides a rich set of structuring mechanisms for building distributed applications. The emphasis in HPC is on structural and architectural issues in distributed software systems, especially interactions involving dynamic reconfiguration, protection, and distribution. The major contributions of this work come from the detailed consideration, based on case studies, formal analysis, and a prototype implementation, of how abstraction and composition interact in unexpected ways with each other and with a distributed environment. HPC ties processes together with heterogeneous interprocess communication mechanisms, such as TCP/IP and remote-procedure call. Explicit structure determines the logical connectivity between processes, masking differences in communication mechanisms. HPC supports one-to-one, parallel channel, and many-to-many (multicasting) connectivity. Efficient computation of end-to-end connectivity from the communication structure is a challenging problem, and a third-party connection facility is needed to implement dynamic reconfiguration when the logical connectivity changes.

Friedberg, S.A.

1988-01-01

208

Stable carbon isotope composition, depth distribution and fate of macroalgae from the Antarctic Peninsula region  

Microsoft Academic Search

Stable carbon isotope composition of macroalgae collected at King George Island (Antarctica) ranged from about -8‰ to -34‰. We hypothesize that the d13C values are related to the depth distribution: species inhabiting greater depth had much lower values (around-30‰) compared to species from shallower waters (around -17‰). Isotopic studies on sediment trap samples from the King George Basin (2,000 m

G. Fischer; C. Wiencke

1992-01-01

209

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

210

Composition, structure, and distribution of woody vegetation on the Cache River Floodplain, Arkansas  

Microsoft Academic Search

This study characterizes the species composition, structure, and distribution of woody plants on the floodplain of the Cache\\u000a River in northeastern Arkansas. Trees, saplings, and shrubs were sampled in 249 plots along with 28 environmental variables.\\u000a Classification of the plots resulted in four forest dominance types being identified. The basal area, density, species richness,\\u000a and diversity of these four types

R. Daniel Smith

1996-01-01

211

On species composition and distribution of lanternfish larvae (Myctophidae) in the eastern South Pacific  

Microsoft Academic Search

The results of the study of species composition and distribution of lanternfish larvae (Myctophidae) in July through September\\u000a of 1980 in open waters of the eastern South Pacific in areas situated beyond the 200-mile zones of Ecuador, Peru, and Chile\\u000a are provided. In collections of ichthyoplankton from this region, larvae of 19 taxonomic forms of myctophids were found, of\\u000a which

S. A. Evseenko

2006-01-01

212

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

213

Fatigue properties of jointed wood composites Part II Life prediction analysis for variable amplitude loading  

Microsoft Academic Search

A method of predicting lifetime to failure for any wood composite system subjected to a complex load–time history has been developed. The prediction first requires the generation of a simple model to characterize the fatigue response of the particular composite system and a rainflow analysis breakdown of the load–time history under investigation. Once the models are derived they can be

I. P. Bond; M. P. Ansell

1998-01-01

214

Influence of meteorological conditions on aerosol vertical distribution and composition off the northeast American coastline  

NASA Technical Reports Server (NTRS)

The size distribution and composition of lower tropospheric aerosols were measured off the northeast American coastline under clear air and disturbed meteorological conditions. Under the clear air conditions observed on 5 August 1982, with air flow from west to east, sulfate-rich stratified layers are the dominant feature of aerosol distribution in the lowest 3000 m of the troposphere. The encroachment of a warm frontal system over the study area on 9 August 1982 resulted in dramatic changes in aerosol distribution and composition prior to any precipitation, probably due to increased vertical mixing and dilution of pollutant aerosols. Chloride becomes the dominant water soluble anion in the lower 3000 m, primarily due to a several fold decrease in sulfate. Although these results are limited to only two sets of measurements, the data indicate the variability which can occur in the tropospheric vertical aerosol distributions at remote locations. A knowledge of the structure and stability of these stratified layers is of particular importance to studies of the ocean-troposphere chemistry problem.

Sebacher, D. I.; Harriss, R. C.; Cofer, W. R., III; Browell, E. V.

1985-01-01

215

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

216

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...

217

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)...

218

Connection of stratospheric QBO with global atmospheric general circulation and tropical SST. Part I: methodology and composite life cycle  

NASA Astrophysics Data System (ADS)

The stratospheric quasi-biennial oscillation (QBO) and its association with the interannual variability in the stratosphere and troposphere, as well as in tropical sea surface temperature anomalies (SSTA), are examined in the context of a QBO life cycle. The analysis is based on the ERA40 and NCEP/NCAR reanalyses, radiosonde observations at Singapore, and other observation-based datasets. Both reanalyses reproduce the QBO life cycle and its associated variability in the stratosphere reasonably well, except that some long-term changes are detected only in the NCEP/NCAR reanalysis. In order to separate QBO from variability on other time scales and to eliminate the long-term changes, a scale separation technique [Ensemble Empirical Mode Decomposition (EEMD)] is applied to the raw data. The QBO component of zonal wind anomalies at 30 hPa, extracted using the EEMD method, is defined as a QBO index. Using this index, the QBO life cycle composites of stratosphere and troposphere variables, as well as SSTA, are constructed and examined. The composite features in the stratosphere are generally consistent with previous investigations. The correlations between the QBO and tropical Pacific SSTA depend on the phase in a QBO life cycle. On average, cold (warm) SSTA peaks about half a year after the maximum westerlies (easterlies) at 30 hPa. The connection of the QBO with the troposphere seems to be associated with the differences of temperature anomalies between the stratosphere and troposphere. While the anomalies in the stratosphere propagate downward systematically, some anomalies in the troposphere develop and expand vertically. Therefore, it is possible that the temperature difference between the troposphere and stratosphere may alter the atmospheric stability and tropical deep convection, which modulates the Walker circulation and SSTA in the equatorial Pacific Ocean.

Huang, Bohua; Hu, Zeng-Zhen; Kinter, James L.; Wu, Zhaohua; Kumar, Arun

2012-01-01

219

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

220

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

221

Enhancing Composition Window of Bicontinuous Structures by Designed Polydispersity Distribution of ABA Triblock Copolymers  

E-print Network

The phase behavior of polydisperse ABA triblock copolymers is studied using dissipative particle dynamics simulations, focusing on the emergence and property of bicontinuous structures. Bicontinuous structures are characterized by two separate, intermeshed nanoscopic domains extending throughout the material. The connectivity of polymeric bicontinuous structures makes them highly desirable for many applications. For conventional monodisperse diblock and triblock copolymers, regular bicontinuous structures (i.e., gyroid and Fddd) can be formed over a narrow composition window of ~3%. We demonstrate that the composition window for the formation of bicontinuous structures can be regulated by designed polydispersity distributions of ABA triblock copolymers. In particular, introducing polydispersity in both A and B blocks can lead to a significant enhancement of the composition window of bicontinuous structures with both continuous A and B domains. The mechanism of the bicontinuous structure enhancement is elucidated from the distribution of the long and short blocks. Furthermore, it is shown that the polymeric bicontinuous structures from polydisperse ABA triblock copolymers possess good continuity throughout the sample, making them ideal candidates for advanced applications.

Yue Li; Hu-Jun Qian; Zhong-Yuan Lu; An-Chang Shi

2013-10-22

222

Phylogenetic diversity, composition and distribution of bacterioplankton community in the Dongjiang River, China.  

PubMed

Bacterioplankton community compositions in the Dongjiang River were characterized using denaturing gradient gel electrophoresis (DGGE) and 16S rRNA gene clone library construction. Water samples in nine different sites were taken along the mainstem and three tributaries. In total, 24 bands from DGGE gels and 406 clones from the libraries were selected and sequenced, subsequently analyzed for the bacterial diversity and composition of those microbial communities. Bacterial 16S rRNA gene sequences from freshwater bacteria exhibited board phylogenetic diversity, including sequences representing the Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Actinobacteria, Bacteriodetes, Verrucomicrobia, and candidate division TM7. Members of Betaproteobacteria group were the most dominant in all sampling sites, followed by Gammaproteobacteria, Alphaproteobacteria, and Actinobacteria. DGGE profiles and the ?-LIBSHUFF analysis revealed similar patterns of bacterial diversity among most sampling sites, while spatial distribution variances existed in all sites along the river basin. Statistical analysis showed that bacterial species distribution strongly correlated with environmental variables, such as nitrate and ammonia, suggesting that nitrogen nutrients may shape the microbial community structure and composition in the Dongjiang River. This study had important implications for the comparison with other rivers elsewhere and contributed to the growing data set on the factors that structure bacterial communities in freshwater ecosystems. PMID:22133045

Liu, Zhenghui; Huang, Shaobin; Sun, Guoping; Xu, Zhencheng; Xu, Meiying

2012-04-01

223

Assembly and intracellular distribution of kainate receptors is determined by RNA editing and subunit composition.  

PubMed

Kainate receptors (KARs) modulate neuronal network activity. The molecular mechanisms that control the assembly and trafficking of KARs are unclear. Here, we examined the role of Q/R editing and subunit composition on KAR subunit assembly and subcellular distribution. The majority of GluK2 subunits undergo editing at the Q/R site in the channel pore loop. Cell surface biotinylation, cross-linking, Endoglycosidase-H analysis and gradient separation of KAR subunit assembly states revealed that Q/R editing reduces oligomerization, endoplasmic reticulum (ER) export, plasma membrane expression and stability of homomeric GluK2-containing KARs. These results indicate that Q/R editing of GluK2 may orchestrate channel subunit composition during KAR assembly in the ER. GluK2/GluK5 heteromers are the most abundant KAR subtype in the brain. While subcellular fractionation of brain tissue confirmed that both GluK2/3 and GluK5 are present in synaptosomes and tightly associated with post-synaptic density fractions, biochemical analysis revealed that endogenous GluK2/3 subunits show less complete assembly and trafficking compared with GluK5. In transgenic mice, the loss of the key assembly partner GluK2 leads to dramatic reduction in GluK5 expression. These results support the idea that the assembly and intracellular distribution of KARs is determined by RNA editing at the Q/R site and subunit composition. PMID:20626562

Ball, Simon M; Atlason, Palmi T; Shittu-Balogun, Olayemi O; Molnár, Elek

2010-09-01

224

Effects of diet macronutrient composition on body composition and fat distribution during weight maintenance and weight loss  

PubMed Central

Qualitative aspects of diet may affect body composition and propensity for weight gain or loss. We tested the hypothesis that consumption of a relatively low glycemic load (GL) diet would reduce total and visceral adipose tissue under both eucaloric and hypocaloric conditions. Participants were 69 healthy overweight men and women. Body composition was assessed by DXA and fat distribution by CT scan at baseline, after 8 weeks of a eucaloric diet intervention, and after 8 weeks of a hypocaloric (1000 kcal/d deficit) diet intervention. Participants were provided all food for both phases, and randomized to either a low GL diet (?45 points per 1000 kcal; n=40) or high GL diet (>75 points per 1000 kcal, n=29). After the eucaloric phase, participants who consumed the low GL diet had 11% less intra-abdominal fat (IAAT) than those who consumed the high GL diet (P<0.05, adjusted for total fat mass and baseline IAAT). Participants lost an average of 5.8 kg during the hypocaloric phase, with no differences in the amount of weight loss with diet assignment (P=0.39). Following weight loss, participants who consumed the low GL diet had 4.4% less total fat mass than those who consumed the high GL diet (P<0.05, adjusted for lean mass and baseline fat mass). Consumption of a relatively low GL diet may affect energy partitioning, both inducing reduction in IAAT independent of weight change, and enhancing loss of fat relative to lean mass during weight loss. PMID:23671029

Goss, Amy M.; Goree, Laura Lee; Ellis, Amy C.; Chandler-Laney, Paula C.; Casazza, Krista; Lockhart, Mark E.; Gower, Barbara A.

2012-01-01

225

Exobiology, the study of the origin, evolution and distribution of life within the context of cosmic evolution: a review  

Microsoft Academic Search

The primary goal of exobiological research is to reach a better understanding of the processes leading to the origin, evolution and distribution of life on Earth or elsewhere in the universe. In this endeavour, scientists from a wide variety of disciplines are involved, such as astronomy, planetary research, organic chemistry, palaeontology and the various subdisciplines of biology including microbial ecology

G. Horneck

1995-01-01

226

On the Relationship Between Site Geology and the Distribution of Surface Regolith Compositions at the Apollo Sites  

NASA Technical Reports Server (NTRS)

Some considerations are discussed on how information on site geology can be obtained from the distribution of data points on 2-element plots of composition of lunar regolith samples collected along a traverse.

Korotev, Randy L.

2000-01-01

227

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

228

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

229

A study of stiffness, residual strength and fatigue life relationships for composite laminates  

NASA Technical Reports Server (NTRS)

Qualitative and quantitative exploration of the relationship between stiffness, strength, fatigue life, residual strength, and damage of unnotched, graphite/epoxy laminates subjected to tension loading. Clarification of the mechanics of the tension loading is intended to explain previous contradictory observations and hypotheses; to develop a simple procedure to anticipate strength, fatigue life, and stiffness changes; and to provide reasons for the study of more complex cases of compression, notches, and spectrum fatigue loading. Mathematical models are developed based upon analysis of the damage states. Mathematical models were based on laminate analysis, free body type modeling or a strain energy release rate. Enough understanding of the tension loaded case is developed to allow development of a proposed, simple procedure for calculating strain to failure, stiffness, strength, data scatter, and shape of the stress-life curve for unnotched laminates subjected to tension load.

Ryder, J. T.; Crossman, F. W.

1983-01-01

230

The chemical composition and nitrogen distribution of Chinese yak (Maiwa) milk.  

PubMed

The paper surveyed the chemical composition and nitrogen distribution of Maiwa yak milk, and compared the results with reference composition of cow milk. Compared to cow milk, yak milk was richer in protein (especially whey protein), essential amino acids, fat, lactose and minerals (except phosphorus). The contents of some nutrients (total protein, lactose, essential amino acids and casein) were higher in the warm season than in the cold season. Higher ratios of total essential amino acids/total amino acids (TEAA/TAA) and total essential amino acids/total non essential amino acids (TEAA/TNEAA) were found in the yak milk from the warm season. However its annual average ratio of EAA/TAA and that of EAA/NEAA were similar to those of cow milk. Yak milk was rich in calcium and iron (p < 0.05), and thus may serve as a nutritional ingredient with a potential application in industrial processing. PMID:21954332

Li, Haimei; Ma, Ying; Li, Qiming; Wang, Jiaqi; Cheng, Jinju; Xue, Jun; Shi, John

2011-01-01

231

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.

Cornell Center for Materials Research

2003-01-01

232

Free-standing carbon nanotube composite sensing skin for distributed strain sensing in structures  

NASA Astrophysics Data System (ADS)

The technical challenges of managing the health of critical infrastructure systems necessitate greater structural sensing capabilities. Among these needs is the ability for quantitative, spatial damage detection on critical structural components. Advances in material science have now opened the door for novel and cost-effective spatial sensing solutions specially tailored for damage detection in structures. However, challenges remain before spatial damage detection can be realized. Some of the technical challenges include sensor installations and extensive signal processing requirements. This work addresses these challenges by developing a patterned carbon nanotube composite thin film sensor whose pattern has been optimized for measuring the spatial distribution of strain. The carbon nanotube-polymer nanocomposite sensing material is fabricated on a flexible polyimide substrate using a layer-by-layer deposition process. The thin film sensors are then patterned into sensing elements using optical lithography processes common to microelectromechanical systems (MEMS) technologies. The sensor array is designed as a series of sensing elements with varying width to provide insight on the limitations of such patterning and implications of pattern geometry on sensing signals. Once fabrication is complete, the substrate and attached sensor are epoxy bonded to a poly vinyl composite (PVC) bar that is then tested with a uniaxial, cyclic load pattern and mechanical response is characterized. The fabrication processes are then utilized on a larger-scale to develop and instrument a component-specific sensing skin in order to observe the strain distribution on the web of a steel beam. The instrumented beam is part of a larger steel beam-column connection with a concrete slab in composite action. The beam-column subassembly is laterally loaded and strain trends in the web are observed using the carbon nanotube composite sensing skin. The results are discussed in the context of understanding the properties of the thin film sensor and how it may be advanced toward structural sensing applications.

Burton, Andrew R.; Minegishi, Kaede; Kurata, Masahiro; Lynch, Jerome P.

2014-04-01

233

General models for resource use or other compositional count data using the Dirichlet-multinomial distribution.  

PubMed

Many ecological studies investigate how organisms use resources, such as habitats or foods, in relation to availability or other variables. Related statistical problems include analysis of proportions of species or genotypes in a community or population. These require statistical modeling of compositional count data: data on relative proportions of each category collected as counts. Common methods for analyzing compositional count data lack one or more important considerations. Some methods lack explicit accommodation of count data, dealing instead with proportions. Others do not handle between-sample heterogeneity for overdispersed data. Yet others do not allow general types of relationships between explanatory variables and resource use. All three components have been combined in a Bayesian framework, but for frequentist hypothesis tests and AIC model selection, maximum-likelihood estimation is needed. Here we propose the Dirichlet-multinomial distribution to accommodate overdispersed compositional count data. This approach can be used flexibly in combination with explanatory models, but the only correlations among compositional proportions that it can accommodate are the negative correlations due to the fact that proportions must sum to 1. Many existing models can be generalized to use the Dirichlet-multinomial distribution for residual variation, and the flexibility of the approach allows new hypotheses that have often not been considered in resource preference analysis, including that availability has no relation to use. We also highlight a new design for resource use studies, with multiple individual-use data sets from each of multiple sites, with different explanatory data for each site. We illustrate the approach with three examples. For two previously published habitat use data sets, we support the original conclusions and show that use is not unrelated to availability. For a data set of pollen collected by multiple bees from each of two sites, pollen use differs between the sites. Using bootstrap goodness-of-fit tests, we illustrate that the Dirichlet-multinomial is acceptable for two of the examples but unsuitable for one of the habitat use examples. PMID:24597215

De Valpine, Perry; Harmon-Threatt, Alexandra N

2013-12-01

234

Semi-automatic web service composition for the life sciences using the BioMoby semantic web framework.  

PubMed

Researchers in the life-sciences are currently limited to small-scale informatics experiments and analyses because of the lack of interoperability among life-sciences web services. This limitation can be addressed by annotating services and their interfaces with semantic information, so that interoperability problems can be reasoned about programmatically. The Moby semantic web framework is a popular and mature platform that is used for this purpose. However, the number of services that are available to select from when building a workflow is becoming unmanageable for users. As such, attempts have been made to assist with service selection and composition. These tasks fall under the general label of automated service composition. We present a prototype workflow assembly client that reduces the number of choices that users have to make by (1) restricting the overall set of services presented to them and (2) ranking services so that the the most desirable ones are presented first. We demonstrate via an evaluation of this prototype that a unification of relatively simple techniques can rank desirable services highly while maintaining interactive response times. PMID:18373957

DiBernardo, Michael; Pottinger, Rachel; Wilkinson, Mark

2008-10-01

235

Metabolic bacterial genes and the construction of high-level composite lineages of life  

PubMed Central

Understanding how major organismal lineages originated is fundamental for understanding processes by which life evolved. Major evolutionary transitions, like eukaryogenesis, merging genetic material from distantly related organisms, are rare events, hence difficult ones to explain causally. If most archaeal lineages emerged after massive acquisitions of bacterial genes, a rule however arises: metabolic bacterial genes contributed to all major evolutionary transitions. PMID:25601290

Méheust, Raphaël; Lopez, Philippe; Bapteste, Eric

2015-01-01

236

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

237

Chamber-confined silicon-carbon nanofiber composites for prolonged cycling life of Li-ion batteries.  

PubMed

Silicon is a promising high capacity (4200 mA h g(-1)) anode material for lithium ion batteries but the significant volume change (over 300%) of silicon during lithiation/delithiation remains a challenge in terms of silicon pulverization and solid-electrolyte-interphase (SEI) accumulation in the silicon composite electrode. To alleviate the volumetric change of silicon, we built a flexible and self-supporting carbon-enhanced carbon nanofiber (CNF) structure with vacant chamber to encapsulate Si nanoparticles (vacant Si@CNF@C). This composite was tested directly without any polymer and current collector. The confined vacant chamber allowed the increasing volume of silicon and SEI accumulates to be well retained for a long cycle life. This chamber-confined silicon-carbon nanofiber composite exhibited an improved performance in terms of good cycling performance (620 mA h g(-1)), high coulombic efficiency (99%), and good capacity retention (80%) after 200 cycles. This self-supported silicon-carbon nanofiber structure showed high flexibility and good electrochemical performance for the potential as flexible electrode for lithium-ion batteries. PMID:24882561

Fu, Kun; Lu, Yao; Dirican, Mahmut; Chen, Chen; Yanilmaz, Meltem; Shi, Quan; Bradford, Philip D; Zhang, Xiangwu

2014-07-01

238

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

239

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

Microsoft Academic Search

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

Ling Tong; Xiaohui Yu; Hong Liu

2010-01-01

240

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

241

EFFECT OF THE CASTING SOLUTION COMPOSITION ON PORE SIZE AND PORE SIZE DISTRIBUTION OF RESULTING AROMATIC POLYAMIDE MEMBRANES  

Microsoft Academic Search

The control of average pore size and pore size distribution on the surface of reverse osmosis (RO) membranes of aromatic polyamide (PA) material was studied by properly adjusting the composition of casting solutions which consisted of polymer—solvent, dimethylacetamide (DMA) —nonsolvent (swelling agent), calcium chloride. The average size and the distribution of the network and aggregate. pores were related to the

T. D. NGUYEN; TAKESHI MATSUURA; S. SOURIRAJAN

1987-01-01

242

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

243

Astrobiology: exploring the origins, evolution, and distribution of life in the Universe  

NASA Technical Reports Server (NTRS)

The search for the origins of life and its presence beyond Earth is strengthened by new technology and by evidence that life tolerates extreme conditions and that planets are widespread. Astrobiologists learn how planets develop and maintain habitable conditions. They combine biological and information sciences to decipher the origins of life. They examine how biota, particularly microorganisms, evolve, at scales from the molecular to the biosphere level, including interactions with long-term planetary changes. Astrobiologists learn how to recognize the morphological, chemical, and spectroscopic signatures of life in order to explore both extraterrestrial samples and electromagnetic spectra reflected from extrasolar planets.

Des Marais, D. J.; Walter, M. R.

1999-01-01

244

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

245

Evaluation of hole quality and bit life in graphite epoxy composites using video scanning  

E-print Network

composite materials. such of this effort was directed towards finding optimum machining conditions to produce better quality holes. Another area investigated was that of evaluating the quality of drilled holes with different types of nondestructive... was the drilling portion of Grumman's research. After a review of drilling data from various sources a series of summary charts was presented. For drilling graphite epoxy with a power feed drilling machine the Grumman report [1] recommends a rotary speed...

Lednicky, Thomas Edward

1985-01-01

246

Out-Life Characteristics of IM7/977-3 Composites  

NASA Technical Reports Server (NTRS)

The capability to manufacture large structures leads to weight savings and reduced risk relative to joining smaller components. However, manufacture of increasingly large composite components is pushing the out-time limits of epoxy/ carbon fiber prepreg. IM7/977-3 is an autoclave processable prepreg material, commonly used in aerospace structures. The out-time limit is reported as 30 days by the manufacturer. The purpose of this work was to evaluate the material processability and composite properties of 977-3 resin and IM7/977-3 prepreg that had been aged at room temperature for up to 60 days. The effects of room temperature aging on the thermal and visco-elastic properties of the materials were investigated. Neat resin was evaluated by differential scanning calorimetry to characterize thermal properties and change in activation energy of cure. Neat resin was also evaluated by rheometry to characterize its processability in composite fabrication. IM7/977-3 prepreg was evaluated by dynamic mechanical analysis to characterize the curing behavior. Prepreg tack was also evaluated over 60 days. The overall test results suggested that IM7/977-3 was a robust material that offered quality laminates throughout this aging process when processed by autoclave.

Miller, Sandi G.; Sutter, James K.; Hou, Tan-Hung; Scheiman, Daniel A.; Martin, Richard E.; Maryanski, Michael; Schlea, Michelle; Gardner, John M.; Schiferl, Zack R.

2010-01-01

247

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

248

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

249

Realistic modeling of environmental tracer migration and composite age distributions in a pine beetle impacted watershed  

NASA Astrophysics Data System (ADS)

Descriptions of age in hydrologic systems are often limited to the residence time in the surface water system or the subsurface with little consideration of the interaction between the two, or the different ways geochemical tracers are altered in each domain. Understanding the way tracer concentrations change in each domain is essential to accurate estimation of age, but few models have explicitly modeled the fully coupled system or considered distributions of age. This work presents a numerical laboratory that is specifically designed to investigate composite age distributions (CADs) and their connections to tracer concentrations. The CAD is defined here as the combination of the residence time distributions for surface flows, vadose zone, and groundwater systems, providing an accounting for the total time a discrete fluid parcel has spent within the integrated hydrologic system. CADs are generated by particle tracking through a fully integrated flow model and it is straight forward to realistically simulate the transport of environmental tracers such as 85-Krypton and 39-Argon that can be used for estimating water ages. This framework allows explicit modeling of the different processes in each domain that affect tracer concentrations including the mixing of different source waters, partial equilibrium with the atmosphere through the vadose zone, evaporative enrichment in surface flows, and diffusive fractionation in the subsurface. Transient forcings, such as seasonal or daily variations in precipitation, can also be simulated and the effects of this transience on concentrations and age distributions can easily be investigated. The model domain used to demonstrate these tools is based on a well-defined watershed within Rocky Mountain National Park. The mountain pine beetle has devastated the park's forests and the massive tree-kill has begun to affect the quality and distribution of the water resources. Accurate modeling of the CADs in the park is a crucial step in understanding the long-term environmental impacts of the infestation, and comparisons to measured concentrations are needed to validate those models, making it an ideal test platform. The flow model is a combination of deterministic and geostatistically specified properties that provides a realistic representation of the study site, with age distributions and tracer concentrations subsequently simulated by particle tracking. The simulated concentrations are used to compute inferred mean ages and estimates of the entire age distribution, which are then compared to the known CADs and the domain specific age distributions for several scenarios.

Engdahl, N. B.; Maxwell, R. M.

2013-12-01

250

[Floristic composition and distribution of the Andean subtropical riparian forests of Lules River, Tucuman, Argentina].  

PubMed

We studied the floristic composition and distribution of the riparian forest of two hydrographical systems in a subtropical Andean region. Using uni and multivariate techniques, we tested the hypotheses that a differentiable riparian forest exists, composed by native vegetation typical of the Yungas phytogeographical province, and that the distribution of vegetation varied significantly with geomorphologic characteristics. Parallel transects along the water courses were used to collect presence-absence data of vegetation in eleven sites. Detrended Correspondence Analysis defined a group of common riparian species for the studied area (Solanum riparium, Phenax laevigatus, Tipuana tipu, Cestrum parqui, Carica quercifolia, Acacia macracantha, Celtis iguanaea, Juglans australis, Pisoniella arborescens, Baccharis salicifolia, Cinnamomum porphyrium and Eugenia uniflora) and identified two reference sites. The distribution of the riparian vegetation varied significantly with the geomorphic characteristics along the studied sites. Riparian habitats were composed by native and exotic species. A distinct riparian flora, different in structure and function from adjacent terrestrial vegetation, could not be identified. Riparian species were similar to the adjacent terrestrial strata. These species would not be limited by the proximity to the river. Anthropogenic impacts were important factors regulating the introduction and increase of exotic vegetation. The lack of regulation of some activities in the zone could cause serious problems in the integrity of this ecosystem. PMID:20411737

Sirombra, Martín G; Mesa, Leticia M

2010-03-01

251

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

252

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

253

Aerobic versus resistance training effects on health-related quality of life, body composition, and function of older adults.  

PubMed

This study aimed to investigate the effects of training on health-related quality of life (HRQoL), body composition, and function in older adults. Fifty participants were randomized into aerobic training (AT-70%-80% HRreserve), resistance training (RT-80% 1RM), or controls. They had HRQoL, body composition, and function assessed before and after 8 months. Training groups reduced body fat, increased performance in the stair ascent, 8-ft up-and-go and sit-to-stand five-times tests, and improved their physical component score (PCS; p ? .03). AT increased performance in the 6MWT test, and improved general and mental health (MH) domains when compared to controls (p < .01). Finally, changes in stair ascent were associated with changes in bodily pain, MH, and mental component score (p ? .04), while changes in handgrip strength were associated with changes in physical role and MH (p = .03). AT and RT were effective interventions for decreasing body fat and improving functionality and the PCS in older adults. PMID:24652860

Wanderley, Flávia Accioly Canuto; Oliveira, Nórton Luis; Marques, Elisa; Moreira, Pedro; Oliveira, José; Carvalho, Joana

2015-04-01

254

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

255

Interfacial shear stress distribution in model composites. I - A Kevlar 49 fibre in an epoxy matrix  

SciTech Connect

The technique of Laser Raman Spectroscopy has been applied in the study of aramid fibers, such as Kevlar 49, and aramid/epoxy interfaces. A linear relationship has been found between Raman frequencies and strain upon loading a single Kevlar 49 filament in air. Model composites of single Kevlar 49 fibers embedded in epoxy resins have been fabricated and subjected to various degrees of mechanical deformation. The transfer lengths for reinforcement have been measured at various levels of applied tensile load and the dependence of transfer length upon applied matrix strain has been established. Finally, by balancing the tensile and the shear forces acting along the interface, the interfacial shear stress (ISS) distribution along the embedded fiber was obtained. 52 refs.

Jahankhani, H.; Galiotis, C. (Queen Mary and Westfield College, London (England))

1991-05-01

256

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

257

Where did the Trojan asteroids form? Constraints from composition and size distributions  

NASA Astrophysics Data System (ADS)

We propose to make near-infrared (0.8 - 2.5 ?m) spectral observations of 15 small to medium sized (<100 km) Jovian Trojan asteroids. These objects are part of a substantial population of primitive bodies trapped in Jupiter's stable Lagrange regions. Because they may have become trapped in these orbits at the end of the initial phase of planetary formation and subsequent migration, the physical properties of Trojans provide unique perspectives on chemical and dynamical processes that shaped the Solar System. Indeed, in recognition of their importance, the Trojans are one of only five allowable target destinations for NASA's next New Frontiers mission. Previous observations have identified two spectral classes, suggesting that the Trojans are comprised of two distinct compositional groups, perhaps representing distinct outer Solar System reservoirs for their formation. These new proposed observations will: (a) Enable a search for minor absorptions due to ices, organics, and/or silicates in the smallest Trojans yet observed, near and below the size regime thought to represent the largest collisional fragments from impacts within the Trojan clouds; and (b) Test whether the two spectral groups previously identified have different cumulative size distributions, which would suggest different internal strengths and support the hypothesis of distinct compositions and origins.

Emery, Joshua; Bell, Jim; Trilling, David; Patience, Jennifer; Brown, Mike

2014-08-01

258

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

259

The bacteriological composition of biomass recovered by flushing an operational drinking water distribution system.  

PubMed

This study investigates the influence of pipe characteristics on the bacteriological composition of material mobilised from a drinking water distribution system (DWDS) and the impact of biofilm removal on water quality. Hydrants in a single UK Distribution Management Area (DMA) with both polyethylene and cast iron pipe sections were subjected to incremental increases in flow to mobilise material from the pipe walls. Turbidity was monitored during these operations and water samples were collected for physico-chemical and bacteriological analysis. DNA was extracted from the material mobilised into the bulk water before and during flushing. Bacterial tag-encoded 454 pyrosequencing was then used to characterize the bacterial communities present in this material. Turbidity values were high in the samples from cast iron pipes. Iron, aluminium, manganese and phosphate concentrations were found to correlate to observed turbidity. The bacterial community composition of the material mobilised from the pipes was significantly different between plastic and cast iron pipe sections (p < 0.5). High relative abundances of Alphaproteobacteria (23.3%), Clostridia (10.3%) and Actinobacteria (10.3%) were detected in the material removed from plastic pipes. Sequences related to Alphaproteobacteria (22.8%), Bacilli (16.6%), and Gammaproteobacteria (1.4%) were predominant in the samples obtained from cast iron pipes. The highest species richness and diversity were found in the samples from material mobilised from plastic pipes. Spirochaeta spp., Methylobacterium spp. Clostridium spp. and Desulfobacterium spp., were the most represented genera in the material obtained prior to and during the flushing of the plastic pipes. In cast iron pipes a high relative abundance of bacteria able to utilise different iron and manganese compounds were found such as Lysinibacillus spp., Geobacillus spp. and Magnetobacterium spp. PMID:24565801

Douterelo, I; Husband, S; Boxall, J B

2014-05-01

260

Friction Stir Processing of Al-TiB2 In Situ Composite: Effect on Particle Distribution, Microstructure and Properties  

NASA Astrophysics Data System (ADS)

Aluminum-based in situ composites suffer from the age-old issue of particle segregation along the grain boundaries after casting. In the present study, friction stir processing (FSP) was employed as a secondary process to improve the distribution of in situ formed TiB2 particles in Al-based composite. All the agglomerates of TiB2 were broken, and uniform distribution of particles was achieved after double-pass FSP. Also, FSP removed the casting defects and caused significant grain refinement of the Al matrix. The microstructure was characterized by equiaxed fine grains with average size of 3 µm and narrow grain size distribution. The microstructural refinements and homogenization after FSP not only enhanced the strength but also improved the ductility of the as-cast composite.

Yadav, Devinder; Bauri, Ranjit

2015-03-01

261

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

262

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

263

Distribution of volatile composition in 'marion' ( rubus species hyb) blackberry pedigree.  

PubMed

The distribution of volatile constituents in ancestral genotypes of 'Marion' blackberry's pedigree was investigated over two growing seasons. Each genotype in the pedigree had a specific volatile composition. Red raspberry was dominated by norisoprenoids, lactones, and acids. 'Logan' and 'Olallie' also had a norisoprenoid dominance but at much lower concentrations. The concentration of norisoprenoids in other blackberry genotypes was significantly lower. Terpenes and furanones were predominant in wild 'Himalaya' blackberry, whereas terpenes were the major volatiles in 'Santiam'. 'Marion', a selection from 'Chehalem' and 'Olallie', contained almost all of the volatile compounds in its pedigree at moderate amount. The chiral isomeric ratios of 11 pairs of compounds were also studied. Strong chiral isomeric preference was observed for most of the chiral compounds, and each cultivar had its unique chiral isomeric distribution. An inherent pattern was observed for some volatile compounds in the 'Marion' pedigree. Raspberry and 'Logan' had a very high concentration of beta-ionone, but was reduced by half in 'Olallie' and by another half in 'Marion' as the crossing proceeded. A high content of linalool in 'Olallie' and a low content in 'Chehalem' resulted in a moderate content of linalool in their progeny 'Marion'. However, the concentration of furaneol in 'Marion' was higher than in its parents. A high content of (S)-linalool in 'Olallie' and a racemic content of (S)-,(R)-linalool in 'Chehalem' resulted in a preference for the (S)-form in 'Marion'. PMID:20055446

Du, Xiaofen; Finn, Chad; Qian, Michael C

2010-02-10

264

Monitoring of atmospheric composition with IASI and MOPITT: CO distributions and trends  

NASA Astrophysics Data System (ADS)

Carbon monoxide (CO) is an important trace gas for understanding air quality and atmospheric composition. It is a good tracer of pollution plumes and atmospheric dynamics. In this talk we describe the analysis of global and regional CO distributions as seen by both the MOPITT/Terra and IASI/MetOp missions, from mid-2007 up to now. Long term trends for IASI and MOPITT (version 3, 4 and 5) CO total columns over specific areas are presented, and show excellent agreement. CO distributions over polluted and clean regions are compared. Preliminary results of a study comparing the surface CO level for the two sounders over different cities will be presented, using MOPITT version 5 products that include the NIR and show a better sensitivity near the ground. Finally, this talk will also illustrate how the data processed at ULB-LATMOS are currently assimilated in the MACC project in near-real time in order to generate the CO pollution forecasts over Europe. Surface CO obtained after assimilation show better agreement with ground-based station measurements.

George, M.; Clerbaux, C.; Hadji-Lazaro, J.; Bouarar, I.; Hurtmans, D.; Coheur, P.; Edwards, D. P.; Deeter, M. N.; Worden, H. M.

2011-12-01

265

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

266

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

267

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

268

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

269

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

270

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

271

Distribution and life history of two planktonic copepods, Rhincalanus nasutus and Rhincalanus rostrifrons, in the northwestern Pacific Ocean  

NASA Astrophysics Data System (ADS)

To clarify the life histories of two tropical-subtropical Eucalanidae species, Rhincalanus nasutus and Rhincalanus rostrifrons, we investigated the geographical and vertical distributions of their copepodid populations in the northwestern (NW) Pacific Ocean. Zooplankton samples were collected between 15°N and 49°N in the NW Pacific. Rhincalanus nasutus was widely distributed from 20°N to 49°N, whereas R. rostrifrons was restricted to more southerly latitudes (15-37°N). The occurrence of the two species in the surface layer was associated with seasonal spring ontogenetic vertical migration (OVM). Gonadal analysis indicated that, during spring, both species reproduce in the surface layers of the Kuroshio-Oyashio Transition Area (TA) and the slope water area, which is a region of the continental slope situated north of the Kuroshio axis. Our results suggest that both species might have 1 or 2 year life cycles. In comparison, dormant populations occupying the water below the surface layer mainly comprised adult females (50.2% for R. nasutus and 57.7% for R. rostrifrons), which implied that this is an advantageous strategy for this life state in response to irregular increases of primary production in tropical-subtropical oceans. Furthermore, dormancy in deep waters (500-1000 m) by R. nasutus might indicate a strategy to avoid the relatively high predation risks incurred in shallower waters, due to its larger body size. In contrast, the smaller body size of R. rostrifrons facilitates dormancy in shallower waters (200-500 m depth).

Shimode, Shinji; Takahashi, Kazutaka; Shimizu, Yugo; Nonomura, Takumi; Tsuda, Atsushi

272

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

273

Phytogeographic distribution groups of benthic marine algae in the North Atlantic Ocean. A review of experimental evidence from life history studies  

NASA Astrophysics Data System (ADS)

Experimentally determined lethal temperatures and temperatures limiting growth or reproduction in the life histories of 15 benthic algal species were used to infer possible phytogeographic boundaries in the North Atlantic Ocean. These appeared to correspond closely with phytogeographic boundaries based on distribution data. Many boundaries appeared to be of a composite nature. For instance, the southern boundary of Nemalion helminthoides is interpreted as a “southern reproduction boundary” on the N. Atlantic E. shore and a “southern lethal boundary” on the N. Atlantic W. shore. The northern boundary on both sides of the ocean is a “northern reproduction boundary”. N. helminthoides is a typical representative of the “amphiatlantic temperate distribution group”, to which seven other of the fifteen investigated species belong ( Chondrus crispus, Desmarestia aculeata, D. viridis, Monostroma grevillei, Acrosiphonia “arcta” with a comparable composite southern boundary; Rhodochorton purpureum with a “southern lethal boundary”). Polysiphonia ferulacea and Dictyota dichotoma are treated as representatives of the “amphiatlantic tropical-to-warm-temperate distribution group”, and P. denudata as representative of the “amphiatlantic tropical-to-temperate group”. P. harveyi belongs to the N.E. American temperate group and is bounded by a “northern reproduction boundary” and a “southern reproduction boundary”. This is one of the very few species endemic to N.E. America. This poor endemism is ascribed to the vast adverse sediment shores and their additional acting as barriers to glacial northsouth displacements of the flora; it is not related to the wide annual temperature fluctuations (>20 °C) typical for N.E. America. The temperate algal flora of Japan, however, which is extremely rich in endemic species is subject to equally wide annual temperature fluctuations. Bonnemaisonia hamifera is such a Japanese endemic, which has been accidentally introduced into the North Atlantic Ocean where its life history seems to be disrupted: it is maintained mainly by vegetative propagation of the heteromorphic tetrasporophyte. The species of the “warm temperate Mediterranean-Atlantic group” are probably too stenothermous for life on N.E. American shores; they need annual temperature fluctuations<20 °C. Acrosymphyton purpuriferum seems to belong to this group, but arguments are presented to unite this species with A. caribaeum and to range it under the “amphiatlantic tropical-to-warm-temperate group”. Clathromorphum circumscriptum belongs to the “Arctic distribution group” and has a “southern reproduction boundary” across the ocean along the 3 °C February isotherm. This species is able to survive temperatures of about 20 °C. Five amphiequatorial temperate species discussed in this paper and four in another related paper have similar maximum winter temperatures of 14-17 °C (mean monthly values) allowing reproduction. Their amphiequatorial distribution can be explained by assuming similar low temperatures in the euphotic zone along E. Pacific and E. Atlantic equatorial coasts i.e. in narrow inshore belts of intensified upwelling during the presumably intensified glacial circulation of the ocean gyres.

van den Hoek, C.

1982-06-01

274

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

275

Physical and biological control of protistan community composition, distribution and abundance in the seasonal ice zone of the Southern Ocean between 30 and 80°E  

NASA Astrophysics Data System (ADS)

Protists are critical components of the Antarctic marine ecosystem as they comprise most of the living carbon and are the base of the Antarctic food web. They are also key determinants of vertical carbon flux and mediate draw-down of atmospheric CO 2 by the ocean. The community composition, abundance and distribution of marine protists (phytoplankton and protozoa) was studied during the Baseline Research on Oceanography, Krill and the Environment-West (BROKE-West) survey, in the seasonal ice zone during the 2005-2006 austral summer between 30°E and 80°E. Light and electron microscopy were used to determine the protistan composition and abundance in samples obtained at 30 sites from surface waters and at 26 sites from the depth of the maximum in situ chlorophyll fluorescence (Chl max). Cluster analysis was used to identify 5 groups of sample sites at the surface and 5 at the Chl max that were of similar protist composition and abundance. The physical characteristics, taxonomic composition, indicator taxa, and taxonomic diversity were determined for each group. In the southwest, a bloom of colonial Phaeocystis antarctica dominated the protistan community composition and biomass amongst the receding ice, but this was replaced by the flagellate life stage/s of this haptophyte in waters to the north. In the southeast, a diatom bloom had the highest diversity of protist taxa observed during the survey and centric diatoms dominated the biomass. Outside these blooms, grazing by krill probably reduced the composition and abundance of large diatoms and autotrophic dinoflagellates in coastal to mid-inshore waters. Only in offshore waters did large diatoms and dinoflagellates increase in abundance and diversity, despite low concentrations of iron and silicate at many of these sites. This increase was probably due to reduced top-down control by krill and other large zooplankton. Large diatoms dominated in offshore waters, despite other coincident studies showing that the trophic structure and function of the microbial community was frequently typical of nanoflagellate-dominated systems in high-nutrient low-chlorophyll waters. Nanoflagellate abundances were low during the survey and were either poorly resolved by our study or limited by microheterotrophic grazing. We propose that protistan abundance and composition in the sea-ice zone of the Indian Sector were determined by synoptic-scale oceanographic features, meso-scale changes caused by sea-ice retreat and meso- to nano- scale interactions between grazers and the composition and abundance of their protistan prey.

Davidson, Andrew T.; Scott, Fiona J.; Nash, Geraldine V.; Wright, Simon W.; Raymond, Ben

2010-05-01

276

Defect effects on the physical and electrochemical properties of nanoscale LiFe0.92PO4 and LiFe0.92PO4/C/graphene composites.  

PubMed

Nanoscale LiFe0.92PO4 and LiFe0.92PO4/C/graphene composites including defects as performance-improved cathode materials for lithium-ion batteries were prepared by a carbothermal reduction method. The physical and electrochemical properties of samples were characterized by means of X-ray diffraction, inductively coupled plasma optical emission spectrometry, X-ray photoelectron spectroscopy, Mössbauer spectroscopy, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and electrochemical testing techniques. The results confirmed that defects existed within the nanoscale LiFe0.92PO4 lattice and had significant effects on improving the electrochemical properties of samples. The excellent graphene sheets covered on nanoparticles and formed a three-dimensional conductive network in nanoscale LiFe0.92PO4/C/graphene composites. The composites exhibited a discharge capacity of 90 mA h g(-1) at 10 C and capacity retention ratios of 98% after 100 cycles at various rates, implying outstanding high-rate capability and cycling stability. PMID:23493954

Wang, Yan; Feng, Zhe-sheng; Zhang, Chuan; Yu, Le; Chen, Jin-ju; Hu, Jing; Liu, Xing-zhao

2013-05-01

277

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

Microsoft Academic Search

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

Leslie E. Holland

1986-01-01

278

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

279

Life table demography of the rotifer Lecane Tenuiseta under culture conditions, and various age distributions  

Microsoft Academic Search

The rotifer Lecane tenuiseta found contaminating an unpolluted culture water reservoir, was cultured in a dilute baker's yeast suspension using the same water. Ova, cultured individually in 10 µl wells at 20°C, were observed at half day intervals for hatching, daughter ova and death. Data were subjected to life table demographic analyses. With a stable age population of parthenogenic females,

William D. Hummon; Darlene P. Bevelhymer

1980-01-01

280

Oceanic distribution and life cycle of Calanus species in the Norwegian Sea and adjacent waters  

Microsoft Academic Search

The distribution and demography of Calanus finmarchicus, C. glacialis and C. hyperboreus were studied throughout their growth season on a basin scale in the Norwegian Sea using ordination techniques and generalized additive models. The distribution and demographic data were related to the seasonal development of the phytoplankton bloom and physical characteristics of water masses. The resulting quantified relationships were related

Cecilie Broms; Webjørn Melle; Stein Kaartvedt

2009-01-01

281

Reliability based optimal design of water distribution networks considering life cycle components  

Microsoft Academic Search

Water distribution systems play an important role in supplying water to consumers in a timely and efficient manner. The importance and complexity of such systems lead to extensive research in the area of optimal design of water distribution networks. Traditionally, only system costs are considered in design with few models incorporating environmental impacts. This paper presents a model for designing

Kalyan R. Piratla; Samuel T. Ariaratnam

2012-01-01

282

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...

283

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

PubMed Central

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 from a museum specimen database and literature searches; (ii) a nearly identical survey conducted 15 years earlier; and (iii) a modeled historical community constructed with species distribution models (SDMs). This holistic approach, and especially the application of SDMs, allowed us to discover that the fish community in Barton Creek was more diverse than the historical data and survey methods alone indicated. Sixteen native species with high modeled probability of occurrence within the watershed were not found in the 2008 survey, seven of these were not found in either survey or in any of the historical collection records. Our approach allowed us to more rigorously establish the true baseline for the pre-development fish fauna and then to more accurately assess trends and develop hypotheses regarding factors driving current fish community composition to better inform management decisions and future restoration efforts. Smaller, urbanized freshwater systems, like Barton Creek, typically have a relatively poor historical biodiversity inventory coupled with long histories of alteration, and thus there is a propensity for land managers and researchers to apply inaccurate baseline standards. Our methods provide a way around that limitation by using SDMs derived from larger and richer biodiversity databases of a broader geographic scope. Broadly applied, we propose that this technique has potential to overcome limitations of popular bioassessment metrics (e.g., IBI) to become a versatile and robust management tool for determining status of freshwater biotic communities. PMID:21966438

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

2011-01-01

284

[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

285

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

286

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

287

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

288

Pyrolysis as a way to close a CFRC life cycle: Carbon fibers recovery and their use as feedstock for a new composite production  

NASA Astrophysics Data System (ADS)

Pyrolysis is shown to be an efficient method for recycling carbon fiber composites in the form of both uncured prepregs scraps or as cured end-of-life objects. The pyrolytic process leads to different products in three physical states of matter. The gaseous fraction, called syngas, can be used as energy feedstock in the process itself. The oil fraction can be used as fuel or chemical feedstock. The solid residue contains substantially unharmed carbon fibers that can be isolated and recovered for the production of new composite materials, thus closing the life cycle of the composite in a "cradle to cradle" approach. All the pyrolysis outputs were thoroughly analyzed and characterized in terms of composition for oil and gas fraction and surface characteristics of the fibers. In particular, it is of paramount importance to correlate the aspect and properties of the fibers obtained with different composite feedstock and operational conditions, that can be significantly different, with the reinforcing performance in the newly produced Recycled Carbon Fibers Reinforced Polymers. Present results have been obtained on a pyrolysis pilot plant that offers the possibility of treating up to 70kg of materials, thus leading to a significant amount of products to be tested in the further composites production, focused mainly on chopped carbon fiber reinforcement.

Giorgini, Loris; Benelli, Tiziana; Mazzocchetti, Laura; Leonardi, Chiara; Zattini, Giorgio; Minak, Giangiacomo; Dolcini, Enrico; Tosi, Cristian; Montanari, Ivan

2014-05-01

289

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

290

Alterations in body composition and fat distribution in growth hormone—Deficient prepubertal children during growth hormone therapy  

Microsoft Academic Search

Growth hormone (GH) deficiency in children results in increased body fat, reduced fat-free mass (FFM) including muscle (protein) and bone, and abdominal obesity. Thus, proper GH secretion likely has major developmental influences on later health risks including cardiovascular diseases and osteoporosis. However, the in vivo control of the development of the body composition and fat distribution by GH has not

J. N. Roemmich; M. G. Huerta; S. M. Sundaresan; A. D. Rogol

2001-01-01

291

Use of reactive transport models to quantify changes in baseflow composition due to changes in the seasonal rainfall distribution  

Microsoft Academic Search

Future climate scenarios predict a shift in the seasonal distribution of precipitation throughout large areas of the world. Changes in the timing of recharge events are expected to have an impact on groundwater quality and hence, on the baseflow of streams and rivers. Factors that control the seasonal variability of the chemical composition of the recharge water include seasonal differences

H. Kooi; V. Post

2008-01-01

292

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 ...

293

The temporal and spatial distribution, composition and abundance of Protozoa in Chaohu Lake, China: Relationship with eutrophication  

Microsoft Academic Search

Systematic investigations into the temporal and spatial distribution, composition and abundance of protozoa in two regions with different trophic levels in Chaohu Lake, a large, shallow and highly eutrophic freshwater lake in China, were conducted during 2002–2003. A total of 114 species of protozoa, including phytomastigophorans, zoomastigophorans, amoebae and ciliates, were identified from 120 polyurethane foam unit (PFU) samples exposed

Muqi Xu; Hong Cao; Ping Xie; Daogui Deng; Weisong Feng; Jian Xu

2005-01-01

294

On the relationship between statistical distributions of defect size and fatigue life in 7050-T7451 thick plate and A356-T6 castings  

Microsoft Academic Search

The relationship between the distributions for the size of fatigue-initiating defects and fatigue life of 7050-T7451 thick plate and A356-T6 alloy castings reported previously in the literature were analyzed. Results showed that (i) the size of fatigue-initiating defects in all four datasets follow the Gumbel distribution, (ii) the fatigue life model based on the Paris-Erdo?an law for crack propagation provides

Murat Tiryakio?lu

2009-01-01

295

Evaluation of both composition and strain distributions in InGaN epitaxial film using x-ray diffraction techniques  

NASA Astrophysics Data System (ADS)

The composition and stain distributions in the InGaN epitaxial films are jointly measured by employing various x-ray diffraction (XRD) techniques, including out-of-plane XRD at special planes, in-plane grazing incidence XRD, and reciprocal space mapping (RSM). It is confirmed that the measurement of (204) reflection allows a rapid access to estimate the composition without considering the influence of biaxial strain. The two-dimensional RSM checks composition and degree of strain relaxation jointly, revealing an inhomogeneous strain distribution profile along the growth direction. As the film thickness increases from 100 nm to 450 nm, the strain status of InGaN films gradually transfers from almost fully strained to fully relaxed state and then more In atoms incorporate into the film, while the near-interface region of InGaN films remains pseudomorphic to GaN.

Guo, Xi; Wang, Hui; Jiang, De-Sheng; Wang, Yu-Tian; Zhao, De-Gang; Zhu, Jian-Jun; Liu, Zong-Shun; Zhang, Shu-Ming; Yang, Hui

2010-10-01

296

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

297

Calf foetal and early life nutrition on grazing conditions: metabolic and endocrine profiles and body composition during the growing phase.  

PubMed

The aim of this study was to determine the effect of nutrition during foetal and lactation periods on calf growth and body composition, and their association with changes in metabolic and endocrine profiles during the calf first year of life on purebred (Hereford and Angus) and cross-bred (F1) dam offspring. Forty cross-bred calves and their dams (purebred--PU: Hereford and Angus, and cross-bred--CR: F1) were used in a randomized block design with a factorial arrangement of herbage allowance of native pastures (high: Hi-HA and low: Lo-HA), 4 vs. 2.5 kg dry matter/kg body weight (BW) and dam genotype (PU vs. CR). Calf BW and blood samples were collected monthly from birth to 380±15 days of age, and body composition was estimated by the urea dilution technique at weaning (142±15 days) and 380 days. Calf birthweight did not differ among groups but from birth to 380 days, and BW was reduced (p=0.046) in Lo-PU offspring. Although Lo-CR calves achieved similar BW than Hi-PU and Hi-CR offspring, they showed an increased fat in detriment of lean tissue deposition. At birth, plasma total protein was less (p=0.04), while plasma glucose, insulin or IGF-I tended or were greater (p<0.072) in Hi-HA than Lo-HA calves. Greater (p<0.03) plasma total protein and/or glucose concentrations during the first months of lactation were observed in CR offspring associated with the greater dam milk production. Although glucose concentrations did not differ among calf groups after weaning, plasma insulin was greater (p=0.004) in Hi-PU than other groups at 380 days. Consistent with the reduced BW, Lo-PU offspring presented the lowest (p=0.026) plasma IGF-I from birth to 380 days. Herbage allowance of native grasslands during calf foetal and lactation periods interacted with maternal heterosis to affect, in the short and/or long term, calf BW or body composition, and metabolic and endocrine profiles. PMID:22712599

Gutiérrez, V; Espasandin, A C; Astessiano, A L; Casal, A; López-Mazz, C; Carriquiry, M

2013-08-01

298

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

299

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

300

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

301

The microscopic state of the solar wind: Links between composition, velocity distributions, waves and turbulence  

NASA Technical Reports Server (NTRS)

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. The possible links between composition, ionization state. velocity distribution functions of electrons, protons and heavy ions. kinetic plasma waves and MHD-scale turbulence are elaborated. Emphasis is placed on a connection of interplanetary kinetic-scale phenomena with their generating microscopic processes in the corona. The fast streams seem to consist of mesoscale pressure-balanced plasma filaments and magnetic flux tubes, reminiscent of the supergranular-size structures building the open corona, from which copious Alfven waves emanate. The wind from the magnetically structured and active corona shows developed compressive turbulence and considerable abundance and ionization state variations. Some modelling attempts to explain the observed element fractionation are briefly reviewed. The causes of the nonthermal particle features. such as proton-ion differential streaming, ion beams. temperature anisotropies, and skewed distributions associated with collisionless heat conduction, are ultimately to be searched in the fact, that the corona is never quiescent but fundamentally variable in space and time. Consequently, the radial evolution of the internal state of the wind resembles at all latitudes a complicated relaxation process, in the course of which the free (in comparison with LTE conditions) particle kinetic energy is converted into plasma waves and MHD turbulence on a wide range of scales. This leads to intermittent wave-particle interactions and unsteady anomalous transport, mixed with the weak effects of the rare Coulomb collisions. Spherical expansion and large-scale inhomogeneity forces the wind to attain microscopically a complex internal state of dynamic statistical equilibrium.

Marsch, E.

1995-01-01

302

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

303

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

304

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

305

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

306

Silicon Isotopic Composition of Isua BIF and Other Early Archean Supracrustal Rocks: a Tracer for Early Life?  

NASA Astrophysics Data System (ADS)

High temperature vapor condensations and stardust forming stellar outflows strongly differentiate Si-isotopes (-650\\permil<\\delta29Si<+200\\permil). In contrast, on Earth, the major cause of slight Si isotope fractionation (-1.8\\permil <\\delta29Si <+1.5\\permil) is related to preferential biological uptake of 28Si by diatoms, radiolarian, sponges and plants in building their opaline frustules, spicules and phytoliths. As a consequence, modern waters, clays, soils and sediments are also fractionated: -0.9\\permil<\\delta29Si<+1.7\\permil, while Phanerozoic magmatic and metamorphic processes leave terrestrial crystalline rocks almost unfractionated: -0.4\\permil <\\delta29Si <+0.2\\permil. Spectacular claims for discovery of oldest evidence for terrestrial life in early Archean (ca 3.7-3.8 Ga) metamorphosed rocks from southern West Greenland have been challenged in a series of studies, and there is need for some independent tracer to gain new insights into the quest for primitive life. In order to unravel potentialities of silicon isotopes, we determined the Si-isotope composition of four groups of rocks from the Isua Greenstone Belt: magnetite-quartz "Banded Iron Formations" (BIF); mica-feldspar-quartz-(garnet) schists of potential pelitic origin; a series of tonalitic gneisses, metabasalt pillows, volcanogenic sediments and hydrothermal quartz veins and vesicles. Specimens were powdered using diamond-coated microdrills. Si was purified by TEA molybdate co-precipitation and measured on a Nu Plasma MC-ICP-MS using Mg external doping in dry plasma mode following Cardinal et al's (2003) methodology. Measured 29Si/28Si are expressed with the \\delta29Si notation relative to the NBS28 quartz standard. Overall reproducibility assessed on 5 BIF duplicates is better than 0.08\\permil. Merck Quartz aliquots processed in the same way as the Isua specimens are unfractionated, showing that our chemical procedure does not produce any isotopic artefacts. Metasediments yield an undifferentiated signature: -0.15\\permil <\\delta29Si <+0.00\\permil. Since they may reflect the average composition of pre-3.8Ga Archean crust, this points to a lack of significant "stellar dust" or "impact-related thermal volatilisation" imprints from pre-3.8Ga meteoritic infall on detrital Si-isotope compositions. The undifferentiated signature (-0.06\\permil<\\delta29Si <+0.21\\permil) of magmatic and hydrothermal derived rocks confirms that Archean crystalline rock-forming processes compare with their Phanerozoic counterparts in terms of their inefficacy to fractionate silicon isotopes. BIF's differ by their significant relative 29Si depletion, which is stronger for the well-preserved, finely-banded BIF (-1.28\\permil<\\delta29Si<-1.11\\permil) than for those with irregular or folded banding (-0.71\\permil<\\delta29Si<-0.28\\permil). Moreover, the finely banded BIF presents very homogeneous interlayer \\delta29Si. Considering the seawater-derived origin of Isua BIF (e.g.Bolhar et al, 2004), the 29Si depletion might either directly reflect the ambient early Archean ocean or seawater-derived hydrothermal fluid, or indicate that BIF precipitation was associated with some unknown organic or inorganic fractionation process. Because the observed isotopic differentiation fits in the range of modern biogically-mediated Si-isotope fractionations, the hypothesis of some potential links between BIF precipitation and early biological activity cannot be overlooked.

André, L.; Cardinal, D.; Alleman, L. Y.; Moorbath, S.

2004-12-01

307

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

308

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

PubMed

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. PMID:10943338

Margulis, L; Navarrete, A; Solé, M

1998-03-01

309

Bacterial composition in a metropolitan drinking water distribution system utilizing different source waters.  

PubMed

We investigated the bacterial composition of water samples from two service areas within a drinking water distribution system (DWDS), each associated with a different primary source of water (groundwater, GW; surface water, SW) and different treatment process. Community analysis based on 16S rRNA gene clone libraries indicated that Actinobacteria (Mycobacterium spp.) and ?-Proteobacteria represented nearly 43 and 38% of the total sequences, respectively. Sequences closely related to Legionella, Pseudomonas, and Vibrio spp. were also identified. In spite of the high number of sequences (71%) shared in both areas, multivariable analysis revealed significant differences between the GW and SW areas. While the dominant phylotypes where not significantly contributing in the ordination of samples, the populations associated with the core of phylotypes (1-10% in each sample) significantly contributed to the differences between both service areas. Diversity indices indicate that the microbial community inhabiting the SW area is more diverse and contains more distantly related species coexisting with local assemblages as compared with the GW area. The bacterial community structure of SW and GW service areas were dissimilar, suggesting that their respective source water and/or water quality parameters shaped by the treatment processes may contribute to the differences in community structure observed. PMID:25719474

Gomez-Alvarez, Vicente; Humrighouse, Ben W; Revetta, Randy P; Santo Domingo, Jorge W

2015-03-01

310

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

311

Dietary fatty acid composition alters magnesium metabolism, distribution, and marginal deficiency response in rats.  

PubMed

Based on dietary intake recommendations, magnesium deficiency commonly occurs throughout the world. However, widespread pathological conditions induced by dietary magnesium deficiency have not been identified. This discrepancy may be caused by other dietary factors ameliorating or exacerbating the response to a marginal magnesium deficiency and/or the length of the deficiency. Thus, a study was performed to determine whether the n-6/n-3 fatty acid composition of the diet affects the response to marginal magnesium deprivation, and whether the effect was dependent upon the length of deprivation. Weanling female rats were fed diets containing 250 mg/kg magnesium in a factorial arrangement with dietary variables of supplemental magnesium at 0 or 250 mg/kg (total of 250 or 500 mg/kg) and fat sources of 75 g/kg corn oil or 65 g/kg fish (menhaden) oil plus 10 g/kg linoleic acid. After 8 and 12 weeks on their respective diets, each rat was placed in a metabolic cage for a 16-hour collection of urine. After 13 weeks, the rats were anesthetized with ether for the collection of plasma and organs. Marginal magnesium deficiency was confirmed by decreased urinary excretion and femur, tibia and vertebrae concentrations of magnesium. Dietary oil influenced the effect of marginal magnesium deficiency on magnesium metabolism, distribution and oxidative stress indicators. Fish oil, but not corn oil, significantly decreased urinary magnesium excretion and increased kidney magnesium concentration. Femur magnesium was significantly decreased by marginal magnesium deficiency in rats fed fish oil but not in rats fed corn oil, and liver magnesium concentration was decreased by fish oil. Marginal magnesium deficiency increased plasma extracellular superoxide dismutase and cysteine (component of glutathione) in rats fed corn oil but not in rats fed fish oil. Urinary prostaglandin E? excretion was significantly decreased by marginal magnesium deficiency at 8 weeks, but not at 12 weeks; an increase between weeks 8 and 12 in marginally magnesium-deficient rats fed fish oil caused this change in significance. The findings show that the dietary fatty acid composition affects the response of rats to marginal magnesium deprivation. The findings also indicate that dietary or physiological factors affecting oxidative stress could affect the response to marginal magnesium deficiency, and that a response to a dietary change that takes time to develop, such as an increase in dietary n-3 fatty acids, may result in signs of marginal deficiency being different over time. PMID:20228007

Nielsen, Forrest H

2009-12-01

312

Distributed feedback lasing from a composite poly(phenylene vinylene)-nanoparticle one-dimensional photonic crystal.  

PubMed

Nanoparticle one-dimensional photonic crystals exhibit intense, broadband reflectivity coupled with a unique mesoporosity. The latter property allows for infiltration of the one-dimensional photonic crystal with functional materials, such as emitting polymers, which in turn can lead to the fabrication of composites whereby the emitter's emission can be modulated by the photon density of states of the photonic crystal. We exploit this interaction in order to produce efficient distributed feedback lasing from a composite poly(phenylene vinylene)-infiltrated nanoparticle one-dimensional photonic crystal. PMID:19842702

Puzzo, Daniel P; Scotognella, Francesco; Zavelani-Rossi, Margherita; Sebastian, Maria; Lough, Alan J; Manners, Ian; Lanzani, Guglielmo; Tubino, Riccardo; Ozin, Geoffrey A

2009-12-01

313

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

314

Rate of Return to Education: A Distributional Analysis Using the LifePaths Model  

ERIC Educational Resources Information Center

This paper reports estimates of the distribution of individual private rates of return to undergraduate and community college education by field of study for Canada. It is important to know the dispersion of the private rate of return to post-secondary education, as well as its average level. There are very different implications for…

Boothby, Daniel; Rowe, Geoff

2002-01-01

315

LETTER doi:10.1038/nature12169 Barium distributions in teeth reveal early-life dietary  

E-print Network

through the weaning process. We also document dietary transitions in a Middle Palaeolithic juvenile cessation of breastfeeding at 1.2 years of age. Integration of Ba spatial distributions and histological map chronological ages to be determined at various positions within tooth crowns and roots (Sup- plementary Fig. 1

Gunawardena, Jeremy

316

Effects of composition and compositional distribution on the electronic structure of ZnSe1-xTex ternary quantum dots  

NASA Astrophysics Data System (ADS)

We report results of first-principles density functional theory (DFT) calculations for the electronic structure of ZnSe1-xTex ternary quantum dots (TQDs) and the effects of composition and compositional distribution on the electron density distribution, electronic density of states, and band gap. We analyze the electronic structure of five types of nanocrystal configurations, namely, pristine ZnSe and ZnTe quantum dots, as well as ZnSe/ZnTe core/shell, ZnTe/ZnSe reverse core/shell, and randomly alloyed ZnSe1-xTex TQDs. We find that the band gaps for ZnSe/ZnTe core/shell TQDs are nonlinearly dependent on the number of Te atoms in the shell, whereas presence of Te in the core of alloyed ZnSe1-xTex TQDs modifies the electronic energy levels abruptly and significantly in the limits of x ? 0 and x ? 1. Our results imply that distribution of Te atoms in the TQD in the form of a ZnSe/ZnTe core/shell configuration allows for optimum tunability of the band gap and wave function confinement in TQDs.

Pandey, Sumeet C.; Maroudas, Dimitrios

2011-12-01

317

Surface and subsurface composition of the Life in the Atacama field sites from rover data and orbital image analysis  

Microsoft Academic Search

The Life in the Atacama project examined six different sites in the Atacama Desert (Chile) over 3 years in an attempt to remotely detect the presence of life with a rover. The remote science team, using only orbital and rover data sets, identified areas with a high potential for life as targets for further inspection by the rover. Orbital data

Jennifer L. Piatek; Craig Hardgrove; Jeffrey E. Moersch; Darrell M. Drake; Michael B. Wyatt; Michael Rampey; Orion Carlisle; Kim Warren-Rhodes; James M. Dohm; Andrew N. Hock; Nathalie A. Cabrol; David S. Wettergreen; Edmond A. Grin; Guillermo Chong Diaz; Peter Coppin; Shmuel Weinstein; Charles S. Cockell; Lucia Marinangeli; Gian Gabriele Ori; Trey Smith; Dominic Jonak; Michael Wagner; Kristen Stubbs; Geb Thomas; Erin Pudenz; Justin Glasgow

2007-01-01

318

Composites  

NASA Astrophysics Data System (ADS)

The Composites market is arguably the most challenging and profitable market for phenolic resins aside from electronics. The variety of products and processes encountered creates the challenges, and the demand for high performance in critical operations brings value. Phenolic composite materials are rendered into a wide range of components to supply a diverse and fragmented commercial base that includes customers in aerospace (Space Shuttle), aircraft (interiors and brakes), mass transit (interiors), defense (blast protection), marine, mine ducting, off-shore (ducts and grating) and infrastructure (architectural) to name a few. For example, phenolic resin is a critical adhesive in the manufacture of honeycomb sandwich panels. Various solvent and water based resins are described along with resin characteristics and the role of metal ions for enhanced thermal stability of the resin used to coat the honeycomb. Featured new developments include pultrusion of phenolic grating, success in RTM/VARTM fabricated parts, new ballistic developments for military vehicles and high char yield carbon-carbon composites along with many others. Additionally, global regional market resin volumes and sales are presented and compared with other thermosetting resin systems.

Taylor, John G.

319

Monitoring of Pb Contamination in Loire Estuary: Trends, Distribution and Isotopic composition  

NASA Astrophysics Data System (ADS)

The Loire River is one of the largest river systems in Western Europe and constitutes a major continental input to marine environment in the Bay of Biscay. Its catchment area flows through agricultural, industrial areas and through a more and more urbanized estuary. Even if Loire River is not considered as a highly polluted system, some studies identified a Pb contamination of its estuary due to industrial inputs and combustion of leaded gasoline up to the mid 90's. A retrospective study, based on the analysis (Pb contents and isotopic composition) of Mytilus edulis samples collected by the French mussel watch program (RNO/ROCCH) has highlighted this contamination and its trend between 1985-2005 (Couture et al., 2010). This poster will first complete the work initiated by Couture et al. Pb contents and isotopic signatures in mussel samples collected by RNO/ROCCH over the last 10 years will be presented and discussed. Results will be compared to measurements performed on various environmental samples (sediment, biota…) collected in the frame of the environmental monitoring project RS2E started in 2012 by the "Observatoire des Sciences de l'Univers Nantes-Atlantique" (OSUNA). This new data will contribute to a better characterisation of Pb contents and distribution along the Loire Estuary. Moreover, some key samples will be submitted to HR-ICP-MS for Pb isotopic analysis. Discrimination of anthropic Pb sources requires both precise and accurate isotope ratio determination and also high versatility due to the complex matrix, which is typical for marine and estuarine samples. These measurements will contribute to a more accurate definition and characterisation of main actual anthropic Pb sources (urban, agricultural, industrial or atmospheric deposition). Couture R.- M., Chiffoleau J.-F., Auger D., Claisse D., Gobeil C. and Cossa D. (2010) Seasonal and decadal variation in lead sources to eastern north Atlantic mussels. Environ. Sci. Technol. 44, 1211-1216.

Brach-Papa, Christophe; Chiffoleau, Jean-François; Knoery, Joel; Chouvelon, Tiphaine; Auger, Dominique; Bretaudeau, Jane; Crochet, Sylvette; Rozuel, Emmanuelle; Thomas, Batien; Vasileva, Emilia; Oriani, Anna Maria

2014-05-01

320

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

321

Composition and distribution of internal resistance in three types of microbial fuel cells.  

PubMed

High internal resistance is a key problem limiting the power output of the microbial fuel cell (MFC). Therefore, more knowledge about the internal resistance is essential to enhance the performance of the MFC. However, different methods are used to determine the internal resistance, which makes the comparison difficult. In this study, three different types of MFCs were constructed to study the composition and distribution of internal resistance. The internal resistance (R(i)) is partitioned into anodic resistance (R(a)), cathodic resistance (R(c)), and ohmic resistance (R(Omega)) according to their origin and the design of the MFCs. These three resistances were then evaluated by the "current interrupt" method and the "steady discharging" method based on the proposed equivalent circuits for MFCs. In MFC-A, MFC-B, and MFC-C, the R(i) values were 3.17, 0.35, and 0.076 Omega m(2), the R(Omega) values were 2.65, 0.085, and 0.008 Omega m(2), the R(a) values were 0.055, 0.115, and 0.034 Omega m(2), and the R(c) values were 0.466, 0.15, and 0.033 Omega m(2), respectively. For MFC-B and MFC-C, the remarkable decrease in R(i) compared with the two-chamber MFC was mainly ascribed to the decline in R(Omega) and R(c). In MFC-C, the membrane electrodes' assembly lowered the ohmic resistance and facilitated the mass transport through the anode and cathode electrodes, resulting in the lowest R(i) among the three types. PMID:17899067

Liang, Peng; Huang, Xia; Fan, Ming-Zhi; Cao, Xiao-Xin; Wang, Cheng

2007-12-01

322

Biology, systematics, life cycle, and distribution of Angiostrongylus cantonensis, the cause of rat lungworm disease.  

PubMed

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

Cowie, Robert H

2013-06-01

323

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

324

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

325

A cumulative damage model to predict the fatigue life of composite laminates including the effect of a fibre-matrix interphase  

Microsoft Academic Search

Recent experimental efforts have established the significance of the fibre-matrix interface \\/interphase in the long-term behaviour of polymeric composites. Results indicate that small alterations at the interface level could translate into orders-of-magnitude changes in fatigue life. However, there is no model currently available in the literature to predict these changes. In this paper, a micromechanics model that includes the effects

S. Subramanian; K. L. Reifsnider; W. W. Stinchcomb

1995-01-01

326

A Dynamic and Distributed Scatternet Formation Protocol for Real-life Bluetooth Scatternets  

Microsoft Academic Search

Bluetooth is a universal radio interface for short-range wireless networks. The basic Bluetooth network topology is a single-hop star-shaped piconet. Several such piconets can be interconnected into a scatternet to form a wireless ad hoc network. This paper proposes a dynamic and distributed protocol to the Bluetooth scatternet formation problem. The protocol was developed strictly within the constraints imposed by

Deepak Jayanna; Gergely V. Záruba

2005-01-01

327

Distribution of perch ( Perca fluviatilis L.) during their first year of life in Lake Constance  

Microsoft Academic Search

The distribution and behaviour of larval and juvenile perch (Perca fluviatilis L.) were studied for two years in large, deep Lake Constance. After hatching larvae were transported by water currents to\\u000a the open water. The majority of larvae remained in the pelagic zone for about one month. In both years, their return to the\\u000a littoral zone coincided with the decline

Ning Wang; Reiner Eckmann

1994-01-01

328

Anchovy shelf life as affected by different chilling methods during distribution.  

PubMed

Anchovies are a very labile fish and deteriorate fast under chilling conditions. In the South of Spain, fishing boats land their catches in wooden boxes with ice (12 to 14 kg). For some years now, fish processors have prepared this species for market distribution by placing about 7 kg fish in expanded polystyrene (EPS) boxes containing water and ice. Then, in the distribution market, boxes are dewatered and re-iced. Transportation of the fish in EPS boxes containing water and ice was recently forbidden on the grounds that boxes for transportation of fish in ice must have holes to let melted ice drain away. In this paper, the effect of preserving the anchovy in water and ice from landing to the distribution market was studied and compared with the more traditional methods of storing the fish in ice in either wooden or EPS boxes. Physical, chemical, microbiological, and sensory analyses were carried out over three different storage trials to account for the effect of seasonality. Little differences were found among lots, but some of the parameters showed that fish transported in water and ice did present less spoilage than fish stored in ice, especially when compared to the wooden boxes. According to these results, chilling of this fish in water and ice can be used as an alternative preserving method during transport. PMID:11848567

Careche, Mercedes; García, Raul; Borderías, Javier

2002-02-01

329

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

330

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

331

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

332

Effect of melt-solid interface shape on lateral compositional distribution of unidirectionally solidified 2-6 semiconducting alloys  

NASA Technical Reports Server (NTRS)

A computer code developed previously has been used to simulate lateral compositional distributions for several 2-6 semiconducting systems. The code is based on analytical results obtained previously. The system under study is an azimuthal symmetric cylindrical system with a curved melt-solid interface shape during an unidirectional solidification process. It is assumed that the system is under a steady state diffusion limited growth condition.

Wang, Jai-Ching

1996-01-01

333

Vibration amplitude distribution measurements on piezoelectric PZT\\/glass composite transducers for ultrasonic bio-cell filters  

Microsoft Academic Search

The typical out-of-plane vibration amplitude distributions associated with the various piezoelectrically excitable resonance frequencies of PZT\\/glass composite resonators have been measured systematically by use of a specially developed scanning LDV vibration amplitude measurement system. The corresponding vibration modes have been identified and characterized, the influence of the lateral boundary conditions is demonstrated. The presented results are of importance for state

E. Benes; A. Frank; H. Bohm; M. Groschl; F. Trampler; W. Burger; H. Nowotny

2000-01-01

334

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.

335

Groundwater age, life expectancy and transit time distributions in advective dispersive systems; 2. Reservoir theory for sub-drainage basins  

NASA Astrophysics Data System (ADS)

Groundwater age and life expectancy probability density functions (pdf) have been defined, and solved in a general three-dimensional context by means of forward and backward advection-dispersion equations [Cornaton F, Perrochet P. Groundwater age, life expectancy and transit time distributions in advective-dispersive systems; 1. Generalized reservoir theory. Adv Water Res (xxxx)]. The discharge and recharge zones transit time pdfs were then derived by applying the reservoir theory (RT) to the global system, thus considering as ensemble the union of all inlet boundaries on one hand, and the union of all outlet boundaries on the other hand. The main advantages in using the RT to calculate the transit time pdf is that the outlet boundary geometry does not represent a computational limiting factor (e.g. outlets of small sizes), since the methodology is based on the integration over the entire domain of each age, or life expectancy, occurrence. In the present paper, we extend the applicability of the RT to sub-drainage basins of groundwater reservoirs by treating the reservoir flow systems as compartments which transfer the water fluxes to a particular discharge zone, and inside which mixing and dispersion processes can take place. Drainage basins are defined by the field of probability of exit at outlet. In this way, we make the RT applicable to each sub-drainage system of an aquifer of arbitrary complexity and configuration. The case of the well-head protection problem is taken as illustrative example, and sensitivity analysis of the effect of pore velocity variations on the simulated ages is carried out.

Cornaton, F.; Perrochet, P.

2006-09-01

336

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

337

Microbial Biomass Distribution and Compositional Changes Associated with a Warmer Climate in Boreal Forest Soils  

NASA Astrophysics Data System (ADS)

Predicting the physiological and structural changes of the microbial community in warming soils is essential for a functional understanding of climate feedback mechanisms. Laboratory and field experiments have often found that warming increases soil organic carbon (SOC) mineralization and decreases microbial biomass, but remain more inconclusive regarding microbial community structure. These experiments, however, have been limited to responses on a time scale of months to years, while soil properties change over decades to centuries. Studies along climate gradients may prove helpful in elucidating how climate history affects soil properties, including microbial community structure. We present the phospholipid fatty acid (PLFA) based community characterization of the organic (L, F, H) and mineral (B; top 10cm) horizons of podzols from two mesic boreal forest sites similar in most aspects (e.g. stand type, class and age) but differing in mean annual temperature (MAT) by almost 6°C. This temperature difference is similar to the warming predicted for this region by 2100. Results are compared to respiration rates in laboratory incubations. We observed consistent PLFA derived biomass per unit SOC throughout the profile, independent of depth or site. The organic horizons contained similar amounts of SOC and PLFA as the top 10 cm of the mineral horizon (2.5-3.4 kg C m-2; 10.3-12.6 mmol PLFA m-2). Within the organic horizon, the greatest proportion of SOC and PLFA were found in the F horizon. The overall distribution of PLFA among the soil horizons was largely unaffected by climate regime, except that biomass was shifted from F to L horizons at the warmer site (from 12% to 29% of total organic horizon PLFA located in L) indicating that biomass was located closer to the surface in warmer sites. A similar shift was found in respiration (26 vs. 42% of organic horizon CO2 from L). As expected, community structure changed with depth. The abundance of fungal and protozoan PLFA decreased and that of Gram+ and Gram- bacteria increased in deeper soil horizons. Within each horizon, community composition was well constrained and did not vary with climate except for higher contributions of long chain (C20+) saturated fatty acids at the colder site. Interestingly, the ratio cy17:0/16:1?7, a physiological indicator of elevated stress or dormancy for the bacterial communities, was elevated within the warmer sites and mineral horizons. This is congruent with SOC normalized respiration rates that were least 5x lower in B relative to the LFH horizons and 50% lower within F and H horizons from the warmer relative colder site. In combination these results suggest that the microbial community in deeper soil horizons and from the warmer climate regime contain a microbial community equally abundant relative to the soil C pool sizes, but not as prolific in CO2 production. Overall, our results suggest that relatively warm climatic regimes in the boreal zone can promote shallower peaks of soil microbial biomass and respiration and shifts in physiology compared to cooler systems, but no discernible differences in community composition.

Kohl, L.; Jérôme, J.; Billings, S. A.; Edwards, K.; Morrill, P. L.; Ziegler, S. E.

2013-12-01

338

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

PubMed Central

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; ?etkovi?, Helena; Žaja, Roko; Ahel, Ivan

2014-01-01

339

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; ?etkovi?, Helena; Žaja, Roko; Ahel, Ivan

2014-11-01

340

Development of Atmospheric Neutral Analyzer for Neutral Mass Composition and Velocity Distribution Measurements in the Upper Atmosphere  

NASA Astrophysics Data System (ADS)

In order to understand the temporal and spatial variability of the ionosphere-thermosphere system, simultaneous measurements of the composition and density of the neutral atmosphere and the velocity distribution of individual species are essential. However, most conventional types of instruments for neutral atmosphere lack the simultaneous capability of measuring neutral atmospheric velocity and resolving neutral mass. We are designing the Atmospheric Neutral Analyzer (ANA) instrument to measure neutral composition and velocity distribution simultaneously in the thermosphere. It is designed to measure the detailed, mass-resolved 2-dimensional velocity distribution of neutral species, and to derive the corresponding density, mass composition, bulk velocity and temperature from the measured distribution. The ANA is comprised of 4 sections; Entrance Aperture (EA), Ion Accelerator (IA), Radio-Frequency Ion Mass Analyzer (MA) and Imaging Particle Detector (PD). The EA consists of a planar aperture slit and deflection electrode, and functions as an incident-particle selector and collimator. A small fraction of the neutral particles is ionized by electron beam. The IA acts as a particle energy selector by accelerating the ionized neutral particles. The MA acts as an ion velocity selector. The radio-frequency voltage is applied to grids and selectively accelerates ions of matching speed. As a result, ions with a particular mass-per-charge are selected. The PD, which is comprised of a retarding grid, micro-channel plate and charge coupled device, detects the mass-selected ions, and a 2-dimensional image of velocity distribution is obtained. We present the detailed design of the ANA in this paper.

Shimoyama, M.; Hayashi, A.; Ishiguro, K.; Hirahara, M.; Yau, A. W.

2012-12-01

341

Fatty acid composition and distribution in the blubber of bottlenose dolphins (Tursiops truncatus)  

E-print Network

Angelica and Greg for their patience and assistance. My life as a graduate student was so much easier thanks to many administrative personnel. Janice Crenshaw, Stacie Arms, Tracie Albritton, and Dr. Tammy Holliday all went above and beyond their duties...

Samuel, Asha Melina

2000-01-01

342

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

343

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

344

Formation, composition and particle size distribution of fly-ashes from biomass combustion plants  

SciTech Connect

Due to the fact that fly-ash particles and aerosols formed during biomass combustion and gasification processes are contaminated with environmentally harmful heavy metals like zinc, cadmium and lead, efficient dust removal from the flue gas is of great importance. In order to characterize biomass fly-ashes and to describe and investigate influencing factors on fly-ash and dust formation, comprehensive particle size measurements were performed with low pressure Berner-type cascade impactors under consideration of different combustion technologies and various types of biomass fuels (bark, wood chips and straw). The results showed that biomass fly-ash can be divided into two major fractions differing in particle size and composition. The first fraction consists of coarse fly-ash particles with an average particle size larger than 5{micro}m results from particles entrained from the fuel bed and is formed mainly by non-volatile minerals (Si, Ca, Mg). The second fraction consists of aerosols (particles smaller than 1{micro}m) which are formed when the flue gas is cooled (in the heat exchanger section) by condensation of volatile ash forming compounds. Chemical analyses of aerosol particles collected by low-pressure impactors revealed that these particles mainly consist of chlorides and sulfates of alkali compounds. These results are in accordance with the outputs of chemical equilibrium calculations performed for the test run conditions. Concerning heavy metal concentrations, the aerosols formed in grate furnaces contain considerable amounts of the environmentally relevant and volatile heavy metals Cd, Zn and Pb due to condensation of metal vapors with decreasing flue gas temperature. The aerosols formed in CFB combustion plants do not contain significant amounts of heavy metals which means that in these systems condensation of gaseous metal compounds does not play a major role. Chemical surface reactions between coarse fly-ash particles and metal vapors seem to be dominant. The particle size distribution of aerosols formed in grate combustion systems is unimodal and has a distinct peak in the range < 1{micro}m without major variations between different biomass fuels. For bark, wood chips and sawdust the major amount of aerosols appears in the range of approximately 0.1{micro}m (Stokes diameter). The dominating particle size of aerosols formed during straw combustion is about 0.5{micro}m. Concerning the combustion of wood and bark, no significant influence of the fuel particle size, the combustion temperature and the boiler load on the size distribution of aerosols was detected for wood and bark in grate furnaces. However, the total amount of aerosols formed by different biomass fuels differs considerably and can be explained by the varying amounts of volatile alkali metals (mainly K and Na), sulfur and chloride in the fuels. That is, the combustion of straw displays total aerosol amounts of up to 900 mg/Nm{sup 3} (related to dry flue gas and 13 Vol.% O{sub 2}) which is about 10 times higher than the emissions of bark- and hardwood-fired grate combustion units. A second influencing parameter revealed is the temperature of combustion. Raising combustion temperatures increase the total amount of aerosols formed.

Brunner, T.; Dahl, J.; Obernberger, I. [Technical Univ. of Graz (Austria). Inst. of Chemical Engineering

1998-12-31

345

Relations of low contrast visual acuity, quality of life and multiple sclerosis functional composite: a cross-sectional analysis  

PubMed Central

Background Although common and often disabling in multiple sclerosis (MS), visual dysfunction is currently not adequately accounted for in both clinical routine and MS trials. Sloan low contrast letter acuity (SLCLA) is a standardised chart-based measure of visual function particular at low contrast and has been suggested as additional visual component to the Multiple Sclerosis Functional Composite (MSFC). Here, we evaluate the relations between SLCLA, retinal integrity, MSFC, and quality of life (QoL) in MS patients. Methods Cross-sectional analysis of retinal nerve fibre layer (RNFL) thickness, MSFC, SLCLA (2.5% and 1.25% contrast levels), visual evoked potentials, and QoL (Short Form (SF) 36, National Eye Institute Visual Functioning Questionnaire (NEIVFQ)) using baseline data of 92 MS patients from an ongoing prospective longitudinal trial. Relations between RNFL thickness or P100 latency and SLCLA were analysed using generalised estimating equations (GEE) accounting for intra-individual inter-eye dependencies and corrected for age, gender, and history of optic neuritis. Pearson’s correlations were used to assess relations between SLCLA, MSFC, and QoL. Results SLCLA reflected RNFL thickness (p?=?0.021) and P100 latency (p?=?0.004) and predicted vision-related QoL, reflected by the NEIVFQ39 subscores “general vision” and “near activities” (p?

2014-01-01

346

Decapod crustacean larval communities in the Balearic Sea (western Mediterranean): Seasonal composition, horizontal and vertical distribution patterns  

NASA Astrophysics Data System (ADS)

Decapod crustaceans are the main target species of deep water bottom trawl fisheries in the Balearic Sea but little is known about their larval stages. This work focuses on the species composition of the decapod larval community, describing the main spatio-temporal assemblages and assessing their vertical distribution. Mesozooplankton sampling was carried out using depth-stratified sampling devices at two stations located over the shelf break and the mid slope, in the north-western and southern Mallorca in late autumn 2009 and summer 2010. Differences among decapod larvae communities, in terms of composition, adult's habitat such as pelagic or benthic, and distribution patterns were observed between seasons, areas and station. Results showed that for both seasons most species and developmental stages aggregated within the upper water column (above 75 m depth) and showed higher biodiversity in summer compared to late autumn. Most abundant species were pelagic prawns (e.g., Sergestidae) occurring in both seasons and areas. The larval assemblages' distributions were different between seasonal hydrographic scenarios and during situations of stratified and non-stratified water column. The vertical distribution patterns of different larval developmental stages in respect to the adult's habitat were analyzed in relation to environmental variables. Fluorescence had the highest explanatory power. Four clearly different vertical patterns were identified: two corresponding to late autumn, which were common for all the main larval groups and other two in summer, one corresponding to larvae of coastal benthic and the second to pelagic species larvae.

Torres, Asvin P.; Dos Santos, Antonina; Balbín, Rosa; Alemany, Francisco; Massutí, Enric; Reglero, Patricia

2014-10-01

347

Response of grooved composites to transversely distributed and localized spherical contact loadings  

E-print Network

The response of a grooved composite specimen to two contact loading situations is studied; load applied via a transversely oriented cylindrical indenter and via a localized spherical ball-ended indenter. The philosophy of ...

Jeffrey, Holly K

2011-01-01

348

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

349

Quasi-static strength and fatigue life of hybrid (bonded\\/bolted) composite single-lap joints  

Microsoft Academic Search

The strength and fatigue life of hybrid (bonded\\/bolted) joints with carbon-fibre reinforced plastic adherends have been investigated. The effect of adhesive material properties and laminate stacking sequence on the joint structural behaviour and failure modes were determined experimentally. Hybrid joints were shown to have greater strength, stiffness and fatigue life in comparison to adhesive bonded joints. However, the benefits were

Gordon Kelly

2006-01-01

350

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.

351

[Distribution and abundance of Caiman crocodilus in the Caño Negro National Wild Life Refuge, Costa Rica].  

PubMed

The distribution and abundance of a population of Caiman crocodilus fuscus were estimated by monthly counting of eye-shines at night, from February 1999 to March 2000 in six transects of Río Frío in the Caño Negro National Refuge (RNVSCN), Northern Costa Rica. March was the month with the greatest abundance of caimans observed. The visible fraction of the population (PV2 index) fluctuated between 42.59% to 54.71% during the wet season and 35.49% to 53.93% in the dry season. The transects of river with greater abundance of caimans were Terrón-Sabogal and Sabogal-Playuela. Significant differences were determined in the abundance of caimans between transects, except the transects Entrada San Sebastían-Las Cubas and Las Cubas-Entrada Caño Los Patos and Entrada Caño Los Patos-Terrón and Boca Sabogal-Playuela. The population of estimated brown caiman in this study was 2283.48 +/- 313.5. The statistical analysis by seasons did not show significant differences in the number of caimans observed. Estimated mean number of caimans per km of river was 74.36/km for 30.7 km of habitat. The results of this study indicated that the fluctuation in population density during the seasons is attributable to local movements. PMID:15162749

Cabrera Peña, Jorge; Protti Quesada, Maurizio; Urriola Hernández, Mario; Cubero Murillo, Rolando

2003-06-01

352

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

353

Deep-sea surface-dwelling enteropneusts from the Mid-Atlantic Ridge: Their ecology, distribution and mode of life  

NASA Astrophysics Data System (ADS)

The ecology, distribution and mode of life of three species of surface-dwelling enteropneusts is described, based on ROV observations and samples on the flanks of the Northern Mid-Atlantic Ridge (MAR) at comparative stations north and south of the Sub-Polar Front. Tergivelum cinnabarinum was most abundant in the north (mean=4.56 ind. 1000 m-2±3.50 s.d.) and occurred at low densities in the south (mean=1.19±1.68 s.d.). Yoda purpurata was dominant in the south (mean=17.00 ind. 1000 m-2±12.32 s.d.) but only one individual was found in the north. The within-station distribution of all enteropneust species encountered was generally random. T. cinnabarinum was larger (mean total length 142 mm) than Y. purpurata (mean total length 70 mm). Size distributions suggested smaller individuals of both species on the western side of the MAR. Size and density of enteropneusts were generally higher in areas with higher carbon flux to the seafloor. A single individual of Allapasus isidis was observed drifting and settling to the seafloor at the SW site. Traces on the seafloor made by T. cinnabarinum covered a much higher percentage of the total seabed area surveyed (mean=0.323%±0.155 s.d.) than those of Y. purpurata (mean=0.034%±0.037 s.d.). Stable isotope values for T. cinnabarinum suggested that it was a typical surficial deposit feeder. Enteropneusts appear to be abundant and an important bioturbator on the sedimented seafloor of the MAR at around 2500 m depth.

Jones, Daniel O. B.; Alt, Claudia H. S.; Priede, Imants G.; Reid, William D. K.; Wigham, Benjamin D.; Billett, David S. M.; Gebruk, Andrey V.; Rogacheva, Antonina; Gooday, Andrew J.

2013-12-01

354

Composition, spatial distribution, and diversity of the bacterial communities in the rumen of cows fed different forages.  

PubMed

The species composition, distribution, and biodiversity of the bacterial communities in the rumen of cows fed alfalfa or triticale were investigated using 16S rRNA gene clone library analyses. The rumen bacterial community was fractionated and analyzed as three separate fractions: populations in the planktonic, loosely attached to rumen digesta particles, and tightly attached to rumen digesta particles. Six hundred and thirteen operational taxonomic units (OTUs) belonging to 32 genera, 19 families, and nine phyla of the domain Bacteria were identified from 1014 sequenced clones. Four hundred and fifty one of the 613 OTUs were identified as new species. These bacterial sequences were distributed differently among the three fractions in the rumen digesta of cows fed alfalfa or triticale. Chao 1 estimation revealed that, in both communities, the populations tightly attached to particulates were more diverse than the planktonic and those loosely attached to particulates. S-Libshuff detected significant differences in the composition between any two fractions in the rumen of cows with the same diet and between the communities fed alfalfa and triticale diets. The species richness estimated for the communities fed alfalfa and triticale is 1027 and 662, respectively. The diversity of the rumen bacterial community examined in this study is greater than previous studies have demonstrated and the differences in the community composition between two high-fiber diets have implications for sample selection for downstream metagenomics applications. PMID:21044097

Kong, Yunhong; Teather, Ronald; Forster, Robert

2010-12-01

355

Effect of re-melting on particle distribution and interface formation in SiC reinforced 2124Al matrix composite  

SciTech Connect

The interface between metal matrix and ceramic reinforcement particles plays an important role in improving properties of the metal matrix composites. Hence, it is important to find out the interface structure of composite after re-melting. In the present investigation, the 2124Al matrix with 10 wt.% SiC particle reinforced composite was re-melted at 800 °C and 900 °C for 10 min followed by pouring into a permanent mould. The microstructures reveal that the SiC particles are distributed throughout the Al-matrix. The volume fraction of SiC particles varies from top to bottom of the composite plate and the difference increases with the decrease of re-melting temperature. The interfacial structure of re-melted 2124Al–10 wt.%SiC composite was investigated using scanning electron microscopy, an electron probe micro-analyzer, a scanning transmission electron detector fitted with scanning electron microscopy and an X-ray energy dispersive spectrometer. It is found that a thick layer of reaction product is formed at the interface of composite after re-melting. The experimental results show that the reaction products at the interface are associated with high concentration of Cu, Mg, Si and C. At re-melting temperature, liquid Al reacts with SiC to form Al{sub 4}C{sub 3} and Al–Si eutectic phase or elemental Si at the interface. High concentration of Si at the interface indicates that SiC is dissociated during re-melting. The X-ray energy dispersive spectrometer analyses confirm that Mg- and Cu-enrich phases are formed at the interface region. The Mg is segregated at the interface region and formed MgAl{sub 2}O{sub 4} in the presence of oxygen. The several elements identified at the interface region indicate that different types of interfaces are formed in between Al matrix and SiC particles. The Al–Si eutectic phase is formed around SiC particles during re-melting which restricts the SiC dissolution. - Highlights: • Re-melted composite shows homogeneous particle distribution • Thick reaction products are observed at the interface • Carbide is identified at interface due to SiC dissolution at high temperature • Reaction products are also Si enrich phase • Mg and Cu segregated and formed MgAl{sub 2}O{sub 4}, CuMgAl{sub 2} phase at grain boundary.

Mandal, Durbadal, E-mail: durbadal73@yahoo.co.in [MEF Division, CSIR-National Metallurgical Laboratory, Jamshedpur 831007 (India); Viswanathan, Srinath [Dept of Metallurgical and Materials Engineering, University of Alabama, Tuscaloosa, AL (United States)

2013-12-15

356

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

357

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

358

Distribution and stable isotopic composition of amino acids from fungal peptaibiotics: assessing the potential for meteoritic contamination.  

PubMed

The presence of nonprotein ?-dialkyl-amino acids such as ?-aminoisobutyric acid (?-AIB) and isovaline (Iva), which are considered to be relatively rare in the terrestrial biosphere, has long been used as an indication of the indigeneity of meteoritic amino acids. However, recent work showing the presence of ?-AIB and Iva in peptides produced by a widespread group of filamentous fungi indicates the possibility of a terrestrial biotic source for the ?-AIB observed in some meteorites. We measured the amino acid distribution and stable carbon and nitrogen isotopic composition of four ?-AIB-containing fungal peptides and compared this data to similar meteoritic measurements. We show that the relatively simple distribution of the C(4) and C(5) amino acids in fungal peptides is distinct from the complex distribution observed in many carbonaceous chondrites. We also identify potentially diagnostic relationships between the stable isotopic compositions of pairs of amino acids from the fungal peptides that may aid in ruling out fungal contamination as a source of meteoritic amino acids. PMID:21417942

Elsila, Jamie E; Callahan, Michael P; Glavin, Daniel P; Dworkin, Jason P; Brückner, Hans

2011-03-01

359

Abundance, composition, and distribution of crustacean zooplankton in relation to hypolimnetic oxygen depletion in west-central Lake Erie  

USGS Publications Warehouse

Samples of crustacean zooplankton were collected monthly in west-central Lake Erie in April and June to October 1968, and in July and August 1970, before and during periods of hypolimnetic dissolved oxygen (DO) depletion. The water column at offshore stations was thermally stratified from June through September 1968, and the hypolimnion contained no DO in mid-August of 1968 or 1970. Composition, abundance, and vertical distribution of crustacean zooplankton changed coincidentally with oxygen depletion. From July to early August, zooplankton abundance dropped 79% in 1968 and 50% in 1970. The declines were attributed largely to a sharp decrease in abundance of planktonic Cyclops bicuspidatus thomasi. Zooplankton composition shifted from mainly cyclopoid copepods in July to mainly cladocerans and copepod nauplii in middle to late August. We believe that mortality of adults and dormancy of copepodites in response to anoxia was the probable reason for the late summer decline in planktonic C. b. thomasi.

Heberger, Roy F.; Reynolds, James B.

1977-01-01

360

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

361

I Am Crrarn Soc, 1 5 [2] 316-2r (1992) Distribution of Matrix Cracks in a Uniaxial Ceramic Composite  

E-print Network

obtained for a unidirectional ceramic-matrix composite (Sic fibers in a calcium aluminosilicate matrixI Am Crrarn Soc, 1 5 [2] 316-2r (1992) journal Distribution of Matrix Cracks in a Uniaxial Ceramic cracking and debonding in uniaxial composites loaded in tension predict that the matrix stress varies only

Barber, James R.

1992-01-01

362

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

363

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

364

Investigation of the Composition and Electromagnetic Properties of Lithium Ferrite LiFe5O8 Ceramics Synthesized from Ultradisperse Iron Oxide  

NASA Astrophysics Data System (ADS)

Structural, magnetic, and electric characteristics of LiFe5O8 synthesized from ultradisperse iron oxide powder are investigated. The basic Fe2O3 reagent is prepared by oxidation of iron nanopowder with particle sizes of 100 nm synthesized by the electroexplosive method. It is demonstrated that LiFe5O8 is characterized by fine-grained ceramic structure with average grain size of 1.4 ?m, high values of the Curie temperature (~630°C), specific electrical resistance (107 ??cm), and saturation magnetization (>3300 G). Thus, lithium ferrite so obtained without additives has the parameters suitable for its application as a microwave ferrite material. It is also demonstrated that addition of bismuth ferrite to the lithium ferrite composition during its sintering yields lower values of the specific electrical resistance and relatively high values of the density and saturation magnetization.

Surzhikov, A. P.; Lysenko, E. N.; Malyshev, A. V.; Nikolaev, E. V.; Zhuravkov, S. P.; Vlasov, V. A.

2015-02-01

365

[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

366

Composition and daytime vertical distribution of the ichthyoplankton assemblage in the Central Cantabrian Sea shelf, during summer: An Eulerian study  

NASA Astrophysics Data System (ADS)

During summer, wind driven coastal upwelling dominates in the Central Cantabrian Sea (southern Bay of Biscay). Nevertheless, atmospheric forcing is highly variable and wind pulses may cause noticeable and fast hydrographic responses in the shelf region. In this paper, the composition and vertical distribution of the summer ichthyoplankton assemblage during the daytime at a fixed station, located on the Central Cantabrian Sea shelf, are documented. Also, the impact of a short-time scale hydrographic event on the abundance and structure of the larval fish assemblage is examined. Significant small-scale temporal hydrographic variability was observed. Currents showed changes in speed and direction and significant changes in thermocline depth were also observed. A total of 34 taxa of fish larvae were identified. Engraulis encrasicolus eggs and larvae of the shelf-dwelling species Trachurus trachurus, Capros aper and E. encrasicolus dominated the ichthyoplankton assemblage. The distribution of E. encrasicolus eggs and fish larvae was vertically structured. E. encrasicolus egg concentration increased exponentially towards the surface. Fish larvae showed a subsurface peak of concentration and their vertical distribution was not conditioned by thermocline depths. The short term hydrographic event did not affect the vertical distribution of fish larvae but it accounted for significant temporal changes in larval fish assemblage structure and abundance. Results suggest that temperature and light intensity are important factors in the vertical distribution of fish larvae. They also indicate that the temporal monitoring of the larval fish assemblage in this region requires multiple sampling sites.

Rodriguez, J. M.; Gonzalez-Pola, C.; Lopez-Urrutia, A.; Nogueira, E.

2011-09-01

367

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

368

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

369

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

370

Dynamic instability characteristics of laminated composite doubly curved panels subjected to partially distributed follower edge loading  

Microsoft Academic Search

This paper deals with the study of vibration and dynamic instability characteristics of laminated composite doubly curved panels, subjected to non-uniform follower load, using finite element approach. First order shear deformation theory is used to model the doubly curved panels, considering the effects of shear deformation and rotary inertia. The formulation is based on the extension of dynamic, shear deformable

L. Ravi Kumar; P. K. Datta; D. L. Prabhakara

2005-01-01

371

Measurement of Dijet Angular Distributions and Search for Quark Compositeness in pp Collisions at s=7TeV  

NASA Astrophysics Data System (ADS)

Dijet angular distributions are measured over a wide range of dijet invariant masses in pp collisions at s=7TeV, at the CERN LHC. The event sample, recorded with the CMS detector, corresponds to an integrated luminosity of 36pb-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 ?+=5.6TeV (?-=6.7TeV) for destructive (constructive) interference is obtained at the 95% confidence level.

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., Jr.; 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.

2011-05-01

372

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

373

Martian Surface Composition From Multiple Datasets, Part II: Chemical Analysis of Global Mineral Distributions from MGS-TES  

NASA Astrophysics Data System (ADS)

Koeppen and Hamilton [2008, JGR-Planets] produced global mineral maps of Mars from Thermal Emission Spectrometer (TES) data using a library of mineral and amorphous phase spectra and a linear least squares fitting algorithm. Here we will use known or estimated bulk chemistries of the phases in the Koeppen and Hamilton [2008] spectral library, along with each phase's modeled abundance in the TES data from that work, to calculate effective bulk chemistry for Martian dark regions at a spatial resolution of ~3x6 km. By doing this, we are able to analyze global bulk chemical variation as well as enable direct comparisons between TES data and chemical/elemental abundance maps (e.g., wt.% SiO2) produced using data collected by the Gamma Ray Spectrometer. A second chemical analysis also makes use of the Koeppen and Hamilton [2008] global mineral maps and focuses on the spatial variations in solid solution chemistry among feldspars, pyroxenes, high silica phases (e.g., silica, phyllosilicates, zeolites), and sulfates. Koeppen and Hamilton [2008] demonstrated that there is a range of Mg-Fe olivine compositions on Mars and that there are distinct geographic distributions of those phases, pointing to spatial variations in geologic processes. We use the same methodology to search for correlations between geography (e.g., geologic unit, latitude), elevation, and chemical (solid solution) composition. Preliminary analyses of pyroxene chemical variation reveal that globally, low-Ca pyroxenes are dominated by the clinopyroxene pigeonite and that among orthopyroxenes, Mg-rich phases (enstatite) are virtually never identified and phases with greater proportions of Fe (bronzite and hypersthene) are identified in distinct geographic and/or geologic terrains. Only the distribution of hypersthene (the composition of pyroxene in the Martian meteorite ALH 84001) correlates with the OMEGA-mapped distribution of low-Ca pyroxene suggesting that OMEGA-based maps of high-Ca pyroxene may include pigeonite. Many of the chemical-spatial variations observed among solid solution phases in TES data correspond to both relative surface age and the distribution of lithologic units identified by Rogers and Christensen [2007, JGR-Planets], where the lithologic units were identified using a different analytical approach, giving us confidence in the variations observed in our mineral maps. These results point to variations in and/or the evolution of igneous compositions over time. Any observable variations in other phase groups (e.g., sulfates, phyllosilicates) may indicate variations in the timing and extent of aqueous or alteration processes over time.

Hamilton, V. E.; Rogers, D.

2010-12-01

374

Search for quark compositeness in dijet angular distributions from pp collisions at sqrt(s) = 7 TeV  

SciTech Connect

A search for quark compositeness using dijet angular distributions from pp collisions at sqrt(s) = 7 TeV is presented. The search has been carried out using a data sample corresponding to an integrated luminosity of 2.2 inverse femtobarns, recorded by the CMS experiment at the LHC. Normalized dijet angular distributions have been measured for dijet invariant masses from 0.4 TeV to above 3 TeV and compared with a variety of contact interaction models, including those which take into account the effects of next-to-leading-order QCD corrections. The data are found to be in agreement with the predictions of perturbative QCD, and lower limits are obtained on the contact interaction scale, ranging from 7.5 up to 14.5 TeV at 95% confidence level.

Chatrchyan, Serguei; et al.

2012-05-01

375

Search for quark compositeness in dijet angular distributions from pp collisions at sqrt(s) = 7 TeV  

E-print Network

A search for quark compositeness using dijet angular distributions from pp collisions at sqrt(s) = 7 TeV is presented. The search has been carried out using a data sample corresponding to an integrated luminosity of 2.2 inverse femtobarns, recorded by the CMS experiment at the LHC. Normalized dijet angular distributions have been measured for dijet invariant masses from 0.4 TeV to above 3 TeV and compared with a variety of contact interaction models, including those which take into account the effects of next-to-leading-order QCD corrections. The data are found to be in agreement with the predictions of perturbative QCD, and lower limits are obtained on the contact interaction scale, ranging from 7.5 up to 14.5 TeV at 95% confidence level.

CMS Collaboration

2014-07-27

376

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.

377

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

PubMed

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. PMID:12807140

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

2002-01-01

378

Distributions, speciation and stable isotope composition of organic matter in the southeastern Bering Sea  

Microsoft Academic Search

Seawater samples were collected from the southeastern Bering Sea for determinations of dissolved (DOC, 0.7 ?m), dissolved organic nitrogen (DON), particulate nitrogen (PN), and dissolved carbohydrate (DCHO) species, as well as stable isotopic composition (?13C and ?15N) of suspended particulate organic matter (POM). DOC concentrations ranged from 61 to 92 ?M (average 76±9 ?M) with increasing concentrations from outer shelf

Laodong Guo; Tomoyuki Tanaka; Deli Wang; Noriyuki Tanaka; Akihiko Murata

2004-01-01

379

Characterization of Self-Healing Fiber-Reinforced Polymer-Matrix Composite with Distributed Damage  

Microsoft Academic Search

Th.e objective ofthis manuscript is to describe experimental work that quantifies the damage and self-healing behav­ ior of fiber-reinforced, polymer-matrix, laminated composites. The effects of damage and healing on stiffness and strength are described. While previous research looks at healing of macro-cracks, this work studies the healing of micro-cracks. Therefore, this work quantifies the effect of damage and self-healing within

Ever J. Barbero; Kevin J. Ford

380

Global distribution, composition, and abundance of olivine on the surface of Mars from thermal infrared data  

Microsoft Academic Search

We used spectral indexing and linear deconvolution to compare thermal infrared emission spectra of Fo91, Fo68, Fo53, Fo39, Fo18, and Fo1 olivine samples to Mars Global Surveyor Thermal Emission Spectrometer (TES) data over low-albedo regions of Mars. The Fo91, Fo68, Fo53, and Fo39 spectral end-members were confidently identified on Mars, a range of compositions wider than inferred from Martian meteorites.

William C. Koeppen; Victoria E. Hamilton

2008-01-01

381

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

382

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

383

Silicon and oxygen charge state distributions and relative abundances in the solar wind measured by SWICS on Ulysses. [Solar Wind Ion Composition Spectrometer  

NASA Technical Reports Server (NTRS)

We report an initial survey of solar wind silicon and oxygen using data obtained with the Ulysses Solar Wind Ion Composition Spectrometer. In this study, the O(+7)/O(+6) ratio is used to group silicon counts accumulated over a two month period. Results on Si charge state distributions, relative Si/O abundances, and associated proton kinetic temperature and speed distributions are presented.

Galvin, A. B.; Ipavich, F. M.; Gloeckler, G.; Von Steiger, R.; Wilken, B.

1992-01-01

384

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

385

Simplified Shear Solution for Determination of the Shear Stress Distribution in a Composite Panel from the Applied Shear Resultant  

NASA Technical Reports Server (NTRS)

The simplified shear solution method is presented for approximating the through-thickness shear stress distribution within a composite laminate or panel based on laminated beam theory. The method does not consider the solution of a particular boundary value problem; rather it requires only knowledge of the global shear loading, geometry, and material properties of the laminate or panel. It is thus analogous to lamination theory in that ply level stresses can be efficiently determined from global load resultants (as determined, for instance, by finite element analysis) at a given location in a structure and used to evaluate the margin of safety on a ply by ply basis. The simplified shear solution stress distribution is zero at free surfaces, continuous at ply boundaries, and integrates to the applied shear load. Comparisons to existing theories are made for a variety of laminates, and design examples are provided illustrating the use of the method for determining through-thickness shear stress margins in several types of composite panels and in the context of a finite element structural analysis.

Bednarcyk, Brett A.; Aboudi, Jacob; Yarrington, Phillip W.; Collier, Craig S.

2008-01-01

386

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 ...

387

ALUMINUM-CONTAINING SCALES IN WATER DISTRIBUTION SYSTEMS: PREVALENCE AND COMPOSITION  

EPA Science Inventory

Aluminum (Al) deposits in distribution systems can have important detrimental effects on tap water quality because they can increase turbidity and interfere with disinfection, and they can increase energy loss during water transport. There is also the possibility that they have ...

388

Distribution, composition and seasonality of aquatic birds in the Nhecolândia sub-region of South Pantanal, Brazil.  

PubMed

Despite remarkable significance of Pantanal for the conservation of aquatic birds, the status of their populations, the spatiotemporal patterns of distribution and habitat use and structure of communities are little known. Thus, we studied three aquatic environments (Negro river, bays and salines) from 2007 to 2009 in the Nhecolândia Pantanal to verify the distribution and composition of aquatic birds and also if there is significant seasonal influence on these aspects. We adopted the transect method (288 hours of sampling) and recorded 135 species (7.834 individuals). The Negro river showed the highest diversity, while the salines the lowest. The similarity of aquatic bird communities was higher between bays and salines, followed by Negro river and bays and lower between salines and Negro river. The equidistribution is more variable in the salines and more stable in the Negro river. The environments strongly differ from each other in aquatic bird composition in space (habitat use and distribution) and time (seasonal water fluctuations). The diversity of bird community in the dry season varies significantly in the salines, followed by the bays and more stable in the Negro river. The Negro river, regardless of large annual amplitude of flow, is more seasonally stable since its riparian vegetation is continuous (not isolated) and constant. These aspects provide better conditions to stay all year, contributing to decrease the seasonal nomadic tendencies of aquatic birds. Finally, all these data provide strong arguments to the preservation of all phytophysiognomies in the Nhecolândia sub- region of Pantanal, but with special attention to the salines widely used by many flocks of aquatic birds (mainly in the dry season) and migrant and/or rare species restricted to this habitat. PMID:25627594

Donatelli, R J; Posso, S R; Toledo, M C B

2014-11-01

389

Fatigue properties of jointed wood composites Part I Statistical analysis, fatigue master curves and constant life diagrams  

Microsoft Academic Search

The primary aim of this work was to assess the fatigue performance of scarf-jointed laminated wood composites used to manufacture wind turbine blades and establish simple fatigue design procedures. Laminates made from poplar (Populus canadensis\\/serotina), Khaya (Khaya ivorensis) and beech (Fagus sylvatica), incorporating typical scarf joints, were assessed under reversed loading (R =-1). Scarf joints were found to be great

I. P. Bond; M. P. Ansell

1998-01-01

390

Salp distribution and size composition in the Atlantic sector of the Southern Ocean  

NASA Astrophysics Data System (ADS)

Salp abundance and length frequency were measured during the large-scale CCAMLR 2000 Survey conducted in the Atlantic Sector of the Southern Ocean in the 1999/2000 season. Results from regional surveys around Elephant Island in 1994/95 and 1996/97 seasons also were examined. During the CCAMLR 2000 Survey, salp abundance was higher in the Antarctic Peninsula and South Sandwich Island areas than in the central Scotia Sea. The probable reason for this pattern is a negative relationship with phytoplankton abundance; the central Scotia Sea having greater phytoplankton concentrations than required for optimal salp filter-feeding performance. Cluster analysis of salp size composition resulted in three cluster groups for each of the three surveys. Clusters comprising large salps occurred in warmer waters in all three surveys. The size composition of the salp populations suggests that the timing of intense asexual reproductive budding was earlier in warmer waters. As surface water temperatures generally decrease from north to south, and increase from spring to summer, the general spatio-temporal pattern of asexual reproduction by budding is likely to proceed from north to south as the summer season progresses.

Kawaguchi, S.; Siegel, V.; Litvinov, F.; Loeb, V.; Watkins, J.

2004-06-01

391

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

392

Cr-pyrope garnets in the lithospheric mantle 2. Compositional populations and their distribution in time and space  

NASA Astrophysics Data System (ADS)

Three novel statistical approaches (Cluster Analysis by Regressive Partitioning [CARP], Patient Rule Induction Method [PRIM], and ModeMap) have been used to define compositional populations within a large database (n > 13,000) of Cr-pyrope garnets from the subcontinental lithospheric mantle (SCLM). The variables used are the major oxides and proton-microprobe data for Zn, Ga, Sr, Y, and Zr. Because the rules defining these populations (classes) are expressed in simple compositional variables, they are easily applied to new samples and other databases. The classes defined by the three methods show strong similarities and correlations, suggesting that they are statistically meaningful. The geological significance of the classes has been tested by classifying garnets from 184 mantle-derived peridotite xenoliths and from a smaller database (n > 5400) of garnets analyzed for >20 trace elements by laser ablation microprobe-inductively coupled plasma-mass spectrometry (LAM-ICPMS). The relative abundances of these classes in the lithospheric mantle vary widely across different tectonic settings, and some classes are absent or very rare in either Archean or Phanerozoic SCLM. Their distribution with depth also varies widely within individual lithospheric sections and between different sections of similar tectonothermal age. These garnet classes therefore are a useful tool for mapping the geology of the SCLM. Archean SCLM sections show high degrees of depletion and varying degrees of metasomatism, and they are commonly strongly layered. Several Proterozoic SCLM sections show a concentration of more depleted material near their base, grading upward into more fertile lherzolites. The distribution of garnet classes reflecting low-T phlogopite-related metasomatism and high-T melt-related metasomatism suggests that many of these Proterozoic SCLM sections consist of strongly metasomatized Archean SCLM. The garnet-facies SCLM beneath Phanerozoic terrains is only mildly depleted relative to Primitive Upper Mantle (PUM) compositions. These data emphasize the secular evolution of SCLM composition defined earlier [Griffin et al., 1998, 1999a] and suggest that at least part of this evolutionary trend reflects reworking and refertilization of SCLM formed in the Archean time.

Griffin, W. L.; Fisher, N. I.; Friedman, J. H.; O'Reilly, Suzanne Y.; Ryan, C. G.

2002-12-01

393

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

394

Atmospheric Neutral Analyzer for In-Situ Neutral Mass Composition and Velocity Distribution Measurements in Ionosphere-Thermosphere Coupling Studies  

NASA Astrophysics Data System (ADS)

The atmospheric neutral analyzer (ANA) is a new instrument for measuring in-situ the mass composition and velocity distributions of neutrals in the upper atmosphere. It combines radio frequency (RF) mass analysis and charge-coupled device (CCD) particle imaging to provide images of detailed two-dimensional velocity distribution functions of individual mass species. It comprises an entrance aperture (EA), electron source (ES), ion accelerator (IA), RF ion mass analyzer (MA), and an imaging particle detector (PD). The EA permits neutrals to enter the analyzer but inhibits ion and electron entry. The ES ionizes a collimated fraction of the incident neutral particles while preserving their velocities. The IA accelerates all ionized neutrals to a fixed energy in the perpendicular direction to the entrance aperture plane. The MA further accelerates those of a specific velocity (and hence mass) for detection, using an RF electric field of specific amplitude and frequency. In the imaging PD, the detected ions produce charges on the surface of a micro-channel plate 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. We present the design of ANA and discuss its development in preparation for flight in ionosphere-thermosphere missions.

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

395

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

396

Composition, Physiochemical Properties, Nitrogen Fraction Distribution, and Amino Acid Profile of Donkey Milk  

Microsoft Academic Search

This study investigated the changes in chemical com- position, nitrogen fraction distribution, and AA profile of milk samples obtained during lactation from the Ji- angyue 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

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

2007-01-01

397

Spatial distributions of ultrafine particles and their behavior and chemical composition in relation to roadside sources  

Microsoft Academic Search

Vertical and horizontal distributions of the chemical components of ultrafine particles (UFP; <0.1?m) in relation to roadside sources were investigated by using a newly developed PM0.1 collection system with a UFP impactor filter (50% cut-off, 0.1?m; air flow rate, 40.0Lmin?1). UFP were measured at a suburban roadside, at two background sites in Saitama (summer 2007 and winter 2008), and at

Shinji Kudo; Kazuhiko Sekiguchi; Kyung Hwan Kim; Kazuhiko Sakamoto

2011-01-01

398

Composition and fatty acid distribution of bovine milk phospholipids from processed milk products  

PubMed Central

The aim of this work was to assess the accuracy of different extraction methods of phospholipids and to measure the effect that processing has on phospholipid composition. Four methods of extracting phospholipids from buttermilk powder were compared to optimize recovery of sphingomyelin. Using the optimal method, the phospholipid profile of four dairy products (raw milk, raw cream, homogenized and pasteurized milk, and buttermilk powder) was determined. A total lipid extraction by the Folch method followed by a solid-phase extraction using the Bitman method was the most efficient technique to recover milk sphingomyelin. Milk processing (churning, centrifuging, homogenization, spray-drying) affected the profile of milk phospholipids, leading to a loss of sphingomyelin and phosphatidylcholine after centrifugation for cream separation. We also observed a corresponding decrease in the saturation content of the raw cream phospholipids, and a loss of phosphatidylethanolamine after spray-drying to produce buttermilk powder. PMID:20828196

Gallier, Sophie; Gragson, Derek; Cabral, Charles; Jiménez-Flores, Rafael; Everett, David W.

2014-01-01

399

Composition and fatty acid distribution of bovine milk phospholipids from processed milk products.  

PubMed

The aim of this work was to assess the accuracy of different extraction methods of phospholipids and to measure the effect that processing has on phospholipid composition. Four methods of extracting phospholipids from buttermilk powder were compared to optimize recovery of sphingomyelin. Using the optimal method, the phospholipid profile of four dairy products (raw milk, raw cream, homogenized and pasteurized milk, and buttermilk powder) was determined. A total lipid extraction by the Folch method followed by a solid-phase extraction using the Bitman method was the most efficient technique to recover milk sphingomyelin. Milk processing (churning, centrifuging, homogenization, spray-drying) affected the profile of milk phospholipids, leading to a loss of sphingomyelin and phosphatidylcholine after centrifugation for cream separation. A corresponding decrease in the saturation content of the raw cream phospholipids and a loss of phosphatidylethanolamine after spray-drying to produce buttermilk powder were also observed. PMID:20828196

Gallier, Sophie; Gragson, Derek; Cabral, Charles; Jiménez-Flores, Rafael; Everett, David W

2010-10-13

400

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

401

Top-down control of soil fungal community composition by a globally distributed keystone consumer.  

PubMed

The relative contribution of top-down and bottom-up processes regulating primary decomposers can influence the strength of the link between the soil animal community and ecosystem functioning. Although soil bacterial communities are regulated by bottom-up and top-down processes, the latter are considered to be less important in structuring the diversity and functioning of fungal-dominated ecosystems. Despite the huge diversity of mycophagous (fungal-feeding) soil fauna, and their potential to reverse the outcomes of competitive fungal interactions, top-down grazing effects have never been found to translate to community-level changes. We constructed soil mesocosms to investigate the potential of isopods grazing on cord-forming basidiomycete fungi to influence the community composition and functioning of a complex woodland soil microbial community. Using metagenomic sequencing we provide conclusive evidence of direct top-down control at the community scale in fungal-dominated woodland soil. By suppressing the dominant cord-forming basidiomycete fungi, isopods prevented the competitive exclusion of surrounding litter fungi, increasing diversity in a community containing several hundred fungal species. This isopod-induced modification of community composition drove a shift in the soil enzyme profile, and led to a restructuring of the wider mycophagous invertebrate community. We highlight characteristics of different soil ecosystems that will give rise to such top-down control. Given the ubiquity of isopods and basidiomycete fungi in temperate and boreal woodland ecosystems, such top-down community control could be of widespread significance for global carbon and nutrient cycling. PMID:24400503

Crowther, Thomas W; Stanton, David W G; Thomas, Stephen M; A'Bear, A Donald; Hiscox, Jennifer; Jones, T Hefin; Vorísková, Jana; Baldrian, Petr; Boddy, Lynne

2013-11-01

402

Shallow-water Mysida (Crustacea: Mysidacea) of Bahrain (Arabian Gulf): species composition, abundance and life history characteristics of selected species  

Microsoft Academic Search

Mysida were collected from Tubli Bay and the eastern coastline of Bahrain during 1991–1992 incidental to a survey of penaeid prawns. These samples provided an opportunity to assess the species composition of mysids from a nearshore region of the Arabian Gulf—an area in which mysid fauna is poorly known. The 114 beam trawl samples yielded >29?000 mysids. Rhopalophthalmus sp. (>90%),

Stephen A. Grabe; W. Wayne Price; Ebrahim A. A. Abdulqader; Richard W. Heard Jr

2004-01-01

403

Setting the pace of life: membrane composition of flight muscle varies with metabolic rate of hovering orchid bees.  

PubMed

Patterns of metabolic rate variation have been documented extensively in animals, but their functional basis remains elusive. The membrane pacemaker hypothesis proposes that the relative abundance of polyunsaturated fatty acids in membrane phospholipids sets the metabolic rate of organisms. Using species of tropical orchid bees spanning a 16-fold range in body size, we show that the flight muscles of smaller bees have more linoleate (%18 : 3) and stearate (%18 : 0), but less oleate (%18 : 1). More importantly, flight metabolic rate (FlightMR) varies with the relative abundance of 18 : 3 according to the predictions of the membrane pacemaker hypothesis. Although this relationship was found across large differences in metabolic rate, a direct association could not be detected when taking phylogeny and body mass into account. Higher FlightMR, however, was related to lower %16 : 0, independent of phylogeny and body mass. Therefore, this study shows that flight muscle membrane composition plays a significant role in explaining diversity in FlightMR, but that body mass and phylogeny are other factors contributing to their variation. Multiple factors are at play to modulate metabolic capacity, and changing membrane composition can have gradual and stepwise effects to achieve a new range of metabolic rates. Orchid bees illustrate the correlated evolution between membrane composition and metabolic rate, supporting the functional link proposed in the membrane pacemaker hypothesis. PMID:25652831

Rodríguez, Enrique; Weber, Jean-Michel; Pagé, Benoît; Roubik, David W; Suarez, Raul K; Darveau, Charles-A

2015-03-01

404

Mass-spectrometric method for signs of life search via analysis of the element composition of the supposed biomass extracted from regolith of Mars  

NASA Astrophysics Data System (ADS)

A mass-spectrometric method for identifying signs of life in a sample extracted from regolith of extraterrestrial objects is presented. The structure and composition of a laboratory prototype of an onboard measurement facility addressing the assigned astrobiological task is analyzed. The instrument proposed can be used to analyze the element composition of the supposed extraterrestrial biomass and compare it to the element composition of terrestrial microorganisms. Biomass is to be identified by a number of criteria: the presence and abundance ratio of matrix biogenic elements - H, C, N, O; abundance ratios of biogenic markers like P/S, K/Ca, the presence of other biologically important elements (e.g., Cl) and microelements, such as Mg, Fe, Cu, Zn, and F. The results of measurements performed on microorganisms and soil samples confirm the applicability of this solution. Various methods of extracting the biomass from different space bodies are discussed. The element composition of the sample studied is to be performed using the onboard LASMA time-of-flight laser mass-reflectron similar to the instrument developed for the «Phobos-Grunt» mission however after significant improvement. The system of sample preparation is based on the separation of the microorganisms from regolith. After extraction of microorganisms with water the solution obtained must be desalted. Sample for investigation is produced by drying the solution on the holder being the target for laser ablation. The method can be used to search for and identify biomass in different samples including ice retrieved from the subsurface layer of Solar-System planets or satellites, e.g., Europa or Enceladus.

Luchnikov, Konstantin; Managadze, George; Chumikov, Alexander; Managadze, Nina; Vorobyova, Elena; Safronova, Anastasia

405

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

406

Spatial distribution of the upside-down jellyfish Cassiopea sp. within fringing coral reef environments of the Northern Red Sea: implications for its life cycle  

Microsoft Academic Search

The zooxanthellate mangrove jellyfish Cassiopea sp. represents a prominent invasive species and a potential bioindicator for nutrient monitoring in coral reefs. However,\\u000a information about its spatial distribution in combination with abundance, habitat specificity and life cycle elements is barely\\u000a available. This study, therefore, presents the results of field surveys conducted within four different benthic habitat types\\u000a (coral reef, seagrass meadow,

Wolfgang Niggl; Christian Wild

2010-01-01

407

Distribution of Traumatic and Other Stressful Life Events by Race\\/Ethnicity, Gender, SES and Age: A Review of the Research  

Microsoft Academic Search

Much research has shown that reports of stressful life events are related to a wide variety of psychiatric and physical health\\u000a outcomes. Relatively little research exists, however, on the distribution of the events according to gender, age, racial\\/ethnic\\u000a background, and socioeconomic status (SES). Such information would help identify groups at greatest risk for further investigation.\\u000a This paper presents a review

Stephani L. Hatch; Bruce P. Dohrenwend

2007-01-01

408

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

409

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

410

Strength distribution and size effects for the fracture of fibrous composite materials  

SciTech Connect

Random network models have recently been developed in the physics literature to explain the strength and size effect in heterogeneous materials. Applications have included the breakdown and brittle fracture. Unfortunately, conventional scaling approaches of statistical mechanics have yielded incorrect predictions, and new approaches have been proposed which build on field enhancement occurring near the tips of critical, random clusters together with the statistical theory of extremes. New distributions and size scalings for strength have been proposed and supported through Monte Carlo simulation. Here we consider an idealized, one-dimensional model for the failure of such networks where elements of constant strength may be initially present or absent at random. Our idealized rule for local stress redistribution near breaks reflects features we find in a discrete mechanics model that has limiting forms consistent with continuum theories for cracks. We obtain rigorous asymptotic results for the strength distribution and size effect with constants and exponents that are known. The validity of various analytical approximations in the literature is then discussed.

Phoenix, S.L. [Cornell Univ., Ithaca, NY (United States). Dept. of Theoretical and Applied Mechanics; Beyerlein, I.J. [Los Alamos National Lab., NM (United States)

1997-10-01

411

Cytoplasmic annulate lamellae in cultured cells: composition, distribution, and mitotic behavior.  

PubMed

We have used antibodies against different proteins of the nuclear pore complex to identify cytoplasmic annulate lamellae by immunocytochemistry at the light- and electron-microscopic level in various lines of cultured mammalian cells. Although annulate lamellae (AL) are seldom observed in some cell lines, they occur in large numbers in other lineages, also with cell-type-specific size distributions. AL are especially abundant and prominent in African green monkey kidney epithelial cells of line RC37 and bovine mammary gland epithelial, cells of line BMGE. We have studied the distribution of AL in relation to other organelles by using double-label immunofluorescence microscopy and have demonstrated a significant relationship between AL and rough endoplasmic reticulum. We have further shown that AL are disassembled during prophase and reassembled at the end of mitosis, almost concomitantly with the disassembly and reassembly of the nuclear envelope. Cultured mammalian cells that are rich in AL can therefore be used as suitable models for studies of the biogenesis of these lamellae, which can conveniently be detected by immunofluorescence microscopy. PMID:8625385

Cordes, V C; Reidenbach, S; Franke, W W

1996-05-01

412

Airborne brake wear debris: size distributions, composition, and a comparison of dynamometer and vehicle tests.  

PubMed

Particle size distributions of light-duty vehicle brake wear debris are reported with careful attention paid to avoid sampling biases. Electrical low-pressure impactor and micro-orifice uniform deposit impactor measurements yield consistent size distributions, and the net particulate matter mass from each method is in good agreement with gravimetric filter measurements. The mass mean diameter of wear debris from braking events representative of urban driving is 6 microm, and the number-weighted mean is 1-2 microm for three currently used classes of lining materials: low metallic, semimetallic, and non-asbestos organic (NAO). In contrast, the wear rates are very material dependent, both in number and mass of particles, with 3-4 times higher emissions observed from the low metallic linings as compared to the semimetallic and NAO linings. Wind tunnel and test track measurements demonstrate the appearance of micron size particles that correlate with braking events, with approximately 50% of the wear debris being airborne for the test vehicle in this study. Elemental analysis of the wear debris reveals a consistent presence of the elements Fe, Cu, and Ba in both dynamometer and test track samples. PMID:14524436

Sanders, Paul G; Xu, Ning; Dalka, Tom M; Maricq, M Matti

2003-09-15

413

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